Patent ID: 6674482
Filing Date: 2004-01-06
Classification: H03L,H04N

Abstract:
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 vertical sync phase controlling unit includes: a phase difference detector for detecting a phase difference between the vertical sync (Vsync_in) separated from an inputted image signal and the vertical sync (Vsync) generated by the component data read controlling unit; 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 low pass filter for low pass filtering the signal selected by the multiplexer; and the voltage control crystal oscillator for varying the output frequency according to the signal filtered by the low pass filter and outputting it.