温度传感器资料(一).doc

题目：温度传感器的发展现状，论述检测的重要性目录：1. 温度传感器及特性介绍2. 温度传感器的发展趋势3. 温度检测技术及相关仪器的发展现状4. 检测的重要性以及与温度传感器的关联5. 参考资料网址温度传感器及特性介绍Temperature sensors are used to measure temperature in circuits which control a wide variety of equipment. Various processes require temperature monitoring for effective control. Such processes include manufacturing processes, transportation, security, maintenance, and other types of processes during which monitoring the thermal characteristics of devices is necessary or advisable. Temperature sensors are widely used in many fields, such as household electrical appliances and medical appliances. They are also used in mobile communication equipment, for example, cellular phones. Many different types of temperature sensors are commercially available. Temperature sensors having temperature-dependent properties which can be measured electrically include resistors, semiconductor devices such as diodes, and thermocouples. A resistance thermometer has a sensing resistor having an electrical resistance varying with temperature. The temperature sensor is driven by a constant current source in order to develop voltages across the changing resistance of the sensing resistor. The thermistor is a temperature sensitive resistor and is generally composed of semi-conductor materials. The integrated circuit temperature sensor has also been used to measure temperatures. The integrated circuit sensor typically employs an integrated diode whose output characteristics are dependent upon temperature. Temperature sensing in high temperature environments such as automotive vehicle exhaust systems, is typically done using thermistors constructed of materials capable of withstanding the high temperature environment.A thermistor is an electronic device which utilizes the change of resistance when the temperature changes, and is widely used as a temperature sensor and a compensator for an electronic circuit. Thermistors are ceramic semiconductors which exhibit large changes in electrical resistance with corresponding changes in temperature. Thermistors have an extremely high temperature coefficient of resistance and precise resistance versus temperature characteristics. Because of their sensitivity, accuracy, and stability, thermistors are generally accepted to be the most advantageous sensor for many applications including temperature measurement, compensation, and control. Thermistors having positive temperature coefficients (PTC thermistors) as well as thermistors having negative temperature coefficients (NTC thermistors) are used. The NTC thermistor has a negative temperature coefficient and whose resistivity decreases with increasing temperature, and is applied in the form of a temperature sensor to temperature compensation elements, etc. NTC thermistors are widely being used for the purposes of temperature detection and temperature compensation. NTC thermistors used for temperature measurement and compensation are usually made from various compositions including the oxides of manganese, nickel, cobalt, copper, iron, and other metals to form a ceramic semiconductor material. The PTC thermistor has a positive temperature coefficient and whose resistivity increases sharply at a certain specific temperature. A PTC chip thermistor may be incorporated into the circuit of an electronic device so as to generate heat when an overcurrent with intensity greater than a specified level flows therethrough, thereby increasing its resistance due to its positive resistance-temperature characteristic and keeping the intensity of the current flowing into the electronic device below a certain level. The PTC thermistor is widely applied to temperature control elements, overcurrent control elements, motor-starting elements, constant-temperature heat generators, etc.Thermistor TerminologyNegative Temperature Coefficient (NTC)An NTC thermistor is one in which the zero-power resistance decreases with an increase inbody temperature.Zero-Power Resistance (RT)The zero-power resistance is the DC resistance value of a thermistor measured at a specifiedtemperature with power dissipated by the thermistor low enough that any further decrease inpower will result in not more than 0.1 % (or one-tenth of the specified measurement tolerance, whichever is smaller) change in resistance.Rated zero power resistance (R25)The zero power resistance