JP2001505394A - Teletext - Google Patents

Abstract

(57) [Summary] In order to decode full-field teletext data using a conventional teletext decoder that only recognizes teletext data included in a line during a vertical blanking period, each of the full-field data is It is divided into a plurality of channels occupying only the number of lines in the vertical flyback period. Data from one of the selected channels is delayed before being provided to the decoder, as occurs in a subsequent vertical blanking interval.

Description

DETAILED DESCRIPTION OF THE INVENTION Teletext Technical field   The present invention relates to a method and a device for transmitting and / or decoding teletext signals. . Background art   Normal teletext signals are transmitted in the vertical blanking interval (VBI) and are typically Occupies up to 15 lines per field. However, given the video signal Channel is used only for transmitting teletext data without being , 625 lines of PAL television signal, about 300 lines per field Can be used. This is roughly two times the normal teletext transmission capacity. 0x to send more pages and / or access to each page Access time can be reduced. However, for television receivers Normally equipped teletext decoders provide full channel teletext data Can not accept. This is a normal teletext television receiver Expects and can only receive teletext data in VBI Because there is no. That is, if the television set is, for example, a full-field teletext, Access to this data when connected to the cable channel sending the Access can only be achieved by having a special teletext decoder. this is , Obviously inconvenient for the user, teletext over the full field Say that it significantly reduces the potential audience for the channel you send Seems to mean. In addition, files provided by other than cable television Field teletext information, for example, on a record carrier such as a videotape. The potential user base for recorded data will also be reduced. Would. Disclosure of the invention   It is an object of the present invention to provide a full-field teletext using a normal teletext decoder. The object of the present invention is to enable decryption of text transmission.   The present invention a) Teletext data is stored in at least a part of the field period outside the vertical blanking period.     Sending, b) the teletext data into m separate data streams, each occupying up to n lines. And m and n are integers, and n is a vertical flyback period. The method of transmitting teletext data, characterized in that the number of lines is not more than Provide the law.   This method has multiple channels where one of the channels can be dedicated to transmitting data It can be used inter alia in cable television systems. The above data is Formatted in standard teletext form, normal as well as vertical retrace May be transmitted during the effective image period. Each is less than or equal to the number of lines in the vertical flyback period Splitting teletext data into multiple distinct data streams occupying line numbers To allow a standard teletext decoder to receive the teletext data It can be used in various receivers. Obviously, each of the data streams exceeds n May contain a different number of lines, provided that no It may vary depending on the quality of the data to be generated.   The teletext data may be recorded on a record carrier. That is, a disk or It can be tape, accessed and read using a standard television receiver It is possible to provide a record carrier on which the obtained data is pre-recorded. VHS bidet To enable satisfactory playback of teletext data recorded on the tape The teletext data is lower than the standard teletext data rate. It may be recorded as a multilevel signal at a tare rate. Standard VHS video recorder Satisfactorily records standard teletext data due to limited bandwidth And it is well known that it cannot be regenerated. Telephone by VHS video recorder An arrangement to enable the recording and playback of text data is available from the applicant's co-pending UK Patent Application No. 9605614. No. 8 (PHB34056). In this co-pending application In some cases, teletext data is lower than the standard teletext data rate. A configuration in which a signal is recorded as a multilevel signal at a tare rate is disclosed. Record Da Also converts the input standard teletext data into multi-level codes, A circuit that converts this multilevel code back to the standard teletext data rate Contains. Conversion of standard teletext data to multi-level signals is, of course, Recorded teletext data is already recorded as a multi-level signal When playing a tape, a video recorder is not required. In this case, multiple levels Only a configuration that encodes the code into a standard teletext code is required.   Each of the data streams may occupy 15 lines, which is This is a number typically occupied by a text transmission. In this case, the number of data streams is 20 It is good. This will occupy a total of 300 lines per field.   The present invention further provides that the teletext data has fewer field periods outside the vertical retrace period. The teletext data each occupy up to n lines Divided into m separate data streams, where m and n are integers and n is the vertical retrace interval Carrying teletext data, characterized by being less than or equal to the number of lines in A record carrier is provided. The record carrier may be a VHS tape, Text data has a lower data rate than the standard teletext data rate May be stored as a multi-level signal.   Thus, say the television receiver includes a teletext decoder The main requirement is that standard teletext data in a normal television receiver be used. Data decodable by the coder may be provided on the record carrier. Especially in the UK Most television sets today are equipped with a teletext decoder Thus, data can be reproduced from the record carrier by the television set. Wax and more data than can be carried by the teletext service during the vertical retrace. Data can be obtained. Of course, teletext data occupies the whole field Teletext data outside of the vertical retrace interval or in all parts of the record carrier Is not essential. Teletext day as a percentage of the entire field It may be convenient to have videos with interspersed data. In the data stream All lines are used, or all data streams contain the same number of lines It is not mandatory.   