JPH03289252A - Telephone conference equipment - Google Patents

Abstract

PURPOSE:To allow individual talking with a specific conference participant and to prevent the content of the conference from being intercepted by a specific participant by applying mute control to an output channel corresponding to plural output channels when a detection means and an identification means detect the reception of an audible tone. CONSTITUTION:When a input signal detection circuit 7 outputs input signal absence information from its own line, an input signal display device 11 of a relevant line displays the state of absence of the input signal independently of the output information from an audible tone identification circuit 8. When the input signal detection circuit 7 outputs the information representing the presence of the input signal from its own line and the output information from the audible tone identification circuit 8 is audible tone detection information, the input signal display device 11 of the relevant line displays the audible tone reception state to bring the output channel mute circuit 9 into the mute state (channel interruption). Thus, individual talking is attained with a specific conference participant during conference and the intercept of the content of conference is inhibited to the specific conference participant.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Field of Industrial Application to which the Invention Pertains The present invention relates to a telephone conference device that connects a plurality of telephones via a communication line and conducts a conference call between multiple points.

(2) Conventional technology and its problems When making conference calls between multiple points by connecting communication lines,
A commonly used method is the so-called (N-1) addition method, in which input signals from lines other than the own line are added to each conference participant and sent back. FIG. 7 shows a block diagram of a conference call circuit using the (N-1) addition method. In the figure, 1 is an audio input/output terminal connected to a line for contacting conference participants, 2 is a 2-wire to 4-wire conversion circuit, 3 is a subtraction circuit, 4 is an input communication path, 5 is an output communication path, and 6 is a total signal adder circuit. The input signal input from the communication line is the audio input/output terminal 1.
, 2-wire to 4-wire conversion circuit 2 and input communication path 4, and are added by a total signal addition circuit 6, and a subtraction circuit 3 subtracts the audio signal input from its own line (hereinafter abbreviated as own line) and outputs the result. Communication path 5, 2-wire to 4-wire conversion circuit 2, and audio input/output terminal l
It is output to the communication line via .

In such a conference call circuit, the 2-4 wire conversion circuit 2
Due to the impedance mismatch, leakage signals (echoes) leak from the output communication path 5 to the input communication path 4. Therefore, when the input communication path 4 detects an input signal from the communication line,
Is the detected signal an input signal from your own line, or is it an input signal from another line (hereinafter referred to as other line) to your own line?
I couldn't tell if it was an echo that had gone around.

In addition, the audible sounds output from the exchange (dial tone 2 mid-call tone,
If a voice signal input from another line mixes in as an echo while detecting a ringtone (ringing tone), the audible tone of the own line may not be detected accurately.

Further, in such a conference call circuit, the input signal is output to all lines other than the line to which the input signal is input. Therefore, the audio spoken by a conference participant can be heard by all participants.

Conventionally, with telephone conference devices configured in this way, it has been possible to talk to specific conference participants individually during a conference call, or to prevent specific participants from hearing the content of the conference. There wasn't.

(3) Purpose of the Invention The present invention connects a 2-wire to 4-wire conversion circuit for each communication line to a plurality of connected 2-wire communication lines, and provides means for distributing the 2-wire to 4-wire conversion circuits to each communication line. It is an object of the present invention to provide a telephone conference device that is configured to be connected to the 4-wire side of a line conversion circuit and that an on/off control circuit is inserted on the 4-wire communication path side, thereby solving the drawbacks of the above-mentioned prior art. shall be.

That is, the present invention provides a telephone conference device that can stably detect audible sounds and voice signals input from the own line during a conference call, and when detected, display the detected signals on a display. The purpose is to

Furthermore, the present invention provides a teleconference device that makes it possible to talk to specific conference participants individually during a conference, to prevent specific participants from hearing the content of the conference, or forcibly prohibit them from speaking. The purpose is to

