JPS624915B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a still image receiving device that can be used in a system in which still image signals for a plurality of programs are multiplexed and transmitted during a horizontal scanning period during a vertical retrace period of a television signal. It is an object of the present invention to provide a device that can receive and retransmit still image signals of different programs to a plurality of terminal receivers in a CATV system or a parent-child television system.

It has been considered that various types of still image information can be transmitted by using television signals and superimposing multiplexed signals during the vertical retrace period. The following transmission system is being considered. The present invention will be explained below using this system as an example.

In this system, a page of still images to be transmitted is transmitted over 200 horizontal television lines (or
208) consists of lines, and each line is
As shown in the figure, each picture element consists of 245 bits. Furthermore, when transmitting a character image, one page of character image consists of 8 lines, and each line is
It consists of 26 lines each. When transmitting a graphic image, all 208 lines are used; when transmitting a character image, the upper 18 lines of each line are used for the character pattern, and the lower 8 lines of each line are used as interline spaces.

The following description will be made assuming that such a character image is transmitted.

Then, on the transmitting side, such a character image is scanned in the horizontal direction sequentially from the upper line as shown by the dashed line in FIG. 1A, and an image signal V for each line as shown in FIG. Obtain a binary signal of
As shown in FIG.
One line is superimposed on the 20th H (odd field) and the 283rd H (even field), multiplexed, and transmitted.

At the same time, an 8-bit (4 cycle) start signal indicates the reference phase and reference amplitude of all signals.
STX, a 4-bit program code signal PC that indicates which program the image signal V belongs to, and an 8-bit program code signal PC that indicates which line from the top of the image the image signal V belongs to. line number signal
Code signals such as LN are also superimposed, multiplexed, and transmitted as information signals.

An 8-bit framing code signal (for example, a fixed signal of "11100101") FC indicating that this multiplexed signal is a still image signal may be inserted next to the start signal STX.

The image signals V are multiplexed sequentially from the line above the character image at a rate of one line per field as described above, and the image signals for one page of one program are continuously superimposed.

However, as shown above, one page of still images can be
In the field immediately before transmitting the image signal V of each row divided into rows, the image signal V is not superimposed, but instead a row code signal indicating which row it is and a color code signal indicating the display color of that row. The image signals V for one row are transmitted continuously from the next field. The row code signal is distinguished from the line number code signal LN by using "225" to "232", which are never used as the line number code signal LN, as code signals representing the 1st to 8th rows, respectively. The superimposition position is the position of the line number code signal LN. Further, the color code signal is superimposed on the first half of the superimposition position of the image signal V, and the color to be displayed for each character in the row is instructed by a code signal of 3 bits per character.

In addition, in order to transmit many types of images such as news and weather forecasts, it is necessary to provide many programs, and still image signals for multiple programs, for example, nine programs, are multiplexed per channel of the television signal. transmitted. In that case, for each program, one page of still image signals is continuously transmitted across 208 fields as described above, but 9
When transmitting a program, one continuous program is transmitted as a unit, as shown in Figure 1E.
Still image signals for nine programs of "B", .

Next, the basic configuration of an apparatus that receives such a still image multiplexed information signal and displays a still image will be explained using FIG.

Here, 1 is a television signal receiving circuit including a tuner/video detection circuit, etc., 2 is a waveform shaping circuit that shapes the output of this receiving circuit 1 into a binary signal, 3 is a synchronization separation circuit, and 4 is a synchronization This is a horizontal/vertical oscillation circuit synchronized with the signal.

5 is for extracting the multiplexed information signal superimposed on the 20th H (and 283rd H; hereinafter only the 20th H will be described and the 283rd H will be omitted) based on the horizontal and vertical signals. 20th H of this
This is a gate pulse generation circuit that generates a sampling gate pulse during the second period. Gate circuit 6 for signal extraction
In this case, each information signal STX, FC, PC, LN, V of the 20th H from the output of the waveform shaping circuit 2 is generated by the gate pulse from the gate pulse generating circuit 5.
etc., and supplies it to the buffer memory 7, etc.

