KR19990041229A - Television receiver with moire phenomenon prevention function at the time of no signal - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a television receiver having a moiety prevention function at the time of no signal, which is capable of eliminating the moire phenomenon appearing on the screen in the no signal state, and is supplied from an external A / V device according to a predetermined control signal. A / V switching unit 11 for selectively switching one of the video and audio signals and the broadcast signal received and processed by the antenna, and the signal output from the audio output terminal of the A / V switching unit 11 Outputs a predetermined oscillation pulse for the horizontal and vertical outputs of the CRT 19 based on the synchronization signal detection unit 20 for detecting and detecting the synchronization signal and the synchronization signal separately detected by the synchronization signal detection unit 20. In addition, a chroma IC 23 for outputting a color difference signal and a luminance signal for outputting an image is provided by driving the CRT driver 18 based on the composite image signal applied from the A / V switching unit 11. In the television receiver; The synchronization signal 22 which performs frequency correction and phase correction on the synchronization signal detected by the synchronization signal detection unit 20 according to a predetermined control signal, and the synchronization signal by the synchronization signal detection unit 20 are not detected. If no signal determination unit 21 outputs a determination signal of the first level, and the determination signal of the first level is applied from the signal-free determination unit 21, the synchronization correction unit 22 is controlled and tuned. And a controller 24 for adjusting the reference frequency to be restored to the synchronization signal reference frequency in the broadcast reception mode.

Description

Television receiver with moire phenomenon prevention function at the time of no signal

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a television receiver, and in particular, a moire phenomenon that appears on a screen in a no signal state by automatically returning a frequency of a synchronization signal to an initial setting value immediately after the input of an external video signal having a low synchronization frequency is stopped. The present invention relates to a television receiver having a moyer phenomenon prevention function at the time of no signal which can solve the problem.

Some television receivers (hereinafter, referred to as TV receivers) currently on the market are configured to perform more various and comprehensive functions by connecting to an external device such as a VCR. It is a block diagram showing the main components of a general TV receiver equipped with a function.

In Fig. 1, reference numeral 1 denotes an antenna for receiving an airwave broadcasting signal, 2 denotes a tuner for tuning the broadcast signal received by the antenna 1, and 3 denotes an intermediate frequency signal output from the tuner 2; IF amplifier that amplifies (IF signal).

Also, reference numeral 4 denotes P / S separation, for example, consisting of a surface acoustic wave filter (SAW FILTER) for separating the IF signal output from the IF amplifier 3 into an image intermediate frequency signal PIF and an audio intermediate frequency signal SIF. 5 is an image signal detector for detecting a video intermediate frequency signal separated and output from the P / S separator 4 and outputting a composite video signal, and 6 is outputted from the P / S separator 4 An audio signal detection unit detects an audio signal from an audio intermediate frequency signal.

On the other hand, reference numeral 7 is a remote control device for the viewer to adjust the output volume or to remotely control the whole other device, 8 is to receive the infrared signal transmitted from the remote control device 7 and converts it into an electrical signal The receiving unit 9 is a microcomputer as a control unit which controls the whole apparatus in accordance with the contracted code signal output from the receiving unit 8, and 10 is a video (V; video) and an audio (R) output from an external device, for example, a VCR. A / V connection terminal 11 for receiving a Right, L; Left signal, 11 is a signal received and processed by the antenna 1 according to a predetermined switching control signal from the microcomputer 9 and the A / V connection A / V switching unit for selectively switching the signal applied into the TV via the terminal 10, 12 is not shown for the audio signal output from this A / V switching unit 11, but from the micom (9) Predetermined control scene The voice processing unit for processing the base, treble, volume control, etc., 13 amplifies the audio signal processed by the voice processing unit 12 and outputs to the speaker 14 connected to the rear stage It is wealth.

Although not illustrated, reference numeral 16 may be used to indicate the brightness, tint, and color of the image signal output from the A / V switching unit 11 according to a predetermined control signal from the microcomputer 9. ) Is an image processing unit which outputs R (Red), G (Green), B (Blue) and luminance (Y) signals corresponding to the image signal by processing the adjustment, etc., and 18 denotes the R output from the image processing unit 16. A CRT driving unit for driving a CRT (Cathode-ray Tube) connected to the rear stage based on the G, B and luminance (Y) signals.

That is, in the conventional TV receiver having the above-described configuration, when the viewer operates the remote controller 7 to select one of the broadcast reception mode (RF mode) and the A / V input mode (A / V mode), the microcomputer A broadcasting signal, i.e., an RF signal side, tuned and processed by the tuner 2 by switching control of the A / V switching section 11 by 9; By selectively switching either the video and audio signals applied to the inside of the TV receiver via the A / V connecting terminal 10, that is, the A / V signal side, and as a result, the CRT 19 and the speaker Through 14, video and audio of the processed signal are output.

