Kabushiki Kaisha Toshiba

Rca Inc.

Tokyo Shibaura Denki Kabushiki Kaisha

Yoji Miyasako

Toru Tanaka

Takashi Sugimoto

Albert Y Chang

A video signal control apparatus disclosed herewith stores, in a memory, contrast control data that is output from a video operation unit, reads out the control data from the memory during a vertical retrace period in which no image is output, and performs contrast control within the vertical retrace period based on the control data.

Video signal control apparatus

In a television receiver, the brightness of a displayed image is controlled in response to a reference voltage having a magnitude related both to the magnitude of a voltage derived from a viewer adjustable brightness control, and to the magnitude of the DC level of color information signals during image blanking intervals.

Brightness control circuit for a television receiver

This invention is described a current mirror circuit. In a current mirror circuit wherein there are provided first and second transistors which have their emitters in common and constitute a differential amplification circuit, third and fourth transistors which have their bases in common, emitters of the first and second transistors are coupled with a constant current source, a collector of the second transistor is coupled with bases of the third and fourth transistors, a collector of the third transistor is coupled with a base of the first transistor and an input current source, a base of the second transistor is coupled with a bias node, emitters of the third and fourth transistors are coupled with a reference power source, a collector of the fourth transistor is coupled with an output node, a collector of the first transistor is coupled with the reference power source through a load resistance, and a capacitor for coupling the base and the collector of the first transistor each other.

Current mirror circuit

In a color signal processing circuit having first and second chroma amplifiers, a burst amplifier for extracting a color burst signal from an output signal of the first chroma amplifier, a synchronous color killer detector for detecting the color burst signal and for turning on/off the second chroma amplifier in accordance with the amplitude of the color burst signal and a peak detection type automatic chroma control circuit for controlling the gain of the first chroma amplifier in accordance with the amplitude of the color burst signal, a switching circuit is provided for operating the automatic chroma control circuit when the output voltage of the color killer detector reaches a second level which is higher than a first level at which the second chroma amplifier is turned on.

Growing community of inventors

Yokohama, Japan

Yoji Miyasako