JPH06296267A - Teletext receiving method - Google Patents

Abstract

PURPOSE: To shorten delay between page selection and display by providing a teletext reception equipment having a page memory where a prescribed number of pages which a user selects most frequently are stored. CONSTITUTION: A teletext page subjected to serial-parallel conversion is displayed from a video VT signal in accordance with user's selection of a page identifier. Therefore, a page selection memory 30 where information indicating frequencies in user's selection of page identifiers is stored and a controller 40 as a means which detects the prescribed number of most frequently selected page identifiers are provided. Further, a page memory 60 where teletext pages corresponding to these most frequently selected page identifiers are stored and a read comparator 90 which retrieves teletext pages from the memory 60 in accordance with selection of page identifiers corresponding to teletext pages stored in this memory 60 are provided. Thus, the delay between user's selection and teletext page display is shortened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a teletext receiving system.

[0002]

BACKGROUND OF THE INVENTION Teletext data, which consists of character and graphic control codes, is transmitted between video lines during the vertical (or field) blanking interval of broadcast television signals. In the teletext system used in the UK and several other countries, the data is 40 x 24 per page.
It is arranged as a contiguous page of lines of text characters. The teletext receiving device converts the teletext data from the television signal into serial-parallel data and displays the page selected by the user (user).

Only a limited number of video lines can be used in the vertical blanking period to transmit teletext data. For example, in the phase alternating line (PAL) transmission standard used in the United Kingdom, lines 11-18
(Even fields) and lines 324-331 (odd fields) are reserved for teletext. During the active line period of each teletext line, five sync symbols (codes) and 40 characters (ie one line of the teletext page) are transmitted digitally, so one line of heading and 24 lines of text. It takes about 3 video fields (0.06 seconds) to send one full page of line teletext.

A typical teletext service (supply) corresponding to one television channel may include hundreds of pages of teletext, and these pages are periodically provided with a period of, for example, 20 seconds. Has been sent. Therefore, when the user selects a specific page, the page cannot be displayed until the page is transmitted in the next cycle. This causes a delay between the selection and display of a page, the length of the delay depending on which point in the cycle the page was selected.

To reduce the delay between page selection and display, the so-called "Fastext" method has been proposed. This scheme sends each page along with pointers to four other pages that the user normally selects after reading the page. The Fastext receiver detects the four pointers, performs serial-parallel conversion, stores the other four pages, and immediately displays them when the user selects those pages. However, if the user selects another different page, there is still a delay between the selection and the display to access that page.

[0006]

The object of the invention is therefore to reduce the time delay between the user's selection and the display of a teletext page.

[0007]

A teletext receiver according to the present invention displays a teletext page obtained by serial-parallel converting a video signal when a user selects a page identifier corresponding to the teletext page. , The following components, that is, means for storing information indicating the relative frequency with which the user selects the page identifier, and selection frequency detection means for detecting a predetermined number of the most frequently selected page identifiers, When a user selects a page memory that stores a teletext page corresponding to the most frequently selected page identifier above, and a page identifier corresponding to a teletext page stored in the page memory, a display is displayed. Means for retrieving the teletext page from the page memory.

The present invention provides a teletext receiver having a page memory that stores a predetermined number of pages that the user of the teletext receiver selects most often, thereby providing the problem of delay between page selection and display. To solve, or at least reduce. This is in contrast to, for example, the Fastext scheme, which relies on page selection frequencies that are suitable for all users of a particular teletext service.

In one preferred embodiment, the storing means comprises a plurality of addressable entries (storage locations).
Each entry stores a selection frequency value for each page identifier, and has a memory address corresponding to each page identifier. The storage means also includes means for incrementing (incrementing) the selection frequency value for the selected page identifier when the user selects the page identifier.

In another preferred embodiment, the memory size required for the storage means can be reduced by using the following storage means. That is, each entry is stored in the first and second memory areas, each having a plurality of entries storing one page identifier and a selection frequency value relating to the page identifier, and the entry in the first or second memory area. Means for incrementing the selection frequency value relating to the selected page identifier when the user selects a page identifier that is not stored in the entry of the first or second memory area, In the entry of the second memory area, and means for overwriting on the most recently stored (least frequently) page identifier of the second memory area, and the entry of the first memory area is the entry of the second memory area. When it is detected that it has a lower selection frequency value, the first
A storage means is used which comprises means for exchanging an entry in the memory area with an entry in the second memory area.

