热电偶温度传感器中英文对照外文翻译文献

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热电偶英文标记

热电偶英文标记A thermocouple, also known as a hot junction pair, is a type of sensor used to measure temperature in various industries. The English label for a thermocouple is typically "TC." Thermocouples work on the principle of Seebeck effect, where a voltage is generated when there is a temperature difference between the two junctions of the sensor.热电偶，也称为热接点对，是一种用于各种工业中测量温度的传感器。

热电偶的英文标记通常是"TC"。

热电偶的工作原理是基于塞贝克效应，即在传感器的两个接头之间存在温度差时会产生电压。

One of the key advantages of thermocouples is their ability to measure a wide range of temperatures, from cryogenic levels to extremely high temperatures. This versatility makes them suitable for a variety of industrial applications where temperature monitoring is critical for operational efficiency and safety.热电偶的一个主要优势是其能够测量从低温到极高温范围内的温度。

这种多功能性使它们适用于各种工业应用，其中温度监测对于操作效率和安全至关重要。

热释电红外传感器中英文对照外文翻译文献

热释电红外传感器中英文对照外文翻译文献中英文对照翻译热释电红外传感器前言热释电红外传感器是一种非常有应用潜力的传感器。

它能检测人或某些动物发射的红外线并转换成电信号输出。

早在1938年，有人就提出利用热释电效应探测红外辐射，但并未受到重视。

直到六十年代，随着激光、红外技术的迅速发展，才又推动了对热释电效应的研究和对热释电晶体的应用开发。

近年来，伴随着集成电路技术的飞速发展，以及对该传感器的特性的深入研究，相关的专用集成电路处理技术也迅速增长。

本文先介绍热释电传感器的原理，然后再描述相关的专用集成电路处理技术。

热释电效应在自然界，任何高于绝对温度（-273K）的物体都将产生红外光谱，不同温度的物体释放的红外能量的波长是不一样的，因此红外波长与温度的高低是相关的，而且辐射能量的大小与物体表面温度有关。

可见光的波长通常在1μm以下，而1μm以上的光人眼是看不到的，但是可以通过适当的仪器对辐射的能量进行检测。

当一些晶体受热时，在晶体两端将会产生数量相等而符号相反的电荷，这种由于热变化产生的电极化现象，被称为热释电效应。

通常，晶体自发极化所产生的束缚电荷被来自空气中附着在晶体表面的自由电子所中和，其自发极化电矩不能表现出来。

当温度变化时，晶体结构中的正负电荷重心相对移位，自发极化发生变化，晶体表面就会产生电荷耗尽，电荷耗尽的状况正比于极化程度，图1表示了热释电效应形成的原理。

能产生热释电效应的晶体称之为热释电体或热释电组件，其常用的材料有单晶(LiTaO3 等)、压电陶瓷（PZT等）及高分子薄膜（PVFZ等）[2]当以LiTaO3为代表的热释电材料处于自极化状态时，吸收红外线入射波后，结晶的表面温度改变，自极化也发生改变，结晶表面的电荷变得不平衡，把这种不平衡电荷的电压变化取出来，便可测出红外线。

热释电材料只有在温度变化时才产生电压，如果红外线一直照射，则没有不平衡电压，一旦无红外线照射时，结晶表面电荷就处于不平衡状态，从而输出电压。

温度传感器外文翻译

英文翻译Temperature humidity sensorThe sensor in type many sensors, the temperature sensor and applies two aspects in its output both is second to and with it correlation temperature is an important physical parameter, he affects all physical, chemistry and biomedicine process march, regardless of in the industry, the agriculture, the scientific research, the national defense and people's daily life each aspect, the temperature survey and the control all is the extremely important with the electronic technology and the materials science development, to each kind of new thermal element and the temperature sensor request structure advanced, the performance is stable, satisfies the more and more high request which proposed to the temperature survey and the control.Sensor classification carries on classified resistance type PN according to the manufacture temperature sensor material and the principle of work to tie the type thermoelectricity type radiation formular operating region is refers to the resistance value to have the remarkable change temperature sensor along with the temperature change, it may transform directly the temperature as the electrical the operating temperature scope, its resistance the which increases along with the temperature ascension is called positive temperature coefficient (PTC); Its resistance number the which reduces along with the temperature t ascension is called negative temperature (NTC); The negative temperature which reduces suddenly along with the temperature rise is called critical (CTR) in a warm area internal resistance.1. PTC principle of the PTC r usually to use the (BaTio3) ceramic material, the pure BaTio3 ceramics have the extremely high electronic resistivity under often the temperature, above 108Ω · m, therefore is the insulator.If carries on the doping in BaTio3, may cause the BaTio3 semiconductor, for example: Mixes by %% rare-earth element, but causes it to become has under the normal temperature----10Ω · m N line of semiconductors .Has electricity semiconductor BaTio3, when the temperature achieved when Curie temperature T, it transforms by the tetragonal system into the cubic system, this time its electronic resistivity leap increases several magnitudes ( times).Positive temperature coefficient the (PTC) acts according to this nature manufacture.After in semiconductor multi-crystal grain structure BaTio3, its crystal grain (general size small is approximately 3-10 µ m) the interior is the semiconductor nature; But the crystal boundary (has f e r r o electricity) for the high-resistance area. When type crystal external voltage, voltage majority of landings on high-resistance crystal boundary level, thus the crystal boundary has an effect to the material electric conductivity .The electron must pass through the crystal boundary barrier potential barrier from a crystal grain to be able to arrive another crystal grain .Below Curie temperature T c, BaTio3 is tetragonal system dielectric, the existence has the spontaneous polarized very strong internal electric field, enable the electron to have the high energy, thus the traversing crystal boundarypotential barrier is easy. But above Curie temperature T c, BaTio3 becomes the cubic system by the tetragonal system, polarizes vanishing spontaneously, internal electric field vanishing, the electricity is difficult in the traversing potential barrier, therefore above curie warm waste T c, electronic resistivity sharp increase. When two crystal grains contact mutually, crystal grain barrier potential barrier as shown in Figure is potential barrier le vel thickness, ø0 is the barrier height .According to the equation, the barrier height ø0 sticks the effective dielectric constant εe ff between with the crystal the relations is: In the formula, n0 is the density of donors; e is t he electronic electric quantity .ε0 is the vacuum coefficient of d i electrical loss. When the electronic overstepping potential barrier enters ø0, the electronic resistivity may write isWhen the temperature is l ower than Curie temperature TC, εe ff the value is approximately about 104, therefore ø0 very small, the ceramic electronic resistivity rho approaches in the volume resistivity ρv, after the temperature surpasses Curie temperature TC, the value drops suddenly, the A value increases, causes rho the value sharp increase, dopes BaTio3 and rho and between the temperature relational like chart .NTC t h r principle of work NTC the r s tor majority is by the transition family metal oxide compound (mainly is with M n, co, Ni, Fe and so on), the agglutination forms the semiconductor metal oxide compound under the controlled condition, they only have the P semiconductor characteristic .Regarding the common semiconducting material, the electronic resistivity mainly is relies on along with the warm waste change the current carrier number along with the temperature change, the temperature increment, the current carrier number increases, electric conduction ability enhancement. Thus electronic resistivity F falls. Regarding transition metal oxide compound semiconductor, for example Ni O, because its acceptor ionizing energy is very small, broad basic ionized completely in the room temperature, namely the current carrier density basically has nothing to do with the temperature, this time, should mainly consider the transport ratio and the temperature relations .By the semiconductor physics knowledge, the transport ratio expresses by the equation below:In the formula: The d-- oxygen octahedron gap is away from (Ni O is the Na Cl structure); V0-- lattice vibration frequency; The Ei-- activation energy, indicated the electron jumps originally from one in the position the energy which needs to the neighboring atom site. Or rewriting Then the electronic resistivity is: 0Ne-Ei/kT If command, then type changes: rho =ρ0eEi/KT Obviously the metal oxide compound semiconductor electronic resistivity mainly has the transport ratio along with the temperature change to cause along with the temperature change .When temperature increment, the electronic resistivity drops, assumes the negative temperature coefficient characteristic. Critical temperature also belongs to the negative temperature coefficient. But in some critical temperature scope, its resistance number drops suddenly along with the temperature rise .Anti- as shown in Figure 4-4. In the chart the anti- r curve has aresistance number point of discontinuity, approximately for 68℃, resistance number point of discontinuity magnitude generally in 3~ carry on the adjustment based on the material ingredient, it is suitable specially in 65℃~75℃ between uses, this kind of resistor may make the constant temperature control and on-off element.The CTR r usually uses the glass semiconductor processing, take the vanadium as the main material. Mixes in certain materials and so on oxide compound like C a O, B a O, S O or P2O5, TiO2 becomes after the hot dissolve. temperature sensor basic characteristic in view of the fact that the temperature sensor type is many, moreover its work mechanism is also different. This mainly introduces t the hot sensitive diode and the hot sensitive transistor characteristic and the parameter. from the s the material and anti- and so on carry on the classification variously. According to structure shape classification: Laminated shape, gasket shape, rod-shaped, tubular, thin membrane, thick membranous and other shapes. Includes according to the anti- temperature ra classification: Normal temperature, high temperature and ultralow temperature hot sensitive resistor. Includes according to the anti- classification: Negative temperature coefficient r (NTC), switch temperature r (PTC); Slow aberration positive temperature coefficient r (PTC), the critical negative temperature coefficient, the platinum resistor limits the temperature curve like chart 4-4 curvature 1. 1st, resistance - temperature characteristic anti- is refers to between the actual resistance value and the resistance body temperature dependent relations, this is one of basic characteristics.PTC switch positive temperature coefficient anti- curve. value rises suddenly to some temperature nearby the maximizing.Through the doping .If dopes P b in BaTio3, may cause Tc to the high temperature traverse, mixes in elements and so on S r or S n after BaTio3, may cause TC to the low temperature traverse. May according to need to adjust t Curie temperature TC. The actual resistance number expressed with RT. Is under certain ambient temperature, uses causes the resistance number change not to surpass the resistance value which % survey power actual resistance value is called the zero energy resistance value, or is called does not give off heat the power resistance value (cold resistance value).The actual resistance value size is decided by the resistor material and the geometry shape. If the actual resistance number own temperature has the following relations: NTC In the formula: RT time 11 temperature T actual resistance value; R 1 and resistance geometry shape with material related constant B, A 11 material constants. For the easy to operate, usually takes the ambient temperature for 25℃ to take the reference temperature, then has: NTC puts the resistor hotly: RT/R25=exp[B(1/T-1/298)] PTC g change along with the temperatureT change, and is proportional with material constant B. Therefore, usually while gives the resistance temperature coefficient, must point out when the survey temperature, positive temperature coefficient t a T in value superior constant A. Slow aberration positive temperature coefficient value in %/℃ 110%/℃ between. But the switch(mutant) positive temperature co efficient T may achieve 60%/℃ or higher. Material constant B is uses for to describe the t material physical property - parameter. Also is called the thermal sensitivity target. In the operating region, the B value is not a strict constant, has slightly along with the temperature ascension increases .In general, the B value great electronic resistivity is also high. The different B value material has the different use, like ordinary negative temperature coefficient material constant B value between 2000yi5000 K. The negative temperature coefficient B value may according to the equation below computation: Positive temperature coefficient resistor, its A value according to equation below computation: In the formula, R1 R2 respectively is time thermodynamic temperature T1 and the T2 resistance value. 2. thermal properties (1) dissipation constant H dissipation constant H defined as the temperature each increase once diffusion power .It uses for when describes work, the resistance element and the external environment carry on the hot conversation a physical quantity. Dissipation constant H and dissipated power P .The temperature increment AT relations are The H size and the t structure, locates the environment medium type, the velocity of movement, the pressure and the heat conduction performance and so on related, when ambient temperature change, H has the change. (2) capacity and the time-constant r appliance has certain calorific capacity C, therefore it has certain warm. Also is the temperature change needs certain time. When the is heated up the T2 temperature, puts to the temperature is in the T0 environment, does not add the electric power, the starts to decrease temperature, its temperature T is the time t function, in △t time. The may indicate to the environment diffusion quantity of heat is: H(T-T0)△t, this part of quantity of heat is provides by the temperature decrease. Its value for - C△T, therefore has:Expressed in the environment atmosphere the steam content physical quantity is a y. The humidity expression method has two kinds, namely absolute humidity and relative h um (RH).The absolute humidity is refers to in the atmosphere the water content absolute value, the relative humidity is refers to in the atmosphere the steam to press with the identical temperature under ratio of the saturated steam tension, expressed with the percentage. The humidity sensor or the dew cell are refer to the paraphrase to the humidity sensitive part, it may be the wet sensitive resistor, also may be the wet sensitive capacitor or other dew cells. The humidity sensor classification classifies according to the feeling wet physical quantity, the humidity sensor may divide into three big kinds, namely wet sensitive resistor, wet sensitive capacitor and wet sensitive transistor. The humidity resistor makes which according to the use different material may divide into: Metal oxide compound semiconductor ceramics wet sensitive resistor, for example: MgCr2O4 series, ZnO-Cr2O3 series; Element material wet sensitive resistor, for example: Semiconductor G e, Si, Se and C element; Compound wet sensitive resistor, for example: Li Cl, CaSO4, and fluoride and iodide and so on; High polymer wet sensitive resistor and so on. The wet sensitive capacitor mainly is the porous Al2O3material makes as the medium. The wet sensitive transistor divides into the wet sensitive diode and the wet sensitive three levels of tubes. The wet sensitive resistor principle of work and the characteristic 1, the metal oxide compound semiconductor ceramics wet sensitive resistor (1) principle of work porous metal oxide compound semiconductor ceramics, in the crystal plane and the crystal boundary place, very easy to adsorb t drone. Because the water is one strong polar dielectric medium, nearby the h y drone hydrogen atom has the very strong electric field, has the very big electron affinity. When h y drone adheres to stick cohere when the semiconductor ceramics surface, will form the energy level very deep attachment surface acceptor condition, but from semiconductor ceramics surface capture electron, but will form the bound state in the ceramic surface the negative space charge, correspondingly will appear the hole in the near surface layer to accumulate, thus will cause the semiconductor ceramics electronic resistivity depression.Moreover, according to the ion electric conductance principle, the structure not compact semiconductor ceramics crystal grain has certain crevice, reveals the porous capillarity tubular .The drone may adsorbs through this kind of pore between various crystal grains surface and the crystal grain, because adsorbs the e separable relieves the massive electric conduction ion, these ions are playing the electric charge transportation role in the water adsorbed layer. along with humidity increase, material electronic resistivity drop. oxide compound semiconductor ceramics wet sensitive resistor principal variety and structure The metal oxide compound semiconductor ceramics wet sensitive resistor typical product includes: MgCr2O4 - TiO2 wet sensitive resistor, ZnO-Cr2O3 wet sensitive resistor, ZnO-Li2O3-V2O5 wet sensitive resistor and so on. For example: The ZnO-Li2O3-V2O5 wet sensitive resistance, is take Zn O as the main material, is joining a price, two prices, three prices and so on other metal oxide compound burns the ceramics semiconducting material, the survey humidity scope is 5%~100%RH, the measuring accuracy is 2%, is one kind of more ideal dew cell, and may make the miniaturization, the structure is simple. 2nd, element material wet sensitive resistor kind of wet sensitive resistor is a part which the element semiconducting material or the element material make.The carbon wet sensitive resistor is one resistance - humidity characteristic is the dew cell. With the organic matter polypropylene plastic piece or the stick are substrates, spreads cloth one to include the conductive carbon granule organic textile fiber constitution. This kind of wet sensitive resistor craft is simple, is advantageous for the uses the organic material absorption of moisture, the volume expansion, between the carbon granule distance increases, thus the resistance value increases principle. The element semiconductor, have on the honeycomb electrode ceramic substrate, is composed [granule diameter by the characteristic in the Fe3O4 colloid by the particle approximately for (100~250)×10-8m], each pellet only then a magnetic domain, therefore, the co current pellet attracts the union mutually, thus does not need the highpolymer material to make the colloid bond, but can obtain the good performance and the long service life. Figure 4-1 is the Fe3O4 colloid wet sensitive resistor structure drawing. Figure 4-2 is the Fe3O4 wet sensitive resistor resistance humidity characteristic curve, displays for the negative feeling wet characteristic. 4th, the wet sensitive resistor characteristic (1) resistance - humidity characteristic wet sensitive resistor resistance number along with the humidity change is generally the index relations change.温度传感器在种类繁多的传感器中，温度传感器在其产量和应用两方面都是数一数二的。

