LED发光的光谱及色度分析要点

武汉工业学院

毕业论文

论文题目：LED发光的光谱及色度分析

姓名谢鑫

学号 071203210

院系数理科学系

专业电子信息科学与技术

指导教师李鸣

2011年06月08日

目录

摘要 ................................................................... I ABSTRACT .............................................................. II 第一章绪论 .. (1)

1.1 研究背景 (1)

1.2 发展的历史和现状 (1)

1.3 LED的特点和分类 (2)

1.4 LED测试标准及检测技术研究现状 (3)

第二章相关光度学基本原理 (4)

2.1 LED的发光原理 (4)

2.2 LED的封装 (6)

2.3 LED的主要特性 (7)

2.3.1 光谱分布、峰值波长和光谱辐射带宽 (7)

2.3.2 光通量 (7)

2.3.3 发光强度 (8)

2.3.4 色温 (9)

2.3.5 发光效率 (9)

2.3.6 显色性 (9)

2.3.7 正向工作电压

V (10)

F

2.3.8 V－I 特性 (10)

2.3.9 P－I 特性 (10)

2.4 小结 (11)

第三章实验设计 (12)

3.1 实验用具 (12)

3.2 实验记录与数据处理 (12)

3.2.1 LED光通量的测量 (12)

3.2.2 测量V-I特性 (15)

3.2.3 测量P－I特性 (17)

3.3 结果与讨论 (19)

第四章总结与展望 (20)

致谢 (22)

参考文献 (23)

摘要

LED光源现今已经广泛应用于照明领域和信息技术领域，而且有希望成为未来

最主要的光源之一。随着LED产业的快速增长，LED的光度测量仍然是一个值得

探讨的问题。

本论文基于相关光度学理论，通过对现有测量LED光度特性的各种方法和标准的研究，针对LED本身作为光源所特有的结构和光学特性，提出了LED发光强度空间分布特性的测量方法及其系统设计方案，讨论了相关的测试条件，确定了测试步骤，并且分析了影响测量结果精度的可能因素。

在硬件设计方面，系统采用光栅单色仪（光谱仪），接收单元，扫描系统，电子放大器，A/D采集单元，计算机及打印机组成完成整个光度测量过程。该设备集光学、精密机械、电子学、计算机技术于一体。

系统软件采用WGD-9型色度实验系统。该系统能准确测量光源各个波长段的光强，其中驱动控制、光电信号采样、测试数据通讯传送等几个功能模块组成，都由PC机客户端程序来决定所需执行操作；实现LED的光度测量和光度定标，并对测得的数据进行处理，在用户界面上显示最大光强、偏差角、光束发散角等相关光度参数以及发光强度空间分布曲线等测试结果。

在完成设计和功能调试的基础上，对本系统的光度测试性能进行了一系列的实验评价。通过对一些典型LED样品的测试，获得不同品种的LED在各种不同条件下发光强度空间分布曲线以及相关光度参数等大量实验结果。

关键词:光度学，发光二极管，发光强度空间分布曲线，光束发散角

ABSTRACT

LED (light emitted diode) is now widely used in the field of illuminating engineering as well as information technology, and is expected to be one of the uppermost light sources in the future. Despite of the wide and rapidly growing application of LED, the reliable method for its photometric measurement is worth while to be researched.

Based on the photometry, the related methods and standards of LED's photometric test are studied, a system scheme is presented for measuring the luminous intensity distribution characteristics of LED, in which structure and optical characters are considered. In addition, the test condition, operation procedures, and the measurement uncertainty are discussed.

For the hardware of the system, the single-chip computer of AT89C52 is adopted as the MCU (micro-controller unit),and the photoelectric transformation and signal amplification circuit are designed for the sampling channel. A high-speed 16bit A/D converter is used to ensure the precision and respondent rate, while the data communication with PC (personal computer) is realized via RS-232 serial port.

The system software is comprised by the MCU program and the PC program. The MCU system software includes the modules of step-motor driver, signal sampling, and data communication, all of which are controlled by the PC. The PC directs the rotation of the step-motor, by means of RS-232,to implement the photometric measurement and its calibration of the LED. Then the data processing is performed, and the measurement results are displayed on the user interface of PC, including the photometric parameters such as the maximal luminous, misalignment angle, spread angle of light beam and the spatial distribution curve for the luminous intensity of the LED.

A series of experiments are carried out to evaluate the photometric measurement performance of this system. The experimental results of the typical LEDs show that the measurement meets the specification of related standard, the performance is reliable and stable, there by the system is applicable to industry. Finally, the aspects of this study are summarized, and the possible improvements in this scheme are proposed.

Key words: photometry, light emitted diode (LED), spatial distribution curve of luminous intensity, spread angle of light beam.