点阵LED外文文献+翻译
LED点阵书写显示屏
LED点阵书写显示屏摘要本设计运用了基于 Nios II 嵌入式处理器的 SOPC 技术。
系统以 ALTERA 公司的 Cyclone II 系列 FPGA 为数字平台，将微处理器、Avalon 总线、LED 点阵扫描控制器、存储器和人机接口控制器等硬件设备集中在一片 FPGA 上，利用片内硬件来实现 LED 点阵的带地址扫描，降低系统总功耗和简化 CPU 编程的同时，提高了系统的精确度、稳定性和抗干扰性能。
关键词：SOPC FPGA 带地址扫描AbstractThis design using the Nios II based on embedded processor SOPC technology.ALTERA system to the company for the Cyclone II FPGA digital platform、 series、Will microprocessor、 Avalon bus of LED dot matrix scanning controller、memory and human-computer interface controller hardware device focused on such a FPGA,Using the piece of hardware to achieve inside of LED dot matrix with address scanning, reduce the total power of the programming and simplify the CPU, improve the precision and stability of the system and the anti-jamming performance.Keyword: SOPC FPGA Address scanning１目录1 引言 (3)2 系统方案 (3)2.1主控器选择方案论证 (3)2.2点阵驱动方案论证 (3)3 理论分析与计算 (4)3.1 光笔选取与参数设计 (5)3.2 LED点阵屏驱动参数设计........................................ (5)3.3 屏亮自动调节设计 (6)3.4 超时关显示节电设计 (6)4 系统电路设计 (7)4.1 系统工作原理 (7)4.2 系统工作时序 (7)5 系统程序设计 (8)5.1 系统流程概述 (8)5.2系统总流程图 (8)6 系统测试与结果 (9)7 结论 (9)参考文献 (10)附录: (10)附1:电路原理图 (10)附2:扫描电路硬件描述 (11)附2:软核NIOS II程序 (17)附4:完整的测试结果 (47)２1 引言LED点阵显示屏被用到很多领域，随着电子技术的发展，LED点阵书写显示屏的广泛应用是一种趋势。
关于LED的外文文献和中文译文
多个LED发光装置的新型采集系统作为光源的一种，发光二极管（LED）有很多优点。
LED集成度更高，颜色种类多，使用寿命更长，而且工作电压较低。
但是，它仍有一个非常大的缺陷：一只LED的光照强度还是比较低。
这个缺点导致显示屏上的光通量不会很高。
但是无论如何，LED还是以其出色的性能在低电压装置中普遍应用。
因此，利用此系统采集多个LED的光，集成为更高强度的照明装置。
本设计提出三种采集系统，来实现增强光强的功能。
效率最好的一种采集系统可以达到96%。
同时，还分析了本系统的制造误差以及预算。
1 简介利用传统的光源来设计一个便携式探照灯，尺寸和能耗会很大。
而利用LED 来设计将会避免这些问题。
LED有很多优点：节能、体积较小、使用寿命长（约100,103小时）等，尤其是LED的光很适合环境工作。
Carel Zeiss和Philips打算用LED光源设计两种便携式探照灯。
尽管LED有诸多优点，可以让他们设计出的探照灯更加便携和小巧，但是由于光学元件的转换效率问题，导致系统有很多困难。
解决这个困难将是本文研究的重点。
通常，用一种合成非线性集中器（CPC）来减小分散度。
但是，这种传统的CPC采集效率仅为72%，必须要改善采集效率来提高光的利用率。
本文中将解决分散度和采集效率两个问题。
为实现这个目标，设计了三种不同的采集系统，以提高效率，下面逐一介绍。
2 仿真部分利用光学仿真软件和标签查找模块（BRO），来设计并分析采集系统的性能。
LED光源部分来自Osram-Opical半导体。
远程LED光源是一种Lambertian模式，LED的规格见表1。
在采集系统的底部有四个LED。
系统各个LED之间的位置关系如图1。
通光部分为2.1×2.1mm2，孔径3.26mm。
LED阵列对称的分布于系统的底部。
采集系统的第一个光学元件为均质器。
这个均质器的受光角度是12.5°。
因此，这个系统就是要把LED的受光角度的范围控制在±60°到±12.5°之间。
led点阵显示原理
led点阵显示原理LED点阵显示原理。
LED点阵是一种常见的显示设备，它由许多小的LED灯组成，可以显示数字、字母、符号等信息。
它在各种电子产品中广泛应用，如电子钟、电子表、电子游戏机等。
那么，LED点阵显示的原理是什么呢？首先，我们来了解一下LED的基本原理。
LED全称为“Light Emitting Diode”，即发光二极管。
它是一种半导体器件，具有正向导通特性，当正向电压施加到LED两端时，电子和空穴在PN结复合，释放出能量，产生光。
LED点阵就是将许多这样的LED灯排列在一起，通过控制不同的LED灯点亮或熄灭，从而显示出所需的图形或文字。
LED点阵的显示原理可以分为两部分，控制和驱动。
首先是控制部分。
LED点阵的控制通常采用行列扫描的方式。
即将LED按行和列的方式排列，通过控制各行和列的电平信号来控制LED的点亮和熄灭。
控制部分通常由微控制器或者专门的LED控制芯片来实现，通过发送相应的控制信号来控制LED点阵的显示。
其次是驱动部分。
LED点阵的驱动通常采用常流驱动的方式。
LED是一种电流驱动的器件，为了保证LED的亮度稳定，需要对LED施加恒定的电流。
因此，在LED点阵的驱动电路中通常会加入恒流源，以保证LED的亮度稳定。
此外，还需要考虑LED的正向电压和功率等参数，来设计合适的驱动电路。
除了控制和驱动，LED点阵的显示原理还涉及到LED的亮度和色彩控制。
LED的亮度可以通过控制LED的通电时间来实现，即通过调节LED的占空比来控制LED的亮度。
而LED的色彩控制则需要使用不同颜色的LED，并通过控制不同颜色LED的点亮组合来实现。
总的来说，LED点阵显示的原理是通过控制和驱动LED点阵中的各个LED灯，来实现所需的图形或文字显示。
控制部分通过行列扫描的方式来控制LED的点亮和熄灭，驱动部分采用常流驱动的方式来保证LED的亮度稳定，同时还需要考虑LED的亮度和色彩控制。
LED点阵显示原理的了解对于电子产品的设计和应用具有重要意义，希望本文能够帮助大家更好地理解LED点阵显示的原理和应用。
LED点阵的外文翻译---纳米结构InGaN发光Diodesfor固态照明
（要求翻译与毕业设计（论文）相关的外文文献两篇，且3000单词以上/ 篇，将译文附在原文之后）第一篇：[ 所译外文资料：①作者：Taeil Jung②书名（或论文题目）：Nano-structured InGaN Light-Emitting Diodesfor Solid-State Lighting③出版社（或刊物名称或可获得地址）：All Rights Reserved.④出版时间（或卷期号）：2009.⑤所译起止页码：Nano-structured InGaN Light-Emitting Diodesfor Solid-State LightingSolid-state lighting can potentially reduce the electricity consumption by 25%. It requires high efficiency light-emitting diodes across the visible spectrum. GaN and related materials have direct band gap across the entire visible spectrum and are ideal for future solid-state lighting applications. However, materials defects, polarization charges, and total internal reflection have thus far limited the efficiencies of InGaN LEDs, in particular InGaN LEDs in the green/yellow wavelength range, which are critical in achieving highly efficient LED luminaries with an excellent color-rendering indexIn this Thesis, we have developed and demonstrated that novel in situ nanostructured GaN processes in MOCVD are effective in improving the efficiencies of InGaN LEDs. InGaN LEDs grown on quasi-planar semi-polar GaN templates were proven to exhibit three times higher internal quantum efficiencies and negligible quantum confined Stark effect using selective area epitaxy. InGaN LEDs grown on nanostructured semi-polar GaN templates are also effective to improve the internal quantum efficiency by 31%. The same in situ processes are also effective in reducing the defect density by an order of magnitude and increasing the photon extraction efficiency as a factor of two.The in situ processes include in situ silane treatment and high temperature overgrowth. Both processes require only standard MOCVD tools and hence are cost effective and suitable for mass-production. In situ silane treatment treatsc-plane GaN samples with silane under ammonia environment, generating nano-scale truncated cone structures with up to 200 nm scale. These truncated cone structures can be subsequently transformed into pyramidal nanostructures comprising of only (10-11) and (11-22) semipolar planes using high temperature overgrowth. These processes were applied to both InGaN active region and the LED surface to improve the internal quantum efficiency and the photon extraction efficiency, respectively. Extensive materials, device, and optical characterizations have been carried out in this research.1.1 Gallium Nitride Materials for Optoelectronic ApplicationsGallium nitride based materials, including GaN, AlN, InN, and their alloys, are excellent candidates for short-wavelength optoelectronic applications. Their direct bandgaps extend from ultraviolet to near-infrared. In addition, they exhibit high mechanical and thermal stabilities compared to other III-Vsemi-conductors, making them especially suitable for high-power andhigh-temperature operations. In recent years, breakthroughs in p-type doping and defect reduction have led to the commercialization of GaN based laser diodes, light-emitting diodes (LEDs), high electron mobility transistors (HEMT) and hydrogen detectors. Despite these advances, many technological challenges such as green gap and substrate growths still remain.Perhaps one of the most important applications for GaN based materials is solidstate lighting (SSL). Worldwide, lighting constitutes 20% of electricity consumption while its efficiency is much lower than 25%. In contrast, efficiency of space heating has exceeded 90%. To this end, the development of highly efficient and reliable LEDs for solid-state lighting has been very active in both industry and academia in the past few years. It is projected by the US Department of Energy that by 2015, if successful, solidstate lighting can reduce the overall electricity consumption by 25%.Unlike GaAs and InP based semi-conductors, GaN based materials have suffered from a high density of defects due to very limited availability of lattice-matched GaN substrates. Up to now, most GaN based optoelectronic devices have been fabricated using hetero-epitaxy on foreign substrates such as sapphire (Al2O3), silicon carbide (SiC), and aluminum nitride (AlN), and in a very small percentage on silicon. Because of large lattice mismatch, GaN grown on these substrates often exhibits a high density of threading dislocations, typically on the order of 108 – 1010 /cm2. These defects are still one of the major limiting factors for the performance of GaN based optoelectronic devices, acting as non-radiative recombination and scattering centers. Achievement of lower defect density would also improve device reliability, resulting in a longer lifetime. Various defect reduction approaches, such as epitaxial lateral over-growth (ELOG), have been demonstrated and some of the details will be discussed in Chap.1.3.1. As part of this thesis, we have explored a novel approach to using nano-structured GaN to effectively lower the threading dislocation density.Among various epitaxial techniques that have been developed for GaN based materials, metal-organic chemical vapor deposition (MOCVD) is the leading technology. The typical growth temperature for GaN materials is around 1000 to 1200°C. This high growth temperature is necessary to improve the crystal quality and is a result of low cracking efficiency of the nitrogen source, ammonia (NH3), at a low temperature. In Chapter 2, I will summarize my contributions to successfully ramp up an MOCVD tool for the epitaxial growth of GaN LEDs for this research.1.2 InGaN LEDs for Solid-State LightingThe basic component for SSL is a white-light LED. As shown in Figure 1-1, itcan be achieved by mixing various color components, which can be generated either from the direct output of individual LEDs or from color-conversion materials, such as phosphor. To date, commercially available white-light LEDs usually consist of a blue emitter and a yellow phosphor plate. It has been shown that InGaN based blue LEDs could achieve external quantum efficiency in excess of 70% [1, 2]. However, this di-chromatic configuration typically has a poor color rendering index due to the lack of green and red components. The phosphor conversion process also limits the overall luminous efficiency due to energy loss during downconversion. To achieve luminous efficiency in excess of 200 lm/W and a color rendering index (CRI) in excess of 90, which is required for general illumination, a further improvement in blue LED efficiency and the use of tetra-chromatic configuration (blue + green + yellow + red) is necessary [3].* Unfortunately, the efficiency of both InGaN and AlInGaP LEDs decreases significantly in the green-yellow (500 - 580 nm) range. This efficiency gap is also known as “green gap”. Because AlInGaP materials have indirect bandgaps in this wavelength range, to achieve high-efficiency SSL, it is crucial to significantly improve the luminousNote that a trichromatic (e.g. blue + green + red) source cannot achieve a CRI > 90. efficiency of green and yellow InGaN LEDs. In this thesis, we will address these challenges using nano-structured GaN.Figure 1-1. Illustration of various potential white-light LEDs configurations (after Ref. [4]).1.3Limiting Factors for InGaN LEDs EfficiencyTo date, the efficiencies of InGaN LEDs are still limited by materials defects, polarization charges, and photon trapping. In this Section, we will briefly review the state of theart and overview how this research helps address these limitations.1.3.1 Materials DefectsAs mentioned before, the high defect density in GaN based materials grown on foreignsubstrates increases the non-radiative recombination rate and lowers the radiative efficiency. To date, several techniques have been demonstrated to improve the crystal quality and reduce the threading dislocation (TD) density of the GaN layer. Substrate pretreatmentat the growth temperature in an ammonia environment, also known as nitridation [5-7], has been shown to be critical for high quality GaN epilayers. The TD density of a typical GaN layer grown on c-plane sapphire substrate can be reduced to 108/cm2 [8] by employing the combination of a low temperature (LT; 450 - 600 °C)nucleation layer (NL) and a short annealing at the growth temperature to change the phase of the as-grown NL from cubic to hexagonal [9-11]. As will be discussed in Chapter 2, careful optimization of these low temperature growth sequences can significantly alter the subsequent GaN template growth. To this end, a home-made optical in situ monitoring tool (reflectometry) was established and will be discussed extensively in Chapter 2.In addition low temperature buffer growth, epitaxial lateral overgrowth (ELOG) which is a variation of selective area epitaxy (SAE) has been introduced [12, 13] to further lower the TD density by an order of magnitude to below 107/cm2. Variations of ELOG including pendeo- (from the Latin : hang on or suspended from) epitaxy (PE) [14] and multi-step ELOG are also effective to further reduce the TD density. Additional techniques such as TiN nano-porous network [15] and anodic aluminum oxide nano-mask [16] have also been proposed and demonstrated. All these methods, however, require ex situ processing and hence will add complexity and cost to the manufacturing. In this thesis, we will explore and generalize an in situ silane treatment approach to effectively lowering the TD density by an order of magnitude.1.3.2 Polarization ChargesDue to the non-cubic symmetry of GaN materials, compressively-strained active regions in InGaN LEDs exhibit both spontaneous and piezoelectric polarization charges. These polarization charges induce a strong internal electric field (IEF), typically on the order of MV/cm, in the active region, resulting in both efficiency droop at a high injection current density and the decrease of radiative efficiency with an increasing emission wavelength. The IEF can separate electrons from holes and increase electron leakage, resulting in low internal quantum efficiency (IQE) and efficiency droop [17], respectively. The suppression of the IEF, which is expected to increase IQE and the current density at which efficiency droop occurs, can be achieved by reducing the lattice mismatch in hetero-structures or growing them on semi-polar (e.g. {10-11} and {11-22}) and non-polar (e.g. a-plane and m-plane) surfaces. Because indium incorporation is more difficult on non-polar planes than on semi-polar planes, it is more advantageous to fabricate long-wavelength green-yellow LEDs on semi-polar planes to suppress the IEF.At least three approaches to fabricating semi-polar InGaN LEDs have been reported thus far. These include the growth of a GaN epilayer on spinel substrates [18], on bulk GaN substrates [19-27], and on the sidewalls of pyramidal or ridge GaN structures created on planar polar GaN surfaces using SAE [28-35]. GaN grown on spinel substrates have so far exhibited a high density of threading dislocations and stacking faults, thereby compromising the potential improvement of efficiency from the lowering of IEF. The use of bulk semi-polar GaN substrates has demonstrated the advantage of a lower IEF for the enhanced efficiency of green and yellow LEDs [25, 26]. However, limitations such as prohibitively high wafer cost and small substrate size need to be resolved before this approach can become more practical. On the other hand, the SAE technique can create semi-polar planes on polar GaN surfaces.High quality polar GaN films have been fabricated from a variety of substrates including sapphire, 6H-SiC, and bulk GaN by MOCVD. Using growth rate anisotropy and three-dimensional growth, different semi-polar and non-polar GaN planes can be generated on c-plane GaN [13]. In Chapter 3, we will show that high quality InGaN multiple quantum wells (MQWs) which exhibit IQE as large as a factor of three compared to polar MQWs can be grown on pyramidal GaN microstructures. This approach, however, requires ex situ patterning processes and does not easily produce a planar structure for electrical contacts. In this thesis, a new semi-polar LED structure is investigated, which is enabled by a novel epitaxial nanostructure, namely the nanostructured semi-polar (NSSP) GaN, which can be fabricated directly on c-plane GaN but without the issues of the SAE technique mentioned above [36]. NSSP GaN also eliminates the issues of excessive defects for GaN grown on spinel substrates and lowers the cost of using bulk semi-polar GaN substrates. As we will show later, the surface of NSSP GaN consists of two different semi-polar planes: (10-11) and (11-22). Therefore it is expected that InGaN active regions fabricated on NSSP GaN can exhibit a low IEF, and hence much improved IQE.1.3.3 Photon ExtractionAfter photons are generated from the active region in LEDs, they need to escape the device in order to be useful. When light travels from a medium with a higher refractive index to a medium with a lower refractive index, total internal reflection (TIR) occurs at the interface. In InGaN LEDs, photons experiencing TIR at LED surfaces can be re-absorbed by the active region or trapped in the device due to a wave-guiding effect as shown in Figure 1-2. In a simple InGaN LED, only 4% of photons generated from the active region can escape from each device surface. It has been shown that surface textures on LED surfaces can greatly reduce TIR and improve photon extraction efficiency as illustrated in Figure 1-2. To date, many surface texturing techniques such as photonic crystal structures [37] and photo-electrochemical etching of GaN surfaces [38] have been introduced. Notably, the photo-electrochemical etching of nitrogen-terminated GaN surface has been successfully implemented into commercial blue LEDs [2]. However, these approaches all require additional ex situ patterning processes which add significant costs.In this thesis, we investigate an in situ process to fabricate nano-structured GaN surfaces on LEDs which effectively improves the photon extraction efficiency. Figure 1-2. Light traveling within waveguides (left) with a smooth interface and (right) with a rough interface (after [39]).1.4 Organization of the ThesisThe objective of this thesis is to investigate cost-effective nanofabrication techniques that can significantly improve the efficiency of the state-of-the-art InGaN LEDs in both blue and green/yellow ranges for high performance solid-state lighting. The organization of this thesis is as follows.In Chapter 2, a summary of the MOCVD techniques for InGaN LEDs is given. In Chapter 3, we study the dependence of InGaN LED IQE on {10-11} semi-polar planes using SAE. In Chapter 4, fabrication and characterization of novel andcost-effective nano-structured GaN templates will be described. Using in situ silane treatment (ISST) and high temperature overgrowth (HTO), the formation of nano-scale inverted cone structures and nano-structured semi-polar (NSSP) templates has been obtained. In Chapter 5, we study InGaN semi-polar LEDs based on NSSP templates. An improvement of internal quantum efficiency is demonstrated.A green semi-polar InGaN LED