JPH09322187A - Malfunction preventive circuit for secam color signal processing circuit for video equipment in common use of various television systems - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a SECAM color signal processing circuit from mis-deciding an input signal to be a SECAM input signal and malfunctioning when the input signal is an NTSC signal or a PAL signal. SOLUTION: The video equipment in common use for various television systems receiving two kinds or over of composite video signals including a SECAM system among the NTSC, PAL and SECAM systems is provided with a vertical synchronizing frequency discrimination circuit 33, a color burst discrimination circuit 36, a SECAM color signal processing circuit 38, and a color standard discrimination and control circuit 42. When the input signal is the NTSC signal, the vertical synchronizing frequency discrimination circuit 33 discriminates it that the vertical synchronizing signal frequency is 60Hz, and when the input signal is the PAL signal, the color burst discrimination circuit 36 discriminates the presence of a color burst, then the color standard discrimination and control circuit 42 outputs a forced SECAM signal to the SECAM color signal processing circuit 38 based on the discrimination signals and the SECAM color signal processing is stopped.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to NTSC, PA.
A composite video signal of a SECAM system in a video device compatible with various television systems (hereinafter simply referred to as a video device compatible with various television systems) that uses as input signals two or more composite video signals including SECAM systems of L and SECAM systems. The present invention relates to a malfunction prevention circuit of a SECAM color signal processing circuit that performs color signal processing (hereinafter, simply referred to as SECAM signal) (for example, color demodulation processing). NTS here
The C system represents a color television (hereinafter referred to as color TV) standard system used in Japan and the United States,
The PAL system is the color T used in Western Europe.
5 shows the V standard system, and the SECAM system represents the color TV standard system used in France, Russia, etc., and FIG. 5 shows the determination results of the vertical sync signal frequency, the color subcarrier frequency, and the color burst (color sync signal). There are differences as shown in.

[0002]

2. Description of the Related Art In various television system / video equipment, when a dual-purpose device (for example, a comb filter or a clock generator) set to a mode corresponding to the system of an input signal by a switching control signal from the outside is used, The mode of the dual-purpose device was manually switched according to the input signal system.

For example, NTSC, PAL, and SECAM provided with dual-purpose devices such as a comb filter and a clock generator in the preceding stage of the luminance signal processing circuit and the color signal processing circuit.
In the video device compatible with the system, the comb filter is switched to the through mode in which the Y signal is output as it is when the input signal is the SECAM signal, and the input signal is the composite video signal of the NTSC system or the PAL system (hereinafter referred to as NTSC / PAL).
Signal), separates the luminance signal and the color signal into Y
When the input signal is a composite video signal of NTSC system (hereinafter, referred to as NTSC signal), the clock generator is switched to the comb mode of the output and the C output, and the clock generator outputs the NTSC signal.
The mode is switched to a mode that outputs a clock that is four times (4Fsc) the color subcarrier frequency Fsc (= 3.58MHz) of the system, and the input signal is a PAL system composite video signal (hereinafter P
In the case of the AL signal), the mode was switched to a mode for outputting a clock that is four times (4Fsc) the color subcarrier frequency Fsc (= 4.43 MHz) of the PAL system.

[0004]

However, when the dual-purpose device such as the mode-switching comb filter or the clock generator described above is used in the video equipment for dual-purpose NTSC, PAL, and SECAM systems, the input signal is an NTSC signal or a PAL signal. However, there is a problem that the SECAM color signal processing circuit may determine that the SECAM signal is input and malfunction.

The present invention has been made in view of the above-mentioned points, and in various television system / combined video equipment having two or more kinds of composite video signals including the SECAM system as input signals, the input signals are NTSC signals or PAL signals. When S
It is an object of the present invention to prevent the ECAM color signal processing circuit from judging that the SECAM signal is input and malfunctioning. Further, if necessary, it is possible to automatically perform mode switching of a dual-purpose device (for example, a comb filter or a clock generator) set to a mode corresponding to the input signal system by a switching control signal from the outside. That is the purpose.

