JP2588896B2 - Audio conference equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention realizes a high quality conference call, instead of using a single analog telephone line for a conference call.
A loudspeaker system consisting of a speaker receiving system and a microphone transmitting system for the two lines is automatically installed in order to eliminate the influence of side tone coupling by performing a loudspeaker call using two analog subscriber lines and to realize the two-line conference call. The present invention relates to a loudspeaker conference device which can be connected to a public telephone.

[Conventional technology]

Conventionally, in a voice conference in which a telephone conversation is performed using a microphone / speaker, a loudspeaker having a configuration as shown in FIG. 4 is used, and a telephone conversation is performed using one analog telephone line, or as shown in FIG. A conference call was realized by using the configured voice conference apparatus using four transmission / reception lines via a dedicated line or the like.

In these figures, 1 is a microphone, 2 is a microphone amplifier, 3 is a voice switch circuit, which is composed of voice insertion loss circuits 31, 32 and a voice switch loss control circuit 33. 4 is a soundproofing circuit, 5 is a PB signal generation circuit, 6 is an amplifier for a speaker, 7 is a speaker, 8 is a telephone line connection terminal,
9 is a transmission line connection terminal, and 10 is a reception line connection terminal.

The operation is as follows. After the voice switch loss control circuit 33 compares the magnitude of the transmission input signal from the microphone 1 with the magnitude of the reception input signal from the telephone line connection terminal 8 or the reception line connection terminal 10, The conference call is realized by controlling the voice insertion loss circuit 31 or 32 to 0 dB and the other to LdB.

The amount of side-tone coupling of a loudspeaker or a voice conference device achieved with a conventional analog line varies greatly depending on the conditions of the line to be connected, and the amount of change reaches as much as 20 dB. For this reason, the voice switch insertion loss used for echo / howling suppression at this time is 50 to 30 dB including acoustic coupling. However, if two analog public telephone lines are used and the transmission and reception lines are electrically separated and connected to each other to eliminate the problem of side-tone coupling, the insertion loss is determined only by the acoustic coupling between the conference devices. The insertion loss
It can be reduced to less than dB, and a high quality conference call can be realized. However, when a two-way analog public telephone line is used for transmitting and receiving calls, it is necessary to determine which of the two lines is to be transmitted and the other is to be received upon agreement with the other party's conference apparatus. That is, at the time of transition to the two-line audio communication conference mode after the two-line conference button is pressed, the own transmitting side is not connected to the other party's transmitting line and the own receiving side is not connected to the other party's receiving side between the audio conference devices. It is necessary to correctly connect one public telephone line for transmission only and the other public telephone line for reception only. Must be intervened, and it is necessary to make a decision as to which is to be transmitted or received.

[Problems to be solved by the invention]

As described above, in the case of the loudspeaker shown in FIG. 4, the audio switch circuit 3 is used to cut off the loop path between the acoustic coupling path of the speaker / microphone and the side tone path generated in the telephone and to prevent howling. Therefore, the first disadvantage is that
Since a large amount of loss due to the voice switch circuit 3 needs to be inserted into the communication path for transmission or reception, a problem arises in that the communication voice is easily cut off.

The second drawback is that the voice conference apparatus of FIG. 5, which is free from the problem of the side tone path, can realize a relatively high-performance call because both the loss amount and fluctuation of the transmission path are small. It is difficult to prepare easily, and the trouble of the line carrier is troubled. Also, there is a drawback that the dedicated line is not widely used so that it can be used anywhere.

Also, in a system using an external device such as a facsimile, a signal is transmitted to a line, but this uses only one line and only determines whether the device is transmitting or receiving. is there.

The voice switch will be described. The voice switch compares the level of a transmission signal input to a microphone with the level of a reception signal (partner voice) input from a telephone line,
Set the loss amount of the insertion loss circuit of the larger one to 0
(Zero, no), and performs an operation to increase the loss amount of the insertion loss circuit inserted into the other communication path. For example, it is connected to one telephone line as shown in FIG. In the case of a loudspeaker with a single microphone, the other party's voice radiated from the loudspeaker is also collected and amplified by the microphone and sent out to the telephone line, and at the same time, a part of the transmission signal is a protection sound. Since the sound signal leaks to the receiving circuit through the circuit, the audio signal forms a loop of the receiving amplifier, speaker, microphone, amplifier, and soundproofing circuit, and oscillates (this is called howling). In order to prevent this, a loss is inserted into a transmission path or a reception path, and one of the communication paths is blocked.

