Clamp circuit with feed back
AssigneeCanon Kabushiki Kaisha
InventorSeiji Hashimoto
Life of this patent
Estimating the term…
Abstract
A clamp circuit comprising: a clamp circuit for clamping an input video signal to a predetermined clamp level in the interval corresponding to a first gate signal; a clamp level forming device for extracting a signal after it is clamped in the interval corresponding to a second gate signal, thereby forming the clamp level; and a signal generating circuit for outputting the first and second gate signals in the black level interval in the signal so that the trailing edge of the first gate signal is time-delayed relative to the trailing edge of the second gate signal. With this clamp circuit, the stable black level can be obtained, so that an image pickup camera in which the clamping characteristic was improved is realized.
Claims21
A clamp circuit comprising:
- clamp means for clamping an input video signal to a predetermined clamp level in an interval corresponding to a first gate signal;
- clamp level forming means for extracting a signal which was clamped by said clamp means in an interval corresponding to a second gate signal to form said predetermined clamp level;
- and
- signal generating means for outputting said first and second gate signals in a predetermined level interval in the signal.
A clamp circuit comprising:
- means for causing a signal at a predetermined level to act on an input video signal during at least a partial interval except for a reference black level interval in a horizontal blanking interval of said input video signal;
- and
- clamp means for clamping the signal which was caused to be at said predetermined level by said causing means to a clamp level.
A clamp circuit comprising:
- (a) signal generating means for outputting a signal at a predetermined level over a predetermined interval in a horizontal blanking interval;
- (b) means for allowing said signal to act on a video signal in said predetermined interval in the horizontal blanking interval;
- (c) clamp means for clamping the video signal in at least a part of said predetermined interval on the basis of said signal;
- and
- (d) means for controlling a clamp level of said clamp means in accordance with a level of the signal in a reference black level interval in the video signal which was clamped by said clamp means.
Dependencies are inferred from the claim text.