JPH05183882A - Broadcasting system converter - Google Patents

Abstract

PURPOSE:To prevent a video signal in a broadcasting system not coincident with the system conversion of a broadcasting system converter from being outputted as an irregular signal when such a video signal is inputted, in the broadcasting system converter. CONSTITUTION:A control circuit part 10 is provided which permits an inputted composite video signal to be outputted as it is without passing through the PAL/NTSC system conversion circuit part 3 or permits only a liminance signal to be taken out of the inputted composite video signal in the PAL/NTSC system conversion circuit part 3 to convert and output, when the composite video signal in SECAM system not coincident with the system conversion in a PAL/NTSC system conversion circuit part 3 is inputted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a broadcasting system converter mounted on a video device such as a video tape recorder or a television receiver, or connected to the video device in an adapter format.

[0002]

2. Description of the Related Art Conventionally, for example, both NTSC and PAL broadcasting system converters have a block circuit configuration as shown in FIG. 2, where 1 is an input terminal to which a composite video signal of each broadcasting system is input, 2 Is an AGC circuit for preventing the input composite video signal from being affected by level fluctuations due to the strength of the received radio wave, 3 is a PAL / NTSC system conversion circuit section, and 4 is a composite video signal that has passed through the AGC circuit 2. A PAL / NTSC decoder for separating a luminance signal and a chroma (carrying color) signal from each other and demodulating the chroma signal by the PAL or NTSC system to output the color difference signal.
The luminance signal and the color difference signal output from the NTSC decoder 4 are temporarily converted from analog to digital signal form, and PAL is used.
Alternatively, the signal processing circuit 6 performs signal processing (calculation, etc.) for system conversion to NTSC and then converts and outputs the original analog signal form. Reference numeral 6 designates the output signal system from the signal processing circuit 5 as NTSC or PAL. An output method specifying circuit for outputting a method specifying signal to the signal processing circuit 5 for specifying, and a color difference signal output from the signal processing circuit 5 for modulating a color subcarrier by a PAL or NTSC method that matches the output method. After that, PAL / NTS that synthesizes with luminance signal and outputs
A C encoder, 8 is a Y / C (video output) circuit for performing level adjustment, and 9 is an output terminal.

Therefore, when the user designates the system conversion to NTSC by the output system designating circuit 6, when the PAL system composite video signal is input to the input terminal 1, the composite video signal is output. PAL / NTS via 2
The C decoder 4 separates the color difference signals RY and BY from the chroma demodulation processing in the PAL system and the luminance signal Y, and
The signal processing circuit 5 converts the luminance signal Y'of the NTSC system into the color difference signals RY 'and BY'. Then, after being converted into a composite video signal in the NTSC system by the PAL / NTSC encoder 7, it is output from the output terminal 9 via the Y / C circuit 8 and supplied to, for example, an NTSC system television receiver or a video tape recorder. Will be. When an NTSC composite video signal is input,
The composite video signal is sent to the PAL / NT via the AGC circuit 2.
After being separated by the SC decoder 4 into a color difference signal and a luminance signal by chroma demodulation processing in the NTSC system, the signal processing circuit 5 does not convert the system, that is, in the latter stage P in the NTSC system.
It will be output to the AL / NTSC encoder 7.

[0004]

However, in such a conventional PAL and NTSC both-broadcast system conversion apparatus having such a configuration, a video signal of a broadcasting system which does not match the system conversion, in this case, a composite video signal is input. When a composite video signal of the SECAM system is input,
Both AL and NTSC chroma signals are color subcarrier AM
In contrast to the modulated signal, the SECAM type chroma signal is an FM modulated signal of two color subcarriers, so PAL
/ NTSC decoder can extract luminance signals but not color difference signals, that is, FM-modulated SEC
No matter how PAL / NTSC chroma demodulation is applied to the AM chroma signal, a normal color difference signal output cannot be expected.
There was a problem that a nonstandard signal was output. The present invention has been made in view of the above circumstances, and is a broadcast that prevents a nonstandard signal from being output when a video signal of a broadcast system that does not match the system conversion is input. An object is to provide a method conversion device.

[0005]

In order to achieve the above-mentioned object, according to the present invention, in a broadcasting system converter having a system conversion circuit section for converting a broadcasting system of an inputted video signal, broadcasting of the inputted video signal is performed. When the system does not match the system conversion in the system conversion circuit unit, control is performed to output the signal as it is without passing through the system conversion circuit unit, or to output only the luminance signal after system conversion. A circuit section is provided, and the control circuit section has a system discriminating circuit for discriminating the broadcasting system of the input video signal. The system discriminating circuit switches the output mode based on the discrimination result. A signal or a control signal for controlling the conversion processing in the system conversion circuit section is output. Specifically, the system conversion circuit unit is
A PAL / NTSC system conversion circuit unit that performs both SC and PAL conversion, and the system determination circuit is a SECAM determination circuit that determines whether or not the input video signal is the SECAM system.

