JPS63196161A - Picture signal transmission equipment - Google Patents

Abstract

PURPOSE:To realize fast two-way transmission with a telephone line of one line, by providing two kinds of picture signal conversion means of slow mode and fast mode, and outputting a picture signal to the telephone line by switching the picture signal from a facsimile unit which converts and outputs the picture signal to an image and the picture signal from the above means alternatively. CONSTITUTION:The picture signal photographed by a video camera 1 is converted to a digital picture signal, and is outputted to a pattern synthesizer 33, then, it is outputted to the signal input terminal 10a of a full duplex modem 10. Also, the digital picture signal outputted from the document reader 3a of the facsimile unit 3 is outputted to the signal input terminal 10a of the full duplex modem 10. A change-over switch 34 is switched to side (a) when a velocity control signal of fast mode is inputted to the input terminal of the said control signal from a velocity control circuit 27, meanwhile, it is switched to side (b) when the velocity control signal of low speed is inputted. In such a way, it is possible to transmit a prescribed image desired to be transmitted by using the facsimile unit 3 after completing a call by using a telephone set 24 of slow mode.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image signal transmission device that transmits image signals via a telephone line.

[Prior Art] Conventionally, videophone devices have been developed that transmit image signals and audio signals via telephone lines to make calls. This videophone device has an analog transmission speed of 7200 bps.
An image signal is transmitted using an image transmission means of a certain amplitude modulation method, and the image of the image signal transmitted from the other party is CR.
It is displayed on a display device such as a T display.

[Problems to be Solved by the Invention] However, in the video telephone device described above, two telephone lines are required in order to transmit image signals in both directions at the same time. Furthermore, for example, if the image signal is compressed and transmitted at a low speed in order to be transmitted via a telephone line in the 3.4 KHz band, the interval between frames of the image signal becomes long, and the display device of the other party does not transmit the image signal. There is a problem in that fast movements in the image of the image signal cannot be smoothly displayed.

An object of the present invention is to solve the above-mentioned problems, to be able to transmit image signals in both directions at a higher speed than in the conventional example through a single telephone line, and further to provide a facsimile unit. An object of the present invention is to provide an image signal transmission device that can selectively switch and transmit image signals output from a facsimile unit.

[Means for Solving the Problems] The present invention provides image signal generation means for converting first image information into a first image signal, converting second image information into a second image signal, and a facsimile unit that converts an image signal into an image and outputs the image; a switching device that selectively switches and outputs the first image signal and the second image signal; and the image signal generating device that converts a predetermined carrier wave signal into an image. The first image signal outputted from the facsimile unit or the second image signal outputted from the facsimile unit is modulated and outputted to the telephone line, and the outputted and modulated image signal is delayed, and at the same time the telephone line is full-duplex modem means for demodulating a difference signal between the modulated image signal and the delayed image signal input through the full-duplex modem means; and a display means for displaying the image signal output from the full-duplex modem means. It is characterized by:

[Operation] By connecting the two image signal transmission devices configured as described above at both ends via a telephone line, the first image signal generation means converts the first image information into an image signal. ,
The facsimile unit converts the second image information into a second image signal. Further, the switching means may be the first switching means.
The image signal and the second image signal are selectively switched and output.

Furthermore, the full-duplex modem modulation means modulates a predetermined carrier wave signal with the first image signal output from the image signal generation means or the second image signal output from the facsimile unit, and outputs the modulated signal to the telephone line. At the same time, the outputted modulated image signal is delayed. In response to this, the full-duplex modulation/demodulation means of the other party's device demodulates the difference signal between the modulated image signal and the delayed image signal input via the telephone line at the same time as the above modulation operation. ,
The display means displays the image signal output from the full-duplex modem and modulation means, and the facsimile unit converts the image signal demodulated by the full-duplex modem and demodulate into an image and outputs the image.

Therefore, image signals can be transmitted bidirectionally at a higher speed than in the conventional example through a single telephone line, and the second image signal output from the facsimile unit can be selectively switched. transmission.

