JPH0715683A - Video signal switching circuit - Google Patents

Abstract

PURPOSE:To automatically replace the video images of master and slave screens at the time of commercials. CONSTITUTION:An input selection switch control circuit 5 judges that the commercial is started when a second discrimination signal 14 from a sound multiplex mode discrimination circuit 4 changes from monophonic broadcasting to stereo broadcasting for instance, controls an input selection switching circuit 6 and replaces input video signals to be video output 20 and 21 for the master and slave screens. Further, when the discrimination signal 14 returns from the stereo broadcasting to the monophonic broadcasting, the input video signals to be the video output 20 and 21 for the master and slave screens are replaced inversely this time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
It's called TV. ) A video signal switching circuit for selecting a video signal displayed on a screen in a receiver.

[0002]

2. Description of the Related Art A picture-in-picture type video signal switching circuit used in a conventional TV receiver will be described with reference to FIG. A TV video signal 101 demodulated from a video intermediate frequency, a video signal 102 from a VTR, a video signal 103 of BS and another video signal 104 are input to the input selection switch circuit 100. The input selection switch circuit 100 selects the parent screen image signal 105 and the child screen image signal 1 from the input image signals.
06 is selected and output. Input selection switch circuit 110
Receives the input selection signal 120 and outputs the selection signal 120
The selection operation of the input selection switch circuit 100 is controlled accordingly.

In the above-mentioned conventional video signal switching circuit, the video of the TV video signal 101 is displayed on the main screen, and the video of the video signal 102 from the VTR, for example, is displayed on the sub screen, and the main screen becomes commercial. When you want to switch the images of the parent screen and the child screen, input selection signal 1
I have to send 20. Next, when the commercial is finished, the input selection signal 120 must be sent again when the images of the parent screen and the child screen are to be interchanged.

[0004]

In the conventional video signal,
If you want to replace the parent and child screen images when the parent screen image becomes commercial, you must send an input selection signal. Next, at the end of the commercial, it was troublesome that the input selection signal had to be sent again when the images of the parent screen and the child screen were to be exchanged in reverse.

It is an object of the present invention to provide a video signal switching circuit which automatically switches the video of the parent-child screen when the video of the parent screen becomes commercial and when it is finished.

[0006]

An audio signal demodulating circuit for demodulating a main audio signal from an input signal including a video signal and an audio signal, and an output of the audio signal demodulating circuit are input to generate an audio multiplex mode from the input. An audio multiplex mode discriminating circuit for discriminating and outputting a discriminating signal, a video signal demodulating circuit for demodulating a video signal from the input signal, and a plurality of video signals including the video signal from the video signal demodulating circuit are inputted. An input selection switch circuit for selectively outputting a video signal to be displayed on the screen from the inside, and controlling a selection output operation of the input selection switch circuit in response to a change in the input selection signal or the discrimination signal from the audio multiplex mode discrimination circuit. An input selection switch control circuit is provided.

[0007]

The input selection switch control circuit controls the selection operation of the input selection switch circuit in response to the change of the discrimination signal from the voice multiplex mode discrimination circuit. As a result, the input selection switch circuit selects whether to output the video signal from the video signal demodulation circuit or another video signal.

[0008]

1 is a block diagram showing a first embodiment of a video signal switching circuit according to the present invention. Hereinafter, description will be given with reference to FIG. The video signal demodulation circuit 1 demodulates the video signal from the input 10 of the video and the intermediate frequency and generates one input video signal 11 of the input selection switch circuit 6 described later.
The audio signal demodulation circuit 2 performs the FM demodulation of 4.5 MHz, extracts the main audio signal 12 from the input 10 of the intermediate frequency of video and audio, and extracts the main audio signal 12 from the next stage. -Input to the discrimination circuit 4. Multiple audio mode
The mode discriminating circuit 4 discriminates, based on the input audio signal 12, whether the currently received audio multiplex mode is a monaural broadcast, a stereo broadcast or a bilingual broadcast.
The discrimination signal 13 is added to the control terminal of the audio multiplex demodulation circuit 3. When the first determination signal 13 indicates that monaural broadcasting is being received, the audio multiplex demodulation circuit 3 outputs the main audio signal to both the left and right speakers as it is for monaural reproduction. When the discrimination signal 13 indicates that the stereo broadcast is being received, the audio multiplex demodulation circuit 3 demodulates the sub audio signal included in the input main audio signal 12 and outputs L (left) to the left speaker. ) Audio signal is output, and the R (right) audio signal is output to the right speaker for stereo reproduction. When the discrimination signal 13 indicates that a bilingual broadcast is being received, the audio multiplex demodulation circuit 3 demodulates the sub foreign language included in the input main audio signal 12 and the demodulated sub foreign language. By outputting a word or a main voice signal (for example, Japanese) to the left and right speakers, bilingual reproduction is performed.

The input selection switch circuit 6 includes the above-mentioned TV.
In addition to the video signal 11, the video signal 17 from the VTR, SB
The video signal 18 and the other video signal 19 are input. The input selection switch circuit 6 receives the video signal 1 according to the control signal 16 from the input selection switch control circuit 5 described later.
1 is used as the parent screen video output 20, and one of the other video signals 17 to 19 is used as the slave screen video output 21.

