| 摘要 |
PURPOSE:To abandon an A/D converter circuit dedicated to each separating color light and to allow the same A/D converter circuit to cope with a separating color picture signal by providing a variable frequency type clock generator circuit that changes the frequency of a pulse wave generated according to each control signal. CONSTITUTION:An image sensor 1 outputs incident optical information in accordance with a clock pulse from the frequency variable type drive clock generator circuit 2 as a pulse signal and supplies it to an amplifier circuit 3. The frequency of an output signal from the sensor 1 varies in accordance with a frequency control signal applied to a control terminal 11. Since the amplifier circuit 3 has a gain characteristic corresponding to the frequency of an input signal, the level of the output signal of the amplifier circuit 3 varies in accordance with the frequency of a signal with the same amplitude level when said signal is inputted. Accordingly, even if the output voltage of a reference voltage generator circuit 5 is constant, the level of a picture signal 15 inputted to a comparison and binarization circuit 4 varies in accordance with the input of the control terminal 11, and the binarization level also varies, which is the same as a reference voltage is changed.
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