Television receiver

Abstract

Abstract PURPOSE:To always keep a contrast of a slave picture constant, and to always read the contents of an image without any trouble by controlling the contrast of the slave picture without making it depend on a master picture. CONSTITUTION:A video signal 12 sent out from a synthesizing circuit 8 is supplied to a cathode ray tube 6, and also supplied to a master picture contrast controlling circuit 13 and a slave picture contrast holding circuit 14. The master picture contrast controlling circuit 13 uses an average current of the cathode ray tube 6 as a control signal and controls a contrast of the video signal 12. The slave picture contrast holding circuit 14 is brought to an on-off control by a gate pulse 11, and holds a contrast of only a slave picture image signal in the video signal 12, in a constant state. Outputs of these circuits 13, 14 are selected by a switch 15 which is brought to opening and closing control by the gate pulse 11, and fed back to the synthesizing circuit 8.

Inventors

• 👤 Koji Aoki
• 👤 青木　宏司

Bibliographic Details