JP2945691B

PURPOSE:To ensure a DC level of a video signal normally obtained from an image pickup element by stopping the charge discharge drive for a period including a clamping timing so as to prevent mis-clamping effectively at discharge of undesired charge. CONSTITUTION:A clamp pulse CLP to specify the timing for clamp processing to a video signal output from a solid-state image pickup element is generated within a generating period of a horizontal blanking pulse HBLK. In order to prevent erroneous clamp of undesired charge in advance based on the clamp pulse CLP, the production output of horizontal transfer pulse H1/H2 for the horizontal blanking pulse HBLK is stopped. As a result, the discharge of undesired charge in the clamp timing is avoided when the horizontal transfer pulse H1/H2 is generated continuously. Thus, the generation of mis-clamping for the discharge period of undesired charge is avoided effectively and the DC level of the video signal is always stably ensured.