JP3157785B2 - Video signal processing circuit and sync separation system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit used for separating and extracting a synchronizing signal in a video display device or the like, and more particularly to a circuit suitable for processing a color difference signal including a component video signal and a conventional video signal. The present invention relates to a video signal processing circuit and a synchronization separation system.

[0002]

2. Description of the Related Art In a video display device or the like, video signals such as an RGB signal and a conventional video signal are provided, and predetermined processing corresponding to each video signal is performed to provide video display. For this reason, there are many video display devices equipped with an input system for various video signals such as an RGB signal and a conventional video signal, and appropriately processing any of the video signals according to each of them.

In recent years, DVD (Digital Video)
Disc) and other new media are spreading.
Processing of video signals such as VD has also been required of video display devices and the like.

[0004] By the way, horizontal and vertical synchronizing signals are required for processing of video signals, and when a synchronizing signal is separated and extracted from a video signal, processing corresponding to various video signals is required.

For example, in the case of a three-wire RGB signal,
A synchronization signal is superimposed on the G signal, and the synchronization signal is separated and extracted from the G signal on which the synchronization signal is superimposed, that is, the G sync signal.

In the case of a conventional video signal, a synchronizing signal is separated and extracted from a Y / C separated luminance signal. In addition, conventional video signals include video tape recorders (VTRs).
In addition, a non-standard signal from a video cassette recorder (VCR), a copy guard signal for preventing illegal copying, and the like are mixed in a form confusing with the synchronization signal. For this reason,
An automatic frequency control circuit (AFC circuit) is provided in this type of video signal sync separation circuit in order to avoid adverse effects due to a copy guard signal or the like. Further, in the case of a conventional video signal, in a video signal such as a movie, a closed caption signal for displaying characters in synchronization with the video may be included in association with the synchronization signal,
A closed caption processing circuit for decoding the closed caption signal is provided in association with the synchronization separation circuit.

[0007] A video signal of a DVD or the like is a color difference signal called a component video signal, and may include a copy guard signal, a closed caption signal, and the like.

Therefore, RGB signals, conventional video signals,
In general, a video display device or the like that processes a component video signal or the like includes a terminal for the G signal of the component video signal and the RGB signal, and includes an automatic frequency control circuit substantially similar to that for a conventional video signal. The synchronization signal is separated and extracted using the synchronization separation circuit. In this case, the conventional video signal terminal is provided separately from the above-described component video signal and G signal common terminal.

[0009]

As described above, RG
In a video display device or the like that processes a B signal, a conventional video signal, a component video signal, and the like, a shared terminal for processing the component video signal and the RGB signal is provided separately from a terminal for the conventional video signal, In general, the synchronization signal is separated and extracted by using a synchronization separation circuit including an automatic frequency control circuit substantially similar to that for a conventional video signal.

However, the use of such a configuration causes the following problem. The first problem is that it is necessary to use a sync separation circuit having an automatic frequency control (AFC) function in order to cope with a copy guard signal of a DVD component video signal. This sync separation circuit is the same as the frequency separation circuit in the conventional video signal processing circuit, but it is newly added, which increases the manufacturing cost and the occupied space on the circuit board.

The second problem is that since the Y signal of the component video signal and the G signal of the RGB signal (G sync signal) are input from the same shared terminal, it is necessary to switch the sync separation circuit according to the input signal. is there.

The present invention has been made in view of the above circumstances, and can automatically process a copy guard signal and the like in response to an RGB signal, a conventional video signal, and a component video signal automatically. It is a first object of the present invention to provide a video signal processing circuit which has a simple configuration and is excellent both in cost and space occupied by a circuit board.

Further, the present invention can automatically cope with an RGB signal, a conventional video signal and a component video signal, separate a synchronization signal, appropriately process a copy guard signal, and the like, and have a simple configuration. It is a second object of the present invention to provide a synchronous separation system which is excellent both in cost and space occupied by a circuit board.

[0014]

In order to achieve the above object, a video signal processing circuit according to a first aspect of the present invention comprises an RGB signal processing circuit which does not include an automatic frequency control function for separating and extracting a synchronization signal from an input signal. A first sync separation circuit for
A second synchronous separation circuit for conventional video signal processing that includes an automatic frequency control function and separates and extracts a synchronization signal from an input signal; and, based on a frequency component of the input signal, converts a component video signal based on the presence of a predetermined frequency component. When the input signal is determined to be a component video signal by the frequency discriminating circuit to discriminate and the frequency discriminating circuit,
Selection switching means for selecting the second sync separation circuit and, when it is determined that the input signal is not a component video signal, selecting and using the first sync separation circuit;
A signal processing circuit for processing a video signal using a synchronization signal extracted by the first and second synchronization separation circuits selected by the selection switching means.

