JPS6212282A - Color television receiver - Google Patents

Abstract

PURPOSE:To display the image of a slave picture even where there is no video signal for a master picture by detecting the absence of the video signal input for the master picture by a signal presence/absence detecting circuit, inputting the synchronizing signal of a local synchronizing signal generator to a synchro nous separating circuit through a switching means, and reading and displaying a video signal for the slave picture. CONSTITUTION:When the video signal A for the master picture is not inputted, the signal presence/absence detecting circuit 1 detects that and a switch 3 is changed to the side of the local synchronizing signal generator 2 with its detection signal K, so that the horizontal and vertical synchronizing signal L of the local synchronizing signal generator 2 is inputted to a memory control 17 and a deflecting circuit 8 through the synchronous separating circuit 5. Then, the digital video signal M for the slave picture is read out of a video memory 16 on the basis of the synchronizing signal L. Consequently, when there is not the video signal for the master picture, the horizontal and vertical synchronizing signal L required for the slave picture display is obtained from the local synchronizing signal generator 2 and the slave picture is displayed normally without any disorder.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention stores a television video signal in a video memory, reads it out, combines it with a main screen video signal, and displays it on two TV screens. This relates to improvements to John receivers.

[Conventional technology]

Generally, when using a television receiver, for example, there are times when one wishes to monitor the video of a VTR or the like while watching a television program. In order to realize this kind of function, in conventional devices, a video signal to be monitored is stored in a video memory, and the video signal is combined with a main screen video signal and displayed. At this time, the video signal stored in the video memory is read out and displayed in accordance with the synchronization signal of the main screen video signal.

[The problem that the invention attempts to solve]

Conventional color television receivers are configured as described above, so, for example, when displaying a VTR playback image as the main screen and a TV broadcast program as a sub screen on two screens, it is possible to rewind the tape, fast forward, etc. If the reproduction signal of the VTR becomes silent, the synchronization of the monitor output video of the sub-screen is disrupted and normal display cannot be performed.

This invention has been made in view of the above-mentioned problems, and an object thereof is to provide a color television receiver that can normally display images on a sub-screen even when there is no video signal for the main screen. .

[Means for solving problems]

A color television receiver according to the present invention includes: a local synchronization signal generator that generates the same synchronization signal as the main screen video signal; a signal presence/absence detection circuit that detects whether or not the main screen video signal is input; A signal selection circuit that selects a synchronization signal of the screen video signal or a synchronization signal of the local synchronization signal generator, and a control means that controls reading of the sub-screen video signal and display of the composite image using either of the synchronization signals. It has been established that

[Function] In this invention, when the main screen video signal input disappears, the signal presence/absence detection circuit detects this, and the switching means synchronizes and separates the synchronization signal of the local synchronization signal generator instead of the main screen video signal. input to the circuit, whereby the video signal for the small screen in the video memory is read out in synchronization with the synchronization signal,
The image is displayed on the cathode ray tube in synchronization with the signal.

〔Example〕

Next, one embodiment of the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram of a television receiver having a two-screen display function according to an embodiment of the present invention.

In the figure, the chainer section, detection section, and audio section are omitted.

In the figure, 1 is a signal presence/absence detection circuit that detects the presence or absence of a main screen video signal input, 2 is a local synchronization signal generator that generates the same synchronization signal as the main screen video signal, and 3 is the signal presence/absence detection circuit 1. a switch (signal selection circuit) which receives the output of the main screen video signal A and the synchronization signal of the local synchronization signal generator 2 and inputs one of them to the video amplification circuit 4; 5 is the video amplification circuit; 4 separates the synchronizing signal C from the output B of the deflection circuit 8 and the memory control circuit 17.
13 is a video amplification circuit that amplifies the video signal for the child screen; 14 is a synchronization separation circuit that separates the synchronization signal G from the video signal for the child screen; 15 is the output of the video amplification circuit 13; 16 is a video memory that stores the digital video signal F that is the output of the A/D converter 15; 18 is a video memory that stores the digital video signal F that is the output of the A/D converter 15; D/A converter for converting into video memory No. 16, 6 is memory control circuit 1
A switch 9.10 selects the output B of the video amplifying circuit 4 or the output J of the D/A converter 18 and inputs one of them to the video output circuit 7 according to the signal 7 of the video output circuit 7. output.

