JPH07298229A - Communication method, communication system and terminal equipment - Google Patents

Abstract

PURPOSE:To utilize effectively a communication channel in the communication system in which communication data are circulated unidirectionally through the communication channel. CONSTITUTION:TV conference terminal equipments 300, 302, 304, 306 are connected in a loop by a digital line 308 being a digital communication network such as an ISDN. Each of the TV conference terminal equipments 300-306 deletes data generated by a downstream terminal equipment from received data and inserts data generated in a concerned terminal equipment to the received data and outputs the resulting data to the downstream side terminal equipment. For example, the terminal equipment 300 receives data generated by the terminal equipments 302, 304, 306 from the terminal equipment 306 in a form of a multiplexed communication frame. The terminal equipment 300 deletes the data generated from the terminal equipment 302 from the received data and inserts the data generated by itself to the received data and outputs the resulting data to the terminal equipment 302. That is, the terminal equipment 300 transfers the data generated from the terminal equipments 300, 304, 306 to the terminal equipment 302.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication method, a communication system and a terminal device, and more specifically to a communication method, a communication system and a terminal device suitable for multipoint image communication.

[0002]

2. Description of the Related Art In recent years, the development of image compression coding technology and the spread of digital communication lines have been remarkable, and service regulations and protocol regulations for audio-visual services and multimedia multiplexing frame configuration regulations for videophones or videoconferences have been remarkable. Etc. were prepared as recommendations, etc.
Various audio-visual terminal devices such as a TV telephone device and a TV conference system have been proposed. Above all, 3
Attention has been paid to a multipoint video conference system in which the above multipoint terminals are connected to perform a video conference or a video conference.

In a multipoint video conference system, a multipoint communication control unit (hereinafter referred to as MCU) uses a multipoint TV.
Enables the interconnection of conference terminals, which allows multipoint T
V conference is realized.

Further, there has been proposed a method for realizing a multipoint TV conference system by connecting a TV conference terminal to a communication line in a ring shape or a bus shape and relaying predetermined data in each terminal. Specifically, a data area is allocated to each terminal to circulate various data including video data, and each terminal generates or updates the circulated data as necessary.

[0005]

However, in the former multipoint TV conference system, all the TV conference terminals are connected to the MCU, and the MCU monitors and controls all the TV conference terminals and the communication between the terminals. Since the multipoint video conference system is realized, it has the following drawbacks. First,
The video conference cannot be realized when the MCU is in an inoperable state or is being used by another multipoint video conference. Secondly, the MCU main body is very expensive because it requires a plurality of communication control circuits for connecting a plurality of terminals. Thirdly, the number of participants in the conference is limited depending on the terminal (line) accommodation capacity of the MCU.

The latter method, that is, the method of connecting a TV conference terminal to the communication line in a ring shape or a bus shape, allocating a data area for each terminal, and relaying or updating the circulating data does not require an MCU. However, since all the data circulate in the communication path, each terminal also receives the data generated by itself. It is a completely meaningless operation for the own terminal to receive the data inserted on the communication path. In other words, essentially meaningless data always occupies a part of the communication line. Particularly, since the moving image information has a huge amount of information to be transmitted, as a result, it may hinder the effective use of the communication line, and it may be impossible to transmit other useful information.

It is an object of the present invention to provide a communication method that does not use an MCU or an expensive device that replaces it, a communication system, and a terminal device that can be used in the communication system.

It is another object of the present invention to provide a communication method, a communication system, and a terminal device that can be used in this system, which effectively uses the communication capacity.

[0009]

A communication method according to the present invention is a communication method in which communication data circulates on a communication path connected by a plurality of terminals, in which each terminal receives data received from an upstream side from a downstream side. It is characterized in that the information generated by the terminal adjacent to the side is deleted, the generation information of the own terminal is added, and the data is output to the downstream side.

A communication system according to the present invention is a communication system in which communication data circulates in a communication path to which a plurality of terminals are connected, and each of the plurality of terminals receives the communication conference data from the upstream side. And an information changing unit that deletes information generated by another terminal adjacent to the downstream side from the communication data received by the receiving unit and adds generation information of the own terminal, and an output of the information adding unit. And a transmitting means for transmitting to the downstream side.

