JP2001157292A - Earphone having microphone function and full duplex audio communication circuit using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a full duplex audio communication circuit that employs only one earphone with reversibility, that is, having a microphone function and enhances a cancellation quantity by a feedback. SOLUTION: By combining a compressor and an expander with a cancellation circuit conducting cancellation with a feedback with the same amplitude and an opposite phase, the cancellation quantity can further be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an earphone having a microphone function through air conduction in the ear canal of a uttered voice, and a full-duplex audio communication circuit using only one of the earphones without electrical feedback.

[0002]

2. Description of the Related Art Conventional earphones include a bone conduction microphone for picking up bone conduction voice vibration and a bone conduction earphone microphone in which a sound pressure type speaker is incorporated in the same case. In this method, a pressure bimorph is used as an acoustic-electrical signal conversion element, which is housed in an ear hole insertion portion of an earphone microphone case, detects bone conduction voice vibration, and simultaneously receives a reception sound of a speaker from an opening at a distal end of the ear hole insertion portion. (JP-A-5-199577, JP-A-8-26588).
No. 7).

However, since the bone conduction microphone and the sound pressure type speaker are incorporated in the same case as described above, there is a problem that howling of sound is apt to occur.

The inventor of the present invention has proposed a microphone function for converting an audio input-to-electrical signal output through air conduction in the ear canal of a voice to be uttered, and converting an audio signal current received from the outside into a voice to generate a voice in the ear canal. By using only one earphone having a microphone function without voice howling simultaneously having an electric signal output-sound input conversion earphone function to be transmitted to the inner ear via the air conduction, a handset circuit unit without electronic feedback is provided. We have proposed a full-duplex audio communication circuit that is easy to design. Although the conventional example still has problems, it will be described with a specific example shown below.

[0005] The first proposal was made so that only the components of the received signal were canceled out in the transmitted signal by connecting between the transmitting / receiving section of the portable telephone and the handset circuit section, that is, the electrical feedback was reduced. FIG. 6 shows a block diagram of a conventional example which is a full-duplex audio communication circuit but its improvement is not sufficient.

In FIG. 6, reference numeral 200 denotes a conventional full-duplex audio communication circuit (transmitter / receiver circuit), 10 denotes an output terminal, 11 denotes an input terminal, and 12 denotes an input / output terminal of an earphone having a microphone function. . G1 and Z1 denote a reception voltage at an input terminal and an equivalent load resistance at an output terminal, respectively. Also,
G2 and Z2 indicate the output voltage at the input / output terminal and the equivalent load resistance, respectively.

The operation is as follows. The input signal G1 from the input terminal 11 is output to the load resistor Z2 through the input / output terminal 12 via the operational amplifier amplifier circuit A1 and the resistor circuit R1.

On the other hand, the input voltage G2 from the input / output terminal 12
Output through the output terminal 10 to the load resistor Z1 via the resistor circuit R2 and the operational amplifier amplifier circuit A2.

However, in this case, the signal component passing through the output terminal 10 includes the signal component passing from the input terminal 11 through the operational amplifier amplifier circuit A1, the resistor circuits R1 and R2, and the operational amplifier amplifier circuit A2, and causes feedback. Further, as shown in FIG. 6, a branch circuit is provided between the input terminal 11 and the connection point 13 of the resistor circuit R2 and the operational amplifier amplifier circuit. The branch circuit includes an operational amplifier inverting amplifier circuit I1 and a gain / phase adjusting circuit 14.

The branch circuit and the resistor circuit R2 form a cancel circuit 15 for the input signal G1. That is, first, the phase of the input signal G1 input from the first input terminal 15a of the cancel circuit 15 is inverted by the operational amplifier inverting amplifier circuit I1, and the gain / phase adjusting circuit 14 further inputs the input signal G1 from the second input terminal 15b of the cancel circuit 15. The input signal G1 is adjusted so as to have the same amplitude and opposite phase as that of the input signal G1 passing through the resistance circuit R2, and is synthesized at the connection point 13.
The cancellation circuit 15 is set so that only the components cancel each other.
From the output terminal 15c. Therefore, the output terminal 10
Should be a component of only the input voltage from the input / output terminal, but it is actually difficult to completely cancel it out, and it is usually about -30 dB.

