JPS628683A - Image transmission system - Google Patents

Abstract

PURPOSE:To transmit and receive a video signal without using a specified line by digitizing the video signal at a transmission side, sending it through a telephone line and obtaining the video signal while putting it into analog at a receiving side. CONSTITUTION:The video signal from a television camera 9 or a video tape recorder 10 is AD-converted at an AD converter 16 in a video signal transmitter 6, and is quantized by a quantizer 19, and is supplied to a a variable length encoder 20. All of variable length encoded data are temporarily stored at a recording medium 8 through a buffer memory 22. With dialing in a sending destination from a display operating part 7, a controller 26 controls a line controller 25 through a control signal conversion part 27 and calls a sending opposite. The controller 26 sends a recording speed signal corresponding to a transmittable highest transmission angle and other information required for its control to a modem 24 through a telephone line 2 and with recognizing an answer back from an opposite video signal recorder, they are sent to the telephone line 2 through a line controller 25.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an image transmission system that makes it possible to transmit and receive video signals using telephone lines, and in particular, to digitize video signals and increase the communication speed of the telephone line. Send the converted digital data signal to the telephone line, receive the data signal,
The present invention relates to an image transmission method that can reproduce the data signal as a video signal by converting the data signal into analog data at a normal speed.

[Conventional technology]

Generally, as a system for transmitting and receiving video signals, C
ATV (cable television) systems are well known. In this system, a coaxial cable is used to connect the video signal transmitter and video signal receiver, and the transmitter sends the video signal to the coaxial cable, and the receiver receives the video signal. be.

Furthermore, a videophone system has been experimentally provided as a system for transmitting and receiving video signals using public communication lines. For example, a television camera and a telephone are installed at two locations, and video and audio signals are sent and received through public communication lines.

[Problem that the invention seeks to solve]

However, with the above CATV system, if you live in an area where coaxial cables are installed, you can receive video signals at a relatively low cost, but if you try to receive new signals outside of the area, coaxial There was a need to run cables, and there were also legal and regulatory issues, as well as time and cost issues.

On the other hand, since videophone calls are public communication lines,
Although there are no problems with respect to legal regulations, it is necessary to prepare a special line, which poses the same problem as mentioned above.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide an image transmission system that allows video signals to be transmitted and received using ordinary telephone lines.

[Means to solve the problem]

The image transmission method of the present invention that solves the above problems includes a video signal transmitting device that can digitize a video signal and transmit the digital data signal at a speed corresponding to the communication speed of the telephone line, and a telephone line connected to the video signal transmitting device. connected with
It consists of a video signal recording device that receives the digital data signal, converts the data signal into an analog signal, and converts it into a video signal.

[Effect]

On the transmitting side, the video signal is digitized and recorded on a recording medium, the digital data signal recorded on the recording medium is reproduced according to the communication speed of the telephone line, and the low-speed data signal is sent to the telephone line.

The receiving side receives this sent out low-speed data signal and records it on a recording medium. The video signal is reproduced by converting the data on the recording medium into analog data at normal speed. Therefore, by applying this reproduced video signal to a normal video reproduction device, the video can be reproduced.

According to this, a special communication circuit is not required, and ordinary video signals can be transmitted and received.

〔Example〕

Hereinafter, the present invention will be explained according to illustrated embodiments.

FIG. 1 is a block diagram showing an embodiment of an image transmission system according to the present invention.

Reference numeral 1 in the figure represents a telephone office, and the telephone office 1 is connectable to subscriber telephones 4 and 5 via telephone lines 2 and 3, respectively. A video signal transmitting device 6 is connected to the terminal of the telephone diagram wA2, and the telephone 4 can be connected to the telephone line 2 via the video signal transmitting device 6. The video signal transmitting device 6 is provided with a display operation section 7 and a removable storage medium 8. A television camera 9 and a video tape recorder 10 are connected to the video signal transmitting device 6. The video signal recording device 11 is connected to the end of the telephone line 3, so that the telephone set 5 can be connected to the telephone line 3 via the video signal recording device 11. The video signal recording device 11 includes a display/operation unit 12 for displaying various operating states and inputting various operation commands, and a removable recording medium 13 for recording received data signals.
This is the provision.

Here, the recording media 8 and 13 may be, for example, magnetic tapes, magnetic or optical disks, magnetic drums, etc. Reference numeral 14 is a monitor television, and this monitor television 14 is connected to the video recording device 11. It is.

