JP2746084B2 - Conference equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conference apparatus, and more particularly to a conference apparatus.
The present invention relates to a multipoint audio conference device using a line type line.

[0002]

2. Description of the Related Art A schematic block diagram of a conventional voice conference apparatus is shown in FIG. 3, which shows a configuration of only one subscriber point. In the figure, a hybrid circuit 31 converts a two-wire system 36 into a four-wire system, and its transmission output (two-wire system) 37 and reception input (two-wire system) 38 both use echo cancelers 32 and 33. A speaker 34 and a microphone 35 are connected to the speaker 34 and the microphone 35, respectively.

The echo canceller 32 is for canceling the echo (line echo) reflected by the hybrid circuit 31, and the echo canceller 33 is for a speaker 34.
This cancels the echo (room echo) circulating from the microphone to the microphone 35.

[0004]

In this type of voice conference device shown in FIG. 3 [0007] is capable of connection in a point-to-point, thus mutual meeting between two subscribers but has become possible, multi Point-to-point connection is not possible with the configuration of FIG.

[0005] It is an object of the present invention to provide a conference apparatus which enables multipoint connection.

[0006]

According to the present invention, a transmission circuit for deriving a transmission signal generated from a microphone and a reception circuit for guiding a reception signal from a partner device to a speaker are connected to a two-wire system via a hybrid circuit. A conference device connected to a line, wherein the first and second hybrid circuits convert a two-wire line into a four-wire line, respectively, and the transmission signal and the transmission output of the first hybrid circuit. Is added to the first hybrid circuit as a reception input of the second hybrid circuit.
Adding means for adding the transmission outputs of the first and second hybrid circuits and supplying the result to the receiving circuit; and polarity inverting means for inverting the polarity of the transmission signal
And the output of the polarity inversion means and the second hybrid
And the transmission output of the first hybrid circuit.
And a third adding means for receiving a road .

[0007]

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

FIG. 1 is a block diagram of an embodiment of the present invention, and is a block diagram showing an example of a three-point connection between subscribers 1 to 3.

The subscriber 1 is provided with two hybrid circuits 11 and 12 for 2-wire / 4-wire conversion, and the exchange 4 has two hybrid circuits 41 and 12 for 2-wire / 4-wire conversion. 42 are provided. The four hybrid circuits 11, 12, 41, and 42 form a so-called bridge connection configuration.

[0010] The four-wire circuit converted by the hybrid circuit 41 is converted into a two-wire system again by the hybrid circuit 51 of the converter 5 corresponding to the subscriber 2 and connected to the subscriber 2 side.

The four-wire circuit converted by the hybrid circuit 42 is converted into a two-wire system again by the hybrid circuit 61 of the exchange 6 corresponding to the subscriber 3, and
Connected to the side.

In the subscriber 1, a transmission signal generated from the microphone 20 (generated by a transmission circuit,
(Not shown) is added to the two-wire transmission output of the hybrid circuit 11 in the adder 14 to become a two-wire reception input of the hybrid circuit 12.

The two-wire transmission outputs of the hybrid circuits 11 and 12 are added by an adder 13, and the added output is supplied to a speaker 19 via a reception circuit (not shown).

Further, the transmission signal from the microphone 20 is inverted in polarity by the inverter 16, added to the transmission output from the hybrid circuit 12 in the adder 15, and becomes the reception output of the hybrid circuit 11.

Reference numeral 17 denotes an echo canceller for canceling line echo, and reference numeral 18 denotes an echo canceller for canceling room echo.

In such a configuration, the microphone 20
There are two types of echoes E1 and E2 due to the transmission signal from the E1. The echo E1 is generated by the reflection of the transmission signal in the hybrid circuit 11, and the echo E1
2 is caused by reflection of the signal in the hybrid circuit 12.

If these two hybrid circuits (hybrid transformers) are composed of transformers having equivalent characteristics, the echoes E1 and E2 generated by the transformers 11 and 12 can be regarded as substantially equal.

