KR0124601B1 - Apparatus for eliminating a noise of vertical sync. signal in tft-lcd tv - Google Patents

Abstract

There is provided an apparatus for removing a noise from a vertical synchronous signal in a TFT-LCD television. The removing apparatus includes: an integral part for integrating a composite synchronous signal to output a vertical synchronous signal; and an initializing part for initializing both a counter and a selection part when a desired vertical synchronous signal is output from the integral part, the counter counting a time taken from which the desired vertical synchronous signal is output from the integral part, and the selection part selecting only a desired signal from the output vertical synchronous signal of the integral part according to the output signals of the counter and the initializing part.

Description

Vertical Synchronous Signal Noise Canceling Device for TFT-LCD TV

1 is a basic configuration of a TFT-LCD.

2 is a block diagram of a conventional vertical synchronization signal generator.

3 is a graph showing normal composite and vertical synchronous signals of a conventional vertical synchronous signal generator.

4 is a graph showing an abnormal composite synchronous signal and a vertical synchronous signal of a conventional vertical synchronous signal generator.

5 is a block diagram of a vertical synchronization signal noise canceller of the liquid crystal TV of the present invention.

6 is a detailed circuit diagram of the selector of FIG.

7 is an output waveform diagram of each part of the vertical synchronization signal noise canceller of the liquid crystal TV of the present invention.

* Explanation of symbols for main parts of the drawings

11: Integrator 12: Initializer

13: counter 14: selection

15: Exclusive noah gate

16: AND gate 17: Inverter

19 Inverter 18 D-flip flop

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal television (TFT-LCD TV), and more particularly, to a vertical synchronization signal noise canceling device of a liquid crystal TV that is suitable for removing a vertical synchronization signal noise component of the liquid crystal TV to prevent shaking of the screen.

The basic structure of the TFT-LCD will be described with reference to the accompanying drawings.

1 shows the basic configuration of the TFT-LCD.

First, as shown in FIG. 1, the control unit 1 controls each unit by inputting a composite synchronization signal, a video signal, and a power signal, and receives each control signal of the control unit 1 to drive each pixel of the LCD panel. A panel for displaying an image signal by driving the vertical driving IC 2 and the upper and lower horizontal driving ICs 3a and 3b and the vertical driving IC 2 and the upper and lower horizontal driving ICs 3a and 3b. It consists of (4).

Hereinafter, a conventional vertical synchronization signal generating apparatus and method of a TFT-LCD will be described with reference to the accompanying drawings.

2 is a block diagram of a conventional vertical synchronous signal generator.

As shown in FIG. 2, it can be seen that the vertical synchronization signal for synchronizing various control signals of the TFT-LCD is obtained by simply integrating the composite synchronization signal in the integrator 5.

Next, FIG. 3 is a graph showing a conventional composite and vertical synchronization signal, showing that the composite synchronization signal is integrated into the vertical synchronization signal by the integrator 5 of FIG.

However, in the conventional vertical synchronization signal generating device and method of the above-described TFT-LCD, when the composite synchronization signal containing noise is integrated by the integrator as shown in FIG. 4, the desired vertical synchronization signal and the unwanted vertical synchronization signal are simultaneously generated. This caused a problem that the screen flows up and down, left and right because the various control signals are not synchronized.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object thereof is to provide a vertical synchronization signal noise canceling device for a liquid crystal TV in which various control signals are synchronized by realizing the removal of unwanted vertical synchronization signals.

Vertical sync signal generator of the liquid crystal TV of the present invention for achieving the above object is an integral part for integrating the composite sync signal to output a vertical sync signal, and the desired signal of the vertical sync signal output from the integrator An initialization unit for initializing the following counter and selection unit each time, a counter for counting a predetermined time after inputting a desired synchronization signal to remove noise within a specific time period from a desired vertical synchronization signal among the vertical synchronization signals outputted from the integration unit; And a selector for selecting only a desired signal from the vertical synchronization signal output from the integrator by the output signal of the counter and the initializer.

Hereinafter, with reference to the accompanying drawings and described in more detail the vertical synchronization signal noise canceller of the liquid crystal TV of the present invention.

5 shows a block diagram of a liquid crystal TV vertical synchronization signal noise canceller of the present invention. An integrating unit 11 for integrating a complex synchronizing signal and outputting a vertical synchronizing signal, and initializing the counter and the selecting unit whenever a desired signal is input from the vertical synchronizing signal by inputting the vertical synchronizing signal output from the integrating unit 11; The counter 12 and a counter 13 for counting a predetermined time after input of a desired signal in order to determine which noise within a specific time from the desired vertical synchronization signal among the vertical synchronization signals output from the integrating unit 11 is removed. And a selector 14 which selects only a desired signal from the vertical synchronization signal output from the integrator 11 by the output signals of the counter 13 and the initialization unit 12.

