Working principle of photoelectric camshaft position sensor

The signal plate is installed between the light emitting diode (LED) and the phototransistor (or photodiode). When the light-transmitting hole on the signal plate rotates between the LED and the phototransistor, the light emitted by the LED will illuminate the phototransistor. At this time, the phototransistor is turned on, and its collector outputs a low level (0.1～O .3V); When the light-shielding part on the signal plate rotates between the LED and the phototransistor, the light emitted by the LED cannot illuminate the phototransistor. At this time, the phototransistor is cut off, and its collector outputs a high level (4.8 ~5.2V).
If the signal plate rotates continuously, the light-transmitting hole and the light-shielding part will alternately pass through the LED to transmit or shield light, and the collector of the phototransistor will alternately output high and low levels. When the sensor shaft rotates with the crankshaft and the valve camshaft, the light-transmitting hole and shading part on the signal plate will turn between the LED and the phototransistor, and the light emitted by the LED will be illuminated alternately by the light-transmitting and shading effect of the signal plate. On the phototransistor of the signal generator, the signal sensor will generate pulse signals corresponding to the crankshaft position and camshaft position sensors.