温度变送器中英文对照外文翻译文献

中英文对照外文翻译中英文资料对照外文翻译TT302 温度变送器概述TT302温度变送器接收毫伏(mV)输出的信号，这类传感器包括热电偶或阻性传感器，例如：热电阻（RTD）。

它所接受的信号必须在允许的输入范围之内。

允许输入电压范围为-50到500，电阻范围为0到2000欧姆。

功能描述-硬件每个板的功能介绍如下：图2.1 TT302-硬件构成方框图多路转换器多路转换器将变送器端子接到相应信号调理板上，以保证在正确的端子上测量电压。

信号调理板他的作用给输入信号提供一个正确的值以满足A/D转换。

A/D转换器A/D转换器将输入信号转换成数字形式传给CPU。

信号隔离他的作用在输入和CPU之间隔离控制信号和数字信号。

中央处理单元（CPU）RAM PROM和EEPROMCPU是变送器的智能部分，主要完成测量，板的执行，自诊断和通信的管理和运行。

系统程序存储在PROM中。

RAM用于暂时存放运算数据。

在RAM中存放的数据一旦断电立即消失，所以数据必须保存在不易丢失的EEPROM中。

例如：标定，块的标识和组态等数据。

通信控制器监视在线动态，调整通信信号，插入，删除预处理，滤波。

电源变送器电路通过现场总线电源供电。

电源隔离像信号隔离一样，供给输入部分的信号必须要隔离，电源隔离采用变压器将直流供电电源转换成高频交流供电。

显示控制器从CPU接收数据送给LCD显示器的显示部分，此时显示器必须处于打开状态。

本机调整它有两个磁性驱动开关，它们必须由磁性工具来驱动而不是机械或电的接触。

图2.2-LCD指示器温度传感器TT302像前面所描述的那样，可以兼容多种类型的传感器。

TT302为使用热电偶或热电阻RTD 测量温度进行了特殊设计。

此类传感器的基本内容如下所述：热电偶热电偶由两种不同的金属或合金在一端连接在一起所组成的，被称为测量端或热端。

测量端必须放在测量点上，热电偶的另一端是打开的连接在温度变送器上，这一端称做参考端或冷端。

在大多数应用中，塞贝克效应可以充分解释热电偶的工作原理。

传感器的基础知识中英文对照外文翻译文献

中英文对照外翻译Basic knowledge of transducersA transducer is a device which converts the quantity being measured into an optical, mechanical, or-more commonly-electrical signal. The energy-conversion process that takes place is referred to as transduction.Transducers are classified according to the transduction principle involved and the form of the measured. Thus a resistance transducer for measuring displacement is classified as a resistance displacement transducer. Other classification examples are pressure bellows, force diaphragm, pressure flapper-nozzle, and so on.1、Transducer ElementsAlthough there are exception ,most transducers consist of a sensing element and a conversion or control element. For example, diaphragms,bellows,strain tubes and rings, bourdon tubes, and cantilevers are sensing elements which respond to changes in pressure or force and convert these physical quantities into a displacement. This displacement may then be used to change an electrical parameter such as voltage, resistance, capacitance, or inductance. Such combination of mechanical and electrical elements form electromechanical transducing devices or transducers. Similar combination can be made for other energy input such as thermal. Photo, magnetic and chemical,giving thermoelectric, photoelectric,electromaanetic, and electrochemical transducers respectively.2、Transducer SensitivityThe relationship between the measured and the transducer output signal is usually obtained by calibration tests and is referred to as the transducer sensitivity K1= output-signal increment / measured increment . In practice, the transducer sensitivity is usually known, and, by measuring the output signal, the input quantity is determined from input= output-signal increment / K1.3、Characteristics of an Ideal TransducerThe high transducer should exhibit the following characteristicsa) high fidelity-the transducer output waveform shape be a faithful reproduction of the measured; there should be minimum distortion.b) There should be minimum interference with the quantity being measured; the presence of the transducer should not alter the measured in any way.c) Size. The transducer must be capable of being placed exactly where it is needed.d) There should be a linear relationship between the measured and the transducer signal.e) The transducer should have minimum sensitivity to external effects, pressure transducers,for example,are often subjected to external effects such vibration and temperature.f) The natural frequency of the transducer should be well separated from the frequency and harmonics of the measurand.4、Electrical TransducersElectrical transducers exhibit many of the ideal characteristics. In addition they offer high sensitivity as well as promoting the possible of remote indication or mesdurement. Electrical transducers can be divided into two distinct groups:a) variable-control-parameter types,which include:i)resistanceii) capacitanceiii) inductanceiv) mutual-inductance typesThese transducers all rely on external excitation voltage for their operation.b) self-generating types,which includei) electromagneticii)thermoelectriciii)photoemissiveiv)piezo-electric typesThese all themselves produce an output voltage in response to the measurand input and their effects are reversible. For example, a piezo-electric transducer normally produces an output voltage in response to the deformation of a crystalline material; however, if an alternating voltage is applied across the material, the transducer exhibits the reversible effect by deforming or vibrating at the frequency of the alternating voltage.5、Resistance TransducersResistance transducers may be divided into two groups, as follows:i) Those which experience a large resistance change, measured by using potential-divider methods. Potentiometers are in this group.ii)Those which experience a small resistance change, measured by bridge-circuit methods. Examples of this group include strain gauges and resistance thermometers.5.1 PotentiometersA linear wire-wound potentiometer consists of a number of turns resistance wire wound around a non-conducting former, together with a wiping contact which travels over the barwires. The construction principles are shown in figure which indicate that the wiperdisplacement can be rotary, translational, or a combination of both to give a helical-type motion. The excitation voltage may be either a.c. or d.c. and the output voltage is proportional to the input motion, provided the measuring device has a resistance which is much greater than the potentiometer resistance.Such potentiometers suffer from the linked problem of resolution and electrical noise. Resolution is defined as the smallest detectable change in input and is dependent on thecross-sectional area of the windings and the area of the sliding contact. The output voltage is thus a serials of steps as the contact moves from one wire to next.Electrical noise may be generated by variation in contact resistance, by mechanical wear due to contact friction, and by contact vibration transmitted from the sensing element. In addition, the motion being measured may experience significant mechanical loading by the inertia and friction of the moving parts of the potentiometer. The wear on the contacting surface limits the life of a potentiometer to a finite number of full strokes or rotations usually referred to in the manufacture’s specification as the ‘number of cycles of life expectancy’, a typical value being 20*1000000 cycles.The output voltage V0 of the unload potentiometer circuit is determined as follows. Let resistance R1= xi/xt *Rt where xi = input displacement, xt= maximum possible displacement, Rt total resistance of the potentiometer. Then output voltage V0= V*R1/(R1+( Rt-R1))=V*R1/Rt=V*xi/xt*Rt/Rt=V*xi/xt. This shows that there is a straight-line relationship between output voltage and input displacement for the unloaded potentiometer.It would seen that high sensitivity could be achieved simply by increasing the excitation voltage V. however, the maximum value of V is determined by the maximum power dissipation P of the fine wires of the potentiometer winding and is given by V=(PRt)1/2 .5.2 Resistance Strain GaugesResistance strain gauges are transducers which exhibit a change in electrical resistance in response to mechanical strain. They may be of the bonded or unbonded variety .a) bonded strain gaugesUsing an adhesive, these gauges are bonded, or cemented, directly on to the surface of the body or structure which is being examined.Examples of bonded gauges arei) fine wire gauges cemented to paper backingii) photo-etched grids of conducting foil on an epoxy-resin backingiii)a single semiconductor filament mounted on an epoxy-resin backing with copper or nickel leads.Resistance gauges can be made up as single elements to measuring strain in one direction only,or a combination of elements such as rosettes will permit simultaneous measurements in more than one direction.b) unbonded strain gaugesA typical unbonded-strain-gauge arrangement shows fine resistance wires stretched around supports in such a way that the deflection of the cantilever spring system changes the tension in the wires and thus alters the resistance of wire. Such an arrangement may be found in commercially available force, load, or pressure transducers.5.3 Resistance Temperature TransducersThe materials for these can be divided into two main groups:a) metals such as platinum, copper, tungsten, and nickel which exhibit and increase in resistance as the temperature rises; they have a positive temperature coefficient of resistance.b) semiconductors, such as thermistors which use oxides of manganese, cobalt, chromium, or nickel. These exhibit large non-linear resistance changes with temperature variation and normally have a negative temperature coefficient of resistance.a) metal resistance temperature transducersThese depend, for many practical purpose and within a narrow temperature range, upon the relationship R1=R0*[1+a*(b1-b2)] where a coefficient of resistance in ℃-1,and R0 resistance in ohms at the reference temperature b0=0℃ at the reference temperature range ℃.The international practical temperature scale is based on the platinum resistance thermometer, which covers the temperature range -259.35℃ to 630.5℃.b) thermistor resistance temperature transducersThermistors are temperature-sensitive resistors which exhibit large non-liner resistance changes with temperature variation. In general, they have a negative temperature coefficient. For small temperature increments the variation in resistance is reasonably linear; but, if large temperature changes are experienced, special linearizing techniques are used in the measuring circuits to produce a linear relationship of resistance against temperature.Thermistors are normally made in the form of semiconductor discs enclosed in glass vitreous enamel. Since they can be made as small as 1mm,quite rapid response times are possible.5.4 Photoconductive CellsThe photoconductive cell , uses a light-sensitive semiconductor material. The resistance between the metal electrodes decrease as the intensity of the light striking the semiconductor increases. Common semiconductor materials used for photo-conductive cells are cadmium sulphide, lead sulphide, and copper-doped germanium.The useful range of frequencies is determined by material used. Cadmium sulphide is mainly suitable for visible light, whereas lead sulphide has its peak response in the infra-red regionand is, therefore , most suitable for flame-failure detection and temperature measurement. 5.5 Photoemissive CellsWhen light strikes the cathode of the photoemissive cell are given sufficient energy to arrive the cathode. The positive anode attracts these electrons, producing a current which flows through resistor R and resulting in an output voltage V.Photoelectrically generated voltage V=Ip.RlWhere Ip=photoelectric current(A),and photoelectric current Ip=Kt.BWhere Kt=sensitivity (A/im),and B=illumination input (lumen)Although the output voltage does give a good indication of the magnitude of illumination, the cells are more often used for counting or control purpose, where the light striking the cathode can be interrupted.6、Capacitive TransducersThe capacitance can thus made to vary by changing either the relative permittivity, the effective area, or the distance separating the plates. The characteristic curves indicate that variations of area and relative permittivity give a linear relationship only over a small range of spacings. Thus the sensitivity is high for small values of d. Unlike the potentionmeter, the variable-distance capacitive transducer has an infinite resolution making it most suitable for measuring small increments of displacement or quantities which may be changed to produce a displacement.7、Inductive TransducersThe inductance can thus be made to vary by changing the reluctance of the inductive circuit. Measuring techniques used with capacitive and inductive transducers:a)A.C. excited bridges using differential capacitors inductors.b)A.C. potentiometer circuits for dynamic measurements.c) D.C. circuits to give a voltage proportional to velocity for a capacitor.d) Frequency-modulation methods, where the change of C or L varies the frequency of an oscillation circuit.Important features of capacitive and inductive transducers are as follows:i)resolution infiniteii) accuracy+- 0.1% of full scale is quotediii)displacement ranges 25*10-6 m to 10-3miv) rise time less than 50us possibleTypical measurands are displacement, pressure, vibration, sound, and liquid level.8、Linear Variable-differential Ttransformer9、Piezo-electric Transducers10、Electromagnetic Transducers11、Thermoelectric Transducers12、Photoelectric Cells13、Mechanical Transducers and Sensing Elements传感器的基础知识传感器是一种把被测量转换为光的、机械的或者更平常的电信号的装置。