The selection frequency value stored in the storage means can be effectively used in a specific configuration in which the selection frequency detection means detects a predetermined number of highest selection frequency values stored in the storage means. it can.

The storage means may be arranged such that the maximum selectable frequency value that can be stored is sufficiently large in view of the teletext page selection over the entire life of the teletext receiving device. It can be very slow for the storage means to respond to changes in the user's page selection habits (e.g., when the receiving device is sold or given to a new user). Therefore,
Means for detecting whether one or more selection frequency values are equal to a predetermined maximum value, and decrementing at least some of the selection frequency values when detecting that one or more selection frequency values are equal to the maximum value. It is better to use means (reduce one). The predetermined maximum value can be selected such that the storage means responds reasonably and promptly as described above, without responding to the pseudo page selection.

The decrement means may include means for decrementing all the selection frequency values stored in the storage means. However, in another preferred embodiment, the decrementing means comprises the selection means stored in the storage means so that small selection frequency values can be accumulated even when other selection frequency values reach a predetermined maximum value. Among the frequency values, those within a predetermined range of the maximum value are decremented.

The teletext receiving device is provided with a predetermined number of the most frequently selected page identifiers so that the searching means can detect when the page memory has stored the teletext page identifiers in the list below. A list containing
Teletext corresponding to each page identifier in the list
Means may be provided for storing a respective storage flag indicating that the page has been stored in the page memory.
In this case, the teletext receiving device comprises means for controlling the storage in the page memory of a teletext page which is currently serial-to-parallel converted and has a page identifier identical to the page identifier in the list of page identifiers; Means for generating a storage flag for the page identifier indicating that the teletext page being deserialized has been stored in the page memory.

For example, only the page number can be used as the page identifier, but each page identifier preferably includes the page number and the television channel number (the television channel number selected by the user is Probably constant for several page numbers to be selected subsequently, though). In this case, the most frequently selected page from any channel may be detected and stored,
In order to make effective use of the page memory, the selection frequency detection means is preferably operable to detect a predetermined number of the most frequently selected page identifiers for the currently receiving television channel.

In a second aspect, the present invention receives a deserialized teletext page from a video signal,
Provided is a teletext decoding device which operates to output a teletext page for display when a user selects a corresponding page identifier. The decryption device
Means for storing information indicating the relative frequency with which the user selects the page identifier, selection frequency detection means for detecting a predetermined number of the most frequently selected page identifiers, and the most frequently selected page identifier Page memory for storing teletext pages corresponding to
When a user selects a page identifier corresponding to a teletext page stored in memory, the teletext page is retrieved from the page memory and the teletext page is output for display. And means.

Viewed from a third aspect, the present invention provides a teletext receiving method for displaying a teletext page serial-parallel converted from a video signal when the user selects the corresponding page identifier. The method comprises storing information indicating the relative frequency with which the page identifier is selected by the user, detecting a predetermined number of the most frequently selected page identifiers, Page the corresponding Teletext page
Storing in memory, detecting whether a teletext page corresponding to the user-selected page identifier is stored in the page memory, the teletext page stored in the page memory The step of retrieving the teletext page from the page memory for display is selected by the user when the page identifier corresponding to is selected.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a teletext receiver according to the present invention. In the figure, a teletext serial-parallel converter 10 receives a television (TV) signal and serial-parallel converts the teletext information from the TV signal. It is always possible to display either or both of the serial-parallel converted teletext information and the normal image information extracted from the TV signal by the teletext receiving device.

As mentioned above, the teletext page is
It is continuously received on the video line of the vertical blanking period of the TV signal. Each page takes about 0.06 seconds to send and includes a page heading line that specifies the page number corresponding to the page. The teletext serial-parallel converter 10 has 3
Provides two output signals. That is, the T currently being received
The current channel identifier indicating the V channel, the current teletext page number obtained from the header row of the page currently being received, and the serial text teletext page data itself.