[0006]

SEC according to claim 1,
An invention relating to a malfunction prevention circuit of an AM color signal processing circuit is provided in a video device for various television systems and a vertical synchronization frequency determining circuit for determining a frequency (vertical scanning frequency) of a vertical synchronization signal in an input signal, and an input signal. A color burst discriminating circuit for discriminating whether or not there is a color burst,
A SECAM color signal processing circuit that performs color signal processing in a composite video signal of the SECAM system and that is stopped by an external forced SECAM signal, and a discrimination signal of a vertical synchronization frequency discrimination circuit and a color burst discrimination circuit. Based on the above, a color standard discrimination / control circuit for outputting a forced SECAM signal to the SECAM color signal processing circuit is provided.

When the input signal is an NTSC signal, the vertical sync frequency discrimination circuit determines that the frequency of the vertical sync signal is 60 Hz.
When the input signal is a PAL signal, the color burst determination circuit determines that there is a color burst. Therefore, based on these determination signals, the color standard determination / control circuit forces the SECAM color signal processing circuit. The SECAM signal is output and the SECAM color signal processing is stopped. Therefore, the input signal is NTSC signal or PAL.
In case of signal, SECAM color signal processing circuit
It is possible to prevent a malfunction by determining that the CAM signal is input.

According to a second aspect of the present invention, in the first aspect of the present invention, the vertical synchronizing frequency discriminating circuit and the color burst discriminating circuit are provided with a circuit for processing a luminance signal in the input signal, and an NTS.
When the circuit for processing the color signal in the C / PAL signal is integrally formed on the main chip and the SECAM color signal processing circuit is integrally formed on the sub chip, the number of required components can be reduced. it can.

According to a third aspect of the present invention, in the first aspect of the present invention, a dual-purpose device (for example, a comb filter or a clock generator) which is set to a mode corresponding to the input signal system by an external switching control signal, and an input A color subcarrier frequency discriminating circuit for discriminating the color subcarrier frequency of the color signal in the signal and a SECAM discriminating circuit for discriminating whether or not the SECAM signal is present in the input signal are added, and a color standard discrimination / control circuit is also added. In addition, a function of outputting a mode switching control signal to a dual-purpose device based on the discrimination signals of the color subcarrier frequency discrimination circuit and the SECAM discrimination circuit is added,
In addition to the action of the invention of claim 1, the following action is added to automatically perform mode switching of the dual-purpose device.

When a SECAM signal is input when the dual-purpose device (for example, a comb filter) is in the NTSC / PAL mode (for example, the comb mode), the color standard discrimination / separation is performed based on the discrimination signal with the SECAM signal of the SECAM discrimination circuit. The control circuit outputs a mode switching control signal to the dual-purpose device, and the dual-purpose device is automatically switched to the SECAM mode (for example, the through mode).

When an NTSC / PAL signal is input when the dual-purpose device (for example, a comb filter) is in the SECAM mode (for example, the through mode), the SECAM discriminator signal without the SECAM signal or the color subcarrier frequency discriminating circuit is used. Discrimination signal (for example, 3.58 MHz or 4.
43 MHz), the color standard discrimination / control circuit outputs a mode switching control signal to a dual-purpose device,
The dual-purpose device is automatically switched to the NTSC / PAL mode (for example, comb mode).

According to a fourth aspect of the present invention, in the third aspect of the present invention, a vertical synchronizing frequency discriminating circuit, a color burst discriminating circuit and a color subcarrier frequency discriminating circuit are provided for processing a luminance signal in an input signal, and an NTSC. If the circuit that performs color signal processing in the / PAL signal is integrally formed on the main chip, and the SECAM discrimination circuit is integrally formed on the sub chip together with the SECAM color signal processing circuit, the required number of components is reduced. Can be reduced.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. In FIG. 1, 10 is a 3-line comb filter, 12 is a clock generator, and these are examples of dual-purpose devices which are set to a mode corresponding to the input signal system by a switching control signal from the outside.

