JPH021432B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an information display device that can be used when receiving a teletext signal and displaying information in the form of characters and graphics, and is suitable for display on many television receivers. The object of the present invention is to provide a signal that can be easily superimposed on a normal television image and then supplied.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to an embodiment in which the present invention is implemented in a teletext reception and display device.

FIG. 1 shows a schematic configuration of an apparatus according to an embodiment of the present invention. In the figure, 1 is a television receiver;
It has input terminals for displaying R, G, B signals, etc., and output terminals for video signals, synchronizing signals, etc., and these input/output terminals are assembled in the connector 2 shown in the figure. 3 is a teletext signal receiver, 4 is a connector that collects its output terminals, 5 is an encoder block, and 6 and 7 are connectors that collect the respective input terminals and output terminals. Numerals 8 and 9 are coupling cables having completely identical connectors 10, 11 and 12, 13 attached to both ends, respectively, and have no directionality.
Here, connectors 2 and 13, 4 and 10, 6 and 1
Combine 1, 7 and 12 respectively. In a conventional television receiver with a built-in teletext receiver, when receiving a teletext signal and displaying characters or graphics on the cathode ray tube of the television receiver, the R and G of the cathode ray tube are usually used. , B input signals such as letters and figures to the input electrodes to minimize the occurrence of cross color and dot interference.
In addition, vertical lines such as narrow characters can be displayed in vivid color, but when the teletext receiver 3 is taken out of the television receiver 1, it is possible to display it as shown in Fig. 1. A configuration is often used in which the two are connected using a cable with a connector. In that case, usually one cable 9 connects the connectors 2 and 4 so that colored characters and figures can be displayed in exactly the same way as when the teletext receiver 3 is built in.

However, in schools etc., teletext receivers 3
The screen of characters and figures received by the receiver 1
If you want to display images at the same time, even if you prepare a large number of receivers 1 that are the same as those in Figure 1, connectors 2 and 4
The levels of the R, G, and B signals transmitted between the
Another problem is that the cable cannot be made long.

Therefore, in the present invention, an encoder block 5 as shown in FIG. 1 is used to convert the display R and GB output signals from the teletext receiver 3 into an NTSC video signal or an RF signal modulated therewith. In this way, the cable can be stretched for a long time, and the screen with the same characters and figures can be viewed on many television receivers 1.

Next, the basic circuit configuration of the one shown in FIG. 1 is shown in FIG. Here, 14 is a video detection circuit of the television receiver 1, 15 is a processing circuit that processes the detection output to obtain R, G, and B color signal output for normal image projection, and 16 is the R, G, B output and R, for displaying characters and graphics from the teletext receiver 3.
17 is an output amplifier circuit, 18 is a color cathode ray tube, 19 is a synchronous deflection circuit, and 20 is for outputting a video signal VI in which teletext signals are multiplexed. It is a buffer amplifier. The contents of the teletext receiver include a slicing circuit 21 that slices the video signal input VI from the buffer amplifier 20 of the television receiver 1 and reproduces it into a binary signal; Clock regeneration circuit 22 that regenerates the sampling clock, framing code (FC) in the character signal
A circuit 23 for detecting a signal, a main memory 24 for storing extracted received character signals for a screen, and this main memory 2
a write control circuit 25 that controls writing to the main memory 24; a read control circuit 2 that controls reading from the main memory 24;
6, an output buffer amplifier 27, a program selection circuit 27', etc., which have the same functions as already known teletext receivers. By connecting the connectors 2, 4, 6, and 7 with cables 8 and 9, it can be operated as a conventionally known teletext receiver. Furthermore, as shown in FIG.
Convert to NTSO standard signal using Sy
It consists of an NTSO encoder 28 and an RF converter 29 that converts the converted output into an RF signal of an arbitrary channel. The NTSC encoder 28 can be created by slightly modifying the encoder circuit for color cameras. 30 and 31 are output connectors, respectively.
Note that the color burst Bu is obtained from the teletext receiver 3. It is preferable to use an existing unit as the RF converter 29. Power is supplied from the television receiver 1 or teletext receiver 3. Further, although the power supply line is not shown in FIG. 2, it is branched and supplied to the NTSC encoder 28 and the RF converter 29 in the same way as the signal.

