| 摘要 |
PURPOSE:To prevent the deterioration of video quality, by resetting the peak hold circuit holding the peak value of video signal read out, within nonvideo signal period during each readout period. CONSTITUTION:Every time the original and image sensor IS relatively move toward subscanning direction by a given amount, the control pulse to start readout is produced at the timing pulse generator TPG based on the amount of movement detecting pulse Pd from the amount of movement detecting circuit DS. The drive circuit DC supplies the drive pulse to IS so that IS can start the readout of the video signal Sa at a new scanning line unit position. Further, IS generates the reset signal Pr from TPG during the nonvideo signal period Tb on and after the end of readout of video signal at the scanning line position and resets the peak hold circuit PH. Accordingly, the threshold voltage Vs based on the peak value held at PH is reset every end of the main scanning, and the voltage Vs is produced every new main scanning and is given to the comparator COMP for the comparison with the signal Sa, allowing to produce binary signal. |