The comb filter 10 comprises a Y / C separation circuit 14 and a switching circuit 16, and the input signal is NTSC.
In the case of the / PAL signal, the switching circuit 16 is connected to the a2 side (com mode side), and the luminance signal and the color signal separated by the Y / C separation circuit 14 are used as the Y output and the C output. In the case of the SECAM signal, the switching circuit 16 is switched. The circuit 16 is connected to the a1 side (through mode side) and the input signal is directly output as the Y output. Switching of the switching circuit 16 is performed by a switching control signal a supplied from the outside.

As shown in FIG. 2, the Y / C separation circuit 14 includes two 1-line delay circuits 18, 20 and a switching circuit 2.
2, consisting of an addition circuit 24 and a subtraction circuit 26, NTSC
By utilizing the fact that the phase of the color subcarrier of the signal (or PAL signal) is inverted every line (or every two lines),
The data before the line (or two lines) and the data of the current line are added and divided by 2 to eliminate the color component to obtain the Y (luminance) signal, and subtracted and divided by 2 to leave only the color component and C (color)
The signal is obtained and the Y signal and the C signal are separated.
Switching between the NTSC signal and the PAL signal is performed by switching the switching circuit 22 by a switching control signal b supplied from the outside.

As shown in FIG. 2, the clock generator 12 receives an Fsc signal from an external switching control signal c.
Crystal oscillator 13 and Fsc to set the frequency to 3.58 MHz
Is mainly composed of a switching circuit 17 for selecting one of the crystal oscillators 15 for setting the frequency to 4.43 MHz and an APC (automatic phase control) circuit 19. The APC circuit 19 is configured to match the color burst and the phase in the input signal. Switch circuit 1
The sampling clock of frequency 4Fsc corresponding to the frequency selected in 7 is output to the Y / C separation circuit 14. Fsc represents the color subcarrier frequency.

Reference numerals 28 and 30 are a main chip and a sub chip composed of an IC (integrated circuit). A luminance signal processing circuit 32, a vertical synchronizing frequency discriminating circuit 33, an NTSC / PAL color signal processing circuit 34, a color subcarrier frequency discriminating circuit 35 and a color burst discriminating circuit 36 are formed in the main chip 28, and the sub chip 30 is formed. Inside, SEC
AM color signal processing circuit 38, control switch circuit 39 and S
An ECAM discrimination circuit 40 is formed.

The luminance signal processing circuit 32 controls the NTSC, PAL, and SECA of the Y output of the comb filter 10.
The M-type luminance signal is processed and the Y signal is output. Vertical sync frequency discrimination circuit 33
Is the frequency (vertical scanning frequency) of the vertical synchronizing signal in the Y output of the comb filter 10 is 60 Hz or 50H.
It is configured to determine whether it is z and output a determination signal. The NTSC / PAL color signal processing circuit 34
Is NTSC, P in the C output of the comb filter 10.
The color difference signal R−Y, which is obtained by demodulating the AL type color signal,
It is configured to output BY. The color sub-carrier frequency discrimination circuit 35 uses the C of the Y / C separation circuit 14.
It is configured to determine the color subcarrier frequency of the NTSC and PAL color signals being output and output the determination signal. The color burst discrimination circuit 36 is configured to discriminate whether or not there is a color burst during the C output of the Y / C separation circuit 14 and output a discrimination signal.

The SECAM color signal processing circuit 38 is configured to demodulate the SECAM color signal in the Y output of the comb filter 10 and output color difference signals RY and BY. There is. The SECAM discrimination circuit 4
0 indicates SECAM during Y output of the comb filter 10.
It is configured to determine whether or not there is a signal and output a determination signal. The control switch circuit 39 uses a forced S signal from a color standard discrimination / control circuit 42 described later.
It is configured to turn on and off with and without the ECAM signal. The SECAM color signal processing circuit 38 is configured to stop the color demodulation processing when the control switch circuit 39 is turned on.

