JP2752068B2 - Teletext receiver - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention relates to a teletext receiving apparatus provided with a page memory, and is also applicable to a case where a channel is switched while writing teletext data. The present invention relates to a teletext receiver in which a program is written in page memory in page units. (Prior Art) Teletext broadcasting is a system for repeatedly transmitting various types of teletext programs in the form of digital signals during a specific horizontal scanning period of a vertical retrace period of a television signal. The receiving side has a buffer memory for receiving teletext data, and sequentially writes the transmitted signals into the buffer memory. Then, the receiver specifies the program number of the desired program using a keyboard or other means, and the specified program is retrieved from the buffer memory. It can be performed. In such a receiving system, when the number of programs increases, the time required to transmit all programs becomes longer, and the waiting time until the designated program is presented on the screen becomes longer. Therefore, conventionally, a page memory for storing text broadcast data for a plurality of screens is provided, and the program desired by the receiver is stored in the form of program number registration, thereby eliminating the waiting time. FIG. 4 is a memory map showing the operation of the page memory. FIG. 4a shows the receiving order of the teletext data (the order in which the data is held in the buffer memory). Now, when registering the program of program number 0 / 012,0 / 013,0 / 014,0 / 015 ...
As shown in FIG. 4b, when one page of data is received, each program is held in the page memory in the order of reception. When the time further elapses, the page memory is rewritten with data as shown in FIG. 4c. The bold line indicates this rewriting time. Therefore, the program secured in the page memory at each rewriting time can be received without waiting time. Also, in the case of a multi-page program, even if the program is not entirely stored in the page memory, the stored portion is received without waiting time, and during that time, data of an unregistered page is transmitted. If it comes, the whole program can be received without waiting time. On the other hand, teletext is broadcast not only on one television channel but also on a plurality of channels. Therefore, in order to receive a teletext program, the receiving channel of the television tuner is set to the channel on which the program is being broadcast, and then the program is selected. The same applies to the case where a teletext program is registered in the page memory. After switching the receiving channel, a program number is designated and a desired program of the channel is registered. However, since teletext is transmitted in a packet format during a limited plurality of horizontal scanning periods in a vertical blanking period, 1
It takes a predetermined time until the page data of one program is transmitted and the entire page data is stored in the page memory. Therefore, if the channel is changed in the middle of the page,
Since the data of the page is not written to the page memory from the middle of the switching, the character image is interrupted in the middle of the screen when the program is presented. FIG. 5 is an explanatory diagram for explaining an operation when all page data cannot be written as described above.
5a, 5b, and 5c show the text broadcast data sequence in the receiving order and the data content of the page memory corresponding to FIGS. 4a, 4b, and 4c, respectively. In FIG. 5A, when the data is switched to the fourth channel while the data of the first channel having the program number 0/014 and the page number 02 is being transmitted, the received data is replaced with the data of the fourth channel. I will. Therefore, program number 0 /
The teletext program of the first channel transmitted in 014 is not received except for the dotted line portion in the middle of the data of the second page, and the 0/014 program is located in the area indicated by page "2". Only a fixed amount will be written. However, at the time of the presentation process, all the contents of this page area are displayed, and the screen of this page lacks information. Such inconvenience has always occurred, for example, when registering a teletext program between different channels, because the information for writing data is unknown to the operator. It is also conceivable that this may occur when the user inadvertently switches to another channel to watch a television broadcast during the registration operation. (Problems to be Solved by the Invention) A conventional teletext receiving apparatus having a page memory is:
If the channel is switched in the middle of the data for the page, the data received so far is written to the page memory, but the remaining data is not written, so a character image with missing information is displayed during the presentation process. There was an inconvenience. SUMMARY OF THE INVENTION It is an object of the present invention to eliminate the above-mentioned problems and to provide a teletext receiver which does not display a screen lacking data. [Structure of the Invention] (Means for Solving the Problems) The present invention receives a teletext signal multiplexed during a vertical retrace period of a television broadcast signal, and assigns a program desired for teletext to a program number. In a teletext receiving device designated and displayable, a tuner for receiving a television broadcast signal of a predetermined channel, and means for extracting a teletext signal included in the received television broadcast signal,
