| 摘要 |
PURPOSE:To improve noise resistance without increasing the amount of power supply to a light emitting element, by allowing the amount of light emission of a photodetector constituting a rotary encoder to respond to a pulse output of a comparison circuit. CONSTITUTION:To a rotary disc P having a light/dark pattern, a light emitting element D1 and a photodetector T1 are arranged. An output of the photodetector T1 is applied to a comparison circuit C1. Voltage division resistors R7, R8 are connected between an output 2 of the circuit C1 and a power supply terminal 1, and one electrode of the element D1 is connected to the connecting point between the resistors R7 and R8. Since the D1 responds to an output pulse of the C1, a detection voltage output generated in a load resistor R5 of the T1 has a difference of level. Thus, without increasing the power supply amount i2 of the D1, the pulse output of the C1 is steep and the noise resistance characteristics can be improved. |
