JPS61257089A - Still picture transmitting method for telephone line - Google Patents

Abstract

PURPOSE:To transmit a still picture in a short time using narrow band telephone line by converting a digital video signal recorded in a memory into an analogue video signal, and sending it through telephone line after FM- or AM-modulating it. CONSTITUTION:When a picture is sent from station A to station B, the picture from video devices 1A, 2a is converted into the digital video signal by an A/D converter 3 at the station A, and the memory area in a CPU 4A is recorded in an outside memory 5A. When the recording is completed, the recorded signal is called from the memory and converted into the analogue video signal by a D/A converter. This signal is FM-modulated by an AM-modulator 7A and transmitted through telephone line by a acoustic coupler or a modem 8A. At the station B, the signal FM-modulated is received by the acoustic coupler or a modem 8B and demodulated by an FM demodulator 10B, and converted into the digital video signal by an A/D converter 11B. This signal is then recorded on the memory in the CPU 4 or an outside memory 5B. The signal is called and inputted to a television set 12B or a printer 13B to be displayed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a still image transmission method using a telephone line, in which a still image is transmitted to the other party using a telephone line.

[Prior Art] Conventional image transmission methods of this type include a method using a video telephone system, a method using R5-232C communication, and a method using facsimile.

[Problems to be Solved by the Invention] However, in the case of the method using a video telephone system, transmission is impossible without using a high frequency line, and very expensive equipment is required, so it is difficult to reach ordinary households. There are limits to its spread. On the other hand, methods using Its-232C communication or facsimile communication have a problem in that the time required for transmission is very long. For example R8-232
With the method using C communication, it takes about 71 minutes at 300 baud and 120 minutes.
It takes about 18 minutes at 0 baud and about 2 minutes at 9600 baud. .

SUMMARY OF THE INVENTION An object of the present invention is to provide a still image transmission method using a telephone line that can transmit a still image in an extremely short time even on an existing narrowband (3Ktlz) telephone line.

[Means for Solving the Problems] To explain in detail the present invention for achieving the above object, the present invention configures a required screen output from a video device such as a television camera or a video tape recorder. The video signal is digitally stored in a memory, the digital video signal is retrieved from the memory and converted into an analog video signal, which is FM or AM modulated and transmitted to the other party via a telephone line, and is received by the other party. After demodulating the FM or AM modulated analog video signal, converting it into a digital video signal and storing it in a memory,
The present invention is characterized in that the digital video signal is retrieved from the memory and displayed on a visual display such as a cathode ray tube display or a printer.

[Effect] Like this! In the i-image transmission method, the video signals input from the video equipment that make up the screen are once digitally stored in memory, and then the digital video signals are retrieved from the memory and transmitted, so the input speed and transmission speed are Able to deal with differences.

In addition, during transmission, the digital video signal is converted to an analog video signal, then FM or AM modulated and output to the telephone line, so even if the telephone line is narrow band, the video signal that composes the screen can be transmitted in a very short time. transmission becomes possible.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings. In the figure, the left side is station A, and the right side is station 8. In the figure, 1Δ and IB are video equipment consisting of a television camera, 2Δ and 2B are video equipment 1Δ and an A/D converter that converts analog video signals from IB into digital video signals, and 4Δ and 4B are digital video signals. 5A, 5B are memories such as floppy disks that store transmitted or received digital video signals; 6A, 6B are memory 5 via CPUs 4A, 4B;
Called from A, 5B or CPU4A, 4B
A D/A converter that converts a digital video signal called from a memory such as RAM in the camera into an analog video signal, 7A and 7B are FM modulators that perform FM modulation on analog video signals, and 8A and 8B are FM modulators. transmits the analog video signal to the receiver side via the telephone line
Cobra or modem, IOA, 10B is an FM demodulator for demodulating the received FM modulated analog video signal, 11A
, 11B is a Δ/D converter that converts the demodulated analog video signal into a digital video signal; 12A, 12
B is received and stored in the memory 5A.