At this time, the image signal V among the received still image signals is written and stored in the buffer memory 7.
This buffer memory 7 stores an image signal V for one line.
It is constructed using a 256-bit shift register, for example, and is driven by a clock signal from the reception clock generation circuit 8.

On the other hand, the program code signal extraction circuit 9 extracts the program code signal PC using the clock signal from the reception clock generation circuit 8 and holds it for one field period. Then, the program comparison circuit 10 compares the program designation signal from the program designation circuit 11 with the sampled program code signal PC, and when the two match, a match output is generated.

On the other hand, the line number signal sampling circuit 12 uses the clock signal from the reception clock generation circuit 9 to extract the line number code signal LN. Then, the line comparison circuit 13 compares the count output from the line counter 14 indicating the line being scanned and the extracted line number code signal LN, and when the two match, a match output is generated.

Then, the program comparison circuit 10 and the line comparison circuit 1
3 and 3, the transfer gate circuit 15 is opened and the image signal V for one line stored in the buffer memory 7 is written to the storage position of the line in the main memory 16 and stored. This main memory 16 is normally a storage circuit having a storage capacity for one page of still images, is constructed using a dynamic shift register or RAM, and is driven by a clock signal from a main clock generation circuit 17.

By repeating such receiving and storing operations, the received image signals V are stored in the main memory 1 one after another.
6 can be stored.

Thereafter, for example, during 200H from the 42nd H to the 241st H, a readout clock signal is supplied to the main memory 16 at a rate of 245 bits for 1 line every H to read out the stored image signal V, and the switching circuit By applying the received signal to the cathode ray tube 20 via 18 and a processing amplifier 19 in place of a normal television reception signal, a character image can be displayed as shown in FIG.

Further, the color code signal is extracted by a color code signal extracting circuit 21 using a clock signal from the reception clock generating circuit 8, and stored in a color code memory 22, which operates in synchronization with reading out the image signal from the main memory 16. A color signal is generated by controlling the color signal generation circuit 23, and in addition to the processing amplifier 19, each character of the character image on the cathode ray tube 20 is displayed in a predetermined color.

As explained above, still images are transmitted, received, and displayed in this system.

However, with only the above configuration, it is possible to receive only the still image signal of one program designated by the program designation circuit 11 at a time. If each of the parties wishes to receive different programs, it is inconvenient that it is not possible to respond to those requests.

Therefore, in this device, the main body x with the above-mentioned configuration is
In addition to the memory block 24 shown in FIG. Read from this and output terminal 30
The data is retransmitted via A to 30I.
If these additional memory blocks 25A to 25I are provided for nine programs, all image signals for the nine programs sent can be received and stored.
If you then select and retransmit it to the desired terminal receivers A to I, any still image of any program can be selectively received by any terminal receiver.

To explain the details with reference to FIG. 2, each of the additional memory blocks 25A to 25I has transfer gate circuits 26A to 26I, and each stores image signals for one page, similar to the memory block 24 of the main body. The main memories 27A-27I have a storage capacity of 1000 yen, and program designation circuits 28A-28I and program comparison circuits 29A-29I for designating programs to be received by the respective additional main blocks 25A-25I are provided. The output signal of the buffer memory 7 is applied to each of the transfer gates 26A to 26I, and the program code signal extraction circuit 9 is applied to each of the program comparison circuits 29A to 29I.
output signals are added to each main memory 27A to 27.
I is driven by a clock signal from the main clock generating circuit 17.

Each additional memory block 25A to 25I
The program of the still image signal received in the program may be preset by each of the program designation circuits 28A to 28I, and in that case, when the preset program code signal is added from the program code signal extraction circuit 9. Two circuits, program designation circuits 28A to 28I and program comparison circuits 29A to 29I, may be configured using decoders that produce outputs.

In addition, each additional memory block 25A~
In the 25I, the parts surrounded by broken lines in the diagram are assembled into one printed circuit board or one housing to form one block, and can be removably attached to the circuit of main body x using plugs, sockets, etc. It is convenient if you do this.

