JPS645512B2 - - Google Patents

Description

[Detailed description of the invention] Industrial application field
The present invention relates to a color television receiver capable of recording signals for displaying graphics in color on a magnetic recording/reproducing device (hereinafter referred to as a VTR).

Conventional Structures and Their Problems So-called teletext broadcasting has been proposed as a means of multiplexing and transmitting separate new image information using television broadcast signals. As shown in Figure 1A, this uses the vertical blanking period of a normal television broadcast signal.
During an arbitrary horizontal scanning period (for example, the 20th H), a character multiplex signal in which additional information such as characters or figures is separated and transmitted is superimposed with a binary digital signal and transmitted. This character multiplex signal has a fixed number of bits (for example,
It consists of a group of digital signals (called data packets) of 296 bits, and its contents consist of a header part and an information data part. Then, depending on the information contained in the data part, the page control packet PCP, color code packet
There are different types of packets, such as CCP and pattern data packet PDP.

The page control packet PCP is transmitted prior to transmitting one screen of characters and graphics, and its data portion includes page control code signals such as program number PR, page number PA, and code ED indicating screen deletion or screen update. It is. color code packet
The CCP is transmitted following the page control packet PCP, and includes a color code CC indicating the color in which each character or unit division of the additional image information should be displayed. Furthermore, the pattern data packet
PDP is then transmitted one screen at a time (other packets may be inserted in the middle).
The data portion transmits pattern data for each line when characters and figures to be displayed are scanned in the horizontal direction. Note that there are several other types of data packets, but their explanation will be omitted here.

Also, in the header part of all data packets,
A clock line signal CR for synchronizing the data sampling clock on the receiving side, a framing code signal FC for frame synchronization, a service identification/interrupt control signal SI/IN, and the type of data packet the data packet is. Data identification signals DI ₁ and DI ₂ are transmitted. Here, the FC signal is a signal capable of 1-bit error correction, and SI/IN, DI ₁ ,
Each DI ₂ signal uses a Hamming code that can correct 1-bit error and remove 2-bit error.

Therefore, the receiving device receives the television signal transmitted with such a character multiplex signal superimposed on it, extracts the character multiplex signal, and
Select only the signal of the desired program to be received using the page control packet PCP, store the color code data CC in the color code packet CCP of that program and the pattern data in the pattern data packet PDP in memory for one screen, By reading out the signal in synchronization with the screen scanning of the cathode ray tube and converting it into an image signal for display, the characters and figures can be displayed on the screen. In general, a normal television receiver is also used to receive text and graphics, and a circuit for processing the text multiplexed signal is added, and when displaying the received characters and graphics, a cathode ray is used. Image information such as characters and figures is displayed on the tube screen by superimposing the received image (moving image) of a normal television broadcast program or by erasing the received image.

FIG. 2 shows a block diagram of the overall configuration of a general receiver for receiving such character multiplexed signals.

A television broadcast signal on which a text multiplex signal is superimposed is channel-selected by a tuner 1, VIF amplified by a VIF circuit 2, and then detected by a video detection circuit 3 to obtain a composite video signal as shown in Figure 1A. It will be done. The character multiplexed signal portion is corrected for waveform distortion during transmission by a waveform equalization circuit using a transversal filter or the like by a waveform shaping circuit 8, and is sliced at a predetermined level by a slicing circuit into a predetermined binary signal waveform. A molded R/W control circuit 10 composed of a microprocessor and buffer memory.
The main memory 12 is a pattern memory and a color code memory.

On the other hand, in synchronization with the color burst signal in the composite video signal, the color subcarrier f _SC is regenerated by the f _SC reproducing circuit 7, and a write clock is generated so that it is in phase synchronization with the CR signal and FC signal in the character multiplex signal. circuit 9
The write clock is created by multiplying the clock by 8/5.
With this write clock, the pattern data signal PD in the received character multiplex signal is stored in the main memory 12.
and color code data CC are written and stored in a predetermined order. Further, a synchronization signal is extracted from the composite video signal by a synchronization separation circuit 5, a horizontal pulse synchronized with the horizontal synchronization signal is generated by a horizontal oscillation circuit 6, and in synchronization with this, a readout clock generation circuit 11 synchronizes with the television signal. A read clock is created. Therefore, the pattern data PD and color code data CC are read out from the main memory 12 using this readout clock, and the signal processing circuit 13 uses these pattern data PD and color code data CC to generate R, G, B.
Converts to a color signal in the base frequency band for displaying characters and figures. If the demodulated R, G, B signals of the normal television signal from the chroma video processing circuit 4 are superimposed or switched by the switching circuit 14 and supplied to the cathode ray tube 15, image information such as characters and figures is displayed on the screen. can be displayed.

