Apparatus for generating sync of digital television

An apparatus for generating a sync of a digital television in which a component data write controlling unit converts an analog component data to a digital signal according to an input horizontal sync and a vertical sync so as to be stored in a frame buffer, the apparatus comprising:

• a vertical sync phase controlling unit for varying a clock frequency of a voltage control crystal oscillator according to a phase difference between an input vertical sync (Vsync_in) and a vertical sync (Vsync) generated in a final output terminal, to reduce the phase difference;
• and
• a component data read controlling unit for dividing the output frequency outputted from the vertical sync phase controlling unit, outputting a read control signal to read the signal stored in the frame buffer in synchronization with the clock frequency, and outputting a horizontal and a vertical sync (Hsync)(Vsync) to convert the digital signal outputted from the frame buffer to a display format so as to be outputted,
• wherein the component data read controlling unit includes:
• a first divider for dividing the frequency outputted from the voltage control crystal oscillator into a predetermined ratio and generating a read clock;
• a second divider for dividing the read clock divided by the first divider into a predetermined ratio and generating a horizontal sync (Hsync);
• a third divider for dividing the horizontal sync (Hsync) divided by the second divider into a predetermined ratio and generating a vertical sync (Vsync);
• a field signal generator for generating an even field signal or an odd field signal according to the vertical sync (Vsync) divided by the third divider;
• and
• a read controller for outputting a read control signal to read a digital signal as stored in the frame buffer according to the horizontal sync (Hsync) of the second divider, the vertical sync (Vsync) of the third divider and the field signal of the field signal generator.

An apparatus for generating a sync of a digital display device, the apparatus comprising:

• a storage unit to store a converted digital signal therein;
• a vertical sync phase controlling unit to vary a clock frequency of a voltage control crystal oscillator according to a phase difference between first and second vertical syncs, so as to reduce the phase difference;
• and
• a component data read controlling unit to divide the frequency output from the vertical sync phase controlling unit, to output a control signal to read the digital signal stored in the storage unit in synchronization with the clock frequency, and to output a horizontal sync and a vertical sync to convert the digital signal outputted from the storage unit to a display format,
• wherein the vertical sync phase controlling unit includes:
• a phase difference detector for detecting a phase difference between the first vertical sync separated from an inputted image signal and the second vertical sync;
• a multiplexer for outputting either one of an ATSC PWM signal and the signal detected by the phase difference detector according to a signal outputted from a CPU;
• a filter for filtering the signal selected by the multiplexer;
• and
• the voltage control crystal oscillator for varying the frequency output from the vertical sync phase controlling unit according to the signal filtered by the filter.