Photo interruption Module is used in the electronic circuits of automatic packing and sealing machinery using conveyor belts. The conveyor belt having equally spaced holes passes through the slit of the module.When the hole in the belt reaches the interruption module, the circuit will be activated / de activated. Here describes the working of the Photo interruption module.
The photo interruption module has an Infrared LED and a Phototransistor or photo diode in a sealed package. There are openings for the exit of IR rays from the IR LED and entry of IR rays into the Phototransistor. The slit is between the openings through which the belt passes.
Normally when the IR ray is interrupted by the belt, the Phototransistor in the module will be off. So T1 gets base bias and it conducts. Green LED lights to indicate the interruption. When the hole in the belt is in the slit, IR rays hit on the Phototransistor and it conducts. This pulls the base of T1 to ground potential and it turns off. T2 then gets base bias and conducts and Red LED lights.