The page selector 20 includes a page number selected by the user under the control of the user (eg, by a handset or a remote commander) and a TV channel number selected by the user (this is a sequence of several page numbers). Is likely to be constant.) Ch and a selection signal sel indicating that a page or channel is newly selected are output. The three outputs of the page selector 20 are input to a page selection memory 30, which stores the relative selection frequency of the teletext pages used. Page select memory 30 is a non-volatile random access memory (RAM) having multiple address locations, each of which may store a multi-bit data word. The concatenation of the selected page number and the selected channel number is the memory address in which the selection frequency value corresponding to the page number and the channel number is stored. The page selection memory 30 has a sufficient number of address locations to store selection frequency values for each possible page number and channel number combination.

When a new page or channel is selected (selection signal sel is applied to the increment terminal Inc), the selection frequency value stored in the memory address corresponding to the newly selected page number and channel number is incremented. . Since the page selection memory is non-volatile, the selection frequency value stored therein represents the relative frequency of page selections made by the user over a period of time.

The controller 40 uses the page selection memory 3
Access 0 to determine the N most frequently selected page numbers. The controller 40 cycles through the addresses of the page selection memory 30 to detect the N highest selection frequency values. If one or more selection frequency values is at the maximum value that page selection memory 30 can store (eg, for an 8-bit memory, the maximum selection frequency value would be 255), then it is stored in the page selection memory. All selected frequency values are decremented. (Alternatively, only the selection frequency value that has reached the maximum value or only the selection frequency value within a certain range of the maximum value may be decremented. In this way, a small selection frequency value is reduced to another selection frequency value. Can be accumulated even when the value reaches the maximum value above.)

The controller 40 outputs a page list showing the N most frequently selected page and channel number combinations. This page list is stored in the list memory 50.

Teletext data representing the N most frequently selected pages (ie, the identified pages in the list of pages held in list memory 50) is:
It is stored in the N page memory 60 under the control of the write comparator 70. The light comparator 70 receives the current page number and the current channel number from the teletext serial-parallel converter 10 and compares these values with the page list held in the list memory 50. This comparison is the time between the reception of the header row of each page (including the page number of the page) and the output of teletext page data for the page by the teletext serial-to-parallel converter 10 (approximately 9 Microsecond period).
When the current channel number and the current page number match the page list entry, the write comparator 70 issues a write enable (WE) signal to indicate the current page.
Controls (permits) the writing of data to the N page memory 60. The write comparator also issues an "end of storage" flag associated with that entry in the page list to indicate that the page data has been stored.

The list memory 50 and N-page memory 60 may be volatile or non-volatile memory. With non-volatile memory, when the teletext receiver is switched on, the stored page data will be immediately accessed, but that data will be received by the receiver during its previous use. It will be about the page you did.

Each teletext page has 40 × 24
Line = consisting of 960 text characters. Therefore, about 1 kilobyte (1024 bytes) of memory is sufficient to store the entire page together with the page identification data. Thus, the N page memory 60 can be implemented as an N kilobyte RAM.

Data representing one page to be displayed is stored in the display memory 80. To display the page selected by the user, the page data retrieved from the N page memory 60 or the page data currently being received is written to the display memory 80. It depends on whether it is one of the N most frequently selected pages stored in page memory 60. Reading from the display memory 80 is performed continuously according to the scanning of an output display device such as a cathode ray tube.

The read comparator 90 receives the page number selected by the page selector 20 and compares it with the entry in the list memory 50. When the page number is held in the list memory 50 and the "storage end" flag corresponding to the page number is issued (indicating that the page has been stored in the N page memory 60), a read is performed. The comparator 90 outputs a read enable (read enable) “RE” signal to control the reading of the page from the N-page memory 60. This RE signal also serves two other functions. That is, switch 1
Control 10 to select the output of N page memory 60 as the data input to display memory 80, and
It is supplied as an input to the R gate 120 to generate a WE signal to control writing to the display memory 80.

The selected page number is the list memory 5
If it is not held at 0, or if the respective "end of storage" flag has not been issued (indicating that the page has not been written to the N page memory 60),
The read comparator 90 controls the switch 110 to cause the page data currently being received to be selected as an input to the display memory 80. Writing of the page data currently being received into display memory 80 is controlled by a page comparator 130 which compares the selected page number with the current page number from teletext serial-to-parallel converter 10. If the current page number matches the selected page number, the page comparator 130
Generates a WE signal which is sent to the display memory 80 via the OR gate 120 to control (permit) the writing of the current page data to the display memory 80.

