1. photoelectric switch working principle. Photoelectric switch is the use of detected objects on the light beam blocking or reflection, by the synchronous circuit selection circuit, so as to detect the presence or absence of blocking objects. All objects that can reflect light can be detected. The photoelectric switch converts the input current at the transmitter into an optical signal and shoots it out, and then the receiver detects the target object based on the strength or presence of the received light. Most photoelectric switches use infrared light waves with wavelengths close to visible light.
2.Photoelectric switch features
(1) Long testing distance. Compared with inductive proximity switch, photoelectric switch can obtain longer testing distance.
(2) Not affected by magnetic field and vibration. Test switches are more often installed in places with strong magnetic fields and vibration, but photoelectric switches are rarely affected by them and can be used reliably.
(3)High resolution ability. Light is propagated in a straight line, and the wavelength is short, so the resolution is high, which is suitable for tiny objects and high-precision position testing.
(4) Wide range of test objects. Whether it is metal, glass, rubber, wood, liquid, gas, etc. almost all can be tested.
(5) Easy to obtain a regular test area. Optical switch adopts optical system such as lens, easy to gather light, diffusion and refraction, according to different test objects and use environment, it is able to properly select products with a certain test area.
(6) Fast response time. The optical switch contains almost no mechanical action, so it can obtain a high testing speed.
(7) Can use the characteristics of light for testing, able to do the color scale, shape features of the selection test, etc.
3. Photoelectric switch models. (1)Photoelectric switch can be divided into three types according to the structure model: amplifier separated type, amplifier built-in type and power built-in type. (2) Photoelectric switch according to the different detection methods, can be divided into diffuse type, opposite type, mirror reflection type, slot type and fiber optic type.
4. Precautions for the use of photoelectric switches.
(1)The infrared sensor belongs to diffuse reflection type products, and the standard detection body used is flat white drawing paper.
(2) infrared photoelectric switch in the case of high ambient illumination can work stably, but in principle should still try to avoid the sensor optical axis is facing the sunlight and other strong light sources.
(3) The minimum detectable width of the opposite photoelectric switch is 80% of the width of the lens of this kind of photoelectric switch.
(4) When using inductive load, its transient inrush current will be relatively large, so it may damage the AC two-wire photoelectric switch, encounter this situation, the load should be converted to use through the AC relay.
(5) The lens of infrared photoelectric switch can be wiped with mirror wiping paper, but it is strictly forbidden to use chemicals such as dilution solvents to avoid permanent damage to the plastic mirror.
(6) When using and replacing the photoelectric switch, it is necessary to confirm the voltage level and make sure the wiring is correct to avoid accidents.
(7) The place of use of photoelectric switch should try to avoid the place with more dust, more corrosive gas, excessive change of ambient temperature, large vibration impact and without taking shock absorption measures.