With this configuration, the television receiver 1 and the teletext receiver 3 are combined and operated as a normal teletext receiver, while the cathode ray tube 18
You can display the same screen as the characters and figures displayed on the screen.
Standard format video signal such as NTSC format or RF
Signals can be extracted independently. Therefore, the signal converted to this standard method is output to the output connectors 30, 3.
1 to a general color television receiver or a television equipped with a video signal input terminal, it is possible to display an image of almost the same quality as the character and graphic image displayed on the cathode ray tube 18.

Now, in the above explanation, the output of the encoder block 5 is only a character or graphic signal, but there is information that is better displayed by superimposing or mixing with a normal television screen. Therefore, the present invention aims to provide a device that can output such information signals by superimposing them on a normal video image signal.

First, a simple circuit that makes characters and figures appear white when both signals are superimposed will be described with reference to FIG. 32 is an OR gate that forms the logical sum of the R, G, and B outputs from the teletext receiver 3. The output becomes a luminance signal of characters and figures. On the other hand, 33 is a buffer amplifier for the video signal VI from the television receiver 1, and the DC level and amplitude of its output are determined by resistors 34 and 35 to appropriate levels in consideration of the output level of the OR gate 32. and,
Mixing occurs via diode 36 of OR gate 32. Therefore, only when the output of the OR gate 32 is at a high level, the diode 36 becomes conductive and the luminance signal of characters and figures is superimposed on the video signal output, forming an image signal in which white characters are superimposed on the TV screen, which is then sent to the buffer amplifier. It is output from 37. This video signal
Since VI is the output of the buffer amplifier 20 of the television receiver 1, ie, the output of the video detection circuit 14, as shown in FIG. 2, the color burst is an NTSC video signal containing a synchronization signal together with the television image signal.

On the other hand, 38 is a switching gate pulse generation circuit, which generates burst flags and horizontal pulses from a composite synchronization signal of the 3-bit switching signal output from the teletext receiver 3 and the output from the synchronization deflection circuit 19 in the television receiver 1. Includes circuits that form HD, vertical pulse VD, vertical blanking pulse, etc.
The signal is supplied to the NTSC encoder 28. The output signal φ ₁ is a gate pulse that makes the analog gate switch 39C conductive and outputs the output signal of the NTSC concoder 28 when outputting a signal that displays only character and graphic signals, and the output φ ₂ is a television image signal. Analog switch 3 to display only
This is a gate pulse that makes 9B conductive and outputs the output signal of the buffer amplifier 33, and the output φ ₃ is
This is a gate pulse that makes the analog switch 39A conductive and outputs the output signal of the buffer amplifier 37 when outputting a signal that superimposes characters and figures in white on the television screen. These output gate pulses φ ₁ , φ ₂ , φ ₃ are switched by a control signal in the teletext signal received by the teletext receiver 3 and by operation of a selection switch. The output signal of the analog gate 39 is amplified by a buffer amplifier 40 and output. It is to be noted that, in correspondence with the polarity of the output signal of the buffer amplifier 33, the polarity of the diode 36 is reversed and the gate 32 is changed to a NOR gate.

Next, details of an embodiment of the present invention for superimposing colored characters and figures on a television screen will be explained with reference to FIG. FIG. 4 shows details of the encoder block 5 in FIG. 2, which is a partial modification of the configuration in FIG.
45 is added. The phase of the color subcarrier output from the color subcarrier reproducing circuit 41 is determined by the input video signal.
It is completely synchronized with that of the VI, and is strictly adjusted so that the phase of the color burst output from the NTSC encoder 28 is the same as the phase of the color burst output from the buffer amplifier 33 to ensure stable operation. . Further, the output of the OR gate 32 is added to the pulse width expansion circuit 42 to delay only the trailing edge of the signal by about half a bit of the character or figure signal, and the delay circuits 43 to 45 are used to input the character or figure signal. The pulse width expansion circuit 42 generates gate pulses that are wider by 1/4 bit before and after the character or figure signal, and then the switching gate pulse generation circuit 38 supply to Then, using the outputs of the delay circuits 42 to 45, the output of the color subcarrier regeneration circuit 41, and the synchronization signal,
An NTSC encoder 28 forms an NTSC standard video signal.