As will be described later, the voice switch of the present invention uses two telephone lines, and connects a transmission signal to one telephone line and a reception signal to the other telephone line, so that the soundproofing circuit in the side protection circuit can be used. Elimination of the transmission voice signal has been eliminated.
However, in this case, the transmission signal is amplified and sent out to the telephone line, amplified by the other party's receiving amplifier, radiated from the speaker, and listened to. At this time, the radiated sound is collected by the other party's microphone, and then transmitted to the line via the amplifier. This causes a phenomenon in which the user's voice is transmitted and returned again, and further, howling occurs due to a one-circle loop (called a far-end howling group) in which the sound is radiated from the speaker to the microphone. Therefore, a voice switch is required even when transmission and reception are connected using separate telephone lines.

An object of the present invention is to eliminate the influence of the side tone coupling path by using two widely used analog public telephone lines and to make the configuration equivalent to using two dedicated lines, thereby achieving high-quality voice communication. It is to easily realize and provide a call.

[Means for solving the problem]

An audio conference device according to the present invention includes a microphone system including a plurality of microphones and a microphone amplifier;
A speaker system including at least one speaker and a speaker amplifier is compared with an output signal level of the microphone amplifier and a reception signal level input from an analog public telephone line, and inserted into one of the communication paths having a higher level. A two-line analog public line composed of a voice switch circuit for reducing the amount of loss to zero and increasing the amount of loss for the other communication path, and transmitting one of the two lines to which the plurality of microphone-system outputs are connected. A voice conference device which is a reception line for connecting the other line as a reception input signal to a speaker system input side, wherein each of the two lines is provided with an AC signal generation / recognition device for establishing a transmission / reception path, and sequentially for each line. After performing outgoing or incoming operation and closing the communication path, the two-line conference button is pressed to shift to the two-line voice communication conference mode. When a reference signal is generated from the transmission / reception path establishment AC signal generation / recognition device, the reference signal generated and transmitted from the partner transmission / reception path establishment AC signal generation / recognition device is transmitted to the transmission / reception path establishment AC signal. According to a control circuit for causing the generation / recognition device to recognize, and a reference signal identification result of the AC signal generation / recognition device for establishing a transmission / reception path, the own microphone system is connected to the other speaker system, and the other microphone system is connected to the own speaker system, and a call is made. And a transmission / reception line connection switching relay for connecting the road in the forward direction.

The microphone system refers to a plurality of microphones, an amplifier to which these microphone outputs are connected, and an insertion loss circuit of a voice switch circuit inserted into a transmission path. The speaker system refers to a partner voice signal input from a telephone line. , An insertion loss circuit of an audio switch circuit, a speaker amplifier, and at least one speaker that cause a loss to the speaker.

[Operation] In the present invention, a reference signal generated from an AC signal generation / recognition device for establishing a transmission / reception path previously mounted on each audio conference device is transmitted to an analog telephone line, and a reference signal transmitted from one telephone line is transmitted. Is received and identified by the recognition device, and both of them are connected in the forward direction in a predetermined direction to determine which of the two lines is the transmission line and the other is the reception line.

〔Example〕

FIG. 1 is a block diagram showing one embodiment of the present invention,
13 is a transmission / reception line connection switching relay circuit, 41 and 42 are line termination circuits for transmission / reception at the time of a two-line conference, 14 is a connection switching relay of an AC signal generation / recognition device for transmission / reception path establishment,
Reference numeral 43 denotes a line terminating circuit for connecting a transmission / reception path establishment AC signal generation / recognition device, reference numeral 11 denotes a transmission / reception path establishment AC signal generation / recognition device, reference numeral 12 denotes a control circuit, and the other components are the same as those in FIG. The audio conference apparatus according to the present invention is composed of the above-described units and is used by connecting to an analog telephone line.

FIG. 2 shows the transmission / reception establishment in which the transmitting / receiving path establishing / recognition apparatus 11 of FIG. 1 and the transmission / reception communication path to be connected are determined by the signals transmitted / received by this circuit. It is a time chart.