[0011]

In order to further improve the amount of cancellation of the electric feedback by the cancellation circuit 15 as shown in FIG.
Each circuit constant of the cancel circuit 15 must be set accurately. However, if any of these circuit constants has a constant shift change from the constant value, the amount of cancellation is sharply reduced. The limit was about 30 dB.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has as its object to simultaneously provide a sound input-electric signal output conversion microphone function and an electric signal input-sound output earphone function conversely. In order to provide an earphone having a microphone function without feedback, and to use only one of the earphones and improve the electric feedback to a practical level, a canceller 15 is combined with a compressor and a decompressor, and It is another object of the present invention to provide a full-duplex audio communication circuit capable of stably obtaining a cancellation amount up to about -60 dB.

[0013]

In order to solve the above-mentioned problems, an earphone having a microphone function according to the present invention has a microphone function having at least a vibrating member, a magnetic member adhered to the vibrating member, and a coil portion for winding the magnetic member. A magnetic type earphone, wherein the vibration member receives the air vibration via air conduction in the ear canal of the voice to be uttered,
An acoustic input-to-electrical signal output conversion microphone function for causing the magnetic member to vibrate and thereby generate an audio signal current in the coil portion, and an externally sent audio signal current to flow through the coil portion, It has an electric signal input-acoustic output conversion earphone function for outputting sound waves generated in the vibrating member through the air conduction into the ear canal by vibrating, so that both conversions can be performed simultaneously.

Further, the vibration member, a coil portion connected thereto, a magnet provided inside the coil portion, and a magnetic circuit connecting the magnet and a magnetic yoke provided outside the coil portion are provided. A dynamic earphone having at least a microphone function, wherein the sound wave is received by the vibrating member via air conduction in an ear hole of a voice to be uttered, and the coil portion is moved in a static magnetic field gap of the magnetic circuit. An acoustic input-to-electrical signal output conversion microphone function for generating an audio current in the coil section by displacing the coil section, and an audio signal current sent from the outside flows through the coil section, and the coil section flows in the static magnetic field gap. By displacing
It has an electric signal input-sound output conversion earphone function of outputting a sound wave generated by vibrating a vibration member connected thereto to the ear canal through the air conduction, so that both conversions can be performed simultaneously. .

A crystal type earphone having a microphone function provided with a piezoelectric element member, wherein the sound element receives the sound wave via air conduction in an ear hole of a voice to be uttered, and An acoustic input-to-electrical signal output conversion microphone function for generating an audio voltage by displacing and vibrating, and applying an audio signal voltage sent from the outside simultaneously with the uttered voice to the piezoelectric element member, An electric signal input-acoustic output conversion earphone function for outputting a sound wave generated by the displacement vibration to the ear canal through the air conduction, and the two conversions can be performed simultaneously.

According to another aspect of the present invention, a full-duplex audio communication circuit of the present invention is a full-duplex audio communication circuit of a handset circuit section of a communication device.
Or a first earphone having a microphone function by air conduction in the ear canal according to 3 and a first earphone connected between the earphone and the input / output terminal of the earphone to output a reception signal from the input / output circuit section input terminal to the input / output terminal of the earphone. An amplifier circuit, a first impedance circuit in series with the amplifier circuit, and a second impedance circuit connected therebetween for outputting a transmission signal from an input / output terminal of the earphone to an output terminal of the handset circuit unit; A second amplifier circuit, the second impedance circuit, and a second amplifier circuit for preventing a signal received from the input terminal from being output to the output terminal via the second amplifier circuit. A branch circuit comprising an inverting amplifier circuit and a series gain / phase adjustment circuit between the connection point of the circuit and the input terminal, wherein the second impedance circuit and the With the branch circuit, a received signal from the input terminal is combined at a signal combining connection point therebetween to form a cancel circuit that is canceled, and the input to the cancel circuit first input terminal on the input terminal side is the first. The input signal is input via the compressor, the input / output terminal side cancel circuit second input terminal is input via the second compressor, and the combined input signal is output to the output terminal via the decompressor. It is characterized by that.