[Embodiment] Fig. 1 is a block diagram of a telemirror device which is an embodiment of the present invention. This telemirror device is a type of video telephone device that can view images, and this telemirror device is connected to a telemirror device of the same configuration via a telephone line 9, and transmits the image signal of the image at a transmission speed of 9600 bps in high-speed mode or 1200 bps.
In addition to being able to switch the transmission speed in the low-speed mode of
It is characterized by the ability to automatically detect a 40Hz audio signal. Furthermore, an image from the facsimile unit 3 can be sent instead of the above image.

In FIG. 1, an image signal photographed by a video camera l is temporarily stored in a transmission image memory 31, which is a buffer memory of a video signal processing unit 2, and then converted into a digital image signal and output to a pattern synthesizer 33. At the same time, a of the video camera/facsimile selector switch 32 is
side and the a side of the changeover switch 34 to the signal input terminal 10a of the full-duplex modem lO. Further, the digital image signal outputted from the document reader 3a of the facsimile unit 3 is similarly outputted to the signal input terminal 10a of the full-duplex modem 1O via the b side of the changeover switch 32 and the a side of the changeover switch 34. . The selector switch 34 is switched to the a side when a high speed mode speed control signal is input to the control signal input terminal from the speed control circuit 27, and is switched to the b side when a low speed mode speed control signal is input. Switch to .

When the operator positions the light pen 5 at a predetermined position on the screen of the CRT display 4 and presses a switch (not shown) on the light pen 5 to turn it on, the light pen 5 moves onto the screen of the CRT display 4. The position information on the CRT display 4 is detected by detecting the bright line beam emitted from the light pen 5, and the position information is transferred to the light pen 5 via the auxiliary position memory 34, which temporarily stores the position information of the light pen 5 moving at high speed. Output to image memory 35. In response to this, the light pen image memory 35 generates a low-speed digital image signal with a transmission rate of 1200 bps based on the input position information, outputs it to the pattern synthesizer 33, and also outputs it to the pattern synthesizer 33 via the b side of the changeover switch 34. and outputs it to the signal input terminal 10a of the full-duplex modem 10.

On the other hand, after a low-speed digital image signal with a transmission rate of 1200 bps outputted from the signal output terminal 10b of the full-duplex modem 10 is stored in the received image memory 36, which is a buffer memory of the video signal processing section 2, pattern synthesis is performed. It is output to the device 33.

The pattern synthesizer 33 receives the digital image signal input from the received image memory 36 and the light pen image memory 35.
After synthesizing the digital image signals inputted from The data is output to the hard copy device 3b of the facsimile unit 3 via the hard copy device 3b of the facsimile unit 3. The scanner 38 scans l based on the input digital image signal.
A digital image signal of 1 minute is output to the CRT display 4.

The full-duplex modem lO performs PSK modulation on a carrier wave signal with a carrier frequency of 1800 Hz using the digital image signal inputted to the signal input terminal 10a from the common side of the changeover switch 34, and outputs the PSK modulated wave to a modulation signal input/output terminal 10c, The signal is output to the telemirror device of the other party via a band pass filter (hereinafter referred to as BPF) 6, a hybrid circuit 7, and a telephone line 9. In addition, the modem IO is connected to the telephone line 9, the hybrid circuit 7, and the BEF6 from the telemirror device of the other party.
and PS input via the modulation signal input/output terminal 10c.
The K modulated wave is demodulated and output to the received image memory 36 via the signal output terminal 10b. This full-duplex modem lO
The configuration will be described in detail later.

The audio signal output from the telephone 24 is processed through a band elimination filter (hereinafter referred to as BEF) 8 and a hybrid circuit 7.
and is output to the telemirror device of the other party via the telephone line 9. On the other hand, the audio signal output from the telemirror device of the other party is transmitted through the telephone line 9, the hybrid circuit 7, and the B
It is output to the telephone 24 via EF8. In addition, BEF
6 is a filter that extracts only the image signal input/output from the modulator/demodulator 10, while BEF 8 is a filter that removes the image signal and extracts only the audio signal input/output from the audio signal processing unit 5.