FIG. 2 is a block diagram showing an example of the configuration of a video signal transmitting device used in an embodiment of the present invention. In Figure 2, the first
Components that are the same as those shown in the figures will be described with the same reference numerals.

The video signal transmission bag W6 shown in FIG. 2 is constructed as follows. That is, either the television camera 9 or the video tape recorder 10 can be connected to an analog/digital (A/D) converter 16 via a switch 15. The input video signal is band-limited by a filter, and converted into a digital signal of a predetermined number of bits (for example, 8 bits) by an A/D converter 16. This digital signal is sent to the subtraction circuit 17 and the prediction circuit 18
The difference between the predicted value and the calculated value is taken. The data signal from which the difference is taken is quantized by a quantizer 19. This quantizer 19 is
The circuit configuration is such that the amount of information sent to the telephone line 2 is controlled to be constant depending on the amount of information of the input image. The data signal from the quantizer 19 is provided to a variable length encoder 20 as well as to an adder 21. The variable length encoder 20 assigns a short code depending on the amount of quantized data generated, and stores the data signal in the buffer memory 22.
It is a good idea to give it to someone. The buffer memory 22 is monitored by a data controller 23, and the variable length encoder 20, prediction circuit 18, and quantizer 19 are controlled according to the state of the memo IJ 22. The adder 21 adds the output from the prediction circuit 18 and the signal from the quantizer 19 and provides the result to the prediction circuit 18. The data in the buffer memory 22 is stored in the recording medium 8 in sequence. The modem 24 transmits data from the recording medium 8 via the buffer memory 22 to the telephone line 2 via the line controller 28.
Reference numeral 5 has a circuit configuration that can switch and control the telephone line 2 to either the telephone 4 side or the video signal transmitter 6 side in response to a control signal from the control device 26 or a signal from the telephone line 2. The control signal conversion circuit 27 includes the modem 24 and the controller 2.
26, and has a circuit configuration that can detect a call waiting signal and send out specific information. The control device 26 is connected to the display operation section 7, and also controls the switching device 15, the data controller 23, the buffer memory 22, the modem 24, the line controller 25, and the drive device 28 for driving the recording medium 8, respectively. It is possible to control it.

FIG. 3 is a block diagram showing an example of the configuration of a video signal recording device used in an embodiment of the present invention. In Figure 3, the first
The video signal recording device 11, which will be described with the same reference numerals given to the same components as those shown in the figures, is constructed as follows.

That is, the telephone line 3 is connected to a line controller 29. The line controller 29 can switch and control the telephone line 3 between the telephone 5 side and the video signal receiving device 11 side according to a control signal etc. from the control device 3o.
The line controller 29 is connected to a modulator/demodulator 31 , and the modulator/demodulator 31 is configured to demodulate data signals sent from the telephone line 3 and supply them to the buffer memory 32 .

A predetermined amount of data stored in the buffer memo 1J32 is sequentially recorded on the recording medium 13. Recording medium 1
The three pieces of data are provided to a signal controller 34 via a buffer memory 32. This signal controller 34 controls the buffer memory 1732, the variable length decoder 35, and the prediction circuit 36 according to the state of the buffer memory 32, and also sends the data signal from the controller 34 to the variable length decoder 35. It's like it's coming. The variable length decoder 35 is configured to demodulate variable length encoded data into an original digital signal. The prediction circuit 36 is connected to provide the data signal from the signal controller 34 and a prediction result predicted based on the output signal from the adder 37 to the adder 37. Adder 3
7 adds the signal from the prediction circuit 36 to the signal from the variable length decoder 35 to obtain a D/A convertible data signal, and supplies this to a digital/analog (D/A) converter 38. It is.

The D/A converter 38 has a circuit configuration that converts a digital data signal into an analog signal, and its analog output signal (video signal) is provided to the monitor television 14, for example. Note that 39 is a drive device for the recording medium 33, and 40 is a control signal conversion circuit.

The operation of the above embodiment will be explained.

The functions of this embodiment include (11) recording the video signal on the recording medium 8 of the video signal transmitting device 6, and (2) transmitting the video signal from the recording medium 8 of the video signal transmitting device 6 via the telephone line 2.3. The explanation will be divided into three parts: the action of transmitting to the recording medium 13 of the recording device 11, and (3) the action of reproducing the video signal from the video signal recording device 11.

The operation of recording the +11 video signal into the video signal transmitting device 6 will be explained with reference to FIGS. 2 and 4.