A program registration means including a program registration memory, designating a desired program by the program number, storing designated program number data in the program registration memory and registering the program number data, and a plurality of storage areas; A page memory for storing text broadcast data of a program registered in the program registration means in the storage area in units of pages, and a channel for detecting that a channel of the television broadcast signal has been switched; Switching detection means, when a channel is switched during the writing operation of the text broadcast data of the registered program to the page memory, in response to a detection output from the channel switching detection means, Memory initialization means for storing teletext data as it is, and erasing teletext data of a page being written. It was a character broadcast receiver. (Operation) According to the present invention, the teletext program transmitted by the program number stored in the memory means is written from the buffer memory to the page memory, and is switched to another television broadcast channel during the writing operation. Even if the page data has already been written, the page data that has already been written is stored as it is, and the page data that is being written is erased. , Information can be displayed with good separation. Hereinafter, the present invention will be described with reference to the illustrated embodiments. FIG. 1 is a block diagram showing one embodiment of a teletext receiving apparatus according to the present invention. In FIG. 1, 11 is a television antenna, 12 is a tuner, 13 is a video detection circuit, a high-frequency signal induced in the antenna 11 is received by the tuner 12 as an intermediate frequency signal of a desired channel, and the output of the tuner 12 is The image enters the image detection circuit 13 and is detected. The tuner 12 is controlled by a tuning voltage from the tuning control circuit 14 so as to receive a signal of a desired channel. On the other hand, reference numeral 15 denotes a data fetch circuit for extracting teletext data, temporarily correcting the error after correcting the error, and having a buffer memory for temporarily storing the extracted teletext data. The output end of the data acquisition circuit 15 is a data bus
Connected to 19. The CPU 16, the RAM 17, and the ROM 18 are central processing circuits that execute a search (reception process), a presentation process, and the like of data stored in the buffer memory. Reference numeral 20 denotes a display control circuit controlled by the CPU 16. The display control circuit 20 transfers the program data of the desired program number detected by the search process from the data acquisition circuit 15, presents the transferred data to the display memory 21 and writes the written data in a predetermined memory. Displayed during the period. Reference numeral 22 denotes a keyboard such as a remote controller, which supplies key input data for receiving a desired channel to the channel selection control circuit 14 by operating a predetermined key or supplies a program number of a text broadcast number to be received to the CPU 16 . 23 is a page memory composed of a large number of display memories. The page memory 23 is controlled to store data for each teletext program, and each program data is written to a predetermined program memory area. The program can be registered for each channel separately. The RAM 17 is provided with a program number and a registration area for receiving channel data broadcasting the program corresponding to each program memory area. . These reception channel data and program number data can be input by key operation from the keyboard 22. Reference numeral 24 denotes a circuit for performing initialization for erasing data stored in the page memory 23. The memory initialization circuit 24 initializes the entire page area when the reception channel is switched while writing the page data of a certain program. This embodiment is configured as follows. 2A and 2B are explanatory diagrams for explaining the write operation of the page memory 23. FIG. 2A shows the reception order of the program data, FIG. 2B shows the map of the program memory "1", and FIG. Shows a map of the program memory "2", FIG. 4D shows a map of the program memory "3", and FIG. 5E shows a map of the program memory "4". The page memory 23 has n (n is an arbitrary integer).
Although there is an area for storing a number of programs, only four memory areas are shown in accordance with FIG. As can be seen from these figures, the page memory 23 according to the present embodiment divides the entire area into n program memory areas, and allocates each of the divided area memories “1” and “2” for each program of the text broadcast data. ", Memory" 3 ", memory" 4 "... memory" n "
(Not shown). More specifically, each of the program memories “1”, “2”, “3”, and “4” of the page memory 23 has program numbers 0/010, 0/011, and 0/01.