On the other hand, some video players such as VCRs use a 50 Hz synchronization signal which is somewhat lower in frequency than the 60 Hz synchronization signal used in a TV receiver. When it is applied to the inside of the TV receiver through 11, the synchronization circuit inside the TV is driven accordingly, so that even after the reproducing operation is terminated, the injection player is kept in a somewhat larger state for a while.

Therefore, due to the concentration of the electron beam, a gathering phenomenon appears on the screen for a while in the non-signal state in which there is no broadcast signal immediately after the reproduction operation, which causes the reliability of the product.

The present invention has been made in view of the above-described circumstances, and the mower appears on the screen in the no signal state by automatically returning the frequency of the synchronization signal to the initial setting value immediately after the input of the external video signal having a low synchronization frequency is stopped. It is an object of the present invention to provide a television receiver equipped with a moire-free function at the time of no signal which can solve the moire phenomenon.

1 is a block diagram showing a conventional general television receiver equipped with an external device connection function.

Figure 2 is a block diagram showing the main configuration of a television receiver equipped with a moyer phenomenon prevention function at the time of no signal in accordance with an embodiment of the present invention.

******* Explanation of symbols on the main parts of the drawings *******

1 antenna 2 tuner (TUNER)

3: IF amplification unit 4: P / S separation unit

5: Image signal detector 6: Voice signal detector

7: remote control unit 8: receiving unit

9: Microcomputer 10: A / V connection terminal

11: A / V switching unit 12: voice processing unit

13: voice amplifier 14: speaker

16: image processing unit 18: CRT driving unit

19: CRT (Cathode-ray Tube) 20: Synchronization signal detector

21: No Signaling Decision 22

23 Chroma IC 24 Microprocessor

According to the present invention for realizing the above object, a television receiver having a moiety prevention function at the time of no signal among the video and audio signals supplied from an external A / V device and a broadcast signal received and processed by an antenna according to a predetermined control signal An A / V switching unit 11 for selectively switching one, a synchronization signal detection unit 20 for detecting a synchronous signal by detecting a signal output from the audio output terminal of the A / V switching unit 11, and The composite image is output from the A / V switching unit 11 while outputting predetermined oscillation pulses for the horizontal and vertical outputs of the CRT 19 based on the synchronization signal separated and detected by the synchronization signal detector 20. A television receiver having a chroma IC 23 for outputting a color difference signal and a luminance signal for outputting an image by driving the CRT driver 18 based on a signal; The synchronization signal 22 which performs frequency correction and phase correction on the synchronization signal detected by the synchronization signal detection unit 20 according to a predetermined control signal, and the synchronization signal by the synchronization signal detection unit 20 are not detected. If no signal determination unit 21 outputs a determination signal of the first level, and the determination signal of the first level is applied from the signal-free determination unit 21, the synchronization correction unit 22 is controlled and tuned. And a controller 24 for adjusting the reference frequency to be restored to the synchronization signal reference frequency in the broadcast reception mode.

That is, according to the present invention having the above-described configuration, when the input of the reproduced video from an external device is interrupted and temporarily becomes a no signal state, scanning is performed by forcibly returning the frequency of the synchronization signal used in the deflection circuit to the contracted initial setting value. It is possible to solve the problem of the moire phenomenon on the screen due to the change of the player.

Hereinafter, with reference to the accompanying drawings will be described an embodiment according to the present invention.

FIG. 2 is a block diagram showing a main configuration of a television receiver equipped with a moire prevention function at the time of no signal according to an embodiment of the present invention. Components that perform substantially the same functions as those shown in FIG. The same reference numerals are used, and detailed description thereof will be omitted.

In FIG. 2, reference numeral 20 denotes a synchronization signal detection unit that detects a synchronization signal separately from a composite video signal output from the A / V switching unit 11, and 21 denotes whether a signal is detected by the synchronization signal detection unit 20. The signal-free determination unit 21 outputs a determination signal of a predetermined level according to the present invention. When the signal-free determination unit 21 determines that there is no signal detected by the synchronization signal detection unit 20, that is, no signal state is determined, The microprocessor 24 to be described later outputs a high level determination signal.

On the other hand, reference numeral 22 denotes a synchronization correction unit for performing frequency correction and phase correction on the synchronization signal detected by the synchronization signal detection unit 20. The synchronization correction unit 22 supplies a control command according to a predetermined control command. A voltage controlled oscillator 22a for generating and outputting a corresponding frequency signal, and a tuning circuit for tuning the frequency and phase of the signal applied from the synchronous signal detector 20 to the signal output from the voltage controlled oscillator 22a ( 22b) and a phase correction circuit 22c which compares the final output signal of the tuning circuit 22b with a reference frequency signal and performs phase correction by the error value.

