| 摘要 |
PURPOSE:To eliminate erroneous distance measurement by limiting the output of the output stage of a photodetecting circuit, which responds to even a DC input component to some extent, before the output stage enters into a saturated state against an excessive DC input component. CONSTITUTION:Two stages of diodes D1 and D2 connected in series are provided to the output stage of an emitter follower transistor (TR) Q1 to perform limiter operation at a voltage much higher than the reference voltage of a circuit output V0, i.e. the circuit output V0 with normal brightness. When a camera is directed to an excessive brightness subject, a limiter operates before the circuit output V0 is saturated, and variation in power voltage VCC never appears in the circuit output V0 through the TRQ1. |