grown on a c-plane substrate is also demonstrated. In Chapter 6, current spreading in NSSP InGaN LEDs will be discussed. In Chapter 7, the application of ISST for theimprovement of photon extraction efficiency of an InGaN LED will be discussed. In Chapter 8, we will summarize and make suggestions for future work.2.1 Gallium Nitride GrowthAs mentioned in the Introduction, gallium nitride (GaN) and related alloys are excellent candidates for future solid-state lighting. To date, III-nitride epitaxial growth has been limited by the lack of sufficiently large single crystal substrate for homoepitaxial growth. Therefore, the growth of GaN and related materials has been largely based on hetero-epitaxy using hydride vapor phase epitaxy (HVPE), metal organic chemical vapor deposition (MOCVD), and molecular beam epitaxy (MBE). Among these techniques, MOCVD is the leading technology due to the advantages on material quality, scalability, and cost [40]. The material quality of GaN grown by MOCVD has been excellent owing to its relatively high growth temperature (1000 - 1200°C) [41, 42].To date, various substrate materials including sapphire (Al2O3), silicon carbide (SiC), and silicon have been studied for GaN growth (Table 2-1). Although GaN substrates have been recently introduced in markets through bulk material growth on foreign substrates using HVPE and laser cutting along specific crystal planes, the cost has been prohibitively high. On the other hand, GaN grown on c-plane (0001) sapphire substrate exhibits stable growth over a wide range of growth conditions despite high dislocation density at the interface between thesubstrate and epitaxial layer. In this research, I have helped ramping up an MOCVD system together with Dr. Hongbo Yu. In this Chapter, I will summarize the MOCVD technologies and defect reduction strategies for InGaN light-emitting diodes (LEDs) epitaxy that will be used throughout this Thesis.2.1.1 GaN Growth Using MOCVDDue to a large lattice mismatch between GaN and sapphire, it is important to contain the defects near the GaN/sapphire interface such that the defect density can be minimized in the device region. Such optimization is achieved using in situ reflectometry [44, 45]. A home-made reflectometry system shown in Figure 2-1 was established in our 3 x 2” Thomas-Swan Close-Coupled Showerhead (CCS) MOCVD system. White light is reflected from the sample surface and monitored by a spectrometer during the growth. The reflectivity is sensitive to both the surface morphology and the epitaxial layer structure.Figure 2-1. Illustration of a home-made in situ reflectometry system integrated into the MOCVD system.Figure 2-2. Typical growth conditions for GaN templates used in this research.Typical growth conditions for GaN templates used in this research are summarized in Figure 2-2 and Table 2-2. Unless otherwise mentioned, c-plane sapphire substrates were used. The five steps outlined in Table 2-2, including high temperature (HT) cleaning, nitridation, low temperature (LT) nucleation, annealing of LT nucleation layer, and HT GaN growth, are crucial for high quality GaN epilayer.Figure 2-3 and Table 2-3 show the corresponding in situ reflectometry signal.In the following, we will describe how the reflectometry signal can be used to optimize the GaN template growth. Unless otherwise mentioned, we will refer to the reflectometry signal shown in Figure 2-3.Figure 2-3. In situ reflectometry trace of GaN template growth (Sample ID : UM-S07- 254). The highlighted areas correspond to important sub-steps during the epitaxy.2.1.1.1 High Temperature CleaningInitially, as the sample temperature is ramped up, the reflectivity increases due to the increase of the refractive index of the sample. Kim et al. has thoroughly studied the effect of initial thermal cleaning on the sapphire substrate andexperimentally demonstrated that this thermal treatment can effectively reduce the surface roughness of the substrate [46]. Generally, the flat surface is preferred for the GaN nuclei to be formed uniformly, which is critical to the crystal quality of the final GaN epilayer. The specific condition for the HT cleaning should be optimized by examining the treatment temperature and time. In our GaN growth, the optimal treatment temperature and time were set to be 1075 °C and 5 minutes, respectively. Moreover, HT surface annealing can effectively eliminate surface moisture.2.1.1.2 NitridationNitridation [5, 7] is the process of NH3 preflow under hydrogen (H2) ambient to prepare the surface for growth. During nitridation, NH3 reacts with the surface oxygen atoms on the sapphire substrate. Due to the replacement of the oxygen atoms by the nitrogen atoms and the diffusion of the nitrogen atoms into a certain depth, the exposed surface becomes a smooth amorphous state. Because this change of surface morphology is on the order of tens of angstrom, the corresponding reflectivity change is not significant. It has been shown that with a proper nitridation condition, GaN epilayers with lower dislocation density and better electrical and optical properties can be achieved [7]. However, as mentioned above, suitable combination of reactor conditions such as temperature, treatment time, and NH3 flow rate must be considered. In our GaN growth, the nitridation was optimized at 530 °C for a total of 210 seconds under 3 slm of NH3 flow.2.1.1.3 Low Temperature NucleationAs mentioned in Section 1.3.1, several approaches have been introduced to reduce the threading dislocation (TD) density in growing the GaN template. Specifically, the use of low temperature nucleation layer (LT NL) has been shown to be simple yet effective. A threading dislocation density as low as 108/cm2 has been reported [8].As GaN is nucleated on sapphire, the cubic phase islands are first formed at a temperature of 450 - 600 °C. These islands are subsequently transformed into the wurtzite phase [8]. The increase of the reflectivity during the LT NL growth is attributed to the increase of reflection from the flat top surfaces of nuclei. Basically, we know that the reflection from GaN is about twice stronger than that from sapphire due to the difference in refractive indices. As the islands become denser (i.e. the growth time of LT NL becomes longer), total reflection from the top surface of nuclei becomes up to 200% of reflection from sapphire substrate assuming that the entire surface is covered by GaN islands. Even though the islands are not coalesced completely to form a crystalline layer, this is still possible because the distances between the adjacent islands are too small compared to the optical wavelength. Once the reflectance exceeds twice that of the sapphire (as shown in Figure 2-3), the islands continue to coalesce further, which results in larger GaN grains and a thicker NL. Here, the size of the nucleation islands and the thickness of the NL are critical to obtain high quality GaN epilayer. To show that, we have compared a series of GaN templates with different NL conditions. All conditions were kept the same† except the growth time of the LT NL was varied,resulting in different LT NL thicknesses. The thickness of the LT NL was extrapolated by analyzing the reflectometry data as the reflection ratio at the end of LT NL growth to the sapphire substrate (RLT NL / RSapphire). The qualities of the GaN templates were characterized using photoluminescence (PL) and x-ray diffraction (XRD). From these results, the best GaN template quality can be obtained when RLT NL / RSapphire is around 2.6 which corresponds to a 40nm thick NL, at the given growth conditions.† LT NL growth temperature = 530°C, V/III = 9140, LT NL annealing time = 420 seconds, HT GaN growth temperature = 1040°C, V/III = 1230, growth time = 4300 seconds.Figure 2-4. The comparison of GaN template qualities with respect to the reflection ratio between the LT NL surface and the sapphire substrate.2.1.1.4 Annealing of Low Temperature Nucleation LayerIn GaN hetero-epitaxy with a large lattice mismatch, the initial growth on the surface follows the Volmer Weber model [47], i.e. GaN island growth dominates. In order to obtain smooth GaN templates, these islands need to be transformed into the layer-by-layer growth mode using an NL annealing process. During annealing, the substrate temperature is gradually increased up to around 1030 - 1050 °C under NH3 overpressure. Temperature ramping rate, reactor pressure, and NH3 flow can control the NL decomposition rate, which determines the surface roughness at the end of the annealing process [48, 49]. In Figure 2-3, after point (h) at which LT NL annealing begins, slight increase of reflectance is normally observed. The increase continues until around 800 °C at which GaN decomposition process starts to occur. Once the reflection intensity peaks, it begins to drop due to the increase in surface roughness. Initially randomly distributed islands start to be transformed into relatively uniform islands due to the decomposition of the NL and the migration of the gallium ad-atoms.During the annealing process, the reflectivity first decreases due to the increase of surface roughness. Further annealing results in a slight increase of reflectivity because at a higher temperature, the surface morphology becomes smoother. However, if we anneal the surface even further, the surface roughness increases again, which results in the decrease of reflection intensity [48, 49]. This phenomenon can be explained by considering the volume of the GaN islands. At the transition point ((k) in Figure 2-3), the volume of the islands per unit area becomes the highest which is preferable for the subsequent HT GaN growth. As a rule of thumb, the position of this (reflectometry trace) shoulder is dominated by the highest temperature of the annealing process [50]. In summary, the goal of the low temperature nucleation and the subsequent annealing is to achieve a surface morphology with proper density and sizes of the islands for the following HT GaN growth.As shown in Figure 2-5, even a slight change of the island distribution caused by a slight difference of the NL thickness and temperature ramping rate (Table 2-4) can result in a significant difference in the following HT GaN growth under the same conditions. In general, it takes longer for an NL with a rougher surface and smaller islands to be transformed into the 2D growth mode. The conditions to achieve high crystal quality GaN on sapphire are mostly related to the growth and annealing of the LT NL.2.1.1.5 HT GaN GrowthAs soon as the sapphire surface is covered with suitable volume, uniformity, thickness, and density of GaN islands, HT GaN growth can be followed. This HT GaN itself can be divided into two parts (Figure 2-6). Part I corresponds to the initial stage of HT GaN growth when the growth mode is transitioned from 3D to 2D, which affects the crystal quality significantly. In part II, GaN epilayer becomes thicker because the growth mode as well as growth condition is stabilized for 2Dmode. Several strategies to control the GaN growth in each regime will be briefly discussed in the following.The growth in part I is a buffer step to prepare a surface suitable for HT GaN growth. During this step, the oscillation of the reflectometry signal becomes increasingly obvious. Initially, the reflectivity continues to drop due to the increase of surface roughness induced by the coagulations of the islands, i.e. 3D growth. As time goes by, the 3D growth mode is suppressed and the 2D growth mode is enhanced. Once the surface becomes flattened due to the enhanced 2D growth, layer by layer growth of GaN begins, which causes the reflectivity to increase. The duration of this part of growth can be optimized by tweaking the reactor pressure, V/III ratio, and growth rate [51, 52]. For example, in the case of a low V/III ratio, it takes longer to recover the reflection intensity, which implies that the change of the growth mode (3D 2D) occurs more slowly. The reflectivity recovery time is critical to oscillation amplitude in part II. In general, a larger oscillation amplitude corresponds to a better crystal quality.The part II of the HT GaN growth is stable in a wide range of growth conditions because the growth occurs in a mass transfer limited region. Nevertheless, several key factors will still affect the crystalline structure, including the growth temperature, trimethyl-gallium (TMG) flow, NH3 flow, V/III ratio, and reactor pressure. As shown in Figure 2-7, the growth rate increases as the group III flow increases but decreases as the V/III ratio and growth temperature increase. The。
期末论文16×32点阵LED电子显示屏的设计模块
期末电子设计论文16×32点阵LED电子显示屏的设计The 16×32 lattice LED electron display monitor design论文书组长姓名：学号：指导教师；所在院系：计算机科学与技术所学专业：电子信息科学与技术山东财经大学中国·济南2013年6月一、课题名称16×32点阵LED电子显示屏的设计二、课题内容设计一个室内用的16×32点阵LED图文显示屏。
三、课题任务要求在目测条件下16×32点阵LED显示屏各点亮度均匀、充足，可显示图形和文字，显示图形或文字应稳定、清晰无串扰。
图形或文字显示有静止、移入移出等显示方式。
四、主要参考文献[1] 郭天祥主编：《51单片机C语言教程》北京：电子工业出版社，2013[2]张毅刚主编：《单片机原理及应用》．北京：高等教育出版社，2006指导教师签字教研室主任签字年月日摘要本设计是一16×32点阵LED电子显示屏的设计。
整机以美国ATMEL 公司生产的40脚单片机AT89C52为核心，介绍了以它为控制系统的LED点阵电子显示屏的动态设计和开发过程。
通过该芯片控制两个个行驱动器74HC138和两个列驱动器74HC595来驱动显示屏显示。
该电子显示屏可以显示各种文字或单色图像，全屏能显示2个汉字，采用8块8×8点阵LED显示模块来组成16×32点阵显示模式。
显示采用动态显示，使得图形或文字能够实现静止、移入移出等多种显示方式。
文中详细介绍了LED点阵显示的硬件设计思路、硬件电路各个部分的功能及原理、相应软件的程序设计，以及使用说明等。
单片机控制系统程序采用单片机C语言进行编辑，通过编程控制各显示点对应LED阳极和阴极端的电平，就可以有效的控制各显示点的亮灭。
所显示字符的点阵数据可以自行编写（即直接点阵画图）。
LED显示以其组构方式灵活、显示稳定、功耗低、寿命长、技术成熟、成本低廉等特点在车站、证券所、运动场馆、交通干道及各种室内/外显示场合的信息发布，公益宣传，环境参数实时，重大活动倒计时等等得到广泛的应用。
LED点阵显示屏毕业设计文献综述
XXXXXXXX大学专业文献综述LED点阵电子显示屏系统的设计作者:xxx 指导老师：xxx摘要:本设计拟采用一种由单片机控制的8＊8点阵发光模块组成的16＊64发光点阵，探讨简单的汉字、英文字母和动态图象显示技术，以及实时的温度测量显示。
该系统具有设计简单、字符清晰、可靠性高等特点。
关键词:LED；单片机;点阵；Design of LED Dot Matrix Electronic Display SystemAuthor: Song Jian—lei Instruct teacher: Li Xue—lianAbstract:The paper introduces a kind of 16＊64 dot matrix consists of 8*8 dot matrix module，we discuss the display technology of Chinese character, English letter，dynamic image and real time temperature。
It is simple in design，cheap in cost and high in reliability.Key words: LED；Single Chip Microcomputer；Dot Matrix；引言LED（Light Emitting Diode，LED）电子显示屏是随着计算机及相关的微电子、光电子技术的迅速发展而形成的一种新型信息显示媒体。
LED点阵显示器作为一种新兴的显示器件，它是由多个独立的LED发光二极管封装而成。
发光二极管LED具有体积小、抗冲击和抗震性能好、高可靠性、寿命长、工作电压低、功耗小及响应速度等优点[1］.由于电子显示屏具有显示内容信息量大，外形美观大方，操作使用方便灵活，用户可随时任意自行编辑修改显示内容，显示方式图文并茂等优点，因此被广泛应用于商场、学校、银行、邮局、机场、车站、码头、金融证券市场、文化中心、信息中心休息设施等公共场所[2］.本文主要介绍一种用于值班室外等场合的公告牌的LED点阵电子显示屏。
LED点阵全彩屏的设计【文献综述】
文献综述电气工程及其自动化LED点阵全彩屏的设计前言LED灯也就是发光二极管已经成为我们生活的必须品了，现如今我们晚上出门就会被那些多彩的LED灯照的眼花缭乱，无论走到哪里那些五彩的小灯都会进入我们的眼眶，从一出家门锁门的指示灯，到开车时中控台上的LED屏幕，然后去餐厅，公司，车站，医院，学校等各钟LED屏，还有很多，现在我们的生活已经渐渐的离不开那些一点点的发着微弱的光的LED灯了。
正文1 LED的发展概况发光二极管（LED）是一种电致发光的光电器件。
早在1907年开始，人们就发现某些半导体材料制成的二极管在正向导通时有发光的物理现象，但生产出有一定发光效率的红光LED 已是1969年了。
到今天，LED已生产了30多年，回顾过去，它已茁壮成长。
各种类型的LED、利用LED作二次开发的产品及与LED配套的产品（如白光LED驱动器）发展迅速，新产品不断上市，已发展成不少新型产业。
展望将来，还期望更进一步地提高。
早期的LED 主要用于做指示灯。
它的发光强度不高，一般小于1mcd，高的也仅几个mcd；另外，发光效率也不高，一般小于0.2lm/W；其功率仅几十mW到上百个mW（属于小功率LED）。
作为指示灯方面的应用，有几个mcd的发光强度也可以了，但由LED组成的数码管或字符管则显得亮度不足，若要用于户外作信号或标志显示，则其亮度太低，不能满足使用的要求。
所以LED 的主要发展方向是提高发光强度（也就是一般所指的提高亮度）。
随着半导体材料及半导体工艺技术、设备的发展，LED的亮度不断提高，开发出高亮度及超高亮度LED，并且不断创造新记录。
2 LED照明与应用该文从 LED的有关发光原理、特点、LED的驱动、LED的调光控制和LED的世界新产品推出与性能改进等方面进行了讨论,由于 LED照明技术的一系列优点,LED照明进展非常快 , LED照明有很好的应用前景。
1963年2月, LED的发明者N. HOLONY AK在《读者文摘》(美)上发表了“我们坚信LED 会发展成实用的白色光源”一文 ,并作了明确的预言:“将来的灯可以是铅笔尖大小的一块合金 ,它实用且不易破碎、决不烧毁 ,比起今天通用的灯泡来说,其转换效率至少大10倍。
LED显示屏中英文对照外文翻译文献
LED显示屏中英文对照外文翻译文献(文档含英文原文和中文翻译)译文：大屏幕显示系统的研究LED的发展随着计算机技术的高速发展，LED屏幕显示系统作为继电视、广播、报纸、杂志之后的“第五大媒体”正快速步入社会生活的各个方面。
它集微电子技术、计算机技术、信息处理技术于一体，可以将信息通过文字、图案、动画及视频四种形式显示出来。
与电视墙、磁翻板等媒体相比，LED大屏幕显示系统具有图案美观、色彩亮丽；图案、色彩变化丰富、快速；低功耗、长寿命、使用成本低、工作稳定可靠等特点。
它显示的图文视角大、视距远，因而已广泛应用于大型广场、商业广告、体育场馆、信息传播、新闻发布、证券交易；它还应用于工业控制和工业调动系统，便于把各种参数、报警点、工艺流程显示得更加清晰完美，可以满足不同环境的需要。
LED显示屏是一种利用计算机和复杂数字信号处理的电子广告宣传屏。
它的屏体部分由微处理器（主要是单片机）和驱动电路控制运行，显示的图像或文字由计算机编辑软件编辑获得。
由于LED显示屏这种新一代信息显示设备具有显示图案稳定、功耗低、寿命长等特点，而且它综合了各种信息显示设备的长处，并且克服了自身的不足，特别是由于一幅显示屏可以显示不同的内容，显示方式丰富。
所以在公共场合，它具有强烈的广告宣传和信息传递效果，日趋在固体显示中占主导地位。
LED显示屏的发展前景极为广阔，目前正朝着更高亮度、更高耐气候性、更高的发光密度、更高的发光均匀性、可靠性、全色化方向发展。
由不同材料的半导体组成能发出不同色彩的LED晶点。
目前应用最广的是红色、绿色、黄色LED。
而蓝色和纯绿色LED的开发已经达到了实用阶段。
LED显示屏的分类LED显示屏是多种技术综合应用的产品，涉及光电子学、半导体器件、数字电子电路、大规模集成电路、单片机及微机等各个方面，既有硬件又有软件。
LED 显示屏是作为广播、电视、报纸、杂志之后的又一新传播媒体。
目前LED显示屏根据使用场所不同，可以分为室外屏和室内屏两种，其主要区别是发光管的发光亮度不同。
英文文献和中文翻译Probing the Relationship of Long-Range Order in Nanodomain
对利用三元添置中子衍射得到的纳米级FeCo合金远程有序关系的探究1.简介由于具有非常高的饱和磁化强度和居里温度，FeCo合金在工业上是一种重要的工程材料。
这些合金在软磁材料的应用中发挥了重要作用，例如发电机和电动机。
进一步应用的例子是变压器磁芯，磁驱动传动器，高场磁体的磁极以及电磁阀。
在工业的大部分应用当中，面临的挑战是在保持磁性能的同时，如何提高FeCo合金的拉伸强度和韧性。
曾经尝试过的方法有改变合金设计（比如加入一些镍，钒，铌，钽，铬，钼三元金属）、进行退火处理或是采用先进的变形处理。
然而，在现代应用中，要求有更好的力学、磁学性能。
近几年来，由于对现代发电机和配电设备需求的增加，科学家在FeCo合金方面的研究兴趣与日俱增。
特别是在极端环境下，对电气应用的要求非常严格。
另一方面，针对FeCo合金的结构和物理性能，尤其是针对它的纳米结构系统提出了有趣的问题。
得益于低钴FeCo合金（钴占到质量分数的17%到35%）的发展，在满足所需的磁性能的同时，合金的成本才得以降低。
此外，较低的Co含量能够提高合金的延展性和韧性。
合金的力学性能和温度所决定的晶体结构有直接的联系。
在高温时，Fe、Co两元素随机分布在体心立方晶格上（图1 A2型结构）。
Co的含量占到29%到70%，这种无序的结构在低温状态下是不稳定的。
当温度低于远程无序的临界温度Tc时，Fe、Co将会被分配到两个相互穿插的原始立方晶格当中，并形成一个有序的B2型结构。
图1 二元合金FeCo的相图。
所讨论的三元合金的区域示意图。
B2型结构的合金有一些典型的特点。
比如说，“反结构”和“三点”机制产生的点缺陷能够导致晶格空位。
无序的B2型结构合金表现出波浪滑移，而局部无序型合金表现出平面滑移。
有序—无序之间的转变影响了FeCo合金的力学性能，比如合金韧性的改变、更脆的无序相、有序相等。
另外，磁性影响了结构的稳定性，造就了FeCo合金的有序性。
比如，在富铁FeCo合金中，磁有序稳定了体心立方结构，也稳定了来源于铁磁性B2相的有序性。
点阵LED外文文献+翻译
基于AT89C52的LED概述LED（Light Emitting Diode），发光二极管，是一种固态的半导体器件，它可以直接把电转化为光。
LED的心脏是一个半导体的晶片，晶片的一端附在一个支架上，一端是负极，另一端连接电源的正极，使整个晶片被环氧树脂封装起来。
半导体晶片由两部分组成，一部分是P型半导体，在它里面空穴占主导地位，另一端是N型半导体，在这边主要是电子。
但这两种半导体连接起来的时候，它们之间就形成一个“P-N结”。
当电流通过导线作用于这个晶片的时候，电子就会被推向P区，在P区里电子跟空穴复合，然后就会以光子的形式发出能量，这就是LED发光的原理。
而光的波长也就是光的颜色，是由形成P-N结的材料决定的。
LED历史50年前人们已经了解半导体材料可产生光线的基本知识，第一个商用二极管产生于1960年。
LED是英文light emitting diode（发光二极管）的缩写，它的基本结构是一块电致发光的半导体材料，置于一个有引线的架子上，然后四周用环氧树脂密封，即固体封装，所以能起到保护内部芯线的作用，所以LED的抗震性能好。
发光二极管的核心部分是由P型半导体和N型半导体组成的晶片，在P 型半导体和N型半导体之间有一个过渡层，称为P-N结。
在某些半导体材料的PN结中，注入的少数载流子与多数载流子复合时会把多余的能量以光的形式释放出来，从而把电能直接转换为光能。
PN结施加反向电压时，少数载流子难以注入，故不发光。
这种利用注入式电致发光原理制作的二极管叫发光二极管，通称LED。
当它处于正向工作状态时（即两端加上正向电压），电流从LED阳极流向阴极时，半导体晶体就发出从紫外到红外不同颜色的光线，光的强弱与电流有关。
最初LED用作仪器仪表的指示光源，后来各种光色的LED在交通信号灯和大面积显示屏中得到了广泛应用，产生了很好的经济效益和社会效益。
以12英寸的红色交通信号灯为例，在美国本来是采用长寿命、低光效的140瓦白炽灯作为光源，它产生2000流明的白光。
LED英文资料及中文翻译
