JPH0428195B2 - - Google Patents

Description

Detailed Description of the Invention (Technical Field) The present invention is provided in a television receiver equipped with a CRT having a main screen display part and a sub-screen display part for displaying images on a main screen and a sub-screen. The present invention particularly relates to erasing a child screen displayed in a child screen display area and switching parent and child screens at the same time.

(Prior Art) Such a television receiver has a main screen display portion 10 on its CRT 10, as shown in FIG.
a and a child screen display part 10b, and each display part 10a, 10b has a main screen (Mt. Fuji in the example).
There is a device that can display a sub screen (a flower in the example) separately. If the images are displayed on each screen as shown in FIG. 5 according to the image signals for the main screen and the child screen, there is no problem in image display.

By the way, if the video signal for displaying the image on the main screen does not exist due to reasons such as the TV broadcasting of the receiving channel being terminated, the main screen of Mt. Fuji will be displayed on the main screen display portion 10a as shown in FIG. The screen appears to be flowing without being displayed, and since a video signal is given to the sub-screen to the sub-screen display portion 10b, the sub-screen of the flower is displayed as an image, but in this case, the sub-screen is Since the parent screen that serves as the background is no longer synchronized, the child screen also displays an unstable image, which is not desirable, as shown in FIG.

(Object of the Invention) The present invention eliminates unstable video display in the main screen display area, switches the sub screen displayed in the sub screen display area so that it is displayed on the main screen display area, and The purpose is to erase the display part.

(Structure of the Invention) In order to achieve such an object, the present invention provides a CRT having a main screen display part and a sub-screen display part for displaying images of the main screen and the sub-screen, and a video source switching signal. In response, a video source switching switch switches and outputs the first and second video signals individually, and processes each video signal individually output from the video source switching switch and converts these into main screen video signals. A main screen video signal processing circuit and a sub screen video signal processing circuit each output as a video signal for a sub screen, and a video signal for the main screen and a sub screen from both of the video signal processing circuits are synthesized.
a synthesis circuit that outputs to the CRT; a signal detection circuit that detects the presence or absence of one of the video signals supplied to the main screen video signal processing circuit via the video source changeover switch and outputs the detection signal; and a control instruction signal. a control section that outputs the video source switching signal in response to the detection signal and outputs a sub-screen switching signal in response to the detection signal; and a sub-screen changeover switch that cuts off the connection with the synthesis circuit, and when the control section outputs the sub-screen changeover signal, it simultaneously provides a video source changeover signal to the video source changeover switch. The device is characterized in that the child screen displayed in the child screen display area on the CRT is erased and the parent and child screens are switched, and in this configuration, the signal detection circuit does not detect the video signal related to the parent screen. In this case, the control section outputs a sub-screen switching signal that cuts off the sub-screen video signal processing circuit and the synthesis circuit, and this sub-screen switching signal operates the sub-screen switching switch to shut it off. While the video of the child screen is not displayed on the screen display portion, the child screen displayed on the child screen display portion is switched to be displayed on the main screen display portion.

(Example) Hereinafter, the present invention will be described in detail based on an example shown in the drawings. FIG. 1 is a circuit block diagram of a screen switching and erasing device in a television receiver according to an embodiment of the present invention. By operating the operating section 4, a control instruction signal is given to the control section 5 from the operating section 4. The control unit 5 outputs a video source switching signal in response to a given control instruction signal. The operation unit 4 also outputs a reception channel selection signal corresponding to the operation. Tuner 2 uses VHF and UHF signals obtained from antenna 1 in response to the tuning signal.
The signal of that channel is selected and output from among the signals of the channel. The intermediate frequency processing circuit 3 processes the channel signal and outputs it as a video signal.

Reference numeral 6 denotes a video source switching switch which is operated in response to a video source switching signal from the control section 5, and is adapted to switch each video signal and output it individually according to this video source switching signal. This video source switching switch 6 consists of two switch sections 61 and 62, one switch section 61 has a first common contact a, two individual contacts b,
The other switch section 62 also includes a second common contact d and two individual contacts e and f. A video signal from a VTR connected to the television receiver of this embodiment is applied to the first common contact a as an external video signal input. The video signal of this television receiver is applied from the medium frequency processing circuit 3 to the second common contact d.

