JPH0317436B2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Field of Application The present invention is designed to display a character multiplex signal inserted in the vertical retrace period of a television signal on a television receiver employing a digital circuit. The present invention relates to a television signal processing device.

Conventional configurations and their problems In recent years, with the development of new media equipment, the function of television receivers as monitors has been increasing. As an example of these new media devices, still images and character information (hereinafter referred to as a character multiplex signal) are transmitted during the vertical retrace period of a television signal.
Teletext broadcasting that inserts and transmits text has already been put into practical use. Currently, the text multiplex signal receiving device is configured as an adapter, which extracts the text multiplex signal from the television signal and projects it on a cathode ray tube screen instead of the normal video signal, or superimposes it on the video signal. It is projected onto a cathode ray tube screen.

First, the configuration and operation of a text multiplex reception device using an analog television receiver will be described. Figure 1 shows this situation. 1 in the diagram
is a television receiver that includes a video detection circuit and outputs a composite video signal. 2 is a brightness amplification circuit and a color demodulation circuit, 3 is a video output amplification circuit, 4 is a color cathode ray tube, 5 is a character multiplexing adapter with RGB connection method,
A keyboard 6, a teletext decoder section 7 which extracts a character multiplex signal from the vertical retrace interval of the composite video signal, stores it, reads it out, decodes it and outputs it, and an RGB signal indicating this character multiplex signal, a brightness amplification circuit, and a color. Output from demodulation circuit 2
Video switching circuit 8 that switches between and outputs RGB signals
Equipped with. The output of the video switching circuit 8 is projected onto the color cathode ray tube 4 via the video output amplification circuit 3. To further explain the function of the teletext decoder section 7, it selects the desired signal specified by the keyboard 6 from among the character signals of a large number of programs and pages that are sequentially transmitted during the vertical blanking period, and selects the desired signal specified by the keyboard 6. The information is written into a refresh memory according to the display mode, and read out repeatedly during the field period of the television receiver, thereby displaying the text and graphic information on the television receiver.

Recently, so-called digital television receivers have been proposed, which convert television signals into digital signals, process them, and then reconvert them into analog signals to reproduce images. This television receiver converts the detected composite video signal into a digital signal, and after signal processing, converts it back into an analog signal and sends it to a color cathode ray tube. When receiving a text multiplex signal using this digital television receiver and a text multiplex adapter, the following problems occurred. That is,
For digital circuits, the signal processing time is approximately
5 μsec, which is longer than the analog circuit's signal processing time of approximately 0.5 μsec, so the character multiplex signal (RGB signal) supplied from the character multiplex adapter to the color cathode ray tube is slower than the digitally processed composite video signal. Therefore, the phase will advance relatively. For this reason, the horizontal position of the screen displayed based on the synchronization signal included in the composite video signal is not in the correct position, and the left edge of the text and graphics information is missing due to the horizontal shift, making it impossible to confirm the text and graphics information. This will cause inconvenience.

OBJECTS OF THE INVENTION The present invention solves the above-mentioned problems and provides a television signal processing device that can prevent screen defects from occurring when a text multiplex receiver is connected to a digital television receiver. The purpose is to provide.

Composition of the Invention A television signal processing device according to the present invention inputs a composite video signal from a digital television receiver to a text multiplex receiver, and outputs a composite video signal from the output signal from the text multiplex receiver. The video signal is input to the television receiver through a delay device having a delay time equal to 1H minus the delay time required by the digital signal processing circuit, and there is a delay between the synchronization signal and the character multiplex signal. It is possible to correct the misalignment and display text and graphic information in the correct horizontal position.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 2 to 4. FIG. 2 is a block diagram of a television signal processing apparatus in one embodiment of the present invention.
In FIG. 2, 10 is a digital television receiver, which includes a tuner 11, a video intermediate frequency amplification (hereinafter referred to as VIF circuit)/detection circuit 12, a mode switching circuit 13, and an analog-digital (A/D) circuit.
converter 14, digital signal processing circuit 15, digital-to-analog (D/A) converter 16, deflection circuit 1
7, a color cathode ray tube 18 and a video switching circuit 19. Reference numeral 20 denotes a text multiplex receiver having an adapter configuration, which includes a keyboard/text signal extraction circuit 21 and a text broadcast decoder section 22. The RGB signal (text multiplex signal) from the teletext decoder section 22 is input to one side of the video switching circuit 19, and the other input is the RGB signal output from the D/A converter 16.
Then, the composite video signal which is the output of the VIF/detection circuit 12 is supplied as one input to the mode switching circuit 13 and is also input to the character multiplex reception device 20. The character multiplex signal extracted from the signal is supplied to the decoder section 22, while the composite video signal is subjected to phase matching processing with the character multiplex signal in the circuit 21, and then sent to the mode switching circuit 13 via the delay device 23. is supplied as the other input. The delay device 23 has a delay time of 1H-5μsec≒60μsec, assuming that the processing time in the digital signal processing circuit 15 is 5μsec, so that the composite video signal is delayed by 60μsec before being transmitted to the digital signal processing circuit 15.
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In the above configuration, when superimposing a character multiplex signal on a normal video signal and displaying it, the mode switching circuit 13 is connected to the terminal b side, and the composite video signal is passed through the delay device 23 to the A/D converter. 14
At the same time, the character multiplex signal is supplied to the video switching circuit 19 via the decoder section 22.
The video switching circuit 19 inputs a control signal _Ys so that if there is a character multiplex signal, the character multiplex signal is supplied to the color cathode ray tube 18, and if there is no character multiplex signal, the output video signal of the D/A converter 16 is supplied. Therefore, switching control is performed. Here, the composite video signal including the synchronization signal is sent to the delay device 23.
The signal is delayed by 60μsec, and further delayed by 5μsec due to processing in the digital circuit, resulting in a delay of 1H for 1 horizontal period.Based on this delayed signal for 1 horizontal period, the deflection circuit 17 also performs horizontal and vertical deflection operations. Although there is a difference in the horizontal period, there is no difference between the synchronization signal and the character multiplex signal, and the character and graphic information from the character multiplex signal is projected at the correct position in the horizontal direction, causing problems such as the left end of the character and graphic information being missing. will disappear. Note that a shift of one horizontal period of the composite video signal does not pose any problem in terms of visual recognition.