On the other hand, receiving a character multiplex signal in this way,
In addition to processing and displaying characters and figures, there are cases where it is desired to save the displayed characters and figures by recording them on a VTR. In such a case, normally, as shown in Figure 2,
The character/figure display signals supplied to the CRT 15 are superimposed on the video detection output signal by the encoder 16 and encoded into a standard format television signal such as the NTSC format, and the television signal is directly transmitted.
The signal is recorded on the VTR by supplying the signal to the VTR, or by modulating the signal into a high-frequency signal of an arbitrary channel using the high-frequency modulation circuit 17 and then supplying the signal to the VTR.

Since a general VTR has an input terminal for a composite video signal, the output of the encoder 16 can be connected to the input terminal.

Here, a commonly considered encoding means is shown in FIG. 4M is R,
This is a demodulation circuit that demodulates color signals in the G and B base frequency bands. The amplitude ratio of the output R, G, and B color signals is not 1:1:1 because it is selected in consideration of the coloring ratio of the three colors of the CRT 15 and the sensitivity of the eye.

On the other hand, the output from the luminance Y memory and the read output from the color code C memory in the main memory 12 of the character multiplexed signal receiving section are converted into color signals in the R, G, and B base frequency bands by the signal processing circuit 12C. . If the outputs of the three primary colors are expressed as r, g, and b, the amplitude ratio of the r, g, and b color signals is 1:1:1. Further, for specific code data in the color code data, a _YM signal is formed by the signal processing circuit 12C and output. this
The _YM signal is a control signal for reducing the level of both or either of the brightness and contrast of the received image that is the background of characters and graphics when they are superimposed in high-level parts. Also,
The Y _S signal is a switching signal that becomes high level only in the display area of characters/figures, that is, becomes high level when any of the r, g, and b signals becomes high level. Switch the analog switch.

When displaying only characters and figures on CRT15
The Y _S signal is at a high level throughout one field period, and when the color signal for displaying characters and graphics is superimposed on the output signal of the demodulation circuit 4M to display the characters and graphics superimposed on the receiving screen. , the color signal output for characters/figures, that is, the output r of the signal processing circuit 12C,
In a portion where either the g or b signal is at a high level, the Y _S signal becomes at a high level. Note that r, g,
The amplitude ratio of the b signal is matched within the mixing switching circuit 14 to be the same as the R, G, B signals output from the demodulating circuit 4M.

The output of the mixing/switching circuit 14 may be encoded by the encoder 16, but since there is a phase difference between the input signal from the mixing/switching circuit and the detection output signal, that is, the output signal of the detection circuit 3, the synchronization signal If the output and color subcarrier output are used as they are for encoding, the video signal will be delayed by, for example, about 0.5 to 1.5 μsec with respect to the synchronization signal. Therefore, a PLL circuit of f _SC and 4f _SC is provided inside the encoder 16, and the synchronization board is reset with the output signal of the synchronization separation circuit 5, and a synchronization signal and f _SC are formed again.
You need to encode using this. Therefore, there is an inconvenience that a hue shift occurs depending on the accuracy of the PLL circuit. (The color of the original image is shifted)
Also, an LSI etc. that generates synchronization signals etc. from the 4f _SC is required, and the amplitude of the three primary color signals is 1:1:
Since it is not 1, there are drawbacks such as the fact that encoder ICs for television cameras cannot be used as is.

In this way, with conventional systems, when recording on a VTR, when encoding the signal for recording, the character/graphic display signal is superimposed with the normal television reception signal. However, there were disadvantages in that the colors of characters, figures, and the image receiving screen changed unnaturally, and the composition became complicated.

Purpose of the Invention The present invention is an apparatus which eliminates such conventional inconveniences and which does not cause color deterioration even when a character/figure display signal is encoded by being superimposed on a normal received signal and recorded on a VTR. The purpose is to provide the following.

Structure of the Invention In the present invention, characters and figures read from the main memory and obtained through signal processing are encoded with a color signal in the base frequency band for display to form a composite video signal in a standard format such as the NTSC format. At the same time, when displaying characters and graphics to be displayed superimposed on a normal television screen, only the parts of the encoded characters and graphics signal with a high luminance level are output as a video detection output signal. A switching circuit is installed to encode only the color signal in the base frequency band based on the data signal as it is when displayed without superimposing, and to encode the color signal in the base frequency band based on the data signal as it is. The present invention is characterized in that the switching circuit is switched and driven based on a control signal.

DESCRIPTION OF THE EMBODIMENTS The configuration of the main parts of a color television receiver according to an embodiment of the present invention will be described below with reference to FIG.