Either the television camera 9 or the video tape recorder 10 is connected to the A/D converter 16 by the switch 15, and a video signal is supplied to the A/D converter 16 (step 510).
0), the A/D converter 16 A/D converts the video signal to, for example, 8 bits, and supplies the A/D converted data signal to the subtracter 17.
Take the difference from the value predicted by the prediction circuit 17 at (
Step S101). The data signal from which the difference was taken in the subtracter 17 is quantized by the quantizer 19, and
It is supplied to the variable length encoder 2o and the adder 21 (step S102). The quantizer 19 operates so that the amount of information of the input image is constant. Variable length encoder 2
The data signal supplied to 0 is converted into a variable length code by the variable length encoder 20, which assigns a short code to a high value of the generated signal (step S103).In this way, variable length coding is performed. The data is stored in the buffer memory 22.
(Step S104). buffer memo 1
If the data given to J22 is not full (step S105), go to step 3100 and repeat the process from step 5100, but if it is full, go to step S81.
06 to record on the recording medium 8 (step S1
06) If all of the video signal has been recorded on the recording medium 8, the operation ends; if not, the process returns to the Ste knob 5100 and these steps are repeated (step S107).

In this way, all necessary video signals are once recorded on the recording medium 8. This is because the frequency band of a video signal is 4 MHz, while the frequency band of a telephone line is 4 kHz.

(2) From video signal transmitter 6 to video signal recorder 1
1, the data transmission function will be explained with reference to FIGS. 2, 3, 5, and 6.

First, check the setting status of the recording medium 8 on which the digitized video signal is recorded in the video signal transmission bag π6 (
Step S200). Next, the destination is dialed into the control device 26 from the display operation section 7 (step S2
01), the control bag device 26 first converts the control signal converter 27
The line controller 25 is controlled via the sender to call the destination party (step S202). It is determined whether the other party is connected or not (Step S 203), and if it is not connected, a message to that effect is displayed on the display/operation unit 7 (Step S 204), and the process returns to Step 5201 to enter a standby state.

If it is determined in step 5203 that the other party is connected, the control device 26 transmits the maximum communication speed 1.3 that can be transmitted over the telephone line 2.3. 4. Send the recorded recording speed signal and other information necessary for control to the modulator/demodulator 24 via the control signal conversion circuit 27 (step S205), and confirm the answer back from the video signal recording device 11 of the other party. do
(Step S206). If there is no answer back signal, the process moves to step 5105 a certain number of times (step S
207), if the number exceeds a certain number, step 320B
, displays the message that communication is not possible, and terminates communication. When there is an answerback signal in step 8206, the control device 26 activates the buffer memory 22, modem 24, line control section 25, and drive device 28 (step S209). The data on the recording medium 8 is set in the buffer memo IJ 22, provided to the modem 24, and transmitted to the telephone line 2 via the line controller 25 (step S209). When all the data recorded on the recording medium 8 is not sent out, the process returns to step 5209, but when all the data is sent out, the process moves to step 5211 (step S210). In step 5211, "r transmission completed"
is displayed on the display operation section 7 and the transmission is ended (step 3211). Here, when the call waiting signal is received, the control device 26 sends out a stop signal via the control signal conversion circuit 27, and issues a stop command to the drive device 2. When the control device 26 confirms that it has stopped,
The line controller 25 switches the telephone line 2 to the telephone A4 side. When the telephone call on the telephone 4 is completed, transmission of the video signal is started again. Before this start, it is assumed that the control device 26 has previously sent a signal to the effect of transmission and obtained an answer back.

On the other hand, it is assumed that the recording medium 33 is set on the video signal recording device 11 side. When there is a call from the telephone line 3, the line controller 29 is connected to the telephone line 3.
(Step S300) A signal from the telephone line 3 is given to the control device 30 via the modem 31 and the control signal conversion circuit 40, and the control device 30 determines whether or not this signal is a video signal.
(Step S301).

