JPH01117584A - Teletext receiver - Google Patents

Abstract

PURPOSE:To easily confirm the broadcast state of a teletext by using a control circuit, a channel selection circuit, an extraction circuit and a memory and displaying a message representing the absence of the teletext for a prescribed time by superimposition when the teletext is not broadcast. CONSTITUTION:In giving the request of the teletext by an operation section 13, a control circuit 11 reads a Fleming code and SIIN data in a character data during the same horizontal scanning period recorded in a memory 10A to check whether or not the code is a normal code and when both the codes are correct, the selected program is retrieved to continue the reception of the teletext. When no signal exists for nearly 20sec, the channel is switched to other channel to identify the code similarly and it is repeated till the channel is circulated. When the channel of the teletext exists during that time, it is recorded in the memory 12 and the result is displayed by superimposition after the circulation of the channel. Thus, at which channel the teletext is sent is discriminated.

Description

[Detailed Description of the Invention] Industrial Field of Application The present invention relates to a teletext receiving device that displays a superimposed message after a certain period of time if a teletext broadcast is not sent when a teletext broadcast is requested. It is.

2. Description of the Related Art In recent years, along with the practical use of code-based teletext broadcasting, teletext receivers with built-in sets have also been commercialized, and operability has become important.

Conventionally, when teletext is selected on a channel where teletext is not being transmitted, the following two methods have been mainly used.

The first method is to erase the text screen without requiring manual input from the keys, and the second method is to display the message on the entire text screen. Furthermore, the configurations on these leadwares are almost the same, and are realized only by changing the microcomputer program.

Problems to be Solved by the Invention However, in the first method described above, when reception is not possible for a short period of time due to disturbance or the like, key reception is canceled and the display is turned off, giving the impression that there is a malfunction. Also, if you display the message using the second method above, you will know that the teletext is not being sent, but if you request it just before the teletext starts and are waiting for the teletext to be sent, the fd , waiting in superimposition gives a better impression. Also, when teletext is not being transmitted, it would be more convenient to display the channel on which it is being transmitted.

In view of the above problems, the present invention is capable of displaying a superimposed message indicating that teletext is not being sent after a certain period of time when a request for teletext is made on a channel where teletext is not being sent. The present invention provides a teletext receiving device.

Means for Solving the Problems In order to achieve this object, the teletext receiving apparatus of the present invention includes a sampling circuit that extracts a character signal from a television video signal, and a circuit that extracts a character signal from a TV video signal, and a frame code and SIIN of the extracted character signal. a control circuit that checks whether the received channel is correct, performs a teletext reception operation if it is correct, and switches the reception channel if it is incorrect for the period of n fields; a memory that records the reception channel data; It consists of a circuit, a switching circuit, etc., which displays a superimposed display indicating that teletext is not being broadcast on the corresponding channel, and superimposing the channel on which teletext is being broadcast.

According to this configuration, the character signal reproduced by the sampling circuit is once recorded in the memory and then read out. If the Fleming code and SIIN in the same horizontal scanning period are correct, teletext reception operation is performed, and the Fleming code and SIIN are read out. If it is irregular, signals from other multiplexed periods are read out and checked in the same manner as described above, and if no teletext is sent after n fields, a superimposed display indicating that no teletext is being sent is displayed. It is something.

EXAMPLE An example of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a teletext receiver according to an embodiment of the present invention. In FIG. 1, 1 is an antenna, 2 is a tuner, 3 is an intermediate frequency amplification circuit, 4 is a video detection circuit, 6 is a channel selection circuit, 6 is a non-volatile memory, 7 is a sampling circuit, 8 is a synchronization separation circuit, 9 is an RGB conversion circuit.

1o is a memory ram, and RAM (random access memory) is usually used. Reference numeral 11 denotes a control circuit, which uses a CPU. Reference numeral 12 denotes memory B, which uses RAM. 13 is an operation unit, 14 is a timer, and control circuit 1
1 tells the time.