数字温度传感器毕业论文中英文资料外文翻译文献[管理资料]

毕业论文中英文资料外文翻译文献外文资料DS1722 Digital ThermometerWith scientific and technological progress and development of the types of temperature sensors increasingly wide range of application of the increasingly widespread, and the beginning analog toward digital, single-bus, dual-bus and bus-3 direction. And the number of temperature sensors because they apply to all microprocessor interface consisting of automatic temperature control system simulation can be overcome sensor and microprocessor interface need signal conditioning circuit and A / D converters advant ages of the drawbacks, has been widely used in industrial control, electronic transducers, medical equipment and other temperature control system. Among them, which are more representative of a digital temperature sensor DS18B20, MAX6575, the DS1722, MAX6636 other. This paper introduces the DS1722 digital temperature sensor characteristics, the use of the method and its timing. Internal structure and other relevant content.FEATURES:Temperature measurements require no external components;Measures temperatures from -55°C to +120°C. Fahrenheit equivalent is -67°F to +248°F;Thermometer accuracy is ±°C;Thermometer resolution is configurable from 8 to 12 bits (°C to °C resolution);Data is read from/written to via a Motorola Serial Peripheral Interface (SPI) or standard 3-wire serial interface;Wide analog power supply range ( - );Separate digital supply allows for logic;Available in an 8-pin SOIC (150 mil), 8-pin USOP, and flip chip package;PIN ASSIGNMENTFIGURE 1 PIN ASSIGNMENTPIN DESCRIPTION:SERMODE - Serial Interface Mode.CE - Chip Enable.SCLK - Serial Clock.GND – Ground.VDDA - Analog Supply Voltage.SDO - Serial Data Out.SDI - Serial Data In.VDDD - Digital Supply Voltage.DESCRIPTION:The DS1722 Digital Thermometer and Thermostat with SPI/3-Wire Interface provides temperature readings which indicate the temperature of the device. No additional components are required; the device is truly a temperature-to-digital converter. Temperature readings are communicated from the DS1722 over a Motorola SPI interface or a standard 3-wire serial interface. The choice of interface standard is selectable by the user. For applications that require greater temperature resolution, the user can adjust the readout resolution from 8 to 12 bits. This is particularly useful in applications where thermal runaway conditions must be detected quickly.For application flexibility, the DS1722 features a wide analog supply rail of - . A separate digital supply allows a range of to . The DS1722 is available in an 8-pin SOIC (150-mil), 8-pin USOP, and flip chip package.Applications for the DS1722 include personal computers/servers/workstations, cellular telephones, office equipment, or any thermally-sensitive system.OVERVIEW:A block diagram of the DS1722 is shown in Figure 2. The DS1722 consists offour major components:1. Precision temperature sensor.2. Analog-to-digital converter.3. SPI/3-wire interface electronics.4. Data registers.The factory-calibrated temperature sensor requires no external components. The DS1722 is in a power conserving shutdown state upon power-up. After power-up, the user may alter the configuration register to place the device in a continuous temperature conversion mode or in a one-shot conversion mode. In the continuous conversion mode, the DS1722 continuously converts the temperature and stores the result in the temperature register. As conversions are performed in the background, reading the temperature register does not affect the conversion in progress. In the one-shot temperature conversion mode, the DS1722 will perform one temperature conversion, store the result in the temperature register, and then eturn to the shutdown state. This conversion mode is ideal for power sensitive applications. More information on the configuration register is contained in the “OPERATION-Programming”section. The temperature conversion results will have a default resolution of 9 bits. In applications where small incremental temperature changes are critical, the user can change the conversion resolution from 9 bits to 8, 10, 11, or 12. This is accomplished by programming the configuration register. Each additional bit of resolution approximately doubles the conversion time. The DS1722 can communicate using either a Motorola Serial Peripheral Interface (SPI) or standard 3-wire interface. The user can select either communication standard through the SERMODE pin, tying it to VDDD for SPI and to ground for 3-wire. The device contains both an analog supply voltage and a digital supply voltage (VDDA and VDDD, respectively). The analog supply powers the device for operation while the digital supply provides the top rails for the digital inputs and outputs. The DS1722 was designed to be Logic-Ready.DS1722 FUNCTIONAL BLOCK DIAGRAM Figure 2OPERATION-Measuring Temperature:The core of DS1722 functionality is its direct-to-digital temperature sensor. The DS1722 measures temperature through the use of an on-chip temperature measurement technique with an operating range from -55°to +120°C. The device powers up in a power-conserving shutdown mode. After power-up, the DS1722 may be placed in a continuous conversion mode or in a one-shot conversion mode. In the continuous conversion mode, the device continuously computes the temperature and stores the most recent result in the temperature register at addresses 01h (LSB) and 02h (MSB). In the one-shot conversion mode, the DS1722 performs one temperature conversion and then returns to the shutdown mode, storing temperature in the temperature register. Details on how to change the setting after power up are contained in the “OPERATION-Programming”section. The resolution of the temperature conversion is configurable (8, 9, 10, 11, or 12 bits), with 9-bit readings the default state. This equates to a temperature resolution of °C, °C, °C, °C, or °C. Following each conversion, thermal data is stored in the thermometer register in two’s complement format; the information can be retrieved over the SPI or 3-wire interface with the address set to the temperature register, 01h (LSB) and then 02h (MSB). Table 2 describesthe exact relationship of output data to measured temperature. The table assumes the DS1722 is configured for 12-bit resolution; if the evince is configured in a lower resolution mode, those bits will contain 0s. The data is transmitted serially over the digital interface, MSB first for SPI communication and LSB first for 3-wire communication. The MSB of the temperature register contains the “sign” (S) bit, denoting whether the temperature is positive or negative. For Fahrenheit usage, a lookup table or conversion routine must be used.AddressLocation S 2625242322212002h MSB (unit = ℃) LSB2-12-22-32-40 0 0 0 01hTEMPERATURE DIGITAL OUTPUT(BINARY) DIGITAL OUTPUT(HEX)+120℃0111 1000 0000 0000 7800h+ 0001 1001 0001 0000 1910h+ 0000 1010 0010 0000 0a20h+ 0000 0000 1000 0000 0080h0 0000 0000 0000 0000 0000h1111 1111 1000 0000 Ff80h1111 0101 1110 0000 F5e0h1110 0110 1111 0000 E6f0h-55 1100 1001 0000 0000 C900h OPERATION-Programming:The area of interest in programming the DS1722 is the Configuration register. All programming is done via the SPI or 3-wire communication interface by selecting the appropriate address of the desired register location. Table 3 illustrates the addresses for the two registers (configuration and temperature) of the DS1722.Register Address Structure Table 3CONFIGURATION REGISTER PROGRAMMING:The configuration register is accessed in the DS1722 with the 00h address for reads and the 80h address for writes. Data is read from or written to the configuration register MSB first for SPI communication and LSB first for 3-wire communication. The format of the register is illustrated in Figure 2. The effect each bit has on DS1722 functionality is described below along with the power-up state of the bit. The entire register is volatile, and thus it will power-up in the default state.CONFIGURATION/STATUS REGISTER Figure 21SHOT = One-shot temperature conversion bit. If the SD bit is "1", (continuous temperature conversions are not taking place), a "1" written to the 1SHOT bit will cause the DS1722 to perform one temperature conversion and store the results in the temperature register at addresses 01h (LSB) and 02h (MSB). The bit will clear itself to "0" upon completion of the temperature conversion. The user has read/write access to the 1SHOT bit, although writes to this bit will be ignored if the SD bit is a "0", (continuous conversion mode). The power-up default of the one-shot bit is "0".R0, R1, R2 = Thermometer resolution bits. Table 4 below defines the resolution of the digital thermometer, based on the settings of these 3 bits. There is a direct tradeoff between resolution and conversion time, as depicted in the AC Electrical Characteristics. The user has read/write access to the R2, R1 and R0 bits and the power-up default state is R2="0", R1="0", and R0="1" (9-bit conversions).THERMOMETER RESOLUTION CONFIGURATION Table 4SD = Shutdown bit. If SD is "0", the DS1722 will continuously perform temperature conversions and store the last completed result in the temperature register. If SD is changed to a "1", the conversion in progress will be completed and stored and then the device will revert to a low-power shutdown mode. The communication port remains active. The user has read/write access to the SD bit and the power-up default is "1" (shutdown mode).SERIAL INTERFACE:The DS1722 offers the flexibility to choose between two serial interface modes. The DS1722 can communicate with the SPI interface or with a standard 3-wire interface. The interface method used is determined by the SERMODE pin. When this pin is connected to VDDD SPI communication is selected. When this pin is connected to ground, standard 3-wire communication is selected.SERIAL PERIPHERAL INTERFACE (SPI):The serial peripheral interface (SPI) is a synchronous bus for address and data transfer. The SPI mode of serial communication is selected by tying the SERMODE pin to VDDD. Four pins are used for the SPI. The four pins are the SDO (Serial Data Out), SDI (Serial Data In), CE (Chip Enable), and SCLK (Serial Clock). The DS1722 is the slave device in an SPI application, with the microcontroller being the master. The SDI and SDO pins are the serial data input and output pins for the DS1722, respectively. The CE input is used to initiate and terminate a data transfer. The SCLK pin is used to synchronize data movement between the master (microcontroller) and the slave (DS1722) devices. The shift clock (SCLK), which is generated by the microcontroller, is active only when CE is high and during address and data transfer to any device on the SPI bus. The inactive clock polarity is programmable in somemicrocontrollers. The DS1722 offers an important feature in that the level of the inactive clock is determined by sampling SCLK when CE becomes active. Therefore, either SCLK polarity can be accommodated. There is one clock for each bit transferred. Address and data bits are transferred in groups of eight, MSB first.3-WIRE SERIAL DATA BUS:The 3-wire communication mode operates similar to the SPI mode. However, in 3-wire mode, there is one bi-directional I/O instead of separate data in and data out signals. The 3-wire consists of the I/O (SDI and SDO pins tied together), CE, and SCLK pins. In 3-wire mode, each byte is shifted in LSB first unlike SPI mode where each byte is shifted in MSB first. As is the case with the SPI mode, an address byte is written to the device followed by a single data byte or multiple data bytes.外文资料译文DS1722数字温度传感器随着科学技术的不断进步和发展，温度传感器的种类日益繁多，应用逐渐广泛，并且开始由模拟式向着数字式、单总线式、双总线式和三总线式发展。

传感器中英文介绍

. sensorssensors(English name: transducer/sensor) is a kind of detection device, can feel the measured information, and will feel information transformation according to certain rule become electrical signal output, or other form of information needed to satisfy the information transmission, processing, storage, display, record and control requirements.Sensor's features include: miniaturization, digital, intelligent, multi-functional, systematic and network. It is the first step of automatic detection and automatic control. The existence and development of the sensor, let objects have sensory, such as touch, taste and smell let objects become live up slowly. Usually according to its basic cognitive functions are divided into temperature sensor, light sensor, gas sensor, force sensor, magnetic sensor, moisture sensor, acoustic sensor, radiation sensitive element, color sensor and sensor etc. 10 major categories.temperature transducerTemperature sensors (temperature transducer) refers to can feel temperature translates into usable output signal of the sensor. The temperature sensor is the core part of the temperature measuring instrument, wide variety. According to measuring methods could be divided into two types: contact and non-contact, according to the sensor material and electronic component features divided into two categories, thermal resistance and thermocouple.1 principle of thermocoupleThermocouple is composed of two different materials of metal wire, the welded together at the end. To measure the heating part of the environment temperature, can accurately know the temperature of the hot spots. Because it must have two different material of the conductor, so called the thermocouple. Different material to make the thermocouple used in different temperature range, their sensitivity is also each are not identical. The sensitivity of thermocouple refers to add 1 ℃hot spot temperature changes, the output variation of potential difference. For most of the metal material support thermocouple, this value about between 5 ~ 40 microvolt / ℃.As a result of the thermocouple temperature sensor sensitivity has nothing to do with the thickness of material, use very fine material also can make the temperature sensor. Also due to the production of thermocouple metal materials have good ductility, the slight temperature measuring element has high response speed, can measure the process of rapid change.Its advantages are:(1)high precision measurement. Because of thermocouple direct contact with the object being measured, not affected by intermediate medium.(2)the measurement range. Commonly used thermocouple from 1600 ℃to 50 ℃ ~ + sustainable measurement, some special thermocouple minimum measurable to - 269 ℃ (e.g., gold iron nickel chrome), the highest measurable to + 2800 ℃ (such as tungsten rhenium).(3) simple structure, easy to use. Thermocouple is usually composed of two different kinds of metal wire, but is not limited by the size and the beginning of, outside has protective casing, so very convenient to use. The thermocouple type and structure of the form.2. The thermocouple type and structure formation(1)the types of thermocoupleThe commonly used thermocouple could be divided into two types: standard thermocouple and non-standard thermocouple. Standard thermocouple refers to the national standard specifies its thermoelectric potential and the relationship between temperature, permissible error, and a unified standard score table of thermocouple, it has with matching display instrument to choose from. Rather than a standard thermocouple or on the order of magnitude less than the range to use standardized thermocouple, in general, there is no uniform standard, it is mainly used for measurement of some special occasions.Standardized thermocouple is our country from January 1, 1988, thermocouple and thermal resistance of all production according to IEC international standard, and specify the S, B, E, K, R, J, T seven standardization thermocouple type thermocouple for our country unified design.(2)to ensure that the thermocouple is reliable, steady work, the structure of thermocouple requirements are as follows:①of the two thermocouple thermal electrode welding must be strong;②two hot electrode should be well insulated between each other, in case of short circuit;③compensation wires connected to the free cod of a thermocouple to convenient and reliable;④protect casing thermal electrodes should be able to make sufficient isolation and harmful medium.3.The thermocouple cold end temperature compensationDue to the thermocouple materials are generally more expensive (especiallywhen using precious metals), and the temperature measurement points are generally more far, the distance to the instrument in order to save materials, reduce cost, usually adopt the compensating conductor) (the free end of the cold junction of the thermocouple to the steady control of indoor temperature, connected to the meter terminals. It must be pointed out that the role of the thermocouple compensation wire extension hot electrode, so that only moved to the control room of the cold junction of the thermocouple instrument on the terminal, it itself does not eliminate the cold end temperature change on the influence of temperature, cannot have the compensation effect. So, still need to take some of the other correction method to compensate of the cold end temperature especially when t0 indicates influence on measuring temperature 0 ℃.Must pay attention to when using thermocouple compensating conductor model match, cannot be wrong polarity, compensation conductor should be connected to the thermocouple temperature should not exceed 100 ℃.传感器传感器（英文名称：transducer/sensor）是一种检测装置，能感受到被测量的信息，并能将感受到的信息，按一定规律变换成为电信号或其他所需形式的信息输出，以满足信息的传输、处理、存储、显示、记录和控制等要求。