 First, the outline of the present invention will be described.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for realizing a loudspeaker conference call using two telephone lines. The method of using the two lines is a microphone system (or a transmission system) comprising a plurality of microphones, an amplifier, and a transmission line insertion loss circuit. System) is connected to one of the two telephone lines, and the speaker system (or the receiving system) including the receiving path insertion loss circuit, the receiving amplifier, and the speaker is connected to the other of the two telephone lines. To do so, the microphone system must declare to the other party that it is a microphone system. Furthermore, it is necessary to recognize that the other party is a microphone system and connect to a speaker system. This routine first dials the other party over a single line, connects and talks with the other party to confirm the other party. (In this case, both parties are talking on one line.) Next, the line is put on hold.

Dial the other party with another line, connect one line in the same way, and confirm the other party by conversation.

The two-line conference button is pressed in a state where the above and.

When this button is pressed, the line connected to the holding circuit and held is connected to the transmission / reception path establishing AC signal generation / recognition device provided as the third means.

The transmission / reception path establishing AC signal generation / recognition device transmits a predetermined signal (referred to here as a reference signal). On the other hand, if the other party receives the reference signal, it is determined that "the received line is connected to the speaker system". The sending side
Connect the transmitted line to the microphone system. By this operation, the other party declares to the other party that "it is a microphone system", the other party receives the reference signal, determines that the connection destination is the microphone system, connects to the speaker system, and A communication path is established.

Next, the same operation is performed on the other party, and the other communication path is completed.

Here, the reference signal is used to connect the microphone system to the reference signal sending line and to connect the reference signal receiving line to the speaker system. The reference signal itself may be anything as long as it is mutually agreed in advance. However, in order to prevent malfunctions with other devices, a device is added here.

The reference signal may be sent to either of the two lines.
However, the transmission line is stored in the apparatus and connected to the microphone system without fail. This is all stored in the control device used in the device, and appears only in the relay switch circuit diagram on the hardware configuration.

The crossing configuration is realized by a relay switch circuit, and the information confirming the partner by the AC signal generation / recognition device for establishing the transmission / reception path is transmitted to the 12 control circuits, where it is judged and controlled so that the relay switch is crossed. I do. These are all implemented by software.

In FIG. 1, when the microphone-based one-way communication path is determined, the other one-way communication path is determined to be the speaker system by itself, so that the microphone-based relay contact of the transmission / reception line connection switching relay 13 is closed upward. As shown in the figure, the relay contact of the speaker system is closed at the lower side to realize a two-line voice communication conference.

Regarding the relationship between the establishment AC signal generation and the reference signal, in order to establish the communication one-way communication path by transmission and reception,
Transmit reference signals to each other. An AC signal generating / recognizing device for establishing a transmission / reception path generates a reference signal for this purpose.

Next, the operation will be described with reference to FIGS. At the time of a two-line conference call, after realizing a one-line conference call state for each line, the user presses a button for shifting to the two-line conference mode. , Not shown). Line terminating circuits 41 and 42 are connected to the respective connection terminals 9 and 10, which hold the intra-office relay and control circuit by pressing the two-line conference button.
An AC signal generating / recognizing device 11 for establishing a transmission / reception path is connected to an analog telephone line on the transmission line connection terminal 9 side via a connection switching relay 14 controlled by 12, while the reception line connection terminal 10 is connected.
A line termination circuit 42 is connected to the analog telephone line on the side (state shown in FIG. 1).

Under the control of the control circuit 12, an AC signal is transmitted from the transmission / reception establishment AC signal generation / recognition device 11 through the transmission line connection terminal 9 at random according to a time chart as shown in FIG. Also, the transmission / reception path establishing AC signal generation / recognition device 11 is connected to the transmission line connection terminal 9 at a random time, so that the AC signal of the partner device transmitted via the line can be received.

Such an operation is also performed alternately on the reception line connection terminal 10, and transmission / reception is repeated several times with respect to the two lines, and the other party's device is the same model, and one is transmitted (or received) and the other is received ( The transmission is continued within a fixed time until the control circuit 12 confirms the transmission (this is called negotiation). As a result, when confirmed, one is determined as a transmission path and the other as a reception path according to a predetermined format, and a microphone system is connected to the transmission path side, and a speaker system is connected to the reception path side, and an audio switch circuit for audio conference is connected. 3 to enable a conference call, and to generate an AC signal
The recognition device 11 is disconnected from the connection terminals 9 and 10.

