JPH0353650A - Voice conference equipment - Google Patents

Abstract

PURPOSE:To avoid the overall directivity of microphones from being fixed by providing a polarity changeover circuit switching the polarity of a voice signal inputted from the plural microphones. CONSTITUTION:The equipment consists of microphones 1-4, a speaker 5, a polarity changeover circuit 6, an amplifier 7, A/D converters 8, 12, D/A converters 9, 11, an echo canceller control circuit 10, and a hybrid circuit (H) 13. Then the polarity changeover circuit 6 has a relay 14 and a microphone amplifier 15 to select the polarity of the inputted voice signal. Thus, the overall directivity of plural microphones is selected depending on the state of a conference room or the position of a talker.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an audio conference device. [Prior Art] In a conventional audio conferencing device, the positions of multiple microphones are fixed depending on the position where the audio conferencing device is placed, and the polarity of the audio signal input to each microphone is fixed by the transmitting circuit to which each microphone is connected. Therefore, the overall directivity of the microphone was constant. [Problems to be Solved by the Invention] In the conventional audio conferencing device described above, when the position where the audio conferencing device is placed is fixed, each of the multiple microphones becomes a fixed location, and as a result, input to each microphone is Since the polarity of the audio signal is fixed by the transmission circuit connected to each microphone, the overall directivity of the microphones appears to be constant, and the audio signals input to the microphones from multiple speakers are This method has the disadvantage that it causes a difference in level depending on the speaker, and it becomes difficult to hear the voice of a speaker with a low audio level through the audio conference device of the other party. [Means for Solving the Problems] An audio conference device of the present invention is an audio conference device that performs a call using a speaker and a plurality of microphones, and includes a polarity switching circuit that switches the polarity of transmission signals input from the plurality of microphones. a transmitting circuit that guides the output signal of the polarity switching circuit to a hybrid circuit connected to a line; a receiving circuit that guides a received signal arriving from the line through the hybrid circuit to the speaker; the transmitting circuit; The apparatus further includes an echo canceller control circuit connected between the receiving circuit and canceling an echo signal generated when the transmitting signal passes through the hybrid circuit and goes around to the receiving circuit.

〔Example〕

Next, the present invention will be explained with reference to the drawings. Fig. 1 shows an embodiment of the present invention, Fig. 2(a), (
b) is a diagram showing an example of the apparent overall microphone directivity of this embodiment. In FIG. 1, this embodiment includes microphones 1 to 4, a polarity switching circuit 6 that switches the polarity of each input signal of the microphones 1 to 4, and an analog output signal that converts the analog output signal of the polarity switching circuit 6 into a digital output signal. Goo digital converter (hereinafter referred to as A/D) 8,
A digital-to-analog converter (hereinafter referred to as D/A) 11 converts the digital output signal into an analog transmission signal again, sends the transmission signal to a two-line line, receives an analog reception signal from the line, and transmits it. A hybrid circuit (hereinafter referred to as H) 13 that separates the signal and an A/D I 2 that converts the analog reception signal from 813 into a digital input signal.
, D/A9 which converts the digital input signal to analog input signal, digital output signal from A/D8 and A
The echo canceller control circuit 10 performs echo cancellation using the digital input signal from the D/A 9, and the amplifier 7 amplifies the analog input signal from the D/A 9 and amplifies the sound using the loudspeaker 5. ing.

The polarity switching circuit 6 includes a relay 14 that switches the polarity of each input signal from the microphones 1 to 4, and a microphone amplifier 15 that amplifies each input signal whose polarity has been converted. Next, regarding the operation of this embodiment, Fig. 1, Fig. 2(a),
This will be explained using (b).

Microphones 1 to 4 as shown in Figure 2 (a) and (b)
are installed at the four corners of the table, and the audio signals input from the microphones 1 to 4 pass through a transmission circuit comprising a polarity switching circuit 6, an A/D 8, an echo canceller control unit 10, and a D/All. It is sent to the line via In addition, the received signal arriving from the other party's conference room through the line is sent to the A/D 1 2 and the echo canceller control unit 10.
, a D/A 9, and an amplifier 7, and is reproduced as audio by the speaker 5. It is assumed that the overall directivity of the microphones 1 to 4 initially shows the apparent directivity characteristic shown in FIG. 2 (a>).

When the polarity switching circuit 6 receives the switching signal a from the echo canceller control unit 10, the relay 14 operates, and the polarity of the input signal of the microphone 2.4 connected to the input (10 poles and 1 pole) of the microphone amplifier 15 is changed. It is switched by relay 14.

As a result, the overall directivity of microphones 1 to 4 apparently changes to the directivity characteristic shown in FIG. 2(b). [Effects of the Invention] As explained above, the present invention has a polarity switching circuit that switches the polarity of audio signals input from a plurality of microphones, so that the overall directivity of the plurality of microphones can be adjusted depending on the state of the conference room or the speaker. Since it can be switched according to the position of the speaker, the voice level of a speaker with a low voice level can be improved, and the communication state with the other party's voice conference device can always be maintained in a good condition.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention, and FIG. 2 (
FIGS. 3A and 3B are diagrams each showing an example of the apparent overall directivity of microphones in this embodiment.

Claims (1)

[Claims] An audio conferencing device that uses a speaker and multiple microphones to make a call, includes a polarity switching circuit that switches the polarity of transmission signals input from the multiple microphones, and a hybrid system that connects the output signal of the polarity switching circuit to a line. a transmitting circuit that guides a received signal coming from the line through the hybrid circuit to the speaker, and a receiving circuit that is connected between the transmitting circuit and the receiving circuit so that the transmitted signal is connected to the hybrid circuit. and an echo canceller control circuit for canceling an echo signal generated by passing through the circuit and going around to the receiving circuit.