is measured under the standard temperature of25C.B value (unit:K)B value is a constant describing the physical characteristic of the NTC thermistor material, alsocalled thermistor coefficient.That is: = ln(R1/R2)/(1/T1-1/T2)R1-Resistance at Temperature T1R2-Resistance at Temperature T2B value is usually determined by zero-power resistance at25C/85Cin American market and25C/50CinAsiamarket.Maximum Operating TemperatureThe maximum operating temperature of a thermistor is the maximum body temperature atwhich the thermistor will operate for an extended period of time with acceptable stability ofits characteristics. This temperature can be the result of internal or external heating, or both,and should not exceed the maximum value specified.Maximum Power RatingThe maximum power rating of a thermistor is the maximum power which a thermistor willdissipate for an extended period of time with acceptable stability of its characteristics.Dissipation ConstantThe dissipation constant is the ratio, (expressed in milliwatts per degree C) at a specifiedambient temperature, of a change in power dissipation in a thermistor to the resultant bodytemperature change.Thermal Time ConstantThe thermal time constant is the time required for a thermistor to change 63.2 % of the totaldifference between its initial and final body temperature when subjected to a step functionchange in temperature under zero-power conditions.Zero-Power Temperature Coefficient Of Resistance (alpha )Zero-power temperature coefficient of resistance is the slope of the R-T curve at any given temperature is used to express the point. It is a measure of the rate of change in resistance of the thermistor at a specific temperature. Alpha is expressed in -%/C. As the R-T curve is not linear, alpha is greater at lower temperatures than at higher temperatures.Alpha is useful for determining what tolerances are required for an application. For example,the alpha value at25Cfor a particular NTC was 4.0%/C, if the application requires a temperature accuracy 0.5C, then the NTC zero-power resistance at25Ctolerance would need to specified as 2.0%. (4.0%*0.5)Tolerance on ResistanceThis is a method of measuring precision in NTC thermistors. Tolerance is the percentage of variation in resistance at a specific temperature. Tolerance is always stated as a percentage at a specified temperature. The industry standard is to use25Cas the base temperature, unless another temperature is specified.Themaximum operating temperatureis the maximum body temperature at which the thermistor will operate for an extended period of time with acceptable stability of its characteristics. This temperature is the result of internal or external heating, or both, and should not exceed the maximum value specified.Themaximum power ratingof a thermistor is the maximum power which a thermistor will dissipate for an extended period of time with acceptable stability of its characteristics.Thetemperature-wattagecharacteristicof a thermistor is the relationship at a specified ambient temperature between the thermistor temperature and the applied steady state wattage.Thecurrent-time characteristicof a thermistor is the relationship at a specified ambient temperature between the current through a thermistor and time, upon application or interruption of voltage to it.Thestabilityof a thermistor is the ability of a thermistor to retain specified characteristics after being subjected to designated environmental or electrical test conditions./proknowledgeinfo-19-en.htmlTemperature is a fundamental physical quantity and nature of all processes are all closely related to temperature.The temperaturesensoris the earliest development, the most widely used type of sensor.Temperature sensor market share much higher than the othersensors.From the early 17th century, people began to use temperature measurements.Semiconductor technology support, this century have developed a semiconductor thermocouple sensor, PN junction temperaturesensorand integrated temperature sensor.Correspondingly, according to the law of wave interaction with matter, have developed acoustic temperaturesensors, infrared sensors and microwave sensors.The conductors of the two different materials, such as connected to each other at a certain point, heating of this connection point, a potential difference occurs when they are not of the heated