2. Principle: The transmitter generates coded infrared beams, and the receiver receives the corresponding beams; A rectangular protection area is generated between the optical transmitter and the optical receiver. When an opaque object enters this area, the corresponding light beam is blocked, and the light emitter or light receiver generates a shading signal and outputs it to the controller (or directly outputs PNP or NPN transistor signals); The controller finally converts the shading signal into the relay output signal.
3. Major domestic manufacturers: Intech, Keli, SFT, etc.