After the two-line conference call is established by negotiation, for example, the transmission voice collected by the microphone 1 is transmitted to the amplifier 2,
The signal is transmitted to the analog telephone line via the voice switch circuit 3, the line termination circuit 41 for the two-line conference, and the transmission line connection terminal 9. On the other hand, the received audio signal is input from the reception line connection terminal 10 and is received via the line termination circuit 42, the audio switch circuit 3, the amplifier 6, and the speaker 7.

By operating in such a configuration, one-line conference call connection is sequentially connected to each of the analog telephone lines, and then, simply by pressing the two-line conference call button, a two-line conference call can be easily realized, Further, the problem that the voice switch insertion loss due to the side tone coupling in the voice conference call using one analog telephone line increases can be easily eliminated.

As a result, the amount of insertion loss of the voice switch circuit determined by both the acoustic coupling and the sidetone coupling of the speaker / microphone during a one-line conference call is increased from the large value. This has the advantage that the insertion loss can be reduced by only the acoustic coupling path.

It is also necessary to prepare a special device for signal generation by diverting the PB signal generation circuit already installed by the audio conferencing device for the other party connection to the AC signal generation / recognition device 11 for establishing the negotiation transmission / reception path. It can be realized economically and compactly without any. Further, a PB signal receiving circuit designed and manufactured for receiving a PB signal can also be used for the AC signal generating / recognizing device 11 for establishing a transmission / reception path.

FIG. 3 shows a case where the present invention shown in FIG. 1 is used to shift to a mode of transmitting and receiving to and from the other party by using an external device such as a facsimile during a two-line conference, and to shift to a two-line conference call mode. Based on the result of the negotiation between the two conference devices, the control circuit 12 connects one of the analog telephone lines to the voice communication circuit and the other analog telephone line to the external device in a predetermined order. For example, after the transition from the two-line conference call to the one-line conference call, the microphone 1, the speaker 7, and the voice switch circuit 3 are connected to the protection sound circuit 4 via the relay circuit 16, and then the transmission line is connected via the line switching relay 17. Connected to terminal 9. On the other hand, the receiving line connection terminal
Reference numeral 10 is connected to an external device 15 such as a facsimile via a line switching relay 18. Also, since the control circuit 12 stores which line was transmitted and the other was received during a two-line conference call, immediately after the use of the external device, the original operation is performed by the reverse operation as described above. Return to line conference call mode.

By the above operation, when it is necessary to perform transmission / reception using the external device 15 such as a facsimile connected to the audio conference device during the two-line audio conference with the other party, simply press the external device interrupt button. Thus, the two-line conference communication mode is immediately switched to the one-line loudspeaker communication, and the voice signal can be connected to the telephone line via the transmission line connection terminal 9 and the external device 15 such as a facsimile can be connected to another telephone line.

As an effect, when it becomes necessary to send materials or the like to the other party during the two-line conference, the materials can be sent from the external device to the other party in parallel with the call without interrupting the loudspeaker call. Furthermore, after using the external device, the system immediately returns to the two-line conference call mode, so that a high-quality audio conference is performed again.

Further, a push-button dial signal generator, which is widely used in public telephone networks and telephones for an AC signal generation / recognition device 11 for establishing a transmission / reception path and is also mounted on a voice conference device for line connection, is part of the device. The size of the device can be reduced by using a push-button dial signal receiver.
Economy can be achieved. Further, by setting the signal transmission timing and the reception timing from the set of transmission / reception path establishing AC signal generation / recognition device 11 to the line to be a random cycle, the signal transmission status between the two audio conference devices, or the reception status, When one is in a signal transmission state, the other always has a timing to be in a reception state, the transmission and reception paths of both lines are surely established, and the occurrence of malfunctions due to crosstalk in public lines is reduced. can do.

When a one-line conference is temporarily held, it is very troublesome because the user determines which of the two lines is to be performed. It is possible to automatically select a line according to a predetermined procedure without considering whether to use the line.