Further, the first and second compressors perform compression by a logarithmic ratio to 1/2, and the expander expands by a logarithmic ratio to twice.

Further, the first and second amplifier circuits are each an operational amplifier amplifier circuit, the inverting amplifier circuit is an operational amplifier inverting amplifier circuit, and the first and second impedance circuits are each a resistor circuit. .

Further, the communication device is a mobile phone,
A reception circuit and a transmission circuit of the portable telephone body are connected to the input terminal and the output terminal, respectively, so that components of the reception signal are canceled out in the transmission signal.

The full-duplex audio communication circuit of the present invention is a full-duplex audio communication circuit of a handset circuit section of a communication device, and has a microphone function by air conduction in an ear canal according to claim 1, 2, or 3. And an amplifying circuit connected therebetween to output a reception signal from an input terminal of the handset circuit unit to an input / output terminal of the earphone, and an impedance circuit in series with the amplifying circuit. A first A / D converter, a first compressor, a decompressor, and a D / D converter connected in series between the input and output terminals to output a transmission signal to an output terminal of the handset circuit unit.
Connection between the first compressor and the decompressor for preventing an A-converter from being output from the input terminal to the output terminal via the decompressor and the D / A converter. A second A / D connected in series between a point and the input
A converter, a second compressor, and a branch circuit including an adaptive digital filter having a feedback input terminal and performing gain / phase control, provided between the first compressor and the branch circuit. A signal combining circuit that combines the received digital signals from the input terminals, returns the combined output to the feedback input terminal of the adaptive digital filter, and performs digital signal processing to minimize the combined output. It is characterized by.

Further, the first and second compressors perform compression by a log ratio of 1/2, and the expander expands by a log ratio of twice.

Further, the amplifier circuit is an operational amplifier amplifier circuit, and the impedance circuit is a resistance circuit.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, FIG. 5 shows a structural diagram of an earphone having a microphone function according to the present invention. 5A shows an embodiment of a magnetic earphone 50, FIG. 5B shows an embodiment of a dynamic earphone 60, and FIG. 5C shows an embodiment of a crystal earphone 70. FIG. 5A shows a type having the ear hole insertion portion 50a. However, as shown in FIG. 5B, an outer cavity mounting shape 50b having an outer shape that can be mounted in the auricle of the auricle may be used. FIG. 5C may have any of the shapes described above. In FIG. 5A, 51 is a diaphragm, 52 is a permanent magnet and its support, 53 is a coil around which the permanent magnet is wound, and 54 is an input / output terminal connected to both ends of the coil.

The uttered voice passes through the ear hole insertion portion 50a through the air conduction in the ear hole, vibrates the diaphragm 51, vibrates the permanent magnet 52 connected thereto, and generates a voice signal current in the coil portion 53 ( Sound input-electric signal output conversion microphone function).

An audio current sent from the outside is passed through the coil section 53, and the magnetic magnet 52 is vibrated so that the diaphragm 51
Is vibrated and transmitted to the inner ear via the air hole in the ear hole through the ear hole insertion portion 50a (electrical signal input-sound output conversion earphone function). Both of the above conversions can be performed simultaneously.

Next, in FIG. 5B, 61 is a vibrating membrane, 62 is a permanent magnet, 63 is a coil part, 64 is an input / output terminal connected to both ends of the voice coil, and 65 is a magnetic yoke.

Here, the uttered voice passes through the central hole of the insertion cavity 50b through the air conduction in the ear canal and passes through the diaphragm 6
1 and vibrates the coil unit 63 connected thereto. The coil portion 63 includes a permanent magnet 62 and a magnetic yoke 65.
Thus, an audio signal current is generated in the coil unit 63 because the audio signal current is provided in the gap of the magnetic field formed by the above.