The terminal device according to the present invention deletes information generated by another terminal adjacent to the downstream side from the receiving means for receiving the communication conference data from the upstream side and the communication data received by the receiving means. It is characterized by comprising information changing means for adding the generated information of the own terminal and transmitting means for transmitting the output of the information adding means to the downstream side.

The information changing means deletes the information generated by another terminal adjacent to the downstream side from the communication data received by the receiving means, and the information generated by the own terminal at the output of the deleting means. And information adding means for adding. The information changing unit may also be a unit that replaces, in the communication data received by the receiving unit, a portion containing information generated by another terminal adjacent to the downstream side with information generated by the own terminal. Good.

The communication data preferably includes video conference image data and audio information.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 3 shows a schematic system diagram of a configuration in which the invention according to the present application is applied to a TV conference system having four terminals. In FIG. 3, 300, 302, 304, 3
06 is a TV conference terminal, 308 is ISDN
Is a digital line composed of a digital communication network such as. The terminals 300, 302, 304, 306 are connected in a loop by a digital line 308. That is,
The TV conference terminal 300 is the TV conference terminal 302 and the TV conference terminal 306, and the TV conference terminal 302 is the TV conference terminal 30.
4 and the TV conference terminal 300 and the TV conference terminal 304 are T
The V conference terminal 306 and the TV conference terminal B 302, and the TV conference terminal 306 are the TV conference terminal 304 and the TV conference terminal 3.
00, respectively.

Here, the communication line 3 is formed in a loop.
A communication frame composed of data stored in each of the terminals 300, 302, 304, 306 circulates on 08. Each of the TV conference terminals 300 to 306 replaces a part of the received data with the data generated by the device itself and relays the rest, and relays the rest as it is. Each of the TV conference terminals 300 to 306 also appropriately processes the received data and outputs it to an output device such as an image monitor or a speaker in its own device.

TV conference terminals 300, 302, 304, 3
A schematic configuration block diagram of 06 is shown in FIG. In FIG. 2, 10 is a camera for photographing the participants of the conference, 12 is a document camera for photographing the conference materials such as drawings, and 14 is a camera 1.
An image input interface that selects 0 or 12 output and converts it to a predetermined internal format, 16 is a monitor that displays an image,
An image output interface 18 supplies an image signal to the monitor 16.

The monitor 16 may be a single image display device or a plurality of image display devices, and further, a single image display device or a device capable of displaying a plurality of images in separate windows by a window display system. Good.

A selection / combination circuit 20 selects and combines (for example, picture-in-picture processing and / or screen freeze processing) input images and received images from the cameras 10 and 12 and supplies them to the image output interface 18.
Reference numeral 22 is an image coding / decoding circuit including an image coding circuit 22a for coding the image signal to be transmitted and an image decoding circuit 22b for decoding the received coded image signal.

Reference numeral 24 is a handset consisting of a microphone and a speaker, 26 is a microphone, 28 is a speaker, and 30 is a voice input / output interface for the handset 24, the microphone 26 and the speaker 28. The voice input / output interface 30 not only switches the voice input / output of the handset 24, the microphone 26, and the speaker 28, but also performs echo / cancel processing, dial tone, ringing tone,
Tones such as busy tones and ring tones are generated. Reference numeral 32 is a voice encoding / decoding circuit including a voice encoding circuit 32a for encoding the voice signal to be transmitted and a voice decoding circuit 32b for decoding the received encoded voice signal.

Reference numeral 34 designates two communication lines (for example, ISDN).
It is a line interface of lines 35a and 35b.
In this embodiment, the communication line 35a is for data reception and the communication line 35b is for data transmission, and they are respectively connected to adjacent terminals on a ring-shaped communication path. 36
Is multiplexed with the coded information to be transmitted from the image coding circuit 22a and the audio coding circuit 32a and supplied to the line interface 34.
4, the encoded image information, the encoded audio information, the data and the control command are separated from the received information supplied from No. 4, the image information is sent to the image decoding circuit 22b, the audio information is sent to the audio decoding circuit 32b and the data and the control command are sent. Is a demultiplexing / multiplexing device for supplying to the system control circuit 38 described later.

