| 摘要 |
In an auto focus type camera employing an intermittent infrared-ray light to an object to be photographed and which uses the reflected intermittent light from the object as a focusing signal, a signal detecting device is employed. The signal detecting device detects the signal from a signal source oscillating with a certain determined frequency and includes a detecting circuit, a driving power source for the detecting circuit and a signal producing circuit. The signal producing circuit produces a quasi-signal equivalent to a fluctuation signal from the detecting source which depends upon the fluctuation of the driving power source for the detecting circuit. The fluctuation signal from the detecting source is thus compensated by the quasi-signal from the signal producing circuit. Thus the effect of the fluctuation of the power source is substantially eliminated.
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