A sensor is a device that converts the detected quantity into other physical quantities that are easy to handle by using certain laws. For example, a ruler is a very simple sensor. It marks scales at a certain interval, and the scales are a certain law, and then measures the length of the object and the digital distance convenient for application according to this law.

For example, photoresistor is a kind of photoelectric converter, which is made of specific materials, so that its resistance changes proportionally within a certain range under the influence of light. To understand the sensor, you must first determine the application scope of the sensor you want to know, and then learn more. But in the final analysis, the basic principle of the sensor is to use certain laws to convert the measured data into other physical quantities that are easy to handle, and the sensor itself must have certain laws.

2. Principle and characteristics of sensor

Static characteristics-The static characteristics of the sensor refer to the correlation between the static input signal and the sensor output.

Dynamic characteristics-the so-called dynamic characteristics refer to the output characteristics of the sensor when the input changes. In practical work, the dynamic characteristics of a sensor are usually expressed by its response to a specific standard input signal.

Linearity-Under normal circumstances, the actual static characteristic output of the sensor is a curve, not a straight line. In practical work, in order to make the instrument have a uniform scale reading, a straight line is often used to approximate the actual characteristic curve, and linearity (nonlinear error) is the performance index of this approximation.