JPH05908B2 - - Google Patents

Description

1. A video signal converting device comprising: an output prohibition signal output means 23 for supplying an output prohibition signal to a section.

[Detailed description of the invention]

<Industrial Application Field> The present invention is applicable to RGB signals from a computer,
The present invention relates to a video signal converter (digital converter) capable of converting a video signal from a video device such as a television, VTR, video disc, or video camera and a mixing signal of the RGB signal into an NTSC composite video signal.

<Prior art> By combining a personal computer and a color television receiver, television video signals and
There is a technology that superimposes computer signals and displays images.

In such superimposition, synchronization is established between the video signal of the color television receiver and the RGB signal of the personal computer in order to prevent the computer screen from flowing on the screen.

By the way, video signals from color television receivers, video discs, video cameras, etc.
Video signals from external video equipment such as VTR,
While inputting the RGB signals from the personal computer to the corresponding RGB input terminals, one of the two video signals is selected, and the selected video signal is input to the corresponding RGB input terminal. There is a known digital telopper that mixes a signal with the RGB signal and then converts it into an NTSC composite video signal and outputs it (Monthly magazine "Television Technology", Denshi Gijutsu Publishing Co., Ltd., July 1983). (See pages 19 to 30 of the monthly issue).

When a screen is projected on the screen of a color television receiver using the above composite video signal (signal for superimpose mode) output from such a digital television receiver, the screen is based on the video signal of the external video device. Screen (external video equipment screen)
Alternatively, it becomes a superimposed mode screen of a television screen based on the video signal of a color television receiver and a computer screen based on RGB signals.

In this case, the color television receiver is in a mode (video input mode) in which the composite video signal from the digital television receiver is inputted to the external video input terminal and projected on the screen.
In this case, since the color television receiver scans based on the composite video signal from the telopper input from its external video input terminal, it is natural that the color television receiver will scan based on the composite video signal from the telopper input from its external video input terminal. The synchronization relationship between the receivers is the same.

However, if the color television receiver is not in video input mode, i.e. in a mode in which it accepts its own television tuner source and projects it on the screen (television tuner mode), then the composite video from the digital television receiver is The signal is not captured inside the color television receiver, and at this time, a state occurs in which the synchronization of only the color television receiver is inconsistent with the synchronization relationship among the external video equipment, personal computer, and digital television receiver.

<Problems to be Solved by the Invention> By the way, in a combination device of a color television receiver and a personal computer, an RGB signal from the personal computer is inputted from the RGB input terminal of the color television receiver,
When the computer input mode is specified on a color television receiver, the computer screen using the RGB signal is displayed, or when the superimpose mode is specified on the color television receiver, the video signal of the color television receiver and the RGB signal are displayed. It is possible to display a superimposed mode screen with a signal.

By the way, by further combining such a combination device with the above-mentioned digital television monitor and external video equipment, the screen in superimposition mode of the video signal of the external video equipment and the RGB signal of the personal computer can be received by the color television. There is no problem when the color television receiver is in the video input mode, in which the composite video signal from the digital television receiver is input from the external video input terminal in order to be displayed on the screen of the machine, but if the color television receiver is in the television tuner mode. , and when the superimpose mode is specified, the above composite video signal from the digital television receiver is not imported, but the RGB signal is input from the RGB input terminal of the color television receiver. .

However, when the video signal of an external video device and the RGB signal of a personal computer are synchronized via a digital monitor, the RGB
The signal is out of synchronization with the color television receiver. Under such a synchronization relationship, when the superimpose mode is specified and the RGB signal is received from the RGB terminal of the color television receiver, the RGB signal is set to the television tuner mode. Since the computer screen is not synchronized with the TV video signal of the color television receiver, the computer screen based on the RGB signal will flow on the screen, making the screen very difficult to see.

The present invention has been made in view of the above-mentioned problems, and the present invention has been made in view of the above-mentioned problems. When the superimpose mode is specified on the receiver side and the TV tuner mode is selected, the color television receiver receives the RGB input from the RGB input terminal.
By cutting the signal, the computer screen based on the RGB signal is not displayed on the screen of the color television receiver, and the above-mentioned problem where the computer screen is displayed in a flowing manner on the screen can be avoided. The purpose is to eliminate it.