The invention further provides: a) selecting one of the m data streams of the input teletext data     When, b) transmitting the teletext signal containing the selected data stream during a vertical blanking interval; Supplying to a text decoder. Transmitted by a method or reproduced from a record carrier according to the invention And a method for decoding the data. The decoding method according to the present invention provides a single data stream. Is selected and time-shifted so that the data stream occurs during the vertical retrace period. Data transmitted or reproduced from the record carrier for standard teletext deco Allows the user to decrypt. That is, the standard teletext decoder Recognize the text signal, decode the signal and display the appropriate on the display of the TV receiver. Can bring the display.   The invention further comprises means for selecting one of the teletext data streams for playback, Obtaining said selected teletext data stream at an output during a vertical retrace interval Means for reproducing teletext data recorded on a carrier A video playback device is provided.   That is, a playback device such as a video cassette recorder is used to record on a video tape. Means for encoding teletext data into a standard teletext form and the output Means are provided for delaying until the next vertical retrace period. Thus, the television receiver It is clear that the telecommunications equipment has multiple teletext data that occur outside the vertical retrace interval. Receiving a standard teletext signal selected from one of the streams during the vertical retrace interval. Would.   The invention further comprises means for selecting one of the m teletext data streams; The next or subsequent vertical retrace of the supply of the selected data stream to the text decoder Means for delaying until the occurrence of a period. A television receiver adapted to receive teletext data transmitted therefrom Provide a shinki.   In other words, the selection and delay means are provided in the television receiver, so that the selection can be made. The teletext data stream is supplied to the teletext decoder during the vertical retrace interval. obtain. In this way, a standard teletext decoder is used to provide the text provided to the decoder. It will recognize and decode the text signal.   The invention further provides that the television signal is generated by the method according to the invention. Means having text data, wherein the decoder selects one of the m data streams; Means for supplying the selected data to a teletext decoder during a vertical blanking period; Providing a decoder for decoding a television signal, comprising: You.   Decoder, for example, decodes digital video broadcasts from satellite or terrestrial transmitters To decode or decode cable television signals No, it may be a so-called set-top box. Decoders are customarily For example, charging for a channel or pay-per-view application And access control.   The above and other features and advantages of the present invention will now be described, by way of example, with reference to the associated drawings. It will be clear from the following description of an embodiment of the invention given. BRIEF DESCRIPTION OF THE FIGURES   FIGS. 1 to 3 show a normal teletext data signal and a full-channel teletext signal. 3 illustrates a text data signal.   FIG. 4 shows how the selected service can be time-shifted It is a timing chart which shows whether it is.   FIG. 5 shows the teletext data from a video cassette recorder according to the invention. It is a block diagram which illustrates reproduction | regeneration.   FIG. 6 is a block diagram of the service selection function of the video cassette recorder shown in FIG. It is a lock figure.   FIG. 7 shows a combination of a teletext data service and a low and high television image. Are shown.   FIG. 8 illustrates a process for selecting a particular data stream from a number of data streams. ing. BEST MODE FOR CARRYING OUT THE INVENTION   FIG. 1 shows a transmission during a vertical retrace interval represented by period A in the figure. And the remaining text represented by period B in the figure. A typical television program including television image information transmitted during One field of the input signal is shown. Typically, teletext decoders are Between lines 6-22 of field 1 and lines 319-335 of field 2 It will be configured to seek teletext data. This is the standard 625 It relates to the PAL television signal of the line. In contrast, full channel teletext Except for the short field sync sequence shown in FIG. Occupies the entire length of the field. That is, the teletext data is During the threshold period B, is replaced with the television image signal. Such a full channel The teletext signal is known, but the teletext decoder only allows the text during VBI. Standard television reception because it is set to require text data Machine cannot decrypt. Request teletext data only during VBI One reason for imposing on teletext decoders is that text that mimics teletext data This is to prevent erroneous detection of the teletext signal by the revision image signal . That is, some image content may generate signals similar to teletext data. Instead, the teletext decoder may decode this signal as teletext data. There is. However, the teletext decoder may only teletext during VBI. Ensuring that image data is sought, such image content The possibility of incorrect detection of the text data can be eliminated. Only However, in this case, the full channel teletext data cannot be decoded. There is a corresponding disadvantage.   FIG. 3 shows a plurality of separate data each having a duration shorter than the length of the VBI. Figure 4 shows full channel teletext data divided into streams. That is, Text data is, for example, 20 separate data items each occupying 15 lines It may be divided into streams. Of course, the number of lines in each data stream is the number of lines in VBI Each of these 20 separate data streams is the same, provided that It is not necessary to occupy one line number. In addition, the line in any data stream It is not necessary that everything be occupied by teletext data. These 20 Each of the separate data streams can transmit, for example, 20 services. Provide individual services that allow the user to choose between these services Will be.   