JPS6138311Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an empty memory drive circuit for a teletext receiver.

There is a C56 specification proposed by NHK as a television teletext broadcasting system. This specification is for transmitting approximately 100 programs as character patterns.If the transmitted character pattern is displayed in a fixed manner over the entire screen, the transmission period for one page is 3.3 seconds, and the transmission period for 10 programs is , the specified program may not be displayed for even 3.3 seconds. Therefore, it has been proposed to store programs to be displayed in advance and to prepare a memory for a plurality of screens so that programs can be displayed immediately when desired.
With such a receiver, it is possible to make reservations for as much as the memory capacity, and the reserved programs can be displayed immediately. However, if the reservation does not reach the memory capacity, the remaining free memory is wasted.

Therefore, the present invention proposes a new and effective free memory drive circuit that sequentially stores programs that are being transmitted to free memory and that are fixedly displayed on the entire screen, thereby reducing the maximum waiting time for displaying programs that do not have reservations. be.

First, in this specification, a page control packet (PCP) that is transmitted prior to a program other than one-line horizontally scrolling display program consists of a 6-byte header section and a 31-byte information data section. There are 2
A byte clock line code, 1 byte framing code, 1 byte service identification code and interrupt code, and 2 byte data identification code are arranged, and the information data section contains a 2 byte program number code and , a 2-byte page number code, a 1-byte erase code and update code,
A 1-byte display control code, a 1-byte raster background color code, a 1-byte page header background color code, and 23 bytes of spare bytes are each allocated. The display modes in this specification include a full fixed display mode in which static characters are displayed on the entire surface of the CRT with a predetermined background color, a super fixed display mode in which static characters are superimposed on the entire surface of the CRT, and static characters related to the broadcast content. A subtitle display mode that superimposes the text across the bottom two lines, and 1.
There is a one-line horizontal scroll display mode in which a line of characters is moved from left to right and superimposed, and a vertical scroll display mode in which characters moving upward are displayed with the entire surface of the cathode ray tube set in a predetermined background color.
Among the programs in these display modes, programs in the subtitle display mode, programs in the one-line horizontal scroll display mode, and programs in the vertical scroll display mode are transmitted in an interrupt manner due to the information content and display. For programs that are transmitted interruptively in this way, it is meaningful to display the information being transmitted at that timing, and the content can be stored and stored by reservation, and later displayed all at once by a display command. does not have as much advantage as the left, especially when the free memory is only for one program.
It is undesirable to store a program that is transmitted in an interruptive manner with priority over a program in the basic transmission mode that is not transmitted in an interruptive manner. That is, there is no special meaning in storing a program to be transmitted in an interruptive manner in a free memory, except when the user actively reserves the program to be transmitted in an interruptive manner.

Therefore, in the embodiment shown in FIG. 2, it is possible to reserve all programs except for the one-line horizontal scroll display mode, but the free memory is reserved for the full fixed display mode of the basic transmission mode and the super fixed display mode. Programs are stored in the order in which they were transmitted.

In this embodiment, a program can be reserved in four pages of fresh memory, and a program number code signal reserved by a reservation operation is sent from a reservation signal generation circuit 1 to predetermined reserved program memories 2a and 2, respectively.
b, 2c, 2d, program number latch circuit 3
The program number of the broadcast program latched in and each memory output are compared in the reservation comparison circuits 4a, 4b, 4c, and 4d, and the data latch circuit 6 latches in the area of the refresh memory 5 selected by the matching output. The data is sequentially stored by reserved program number, and in response to a display command operation, the display program number code output is input from the display signal generation circuit 7 to the reservation comparison circuits 4a, 4b, 4c, and 4d via the changeover switch 8. For example, the data stored in the corresponding area of the refresh memory 5 is read out all at once to form a character pattern on the television screen.

This embodiment adopts the present invention to such a conventional configuration. That is, in this embodiment, the existence and position of an empty memory is detected by the empty memory detection circuit 9 inputting each output of the reserved program memories 2a, 2b, 2c, and 2d, and the reservation comparison circuits 4a, 4b ，
The unreserved program detection circuit 10, which inputs each output of 4c and 4d, detects that the program being transmitted is not reserved, and the interrupt code detection circuit 11, which inputs the interrupt code in the header section, detects that the program being transmitted is not reserved. The PCP detection circuit which detects that the program is an interrupt program and inputs the data identification control code in the header section detects that the transmitted data packet is a page control packet. Therefore, the program selection circuit 13 inputting the above-mentioned detection output outputs the latched program number code to the program memory selection circuit 14 when a page control packet of an unreserved basic transmission mode program is input.
The program memory selection circuit 14, which takes the empty memory detection output as a control input, selects unreserved memories 15a, 15b, 15c, 1 corresponding to the empty memory.
5d are sequentially selected and the program reservation codes are stored. Programs to be transmitted thereafter are accumulated and stored in a predetermined area of the frame memory 5 based on matching outputs from the non-reservation comparison circuits 16a, 16b, 16c, and 16d. If there are a plurality of free memory areas in the frame memory 5, the program memory selection circuit selects the free memory area storing the old program and stores the new program cyclically.

Note that, although the explanation has been given above using NHK's C56 system as an example, the present invention is not limited to this, and can also be applied to code-based teletext broadcasting.

As described above, according to the present invention, when displaying an unreserved program number code, if the program is in the basic transmission mode, the maximum waiting time can be shortened by a period corresponding to the number of free memories. Memory can be used effectively.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing the structure of a page control packet for a teletext signal adopted by the present invention, and FIG. 2 is a block diagram of an implementation circuit of the present invention. Explanation of main figure numbers, 9...Empty memory detection circuit,
10...Unreserved program detection circuit, 11...Interruption code detection circuit, 12...PCP detection circuit, 13...Program selection circuit, 15a, 15b, 15c, 15d...
...Unreserved number memory, 16a, 16b, 16c,
16d... Comparison circuit for non-reservation, 5... Frame memory.

Claims (1)

[Scope of utility model registration request] In a character signal receiver that compares a reserved program number code and a transmitted program number code, stores a plurality of reserved programs in a predetermined area of a frame memory, and displays a desired program according to a display command, an empty memory detection circuit that detects unreserved free memory, a non-reservation program detection circuit that detects the transmission of a non-reservation program, a detection circuit that detects a page control packet, and a detection circuit that detects the transmission of an interrupt code. and a program selection circuit which captures the program number code interpolated into the page control packet of the non-reservation program in the basic transmission mode by the outputs of both detection circuits, and a non-reservation program memory which stores the circuit output in correspondence with the free memory. A free memory drive circuit for a teletext receiver, characterized in that a non-reservation comparing circuit is provided for comparing a broadcast program number code and a non-reservation program memory output and storing the broadcast program in the free memory.