Color standard discrimination / control circuit 4
2 is the SEC based on the discrimination signals of the vertical synchronization frequency discrimination circuit 33 and the color burst discrimination circuit 36.
Based on the first function of outputting the forced SECAM signal to the AM color signal processing circuit 38 and the discrimination signals of the color subcarrier frequency discrimination circuit 35 and the SECAM discrimination circuit 40, the comb filter 10 and the clock generator 12 are provided. It has a second function of outputting the switching control signals a, b, and c.

Next, the operation of FIGS. 1 and 2 will be described with reference to FIG. For convenience of explanation, A: SECAM color signal processing circuit 3 when the input signal is an NTSC signal or a PAL signal
8 is a function of forcibly stopping the color signal processing, and B: a comb filter 10 corresponding to the television system of the input signal.
The operation will be described separately from the operation of switching the mode.

A: The action in which the color signal processing of the SECAM color signal processing circuit 38 is forcibly stopped when the input signal is the NTSC signal or the PAL signal. (A) First, the switching circuit 16 of the comb filter 10 has a2.
The case where the NTSC signal or the PAL signal is input in the comb mode connected to the side will be described. In the comb mode, the input signal is separated into a luminance signal and a chrominance signal by the Y / C separation circuit 14, and this luminance signal is passed through the Y output side of the comb filter 10 to the vertical synchronization frequency discrimination circuit 3
3 and the color signal is input to the color burst circuit 36 via the C output side of the comb filter 10.

Since the frequency of the vertical synchronizing signal is 60 Hz when the input signal is the NTSC signal, the color standard discrimination / control circuit 42 discriminates the vertical synchronizing signal frequency of 60 Hz regardless of the presence or absence of color burst as shown in FIG. Based on the signal, a forced SECAM signal is output to the sub chip 30 to turn on the control switch circuit 39,
The color signal processing of the AM color signal processing circuit 38 is stopped. When the input signal is the PAL signal, the frequency of the vertical synchronizing signal is 50 Hz. However, the color standard discrimination / control circuit 42 sends the forced SECAM signal to the sub-chip based on the discrimination signal with the color burst as shown in FIG. Then, the control switch circuit 39 is turned on and the color signal processing of the SECAM color signal processing circuit 38 is stopped.

(B) Next, when the switching circuit 16 of the comb filter 10 is in the through mode connected to the a1 side,
The case where the NTSC signal or the PAL signal is input will be described. In the through mode, the input signal is input to the vertical synchronizing frequency discriminating circuit 33 via the Y output side of the Y-C separating circuit 14 and the Y / C separating circuit 14, and also passes through the Y / C separating circuit 14. C of the comb filter 10
It is input to the color burst circuit 36 via the output side.

When the input signal is an NTSC signal, the color standard discrimination and
The control circuit 42, based on the discrimination signal of the vertical synchronizing signal frequency of 60 Hz, irrespective of the presence or absence of color burst, forces the S
The ECAM signal is output to the sub chip 30, the control switch circuit 39 is turned on, and the color signal processing of the SECAM color signal processing circuit 38 is stopped. When the input signal is the PAL signal, the color standard discrimination / control circuit 42 turns on the control switch circuit 39 based on the discrimination signal with the color burst in the same manner as in the case (a), and the SECAM
The color signal processing of the color signal processing circuit 38 is stopped.

B: Comb filter 1 corresponding to the input signal
0 is automatically switched between the comb mode and the through mode (a) First, the switching circuit 16 of the comb filter 10 has a2
Side (com mode side) when connected to SECAM
An operation of inputting a signal and automatically switching the switching circuit 16 to the a1 side (through mode side) will be described.

Since the frequency of the color subcarrier of the SECAM signal changes line by line, the comb filter 10 does not work for the SECAM signal and is not separated into Y and C signals.
Therefore, if the SECAM signal is input when the switching circuit 16 of the comb filter 10 is on the a2 side (com mode side), the SECAM signal is transmitted via the Y output side to the SECAM signal.
It is inputted to the discrimination circuit 40 or inputted to the color burst discrimination circuit 36 via the C output side. Therefore, the color standard discrimination / control circuit 42, as shown in FIG.
Based on the discrimination signal with ECAM signal or the discrimination signal without color burst, output to the switching control signal a switching circuit 16;
The switching circuit 16 is switched from the a2 side (com mode side) to the a1 side (through mode side).