In order to decode the full channel teletext data, these 20 separate data One of the data streams is selected, and the occurrence of the selected data channel corresponds to VBI. Means are provided for shifting during the period of time.   FIG. 4 illustrates this process. As shown in FIG. 4a, the data stream 6 As shown in FIG. 4b, the data in the data stream 6 is selected in a buffer memory. Assume that an enable signal (circuit) is generated that allows writing to You. This is illustrated in FIG. That is, it usually contains a TV image signal but is full. If channel teletext is being sent to channel 6 of teletext data Data is written to the buffer memory during the more occupied lines. Next, The fast memory is read during the next field VBI and is therefore The text decoder will recognize this as teletext data. That is, LeChannel teletext data service into m streams each occupying n lines By splitting, one of these data streams is selected and the data stream is To the teletext decoder. In certain embodiments, m Is equal to 20, and n is equal to 15. These numbers are not required and the requirements are The number of lines in the data stream is equal to or less than the number of lines in the VBI, Within the number of lines that the text decoder considers to be capable of containing teletext data That said, the number of streams depends on how many lines are in the television field To occupy the entire television field with teletext data It will depend on what you want.   Teletext data sources can be terrestrial transmitters, satellite transmitters or cable television. Normal television transmission from any of the services may be used. Other examples smell In some cases, the data source may be a record carrier, for example, an optical disk or magnetic tape. good. Cable television system or satellite broadcasting or cable satellite or ground In the case of the proposed digital service from the above transmitter, the decoder box is It may be inserted before the standard television receiver. Such a decoder box is , Convert the transmitted signal from one encoding format to, for example, a PAL system And may be configured to provide an RGB output. Mae Nagisa, Teletext The television decoder contains a television receiver containing encoded teletext data. Installed in the television receiver to receive at least a CVBS signal. In the latter case, the teletext decoder will determine where the teletext signal is Must be installed in the decoder box for reasons that exist and can be decoded Will not. Playback from an optical recording and playback device or from a video tape recorder. For this reason, the teletext decoder is used in either the playback device or the television receiver. It may be. If it is in a television receiver, of course, The connection to the vision receiver is in CVBS form, ie the modulation back to the PAL channel is Need to be done.   Record standard teletext data with good results from VHS video cassette recorder It is well known that it cannot be played back. This is the above recorder This is because the bandwidth is insufficient for the bandwidth of the teletext signal. That is, During production, a distorted signal is generated that cannot be decoded and is satisfactorily processed. Unable to achieve receipt of the text. However, UK Patent Application No. 96 05614. No. 8 (PHB34056) using the technology disclosed in Teletext on VHS tape. Strike data can be recorded. This application is to enter teletext data A code that encodes the data into a multilevel signal at half the rate of standard teletext Describes a VHS video recorder that includes a digitizer. That is, a collection of 2 bits each The collection is encoded using a four-level code, and this four-level code is Written on the loop. During playback, the four-level code is converted to standard teletext data. A complementary decoder for converting data back to data is used. This standard teletext The data is then transmitted to the VCR or the television receiver connected to the VCR. It can be supplied to a teletext decoder installed in either. This encoding and decoding Details of a video cassette recorder capable of performing these functions are provided by the applicant. Co-pending application 9605614. No. 8 (PHB34056), the contents of which are referenced Hereby incorporated by reference.   FIG. 5 illustrates a telecommunications scheme in accordance with the measures outlined in the above-mentioned co-pending application. VCR that encodes text signals and provides full-channel teletext services 3 is a block diagram of a reproduction function of FIG. The actual source of the data on the tape is in accordance with the present invention. This block diagram only shows the playback function, not the recording function. Not shown. That is, the data is already recorded by the service provider It may be from a recording tape, or may be what you recorded from the broadcast (off air). Would. This record is not relevant to the present invention. As shown in FIG. 5, the playback function It includes a tape reproducing head 1 to be supplied to a luminance processing device 2. This brightness processing device Is simply a standard VCR luminance processor. The output of the luminance processing device is , The control and timing circuit 4 and the multiplexer 5. Decor The output of the memory 3 is supplied to the buffer memory 6. The output of the buffer memory 6 is It is supplied to the text encoder 7. The teletext encoder 7 is Convert the output of Faram to standard teletext data format. Control and timing Circuit 4 inputs timing information from a signal generated by the luminance processing device 2. Then, the operation of the decoder 3 is controlled. That is, the decoder 3 performs control and timing operations. Output from the luminance processing device at an appropriate time during each line period under the control of the road 4 Will decrypt the data. Conveniently, the decoder uses this data line by line. , And the output of the decoder is It is read into the buffer