A visual display 13A, 13B consisting of a television receiver or a CRT displays the digital video signal stored in the memory in the CPU 4A, 4B or the CPU 4A, 4B when it is called up via the CPU 4A, 4B. E
IJ 5 A, 5 B Maka CPU 4Δ, 4
This is a visual display consisting of a printer that displays when the digital video signal stored in the memory in B is called out via the CPUs 4A and 4B. As for the telephone line, a conventional narrowband (3 to 111) line using copper wire can be used as is, and of course a wider band coaxial line or optical fiber line can also be used.

Next, a method of transmitting images using such a system will be described. An example will be explained in which an image is sent from station A to eight stations. At station A, video equipment 1A consists of a television camera or video equipment 2 consists of a video tape recorder.
An analog video signal constituting a required screen is input from A/Dl converter 3A and converted into a digital video signal. Screen capture is performed based on, for example, a vertical synchronization signal. Digital video signal is sent to CPU4A
The data is stored in the internal memory or in the external memory 5A. When the number of screens to be memorized is small, or when there is no need to save them, the memory is stored in the memory within the CPUJA, and when there is a large number of screens to be memorized, or when there is a need to save them, the memory is stored in the external memory 5. Let A memorize it. When the storage is complete, recall the stored digital video signal from that memory and
/A converter 6A converts it into an analog video signal.

This analog video signal is FM-modulated by an FM modulator 7A and transmitted to the other party's B station via an acoustic coupler or modem 8A via a telephone port 1i19.

At station B, an FM modulated analog video signal is received by an acoustic coupler or modem 8B, demodulated by an FM demodulator 10B, converted to a digital video signal by an A/D converter 11B, and sent to the memory in the CPU 4B or externally. is stored in the memory 5B.

When the storage is completed, the digital video signal is called up and inputted to the visual display 12B such as a television receiver or the like or the visual display 13B such as a printer for display.

Note that the modulation of the analog video signal may be AM modulation.

Therefore, in this case, the demodulation is AM demodulation.

Images can also be displayed in color.

A television receiver can also be used as the input video device. In this case, a specific screen is stored in the memory 5A, 5B or the memory in the CPU 4A, 4B. 12A, '12B.

It can also be displayed on 13A and 13B.

The external memories 5A and 5B can also be omitted when downsizing the device.

[Effects of the Invention] As explained above, the still image transmission method over a telephone line according to the present invention converts a digital video signal stored in a memory into an analog video signal, and then modulates the digital video signal into an FM or AM signal and transmits it over the telephone line. Therefore, a still image can be transmitted in a very short time, for example, about 30 seconds, even on a narrowband telephone line using conventional copper wire. Furthermore, since the video signal is stored in the memory, it can easily correspond to the transmission speed determined from the narrowband telephone line side. In particular, according to the present invention, existing telephone lines can be used as is, making it possible for the general public to use the system. Furthermore, if the transmitting means is made portable and compact, for example, images captured by a television camera in a nearby area can be immediately transmitted to a head office or the like as long as there is a telephone line. Furthermore, there is the advantage that images can be transmitted to foreign countries in a short time using existing telephone lines.

[Brief explanation of drawings]

The drawing is a block diagram of a system implementing the method of the invention. IA, 1B...Video unit consisting of a television camera, 2
Δ, 2B... 4z video equipment from a video tape recorder, 3A, 3B... Δ/D converter, 4A. 4B...CPtJ, 5A, 5B...Memory, 6A,
6F3...D/A converter, 7A, 7B...FM
Modulator, 8A, 8B...Acoustic coupler or modem, 9.
...Telephone line, IOA, 10B...FM demodulator, II
A, 11B...A/D converter, 12A, 12B...
...Visual and visual display device consisting of a television receiver, 13A
, 13B... Visual indicator consisting of a printer.

Claims (1)

[Claims] A video signal output from a video device such as a television camera or a video tape recorder and constituting a required screen is digitally stored in a memory, the digital video signal is retrieved from the memory and converted into an analog video signal, and this is converted into an analog video signal. The received FM or AM modulated analog video signal is FM or AM modulated and transmitted to the other party via a telephone line, and the other party demodulates the FM or AM modulated analog video signal, converts it into a digital video signal, stores it in a memory, 1. A still image transmission method using a telephone line, characterized in that a digital video signal is called from a telephone line and displayed on a visual display device such as a cathode ray tube display or a printer.