With the development of the times, the principle of thread breakage sensor of sewing machine is as follows:

　　The detection principle refers to the physical effect, chemical effect and biological effect of the sensor. There are resistance type, capacitance type, inductance type, piezoelectric type, electromagnetic type, magnetoresistance type, photoelectric type, piezoresistive type, thermoelectric type, nuclear radiation type, semiconductor type sensor, etc.

　　For example, according to the principle of variable resistance, there are potentiometer type, strain gauge, piezoresistive sensor, etc; For example, according to the principle of electromagnetic induction, there are inductance type, differential pressure transmitter, eddy current type, electromagnetic type, magnetoresistance type and other sensors; According to the theory of semiconductor, the corresponding solid-state sensors are semiconductor force sensor, thermal sensor, photosensitive sensor, gas sensor and magnetic sensor.

　　The advantage of this classification method is that it is convenient for sensor professionals to make inductive analysis and research from the principle and design, and avoid too many names of sensors, so it is often used. The disadvantage is that it is not convenient for users to select sensors.

　　Sometimes, the use and principle are combined to name, such as inductive displacement sensor, piezoelectric force sensor and so on