JPS61112461A - Voice document confference system - Google Patents

Abstract

PURPOSE:To prevent noise generated at the time of switching in a voice document conference system that switches voice picture multiple signals and picture signals by muting the voice signal path. CONSTITUTION:A center node 2 is provided for terminal units 1a-1n, and the center node 2 is made up of a terminal corresponding sections 10a-20n, a controlling device 21 and a circuit connecting device 22. The terminal corre sponding section 20 includes a circuit that demultiplexes 31 and multiplexes 34, 38 signals consisting of voice of 7-bit and picture of 1-bit or controlling signal, or picture of 7-bit and controlling signal of 1-bit and a buffer 39 of controlling signal of 1-bit etc., and when request for switching of a communica tion mode is detected by the controlling signal, a signal of no sound generation is selected to prevent generation of noise at the time of switching.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an audio document conference system in which a plurality of terminal devices communicate by temporally switching between an audio image multiplex signal and an image signal via a center node.

Configuration of conventional example and its problems In this type of audio document conference system, (a
) and (bl), in mode 1, communication using a 7-bit image signal and a 1-bit control signal occurs, and in mode 2, communication using a 7-bit audio signal and a 1-bit image signal or control signal communicates with the center node. Switching of the communication mode between mode 1 and mode 2 is performed within each terminal device by a command from the center node that has received the request from the terminal device. ing.

In the above-mentioned conventional audio document conference system, mode 1 and mode 2 coexist between terminal devices for a short time because there is some time lag in switching the communication mode in each terminal device.
There was a problem in that the image signal was not output to the speaker of the terminal device in mode 2, causing unpleasant noise.

OBJECTS OF THE INVENTION It is an object of the present invention to eliminate the drawbacks of the conventional example described above and to prevent image signals from leaking to the speaker of a terminal device when switching the communication mode from mode 2 to mode 1.

Structure of the Invention In order to achieve the above object, the present invention provides that, when a center node receives a request from any terminal device to switch the communication mode from mode 2 to mode 1, audio signals are transmitted from all terminal devices. After confirming that the communication mode has not been transmitted, a command to switch the communication mode from mode 2 to mode 1 is issued to all terminal devices, and until a response to this communication mode switching command is received from all terminal devices, the communication mode within the center node is Configured to mute all audio signal paths.

DESCRIPTION OF EMBODIMENTS The present invention will now be described by way of an embodiment with reference to the drawings.

FIG. 1 is a diagram showing the configuration of an embodiment of the audio document conference system of the present invention. In the same figure, la, l
b, . . . 1n are terminal devices, 2 is a center node, 20a, 20b, . Terminal devices 1a, 1. b,...In and terminal correspondence section 2Qa
, 20b, . . . 20n are each connected to the line termination device DCE via a full-duplex communication line. Each of the terminal corresponding parts 20a, 20b, .
．． A silence generation circuit 37 and a buffer circuit 39 are provided.

The data received from the terminal device 1a is converted into 7-pin image signals or audio signals Do to D by the demultiplexing circuit 31.
It is separated into a 1-bit image signal or control signal D7. 7
The bit image signal or audio signal Do-, -D is output onto the signal line 32, passes through the selection circuit 33, and is sent to the multiplexing circuit 3.
4. On the other hand, the 1-bit image signal or control signal Dγ is temporarily stored in the buffer circuit 39. When the signal D7 having a predetermined number of bits accumulated in the buffer circuit 39 is an image signal, this image signal D? is supplied one bit at a time to the multiplexing circuit 34 via the signal line 35, multiplexed with the audio signal, and then supplied to the line connection device 22. On the other hand, if the predetermined number of bits accumulated in the buffer circuit 39 is a control signal, it is taken into the control device 21.

To switch the communication mode between mode 2 and mode 1, each terminal device sends a communication mode switching request to the center node 2, and the control device 21 of the center node 2 receives the request.
is performed within each terminal device by issuing a communication mode switching command to each terminal device.

Now, in the case of mode 2, the terminal device 1a is in mode 1.
The communication mode switching control of the control device 21 at this time will be explained with reference to the flowchart of FIG. 3.

When the control device 21 receives the request for switching to mode 1 sent by the terminal device 1a from the buffer circuit 39, the control device 21 first proceeds to step 42, where it activates audio mute. Activation of this audio mute is performed by activating the silence generation circuit 37 in each circuit corresponding section 20a to 20n, selecting its output by the selection circuit 33, and supplying it to the multiplexing circuit 34.

Next, in step 43, the control device 21 sends the mode switching command to each of the terminal devices 1a to 1n by supplying the mode switching command to the multiplexing circuit 38 in each circuit corresponding section 20a to 20n. In the next step 44, the control device 2 waits until it receives a response to the mode switching command from one of the terminal devices, and then proceeds to step 45. In step 45, the control device 21 receives the responses from all the terminal devices (determines whether the response is 7 or not. The control device 2) repeats steps 44 and 45 until it receives the responses from all the terminal devices. When the control device 21 confirms the reception of responses from all the terminal devices, it proceeds to step 46, switches the selection circuit 33 in each circuit corresponding section 20a to 20n, cancels the audio mute, and changes from mode 2 to mode] Finish switching the communication mode to .

Effects of the Invention As explained above, the present invention provides mode IK from mode 2.
When switching, the configuration is such that all audio signal paths within the center node are met until responses to the communication mode switching command are received from all terminal devices, so image signals may leak into the speakers of the terminal devices, causing discomfort. This has the effect of effectively preventing the problem of generating abnormal noise.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention, FIG. 2 is a diagram showing the signal format of the audio document conference system, and FIG. 3 is a flowchart for explaining the audio meeting operation. 1a to 1n... terminal device, 2... center node, 20a to 20n... terminal corresponding section, 21... control device, 22... line connection device, 31... multiplexing/demultiplexing circuit, 33;・Selection circuit, 34.38...Multiplexing circuit, 3
7... Silence generation circuit, 39... Buffer circuit. Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
Figure 7 - Do 1 Rent 1 G - Do 2 Mochikoma Semiyo y Chiku 3 figure

Claims (1)

[Claims] A plurality of terminal devices communicate via a center node by temporally switching between an audio image multiplex signal and an image signal, and the center node switches the communication mode from the audio image multiplex signal to the image signal. When a request is received from any terminal device, it issues a command to all terminal devices to switch the communication mode from an audio image multiplex signal to an image signal, and waits until a response to this communication mode switching command is received from all terminal devices. An audio document conference system characterized in that all audio signal paths within the center node are muted.