JPH07203401A - Video telephone system - Google Patents

Abstract

PURPOSE:To use a preceding video image with convenience by automatically storing a video image of a current talking opposite party to a memory before a line is switched when interrupt by a call-waiting takes service place so as to leave the preceding video image even when the talking is switched. CONSTITUTION:When an interrupt by a call-waiting takes place and the depression of a line changeover switch (a hook switch of a telephone set or a changeover switch of a remote commander) is detected, a CPU 11 stores at first a video image of a current opposite party to a memory 16c. Then the CPU 11 provides an output of a switching signal to a telephone network to switch an exchange of the telephone network, displays a video image of a new opposite party to a liquid crystal display section 8 and the preceding video image stored in the memory 16c is displayed onto a PinP(picture-in-picture display part).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a videophone device, and more particularly to a videophone device capable of switching a call to a third party when there is a call interruption from a third party during a call. .

[0002]

2. Description of the Related Art With the recent development of a highly information-oriented society, there is an increasing demand for communication media that transmit large amounts of various information at high speed.

In order to meet such demand, in 1988, TTC (Telecommunication Technology Committee:
JJ as a standard communication method of (Telephone and Telephone Technical Committee)
-40.10 "Analog Telephone Band Still Image Video Communication System"
Since then, it has become possible to exchange black and white image data with each other via a communication line.After that, the standard communication system of TTC was revised in 1989, and not only black and white image data but also It is also possible to send and receive color image data, and various videophone devices conforming to these TTC standard communication systems have been developed.

Depending on the type of communication network to be connected and the type of image and voice transmission function, the video telephone device is connected to, for example, an analog public line to transmit a monochrome still image or a color still image, or a color moving image. There are things that transmit images, etc., and the merit that it is possible to show and transmit information that is difficult to convey to the other party only by explanation with voice,
It is expected to be popular because it has the advantage of being able to make a call while looking at the expression of the other party.

Conventionally, a still picture video-phone device connected to an analog public line to transmit a black and white still image has adopted a method of transmitting image data as it is without compressing it, for example, one screen is 100 × 160. 100 x 1 when handling black and white image data with 64 gradations (6 bits) in pixels
60 x 6 = 96000 bits (about 11.7 kilobytes)
Data was transmitted at a transmission rate of about 8740 bps (Bit Per Second: bits / second), it took about 11 seconds to transmit one screen of image data, but the image data Since the amount is large, it is not practical to process it as it is because of the memory capacity and communication speed.

Since the compressed transmission of image data transmits an extremely large amount of data, even if some transmission delay occurs, the influence on the progress of the call is not so large. Therefore, variable length coding (for example, CCITT Recommendation H) is performed. In general, the average generated bit length can be compressed by digitizing the voice data in the compressed transmission of the voice data. Applying entropy compression (eg, Huffman coding) that does not guarantee the bit length to a voice signal causes a large transmission delay in the voice signal if the voice signal is generated to have a long bit length due to the entropy compression. , Because it greatly affects the progress of the call,
It is encoded and transmitted with a fixed bit length.

A video telephone device connected to such an analog communication network has a communication function of multiplexing and transmitting image information and voice information, and communication corresponding to the connected communication network. Regarding the procedure and the encoding method of the image information and the voice information which are transmitted / received in addition to the communication signal based on the communication procedure, according to CCITT (International Telegraph and Telephone Consultative Committee) recommendation etc., It is prescribed.

As a service form of such a videophone device, it is possible to apply a service currently used for a normal telephone device (only voice). If there is a call request from a third party during a call to one of this service,
There is a so-called "call waiting service" in which a speaker who is talking is notified to that effect and when this speaker gives a switching instruction, the speaker switches to a third party.

[0009]

However, in the conventional videophone device that simultaneously displays the transmission screen and the reception screen, when the reception screen and the transmission screen are viewed at the same time,
Since the picture-in-picture is used to superimpose the child screen on the parent screen, there are the following problems.

That is, normally, in a videophone device, when an image is displayed on a display such as a television, the image of the other party who is currently talking is usually displayed.

Here, if the call waiting service is applied as in the case of a normal telephone device, if an interruption is received from the call waiting by another person, switching the line causes the face of the person who was talking until now to disappear from the image. Become.
If there is a screen memory function, it will not disappear if you memorize the screen before switching the call, but if there is an interruption by the waiting call, there is usually no room to do this kind of thing I think that the.

In such a case, it is very inconvenient, for example, when it is desired to leave the image of the previous speaker on the screen.

