Temperature sensor that classified by measurement method

Conceptually, a temperature sensor is a sensor that senses temperature and converts it into a usable output signal. According to the measurement method can be divided into contact and non-contact two categories.
1.Contact Temperature Sensor
The detection part of the contact temperature sensor has good contact with the measured object, also known as the thermometer. Thermometers achieve thermal equilibrium by conduction or convection, so that the value of the thermometer can directly represent the temperature of the object being measured.
The general measurement accuracy is high. Within a certain temperature range, a thermometer can also measure the temperature distribution inside an object. But for the moving body, small target or the object with very small heat capacity will produce large measurement error, commonly used thermometers are bimetal thermometers, glass liquid thermometers, pressure thermometers, resistance thermometers, thermistors and thermocouples. They are widely used in industry, agriculture, commerce and other sectors. People also use these thermometers in their daily life.
2.Non-contact Temperature sensor
Its sensitive element does not contact with the measured object, also known as non-contact thermometer table. The instrument can be used to measure the surface temperature of moving objects, small targets and objects with small heat capacity or rapid temperature change (transient), and also to measure the temperature distribution of temperature fields. The most commonly used non-contact thermometer is based on the basic law of blackbody radiation and is called a radiation thermometer. All kinds of radiation temperature measurement methods can only measure the corresponding luminosity temperature, radiation temperature or colorimetric temperature. Only the temperature measured for a black body (an object that absorbs all radiation and does not reflect light) is the true temperature. If the true temperature of the object is to be determined, the surface emissivity of the material must be corrected. The surface emissivity of materials depends not only on temperature and wavelength, but also on the surface state, coating film and microstructure, so it is difficult to accurately measure.
The advantage of non-contact temperature sensor is that the upper limit of measurement is not limited by the temperature resistance degree of the temperature sensing element, so there is no limit to the maximum measurable temperature in principle.


Post time: Apr-22-2022