On the other hand, an audio current sent from the outside flows through the coil portion 63, vibrates the coil portion 63, vibrates the vibrating membrane 61 connected thereto, and transmits the vibration to the inner ear via the air conduction in the ear canal. Both of the above conversions can be performed simultaneously.

Next, in FIG. 5C, reference numeral 71 denotes a vibration film, 72 denotes a piezoelectric element material mounted thereon, 73 denotes a supporting metal plate thereof, and 74 denotes a vibration film 72 and a supporting metal plate 73, respectively. Input / output terminal.

Here, the uttered voice passes through the ear hole insertion portion 50a through the air conduction in the ear hole, vibrates the vibration film 71, and the piezoelectric element material 7 sandwiched between the vibration film 71 and the supporting metal plate 73.
2 is applied with oscillating pressure. Thus, the audio voltage generated at both ends is output from the input / output terminal 74.

On the other hand, an audio voltage sent from the outside is inputted from the input / output terminal 74 and applied to the piezoelectric element material 72, the piezoelectric element material 72 vibrates, and the vibration plate 71 attached thereto is vibrated. To the inner ear via air conduction. Both of the above conversions can be performed simultaneously.

One embodiment of the full-duplex audio communication circuit of the present invention will be described with reference to FIG. In FIG. 4, reference numeral 100 denotes a full-duplex audio communication circuit (transmitter / receiver circuit unit) according to the first embodiment of the present invention. In the figure, the same functions as those in FIG. 6 of the conventional example are denoted by the same reference numerals, and the description thereof will be omitted. 16 is a first compressor, 17 is a second compressor, and 18 is a decompressor. Next, the operation of the full-duplex audio communication circuit of FIG. 1 of the present invention will be described. First, an input signal from the input terminal 11 is supplied to an operational amplifier amplifier circuit A1 (first amplifier circuit) and a resistance circuit R1.
(First impedance circuit) via input / output terminal 12
And output to the load Z2. On the other hand, the input voltage G2 from the input / output terminal 12 is supplied to the second compressor 17, the resistor circuit R2 (second impedance circuit), and the operational amplifier amplifier circuit A2.
(Second amplifier circuit) and the output terminal 1 via the expander 18
It passes through 0 and is output to the load resistance Z1. Here, output terminal 1
The signal component passing through 0 includes an input signal component from the input terminal 11 that feeds back from the input terminal 11 via the operational amplifier amplifier A1, the resistor R1, the compressor 17, the resistor R2, the operational amplifier amplifier A2, and the expander 18. ing.

In order to cancel this, the operational amplifier inverting amplifier circuit I is input from the input terminal 11 via the first compressor 16.
1 and a branch circuit composed of a gain / phase adjustment circuit 14, which is connected to a connection point 13. A resistor circuit R2 and the branch circuit form a cancel circuit for canceling an input signal component from the input terminal 11.

The input signal from the input terminal 11 is supplied to the compressor 16
Through the first input terminal 15a of the cancel circuit 15, the phase is inverted by the operational amplifier inverting amplifier circuit, the gain and the phase are adjusted, and the input is made from the second input terminal 15b of the cancel circuit. The input signal passing through R2 has the same amplitude as that of the input signal, the phase is adjusted to the opposite phase, the input signal is combined at the connection point to cancel the input signal, and output from the output terminal 15c of the cancel circuit. At the same time, the input signal from the input / output terminal passes without being canceled.