[0013] Therefore, an object of the present invention is to provide a videophone device that can automatically keep the previous image even when a call is switched by a call waiting function and can be used very conveniently. To do.

[0014]

The invention according to claim 1 is
In order to achieve the above object, in a videophone device capable of displaying a video signal sent by a line by a display means,
It is provided with a memory for storing the image of the other party and a control means for controlling the image of the other party before the line is switched to be stored in the memory when the interruption by the call waiting occurs.

According to a second aspect of the present invention, in a videophone device capable of displaying a video signal sent by a line on a display means, a memory for storing a video image of a communication partner and an instruction means for instructing switching of the line. When a call waiting interruption occurs and the line switching is instructed by the instructing unit, a control unit for controlling the line switching after storing the image of the other party before the line switching in the memory. I have it.

For example, as described in claim 3, the control means controls to display the previous image at an arbitrary position in an arbitrary size even after the line is switched and the image is switched. You may do it.

[0017]

According to the invention described in claims 1, 2 and 3, when the interruption by the waiting call occurs and the line switching is instructed by the instructing means, the image of the other party before the line switching is stored in the memory. The line is switched from. In this case, even after the line is switched and the image is switched, the previous image may be displayed at an arbitrary position and in an arbitrary size.

Therefore, even when the call is switched by the call waiting function, the previous image can be left as the switching operation is performed, and it can be used very conveniently.

[0019]

EXAMPLES Examples will be described below with reference to FIGS.

1 to 9 are views showing an embodiment of the video telephone device according to the present invention.

First, the structure will be described. 1 and 2 are
It is the external view which shows the video telephone device of this invention, and the system figure. FIG. 1 shows a system configuration by connecting a videophone device between a normal telephone device and a communication line, and FIG. 2 shows a videophone device connected with a television receiver and a normal telephone device. By doing so, the system is configured. The case where an analog telephone general subscriber line is used as a communication line will be described below.

In FIG. 1, the videophone device 1 is provided with a color liquid crystal display panel having a screen size of 3 inches and 110 × 160 pixels, and is provided with input / output terminals 24L and 24T which will be described later on the back surface.

This video telephone device 1 is installed between an input / output terminal modular jack type outlet 101 and a telephone set 102, and a modular cable 104 having a modular plug 103 at both ends is used to connect the modular jack type outlet 101 and the input / output terminal 24L. , And the input / output terminal 24T and the telephone set 102, respectively.

In FIG. 2, the video telephone device 100 is
As in the system of FIG. 1, the input / output terminals are installed between the modular jack type outlet 101 and the telephone 102,
An image received by the videophone device 100 can be input to the video terminal of the television 106 and displayed on a large screen on the display 106a. Further, in the television 106, channels, voices, and the like are remotely operated by a remote controller 107 using infrared rays, and a switch (SW) for instructing interruption processing by a call waiting is provided on the remote controller 107.

The video signal of the videophone device 100 is a video signal (for example, NT
SC, video signal, etc.) and displayed on the TV screen.

When there is an interruption by a third party in the call waiting service and the hook switch of the telephone set 102 or the interruption switch of the remote control 107 is pressed, the videophone device 100 stores the image of the current calling party in the memory. By outputting a switching signal from the telephone to the telephone line (the side of the modular jack type outlet 101), the previous image is displayed at an arbitrary position even after the exchange (not shown) of the telephone network is switched and the image is switched. It has a function that can be displayed in any size.

The difference between the system shown in FIG. 1 and the system shown in FIG. 2 lies in whether the videophone device has a monitor or a home-use television receiver is used as a monitor.

FIG. 3 is a block diagram showing a schematic configuration of the videophone device 1 shown in FIG. In FIG. 3, the videophone device 1 includes a key input unit 2, a control unit 3, an image processing unit 4, an audio processing unit 5, a modulation / demodulation unit 6, a camera unit 7, and a liquid crystal display unit 8. The input unit 2, the control unit 3, the image processing unit 4, the audio processing unit 5, and the modulation / demodulation unit 6 are
Each is connected to the bus 9.

As shown in FIG. 1, the key input unit 2 is composed of a plurality of key switches 10 and is used by an operator to instruct various operations in the videophone apparatus 1. The key switches 10 include a video on / off switch 10a, an image capture switch 10b, a small screen on / off switch 10c, and the like. The video on / off switch 10a displays the LCD screen on the liquid crystal display unit 8. The toggle switch for instructing the presence / absence and the image capture switch 10b are switches for instructing the storage of the image displayed on the liquid crystal display unit 8 as image data in a predetermined memory, and the small screen on / off switch 10c is a transmission screen. A toggle switch for displaying either one of the transmission screen and the reception screen as a parent screen on the liquid crystal display unit 8 and the other screen as a child screen when the user wants to view the screen and the reception screen at the same time. Is.

