Generation device of multi-cutting horizontal synchronization signal and method thereof

Abstract

The invention discloses a generation device of a multi-cutting horizontal synchronization signal and a method thereof. The generation device comprises a cutter, a numerical control oscillator, a first phase detector, a second phase detector and a correcting circuit. The cutter performs edge detection on a video signal containing a first horizontal synchronization signal respectively according to a first voltage level and a second voltage level to respectively generate a first detection signal and a second detection signal; the numerical control oscillator can generate a second horizontal synchronization signal; the first phase detector can detect a first phase difference between the first detection signal and the second horizontal synchronization signal while the second phase detector candetect a second phase difference between the second detection signal and a reference time point; and the correcting circuit can generate a correcting signal according to the first phase difference and the second phase difference while the numerical control oscillator adaptively regulates the phase of the second horizontal synchronization signal according to the correcting signal.

Description

technical field [0001] The present invention relates to a video clock, especially a multi-slicing horizontal synchronization signal generation device and method. Background technique [0002] Today’s commonly used analog TVs, such as LCD TVs (LCDTV), plasma TVs, etc., must generate corresponding horizontal and vertical synchronization signals for the video signals to be displayed, such as composite video broadcast signals (CVBS). Video frequency for on-screen display. Existing analog TVs use the architecture shown in FIG. 1 to generate horizontal synchronization signals. In FIG. 1 , a slicer 11 receives a CVBS signal, and when the voltage value of the CVBS signal crosses a specific voltage level from high to low, generates a pulse signal to represent the detection of the CVBS signal. The horizontal sync signal in . Next, the pulse signal is sent into a phased lock loop (phased lock loop) 10, wherein the phase detector 12 detects the pulse signal and a numerically controll...

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Problems solved by technology

[0005] However, in addition to the situation of FIG. 3A, the phase detector 12 may also detect larger phase differences in other situations.

For example, when the TV channel is switched, the CVBS signal sent to the cutter 11 will produce a change as shown in Figure 3B, that is, the signal of the original channel will switch to the signal of the new channel when the signal of the original channel is halfway through, but the signal of the NCO14 The output horizontal synchronous signal cannot change immediately, so the phase detector 12 will detect a large phase difference

At this time, if the NCO14 only makes a small correction, it will take a long time to adjust the channel before the picture can return to normal, which will affect the user's visual effect

[0006] Therefore, when the existing structure of FIG. 1 encounters the above two situations that will generate a large phase difference (ie, FIG. 3A and FIG. 3B ), it will lose sight of the other, and it is difficult to properly correct the phase of the horizontal synchronization signal, which is likely to cause screen shake

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