In this case, the compressors 16 and 17 and the decompressor 18
Is shown in FIG. Compression is 1 / log ratio
2. Elongation is twice the logarithmic ratio. The log ratio is 1 /
It can be 3, 3 times, 1/4, 4 times, but gradually,
The sound becomes unnatural. In FIG. 2, the input voltage G1 from the input terminal is set to 0 dBV, and the voltage level (dBV) in each section is indicated by a solid line and an arrow. On the other hand, assuming that the input voltage G2 from the input / output terminal is 0 dBV, the voltage level (dBV) in each section is indicated by a broken line and an arrow.
FIG. 7 shows the voltage level (dBV) in each part of the conventional example shown in FIG. 6 for comparison. In FIG. 2, an attenuator (-3 dB) 19 and an operational amplifier (6 dB) A3 are inserted for the sake of description, so that the levels of respective parts are the same in FIGS. 2 and 7, and are not originally required. For simplicity, R1ＲR2, R1 = Z2, and R2 = R3.
As is clear from the comparison between FIG. 2 and FIG. 7, the output level at the output terminal 10 in FIG. 7 of the conventional example has a difference of −30 dB, whereas in FIG. 2, there is a difference of −60 dB. It can be seen that the logarithmic ratio has been improved twice.

FIG. 3 shows another embodiment of the present invention. In FIG. 3, reference numeral 150 denotes a full-duplex audio communication circuit (transmitter / receiver circuit unit) according to the second embodiment of the present invention. In the figure, the same functions as those in FIG. 6 of the conventional example are denoted by the same reference numerals, and description thereof will be omitted. Reference numeral 20 denotes a range constituted by digital circuits,
Reference numerals 1 and 22 denote first and second analog / digital conversions.
A / D converter 23, a D / A converter for performing digital-to-analog conversion, 24 and 25 are first and second compressors respectively, 26 is a decompressor, and 27 is an adaptive digital
A filter 27a is a gain / phase control input terminal of the adaptive digital filter 27, and 28 is a digital signal synthesizing circuit.

The operation is as follows. An input signal from the input terminal 11 includes an operational amplifier amplifier circuit A1 and a resistor circuit R
1 and output from the input / output terminal to the load resistor Z2. On the other hand, an input signal from the input / output terminal 12 enters the first A / D converter 21 and becomes a digital signal.
to go into. Next, the signal enters the expander 26, enters the D / A converter 23, becomes an analog signal, and outputs the analog signal from the output terminal 10 to the load resistor Z1. On the other hand, in order to prevent the input signal from the input terminal 11 from being fed back to the output terminal 10, the input signal from the input terminal 11 is input to the second A / D converter 22 to be converted into a digital signal to be converted into a second compressor. 25, and then into the adaptive digital filter 27. This output is combined with the input signal passed through the first compressor 24 by a digital signal combining circuit 28. At this time, the synthesized signal is input to the feedback input terminal 27a of the adaptive digital filter 27, and the gain and phase of the adaptive digital filter 27 are changed and adjusted so that the synthesized signal is minimized. That is, it is used as a gain / phase adjustment circuit. The adaptive digital filter can cope with a change in the load resistance Z2 at the input / output terminal.

FIG. 5 shows a communication apparatus using the full-duplex audio communication circuits (transmitter / receiver circuit units) 100 and 150 of the present invention.
Shown in FIG. 5A shows a telephone circuit connected to the input / output terminals.
This is a communication device in which a speaker is connected to an output terminal and a microphone is connected to an input terminal. The full-duplex audio communication circuit (transmitter / receiver circuit section) is a side tone suppression circuit. By connecting the ends connected to a microphone and a speaker to the detection output and modulation input of the base unit of the cordless telephone, the present invention can also be applied to a cordless telephone. FIG. 5 (b) shows an earphone microphone having the function of an amphoteric microphone connected to an input / output terminal.
A mobile phone in which an output terminal is connected to a transmission unit of the mobile phone from a microphone, an input terminal is connected to an earphone from a reception unit, a reception signal from the input terminal is canceled, and a cancellation amount at the output terminal is about -60 dB. . FIG.
(C) Connects a bidirectional speaker microphone having a microphone function to an input / output terminal, uses two sets of a full-duplex audio communication circuit (handset circuit unit), and has an input terminal and an output terminal.
A communication device in which an input terminal is connected to an output terminal, and another input / output terminal is connected to a telephone line. A duplex communication device having good feedback characteristics is obtained.