The control unit 3 includes a CPU (Central Processing).
Unit) 11, RAM (Random Ac-cess Memory) 1
2, ROM (Read Only Memory) 13.

The CPU 11 outputs various control signals for controlling each unit in the videophone device 1 to each unit via the bus 9 and executes a communication control program corresponding to the type of communication line to be connected. , Again, CPU11
Receives the image / audio data multiplexed and transmitted from the other party's videophone device, and when demodulated by the modulation / demodulation unit 6 and input, the demodulated image / audio data is separated and compressed. Image data compression via bus 9
It outputs the compressed audio data to the audio compression / expansion circuit 20 via the bus 9 as well as to the expansion circuit 14. Further, the CPU 11 has an image compression / expansion circuit 14
From the audio compression / decompression circuit 20 via the bus 9, and the compressed image data input via the bus 9 from the audio compression / decompression circuit 20 is multiplexed on the bus 9 as image / audio data.
Is output to the modulation / demodulation unit 6 via.

The RAM 12 is a semiconductor memory that stores program data used in the program processing executed by the CPU 11, compressed image data, audio data, and the like.

The ROM 13 is a semiconductor memory for storing programs and data used in the videophone device 1.

The image processing section 4 includes an image compression / expansion circuit 1.
4, ADC (Analog to Digital Converter: A / D converter) 15, video memory (VRAM) 16a, 1
6b, DAC (Digital to Analog Converter: D / A)
The converter) 17. Reference numeral 18 is an image input terminal.

The image compressing / expanding circuit 14 uses, for example, JPEG (Joint Photographic) according to a predetermined encoding method of the image data stored in the video memory 16a, that is, the type of image to be handled (still image in this case). (Codin
g) Experts Group) Performs compression processing (encoding) by DCT (discrete cosine transform), quantization, and Huffman encoding for each 8 × 8 pixel block, and receives and modulates via a communication line. Decompression (decoding) processing of the reception compressed image data demodulated by the demodulation unit 6 is performed, and the decompressed image data is stored in the video memory 1.
It is output to 6b and stored. The data compression rate in the image compression processing is about 7/100 (about 68/1000) in relation to the image quality after decompression.

Further, the image compression / expansion circuit 14 performs a process of synthesizing the image data from the camera section 7 with the image expanded by the image compression / expansion circuit 14 (see FIG. 5).

The ADC 15 converts the image signal (analog signal) input from the camera unit 7 into a signal (digital signal) that can be processed in the image processing unit 4, and the video memory 16
It is output to a.

The video memories 16a and 16b are VRAMs.
(Video RAM), video memory 16a
Is a semiconductor image memory for storing image data (digital data) output from the ADC 15, and the video memory 16b stores image data (digital data) compressed / expanded by the image compression / expansion circuit 14. Is a semiconductor image memory for the video memory 16
A display buffer 16c for storing the partner image before switching based on the call waiting service is provided in b.

The DAC 17 converts the image signal (digital signal) of the image data stored in the video memory 16 into a signal (analog signal) that can be displayed by the liquid crystal display unit 8 and outputs it. In this embodiment, since an analog data driver is used as a data driver for the LCD 28 described later, a DAC (D / A converter) is used.
However, if a digital data driver is used as the data driver, this DAC17
Is unnecessary.

In the system of FIG. 2, this D
The output of the AC 17 may be converted into a signal (for example, NTSC, video signal, etc.) used in the television receiver 106, and the liquid crystal display unit 8 is not necessary.

The voice processing unit 5 includes an ADC 19, voice compression /
The expansion circuit 20 and the DAC 21 are included.

The ADC 19 is the NCU 2 of the modulation / demodulation unit 6.
A voice signal (analog signal) input from the telephone set 102 via a telephone 3 (described later) is converted into a signal (digital signal) that can be processed in the voice processing unit 5 and output to the voice compression / expansion circuit 20. is there.

The audio compression / expansion circuit 20 converts the digital audio data input from the ADC 19 into, for example, CEL.
By P (Code-Excited Linear Predivtion) algorithm, by a predetermined encoding method by means for analyzing input data for a fixed time, means for synthesizing waveforms by analyzed parameters, means for calculating error between input waveform and synthesized waveform, etc. The input data from the bus 9 is subjected to compression (encoding) processing, the compressed audio data is output to the DAC 21, and the received compressed audio data demodulated by the modulation / demodulation unit 6 is expanded (decoded). ) Processing is executed and the expanded voice data is output to the DAC 21.
Note that the data compression rate in the voice compression process is about 5/100 (about 50/100) in consideration of the voice quality after decompression.
0).

The DAC 21 converts the audio signal (digital signal) expanded by the audio compression / expansion circuit 20 into an analog audio signal and outputs the analog audio signal to the telephone set 102 via the NCU 23 of the modulation / demodulation unit 6.

The modulation / demodulation unit 6 is a modem (MODEM, MOdula
tion and DEModulation) 22, NCU (Network Cont
rol unit) 23. 24L
(Modular jack 101 side), 24T (telephone 102
The side) is an input / output terminal for the above-mentioned communication line (in this case, a general subscriber line).

The modem 22 and the NCU 23 have the CPU 11
Compressed image and audio signals (digital) sent by
Is converted into a transmission signal (analog signal) that can be transmitted over a communication line, and the function as a "modulator", and conversely, the transmission signal (analog signal) sent over a communication line, It has a function as a "demodulator" that demodulates again and returns it to a digital signal, and the NCU 23 makes it possible to use it on a general subscriber line as a communication line to be used.

Further, the modems 22 and N in this embodiment are
The CU 23 is capable of signal transmission at the maximum data transmission rate of 14400 bps that can be used on an analog public line, and bidirectionally transmits image data and audio data by incorporating a video code and an audio code in one frame which is a processing unit. Image data for one screen every 3 seconds
It is transmitted as an intermittent image at the rate of frames.

FIG. 4 is a diagram showing the structure of one frame of the multiplexed code.

The multiplexing code which constitutes one frame is about 256 bytes (about 204 bytes) including a video header and a video code.
It is composed of video data of 8 bits) and audio data of about 256 bytes (about 2048 bits) including an audio header and an audio code. The video code and the audio code include an error correction code, and the video code Since the video header and the audio header are respectively added before and the audio code, the total transmission data amount of the image data included in the actual video code and the audio data included in the audio code is 9600b.
ps, which uses 4800 bps for image data and 4800 bps for audio data.

Specifically, the data length of one frame is about 512 bytes (about 4098 bits) for video data and about 256 bytes for audio data.
At a transmission rate of 14400 bps, the data transmission time for one frame is approximately 280 ms (approximately 14
Since it is 0 ms and about 140 ms for audio data, about 3.57 frames of data are transmitted per second, and video data transmitted per second is about 7300 bits (256 x 8).
× 3.57 = 7311). That is, in this embodiment, about 2300 which is obtained by subtracting the actual image data (4800 bps) from the data of about 7300 bits transmitted per second is used.
The 500-bit data includes the information about the screen size, the command about the image data transmission, the error correction code, and the like.

That is, as image data, one screen has 110 × 160 pixels and 4096 colors (12
When handling (bit) color image data, the amount of image data for one screen is 110 × 160 × 12 = 211200 bits (about 25.8 kilobytes), and by compressing the data to about 68/1000 by image compression processing 1
The image data is 4400 bits, and the intermittent still image is transmitted at a rate of 1 frame in a time period (that is, 14400/4800 = 3 seconds) obtained by dividing the 14400 bits by the number of bits (4800 bits) that can be transmitted in 1 second.

Therefore, in practice, 21,400 bits are divided by 3 to obtain 70400 bits (about 8.6).
The image data of kilobytes is compressed to about 68/1000 to form a video code including the image data of 4800 bits.

In this case, as the image data to be transmitted, the image data for one screen may be collectively compressed and the compressed image data may be transmitted, or at the time of transmitting the image data to be transmitted. The image data may be divided in advance based on the above, and the compression processing may be performed on the divided image data units.

On the other hand, the voice data is 12 bits / 8 kHz.
It is treated as digital data sampled by z, and this 12 × 8000 = 96000 bit voice data is compressed to about 50/1000 to obtain a voice code containing 4800 bit voice data. In FIG. 3, the camera unit 7 includes a lens 25 and a CCD (Charge Coupled Devic).
e) 26 and.

The lens 25 is an optical lens made of glass or plastic provided in the main body of the video telephone 1, and the CCD 26 generates an electric signal based on the intensity of the light imaged by the lens 25. A signal (analog signal) is output to the image processing unit 4.

The liquid crystal display unit 8 is a DD (Display Driver).
27 and an LCD (Liquid Crystal Display) 28. The system shown in FIG. 2 does not require the liquid crystal display unit 8.

The DD 27 drives the LCD 28 in order to display an image on the LCD 28 based on a video signal input from the image processing section 4.

The LCD 28 is composed of a color liquid crystal display device having a TFT (Thin Film T-ransistor) type liquid crystal display panel which is one of the active matrix type,
By driving the DD 27, a color video signal of up to 4096 colors (12 bits) is displayed. In addition, as described above, the number of display pixels of the LCD 28 is 110 × 16.
It is 0.

The ADC 30 converts a video signal, which is an analog signal input from the television tuner 29, into a digital signal.

The liquid crystal display device (LCD) is extremely thin, easy to reduce in size and weight as compared with an image display means such as a CRT, and the active matrix type L
Compared to a simple matrix type LCD, a CD can control fine halftones, can secure a high contrast ratio, and has a high response speed.
It is an effective device in the field where high-quality and multi-gradation color display is required, and especially TF which is a three-terminal element.
The active matrix type LCD using T can obtain a high image quality comparable to that of a CRT.

Further, the video telephone 1 according to the present embodiment.
Then, even if you switch the call by call waiting,
From the viewpoint that it is easier to confirm the image and keep the previous image automatically and it is easy to use, if there is an interrupt request by the call waiting, if the switch is instructed by the hook switch of the telephone 102, By storing the video of the other party's call in the display buffer 16c and then outputting a switching signal to the telephone line, the previous video is displayed even after the telephone network switch (not shown) is switched and the video is switched. Is displayed at any position and at any size. It should be noted that a hold image is output from the telephone network together with a hold sound to the other party before switching.

The bus 9 is a common signal path for connecting the key input unit 2, the control unit 3, the image processing unit 4, the audio processing unit 5, and the modulation / demodulation unit 6, and is an address bus for instructing an address. And a data bus for transferring data.

Next, the operation of this embodiment will be described.

First, the operation of the control unit 3 shown in FIG. 3 will be described based on the flowcharts of FIGS. 6 and 7. A program corresponding to the processing operation of the CPU 11 in the control unit 3 is also stored in the ROM 13 in the control unit 3.

FIG. 6 is a flow chart for explaining the processing operation of the CPU 11.

First, after the power supply of the video telephone 1 is turned on, initialization such as initialization in the control unit 3 and clearing of each memory is performed (step S1), and whether or not there is an input from the key input unit 2 is checked. A key scan is performed for checking (step S2), and when there is a key input, necessary processing described later is executed according to the key operation.

Next, the reception flag is once turned off (= "0").
Then, the line voltage level of the NCU 23 is monitored (step S3), and in this state, the ringer tone is detected to check whether there is a call from the communication partner (step S4).

If it is determined that it is the ringer tone section, the reception flag is turned on (= "1") (step S5), the line voltage level of the NCU 23 is monitored again, and the call is now in progress. It is determined whether or not (step S6).

If it is determined that the communication is not in progress, it is determined whether or not the video on / off switch 10a has been pressed. If not, the process is repeated from step S2 (step S7). ).

On the other hand, in the processing of step S6,
If it is determined that the call is in progress, then it is checked whether the reception flag is on (step S
8) If the reception flag is off (= “0”), the display screen (LCD 28) of the liquid crystal display unit 8 is displayed as in the case where the video on / off switch 10a is pressed in the process of step S7. Initial setting is performed (step S
9).

When the initial setting of the LCD 28 is completed, the image data stored in the video memory 16a is read into the image compression / expansion circuit 14, and the video memory 16b is used as it is.
The image data is transferred from the video memory 16a to the video memory 16b by being output to (step S10).

Next, a key scan is performed to check whether or not there is an input from the key input unit 2 (step S11), and it is determined whether or not the video on / off switch 10a has been pressed (step S11). S12),
It is determined whether or not the call is currently being made (step S13).

Here, in the judgment processing of steps S12 and S13, the video on / off switch 1
If 0a is not pressed and a call is in progress, the process is repeated from step S10. In addition, in the determination processing of steps S12 and S13, the image on / off switch 10a is not pressed,
In addition, when not in a call, the LCD 2 of the liquid crystal display unit 8
The screen displayed in 8 is erased (step S14), and the process is repeated from step S2. Further, in the judgment processing of the step S12, if the video on / off switch 10a is pressed, it is judged whether or not the call is currently in progress (step S15). If the call is not in progress, the step S14, When the process is performed again from the process of step S2, while a call is in progress, FIG.
Proceed to the process shown in.