The speed control circuit 27 is a circuit that switches and controls the transmission speed mode of the image signal output from the telemirror device, and controls the detection signal input from the audio signal detection circuit 26 and the control signal input from the default control circuit 28. , and in response to the switching states of the manual/automatic changeover switch 29 and the high speed/low speed changeover switch 30, the transmission speed is set to 960.
A speed control signal for the 0 bps high speed mode or the 1200 bps low speed mode is output to the control signal input terminals of the pattern synthesizer 33 and changeover switch 34 of the video signal processing section 2, the full duplex modem lO, and the BPr;'6. .

Each circuit to which the speed control signal is input is controlled to operate in each mode according to the mode of the signal.

When the power of this telemirror device is turned on, the default control circuit 28 outputs a control signal to the speed control circuit 27, and in response, the speed control circuit 27 is automatically switched to the low speed mode of the manual mode. . When the changeover switch 29 is switched to the manual side, the operator can switch the changeover switch 30 to the high speed side or the low speed side.
The speed control circuit 27 can be set to a predetermined transmission speed mode.

On the other hand, when the changeover switch 29 is switched to the automatic side, the speed control circuit 27 is set to high speed mode or low speed mode by the detection signal inputted from the audio signal detection circuit 26. That is, the BPF 25 extracts the 340 Hz audio signal component on the telephone line 9 and outputs it to the audio signal detection circuit 26. The audio signal output circuit 26 determines whether the input signal component is equal to or higher than a predetermined threshold voltage, and outputs a detection signal to the speed control circuit 27 when the input signal component is equal to or higher than the predetermined threshold voltage. The speed control circuit 27 always outputs a speed control signal for the high speed mode, and outputs a speed control signal for the low speed mode when receiving the detection signal. Therefore, when the selector switch 29 is set to the automatic side and an audio signal is transmitted to the telephone circuit 9, the audio signal can be detected and the telephone set 24 can be used. , enters low-speed mode that transmits low-speed image signals.

Furthermore, the speed control circuit 27 controls a light emitting diode (hereinafter referred to as an LED) 41 for displaying automatic mode, an LED 42 for displaying high speed mode, and an ED 43 for displaying low speed mode, depending on the above-mentioned setting state of the circuit. Light.

FIG. 2 is a block diagram of the full-duplex modem lO shown in FIG. 1.

This is a diagram. The digital image signal input to the signal input terminal 10a of the modem 1O is input to the synchronous input section 19 of the full-duplex modem 1O, and at the synchronous input section 19, the input digital image signal is input from the modem side. The signal is input to the full-duplex modem lO in accordance with the synchronization signal. After the synchronized digital image signal is scrambled using a predetermined generating polynomial in the scrambler 20, the PSK modulator 21 converts it to a carrier frequency of 18001 (2
PSK modulates the carrier wave with a digital image signal. P.S.
The K-modulated digital image signal has the above-mentioned carrier frequency 1.
A predetermined band centered around 800Hz (approximately 1200Hz in high-speed mode, approximately 150Hz in low-speed mode)
After unnecessary band components are removed in the digital filter 22 that extracts only
The signal is output to a D/A converter (hereinafter referred to as D/A converter) 23 and a pseudo echo generator 15. The pseudo-echo generator 15 sets the impulse response characteristic of the transfer function as the tap coefficient of the generator 15 so that it has a characteristic equivalent to the transfer function of the path through which the echo passes, and performs convolution integration with the input signal. , and output to the differential amplifier 614 as a pseudo echo signal. Thereby, the tap coefficients are controlled so that the echo at the output of the differential amplifier 14 is minimized. On the other hand, the D/A converter 23 performs D/A conversion on the input digital image signal and outputs the digital signal via the hybrid circuit 11 to the modulation signal input/output terminal 10c.

