KR19990042801A - Weak signal judgment device of video equipment - Google Patents

Abstract

The present invention relates to a weak signal determination device of a video device that determines whether or not a weak signal of a composite video signal input to a video device, the horizontal sync signal detection unit 110 for separating the horizontal sync signal from the input composite video signal; A vertical sync signal detector 120 separating a vertical sync signal from the input composite video signal; A first counter (130) for counting horizontal sync signals output from the horizontal sync signal detector (110); A second counter (140) for counting the vertical synchronization signal output from the vertical synchronization signal detector (120); When the count value of the horizontal sync signal counted for a first predetermined time is within a preset first range and the count value of the vertical sync signal counted for a second preset time is within a preset second range, The input composite video signal is determined to be a strong signal, and a count value of the horizontal sync signal counted for a first predetermined time is out of a preset first range, or the vertical sync signal counted for a second preset time. A microcomputer 150 for determining the input composite video signal as a weak signal when the count value of the value is outside the preset second range; When the microcomputer 150 determines that the input composite video signal is a weak signal, the microcomputer 150 includes an OSD unit 160 for blue-backing the video signal under the control of the microcomputer 150. do.

Description

Weak signal judgment device of video equipment

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a weak signal determination device for more accurately measuring the intensity of a video signal applied to performing a channel automatic tuning function in a video device.

The composite video signal used in televisions and video cassette recorders can be divided into a luminance signal representing the contrast of the photographed subject largely, a color signal representing the color of the subject, and a synchronization signal.

Here, the synchronizing signal has the same meaning as a signal used for synchronizing between a general transmitter and a receiver. In a television video signal, a horizontal synchronizing signal for determining that a horizontal scanning line starts and a vertical synchronizing for determining that a field starts It consists of a signal.

The synchronization signals in the video signals are used for other functions of the video device besides synchronizing the scanning lines. For example, a television or the like is provided with a channel automatic tuning function, and channel automatic tuning automatically stores only a broadcast channel among a plurality of receivable channels in the television. In order to perform the channel automatic tuning function, the intensity of the received video signal should be detected. Generally, the intensity of the video signal is determined based on the presence or absence of the horizontal sync signal, and the horizontal sync signal detected within a predetermined time is When more than a predetermined number, the channel is recognized as a broadcast channel.

That is, when it is determined whether the horizontal synchronization signal is present as in the channel automatic tuning function, the broadcast signal is affected by noise during the transmission process, and thus, when a predetermined number or more of the horizontal synchronization signals are detected within a predetermined time, the corresponding channel is broadcasted. Judging method was used. For example, in the conventional NTSC system, 15 to 64 horizontal synchronizing signals must be detected within 2 msec.

On the other hand, a video cassette recorder employs a blue back function that prevents noise from appearing on a television screen by using this synchronization signal detection method in reverse.

In detail, when the number of horizontal sync signals detected within 2 msec is 15 to 64 or more (for example, 14 or 65), a signal that is not received by the video signal currently input through the tuner (usually called a weak signal) is not received. It judges that it is, and drives the OSD (On Screen Display) in a video cassette recorder. The blue back signal output by the OSD driving is provided to the television screen, so that the user can watch the noiseless blue back screen.

However, the conventional weak signal determination method for determining whether to output such a blue back screen has a problem that the weak signal determination is relatively inaccurate since it only depends on the number of horizontal synchronization signals inputted within a predetermined time as described above.

Accordingly, the present invention provides a weak signal determination apparatus of a video device that determines whether the weak signal is determined by considering not only the number of horizontal sync signals included in the video signal but also the number of vertical sync signals. Has its purpose.

In accordance with an aspect of the present invention, there is provided a weak signal determining apparatus of a video device that determines whether or not a weak signal of a composite video signal input to a video device is provided. A signal detector; A vertical sync signal detector for separating a vertical sync signal from the input composite video signal; A first counter for counting a horizontal sync signal output from the horizontal sync signal detector; A second counter for counting a vertical synchronization signal output from the vertical synchronization signal detector; When the count value of the horizontal sync signal counted for a first predetermined time is within a preset first range and the count value of the vertical sync signal counted for a second preset time is within a preset second range, The input composite video signal is determined to be a strong signal, and a count value of the horizontal sync signal counted for a first predetermined time is out of a preset first range, or the vertical sync signal counted for a second preset time. A microcomputer that determines the input composite video signal as a weak signal when the count value of is outside the preset second range; In the micom, when the input composite video signal is determined to be a weak signal, the microcomputer may include an OSD unit configured to blue-back the video signal under the control of the microcomputer.

1 is a detailed configuration diagram showing a preferred embodiment of a weak signal determination device of a video device of the present invention;

Figure 2 is a detailed flowchart for explaining the operation of the weak signal determination device of the present invention.