(4) Structure and operation of the invention In order to achieve this object, one of the telephone conference devices of the present invention includes a 2-wire to 4-wire conversion circuit for each communication line for a plurality of connected 2-wire communication lines. By arranging an audio signal addition/distribution means on the 4-wire side of the 2-wire to 4-wire conversion circuit, which adds the audio signals of subscribers input from the communication line and distributes the sum to the communication line again. The device is configured to conduct a conference call between points, and inputs each input signal from the plurality of communication lines to the audio signal addition and distribution means. a detection means for determining whether the input signal is a signal, an identification means for determining whether the input signal is a voice signal, or an audible sound sent from the exchange (dial tone 2 busy tone, ring tone); -4 to 4-wire conversion circuit
a communication line mute means for muting each of a plurality of output calls on the line side; a display means for displaying that the input signal is being input from the communication line; control means for controlling the display of the signal detected by the display means when an input signal (audio signal/audible sound) is detected from the display; The present invention has a configuration characterized in that it includes a control means for controlling a corresponding one of the plurality of output communication paths to a mute state by a mute means.

To achieve this objective, another one of the telephone conference devices according to the present invention is such that a 2-wire to 4-wire conversion circuit is connected to each of the plurality of connected 2-wire communication lines. The voice signal addition/distribution means for adding subscriber voice signals inputted from the 2-4 line and distributing the same to the communication line again is provided.
By connecting to the 4-line side of the line conversion circuit, it is configured to conduct conference calls between multiple points, and in addition to the conference calls between the multiple points, an individual call can be made separately from the communication line. means, a switch circuit for switching between the individual calling means and the multi-point conference call, a key operation unit, and means for controlling switching between the individual calling means and the multi-point conference call by operating the key. It has a configuration characterized by the following.

The present invention will be explained in detail below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention. In Figure 1, 1
are audio input/output terminals each connected to a line to contact each participant in the conference, 2 is a 2-wire to 4-wire conversion circuit, 4 is an input communication path, 5 is an output communication path, 7 is an input signal detection circuit, 8 1 is an audible sound identification circuit, 9 is an output channel mute circuit, 10 is a display/mute control circuit, 11 is an input signal display, and 12 is an audio signal addition/distribution circuit using the (N-1) addition method.

Referring to FIG. 1, the circuit operation of the audible sound identification circuit 8 will be explained. The audible sounds output from the exchange include a dial tone, a ring tone, and a busy tone. The dialing tone is a continuous signal of 400Hz, the ringing tone is a signal of 400f (z modulated at 16Hz, and the signal is interrupted for 2 seconds by unplugging a bottle), and the busy tone is a 400 tactile signal of 0.5
The bottle opener is an intermittent signal with 0.5 interruptions, and each time is 400H.
The main component is the z signal. The audible sound identification circuit 9 determines whether the detected sound is an audible sound based on whether the main component of the signal on the input communication path 4 is a 400 Hz signal.

An example of the audible sound identification circuit 8 is shown in FIG. In Fig. 2, 13 is a band pass filter that passes only the 400 Hz signal, 14 is a notch filter that does not pass the 400 Hz signal, 15 is a rectifier diode, 16 is a capacitor, 17 is a resistor, 18 is a comparator, 19 is an input terminal, 20 is an output terminal, and 21 is a rectifying and smoothing circuit including 15, 16, and 17. When an audible sound is input from the input communication path 4 through the input terminal 19, the signal path on the band pass filter 13 side is passed through as is, or the notch filter 14 cannot be passed through, so the comparator detected through the rectification and smoothing circuit 21 The signal level of the + terminal and one terminal of 18 is higher on the band pass filter 13 side (+ terminal). Therefore, in this case, a high (H) level is output to the output terminal of the comparator. Furthermore, when an audio signal is input from the input communication path 4, the audio signal via the input terminal 19 includes many signal components other than the 400 Hz signal component, so contrary to the case of audible sound, the band frequency and Since the signal does not pass through the pass filter 13 but passes through the notch filter 14 side, its signal level becomes higher, and a low (L) level is outputted to the output terminal of the comparator 18. The above circuit operation makes it possible to identify audible sounds.

