Black level correcting circuit

Abstract

Abstract PURPOSE:To correct the fluctuation of lightness attended with the manual adjustment of contrast, by detecting an adjusting level of contrast and feeding back the output to a black level output control circuit. CONSTITUTION:A video signal is amplified at a transistor (TR) 1b constituting a buffer amplifier 1 and applied to pedestal clamp circuits 2, 4. The adjusting level of contrast is detected with a TR 10b constituting a contrast adjusting level detecting circuit 10, and the contrast adjusting level detecting signal being this output is fed back to an input of the black level output control circuit 6 via a diode 6e. The predestal clamp circuit 2 is controlled with the output signal of the black level output control circuit 6.

Inventors

• 👤 Koichi Sunada
• 👤 砂田　厚一

Bibliographic Details