First LED SummaryLED (Light Emitting Diode), light-emitting diode, is a solid state semiconductor devices, which can be directly converted into electricity to light. LED is the heart of a semiconductor chip, the chip is attached to one end of a stent, is the negative side, the other end of the power of the cathode, the entire chip package to be epoxy resin. Semiconductor chip is composed of two parts, part of the P-type semiconductor, it inside the hole-dominated, the other side is the N-type semiconductor, here is mainly electronic. But linking the two semiconductors, among them the formation of a "PN junction." When the current through the wires role in this chip, will be pushing e-P, P zone in the hole with electronic composite, and then to be issued in the form of photon energy, and this is the principle of LED luminescence. The wavelength of light that is the color of light, is formed by the PN junction of the decisions of the material.Second LED history and development50 years ago, people have to understand semiconductor materials can produce light of the basic knowledge, the first commercial diodes in 1960. English is the LED light emitting diode (LED) acronym, and its basic structure is an electroluminescent semiconductor materials, placed in a wire rack, then sealed with epoxy resin around, that is, solid package, Therefore, the protection of the internal batteries can play the role of line, so the seismic performance LED good.LED is the core of the P-type semiconductor and components of the N-type semiconductor chips, the P-type semiconductor and N-type semiconductor between a transition layer, called the PN junction. In some semiconductor materials in the PN junction, the injection of a small number of carrier-carrier and the majority of the extra time will be in the form of light energy to release, thus the power to direct conversion of solar energy. PN junction on reverse voltage, a few hard-carrier injection, it is not luminous. This use of injection electroluminescent diodes is produced by the principle of light-emitting diodes, commonly known as LED. When it in a positive state of the work (that is, at both ends with forward voltage), the current flows from the LED anode, cathode, semiconductor crystals on the issue from the ultraviolet to infrared light of different colors, light and the strength of the currents.Instruments used for the first LED light source instructions, but all kinds of light colored LED lights in traffic and large screen has been widely applied, have a very good economic and social benefits. The 12-inch red traffic lights as an example, is used in the United States have long life, low-efficiency 140 watt incandescent lamp as a light source, it produced 2,000 lumens of white light. The red filter, the loss-90 percent, only 200 lumens of red light. In the light of the new design, Lumileds companies have 18 red LED light source, including the loss of circuit, atotal power consumption of 14 watts to generate the same optical effect. Automotive LED lights is also the source of important areas.For general lighting, people need more white light sources. The 1998 white LED successful development. This is the GaN LED chip and Yttrium Aluminum Garnet (YAG) package together cause. GaN chip of the Blu-ray (λ p = 465nm, Wd = 30nm), made of high-temperature sintering of the Ce3 + YAG phosphors excited by this Blu-ray after irradiating a yellow, the peak 550 nm. Blue-chip installed in the LED-based Wanxing reflection in the cavity, covered with a resin mixed with YAG thin layer, about 200-500 nm. LED-based tablets issued by the Blu-ray absorption part of the phosphor, the phosphor another part of the Blu-ray and a yellow light mixed, can be a white. Now, the InGaN / YAG white LED, YAG phosphor by changing the chemical composition of the phosphor layer and adjust the thickness of the3500-10000 K color temperature can be colored white. This blue LED through the method by white, constructed simple, low-cost, high technology is mature, so use the most.The development of LED display can be divided into the following phases: first phase 1990 to 1995, mainly monochrome and 16 color graphics screen. Used to display text and simple images, mainly used in railway stations, financial securities, banks, post offices and other public places, as public information display tools. The second stage is from 1995 to 1999, there have been 64, 256 level gray-scale two-color video screen. Video control technology, image processing, optical fiber communication technology applications will enhance the LED display to a new level. LED display control LSI chips special at this time developed by domestic companies, and can be applied. The third stage, from 1999, red, pure green, blue LED in bulk into China, while domestic enterprises in-depth research and development work, using red, green, and blue LED production of full-color display has been widely used , poured into sports stadiums, convention centers, squares and other public places, which will bring the domestic large-screen full-color era. With the rapid development of LED materials market, surface mount device is available from 2001, mainly used in indoor full color, and its high brightness, colorful, low temperature characteristics, the point spacing can be adjusted by different price Requirements were accepted, in just two years time, product sales have more than 300 million yuan, surface mount full-color LED display application market entered the new century. To meet the 2008 Olympic Games, "downsizing" plan, Liard developed a surface mount dual color displays, a lot of time for the training center and game scoring. Full color in Olympic venues, in order to tighten investment, full color way is mostly detachable, live during the Olympic Games as a tool can be used for rental after the event, as the performance of national policies such as public places, tools released by In this way cost recovery as soon as possible. On the market, China's accession to WTO, Beijing's successful Olympic bid and so on, into the development of LED display industry, a new opportunity. Domestic LED display market continues to grow, currently in the domestic market, domestic LED display market share of nearly 95%. LED display theinternational market capacity is expected to 30% a year growth rate. Currently, LED display manufacturers concentrated primarily in Japan, North America, China LED manufacturers in which the insignificant share of exports. According to incomplete statistics, the world, there are at least 150 manufacturers full color, in which products are complete, the larger company has some 30 or so.Third LED advantagesConductor light-emitting diode (LED) as a third-generation semiconductor lighting source. This fantastic product has a lot of advantages: (1) efficient light: spectra of almost all concentrated in the visible light frequency, the efficiency can reach 80% -90%. The luminous efficiency of incandescent visible light efficiency of almost 10% -20% only. (2) high quality of light: not as a result of spectrum UV and infrared, there is no heat, no radiation, is typically a green light illumination. (3) energy consumption of the small: single power generally 0.05-1w, through the cluster can be tailored to meet different needs, and waste very little. As a light source, under the brightness in the same power consumption of only ordinary incandescent 1/8-10.(4) long life: flux attenuation to 70% of the standard life expectancy is 100,000 hours.A semiconductor light can be used under normal circumstances 50 years, even if the long life of the people, life will be used up to two lights. (5) durable and reliable: No tungsten wire, glass and other easily damaged components, non-normal retirement rate is very small, very low maintenance costs. (6) the application of flexibility: small size, can flat pack, easy to develop into a short thin products, make point, line, face various forms of specific applications. (7) Security: working voltage 1.5-5v or less in between the current 20-70mA in between. (8) green: recyclable waste, no pollution, unlike fluorescent lamps containing mercury as ingredients. (9) response time is short: to adapt to frequent and high-frequency switching operation of occasions.Fourth Classification of LED display1, color by color can be divided intoSingle-color display: Single color (red or green).Two-color display: red and green dual-color, 256 gray scale levels, can display 65,536 colors.Full-color screen: red, green, blue color, 256 grayscale full color display can display more than 16 million kinds of colors.2, according to display device classificationLED Digital Display: 7 segment display devices for the digital control code, suitable for production of the clock screen, the interest rate screens, showing the number of electronic display.LED dot-matrix graphic display: display device is arranged by a number of uniform composition of the dot-matrix LED display modules, suitable for broadcast text, image information.LED video display: display devices are formed by a number of light-emitting diodes that can display video, animation and other video files.3, by using the occasion categoriesIndoor Display: LED spots smaller, general Φ3mm - Φ8mm, shows the general area of a few to more than ten square meters.Outdoor Display: dozens of square meters in size to several hundred square meters, high brightness, can work in the sun, with wind, rain, water resistant.4, classified according to light spot diameterIndoor screen: Φ3mm, Φ3.75mm, Φ5mm,Room external screen: Φ10mm, Φ12mm, Φ16mm, Φ19mm, Φ20mm, Φ21mm, Φ22mm, Φ26mmRoom external screen as the basic unit of light emitting tube, LED tube principle is a set of red, green, and blue light-emitting diode sealed in a plastic barrel and jointly develop5, Display a static, horizontal scroll, vertical scroll and flip display. One block module control drive 12 (up to control 24) 8X8 Dot Matrix, a total of 16X48 dot matrix (or 32X48 dot matrix), is a single block of MAX7219 (or PS7219, HD7279, ZLG7289 and 8279, and the like LED display driver module) 12 times (or 24 times)! Can use "cascade" approach the composition of any large dot matrix display. Effects, good power consumption, and the MAX7219 circuit than the use of lower cost.Fifth LED applicationsIt is a semiconductor light-emitting diode by controlling the display, which probably look like that from lots of small red lights are usually formed by the bright lights off to show character. Used to display text, graphics, images, animations, quotes, video, video signals and other information on the display screen.Graphic display and LED display into the video display by the LED matrix blocks. Graphic displays can be synchronized with the computer display Chinese characters, English text and graphics; video display using micro-computer control, graphics, images, and Mao, real-time, synchronization, clear message to the broadcast of a variety of information dissemination, but also shows two dimensional, three-dimensional animation, video, TV, VCD programs and live on. LED display shows the screen brightly colored, three-dimensional sense of strong, static, such as painting, moving as the film is widely used in finance, tax, business, telecommunications, sports, advertising, industrial enterprises, transport, education systems, stations, docks, airports, shopping malls, hospitals, hotels, banks, securities markets, construction market, auction houses, industrial enterprises in management and other public places.LED display can show changes in the numbers, text, graphics and video; not only can be used in the indoor environment can also be used for outdoor environment, with a projector, TV wall, LCD screen can not match advantage.Sixth LED screen test methodA look at Screen size, appearance, smoothness, with the screen connection and so onSecond look after the dead pixel screen light up, not in not within the scope of (in general the screen is basically gone now)Color consistency, display text is normal, display pictures, play full screen full color to white, red, green, and blue.一 LED概述LED（Light Emitting Diode），发光二极管，是一种固态的半导体器件，它可以直接把电转化为光。
led照明毕业论文中英文资料外文翻译文献
led照明毕业论文中英文资料外文翻译文献Renewable and Sustainable Energy ReviewsHigh-brightness LEDs—Energy efficient lighting sources and their potential in indoor plant cultivation ABSTRACTThe rapid development of optoelectronic technology since mid-1980 has significantly enhanced the brightness and efficiency of light-emitting diodes (LEDs). LEDs have long been proposed as a primary light source for space-based plant research chamber or bioregenerative life support systems. The raising cost of energy also makes the use of LEDs in commercial crop culture imminent. With their energy efficiency, LEDs have opened new perspectives for optimizing the energy conversion and the nutrient supply both on and off Earth. The potentials of LED as an effective light source for indoor agriculturalproduction have been explored to a great extent. There are many researches that use LEDs to support plant growth in controlled environments such as plant tissue culture room and growth chamber. This paper provides a brief development history of LEDs and a broad base review on LED applications in indoor plant cultivation since 1990.Contents1. Introduction2. LED development.3. Color ratios and photosynthesis4. LEDs and indoor plant cultivation.4.1. Plant tissue culture and growth4.2. Space agriculture84.3. Algaculture4.4. Plant disease reduction5. Intermittent and photoperiod lighting and energy saving6. Conclusion1. IntroductionWith impacts of climate change, issues such as more frequent and seriousdroughts, floods, and storms as well as pest and diseases are becoming more serious threats to agriculture. These threats along with shortage of food supply make people turn to indoor and urban farming (such as vertical farming) for help. With proper lighting, indoor agriculture eliminates weather-related crop failures due to droughts and floods to provide year-round crop production, which assist in supplying food in cities with surging populations and in areas of severe environmental conditions.The use of light-emitting diodes marks great advancements over existing indoor agricultural lighting. LEDs allow the control of spectral composition and the adjustment of light intensity to simulate the changes of sunlight intensity during the day. They have the ability to produce high light levels with low radiant heat output and maintain useful light output for years. LEDs do not contain electrodes and thus do not burn out like incandescent or fluorescent bulbs that must be periodically replaced. Not to mention that incandescent and fluorescent lamps consume a lot of electrical power while generating heat, which must be dispelled from closed environments such as spaceships and space stations.2. LED developmentLED is a unique type of semiconductor diode. It consists of a chip of semiconductor material doped with impurities to create a p–n junction. Current flows easily from the p-side (anode), to the n-side (cathode), but not in the reverse direction.Electrons and holes flow into the junction from electrodes with different voltages. When an electron meets a hole, it falls into a lower energy level, and releases energy in the form of a photon. The color (wavelength) of the light emitted depends on the band gap energy of the materials forming the p–n junction. The materials used for an LED have a direct band gap with energies corresponding to near-infrared, visible or near-ultraviolet light.The key structure of an LED consists of the die (or light-emitting semiconductor material), a lead frame where the die is placed, and the encapsulation which protects the die (Fig. 1).Fig.1LED development began with infrared and red devices made with gallium arsenide. Advances in materials science have made possible the production of devices with ever-shorter wavelengths, producing light in a variety of colors. J.Margolin reported that the first known light-emitting solid state diode was made in 1907 by H. J. Round. No practical use of Round’s diode was made for several decades until the invention of the first practical LED by Nick Holonyak, Jr in 1962. His LEDs became commercially available inlate 1960s. These GaAsP LEDs combine three primary elements: gallium, arsenic and phosphorus to provide a 655nm red light with brightness levels of approximately 1–10 mcd at 20mA. As the luminous intensity was low, these LEDs were only used in a few applications, primarily as indicators. Following GaAsP, GaP (gallium phosphide) red LEDs were developed. These device sex hibit very high quantum efficiencies at low currents. As LED technology progressed through the 1970s, additional colors and wavelengths became available. The most common materials were GaP green and red, GaAsP orange, and high efficiency red and GaAsP yellow. The trend towards more practical applications (such as in calculators, digital watches, and test equipment) also began to develop. As the LED materials technology became more advanced, the light output was increased, and LEDs became bright enough to be used for illumination.In 1980s a new material, GaAlAs (gallium aluminum arsenide) was developed followed by a rapid growth in the use of LEDs. GaAlAs technology provides superiorperformance over previously available LEDs. The voltage requirement is lower, which results in a total power savings. LEDs could be easily pulsed or multiplexed and thus are suitable for variable message and outdoor signs. Along this development period, LEDs were also designed into bar code scanners, fiber optic data transmission systems, and medicalequipment. During this time, the improvements in crystal growth and optics design allow yellow, green and orange LEDs only a minor improvement in brightness and efficiency. The basic structure of the material remained relatively unchanged.As laser diodes with output in the visible spectrum started to commercialize in late 1980s, LED designers used similar techniques to produce high-brightness and high reliability