Therefore, the switching circuit 22 of the Y / C separation circuit 14 is connected to the b2 side, and the clock generator 12
Fsc of the sampling clock (frequency 4Fsc) supplied to the comb filter 10 is 4.4 for PAL.
3. The frequency is 3 MHz and 4.
Even if the SECAM discrimination circuit 40 does not output the discrimination signal with the SECAM signal, there is no color burst in the SECAM signal as shown in FIG. A discrimination signal indicating that there is no color burst is output from 36, and a color standard discrimination / control circuit 4 based on this discrimination signal
The switching control signal a from 2 causes the switching circuit 16 to output a2.
The side (com mode side) is switched to the a1 side (through mode side).

(B) Next, when the NTSC signal and the PAL signal are input while the switching circuit 16 of the comb filter 10 is connected to the a1 side (through mode side), the switching circuit 16 is switched to the a2 side (comb). The operation of automatically switching to the mode side) will be described. When the NTSC signal and the PAL signal are input while the comb filter 10 is in the through mode, these signals are input to the SECAM discrimination circuit 40 via the Y output side of the comb filter 10 and Y / C.
The separation circuit 14 separates the Y signal and the C signal, and the C signal is input to the color burst discrimination circuit 36. For this reason,
As shown in FIG. 3, the color standard discrimination / control circuit 42 switches the switching circuit 16 to the a1 side by the switching control signal a based on the discrimination signal of either the discrimination signal without SECAM signal or the discrimination signal with color burst. Automatically switches from the through mode side) to the a2 side (com mode side).

Therefore, monochrome NTSC / PAL
Even when a signal is input and the color burst discriminating circuit 36 does not output the color burst discriminating signal, the monochrome NTSC signal and PAL signal are transferred from the Y output side of the comb filter 10 to the SECAM discriminating circuit 40. Input and use SECA for monochrome NTSC / PAL signals.
Since there is no M signal, the SECAM discrimination circuit 40
A discrimination signal indicating no AM signal is output, and the discrimination circuit automatically switches the switching circuit 16 from the a1 side (through mode side) to the a2 side (com mode side).

(C) Next, the operation after the comb filter 10 is switched to the through mode or comb mode corresponding to the method of the input signal by the above (a) and (b), or the comb filter from the beginning. The operation when 10 is in the through mode or the comb mode corresponding to the method of the input signal will be described.

First, the switching circuit 1 of the comb filter 10
The operation when the SECAM signal is input when 6 is in the through mode (a1 side) will be described. SEC entered
The AM signal is input to the luminance signal processing circuit 32 in the main chip 28 via the Y output side of the comb filter 10 and also to the SECAM color demodulation processing circuit 38 and the SECAM discrimination circuit 40 in the sub chip 30.

The luminance signal Y processed by the luminance signal processing circuit 32 and the color difference signals RY and BY which are color demodulated by the SECAM color demodulation processing circuit 38 are R in a matrix circuit (not shown) in the subsequent stage. , G, B signals are converted and supplied to a display device to display a color image. Also, enter SE
CAM signal Y / C separation circuit 14 of comb filter 10
However, there is no color burst in the SECAM signal, and the SECAM discrimination circuit 40 outputs SECA.
Since the discrimination signal with the M signal is output, the switching circuit 16 does not switch from the through mode to the comb mode by the switching control signal a from the color standard discrimination / control circuit 42.

Next, when the switching circuit 16 of the comb filter 10 is in the comb mode (a2 side), the NTSC signal, P
The operation when the AL signal is input will be described. The input NTSC signal and PAL signal are input to the comb filter 10
Is separated into a Y signal and a C signal by the Y / C separation circuit 14 of
The signal is input to the luminance signal processing circuit 32 in the main chip 28, the SECAM color demodulation processing circuit 38 and the SECAM discrimination circuit 40 in the sub chip 30, and C
The signal is input to the NTSC / PAL color signal processing circuit 34 and the color burst discrimination circuit 36 in the main chip 28.