If it is determined in step 5301 that it is a telephone, the line controller 29
Connect line 3 and telephone 5 by (Step 2 S302). If it is determined in step 5301 that the signal is a video signal, the recording speed 1 signal and other control information are taken into the control device 30 via the line controller 29, modem 31, and signal conversion circuit 40 (step S303). When the information has been completely taken into the control device 30, a message indicating that the information has been reliably taken is sent to the telephone line 3 via the modem 31 and the line controller 29 (step 5304). At the same time, the control device 30 includes a buffer memory 32 and a drive device 39.
is activated (step S305). At this time, the driving device 139 is set to a recording speed corresponding to a constant communication speed given by the transmitting device 6 (a speed corresponding to the maximum communication speed that can be communicated on the telephone line 2.3). Then, in step 8306, the signal sent from the telephone line 3 is applied to the modem 31 via the line controller 29, where it is converted into a predetermined signal and applied to the buffer memory 32, where it is stored until a predetermined amount is reached. , are sequentially recorded on the recording medium 33. Signal conversion circuit 40 converts call waiting signals while receiving and recording video signals.
When the control device 30 detects the
7) Sends a stop signal from the control device 30 to the telephone line 3 via the modulator/demodulator 31 and the line controller 29, and issues a stop command to the drive device 39 (step 3308), and sends a stop completion signal to the transmitting device 6. When the telephone line 3 is received from the telephone set 5, the line controller 29' switches the telephone line 3 to the telephone set 5 (step S309). When the call is completed, input "Call Complete" from the display operation section 12 (Step S
310), the control device 30 gives a restart signal to the transmitter 6 and starts the drive device 39 (step S31+), and returns to step S316. Step 5
If there is no call waiting signal (317), the process moves to step 5312, and it is determined whether there is a transmission completion signal. In step 5312, if there is no transmission completion signal, the process moves to step -8306, but when the transmission completion signal is received, all operations are completed (step S313).

(3) The operation of reproducing a video signal from the video signal recording device II will be explained with reference to FIGS. 3 and 7.

First, a command to reproduce a video signal is given from the operation unit 12 to the control device 30 (step S400).

The control device 30 is supplied with control signals such as those generated by the drive device 39, the signal control unit 34, and the buffer memory 32 (step S401). Data is sequentially written from the recording medium 13 to the buffer memo IJ32 (step 5402). When the data in the buffer memory 32 is given to the signal controller 34, the controller 34 activates the buffer memory 32, variable length decoder 35, and prediction circuit 36 according to the amount of data in the buffer memory 32. control and provide data to the variable length decoder 35 (step 3403
). The data given to the variable length decoder 35 is decoded into normal length data and given to the adder 37 (
Step S404). When the prediction circuit 36 gives a predicted value based on the output of the adder 37 to the adder 37, the adder 3
7 adds the predicted value to the decoded data, converts it into a normal data signal, and supplies this to the D/A converter 38
(Step S405). The D/A converter 38 converts the data into an analog signal (video signal) and provides it to the monitor television 14 (step S406).
Step 5402 until D/A conversion of all data is completed.
Returning to step S407, the video signal thus converted into a digital signal on the recording medium 13 is converted into an analog video signal at a normal speed and reproduced. Of course, although the output (video signal) of the D/A converter 38 is given to the monitor television 14, it goes without saying that it may be given to a video tape recorder (not shown).

As described in sections (1) to (3) above, the video signal transmitting device 6 first digitizes the video signal at a normal speed and records the entire amount of the video signal on the recording medium 8. Next, the video signal transmitting device 6 and the video signal recording device 11 are connected via a telephone line, and the digitized data is transmitted from the transmitting device 6 to the recording device 1 at the communication speed of the telephone line.
1 to the recording medium 13, and all data is transmitted and recorded.

When reproducing a video signal, the data on the recording medium 13 of the recording device 11 is converted into analog data at a normal speed and provided to the monitor television 14.

According to the embodiments described above, video signals can be transmitted and received using telephone lines. Further, according to this embodiment, a specific line is not required.

〔Effect of the invention〕

As mentioned above, according to UII, the transmitting side digitizes the video signal, sends it to the receiving side via the telephone line, and the receiving side converts it into analog again to obtain the video signal. This has the effect of allowing video signals to be sent and received without using a specific line.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the entire system of an embodiment of the image transmission method according to the present invention, FIG. 2 is a block diagram showing an embodiment of the video signal transmitting device used in the present invention, and FIG. 3 is a block diagram showing an embodiment of the video signal transmitting device used in the present invention. A block diagram showing a configuration example of a video signal recording device,
FIG. 4 to FIG. 7 are flowcharts shown to explain the operation of the embodiment. 2.3-telephone line, 6--video signal transmitter, 11
----Video signal recording device, 8 and 13-recording medium.

Claims (1)

[Claims] A video signal transmitting device that can digitize a video signal and transmit the digital data signal at a speed corresponding to the communication speed of a telephone line; An image transmission system characterized by comprising a video signal recording device that converts signals into analog signals and converts them into video signals.