JP2003259478A - Acoustic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an acoustic apparatus preventing howling. <P>SOLUTION: When a sound is generated by vibration of a first vibration plate 11 of a sound generating portion A, an induction current is generated in an auxiliary coil C0 which vibrates together with the first plate 11. The current generated in the coil C0 functions to cancel an induction current generated in a detecting coil C2 by vibrating a second vibration plate 21 in a sound collection portion B. Accordingly, even if the plate 11 in the portion A vibrates, the vibration of the plate 21 of the portion B can be suppressed, and howling can be prevented. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an audio device in which a microphone and a speaker are integrated, and more particularly to an audio device capable of preventing howling and improving the sensitivity of the microphone.

[0002]

2. Description of the Related Art When a microphone and a speaker are housed in a state that they are close to each other, the sound (vibration) emitted from the speaker is picked up by the microphone, converted into an electric signal and emitted from the speaker. In addition, the so-called howling (oscillation state) may occur by repeating the phenomenon that the microphone picks up.

Therefore, in a conventional communication device such as a mobile phone, the microphone and the speaker are separated as much as possible so that the sound emitted from the speaker is not picked up by the microphone to avoid the howling. Has been taken.

Alternatively, a means has been taken to prevent the howling by providing a dedicated electronic circuit or software inside the communication device such as a mobile phone.

[0005]

However, if the means for increasing the distance between the microphone and the speaker is used,
There is a problem that it is difficult to downsize a communication device such as a mobile phone.

In particular, if the microphone and the speaker can be integrated without causing howling, the size of the communication device can be dramatically reduced.

Further, the means using a dedicated electronic circuit has a problem that it is difficult to achieve cost reduction because the circuit configuration becomes complicated.

Further, in the means using software, since it is necessary to secure a dedicated memory, there is a problem that the amount of memory that the user can use decreases.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and an object thereof is to prevent howling from occurring in a sound device including a microphone and a speaker with a simple structure.

[0010]

According to the present invention, there is provided an audio device in which a support is provided with a sound producing section for producing a sound and a sound collecting section operated by a sound pressure generated externally. Is provided with a first vibrating plate for sound generation, a drive coil for vibrating the first vibrating plate, and a magnetic circuit for generating a magnetic field interlinking the drive coil. A second vibrating plate for sound, a detection coil that operates together with the second vibrating plate, and a magnetic circuit that generates a magnetic field that links the detection coil are provided.
An auxiliary coil that is vibrated together with the first diaphragm during a sounding operation in which the diaphragm vibrates, and a current circuit including the detection coil and the auxiliary coil are provided.
When the second diaphragm is vibrated by the sounding operation of the first diaphragm, the induced current generated in the auxiliary coil cancels the induced current generated in the detection coil. Is configured.

In this acoustic device, when the first diaphragm is driven to perform a sounding operation, an induced current is generated in the auxiliary coil which vibrates together with the first diaphragm. When the first diaphragm is driven, the second diaphragm of the sound collector vibrates. At this time, the induced current generated in the detection coil is canceled by the current generated in the auxiliary coil in the current circuit. . Therefore, howling can be suppressed.

Further, it is preferable that the drive coil and the auxiliary coil are attached to the same side of the first diaphragm.

According to this structure, when the second diaphragm is vibrated by the sound from the outside, the first diaphragm is also vibrated together in the same direction. At this time, since the current induced in the auxiliary coil is superimposed on the current induced in the detection coil, the sensitivity of the sound collecting unit as a microphone is increased.

If the drive coil and the auxiliary coil are located in a common magnetic circuit, the magnetic circuit can be easily constructed.

Further, it is preferable that the drive coil, the detection coil and the auxiliary coil have the same winding direction, and the directions of magnetic fields interlinking the drive coil, the detection coil and the auxiliary coil are the same.

Further, for example, the drive coil and the auxiliary coil are connected in series or in parallel in the current circuit.

However, in addition to the drive coil and the auxiliary coil, a transistor, a resistor and other electronic elements are combined in the current circuit so that the induced currents of the drive coil and the auxiliary coil are canceled during the sounding operation. You may comprise.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a sectional view of an audio device showing an embodiment of the invention, FIGS. 2 and 3 show an example of a current circuit including a detection coil and an auxiliary coil, and A is a speaker. B functions as a microphone.

The audio device 1 shown in FIG. 1 has a frame 2. The frame 2 is formed by injection molding using a synthetic resin material or die casting molding using an aluminum alloy, a zinc alloy, or the like.

In the illustrated embodiment, the frame 2 is formed of a synthetic resin material into a dish shape, and an opening 2A having a large inner diameter is formed in the center.
A concave lower yoke 3 made of a magnetic material is fitted in the opening 2A. In this embodiment, the frame 2 and the lower yoke 3 form a support. A sound producing section A and a sound collecting section (microphone) B are provided on the support.

A small-diameter opening 3A is formed in the center of the lower yoke 3, and a microphone case (center pole) 4 is attached to the opening 3A. The microphone case 4 is formed of a synthetic resin material or a non-magnetic metal material in a tubular shape.