The hybrid circuit 11 is an image signal synthesis/separation circuit that outputs the image signal input from the modulation signal input terminal 10c only to the analog filter 12, and also outputs the image signal input from the modulation signal input terminal 10c to the analog filter 12.
The image signal input from the converter 23 is output only to the BPF 6. However, in reality, reflected waves are generated that go around from the D/A converter 23 to the analog filter 12 via the hybrid circuit 11 and are reflected back at the 2-wire to 4-wire conversion point in the middle of the line, so these are eliminated. For this purpose, a pseudo echo generator 15 is used. The image signal input to the analog filter 12 undergoes analog-to-digital conversion (hereinafter referred to as A) after unnecessary band components such as noise are removed.
/D conversion. ) is A/D converted in the unit 13 and becomes 1
The signal is a 200 bps digital image signal and is input to the first input terminal of the differential amplifier 14. On the other hand, the pseudo echo signal output from the pseudo echo generator 15 is input to the second input terminal of the differential amplifier 14. The differential amplifier 14 takes the difference between the two input signals, and outputs an image signal included in the image signal input to the first input terminal from the D/A converter 23 to the analog filter 12 via the hybrid circuit 11. Components and 2 wires in the middle of the line-4
The reflected wave at the line conversion point is canceled by the pseudo echo signal, and the difference voltage is amplified and then output to the PSK@modulator 16. The digital image signal input to the PSK demodulator 16 is subjected to PSK demodulation at a carrier frequency of 1800 Hz, and then input to the descrambler 18 via the line automatic equalizer 17 that compensates for the band characteristics in the telephone line 9, and is converted into a descrambler 18 using a predetermined generating polynomial. A descrambling operation based on

The digital image signal output from the descrambler 18 is output to the signal output terminal 10b.

As shown in FIG. 2, the speed control signal input from the speed control circuit 27 is transmitted to the analog filter 12 of the modulator/demodulator IO.
, pseudo echo generator 15, PSK demodulator 16, line automatic equalizer 17, descrambler 18, synchronization input section 19, scrambler 20, PSK modulator 2L, and digital filter 22, and each circuit is controlled by the control signal. is high speed mode with transmission speed of 9600 bps or 1200 bps
is controlled to low speed mode.

The operation and operation method when two telemirror devices configured as described above are connected via the telephone line 9 will be explained.

As mentioned above, when the telemirror device is powered on, the default control circuit 28 sends a control signal to the speed control circuit 2.
7, and in response, the speed control circuit 27 is set to the low speed mode of the manual mode.

Further, when the changeover switch 29 is switched to the manual side, the changeover switch 30 can be used to switch the telemirror device to a high speed mode or a low speed mode.

Furthermore, when the selector switch 29 is switched to the automatic side, the high speed mode is always set.

At this time, when making a call using the telephone set 24, the voice signal detection circuit 26 detects the voice signal on the telephone line 9 and outputs a detection signal to the speed control circuit 27. In response, the speed control circuit 27 mode is switched to low speed mode, and a speed control signal for the low speed mode is output to each of the above-mentioned circuits.

The operation when set to low speed mode or high speed mode is as follows.

(1) Low-speed mode In this mode, the selector switch 34 is switched to the b side, and the full-duplex modem 10. The pattern synthesizer 33 and BPF 6 are set to low speed mode, and the telephone 24 and the light pen 5 for drawing on the CRT display 4 are enabled.

The audio signal output from the telephone 24 is transmitted to the other party's device via the BBr8, the hybrid circuit 7, and the telephone line 9, and is transmitted to the telephone 24 via the hybrid circuit 7 of the other party's device and the BBr2. Output. Also, CR
The image signal of the drawn image drawn using the light pen 5 on the T-display 4 is transferred from the light pen image memory 35 of the video signal processing unit 2 as a low-speed digital image signal of 1200 bps to the b side of the selector switch 34, full-duplex type. The video signal is transmitted to the other party's device via the modem 10, BPF6, hybrid circuit 7, and telephone line 9, and is further transmitted to the video signal processing unit via the hybrid circuit 7, BPF6, and full-duplex modem 10 of the other party's device. 2 is output. The image signal of the drawn image is output to the CRT display 4 via the a side of the changeover switch 37 and the scanner 38, and the drawn image is displayed. Here, CRT display 4
By correcting the drawn image displayed above using the light pen 5, the corrected drawn image can be transmitted to the other party's device and displayed on the CRT display 4 in the same manner as described above.

