Optical Sensors
Shaft position can be sensed using optical or pulsating lighting techniques. One such applications is the crank angle sensor. The crank angle sensor has a rotor plate and a wave formating circuit. The rotor plate has 360 slits for a 1 signal and 4 slits for 180 signal. light emitting diodes (LEDs) and photo diodes are built in the wave formating circuit.
When the rotor plate passes the space between the LED and the photodiode, the slits of the rotor plate continually cut the light sent to the photodiode from the LED. This couses rought shaped pulses to be generated. The are then converted into ON-OFF pulses by the wave formating circuit and these are sent to microcomputer. The pulses are counted by digital countes whitin the microcomputer to determine engine speed and crankshaft position.