The necessity of using two lines in the present invention is to completely separate the transmission path and the reception path in order to improve the communication quality of the voice communication conference.

The necessity of separating transmission and reception in the present invention is to realize the above means (using two lines) in order to eliminate a path in which a transmission signal goes around a reception circuit.

The reason why the present invention must be divided into transmission and reception is
A voice conference communication device including a loudspeaker using a microphone and a speaker is a side sound path (referred to as a side sound coupling) in which sound goes from a speaker to a microphone (referred to as acoustic coupling) and a transmission signal is transmitted to a receiving circuit. There is a problem that a loop is formed, and oscillation (oscillation development is called howling, especially oscillation caused by both acoustic and side-tone coupling is called near-end howling). Therefore, the problem of the near-end howling is solved by adopting different communication lines for the transmission and reception paths.

The advantage of dividing into transmission and reception according to the present invention is that, in general, in a loudspeaker phone or a voice conference device, in order to prevent howling caused by the acoustic coupling and the sidetone coupling, a voice switch is used according to the transmission / reception signal level. A method of inserting a loss into one of the transmission and reception channels has been adopted for a long time. This method has an advantage that it can be realized relatively inexpensively.
However, the incoming and outgoing voice signals are detected, the levels are compared and judged, and based on the result, the loss in the transmitting and receiving speech path is inserted, inserted, stripped or removed, so that the loss is eventually inserted. -There is a time delay before removal, and there is a problem that the audio signal is cut off only during this delay. In audio conferencing communication in which multiple people participate, there is also a problem that even when the other party is talking, the voice switch is activated by the coughing of people at this site or the sound of turning over materials, and the received voice is interrupted . These are similar to activating the mute function while watching TV, causing the sound to be interrupted, causing a situation in which it is not clear what is going on. The insertion loss of a voice switch reaches 50 to 30 dB in a two-line conference. To improve this, it is necessary to reduce the absolute amount of voice switch insertion loss. For this purpose, it is necessary to reduce the degree of acoustic coupling and lateral sound joining that determine the absolute amount of insertion loss.

Acoustic coupling can be considerably improved by devising the arrangement of microphones and speakers and using a directional microphone, but sidetone coupling varies depending on the impedance of the telephone line to be connected (for example, due to dialing). When the handset is picked up, the impedance of the dial tone transmitter of the station, then the dialing circuit is disconnected from the telephone line, so that the impedance becomes infinite,
Finally, when connected to the other party, it becomes impedance including the other party's line / telephone. In addition, this impedance changes depending on the connected party.)