The luminance signal Y processed by the luminance signal processing circuit 32 and the color difference signals RY and BY which are color demodulated by the NTSC / PAL color demodulation processing circuit 34 are a matrix circuit (not shown) in the subsequent stage. Are converted into R, G, B signals and supplied to the display device to display a color image. Further, the color burst discriminating circuit 36 outputs a discriminating signal with color burst, and the SECAM discriminating circuit 40 outputs the SEC.
Since the determination signal without the AM signal is output, the switching circuit 16 does not switch from the comb mode to the through mode by the switching control signal a from the color standard determination / control circuit 42.

The switching between the NTSC signal and the PAL signal is performed as follows. Input signal is NTSC
When it is a signal, the switching circuit 22 of the Y / C separation circuit 14
Is connected to the b1 side incorporating only the delay circuit 18 by the switching control signal b from the color standard discrimination / control circuit 42, and the clock generator 12 is
Fsc is set to 3.58 MHz (4.43 NT) by the switching control signal c from the color standard discrimination / control circuit 42.
The sampling clock of 4 Fsc, which is 4.43 MHz in the case of SC, is output to the Y / C separation circuit 14.

When the input signal is a PAL signal, Y / C
The switching circuit 22 of the separation circuit 14 is connected to the b2 side that incorporates the delay circuits 18 and 20 by the switching control signal b, and the clock generator 12 uses the switching control signal c to sample 4Fsc at which Fsc is 4.43 MHz. The output clock is output to the Y / C separation circuit 14.

In the above embodiment, the vertical synchronizing frequency discriminating circuit, the color subcarrier frequency discriminating circuit and the color burst discriminating circuit are integrally formed on the main chip together with the luminance signal processing circuit and the NTSC / PAL color signal processing circuit. S
The case where the ECAM discrimination circuit is integrally formed on the sub-chip together with the SECAM color signal processing circuit and the number of components is reduced has been described. However, the present invention is not limited to this, and the vertical synchronization frequency discrimination circuit The carrier frequency determination circuit and the color burst determination circuit are configured separately from the luminance signal processing circuit and the NTSC / PAL color signal processing circuit (for example, configured separately from the main chip), and the SEC
It is also possible to use the AM discrimination circuit configured separately from the SECAM color signal processing circuit (for example, configured separately from the sub chip).

In the above embodiment, the input signal is NTSC.
In addition to forcibly stopping the color signal processing of the SECAM color signal processing circuit by the forced SECAM signal in the case of a signal or a PAL signal, a mode in which a comb filter is supported corresponding to the television system of the input signal (for example, , The comb mode is switched to the through mode, or the through mode is switched to the comb mode, and the clock generator is compatible with the mode (for example, Fs for the NTSC signal).
c = 3.58MHz mode, F for PAL signal
sc = 4.43 MHz mode) has been described, but the present invention is not limited to this, and the color signal of the SECAM color signal processing circuit is generated by the forced SECAM signal at least when the input signal is the NTSC signal or the PAL signal. It can be used for those that forcibly stop processing.

In the embodiment described above, the case where the dual-purpose device which is set to the mode corresponding to the input signal system by the switching control signal from the outside is the comb filter formed by the Y / C separation circuit and the switching circuit will be described. However, the present invention is not limited to this. For example, as shown in FIG. 4, the Y / C separation circuit 14a can also be used when the dual-purpose device set to the mode corresponding to the input signal system by the switching control signal from the outside. In this case, Y /
The main chip 28 is coupled to the Y output side and the C output side of the C separation circuit 14a, and the input signal (composite video signal) introduced from the previous stage side of the Y / C separation circuit 14a is coupled to the input side of the sub chip 30.

In the above embodiment, a dual-purpose device (comb filter or clock generator) is set to a mode corresponding to the input signal system by an external switching control signal.
However, the present invention is not limited to this, and a device without such a dual-purpose device can also be used.