memory 6 under control. That is, the service selector 8 Only when the selected service is output by the luminance processing device 2 is the data It will ensure that it is written into the buffer memory 6. Control and timing The output from the buffering circuit 4 is also used to store the data in the buffer The buffer is used as a read enable signal to be read by the text encoder. It is supplied directly to the memory 6. That is, during normal field video The data written in the RAM is stored in the buffer memory 6 and the subsequent VBI Is read during. To enable the selection of a particular service, the recorder Includes a remote control receiver 15 that receives signals from the remote control type handheld device 9. That is, the command input to the remote control handheld device 9 is detected by the receiver 15 and the control is performed. And the timing circuit 4. As a result, the service selector 8 At a short time, a write enable signal is generated in the buffer memory 6 to select the selected data. The flow It will be possible to write into the buffer memory 6. Multiplexer 5 Controlled by another output from the control and timing circuit 4, the full channel Either text or mixed teletext and video signals are recorded on the tape. Depending on the data from the teletext encoder 7 or from the luminance processing device 2 Select one of the videos. The output of the multiplexer is supplied to output 10 Supplied to the television set via the SCART connector or CBVS signal supplied to the data 11. In the modulator 11, this signal The signal is modulated on a UHF carrier and the associated television receiver antenna input Via the output 12.   FIG. 6 is a block diagram of an embodiment of the service selector 8 shown in the VCR of FIG. FIG. This service selector has an input 80, which is Is supplied to the register 81 for storing the requested service number. Les The output of the register 81 is supplied to a first input terminal of a comparator 82. Of the comparator 82 The input terminal 2 is connected to the output terminal of the service counter 83. Service selector The input terminal 84 at 8 inputs a pulse at the line frequency. These pulses are It is supplied to a line counter 85. This line counter also indicates the end of each field. Instead, a reset signal for resetting the line counter is input from the input terminal 86. Will. The line counter has an output terminal connected to the service counter 83. Have. That is, in the given example, the line counter will service every 15 lines. Will increment the counter. The output of the comparator 82 is a multiplexer 87 to a first input. The second input of the multiplexer 87 is connected to the input A timing signal is input through the terminal 88. Which input of multiplexer 87 A control signal for controlling whether the signal is supplied to the force terminal 90 is supplied to the input terminal 89. Control signal No. 89 is provided with a normal teletext and video composite signal or full channel Indicates whether the teletext data is provided. Time at input 88 Signal is selected when a combined teletext and video signal is provided This is a normal VBI timing. If a full channel teletext is given, The output of the comparator is output as a write enable signal for the buffer memory 6. Feed to end 90. This is where the service flow requested is given. In this case, the decoded data is read into the buffer memory 6. That is, the comparison The write enable signal is output by the output of the detector to decode the selected service 15 Will be given for the line.   FIG. 7 shows an example in which the increased teletext data is transmitted and the low and high TV images are transmitted. The image also shows the situation in which it is transmitted. This is, for example, a letterbox type image. Transmitting an image and some of the active image lines are available for teletext That could be the case. That is, a TV with an aspect ratio of 4 × 3 An image with a 16x9 aspect ratio displayed on the screen with additional teletext Leave some lines above and below the images available for data services Would be. The teletext data contained in these lines is Time shift in the same way as Nel teletext data is time shifted to VBI I can do it.   FIG. 8 shows a multi-channel teletext signal transmitted according to the invention. 5 illustrates a process of selecting a specific data stream from a number of data streams. Box 90 Reads data from the tape indicating whether full channel data is valid. Represents the steps taken. Reading this data from the tape will show which channel An on-screen display is started asking the user to select whether to display the Box 91). This means that the user presses a numbered key on the remote control unit. This is achieved by: This allows the user to enter numbers by remote control Represented by box 92. Then, on-screen what services were selected Check the lean display. This is represented by box 93. That is, onsk The lean display will say, for example, that you have selected service 6. Then , This number is introduced into the service number register 81, so that the service selector A particular data stream will be selected (box 94).   From reading the present disclosure, other modifications will be apparent to persons skilled in the art. like that Modifications include television receivers and / or video containing teletext decoders Other features already known in the design and use of recorders and their components And these features may be used instead of or in addition to the features described here. Can be. In this application, claims are made for specific combinations of features. However, the scope of the disclosure of the present application is hereby expressly or implicitly disclosed. All new features or all new combinations of those features, Whether or not they relate to the same invention as presently claimed in any of the claims. Including any general concept of one or more features that would be obvious to one of ordinary skill in the art. I want to be understood. In addition, the applicant may use the features described above and / or combinations of such features. At the stage of examination of this application or any other application derived from this application. Note that it may be described in the range.

