Multipage display apparatus of teletext receiving system

Claim 1

A multipage display apparatus comprising: a microprocessor for controlling a teletext receiving system and processing data; a tuner for selecting a channel under the control of said microprocessor; a teletext unit for receiving a composite video signal through the channel selected by said tuner, and sequentially outputting information corresponding to each page in synchronization with a clock signal generated in said microprocessor; first encoder for encoding signals R, G and B outputted from said teletext unit and outputting a composite video signal; a synchronizing and sampling frequency separator for receiving the composite video signal outputted from said first encoder and separating a synchronization signal and a sampling frequency; a window signal generator for receiving the separated vertical and horizontal synchronizing signals from said synchronizing and sampling frequency separator and generating a control signal under the control of said microprocessor so as to select a normal or a multipage mode; a luminance signal separator for separating a luminance signal Y from the composite video signal which is an output of said first encoder; a chrominance difference signal separator for separating chrominance difference signals from the composite video signal which is an output of said first encoder; a multiplexer for selectively outputting the luminance signal and the chrominance difference signals supplied from said luminance signal separator and said chrominance difference signal separator, respectively; an A/D converter for converting a signal outputted from the multiplexer into a digital signal and outputting the converted digital signal; a controller for receiving the horizontal and vertical synchronizing signals outputted from said synchronizing and sampling frequency separator and the luminance and chrominance difference signals outputted from said A/D converter, and controlling the write-in and the read-out of said luminance and chrominance difference signals under the control of said microprocessor; a memory unit in which the luminance and chrominance difference signals outputted from said A/D converter are written in and are read out under the control of said controller; a D/A converter for converting the luminance and chrominance difference signals read out from said memory unit into analog signals and outputting the converted analog signals; a second encoder for receiving the luminance signal and the chrominance difference signals outputted form said D/A converter, respectively, converting into a composite video signal, and outputting the converted composite video signal; and a switch unit for selectively outputting composite video signals supplied from said first and second encoders, by the control signal outputted from said window signal generator.