JPS5974788A - Processing system of signal for multiplex character broadcast - Google Patents

Abstract

PURPOSE:To attain automatic reproduction of a sound signal or a character pattern code signal, by detecting both character pattern code start and end signals which are contained in a sound carrier wave. CONSTITUTION:A sound signal carrier wave VW sent from the transmission side contains a character pattern code signal 2 in a gap between a normal sound signal 1 and a sound sinal obtained when a no signal is available or when a short- time interruption is allowed for sounds. Then character pattern code start and end signals 3 and 4 with which both start and end are recognized by a reproducer are distributed before and after the signal 2. Then the signal 3 is detected by a comparator 14, and the reproduction mode of the sound signal is switched automatically to the reproduction mode of the character pattern code signal through a switch circuit 16. Thus the character information is reproduced independently of the picture signal. In addition, the signal 4 is detected by a comparator 15 and then reset to the reproduction mode of the sound signal by the circuit 16.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical field of broadcasting] This invention relates to multiplex text broadcasting (ETEXT) in a television system.

[Technical background of the invention and its problems]

Multiplex teletext (ETEXT) has already been put into practical use and is widespread in Europe, and in recent years there has been a movement towards its practical use in Japan as well. The multiplex teletext system that has been proposed to date uses signals corresponding to two scanning lines controlled by image signals: a scanning line near the top that is not visible on the cathode ray tube, and a scanning line near the bottom. This system receives character pixel signals, stores them sequentially in a buffer memory, and displays them on a cathode ray tube when the signals equivalent to 525 scanning lines required for one screen have been collected.

In this case, if there are more than 200 teletext broadcasts, it takes several seconds to display the screen after selecting a channel, since one frame of field 4 images is formed in 38 seconds in the television system. Furthermore, a considerable amount of time must be spent to obtain various types of information, which is inconvenient, and furthermore, a buffer memory with a large capacity is required to store each pixel data, resulting in high costs.

[Purpose of the invention]

This invention was made in view of the above-mentioned circumstances, and its purpose is to reduce the waiting time from when a desired teletext broadcast is tuned until the character screen appears on the CRT, and the waiting time until the next character screen appears. The purpose of the present invention is to provide a teletext data processing method that can be shortened.

[Summary of the invention]

In order to achieve the above object, the present invention sequentially installs a character pattern code start signal, a character pattern code signal, and a character pattern code end signal in a section of an audio signal carrier wave where no audio signal exists, and a character pattern code start signal. Upon detection, a switching circuit automatically switches from an audio signal reproduction mode to a character pattern code signal reproduction mode to enable reproduction of characters separately from an image signal, and further detects a character pattern code end signal. This is a signal processing system for multiplex teletext broadcasting in which the switching circuit returns to the audio signal reproduction mode.

[Embodiments of the invention]

The present invention will be explained in detail below based on embodiments of the drawings.

FIG. 1 schematically shows the contents of a signal in an audio signal carrier wave, and FIG. 2 is a block diagram of a reproduction device.

In Figure 1, there is a normal audio signal 1 in the audio signal carrier wave VW sent from the transmitting side (broadcasting station), and there are times when there is no audio signal 1 or when it is okay for the audio to be interrupted for a short time. A character turn code signal 2 is provided in the gap between the audio signals, and a character pattern code start signal 6 and a character pattern code end signal are provided before and after the character pattern code signal 20 to make the playback device recognize the start and end of the character pattern code signal. 4 is placed.

The character pattern code signal 2 has various character patterns digitally encoded in advance in a certain system, and is obtained by analog conversion of the code corresponding to the character pattern to be sent. Furthermore, the 1-character pattern code start signal 3 is a special code that indicates that the character pattern code signal starts from that point, and the 1-character pattern code end signal 4 is a special code that indicates that the character pattern code signal has ended at that point. It is made up of code.

Next, the reproducing apparatus will be explained based on FIG.

The audio signal carrier wave VW as shown in FIG. 1 is received by the audio signal input device 11, sequentially subjected to detection, amplification, etc., and output. Immediately after this, this output signal is branched, one being input to the A/D converter 1 and the other being input to the gate circuit 18. The A/D converter 13 converts this signal into a digital signal, and the digitally converted signal is further branched into six parts, one of which is a first comparison circuit that detects a character pattern code start signal. 14, the other one goes into the second comparison circuit 15 which detects the character pattern code end signal, and the other one goes into the gate circuit 17. The output signal of the first comparison circuit 14 is normally in the "0" state.

"1" is output only when the start signal is detected, and is connected to the set input terminal S of the switching circuit 16 composed of a flip-flop, and the second comparison circuit 1
The output signal of No. 5 is also normally in the '0' state.

1" is output only when the end signal is detected, and is connected to the reset input terminal H of the switching circuit 16. The output signal from the positive output terminal Q of the switching circuit 16 is the gate circuit 170 input signal. Therefore, the output signal from the auxiliary output terminal becomes the input signal of the gate circuit 18.The positive output terminal -
The output of the child Q is normally “0”, and the set input terminal is “1”.
When is input, the output signal changes to "1", and the outputs of the auxiliary output terminals change from "1" to "0", and that state is maintained.Furthermore, "1" is input to the reset input terminal 11.
When is input, the output of positive output terminal Q changes from “1” to “O”
Then, the output of the interpolation tip changes from "0" to "1" and this state is maintained.