Reference numeral 38 is composed of a CPU, a ROM, a RAM and an auxiliary storage device, and in particular, the image input interface 14, the image output interface 18 and the selective combining circuit 2 are provided.
0, a system control circuit for controlling the image encoding / decoding circuit 22, the audio input / output interface 30, the audio encoding / decoding circuit 32, and the demultiplexing / multiplexing device 36, and 39 indicates to the system control circuit 38 the user a predetermined instruction It is an operating device for inputting (for example, a numeric keypad, a keyboard, etc.).

The flow of image signals and audio signals when the terminal shown in FIG. 2 performs one-to-one TV conference communication will be briefly described. The input images from the camera 10 and the document camera 12 are selected by the image input interface 14, and one of them is input to the selection / combination circuit 20. The selective synthesizing circuit 20 normally outputs the input images from the cameras 10 and 12 as they are to the encoding circuit 22a of the image encoding / decoding circuit 22. The image encoding circuit 22 a encodes the input image signal in the encoding mode according to the control signal from the system control circuit 38 and the internal determination, and outputs it to the demultiplexing / multiplexing device 36.

On the other hand, the input voice signal from the microphone or the microphone 26 of the handset 24 is input to the voice encoding circuit 32a of the voice encoding / decoding circuit 32 via the voice input / output interface 30 and is encoded to be the demultiplexer. 36
Applied to.

The demultiplexing / multiplexing device 36 includes an encoding circuit 22.
The coded signals from a and 32a are multiplexed and output to the line interface 34. The line interface 34 outputs the information signal to be transmitted from the demultiplexer 36 to the communication line 35b.

The signal received from the communication line 35a is supplied from the line interface 34 to the demultiplexer / multiplexer 36. The demultiplexing / multiplexing device 36 separates the coded image signal and the coded audio signal from the received signal and applies them to the image decoding circuit 22b and the audio decoding circuit 32b, respectively. The image decoding circuit 22 b decodes the coded image signal from the demultiplexing / multiplexing device 36 and applies it to the selective synthesizing circuit 20.

The selective combining circuit 20 is a system control circuit 38.
Image input interface 14 according to the control signal from
The input image from and the received image from the image decoding circuit 22b are selectively combined and output to the image output interface 18. The selective combining circuit 20 performs, for example, picture-in-picture or fitting into a corresponding window in the window display system as a combining process. The image monitor 16 displays the image signal from the image output interface 18 as an image. As a result, the input image and / or the received image is displayed on the screen of the monitor 16.

The received voice signal decoded by the voice encoding circuit 32b is transmitted through the voice input / output interface 30 to the speaker of the handset 24 and / or the speaker 28.
Applied to. As a result, the voice from the communication partner can be heard.

Note that commands other than images and voices to be transmitted to the communication partner are directly supplied from the system control circuit 38 to the demultiplexing device 36, and the received commands are sent from the demultiplexing device 36 to the system control circuit 38. Directly supplied to.

FIG. 4 shows an example of a multiplexed frame structure of various information, in this embodiment, image information, audio information and control information.

Next, an operation in the case of performing a video conference communication between three or more multipoints will be described. Note that, in the following, in the connection configuration shown in FIG. 3, focusing on the TV conference terminal 300, when it is described as its own terminal, it refers to the TV conference terminal 300.

First, an outline of the operation of the entire TV conference communication system will be described. As described above, on the loop formed by the digital communication lines, on the loop formed by the digital communication lines connecting each TV conference terminal forming the TV conference communication system, the data generated by each TV conference terminal is a predetermined communication frame. Is configured and transmitted.

First, the terminal 300 is the TV conference terminal 306.
From the digital communication network 308. The received data is TV conference terminals 302, 304 and 3
06 has a communication frame configuration in which the data stored (generated) is multiplexed. Basically, the video conference terminal 3
The data stored by 00 (own terminal) is not included in the communication frame of the received data. Therefore, the terminal 300
Does not receive the data output to the communication line 308 by itself.