portion.The value of this potential difference is related to the temperature of the heated parts of the measuring point, and the materials of the two conductors.This phenomenon can appear within a very wide range of temperatures, if the accurate measurement of this potential difference, and then measure the temperature of the non-heated parts of the environment, it can accurately know the temperature of the heat spots.Because it must have two conductors of different materials, so called “thermocouple.Thermocouple made of different materials used in the different temperature ranges, their sensitivity also varies.The thermocouple sensitivity refers plus hot temperature changes 1 C, the output potential difference between the amount of change.For most metal material support thermocouple, this value is between about 5 to 40 micro-volts / C.Thermocouplesensorhas its own advantages and shortcomings, it is relatively low sensitivity susceptible to environmental interference signal, also susceptible to temperature drift of the preamplifier, and therefore not suitable for measuring small temperature changes.Contents due to the sensitivity of the thermocouple temperaturesensor, and the thickness of the material, a very thin material can also be made of the temperature sensor.Also due to the production thermocouple metal material has a good ductility, this subtle temperature measurement element has a very high response speed of the rapid changes in the process, can be measured.The temperaturesensoris most commonly a variety of sensor, the modern temperature sensor shape very small, so the more it widely used in various fields of production practices, our lives provide numerous convenience and functionality .The four main types: thermocouples, thermistors, resistance temperature detector (RTD) and IC temperature sensor temperature sensor.IC temperaturesensors, including two types of analog output and digital output.The detection portion of the contact type temperaturesensorhas a good contact with the measured object, also known as a thermometer.Thermometer to reach thermal equilibrium by conduction or convection, so that the thermometer showing the value of the temperature of the object under test can be expressed directly.Generally higher measurement accuracy.Within a certain temperature range, a thermometer, temperature distribution inside the object can be measured.But for the movement of the body, the small goals or the heat capacity of a small object will have a greater measurement error common thermometer bimetal thermometers, glass liquid thermometer, pressure thermometer, resistance thermometer, thermistor and thermocouple, etc.They are widely used in industrial, agricultural, commercial, and other departments.In daily life, people often use these thermometers.With the cryogenic technology in a wide range of applications and defense engineering, space technology, metallurgy, electronics, food, pharmaceutical and petrochemical sector superconducting technology, low-temperature thermometer for measuring temperatures below 120K has been developed, such as low-temperature gas thermometer, steam pressure thermometer, acoustic thermometer paramagnetic salt thermometer quantum thermometer, the low-temperature heat resistance and low-temperature thermoelectric even.Low-temperature thermometer requirements for temperature sensing element, small size, high accuracy, reproducibility and stability.Using a porous high silica glass carburizing sintering carburizing glass thermal resistance of a temperature sensing element is low temperature thermometer, can be used for measuring the temperature within the range of 1.6 300K.The non-contact temperaturesensorsensitive components measured object no contact with each other, also known as non-contact thermometer table.This instrument is used to measure moving objects, and small targets, and a small thermal capacity or rapid temperature changes (transient) objects the surface temperature can also be used to measure the temperature field of the temperature distribution.The most common non-contact thermometer table is based on the basic law of black-body radiation, called radiation thermometer table.Radiation thermometry (see optical pyrometer), including brightness radiation method (see radiation pyrometer) and colorimetry (see colorimetric thermometer).The various types of radiation