LEDs. This led to the development of InGaAlP (indium gallium aluminum phosphide) visible light LEDs. Via adjusting the energy band gap InGaAlP material can have different color output. Thus, green, yellow, orange and red LEDs could all be produced using the same basic technology. Also, light output degradation of InGaAlP material is significantly improved.Shuji Nakamura at Nichia Chemical Industries of Japan introduced blue LEDs in 1993. Blue LEDs have always been difficult to manufacture because of their high photon energies (>2.5 eV) and relatively low eye sensitivity. Also, the technology to fabricate these LEDs is very different and less advanced than standard LED materials. But blue is one of the primary colors (the other two being red and green). Properly combining the red, green, and blue light is essential to produce white and full-color. This process requires sophisticated software and hardware design to implement. In addition, the brightness level is low and the overall light output of each RGB die being used degrades at a different rate resulting in an eventual color unbalance. The blue LEDs available today consist of GaN (gallium nitride) and SiC (silicon carbide) construction. The blue LED that becomes available in production quantities has result in an entire generation of new applications that include telecommunications products, automotive applications, traffic control devices, and full-color message boards. Even LED TVs can soon become commercially available.Compare to incandescent light’s 1000-h and fluorescent light’s 8000-h life span, LEDs have a very significantly longer life of 100,000 h. In addition to their long life, LEDs have many advantages over conventional light source. These advantages include small size, specific wavelength, low thermal output, adjustable light intensity and quality, as well as high photoelectric conversion efficiency. Such advantages make LEDs perfect for supporting plant growth in controlled environment such as plant tissue culture room and growth chamber. Table 1 is a list of some common types of LEDs as compiled from .The chlorophyll molecules in plants initiate photosynthesis bycapturing light energy and converting it into chemical energy to help transforming water and carbon dioxide into the primary nutrient for living beings. The generalized equation for the photosynthetic process is given as:CO2 + H2O—light—>（CH2O）+ O2where (CH2O) is the chemical energy building block for thesynthesis of plant components.Chlorophyll molecules absorb blue and red wavelengths most efficiently. The green and yellow wavelengths are reflected or transmitted and thus are not as important in the photosyntheticprocess. That means limit the amount of color given to the plants and still have them grow as well as with white light. So, there is no need to devote energy to green light when energy costs are aconcern, which is usually the case in space travel.The LEDs enable researchers to eliminate other wavelengths found within normal white light, thus reducing the amount of energy required to power the plant growth lamps. The plants grow normally and taste the same as those raised in white light.Red and blue light best drive photosynthetic metabolism. These light qualities are particularly efficient in improving the developmental characteristics associated with autotrophic growth habits. Nevertheless, photosynthetically inefficient light qualities also convey important environmental information to a developing plant. For example, far-red light reverses the effect of phytochromes, leading to changes in gene expression, plant architecture, and reproductive responses. In addition, photoperiod (the adjustment of light and dark periods) and light quality (the adjustment of red, blue and far-red light ratio) also have decisive impacts on photomorphogenesis.The superimposed pattern of luminescence spectrum of blue LED (450–470 nm) and that of red LED (650–665 nm) corresponds well to light absorption spectrum of carotenoids and chlorophyll. Various plant cultivation experiments are possible when these twokinds of LED are used with the addition of far-red radiation (730–735 nm) as the light source. Along the line of the LED technology advancement, LEDs become a prominent light source for intensive plant culture systems and photobiological researches. The cultivation experiments which use such light sources are becoming increasingly active. Plant physiology and plant cultivation researches using LEDs started to peak in 1990s and become inevitable in the new millennium. Those researches have confirmed that LEDs are suitable for cultivation of a variety of algae,crop, flower, fruit, and vegetable.Some of the pioneering researches are reviewed in the followings.Bula et al. have shown that growing lettuce with red LEDs in combination with blue tubular fluorescent lamp (TFL) is possible. Hoenecke et al. have verified the necessity of blue photons for lettuce seedlings production by using red LEDs with blue TFL. As the price of both blue and red LEDs have dropped and the brightness increased significantly, the research findings have been able to be applied in commercial production. As reported by Agence France Press, Cosmo Plant Co., in Fukuroi, Japan has developed a red LED-based growth process that uses only 60% of electricity than a fluorescent lighting based one.Tennessen et al. have compared photosynthesis from leaves of kudzu (Pueraria lobata) enclosed in a leaf chamber illuminated by LEDs versus by a xenon arc lamp. The responses of photosynthesis to CO2 are similar under the LED and xenon arc lamps at equal photosynthetic irradiance. There is no statistical significant difference between the white light and red light measurements in high CO2. Some leaves exhibited feedback inhibition of photosynthesis which is equally evident under irradiation of either lamp type. The results suggest that photosynthesis research including electron transport, carbon metabolismand trace gas emission studies should benefit greatly from the increased reliability, repeatability and portability of a photosynthesis lamp based on LEDs.Okamoto et al. have investigated the effects of different ratios of red and blue (red/blue) photosynthetic photon flux density (PPFD) levels on the growth and morphogenesis of lettuce seedlings. They have found that the lettuce stem length decreases significantly with an increase in the blue PPFD. The research has also identified the respective PPFD ratio that (1) accelerates lettuce seedlings’stem elongation, (2) maximizes the whole plant dry weight, (3) accelerates the growth of whole plants, and (4) maximizes the dry weights of roots and stems. Photosynthesis does not need to take place in continuous light. The solid state nature allows LEDs to produce sufficient photon fluxes and can be turned fully on and off rapidly (200 ns), which is not easily achievable with other light sources. This rapid on–off feature has made LEDs an excellent light source for photosynthesis research such as pulsed lighting for the study of photosynthetic electron transport details. The off/dark period means additional energy saving on top of the LEDs’low power consumption.4. LEDs and indoor plant cultivation4.1. Plant tissue culture and growthTissue culture (TC), used widely in plant science and a number of commercial applications, is the growth of plant tissues or cells within a controlled environment, an ideal growth environment that is free from the contamination of microorganisms and other contaminants. A controlled environment for PTC usually means filtered air, steady temperature, stable light sources, and specially formulated growth media (such as broth or agar). Micropropagation, a form of plant tissue culture (PTC), is used widely in forestry and floriculture. It is also used for conserving rare or endangered plant species. Other uses of PTC include:1short-term testing of genetic constructions or regeneration oftrans genic plants,2 cross breeding distantly related species and regeneration of the novel hybrid,3 screening cells for advantageous characters (e.g. herbicidere sistance/tolerance),4embryo rescue (i.e. to cross-pollinate distantly related specie sand then tissue culture there sulting embryo which would normally die),5 large-scale growth of plant cells in liquid culture inside bioreactors as a source of secondary products (like recombinant proteins used as biopharmaceuticals).6production of doubled monoploid plants from haploid cultures to achieve homozygous lines more rapidly in breeding programs (usually by treatment with colchicine which causes doubling of the chromosome number).Tissue culture and growth room industries have long been using artificial light sources for production. These light sources include TFL, high pressure sodium lamp (HPS), metal halide lamp (MHL) and incandescent lamp, etc. Among them, TFL has been the most popular in tissue culture and growth room industries. However, the use of TFL consumes 65% of the total electricity in a tissue culture lab. That is the highest non-labor costs. As a result, these industries continuously seek for more efficient light sources. The development of high-brightness LED has made LED a promising light source for plant growth in controlled environments.Nhut et al. have cultured strawberry plantlets under different blue to red LED ratios as well as irradiation levels and compared its growth to that under plant growth fluorescent. The results suggest that a culture system using LED is advantageous for the micropropagation of strawberry plantlets. The study also demonstrates that the LED light source for in vitro culture of plantlets contributes to an improved growth of the plants in acclimatization.Brown et al. have measured the growth and dry matter partitioning of ‘Hungarian Wax’pepper (Capsicum annuum L.) plants grown under red LEDs compared with similar plants grown under red LEDs with supplemental blue or far-red radiation. Pepper biomass reduces when grown under red LEDs without blue wavelengths compared to plants grown under supplemental blue fluorescent lamps. The addition of far-red radiation results in taller plants with greater stem mass than red LEDs alone. Fewer leaves developed under red or red plus far-red radiation than with lamps producing blue wavelengths. The results of their research indicate that with proper combination of other wavelengths, red LEDs may be suitable for the culture of plants in tightly controlled environments.4.2. Space agricultureBecause re-supply is not an option, plants are the only options to generate enough food, water and oxygen to help make future explorers self-sufficient at space colonies on the moon, Mars or beyond. In order to use plants, there must be a light source. Standard light sources that used in homes and in greenhouses and in growth chambers for controlled agriculture here on Earth are not efficient enough for space travel. While a human expedition outside Earth orbit still might be years away, the space farming efforts are aimed at developing promising artificial light sources. LEDs, because of their safety, small mass and volume, wavelength specificity, and longevity, have long been proposed as a primary light source for space-base plant research chamber or bioregenerative life support systems .Infrared LEDs that are used in remote controls devices have other uses. Johnson et al. have irradiated oat (Avena sativa cv Seger) seedlings with infrared (IR) LED radiation passed through a visible-light-blocking filter. The irradiated seedlings exhibited differences in growth and gravitropic response when compared to seedlings grown in darkness at the same temperature. This suggests that the oat seedlings are able to detect IR LED radiation. These findings also expand the defined range of wavelengths involved in radiation–gravity (light–gravity) interactions to include wavelengths in the IR region of the spectrum.Goins et al. grow wheat under red LEDs and compare them to the wheat grown under (1) white fluorescent lamps and (2) red LEDs supplemented with blue light from blue fluorescent lamps. The results show that wheat grown under red LEDs alone displayed fewer subtillers and a lower seed yield compared to those grown under white light. Wheat grown under red LEDs + 10% BF light had comparable shoot dry matter accumulation and seed yield relative to those grown under white light. These results indicate that wheat can complete its life cycle under red LEDs alone, but larger plants and greater amounts of seed are produced in the presence of red LEDs supplemented with a quantity of blue light.The research of Goins and his team continues in plant growth chambers the size of walk-in refrigerators with blue and red LEDs to grow salad plants such as lettuce and radishes. They hope the plant growth chamber would enable space station staff to grow and harvest salad greens, herbs and vegetables during typical fourmonth tours on the outpost .4.3. AlgacultureAlgaculture, refers to the farming of species of algae, has been a great source for feedstock, bioplastics, pharmaceuticals, algae fuel, pollution control, as well as dyes and colorants. Algaculture also provides hopeful future food sources.Algae can be grown in a photobioreactor (PBR), a bioreactor which incorporates some type of light source. A PBR is a closed system, as opposed to an open tank or pond. All essential nutrients must be introduced into the system to allow algae to grow and be cultivated. A PBR extends the growing season and allows growing more species. The device also allows the chosen species to stay dominant. A PBR can either be operated in ‘‘batch mode’’or ‘‘continuous mode’’in which a continuous stream of sterilized water that contains air, nutrients, and carbon dioxide is introduced. As the algae grows, excess culture overflows and is harvested.When the algae grow and multiply, they become so dense that they block light from reaching deeper into the water. As a result, light only penetrates the top 7–10 cm of the water in most algalcultivation systems. Algae only need about 1/10 the amount of direct sunlight. So, direct sunlight is often too strong for algae. A means of supplying light to algae at the right concentration is to place the light source in the system directly.Matthijs et al. have used LEDs as the sole light source in continuous culture of the green alga (Chlorella pyrenoidosa). The research found the light output of the LED panel in continuous operation sufficient to support maximal growth. Flash operation at 5-ps pulse ‘‘on’’ duration between dark periods of up to 45 ps would stillsustain near maximum growth. While longer dark periods tend to cut the growth rate, the light flux decrease resulting from such operation does not reduce the growth as much as that of the similar flux decrease in continuous operation. Their research concludes that the use of flashing LEDs (which means intermittent light) in indoor algal culture yielded a major gain in energy economy comparing to fluorescent light sources. An additional advantage is that heat waste losses are much smaller. The most interesting discovery of this study may be that adding blue light to the red LED light did not change the growth properties.In order to take advantage of the biotechnological potential of algae, Lee and Palsson have calculated theoretical values of gas mass transfer requirements and light intensity requirements to support high-density algal cultures for the 680 nm monochromatic red light from LED as a light source. They have also designed a prototype PBR based on these calculations. Using on-line ultra filtration to periodically provide fresh medium, these researchers have achieved a cell concentration of more than 2×109cells/ml (more than 6.6%, vol/vol), cell doubling times as low as 12 h, and an oxygen production rate as high as 10 mmol oxygen/l culture/h. This research indicates that the development of a small LED-based algal photobioreactors is economically achievable.Another research of algae via LEDs is conducted by Nedbal et al. Their research is a study of light fluctuation effects on a variety of algae in dilute cultures using arrays of red LEDs to provide intermittent and equivalent continuous light in small-size (30 ml) bioreactors. The results endorse that the algae growth rates in certain calculated intermittent light can be higher than the growth rate in the equivalent continuous light. Yanagi and Okamoto has grown five spinach plants under the red LEDs and another five under 40W plant growth fluorescent lamps at the same light intensity of 125 mmol/m2/s. The dry matter production under the LEDs is slightly less than that under the fluorescent lamps. The plant leaf area under the red LEDs is also smaller than that under the fluorescent lamps. Nevertheless, they reach a conclusion that LEDs can qualify as an artificial light source for plant growth.4.4.Plant disease reductionSchuerger and Brown have used LED arrays with different spectral qualities to determine the effects of light on the development of tomato mosaic virus (ToMV) in peppers and powdery mildew on cucumbers. Their research concludes that spectral quality may alter plant disease development. Latter research regarding bacterial wilt on tomato has confirmed this conclusion and demonstrates that spectral quality may be useful as a component of an integrated pest management program for space-based ecological life support systems. Schuerger et al. have shown that the spectral quality effects on peppers’ anatomical changes in stem and leaf tissues are corr elated to the amount of blue light in primary light source.Miyashita et al. use red LEDs (peak wavelength: 660 nm) and white fluorescent lamps as light sources for potato plantlets growth in vitro. They found that shoot length and chlorophyll concentration of the plantlets increases with increasing 630–690 nm red photon flux (R-PF) while there are no significant differences in dry weight and leaf area of the plantlets with different R-PF levels. This means red lightaffects the morphology rather than the growth