The gate circuits 17 and 18 are AND gates, in which the signal from the switching circuit 16 is "1", and the other input signals are passed through. The gate circuit 17 is connected to a character pattern code buffer 19 and further connected to a character generator 20. The character generator 20 outputs a character pattern signal corresponding to a code, and can output a character pattern onto the cathode ray tube 26 by connecting it to the cathode ray tube 26 via a gate circuit 21.

On the other hand, the image signal to be transmitted is received by an image signal input device 12, and the signal from this input device 12 is inputted to a cathode ray tube 26 via a gate circuit 23, so that one normal TV image is displayed on the cathode ray tube 26. It turns out.

The gate circuits 21 and 23 are for switching the output signal between a high level state and a high impedance state, thereby switching between displaying a character pattern on the cathode ray tube 26 or a normal TV image. , the switch 2 is connected to the gate circuit 23 via the inverter 24.
2, and the above switching can be performed by turning ON and OI;'F of this switch 22.

Next, the reproduction of turn code words included in the audio signal carrier wave VW by the reproduction apparatus having such a configuration will be described.

The signal received by the audio signal input device 11 is subjected to detection, amplification, etc., and then branched. One is directly input to the gate circuit 18, and the other is converted from an analog signal by an Al1) converter. converted into a digital signal.

The first comparison circuit 14 stores the same code turn as the code pattern of the character pattern code start signal, and performs pattern matching on this code pattern and the signal from the A/]) converter 13 to find the same code pattern. When the code pattern of is detected, the character pattern code starts, and the output signal from the output terminal changes from the state of 0" to "1", and the set input terminal of the switching circuit 16 consisting of a flip-flop. This causes the output from the positive output terminal Q to change from °0" to 1"9.
While the state of "1" is held, the output signal from the auxiliary output terminal Q changes from the state of "1" to the state of "0" and is held.

Therefore, in the gate circuit 17, the character pattern code signal 2 following the character turn code start signal 6 digitally converted by the A/1] converter 16 can be output, and on the other hand, in the gate circuit 18, the character pattern code signal 2 following the character turn code start signal 6 can be output. The signal is “
0'', signals that do not pass through the A/D converter 16 are blocked, making it impossible to reproduce audio.

Further, when the reproduction of the character pattern code signal 2 is finished and the character pattern code end signal 6 is received, the second comparison circuit 15 converts the code pattern of the end signal in the same manner as the first comparison circuit 14. Detected by matching and outputs "1".

In the switching circuit 16 which receives this signal at the reset input terminal R, the output signal from the positive output terminal Q changes from "1" to "0", and the output signal from the auxiliary output terminal changes from "0" to "1". As a result, the gate circuit 17 is closed and the other gate circuits 18 are opened, so that the signal following the turn code end signal, that is, the audio signal 1 can be reproduced.

In this way, the character Bakun code start signal 6 and the character pattern code end signal 4 included in the voice signal carrier wave VW are detected, and when there is a voice signal, it is possible to automatically reproduce the voice signal, and the single character pattern code signal is reproduced. In this case, the character pattern code signal can be switched to enable reproduction of the character pattern code signal.

The digital character pattern code signal from the gate circuit 17 is temporarily stored in the character pattern code buffer 19.
When a predetermined number of characters is reached, the code is sent to the character generator 20, where it is converted into character pattern information corresponding to the code.

On the other hand, since a normal TV image signal is sent from the image signal input device 12 to the cathode ray tube 26, it is necessary to switch between text information from the audio signal and normal TV image information. This is done using switch 22. That is, switch 2
2 is in the OFF state, a high level potential is applied to the gate circuit 21, which closes the gate, and since the gate circuit 26 is connected via the inverter 24, a low level potential is applied to the gate circuit 26, which closes the gate. opens and a normal TV image can be displayed on the cathode ray tube 26. On the other hand, switch 2
21i! ::When it is closed, it is grounded, which is the opposite of the above case, and the inside of the gate circuit is opened, and the gate circuit 23 is closed, making it possible to read the text information.

〔Effect of the invention〕

As described above, according to the present invention, compared to conventional teletext broadcasting, the requested teletext can be displayed on the screen more quickly because the signal is encoded and sent using an audio signal carrier wave. In addition, if you have a gearactor generator for Japanese letters, Roman letters, and numbers, you can reduce the buffer, and the broadcasting station can also open special subtitles in regular broadcasting. Videos have revolutionary effects, such as being able to be viewed with special news text removed.

Furthermore, in Japan, audio multiplex broadcasting has been put into practical use and is widespread, so it would be more advantageous to implement the invention if sub-audio etc. were used.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is an explanatory diagram schematically showing the contents of a signal in an audio signal carrier wave, and FIG. 2 is an explanatory diagram of a reproducing apparatus. 1...Audio signal 2...Character pattern code signal 6
... Character pattern code start signal 4 ... Character pattern code end signal 14 ... First comparison circuit 15 ... Second comparison circuit 16 ... Switching circuit patent applicant Toppan Printing Co., Ltd.

Claims (1)

[Claims] A character pattern code start signal, a character pattern code signal, and a character pattern code end signal are sequentially provided in the section of the audio signal carrier wave where no audio signal exists, and by detecting a single character pattern code start signal, the switching circuit changes the audio signal playback mode. to automatically switch to a character pattern code signal reproduction mode to enable reproduction of character information separately from the image signal, and furthermore, by detecting a character pattern code end signal, the switching circuit switches to an audio signal reproduction mode. Signal processing method for multiplex teletext to be restored.