thermometry method can only measure the corresponding brightness temperature, radiation temperature or color temperature.Only the right the blackbody (absorbs all radiation is not reflected light of the object) of the measured temperature is the true temperature.For determination of the true temperature of an object, the material surface emissivity correction.Material surface emissivity not only depends on the temperature and wavelength, but also with the surface state of the coating film, and the microstructure, and therefore difficult to precisely measure.In automated production often requires the use of radiation pyrometry measurement or control the temperature of the surface of certain objects, such as the rolling temperature of the strip, the roll temperature in the metallurgical industry, forging temperature and the temperature of the molten metal in the smelting furnace or crucible .In these specific cases, the surface emissivity measurement is very difficult.Additional mirror can be used for automatic measurement and control of the temperature of the solid surface, blackbody cavity together with the measured surface composition.Additional effects of radiation can increase the effective radiation of the surface to be measured and effective emission coefficient.Effective emission coefficient corresponding correction of the measured temperature by instrument, and ultimately the real temperature of the measured surface can be obtained.The most typical example of the additional reflector is a hemispherical mirror.Diffusing radiant energy of the surface to be measured in the vicinity of the center of the ball by the hemispheric mirror is reflected back to the surface formed by the additional radiation, thereby to increase the effective emission coefficient: where is the emissivity of the material surface, is the reflectance of the mirror.As for the gas and the liquid medium the radiation measurement of the true temperature, can be inserted into the heat-resistant material to the tube to a certain depth in order to form a blackbody cavity.Obtained by calculation with the medium reaches thermal equilibrium after the effective emission coefficient of the cylindrical cavity.This value can be used in the automatic measurement and control on the amendments to the temperature of the measuring chamber bottom (medium temperature) and the true temperature of the medium.Non-contact temperature measurement advantages: Measure the ceiling is not temperature sensing element temperature restrictions, and thus the maximum measured temperature in principle there is no limit.For temperatures above 1800 , non-contact temperature measurement method.With the development of infrared technology, radiation thermometry gradually from the visible to the infrared extension to 700 C or below until room temperature has been adopted, and high resolution./2012/10/17/introduction-to-the-temperature-sensor/温度传感器的发展趋势现代信息技术的三大基础是信息采集(即传感器技术)、信息传输(通信技术)和信息处理(计算机技术)。传感器属于信息技术的前沿尖端产品，尤其是温度传感器被广泛用于工农业生产、科学研究和生活等领域，数量高居各种传感器之首。近百年来，温度传感器的发展大致经历了以下三个阶段；(1)传统的分立式温度传感器(含敏感元件)；(2)模拟集成温度传感器控制器；(3)智能温度传感器。目前，国际上新型温度传感器正从模拟式向数字式、由集成化向智能化、网络化的方向发展1 集成温度传感器的产品分类1.1模拟集成温度传感器集成传感器是采用硅半导体集成工艺而制成的，因此亦称硅传感器或单片集成温度传感器。模拟集成温度传感器是在20世纪80年代问世的，它是将温度传感器集成在一个芯片上、可完成温度测量及模拟信号输出功能的专用IC。模拟集成温度传感器的主要特点是功能单一(仅测量温度)、测温误差小、价格低、响应速度快、传输距离远、体积小、微功耗等，适合远距离测温、控温，不需要进行非线性校准，外围电路简单。它是目前在国内外应用最为普遍的一种集成传感器，典型产品有AD590、AD592、TMP17、LM135等。1.2模拟集成温度控制器模拟集成温度控制器主要包括温控开关、可编程温度控制器，典型产品有LM56、AD22105和MAX6509。某些增强型集成温度控制器(例如TC652/653)中还包含了A/D转换器以及固化好的程序，这与智能温度传感器有某些相似之处。但它自成系统，工作时并不受微处理器的控制，这是二者的主要区别。1.3智能温度传感器智能温度传感器(亦称数字温度传感器)是在20世纪90年代中期问世的。它是微电子技术、计算机技术和自动测试技术(ATE)的结晶。目前，国际上已开发出多种智能温度传感器系列产品。智能温度传感器内部都包含温度传感器、A/D转换器、信号处理器、存储器(或寄存器)和接口电路。有的产品还带多路选择器、中央控制器(cpu)、随机存取存储器(RAM)和只读存储器(ROM)。智能温度传感器的特点是能输出温度数据及相关的温度控制量，适配各种微控制器(MCU)；并且它是在硬件的基础上通过软件来实现测试功能的，其智能化程度也取决于软件的开发水平。2智能温度传感器发展的新趋势进入21世纪后，智能温度传感器正朝着高精度、多功能、总线标准化、高可靠性及安全性、开发虚拟传感器和网络传感器、研制单片测温系统等高科技的方向迅速发展。2.1提高测温精度和分辨力在20世纪90年代中期最早推出的智能温度传感器，采用的是8位A/D转换器，其测温精度较低，分辨力只能达到1。目前，国外已相继推出多种高精度、高分辨力的智能温度传感器，所用的是912位A/D转换器，分辨力一般可达0.50.0625。由美国DALLAS半导体公司新研制的DS1624型高分辨力智能温度传感器，能输出13位二进制数据，其分辨力高达0.03125，测温精度为0.2。为了提高多通道智能温度传感器的转换速率，也有的芯片采用高速逐次逼近式A/D转换器。以AD7817型5通道智能温度传感器为例，它对本地传感器、每一路远程传感器的转换时间分别仅为27s、9s。2.2增加测试功能新型智能温度传感器的测试功能也在不断增强。例如，DS1629型单线智能温度传感器增加了实时日历时钟（RTC），使其功能更加完善。DS1624还增加了存储功能，利用芯片内部256字节的E2PROM存储器，可存储用户的短信息。另外，智能温度传感器正从单通道向多通道的方向