If the reception flag is on (= "1") in the process of step S8, a key scan is performed to check whether there is an input from the key input unit 2 (step S16). ), It is determined whether or not the video on / off switch 10a is pressed (step S17), and it is determined whether or not the telephone call is currently in progress (step S18).

Here, in the determination processing of steps S17 and S18, the video on / off switch 1
If 0a is not pressed and the call is in progress, the process from step S16 is executed again, and the video on / off switch 10a is pressed in the determination process of steps S17 and S18. Not
If the call is not in progress, the above step S14,
The process is executed again from step S2. On the other hand, if the video on / off switch 10a is pressed in the determination process of step S17, the process proceeds to the process shown in FIG.

FIG. 7 is a flow chart for explaining the processing operation of the CPU 11 following FIG.

If a call is being made in the determination process of step S15, or if the video on / off switch 10a is pressed in the determination process of step S17, the negotiation process is performed (step S21), and the liquid crystal display is displayed. The screen of the unit 8 is initialized (step S2).
2).

Next, the CPU 11 issues a command to the image compression / expansion circuit 14 for image data compression / expansion processing (step S23), and also causes the audio compression / expansion circuit 20 to compress / expand the audio data. A processing command for processing is issued (step S24), and the CPU 11 modulates
It issues a processing command for communication processing to the demodulation unit 6 (step S25).

Then, a key scan is performed to check whether or not there is an input from the key input unit 2 (step S26), and it is determined whether or not the telephone call is currently in progress (step S27).

If a call is in progress, the above step S2 is performed.
When the process from step 3 is executed again and the call is not in progress, FIG.
The processing is executed again from the processing of steps S14 and S2 described above.

The image data compression / expansion process in step S23, the audio data compression / expansion process in step S24, and the data communication process in step S25 will be described below. Since the videophone device 1 of the present embodiment simultaneously executes image data processing and audio data processing in parallel in the transmission processing and the reception processing, the transmission processing and the reception processing will be separately described below. To do.

(Transmission Processing) The image data taken by the camera section 7 is A / D converted by the ADC 15,
Image data corresponding to one screen output from the ADC 15 in response to a trigger signal from the CPU 11 is stored in the video memory 1.
It is taken in by 6a. The image data taken into the video memory 16a is compressed by the image compression / expansion circuit 14 and temporarily stored in a buffer memory (not shown). Then, the image data stored in the buffer memory in a compressed state is sequentially read based on a control signal from the CPU 11.

Here, when it is desired to record a self-portrait (transmission image) displayed on the LCD 28 during a call, the operator depresses the image capture switch 10b, so that the image data stored in the buffer memory is stored in the RAM1.
Stored in 2.

In this case, since the data amount of the compressed image data for one screen is 14400 bits (about 1.76 kilobytes), in order to store the compressed image data for 10 screens, the image data is stored in the RAM 14. Storage area is about 1
8 kilobytes is enough.

On the other hand, the voice data input from the telephone set 102 is A / D converted by the ADC 19 from the input / output terminal 24T on the TEL side via the NCU 23, and then compressed by the voice compression / expansion circuit 20 to be stored in the buffer memory. (Not shown) is temporarily stored. The audio data stored in the buffer memory in the compressed state is C
It is sequentially read based on the control signal from the PU 11.

The CPU 11 sequentially reads the compressed image data and audio data, synthesizes the image data and the audio data, and outputs them to the modem 22. Then, after the input compressed data is modulated by the modem 22 and D / A converted, the input / output terminal 2 on the LINE side from the NCU 23
It is output to the analog public line via 4L.

(Reception Processing) The compressed image data and audio data are input from the analog public line to the modem 22 via the LINE side input / output terminal 24L and the NCU 23. The image data and audio data demodulated by the modem 22 are processed by the DSP (Digital
A / D conversion is performed by the signal processor and output to the bus 9 and sequentially transferred to the CPU 11 via the bus 9.

The CPU 11 separates the combined data into image data and audio data, the compressed image data is temporarily stored in the buffer memory, and the compressed audio data is temporarily stored in the buffer memory.

The image compression / expansion circuit 14 sequentially reads out the written image compression data from the buffer memory, decompresses it, and writes it in the video memory 16b.

When it is desired to record the partner image (received image) displayed on the LCD 28 during a call, the operator depresses the image capture switch 10b so that the image data stored in the buffer memory is stored. RAM1
Stored in 2.

In this case, as described in the above transmission processing, the data amount of the compressed image data for one screen is about 2.
Since it is 5.8 kilobytes, if the image data storage area of the RAM 12 is 256 kilobytes, about 10
Since 10 screens can be stored, the storage area for 10 screens can be stored in, for example, 3 screens for storing image data for transmission.
The image data for reception can be divided into seven screens and used.