[0015] The frequency discrimination circuit may include means for discriminating a component video signal by detecting a horizontal frequency component in the input signal.

[0016] The apparatus may further include input selection means for selectively supplying the conventional video signal input and the component video signal input to the second sync separation circuit.

[0017] The second sync separation circuit may further include a closed caption processing circuit for decoding a closed caption signal.

The input signal includes a G signal including a synchronizing signal among the RGB signals, and the selecting means determines that the input signal is a component video signal when the frequency discriminating circuit determines that the input signal is a component video signal. When the second sync separation circuit is selected and the input signal is determined to be the G signal, the first sync separation circuit is selected and used.

In the video signal processing circuit according to the present invention, a first synchronizing separation means for RGB signal processing which does not include an automatic frequency control function for separating and extracting a synchronizing signal from an input signal, in particular, a G sync signal; Including a control function, comprising a second synchronization separation means for conventional video signal processing to separate and extract the synchronization signal from the input signal including the luminance signal, to discriminate the component video signal based on the frequency component of the input signal, When it is determined that the input signal is a component video signal, the output of the second sync separation means is selected. When it is determined that the input signal is not a component video signal, the first sync signal is output. The output of the separating means is selected and used. Therefore, it is possible to automatically cope with RGB signals, conventional video signals and component video signals, appropriately process copy guard signals and the like, and has a simple configuration, and is simple in terms of cost and space occupied by a circuit board. It is advantageous.

Further, a synchronization separation system according to a second aspect of the present invention is a system for RGB signal processing which does not include an automatic frequency control function for separating and extracting a synchronization signal from a G signal including a synchronization signal among the RGB signals. A second sync separation circuit for conventional video signal processing including a sync separation circuit, an automatic frequency control function, and separating and extracting a sync signal from a video signal including a luminance signal; A frequency discriminating circuit for discriminating between a component video signal and a G signal including a synchronization signal based on the presence of a predetermined frequency component; and, when the frequency discriminating circuit determines that the input signal is a component video signal, the second And if it is determined that the input signal is a G signal including the synchronization signal, the first synchronization separation circuit is selected and used. Comprising a selection switch means.

The selection switching means may include means for selecting and outputting one output of the first and second synchronization separation means.

[0022] The frequency discriminating means may include means for discriminating a component video signal by detecting a horizontal frequency component in the input signal.

[0023] The apparatus may further include input selection means for selectively supplying the conventional video signal input and the component video signal to the second synchronization separation means.

In the synchronization separation system of the present invention, G
A first synchronization separation unit for RGB signal processing that does not include an automatic frequency control function for separating and extracting a synchronization signal from a sync input signal, and a synchronization signal that includes an automatic frequency control function and separates and extracts a synchronization signal from a luminance signal. A conventional video signal processing second sync separation unit, and discriminates the component video signal based on the frequency component of the input signal. If the input signal is determined to be the component video signal, the second 2 is selected, and if it is determined that the input signal is not a component video signal, the output of the first sync separation is selected and used.
Therefore, it is possible to automatically cope with the RGB signal, the conventional video signal and the component video signal, appropriately process the copy guard signal and the like, and accurately separate the synchronization signal. This is also advantageous in terms of the space occupied by the circuit board.

[0025]

Embodiments of the present invention will be described below with reference to the drawings. An embodiment of a video signal processing circuit according to the present invention will be described with reference to FIGS.

FIG. 1 shows a configuration of a sync separation section which is a main part of a video signal processing circuit according to an embodiment of the present invention.

The video signal processing circuit shown in FIG. 1 has a first input terminal T1, a second input terminal T2, a frequency discriminating circuit 1,
First sync separation circuit 2, first changeover switch 3, second sync separation circuit 4, microcomputer (microcomputer)
5, a color difference-RGB conversion circuit 6, a control circuit 7, and a second changeover switch 8.

The first input terminal T1 is a terminal commonly used for inputting a component video signal such as a DVD and inputting a G signal including a synchronizing signal among RGB signals, that is, a so-called G sync signal. Note that both the component video signal and the RGB signal of the DVD are of a three-wire type and are supplied at three terminals together with other two terminals not shown. However, the Y signal and the G signal (G sync signal) of the component video signal are commonly supplied to the first input terminal T1 for synchronization separation. The second input terminal T2 is a terminal for inputting a conventional video signal.

The frequency discriminating circuit 1 has a first input terminal T1
To determine (discriminate) the frequency of the signal input to
When a large amount of z components are contained, an H level signal is output by discriminating the component video signal,
In other cases, the circuit outputs an L-level signal. That is, for a component video signal such as a DVD,
Almost 15kHz by horizontal synchronization frequency (horizontal synchronization signal)
Contains a lot of ingredients. Therefore, the frequency discriminating circuit 1 discriminates the component video signal from other signals based on the presence or absence of the signal component of 15 kHz. Based on the discrimination result, the second changeover switch 8 is switched and controlled.

The first sync separation circuit 2 is a sync separation circuit for RGB signals (that is, a sync separation circuit provided in a conventional RGB circuit), and a sync signal superimposed on a G signal of the RGB signals. Separate signals. This synchronization separation circuit 2
Since it is for RGB signals, it does not include an automatic frequency control (AFC) function. This is because the RGB signal does not include a signal that is easily confused with a synchronization signal, such as a pseudo synchronization signal for copy guard.

The first changeover switch 3 is operated by a microcomputer 5 for controlling the video signal processing circuit, and converts the video signal supplied to the second signal input terminal T2 by a Y / C separation circuit (not shown). The luminance signal obtained by the Y / C separation and the signal input to the first input terminal T1 are selectively switched and supplied to the second synchronization separation circuit 4.

The second sync separation circuit 4 is a sync separation circuit for a video signal including an automatic frequency control function (ie, a sync separation circuit provided in a conventional video circuit), and is a pseudo-separation circuit for copy guard. Even if a signal such as a synchronization signal that is easily confused with the synchronization signal is included, the synchronization signal is correctly separated and used for decoding the video signal.

The second changeover switch 8 is switched according to the judgment result of the frequency judgment circuit 1, and the first input terminal T
It is determined that the signal input from 1 is a component video signal, that is, a signal containing a large amount of a 15 kHz component, and when an H level signal is output, the second synchronization separation for the video signal is performed. The synchronous output of the circuit 4 is selected. On the other hand, when the input signal of the first input terminal T1 is determined to be a signal other than the component video signal and is at the L level, the synchronization output of the first synchronization separation circuit 2 for the RGB circuit is selected. The synchronization signal selected and output by the second changeover switch 8 is supplied to a circuit portion including the color difference-RGB conversion circuit 6, the control circuit 7, and the like, and used for display control as appropriate.

The color difference / RGB conversion circuit 6 supplies a three-line color difference signal (Y, Pb, Pr / Y,
Cb, Cr) and the like, and further, a synchronization signal selected by the second changeover switch 8 is supplied. The control circuit 7 uses the synchronization signal selected by the second changeover switch 8 to control video signal processing such as display of a video by RGB output from the color difference-RGB conversion circuit 6.

FIG. 2 shows a detailed configuration of the frequency discriminating circuit 1. The frequency discriminating circuit 1 includes a synchronization separating circuit 9,
It has a frequency / voltage conversion circuit 10 and a window comparator 11.

The sync separation circuit 9 is a circuit for separating and extracting a sync signal from the component video signal supplied to the first input terminal T1. Frequency / voltage conversion circuit 10
Converts the frequency of the synchronization signal separated and extracted by the synchronization separation circuit 9 into a voltage. Window comparator 11
Detects a component video signal based on a voltage component corresponding to a frequency of about 15 kHz based on a voltage signal output from the frequency / voltage conversion circuit 10, and outputs a determination signal according to a determination result.

The window comparator 11 includes voltage comparators CP1, CP2, diodes D1, D2, resistors R1,
It is composed of R2, R3, R4 and R5.

The first voltage comparator CP1 comprises resistors R1 and R
2. The output voltage of the frequency / voltage conversion circuit 10 is subtracted from the first predetermined voltage obtained by dividing the power supply voltage in 2, and only when the voltage output from the frequency / voltage conversion circuit 10 is lower than the first predetermined voltage "H (high level)" is output. The second voltage comparator CP2 subtracts a second predetermined voltage obtained by dividing the power supply voltage by the resistors R3 and R4 from the output voltage of the frequency / voltage conversion circuit 10, and the output voltage of the frequency / voltage conversion circuit 10 "H" is output only when the voltage is higher than the second predetermined voltage.

The diodes D1 and D2 and the resistor R5 are connected to the output of the first voltage comparator CP1 and the second voltage comparator CP2.
AND logic with the output of the first voltage comparator CP1
Is “H” when both the output of the second voltage comparator CP2 and the output of the second voltage comparator CP2 are “H”, and one or both of them are “L”.
(Low level) ". In other words, the window comparator 11 outputs a voltage from the frequency / voltage conversion circuit 10 between the first predetermined voltage and the second predetermined voltage. Only in this case, the output is set to “H”.

Therefore, the first predetermined voltage and the second predetermined voltage are respectively converted into values corresponding to the lower limit value and the upper limit value of the voltage obtained by frequency-voltage conversion of the signal of the horizontal frequency component near 15 kHz. With this setting, an H-level signal can be output only when the horizontal frequency component of the component video signal is detected.

Next, the operation of the video signal processing circuit shown in FIGS. 1 and 2 will be described. First changeover switch 3
Is usually a second input T for a conventional video signal input.
2 is connected to the second synchronization separation circuit 4. In this state, when a video signal, that is, a Y signal (luminance signal) obtained by Y / C separation of the video signal is input to the second input terminal T2, the Y signal is subjected to the second synchronization separation. The synchronization signal is supplied to the circuit 4, and the second synchronization separation circuit 4 separates the synchronization signal from the luminance signal and supplies the synchronization signal to the second switch 8.

In this state, since no component video signal is supplied to the first input terminal T1, the frequency discriminating circuit 1 outputs an L-level signal, and the second changeover switch 8 sets the second video synchronous The synchronization signal output from the separation circuit 4 is selected and output. A circuit group (not shown) performs a display operation using the synchronization signal. At this time, even if the video signal includes a pseudo sync signal such as a copy guard signal, the second sync separation circuit 4 is a sync separation circuit for a video circuit and includes an automatic frequency adjustment circuit. ,
Synchronous separation can be performed appropriately.

Here, the microcomputer 5 instructs the first changeover switch 3 to select the first input terminal T1 according to the user's switching operation (switching from a video signal to an RGB signal or a component video signal) or the like. Suppose you did. In accordance with an instruction from the microcomputer 5, the first switch 3 inputs the signal supplied to the first input terminal T1 to both the first and second synchronization separation circuits 2 and 4.

Here, when a component video signal is supplied to the first input terminal T1, the frequency discriminating circuit 1 discriminates that a signal near 15 kHz has been inputted, and recognizes the input signal as a component video signal. To output an H level signal. With this signal, the second changeover switch 8 selects the output of the second synchronization separation circuit 4.

On the other hand, the second sync separation circuit 4 separates and outputs a sync signal in the component video signal.
Since the second synchronization separation circuit 4 also has an automatic frequency control function, it can cope with a copy guard signal or the like in a DVD. That is, even when the component video signal includes a copy guard signal or the like, the synchronization separation can be accurately performed. The color difference-RGB conversion circuit 6 converts the component video signal into an RGB signal using the synchronization signal, and outputs the RGB signal. Control circuit 7
Displays an image using the supplied synchronization signal and the RGB output. The separated synchronization signal is supplied to a circuit group (not shown) as necessary.

On the other hand, when the signal supplied to the first input terminal T1 is a G signal of an RGB signal, a signal near 15 kHz is not included so much.
Recognizes that the input signal is a signal other than the component video signal and outputs an L-level signal. With this signal, the second switch 8 switches the first synchronization separation circuit 2
Select the output of The first synchronization separation circuit 2 separates and outputs a synchronization signal in the G signal. First sync separation circuit 2
Does not have an automatic frequency control function, but since the G signal does not include a copy guard signal or the like, no problem occurs.

Further, a conventional video signal circuit, for example, the second sync separation circuit 4 is provided with a closed caption processing circuit for displaying character information synchronized with the video, and is used when a component video signal of a DVD is input. Also,
The closed caption processing circuit can be used without newly adding a closed caption processing circuit.

As described above, first, it is necessary to add a new automatic frequency control circuit for the synchronization separation by utilizing the synchronization separation circuit of the conventional video circuit for the synchronization separation of the component video signal. In addition, since it is also a countermeasure for the synchronization separation of the DVD copy guard signal, the cost is excellent and the space occupied by the circuit board is also excellent.

Further, when a conventional video processing circuit has a closed caption processing circuit, it is not necessary to separately add this circuit.

Second, the frequency discriminating circuit 1 discriminates the horizontal frequency of the input signal, thereby automatically discriminating the component video signal from the other signals, and performing the optimum synchronizing signal processing.

