| 摘要 |
PURPOSE:To prevent automatically a target from deterioration and damage due to excessive input by making a chopper, which is located in front of the target, to be in the closed state, if excessive incoming light is made incident. CONSTITUTION:The output of a pyroelectric-type image pickup tube 1 is supplied to a TV monitor 11 via a video amplifier 2 and an adding circuit 10. The output of the amplifier 2 is given to a timer circuit 6 and an image-pickup-mode switching circuit 13 via a band-pass filter 3, a gate circuit 4 and a waveform shaping circuit 5. If excessive incoming light is made incident, the circuit 13 makes a chopper 15 to be in closed state, and an alarming buzzer 7 is actuated by the output of the circuit 6. |