In the terminal 300, the demultiplexing / multiplexing device 36 is
The received frame data is separated according to the data type and the terminal storing it. The separated received coded image data is sequentially transferred to the image decoding unit 22b and subjected to decoding processing, applied to the monitor 16 via the selective combining circuit 20 and the image output interface 18, and displayed as an image. Similarly, the separated reception coded voice data is decoded by the voice decoding unit 32 b, and is transmitted via the voice input / output interface 30 to the handset 24 or the speaker 28.
Is applied to the sound output. Control signals and the like are transferred to the system control circuit 38.

In addition to the execution of these operations, the terminal 300 relays the data in the predetermined area in the received frame to the TV conference terminal 302. That is, in this embodiment,
In the relay transmission operation, the received frame data is not simply transmitted back, but the data portion required by the receiving terminal is transmitted. Specifically, after detecting and recognizing the data area (in the communication frame) stored by the TV conference terminal 302 which is the next relay transmission destination and canceling the data in the area,
Data generated in the conference terminal 300 is stored in this area and transmitted to the TV conference terminal 302.

FIG. 5 shows an example of a multiplexed frame structure of each point and various information in the received data, and FIG. 6 shows an example of a multiplexed frame structure of each point and various information in the transmitted data in comparison with FIG. Show. Here, the transmission rate of the communication line connecting each point terminal is R, and the transmission rate assigned to each terminal is R / 3. FIG. 7 is a schematic diagram showing the data transmission direction between the terminals.

An internal circuit of the demultiplexing / multiplexing device 36 for realizing such selective relay transmission will be described. FIG. 1 shows a schematic block diagram thereof.

In FIG. 1, reference numeral 100 denotes a multiplexer, which is encoded image data to be transmitted from the image encoding circuit 22a (data generated by its own terminal) and encoded image data to be relay-transmitted (other terminals). Image multiplexing circuit 1 that multiplexes the data generated by the
02, encoded voice data to be transmitted from the voice encoding circuit 32a (data generated by the own terminal) and encoded voice data to be relay-transmitted (data generated by another terminal and required by the receiving side terminal) ) And a voice multiplexing circuit 1 for multiplexing
04, the output of the image multiplexing circuit 102, the output of the audio multiplexing circuit 104, and the multiplexing circuit 106 that multiplexes the control data (including synchronization data and the like) from the system control circuit 38.

Reference numeral 108 denotes a demultiplexing device, which receives the received multiplexed data input from the line interface 34 as image information,
Separation circuit 110 for separating audio information and control information for the system control circuit 38, image separation circuit 112 for separating image information output from the separation circuit 110 for each terminal, and audio information output from the separation circuit 110. A voice separation circuit 114 for separating the terminal for each terminal.

Reference numeral 116 is a point information management device for identifying the terminal that generated the data in the multiplexed communication frame from the control data separated by the separation circuit 110. The point information management device 116 associates the identification result of the data generation terminal with the data in the received communication frame, and manages the terminal point information.

Reference numeral 118 is a canceling device which deletes the data portion generated by the receiving side terminal from the outputs of the image separating device 112 and the audio separating device 114 according to the spot information from the spot information managing device 116 and outputs it. The image output and the audio output of the cancel device 118 are applied to the image multiplexing circuit 102 and the audio multiplexing circuit 104, respectively, as encoded information to be relay-transmitted.

The operation of the apparatus shown in FIG. 1 will be described in detail.

First, the separating operation of the separating device 108 will be described. Received data from the communication line 35a is input to the separation circuit 108 via the line interface 34 (FIG. 2). The received data that is input is a multiplexed communication frame in which image data, audio data, control data, etc. are multiplexed, and the separation circuit 110 separates this multiplexed frame according to its frame configuration information. The image data is sent to the image separation circuit 112, and the audio data is sent to the audio separation circuit 11.
4. Output control data and the like to the system control circuit 38 and the spot information management device 116.