Note that the present invention is not limited to the above embodiment, and various modifications and applications are possible. For example, the first
May be supplied with an HD (High Definition; so-called high-vision) signal to the input terminal T1. The synchronization signal of the HD color difference signal can be separated by a synchronization separation circuit 2 of a conventional RGB circuit, and the frequency of the synchronization signal can be determined by a frequency determination circuit 1. That is, in a state where the HD signal is supplied to the first input terminal T1, the frequency discriminating circuit 1 outputs an L-level signal, whereby the second switch SW2 outputs the signal of the second synchronization separating circuit 2. Select the synchronization signal to be output.

[0052]

As described above, according to the present invention,
It automatically responds to RGB signals, conventional video signals and component video signals, can appropriately process copy guard signals, etc., and has a simple configuration, and is excellent in cost and space occupied by circuit boards. An image signal processing circuit and a sync separation system can be provided.

[Brief description of the drawings]

FIG. 1 is a block diagram schematically showing a configuration of a main part of a video signal processing circuit according to an embodiment of the present invention.

FIG. 2 is a circuit configuration diagram schematically showing a detailed configuration of a frequency discrimination circuit used in the video signal processing circuit of FIG. 1;

[Explanation of symbols]

Reference Signs List 1 frequency discrimination circuit (component video signal discrimination circuit) 2 first synchronization separation circuit (for RGB signal) 3 first changeover switch 4 second synchronization separation circuit (for conventional video signal) 5 microcomputer (microcomputer) Reference Signs List 6 color difference-RGB signal discrimination circuit 7 control circuit 8 second changeover switch 9 synchronization separation circuit 10 frequency / voltage conversion circuit 11 frequency discrimination circuit

Claims (9)

(57) [Claims] A first synchronizing separation circuit for RGB signal processing not including an automatic frequency control function for separating and extracting a synchronization signal from an input signal; and an automatic frequency control function for separating and extracting a synchronization signal from the input signal. A second synchronization separation circuit for processing a conventional video signal; a frequency discrimination circuit for discriminating a component video signal based on a frequency component of the input signal based on the presence of a predetermined frequency component; When it is determined that the input signal is a video signal, the second sync separation circuit is selected. When it is determined that the input signal is not a component video signal, the first sync separation circuit is selected. A video signal using a selection switching unit to be used, and a synchronization signal extracted by the first and second synchronization separation circuits selected by the selection switching unit. And a signal processing circuit for processing. 2. The video signal processing circuit according to claim 1, wherein said frequency discriminating circuit includes means for discriminating a component video signal by detecting a horizontal frequency component in said input signal. 3. An apparatus according to claim 1, further comprising input selection means for selectively supplying said conventional video signal input and said component video signal input to said second sync separation circuit. The video signal processing circuit according to the above. 4. The video signal processing circuit according to claim 1, wherein said second synchronization separation circuit includes a closed caption processing circuit for decoding a closed caption signal. . 5. The input signal includes a G signal including a synchronizing signal among the RGB signals, and the selection unit determines that the input signal is a component video signal when the frequency discrimination circuit determines that the input signal is a component video signal. 2. The method according to claim 1, wherein the second synchronization separation circuit is selected, and when the input signal is determined to be the G signal, the first synchronization separation circuit is selected and used. The video signal processing circuit according to any one of claims 4 to 4. 6. A first synchronization separation circuit for RGB signal processing not including an automatic frequency control function for separating and extracting a synchronization signal from a G signal including a synchronization signal among RGB signals, and an automatic frequency control function, A second sync separation circuit for processing a conventional video signal that separates and extracts a sync signal from a video signal including a luminance signal; A frequency discriminating circuit for discriminating the G signal including the signal, and when the input signal is determined to be a component video signal by the frequency discriminating circuit, the second sync separation circuit is selected, and the input signal is G including signal
And a selection switching means for selecting and using the first synchronization separation circuit when the signal is determined to be a signal. 7. The synchronization separation system according to claim 6, wherein said selection switching means includes means for selecting and outputting one of the outputs of said first and second synchronization separation means. 8. The synchronization separation system according to claim 6, wherein said frequency discriminating means includes means for discriminating a component video signal by detecting a horizontal frequency component in said input signal. 9. The apparatus according to claim 6, further comprising input selection means for selectively supplying said conventional video signal and component video signal to said second synchronization separation means.
9. The synchronization separation system according to any one of claims 8 to 8.