| 摘要 |
<p>PURPOSE:To automatically adjust the radiation intensity of a light emitting element and the output voltage level of a light receiving element by inputting the photoelectric current detection signal to a luminous current adjusting circuit via a feedback circuit. CONSTITUTION:When light is fed to a light receiving element 1, a photoelectric current flows in a photoelectric current detecting resistor 2 to generate the detection voltage Va, and it is inputted to a feedback circuit 3. The circuit 3 is connected with a diode 6 to a capacitor 7 and a resistor 8 to hold the voltage Va. The held voltage Va is inputted to a luminous current adjusting circuit 4 to drive a MOS-FET 9, and the current flowing in a light emitting element 5 is changed to adjust the light emitting intensity. The output voltage Vout of the element 1 is automatically adjusted gradually. The cost and time for adjustment can be reduced, even if dust is stuck to a sensor to reduce the voltage level, the reduction of the voltage level can be prevented by automatically following it.</p> |