Next, the circuit operation of the input signal detection circuit 7 will be explained with reference to FIG. The input signal detection circuit 7 is connected to the input communication path 4
By comparing the signal level of the output communication path 5 with the signal level of the output communication path 5, it is determined whether the signal detected on the input communication path 4 or the signal input from the own line is output, and the result is output to the display mute control circuit 10. Here, the signal level when the signal input from another line is added and distributed by the addition/distribution circuit 12 and detected on the output communication path 5 of the own line is Vout, and the signal is output from the 2-wire to 4-wire conversion circuit 2. Let Vin be the signal level when the signal is leaked and detected in the input communication path 4, and bs be the leakage attenuation in the 2-wire to 4-wire conversion circuit at this time.The leakage attenuation bs can be expressed by the following formula. can.

bs=Vout−Vin −−−−−−−−−−
-・-11) If the signal levels of the output communication path 5 and the input communication path 4 detected by the input signal detection circuit 7 during a conference call are V out' and V in', respectively, the detected signal of the input communication path 4 is Whether or not the input signal is from the own line is determined by the following formula.

V in'> V out' -bs ---
−−−−−−−−(2) Vin' ≦V out'
-bs -------(3) In the above formula, (2
) If the formula holds true, it is determined that the input signal is from the own line, and
If formula (3) holds true, it is determined that the echo is from the output channel 5.

FIG. 3 shows an example of an input signal detection circuit. In Fig. 3, 22 is a logarithmic conversion circuit, 23 is an analog/digital (
A/D) converter, 24 is an input signal detection control circuit, 2
5 is an operational amplifier, 26 is an input channel input terminal, and 27 is an output channel input terminal. Explanation of parts with the same numbers as those in FIG. 2 will be omitted. The signals at the input communication path input terminal 26 and the output communication path input terminal 27 are logarithmically converted in the logarithmic conversion circuit 22, then rectified and smoothed in the rectification and smoothing circuit 21, and further A/
It is converted into a digital quantity by the D converter 23 and read by the input signal detection control circuit 24. The input signal detection control circuit 24 determines the leakage attenuation amount bs from the read signal levels of the input communication path 4 and the output communication path 5, and determines whether the signal from the input communication path 4, the input signal from the own line, or the output signal from the output communication path 5 is detected. It is determined whether it is an echo or not, and the result is output to the output terminal 20.

Next, in FIG. 1, a method of controlling the display/mute control circuit IO will be described with reference to the flowchart in FIG. 4. The display/mute control circuit 10 controls the input signal display 11 and the output channel mute circuit 9 from the output information of the input signal detection circuit 7 and the audible sound identification circuit 8 as follows. When the input signal detection circuit 7 outputs information that there is no input signal from its own line (Sl), the audible sound identification circuit 8
Regardless of the output information from S, the input signal indicator 11 of the corresponding line displays the state of no input signal (S,...
).

To output information indicating whether the input signal is from the input signal detection circuit 7 or from the own line S→, and if the output information from the audible sound identification circuit 8 or the audible sound detection information (S2), the input of the corresponding line The signal indicator 11 should display the audible sound reception status.
S, , ), the output communication path mute circuit 9 is put into a mute state (the communication path is cut off).

By muting the output communication path 5 when receiving an audible sound, signals input from other lines will not enter the input communication path 4 of the own line (S4), and the audible sound identification circuit 8 can be stably operated. Audible sounds can be detected. here,
Among the audible sounds, the ring tone and the busy tone are intermittent signals, so to ensure stable operation, the transmitter is kept in a muted state even during signal interruptions (Ss,).

Further, if the input signal detection circuit 7 outputs the information that "there is an input signal from the own line" (S1), and the output information from the audible sound identification circuit 8 is audio signal detection information (S2),
The input signal display 11 of the corresponding line displays the audio signal receiving state (S=-2). At this time, it is determined that the own line is in a conference call (S4), so the output channel mute circuit 9 is not muted (S5-2).

Here, the signal display 11 is constituted by a display such as an LED or a liquid crystal display.