FIG. 2 is an explanatory diagram of the list memory 50 shown in FIG. The list memory 50 has a fixed number (N) of entries (memory locations) illustrated schematically as columns 55. Each entry stores a page number, a channel number, and an “end of storage” flag indicating whether the page is stored in the N-page memory 60.

In another embodiment, the controller 40 is
Select the N most frequently selected pages from the current channel only. This is a controller 40 that changes only the page number when addressing the page selection memory 30.
Reached by. In this case, the list memory 50 is
It need only have an entry that stores the page number and the "end of storage" flag. When the user selects a new channel, controller 40 resets all "end of store" flags in list memory 50.

The page selection memory 30 described with reference to FIG.
Has one address location for each possible page number and channel number combination. However, if multiple TV channels are available and each channel has multiple teletext pages (eg, cable television equipment), not only is the page selection memory 30 large, but the controller 40 also has multiple entries. We have to determine the N most frequently selected pages to cycle through and use for the page list.

FIG. 3 is an explanatory diagram showing another example of the page selection memory of FIG. In the figure, reference numeral 150 designates a page selection memory which requires a smaller number of address positions. Each memory (address) location is arranged to store a channel number, a page number and a selection frequency value for the combination of the channel number and page number. The page selection memory 150 has address locations A _{1 to} A _1.
and "A" region with _n, with the address location B ₁ .about.B _m made more "B" region. The total number of entries in page selection memory 150, n + m, is chosen to be greater than the number of different pages that a typical user would normally access.

When a new teletext page is selected, if the page number and channel number already exist in either the A or B area of the page selection memory 150, the selection frequency value at that location is incremented.
However, when the combination of the page number and the channel number does not exist in the page selection memory, the data stored in the B _m position is discarded and the data stored in the B _m-2 position is replaced with the B _m-1 position. Move to. In the same manner, finally, the newly selected combination of the page number and the channel number is written in the free position B ₁ . In this way, the newly selected page number and channel number are stored in the page selection memory 1
It will be overwritten on the most recently written (least frequently) combination of page number and channel number in the 50 B area.

The controller 40 uses the page selection memory 1
Each time it detects that an entry in the 50 area B has a higher selection frequency value than an entry in the A area, it replaces those two entries. When any of the selection frequency values reaches the maximum value that can be stored in the page selection memory 150, the controller 40 decrements some or all of the selection frequency values stored in the A area.

The page selection memory 150 requires a significantly smaller storage space than the page selection memory 30. However, page numbers not previously selected by the user may be listed on the most frequently selected pages.

Although the present invention has been described with reference to the teletext receiving apparatus shown in FIG. 1, the present invention is a teletext decoding apparatus that operates to receive teletext data that has already been serial-parallel converted from a video signal. Can be similarly embodied. Although the present invention has been described as being implemented by hardware, other specific configurations using a general-purpose data processing device that operates under the control of appropriate computer software are also possible.

[0038]

As described above, according to the present invention, it is possible to obtain a teletext receiving apparatus in which there is no time delay between the selection by the user and the display of the teletext page.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a teletext receiver according to the present invention.

FIG. 2 is an explanatory diagram of a list memory shown in FIG.

FIG. 3 is an explanatory diagram showing another example of the page selection memory of FIG.

[Explanation of symbols]

30 page selection memory (storage means for selection frequency information) 40 controller (maximum selection frequency detection means) 60 N page memory (teletext page memory) 80 display memory 90 read comparator (teletext search means)

Claims (17)