In the sound producing section, the support is provided with the first diaphragm 11. The diaphragm 11 is formed of a paper material, a laminated material of a paper material and a resin film, a paper material impregnated with a resin, or the like. An outer peripheral edge 11a of the diaphragm 11 is fixed to an upper surface of a step portion 2B formed on an outer peripheral portion of the frame 2. Further, a hole is opened at the center of the diaphragm 11, and an inner peripheral edge 11b around the hole is fixed to the outer peripheral surface on the front side of the microphone case 4 to form the diaphragm. 11 is vibratably supported.

A cylindrical bobbin 13 extending in the Z2 direction in the figure is fixed to the lower surface of the diaphragm 11, and a drive coil C1 is wound around the outer peripheral surface thereof. A tubular bobbin 12 concentric with the bobbin 13 is fixed to the inner peripheral side of the bobbin 13, and an auxiliary coil C0 is wound around the bobbin 12.

On the outer periphery of the microphone case 4, a ring-shaped permanent magnet 5 and an upper yoke 6 made of a magnetic material are fitted in a stacked state. The permanent magnet 5 is magnetized to have magnetic poles whose upper surface side and lower surface side are opposite to each other. For example, the Z1 side in the figure is magnetized as the N pole and the Z2 side in the figure is magnetized as the S pole. The outer peripheral surface of the upper yoke 6 and the lower yoke 3
A driving gap G1 is formed between the inner peripheral surface of the bobbin 13 and the inner surface thereof, and the bobbin 13 and the driving coil C1, and the bobbin 12 and the auxiliary coil C0 are located.

The magnetic field generated by the permanent magnet 5 is from the upper yoke 6 to the lower yoke 3 in the gap G1.
A magnetic circuit is formed to reach the inner surface of the outer peripheral part of the magnetic field. In this magnetic circuit, magnetic fields in the same direction are linked to the drive coil C1 and the auxiliary coil C0. The winding directions of the drive coil C1 and the auxiliary coil C0 are the same.

In this embodiment, the permanent magnet 5, the upper yoke 6, the gap G1, the driving coil C1 and the lower yoke 3 constitute a magnetic driving portion which serves as a vibration generating portion. The magnetic drive section and the diaphragm 11 constitute a sounding section A. Further, the permanent magnet 5, the upper yoke 6, the gap G1, the auxiliary coil C0, and the lower yoke 3 constitute an auxiliary magnetic drive unit for preventing howling.

A sound collecting section B which functions as a microphone is provided in the microphone case 4. This sound collection part B
The cup-shaped inner yoke 7 is fixed, and the lower surface of the cylindrical permanent magnet 8 is closely fixed to the center of the bottom surface thereof. A disk-shaped opposed yoke 9 is fixed to the upper surface of the permanent magnet 8. Both the inner yoke 7 and the counter yoke 9 are made of a magnetic material. On the inner peripheral surface of the upper end of the inner yoke 7, a protruding portion 7a is formed which protrudes toward the center toward the opposing yoke 9, and is provided between the protruding portion 7a and the side surface of the opposing yoke 9 for detection. G2 is formed. A magnetic circuit for detection is formed by the inner yoke 7, the permanent magnet 8 and the opposing yoke 9.

A second diaphragm 21 having a substantially W-shaped cross section is provided inside the microphone case 4, and an outer edge portion of the second diaphragm 21 is circumferentially formed on an inner wall of the microphone case 4. Is stuck to. A cylindrical bobbin 22 is fixed to the center of the second diaphragm 21, and a detection coil C2 is wound around the outer peripheral surface of the bobbin 22. And
The second bobbin 22 having the detection coil C2 is housed in the gap G2.

The permanent magnet 8, the opposing yoke 9, the gap G2, the detecting coil C2 and the inner yoke 7 constitute a magnetic detecting portion, and the magnetic detecting portion and the second vibrating plate 21 are provided.
And constitute the sound collecting unit B. In this embodiment, the driving gap G1 and the detection gap G2 are used.
Thus, the magnetic field direction is the same, and the detection coil C2 is wound in the same direction as the drive coil C1 and the auxiliary coil C0.

The detection coil C2 and the auxiliary coil C0 are located in the same current circuit. For example, the coils C2 and C0 are connected in series as shown in FIG. 2, or are connected in parallel as shown in FIG.

Further, at the stepped portion 2B of the frame 2, the resonance plate 3 which covers the first vibration plate 11 and the second vibration plate 21.
1 is fixed. The resonance plate 31 is provided with a plurality of holes.

The operation of the above acoustic device will be described below. When an audio signal is given to the drive coil C1 of the sounding section A, the first diaphragm 11 is vibrated and driven in the Z direction in the drawing by the electromagnetic force generated by the magnetic flux linking the drive coil C1 and the current flowing in the drive coil C1. Sound corresponding to the audio signal is generated from the first diaphragm 11 forward (Z1 direction).

At this time, the sound pressure emitted forward from the first vibrating plate 11, that is, the vibration due to the density of air in the front space, is given to the second vibrating plate 21 to generate the second vibration. The plate 21 is vibrated. Then, the current I1 is induced in the detection coil C2 that vibrates together with the second diaphragm 21. 2A and 3A, the direction of the current I1 at a certain point of time is indicated by an arrow.