On the other hand, the voice compression / decompression circuit 20 sequentially reads the written voice compressed data from the buffer memory, decompresses it, and outputs it to the DAC 21 at a constant rate. Then, the expanded analog voice data is output from the NCU 23 to the telephone set 102 via the input / output terminal 24T on the TEL side and can be heard from the handset.

The above transmission / reception processing is repeatedly executed until the receiver of the telephone set 102 is placed.

That is, in this embodiment, the modulation / demodulation unit 6
Based on the data compression rate (about 7/100) in the image compression / expansion circuit 14 and the image data transmission rate (4800 bps) of the modulation / demodulation unit 6, the image data and the audio data compressed by the are simultaneously transmitted. LCD
Image data for one screen (211
(200 bits) is divided into three and transmitted,
High-quality images are transmitted over the analog public line. That is, the screen size of the LCD 28 is 3 inches, and one screen is 1
10 × 160 pixels × 12 bits (4096 colors) = 211
Since it has 200-bit data, image data is transmitted at a rate of one frame every three seconds. However, as the number of pixels and the number of colors (the number of gradations) of one screen increases or decreases as the screen size changes, The time for transmitting one screen of image data is changed.

Specifically, for example, the mode for transmitting image data with 4096 colors is set to the normal mode, and the same number of pixels (1
When the mode for displaying 65536 colors (16 bits) in 10 × 160 pixels) is set to the high image quality mode, when transmitting image data in the high image quality mode, the image data amount for one screen is 110 × 160 × 16 = It becomes 281600 bits (about 34.4 kilobytes), which is 1 when the data is compressed to about 68/1000 by the image compression process.
It is image data of 9200 bits, and this 19200 bits is divided by the number of bits (4800 bits) that can be transmitted in 1 second (that is, 19200/4800 = 4 seconds).
Intermittent still images are transmitted at a rate of one frame. That is, in this case, image data of 70400 bits (about 8.6 kilobytes) obtained by dividing 281600 bits by 4 is compressed to about 68/1000, and as shown in FIG. 4, a video including image data of 4800 bits. It is a code.

FIG. 8 is a flow chart showing display control of parent-child screen display.

During the key scan processing shown in FIGS. 6 and 7, first, the key is fetched (step P1),
It is checked whether there is a key input (step P
2).

If there is no key input, the key scan process is terminated and only the image of the other party is displayed.

On the other hand, if there is a key input, the type of the key is judged (step P3), and the small screen on / off switch 1
When 0c is pressed, it is determined which mode the display content mode displayed on the child screen is (step P4), and the type of frame corresponding to the mode determined by the mode determination processing is determined (step P5). .

Then, the CPU 11 causes the image compression / expansion circuit 14 to send a picture-in-picture (Pi
(nP) display command is issued, and the picture compression / expansion circuit 14 performs picture-in-picture display (step P6). By the way, in this state, the image on your side is displayed on the child screen.

Display control in parent-child screen display (picture-in-picture) will now be described.

A display buffer (not shown) for the LCD 28 for picture-in-picture display
The screen corresponding to the picture-in-picture is drawn inside, and the drawn data is displayed as it is. CPU
Reference numeral 11 designates an image compression / compression command for executing / stopping the picture-in-picture display and replacing the parent screen with the child screen.
The image compression / expansion circuit 14 performs each process in response to each command sent from the CPU 11 only by sending it to the expansion circuit 14.

Here, if there is an interruption by the call waiting and the line changeover switch (hooks switch of the telephone set 102) is pressed, the image of the current communication partner is stored in the memory 16c before the CPU 11 outputs the changeover signal to the line. Then, the call waiting process (FIG. 9) of switching the line and outputting the signal to the telephone network is performed (step P7). The exchange is switched in the telephone network based on this switching signal.

In addition, another key (for example, zoom, reverse,
If there is an input by the screen stillness or the like), other processing corresponding to the pressed key is performed (step P8). In this case, other processing is not limited to the above-described zooming, reversing, screen stillness, etc., but includes reception of TV broadcasts, etc., and changes the frame type according to the type of image displayed on the child screen. May be

FIG. 9 is a flow chart showing the operation of the videophone device 1 when there is an interruption by the waiting call.