[Claims] 1. A teletext receiving device for displaying a teletext page obtained by serial-parallel conversion from a video signal when a user selects a corresponding page identifier, wherein the user selects the page identifier. Means for storing information indicating the target frequency, a selection frequency detecting means for detecting a predetermined number of the most frequently selected page identifiers, and a teletext page corresponding to the above most frequently selected page identifiers And a means for retrieving the teletext page from the page memory for display when the user selects a page identifier corresponding to the teletext page stored in the page memory. Teletext receiver equipped. 2. The storage means comprises a plurality of addressable entries, each entry storing a selection frequency with respect to a respective page identifier and a memory address corresponding to the respective page identifier. 2. The receiver of claim 1, comprising: a memory comprising; and means for incrementing a selection frequency value for the selected page identifier when the user selects the page identifier. 3. The first and second memory areas, wherein the storing means has a plurality of entries, and each of the entries stores one page identifier and one selection frequency value related to the page identifier. And a means for incrementing a selection frequency value related to the selected page identifier when the user selects a page identifier stored in the entry in the first memory area or the second memory area, the first memory area or the When the user selects a page identifier that is not stored in the entry of the second memory area, the selected page identifier is stored in the second memory area and the smallest page identifier recently stored in the second memory area is stored. Means for overwriting, and a selection mode in which the entry in the first memory area is lower than the entry in the second memory area. When it is detected that with the receiving apparatus according to claim 1, the entry of the first memory area equipped with an entry and Tokaeru means of the second memory area. 4. The receiving apparatus according to claim 2, wherein the selection frequency detecting means operates to detect a predetermined number of maximum selection frequency values stored in the storing means. 5. Means for detecting whether one or more of said selection frequency values are equal to a predetermined maximum value, and said selecting if one or more of said selection frequency values is equal to said predetermined maximum value. The receiving device according to claim 2, comprising means for decrementing at least some of the frequency values. 6. The receiving apparatus according to claim 5, wherein said decrementing means has means for decrementing all of said selection frequency values stored in said storing means. 7. The reception according to claim 5, wherein said decrementing means includes means for decrementing selection frequency values stored in said storing means within a predetermined range of said maximum value. apparatus. 8. The receiving apparatus according to claim 3, wherein the selection frequency detecting means operates to detect a predetermined number of optimum selection frequency values stored in the storing means. 9. Means for detecting whether one or more of said selection frequency values are equal to a predetermined maximum value, and said selection frequency if said one or more of said selection frequency values is equal to said predetermined maximum value. 4. The receiving device according to claim 3, comprising means for decrementing at least some of the values. 10. The receiving apparatus according to claim 9, wherein the decrementing unit has a unit for decrementing all the selection frequency values stored in the storing unit. 11. The receiving apparatus according to claim 10, wherein said decrementing means has means for decrementing a selection frequency value stored in said storage means within a predetermined range of said maximum value. 12. A list containing the predetermined number of most frequently selected page identifiers and a teletext page corresponding to each page identifier in the list is the page.
2. The receiving device according to claim 1, further comprising means for storing respective storage flags indicating that the storage has been completed in the memory. 13. Means for controlling storage in said page memory of a teletext page currently being serial-parallel converted having a page identifier identical to the page identifiers in said list of page identifiers, and present serial-parallel. Means for generating the storage flag for the page identifier indicating that the teletext page being converted has been stored in the page memory. 14. The receiving apparatus according to claim 1, wherein each of the page identifiers includes one page number and one television channel number. 15. The receiving apparatus according to claim 14, wherein the selection frequency detecting means operates to detect the predetermined number of the most frequently selected page identifiers for the currently receiving television channel. 16. A teletext decoding device that operates to receive a teletext page that has been serial-parallel converted from a video signal, and to output the teletext page for display when the user selects the corresponding page identifier. And a means for storing information indicating the relative frequency with which the user selects the page identifier, a selection frequency detection means for detecting a predetermined number of the most frequently selected page identifiers, and the most frequent selection A page memory storing a teletext page corresponding to the stored page identifier and a page identifier corresponding to the teletext page stored in the page memory, the user selects the teletext page as the page.・ Search from memory,
A teletext decoding device comprising means for operating to output the teletext page for display. 17. A teletext receiving method for displaying a teletext page that has been serial-parallel converted from a video signal when the user selects the corresponding page identifier, wherein the page identifier is selected by the user. Storing information indicating the target frequency, detecting a predetermined number of the most frequently selected page identifiers, and storing the teletext page corresponding to the above most frequently selected page identifier in the page memory. Detecting whether a teletext page corresponding to the page identifier selected by the user is stored in the page memory; a page corresponding to the teletext page stored in the page memory; When the user selects an identifier, the teletext page is displayed from the page memory for display. Teletext receiving method comprising the steps of searching the di.