[0042]

According to the invention of claim 1, NTSC, PAL,
Color signal processing is stopped by a vertical sync frequency discrimination circuit, a color burst discrimination circuit, and a forced SECAM signal from the outside in various television system video equipment that uses a composite video signal of SECAM system or PAL, SECAM system as an input signal. It is equipped with a SECAM color signal processing circuit and a color standard discrimination / control circuit. When the input signal is an NTSC signal, the vertical sync frequency discrimination circuit determines that the vertical sync signal frequency is 60 Hz, and when the input signal is a PAL signal, a color burst. Since the determination circuit determines that there is a color burst, the color standard determination / control circuit outputs the forced SECAM signal to the SECAM color signal processing circuit based on these determination signals and stops the SECAM color signal processing. . Therefore, the input signal is N
SECAM for TSC or PAL signals
It is possible to prevent the color signal processing circuit from malfunctioning due to the determination that the SECAM signal is input.

According to a second aspect of the present invention, in the first aspect of the present invention, the vertical synchronizing frequency discriminating circuit and the color burst discriminating circuit include a luminance signal processing circuit and a color signal processing circuit (NTSC / P).
(For AL signal) and integrated on the main chip,
Since the SECAM color signal processing circuit is integrally formed on the sub chip, the number of required components can be reduced.

According to a third aspect of the present invention, in the first aspect of the present invention, a dual-purpose device (for example, a comb filter or a clock generator) is set in a mode corresponding to an input signal system by an external switching control signal, and an input device. A color subcarrier frequency discriminating circuit for discriminating the color subcarrier frequency of the color signal in the signal and a SECAM discriminating circuit for discriminating whether or not the SECAM signal is present in the input signal are added, and a color standard discrimination / control circuit is also added. In addition, a function of outputting a mode switching control signal to a dual-purpose device based on the discrimination signals of the color subcarrier frequency discrimination circuit and the SECAM discrimination circuit is added,
In addition to the action of the invention of claim 1, the following action is added to automatically perform mode switching of a dual-purpose device (for example, a comb filter).

That is, if the SECAM signal is input when the dual-purpose device (eg comb filter) is in the NTSC / PAL mode (eg comb mode), SECA
Based on the discrimination signal with SECAM signal of the M discrimination circuit,
The color standard discrimination / control circuit outputs the mode switching control signal to the dual-purpose device, and the dual-purpose device is SECAM.
Mode (for example, through mode).

When an NTSC / PAL signal is input when the dual-purpose device (for example, comb filter) is in the SECAM mode (for example, the through mode), the SECAM signal without discrimination signal or the color subcarrier frequency discrimination circuit Discrimination signal (for example, 3.58 MHz or 4.
43 MHz), the color standard discrimination / control circuit outputs a mode switching control signal to a dual-purpose device,
The dual-purpose device is switched to the NTSC / PAL mode (for example, comb mode).

According to a fourth aspect of the present invention, in the third aspect of the present invention, the vertical synchronizing frequency discriminating circuit, the color burst discriminating circuit, and the color subcarrier frequency discriminating circuit are the luminance signal processing circuit and at least one of the NTSC signal and the PAL signal. If the circuit that performs color signal processing in the signal of 1) is integrally formed on the main chip and the SECAM discrimination circuit is integrally formed on the sub chip together with the SECAM color signal processing circuit, the number of required components is reduced. can do.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment example of a malfunction prevention circuit of a SECAM color signal processing circuit in a device compatible with multiple television standard systems according to the present invention.

FIG. 2 is a block diagram showing an example of a part of the configuration of FIG.

FIG. 3 is an NTS for explaining the operation of FIGS. 1 and 2;
It is explanatory drawing which shows the difference of C, PAL, and a SECAM system.

FIG. 4 is a block diagram showing another embodiment of the present invention.

FIG. 5 is an explanatory diagram showing a difference between NTSC, PAL, and SECAM systems.