When it is detected that the line switch (hook switch of the telephone set 102 or the switch of the remote controller 107 of FIG. 2) is pressed due to an interruption by the call waiting (step P11), first, the image of the current partner is displayed. It is stored in the memory 16c (step P12). After this, a switching signal is output to the telephone network to switch the telephone network switch (step P1).
3) After the image of the new partner is displayed on the liquid crystal display unit 8,
The previous image stored in the memory 16c is displayed on the PinP display portion (step P14).

In this embodiment, the PinP section is used as the display location of the previous image, but this is not limited to the PinP section.

In the system of FIG. 2, the display position and size of the previous image can be arbitrarily set by the switch on the remote controller 107.

As described above, in the videophone device 1 of the present embodiment, when there is an interruption by the call waiting and the switch for switching the telephone line is pressed, the current call is output before the switching signal for switching the telephone line is output. After the other party's video is stored in the memory, the signal is switched to the telephone network and the previous video is displayed at any position and in any size even after the telephone line is switched and the video is switched. Since it is equipped with a function that allows you to switch to another line by pressing the line switch when an interruption is received from the call waiting while the image of the other party who is currently talking is displayed. You can keep the previous image, which is very convenient to use.

The image data compression method is not limited to the JPEG algorithm in this embodiment, and may be, for example, a block coding method, a predictive coding method, an orthogonal transform coding method, or the like. The data compression method is not limited to the CELP algorithm in this embodiment, but may be, for example, AD-PCM (Adaptive Differenti-
al Palse Code Modulation) method, VSELP (Vector
A Sum Excited Linear P-rediction) method or the like may be used.

Further, by providing a composite video input terminal, an S terminal or the like as the image input terminal 18 provided in the image processing section 4, the video cassette recorder (VC
R) or a laser disc player (LD) and other video equipment can be connected, and the video input from the video equipment such as a video cassette recorder or a laser disk player is captured as image data and transmitted to the communication partner. It is also possible to do so.

[0112]

According to the first, second and third aspects of the present invention, when the interruption by the call waiting occurs, the video of the current call partner is stored in the memory before the line is switched, and then the line is switched. Therefore, even if the call is switched by the call waiting function, the previous image can be retained and it can be used very conveniently.

[Brief description of drawings]

FIG. 1 is an external view showing a videophone device of the present invention.

FIG. 2 is a diagram showing a connection of the videophone device of the embodiment.

FIG. 3 is a block diagram showing the overall configuration of the videophone device of FIG. 1 of the same embodiment.

FIG. 4 is a diagram showing the structure of one frame of a multiplexing code according to the embodiment.

FIG. 5 is a diagram showing an example of simultaneous display of a reception screen and a transmission screen of the embodiment.

FIG. 6 is a flowchart showing a control operation of a control unit of the embodiment.

FIG. 7 is a flowchart showing the control operation of the control unit following that of FIG. 6 of the embodiment.

FIG. 8 is a flowchart showing display control of parent-child screen display in the embodiment.

FIG. 9 is a flowchart showing an operation of the videophone device in the case where there is an interruption by the waiting call of the embodiment.

[Explanation of symbols]

 1 Videophone Device 1a Device Main Unit 2 Key Input Unit 3 Control Unit 4 Image Processing Unit 5 Audio Processing Unit 6 Modulation / Demodulation Unit 7 Camera Unit 7a Video Cable 8 Liquid Crystal Display 9 Bus 10 Key Switch 10a Video On / Off Switch 10b Image Capture switch 10c Child screen on / off switch 11 CPU 12 RAM 13 ROM 14 Image compression / expansion circuit 15 ADC 16a Video memory 16b Video memory 16c Display buffer 17 DAC 18 Image input terminal 19 ADC 20 Audio compression / expansion circuit 21 DAC 22 Modem 23 NCU 24L Input / output terminal 24T Input / output terminal 25 Lens 26 CCD 27 DD 28 LCD 101 Modular jack type outlet 102 Telephone 103 Modular plug 104 Modular cable 106 Television 106 a display 107 remote control

Claims (3)

[Claims] 1. A videophone device capable of displaying a video signal sent through a line by a display means, a memory for storing the image of the other party of the call, and the other party before the line is switched when an interruption occurs by a call waiting function. And a control means for controlling so that the image of (4) is stored in the memory. 2. A videophone device capable of displaying a video signal sent by a line on a display means, a memory for storing the image of the other party of the call, an instruction means for instructing switching of the line, and an interruption by a waiting call. Then, when the line switching is instructed by the instructing unit, the control unit controls to store the image of the communication partner before the line switching in the memory and then switch the line. Videophone device. 3. The control means controls to display the previous image at an arbitrary position and in an arbitrary size even after the line is switched and the image is switched. The videophone device according to claim 1 or 2.