JPS608674B2 - Still image transmission system - Google Patents

Description

[Detailed Description of the Invention] This invention transmits a still image signal by multiplexing it onto a part of the vertical line period of a television signal, receives the signal, stores its contents, and displays it on a television screen. In a still image transmission system that converts the still image into a similar format and displays the still image on a television screen, the display changes depending on whether or not the still image has been updated.

NHK C, one of the television multiplex broadcasting systems
In the system, character signals of one horizontal scanning line IH are multiplexed for each field of the television signal, and this one
1 of the character to be displayed in the character signal of the horizontal scanning line IH
Information for the horizontal scanning period, a binary 4-bit program code signal indicating which of the nine programs this information corresponds to, and the number of the horizontal scanning line on one screen displayed for that program. A binary 8-bit line code signal indicating whether the signal is a signal is added.

Then, this line code signal is a binary number [1] to [1]
98] is used for actual video display, and the binary number [240]
is used to erase the page to update the screen. And this system uses 30 horizontal scan lines (character side, line spacing 1
Since one line of characters is displayed using the character signal of the general public, there are 210 fields on one screen, so there are 1 field in 9 programs.
New information is transmitted in field 8907 in 31.5 seconds. That is, one screen consists of 14 characters per line and 7 lines, and nine types of programs can be transmitted sequentially. If we were to utilize 100% of this transmission capacity, we would have to prepare 7 lines of information for every 3 blocks of information, and it would be extremely difficult to prepare such multiple pieces of information. Depending on the content of the information. is often meaningless.

Among the information services currently being considered, for example, weather forecasts do not require such frequent updating of information content. Therefore, a method has been adopted in which one piece of information is composed of several pages and this information is sent out repeatedly. However, with this method, if the receiver selects one program, the same content is shown over and over again.
Even though it is easy to understand once you watch it, it is shown for an unnecessary amount of time, distracting from the actual viewing of the television program. This invention has been developed with the above-mentioned points in mind.
Adding some kind of code signal to one unit of information of each program,
The receiver side detects the code signal and identifies whether the same content is repeated or new information, and when the same content is displayed a preset number of times, multiple still images are not displayed until new information is received. This is how it was done.

That is, the binary number of the line code signal [240]
is used to erase the page for screen updating as described above, and at the same time is added to the beginning of the first page of one unit of information to indicate the beginning of new information, and the binary number of the code signal [ 250] is added to the beginning of the first page of the second and subsequent transmissions of that information, and the binary number [251] is added to the second and subsequent pages of one unit of information, generally consisting of N pages. shall be given at the beginning of each page. Therefore, when one unit of information consists of three pages, the line code signals at the beginning of each page are binary numbers [240], [251], [251], [25
0], [251], [250], [251],...
One embodiment will be described in detail with reference to the drawings. In Figure 1, 1 is a buffer memory that reads the video signal sent only for 1 horizontal scanning period per field day, regardless of program code or line code, and 2 is a buffer memory into which a transfer pulse T or 1 field pulse F is input. This is a transfer gate that transfers the contents of the buffer memory to the main memory 3, and the main memory 3 is configured to circulate once in 1 field of 4 secondary K bits.

4 is a line counter that counts horizontal scanning lines in synchronization with the circulation of the main memory 3; 5 is a line code detection circuit that detects the line code of the video signal; and 6 is a line code detection circuit that uses the counted value of the line counter 4 and the line code detection circuit 5. This is a comparison circuit that compares the detected line code, and when the two match, and the program code of the video signal and the selected program code match, and the number code match signal C is input, the transfer gate 2 is opened. A transfer pulse T is generated.

7 should detect the page erase signal in the line code.
8 is a 1-field pulse generation circuit that generates 1-field pulse F when detecting a page erase signal; 9 is a page erase signal detected by the page erase signal detection circuit 7; the same content is repeated; A code ' indicates a video switching circuit that switches between a normal television video signal TV and a multiplexed still image MC that is the output of the main memory 3.

Next, FIG. 2, which shows the video switching circuit 9 in more detail, will be described.

11 is a shift register that holds an 8-bit signal that is a line code from the input video signal, 11 is a negative logic output decoder that detects the binary numbers [240], [250], and [251] in the shift register, 12 is a decoder 13 is a flip-flop whose J input is the output of the NAND circuit 12, and its negative output from the inverter 13' is the K input; CK is the flip-flop 1.
3 clock pulses, and the flip-flop 13 generates a 1-field pulse F to the transfer gate 2.

14 is the [250
] For example, a counter that outputs a positive logic output (/・i) by detecting the output twice (you can set it to any value more than twice, but 2 to 3 times is common) is cleared by the [240] detection pulse of the decoder 11.