<Means for Solving the Problems> In order to achieve such an object, the video signal conversion device of the present invention has an RGB input terminal to which an RGB signal from a personal computer is input, and a color television receiver. an RGB output terminal for outputting RGB signals from the personal computer; and the color television receiver;
A first video input terminal receives a video signal from an external video device such as a VTR or video camera, and mixes the RGB signal from the personal computer with the video signal from the color television receiver or external video device. A video signal converter having a video output terminal for outputting an NTSC composite video signal, and capable of mixing a video signal from a color television receiver or an external video device with an RGB signal from a personal computer. A group of gate circuits each receives an RGB signal from a personal computer via an RGB input terminal into one input section, and an RGB signal output prohibition signal is input into the other input section, and a video signal from the external video device. is input to the second video input terminal, and when the color television receiver is set to superimpose mode in which external RGB input is superimposed and displayed on the video screen, the color television a sync signal input terminal into which a sync signal is input from the color television receiver; and a first detection signal indicating that the color television receiver is in a superimpose mode based on the sync signal obtained from the sync signal input terminal. a superimpose mode detection means that outputs a second detection signal when a video signal from the external video device is detected based on a signal input through the second video signal input terminal; signal detection means; and cut signal output means for outputting a cut signal when a first detection signal is input from the superimpose mode detection means and a second detection signal is input from the video signal detection means. and transmitting the output prohibition signal to the other input section of the gate circuit group, which prohibits the output of the RGB signal from the gate circuit group to the RGB output terminal when the cut signal is input from the cut signal output means. The present invention is characterized in that it includes an output prohibition signal output means for supplying an output prohibition signal.

<Function> In the video signal conversion device having the above configuration, first, the RGB signal from the personal computer input to the RGB input terminal is applied to one input section of each of the gate circuit groups. When an output prohibition signal that prohibits the output of that RGB signal is input to the other input section of each of the gate circuit groups, that RGB signal is
It is now prohibited to output from the RGB output terminal.

In such a video signal conversion device, the present invention provides a superimpose mode detection means based on a synchronization signal given from the color television receiver when the color television receiver is designated as the superimpose mode. A first detection signal indicating that the color television receiver is in superimpose mode is output from the first detection signal. Further, when a video signal from an external video device is detected based on a signal input via the second video signal input terminal, a second video signal is output from the video signal detection means.
A detection signal is output. A cut signal is output from the cut signal output means to which the first and second detection signals are input, and in response to the cut signal, a prohibition signal is output from the prohibition signal output means to the other input of the gate circuit group. When given to the department,
Output of RGB signals via the RGB output terminal is prohibited.

Therefore, in the present invention, when the video signal from the external video device and the RGB signal of the personal computer are in the superimpose mode and synchronization is established between the external video device and the personal computer, color When the television receiver is in its synchronized mode,
Since RGB signals from a personal computer are not input to color television receivers,
The computer screen based on the RGB signal from the personal computer is no longer displayed, and as a result, the computer screen based on the RGB signal is no longer displayed.

<Example> Hereinafter, an example of the present invention will be described in detail with reference to the drawings. The figure is a circuit diagram of a video signal converter (digital converter) according to an embodiment of the present invention.

In the figure, 1 is a digital terrorist, 4,
5 and 6 are respectively 2a, 2b, 2c, 3a, 3
A video camera, a VTR, and a color television receiver are individually connected to the video signal input terminal group consisting of b and 3c. Here, the video camera 4 and VTR 5 constitute external video equipment,
Further, the video signal input terminals 2a, 2b, and 2c constitute a first video signal input terminal to which a first video signal is input from an external video device, a color television receiver 6, in the present invention. 3
a and 3b constitute a second video signal input terminal to which a second video signal is input from an external video device.

7a and 7b are RGB input terminals to which RGB signals are input from the personal computer 8;
10 is an RGB output terminal that outputs an RGB signal to the color television receiver 6; 10 is an input terminal to which a synchronization signal is input from the color television receiver 6;
11 is a composite video signal created by an encoder (not shown) inside the digital television 1 and is sent to the VTR 1.
2 and a color television receiver 6, respectively. The color television receiver 6 and the personal computer 8 are combined with each other to constitute a combination device 13 that superimposes a television screen and a computer screen on the screen of the color television receiver 6.

14 is each input terminal 2 of one input terminal group 2
A first input selector switch 16 switches each video signal inputted from a, 2b, and 2c and supplies it to the mixing circuit 15, and 16 is a mode selector switch, and the signal from this moder selector switch 16 is sent to the output terminal 11. Given.