In this device, as shown in FIG. 4, the method of superimposing onto a video signal is switched depending on whether it is displayed on a CRT or when it is RF modulated. That is, reading from the main memory 12 is performed earlier than the time difference ΔT between the video detection output signal and the output signal of the demodulation circuit 4M. The delay circuit 12D delays the signal by ΔT. This results in
Characters and characters are transferred to CRT15 under the same conditions as in Figure 3.
A signal for graphic display is sent.

On the other hand, in this circuit, the encoder 16B may be a circuit for a camera, for example, which requires external synchronization, and the ratio of r, g, and b color signals is 1:1:
1 is fine. At this time, the inside of encoder 16B
Even if the accuracy of the PLL circuit between the 4f _SC and the input f _SC is poor, the hue will not be affected much, and if you want to display only characters and figures without superimposing them, you can simply RF modulate the output of the encoder 16B as is. good. Here, the delay in the encoder 16B is set to 0, but if it is assumed that there is a delay of Δt, the signal processing circuit 13
Then, it is necessary to output the signal earlier by Δt and to delay the signal further by Δt in the delay circuit 12D.

Also, whether or not to display the text/graphics screen superimposed on the received video is determined by the received text multiplex signal.
Determined by the detection output of the display control code DC of the pcp packet. In the case of superimposed display, the detection output becomes "0" in FIG. 4, for example, and the inverter 18
The output becomes "1" and the AND gate 19 becomes conductive. The output of encoder 16B is Y _S signal “1”
Only the part exists, and if this Y _S signal is "1", the output of the inverter 20 is "0", so
The AND gate 19 is cut off and the video signal output from the video detection circuit 3 is blocked. Therefore, only the output of the AND gate 22, that is, the character/figure display signal is transmitted to the OR gate 21. As a result, OR
The output of the gate 21 is in the form of a character/graphic display signal superimposed on a received image signal. On the other hand, 23
is an audio circuit, and the AND gate 24 is conductive only when the output of the inverter 18 is "1", that is, when superimposed display is performed. Therefore, in the case of superimposed display, an audio signal is also added to the output of the RF modulation circuit 17 and modulated. Therefore, when the output RF signal is received by a monitor TV, characters and graphics are displayed, and when superimposed display is performed, the sound of the main image is also output.

In addition, each gate 19, 20, 21,
24 is an analog gate.

Further, if the outputs of the OR gate 21 and the AND gate 23 are supplied to a monitor television (video input type), the same state as that of receiving the output of the RF modulation circuit 17 will be obtained.

Effects of the Invention As described above, according to the present invention, when recording on a VTR, it is possible to prevent color deterioration of the main image during superimposed display, and also as an encoder for standard formats such as the NTSC format. It is also possible to use one for television cameras, making it simple and inexpensive.

[Brief explanation of drawings]

Fig. 1 is a waveform diagram of a teletext signal, Fig. 2 is a block diagram of a conventional color television receiver, Fig. 3 is a block diagram of its main parts, and Fig. 4 is a diagram of an embodiment of the present invention. FIG. 2 is a block diagram of the main parts of a color television receiver. 3...Video detection circuit, 10...R/W processing circuit, 12...Main memory, 12D...Delay circuit, 1
3...Signal processing circuit, 14...Mixing switching circuit, 1
6B... Encoder, 17... RF modulation circuit, 1
8, 20... Inverter, 19, 22, 24...
AND gate, 21...OR gate.

Claims (1)

[Scope of Claims] 1. A multiplexed signal representing characters and figures transmitted superimposed on a television signal is received, and based on a control signal in the multiplexed signal, the control signal is removed. A data signal for representing characters and figures is stored in a digital memory, and the data signal is read out from this digital memory in synchronization with the vertical and horizontal synchronization of the television screen, and is converted into a color code signal indicating coloring information in this data signal. Therefore, a color signal in the base frequency band is formed to display color characters and figures on a color display device, and the color signal in the base frequency band is encoded to form a composite video signal in a standard system such as the NTSC system and output. In addition, when displaying characters and graphics to be displayed superimposed on a normal television screen, only the portions of the encoded characters and graphics signal with a high luminance level are included in the video detection signal. When displaying the composite video signal without superimposing it, a switching circuit is provided to switch so that only the base frequency band color signal based on the data signal is encoded as is, and the multiplexed signal representing characters/figures is A color television receiver characterized in that the switching circuit is switched and driven based on a control signal. 2. The color device according to claim 1, wherein the audio signal is outputted only when characters and figures are superimposed and displayed on a normal television screen, and is high-frequency modulated together with the composite video signal. television receiver.