KR200149259Y1 - Synchronous signal stabilizing apparatus for television - Google Patents

Abstract

The present invention relates to a video synchronous stabilization apparatus of a television, based on a gain control signal (AGC voltage) from the AGC 18 for stabilization of a video screen reproduced on a CRT apparatus when the video signal indicates a weak signal level. When the weak level of the video signal is determined, the control unit 26 for switching output control of the composite video IF signal including the pseudo synchronization signal and the pseudo synchronization signal activated under the control of the control unit 26 to oscillate the pseudo synchronization signal An oscillator 28, a synchronizing signal clamp circuit 30 for clamping a synchronizing signal from the image IF signal, a signal synthesizing unit 32 for synthesizing the pseudo synchronizing signal and an image IF signal clamped with the synchronizing signal, and the The synchronization signal of the synchronization signal processing unit 20 and the composite image IF signal of the signal synthesis unit 32 interposed between the synchronization signal processing unit 20 and the signal synthesis unit 32 under the control of the control unit 26. Remind And a switching unit 34 for selectively switching output to the image processing unit 14.

Description

Video Synchronization Stabilizer

The present invention relates to an image synchronization stabilization apparatus for a television. More specifically, when synchronization is unstable due to a weak level of an image signal upon reception of an over-the-air transmission of a television broadcast signal, a pseudo-synchronization signal is synthesized to an image IF signal, thereby synthesizing the CRT. An image synchronous stabilization apparatus for a television for stabilizing an image on a device.

As is well known, for reproducing a broadcast signal transmitted over the air from a broadcasting station in video and audio, for playing a video / audio signal applied via a wired cable, or for outputting a video / audio applied in a VCR as an external video playback system. The television is equipped with a CRT apparatus as a means for outputting the image.

According to the CRT apparatus of the television, the R / G / B electron gun and the R / G / B that emit an electron beam of R / G / B color corresponding to the R / G / B signal of the image reproduced by the image processing means. A horizontal / vertical deflection means for deflecting the R / G / B color beam emitted from the B electron gun in the horizontal and vertical directions, and emitting a corresponding R / G / B color upon arrival of the deflected R / G / B color beam. It comprises a fluorescent panel in which a plurality of pixel fluorescent points are formed.

Therefore, when the R / G / B signal of the image is applied to the CRT device and the horizontal / vertical deflection signal by the horizontal / vertical deflection means is applied, the color image of one frame unit is reproduced on the fluorescent panel of the CRT device. .

1 is a view illustrating a video signal processing system of a general television. Reference numeral 10 denotes a tuner which outputs only a broadcast video / audio signal for a channel to which a viewer tunes among a plurality of airwave signals received by an antenna (not shown). 12 represents an image IF processing module for performing IF (Intermediate frequency) conversion processing on the broadcast video signal applied from the tuner 10, and 14 represents an image IF applied from the image IF processing module 12. An image processor (Chroma IC) for processing a signal into an R / G / B signal to reproduce it on the CRT apparatus 16 is shown. In addition, 18 controls gain of the tuner 10 based on the level of the image signal processed by the image processor 16 (RF AGC) and controls gain of the image IF processing module 12 ( IF AGC (Auto gain control) is shown, 20 is a synchronization signal processing unit for detecting a horizontal / vertical synchronization signal in the image signal processed by the image processing unit 14, 22 and 24 are the synchronization signal processing unit ( 20 shows a vertical deflection portion and a vertical deflection portion for performing horizontal / vertical deflection of an image scene reproduced by the CRT apparatus 16 in response to the horizontal synchronous signal and the vertical synchronous signal applied in FIG.

Therefore, according to the video signal processing system of the television shown in Fig. 1, when an international language of a specific channel is performed with respect to the tuner 10, the tuner 10 is tuned to the channel to be tuned and broadcast video. A signal is outputted, and the broadcast video signal is subjected to IF conversion processing by a specific IF signal in the video IF processing module 12, and the video IF signal is R / G / It is reproduced as a B signal and reproduced on the CRT apparatus 16.

Here, in order to reproduce the image on the CRT device 16, the synchronization signal processing unit 20 separates the horizontal / vertical synchronization signal from the image signal processed by the image processing unit 14, and the separated horizontal / vertical synchronization unit. As the signal is applied to the vertical / horizontal deflection portions 22 and 24, the vertical / horizontal deflection portions 22 and 24 give a horizontal / vertical direction to the CRT device 16 based on the horizontal / vertical synchronization signal. Since a deflection signal is generated and applied to the CRT device 16, the image screen is reproduced in a stable state on the CRT device 16.

In order to compensate for the case where the broadcast signal of the channel tuned by the tuner 10 is at the weak level, the AGC 18 receives the level of the video signal processed by the image processor 14 to be a weak level signal. In this case, in order to increase the overall gain, the 'RF AGC' voltage is increased to the tuner 10 and the 'IF AGC' voltage is gradually applied to the image IF processing module 12 to perform the broadcasting. Compensation for the weak level of the signal is made.

