温度传感器资料(一)

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Temperaturesensorsareusedtomeasuretemperatureincircuitswhichcontrolawidevarietyofequipment.Variousprocessesrequiretemperaturemonitoringforeffectivecontrol.Suchprocessesincludemanufacturingprocesses,transportation,security,maintenance,andothertypesofprocessesduringwhichmonitoringthethermalcharacteristicsofdevicesisnecessaryoradvisable.Temperaturesensorsarewidelyusedinmanyfields,suchashouseholdelectricalappliancesandmedicalappliances.Theyarealsousedinmobilecommunicationequipment,forexample,cellularphones.Manydifferenttypesoftemperaturesensorsarecommerciallyavailable.Temperaturesensorshavingtemperature-dependentpropertieswhichcanbemeasuredelectricallyincluderesistors,semiconductordevicessuchasdiodes,andthermocouples.Aresistancethermometerhasasensingresistorhavinganelectricalresistancevaryingwithtemperature.Thetemperaturesensorisdrivenbyaconstantcurrentsourceinordertodevelopvoltagesacrossthechangingresistanceofthesensingresistor.Thethermistorisatemperaturesensitiveresistorandisgenerallycomposedofsemi-conductormaterials.Theintegratedcircuittemperaturesensorhasalsobeenusedtomeasuretemperatures.Theintegratedcircuitsensortypicallyemploysanintegrateddiodewhoseoutputcharacteristicsaredependentupontemperature.Temperaturesensinginhightemperatureenvironmentssuchasautomotivevehicleexhaustsystems,istypicallydoneusingthermistorsconstructedofmaterialscapableofwithstandingthehightemperatureenvironment.Athermistorisanelectronicdevicewhichutilizesthechangeofresistancewhenthetemperaturechanges,andiswidelyusedasatemperaturesensorandacompensatorforanelectroniccircuit.Thermistorsareceramicsemiconductorswhichexhibitlargechangesinelectricalresistancewithcorrespondingchangesintemperature.Thermistorshaveanextremelyhightemperaturecoefficientofresistanceandpreciseresistanceversustemperaturecharacteristics.Becauseoftheirsensitivity,accuracy,andstability,thermistorsaregenerallyacceptedtobethemostadvantageoussensorformanyapplicationsincludingtemperaturemeasurement,compensation,andcontrol.Thermistorshavingpositivetemperaturecoefficients(PTCthermistors)aswellasthermistorshavingnegativetemperaturecoefficients(NTCthermistors)areused.TheNTCthermistorhasanegativetemperaturecoefficientandwhoseresistivitydecreaseswithincreasingtemperature,andisappliedintheformofatemperaturesensortotemperaturecompensationelements,etc.NTCthermistorsarewidelybeingusedforthepurposesoftemperaturedetectionandtemperaturecompensation.NTCthermistorsusedfortemperaturemeasurementandcompensationareusuallymadefromvariouscompositionsincludingtheoxidesofmanganese,nickel,cobalt,copper,iron,andothermetalstoformaceramicsemiconductormaterial.ThePTCthermistorhasapositivetemperaturecoefficientandwhoseresistivityincreasessharplyatacertainspecifictemperature.APTCchipthermistormaybeincorporatedintothecircuitofanelectronicdevicesoastogenerateheatwhenanovercurrentwithintensitygreaterthanaspecifiedlevelflowstherethrough,therebyincreasingitsresistanceduetoitspositiveresistance-temperaturecharacteristicandkeepingtheintensityofthecurrentflowingintotheelectronicdevicebelowacertainlevel.ThePTCthermistoriswidelyappliedtotemperaturecontrolelements,overcurrentcontrolelements,motor-startingelements,constant-temperatureheatgenerators,etc.ThermistorTerminologyNegativeTemperatureCoefficient(NTC)AnNTCthermistorisoneinwhichthezero-powerresistancedecreaseswithanincreaseinbodytemperature.Zero-PowerResistance(RT)Thezero-powerresistanceistheDCresistancevalueofathermistormeasuredataspecifiedtemperaturewithpowerdissipatedbythethermistorlowenoughthatanyfurtherdecreaseinpowerwillresultinnotmorethan0.1%(orone-tenthofthespecifiedmeasurementtolerance,whicheverissmaller)changeinresistance.Ratedzeropowerresistance(R25)Thezeropowerresistanceismeasuredunderthestandardtemperatureof25°C.Bvalue(unit:K)BvalueisaconstantdescribingthephysicalcharacteristicoftheNTCthermistormaterial,alsocalledthermistorcoefficient.Thatis:β=ln(R1/R2)/(1/T1-1/T2)R1-ResistanceatTemperatureT1R2-ResistanceatTemperatureT2Bvalueisusuallydeterminedbyzero-powerresistanceat25°C/85°CinAmericanmarketand25°C/50°CinAsiamarket.MaximumOperatingTemperatureThemaximumoperatingtemperatureofathermistoristhemaximumbodytemperatureatwhichthethermistorwilloperateforanextendedperiodoftimewithacceptablestabilityofitscharacteristics.Thistemperaturecanbetheresultofinternalorexternalheating,orboth,andshouldnotexceedthemaximumvaluespecified.MaximumPowerRatingThemaximumpowerratingofathermistoristhemaximumpowerwhichathermistorwilldissipateforanextendedperiodoftimewithacceptablestabilityofitscharacteristics.DissipationConstantThedissipationconstantistheratio,(expressedinmilliwattsperdegreeC)ataspecifiedambienttemperature,ofachangeinpowerdissipationinathermistortotheresultantbodytemperaturechange.ThermalTimeConstantThethermaltimeconstantisthetimerequiredforathermistortochange63.2%ofthetotaldifferencebetweenitsinitialandfinalbodytemperaturewhensubjectedtoastepfunctionchangein