When the mode selector switch 16 is switched to the individual contact 16a side, the video camera 4, VTR
5. Each video signal from the color television receiver 6 is sent to the output terminal 11 via an encoder (not shown).
and when switching to the individual contact 16b side, the mixed output of the selected video signal and the RGB signal from the personal computer 8 is converted into a composite video signal by an encoder. It is then applied to the output terminal 11. In this case, a circuit for converting the mixing output into a composite video signal, such as an encoder, a synchronization signal generator, and another mixing circuit, etc., is provided on the output side of the mixing circuit 15; Omitted. In addition, individual contact 1
6c, the RGB signal is similarly converted into a composite video signal and applied to the output terminal 11.

17 is a second input changeover switch, and this second input changeover switch 17 connects the video camera 4 through the input terminal 3a and the buffer gate 18a.
, an individual contact 17b connected to the VTR 5 via the input terminal 3b and the buffer gate 18b, and an individual contact connected to the color television receiver 6 via the input terminal 3c and the inverter gate 18c. 17c. 17d is a movable terminal of the second input changeover switch 17. First and second input selector switch 1
4 and 17 are designed to be linked.

The second input selector switch 17 selectively inputs the video signal input via the second video signal input terminals 3a, 3b or the video signal input via the video signal input terminal 3c in the present invention. It constitutes input switching means.

Reference numeral 19 indicates a signal input to the color television receiver 6 via the input terminal 10 when the color television receiver 6 is specifically designated to superimpose mode.
This is a synchronization signal detection circuit that detects a synchronization signal that is input to the digital teloper 1 from the input terminal.

In order to obtain a superimposed mode screen of the video signals of the external video devices 4 and 5 and the RGB signals of the personal computer 8 on the screen of the color television receiver 6, a diagram provided in the color television receiver 6 is used. When the superimpose mode switch is operated to disable the superimpose mode, a synchronizing signal is output from the color television receiver 6 to the synchronizing signal detection circuit 19 in response to this operation. The synchronizing signal detection circuit 19 provides a high level output to the inverter gate 20 by detecting this synchronizing signal. Therefore, when the superimpose mode is specified, the inverter gate 20 outputs a low level output, and when the superimpose mode is not specified, a high level output is output. Here, the synchronization signal detection circuit 19 and the inverter gate 20 constitute a superimpose mode detection means inside the digital detector 1.

In the color television receiver described above, the synchronization signal is not output when the superimpose mode is not specified, and therefore the synchronization signal detection circuit 19 configures a simple integration circuit to If there is a signal, a high level output is output, and if there is no synchronization signal, a low level output is output.

The external video equipment video signal and the color television receiver video signal are applied to an inverter gate 21 as video signal detection means via the second input changeover switch 17. In this case, input terminal 3
Since the video signals from the external video equipment and the color television receiver are set to high level by the resistor connected to the +B power supply, they are directly applied to the inverter gate 21 from the buffers 18a and 18b. The video signal given to the inverter gate 21 via the inverter gate 18c is output as a high level output from the inverter gate 21, whereas the video signal given to the inverter gate 21 via the inverter gate 18c is output as a high level output from the inverter gate 21. will be done.

22 is Noah Gate, this Noah Gate 22
The output signals of the inverter gates 20 and 21 are applied to both input terminals of the inverter gates 20 and 21. The high level output from the NOR gate 22 is due to the low level output from the inverter gate 20 in the superimpose mode and the low level output from the video signal from the inverter gate 21. Only time will tell. This NOR gate 22 constitutes a cut signal output means for cutting so that the RGB signal is not outputted from the digital television receiver 1 to the color television receiver 6 when the superimpose mode is specified.

That is, this NOR gate 22 receives a low level output from the synchronizing signal detection circuit 19 as a superimpose mode detection means and an inverter gate 20 as a first detection signal, and a low level output from an inverter gate 21 as a video signal detection means. A high level cut signal is output when each level output is input as a second detection signal.

When the high-level cut signal is output from the NOR gate 22, the transistor 23, which serves as cut signal output prohibition means, is turned on. The collector of this transistor 23 is connected to one input part of AND gate groups 24a, 24b, and 24c. When this transistor 23 is turned on, its collector is pulled to a low level. AND gate 24a, 24b, 2
The other input section of each 4c is individually RGB
Personal computer 8 via input terminal 7b
It is connected to the output line of the RGB signal input from. Therefore, when this transistor 23 is turned on, its collector potential becomes low level, so that the AND gate groups 24a and 24
Since the gates b and 24c are closed, the RGB signals are cut off at the AND gates 24a, 24b, and 24c, and are not applied to the color television receiver 6 via the RGB output terminal 9. Therefore, when the external video equipment 4, 5 and the personal computer 8 are in the superimpose mode and the external video equipment 4, 5 and the personal computer 8 are synchronized, the color television receiver 6 Even when the superimpose mode is specified and the TV tuner mode is set, the personal computer 8
The RGB signals are cut off and are not sent to the color television receiver 6.

