Apparatus for inserting color character data into composite video signal

Abstract

An apparatus for inserting color character data into a composite video signal, comprises a display controller determining a character display position on the basis of a horizontal synchronizing signal and a vertical synchronizing signal to generate a character generation timing signal and a character output timing signal. A character generator receives the character generation timing signal and generates a character color data signal and a character dot data signal, which are used for controlling the kind of a character to be displayed. A luminance signal generator receives the character color data signal and generates a luminance component control signal controlling a luminance component of the character to be displayed. A carrier chrominance signal generator receives the input composite video signal, the horizontal synchronizing signal and the character color data signal, and generates a carrier chrominance signal control clock which determines a phase of a carrier chrominance signal for the character to be displayed, on the basis of a color synchronization signal included in the input composite video signal. When the character dot data signal is active, a character output circuit generates a potential level in accordance with the luminance component control signal, and outputs the generated potential level in response to the carrier chrominance signal control clock, so that a character output data having an amplitude and a phase of a desired color is inserted into the input composite video signal in accordance with the character output timing signal.