FIG. 5 shows another embodiment according to the invention. In the figure,
1 is an audio input/output terminal connected to a plurality of lines that contact each participant in the conference, 2 is a 2-wire to 4-wire conversion circuit, 1
2 is an audio signal addition/distribution circuit, 4 is an input communication path, 5 is an output communication path, 56 is an input communication path mute circuit, 57 is an output communication path mute circuit, 58 is a status indicator, 59 is a control circuit, and 60 is a control circuit. Key operation unit, 61-1 is a connection terminal for conference calls, 61-2 is a connection terminal for individual calls, 62-1 is a conference call telephone that connects to this device to make conference calls, 62-2 is connected to this device. Individual call telephone for connecting and making individual calls, 6
3 is a capacitor; 64 is a current source that supplies a talking current to the individual telephone set 62-2; 65 is a current detection circuit that detects the talking current supplied to the individual telephone set; 66 is a circuit for each audio input terminal I; This is a switch for switching between the individual call telephone 62-2 side (b side) and the conference call circuit (consisting of circuits after the 2-wire to 4-wire conversion circuit 2) side (a side).

In FIG. 5, during a conference call, the control circuit 59 switches the switch 66 to the a side and sets the input channel mute circuit 56 and the output channel mute circuit 57 to a non-muted state (talking state) as shown. When an audio signal is input from the audio input/output terminal l during a conference call, the input audio signal is sent to the switch 66 (a side).

It reaches an addition/distribution circuit I2 via a 2-wire to 4-wire conversion circuit 2 and an input communication path 4. The addition/distribution circuit 12 outputs the audio signal to the output communication paths 5 of all lines except the line into which the audio signal is input.

The output audio signal is sent to an output communication path 5, a 2-wire to 4-wire conversion circuit 2. The signal is output to the line via the switch 66 (a side) and the audio input/output terminal 1. At this time, the conference call connection terminal 6
If telephone 62-■ is connected to 1-1,
The audio signal can be heard at 2-1.

Next, the operation of the individual call will be explained with reference to the flowchart shown in FIG. First, individual call connection terminal 61-
Connect the telephone 62-2 to 2. Next, by operating the keys on the key operation unit 60, the user individually selects the line on which he or she wishes to make a call, and takes the connected telephone 62-2 off-hook. Telephone 62-2
When the telephone 62-2 is taken off-hook, the current source 64 supplies telephone current to the telephone 62-2. At this time, the current detection circuit 65 detects the communication current (S, , ), and the communication current presence information is read into the control circuit 59. The control circuit 59 switches the switch 66 of the selected line to the b side based on the key information obtained by the key operation and the talk current information (S, □), and individually communicates between the other party of the selected line and the telephone 62-2. You can now make calls (S,).

At this time, the status display 58 displays the individual call status and the line number on which the individual call is being made (S,...).

When the individual call ends, when the telephone 62-2 is turned on-hook, the current supply to the telephone 62-2 is cut off.
The current detection circuit 65 outputs the no-talk current information (S, , ). If the individual call is not in progress (S, 5), the control circuit 59 switches the switch 66, which had been switched to the b side, to the a side in order to make an individual call based on the communication current information (S, . . .). After switching the switch 66 to the a side, conference calls are possible again, and the status display 58 displays the conference call status (S, . . .).

Next, the functions of the input channel mute circuit 56 and the output channel mute circuit 57 will be explained. If you do not want specific conference participants to hear the content of the conference, press the key operation section 60.
key operation mutes the output call path mute circuit 57 of the line corresponding to the participant (output call path disconnected state)
Make it. When the output communication path 5 is in the muted state, the audio signals from each line added and distributed by the addition/distribution circuit 2 cannot pass through the output communication path in the muted state. The content of the meeting will no longer be transmitted to the line that is muted. At this time,
It is also possible to mute the output communication paths 5 for a plurality of lines at the same time.

Furthermore, when the input communication path mute circuit 56 is put into the mute state by key operation, the audio signal input from the line will no longer pass through that input communication path, so the audio signals spoken by conference participants on the same line will be transmitted to all other channels. The message will not be communicated to the meeting participants. By muting the receiving channel in this way, it is possible to forcibly invalidate the speech of a conference participant who is not allowed to speak. Similar to the output call path mute function, the input call mute function can mute input call paths for multiple lines at the same time. When using this device in broadcast format, the mute function of the input communication path is enabled. Note that when the input communication path is muted and the output communication path is muted, the muted line is displayed on the status display 58, so it can be easily determined whether the line is muted or not. . A liquid crystal display, an LED, or the like is used as the status display 58.

