KR20040036081A - Television receiver and method for eliminating transient phenomena in channel switching - Google Patents

Abstract

PURPOSE: A method for removing an excessive phenomenon while changing a television channel is provided to stepwise change levels of each R, G, and B signal when changing a television channel, in order to prevent a screen from flickering or shaking, thereby naturally changing a channel and more exactly intercepting the screen when controlling overall brightness. CONSTITUTION: A user displays a video signal of a selected broadcasting channel(510). While the broadcasting channel is displayed on a screen, a system checks whether the channel is changed through an inputted key signal(520). If so, the system receives a command for the channel change from a remote controller or a front panel, and reduces levels of R, G, and B signals(530). The system stepwise reduces the levels until the levels of the R, G, and B signals become minimal(540). If a broadcasting signal of the changed channel is received, the system increases the levels of the R, G, and B signals(570), and stepwise increases the levels until the levels become previous values(580). The system displays the broadcasting signal of the changed channel(590).

Description

Transient receiver and method for eliminating transient phenomena in channel switching

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a television receiver for displaying a screen using a CRT, and more particularly to a method for removing a transient phenomenon when a television channel is changed and a television receiver to which the same is applied.

In general, when the channel is changed in the TV, the screen shake occurs due to the instability of the synchronization signal.

Therefore, in the related art, the video signal is muted for a while when the channel is changed so as not to be displayed on the screen, or the brightness of the screen is darkened so that the synchronization signal is not displayed when the channel is changed.

Referring to FIG. 1, the tuner 110 tunes an RF signal induced by an antenna and converts the RF signal into an intermediate frequency (IF) signal.

The surface acoustic wave filter 120 removes unnecessary frequency components other than the IF signal generated by the tuner 110.

The video demodulator 130 demodulates the video signal components included in the IF signal output from the SAW filter 320 and outputs the result in a composite video base signal (CVBS) form.

The video processor 140 extracts an RGB signal from the CVBS signal output from the video demodulator 130.

The CRT driver 150 drives the CRT 160 using the RGB signal input from the video processor 140.

If the user changes the channel through the remote controller 180, the controller 170 blocks the video signal by applying a video mute signal to the video processor 140 while synchronizing with the signal of the channel, and the synchronization signal for the changed channel is When detected from the video demodulator 130, the blocked video signal is recovered. Referring to FIG. 2, the video signal of the channel before the change is displayed in the first on-air section 210, the video signal of the channel after the change in the second on-air section 230 is displayed, and in the video mute section 220. The video signal is not displayed.

However, the video blocking method when changing the channel as shown in FIG. 1 temporarily blocks the video signal, thereby causing a burden on the eyes of the viewer because the screen is severely changed when viewing a bright screen or turning off the lights at night.

In addition, conventionally, there is a method of gradually fading out a screen by adjusting brightness during screen output when changing a channel, and fading in after changing a channel. However, in this case, even if the screen brightness is minimized, the screen output is not completely blocked, so there is a problem in that the return of the channel changes.

SUMMARY OF THE INVENTION The present invention has been made in an effort to provide a transient removal method that prevents flickering or blurring of a screen by gradually changing the level of an RGB signal when a television channel is changed.

Another technical problem to be achieved by the present invention is to provide a television receiver to which the method for removing a transient phenomenon when the channel is changed.

In order to solve the above technical problem, the present invention provides a method for removing a transient phenomenon when changing a channel in a television receiver that outputs a video signal by tuning a corresponding channel,

Receiving a channel change command while displaying the RGB signal of the channel;

Searching for a channel after decreasing the signal level of each RGB when the channel command is input until the signal level becomes a minimum value;

When the channel is searched and the channel change is completed, the step of increasing the signal level of each RGB until the previous value is characterized in that it comprises a step.

In order to solve the above other technical problem, the present invention provides a television receiver,

A tuner unit which tunes the RF signal induced from the antenna and converts the RF signal into an IF signal;

A video demodulator extracting a synthesized video baseband signal from the IF signal output from the tuner;

A video processor for extracting an RGB signal from the synthesized video baseband signal output from the video demodulator;

A CRT driver configured to drive a CRT by adjusting a level of an RGB signal output from the video processor;

A CRT unit displaying an RGB signal output from the CRT driver;

A control unit that gradually decreases the RGB signal level of the CRT driver when the channel change command is input; and increases the RGB signal level of the CRT driver when the synchronization signal is detected from the composite video baseband signal extracted by the video demodulator. Characterized in that it comprises a.

1 is an overall block diagram of a television receiver that mutes a video signal in the prior channel change.

2 is a waveform diagram of a conventional television channel change.

3 is an overall block diagram of a television receiver for removing a transient during channel change according to the present invention.

Figure 4 is a waveform diagram of each of the RGB output to remove the transient phenomenon when changing the channel according to the present invention.

5 is a flowchart illustrating a method of removing a transient phenomenon when changing a channel in a television receiver according to the present invention.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

3 is an overall block diagram of a television receiver for removing a transient during channel change according to the present invention.

Referring to FIG. 3, the tuner 310 tunes an RF signal induced by an antenna to convert an IF signal into an intermediate frequency (IF) signal. Typically, this tuner 310 has a high frequency amplification circuit, a local oscillation circuit, a frequency conversion circuit, and the like. This IF signal is generated by the difference between the received frequency and the local oscillator frequency and is usually lower than the received frequency. For example, in a television receiver, the video intermediate frequency varies depending on the broadcasting system, but usually uses 38.9 MHz.

The surface acoustic wave filter 320 removes unnecessary frequency components other than the IF signal generated by the tuner 310. In this case, the modulated video signal and the sound signal are included in the IF signal.