rate of potato plantlets in vitro. As a result, they suggest that red LEDs can be used for controlling plantlet morphology in micropropagation.5. Intermittent and photoperiod lighting and energy savingTime constants for photosynthetic processes can be divided into three ranges: primary photochemistry, electron shuttling, and carbon metabolism. These three photosynthetic processes can be uncoupled by providing pulses of light within the appropriate range for each process. At high frequencies, pulsing light treatments can be used to separate the light reactions (light harvesting and charge separation) from the dark reactions (electron shuttling) of photosynthetic electron transport. LEDs’ flexible pulsating ability can be coupled with such characteristics of photosynthesis and lead to additional energy saving.Tennessen et al. use LEDs to study the effects of light pulses (micro- to milli-second) of intact tomato leaves. They found that when the equivalent of 50 mmol photons mp -2s-1 is provided during 1.5 ms pulses of 5000 mmol photons mp -2s-1 followed by 148.5 ms dark periods, photosynthesis is the same as in continuous 50 mmol photons mp -2s-1 . Data support the theory that photons in pulses of 100 ps or shorter are absorbed and stored in the reaction centers to be used in electron transport during the dark period. Pigments of the xanthophyll cycle were not affected by pulsed light treatments. This research suggests that, instead of continuous light, using effectively calculated intermittent light (which means less energy consumption) might not affect the plant production.Jao and Fang have investigated the effects of intermittent light on growth of potato plantlets in vitro. They also use conventional TFLs for the experiment to explore the electrical savings realized by adjusting the frequency and duty ratio of LEDs. TFLs provide continuous fluctuating light at 60 Hz while LEDs provide nonfluctuating light and pulse light of the preset frequency and duty ratio. When the growth rate is the only concern, LEDs at 720 Hz (1.4 ms) and 50% duty ratio with 16-h light/8-h dark photoperiod stimulated plant growth the most. When energy consumption is the major concern, using LEDs at 180 Hz (5.5 ms) and 50% duty ratio with 16-h light/8-h dark photoperiod would not significantly sacrifice plant growth, especially when energy for heat removal is also taken into account.6. ConclusionsThe first sustained work with LEDs as a source of plant lighting occurred in the mid-1980s when a lighting system for plant growth was designed for space shuttles and space stations for it is realized that people cannot go to the Moon, Mars, or beyond without first mastering the art of indoor farming on Earth. As the performance of LED continues to improve, these lighting systems progress from red only LED arrays using the limited components available to high-density, multi-color LED chip-on-board technologies. Today, space age gardeners who have been testing high-efficiency light sources for future space colonists have identified energy efficient LEDs as the major light source not only to grow food but also to generate and purify oxygen and water—key sustainers of human life. The removal of carbon dioxide from a closed environment is another added benefit.LEDs are the first light source to provide the capability of true spectral composition control, allowing wavelengths to match to plant photoreceptors to optimize production as well as to influence plant morphology and composition. They are easily integrated into digital control systems, facilitating complex lighting programs like varying spectral composition over the course of a photoperiod or with plant development stage. LEDs do not contain mercury. They are safer to operate than current lamps since they do not have glass envelopes or high touch temperatures.While the process of photosynthesis does not require continuous light of full spectrum, LEDs can produce sufficient photon fluxes of specific wavelength on and off rapidly. Such mechanism of photosynthesis coupled with the solid state characteristics of LEDs constitute two ways of energy saving (cutting out unnecessary spectrum segment and turning off the light periodically) on top of the LEDs’ low power consumption. These are not easily achievable with other light sources.This paper provides a broad base review on LED applications in horticulture industry since 1990. These researches pave the way for the researches of similar types using different species and lead to comparable conclusion that LEDs are well qualified to replace its more energy demanding counterparts as controlled environment light source for agricultural research such as providing tissue culture lighting as well as supplemental and photoperiod lighting for greenhouses.With the energy it can save, LED’s becoming ec onomically feasible in large-scale indoor farming lighting applications is just around the corner.再生可持续能源评论高亮高效节能LED灯的来源及其在室内植物栽培中的潜力摘要自1980年中期以来，光电子技术的迅猛发展，显著调高了发光二极管（LED）的亮度和效率。
点阵LED外文翻译3000字文献
Based on AT89C52 LED overviewLED (Light Emitting Diode), light-emitting diode, is a solid state semiconductor devices, which can be directly converted into electricity to light. LED is the heart of a semiconductor chip, the chip is attached to one end of a stent, is the negative side, the other end of the power of the cathode, the entire chip package to be epoxy resin. Semiconductor chip is composed of two parts, part of the P-type semiconductor, it inside the hole-dominated, the other side is the N-type semiconductor, here is mainly electronic. But linking the two semiconductors, among them the formation of a "PN junction." When the current through the wires role in this chip, will be pushing e-P, P zone in the hole with electronic composite, and then to be issued in the form of photon energy, and this is the principle of LED luminescence. The wavelength of light that is the color of light, is formed by the PN junction of the decisions of the material.LED history 50 years ago, people have to understand semiconductor materials can produce light of the basic knowledge, the first commercial diodes in 1960. English is the LED light emitting diode (LED) acronym, and its basic structure is an electroluminescent semiconductor materials, placed in a wire rack, then sealed with epoxy resin around, that is, solid package, Therefore, the protection of the internal batteries can play the role of line, so the seismic performance LED good.LED is the core of the P-type semiconductor and components of the N-type semiconductor chips, the P-type semiconductor and N-type semiconductor between a transition layer, called the PN junction. In some semiconductor materials in the PN junction, the injection of a small number of carrier-carrier and the majority of the extra time will be in the form of light energy to release, thus the power to direct conversion of solar energy. PN junction on reverse voltage, a few hard-carrier injection, it is not luminous. This use of injection electroluminescent diodes is produced by the principle of light-emitting diodes, commonly known as LED. When it in a positive state of the work (that is, at both ends with forward voltage), the current flows from the LED anode, cathode, semiconductor crystals on the issue from the ultraviolet to infrared light of different colors, light and the strength of the currents.Instruments used for the first LED light source instructions, but all kinds of light colored LED lights in traffic and large screen has been widely applied, have a very good economic and social benefits. The 12-inch red traffic lights as an example, is used in the United States have long life, low-efficiency 140 watt incandescent lamp as a light source, it produced 2,000 lumens of white light. The red filter, the loss-90 percent, only 200 lumens of red light. In the light of the new design, Lumileds companies have 18 red LED light source, including the loss of circuit, a total power consumption of 14 watts to generate the same optical effect. Automotive LED lights is also the source of important areas.For general lighting, people need more white light sources. The 1998 white LED successful development. This is the GaN LED chip and Yttrium Aluminum Garnet (YAG) package together cause. GaN chip of the Blu-ray (λ p = 465nm, Wd = 30nm), made of high-temperature sintering of the Ce3 + YAG phosphors excited by this Blu-ray after irradiating a yellow, the peak 550 nm. Blue-chip installed in the LED-based Wanxing reflection in the cavity, covered with a resin mixed with YAG thin layer, about 200-500 nm. LED-based tablets issued by the Blu-ray absorption part of the phosphor, the phosphor another part of the Blu-ray and a yellow light mixed, can be a white. Now, the InGaN / YAG white LED, YAG phosphor by changing the chemical composition of the phosphor layer and adjust the thickness of the 3500-10000 K color temperature can be colored white. This blue LED through the method by white, constructed simple, low-cost, high technology is mature, so use the most.In the 1960s, the use of science and technology workers semiconductor PN junction of The principle of developing a LED light-emitting diodes. At that time, the development of LED, the materials used are GaASP, its luminous color is red. After nearly 30 years of development, and now we are very familiar with the LED, has been sent to red, orange, yellow, green, blue, and other shade. However lighting necessary for white LED light only in recent years to develop, readers here to tell us about lighting with white LED.The LED display screen and video display into the text by LED matrix blocks. Graphic display can be displayed with computer, English, Chinese text and graphics, Video screen using microcomputer control, graphic, image, with real-time, synchronization, clear information dissemination way play all kinds of information, but also shows 2d, 3d animation, videos, TV, VCD programs and live. The LED display screen display bright colors, stereo sense is strong, such as oil, such as films, widely used in finance, taxation, industry and commerce, telecommunications, sports, advertising, corporations, transportation, education system, station, port, airport, hospital, shopping malls, hotels, Banks, securities market, market, and construction management of industrial enterprises, Christie's and other public places.The LED display can display the change of digital image; text, graphics, Not only can be used for indoor environment can also be used in outdoor environment, projectors, LCD TV wall, and the incomparable advantages.LED by the wide attention and rapid development, and it is the advantages of itself. These advantages in is: high brightness, working voltage, low consumption, miniaturization, impact resistance and long service life and stable performance. LED the development prospect, is currently towards a higher brightness, higher resistance to climate, higher and higher light shine density evenness, reliability, the direction of development. Full-colorThe classification of the LED display1, the color can be divided into gezerThe single color display: single colors (red or green).Double colors: red and green screen, double colors gray, can show 256 levels 65536 colors.Full-color display: red, green, and blue, gray level 256 gezer full-color display screen can show more than 1,600 colors.2, according to the classification of display devicesLED digital display: display device for seven yards, suitable for making the clock display screen, interest rates, digital electronic display screen.Pictures of LED dot matrix LCD display device is composed of many: evenly composed of light emitting diode matrix display module, suitable for broadcast text, images of information.LED video display: display device is composed by many light-emitting diodes, video, animation shows various video files.3, by using occasions classificationIndoor display: light point is lesser, general Φ 3mm - Φ 8mm, display area of general several ten square meters to.Outdoor screen area to several hundred square meters general dozens, high brightness, can work under the sun, in the wind, rain, waterproof function.4 points, according to the classification of light in diameterIndoor screens: Φ 3mm, Φ 3.75 mm, Φ 5mm,Outdoor screen: Φ 10mm, Φ 12mm and Φ 16mm Φ, 19mm, Φ 20mm, Φ 21mm, Φ 22mm, Φ 26mmThe basic unit of the light outdoor screen for led light cone tube, the principle is a group of red, green, and blue light emitting diode sealed in a plastic tube in common5. Display horizontally scrolling, static, vertical scroll and flip shows, etc. Single block module control drive 12 (maximum control and block), 16X48 matrix 8X8 matrix (or 32X48 matrix), is a single block of MAX7219 (or PS7219, HD7279, ZLG7289 8279 and other similar LED display driver module) 12 times (or 24 times)! Can use "cascade" means any bitmap big screen composed. Show good effect, low consumption, and the cost of using MAX7219 circuit is lower.The LED display inspection method,See appearance, specifications, screen body flatness, screen the attachment within2 look bad, after the light screen is not in scope, the screen (generally now basically no)Color consistency, displays text display is normal, the picture to screen, full-color play white, red, green and blue.Technical advantageExisting common indoor full-color scheme comparison:1 the matrix modules: design, color dot matrix LCD by indoor artifactsAdvantage: the cost of raw materials, production and processing of the most advantage of simple process, quality is stable.Faults: color consistency, Mosaic phenomenon, serious effect.2. Single lamp schemes for solving the bitmap screen color: for outdoor screen technology,a scheme of pixels, outdoor multiplexing technique (also called pixel sharing technology, virtual pixels to indoor display technology) transplantation.Advantage: color consistency than bitmap module of good way.Weakness: the effect not beautiful, color mixing, horizontal Angle and have off color. Process is relatively complex, anti-static high. Actual pixel resolution do 10,000 more difficult.Features• Compatible with MCS-51® Products• 8K Bytes of In-System Programmable (ISP) Flash Memory• 1000 Write/Erase Cycles• Fully Static Operation: 0 Hz to 33 MHz• Three-level Program Memory Lock• 256 x 8-bit Internal RAM• 32 Programmable I/O Lines• Three 16-bit Timer/Counters• Eigh t Interrupt Sources• Full Duplex UART Serial Channel• Low-power Idle and Power-down Modes• Interrupt Recovery from Power-down Mode• Watchdog Timer• Dual Data Pointer• Power-off FlagDescriptionThe AT89C52 is a low-power, high-performance CMOS 8-bit microcontroller with 8K bytes of in-system programmable Flash memory. The device is manufactured using Atmel’s high-density nonvolatile memory technology and is compatible with the industry standard 80C51 instruction set and pinout. The on-chip Flash allows the programmemory to be reprogrammed in-system or by a conventional nonvolatile memory programmer.By combining a versatile 8-bit CPU with in system programmable Flash on a monolithicchip, the Atmel AT89C52 is a powerful icrocontroller which provides a highly-flexible and cost-effective solution to many embedded control applications.The AT89C52 provides the following tandard features: 8K bytes of Flash, 256 bytes of RAM, 32 I/O lines, Watchdog timer, two data pointers, three 16-bit timer/counters, a six-vector two-level interrupt architecture, a full duplex serial port, on-chip oscillator,and clock circuitry. In addition, the AT89C52 is designed with static logic for operation down to zero frequency and supports two software selectable power saving modes.The Idle Mode stops the CPU while allowing the RAM, timer/counters, serial port, and interrupt system to continue functioning. The Power-down mode saves the RAM contents but freezes the oscillator, disabling all other chip functions until the next interrupt or hardware reset.In the Counter function, the register is incremented in response to a 1-to-0 transition at its corresponding external input pin, T2. In this function, the external input is sampled during S5P2 of every machine cycle. When the samples show a high in one cycle and a low in the next cycle, the count is incremented. The new count value appears in the register during S3P1 of the cycle following the one in which the transition was detected. Since two machine cycles (24 oscillator periods) are required to recognize a 1-to-0 transition, the maximum count rate is 1/24 of the oscillator frequency. To nsure that a given level is sampled at least once before it changes, the level should be held for at least one full machine cycle.InterruptsThe AT89C52 has a total of six interrupt vectors: two external interrupts (INT0 and INT1), three timer interrupts (Timers 0, 1, and 2), and the serial port interrupt. These interrupts are all shown in Figure 10. Each of these interrupt sources can be individually enabled or disabled by setting or clearing a bit in Special Function Register IE. IE also contains a global disable bit, EA, whichdisables all interrupts at once. Note that Table 5 shows that bit position IE.6 is unimplemented. In the AT89C52, bit position IE.5 is also unimplemented.User software should not write 1s to these bit positions, since they may be used in future AT89 products. Timer 2 interrupt is generated by the logical OR of bits TF2 and EXF2 in register T2CON. Neither of these flags is cleared by hardware when the service routine is vectored to. In fact, the service routine may have to determine whether it was TF2 or EXF2 that generated the interrupt, and that bit will have to be cleared in software. The Timer 0 and Timer 1 flags, TF0 and TF1, are set at S5P2 of the cycle in which the timers overflow. The values are then polled by the circuitry in the next cycle. However, the Timer 2 flag, TF2, is set at S2P2 and is polled in the same cycle in which the timer overflows.Reference data:1. the ATMEL company AT89S52 technical manuals2.Shenzhen Development Co., Ltd. AT89C523.Fudan University Press, single-chip microprocessor theory, application and test ZHANG You-de, etc.基于AT89C52的LED概述LED（Light Emitting Diode），发光二极管，是一种固态的半导体器件，它可以直接把电转化为光。