〔The invention's effect〕

As described above, the present invention provides a microphone system including a plurality of microphones and a microphone amplifier, a speaker system including at least one speaker and a speaker amplifier, an output signal level of the microphone amplifier, and an input from an analog public telephone line. An analog public line composed of a voice switch circuit that compares the magnitude of the received signal level to be received, makes the loss amount inserted into one of the communication paths having a higher level zero, and increases the loss amount of the other communication path. An audio conference device using two lines, one of the two lines being a transmission line to which the plurality of microphone output sides are connected, and the other being a reception line for connecting to the speaker input side as a reception input signal. Each line is equipped with an AC signal generation / recognition device for establishing transmission / reception paths. After performing the receiving operation and closing each communication path, when the two-line conference button is pressed to shift to the two-line voice communication conference mode, the reference signal is generated from the transmission / reception path establishment AC signal generation / recognition device. A control circuit for recognizing a reference signal generated and transmitted from a transmission / reception path establishment AC signal generation / recognition apparatus by the transmission / reception path establishment AC signal generation / recognition apparatus; and a transmission / reception path establishment AC signal generation / recognition apparatus. According to the identification result of the reference signal of the device, since the own microphone system is connected to the other speaker system, the other microphone system is connected to the own speaker system, and the transmission / reception line connection switching relay connects the communication path in the forward direction, the telephone line is connected. When realizing a high-quality loudspeaker conference call using a line, operate a negotiation to determine which is to transmit conference audio and the other is to receive conference audio. Since it automatically determined without troubling the, it can realize high-quality conference call with a simple configuration. If a PB signal generation / reception circuit is used for the negotiation signal, the above function can be realized economically and in a small size. Furthermore, even when it is necessary to interrupt an external device, such as a facsimile, during a two-line conference call, there is no need to interrupt the conference call, and the operation is as simple as using an external device. In addition, since the result of the negotiation is stored in the audio conference device after the use of the external device, it can be easily and immediately recovered.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of a voice conference apparatus according to the present invention, FIG. 2 is a timing chart of a signal for establishing a transmission / reception path of the voice conference apparatus according to the present invention, and FIG. FIG. 4 is a block diagram showing a configuration of a conventional loudspeaker, and FIG. 5 is a block diagram showing a configuration of a conventional voice conference device. . In the figure, 1 is a microphone of a loudspeaker, 2 is an amplifier for a microphone of a loudspeaker, 3 is a voice switch circuit, 4
Is a soundproofing circuit, 5 is a PB signal generation circuit, 6 is a speaker amplifier, 7 is a speaker, 8 is a telephone line connection terminal, 9 is a transmission line connection terminal, 10 is a reception line connection terminal, and 11 is a transmission / reception path establishment. 12 is a control circuit, 13 is a transmission / reception line connection switching relay circuit of a voice conference device controlled by the control circuit 12, and 14 is a transmission / reception path establishment AC signal generation / reception controlled by the control circuit 12. Reference numerals 41, 42, and 43 denote line termination circuits for transmission and reception during a two-line conference, reference numeral 15 denotes an external device, reference numeral 16 denotes a relay circuit, and reference numerals 17 and 18 denote line switching relays.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Mizuhiro Tobita 1-2356 Take, Yokosuka City Nippon Telegraph and Telephone Corporation Inside the Combined Communications Research Laboratories (72) Inventor Hiroaki Nomura 1-2356 Take, Yokosuka City Nippon Telegraph and Telephone (72) Inventor: Kazuyuki Watanabe 1-7-41 Kugayama, Suginami-ku, Tokyo Iwasaki Communication Equipment Co., Ltd. (72) Yosuke Hiromi 1-7-141, Kugayama, Suginami-ku, Tokyo Iwasaki Saki Communication Equipment Co., Ltd.

Claims (4)

(57) [Claims] 1. A microphone system comprising a plurality of microphones and a microphone amplifier, a speaker system comprising at least one speaker and a speaker amplifier, an output signal level of the microphone amplifier and a reception signal level inputted from an analog public telephone line. Using two analog public lines composed of a voice switch circuit that reduces the amount of loss to be inserted into one of the channels with a larger level to zero and the amount of loss in the other channel to be larger. ,
In a voice conference device, one of the two lines is a transmission line to which the plurality of microphone-system outputs are connected, and the other is a reception line to be connected to a speaker-system input as a reception input signal. AC signal generation for path establishment
A recognition device is provided, and after performing a calling or receiving operation sequentially for each line and closing each communication path, when the two-line conference button is pressed to shift to a two-line voice communication conference mode, the transmission / reception path establishing AC is established. A control circuit for generating a reference signal from a signal generation / recognition device and for recognizing the reference signal generated and transmitted from the transmission / reception channel establishment AC signal generation / recognition device of the other party by the transmission / reception channel establishment AC signal generation / recognition device. A transmission / reception line that connects the own microphone system to the other speaker system, connects the other microphone system to the own speaker system, and connects the communication path in the forward direction, based on the reference signal identification result of the transmission / reception path establishing AC signal generation / recognition device. An audio conference device comprising a connection switching relay. 2. A voice conference apparatus according to claim 1, wherein said push-button dial signal generator and said receiver are used for an AC signal generation / recognition apparatus for establishing a transmission / reception path. 3. An audio conference apparatus includes a set of AC signal generating / recognizing devices for establishing a transmission / reception path, randomly performing timing and intervals of AC signal generation, and generating / recognizing the AC signal for establishing a transmission / reception path. The audio conference apparatus according to claim 1 or 2, wherein a cycle of connection of the apparatus to each line is alternately performed. 4. After the transmission / reception path is established, the line information is stored, and when the mode temporarily shifts to the one-line conference mode and then returns to the two-line conference mode, the communication path is immediately forwarded by the preceding information. The audio conference apparatus according to claim 1 or 2, wherein the audio conference apparatus operates so as to be connected to a telephone.