传感器技术7-热电式传感器-中英对照

适宜制作热电阻的材料有铂(Platinum)、铜(Copper)、镍 (Nickel)、铁(Ferrum)等。
第7章热电式传感器

2.铂、铜热电阻的特性铂Platinum、铜Copper为应用最广的热电阻材料。虽然铁Ferrum、镍Nickel的温度系数和电阻率均比铂、铜要高，但由于存在着不易提纯(purify)和非线性(nonlinearity)严重的缺点，因而用得不多。铂容易提纯，在高温和氧化性(oxidative)介质中化学、物理性能(physical properties)稳定，制成的铂电阻输出－输入特性接近线性，测量精度高。
E A (T , T0 ) Adt E A (T0 , T )
T0
T
(7-8)
式中 EA(T,T0)——金属A两端温度分别为T与T0时的温差电势； σ A——温差系数(temperature differential coefficient)； T、T0——高、低温端的绝对温度。
第7章热电式传感器 Thermoelectric Sensors
第7章热电式传感器

7.1
热电阻传感器 Thermal resistance sensors 热电偶传感器 Thermocouple sensors 热电式传感器的应用 Applications of thermoelectric sensors
第7章热电式传感器

3.其他热电阻 ⑴.铟(Indium)电阻适宜在-269～-258℃温度范围内使用，测温精度高，灵敏度是铂电阻的10倍，但是复现性(repeatability)差。 ⑵.锰(Manganese)电阻适宜在-271～-210℃温度范围内使用，灵敏度高，但是质脆易损坏。 ⑶.碳(Carbon)电阻适宜在-273～-268.5℃温度范围内使用，热容量(thermal capacity)小，灵敏度高，价格低廉，操作简便，但是热稳定性(thermal stability) 较差。

外文翻译(供热站温度实时监测)

Heating temperature and pressure test Thermistors are inexpensive, easily-obtainable temperature sensors. They are easy to use and adaptable. Circuits with thermistors can have reasonable outout voltages - not the millivolt outputs thermocouples have. Because of these qualities, thermistors are widely used for simple temperature measurements. They're not used for high temperatures, but in the temperature ranges where they work they are widely used. Thermistors are temperature sensitive resistors. All resistors vary with temperature, but thermistors are constructed of semiconductor material with a resistivity that is especially sensitive to temperature. However, unlike most other resistive devices, the resistance of a thermistor decreases with increasing temperature. That's due to the properties of the semiconductor material that the thermistor is made from. For some, that may be counterintuitive, but it is correct. Here is a graph of resistance as a function of temperature for a typical thermistor. Notice how the resistance drops from 100 kW, to a very small value in a range around room temperature. Not only is the resistance change in the opposite direction from what you expect, but the magnitude of the percentage resistance change is substantial.Temperature Sensor - The Thermocouple You are at: Elements - Sensors - Thermocouples Return to Table of Contents A thermocouple is a junction formed from two dissimilar metals. Actually, it is a pair of junctions. One at a reference temperature (like 0 oC) and the other junction at the temperature to be measured. A temperature difference will cause a voltage to be developed that is temperature dependent. (That voltage is caused by something called the Seebeck effect.) Thermocouples are widely used for temperature measurement because they are inexpensive, rugged and reliable, and they can be used over a wide temperature range.In particular, other temperature sensors (like thermistors and LM35 sensors) are useful around room temperature, but the thermocouple can The Thermocouple Why Use thermocouples To Measure Temperature? They are inexpensive. They are rugged and reliable. They can be used over a wide temperature range. What Does A Thermocouple Look Like? Here it is. Note the two wires (of two different metals) joined in the junction. What does a thermocouple do? How does it work? The junction of two dissimilar metals produces a temperature dependent voltage. For a better description of how it works, click here. How Do You Use A Thermocouple? You measure the voltage the thermocouple produces, and convert that voltage to a temperature reading. It may be best to do the conversion digitally because the conversion can be fairly nonlinear. Things You Need To Know About Thermocouples A junction between two dissimilar metals produces a voltage. In the thermocouple, the sensing junction - produces a voltage that depends upon temperature. Where the thermocouple connects to instrumentation - copper wires? - you have two more junctions and they also produce a temperature dependent voltage. Those junctions are shown inside the yellow oval. When you use a thermocouple, you need to ensure that the connections are at some standard temperature, or you need to use an electronically compensated system that takes those voltages into account. If your thermocouple is connected to a data acquisition system, then chances are good that you have an electronically compensated system. Once we obtain a reading from a voltmeter, the measured voltage has to be converted to temperature. The temperature is usually expressed as a polynomial function of the measured voltage. Sometimes it is possible to get a decent linear approximation over a limited temperature range. There are two ways to convert the measured voltage to a temperature reading. Measure the voltage and let the operator do the calculations. Use the measured voltage as an input to a conversion circuit - either analog or digital. Let us look at someother types of base-metal thermocouples. Type T thermocouples are widely used as are type K and Type N. Type K (Ni-Cr/Ni-Al) thermocouples are also widely used in the industry. It has high thermopower and good resistance to oxidation. The operating temperature range of a Type K thermocouple is from -269 oC to +1260 oC. However, this thermocouple performs rather poorly in reducing atmospheres. Type T (Cu/Cu-Ni) thermocouples can be used in oxidizing of inert atmospheres over the temperature range of -250 oC to +850 oC. In reducing or mildly oxidizing environments, it is possible to use the thermocouple up to nearly +1000 oC. Type N (Nicrosil/Nisil) thermocouples are designed to be used in industrial environments of temperatures up to +1200 oC. A polynomial equation used to convert thermocouple voltage to temperature (oC) over a wide range of temperatures. We can write the polynomial as: The coefficients, an are tabulated in many places. Here are the NBS polynomial coefficients for a type K thermocouple. (Source: T. J. Quinn, Temperature , Academic Press Inc.,1990) Type K Polynomial Coefficients n an 0 0.226584602 1 24152.10900 2 67233.4248 3 2210340.682 4 -860963914.9 5 4.83506x1010 6 -1.18452x1012 7 1.38690x1013 8 -6.33708x1013 What If The Surrounding Temperature Exceeds Limits? There are really no thermocouples that can withstand oxidizing atmospheres for temperatures above the upper limit of the platinum-rhodium type thermocouples. We cannot, therefore, measure temperature in such high temperature conditions. Other options for measuring extremely high temperatures are radiation or the noise pyrometer. For non-oxidizing atmospheres, tungsten-rhenium based thermocouples shows good performance up to +2750 oC. They can be used, for a short period, in temperatures up to +3000 oC. The selection of the types of thermocouple used for low temperature sensing is primarily based on materials of a thermocouple. In addition, thermopower at low temperatue israther low, so measurement of EMF will be proportionally small as well. More Facts On Various Thermocouple Types A variety of thermocouples today cover a range of temperature from -250 oC to +3000 oC. The different types of thermocouple are given letter designations: B, E, J, K, R, S, T and N Types R,S and B are noble metal thermocouples that are used to measure high temperature. Within their temperature range, they can operate for a longer period of time under an oxidizing environment. Type S and type R thermocouples are made up of platinum (Pt) and rhodium (Rh) mixed in different ratios. A specific Pt/Rh ratio is used because it leads to more stable and reproducible measurements. Types S and R have an upper temperature limit of +1200 oC in oxidizing atmospheres, assuming a wire diameter of 0.5mm. Type S and type R thermocouples are made up of platinum (Pt) and rhodium (Rh) mixed in different ratios. A specific Pt/Rh ratio is used because it leads to more stable and reproducible measurements. Types S and R have an upper temperature limit of +1200 oC in oxidizing atmospheres, assuming a wire diameter of 0.5mm. Type B thermocouples have a different Pt/Rh ratio than Type S and R. It has an upper temperature limit of +1750 oC in oxidizing atmospheres. Due to an increased amount of rhodium content, type B thermocouples are no quite so stable as either the Type R or Type S. Types E, J, K, T, and N are base-metal thermocouples that are used for sensing lower temperatures. They cannot be used for sensing high temperatures because of their relatively low melting point and slower failure due to oxidation. Type B thermocouples have a different Pt/Rh ratio than Type S and R. It has an upper temperature limit of +1750 oC in oxidizing atmospheres. Due to an increased amount of rhodium content, type B thermocouples are no quite so stable as either the Type R or Type S. we will look into some differences between different base-metal thermocouples. Type E (Ni-Cr/Cu-Ni) thermocouples have an operating temperature range from -250 oC to +800 oC. Their use is less widespread than other base-metalthermocouples due to its low operating temperature. However, measurements made by a Type E have a smaller margin of error. 1000 hours of operation in air of a Type E thermocouple at +760 oC, having 3mm wires, shold not lead to a change in EMF equivalent to more than +1 oC. Type J (Fe/Cu-Ni) thermocouples are widely used in industry due to their high thermopower and low cost. This type of thermocouple has an operating temperature range from 0 oC to +760 oC. Links to Related Lessons Temperature Sensors Thermistors Thermocouples LM35s Other Sensors Strain Gages Temperature Sensor Laboratories Return to Table of ContentsExperiments With Temperature Sensors - Data Gathering Measuring temperature is the most common measurement task. There are numerous devices available for measuring temperature. Many of them are built using one of these common sensors. Thermistor Thermocouple LM35 Integrated Circuit Temperature Sensor You can get more information about these sensors by clicking the links above. Laboratory The purpose of this laboratory is to get time response data for the three sensors you were introduced to labs week. Here are links to LabVIEW programs you can use. NTempsHydra.vi - to measure temperature from the Hydra. NVoltsHydra.vi - to measure voltage from the Hydra. ResetHydra.vi - A "sub-vi" you need to reset the Hydra. 1Temp.vi - A sub-vi that will take one temperature measurement on the Hydra. 1VoltHydra.vi - A sub-vi that will take one voltage measurement on the Hydra. You should have all the files above on your desktop. You can click on each link and save to the desktop, or you can find the NMeas folder in my public space and copy the entire folder to the desktop (best). You only need to double click the NTemps or NVolts files to start and run them in LabVIEW - but they have to be taken out of the network folder! Once you have the files together in a single folder onyour desktop, Start NTempsHydra.vi to measure temperature using the thermocouple attached to terminals 21 (yellow lead) and 22 (red lead). Note that these terminals (21 and 22) are the connections for channel 1 for the Hydra. (For example, if you were doing a manual temperature reading using the front panel, you would need to set to channel 1.) You need to connect the yellow lead of the thermocouple to the top connector for Channel #1 (Terminal #21) and the red lead of the thermocouple to the bottom connector (ground?) for Channel #1 (Terminal #22). Both of those connections are made to the connector strip on the top of the Hydra Data Acquisition Unit. Start NVoltsHydra.vi to measure voltages using the LM35 and the voltage divider circuit for the thermistor. Both sets of measurements should be taken from the front panel connection points on the Hydra. For both the LM35 and the thermistor circuit, you need to supply 5v to the circuit board. In your lab notebook record any circuitry you use, and any pertinent points regarding the equipment you use. Note any other features of each sensor that will help you for your project or make things more difficult. Do the following: Connect each sensor. Here are links to using each sensor in a measurement. Thermocouples LM35s Thermistors For each sensor you need to get data in two situations: As the sensor heats up (rising time constant behavior) As the sensor cools down to ambient temperature (decaying time constant behavior) That data should be stored in a computer file. Use a different, understandable name for each file. The program will prompt you for a file name. Suggested file names are things like ThermistorUp.txt, etc. Before you leave lab be sure that you can bring your data up in Excel (to test that you have a good data file) and that you can plot the data to see that it looks like what you expect. Estimate the following for each sensor. The time it will take for the sensor to get within 1oC when the sensor is in good thermal contact with the temperature environment being measured and the temperature sensor starts at 25 oC and goes to 50 oC. (That means tomeasure the time it takes to get to between 49 oC and 51 oC.) The time it will take for the sensor to get within 1oC of the final value when the sensor is in air at a constant temperature and the temperature sensor starts at 25oC and goes to 50oC. In other words, when will the temperature sensor reach 49oC? The time it will take for the sensor to get within 0.1oC for the two situations above. (i.e., between 49.9 oC and 50.1 oC.) The time it will take for the sensor to get within 1oC when the sensor is in good thermal contact with the temperature environment being measured and the temperature sensor starts at 50 oC and goes to 25 oC. Explain why there is a difference in the speed of the response in the various situations above. Your report should show calculations for the time constant(s) for each device, and should show the results using the three methods. Tabular presentation of the results is best. Finally, you should - as best possible - explain your results. Why would the time constant be different going up and going down.供热站温度压力实时检测热敏电阻很便宜，易于得到的温度传感器。