Image separation circuit 112 and audio separation circuit 11
4 further separates the separated image data and audio data according to the terminal that stores it on the communication line, that is, the terminal point where the data is generated. The terminal spot information is supplied from the spot information management device 116. The image separation circuit 112
The image data of each separated point is decoded by the image decoding circuit 22b.
And output to the cancel device 118. Similarly, the voice separation circuit 114 outputs the separated voice data of each point to the voice decoding circuit 32b and the cancel device 118.

In this way, the received data separated according to the data type is further separated according to the storage point,
Each of them is supplied to a processing circuit in its own terminal and is also supplied to the cancel device 118 for relay transmission. Specifically, the data in communication frame units received from the TV conference terminal 306 is separated into various data such as images, voices, and controls, which are further stored in the data stored in the TV conference terminal 302 and the TV conference terminal 304. The stored data,
And the data stored in the TV conference terminal 306.

The cancel device 118 operates as follows. In the following, information generated by each terminal will be referred to as spot information. That is, the image data and audio data generated by each terminal are described as spot image data and spot audio data, respectively.

Image data and voice data generated by terminals other than the own terminal are input to the cancel device 118 from the image separation circuit 112 and the voice separation circuit 114, respectively, and the data storage terminal spot information is sent from the spot information management device 116. Then, the next destination point information of the relay data is input from the system control circuit. The canceling device 118 detects the data area stored in the terminal point of the next transmission destination based on the terminal point information from the point information managing device 116, and detects the point image data and the point audio from the image separating circuit 112 and the sound separating circuit 114. Of the data, the data in the area stored by the terminal point which is the next transmission destination is canceled or deleted. The data in which only the data stored in the next transmission destination terminal is canceled is applied to the image multiplexing circuit 102 and the audio multiplexing circuit 104 as relay encoded image data and relay encoded audio data, respectively.

The spot information management device 116 detects and recognizes the terminal spot information storing each data from the received / separated control data (or as information multiplexed with various data), and stores the various data. Identify and associate points. Further, according to an instruction from the system control circuit 38, it takes charge of a part of the multiplexing processing control in the image multiplexing circuit 102, the audio multiplexing circuit 104, and the multiplexing circuit 106.

Next, the multiplexing operation of the multiplexing device 100 will be described. The image multiplexing circuit 102 includes an image encoding circuit 2
The coded image data of the terminal itself is input from 2a, and the coded image data to be relay-transmitted is input from the cancel device 118. The image multiplexing circuit 102 is used for the spot information management device 1
These image data are multiplexed based on the 16 terminal point information and the multiplexing control information of the system control circuit 38. Here, the self-terminal coded image data is the cancellation device 11
The data is inserted into the area where the data is canceled by 8, that is, the storage area allocated to the relay destination terminal.

The speech multiplexing circuit 104 receives the speech data encoded by the terminal itself from the speech encoding circuit 32a and the speech data to be relayed from the cancel device 118. As with the image multiplexing circuit 102, the audio multiplexing circuit 104 multiplexes these audio data based on the terminal location information of the location information management device 116 and the multiplexing control information of the system control circuit 38. even here,
The own terminal encoded voice data is inserted into the area where the data is canceled by the canceling device 118, that is, the storage area allocated to the relay destination terminal.

The multiplexing circuit 106 is the system control circuit 3
In accordance with the multiplexing control information of No. 8, multiplexed image data from the image multiplexing circuit 102, multiplexed audio data from the audio multiplexing circuit 104, control data from the system control circuit 38, synchronization data, and the like are multiplexed. Turn into.

In this way, in this embodiment, the data stored in the next destination terminal is deleted and the data of its own terminal is inserted therein. In other words, the data area (or transmission rate) assigned to the next destination terminal is used as the assigned data area (or transmission rate) of the own terminal for relay transmission.

By such a demultiplexing operation, the TV conference terminal 300 transmits the next data from the data received from the TV conference terminal 306 (data placed on the communication line by the TV conference terminals 302, 304, 306). The area in which the data generated by the previous TV conference terminal 302 is stored is canceled, the data generated by the own terminal (TV conference terminal 300) is inserted in the area, and the data is transmitted to the TV conference terminal 302.