Claims (1)

[Claims] 1. In the method of transmitting teletext data,   a) The teletext data is included in at least a part of the field period outside the vertical blanking period       Sending data,   b) the teletext into m separate data streams each occupying up to n lines       Splitting the data,       m and n are integers, and n is equal to or less than the number of lines in the vertical flyback period;   A transmission method characterized by the above-mentioned. 2. 2. The transmission method according to claim 1, wherein the teletext data is a cable.   A transmission method, wherein the transmission is performed via a television channel. 3. 2. The transmission method according to claim 1, wherein the teletext data is a record carrier.   A transmission method characterized by being recorded above. 4. 4. The transmission method according to claim 3, wherein the record carrier is a VHS video tape.   A transmission method, characterized in that: 5. 5. The transmission method according to claim 4, wherein the teletext data is a standard text.   Record as a multi-level signal at a data rate lower than the textual data rate   Transmission method characterized by being performed. 6. The transmission method according to claim 1, wherein n = 15.   And a transmission method. 7. 7. The transmission method according to claim 1, wherein m = 20.   And a transmission method. 8. In a record carrier carrying teletext data,     The teletext data includes at least a field period outside a vertical blanking period.   The teletext data spreads out partially, and m teletext data each occupy up to n lines   Of data streams, where m and n are integers, where n is the vertical retrace interval.   A record carrier, the number of lines being equal to or less than the number of lines. 9. 9. The record carrier according to claim 8, wherein the record carrier is a VHS tape.   A record carrier characterized by the above. 10. 10. The record carrier according to claim 9, wherein the teletext data is a standard teletext data.   As a multi-level code at a lower data rate than the teletext data rate   A record carrier characterized by being stored. 11. 8. Transmitted by a method according to any one of claims 1 to 7, or claimed.   Teletext data reproduced from a record carrier according to any one of claims 8 to 10   In the method of decrypting   a) a step of selecting one of the m data streams of the input teletext data;       And   b) applying the teletext signal containing the selected data stream to a vertical blanking interval;       Supplying to the text decoder.   A decoding method characterized by the above-mentioned. 12. 10. Reproducing teletext data recorded on the record carrier according to claim 8 or 9.   Video playback device,     Means for selecting one of said teletext data streams for playback;     Obtaining the selected teletext data stream at the output during a vertical retrace interval.   Means for reproducing the video. 13. 13. The video camera according to claim 12, which is cascaded to claim 9 having a VHS video recorder.   In the video playback device, the video recorder is read from the tape.   Features include means for encoding multi-level codes into standard teletext data.   Video playback device. 14． 14. Teletext data is input from the video playback device according to claim 12 or 13.   A television receiver connected to power up. 15. Teletext transmitted by the method according to any one of claims 1 to 7.   In a television receiver configured to receive data,     means for selecting one of the m teletext data streams;     Supplying the selected data stream to a teletext decoder in the next or subsequent   Means for delaying the occurrence of a vertical blanking period.   Receiver. 16. Teletext generated by a method according to any one of the preceding claims. In a decoder for decoding a television signal having data,   means for selecting one of the m data streams;   Means for supplying the selected data to a teletext decoder during a vertical blanking interval And a decoder comprising: