JPH11187411A - Input video mode discriminating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To rationalize the circuit configuration of the input video mode discriminating device by discriminating a video mode of a signal selected by switching color signals from each video input terminal. SOLUTION: A color signal S1 (S2) is fed to a first changeover circuit 1 directly and to a second changeover circuit 2 via a capacitor C3 (C4). Both the changeover circuits 1, 2 are switched interlockingly by a common switching signal S3 to select the same color signal system. A selected color signal from the first changeover circuit 1 is outputted and a color signal of the same system from the second changeover circuit 2 is given to a base of a transistor TR1 and outputted with a low impedance circuit from the emitter. The emitter output is given to an integration circuit consisting of a resistor R3 and a capacitor C5, from which a DC component is extracted. The DC component is converted by an A/D converter section 3 into digital data, corresponding to a DC voltage of the component. Video mode data are fed to a discrimination section 4, where the video mode is discriminated, and a discrimination signal S4 is outputted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an input video mode discriminating apparatus, and more particularly, to a video mode discrimination of a so-called S terminal input signal.

[0002]

2. Description of the Related Art In the past, the display aspect ratio of a television receiver was mainly 4: 3, but in recent years, it has been 16: 9.
The so-called landscape television is increasing. In addition, it is a natural function of recent television receivers to provide a plurality of video input terminals for connection to external devices such as a VTR. One of the forms of the external video input terminal is an S terminal. It is well known that the video signal input to the S terminal is a signal separated into a luminance signal and a chrominance signal (chroma signal). In addition, video sources, such as video tapes and video disks, targeting the S terminal are diversified.
There are a lot of video images. Therefore, each television receiver having a different aspect ratio needs an automatic processing function according to the aspect ratio of the video source.

For this reason, in recent S terminal input signals, a signal indicating its own video mode is superimposed on the color signal component, so that the television receiver can automatically determine the input video. The signal indicating the video mode is a DC voltage, and the magnitude of the DC voltage indicates a specific video mode. For example, when the DC voltage is 0 V, the conventional video mode has a 4: 3 aspect ratio (the video is also referred to as normal). When the DC voltage is 2.2 V, the aspect ratio is 4: 3. A predetermined area in each of the upper and lower portions of the screen is set to a black screen, and the projected image portion is in a 16: 9 image mode (the image is also referred to as a letter box).
Is a video mode in which an image having an aspect ratio of 16: 9 is changed to an aspect ratio of 4: 3 (the image is also referred to as squeeze).

Conventionally, the switching of each input video and the determination of the video mode associated with the switching have been processed by a circuit having the configuration shown in FIG. Hereinafter, FIG. 3 will be described. FIG. 3 shows an example in which the number of input systems is two, and only the switching of the video signal is shown for switching the video components, and the switching circuit for the luminance signal is omitted. In the figure, the signals S1 and S1 input to the two inputs
S2 means a color signal (analog) in the S terminal input. The above-described DC voltage is superimposed on the color signal. The color signals S1 and S2 are input to the transistors TR21 and TR22, respectively, are reduced in impedance, and output from the emitter. The resistors R21 and R22 on the base side are mainly for impedance matching, and the capacitors C21 and C22
Is for blocking DC voltage.

The emitter output of each of TR21 and TR22 is R
DC components are extracted through respective integrating circuits (functionally low-pass filters) including R23 and C23 and R24 and C24. The DC component is converted into digital data (for example, an 8-bit signal) corresponding to the DC voltage value by A / D converters 21 and 22 provided for each system. Hereinafter, this digital data is referred to as video mode data.
On the other hand, the color signals S1 and S2 are connected to capacitors C25 and C26, respectively.
Is input to the first switching circuit 23 via the. The switching circuit 23 switches and selects a desired color signal, and the switching is performed according to the switching signal S3. The switching signal S3 is a signal based on the video input system designation by the user operating the operation unit or the like. The video mode data from each of the A / D converters 21 and 22 is input to a second switching circuit 24. The switching circuit 24 operates in conjunction with the first switching circuit 23, and switches so as to select the same video as the first switching circuit 23. Therefore, the switching signal S3 is shared.

Here, if the first switching circuit 23 and the second switching circuit 24 are set to one input system side (each a side) in accordance with the switching signal S3, for example, The color signal S1 is output. Further, the video mode data from the second switching circuit 24 is sent to the determination unit 25, where the video mode is determined, and a determination signal S4 is output. Discriminator 25
For example, in the determination method in the above, the input video mode data is compared with the reference data Ds, and the determination is made based on the level of the video mode data with respect to the reference data Ds. From the above,
While the desired color signal is output from the first switching circuit 23,
A determination signal S4 indicating which mode is the video mode of the input video signal related to the color signal is obtained. The discrimination signal S4 is used as follows.

For example, if the display unit aspect ratio of the receiver is 1
In the case of 6: 9, when the video mode of the external video input selected and specified is a signal having a normal aspect ratio of 4: 3, the signal is projected as it is at 4: 3, or 1: 1.
It is used for a setting signal of a video processing circuit, a deflection circuit, and the like in the case where the image is enlarged to 6 to 9 and projected. Or an aspect ratio of 4
Although the signal is a pair 3 signal, when a predetermined range of the upper and lower portions of the screen is a black screen, the signal is enlarged in the upper and lower directions of the screen, and a video processing circuit, a deflection circuit, or the like for eliminating the upper and lower black screens is used. Used for setting signal of. Alternatively, when the original image is a signal having an aspect ratio of 16: 9 and an aspect ratio of 4: 3, the signal is used as a setting signal for a video processing circuit, a deflection circuit, and the like when displaying the original image at 16: 9. I do.

[0008]

However, in the configuration of the related art (FIG. 3), an A / D unit, a transistor for impedance conversion, an integration circuit (low-pass filter), and the like are provided for each video input system. doing. From the viewpoint of circuit rationalization, such redundant circuit configuration should be avoided, and it is desirable to commonly use them. Further, the cost can be reduced by this common use. The present invention has been made from such a viewpoint, and includes an A / D unit, a transistor for impedance conversion,
It is another object of the present invention to provide an input video mode discriminating apparatus having a common circuit configuration of an integrating circuit and streamlining the circuit configuration and reducing the cost.

[0009]

According to the present invention, there is provided a video input terminal for inputting a video signal which is obtained by separating an analog luminance signal and an analog color signal obtained by superimposing a DC voltage different according to a video mode. In a system comprising at least two systems, a first switching means for switching a color signal from each of the video input terminals, and a color signal from each of the video input terminals, interlocked with the first switching means, and Second switching means for switching to select color signals of the same system, signal impedance conversion means for converting the color signal from the second switching means into a low impedance signal and outputting the signal, and signal impedance conversion means DC voltage extracting means for extracting the DC voltage component from the input signal, and the input video signal based on the DC voltage from the DC voltage extracting means. Discriminating means for discriminating an image mode and outputting a discrimination signal, wherein the discriminating means discriminates the video mode of the signal selected by the first switching means. It is.

The second switching means has a required number of input terminals and one output terminal, and outputs a required color signal from each of the color signals input to each of the input terminals to the output terminal. It is composed of an electronic switch output from.

Alternatively, an NPN-type first transistor of a common-emitter type in which a signal for turning on or off the second switching means is input to the base, and one system of the color signal is input to the emitter. , A base and a collector of the first transistor are connected via a resistor, and a switching circuit including a PNP-type second transistor having a collector as an output terminal is provided for each system of the color signal. When a color signal of a system is selected, a signal for turning on the transistor may be applied to the base of the first transistor of the system.

In addition, a series circuit of a resistor for impedance matching and a capacitor for blocking DC voltage is provided between the signal line on the input side of the second switching means and the ground for each system of the color signals. .

The switching in the first switching means and the second switching means is performed by a switching signal based on a video selection operation.

Further, the DC voltage extracting means comprises an integrating circuit comprising a resistor and a capacitor of a required value in one or more stages.

Further, the discriminating means includes an A / D converter for converting the DC voltage component from the DC voltage extracting means into digital data corresponding to a voltage value, and a digital data from the A / D converter. And a comparator that determines by comparing with the reference data.

[0016]

Embodiments of the present invention will be described below with reference to the drawings based on embodiments. FIG. 1 is a main part circuit diagram showing an embodiment of the input video mode discriminating apparatus according to the present invention, and FIG. 2 is a main part circuit diagram showing another embodiment of the input video mode discriminating apparatus according to the present invention. In both embodiments, as in FIG. 3, two input systems are used, and only video signal switching is shown for color signal switching, and the luminance signal switching circuit is omitted. Hereinafter, the operation of the present invention will be described for each drawing.

(1) Embodiment of FIG. 1 The signal S1 input to each of the two inputs 1 and 2
And S2 are color signals (analog) in S terminal input
And a DC voltage indicating each video mode is superimposed thereon. The series circuit of resistors R1 and R2 and capacitors C1 and C2 provided between the signal lines of each system and the ground is mainly for impedance matching for resistors and for blocking DC voltage for capacitors. is there. The color signals S1 and S2 are input to a first switching circuit 1 and a second switching circuit 2, respectively. The former is input via capacitors C3 and C4, and the latter is directly input.

The two switching circuits 1 and 2 are switched in response to a common switching signal S3 and switched so as to select the same system. The switching signal S3 is a signal based on the video input system designation by the user operating the operation unit or the like. As a result, the selected color signal is output from the first switching circuit 1, and the same color signal from the second switching circuit 2 is input to the base of the transistor TR1 (emitter-follower configuration). A color signal having a reduced impedance is output. This emitter output passes through an integration circuit (low-pass filter) including a resistor R3 and a capacitor C5, and a DC component is extracted. In the figure, the integrating circuit has one stage, but a plurality of stages may be connected in cascade to increase the integration effect (filter effect).

The DC component is converted by the A / D converter 3 into digital data (for example, an 8-bit signal) corresponding to the DC voltage value. This digital data is referred to as video mode data. The video mode data is sent to the determination unit 4, where the video mode is determined, and a determination signal S4 is output.
The determination unit 4 may compare the input video mode data with the reference data Ds using a comparator, for example, and determine based on the level of the video mode data with respect to the reference data Ds. As described above, the desired color signal is set to the first switching circuit 1
, The determination signal S4 indicating the video mode of the input video signal relating to the color code is obtained, and the function equivalent to that in FIG. 3 is achieved.

(2) Embodiment of FIG. 2 In the embodiment shown in FIG. 2, the second switching circuit 2 in FIG. 1 is constituted by a transistor circuit. The same components as those in FIG. 1 are denoted by the same reference numerals. The color signal of input 1 is turned on / off by TR11 and TR12 shown in the figure, and input signal 2 is input by TR13 and TR14.
Turn on / off the color signal of This circuit operates such that when one is turned on, the other is turned off. for that reason,
Two types of switching signals, S11 for turning on and off TR12 and S12 for turning on and off TR14, are used. When S11 is an ON signal, S12 is an OFF signal. Specifically, the ON signal is a “high (H)” signal, and the OFF signal is a “low (L)” signal. Further, the first switching circuit 11 is provided with the S
Use a type that switches to the required side by a combination of 11 and S12. Specifically, when S11 is H and S12 is L, the input is on the input 1 side (a side), S11 is L and S12 is H
In the case of, it is the input 2 side (b side).