[0006]

According to this structure, when a PAL or NTSC system video signal matching the system conversion is input, the PAL / NTSC system conversion circuit section receives PAL or NSC.
The system is converted to the TSC system and then output. Then, when a SECAM video signal that does not match the system conversion is input, it is discriminated by the SECAM discrimination circuit, and the output mode is switched so that it is output as it is without passing through the PAL / NTSC system conversion circuit section. Or the conversion process is controlled in the PAL / NTSC system conversion circuit unit so that only the luminance signal is extracted and system conversion is performed and then output.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An example of block circuit configuration for implementing the present invention will be described below with reference to the drawings. The same parts as those of the conventional one are designated by the same reference numerals and the description thereof will be omitted. In this embodiment, the PAL / NTSC system conversion circuit unit 3
Broadcast system that does not match the system conversion in this case, in this case SECA
When a composite video signal of M system is input, PAL / N
The control circuit unit 10 is provided so as to output the signal as it is without passing through the TSC system conversion circuit unit 3 or to output only the luminance signal thereof after system conversion and output. Specifically, as shown in FIG. 1, the control circuit unit 10 outputs the composite video signal from the AGC circuit 2 to the PAL / NTS.
The conversion output mode (contact side a) supplied to the Y / C circuit 8 in the subsequent stage through the C system conversion circuit unit 3 and the Y / C circuit 8 in the subsequent stage without passing through the PAL / NTSC system conversion circuit unit 3
To the through output mode (contact b side) supplied to the AGC circuit 2, a bandpass filter 12 for extracting only the chroma signal from the composite video signal supplied to the AGC circuit 2, and a bandpass filter 12 for extracting the chroma signal. The composite video signal input from the input chroma signal is S
SECAM discrimination circuit 13 for discriminating whether or not the ECAM system is used
The SECAM discriminating circuit 13 switches the switch circuit 11 which is normally in the conversion output mode to the through output mode when the SECAM system is discriminated, or the PAL / NTSC decoder 4 outputs the switching signal. A control signal for stopping the chroma demodulation processing (that is, for operating the color killer) is output.
Here, whether to output the switching signal or the control signal is
It is assumed that the user can freely select it according to the broadcasting system of the video equipment connected to the output terminal 9 or according to the purpose of use.

Therefore, in the broadcasting system converter having such a block circuit structure, the SECAM is connected to the input terminal 1 of the broadcasting system converter.
When a composite video signal of the H.264 system is input, it is determined that the SECAM system is the AGC circuit 2-bandpass filter 12
The SECA discrimination circuit 13 discriminates the SECA
A control signal or a switching signal is output from the M discriminating circuit 13. As a result, for example, when the control signal is output, the input composite video signal is output from the output terminal 9 through the PAL / NTSC system conversion circuit unit 3, and at this time, the chroma in the PAL / NTSC decoder 4 is changed. Since the demodulation processing is stopped, the PAL / NTSC decoder 4 extracts only the luminance signal of the composite video signal, and the signal processing circuit 5 outputs P specified by the output method specifying circuit 6.
After converting to AL or NTSC system, PAL / NT
It is output as a monochrome signal without a chroma signal via the SC encoder 7-switch circuit 11-Y / C circuit 8. When the switching signal is output, the input composite video signal does not pass through the PAL / NTSC system conversion circuit unit 3, that is, from the AGC circuit 2 to the switch circuit 11-Y.
It is output from the output terminal 9 through the / C circuit 8 in the SECAM mode as it is. When a PAL or NTSC composite video signal is input, the SECAM discrimination circuit 13 does not output a switching signal or a control signal. Therefore, the input composite video signal is output through the PAL / NTSC conversion circuit unit 3. The signal is output from the terminal 9. At that time, both the luminance signal and the chroma signal are PAL or NT designated by the output system designation circuit 6 in the signal processing circuit 5.
It will be converted to the SC system. As described above, in the present embodiment, both the switching signal and the control signal are output from the SECAM discrimination circuit, but only one of them may be output. For example, when only the control signal is used, the switch circuit is unnecessary. Becomes Further, in this embodiment, PAL, NTS
Although the case where the system is converted to both the C system has been described, for example, the system may be converted from the SECAM system to the NTSC system, in which case it is determined that a composite video signal of a broadcasting system other than SECAM is input. To do PAL /
An NTSC discriminating circuit may be provided.

[0009]

As described above, according to the broadcasting system converter of the present invention, when the broadcasting system of the input video signal does not match the system conversion in the system conversion circuit section, the system conversion circuit section is passed through. Instead, it is output as it is, or only the luminance signal is taken out and output after performing system conversion, so when a video signal of a broadcasting system that does not match the system conversion is input, it is regarded as a nonstandard signal. It is possible to eliminate the inconvenience that it is output as.

[Brief description of drawings]

FIG. 1 is a diagram showing a block circuit configuration example for realizing the present invention.

FIG. 2 is a diagram showing a conventional block circuit configuration example.

[Explanation of symbols]

 3 PAL / NTSC system conversion circuit section 10 Control circuit section 11 Switch circuit 13 SECAM discrimination circuit

Claims (3)

[Claims] 1. A broadcasting system conversion device having a system conversion circuit unit for converting a broadcasting system of an input video signal, when the broadcasting system of the input video signal does not match the system conversion in the system conversion circuit unit. Is a broadcasting system conversion device, characterized in that it is provided with a control circuit unit that outputs the signal as it is without passing through the system conversion circuit unit, or takes out only the luminance signal and outputs it after system conversion. 2. The control circuit section has a system discriminating circuit for discriminating a broadcasting system of an input video signal, and the system discriminating circuit switches a output signal based on the discrimination result or system conversion. The broadcasting system conversion device according to claim 1, wherein the broadcasting system conversion device outputs a control signal for controlling conversion processing in the circuit unit. 3. The system conversion circuit unit is NTSC, PAL
It is a PAL / NTSC system conversion circuit section that performs conversion of both systems, and the system discrimination circuit uses the SEC as an input video signal.
The broadcasting system conversion device according to claim 2, wherein the broadcasting system conversion device is a SECAM discrimination circuit that discriminates whether the system is an AM system.