[0039]

The full-duplex audio communication circuit (handset circuit section) of the present invention has the following effects. By combining a compressor and a decompressor with a cancel circuit that adjusts the gain and phase so that the input signal from the input terminal hardly appears at the output terminal, the conventional example was said to be the limit of stable operation. It has become possible to provide a full-duplex audio communication circuit (transmitter / receiver circuit section) that greatly improves -30 dB and performs a stable operation of about -60 dB.

[Brief description of the drawings]

FIG. 1 is a block diagram of a full-duplex audio communication circuit according to an embodiment of the present invention.

FIG. 2 is a diagram showing an example of a signal level of each unit in the block diagram of FIG. 1 of the present invention. The cancellation amount is calculated at 30 dB.

FIG. 3 is a block diagram of a full-duplex audio communication circuit according to another embodiment of the present invention.

FIG. 4 is an input / output characteristic diagram of a compressor and a decompressor used in the present invention.

FIG. 5 is a diagram showing an earphone having a microphone function according to the present invention.

FIG. 6 is a block diagram of a conventional full-duplex audio communication circuit.

7 is a diagram showing an example of a signal level of each unit in the block diagram of FIG. 6 of a conventional example. Note that the cancellation amount is calculated at 30 dB.

[Explanation of symbols]

A1 first amplifier circuit, operational amplifier amplifier circuit A2 second amplifier circuit, operational amplifier amplifier circuit A3 operational amplifier (6 dB) I1 operational amplifier inverting amplifier circuit G1 input voltage at input terminal G2 input voltage from input / output terminal R1 first impedance circuit , Resistance circuit R2 second impedance circuit, resistance circuit R3 resistance circuit Z1 load resistance at output terminal Z2 load resistance at input / output terminal 10 output terminal 11 input terminal 12 earphone input / output terminal having microphone function 13 signal synthesis circuit, connection point Reference Signs List 14 gain / phase adjustment circuit 15 cancellation circuit 15a first input terminal of cancellation circuit 15b second input terminal of cancellation circuit 15c output terminal of cancellation circuit 16 first compressor 17 second compressor 18 expander 19 attenuation (-3 dB) 20 Digital circuit 21 First A / D conversion Reference Signs List 22 second A / D converter 23 D / A converter 24 first compressor 25 second compressor 26 expander 27 adaptive digital filter 27a feedback input terminal 28 digital signal synthesis circuit 50, 60, 70 Earphones with microphone function 51, 61, 71 Vibration plate, diaphragm 52, 62, 72 Permanent magnet 53, 63 Coil unit 73 Support metal plate 54, 64, 74 Input / output terminal 65 Magnetic yoke 100, 150, 200 Full duplex Audio communication circuit (handset circuit unit)

Claims (10)