Further, reference numeral 23 outputs a predetermined oscillation pulse for the horizontal output and the vertical output of the CRT 19 on the basis of the synchronization signal separated and detected by the synchronization signal detection unit 20 and the A / V switching unit ( 11) is a chroma IC that outputs a color difference signal and a luminance signal for outputting an image by driving the CRT driver 18 based on a composite video signal (CVS) applied from 11).

Next, the operation of the device having the above configuration will be described.

When the user selects an A / V input mode switching key (not shown) included in the remote control device 7 to execute mode switching, the microprocessor 24 controls the A / V switching unit 11. Thus, the playback video and audio signals applied from the external A / V device are controlled to be switched.

On the other hand, the synchronization signal detector 20 detects a synchronization signal from the composite video signal CVS of an external input output from the A / V switching unit 11 and synchronizes the detected synchronization signal 22 with the detected synchronization signal. Will output

At this time, the voltage controlled oscillator 22a provided in the synchronization compensator 22 generates a frequency signal (50 Hz) corresponding to the corresponding voltage according to the voltage signal applied from the phase correction circuit 22c to be described later. The frequency signal oscillated by the voltage controlled oscillator 22a is applied to the tuning circuit 22b so that the tuning circuit 22b receives the synchronization signal applied by the synchronization signal detecting unit 20 at a frequency of 50 Hz. To control the

Therefore, after the synchronization operation by the above process is executed, the synchronization correction unit 22 is set as a synchronization signal of 50 Hz until there is an input of a video signal having a different synchronization frequency.

On the other hand, when the input of the video signal SIG2 through the A / V switching unit 11 is stopped as the playback operation by the external device is terminated, the non-signal determination unit 21 is the synchronization signal detection unit 20. Since there is no signal detection by), the microprocessor 24 outputs a high level determination signal.

When the high level determination signal is applied from the non-signal determination unit 21 by the above-described process, the microprocessor 24 controls the tuning circuit 22b inside the synchronization compensator 22 to adjust the tuning reference. The frequency is restored to 60 Mz, which is the reference frequency of the synchronization signal in the broadcast reception mode. As a result, the moir phenomenon that appears on the screen in the no signal state can be prevented, and the user can then operate the remote controller 7 Even if the operation mode of the TV is switched to the broadcast reception mode, it is possible to adjust the normal screen output without moir phenomenon to the broadcast reception image applied through the A / V switching unit 11.

That is, according to the embodiment, as soon as the input of the external video signal having a low synchronization frequency is stopped, the frequency of the synchronization signal is automatically returned to the initial setting value, thereby eliminating the moire phenomenon that appears on the screen in the no signal state. It is possible to realize a television receiver equipped with a moyer prevention function at the time of no signal.

Meanwhile, the present invention is not limited to the above embodiments and can be variously modified within the scope not departing from the technical gist of the present invention.

As described above, according to the present invention, when the input of a reproduced image from an external device is interrupted and temporarily becomes a no signal state, the scanning player changes by forcibly returning the frequency of the synchronization signal used in the deflection circuit to the predetermined initial value. This can solve the problem of the moire phenomenon appearing on the screen.

Claims (2)

An A / V switching unit 11 for selectively switching one of a video and audio signal supplied from an external A / V device and a broadcast signal received and processed by an antenna according to a predetermined control signal, and the A / V switching unit A synchronization signal detection unit 20 for detecting a signal output from the audio output terminal of (11) to detect a synchronization signal, and a horizontal of the CRT 19 based on the synchronization signal separated and detected by the synchronization signal detection unit 20; Outputs a predetermined oscillation pulse for output and vertical output, and drives the CRT driving unit 18 based on the composite video signal applied from the A / V switching unit 11 to output a color difference signal and a luminance signal for image output. A television receiver provided with a chroma IC 23 for outputting; A synchronization correction unit 22 for performing frequency correction and phase correction on the synchronization signal detected by the synchronization signal detection unit 20 according to a predetermined control signal; A no-signal determination unit 21 for outputting a determination signal of a first level when the synchronization signal is not detected by the synchronization signal detection unit 20, and Control unit 24 for controlling the synchronization reference frequency 22 to restore the synchronization reference frequency to the synchronization signal reference frequency in the broadcast reception mode when the determination signal of the first level is applied from the non-signal determination unit 21. A television receiver having a moiety phenomenon preventing function at the time of no signal, comprising a). The synchronization control unit (22) of claim 1, wherein the synchronization compensator (22) includes a voltage controlled oscillator (22a) for generating and outputting a frequency signal corresponding to the control command according to a predetermined control command, and a signal applied from the synchronization signal detector (20). The tuning circuit 22b for tuning the frequency and phase with the signal output from the voltage controlled oscillator 22a, and the final output signal of the tuning circuit 22b is compared with the reference frequency signal and phased by the error value. And a phase correction circuit (22c) for performing correction, characterized in that the television receiver having the moyer phenomenon prevention function at the time of no signal.