Reference numerals 7 and 8 denote a main screen video signal processing circuit and a sub-screen video signal processing circuit that process each video signal individually output from the video source switching switch 6 and output these as a main screen video signal and a sub-screen video signal, respectively. A signal processing circuit 9 is a synthesis circuit that synthesizes RGB video signals for the main screen and the child screen from both video signal processing circuits 7 and 8 and outputs the RGB signal to the color CRT 10. This color CRT10 is shown in Figures 5 and 6.
As shown in the figure, it has a main screen display section 10a and a sub-screen display section 10b for displaying images of a main screen and a sub-screen. Reference numeral 12 denotes a signal detection circuit that detects the presence or absence of a video signal applied to the small screen video signal processing circuit 7 via the video source changeover switch 6, and outputs the detection signal. And the control section 5
outputs a video source switching signal to the video source switching switch 6 as described above in response to a control instruction signal from the operation unit 4, and also switches the sub-screen in response to a detection signal from the signal detection circuit 12. It is designed to output a signal. Reference numeral 11 denotes a small screen switching switch that cuts off the connection between the small screen video signal processing circuit 8 and the combining circuit 9 in response to a small screen switching signal from the control section 5.

FIG. 2 is a concrete circuit block diagram of the signal detection circuit 12. A signal detection method in the signal detection circuit 12 is proposed, for example, in Japanese Patent Publication No. 16790/1983. The method described in this publication calculates the number of synchronization signals of a television signal,
It is determined whether or not the synchronization signal is a regular television signal based on whether or not a predetermined number of synchronization signals are present during a certain period of time. Signal detection circuit 1 in Figure 2
2 has a function of determining whether or not a synchronization signal in a video signal given to the small screen video signal processing circuit 7 is a regular synchronization signal using such a technique. In FIG. 2, reference numeral 13 detects the presence or absence of a video signal from the intermediate frequency processing circuit 3 of the television receiver given from the individual contact f of the video source changeover switch 6 using a synchronizing signal, and when there is a video signal, an ON signal is sent. 1, but outputs an OFF signal when there is no video signal.
Reference numeral 4 refers to a judgment unit that judges whether an OFF signal or an ON signal is input from the detection unit 13, and issues an output command when a count-up output is given from the counter 15, which will be described next.
4 performs a counting operation for a predetermined period of time after the OFF signal is given, and when the count value N reaches N=M after counting from N=0, the judgment section 1
4 is a counter that outputs a count-up output, and 16 is a detection signal output unit that outputs a detection signal in response to an output command from the determination unit 14.

Next, the operation will be explained according to the flowchart of the signal detection circuit 12 shown in FIG. The process starts when the power of the apparatus of this embodiment is turned on, and at step n1 initial settings are made and the counter 15 is reset. In step n2, it is determined whether the detection signal from the detection section 13 is an ON signal. When the main screen video signal is supplied to the main screen video signal processing circuit 7, the detection signal of the detection unit 13 is an ON signal, so the judgment unit 14 determines that it is YES and the step
Proceed to n3. At step n3, the counter 15 is reset. Step n1 again from step n8
Return to Next, the sub-screen video signal is transmitted to the signal detection circuit 1.
When the power is no longer supplied to the second detection unit 13, the step
At n2, it is judged as NO, and the count value N of the counter 15 is increased by +1. At step n5, it is determined whether the count value N is N=M.
If NO is determined, the process returns to step n1 in the same manner as described above.

