JPS60146593A - Still picture transmitter - Google Patents

Abstract

PURPOSE:To obtain a transmitter which trnsmits a flicker-free still picture obtained by frame reproduction by sending out a field/frame discrimination signal and performing field/frame switching automatically. CONSTITUTION:A serial data signal inputted from a reception input terminal 1 is separated by a control signal detector 2 into a control and an image data signal, and this control signal is used to generate a reception start pulse 101 and a reception end pulse 102 and also perform field/frame detection, thereby outputting a field/frame signal which is ''0'' for a field and ''1'' for a frame. Latching operation is performed with the reception start pulse of the field/frame signal and whether one or both of video memories is used is selected by a field addressor 7 according to the field or frame mode.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to still image transmission for transmitting television video signals through a narrowband transmission line (such as a telephone line), and particularly to a still image transmission apparatus for automatically transmitting fields and frames.

In recent years, still image transmission devices are being used for meetings with remote locations, monitoring of dams, and the like. When transmitting images of people, distant views, etc. for conferences or monitoring, field transmission is used to shorten the transmission time (compared to frame transmission) because high resolution is not required. However, when high resolution is desired, such as drawings and documents, frame transmission is used, which takes a long time to transmit but has a low resolution. In this way, with gold wire, people and drawings are often switched and transmitted, so
Manually switching fields/frames every time transmission is performed on the transmitting side and the receiving side has the disadvantage that the operation becomes complicated.

For this reason, the conventional system sends an identification signal indicating whether the transmitted image is a field or a frame at the start of transmission, and the receiving side automatically switches between fields and frames by receiving the identification information. That is, the still image transmission apparatus uses two sets of field memories, and during field transmission, only one of the field memories is used to sequentially transmit information in the order of scanning lines. Also, when transmitting a frame, two sets of field memories are used for frame transmission, but if the first field and then the second field are transmitted in the order of the scanning lines, the received image will be one field memory in the order of the scanning lines shown in Figure 1. .2...262,263°264,・
...The image will be rewritten as 525. That is, 1
Since the image is rewritten every other line, there may be flicker between it and the previous image (lines that have not been rewritten).
happens. Therefore, when transmitting a frame, the first
Scan line 1 of the field is transmitted, followed by scan line 264 of the second field. If the images of the first field and the second field are transmitted by changing the field for each scanning line in this manner, the images on the receiving side are rewritten in order from the top, and flicker disappears. However, if field transmission has been performed up until the last time, the previously received image is written in one field memory on the receiving side, but it is unknown what is written in the other field memory. Therefore, when switching from field transmission to frame transmission and setting the receiving side to frame playback when the receiving side detects the field/frame identification signal, two sets of field memories are played back in order, so the previously received image and the In one example, since an image that is not known whether it has been loaded or not is played back, the playback screen has a memory value of 1 for each scanning line, resulting in a double image and the disadvantage that flicker can be seen. there were. Also,
In order to eliminate the above drawback, there is a method that rewrites the same information into both memories on the receiving side during field transmission, but this always requires retrieving two sets of field memories, and the data is stored in the memory. The drawback was that it required the same amount of power in the field as it did in the frame.

The object of the present invention has been made in view of these drawbacks, and is aimed at the stationary II! In the I11 area transmission equipment, a field/frame identification signal is sent out, field/frame switching is performed automatically, and when transmitting a frame, 1
In addition to transmitting data by field switching for each horizontal line, in playback on the receiving side, field playback is performed at the start of reception, and frame playback is performed at the end of reception, thereby reproducing two fields of memory. The present invention provides a still image transmission device that eliminates flicker caused by reproduction.

Next, the present invention will be explained in detail with reference to the drawings showing embodiments. FIG. 2 shows one embodiment of the present invention, and is a block diagram of the receiving side. A serial data signal inputted from the reception input terminal 1 is separated into a control signal and an image data signal by the control signal detector 2, and from the control signal, a reception start pulse 101 and a reception end pulse 1 are generated.
02 and performs field/frame detection, and when the field is 101. It outputs a field/frame signal 103 which becomes 111 when it is a frame. In addition, the image data signal is sent to the direct-to-parallel converter 3, and one pixel 8b
It is converted into parallel signals and sent to the image memory 4.

The image memory 4 is composed of two sets of field memories. In other words, it is a memory with a capacity for a frame.

The image memory 4 is supplied with write addresses and read addresses from slow addressers (write address generators) 5, 6.7 and TV addressers (M overflow address generators) 8, 9, 10, respectively, and receives Inside, image data is written at the speed of the transmission line in accordance with the writing address, and at the same time, the mochi is rolled out at the TV rate (high-speed television scanning speed).