Therefore, in the present embodiment, the polarity of the transmission signal from the microphone 20 is inverted by the inverter 16 and applied to the adder 15 so that the echo E1 and the echo E2 have opposite polarities. They try to negate it.

In the present embodiment, the polarity of the transmission signal is inverted by providing an inverter 16 at a stage preceding the reception input to the hybrid circuit 11, but the inverter is provided anywhere on the path (broken line) of the echo E1. Alternatively, instead of providing an inverter on the path of the echo E1, it may be provided on the path of the echo E2. In short, both echoes E1,
It is only necessary to cancel E2.

FIG. 2 is a block diagram showing another embodiment of the present invention, and the same parts as those in FIG. 1 are denoted by the same reference numerals.
FIG. 2 shows a specific embodiment of the subscriber 1 in FIG. 1 and is assumed to be connected to the subscribers 3 and 2 by hybrid circuits 11 and 12, respectively.

In this example, for level compensation of each signal,
The amplifier 21 amplifies the transmission output of the hybrid circuit 12, the amplifier 22 amplifies the transmission output of the hybrid circuit 11, and the amplifier 23 amplifies the transmission signal from the microphone 20. .

The amplifier 22 compensates for the attenuation when the signal from the subscriber 3 passes through the hybrid circuits 11 and 12 twice. The amplifiers 21 and 23 make the echo levels of the transmission signals equal to E1 and E2. It is for doing.

In the above embodiment, an example of a three-point conference of the subscribers 1 to 3 has been described. However, by forming a bridge circuit in the subscriber 2 in the same manner as the subscriber 1, the other fourth point (subscriber) who 4 connected to) becomes possible, multi in a similar manner
So that the point can be realized.

[0024]

As described above, according to the present invention, a multi-site
Employment of a bridge structure that enables point connection makes it possible to remove echoes, increases the tolerance to howling, and has the effect of simplifying the line-side echo canceller.

[Brief description of the drawings]

FIG. 1 is a block diagram of one embodiment of the present invention.

FIG. 2 is a block diagram of another embodiment of the present invention.

FIG. 3 is a block diagram of a conventional conference device.

[Explanation of symbols]

 1-3 Subscriber 11,12 Hybrid circuit 13-15 Adder 16 Inverter 17,18 Echo canceller 19 Speaker 20 Microphone 21-23 Amplifier

Claims (5)

(57) [Claims] A conference apparatus in which a transmission circuit for deriving a transmission signal generated from a microphone and a reception circuit for guiding a reception signal from a partner apparatus to a speaker are connected to a two-wire circuit via a hybrid circuit. A first and a second hybrid circuit for converting a two-wire circuit into a four-wire circuit, respectively; and adding the transmission signal and the transmission output of the first hybrid circuit to the second hybrid circuit. A first adding means for receiving the input signal, a second adding means for adding both transmission outputs of the first and second hybrid circuits and supplying the result to the receiving circuit, and inverting the polarity of the transmission signal. Polarity inversion means, output of the polarity inversion means, and the second hybrid circuit
And the transmission output of the first hybrid circuit.
And a third adding means for receiving input . 2. The conference apparatus according to claim 1, further comprising amplifying means for amplifying the transmission signal and supplying the amplified signal to the first and third adding means. 3. The conference apparatus according to claim 1, further comprising an amplification unit that amplifies a transmission output of the first hybrid circuit and supplies the amplified output to the first addition unit. 4. The conference apparatus according to claim 1, further comprising an amplifying means for amplifying a transmission output of said second hybrid circuit and supplying the amplified output to said third adding means. 5. The method according to claim 1, further comprising referring to a received signal to said speaker.
The echo component contained in the transmitted signal is removed and the room echo is removed.
Means for canceling, and referring to the transmission signal,
Line echo in the first and second hybrid circuits
2. The method according to claim 1, further comprising: canceling means.
5. The conference device according to any one of items 1 to 4.