热电偶温度传感器参考文献

热电偶温度传感器参考文献以下是一些关于热电偶温度传感器的常见参考文献，这些文献涵盖了热电偶的基本原理、应用、特性及相关技术方面的知识：1."Temperature Measurement" by J. M. Steele•作者J. M. Steele 对温度测量原理进行了深入讲解，包括热电偶的工作原理、应用及相关技术。

这本书是温度测量领域的经典教材之一。

2."Temperature Measurement Handbook" by A. C. M. Tam•该手册提供了关于温度测量各种方法的综合概述，其中包括了热电偶原理和应用的内容，对于了解温度传感器具有很好的参考价值。

3."Industrial Temperature Measurement" by Z. K. Spakovszky•该书专注于工业领域中的温度测量技术，包括热电偶传感器的应用和优缺点。

4."Thermocouples: Theory and Properties" by I. Berge•作者I. Berge 阐述了热电偶的理论和特性，对热电偶的原理和工作方式进行了详细解释。

5."Temperature Measurement, Second Edition" by T. Dooley•这本书提供了关于温度测量技术的广泛知识，其中涵盖了热电偶传感器的原理和应用。

6."Handbook of Temperature Measurement, Volume 3: The Theory and Practice ofThermoelectric Thermometry" by A. J. Morris•这本手册讨论了热电偶传感器的理论和实践应用，包括了其在温度测量领域中的重要性和应用范围。

这些参考文献提供了关于热电偶温度传感器原理、应用、特性以及温度测量领域的深入知识。

温度传感器中英文对照外文翻译文献文

中英文对照外文翻译文献英文原文Temperature Sensor ICs Simplify DesignsWhen you set out to select a temperature sensor, you are no longer limited to either an analog output or a digital output device. There is now a broad selection of sensor types, one of which should match your system's needs.Until recently, all the temperature sensors on the market provided analog outputs. Thermistors, RTDs, and thermocouples were followed by another analog-output device, the silicon temperature sensor. In most applications, unfortunately, these analog-output devices require a comparator, an ADC, or an amplifier at their output to make them useful.Thus, when higher levels of integration became feasible, temperature sensors with digital interfaces became available. These ICs are sold in a variety of forms, from simple devices that signal when a specific temperature has been exceeded to those that report both remote and local temperatures while providing warnings at programmed temperature settings. The choice now isn't simply between analog-output and digital-output sensors; there is a broad range of sensor types from which to choose.Classes of Temperature SensorsFour temperature-sensor types are illustrated in Figure 1. An ideal analog sensor provides an output voltage that is a perfectly linear function of temperature (A). In the digital I/O class of sensor (B), temperature data in the form of multiple 1s and 0s are passed to the microcontroller, often via a serial bus. Along the same bus, data are sent to the temperature sensor from the microcontroller, usually to set the temperature limit at which the alert pin's digital output will trip. Alert interrupts the microcontroller when the temperature limit has been exceeded. This type of device can also provide fan control.Figure 1. Sensor and IC manufacturers currently offer four classes of temperature sensors."Analog-plus" sensors (C) are available with various types of digital outputs. The V OUT versus temperature curve is for an IC whose digital output switches when a specific temperature has been exceeded. In this case, the "plus" added to the analog temperature sensor is nothing more than a comparator and a voltage reference. Other types of "plus" parts ship temperature data in the form of the delay time after the part has been strobed, or in the form of the frequency or the period of a square wave, which will be discussed later.The system monitor (D) is the most complex IC of the four. In addition to the functions provided by the digital I/O type, this type of device commonly monitors the system supply voltages, providing an alarm when voltages rise above or sink below limits set via the I/O bus. Fan monitoring and/or control is sometimes included in this type of IC. In some cases, this class of device is used to determine whether or not a fan is working. More complex versions control the fan as a function of one or more measured temperatures. The system monitor sensor is not discussed here but is briefly mentioned to give a complete picture of the types of temperature sensors available.Analog-Output Temperature SensorsThermistors and silicon temperature sensors are widely used forms of analog-output temperature sensors. Figure 2 clearly shows that when a linear relationship between voltage and temperature is needed, a silicon temperature sensor is a far better choice than a thermistor. Over a narrow temperature range, however, thermistors can provide reasonable linearity and good sensitivity. Many circuits originally constructed with thermistors have over time been updated using silicon temperature sensors.Figure 2. The linearity of thermistors and silicon temperature sensors, two popular analog-output temperature detectors, is contrasted sharply.Silicon temperature sensors come with different output scales and offsets. Some, for example, are available with output transfer functions that are proportional to K, others to °C or °F. Some of the °C parts provide an offset so that negative temperatures can be monitored using a single-ended supply.In most applications, the output of these devices is fed into a comparator or a n A/D converter to convert the temperature data into a digital format. Despite the need for these additional devices, thermistors and silicon temperature sensors continue to enjoy popularity due to low cost and convenience of use in many situations.Digital I/O Temperature SensorsAbout five years ago, a new type of temperature sensor was introduced. These devices include a digital interface that permits communication with a microcontroller. The interface is usually an I²C or SMBus serial bus, but other serial interfaces such as SPI are common. In addition to reporting temperature readings to the microcontroller, the interface also receives instructions from the microcontroller. Those instructions are often temperature limits, which, if exceeded, activate a digital signal on the temperature sensor IC that interrupts the microcontroller. The microcontroller is then able to adjust fan speed or back off the speed of a microprocessor, for example, to keep temperature under control.This type of device is available with a wide variety of features, among them, remote temperature sensing. To enable remote sensing, most high-performance CPUs include an on-chip transistor that provides a voltage analog of the temperature. (Only one of the transistor's two p-n junctions is used.) Figure 3 shows a remote CPU being monitored using this technique. Other applications utilize a discrete transistor to perform the same function.Figure 3. A user-programmable temperature sensor monitors the temperature of a remote CPU's on-chip p-n junction.Another important feature found on some of these types of sensors (including the sensor shown in Figure 3) is the ability to interrupt a microcontroller when the measured temperature falls outside a range bounded by high and low limits. On other sensors, an interrupt is generated when the measured temperature exceeds either a high or a low temperature threshold (i.e., not both). For the sensor in Figure 3, those limits are transmitted to the temperature sensor via the SMBus interface. If the temperature moves above or below the circumscribed range, the alert signal interrupts the processor.Pictured in Figure 4 is a similar device. Instead of monitoring one p-n junction, however, it monitors four junctions and its own internal temperature. Because Maxim's MAX1668 consumes a small amount of power, its internal temperature is close to the ambient temperature. Measuring the ambient temperature gives an indication as to whether or not the system fan is operatingproperly.Figure 4. A user-programmable temperature sensor monitors its own local temperature and the temperatures of four remote p-n junctions.Controlling a fan while monitoring remote temperature is the chief function of the IC shown in Figure 5. Users of this part can choose between two different modes of fan control. In the PWM mode, the microcontroller controls the fan speed as a function of the measured temperature by changing the duty cycle of the signal sent to the fan. This permits the power consumption to be far less than that of the linear mode of control that this part also provides. Because some fans emit an audible sound at the frequency of the PWM signal controlling it, the linear mode can be advantageous, but at the price of higher power consumption and additional circuitry. The added power consumption is a small fraction of the power consumed by the entire system, though.Figure 5. A fan controller/temperature sensor IC uses either a PWM- or linear-mode control scheme.This IC provides the alert signal that interrupts the microcontroller when the temperature violates specified limits. A safety feature in the form of the signal called "overt" (an abbreviated version of "over temperature") is also provided. If the microcontroller or the software were to lock up while temperature is rising to a dangerous level, the alert signal would no longer be useful. However, overt, which goes active once the temperature rises above a level set via the SMBus, istypically used to control circuitry without the aid of the microcontroller. Thus, in thishigh-temperature scenario with the microcontroller not functioning, overt could be used to shut down the system power supplies directly, without the microcontroller, and prevent a potentially catastrophic failure.This digital I/O class of devices finds widespread use in servers, battery packs, and hard-disk drives. Temperature is monitored in numerous locations to increase a server's reliability: at the motherboard (which is essentially the ambient temperature inside the chassis), inside the CPU die, and at other heat-generating components such as graphics accelerators and hard-disk drives. Battery packs incorporate temperature sensors for safety reasons and to optimize charging profiles, which maximizes battery life.There are two good reasons for monitoring the temperature of a hard-disk drive, which depends primarily on the speed of the spindle motor and the ambient temperature: The read errors in a drive increase at temperature extremes, and a hard disk's MTBF is improved significantly through temperature control. By measuring the temperature within the system, you can control motor speed to optimize reliability and performance. The drive can also be shut down. In high-end systems, alerts can be generated for the system administrator to indicate temperature extremes or situations where data loss is possible.Analog-Plus Temperature Sensors"Analog-plus" sensors are generally suited to simpler measurement applications. These ICs generate a logic output derived from the measured temperature and are distinguished from digital I/O sensors primarily because they output data on a single line, as opposed to a serial bus.In the simplest instance of an analog-plus sensor, the logic output trips when a specific temperature is exceeded. Some of these devices are tripped when temperature rises above a preset threshold, others, when temperature drops below a threshold. Some of these sensors allow the temperature threshold to be adjusted with a resistor, whereas others have fixed thresholds.The devices shown in Figure 6 are purchased with a specific internal temperature threshold. The three circuits illustrate common uses for this type of device: providing a warning, shutting down a piece of equipment, or turning on a fan.Figure 6. ICs that signal when a temperature has been exceeded are well suited forover/undertemperature alarms and simple on/off fan control.When an actual temperature reading is needed, and a microcontroller is available, sensors that transmit the reading on a single line can be useful. With the microcontroller's internal counter measuring time, the signals from this type of temperature sensor are readily transformed to a measure of temperature. The sensor in Figure 7 outputs a square wave whose frequency is proportional to the ambient temperature in Kelvin. The device in Figure 8 is similar, but theperiod of the square wave is proportional to the ambient temperature in kelvins.Figure 7. A temperature sensor that transmits a square wave whose frequency is proportional tothe measured temperature in Kelvin forms part of a heater controller circuit.Figure 8. This temperature sensor transmits a square wave whose period is proportional to the measured temperature in Kelvin. Because only a single line is needed to send temperature information, just a single optoisolator is required to isolate the signal path.Figure 9, a truly novel approach, allows up to eight temperature sensors to be connected on this common line. The process of extracting temperature data from these sensors begins when the microcontroller's I/O port strobes all the sensors on the line simultaneously. The microcontroller is then quickly reconfigured as an input in order to receive data from each of the sensors. The data are encoded as the amount of time that transpires after the sensors are strobed. Each of the sensors encodes this time after the strobe pulse within a specific range of time. Collisions are avoided by assigning each sensor its own permissible time range.Figure 9. A microcontroller strobes up to eight temperature sensors connected on a common line and receives the temperature data transmitted from each sensor on the same line.The accuracy achieved by this method is surprisingly high: 0.8°C is typical at room temperature, precisely matching that of the IC that encodes temperature data in the form of the frequency of the transmitted square wave. The same is true of the device that uses the period of the square wave.These devices are outstanding in wire-limited applications. For example, when a temperature sensor must be isolated from the microcontroller, costs are kept to a minimum because only one optoisolator is needed. These sensors are also of great utility in automotive and HVAC applications, because they reduce the amount of copper running over distances.Anticipated Temperature Sensor DevelopmentsIC temperature sensors provide a varied array of functions and interfaces. As these devicescontinue to evolve, system designers will see more application-specific features as well as new ways of interfacing the sensors to the system. Finally, the ability of chip designers to integrate more electronics in the same die area ensures that temperature sensors will soon include new functions and special interfaces.中文翻译温度传感器芯片简化设计当选择一个温度传感器时，将不再局限于模拟输出或数字输出设备。