By the above operation, in the situation where the communication frame composed of the data generated by the plurality of TV conference terminals circulates on the loop constituted by the digital communication line, the transmission of the data which has no meaning to the next destination terminal is transmitted. However, since only useful data to be transmitted is relayed and transmitted, it is possible to realize an efficient multipoint TV conference communication system that effectively uses a communication line.

In the above embodiment, the description has been made focusing on the one-way loop. However, in a digital communication network such as ISDN, it is possible to perform both times transmission between terminals, so as shown in FIG. It goes without saying that actually two loops in opposite directions can be constructed and used.

In the above embodiment, the case where the data to be transmitted by each TV conference terminal is the image information and the audio information has been described, but the present invention is not limited to this. That is, it goes without saying that the present invention can be applied as it is to the transmission of various information effective for a two-point or multipoint TV communication conference, as well as multipoint communication and control information for controlling terminals. Also,
Although the multi-point video conference has been described as an example, it is obvious that it can be applied to other image communication.

In the above embodiment, the equal transmission rate was assigned to each terminal in the communication frame, but it is also clear that a different rate or a variable rate may be used for each terminal. A control rate may be set in order to transmit or circulate control data for multipoint communication or the like, and the present invention is applied to such control information as well to improve the utilization of the communication line. You can

Further, in the above embodiment, four points are connected in a ring shape, but the present invention is not limited to this in terms of the number of points and the connection form. That is, the number of points is 3 or 5 or more, and the connection is ring-shaped or
Various connection forms can be used, such as the chain shape shown in FIG.

In the above embodiment, the data of the area of information generated by another terminal adjacent to the downstream side is deleted in the multiplexed communication frame, and then the information generated by the own terminal is inserted.
However, if the size of the data area that can be used by each terminal is fixed, the generation of the own terminal is performed directly in the information area generated by another terminal adjacent to the downstream side. You may overwrite the information.

In the case where the participating terminals are specified at the time of setting up the video conference, if the storage location of the occurrence information of each terminal in the multiplexed communication frame flowing through the communication path is fixed, in the multiplexed communication frame The information that indicates which terminal has the occurrence information stored in which data area is
You don't have to. This is because each terminal can determine which terminal the information is from from the position in the multiplexed communication frame.
Of course, in the case of allowing late participation, it is convenient to include in the multiplexed communication frame, information indicating in which data area of the multiplexed communication frame the generation information of which terminal is stored. This is because it is possible to save the trouble and time for updating the information on the arrangement order of the participating terminals held by each terminal each time the participant joins halfway.

[0061]

As can be easily understood from the above description, according to the present invention, it is possible to improve the utilization efficiency of a communication path in a communication system in which communication data circulates in a communication path to which a plurality of terminals are connected. . As a result, the communication speed can be relatively increased, and image data, which is a huge amount of data, can be communicated with a relatively low speed communication path.

When the information generated by the own terminal is inserted into the portion where the information generated by another terminal adjacent to the downstream side is deleted, the information generated by another terminal adjacent to the downstream side in the communication frame is inserted. By replacing the accommodating portion with the generated information of the own terminal, it is not necessary to perform the two processes of inserting the generated information of the own terminal after deleting the information generated by the terminal adjacent to the downstream side. There is an effect that only step processing is required.

[Brief description of drawings]

1 is a schematic block diagram of an internal circuit of the demultiplexing and multiplexing unit 36 shown in FIG. 2, which is a characteristic part of one embodiment of the present invention.

FIG. 2 is a schematic configuration block diagram of an image communication apparatus of this embodiment.

FIG. 3 is a schematic configuration diagram of a TV conference communication system according to the present embodiment.

FIG. 4 is a basic structural diagram of a multiplexed communication frame.

FIG. 5 shows a multiplexed frame structure which the terminal 300 receives from the terminal 306.

FIG. 6 shows a multiplexed frame configuration transmitted from terminal 300 to terminal 302.

FIG. 7 is a schematic diagram showing a data transmission direction between terminals in the present embodiment.

