| 摘要 |
PURPOSE:To obtain a large S/N and to attain high-speed operation by providing a signal switch connected in series with a photodetector to a drive section of a picture read sensor and a dummy switch in pairs therewith and applying differential operation to both outputs. CONSTITUTION:When the 1st pulse of a shift clock enters a shift register 4, a pulse turning on a signal switch 2 and a dummy switch 3 is outputted from the shift register 4. Since the output pulse of the signal switch 2 is generated in a signal common line 5 and an output pulse from the dummy switch 3 is generated in a dummy common line 6 at the same time, both pulses are processed differentially by using a differential amplifier 7, then the switching noise of rejection mode is cancelled and an optical signal pulse is obtained at an output terminal 8.
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