二氧化碳点阵激光英文缩写
二氧化碳点阵激光英文缩写Title: Fractional CO2 Laser: A Revolutionary Skin Rejuvenation Technique.The Fractional CO2 Laser, commonly abbreviated as FCL, has revolutionized the field of skin rejuvenation and aesthetic dermatology. This advanced technology utilizes the principles of fractional photothermolysis to deliver precise and targeted laser energy to the skin, resulting in remarkable improvements in skin texture, tone, and overall appearance.The Fractional CO2 Laser works by creating microscopic treatment zones within the skin, while sparing the surrounding tissue. This approach allows for more precise and controlled laser energy delivery, minimizing collateral damage to the surrounding skin. The treated areas undergo a controlled injury response, stimulating the production of new collagen and elastin, which are essential for maintaining skin firmness and elasticity.The results of Fractional CO2 Laser treatment are truly remarkable. Patients can expect significant improvements in skin texture, fine lines, wrinkles, acne scars, and other skin imperfections. The treated skin appears smoother, firmer, and younger-looking, with a noticeable improvement in overall skin quality.The Fractional CO2 Laser is suitable for a wide range of skin types and conditions, making it a popular choice among dermatologists and aestheticians. However, it is important to note that this treatment is not suitable for all skin concerns, and it is essential to consult with a qualified professional to determine if Fractional CO2 Laser is the right choice for you.The treatment process itself is relatively straightforward. A topical anesthetic may be applied to the treatment area to minimize discomfort during the procedure. The laser is then applied to the skin, targeting the desired treatment zones. The entire treatment typically takes between 30 minutes and an hour, depending on the sizeand condition of the treatment area.Recovery from Fractional CO2 Laser treatment is generally well-tolerated. Patients may experience some redness, swelling, and discomfort for a few days following the treatment. However, these symptoms typically resolve within a week, and most patients are able to resume their normal activities soon after the procedure.The long-term benefits of Fractional CO2 Laser treatment are truly transformative. By stimulating the production of new collagen and elastin, this treatment not only improves the appearance of the skin but also helps to maintain its health and vitality over time. With regular maintenance treatments, patients can enjoy younger-looking, healthier skin for years to come.In conclusion, the Fractional CO2 Laser is a powerful tool in the field of aesthetic dermatology, offering remarkable improvements in skin texture, tone, and overall appearance. Its precision and effectiveness have made it a popular choice among patients seeking a non-invasiveapproach to skin rejuvenation. If you are considering a skin rejuvenation treatment, Fractional CO2 Laser may be the perfect choice for you. Be sure to consult with a qualified professional to learn more about this exciting technology and how it can help you achieve your desired skin appearance.。
LED发展及应用中英文对照外文翻译文献
中英文对照外文翻译文献(文档含英文原文和中文翻译)译文:LED发展及应用我们相信我国LED产业具有良好的发展前景，基于以下几点：第一，在技术方面LED 技术处于高速增长的瓶颈，国内长期积累在半导体领域研究资源为进一步研究打下了良好的基础。
虽然集成电路制造的基础差，技术水平相对较低，但是随着一些国内企业海外技术人员加入，技术不断的突破，国内企业的良好技术水平、企业与台湾的技术水平与国际公司作为一个整体，已经缩小了差距。
第二，投资相对较小的初始投资1亿，国内企业进入的门槛低，容易导致滚动发展。
制造集成电路和液晶面板制造商数百亿数十亿元的投资都是“微不足道”的，更容易使国内企业形成产业集群。
当然，还可能导致恶性竞争和发展阶段的市场整合。
第三，国内市场大，LED市场主要是普通照明市场，消费者市场分散，难以形成垄断一个巨大的国内企业的生存空间。
第四，一些企业的核心知识产权，如晶体硅光伏衬底项目，美国的面积和芯片的核心技术，具有全球竞争力的企业技术发展的示范效应容易形成和促进国内商业市场的健康发展。
第五，成熟的技术导致下游的劳动密集型生产,包装和设备的发展与大陆劳动力具有成本优势。
LED行业的开发过程中，全球的LED销售根据市场目前最大的手机背光市场，与手机销售增长放缓提高了LED屏幕手机液晶屏幕渗透的全球LED的增长率。
技术进步降低了成本，在当前（甚至2010年以前）允许完全访问一般使用LED照明市场在全球经济增长下将成为下一个液晶笔记本和汽车室内灯背光市场。
作为世界五大液晶面板(LG飞利浦、三星、友达、CMO和夏普)LED的一个高水平的技术，大量生产能力在日本、台湾、韩国。
国内只有央行、波兰电力和五个龙光伏电池板三行，4.5代上海天马生产线需求后能使用LED 背光，但整体需求不占主导地位，国内企业进入液晶屏背光使供应链收益不应太大面板背光手机市场非常相似。
中国市场应用LED在这个阶段主要是在建筑照明、室内外显示屏。
LED照明常用英文翻译对照
LED照明常用英文翻译对照1backplane背板2Bandgapvoltagereference带隙电压参考3benchtopsupply工作台电源4BlockDiagram方块图5BodePlot波特图6Bootstrap自举7BottomFETBottomFET8bucketcapcitor桶形电容9chassis机架10Combi-senseCombi-sense11constantcurrentsource恒流源12CoreSataration铁芯饱和13crossoverfrequency交叉频率14currentripple纹波电流15CyclebyCycle逐周期16cycleskipping周期跳步17DeadTime死区时间18DIETemperature核心温度19Disable非使能，无效，禁用，关断20dominantpole主极点21Enable使能，有效，启用22ESDRatingESD额定值23EvaluationBoard评估板24Exceedingthespecificationsbelowmayresultinpermanent damagetothedevice,ordevicemalfunction.Operationoutsideofthe parametersspecifiedintheElectricalCharacteristicssectionisnotimplied.超过下面的规格使用可能引起永久的设备损害或设备故障。
建议不要工作在电特性表规定的参数范围以外。
25Faillingedge下降沿26figureofmerit品质因数27floatchargevoltage浮充电压28flybackpowerstage反驰式功率级29forwardvoltagedrop前向压降30free-running自由运行31Freewheeldiode续流二极管32Fullload满负载33gatedrive栅极驱动34gatedrivestage栅极驱动级35gerberplotGerber图36groundplane接地层37Henry电感单位：亨利38HumanBodyModel人体模式39Hysteresis滞回40inrushcurrent涌入电流41Inverting反相42jittery抖动43Junction结点44Kelvinconnection开尔文连接45LeadFrame引脚框架46LeadFree无铅47level-shift电平移动48Lineregulation电源调整率49loadregulation负载调整率50LotNumber批号51LowDropout低压差52Miller密勒53node节点54Non-Inverting非反相55novel新颖的56offstate关断状态57Operatingsupplyvoltage电源工作电压58outdrivestage输出驱动级59OutofPhase异相60PartNumber产品型号61passtransistorpasstransistor62P-channelMOSFETP沟道MOSFET 63Phasemargin相位裕度64PhaseNode开关节点65portableelectronics便携式电子设备66powerdown掉电67PowerGood电源正常68PowerGroud功率地69PowerSaveMode节电模式70Powerup上电71pulldown下拉72pullup上拉73PulsebyPulse逐脉冲（PulsebyPulse）74pushpullconverter推挽转换器75rampdown斜降76rampup斜升77redundantdiode冗余二极管78resistivedivider电阻分压器79ringing振铃80ripplecurrent纹波电流81risingedge上升沿82senseresistor检测电阻83SequencedPowerSupplys序列电源84shoot-through直通，同时导通85strayinductances.杂散电感86sub-circuit子电路87substrate基板88Telecom电信89ThermalInformation热性能信息90thermalslug散热片91Threshold阈值92timingresistor振荡电阻93TopFETTopFET94Trace线路，走线，引线95Transferfunction传递函数96TripPoint跳变点97turnsratio匝数比，＝Np/Ns。
LED显示屏外文翻译
附录3 中英文翻译The led manifestation holdThe LED manifestation hold(LED panel):The LED is a light emitting diode, give out light the English abbreviation of diode, brief name LED. It is 1 kind to passThe control semi-conductor give out light diode of manifestation way, it probably of appearance be from a lot of usually is red of the small light constitute, depend light of bright put out to manifestation character list. Using to the manifestation writing, sketch, picture, animation, condition of the market, video frequency and recording image signal's etc. is various manifestation screen of information.The LED manifestation hold to is divided into a diagram text's manifestation to hold with video frequency manifestation hold, is all constitute by LED matrix piece. The diagram text's manifestation hold can with calculator synchronous manifestation Chinese characters, English The text text origin and sketch，The video frequency manifestation hold adoption microcomputer to carry on control, diagram text, picture combine luxuriant, with solid hour, synchronous, clear information dissemination the way sow Putting various information, returning can manifestation two dimensions, 3D animation, record image, television, VCD program and the spot actual condition. The LED manifestation hold a manifestation an appearance color fresh and gorgeous, Stereoscopic the feeling be strong, quiet like oil painting, move like movie, extensive application in finance, tax administration, industry and business, post and tele, athletics, advertisement, factory mineral business enterprise, transportation, Teach system station, wharf, airport, market, hospital, guest house, bank, stock market, building market, sale line, industry business enterprise management and other public place.The LED's manifestation hold can manifestation variety of numeral, writing, sketch picture，Can not only used for an indoor environment but also used for outdoors environment, have to cast shadow an instrument, television wall, LCD manifestation to hold the advantage that can't compare to.The reason that, the LED be extensively valued but get quick development, is with it have of advantage inseparable. These advantages summarize BE，Bright degree Gao, work the electric voltage be low, achievement consume small and small scaled turn, life span long, bear pound at and function stability. The LED development foreground is extremely vast, currently just toward the higher and bright degree, higher bear weather, higherly give out light density and higherly give out light even, the credibility, whole color turn a direction development.the LED manifestation hold a development process 30 year review1970's at the earliest stage of GaP, GaAsP together quality knot red, Huang, green low give out light the LED of efficiency a beginning already application at the indicator, numeral and writing manifestation .From now on the LED start get into a variety application realm and include astronautics, airplane, car, industry application, correspondence, consume type product etc., all over each section of national economy and thousand 10000.To 1996 LED is in the whole world of sale sum already arrive several USD 1,000,000,000.Though the LED has been be subjected to a color and give out light therestriction of efficiency over several years, have a longevity life because of the GaP and the GaAsP LED, Gao credibility, work the electric current be small, can and TTL, CMOS numeral electric circuit and permit many advantage of etc. as a result has been be subjected to the green Mi of user. Recent decade, Gao Liang4 Du4 turn, whole color's turn has been being LED material and spare part craft technique research of front follow a topic. The extremely high and bright degree(UHB) is that give out light strength to attain or more than 100 mcd LED, call hole again virtuous pull(cd) class LED. Gao Liang4 Du4 the A1 GaInP and InGaN LED develop to make progress very quick, now already arrive normal regulations material GaA1 As, GaAsP, GaP impossible attain of function level.1991 Toshiba in Japan company and the United States the HP company develop into the InGaA1 P 620 nm an orange and extremely high and bright degree LED, 1992 the InGaA1 p 590 nm yellow extremely high and bright degree the LED be practical to turn At the same year, Toshiba company develop the InGaA1 P 573 nm Huang green an extremely high and bright degree LED, method to light as strong as 2 cd.1994 Japan day the second company develop into InGaN450 nm blue(green) color extremely high and bright degree LED. Go to this, color manifestation three Ji colors need be red, green, blue and orange, Huang variety the LED of the color all come to a hole virtuous pull give out light of class strength, realization the extremely high and bright degree turn, the whole color turn and make to give out light tube of outdoor whole color manifestation become reality. Our country development LED start in 70's, the industry appear in 80's.There is around more than 100 business enterprise in whole country, 95% factory house all be engaged in behind way pack produce, need tube Xin almost all from the abroad import. Pass the technique of a few "five years plan" reformation, the technique offend pass and usher in abroad forerunner equipments and parts of key technique, make our country LED of produce the technique have already step forward into one step.Two, extremely high and bright degree LED function:The extremely high and bright degree red A1 GaAsLED and GaAsP-GaP LED compare, have to higherly give out light an efficiency, the flow of transparent Chen low(TS) A1 GaAs LED(640 nm) clear efficiency already close 10 lm/w, ratio the red GaAsP-GaP LED big 1000%.Color and GaAsP-GaP that the extremely high and bright degree InGaAlP LED provide LED homology include，academy blue(560 nm), shallow academy blue(570 nm), yellow(585 nm), shallow Huang(590 nm),orange(605 nm) and pink(625 nm deep red.(640 nm)The transparent Chen bottom A1 GaInP LED give out light an efficiency and the other LED structure and white Chi light source of comparison, the InGaAlP LED absorb the flow of Chen bottom(AS) clear efficiency as 101 m/w, the transparent Chen bottom(TS) want to be 10 －s in height than the GaAsP-GaP flow of LED clear efficiency within the scope of the wave-length of 590 －626 nm for the 201 m/w 2000%;In 560 －s 570 wave-length scopes ratio GaAsP-GaP LED Gao Chu's 2 －s 400%.The extremely high and bright degree InGaN LED provided an orchid color light and green light, its wave-length scope orchid color is 450 －480 nm, orchid green is 500 nm, green is 520 nm，It flow the clear efficiency as 3 －151 m/ws. Extremely high and bright degree LEDcurrently flow a clear efficiency have already exceeded to take the incandescent lamp of color filter, can replace the power incandescent lamp within 1 w, and use a LED array can replace the power incandescent lamp within 150 w. For many application, all of incandescent lamps be an adoption color filter to get red, orange, green and orchid color, but use an extremely high and bright degree LED can then get homology of color. The extremely high and bright degree of the material and InGaN material manufacturing of the recent years AlGaInP LED many extremely high and bright degree LED chip combination together, need not color filter also ability get various color. Include red, orange, Huang, green and blue, currently its giving out light an efficiency all have already exceeded an incandescent lamp, is connecting toward the fluorescent lamp near. Give out light a bright degree Gao have already canned satisfy outdoors at the 1000 mcd all-weather, whole color manifestation of demand, use LED color big screen can performance the sky and ocean, realization 3D animation. The new generation red, green and blue and extremely high and bright degree LED come to an unprecedented function.Three, extremely high and bright degree LED application:rmation indicatorCar signal designation，car indicator's exterior in car's being main be a turn signal, tail lamp and brake light，Main is various appearance in the inner part of car of illuminate and manifestation. The extremely high and bright degree LED used for car indicator and the incandescent lamp of tradition to compare to have many advantage, in the car industry have extensive of market .The LED can experience a stronger machine to pound at and vibrate. Average work life span MTBF ratio incandescent lamp bubble Gao Chu Ji3 quantity class, far far Gao Chu's car of work life span, so flow bottom work, typical model of drive electric current an incandescent lamp to only at least have 12 red, yellow, blue green signal beacon.2.great screen manifestationGreat screen manifestation is extremely high and bright degree LED application of another one huge market, include，color and whole color of the monochrome, double of the sketch, writing, numeral manifestation. Tradition of the big screen have a source manifestation general adoption incandescent lamp, fiber optic, cathode ray tube etc.，Have no source manifestation general adoption turn over the method of card .Form 3 listed a few kinds manifestation of function comparison. The LED manifestation once had been be subjected to LED function and the restriction of the color .Now the extremely high and bright degree AlGaInP, TS-AlGaAs, InGaN LED have already can provide brightness of red, Huang, various green and blue color, can complete satisfy realization whole color big screen manifestation of request. LED manifestation hold can assemble into various structure according to the pixel size, figurine vegetable diameter general small at the 5 mm, monochrome manifestation of each pixel use a LED light of T-1(3/4), double color manifestation of each pixel is double the LED light of T-1(3/4) of the color, whole color manifestation demand 3T-1 be red, green, blue light, perhaps assemble much aer LED light of T-1(3/4) of chip be a pixel. The big pixel then pass pair of many T-1(3/4) red, green, the blue LED light combination together constitute e InGaN(480 nm) blue, InGaN's(515nm) being green be three Ji colors of LED manifestation with the ALGaAS(637 nm) red LED light, can provide a lifelike whole color function, and have bigger color scope to include: blue and green and green and red etc., with international television system committee(NTSC) provision of television color the scope be basic to agree with.3.the LCD manifestation(LCD) carry on the back to illuminateHave 10% adoption to have source light as to carry on the back illuminate atleast in the LCD manifestation, the light source can make LCD manifestation hold of dark of environment bottom easy read, whole color LCD manifestation also demand light source. The LCD carry on the back to illuminate the light source need main have，incandescent lamp bubble, field with the result that give out light, cold cathode fluorescence, LED etc., they be listed on form 4 carry on comparison, among them,the LED have a competition ability most in the LCD carry on the back the lighting,the new extremely high and bright degree AlGaInP, AlGaAs, InGaN LED can provide to high-efficiencily give out light with the color of breadth scope.The LED used for LCD to carry on the back to illuminate main have three kinds of way.(1)Most simple is LED light direct install spread to shoot a film in the LCD of behind, can use many pack of LED light, they should have very breadth of light beam Cape with make stalk to light the even be better. Can also adoption don't pack of tube Xin, general use GaP LED, however use AlGaInP, TS-AlGaAs LED can then under the small electric current work, let up achievement consume.(2)Another a way are an edge light the LCD carry on the back illuminate and use a transparent or translucent rectangle plastics a piece conduct and actions lead light body, is direct it install to spread to shoot a film in the LCD of behind, plastics piece of empress surface Tu2 Shang4 white reflection material, LED light shoot from a flank of plastics piece go into, rest the flank make with white reflection material.(3)LED send out of light ducting fiber optic bunch in, fiber optic bunch of spread and shoot film behind constitute a flat of thin slice, can use dissimilarity of method's taking out from the thin slice the light be a carry on the back of LCD illuminate .Adoption LED conduct and actions carry on the back illuminate of the liquid crystal display can used for ambulation telephone, notebook, along with the small scaled liquid crystal display isin the stanza the electricity the type the correspondence the product of extensive usage, will have greater need to the extremely high and bright degree LED.4.the solid shine on a lightWhole color extremely high and bright degree LED of practical turn with commercialize, make to illuminate a technique to face a new of revolution, solid floodlight make into by many extremely high and bright degree red, blue and green three color LEDses not only can send out a wave-length continuous various adjustable color light, and also can send out a bright degree can reach several 10-100 candlelights of white become lighting light source .Recen Japan day second company make use of its InGaN be blue light LED and fluorescence technique, again released white light the solid give out light a spare part product, its color is 6500 K, the efficiency reach each tile 7.5 flow clear .For homology give out light incandescent lamp and LED solid floodlight of bright degree to say, the achievement of the latterconsume a have the former of 10% －be 20% and the life span of the incandescent lamp's being general be not over 2000 hours, but the life span of the LED light be as long as tens of thousands hours. This kind of physical volume is small, the weight be light and directive good, economy energy, life span long, bear various bad condition of solid light source necessarily will to tradition of the light source market result in pound at. Though this kind of is new to illuminate the cost of solid light source still higher, can application like mineral mountain at some special situation, dive, rob insurance, for use by the military equip of illuminate etc From farsighted see, if the LED the further extension of the production scale of the extremely high and bright degree, cost further lower, it at economy energy and longevity life of the advantage is good enough to make up its price higher bad situation .The extremely high and bright degree LED will probably become a kind of new lightning source which have much of a competition ability.LED显示屏LED显示屏：LED就是light emitting diode ，发光二极管的英文缩写，简称LED。