On the other hand, the switching gate pulse generation circuit 38 generates switching gate pulses φ ₄ and ₄ as follows. That is, when the output signal for displaying only the television reception screen is the output of the analog gate 39, the gate pulse ₄ is set to a high level, _φ4 is set to a low level, the analog switch 39A is made conductive, and the output of the buffer amplifier 33 is turned on. The signal is directly transmitted to the buffer amplifier 40 and output. Conversely, when you want to use the output signal for displaying only characters or figures as the output of the analog gate 39, the gate pulse _φ4 is set to high level and ₄ is set to low level, the analog switch 39B is made conductive, and the output of the NTSC encoder 28 is turned on. The signal is directly transmitted to the buffer amplifier 40 and output.

When a mixture of colored characters and figures is displayed on the television screen, the outputs φ ₄ and ₄ of the switching gate pulse generation circuit 38 are as follows. That is,
Considering the 1-bit width of a character or figure, when a video signal as shown in _FIG . ) bit width, while gate pulse _φ4 is C
The analog switch 39B is made conductive with a width of (1+1/2) bits as shown in FIG. NTSC encoder 28
As for the output, when the signal for displaying characters and figures is mixed with the television image, the color signal for display is supplied from the teletext receiver 3 so that the area where there are no characters or figures becomes black level. As shown in FIG. 5C, the background area other than the characters and figures to be displayed is at a black level. Now, in Figure 5C, C ₁ is yellow, and the color signal C ₂
If it is a red signal, the output of the analog gate 39 will be as shown in Figure 5D, and 1 bit of yellow and red will be inserted into the TV image, and 1 bit will be inserted before and after the red signal. The black level is /4 bit wide, and text and graphics appear clear and clear without being affected by the content of the TV image. That is, the gate pulse φ ₄ of the output of the switching gate pulse generation circuit 38,
_φ4 becomes a gate pulse that is slightly wider than the width of the characters or figures only when displaying a mixture of the TV image and the signal for displaying characters or figures, blocking the TV image and allowing the signal for displaying the letters or figures to pass. Controls analog gate 39.

As described above, it is possible to form an NTSC standard video signal that can display colored characters and figures superimposed on a television image.

As described in detail above, according to the present invention, a color signal for displaying characters and figures obtained from a display color signal supplying means such as a single teletext receiver is used to convert a standard video signal to a video signal of a standard format. By supplying the signals in a superimposed manner, it is possible to obtain a useful device that can simultaneously supply signals for displaying characters and figures to the display means of many television receivers and display them in an easy-to-understand manner along with television images. It is possible.

[Brief explanation of drawings]

FIG. 1 is a perspective view of an information display device according to an embodiment of the present invention, FIG. 2 is a block diagram of an information display device provided to explain an example of the present invention, and FIG. 3 is a diagram illustrating an example of the present invention. FIG. 4 is a circuit diagram of an information display device provided for explanation, a circuit diagram of a main part of an embodiment of the present invention, and FIG. 5 is a waveform diagram of each part of FIG. 4. 1... Television receiver, 3... Teletext receiver, 5... Encoder block, 2, 4, 6,
7, 10, 11, 12, 13... Connector, 8,
9...Cable, 28...NTSC encoder, 2
9...RF converter, 30, 31... Output connector, 32...OR gate, 39... Analog gate.

Claims (1)

[Scope of Claims] 1. A teletext receiver that outputs an information display color signal for displaying text and graphic information in color on a display device, and a teletext receiver that encodes the information display color signal and converts it into NTSC.
an encoder block provided between the teletext receiver and the television receiver, the encoder block being provided between the teletext receiver and the television receiver; A video signal and a synchronization signal in which the teletext signal is multiplexed are extracted from the teletext receiver and supplied to the teletext receiver via the encoder block, and the teletext receiver outputs the information display color signal and control signal. a gate signal for switching between a television program signal and an information display color signal in the encoder block based on the information display color signal and the control signal; A teletext signal is superimposed on a television program signal by blanking the signal with a width wider than the information display color signal and inserting the information display color signal therein.
An information display device characterized by forming an NTSC video signal and supplying it to a plurality of television receivers.