The program transmitted in 2,0 / 015 is stored. Each program is a multi-page program, and 0/010 is a 4-page program, 0/01
1 has a 3-page configuration, 0/012 has a 4-page configuration, and 0/015 has a 5-page configuration. These programs are registered in advance in the form of program designation by key operation, and when a packet of program number data indicating the above number is held in the buffer memory,
The program data packets of 0/010 are stored in memory “1” and 0
/ 011 packet is distributed to memory “2”,
The latest predetermined page data is always stored. Here, whether or not the packet held in the data acquisition circuit 15 is registered program data is determined by storing data identification data such as a program data header (PRCI) and a page data header (PACI) together with a registered program number. Therefore, the CPU 16 determines based on these data. When there is no more free space in the program memory, the program returns to the beginning of the address and continues writing. As a result, old page data is rewritten with new data. The size of each program memory is determined in consideration of the number of pages of the program or the data format. However, it is necessary to set the maximum data length of one program, that is, a capacity capable of storing all pages. There is no. This is because, if a predetermined number of page data are secured, the remaining page data that has not been stored is stored while presenting these (see program number 0/015). Of course, a program having a single page configuration can be stored in each program memory. Next, the operation when the reception channel is switched during the registration of the program data as described above will be described. As shown in FIG. 3, each program 0/010,
While writing 0/011, 0/012, 0/015, the receiving channel is switched from the first channel to the fourth channel. Now, the switching time is set to the program number 0 /
Assuming that the channel is switched during the reception of page 03 data in the program data of 010, first, the channel selection control circuit 14 outputs information indicating that the channel has been switched, and transmits it to the CPU 16. The CPU 16 decodes this information and sends an instruction to interrupt the write operation to the page memory 23, and in each page area of each program memory, the data to be written is less than one page of data. If there is an area having the following, a command to initialize the page area is sent. In the example of FIG. 3, the channel is switched while receiving page 03 data of the program with the program number 0/010, so that the program memory "1"
Initialize the area for writing page 03 data.
As a result, the data written in the program memory “1” becomes the data for the 01 and 02 pages. Therefore, when the receiving channel is switched from the fourth channel to the first channel again and the presentation processing of the program number 0/010 of the first channel is performed, the program of the program number 0/010 is already stored in the program memory “1”. Page 01 and page 02 are displayed first, during which page 03 is received, page 03 data is written and displayed in the program memory "1", and displayed with information missing as in the prior art. Never. At the time of the channel switching, the program memory “2” is 0 /
Before writing page 03 of the program 011, there is no need for initialization. Similarly, in the case of the program memory “3”, 0 of 0/012
Before writing 1 page, 0 for program memory “4”
Before writing page 05 of / 015, there is no need to initialize each page. Due to the nature of the data transmission mode, the data is not always received as shown in FIG. 2A, and a plurality of programs may match the channel switching while receiving one page of data. In such a case, the CPU 16 initializes each of the plurality of page areas. In addition, each of the programs on the first channel 0/010, 0/011, 0/01
If the receiving channel is switched at the above timing to write a teletext program registered on the fourth channel, then the page area where the 0/010 program is written is initialized. After the conversion, the teletext program registered on the fourth channel can be written to another program memory or the same program memory area. Thus, the present invention prevents teletext data from being displayed with information missing. In the above-described embodiment, the memory area is allocated to each registered program in the page memory 23 so as to be suitable for calling a program having a multi-page structure. However, as shown in FIG. Alternatively, the present invention may be applied to a page memory that writes data in the order of reception. [Effects of the Invention] As described above, according to the present invention, a program registered in the page memory is not displayed with missing information.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of a teletext receiving apparatus according to the present invention, and FIG. 2 is for explaining a write operation of a page memory used in the embodiment of FIG. Memory map,
FIG. 3 is a memory map for explaining an example of the operation of the present invention, FIG. 4 is a memory map for explaining the operation of the page memory, and FIG. 5 is a memory map for explaining the conventional operation. 14 …… Tuning control voltage, 15 …… Data acquisition circuit, 16 …… CP
U, 17… RAM, 18… ROM, 23… Page memory, 24…
... Memory initialization circuit.

Claims (1)

(57) [Claims] A teletext receiving apparatus which receives a teletext signal multiplexed during a vertical blanking period of a television broadcast signal and allows a desired teletext program to be displayed by designating a program number. A tuner for receiving a signal, means for extracting a teletext signal included in the received television broadcast signal, and a program registration memory, wherein a desired program is designated by the program number, and the designated program data A program registration means for storing and registering in the program registration memory; and having a plurality of storage areas, among extracted teletext signals,
A page memory for storing text broadcast data of a program number registered in the program registration unit in the storage area in page units; a channel switching detection unit for detecting that a channel of the television broadcast signal has been switched; When a channel is switched during the operation of writing the text broadcast data of the registered program to the page memory, in response to a detection output from the channel switching detection unit,
A character broadcast receiving apparatus, comprising: memory initialization means for storing text broadcast data of a page for which writing has been completed as it is, and erasing text broadcast data of a page being written.