DS18B20数字式温度传感器毕业论文中英文资料外文翻译文献

中英文资料外文翻译文献The introduction to The DS18B201. DESCRIPTIONThe DS18B20 digital thermometer provides 9-bit to 12-bit Celsius temperature measurements and has an alarm function with nonvolatile user programmable upper and lower trigger points. The DS18B20 communicates over a 1-Wire bus that by definition requires only one data line for communication with a central microprocessor. It has an operating temperature range of -55°C to +125°C and is accurate to ±0.5°C over the range of -10°C to +85°C. In addition, the DS18B20 can derive power directly from the data line (“parasite power”), eliminating the need for an external power supply.Each DS18B20 has a unique 64-bit serial code, which allows multiple DS18B20s to function on the same 1-Wire bus. Thus, it is simple to use one microprocessor to control many DS18B20s distributed over a large area. Applications that can benefit from this feature include HV AC environmental controls, temperature monitoring systems inside buildings, equipment, or machinery, and process monitoring and control systems.2.FEATURES●Unique 1-Wire® Interface Requires Only One Port Pin for Communication●Each Device has a Unique 64-Bit Serial Code Stored in an On-Board ROM●Multi-drop Capability Simplifies Distributed Temperature-Sensing Applications ●Requires No External Components●Can Be Powered from Data Line; Power Supply Range is 3.0V to 5.5V1●Measures Temperatures from -55°C to +125°C (-67°F to +257°F)●±0.5°C Accuracy from -10°C to +85°C●Thermometer Resolution is User Selectable from 9 to 12 Bits●Converts Temperature to 12-Bit Digital Word in 750ms (Max)●User-Definable Nonvolatile (NV) Alarm Settings●Alarm Search Command Identifies and Addresses Devices Whose Temperature isOutside Programmed Limits●Software Compatible with the DS1822●Applications Include Thermostatic Controls, Industrial Systems, ConsumerProducts, Thermometers, or Any Thermally Sensitive System3.OVERVIEWFigure 1 shows a block diagram of the DS18B20, and pin descriptions are given in the Pin Description table. The 64-bit ROM stores the device’s unique serial code. The scratchpad memory contains the 2-byte temperature register that stores the digital output from the temperature sensor. In addition, the scratchpad provides access to the 1-byte upper and lower alarm trigger registers (TH and TL) and the 1-byte configuration register. The configuration register allows the user to set the resolution of the temperature to-digital conversion to 9, 10, 11, or 12 bits. The TH, TL, and configuration registers are nonvolatile (EEPROM), so they will retain data when the device is powered down.The DS18B20 uses Maxim’s exclusive 1-Wire bus protocol that implements bus communication using one control signal. The control line requires a weak pull up resistor since all devices are linked to the bus via a 3-state or open-drain port (the DQ pin in the case of the DS18B20). In this bus system, the microprocessor (the master device) identifies and addresses devices on the bus using each device’s unique 64-bit code. Because each device has a unique code, the number of devices that can be addressed on one DS18B20 bus is virtually unlimited. The 1-Wire bus protocol, including detailed explanations of the commands and “time slots,” is covered in the21-Wire Bus System section.Another feature of the DS18B20 is the ability to operate without an external power supply. Power is instead supplied through the 1-Wire pull up resistor via the DQ pin when the bus is high. The high bus signal also charges an internal capacitor (CPP), which then supplies power to the device when the bus is low. This method of deriving power from the 1-Wire bus is referred to as “parasite power.” As an alternative, the DS18B20 may also be powered by an external supply on VDD.Figure 1.DS18B20 Block Diagram4.OPERATION—MEASURING TEMPERATURThe core functionality of the DS18B20 is its direct-to-digital temperature sensor. The resolution of the temperature sensor is user-configurable to 9, 10, 11, or 12 bits, corresponding to increments of 0.5°C, 0.25°C, 0.125°C, and 0.0625°C, respectively. The default resolution at power-up is 12-bit. The DS18B20 powers up in a low-power idle state. To initiate a temperature measurement and A-to-D conversion, the master must issue a Convert T [44h] command. Following the conversion, the resulting thermal data is stored in the 2-byte temperature register in the scratchpad memory and the DS18B20 returns to its idle state. If the DS18B20 is powered by an external supply, t he master can issue “read time slots” (see the 1-Wire Bus System section) after the Convert T command and the DS18B20 will respond by transmitting 0 while the temperature conversion is in progress and 1 when the conversion is done. If the3DS18B20 is powered with parasite power, this notification technique cannot be used since the bus must be pulled high by a strong pull up during the entire temperature conversion.The DS18B20 output temperature data is calibrated in degrees Celsius; for Fahrenheit applications, a lookup table or conversion routine must be used. The temperature data is stored as a 16-bit sign-extended two’s complement number in the temperature register (see Figure 2). The sign bits (S) indicate if the temperature is positive or negative: for positive numbers S = 0 and for negative numbers S = 1. If the DS18B20 is configured for 12-bit resolution, all bits in the temperature register will contain valid data. For 11-bit resolution, bit 0 is undefined. For 10-bit resolution, bits 1 and 0 are undefined, and for 9-bit resolution bits 2, 1, and 0 are undefined. Table 1 gives examples of digital output data and the corresponding temperature reading for 12-bit resolution conversions.5.64-BIT LASERED ROM CODEEach DS18B20 contains a unique 64–bit code (see Figure 3) stored in ROM. The least significant 8 bits of the ROM code contain the DS18B20’s 1-Wire family4code: 28h. The next 48 bits contain a unique serial number. The most significant 8 bits contain a cyclic redundancy check (CRC) byte that is calculated from the first 56 bits of the ROM code. The 64-bit ROM code and associated ROM function control logic allow the DS18B20 to operate as a 1-Wire device using the protocol detailed in the 1-Wire Bus System section.Figure 3.64-Bit Lasered ROM Code6.MEMORYThe DS18B20’s memory is organized as shown in Figure 4. The memory consists of an SRAM scratchpad with nonvolatile EEPROM storage for the high and low alarm trigger registers (TH and TL) and configuration register. Note that if the DS18B20 alarm function is not used, the TH and TL registers can serve as general-purpose memory.Byte 0 and byte 1 of the scratchpad contain the LSB and the MSB of the temperature register, respectively. These bytes are read-only. Bytes 2 and 3 provide access to TH and TL registers. Byte 4 contains the configuration register data. Bytes 5, 6, and 7 are reserved for internal use by the device and cannot be overwritten. Byte 8 of the scratchpad is read-only and contains the CRC code for bytes 0 through 7 of the scratchpad. The DS18B20 generates this CRC using the method described in the CRC Generation section.Data is written to bytes 2, 3, and 4 of the scratchpad using the Write Scratchpad [4Eh] command; the data must be transmitted to the DS18B20 starting with the least significant bit of byte 2. To verify data integrity, the scratchpad can be read (using the Read Scratchpad [BEh] command) after the data is written. When reading the scratchpad, data is transferred over the 1-Wire bus starting with the least significant bit of byte 0. To transfer the TH, TL and configuration data from the scratchpad to EEPROM, the master must issue the Copy Scratchpad [48h] command.57.CONFIGURATION REGISTERByte 4 of the scratchpad memory contains the configuration register, which is organized as illustrated in Figure 5. The user can set the conversion resolution of the DS18B20 using the R0 and R1 bits in this register as shown in Table 2. The power-up default of these bits is R0 = 1 and R1 = 1 (12-bit resolution). Note that there is a direct tradeoff between resolution and conversion time. Bit 7 and bits 0 to 4 in the configuration register are reserved for internal use by the device and cannot be overwritten.68.1-WIRE BUS SYSTEMThe 1-Wire bus system uses a single bus master to control one or more slave devices. The DS18B20 is always a slave. When there is only one slave on the bus, the system is referred to as a “single-drop” system; the system is “multi-drop” if there are multiple slaves on the bus. All data and commands are transmitted least significant bit first over the 1-Wire bus. The following discussion of the 1-Wire bus system is broken down into three topics: hardware configuration, transaction sequence, and1-Wire signaling (signal types and timing).9.TRANSACTION SEQUENCEThe transaction sequence for accessing the DS18B20 is as follows:Step 1. InitializationStep 2. ROM Command (followed by any required data exchange)Step 3. DS18B20 Function Command (followed by any required data exchange)It is very important to follow this sequence every time the DS18B20 is accessed, as the DS18B20 will not respond if any steps in the sequence are missing or out of order. Exceptions to this rule are the Search ROM [F0h] and Alarm Search [ECh] commands. After issuing either of these ROM commands, the master must return to Step 1 in the sequence.（1）INITIALIZATIONAll transactions on the 1-Wire bus begin with an initialization sequence. The initialization sequence consists of a reset pulse transmitted by the bus master followed by presence pulse(s) transmitted by the slave(s). The presence pulse lets the bus master know that slave devices (such as the DS18B20) are on the bus and are ready to operate.（2）ROM COMMANDS7After the bus master has detected a presence pulse, it can issue a ROM command. These commands operate on the unique 64-bit ROM codes of each slave device and allow the master to single out a specific device if many are present on the 1-Wire bus. These commands also allow the master to determine how many and what types of devices are present on the bus or if any device has experienced an alarm condition. There are five ROM commands, and each command is 8 bits long. The master device must issue an appropriate ROM command before issuing a DS18B20 function command.1.SEARCH ROM [F0h]When a system is initially powered up, the master must identify the ROM codes of all slave devices on the bus, which allows the master to determine the number of slaves and their device types. The master learns the ROM codes through a process of elimination that requires the master to perform a Search ROM cycle (i.e., Search ROM command followed by data exchange) as many times as necessary to identify all of the slave devices. If there is only one slave on the bus, the simpler Read ROM command can be used in place of the Search ROM process.2.READ ROM [33h]This command can only be used when there is one slave on the bus. It allows the bus master to read the slave’s 64-bit ROM code without using the Search ROM procedure. If this command is used when there is more than one slave present on the bus, a data collision will occur when all the slaves attempt to respond at the same time.3.MATCH ROM [55h]The match ROM command followed by a 64-bit ROM code sequence allows the bus master to address a specific slave device on a multi-drop or single-drop bus. Only the slave that exactly matches the 64-bit ROM code sequence will respond to the function command issued by the master; all other slaves on the bus will wait for a reset pulse.84.SKIP ROM [CCh]The master can use this command to address all devices on the bus simultaneously without sending out any ROM code information. For example, the master can make all DS18B20s on the bus perform simultaneous temperature conversions by issuing a Skip ROM command followed by a Convert T [44h] command. Note that the Read Scratchpad [BEh] command can follow the Skip ROM command only if there is a single slave device on the bus. In this case, time is saved by allowing the master to read from the slave without sending the device’s 64-bit ROM code. A Skip ROM command followed by a Read Scratchpad command will cause a data collision on the bus if there is more than one slave since multiple devices will attempt to transmit data simultaneously.5.ALARM SEARCH [ECh]The operation of this command is identical to the operation of the Search ROM command except that only slaves with a set alarm flag will respond. This command allows the master device to determine if any DS18B20s experienced an alarm condition during the most recent temperature conversion. After every Alarm Search cycle (i.e., Alarm Search command followed by data exchange), the bus master must return to Step 1 (Initialization) in the transaction sequence.（3）DS18B20 FUNCTION COMMANDSAfter the bus master has used a ROM command to address the DS18B20 with which it wishes to communicate, the master can issue one of the DS18B20 function commands. These commands allow the master to write to and read from the D S18B20’s scratchpad memory, initiate temperature conversions and determine the power supply mode.1.CONVERT T [44h]This command initiates a single temperature conversion. Following the conversion, the resulting thermal data is stored in the 2-byte temperature register in9the scratchpad memory and the DS18B20 returns to its low-power idle state. If the device is being used in parasite power mode, within 10µs (max) after this command is issued the master must enable a strong pull up on the 1-Wire bus. If the DS18B20 is powered by an external supply, the master can issue read time slots after the Convert T command and the DS18B20 will respond by transmitting a 0 while the temperature conversion is in progress and a 1 when the conversion is done. In parasite power mode this notification technique cannot be used since the bus is pulled high by the strong pull up during the conversion.2.READ SCRATCHPAD [BEh]This command allows the master to read the contents of the scratchpad. The data transfer starts with the least significant bit of byte 0 and continues through the scratchpad until the 9th byte (byte 8 – CRC) is read. The master may issue a reset to terminate reading at any time if only part of the scratchpad data is needed.3.WRITE SCRATCHPAD [4Eh]This comm and allows the master to write 3 bytes of data to the DS18B20’s scratchpad. The first data byte is written into the TH register (byte 2 of the scratchpad), the second byte is written into the TL register (byte 3), and the third byte is written into the configuration register (byte 4). Data must be transmitted least significant bit first. All three bytes MUST be written before the master issues a reset, or the data may be corrupted.4.COPY SCRATCHPAD [48h]This command copies the contents of the scratchpad TH, TL and configuration registers (bytes 2, 3 and 4) to EEPROM. If the device is being used in parasite power mode, within 10µs (max) after this command is issued the master must enable a strong pull-up on the 1-Wire bus.5.RECALL E2 [B8h]This command recalls the alarm trigger values (TH and TL) and configuration10data from EEPROM and places the data in bytes 2, 3, and 4, respectively, in the scratchpad memory. The master device can issue read time slots following the Recall E2command and the DS18B20 will indicate the status of the recall by transmitting 0 while the recall is in progress and 1 when the recall is done. The recall operation happens automatically at power-up, so valid data is available in the scratchpad as soon as power is applied to the device.6．READ POWER SUPPL Y [B4h]The master device issues this command followed by a read time slot to determine if any DS18B20s on the bus are using parasite power. During the read time slot, parasite powered DS18B20s will pull the bus low, and externally powered DS18B20s will let the bus remain high.10.WIRE SIGNALINGThe DS18B20 uses a strict 1-Wire communication protocol to ensure data integrity. Several signal types are defined by this protocol: reset pulse, presence pulse, write 0, write 1, read 0, and read 1. The bus master initiates all these signals, with the exception of the presence pulse.（1）INITIALIZATION PROCEDURE—RESET AND PRESENCE PULSES All communication with the DS18B20 begins with an initialization sequence that consists of a reset pulse from the master followed by a presence pulse from the DS18B20. This is illustrated in Figure 6. When the DS18B20 sends the presence pulse in response to the reset, it is indicating to the master that it is on the bus and ready to operate.During the initialization sequence the bus master transmits (TX) the reset pulse by pulling the 1-Wire bus low for a minimum of 480µs. The bus master then releases the bus and goes into receive mode (RX). When the bus is released, the 5kΩ pull-up resistor pulls the 1-Wire bus high. When the DS18B20 detects this rising edge, it waits 15µs to 60µs and then transmits a presence pulse by pulling the 1-Wire bus low11for 60µs to 240µs.TimingBus master pulling lowDS18B20 pulling lowResistor pullupFigure 6.Initialization Timing（2）READ/WRITE TIME SLOTSThe bus master writes data to the DS18B20 during write time slots and reads data from the DS18B20 during read time slots. One bit of data is transmitted over the 1-Wire bus per time slot.1.WRITE TIME SLOTSThere are two types of write time slots: “Write 1” time slots and “Write 0” time slots. The bus master uses a Write 1 time slot to write a logic 1 to the DS18B20 and a Write 0 time slot to write a logic 0 to the DS18B20. All write time slots must be a minimum of 60µs in duration with a minimum of a 1µs recovery time between individual write slots. Both types of write time slots are initiated by the master pulling the 1-Wire bus low (see Figure 7).To generate a Write 1 time slot, after pulling the 1-Wire bus low, the bus master must release the 1-Wirebus within 15µs. When the bus is released, the 5kΩ pull-up resistor will pull the bus high. To generate a Write 0 time slot, after pulling the 1-Wire bus low, the bus master must continue to hold the bus low for the duration of the time slot (at least 60µs).The DS18B20 samples the 1-Wire bus during a window that lasts from 15µs1213to 60µs after the master initiates the write time slot. If the bus is high during the sampling window, a 1 is written to the DS18B20. If the line is low, a 0 is written to the DS18B20.DS18B20Write Time SlotSTART OF SLOTVccBus master pulling low Resistor pullupFigure 7.DS18B20 Write Time Slot2.READ TIME SLOTSThe DS18B20 can only transmit data to the master when the master issues read time slots. Therefore, the master must generate read time slots immediately after issuing a Read Scratchpad [BEh] or Read Power Supply [B4h] command, so that the DS18B20 can provide the requested data. In addition, the master can generate read time slots after issuing Convert T [44h] or Recall E 2 [B8h] commands to find out the status of the operation.All read time slots must be a minimum of 60µs in duration with a minimum of a 1µs recovery time between slots. A read time slot is initiated by the master device pulling the 1-Wire bus low for a minimum of 1µs and then releasing the bus (see Figure 8). After the master initiates the read time slot, the DS18B20 will begin transmitting a 1 or 0 on bus. The DS18B20 transmits a 1 by leaving the bus high and transmits a 0 by pulling the bus low. When transmitting a 0, the DS18B20 will release the bus by the end of the time slot, and the bus will be pulled back to its high idle state by the pull up resister. Output data from the DS18B20 is valid for 15µs after the falling edge that initiated the read time slot. Therefore, the master must release thebus and then sample the bus state within 15µs from the start of the slot.VccBus master pulling lowResistor pullupDS18B20 pulling lowFigure 8.DS18B20 Read Time Slot1415DS18B20介绍1.说明DS18B20数字式温度传感器提供9位到12位的摄氏温度测量，并且有用户可编程的、非易失性温度上下限告警出发点。