Reference numeral 15 denotes a display control circuit, which controls the kanji ROM and display memory, which will be described later, and creates ROB signals and synchronization signals. 16 is a kanji ROM with alphanumeric characters.

Contains patterns such as kana and kanji. Reference numeral 17 denotes a display memory, which uses RAM. Reference numeral 18 denotes a superimpose circuit that mixes the RGB signals of the text information and the RGB signals of the television video signal to create a superimpose signal. Reference numeral 19 denotes a switching circuit that switches between a superimpose signal and a signal for character information alone. Reference numeral 20 denotes a synchronization switching circuit that switches between a television video signal and a synchronization signal for text information. 21 is the RGB output terminal, 22
is a synchronous output terminal.

The operation of the teletext receiving apparatus configured as described above will be described below.

First, when you select a TV channel using the operation unit 13,
The RGB output terminal 21 has a TV video detection circuit 4, RGB
After passing through the conversion circuit 9 and the superimpose circuit 18, R, G, and B signals of the television video signal are output. Further, a synchronization signal of the television video signal is outputted to the synchronization output terminal 22 via the synchronization separation circuit 8 and the synchronization switching circuit 2o.

Now, when you request a teletext broadcast using the operation unit 13, text information is displayed on the entire TV screen as shown in Figure 2, and the message shown in Figure 2 is displayed in the header section at the top of the screen. Is displayed. At this time, the ReB output passes through the display control circuit 16 and the switching circuit 19, and only character information is output. The output of the display control circuit 15 is applied to the switching circuit 2o, and the synchronization signal is output as a synchronization output. The control circuit 11 also sets the timer 14 to 20 seconds. In this state, the video output of the video detection circuit 4 is transmitted to the synchronous separation circuit 8.
In addition to this, a horizontal synchronization signal and a vertical synchronization signal are created, and the sampling circuit 7 is also used. If a character multiplex signal as shown in Fig. 4 exists in this video signal,
In synchronization with the clock run-in in FIG. 4(A), the sampling circuit 7 creates a sampling clock and performs analog-to-digital conversion of the character multiplexed signal, and then serially converts the signal digitized by the sampling clock. Convert to parallel. This signal is subjected to byte processing using the Fleming code shown in FIG. 4(b).

Thereafter, error correction processing is performed and the SIIN shown in (c) is reproduced. The preceding error correction process is a correction method using a difference set cyclic code correction method, which can perform 8-bit error correction by adding 82 correction bits out of 192 bits, and is a well-known method. .

The character data from the 10th horizontal scanning period to the 21st horizontal scanning period after the error correction is recorded for one field in the memory 10m. The control circuit 11 uses the framing code and SII of the character data recorded in the memory 10m during the same horizontal scanning period.
N data is read out and checked to see if it is a regular code, and if both are correct, the program that has been selected is searched for and the teletext reception operation is continued.

If either code is different in the character code check, the control circuit 11 performs another horizontal scanning period to check the Fleming code and SIIN island in the same manner as described above. This check starts from the 10th horizontal scanning period of the vertical retrace period.
When the process is carried out up to the second horizontal scanning period and there is no regular Fleming code and SIIN between 1200 fields,
Alternatively, even when the value of the timer 14 is decremented to 0, the control circuit 11 gives an instruction to the channel selection circuit 5 to increase the channel position when a regular framing code and SIIN are not present. The tuning circuit 6 uses a 4-bit microcomputer, and the non-volatile memory 6 contains tuning data according to the channel position, so it is converted from digital to analog to the tuner 2 and sent to the tuner. When the synchronization is achieved, the signal power of the corresponding position is outputted, and a video signal is outputted via the intermediate frequency amplification circuit 3 and the video detection circuit 4. This video signal is processed using the regular Fleming code and SI from the 10th horizontal scanning period to the 21st horizontal scanning period of the vertical blanking period in the same way as above.
If there is no teletext signal for 600 fields or 10 seconds after identifying the presence or absence of the channel N, the control circuit 11 issues an instruction to raise the next channel position.