With the above circuit configuration, the following can be said in the present invention.

That is, the first input changeover switch 14 is connected to the input terminal 2a or 2b side, and the mode changeover switch 1 is connected to the input terminal 2a or 2b side.
6 is switched to contact 16b, the video signal from the video camera 4 or VTR 5 is mixed with the RGB signal from the personal computer 8 in the mixing circuit 15, and then converted into a composite video signal by the encoder. and the color television receiver 6 via the output terminal 11.
is applied to the external video input terminal. In this case, the screen of the color television receiver 6 is in a mode in which a screen (superimpose mode screen) based on a composite video signal of the video signal from the external video device and the RGB signal from the personal computer 8 is displayed. There is.

However, when the color television receiver 6 is in the television tuner mode, the composite video signal is not input to the color television receiver 6. On the other hand, the RGB signal is transmitted to external video equipment 4 and 5.
Although synchronization is established with the video signal of the color television receiver 6, synchronization is not established with the television screen of the color television receiver 6. outputs an RGB signal from the RGB output terminal 9 and inputs it to the RGB input terminal on the television receiver side, and the computer screen based on the RGB signal is displayed on the screen of the color television receiver 6 as if the image was flowing. However, in this embodiment, the RGB signals are cut off from being output from the output terminal 9, thereby preventing the computer screen from being displayed on the screen in a flowing manner.

<Effects of the Invention> As described above, according to the present invention, a composite video signal of a video signal from an external video device and an RGB signal from a personal computer is output to a color television receiver via a digital television receiver. When the color television receiver is in a mode that projects a superimpose mode screen based on the superimpose mode screen on the screen of the color television receiver, the color television receiver enters a TV tuner mode that is not an external video input mode that displays the superimpose mode screen. If the video signal from the external video device and the RGB signal from the personal computer are not synchronized, the RGB signal from the personal computer will not be sent directly to the color television receiver. The computer screen based on the RGB signal is no longer displayed on the screen of the digital receiver, and as a result, the computer screen is prevented from being displayed.

[Brief explanation of the drawing]

The figure is a circuit diagram of a video signal conversion device according to an embodiment of the present invention. 1...Video signal converter (digital converter), 3a, 3b, 3c...Video signal input terminal,
4, 5...Video camera as external video equipment,
VTR, 6...Color television receiver, 7b
... RGB input terminal, 8 ... Personal computer, 9 ... RGB output terminal, 17 ... Second input selection switch, 19 ... Synchronization signal detection circuit, 2
0, 21... Inverter gate, 22... NOR gate, 23... Transistor, 24a to 24c...
...Gate circuit group.

Claims (1)

[Scope of Claims] 1. RGB input terminals 7a and 7b into which RGB signals from the personal computer 8 are input; RGB output terminal 9 which outputs the RGB signals from the personal computer to the color television receiver 6; color television receiver 6,
A first video input terminal 2a to which a video signal is input from an external video device such as a VTR 5 or a video camera 4;
2b, 2c, and a video output terminal 11 that outputs an NTSC composite video signal obtained by mixing the RGB signal from the personal computer 8 and the video signal from the color television receiver 6 or the external video device, In a video signal conversion device that is capable of mixing video signals from a color television receiver or external video equipment with RGB signals from a personal computer, the RGB signals from the personal computer 8 are respectively input via the RGB input terminal 7b. Gate circuit group 24 into which an output prohibition signal of an RGB signal is input to one input part and to the other input part
a, 24b, 24c, second video input terminals 3a, 3b into which video signals are input from the external video devices 4, 5, and RGB signals input from the outside in the color television receiver 6 as video signals. a sync signal input terminal 10 to which a sync signal is input from the color television receiver 6 when a superimpose mode is specified in which the screen is displayed superimposed on the sync signal obtained from the sync signal input terminal 10; a first indicating that the color television receiver 6 is in superimpose mode based on a synchronization signal;
superimpose mode detection means 19, 20 that output detection signals; a video signal detection means 21 that outputs a second detection signal when detected; the superimpose mode detection means 19;
a cut signal output means 22 that outputs a cut signal when a first detection signal is input from the video signal detection means 20 and a second detection signal is input from the video signal detection means 21; When the cut signal is input, the gate circuit groups 24a, 24
The output prohibition signal for prohibiting the output of RGB signals from the RGB output terminals 9 to the RGB output terminals 9 is input to the other input of the gate circuit group 24a, 24b, 24c.