| 摘要 |
PURPOSE: To obtain the black level correction circuitry for a high sensitivity television camera in which the stability of a black level and black balance at high gain is improved. CONSTITUTION: An optical black clamp circuit 3 clamps at first a black level of an optical black section included in an output signal of a solid-state image pickup element 1. A gain adjustment circuit 5 adjusting an output level of the solid-state image pickup element 1 after the processing, black level detection circuits 6a, 6b detecting a black level and a black level adjustment circuit 4 clamping a black DC level are formed to be a closed loop and DC clamping is conducted by a signal detected by the black level detection circuits 6a, 6b. Thus, even in the case of the high sensitivity camera whose gain is very high, the black level is made stable and fluctuation in the black level with respect to a temperature change/gain change can be suppressed. |