16 is a switch for the viewer to select either normal television video TV or multiple still image MC; 17 is an input of the inverted output of power unloader 14 by inverter 8 and the television video TV side output of switch 16; 19 is an OR circuit that receives the output of the counter 4 and the still image MC side output of the switch 16, and a differentiation circuit that differentiates the still image MC side output of the switch 16 and resets the counter 4. , 21 is a flip-flop whose inputs are the outputs of the AND circuit 17 and the OR circuit 19;
22 is an AND circuit whose inputs are the output of the flip-flop 21 and the output of the main memory 3; 23 is an AND circuit whose inputs are the output of the NAND circuit 21 and the video erasing pulse VE;
4 is a video circuit into which the outputs of the AND circuits 22 and 23 and the television video signal TV are input; Q is a video circuit 24;
video or image output.

Next, the operation of the above embodiment will be explained.

The still image signal sent for one field's worth of one horizontal scanning line is read into the buffer memory 1, and when the program code matches the selected program and the program code match signal C is input, and the line code detection circuit 5 When the detected line code matches the count value of the line counter 4, the comparator circuit 6 generates a transfer pulse T, opens the transfer gate 2, and transfers the contents of the buffer memory 1 to the main memory 3.

An 8-bit signal serving as the middle line code of the input image signal is held in a shift register 10 and decoded by a decoder 11. The decoder uses binary numbers [240], [250], [
251], and this output is input to the NAND circuit 12 to drive the flip-flop 13 and generate a 1-field pulse F for page erasing.

The one-field pulse F opens the one-field transfer gate 2, causing the no-signal state of the buffer memory 1 to be transferred to the main memory 3, and substantially erasing the contents of the main memory 3.

When you want to display a normal television image, when you change the switch 16 to the television image TV, the outputs of the AND circuit 17 and the OR circuit 19 become low and high, respectively, regardless of the counter 4 output, and the flip-flop 2
The output of 1 becomes low.

Therefore, in order to display the multiple still image signal MC and the multiple image signal from the main memory 3, the gate signal VE for erasing the television video TV is prevented from being applied to the video circuit 24 by the AND circuits 22 and 23, respectively. Therefore, the original television image TV appears on the television screen.
only is displayed. If you want to display multiple still images,
When the switch 16 is switched to the still image MC side, the differentiating circuit 20 detects that the switch 16 has been switched regardless of the state of the counter 14, clears the counter 14, and conversely sets the AND circuit 17. The output is high, the output of the OR circuit 19 is low, and the output of the flip-flop 21 is high.

As a result, the television image erasing pulse VE and the still image MC from the main memory 3 are input to the video circuit 24, and the television image of the portion where the multiplexed still image should be displayed is erased.
Instead, a still image MC from the main memory 3 is inserted and displayed on the screen. When this state continues for a while, the decoder 11 detects line codes [250] and [251] indicating that this program is a repetition of the same content.

[250] When the detection pulse is detected twice, the counter 14
The output of the AND circuit 17 and the OR circuit 19 become low and high, respectively, and the output of the flip-flop 21 becomes low, and the television image is displayed as described above. Of course, the counter 14 will have [250
] Input of the detection pulse is prohibited, and this state is maintained until the counter 14 is reset next time. When the content of this program is updated and a new screen starts, the page erase signal returns to [240] and the counter 14 is reset.

Since the switch 16 remains switched to the multiplexed image MC side, the output of the flip-flop 21 becomes /, and the multiplexed still image is displayed. As described above, according to the still image transmission system of the present invention, at least one
One unit of information is composed of still image signals of more than one sheet,
A first image signal indicating whether or not this one unit of information is the same as the previous one unit of information is included in the first image signal of this one unit of information.
A second code signal is added and transmitted, and by detecting the first and second code signals, the receiving side detects that the same still image signal has been repeatedly received a preset number of times. Then, the television program display mode is automatically switched, so viewing of the television program is not unnecessarily interrupted, and therefore still image broadcasts and television broadcasts can be viewed efficiently. can.

Moreover, since the above control is performed using the first and second code signals, there is an advantage that the circuit for the control can be realized at low cost by combining a simple decoder, counter, etc.

[Brief explanation of the drawing]

The drawings show one embodiment of the still image transmission system of the present invention, FIG. 1 is a block wiring diagram of the still image receiving device, and FIG. 2 is a more detailed book wiring diagram of FIG. 1. Figure 1 Figure 2

Claims (1)

[Claims] 1 When multiplexing and transmitting still image signals during the vertical retrace period of a television signal, one unit of information is composed of at least one still image signal, and this one unit of information is repeatedly transmitted. Later, in a still image transmission system in which new units of information with different contents of the still image signal are repeatedly transmitted, the transmitting side transmits the first still image signal of each unit of information. If the one unit of information is the same as the previous one unit of information, a first code signal is added, and if they are different, a second code signal is added and transmitted, and the receiving side transmits the second code signal. The number of times the first code signal is detected is counted between when the code signal is detected and when the second code signal is detected again, and when the number of times the first code signal is detected reaches the number set in advance on the receiving side, the signal stops. A still image transmission system characterized by switching from an image display mode to a television video display mode.