The video demodulator 330 demodulates the modulated video signal component included in the IF signal output from the SAW filter 320 and outputs the result in the form of a composite video base signal (CVBS). This CVBS signal is composed of a synchronization signal and a video signal.

The video processor 340 extracts an RGB signal from the CVBS signal output from the video demodulator 330.

The CRT driver 350 controls the image quality such as the brightness of the CRT, the size of the screen, the contour correction, and the like to correct the color by controlling the signal level of each RGB output to the CRT in order for the CRT 360 to drive at the optimum image quality. do.

The cathode ray tube (CRT) 360 displays an RGB signal output from the CRT driver 350 on the screen.

When the channel change command is input from the remote controller 380, the controller 370 applies the respective RGB signal level adjustment values to the CRT driver 350 to gradually reduce the RGB signal level, and then synchronizes the signal from the video demodulator 330. If is detected, the RGB signal level is incrementally increased by applying an RGB level adjustment value to the CRT driver 350.

4 is a waveform diagram for removing a transient phenomenon when changing a channel according to the present invention.

Referring to FIG. 4, the first on air section 410 is a section in which the RGB signal of the channel before the change is displayed, and the second on air section 430 is a section in which the RGB signal of the channel after the change is displayed, and the video mute is performed. Section 420 is an RGB blanking section in which no RGB signal is displayed. The RGB output reduction section is a section in which the magnitude (brightness) of the RGB signal decreases step by step when a command for a broadcast channel is received, and the RGB output increase section is the size of the RGB signal when a synchronized broadcast channel signal is received. It is a section in which (brightness) increases step by step.

5 is a flowchart illustrating a method of removing a transient phenomenon when changing a channel in a television receiver according to the present invention.

First, a video signal of a broadcast channel selected by a user is displayed (step 510).

In the state where the broadcast channel is displayed on the screen, it is checked whether the channel is changed through the key signal input by the remote controller or the front panel (step 520).

At this time, upon receiving a command for changing a channel from the remote controller or the front panel, the RGB signal level of the CRT driver 350 is decreased by Δx (see RGB output reduction section of FIG. 4) (step 530). Then, the RGB signal level is gradually decreased by Δx until it reaches a minimum value (eg, 0Vpeak-peak) (step 540). Here, the time taken to decrease the RGB signal stepwise may be adjusted. For example, if the RGB signal of 1Vp-p is blocked in 30 steps in 1 second, 1 ÷ 30 = 1/30 seconds and 1Vp-p / 30 = 1 / 30Vp-p. Step down by / 30Vp-p.

At the same time, the broadcast signal of the channel selected by the user from the remote controller 380 is transmitted to the tuner 310. At this time, the tuner 310 searches for a channel to be changed and performs synchronization. Here, since the RGB signal is blocked in the RGB blanking period until the synchronization is tuned by the tuner 310, unnecessary signals such as horizontal blanking do not appear on the screen (refer to the video mute section in FIG. 4). This RGB blanking period can be arbitrarily modified.

Subsequently, when the tuner 310 receives a broadcast signal of a channel that is synchronized and synchronized, the RGB signal level is increased by Δx (refer to the RGB output increasing section of FIG. 4) (step 570). Subsequently, the RGB signal level is gradually increased by Δx until the previous value (eg, 1Vpeak-peak) is reached (step 580). Here, the time taken to raise the RGB signal step by step is adjustable. For example, if 1Vp-p RGB signal is reproduced in 30 steps per second, 1 ÷ 30 = 1/30 seconds and 1Vp-p / 30 = 1 / 30Vp-p, so 1/30 seconds for each step. In steps of 1 / 30Vp-p. At this time, the time it takes to block each signal of RGB and increase again should be within 0.3 ~ 0.5 seconds so that the viewer's eyes are not uncomfortable.

In operation 590, the broadcast signal of the changed channel is displayed.

As a result, when the user changes the channel, the transient cancellation method according to the present invention can change the channel naturally without the transient phenomenon than the channel changing method by the conventional video muting, and also simply controls each RGB signal. When controlling the overall brightness of the screen, you can block the screen more accurately.

The present invention is not limited to the above-described embodiment, and of course, modifications may be made by those skilled in the art within the spirit of the present invention.

As described above, according to the present invention, the flickering or shaking of the screen can be prevented by changing the level of each RGB signal step by step when changing the television channel.

Claims (5)

In the method of removing a transient when changing a channel in a television receiver displaying a video signal by tuning a corresponding channel, (a) receiving a channel change command while displaying the RGB signal of the corresponding channel; (b) searching for a channel after decreasing the signal level of each RGB by a predetermined value when the channel command is received; and (c) stepwise increasing the signal levels of the respective RGB signals by a predetermined value when the channel is searched and the channel change is completed. The method of claim 1, further comprising: blocking signal levels of respective RGB signals while searching for the channel. The method of claim 1, wherein the channel change of step (c) is performed by detecting a demodulated video synchronization signal. The method of claim 1, wherein the level of each RGB in the step (c) is increased step by step at the time of detecting the synchronized RGB signal. In a television receiver, A tuner unit which tunes the RF signal induced from the antenna and converts the RF signal into an IF signal; A video demodulator extracting a synthesized video baseband signal from the IF signal output from the tuner; A video processor for extracting an RGB signal from the synthesized video baseband signal output from the video demodulator; A CRT driver configured to drive a CRT by adjusting a level of an RGB signal output from the video processor; A CRT unit displaying an RGB signal output from the CRT driver; A control unit that gradually decreases the RGB signal level of the CRT driver when the channel change command is input; and increases the RGB signal level of the CRT driver when the synchronization signal is detected from the composite video baseband signal extracted by the video demodulator. Television receiver comprising a.