These are a deflection cork and a cathode ray tube for displaying images by inputting the output of the deflection circuit 8, respectively.

Next, the operation will be explained.

The main screen video signal A is supplied to the video amplifier circuit 4 through the switch circuit 3, and its output signal B is supplied to the cathode ray tube 10 through the switch circuit 6, the video output circuit 7, and the like. The signal B is also supplied to the synchronization separation circuit 5, and its output, the horizontal and vertical synchronization signal C, is guided to the deflection circuit 8 and generates a sawtooth current that drives the deflection yoke 9. In this way, the TV image on the main screen is displayed on the cathode ray tube.

On the other hand, the decoded video signal, which is the video signal for the small screen, is amplified by the video amplification circuit 13, and its output signal E is sent to the A/D converter 1.
5, the signal is sampled in the horizontal and vertical directions according to the size of the child screen and converted into a digital signal F. The sampling clock signal 7H at this time is synchronized with the horizontal and vertical synchronization signal G separated from the child screen video signal by the synchronization separation circuit 14. Then, a write control signal N is supplied from the memory control circuit 17 to the video memory 16, whereby the digital video signal F
is stored in the video memory 16.

Reading is performed by a read control signal N from the memory control 17. This readout control signal N is sent to the main screen synchronization separation circuit 5 in order to superimpose and display the sub screen 20 on the main screen 30.
It was created in accordance with the horizontal and vertical synchronizing signal C from . The read signal M is converted into an analog signal J by the D/A converter 18 and output to the second side of the switch circuit 6. The switch 6 is connected to the contact 2 side during the memory read period by the signal I from the memory control circuit 17, so that the child screen 20 is superimposed on the main screen 30 as shown in FIG. displayed on the cathode ray tube 10.

Next, when the main screen video signal A is not input, this is detected by the signal presence/absence detection circuit 1, and the switch 3 is switched to the local synchronization signal generator 2 side in response to the detection signal K. As a result, the horizontal and vertical synchronizing signals of the local synchronizing signal generator 2 are inputted to the memory control 17 and the deflection circuit 8 via the synchronizing separation circuit 5. The digital video signal M for the sub screen is based on the above horizontal and vertical synchronization signal: 7 seconds/%1J167, 6Vt h l:B
8 h-FMiii &; J: Normally displayed based on the 18 signal.

In this way, according to this embodiment, when there is no video signal for the main screen, the horizontal and vertical synchronization signals C necessary for displaying the sub-screen can be obtained from the local synchronization signal generator, so the sub-screen can be displayed without any disturbance. .

〔Effect of the invention〕

As described above, according to the color television receiver of the present invention, when there is no input of the main screen video signal, the sub-screen video signal is read out from the video memory based on the synchronization signal from the local synchronization signal generator. and a sub-screen display, so while the main screen is displaying a video being played from a VTR, etc.
Even when a video signal from the VTR cannot be obtained during tape rewinding, fast forwarding, etc., the sub-screen can be displayed normally.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a television receiver according to an embodiment of the present invention, and FIG. 2 is a diagram showing how a child screen is inserted into a main screen and displayed.

Claims (1)

[Claims] (1) In a color television receiver that combines and displays a sub-screen video signal stored in a video memory with a main-screen video signal, a local synchronization signal that generates the same synchronization signal as the main-screen video signal. a generator; a signal presence/absence detection circuit for detecting the presence or absence of the main screen video signal; and a synchronization signal separated from the main screen video signal or a synchronization signal from the local synchronization signal generator according to the detection result. A color television set comprising: a signal selection circuit for selecting a synchronization signal; and a control means for controlling readout of the sub-screen video signal in the video memory and display of the combined screen using the selected synchronization signal. john receiver.