Also, when displaying a text multiplex signal on the entire screen instead of a normal video signal, the synchronization signal is supplied with a delay of one horizontal period, as in the case of superimposition, so the text multiplex signal is The image is projected in the correct position in the horizontal direction.

FIG. 3 shows a specific example of the delay circuit 23. In the figure, 23a is an input low-pass filter (LPF);
23b is a 1HCCD delay line, 23C is an output low-pass filter, and 24 is an 11.7MHz clock generator. Here, input low pass filter 23
a is for limiting the frequency band of the input composite video signal, and an output low-pass filter 23
C serves to remove the clock frequency component contained in the output of the 1H delay line 23b, and at the same time removes the frequency component (aliasing distortion) caused by the interference of the high frequency component of the input composite video signal with the clock frequency. Further, by changing the clock frequency, it is possible to change the delay time, and this delay time may be set in accordance with the signal processing time of the digital circuit within the television receiver 10.

Figure 4 shows a digital television receiver 10.
2 shows the actual connection state of the text multiplex receiver 20, and normally a 21-pin female connector (not shown) is installed in both of the above. Therefore, in this device, a cable 33 with male connectors 31 and 32 on both ends, and a cable 36 with a female connector 34 on one end and a male connector 35 on the other end are used to receive the television receiver 10 and the character multiplexing. The device 20 is connected to the female connector 34 at one end of the cable 36, and at this time, a housing is formed at the female connector 34 at one end of the cable 36, and a board (not shown) in which the delay device 23 is configured in the housing and the female connector are connected to each other. By installing 34 units, the intended purpose was achieved.
Television receiver 10, text multiplex receiver 20
No circuit changes are required.

Effects of the Invention As described above, according to the present invention, by applying a predetermined time delay to the composite video signal supplied from the text multiplex receiver to the digital television receiver, text and graphic information can be transmitted horizontally on the screen. The image can be projected in the correct direction. At this time,
Instead of adding a delay to the character multiplexed signal output in RGB format, the delay used is added to the composite video signal as described above by adding a delay time that is 1H minus the delay time required by the digital signal processing circuit. Only one device is required, which is advantageous in terms of cost. In addition, we are currently installing a delay device using the existing connector device used for the multiplex text receiving device with an adapter configuration, so there is no need to make any circuit changes in the television receiver or multiplex text receiving device. Because of this, connections with other devices can be streamlined.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional character multiplex reception device using an analog television receiver, FIG. 2 is a block diagram of a television signal processing device according to an embodiment of the present invention, and FIG. 3 is the same. FIG. 4 is a block diagram showing the configuration of a delay device used in the apparatus, and is a diagram for explaining the connection state of the delay device. 10...Digital television receiver, 1
2...VIF/detection circuit, 13...Mode switching circuit, 14...A/D converter, 15...Digital signal processing circuit, 16...D/A converter, 17...Deflection circuit, 20... Character multiplex reception device, 21...Keyboard/character signal extraction circuit, 22...Decoder section, 23...Delay device.

Claims (1)

[Claims] 1 A VIF/detection circuit that outputs a composite video signal,
A character multiplex receiver inputs the composite video signal, extracts the character multiplex signal inserted during the vertical retrace period, and outputs the composite video signal and RGB format character multiplex signal, and the output of the VIF/detection circuit described above. A mode switching circuit that selects and outputs either a certain composite video signal or a composite video signal from a text multiplex receiver, an A/D converter, and a D/A converter, and includes an A/D converter and a D/A converter. A digital signal processing circuit that digitally processes one of the composite video signals, and a video switching circuit that switches the output video signal of the D/A converter and the character multiplexed signal at high speed based on the Y _s signal and supplies it to the display unit. and 1 for the composite video signal output from the above text multiplex receiver.
A television signal processing device comprising: a delay device that provides a delay time obtained by subtracting a delay time generated in the digital signal processing circuit from a horizontal period and outputs the resulting signal to the mode switching circuit.