Here, the configuration of the selection unit 14 will be described in more detail with reference to FIG.

That is, FIG. 6 is a detailed circuit diagram of the selector of FIG. 5, which includes an exclusive NOR gate 15 for exclusively ORing the outputs of the initialization unit 12 and the counter 13 and the integrating unit. AND gate 16 for ANDing the output signal of (11) and the signal fed back from the second inverter below, and outputting only the desired synchronization signal, and a first inverter for inverting the output of the AND gate 16. (17), a D-flip-flop (DF / F) 18 that delays the output of the first inverter 17 by using the output signal of the exclusive noar gate 15 as a clock signal, and the D A second inverter 19 which inverts the output of the flip-flop 18 and feeds it back to one end of the AND gate 16.

Referring to the operation of the liquid crystal TV vertical synchronization signal noise canceller of the present invention configured as described above is as follows.

FIG. 7 is an output waveform diagram of each part of the present invention. First, the composite synchronization signal is integrated in the integrating unit 11 to generate a vertical synchronization signal. When the composite synchronization signal has no noise, only the desired synchronization signal A is shown in FIG. Although it occurs as shown in (a), if there is noise in the composite synchronous signal, the desired vertical synchronous signal A and the unwanted vertical synchronous signal B are simultaneously generated as shown in FIG.

The initialization signal of the initialization unit 12 initializes the selection unit 14 and the counter 13 whenever a desired vertical synchronization signal is generated among the vertical synchronization signal outputs of the integration unit 11 as shown in FIG. To reset the circuit before starting the count.

Then, the counter 13 determines a signal within a certain time after outputting the desired synchronization signal A as a noise.

That is, the period of the desired vertical synchronization signal (A) is 16.67 msec in the case of NTSC, to determine whether to remove the signal within 13msec or 14msec, 15msec within the count range is shown in Figure 7 (d) It is larger than the range from the falling edge (fal-ling edgd) of the desired vertical synchronization signal (A) to the falling edge of the unwanted vertical synchronization signal (B), and from the falling edge of the desired vertical synchronization signal (A) as follows. The count number is set to be smaller than the range to the rising edge of the desired vertical synchronization signal A.

The start of the counter is equal to the falling edge of the desired vertical sync signal A.

Accordingly, the selector 14 outputs a waveform as shown in FIG. 7E to output only a desired vertical synchronization signal.

The output of the selector 14 will be described in more detail as follows.

That is, when the initialization signal as shown in FIG. 7 (c) and the output of the counter 13 as shown in FIG. 7 (d) are input to the exclusive noar gate 15, the output of the exclusive noar gate 15 is It is output as shown in FIG. 7 (f) and applied to the clock CLK terminal of the D-flip flop 18.

Since the D-flip-flop 18 outputs a low signal in an initial state, the D-flip flop 18 is inverted by the second inverter 19 and input to one end of the AND gate 16, so that the output signal of the integrator 11 is inputted to the AND gate. The input of the D-flip flop 18 at the falling edge of the input signal at the falling edge of the input signal. The output goes high and the AND gate 16 outputs a low signal regardless of the input signal.

Therefore, the D-flip-flop 18 remains in this state and then becomes low again when the output of the counter 13 becomes low so that the second inverter 19 outputs a high signal. Prepares to pass the signal output from the integrator 11.

By repeating this process, the output of the D-flip-flop 18 outputs a waveform as shown in FIG. 7 (g), and the AND gate 16 uses only the desired vertical synchronous signal as shown in FIG. 7 (e) through the output terminal. The unwanted signal due to the noise of the composite synchronous signal is removed and output.

As described above, in the vertical synchronous signal noise removing device of the liquid crystal TV of the present invention, the noise coming into the composite synchronous signal can be removed within a predetermined time, thereby preventing the shaking of the screen due to the noise.

Claims (2)

An integrator for integrating a complex synchronous signal and outputting a vertical synchronous signal, an initializer for initializing the following counter and a selector whenever a desired signal is output among the vertical synchronous signals output from the integrator, and a vertical output from the integrator A counter for counting a predetermined time after inputting a desired sync signal to remove noise within a certain time from the desired vertical sync signal among the sync signals, and a desired signal among the vertical sync signals output from the integrator by the output signals of the counter and the initialization unit. Vertical synchronization signal noise canceller of the liquid crystal TV, characterized in that it comprises a selection unit for selecting only. The receiver of claim 1, wherein the selector is configured to exclusively OR the negative outputs of the initialization unit and the counter, and an AND gate to output only a desired synchronization signal by performing an AND operation on the signal fed back with the output signal of the integrator. A first inverter for inverting the output of the AND gate, a D-flip flop for delaying the output of the first inverter using the output signal of the exclusive noar gate as a clock signal, and an output of the D-flip flop And a second inverter for feeding back to one end of the AND gate by inverting the vertical synchronization signal of the liquid crystal TV.