However, in the case of a broadcast signal transmitted from a broadcasting station, when the electric field is weakened due to the mixing of noise components or obstacles during the transmission, the horizontal / vertical synchronization signal becomes unstable, and accordingly, the synchronization signal processing unit 20 accurately corrects the synchronization signal. Separation processing becomes difficult and synchronization of the video signal on the CRT apparatus 16 is not performed correctly.

In this case, the vertical and horizontal deflections of the CRT apparatus 16 in the vertical / horizontal deflection portions 22 and 24 are not executed at the correct timing, so that the screen displayed on the CRT apparatus 16 is shaken or The scrolling phenomenon occurs, and there is a disadvantage in that the visual perception of the image signal reproduced on the CRT apparatus 16 is deteriorated.

The present invention has been made in view of the above circumstances, and when the synchronization signal level of the broadcast video signal is weakened, the video screen displayed on the CRT apparatus by oscillating a standard pseudo-synchronization signal and synthesizing it into an image IF signal for post-processing It is an object of the present invention to provide an image synchronization stabilization apparatus for a television to be stabilized.

In order to achieve the above object, according to a preferred example of the present invention, the IF processing video IF signal of the video / audio signal of the channel tuned by the tuner is reproduced by the image processing means to be reproduced on the CRT apparatus, A television having an AGC controlling the gain of the tuner based on the level of a video signal and a synchronizing signal processing means for performing synchronizing signal processing for vertical / horizontal deflection for the CRT apparatus, wherein the gain control from the AGC means If the weak level of the video signal is determined based on the signal AGC voltage, the control means for switching output control of the composite video IF signal including the pseudo synchronous signal, and is activated under the control of the control means to oscillate the pseudo synchronous signal. Pseudo synchronous signal oscillation means, synchronous signal clamp circuit means for clamping a synchronous signal in the image IF signal, and the synchronous synchronous signal and the synchronous signal Signal synthesizing means for synthesizing the video IF signal clamped by the call, and interposed between the synchronizing signal processing means and the signal synthesizing means, under the control of the control means, of the synchronizing signal of the synchronizing signal processing means and the signal synthesizing means. There is provided a video synchronous stabilization apparatus for a television, further comprising switching means for selectively switching and outputting a composite video IF signal to the image processing means.

According to the present invention of the above configuration, the control means detects the level of the AGC voltage applied to the tuner from the image processing means, and if the level of the AGC voltage is higher than or equal to a predetermined value, the pseudo-synchronous signal oscillated by the pseudo-synchronization signal oscillating means. By synthesizing the video IF signal and applying it to the video means through the switching means, post-processing of the stabilized video signal is performed in the video processing means, so that the video screen is reproduced in a stable state in the CRT apparatus.

1 is a diagram schematically illustrating a video signal processing system of a general television;

2 is a block diagram showing an image synchronization stabilization apparatus for a television according to a preferred embodiment of the present invention;

FIG. 3 is a flowchart illustrating the operation of the apparatus for synchronizing the image synchronization of a television according to a preferred embodiment of the present invention shown in FIG. 2.

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

10: tuner, 12: image IF processing module,

14: image processing unit, 16: CRT device,

18: AGC, 20: synchronization signal processing unit,

22: vertical deflection portion, 24: horizontal deflection portion,

26: control unit, 28: pseudo synchronous signal oscillation unit,

30: synchronization signal clamp circuit portion, 32: signal synthesis portion,

34: switching unit.

Hereinafter, preferred examples of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 is a block diagram illustrating a video synchronization stabilization apparatus for a television according to a preferred embodiment of the present invention. Reference numeral 10 denotes a tuner in which the image IF processing module 12 is included in the tuner shown in FIG. 14, 18, and 20 represent an image processor, an AGC, and a synchronization signal processor shown in FIG.

Further, reference numeral 26 applies tuning data VT corresponding to a channel to be tuned by a remote control signal to the tuner 10 so that the channel is tuned, and the image processing unit 14 processes the channel. On the basis of the AGC voltage for the level of the video signal to be determined, the level of the video signal tuned by the tuner 10 is determined, and when the signal level is a weak signal, the video IF signal synthesized with the pseudo-synchronous signal is transmitted to the image processor 14. The control part which controls to be applied is shown.

28 denotes a pseudo synchronous signal oscillator controlled by the microcomputer 26 to oscillate a standard synchronous signal, and 30 denotes a synchronous signal in an image IF signal applied from the tuner 10 to the image processor 14. 32 denotes a synchronous signal clamp circuit portion for outputting by clamping only, and 32 denotes a synthesizing process of the pseudo synchronous signal oscillated by the pseudo synchronous signal oscillator 28 to the image IF signal of which the synchronous signal is clamped by the synchronous signal clamp circuit 30. A signal synthesizing section for reconstructing the composite video IF signal.