led照明中英文对照外文翻译文献
(文档含英文原文和中文翻译)中英文资料外文翻译文献Renewable and Sustainable Energy ReviewsHigh-brightness LEDs—Energy efficient lighting sources and their potential in indoor plant cultivation ABSTRACTThe rapid development of optoelectronic technology since mid-1980 has significantly enhanced the brightness and efficiency of light-emitting diodes (LEDs). LEDs have long been proposed as a primary light source for space-based plant research chamber or bioregenerative life support systems. The raising cost of energyalso makes the use of LEDs in commercial crop culture imminent. With their energy efficiency, LEDs have opened new perspectives for optimizing the energy conversion and the nutrient supply both on and off Earth. The potentials of LED as an effective light source for indoor agriculturalproduction have been explored to a great extent. There are many researches that use LEDs to support plant growth in controlled environments such as plant tissue culture room and growth chamber. This paper provides a brief development history of LEDs and a broad base review on LED applications in indoor plant cultivation since 1990.Contents1. Introduction2. LED development.3. Color ratios and photosynthesis4. LEDs and indoor plant cultivation.4.1. Plant tissue culture and growth4.2. Space agriculture84.3. Algaculture4.4. Plant disease reduction5. Intermittent and photoperiod lighting and energy saving6. Conclusion1. IntroductionWith impacts of climate change, issues such as more frequent and serious droughts, floods, and storms as well as pest and diseases are becoming more serious threats to agriculture. These threats along with shortage of food supply make people turn to indoor and urban farming (such as vertical farming) for help. With proper lighting, indoor agriculture eliminates weather-related crop failures due to droughts and floods to provide year-round crop production, which assist in supplying food in cities with surging populations and in areas of severe environmental conditions.The use of light-emitting diodes marks great advancements over existing indoor agricultural lighting. LEDs allow the control of spectral composition and the adjustment of light intensity to simulate the changes of sunlight intensity during the day. They have the ability to produce high light levels with low radiant heat output and maintain useful light output for years. LEDs do not contain electrodes and thus do not burn out like incandescent or fluorescent bulbs that must be periodically replaced. Not to mention that incandescent and fluorescent lamps consume a lot of electrical power while generating heat, which must be dispelled from closed environments such as spaceships and space stations.2. LED developmentLED is a unique type of semiconductor diode. It consists of a chip of semiconductor material doped with impurities to create a p–n junction. Current flows easily from the p-side (anode), to the n-side (cathode), but not in the reverse direction.Electrons and holes flow into the junction from electrodes with different voltages. When an electron meets a hole, it falls into a lower energy level, and releases energyin the form of a photon. The color (wavelength) of the light emitted depends on the band gap energy of the materials forming the p–n junction. The materials used for an LED have a direct band gap with energies corresponding to near-infrared, visible or near-ultraviolet light.The key structure of an LED consists of the die (or light-emitting semiconductor material), a lead frame where the die is placed, and the encapsulation which protects the die (Fig. 1).Fig.1LED development began with infrared and red devices made with gallium arsenide. Advances in materials science have made possible the production of devices with ever-shorter wavelengths, producing light in a variety of colors. J.Margolin reported that the first known light-emitting solid state diode was made in 1907 by H. J. Round. No practical use of Round’s diode was made for several decades until the invention of the first practical LED by Nick Holonyak, Jr in 1962. His LEDs became commercially available inlate 1960s. These GaAsP LEDs combine three primary elements: gallium, arsenic and phosphorus to provide a 655nm red light with brightness levels of approximately 1–10 mcd at 20mA. As the luminous intensity was low, these LEDs were only used in a few applications, primarily as indicators. Following GaAsP, GaP (gallium phosphide) red LEDs were developed. These device sex hibit very high quantum efficiencies at low currents. As LED technology progressed through the 1970s, additional colors and wavelengths became available.The most common materials were GaP green and red, GaAsP orange, and high efficiency red and GaAsP yellow. The trend towards more practical applications (such as in calculators, digital watches, and test equipment) also began to develop. As the LED materials technology became more advanced, the light output was increased, and LEDs became bright enough to be used for illumination.In 1980s a new material, GaAlAs (gallium aluminum arsenide) was developed followed by a rapid growth in the use of LEDs. GaAlAs technology provides superior performance over previously available LEDs. The voltage requirement is lower, which results in a total power savings. LEDs could be easily pulsed or multiplexed and thus are suitable for variable message and outdoor signs. Along this development period, LEDs were also designed into bar code scanners, fiber optic data transmission systems, and medicalequipment. During this time, the improvements in crystal growth and optics design allow yellow, green and orange LEDs only a minor improvement in brightness and efficiency. The basic structure of the material remained relatively unchanged.As laser diodes with output in the visible spectrum started to commercialize in late 1980s, LED designers used similar techniques to produce high-brightness and high reliability LEDs. This led to the development of InGaAlP (indium gallium aluminum phosphide) visible light LEDs. Via adjusting the energy band gap InGaAlP material can have different color output. Thus, green, yellow, orange and red LEDs could all be produced using the same basic technology. Also, light output degradation of InGaAlP material is significantly improved.Shuji Nakamura at Nichia Chemical Industries of Japan introduced blue LEDs in 1993. Blue LEDs have always been difficult to manufacture because of their high photon energies (>2.5 eV) and relatively low eye sensitivity. Also, the technology to fabricate these LEDs is very different and less advanced than standard LED materials. But blue is one of the primary colors (the other two being red and green). Properly combining the red, green, and blue light is essential to produce white and full-color. This process requires sophisticated software and hardware design to implement. In addition, the brightness level is low and the overall light output of each RGB die being used degrades at a different rate resulting in an eventual color unbalance. The blue LEDs available today consist of GaN (gallium nitride) and SiC (silicon carbide) construction. The blue LED that becomes available in production quantities has result in an entire generation of new applications that include telecommunications products, automotive applications, traffic control devices, and full-color message boards. Even LED TVs can soon become commercially available.Compare to incandescent light’s 1000-h and fluorescent light’s 8000-h life span, LEDs have a very significantly longer life of 100,000 h. In addition to their long life, LEDs have many advantages over conventional light source. These advantages include small size, specific wavelength, low thermal output, adjustable light intensity and quality, as well as high photoelectric conversion efficiency. Such advantages make LEDs perfect for supporting plant growth in controlled environment such as plant tissue culture room and growth chamber. Table 1 is a list of some common types of LEDs as compiled from .The chlorophyll molecules in plants initiate photosynthesis bycapturing light energy and converting it into chemical energy to help transforming water and carbon dioxide into the primary nutrient for living beings. The generalized equation for the photosynthetic process is given as:CO2 + H2O—light—>（CH2O）+ O2where (CH2O) is the chemical energy building block for thesynthesis of plant components.Chlorophyll molecules absorb blue and red wavelengths most efficiently. The green and yellow wavelengths are reflected or transmitted and thus are not as important in the photosyntheticprocess. That means limit the amount of color given to the plants and still have them grow as well as with white light. So, there is no need to devote energy to green light when energy costs are aconcern, which is usually the case in space travel.The LEDs enable researchers to eliminate other wavelengths found within normal white light, thus reducing the amount of energy required to power the plant growth lamps. The plants grow normally and taste the same as those raised in white light.Red and blue light best drive photosynthetic metabolism. These light qualities are particularly efficient in improving the developmental characteristics associated with autotrophic growth habits. Nevertheless, photosynthetically inefficient light qualities also convey important environmental information to a developing plant. For example, far-red light reverses the effect of phytochromes, leading to changes in gene expression, plant architecture, and reproductive responses. In addition, photoperiod (the adjustment of light and dark periods) and light quality (the adjustment of red, blue and far-red light ratio) also have decisive impacts on photomorphogenesis.The superimposed pattern of luminescence spectrum of blue LED (450–470 nm) and that of red LED (650–665 nm) corresponds well to light absorption spectrum of carotenoids and chlorophyll. Various plant cultivation experiments are possible whenthese twokinds of LED are used with the addition of far-red radiation (730–735 nm) as the light source. Along the line of the LED technology advancement, LEDs become a prominent light source for intensive plant culture systems and photobiological researches. The cultivation experiments which use such light sources are becoming increasingly active. Plant physiology and plant cultivation researches using LEDs started to peak in 1990s and become inevitable in the new millennium. Those researches have confirmed that LEDs are suitable for cultivation of a variety of algae, crop, flower, fruit, and vegetable.Some of the pioneering researches are reviewed in the followings.Bula et al. have shown that growing lettuce with red LEDs in combination with blue tubular fluorescent lamp (TFL) is possible. Hoenecke et al. have verified the necessity of blue photons for lettuce seedlings production by using red LEDs with blue TFL. As the price of both blue and red LEDs have dropped and the brightness increased significantly, the research findings have been able to be applied in commercial production. As reported by Agence France Press, Cosmo Plant Co., in Fukuroi, Japan has developed a red LED-based growth process that uses only 60% of electricity than a fluorescent lighting based one.Tennessen et al. have compared photosynthesis from leaves of kudzu (Pueraria lobata) enclosed in a leaf chamber illuminated by LEDs versus by a xenon arc lamp. The responses of photosynthesis to CO2 are similar under the LED and xenon arc lamps at equal photosynthetic irradiance. There is no statistical significant difference between the white light and red light measurements in high CO2. Some leaves exhibited feedback inhibition of photosynthesis which is equally evident under irradiation of either lamp type. The results suggest that photosynthesis research including electron transport, carbon metabolismand trace gas emission studies should benefit greatly from the increased reliability, repeatability and portability of a photosynthesis lamp based on LEDs.Okamoto et al. have investigated the effects of different ratios of red and blue (red/blue) photosynthetic photon flux density (PPFD) levels on the growth and morphogenesis of lettuce seedlings. They have found that the lettuce stem length decreases significantly with an increase in the blue PPFD. The research has also identified the respective PPFD ratio that (1) accelerates lettuce seedlings’stem elongation, (2) maximizes the whole plant dry weight, (3) accelerates the growth of whole plants, and (4) maximizes the dry weights of roots and stems. Photosynthesis does not need to take place in continuous light. The solid state nature allows LEDs to produce sufficient photon fluxes and can be turned fully on and off rapidly (200 ns), which is not easily achievable with other light sources. This rapid on–off feature has made LEDs an excellent light source for photosynthesis research such as pulsed lighting for the study of photosynthetic electron transport details. The off/dark period means additional energy saving on top of the LEDs’low power consumption.4. LEDs and indoor plant cultivation4.1. Plant tissue culture and growthTissue culture (TC), used widely in plant science and a number of commercial applications, is the growth of plant tissues or cells within a controlled environment, anideal growth environment that is free from the contamination of microorganisms and other contaminants. A controlled environment for PTC usually means filtered air, steady temperature, stable light sources, and specially formulated growth media (such as broth or agar). Micropropagation, a form of plant tissue culture (PTC), is used widely in forestry and floriculture. It is also used for conserving rare or endangered plant species. Other uses of PTC include:1short-term testing of genetic constructions or regeneration oftrans genic plants,2 cross breeding distantly related species and regeneration of the novel hybrid,3 screening cells for advantageous characters (e.g. herbicidere sistance/tolerance), 4embryo rescue (i.e. to cross-pollinate distantly related specie sand then tissue culture there sulting embryo which would normally die),5 large-scale growth of plant cells in liquid culture inside bioreactors as a source of secondary products (like recombinant proteins used as biopharmaceuticals).6production of doubled monoploid plants from haploid cultures to achieve homozygous lines more rapidly in breeding programs (usually by treatment with colchicine which causes doubling of the chromosome number).Tissue culture and growth room industries have long been using artificial light sources for production. These light sources include TFL, high pressure sodium lamp (HPS), metal halide lamp (MHL) and incandescent lamp, etc. Among them, TFL has been the most popular in tissue culture and growth room industries. However, the use of TFL consumes 65% of the total electricity in a tissue culture lab. That is the highest non-labor costs. As a result, these industries continuously seek for more efficient light sources. The development of high-brightness LED has made LED a promising light source for plant growth in controlled environments.Nhut et al. have cultured strawberry plantlets under different blue to red LED ratios as well as irradiation levels and compared its growth to that under plant growth fluorescent. The results suggest that a culture system using LED is advantageous for the micropropagation