These switching signals S11 and S12, like the switching signal S3 in FIG. 1, are signals based on the video input system designation by the user operating the operation section or the like. From the above, for example, input 1
Is specified, S11 is H and S12 is L. Thereby, TR12 is turned on, and by this on, TR11 is turned on,
The color signal of input 1 is sent to the base of TR1. On the other hand, S
Since L is at L, TR14 is turned off, so that TR13 is also turned off, and the color signal of input 2 is cut off. Further, the first switching circuit 11 is on the input 1 side (a side) from the above. When input 2 is specified, the operation is the opposite of the above. As described above, as in the case of FIG. 1, the desired color signal is output from the first switching circuit 11, while the determination signal S4 indicating the video mode of the input video signal related to the color signal is obtained. Can be The operation of the discriminating unit 4 after TR1 is the same as that in FIG.

[0022]

As described above, according to the present invention, the circuit configuration of the conventional input video mode discriminating apparatus can be rationalized. That is, in the above-described conventional discriminating apparatus, a transistor for impedance conversion, an A / D converter, an integrating circuit (low-pass filter), and the like are provided for each input system. Thus, these A / D converters and the like can be commonly used, and the circuit configuration can be rationalized and the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a main part circuit diagram showing one embodiment of an input video mode discriminating apparatus according to the present invention.

FIG. 2 is a main part circuit diagram showing another embodiment of the input video mode discriminating apparatus according to the present invention.

FIG. 3 is a main part circuit diagram showing an example of a conventional input video mode discriminating apparatus.

[Explanation of symbols]

 1, 11, 23 First switching circuit 2, 24 Second switching circuit 3, 21, 22 A / D converter 4, 25 Discriminator S1, S2 Color signal S3 Switching signal S4 Discrimination signal Ds Reference data TR1, TR11 ~ TR14, TR21, TR22 Transistors R1, R2, R3, R21 ~ R24 Resistors C1 ~ C5, C21 ~ C26 Capacitors

Claims (7)

[Claims] An image display apparatus comprising at least two video input terminals for inputting a video signal obtained by separating an analog luminance signal and an analog color signal obtained by superimposing a DC voltage different according to a video mode. A first switching means for switching a color signal from each of the video input terminals; and a color signal from each of the video input terminals, interlocking with the first switching means, and selecting a color signal of the same system. Switching means, a signal impedance conversion means for converting the color signal from the second switching means into a low-impedance signal, and outputting the low-impedance signal, and a conversion of the DC voltage from the signal from the signal impedance conversion means. DC voltage extracting means for extracting a component, and the video mode of the input video signal is determined based on the DC voltage from the DC voltage extracting means. A video signal mode selected by the first switching means, wherein the video mode of the signal selected by the first switching means is determined by the determination means. 2. The second switching means includes a required number of input terminals and one output terminal, and outputs a required color signal from each of the color signals input to each of the input terminals to the output terminal. 2. The input video mode discriminating apparatus according to claim 1, wherein the input video mode discriminating device is constituted by an electronic switch output from the input switch. 3. An NPN-type first transistor of a common-emitter type to which a signal for turning on or off the second switching means is input to a base, and the one color signal system is input to an emitter. A switching circuit comprising a base and a collector of the first transistor connected via a resistor, and a PNP-type second transistor having a collector as an output terminal, provided for each system of the color signal;
2. The input video mode discriminating apparatus according to claim 1, wherein when a color signal of a required system is selected, a signal for turning on the transistor is applied to a base of the first transistor of the system. . 4. A series circuit of a resistor for impedance matching and a capacitor for blocking DC voltage is provided between a signal line on the input side of said second switching means and ground for each system of color signals. The input video mode discriminating apparatus according to claim 1, wherein: 5. The switching device according to claim 1, wherein the switching in the first switching means and the second switching means is performed by a switching signal based on a video selection operation. 3. The input video mode discriminating apparatus according to 3. 6. The input video mode discriminating apparatus according to claim 1, wherein said DC voltage extracting means comprises an integrating circuit comprising a resistor and a capacitor of a required value in one or more stages. 7. An A / D converter for converting a DC voltage component from the DC voltage extractor into digital data corresponding to a voltage value, and a digital data from the A / D converter. 2. The input video mode determining apparatus according to claim 1, wherein said input video mode determining apparatus comprises a comparator that determines by comparing with said reference data.