JPS602832B2 - Still image receiving device - Google Patents

Description

[Detailed description of the invention]

This invention uses a part of the vertical line period of a television signal to receive a transmitted still image signal, stores the content in a form that can be displayed on a television screen, reads it out and freezes it. In a still image receiving device that displays an image, when updating the displayed still image, the content is not erased all at the same time, but a portion of the content can be erased and updated sequentially. The NHKC system, which is one of the television multiplex broadcasting systems, multiplexes character signals during the 20th horizontal scan period of the vertical line period of the television signal, stores them in the memory of the receiver, and broadcasts them in a series. This is a system in which characters are presented as character patterns and displayed on the television screen, with 14 characters per line.
The screen consists of 7 lines. Also, one line is made up of three K horizontal scanning lines, including the line spacing, and nine types of programs are sequentially transmitted line by line. A program code and a line code are added to each character signal to indicate which program and at which position on the screen the signal should be displayed. One line consists of three scanning lines,
Since only one scanning line per field is multiplexed and sent, it takes 0.9 axes to transmit one row of signals. If the received signal is immediately displayed, one line will be displayed in 0.9 seconds, there will be a blank period of 4 seconds, and the next line will be displayed in 0.5 seconds. These are displayed in order from the top to the bottom of the screen according to the line code instructions. If we were to start displaying from the first line at the top of the screen, it would take 0.5 x 74 x 6 = 27.9 stages to complete all seven lines. If the reception continues, the signal for the first line of the new screen will be sent after 4 seconds. For example, as shown in Figure 1a, when seven lines are displayed on the entire screen, when the signal [H] of the first line of a new image is received,
Only [A] in the row is rewritten to [H], resulting in the result as shown in Figure b. However, on this screen, two lines of characters [H
] and [B] are completely unrelated sentences, so the arrangement as shown in Figure 1b is extremely unsightly and inconvenient. Therefore, in the NHK C system, when a new screen starts, a special code called page erase is inserted when sending the first signal on the first line, and after erasing one to seven lines, the new screen is constructed. I try to do that. To explain this in detail with reference to Figure 2, which shows a block diagram of a conventional still image receiving device, 1 is a buffer memory for reading video signals that have undergone appropriate processing, and is made up of 240 bits. Always input regardless of program code or line code. 2 is a transfer gate that transfers the contents of buffer memory 1 to main memory 3 when transfer pulse T is input, and main memory 3 is a 4th class bit that circulates once in one field. . 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 input video signal, and 6 is a line code detection circuit 5 that combines the count value of the line counter 4 with the line code detection circuit 5. When a program code match signal C is input to the comparison circuit that compares the line code detected by the input video signal and the selected program code matches the program code of the input video signal, the transfer gate 2
Outputs a transfer pulse T for opening. If the program code and line code do not match, the transfer gate 2 is not opened and the output Q of the main memory 3 is circulated to the input. Further, 7 is a page erase code detection circuit that detects a page erase code, and 8 is a 1 field pulse generation circuit that generates 1 field pulse F when the page erase code detection circuit 7 detects a page erase code. Pulse F also opens transfer gate 2 and causes the contents of buffer memory 1 to be transferred to main memory 3. The signal transmission method for one program is as follows. One screen consists of 21 fixed horizontal scanning lines, and the program code is contained between the first IZK horizontal scanning lines on the first line.
Both line cord and video signal

It is [0]. The line code and video signal are multiplexed for the first time in the 13th horizontal scanning line of the first row, and at this time the line code is [1], that is, [00000001]. The video of line code [1] is displayed on the 43rd horizontal scanning line on the reception screen. Therefore, the line counter 4 reset by the vertical synchronization signal
When counting the 3k horizontal scanning line, the contents of the buffer memory 1 are transferred to the hard memory 3 that is synchronized with it, and when the output of the main memory 3 is circulated to the input side, it is displayed on the screen. This signal is exactly the 43rd signal of the next field.
It will be displayed on the K-th scanning line. Line code [
2] is transferred to the fourth K horizontal scanning line of the line counter 4. The following data is transferred in this order at a rate of one field per field. When the line code [18] is received, other programs continue from the next field for 8 programs and 240 fields, and the line code [19] of this program is sent again to complete the program. The 61st horizontal scanning line and subsequent lines of the line counter 4 are transferred to the main memory 3 in a similar manner. As described above, signals for one screen are sent over 210 fields and are all stored in the main memory 34 bits. In reality, signals from eight other programs are sent during that time, so it takes 27.9 episodes to complete one screen. 240 fields after the seventh line of the first screen is received, the second screen begins to be sent. At this time, the first signal on the first line of the second screen, that is, the first scanning line of the first line with no line code.
This page erase signal is inserted. The page erase signal is promised to have the line code part as [11110000]. Immediately when the page erase signal detection circuit 7 detects the page erase signal, the 1 field pulse generation circuit 8 generates the 1 field pulse F, opens the transfer gate 2, and keeps the buffer memory 1 constant for 1 field regardless of the line counter 4. Transfer the contents to Ojimori 3. Since the received signal is only the program code and page erase code and there is no video signal, there is no data in buffer memory 1.