In addition, in FIG. 2, 34 indicates that the synchronization signal separated by the synchronization signal processing unit 20 is applied to the image processing unit 14 in response to the switching signal SW applied from the control unit 26 or the signal synthesis unit ( 32 shows a switching unit for switching and outputting the composite image IF signal reconstructed in the image processing unit 14.

Next, the image synchronization stabilization circuit of the television according to the present invention having the above-described configuration will be described in detail with reference to the flowchart of FIG.

First, when the control unit 26 applies the tuning data VT for tuning of a specific channel in response to a remote control signal to the tuner 10 while the corresponding television is powered on in step 40, From the tuner 10, a broadcast signal of a channel corresponding to the channel selection data VT is subjected to IF conversion processing and applied to the image processor 14.

Accordingly, the AGC 18 detects the level of the image signal applied to the image processor 14 and processes the AGC voltage to control the RF / IF gain of the tuner 10 to the tuner 10. The control unit 26 detects the level of the AGC voltage in step 42 and determines whether the video signal of the broadcast channel tuned by the tuner 10 in step 44 is a weak level signal.

As a result of the determination, when the image signal is at the normal level (NO in step 44), the controller 26 applies the switching control signal SW to the switching unit 34 to process the synchronization signal processing unit 20. The synchronization signal is applied to the image processor 14, so that the image processor 14 continues to reproduce the video IF signal based on the synchronization signal extracted from the image signal.

On the other hand, if the image signal of the channel tuned by the tuner 10 is a weak level signal as a result of the determination in step 44, the control unit 26 activates the pseudo synchronous signal oscillation unit 28 in step 48. By oscillating a predetermined synchronization signal to be applied to the signal synthesizing unit 32. In this state, the synchronous signal clamp circuit 30 clamps only the unstable synchronous signal portion of the video IF signal bypassed from the image processor 14 and applies it to the signal synthesis section 32 (step 50).

Then, the signal synthesizing unit 32 synthesizes the image synchronizing signal oscillated by the pseudo synchronizing signal oscillator 28 in step 52 by synthesizing the image IF signal of the synchronizing signal clamp circuit unit 30 to produce a composite image IF signal. Will be created. At this time, the control unit 26 controls the switching unit 34 to switch to the signal synthesizing unit 32 by applying a switching control signal SW to the switching unit 34, whereby the composite image IF signal is converted into the switching unit ( 34 is applied to the image processor 14.

Accordingly, the image processing unit 14 processes the composite image IF signal as an R / G / B signal and applies it to the CRT device 16 in step 54, and in this state, the image signal of the image processing unit 14 is applied. Since the synchronous signal processing unit 20 separates the horizontal / vertical synchronous signals and applies them to the vertical / horizontal deflection unit ('22' and '24' in FIG. 1), the image screen of the CRT apparatus 16 It will be displayed in a stable state.

Preferably, when the AGC voltage detected from the AGC 18 is restored to a normal level, the switching unit 34 is switched to the synchronization signal processing unit 20 under the control of the control unit 26 to the tuner 10. By this process, the image reproduction processing is performed by the synchronization signal separated and extracted from the video signal of the tuned channel.

As described above, according to the video synchronization stabilization apparatus of the present invention, when the weak level of the broadcast video signal is determined by the detection of the AGC voltage level, the video synchronization is performed by synthesizing the pseudo sync signal to the video IF signal. In this way, the screen synchronization of the image reproduced on the CRT device is stably performed. Accordingly, even when a broadcast signal with a weak signal level is received, scrolling or shaking of the image is prevented and reproduced on the CRT device. The visual perception of the image is further improved.

Claims (1)

The image processing unit 14 reproduces the IF converted video IF signal of the video / audio signal of the channel selected by the tuner 10 to be reproduced on the CRT device 16, based on the level of the video signal. In a television having an AGC 18 for controlling the gain of the tuner 10 and a synchronization signal processing unit for performing synchronization signal processing for vertical / horizontal deflection with respect to the CRT apparatus, A controller 26 for switching output control of the composite video IF signal including the pseudo synchronous signal when the weak level of the video signal is determined based on the gain control signal (AGC voltage) from the AGC 18; A pseudo synchronous signal oscillator 28 which is activated under the control of the controller 26 and oscillates a pseudo synchronous signal; A synchronous signal clamp circuit 30 for clamping a synchronous signal in the image IF signal; A signal synthesizer 32 for synthesizing the pseudo synchronous signal and the image IF signal clamped with the synchronous signal; Interposed between the synchronization signal processing unit 20 and the signal synthesis unit 32 and under the control of the control unit 26, the synchronization signal of the synchronization signal processing unit 20 and the composite image IF of the signal synthesis unit 32. And a switching unit (34) for selectively switching and outputting signals to the image processing unit (14).