[Explanation of symbols]

10 ... Comb-type filter, 12 ... Clock generator, 13, 15 ... Crystal oscillator, 14, 14a ... Y /
C separation circuit, 16, 17, 22 ... Switching circuit, 18, 2
0 ... 1 line (1H) delay circuit, 19 ... APC (automatic phase control) circuit, 24 ... Addition circuit, 26 ... Subtraction circuit, 28 ... Main chip, 30 ... Sub chip, 3
2 ... Luminance signal processing circuit, 33 ... Vertical sync frequency discrimination circuit, 34 ... NTSC / PAL color signal processing circuit, 35
... color subcarrier frequency discrimination circuit, 36 ... color burst discrimination circuit, 38 ... SECAM color signal processing circuit, 39
... control switch circuit, 40 ... SECAM discrimination circuit,
42 ... Color standard discrimination / control circuit, forced SE
CAM ... signal for stopping color signal processing of SECAM color signal processing circuit, 3.58 / 4.43 ... color subcarrier frequency discrimination signal (3.58 MHz and 4.43 MHz),
60/50 ... Vertical sync signal frequency discrimination signal, Fs
c ... Color subcarrier frequency, 4Fsc ... Clock frequency, a, b, c ... Switching control signal, RY, BY ...
Color difference signal, Y ... Luminance signal.

Claims (4)

[Claims] Claims: 1. In various television system / video equipment which uses as input signals two or more composite video signals including the SECAM system among NTSC, PAL and SECAM systems, the frequency of the vertical synchronizing signal in the input signal is A vertical sync frequency discrimination circuit for discriminating, a color burst discrimination circuit for discriminating whether or not there is a color burst in the input signal, color signal processing in the SECAM system composite video signal, and forced from the outside. A SECAM color signal processing circuit in which color signal processing is stopped by a SECAM signal, and a color for outputting a forced SECAM signal to the SECAM color signal processing circuit based on the determination signals of the vertical synchronization frequency determination circuit and the color burst determination circuit. SEC characterized by comprising a standard discrimination / control circuit
Malfunction prevention circuit for AM color signal processing circuit. 2. A vertical sync frequency discriminating circuit and a color burst discriminating circuit are provided on a main chip together with a circuit for processing a luminance signal in an input signal and a circuit for processing a color signal in a composite video signal of NTSC and PAL system. The malfunction prevention circuit of the SECAM color signal processing circuit according to claim 1, wherein the SECAM color signal processing circuit is integrally formed on a sub-chip. 3. In various television system / combined video equipment which uses as input signals two or more kinds of composite video signals including the SECAM system among the NTSC, PAL and SECAM systems, the input signal is supplied by a switching control signal from the outside. A dual-purpose device set in a mode corresponding to the system, a vertical synchronization frequency determination circuit that determines the frequency of the vertical synchronization signal in the input signal, and a color burst that determines whether or not there is a color burst in the input signal. Discriminating circuit, color subcarrier frequency discriminating circuit for discriminating the color subcarrier frequency of the color signal in the input signal, and SECAM discriminating circuit for discriminating whether or not the input signal contains the composite video signal of the SECAM system. And the color signal processing in the composite video signal of the SECAM system is performed, and the color signal processing is stopped by the forced SECAM signal from the outside. The SECAM color signal processing circuit, the vertical synchronization frequency discrimination circuit and the color burst discrimination circuit, and outputs the forced SECAM signal to the SECAM color signal processing circuit based on the discrimination signals of the color burst carrier discrimination circuit. A malfunction prevention circuit for a SECAM color signal processing circuit, comprising: a color standard discrimination / control circuit that outputs a mode switching control signal to the dual-purpose device based on a discrimination signal from the SECAM discrimination circuit. 4. A vertical synchronizing frequency discriminating circuit, a color burst discriminating circuit, and a color subcarrier frequency discriminating circuit, a circuit for processing a luminance signal in an input signal, and a color signal processing in a composite video signal of NTSC or PAL system. The SECAM discrimination circuit is integrally formed on the main chip together with the circuit for
4. The malfunction prevention circuit for a SECAM color signal processing circuit according to claim 3, wherein the malfunction prevention circuit is integrally formed on a sub chip together with the SECAM color signal processing circuit.