[Claims] 1. A magnetic earphone having a microphone function including at least a vibrating member, a magnetic member adhered to the vibrating member, and a coil unit for winding the magnetic member, wherein the earphone has a microphone function through air conduction in an ear hole of a voice to be uttered. An acoustic input-to-electrical signal output conversion microphone function of receiving air vibration by the vibrating member and causing the magnetic member to vibrate, thereby generating an audio signal current in the coil unit, and an audio signal current sent from the outside. An electric signal input-acoustic output conversion earphone function of flowing sound waves generated in the vibrating member by flowing through the coil portion and vibrating the magnetic member through the air conduction into an ear hole thereof; Earphones having a microphone function, which can be performed simultaneously. 2. A vibrating member, a coil portion connected thereto, a magnet provided inside the coil portion, and a magnetic circuit connecting the magnet and a magnetic yoke provided outside the coil portion. A dynamic type earphone having at least a microphone function, wherein the sound wave is received by the vibrating member via air conduction in an ear hole of a voice to be uttered, and the coil portion is received in a static magnetic field gap of the magnetic circuit. An acoustic input-to-electrical signal output conversion microphone function for generating an audio current in the coil portion by displacing the coil portion, and an audio signal current sent from the outside flows through the coil portion, and the coil portion flows in the static magnetic field gap. The electric signal input-acoustic output conversion ear that outputs a sound wave generated by vibrating a vibration member connected thereto by displacing the vibration member through the air conduction into the ear canal. A down function, earphone with microphone function, characterized in that perform the two converted simultaneously. 3. A crystal type earphone having a microphone function provided with a piezoelectric element member, wherein the sound element receives the sound wave via air conduction in an ear hole of an uttered voice, and the piezoelectric element member receives the sound. An acoustic input-to-electrical signal output conversion microphone function for generating an audio voltage by displacing and vibrating; and applying an audio signal voltage sent from outside simultaneously with the uttered voice to the piezoelectric element member, An earphone function having an electric signal input-acoustic output conversion earphone function for outputting a sound wave generated by the displacement vibration of the air through the air conduction into an ear canal thereof, wherein the two conversions can be performed simultaneously. . 4. A full-duplex audio communication circuit of a handset circuit part of a communication device, wherein only one earphone having a microphone function by air conduction in an ear canal according to claim 1, 2, or 3; A first amplifier circuit and a first impedance circuit in series therewith for outputting a reception signal from a circuit unit input terminal to an input / output terminal of the earphone; and a transmission from the input / output terminal of the earphone. A second impedance circuit connected therebetween and a second amplifier circuit in series therewith for outputting a signal to the handset circuit unit output terminal; and a reception signal from the input terminal, the second amplifier circuit To prevent output to the output terminal via
A branch circuit comprising an inverting amplifier circuit and a gain / phase adjusting circuit in series between the input terminal and a connection point between the second impedance circuit and the second amplifier circuit; The branch circuit combines the received signals from the input terminals at a signal combining connection point therebetween to form a cancel circuit that is canceled. The input to the cancel circuit first input terminal on the input terminal side is the first input terminal. , A cancel circuit on the input / output terminal side, a second input terminal is input via a second compressor, and the combined input signals of which are output to an output terminal via a decompressor. A full-duplex audio communication circuit. 5. The first and second compressors have a logarithmic ratio of one.
5. The full-duplex audio communication circuit according to claim 4, wherein the data is compressed to / 2, and the expander expands the logarithmic ratio twice. 6. The first and second amplifier circuits are each an operational amplifier amplifier circuit, the inverting amplifier circuit is an operational amplifier inverting amplifier circuit, and the first and second impedance circuits are each a resistor circuit. A full-duplex audio communication circuit according to claim 4. 7. The communication device is a mobile phone, and a reception circuit and a transmission circuit of the mobile phone main body are connected to the input terminal and the output terminal, respectively, so that only a component of a reception signal cancels out in a transmission signal. Claim 4, characterized in that
7. The full-duplex audio communication circuit according to 5 or 6. 8. A full-duplex audio communication circuit of a handset circuit section of a communication device, wherein only one earphone having a microphone function by air conduction in an ear canal according to claim 1, 2, or 3; An amplifier circuit connected between the input and output terminals of the earphone for outputting a reception signal from an input terminal of the circuit unit to an input / output terminal of the earphone, and a transmission signal from the input / output terminal of the earphone; A first A / D converter, a first compressor, a decompressor, and a D / A converter connected in series between the input terminal and the output signal for output to an output terminal of the circuit unit; In order to prevent output to the output terminal via the decompressor and the D / A converter, it is connected in series between the connection point of the first compressor and the decompressor and the input terminal. Second A / D conversion , The second
And a branch circuit comprising an adaptive digital filter having a feedback input terminal and performing gain / phase control, wherein a signal synthesizing circuit provided between the first compressor and the branch circuit is provided. , Combining the received digital signal from the input terminal, returning the combined output to the feedback input terminal of the adaptive digital filter, and performing digital signal processing to minimize the combined output. Dual audio communication circuit. 9. The first and second compressors have a logarithmic ratio of 1
9. The full-duplex audio communication circuit according to claim 8, wherein the data is compressed to / 2, and the expander expands the logarithmic ratio twice. 10. The full-duplex audio communication circuit according to claim 7, wherein the amplification circuit is an operational amplifier amplification circuit, and the impedance circuit is a resistance circuit.