If only [0] is recorded and this is transferred to the main memory 3 throughout one field, the contents of the main memory 3 will essentially be erased. When displaying the second substantial image in this way, the screen starts from a completely blank state and is displayed sequentially from the first line, but this method It is displayed for only 4 seconds, making it very difficult to read its contents. With the above points in mind, when updating a displayed still image, this invention first erases only a part of the old image, and inserts a part of the new image into the blank space between it and the old image. The present invention will be described in detail with reference to FIG. 3 showing one embodiment of the present invention. In FIG. 3, there is no symbol 1, and 7 indicates the same thing as in FIG. 2, and 8' is different from the subordinate 1-field pulse generation circuit 8, and generates a 2-row erase pulse E. The pulse generation circuit 9 is a 6G ship counter that counts in synchronization with the line counter 4 when the horizontal periodic pulse P is input through the input gate 10. When the page erase code is detected by the page erase code detection circuit 7 when updating the screen, 2 is set in this field.
Width of 48 lines, from the 43rd scan line to the 90th scan line
A scanning line pulse is generated to essentially erase two lines of the contents of the main memory 3, and then when a line code [1] signal is sent in the 12th field, the line code detection circuit 5 detects that line. The code [1] is detected and compared with the count value of the line counter 4, and if it matches the 43rd scanning line of this field, the transfer gate 2 is opened and the signal is transferred from the buffer memory 1 to the main memory 3. At this time, if the input gate 10 of the counter 9 is similarly opened by the transfer pulse T and the horizontal periodic pulse P is input to the counter 9, the counter 9 will count in synchronization with the line counter 4, and the transfer gate 2 will be If we decide to open the transfer gate 2 by the pulse R again after the 4th scanning line is opened and then to transfer the contents of the buffer memory 1 to the 61st scanning line, there is no longer anything in the buffer memory 1. Since it is no longer remembered, the contents of Ojimori 3 have essentially been erased. In other words, at the same time as rewriting the signal of the first scanning line of the first row, the signal of the first line of the third row in the same field is erased. Since the counter 9 generates a pulse with a width of 1 horizontal scanning time in the 61st horizontal scanning period after starting counting, if the second scanning line in the first row is rewritten, the pulse in the third row will be rewritten. By erasing the signal on the second scanning line, new information is displayed sequentially from the top of the second screen, and in synchronization with that display, the remaining information on the first screen is sequentially erased. , the screen can be updated while always leaving two lines of space between the new image and the old image, and it takes 31.9 sands equally from the time one signal is displayed to the time it is erased to display the information. discussions can be facilitated. As described above, according to the still image receiving device of the present invention, when updating a displayed still image, only a part of the screen is erased, and a blank space is left between the new image and the old image.
By gradually updating old images with new images, the images can be easily read, and the present invention exhibits a very remarkable effect.

[Brief explanation of drawings]

Figure 1 a. Fig. b is an explanatory diagram of a conventional image updating method, Fig. 2 is a block wiring diagram of a secondary still box reception bag counterfeit, and Fig. 3 is a block wiring diagram of an embodiment of the still image receiving device of the present invention. . Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. Receive a still image signal multiplexed and transmitted during the vertical retrace period of a television signal, and display this still image signal on a television screen via a main memory driven in synchronization with a synchronization signal of the television signal. a transfer pulse for writing a still image signal received in response to the synchronization signal to the main memory one line at a time from the first line of one page; A circuit that creates
A circuit that creates a first erase pulse for erasing the first few lines of one page of still image signals already stored in the main memory when a page erase signal in the still image signal is detected. a circuit for creating a second erase pulse for sequentially erasing one line at a time from the next line after the first few lines in synchronization with the write operation of one line at a time to the main memory; and the transfer pulse. and a circuit for writing and erasing the main memory in response to the first and second erase pulses, and when updating a page of a still image signal of one program, there is a circuit for writing and erasing the main memory in response to the first and second erase pulses. A still image receiving device characterized in that a blank space corresponding to a line is provided to sequentially replace old images with new images.