of strawberry plantlets. The study also demonstrates that the LED light source for in vitro culture of plantlets contributes to an improved growth of the plants in acclimatization.Brown et al. have measured the growth and dry matter partitioning of ‘Hungarian Wax’pepper (Capsicum annuum L.) plants grown under red LEDs compared with similar plants grown under red LEDs with supplemental blue or far-red radiation. Pepper biomass reduces when grown under red LEDs without blue wavelengths compared to plants grown under supplemental blue fluorescent lamps. The addition of far-red radiation results in taller plants with greater stem mass than red LEDs alone. Fewer leaves developed under red or red plus far-red radiation than with lamps producing blue wavelengths. The results of their research indicate that with proper combination of other wavelengths, red LEDs may be suitable for the culture of plants in tightly controlled environments.4.2. Space agricultureBecause re-supply is not an option, plants are the only options to generate enough food, water and oxygen to help make future explorers self-sufficient at space colonies on the moon, Mars or beyond. In order to use plants, there must be a lightsource. Standard light sources that used in homes and in greenhouses and in growth chambers for controlled agriculture here on Earth are not efficient enough for space travel. While a human expedition outside Earth orbit still might be years away, the space farming efforts are aimed at developing promising artificial light sources. LEDs, because of their safety, small mass and volume, wavelength specificity, and longevity, have long been proposed as a primary light source for space-base plant research chamber or bioregenerative life support systems .Infrared LEDs that are used in remote controls devices have other uses. Johnson et al. have irradiated oat (Avena sativa cv Seger) seedlings with infrared (IR) LED radiation passed through a visible-light-blocking filter. The irradiated seedlings exhibited differences in growth and gravitropic response when compared to seedlings grown in darkness at the same temperature. This suggests that the oat seedlings are able to detect IR LED radiation. These findings also expand the defined range of wavelengths involved in radiation–gravity (light–gravity) interactions to include wavelengths in the IR region of the spectrum.Goins et al. grow wheat under red LEDs and compare them to the wheat grown under (1) white fluorescent lamps and (2) red LEDs supplemented with blue light from blue fluorescent lamps. The results show that wheat grown under red LEDs alone displayed fewer subtillers and a lower seed yield compared to those grown under white light. Wheat grown under red LEDs + 10% BF light had comparable shoot dry matter accumulation and seed yield relative to those grown under white light. These results indicate that wheat can complete its life cycle under red LEDs alone, but larger plants and greater amounts of seed are produced in the presence of red LEDs supplemented with a quantity of blue light.The research of Goins and his team continues in plant growth chambers the size of walk-in refrigerators with blue and red LEDs to grow salad plants such as lettuce and radishes. They hope the plant growth chamber would enable space station staff to grow and harvest salad greens, herbs and vegetables during typical fourmonth tours on the outpost .4.3. AlgacultureAlgaculture, refers to the farming of species of algae, has been a great source for feedstock, bioplastics, pharmaceuticals, algae fuel, pollution control, as well as dyes and colorants. Algaculture also provides hopeful future food sources.Algae can be grown in a photobioreactor (PBR), a bioreactor which incorporates some type of light source. A PBR is a closed system, as opposed to an open tank or pond. All essential nutrients must be introduced into the system to allow algae to grow and be cultivated. A PBR extends the growing season and allows growing more species. The device also allows the chosen species to stay dominant. A PBR can either be operated in ‘‘batch mode’’or ‘‘continuous mode’’in which a continuous stream of sterilized water that contains air, nutrients, and carbon dioxide is introduced. As the algae grows, excess culture overflows and is harvested.When the algae grow and multiply, they become so dense that they block light from reaching deeper into the water. As a result, light only penetrates the top 7–10 cm of the water in most algalcultivation systems. Algae only need about 1/10 theamount of direct sunlight. So, direct sunlight is often too strong for algae. A means of supplying light to algae at the right concentration is to place the light source in the system directly.Matthijs et al. have used LEDs as the sole light source in continuous culture of the green alga (Chlorella pyrenoidosa). The research found the light output of the LED panel in continuous operation sufficient to support maximal growth. Flash operation at 5-ps pulse ‘‘on’’ duration between dark periods of up to 45 ps would still sustain near maximum growth. While longer dark periods tend to cut the growth rate, the light flux decrease resulting from such operation does not reduce the growth as much as that of the similar flux decrease in continuous operation. Their research concludes that the use of flashing LEDs (which means intermittent light) in indoor algal culture yielded a major gain in energy economy comparing to fluorescent light sources. An additional advantage is that heat waste losses are much smaller. The most interesting discovery of this study may be that adding blue light to the red LED light did not change the growth properties.In order to take advantage of the biotechnological potential of algae, Lee and Palsson have calculated theoretical values of gas mass transfer requirements and light intensity requirements to support high-density algal cultures for the 680 nm monochromatic red light from LED as a light source. They have also designed a prototype PBR based on these calculations. Using on-line ultra filtration to periodically provide fresh medium, these researchers have achieved a cell concentration of more than 2×109cells/ml (more than 6.6%, vol/vol), cell doubling times as low as 12 h, and an oxygen production rate as high as 10 mmol oxygen/l culture/h. This research indicates that the development of a small LED-based algal photobioreactors is economically achievable.Another research of algae via LEDs is conducted by Nedbal et al. Their research is a study of light fluctuation effects on a variety of algae in dilute cultures using arrays of red LEDs to provide intermittent and equivalent continuous light in small-size (30 ml) bioreactors. The results endorse that the algae growth rates in certain calculated intermittent light can be higher than the growth rate in the equivalent continuous light. Yanagi and Okamoto has grown five spinach plants under the red LEDs and another five under 40W plant growth fluorescent lamps at the same light intensity of 125 mmol/m2/s. The dry matter production under the LEDs is slightly less than that under the fluorescent lamps. The plant leaf area under the red LEDs is also smaller than that under the fluorescent lamps. Nevertheless, they reach a conclusion that LEDs can qualify as an artificial light source for plant growth.4.4.Plant disease reductionSchuerger and Brown have used LED arrays with different spectral qualities to determine the effects of light on the development of tomato mosaic virus (ToMV) in peppers and powdery mildew on cucumbers. Their research concludes that spectral quality may alter plant disease development. Latter research regarding bacterial wilt on tomato has confirmed this conclusion and demonstrates that spectral quality may be useful as a component of an integrated pest management program for space-based ecological life support systems. Schuerger et al. have shown that the spectral qualityeffects on peppers’ anatomical changes in stem and leaf tissues are correlated to the amount of blue light in primary light source.Miyashita et al. use red LEDs (peak wavelength: 660 nm) and white fluorescent lamps as light sources for potato plantlets growth in vitro. They found that shoot length and chlorophyll concentration of the plantlets increases with increasing 630–690 nm red photon flux (R-PF) while there are no significant differences in dry weight and leaf area of the plantlets with different R-PF levels. This means red light affects the morphology rather than the growth rate of potato plantlets in vitro. As a result, they suggest that red LEDs can be used for controlling plantlet morphology in micropropagation.5. Intermittent and photoperiod lighting and energy savingTime constants for photosynthetic processes can be divided into three ranges: primary photochemistry, electron shuttling, and carbon metabolism. These three photosynthetic processes can be uncoupled by providing pulses of light within the appropriate range for each process. At high frequencies, pulsing light treatments can be used to separate the light reactions (light harvesting and charge separation) from the dark reactions (electron shuttling) of photosynthetic electron transport. LEDs’ flexible pulsating ability can be coupled with such characteristics of photosynthesis and lead to additional energy saving.Tennessen et al. use LEDs to study the effects of light pulses (micro- to milli-second) of intact tomato leaves. They found that when the equivalent of 50 mmol photons mp -2s-1 is provided during 1.5 ms pulses of 5000 mmol photons mp -2s-1 followed by 148.5 ms dark periods, photosynthesis is the same as in continuous 50 mmol photons mp -2s-1 . Data support the theory that photons in pulses of 100 ps or shorter are absorbed and stored in the reaction centers to be used in electron transport during the dark period. Pigments of the xanthophyll cycle were not affected by pulsed light treatments. This research suggests that, instead of continuous light, using effectively calculated intermittent light (which means less energy consumption) might not affect the plant production.Jao and Fang have investigated the effects of intermittent light on growth of potato plantlets in vitro. They also use conventional TFLs for the experiment to explore the electrical savings realized by adjusting the frequency and duty ratio of LEDs. TFLs provide continuous fluctuating light at 60 Hz while LEDs provide nonfluctuating light and pulse light of the preset frequency and duty ratio. When the growth rate is the only concern, LEDs at 720 Hz (1.4 ms) and 50% duty ratio with 16-h light/8-h dark photoperiod stimulated plant growth the most. When energy consumption is the major concern, using LEDs at 180 Hz (5.5 ms) and 50% duty ratio with 16-h light/8-h dark photoperiod would not significantly sacrifice plant growth, especially when energy for heat removal is also taken into account.6. ConclusionsThe first sustained work with LEDs as a source of plant lighting occurred in the mid-1980s when a lighting system for plant growth was designed for space shuttles and space stations for it is realized that people cannot go to the Moon, Mars, or beyond without first mastering the art of indoor farming on Earth. As the performanceof LED continues to improve, these lighting systems progress from red only LED arrays using the limited components available to high-density, multi-color LED chip-on-board technologies. Today, space age gardeners who have been testing high-efficiency light sources for future space colonists have identified energy efficient LEDs as the major light source not only to grow food but also to generate and purify oxygen and water—key sustainers of human life. The removal of carbon dioxide from a closed environment is another added benefit.LEDs are the first light source to provide the capability of true spectral composition control, allowing wavelengths to match to plant photoreceptors to optimize production as well as to influence plant morphology and composition. They are easily integrated into digital control systems, facilitating complex lighting programs like varying spectral composition over the course of a photoperiod or with plant development stage. LEDs do not contain mercury. They are safer to operate than current lamps since they do not have glass envelopes or high touch temperatures.While the process of photosynthesis does not require continuous light of full spectrum, LEDs can produce sufficient photon fluxes of specific wavelength on and off rapidly. Such mechanism of photosynthesis coupled with the solid state characteristics of LEDs constitute two ways of energy saving (cutting out unnecessary spectrum segment and turning off the light periodically) on top of the LEDs’ low power consumption. These are not easily achievable with other light sources.This paper provides a broad base review on LED applications in horticulture industry since 1990. These researches pave the way for the researches of similar types using different species and lead to comparable conclusion that LEDs are well qualified to replace its more energy demanding counterparts as controlled environment light source for agricultural research such as providing tissue culture lighting as well as supplemental and photoperiod lighting for greenhouses.With the energy it can save, LED’s becoming economically feasible in large-scale indoor farming lighting applications is just around the corner.再生可持续能源评论高亮高效节能LED灯的来源及其在室内植物栽培中的潜力摘要自1980年中期以来，光电子技术的迅猛发展，显著调高了发光二极管（LED）的亮度和效率。
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基于AT89C52的LED概述LED（Light Emitting Diode），发光二极管，是一种固态的半导体器件，它可以直接把电转化为光。
LED的心脏是一个半导体的晶片，晶片的一端附在一个支架上，一端是负极，另一端连接电源的正极，使整个晶片被环氧树脂封装起来。
半导体晶片由两部分组成，一部分是P型半导体，在它里面空穴占主导地位，另一端是N型半导体，在这边主要是电子。
但这两种半导体连接起来的时候，它们之间就形成一个“P-N结”。
当电流通过导线作用于这个晶片的时候，电子就会被推向P区，在P区里电子跟空穴复合，然后就会以光子的形式发出能量，这就是LED发光的原理。
而光的波长也就是光的颜色，是由形成P-N结的材料决定的。
LED历史50年前人们已经了解半导体材料可产生光线的基本知识，第一个商用二极管产生于1960年。
LED是英文light emitting diode（发光二极管）的缩写，它的基本结构是一块电致发光的半导体材料，置于一个有引线的架子上，然后四周用环氧树脂密封，即固体封装，所以能起到保护内部芯线的作用，所以LED的抗震性能好。
发光二极管的核心部分是由P型半导体和N型半导体组成的晶片，在P 型半导体和N型半导体之间有一个过渡层，称为P-N结。
在某些半导体材料的PN结中，注入的少数载流子与多数载流子复合时会把多余的能量以光的形式释放出来，从而把电能直接转换为光能。
PN结施加反向电压时，少数载流子难以注入，故不发光。
这种利用注入式电致发光原理制作的二极管叫发光二极管，通称LED。
当它处于正向工作状态时（即两端加上正向电压），电流从LED阳极流向阴极时，半导体晶体就发出从紫外到红外不同颜色的光线，光的强弱与电流有关。
最初LED用作仪器仪表的指示光源，后来各种光色的LED在交通信号灯和大面积显示屏中得到了广泛应用，产生了很好的经济效益和社会效益。
以12英寸的红色交通信号灯为例，在美国本来是采用长寿命、低光效的140瓦白炽灯作为光源，它产生2000流明的白光。
经红色滤光片后，光损失90%，只剩下200流明的红光。
而在新设计的灯中，Lumileds公司采用了18个红色LED光源，包括电路损失在内，共耗电14瓦，即可产生同样的光效。
汽车信号灯也是LED光源应用的重要领域。
对于一般照明而言，人们更需要白色的光源。
1998年白光的LED 开发成功。
这种LED是将GaN芯片和钇铝石榴石（YAG）封装在一起做成。
GaN芯片发蓝光（λp=465nm，Wd=30nm），高温烧结制成的含Ce3+的YAG荧光粉受此蓝光激发后发出黄色光射，峰值550nm。
蓝光LED基片安装在碗形反射腔中，覆盖以混有YAG的树脂薄层，约200-500nm。
LED基片发出的蓝光部分被荧光粉吸收，另一部分蓝光与荧光粉发出的黄光混合，可以得到得白光。
现在，对于InGaN/YAG白色LED，通过改变YAG荧光粉的化学组成和调节荧光粉层的厚度，可以获得色温3500-10000K的各色白光。
这种通过蓝光LED得到白光的方法，构造简单、成本低廉、技术成熟度高，因此运用最多。
上个世纪60年代，科技工作者利用半导体PN结发光的原理，研制成了LED发光二极管。
当时研制的LED，所用的材料是GaASP，其发光颜色为红色。
经过近30年的发展，现在大家十分熟悉的LED，已能发出红、橙、黄、绿、蓝等多种色光。
然而照明需用的白色光LED仅在近年才发展起来，这里向读者介绍有关照明用白光。
LED显示屏分为图文显示屏和视频显示屏，均由LED矩阵块组成。
图文显示屏可与计算机同步显示汉字、英文文本和图形；视频显示屏采用微型计算机进行控制，图文、图像并茂，以实时、同步、清晰的信息传播方式播放各种信息，还可显示二维、三维动画、录像、电视、VCD节目以及现场实况。
LED显示屏显示画面色彩鲜艳，立体感强，静如油画，动如电影，广泛应用于金融、税务、工商、邮电、体育、广告、厂矿企业、交通运输、教育系统、车站、码头、机场、商场、医院、宾馆、银行、证券市场、建筑市场、拍卖行、工业企业管理和其它公共场所。
LED显示屏可以显示变化的数字、文字、图形图像；不仅可以用于室内环境还可以用于室外环境，具有投影仪、电视墙、液晶显示屏无法比拟的优点。
LED之所以受到广泛重视而得到迅速发展，是与它本身所具有的优点分不开的。
这些优点概括起来是：亮度高、工作电压低、功耗小、小型化、寿命长、耐冲击和性能稳定。
LED的发展前景极为广阔，目前正朝着更高亮度、更高耐气候性、更高的发光密度、更高的发光均匀性，可靠性、全色化方向发展。
LED显示屏的分类 1、按颜色基色可以分为，单基色显示屏:单一颜色（红色或绿色）。
双基色显示屏：红和绿双基色，256级灰度、可以显示65536种颜色。
全彩色显示屏：红、绿、蓝三基色，256级灰度的全彩色显示屏可以显示一千六百多万种颜色。
2、按显示器件分类LED数码显示屏：显示器件为7段码数码管，适于制作时钟屏、利率屏等，显示数字的电子显示屏。
LED点阵图文显示屏：显示器件是由许多均匀排列的发光二极管组成的点阵显示模块，适于播放文字、图像信息。
LED视频显示屏：显示器件是由许多发光二极管组成，可以显示视频、动画等各种视频文件。
3、按使用场合分类，室内显示屏：发光点较小，一般Φ3mm--Φ8mm，显示面积一般几至十几平方米。
室外显示屏：面积一般几十平方米至几百平方米，亮度高，可在阳光下工作，具有防风、防雨、防水功能。
4、按发光点直径分类，室内屏：Φ3mm、Φ3.75mm、Φ5mm。
室外屏：Φ10mm、Φ12mm、Φ16mm、Φ19mm、Φ20mm、Φ21mm、Φ22mm、Φ26mm 。
室外屏发光的基本单元为发光筒，发光筒的原理是将一组红、绿、蓝发光二极管封在一个塑料筒内共同发。
5.显示方式有静态、横向滚动、垂直滚动和翻页显示等。
单块模块控制驱动12块（最多可控制24块）8X8点阵，共16X48点阵（或32X48点阵），是单块MAX7219（或PS7219、HD7279、ZLG7289及8279等类似LED显示驱动模块）的12倍（或24倍）！可采用“级联”的方式组成任意点阵大显示屏。
显示效果好，功耗小，且比采用MAX7219电路的成本更低。
LED显示屏检验方法，一看屏体规格，外观，平整度，屏内的连线等。
二看屏点亮后坏点，在不在不范围之内，（一般来说现在的屏基本上没有了）色差一致性，显示文字是否正常，显示屏图片等，全彩的要全屏打白色，红，绿，蓝。
技术优势评述。
现有常见的室内全彩方案的比较：1．点阵模块方案：最早的设计方案，由室内伪彩点阵屏发展而来。
优势：原材料成本最有优势，且生产加工工艺简单，质量稳定。
缺点：色彩一致性差，马赛克现象较严重，显示效果较差。
2．单灯方案：为解决点阵屏色彩问题，借鉴户外显示屏技术的一种方案，同时将户外的像素复用技术（又叫像素共享技术，虚拟像素技术）移植到了室内显示屏。
优势：色彩一致性比点阵模块方式的好。
缺点：混色效果不佳，视角不大，水平方向左右观看有色差。
加工较复杂，抗静电要求高。
实际像素分辨率做到10000点以上较难。
主要性能●与MCS-51单片机产品兼容●8K字节在系统可编程Flash存储器●1000次擦写周期●全静态操作：0Hz～33Hz●三级加密程序存储器●32个可编程I/O口线●三个16位定时器/计数器●八个中断源●全双工UART串行通道●低功耗空闲和掉电模式●掉电后中断可唤醒●看门狗定时器●双数据指针●掉电标识符功能特性描述AT89C52是一种低功耗、高性能CMOS8位微控制器，具有8K在系统可编程Flash 存储器。
使用Atmel公司高密度非易失性存储器技术制造，与工业80C51产品指令和引脚完全兼容。
片上Flash允许程序存储器在系统可编程，亦适于常规编程器。
在单芯片上，拥有灵巧的8位CPU和在系统可编程Flash，使得AT89C52为众多嵌入式控制应用系统提供高灵活、超有效的解决方案。
AT89C52具有以下标准功能：8k 字节Flash，256字节RAM，32位I/O口线，看门狗定时器，2个数据指针，三个16位定时器/计数器，一个6向量2级中断结构，全双工串行口，片内晶振及时钟电路。
另外，AT89C52可降至0Hz静态逻辑操作，支持2种软件可选择节电模式。
空闲模式下，CPU停止工作，允许RAM、定时器/计数器、串口、中断继续工作。
掉电保护方式下，RAM内容被保存，振荡器被冻结，单片机一切工作停止，直到下一个中断或硬件复位为止。
ST: 复位输入。
晶振工作时，RST脚持续2个机器周期高电平将使单片机复位。
看门狗计时完成后，RST脚输出96个晶振周期的高电平。
特殊寄存器AUXR(地址8EH)上的DISRTO位可以使此功能无效。
DISRTO默认状态下，复位高电平有效。
ALE/PROG：地址锁存控制信号（ALE）是访问外部程序存储器时，锁存低8位地址的输出脉冲。
在flash编程时，此引脚（PROG）也用作编程输入脉冲。
在一般情况下，ALE 以晶振六分之一的固定频率输出脉冲，可用来作为外部定时器或时钟使用。
然而，特别强调，在每次访问外部数据存储器时，ALE脉冲将会跳过。
如果需要，通过将地址为8EH的SFR的第0位置“1”，ALE操作将无效。
这一位置“1”，ALE 仅在执行MOVX 或MOVC指令时有效。
否则，ALE 将被微弱拉高。
这个ALE 使能标志位（地址为8EH的SFR的第0位）的设置对微控制器处于外部执行模式下无效。
PSEN:外部程序存储器选通信号（PSEN）是外部程序存储器选通信号。
当 AT89S52从外部程序存储器执行外部代码时，PSEN在每个机器周期被激活两次，而在访问外部数据存储器时，PSEN将不被激活。
EA /VPP:访问外部程序存储器控制信号。
为使能从0000H 到FFFFH的外部程序存储器读取指令，EA必须接GND。
为了执行内部程序指令，EA应该接VCC。
在flash编程期间，EA也接收12伏VPP电压。
XTAL1:振荡器反相放大器和内部时钟发生电路的输入端。
XTAL2:振荡器反相放大器的输出端。
存储器结构:MCS-51器件有单独的程序存储器和数据存储器。
外部程序存储器和数据存储器都可以64K寻址。
程序存储器：如果EA引脚接地，程序读取只从外部存储器开始。
对于89C52，如果EA接VCC，程序读写先从内部存储器（地址为0000H～1FFFH）开始，接着从外部寻址，寻址地址为：2000H~FFFFH。
中断 AT89C52有6个中断源：两个外部中断（INT0和INT1），三个定时中断（定时器0、1、2）和一个串行中断。
这些中断每个中断源都可以通过置位或清除特殊寄存器IE中的相关中断允许控制位分别使得中断源有效或无效。