Then, the count value N of the counter 15 is N=M
If so, it is determined as YES in step n5, and a detection signal is output from the detection signal output section 16 in step n6. That is, as can be seen from the explanation of this flowchart, when the count value of the counter 15 reaches N=M after the main screen video signal is no longer supplied to the main screen video signal processing circuit 7, in other words, when the count value of the counter 15 reaches N=M, the predetermined value is reached. A detection signal is provided from the signal detection circuit 12 to the control unit 5 with a delay time.
The control section 5 switches and operates the small screen changeover switch 11 and the video source changeover switch 6 based on this detection signal. As a result, the synthesis circuit 9 is not provided with the sub-screen video signal from the sub-screen video signal processing circuit 8, but only the main-screen video signal from the main-screen video signal processing circuit 7. In this way, on the color CRT 10, as shown in FIG. 5, an image of Mt. Fuji is initially displayed on the main screen display section 10a, and an image of flowers is displayed on the sub-screen display section 10b. Then, when the TV broadcast on the reception channel on the television receiver ends, the main screen video signal disappears, so the video is displayed on the CRT 10 as shown in Figure 6, but after a predetermined period of time, the video When the source selector switch 6 is switched from the illustrated position, the first common contact a
comes into contact with the individual contact b, and the second common point d comes into contact with the individual contact e. Then, as shown in FIG. 4, the flower image displayed on the child screen display section 10b is displayed on the main screen display section 10a, and the child screen display section 10b is erased.

(Effects of the Invention) As described above, according to the present invention, a sub-screen switching switch is provided which cuts off the connection between the sub-screen video signal processing circuit and the synthesis circuit in response to a sub-screen switching signal, and a control unit When outputting a sub-screen switching signal, at the same time, by giving a video source switching signal to the video source switching switch.
In addition to erasing the child screen displayed in the child screen display area on the CRT, the parent and child screens are also switched, so if the main screen video signal is lost, the child screen can be moved from the child screen display area of the CRT. At the same time, the child screen that was displayed on the child screen display area can be switched to the main screen and displayed. This eliminates unstable images where the main screen is not displayed on the main screen display area, and It is now possible to display the screen in the main screen display area.

[Brief explanation of drawings]

FIG. 1 is a circuit block diagram of a screen switching and erasing device for a television receiver according to an embodiment of the present invention, and FIG.
1 is a concrete circuit block diagram of the signal detection circuit of the device, FIG. 3 is a flowchart for explaining the operation of the embodiment device, and FIG. Figure 5 is a front view of the CRT when the sub-screen that was displayed in the sub-screen display area is displayed on the main screen.
Applicable when displaying a parent screen and a child screen on the main screen display part and child screen display part of a CRT, respectively.
6 is a front view of the core CRT in a state where unstable images are being projected on the main screen and child screen of the CRT shown in FIG. 5. In each figure, numeral 5 is a control unit, 6 is a video source selection switch, 7 is a main screen video signal processing circuit, 8 is a subscreen video signal processing circuit, 9 is a synthesis circuit, 10 is a color CRT, and 11 is a subscreen switch switch, 12 is a signal detection circuit.

Claims (1)

[Claims] 1. A CRT having a main screen display part and a sub-screen display part for displaying images of the main screen and sub-screens.
a video source switching switch that switches and outputs the first and second video signals individually in response to a video source switching signal; and a video source switching switch that processes each video signal that is individually output from the video source switching switch and outputs the first and second video signals individually. a main screen video signal processing circuit and a sub-screen video signal processing circuit that respectively output the video signal for the main screen and the video signal for the sub-screen, and the video signals for the main screen and the sub-screen from both of the video signal processing circuits. and a signal detection circuit that detects the presence or absence of one of the video signals supplied to the main screen video signal processing circuit via the video source selection switch and outputs the detection signal. a control unit that outputs the video source switching signal in response to a control instruction signal and outputs a sub-screen switching signal in response to the detection signal; and a control unit that outputs the sub-screen switching signal in response to the sub-screen switching signal; a sub-screen switching switch that cuts off the connection between the signal processing circuit and the combining circuit, and when outputting the sub-screen switching signal, the control section simultaneously causes the video source switching switch to switch the video source. 1. A screen switching and erasing device for a television receiver, characterized in that by applying a signal, a sub-screen displayed on a sub-screen display portion on the CRT is erased and a parent/sub-screen is switched.