FIG. 8 shows a case where an ISDN line is used in this embodiment,
It is a double loop connection structural example.

FIG. 9 is an example of a connection form of chain connection.

[Explanation of symbols]

10: camera 12: document camera 14: image input interface 16: monitor 18: image output interface 20: selective combining circuit 22: image encoding / decoding circuit 22a: image encoding circuit 22b: image decoding circuit 24: handset 26: Microphone 28: Speaker 30: Voice input / output interface 32: Voice coding / decoding circuit 32a: Voice coding circuit 32b: Voice decoding circuit 34: Line interface 35a, 35b: Communication line 36: Demultiplexing / multiplexing device 38: System control Circuit 39: Operating device 100: Multiplexing device 102: Image multiplexing circuit 10
4: Audio multiplexing circuit 106: Multiplexing circuit 108: Separation device 110: Separation circuit 112: Image separation circuit 11
4: Voice separation circuit 116: Point information management device 11
8: Cancel device 300, 302, 304, 306: TV conference terminal 30
8: Digital line

Claims (15)

[Claims] 1. A communication method in which communication data circulates in a communication path connected to a plurality of terminals, wherein each terminal deletes information generated by a terminal adjacent to the downstream side from data received from the upstream side. , A communication method characterized by adding generation information of its own terminal and outputting data to the downstream side. 2. The communication method according to claim 1, wherein the communication path is a communication line that connects the plurality of terminals in a loop. 3. The communication method according to claim 1, wherein the communication path is composed of a communication medium that connects the plurality of terminals in a chain and has two communication lines. 4. A communication system in which communication data circulates in a communication path to which a plurality of terminals are connected, each of the plurality of terminals receiving means for receiving communication conference data from an upstream side, and the receiving means. From the received communication data, information changing means for deleting information generated by another terminal adjacent to the downstream side and adding generation information of the own terminal, and transmitting the output of the information adding means to the downstream side A communication system comprising: 5. The deleting means for deleting the information generated by another terminal adjacent to the downstream side from the communication data received by the receiving means by the information changing means, and the output of the deleting means of the own terminal. The communication system according to claim 4, further comprising information addition means for adding the generated information. 6. The means for replacing the portion of the communication data received by the receiving means, which contains information generated by another terminal adjacent to the downstream side, with the generated information of the own terminal, in the information changing means. The communication system according to claim 4, wherein 7. The communication data has a multiplexed frame structure in which data generated by the plurality of terminals is multiplexed,
The communication system according to claim 4, wherein the information changing unit adds the generation information of the own terminal to a data area that stores information generated by another terminal adjacent to the downstream side. 8. The communication system according to claim 7, wherein the multiplexed frame structure includes information for identifying a terminal that has supplied data in each data area. 9. The communication system according to claim 4, wherein the communication data includes image data for TV conference and audio. 10. A terminal device for connecting a looped communication path to a communication system through which communication data flows, comprising: receiving means for receiving communication data from an upstream side; and downstream of communication data received by the receiving means. It is characterized by comprising information changing means for deleting the information generated by another terminal adjacent to the side and adding the generated information of the own terminal, and transmitting means for transmitting the output of the information changing means to the downstream side. And the terminal device. 11. The information changing means deletes information generated by another terminal adjacent to the downstream side from the communication data received by the receiving means, and an output of the deleting means of the own terminal. 11. The terminal device according to claim 10, further comprising an information adding unit that adds generated information. 12. The means for replacing the portion of the communication data received by the receiving means, which contains information generated by another terminal adjacent to the downstream side, with the generated information of the own terminal, in the information changing means. The terminal device according to claim 10, wherein 13. The communication data has a multiplexed frame structure in which information generated by the own terminal and another terminal is multiplexed, and the information changing unit is information generated by another terminal adjacent to a downstream side. 11. The terminal device according to claim 10, wherein the occurrence information of the own terminal is added to the data area accommodating the. 14. The terminal device according to claim 13, wherein the multiplexed frame structure includes information for identifying a terminal that has supplied data in each data area. 15. The terminal device according to claim 10, wherein the communication data includes image data for TV conference and audio.