<Description of Symbols for Main Parts of Drawings>

110; A horizontal synchronization signal detector 120; Vertical sync signal detector

130; First counter 140; 2nd counter

150; Micom 160; OSD

170; Image signal processing unit 180; monitor

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

1 is a detailed block diagram showing an embodiment of a weak signal determination apparatus of the present invention.

In FIG. 1, a weak signal determining apparatus of a video device includes a horizontal sync signal detector 110, a vertical sync signal detector 120, a first counter 130, a second counter 140, a microcomputer 150, and an OSD unit ( 160, the image signal processor 170, and the monitor 180.

Here, the horizontal sync signal detector 110 separates the horizontal sync signal from the input composite video signal, and the vertical sync signal detector 120 detects the vertical sync signal from the input composite video signal.

In addition, the first counter 130 counts the horizontal sync signal output from the horizontal sync signal detector 110, and the second counter 140 counts the vertical sync signal output from the vertical sync signal detector 120.

The microcomputer 150 determines whether the video signal is a weak signal based on the count values provided from the first and second counters 130, and the video signal processor 170 processes the video signal from which the synchronization signal is separated. It serves to provide the OSD unit 160. When the video signal is determined to be a weak signal, the OSD unit 160 provides a blue back signal to the monitor 180 under the control of the microcomputer 150.

2 is a detailed flowchart illustrating an operation process of the weak signal determining apparatus of the present invention. Therefore, the operation of the weak signal determining apparatus of the present invention will be described in detail with reference to FIGS. 1 and 2.

First, the composite video signal is input to the horizontal sync signal detector 110, and the horizontal sync signal detector 110 separates only the horizontal sync signal included in the input composite video signal (S1) and provides it to the first counter 130. do.

Meanwhile, the vertical synchronizing signal detector 120 receives an image signal from which the horizontal synchronizing signal is separated from the horizontal synchronizing signal detection unit 110, separates the vertical synchronizing signal (S2), and then outputs the image signal from which the synchronizing signal is separated. The image signal processor 170 is provided, and the vertical synchronization signal is provided to the second counter 140.

The first counter 130 counts the horizontal synchronization signal that is enabled and input under the control of the microcomputer 150 (S3), and provides the microcomputer 150 to the microcomputer 150. The vertical synchronization signal, which is enabled and input by the control of 150, is counted (S4) and then provided to the microcomputer 150.

The microcomputer 150 receives the count value of the horizontal sync signal from the first counter 130 and determines the weak signal of the video signal after receiving the count value of the vertical sync signal from the second counter 140.

That is, if the number of horizontal sync signals detected within a predetermined time is included in the preset range, for example, if the number of horizontal sync signals detected within 2 msec is included in 15 to 64 (S5) Based on the count value of the vertical synchronization signal input from the two counter 140, it is determined whether the weak signal.

However, if the number of horizontal synchronization signals detected within 2 msec is out of 15 to 64, it is determined as a weak signal immediately (S8) to operate the OSD unit 160. The OSD unit 160 provides the blue back signal to the monitor 180 under the control of the microcomputer 150 (S9).

On the other hand, if the number of horizontal synchronization signals detected within 2 msec is included in 15 to 64 (S5), the microcomputer 150 detects within a predetermined time based on the count value of the vertical synchronization signal input from the second counter 140. It is determined whether the number of vertical synchronization signals to be included is within a predetermined range (S6).

As a result of the determination, if the number of vertical synchronization signals detected within a predetermined time is not included in the preset range, the microcomputer 150 determines the input video signal as a weak signal (S8) to operate the OSD unit 160, Accordingly, the OSD unit 160 provides the blue back signal to the monitor 180 under the control of the microcomputer 150 (S9).

However, if the number of vertical synchronization signals detected within a predetermined time is within the preset range, the microcomputer 150 determines the input video signal as a strong signal (S7).

As described above, the present invention determines the weak signal by considering not only the number of horizontal sync signals included in the video signal but also the number of vertical sync signals, thereby making it possible to more accurately determine the weak signal.

Claims (1)

In the weak signal determination device of the video device to determine whether the weak signal of the composite video signal input to the video device: A horizontal sync signal detector 110 for separating a horizontal sync signal from the input composite video signal; A vertical sync signal detector 120 separating a vertical sync signal from the input composite video signal; A first counter (130) for counting horizontal sync signals output from the horizontal sync signal detector (110); A second counter (140) for counting the vertical synchronization signal output from the vertical synchronization signal detector (120); When the count value of the horizontal sync signal counted for a first predetermined time is within a preset first range and the count value of the vertical sync signal counted for a second preset time is within a preset second range, The input composite video signal is determined to be a strong signal, and a count value of the horizontal sync signal counted for a first predetermined time is out of a preset first range, or the vertical sync signal counted for a second preset time. A microcomputer 150 for determining the input composite video signal as a weak signal when the count value of the second signal is outside the preset second range; If the microcomputer 150 determines the input composite video signal as a weak signal, the microcomputer 150 includes an OSD unit 160 for blue-backing the video signal under control of the microcomputer 150. Signal judgment device.