英文文献翻译--温度传感器简单集成电路的设计

XX 大学毕业设计(论文)外文资料翻译学院：系（专业）：电子信息工程姓名：学号：外文出处：Jay Scolio，Maxim Integrated ProductsInc.(用外文写)附件：1.外文资料翻译译文；2.外文原文。

附件1：外文资料翻译译文温度传感器简单集成电路的设计当选择一个温度传感器的时候,将不再限制在模拟输出或数字输出装置。

与你系统需要相匹配的传感器类型现在有很大的选择空间。

市场上供应的所有温度感应器都是模拟输出。

热电阻， RTDs 和热电偶是另一种输出装置,矽温度感应器。

在多数的应用中，这些模拟输出装置在有效输出时需要一个比较器 , ADC, 或一个扩音器。

因此，当更高技术的集成变成可能的时候,有数字接口的温度传感器变成现实。

这些集成电路被以多种形式出售,从超过特定的温度时才有信号简单装置,到那些报告远的局部温度提供警告的装置。

现在不只是在模拟输出和数字输出传感器之间选择，还有那些应该与你的系统需要相匹配的更广阔的感应器类型的选择。

温度传感器的类型：图 1：传感器和集成电路制造商提供的四种温度传感器在图1中举例说明四种温度感应器类型。

一个理想模拟传感器提供一个完全线性的功能输出电压（A）。

在传感器(B)的数字I/O类中, 温度数据通常通过一个串行总线传给微控制器。

沿着相同的总线，数据由温度传感器传到微控制器,通常设定温度界限在引脚得数字输出将下降的时候。

当超过温度界限的时候，报警中断微控制器。

这个类型的装置也提供风扇控制。

"模拟正量"传感器(C)被应用在多种类型的数字输出上。

当超过特定温度的时候 , V OUT 对温度曲线是一个数字输出。

在这情况，增加到模拟温度传感器的"正信号"只不过是一个比较器和参考电压。

其他的类型"正信号"部分在以频率和方波的形式储存以后被延迟,这些将会在以后讨论。

系统监视器(D)是四种类型当中最复杂的集成电路。

传感器的基础知识论文中英文资料对照外文翻译

传感器的根底知识论文中英文资料对照外文翻译英文文献翻译中英文资料对照外文翻译Basic knowledge of transducersA transducer is a device which converts the quantity being measured into an optical, mechanical, or-more commonly-electrical signal. Theenergy-conversion process that takes place is referred to as transduction.Transducers are classified according to the transduction principle involved and the form of the measured. Thus a resistance transducer for measuring displacement is classified as a resistance displacement transducer. Other classification examples are pressure bellows, force diaphragm, pressure flapper-nozzle, and so on. 1、Transducer Elements Although there are exception ,most transducers consist of a sensing element and a conversion or control element. For example, diaphragms,bellows,strain tubes and rings, bourdon tubes, and cantilevers are sensing elements which respond to changes in pressure or force and convert these physical quantities into a displacement. This displacement may then be used to change an electrical parameter such as voltage, resistance, capacitance, or inductance. Such combination of mechanical and electrical elements form electromechanical transducing devices or transducers. Similar combination can be made for other energy input such as thermal. Photo, magnetic and chemical,giving thermoelectric, photoelectric,electromaanetic, and electrochemical transducers respectively. 2、Transducer SensitivityThe relationship between the measured and the transducer output signal is usually obtained by calibration tests and is referred to as the transducer sensitivity K1= output-signal increment / measured increment .In practice, the transducer sensitivity is usually known, and, by measuring the output signal, the input quantity is determined from input= output-signal increment / K1.3、Characteristics of an Ideal TransducerThe high transducer should exhibit the following characteristicsa) high fidelity-the transducer output waveform shape be a faithful reproduction of the measured; there should be minimum distortion.b) There should be minimum interference with the quantity being measured; the presence of the transducer should not alter the measured in any way.c) Size. The transducer must be capable of being placed exactly where it is needed.1英文文献翻译d) There should be a linear relationship between the measured and the transducer signal. e) The transducer should have minimum sensitivity to external effects, pressuretransducers,for example,are often subjected to external effects such vibration and temperature. f) The natural frequency of the transducer should be well separated from the frequency and harmonics of the measurand.4、Electrical TransducersElectrical transducers exhibit many of the ideal characteristics. In addition they offer high sensitivity as well as promoting the possible of remote indication or mesdurement. Electrical transducers can be divided into two distinct groups: a) variable-control-parameter types,which include: i)resistance ii) capacitance iii) inductanceiv) mutual-inductance typesThese transducers all rely on external excitation voltage for their operation. b) self-generating types,which include i) electromagnetic ii)thermoelectric iii)photoemissive iv)piezo-electric typesThese all themselves produce an output voltage in response to the measurand input and their effects are reversible. For example, a piezo-electric transducer normally produces an output voltage in response to the deformation of a crystalline material; however, if an alternating voltage is applied across the material, the transducer exhibits the reversible effect by deforming or vibrating at the frequency of the alternating voltage. 5、Resistance TransducersResistance transducers may be divided into two groups, as follows: i) Those which experience a large resistance change, measured by using potential-divider methods. Potentiometers are in this group.ii)Those which experience a small resistance change, measured by bridge-circuit methods. Examples of this group include strain gauges and resistance thermometers. 5.1 PotentiometersA linear wire-wound potentiometer consists of a number of turns resistance wire wound around a non-conducting former, together with a wiping contact which travels over the barwires. The construction principles are shown in figure which indicate that the wiper2英文文献翻译displacement can be rotary, translational, or a combination of both to give a helical-type motion. The excitation voltage may be either a.c. or d.c. and the output voltage is proportional to the input motion, provided the measuring device has a resistance which is much greater than the potentiometer resistance.Such potentiometers suffer from the linked problem of resolution and electrical noise. Resolution is defined as the smallest detectable change in input and is dependent on the cross-sectional area of the windings and the area of the sliding contact. The output voltage is thus a serials of steps as the contact moves from one wire to next.Electrical noise may be generated by variation in contact resistance, by mechanical wear due to contact friction, and by contact vibration transmitted from the sensing element. In addition, the motion being measured may experience significant mechanical loading by the inertia and friction of the moving parts of the potentiometer. The wear on the contacting surface limits the life of a potentiometer to a finite number of full strokes or rotations usually referred to in the manufacture’s specification as the ‘number of cycles of life expectancy’, a typical value being 20*1000000 cycles.The output voltage V0 of the unload potentiometer circuit is determined as follows. Let resistance R1= xi/xt *Rt where xi = input displacement, xt= maximum possible displacement, Rt total resistance of the potentiometer. Then output voltage V0= V*R1/(R1+( Rt-R1))=V*R1/Rt=V*xi/xt*Rt/Rt=V*xi/xt. This shows that there is a straight-line relationship between output voltage and input displacement for the unloaded potentiometer. It would seen that high sensitivity could be achieved simply by increasing the excitation voltage V. however, the maximum value of V is determined by the maximum power dissipation P of the fine wires of the potentiometer winding and is given by V=(PRt)1/2 . 5.2 Resistance Strain GaugesResistance strain gauges are transducers which exhibit a change in electrical resistance in response to mechanical strain. They may be of the bonded or unbonded variety . a) bonded strain gaugesUsing an adhesive, these gauges are bonded, or cemented, directly on to the surface of the body or structure which is being examined. Examples of bonded gauges arei) fine wire gauges cemented to paper backingii) photo-etched grids of conducting foil on an epoxy-resin backingiii)a single semiconductor filament mounted on an epoxy-resin backing with copper or nickel leads.Resistance gauges can be made up as single elements to measuring strain in one direction only,3英文文献翻译or a combination of elements such as rosettes will permit simultaneous measurements in more than one direction. b) unbonded strain gauges A typical unbonded-strain-gauge arrangement shows fine resistance wires stretched around supports in such a way that the deflection of the cantilever spring system changes the tension in the wires and thus alters the resistance of wire. Such an arrangement may be found in commercially available force, load, or pressure transducers. 5.3 Resistance Temperature TransducersThe materials for these can be divided into two main groups:a) metals such as platinum, copper, tungsten, and nickel which exhibit and increase in resistance as the temperature rises; they have a positive temperature coefficient of resistance. b) semiconductors, such as thermistors which use oxides of manganese, cobalt, chromium, or nickel. These exhibit large non-linear resistance changes with temperature variation and normally have a negative temperature coefficient of resistance. a) metal resistance temperature transducersThese depend, for many practical purpose and within a narrow temperature range, upon the relationship R1=R0*[1+a*(b1-b2)] where a coefficient of resistance in ℃-1,and R0 resistance in ohms at the reference temperature b0=0℃ at the reference temperature range ℃.℃℃. b) thermistor resistance temperature transducersThermistors are temperature-sensitive resistors which exhibit large non-liner resistance changes with temperature variation. In general, theyhave a negative temperature coefficient. For small temperature increments the variation in resistance is reasonably linear; but, if large temperature changes are experienced, special linearizing techniques are used in the measuring circuits to produce a linear relationship of resistance against temperature.Thermistors are normally made in the form of semiconductor discs enclosed in glass vitreous enamel. Since they can be made as small as 1mm,quite rapid response times are possible. 5.4 Photoconductive Cells The photoconductive cell , uses a light-sensitive semiconductor material. The resistance between the metal electrodes decrease as the intensity of the light striking the semiconductor increases. Common semiconductor materials used for photo-conductive cells are cadmium sulphide, lead sulphide, and copper-doped germanium.The useful range of frequencies is determined by material used. Cadmium sulphide is mainly suitable for visible light, whereas lead sulphide has its peak response in the infra-red region4英文文献翻译and is, therefore , most suitable for flame-failure detection and temperature measurement. 5.5 Photoemissive CellsWhen light strikes the cathode of the photoemissive cell are given sufficient energy to arrive the cathode. The positive anode attracts these electrons, producing a current which flows through resistor R and resulting in an output voltage V. Photoelectrically generated voltage V=Ip.RlWhere Ip=photoelectric current(A),and photoelectric current Ip=Kt.B Where Kt=sensitivity (A/im),and B=illumination input (lumen)Although the output voltage does give a good indication of the magnitude of illumination, the cells are more often used for counting or controlpurpose, where the light striking the cathode can be interrupted. 6、Capacitive TransducersThe capacitance can thus made to vary by changing either the relative permittivity, the effective area, or the distance separating the plates. The characteristic curves indicate that variations of area and relative permittivity give a linear relationship only over a small range of spacings. Thus the sensitivity is high for small values of d. Unlike the potentionmeter, the variable-distance capacitive transducer has an infinite resolution making it most suitable for measuring small increments of displacement or quantities which may be changed to producea displacement.7、Inductive TransducersThe inductance can thus be made to vary by changing the reluctance of the inductive circuit. Measuring techniques used with capacitive and inductive transducers: a)A.C. excited bridges using differential capacitors inductors. b)A.C. potentiometer circuits for dynamic measurements.c) D.C. circuits to give a voltage proportional to velocity for a capacitor.d) Frequency-modulation methods, where the change of C or L varies the frequency of an oscillation circuit.Important features of capacitive and inductive transducers are as follows: i)resolution infiniteii) accuracy+- 0.1% of full scale is quoted iii)displacement ranges 25*10-6 m to 10-3m iv) rise time less than 50us possibleTypical measurands are displacement, pressure, vibration, sound, and liquid level. 8、 Linear Variable-differential Ttransformer 9、Piezo-electric Transducers5。