(5) As described in detail, according to the present invention, by detecting audio signals and audible sounds input from a communication line and displaying them on the display, the operator of this device can Even when a line is connected, the status of the connected line can be easily known. For example, after dialing a plurality of lines at the same time, if the signal display indicates that a busy tone has been received on the line, that line can be opened from the loop and dialing can be made again. Further, even when a participant in the conference speaks, it is possible to easily determine who is speaking because the speech is displayed on the audio signal display of the corresponding line.

Furthermore, according to the present invention, it is possible to talk to specific conference participants individually during a conference, and it is also possible to prohibit specific conference participants from speaking or from hearing the content of the conference. Furthermore, since the current status of the device can be confirmed on the display, the convenience of teleconferences can be greatly improved.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of a conference call device according to the present invention, FIG. 2 is a circuit diagram showing an example of an audible sound identification circuit used in the present invention, and FIG. 3 is an input signal detection circuit used in the present invention. A circuit diagram showing an example, FIG. 4 is a flowchart of display control processing according to the embodiment of the present invention in FIG. 1 when audio signals and audible sounds are detected, and FIG. 5 is a block diagram showing another embodiment of the present invention. FIG. 6 is a flow chart for explaining the operation of the embodiment shown in FIG. 5, and FIG. 7 is a block diagram showing an example of a conventional conference call device. 1...Audio input/output terminal, 2...2-4 wire conversion circuit,
3... Subtraction circuit, 4... Input communication path, 5... Output communication path, 6... All signal addition circuit, 7... Input signal detection circuit, 8... Audible sound identification circuit, 9...Output channel mute circuit, 10...Display/mute control circuit, 1
1... Input signal display device, 12... Addition distribution circuit, 1
3... Band pass filter, 14... Notch filter, 15... Rectifier diode, 16... Capacitor, 17... Resistor, 18... Comparator, 1
9... Input terminal, 20... Output terminal, 21... Rectifier and smoothing circuit, 22... Logarithmic conversion circuit, 23... Analog/digital (A/D) converter, 24... Input signal Detection circuit, 25... operational amplifier, 26... input signal input terminal, 27... output signal input terminal, 56...
- Mute circuit for input communication path, 57... Mute circuit for output communication path, 58... Status display, 59... Side leg circuit, 60... Key operation section, 61-1... Conference Call control terminal, 61-2...Individual call connection terminal, 6
2-1...Telephone for conference calls, 62-2...Telephone for individual calls, 63...Capacitor, 64...Current source, 65...Current detection circuit, 66...Switch. Octopus 1 diagram

Claims (2)

[Claims] (1) A 2-wire to 4-wire conversion circuit is connected to each of the plurality of connected 2-wire communication lines, and the subscriber's voice signal inputted from the communication line is added to the communication line again. By arranging audio signal addition and distribution means on the 4-wire side of the 2-wire to 4-wire conversion circuit, a conference call can be made between multiple points, and each input from the plurality of communication lines detecting means for determining whether or not signals detected on a plurality of input communication paths inputting signals to the voice signal addition and distribution means are input signals from the communication line; and detection means for determining whether each of the input signals is a voice signal or from an exchange identification means for identifying whether the transmitted audible tone (dialing tone, busy tone, ringing tone);
a communication line mute means for muting each of a plurality of output calls on the line side; a display means for displaying that the input signal is being input from the communication line; control means for controlling the display of the signal detected by the display means when an input signal (audio signal/audible sound) is detected from the display; A teleconference device comprising: control means for controlling a corresponding one of the plurality of output communication paths to a mute state by a mute means. (2) A 2-wire to 4-wire conversion circuit is connected to each of the plurality of connected 2-wire communication lines, and the subscriber's voice signal inputted from the communication line is added up and retransmitted to the communication line. By connecting an audio signal addition and distribution means for distributing audio signals to the 4-wire side of the 2-wire to 4-wire conversion circuit, it is configured to conduct a conference call between multiple points, and to conduct a conference call between the multiple points. an individual calling means capable of making a call separately from the communication line; a switch circuit for switching between the individual calling means and the conference call between the multipoints; a key operation section; and means for controlling switching of the multipoint conference call.