The slow addresser is composed of a slow horizontal addresser 5, a slow vertical addresser 6, and a slow field addresser 7. The slow horizontal addresser 5 counts up each pixel of received data and counts up the number of pixels for 18 minutes. The carry is counted and input to the slow vertical addresser 6. Is the slow vertical addresser 1? Count the number of yield lines. Also, the slow field address +j-7 is a counter that counts by the carry from the slow horizontal addresser -5 (even if the flip is 70), and this slow field addresser 7
Controls which memory in the image memory 4 the output is written to. That is, by inputting the output of the slow field/frame latch 11, which latches the field/frame signal detected by the control signal detector 2 with the reception start pulse, to the clear of the slow field addresser 7, the latch 11 is cleared in the field mode. The output is 10
Because of m, the slow field addresser 7 is cleared and the output becomes 101, and only one side of the image memory 4 is selected and written, but when it is a frame, the output of the latch 11 is Ill, so the slow field addresser 7 becomes 1.
Since each horizontal line is inverted, both memories are alternately selected and written to alternately.

Next KTV addresser is TV horizontal dresser 8, TV
Vertical addresser-9, TV field addresser-1O
TV horizontal address length-8 is a counter that operates at high speed (scanning speed of television) and counts the number of pixels in one horizontal line, and addressers-9 and 10 are the carry of addresser-8 and addresser-9, respectively. This is a counter that counts up with each carry. Here, the TV field addresser 10 is the image memory 4
Controls which of the two sets of memories is selected. When the field/frame is controlled by supplying the same signal to the clear terminal of the TV field addresser 10 as the clear terminal of the slow field addresser 6, the field transmission changes to frame transmission. At the same time, both memos in image memory 4) - km are played, so the image received in the previous field and the image received in the frame before that or an unknown image (when playing the field, the memory on the side that is not being played back must be accessed) Since data is erased in dynamic memory), it is played back and causes flicker. To avoid this,
The output of the slow field/frame launch 11 is
By inputting the output of TV field/frame latch 2, which is latched at the end of reception pulse detected by the control signal detector, to the clear terminal of TV field address ")--10, the playback side can wait until reception ends. Even while a frame signal is being received, by field playback, a different field image is not played back, and frame playback is performed when the frame reception is completed, eliminating flicker.Also, it is possible to eliminate flicker when the frame signal is received. In this case, by connecting the human power of the latch 12 to the clear terminal of the latch 12, field playback is performed at the start of reception, thereby making it possible to respond to changes from frame to field.Next, the image signal extracted from the image memory 4 is converted into an analog signal by the D/A converter 13 and outputted from the video signal output terminal 14 as a television video signal.

Note that Figure 2 is a block diagram of the receiving side, but on the transmitting side, the video output terminal in Figure 2 is the video input terminal, and the D/A converter is the A/A converter.
The D converter and TV door addresser give a write address, and the slow addresser gives a projecting address. The transmitting side is constructed by making the serial-parallel converter become a parallel-serial converter, the control signal detector becomes a control signal inserter, and the two field/frame latches 11 and 12 are preset at the time of frame. be able to.

As explained above, when transmitting a frame, data is transmitted by changing the field for each line, and the field/frame identification signal is also transmitted, and the playback side changes the fields at the start of reception and the frame playback at the end of reception. It has the effect of automatically detecting fields/7 frames and avoiding flicker by simultaneously reproducing the contents of two different field memories.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the order of scanning lines of a television video signal, and FIG. 2 is a block diagram of an embodiment of the present invention. In the figure, 1... Receive input terminal, 2... Control signal detector, 3... Serial-to-parallel converter,
4... Image memory, 5... Slow horizontal addresser-16... Slow vertical 7)' Lesser, 7... Slow field addresser-18
...TV horizontal addresser-19...T
V vertical addresser-110...T'V field addresser-111...Slow field/
Frame latch, 12...TV field frame latch, 13...D/A converter, 14.
...Video signal output terminal. Agent Patent Attorney Uchihara 1' Japan/

Claims (1)

[Claims] In a still image transmission device that transmits television video signals through a narrowband transmission path, switching is performed by transmitting an identification signal between field-by-field transmission and frame-by-frame transmission, and field switching is performed for each horizontal line during frame-by-frame transmission. What is claimed is: 1. A still image transmitting apparatus characterized in that data is transmitted by transmitting data, and on a receiving side, switching between reproduction for transmission in field units and reproduction for transmission in frame units is performed at the start of reception and at the end of reception, respectively.