If a teletext signal is present, the control circuit 11 requests the channel selection circuit 5 for a channel number.

Since the tuning circuit 5 knows how many channels are selected from the data set in the tuner 2, the control circuit 1
The channel number data is sent to 1. Control circuit 1
1 records the data of the channel in which the teletext signal was present in the memo IJ-12B, and then outputs a channel up instruction to the channel selection circuit 6. The number of channel positions of the operation unit 13 is normally 12, and after repeating the above operation 12 times.

Returning to the originally selected position, as shown in FIG. 3, the message that the corresponding channel is not transmitting a text multiplex signal and the channel that is transmitting the text multiplex signal are displayed in superimposition. As a superimpose display method, a horizontal synchronization signal and a vertical synchronization signal from the synchronization separation circuit 8 are added to the display control circuit 16, and an RGB signal synchronized with this synchronization signal is added to the superimpose circuit 18.
RGB and key IX of TV video signal. Further, if the synchronization signal from the synchronization separation circuit 8 is switched and outputted by the synchronization switching circuit 20, the synchronization signal is displayed as a superimposition as shown in FIG. 3.

As described above, according to this embodiment, the Fleming code and SI engineering code in the teletext multiplex signal are read from the 10th horizontal scanning period to the 21st horizontal scanning period while watching the teletext screen for a while on the full-screen teletext screen when teletext broadcasting is selected. After identification, if there is no borrowed code for about 20 seconds, the system switches to another channel and performs the same identification as described above, and repeats this until the channel has completed one cycle. During this time, if a teletext transmission channel exists, it is recorded in the memory 12 and displayed in superimposition after the channel cycle, so that it is possible to know on which channel the teletext transmission is being transmitted and to start the teletext broadcast. You can watch the TV screen while waiting.

Effects of the Invention As described above, according to the present invention, by using the control circuit 0 channel selection circuit, the sampling circuit, and the memory, when the teletext is not being transmitted, the teletext can be transmitted continuously for a certain period of time in a superimposed manner. Because a message is displayed saying that there is no
The broadcast status of teletext can be easily checked, and its practical effects are significant.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a teletext receiver according to an embodiment of the present invention, FIG. 2 is a front view of the display screen of the present invention when a teletext is requested, and FIG. FIG. 4 is a front view of the display screen of the present invention when the display screen is opened, and is a diagram showing the signal format of the character signal of the portion related to the present invention. 5...Tuning selection circuit, 7...Sampling circuit,
11...control circuit, 12...memory,
16...Display control circuit, 18...Superimpose circuit, 19...Switching circuit. Name of agent: Patent attorney Toshio Nakao and one other person!
E2ri! J Figure 3 Figure 4

Claims (2)

[Claims] (1) After extracting the character multiplex signal multiplexed during the vertical retrace period of the television video signal and recording it in the memory, the character multiplex signal is read out by the control circuit, and if both the framing code and SIIN during the same horizontal scanning period are correct. If the teletext reception and display operation continues, and the regular signals of the Fleming code and SIIN do not exist for n fields in any horizontal scanning period of the teletext multiplex period, teletext is not being superimposed. A teletext receiving device characterized by displaying a message to the effect. (2) Fleming code and SIIH regular code are n
When there is no field, the control circuit gives a channel change instruction to the channel selection circuit and the fleming code and SI are sent.
The presence or absence of IN is detected, and if the regular fleming code and SIIH do not exist within the teletext multiplexing period in the m field, a channel change instruction is given, and if the above regular signal exists on the changed channel, the channel number is given. is stored in the memory, a channel change instruction is given, and the detection operation is performed until the channels previously stored in the memory are completed, and after the detection is completed, the channel on which teletext is being broadcast is displayed on the screen. A teletext receiving device according to claim 1.