| 摘要 |
PURPOSE:To always operate an APD stably with an appropriate sensitivity by controlling a bias voltage detecting noises generated when the APD for photoelectric conversion of a reflected pulse laser beam breaks down. CONSTITUTION:Noises which are generated when a APD1 for photoelectric conversion of a reflected pulse laser beam to measure distance breaks down are detected with an FF12 and the output of the FF12 is inverted. With the inversion of the output, the opening of switches 13 and 14 is controlled through a switch driving circuit 15. The charging of biasing charge capacitors 8 and 9 is stopped with a switch 13 while the supply voltage to the APD varies through the switch 13 so that the bias voltage is reset at the value immediately before the break down. This always enables a stable use of the APD with an appropriate sensitivity to ensure a better measurement of distance. |