In the above embodiment, the low-speed mode image signal generated in the video processing unit 2, modulated by the modem IO, and outputted is in the frequency band of the telephone line 9 (θ to 3.4 KHz).
, occupies a band of 1800Hz ± 150Hz,
On the other hand, although the audio signal output from the telephone set 24 includes components in the entire frequency band of the telephone line 9, the components of the audio signal in the band occupied by the image signal are removed by the BBr2. The audio signal and the low-speed mode image signal are frequency division multiplexed, and one telephone R
9, audio signals and image signals can be transmitted simultaneously. Here, some components of the audio signal corresponding to the lag area of the image signal in the low speed mode are removed,
Since the rejection band is extremely narrow, the intelligibility of the audio signal does not deteriorate in practice.

Furthermore, since the carrier frequency of the PSK image signal is 1800 Hz, the center frequency of the second harmonic of the PSK image signal is 3600 Hz, and the second harmonic of the PSK image signal exists outside the band of the telephone line 9. The second harmonic of the PSK image signal does not affect the audio signal.

(2) High-speed mode In this mode, the switching scanner 34 is switched to the a side, and the full-duplex modem 10. The pattern synthesizer 33 and the BPF 6 are set to high speed mode, the video camera 1 and the facsimile unit 3 are enabled, and the image signal of the video camera 1 or the facsimile unit 3 occupies the entire band of the telephone line 9. At this time, the BPF 6 becomes a pass element without band limitation. Therefore, the telephone 24 becomes unusable. At this time, when using the video camera l, switch the selector switches 32 and 37 to side a, and
When using the facsimile unit 3, the changeover switches 32 and 37 are switched to the b side.

Now, when switching the changeover switches 32 and 37 to the a side, the image signal of the image taken by the video camera l is transferred to the image memory 31, the a side of the changeover switch 32, the a side of the changeover switch 34, and the full-duplex modem. 10, is transmitted to the other party's device via the hybrid circuit 7 and telephone line 9, and is sent to the CRT display 4 via the hybrid circuit 7, full-duplex modem 10°, and video signal processing section 2 of the other party's device. Output and display.

Also, when switching the changeover switches 32 and 37 to the b side, the document reader 3a of the facsimile unit 3
The image signal outputted from the facsimile unit 3 is outputted to the hard copy device 3b of the facsimile unit 3 of the other party in the same manner as described above. Therefore, for example, after making a call using the telephone set 24 in the low-speed mode, it is possible to transmit a desired image using the facsimile unit 3.

[Effects of the Invention] As described in detail above, according to the present invention, an image signal transmission apparatus includes a facsimile unit, a switching means for selectively switching and outputting a first image signal and a second image signal. , modulating a predetermined carrier wave signal with a first image signal or a second image signal and outputting the modulated image signal to a telephone line, delaying the outputted modulated image signal, and simultaneously modulating the modulated image signal input via the telephone line. The system is equipped with a full-duplex modulation/demodulation means that demodulates the difference signal between the delayed image signal and the delayed image signal, so the image signal can be transmitted in both directions at higher speed than in the conventional example. There is an advantage that the second image signal outputted from the facsimile unit can be selectively switched and transmitted.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a telemirror device that is an embodiment of the present invention, and FIG. 2 is a block diagram of the full-duplex modem of FIG. 1. ■...Video camera, 2...Video signal processing unit, 3...Facsimile unit, 4...CRT display, 5...Light pen, 6...Band pass filter (BPF), 7...・Hybrid circuit, 8...Band rejection filter (BEF), 9...Telephone line, 10...Full duplex modem, 24...Telephone, 25...Band pass filter (BPF), 26... Audio signal detection circuit, 27... Speed control circuit, 29.30... Changeover switch.

Claims (1)

[Claims] (1) an image signal generating means that converts first image information into a first image signal; and converts second image information into a second image signal;
a facsimile unit that converts an image signal into an image and outputs the image; a switching device that selectively switches and outputs the first image signal and the second image signal; and the image signal generating device that converts a predetermined carrier wave signal into an image. modulating the first image signal output from the facsimile unit or the second image signal output from the facsimile unit and outputting the modulated image signal to the telephone line, and delaying the output modulated image signal; a full-duplex modulation/demodulation means for demodulating a difference signal between a modulated image signal and a delayed image signal inputted through the full-duplex modulation/demodulation means; and a display means for displaying an image signal output from the full-duplex modulation/demodulation means. An image signal transmission device characterized by: