Introduction of sensors commonly used in automation equipment

　　The following is a brief introduction of the sensors commonly used in industrial automation equipment.

　　1. Magnetic switch: It is a special name for the sensor for the cylinder, which is mainly used to detect the position of the cylinder piston. Usually, they are provided by the cylinder supplier according to the customer's usage. As the name suggests, the magnetic switch detects the target through electromagnetic induction, so its detection accuracy is quite low.

　　2. Proximity switch: The proximity switch is also designed and manufactured based on the principle of electromagnetic induction, so it can only measure metal targets, and the sensing distance of different metals is slightly different. At present, the commonly used detection distances of proximity switches are as follows: 1mm, 2mm, 4mm, 8mm, 12mm and so on. There are usually two types of proximity switches: embedded and non-embedded. The so-called buried type means that the sensor head of the proximity switch does not detect the metal target in the circumferential direction, but only detects the metal target in front of it, that is, the sensor head can not expose the metal mounting bracket; the so-called non-buried type refers to the proximity switch induction head. It detects not only the metal target in front of it, but also the metal target in the circumferential direction, that is, the sensor head must be exposed to the metal mounting bracket for a certain distance, and there must be no metal target within a certain range in the circumferential direction to avoid misjudgment. The detection accuracy of proximity switches is higher than that of magnetic switches. Proximity switches are usually used to judge the presence or absence of products and whether the fixtures are in place, etc., where the requirements for positional accuracy are relatively low.

　　3. Photoelectric switch: The photoelectric detection method has the advantages of high precision, fast response, non-contact, etc., and can measure many parameters. The structure of the sensor is simple, and the form is flexible and diverse. Therefore, the photoelectric sensor is widely used in detection and control. There are roughly three types of photoelectric switches that we usually call: one is a reflective photoelectric sensor, one is a through-beam photoelectric sensor, and the other is a photoelectric sensor that uses a reflective plate to reflect light. The latter two are detected by shading the target, and the former is detected by reflecting light from the target. Therefore, the latter two detection distances are usually farther and the accuracy is higher. Due to the high detection accuracy of photoelectric sensors, they are usually used to detect the precise position of workpieces such as products or robots, as well as feedback devices for stepping and servo systems.

　　4. Optical fiber sensor: Optical fiber sensor is also a detection element that applies photoelectric signal conversion. Compared with photoelectric switch, it can usually detect smaller targets, longer detection distance and higher accuracy. Therefore, optical fiber sensors are usually used in more accurate detection occasions and positioning feedback devices of stepping and servo systems.

　　5. Grating: Grating is also a sensor that utilizes photoelectric signals. The detection area of the grating is large, so it is usually called an area sensor. The main application area of grating is usually the interlocking and safety function between devices, especially for the protection of people.

　　6. Displacement sensor: As the name suggests, it is a sensor that detects changes in the position of the target.

　　7. Pressure sensor: The pressure sensor is used to detect the tension or pressure exerted or endured by the target.

　　8. Thermocouple: Thermocouple is mainly used to detect the ambient temperature around it.

　　9. Laser detector: The main function of the laser detector is to accurately measure the external dimensions of the target.

　　10. Industrial camera: Industrial camera is also commonly called CCD (Charge-coupled Device) in engineering, which is mainly used to detect the shape and position of the target. With the improvement of the current CCD technology, high-resolution industrial cameras can already be used in the field of precise measurement.

　　11. Encoder: According to the working principle, the encoder can be divided into two types: incremental type and absolute type. The incremental encoder converts the displacement into a periodic electrical signal, and then converts the electrical signal into a count pulse, and the number of pulses represents the magnitude of the displacement. Each position of the absolute encoder should have a definite digital code, so its indication is only related to the starting and ending positions of the measurement, and has nothing to do with the intermediate process of the measurement. The encoder is usually used with stepper motor or servo motor to form a closed-loop or semi-closed-loop control system.

　　12. Micro switch: Micro switch is a kind of contact sensor, which is currently mainly used in the connection between devices or the detection of the state of the safety protection door of the device.