Furthermore, in the present invention, as shown in FIG. 4, the program designation in the memory block 24 is also used instead of the memory block 25A to preset, and the switching circuit 18 selects which of the nine memory blocks 24, 25B to 25I. The still image program to be displayed on the cathode ray tube 20 is switched by reading an image signal from that source. In that case, memory blocks 24, 25B~
The output of 25I is retransmitted from output terminals 30A to 30I. In this way, the number of memory blocks used can be reduced.

Furthermore, if there is no need to display a still image on the main body x, the portion for transmitting image signals to the cathode ray tube 20 may be omitted by simply providing the output terminals 30A to 30I from each memory block.

As detailed above, in the present invention, main memories each having a storage capacity capable of storing image signals for one still image program and still image programs to be stored in the main memory are specified and detected. A plurality of sets of memory blocks having means are built in, and an output terminal is provided for reading out the image signals stored in each of the memory blocks in synchronization with the scanning of the cathode ray tube and retransmitting them to the terminal receiver. This makes it easy to achieve this even if you want to receive different still image programs on multiple terminal receivers in a CATV system or parent-child TV system. Since circuits can be used in common, this greatly contributes to cost reduction.

In addition, since the memory block used is one that stores the entire still image screen, any still image can always be displayed in full on each terminal receiver, and furthermore, the main receiving device can store the entire still image screen. Even stored still images can be arbitrarily selected and displayed on the own display means, which has the effect of being extremely convenient for monitoring reception status and presetting received programs.

[Brief explanation of the drawing]

1A, B, C, D, and E are block diagrams and waveform diagrams for explaining transmission modes of still image signals; FIG. 2 is a block diagram of a still image receiving device in an embodiment of the present invention; FIG. 3 is a front view of the device, and FIG. 4 is a block diagram of a still image receiving device in another embodiment of the present invention. 1... Receiving circuit, 2... Waveform shaping circuit, 3...
Synchronous separation circuit, 4...Horizontal/vertical oscillation circuit, 5...
...Gate pulse generation circuit, 6...Gate circuit, 7
... Buffer memory, 8 ... Reception clock generation circuit, 9 ... Program code signal sampling circuit, 10 ... Program comparison circuit, 11 ... Program designation circuit, 12 ... Line number signal sampling circuit, 13 ... Line comparison circuit , 14... Line rower, 15... Transfer gate circuit, 16... Main memory, 17... Main clock generation circuit, 18... Switching circuit, 19...
Processing amplifier, 20...Cathode ray tube, 21...Color code signal extraction circuit, 22...Color code memory, 23...Color signal generation circuit, 24...Memory block, 25A-25I...Memory block, 26A-26I ...Transfer gate circuit, 27A
~27I...Main memory, 28A~28I...
Program designation circuit, 29A to 29I...Program comparison circuit, 30A to 30I...Output terminal, x...Receiving device main body, A, B,...I...Terminal receiver.

Claims (1)

[Scope of Claims] 1. A receiving circuit that receives a television signal in which a still image signal including an image signal obtained by scanning still images for a plurality of programs is multiplexed in a horizontal scanning period during a vertical retrace period; a gate circuit for extracting the multiplexed still image signal from the television signal; a memory each storing one page of still images of the image signal extracted by the gate circuit; and a memory for detecting a program of the still image signal. A plurality of sets of memory blocks each having a program detecting means for writing and storing only the image signal of a specified specific program in the memory, and distributing the received still image signal to the plurality of memories in parallel. and a plurality of output terminals for retransmitting to a terminal receiver image signals read out simultaneously from the plurality of memory blocks in synchronization with the scanning of the cathode ray tube, and transmitting the received television signal. The image signals multiplexed in the memory block are stored in the memories of the memory blocks that are different for each program, and are retransmitted from the output terminal, and the image signals read out from the plurality of sets of memory blocks are 1. A still image receiving device comprising display means for selecting and displaying a still image of an arbitrary program by switching. 2. The still image receiving device according to claim 1, wherein each of the memory blocks is built into a single printed circuit board or a housing, and is detachably attached to the receiving device main body. 3. The still image receiving device according to claim 1 or 2, wherein the program detection means in each memory block is presettable.