传感器技术外文文献及中文翻译

Sensor technologyA sensor is a device which produces a signal in response to its detecting or measuring a property ，such as position , force ，torque ，pressure ，temperature ，humidity , speed ，acceleration , or vibration 。

Traditionally ，sensors (such as actuators and switches ）have been used to set limits on the performance of machines 。

Common examples are （a）stops on machine tools to restrict work table movements ，(b）pressure and temperature gages with automatics shut—off features ，and (c) governors on engines to prevent excessive speed of operation . Sensor technology has become an important aspect of manufacturing processes and systems .It is essential for proper data acquisition and for the monitoring , communication ，and computer control of machines and systems 。

Because they convert one quantity to another ，sensors often are referred to as transducers .Analog sensors produce a signal ，such as voltage ,which is proportional to the measured quantity 。

传感器温湿度测量中英文资料外文翻译文献

中英文资料外文翻译文献SHT11/71传感器的温湿度测量Assist.Prof.Grish Spasov,PhD,BSc Nikolay KakanakovDepartment of Computer Systems,Technical University-branch Plovdiv,25,”Tzanko Djustabanov”Str.,4000Plovdiv,Bulgaria,+35932659576, E-mail:gvs@tu-plovdiv.bg,kakanak@tu-plovdiv.bg 关键词：温湿度测量，智能传感器，分布式自动测控这篇论文阐述了智能传感器的优点，介绍了SHT11/71温湿度传感器（产自盛世瑞公司）。

该传感器是一种理想的对嵌入式系统提供环境测量参数的传感器。

常规的应用时将SHT11/71放于实际的工作环境当中。

应用于分布式的温湿度监测系统。

使用单片机与集成网络服务器来实现对传感器的信息交流与关系。

这个应用是可实现与测试的。

1.介绍温湿度的测量控制对于电器在工业、科学、医疗保健、农业和工艺控制过程都有着显著地意义。

温湿度这两种环境参数互相影响，因为这至关重要的一点，在一些应用中他们是必须并联测量的。

SHT11/71是利用现代技术把温度、湿度测量元件、放大器、A/D转换器、数字接口、校验CRC计算逻辑记忆模块和核心芯片集成到一个非常小的尺寸上[1][3]。

采用这种智能传感器可以缩短产品开发时间和成本。

整合入传感器模数转换和放大器的芯片使开发人员能够优化传感器精度和长期问的的元素。

并不是全结合形式的数字逻辑接口连通性管理的传感器。

这些优点可以减少整体上市时间，甚至价格[1][3]。

本文以SHT11/71（产自盛世瑞公司）智能传感器为例，介绍他的优势和测量程序给出一个实用实例来说明该工作的实现条件。

这个应用时可行可测试的。

2.智能传感器——SHT11/71SHT11/71是一个继承了温度和湿度组建，以及一个多元化校准数字器的芯片。

温度测量热电偶-外文文献及译文2

外文文献翻译文献、资料中文题目：温度测量 - 热电偶文献、资料英文题目：文献、资料来源：文献、资料发表（出版）日期：院（部）：专业：班级：姓名：学号：指导教师：翻译日期： 2017.02.14University of TasmaniaSchool of EngineeringKNE222 Electronic EngineeringTemperature Measurement – ThermocouplesIntroduction.A thermocouple is formed when two dissimilar metals are joined. If a second joint is made from the same materials, and one joint is heated with respect to the other, then a current will flow round the loop. Alternatively, if the circuit is opened, then a small voltage will appear at these terminals, proportional to the difference in temperature between the junctions. This voltage is known as the Seebeck voltage, after Thomas Seebeck who discovered the phenomenon in 1821.Figure 1. Conceptual Application of a Thermocouple(Ref: ”Operational Amplifier Circuits Theory and Applications” E.J Kennedy. HRW Inc.)In order to use a thermocouple to measure temperature with one junction, a reference temperature must be established for the other. This can be done as illustrated in Figure 1, where a 0 ºC ice bath is provided for the reference junction. However an ice bath is not really practical for everyday measurements. Fortunately it is possible to introduce a correction voltage into the circuit so that the reference junction appears to be at zero degrees C. An example of this will be presented later.Thermocouple Characteristics.Table 1 provides a list of commonly used thermocouple materials, together with the useful range of temperatures for each. While the Seebeck voltage increases with the junction temperature difference, the relationship is unfortunately not entirely linear. The proportionality constant is known as the Seebeck coefficient, α, and has the units μV/ºC. Table 1 provides typical α values at 25 ºC; it also gives some idea of how α varies over the useable temperature range for each thermocouple.Table 1. Characteristics of common Thermocouples(Ref: “Operational Amplifier Circuits Theory and Applications” E.J Kennedy. HRW Inc.)Figure 2 shows the variation of α as a function of temperature for K and T Type thermocouples. The K type device offers almost constant α values over much of its useful range, and therefore is useable there without linearization. In contrast, the Seebeck coefficient of the T type thermocouple varies considerably with temperature and as a result these devices must be corrected using a linearization algorithm in order to obtain accurate temperature measurements.Figure 2. Variation of the Seebeck Coefficient with Temperature, T and K Type Thermocouples.(Ref: ”Operational Amplifier Circuits Theory and Applications” E.J Kennedy. HRW Inc.)Finally, figure 3 shows the Seebeck Voltage as a function of temperature difference for the thermocouples listed in Table 1. In each case the reference junction (sometimes called the cold junction ), is held at zero ºC, thus all these curves pass through the origin. Because they are slightly non-linear, it is common to apply a linearization algorithm to the Seebeck Voltage (E), in order to obtain the correct temperature (T). In its simplest form this algorithm assumes that the relationship between Seebeck Voltage and temperature is linear and an equation of the form αE T = is used. This assumption results in errors, particularly over a wide range of temperatures. For more accurate results, higher order polynomials are used.Figure 3. Seebeck Voltage as a function of Temperature Difference.(Note: The Reference Junction temperature is 0 ºC.)(Ref: ”Operational Amplifier Circuits Theory and Applications” E.J Kennedy. HRW Inc.)A Practical Thermocouple Circuit. The schematic shown in Figure 5 is that of an electronically compensated thermocouple amplifier. In this case a J type thermocouple (Iron-Constantan ) has been used. The two metallic junctions that make up this thermocouple, J1 and J2, are shown on the diagram. J1 is the sense junction, while J2 is the reference junction . Ideally J2 should be held in an ice bath at 0ºC, as shown in Figure 1, however this is generally inconvenient. Instead it is more usual to provide electronic reference junction compensation . This involves measuring the temperature of the reference junction and adding a compensating voltage to the thermocouple, so that the residual Seebeck voltage matches that of a similar thermocouple with its reference junction held at 0ºC.Generation of a Compensation VoltageTable 2 shows the Seebeck voltage as function of temperature for J type thermocouples, (referenced to 0ºC). From this we see that the thermocouple voltage will be 1.277mV when the sense junction is at room temperature, (25ºC or 298ºK). Therefore this voltage must be subtracted from the thermocouple potential, when the reference junction is at 25ºC , in order to leave a potential proportional only to the sense junction temperature.If we can keep the reference junction firmly at 25ºC, then this fixed compensation voltage will suffice. However this is generally impractical, and as ambient conditions change so will the reference junction temperature, and with it the required compensation voltage as well.On the other hand, if the compensation voltage is made to vary with temperature , in just the right way, then changes in ambient temperature can be compensated for automatically. Specifically, if the compensation voltage has a temperature coefficient equal to the Seebeck coefficient for the thermocouple in question, at say 25ºC, then ambient changes around this temperature will automatically be compensated for.Let the input voltage to the differential amplifier, IC2 in Figure 5, be V i (T s ) where T s is the temperature of the sense junction (J 1). (IC2 is an Instrumentation Amplifier* provided simply to amplify the net thermocouple voltage to more useable levels.) This voltage will equal the difference between the junction potentials (1j V and 2j V ), plus the compensation voltage, V c (T a ). Remember that the reference junction, (J 2) is at ambient temperature , and that the compensation potential must therefore be a function of the ambient temperature as well. Thus we can write:…(1))0()()()()()(2121j s j a c a j s j s i V T V T V T V T V T V -=+-=So )()0()(22a c j a j T V V T V =- (2)Therefore the compensation voltage must equal the difference between the ambient reference junction voltage and the reference voltage at 0ºC . Equation (2) shows that if T a =0 ºC then 0)0(=c V . Equation (1) shows that when T s = T a = 25 ºC then V c (25) = V i (25) = 1.277mV since this is the Seebeck voltage generated when the junction difference is 25ºC. Finally by differentiating equation (2) we see that the compensation voltage temperature coefficient must equal that of the thermocouple, (α). Figure 4 summarizes this information.Figure 4. Compensation Voltage vs Temperature* An Instrumentation Amplifier is a special form of differential amplifier, designed for large voltage gains and having a high Common Mode Rejection Ratio.The circuit in Figure 5 generates this compensation voltage and applies it together with the thermocouple voltage, to the differential amplifier, IC2. The isothermal block , shown dotted, contains both the thermocouple terminals as well and the reference junction, J2. It also contains an AD590 integrated circuit. This device generates a temperature dependent DC current with a sensitivity of 1μA/ºK. Thus at room temper ature, (298ºK) this current equals 298μA. It is assumed that everything within the isothermal block remains at ambient temperature. In practice this may mean that these components are simply mounted on the same circuit board in close proximity to each other, or preferably they may be thermally bonded to a common ground plane or heatsink.Figure 5. Electronic Reference Junction Compensation Amplifier.(Ref: ”Operational Amplifier Circuits Theory and Applications” E.J Kennedy. HRW Inc.)From Figure 5 the input voltage to the differential amplifier V i , is equal to 121R j j V V V +-, where 1R V is the voltage dropped across R 1. 1R V is itself a function of two components, one from the temperature dependent current source IC1, and the other from the voltage reference, V REF . It is easiest to consider these sources independently, by applying the Principle of Superposition .Figure 6 shows the circuit with the voltage source removed and replaced by its internal impedance, (zero Ohms). In this case v 1 represents the voltage developed across R 1 by the current I 1, thus )()(212112111R R R R I R R I v +==. Note that the component v 1 is in the same direction as V R1.Figure 6. Superposition: I 1 acting aloneFigure 7, on the other hand, shows the circuit with the current source removed and replaced with its internal impedance (an open circuit). Note that the component v 2 now opposes v 1.Figure 7. Superposition: V REF acting aloneFrom potential divider theory )(2112R R R V v REF +=. By summing these components we can write an expression for the compensation voltage, V R1, as follows: )()()()(211212111R R R V R R R R T I V T V REF R c +-+== (3)Since I 1 and V REF are fixed, it is necessary to find values for R1 and R2. From Figure 4 we know that:mV R R R V R R R R I V REF c 277.1)()()25()25(21121211=+-+= mV R R R R R R R A 277.1)(24.1)(15.2982112121=+-+μ …(4) And0)()()0()0(21121211=+-+=R R R V R R R R I V REF c 0)(24.1)(15.2732112121=+-+R R R R R R R A μ (5)By solving (4) and (5) values for R1 and R2 can be found. (You should be able to show that R 1 = 51.66 Ohms and that R 2 = 4540 Ohms). By using a similar process, R 1 and R 2 values can be found for any of the thermocouples listed in Table 1.Finally a word about the isothermal block. Notice that in Figure 5 that the thermocouple terminals also appear on the isothermal block. This is no accident. These terminals are both Constantan alloy, and here they join to the copper conductors if the amplifier circuit. It might be argued that these junctions form a second thermocouple, one that might introduce an unwanted Seebeck voltage into our circuit. This is indeed a valid argument; however no disturbance to our circuit will occur provided the new thermocouple junctions are held at the same temperature . The isothermal block achieves this requirement as well!Linearization AlgorithmsIn some applications thermocouples are used without reference junction compensation or linearization. These applications generally involve sense temperatures many times greater than ambient, and therefore the resulting reference junction temperature error is small. For example, K type thermocouples are frequentlyused to measure cylinder head temperatures on internal combustion engines. These are usually applied in the form of a thermocouple washer placed between the spark plug and the cylinder head. Aircraft exhaust gas temperatures are another such example. Here a thermocouple is placed inside the header pipe not far from the exhaust valve. (The information obtained helps the pilot correctly lean the fuel air mixture in the engine.) In both these cases the thermocouple usually directly drives a temperature indicator, without the need for any additional electronics. In these applications the Seebeck voltage is assumed to be linear with temperature, and while this is not quite true, the resulting error is accepted.In other applications however sufficiently accurate results can only be achieved by providing both reference junction compensation and voltage linearization. The latter can be achieved by the use of a polynomial of the form:44332210E a E a E a E a a T ++++=Where T is the sense temperature, E is the compensated Seebeck voltage, expressed in microvolts , and a 1 – a 4 are empirical constants for the thermocouple concerned. Table 3 includes a list of these for J and K type thermocouples, for the temperature ranges specified. This polynomial will generally be evaluated by the software of the SCADA system to which the thermocouple is interfaced.(Ref: National Institute of Standards and Technology USA. (NIST) and‘Software Linearization of a Thermocouple’ Rex Klopfenstein: King Industries Inc, USA)Table 2. Seebeck Voltages for J Type Thermocouples, (referenced to 0ºC).KNE222电子工程温度测量 - 热电偶塔斯马尼亚大学工程学院摘要当两种不同的金属连接起来，形成一个热电偶。