However, when the first diaphragm 11 is vibrated, the auxiliary coil C0 vibrates together with it.
A current I0 flows to the. The amplitude direction of the vibration of the first diaphragm 11 and the amplitude direction of the vibration of the second diaphragm 21 are opposite to each other, and the phases of the vibrations of both diaphragms 11 and 21 are different by 180 degrees. Therefore, as shown in FIG. 2A or FIG. 3A, the current I0 generated in the auxiliary coil C0 has a direction to cancel the current I1 induced in the detection coil C2. Therefore, even if the first diaphragm 11 is driven to produce a sound and the second diaphragm 21 is driven by the sound pressure, current does not substantially flow from the detection coil C2, and thus howling can be prevented.

It should be noted that the number of turns of the detection coil C2 depends on the difference in the magnetic field strength between the permanent magnets 5 and 8 and the difference in the gap distance between the driving gap G1 and the detection gap G2. By adjusting the ratio of the number of turns of the coil C0, it is possible to almost cancel the currents I0 and I1.

Next, when sound is generated in the space in front of the resonance plate 31 (Z1 side), the sound wave is transmitted to the inside through the hole of the resonance plate 31, and the sound collection section B in the microphone case 4 is exposed. The second diaphragm 21 is vibrated and operates as a microphone.

At this time, the detection current I2 is induced in the detection coil C2 by the vibration of the second diaphragm 21 of the sound collecting section B. 2B and 3B, the direction of the current I2 at a certain time point is indicated by an arrow. When the second diaphragm 21 is vibrated by the sound pressure from the outside, the first diaphragm 11 is also vibrated by the sound pressure. At this time, the phase of vibration of the first diaphragm 11 and the phase of vibration of the second diaphragm 21 are the same. Therefore, as shown in FIGS. 2B and 3B, the direction of the current I3 induced in the auxiliary coil C0 is the same as the direction I2 induced in the detection coil C2.

Therefore, the detection sensitivity of the sound collecting unit B when functioning as a microphone is amplified, and detection with high sensitivity is possible.

In the above embodiment, the drive coil C
1 and the auxiliary coil C0 are different bobbins 12, 1
However, the present invention is not limited to this, and one bobbin has the drive coil C1.
The auxiliary coil C0 and the auxiliary coil C0 may be provided.

[0040]

As described above, according to the present invention, when functioning as a speaker, the current induced in the auxiliary coil of the sound-producing section cancels the current induced in the detection coil of the sound-collecting section. Since the vibration of the diaphragm can be suppressed, it is possible to prevent howling from occurring.

Further, when functioning as a microphone, the detection sensitivity of the entire acoustic device can be amplified by the current induced in the auxiliary coil of the sound producing section and the current induced in the detection coil of the sound collecting section. Good detection is possible.

[Brief description of drawings]

FIG. 1 is a sectional view of an audio device showing an embodiment of the invention.

FIG. 2 shows a circuit configuration of a detection coil and an auxiliary coil, where A is a speaker and B is a microphone.

FIG. 3 shows a circuit configuration of a detection coil and an auxiliary coil, where A is a speaker and B is a microphone.

[Explanation of symbols]

1 audio equipment 2 frames 3 Lower yoke 4 microphone case 5 permanent magnets 6 Upper yoke 7 Internal yoke 8 permanent magnets 9 Opposing yoke 11 First diaphragm 12 bobbins 13 bobbins 21 Second diaphragm C0 auxiliary coil C1 drive coil C2 detection coil 31 resonance plate A pronunciation department B sound collector

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H04R 9/08 H04R 9/08

Claims (5)

[Claims] 1. An audio device in which a support is provided with a sound producing section for producing a sound and a sound collecting section operated by a sound pressure generated outside, wherein the sound producing section has a first sound producing section. A diaphragm, a drive coil that vibrates the first diaphragm, and a magnetic circuit that generates a magnetic field that links the drive coil, and the sound collecting unit includes a second diaphragm for collecting sound. And a magnetic circuit that generates a magnetic field that links the detection coil and the detection coil that operates together with the second diaphragm, and the first diaphragm is vibrated when the sounding operation is performed. An auxiliary coil vibrated together with the diaphragm and a current circuit including the detection coil and the auxiliary coil are provided, and the second diaphragm is vibrated by the sounding operation of the first diaphragm. Sometimes the auxiliary coil The acoustic device is characterized in that the current circuit is configured such that the induced current generated cancels the induced current generated in the detection coil. 2. The drive coil and the auxiliary coil are mounted on the same side of the first diaphragm.
The acoustic device described. 3. The acoustic device according to claim 2, wherein the drive coil and the auxiliary coil are located in a common magnetic circuit. 4. The sound according to claim 2, wherein the drive coil, the detection coil and the auxiliary coil have the same winding direction, and the directions of magnetic fields interlinking the drive coil, the detection coil and the auxiliary coil are the same. apparatus. 5. The drive coil and the auxiliary coil are connected in series or in parallel in the current circuit.
The acoustic device according to any one of 1 to 4.