The input selection switch control circuit 5 receives an input selection signal 15 for instructing the replacement of the images on the parent-child screen, depending on the viewer's will. When the input selection signal 15 is input, the input selection switch control circuit 5 sends the output control signal 16 to the input selection switch circuit 6. The input selection switch circuit 6 receives the control signal 16 and exchanges the input video signals to be the video outputs 20 and 21 for the parent and child screens. Further, the second discrimination signal 14 is inputted from the voice multiplex mode discrimination circuit 4 to the input selection switch control circuit 5. The second determination signal 14 is a signal indicating whether or not the audio signal of the main screen is receiving, for example, a stereo broadcast.
If the second determination signal 14 is a signal indicating that the broadcast is stereo broadcasting, the input selection switch control circuit 5 determines that commercialization has occurred and outputs a control signal 16. As a result, the input selection switch circuit 6 exchanges the input video signals to be the parent-child screen video outputs 20 and 21. next,
If the second determination signal 14 is a signal indicating that it is not a stereo broadcast, the input selection switch control circuit 5 determines that the commercial has ended, and outputs the control signal 16. As a result, the input selection switch circuit 6 reverses the input image signals to be the parent-child screen image outputs 20 and 21.

That is, when the image on the main screen is broadcast with a monaural audio signal, the audio signal often changes to a stereo broadcast when it becomes a commercial signal. Control circuit 5
The input selection switch circuit 6 can be switched by controlling the.

On the contrary, when the commercial ends, the stereo broadcast is changed to the monaural broadcast, so that the input selection switch circuit 6 can be switched to the original state.

As described above, when the image on the parent screen becomes a commercial and when the commercial ends, the images on the parent and child screens can be automatically replaced.

The second discrimination signal 14 may be a signal indicating whether or not a bilingual broadcast is being received. In this case, when the second discrimination signal 14 indicates a bilingual broadcast, the input selection switch control circuit 5 outputs the video signal 11 as a coma.
Judge that the video signal is a normal video signal without char. Then, when the second determination signal 14 indicates that it is not a bilingual broadcast, the input selection switch control circuit 5 causes the video signal 1
It is judged that the commercial has entered 1 and the commercial has ended.

That is, when a foreign movie is displayed on the main screen, since it is usually broadcast in two languages, when it becomes a commercial, it will change to stereo or monaural sound. Therefore, the input can be selected by discriminating this change.

FIG. 2 is a block diagram showing a second embodiment of the video signal switching circuit of the present invention. The difference from the first embodiment is that the extraction of the video output for the child screen is omitted. The input selection switch control circuit 5 uses the second determination signal 1
When it is determined by 4 that the commercial is not received, the input selection switch circuit 6 outputs the video signal 11 as the video output 30. When the input selection switch control circuit 5 determines that the commercial is being received by the second determination signal 14, the input selection switch circuit 6 selects one of the video signals 17 to 19 during the commercial. Video output 30
And When the commercial ends, the input selection switch circuit 6 outputs the video signal 11 as the video output 30 again. The same parts as those in the first embodiment are designated by the same reference numerals, and the operation is the same, and therefore the description thereof is omitted.

[0017]

According to the present invention, the image on the main screen is displayed as a frame.
When it becomes a shar and when the commercial ends
The images on the parent and child screens can be switched automatically.

Further, the input selection switch circuit can output another video signal during the commercial, and automatically output the original video signal after the commercial ends.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first embodiment of a video signal switching circuit of the present invention.

FIG. 2 is a block diagram showing a second embodiment of the video signal switching circuit of the present invention.

FIG. 3 is a block diagram showing a conventional video signal switching circuit.

[Explanation of symbols]

 1 ... Video signal demodulation circuit 2 ... Audio signal demodulation circuit 3 ... Audio multiplex demodulation circuit 4 ... Audio multiplex mode determination circuit 5 ... Input selection switch control circuit 6 ... Input selection switch circuit

Claims (2)

[Claims] 1. An audio signal demodulation circuit for demodulating an audio signal from an input signal including an image signal and an audio signal, and an output of this audio signal demodulation circuit is input to determine an audio multiplex mode from the input and output a determination signal. Voice multiplex mode discriminating circuit,
A video signal demodulation circuit for demodulating a video signal from the input signal, and an input selection switch circuit for inputting a plurality of video signals including the video signal from the video signal demodulation circuit and selectively outputting a video signal to be displayed on the screen A video signal switching, characterized by comprising an input selection switch control circuit for controlling a selective output operation of the input selection switch circuit in response to a change in an input selection signal or a discrimination signal from the audio multiplex mode discrimination circuit. circuit. 2. The input selection switch circuit normally selects the video signal from the video signal demodulation circuit as a parent screen video output and selects the other video signal as a child screen video output. Swap the two video signals that become the parent-child screen video output by the first change of the discrimination signal, and swap the two video signals that become the parent-child screen video output again by the second change of the discrimination signal. The video signal switching circuit according to claim 1, wherein the normal selection operation is resumed.