JP2017183859A - Microphone - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a microphone usable also as a bone conduction microphone that is operable as a unidirectional microphone when utilized as an air conduction type microphone.SOLUTION: A microphone comprises: a unit case 4 in which an electrostatic type acoustic/electric converter formed by disposing a stationary electrode 9 supported by an elastic support 10 oppositely to a diaphragm 7 and forming an opening 9a in the stationary electrode; a front plate 3 which is disposed at a front side of the unit case and configured to open/close a front acoustic terminal hole 4a that is formed in the unit case; a back plate 5 which is disposed at a back side of the unit case and configured to open/close a rear acoustic terminal hole 4b formed in the unit case; and a microphone case 2 in which the front plate and the back plate are accommodated at a front side and a rear side of the unit case when the unit case is defined as a center.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a microphone that can be selectively used as an air conduction microphone that collects sound waves that travel in the atmosphere and a bone conduction microphone that collects bone conduction sound that travels to the human body.

When using a dynamic or condenser air-conduction microphone where there is a lot of ambient noise, the speaker's voice is masked by the noise. It becomes difficult.
In such a case, a bone conduction microphone that picks up bone conduction sound transmitted to the human body is effective, but according to this bone conduction microphone, the high frequency is attenuated by the elasticity of the human body. The intelligibility tends to decrease.

  Therefore, the present applicant has already proposed a microphone whose function can be switched between an air conduction microphone and a bone conduction microphone according to the level of ambient noise, which is disclosed in Patent Document 1. Has been.

According to the microphone disclosed in Patent Document 1, the bone conduction material is made of an elastic material having an air chamber of a predetermined capacity inside, a front portion thereof being closed as a contact surface with respect to the human body, and an output hole in the rear portion. The movable air chamber portion and the movable air chamber portion are supported by an elastic support body, and a microphone housing having an acoustoelectric converter is provided inside.
When the movable air chamber portion is brought into contact with the human body, the movable air chamber portion is brought into close contact with the microphone housing by the contact pressure, and the air chamber of the movable air chamber portion is the acoustic terminal of the acoustoelectric converter. Communicated with This functions as a bone conduction microphone.

Further, in a state where the movable air chamber portion is not in contact with the human body, the movable air chamber portion is separated from the microphone casing by the action of the elastic support member, so that the acoustic wave propagating in the atmosphere is transmitted to the acoustoelectric transducer. This acts as an air conduction microphone.
Therefore, the bone conduction microphone and the air conduction microphone can be selectively used depending on whether or not the movable air chamber is in contact with the human body.

Japanese Patent No. 5075676

  By the way, according to the microphone disclosed in Patent Document 1, the acoustoelectric converter in the microphone casing is housed in the unit case with the back surface of the diaphragm sealed, and thus is used as an air conduction microphone. When used, it functions as an omnidirectional microphone. Therefore, there is a drawback that it is easy to capture ambient noise.

Further, when the microphone disclosed in Patent Document 1 is used as a bone conduction microphone, the movable air chamber portion is pressed against the human body, so that the air in the movable air chamber portion directly acts on the front surface of the diaphragm. This causes a problem that the diaphragm is greatly displaced.
Therefore, assuming that a condenser microphone unit is used as the acoustoelectric converter, not only does the diaphragm come into contact with the fixed pole to generate a large noise, but in extreme cases, the diaphragm is damaged or the diaphragm is This also causes creep (plastic deformation) that does not return to the above state.
In order to avoid such a situation, it is necessary to take another measure such as connecting the front and rear of the diaphragm at a low frequency (for example, making a hole in the diaphragm).

  The present invention has been made in order to solve the above-mentioned technical problems of conventional microphones, and when used as an air conduction microphone, it can be operated as a unidirectional microphone to further reduce noise. In the case of using as a bone conduction microphone, a microphone that can prevent generation of large noises due to excessive displacement of the diaphragm or damage to the diaphragm is provided. is there.

  A microphone according to the present invention includes a unit case in which a fixed pole supported by an elastic support is disposed opposite to a diaphragm, and an electrostatic acoustoelectric transducer having an opening formed in the fixed pole is accommodated. And a front plate disposed on the front side of the unit case for opening and closing a front acoustic terminal hole formed on the unit case, and disposed on the back side of the unit case and formed on the unit case. When a back plate that opens and closes a rear acoustic terminal hole, and a microphone case that houses the front plate and the back plate before and after the unit case with the unit case in the center, when selecting the function of the bone conduction microphone, A front acoustic terminal hole and a rear acoustic terminal hole formed in the unit case are provided on the front plate and the rear plate. Sealed by preparative, when selecting a function of the air conduction microphone is characterized in that the sealing of the front formed in the unit case acoustic terminal holes and rear acoustic terminal holes is solved.

  In this case, as an embodiment of the present invention, the natural vibration frequency of the fixed pole via the elastic support and the natural vibration frequency of the diaphragm are the same.

  In one embodiment of the present invention, the front plate and the back plate are each provided with a sound hole, and when the function of the air conduction microphone is selected, the front sound formed in the unit case is formed. When the terminal hole and the rear acoustic terminal hole communicate with the outside through the sound holes formed in the front plate and the back plate and the function of the bone conduction microphone is selected, the front portion formed in the unit case The acoustic terminal hole and the rear acoustic terminal hole are configured to be sealed on a surface of the front plate and the back plate where the sound passage hole is not formed.

  Further, with the unit case at the center, the front plate and the back plate are connected to each other through a connecting member before and after the unit case, and the connected front plate, unit case, and back plate have an opening at the bottom. A configuration accommodated in a bottom cylindrical microphone case is employed.

  In this case, it is desirable that the back plate is disposed on the bottom side of the microphone case and the front plate is disposed on the open side of the microphone case, thereby selecting the function of the bone conduction microphone, The front plate arranged on the opening side functions as a contact part to the human body.

According to the microphone configured as described above, the front plate and the rear plate are brought into close contact with both sides of the central unit case by holding the microphone case and pressing the front plate disposed on the opening side of the microphone case against the human body, for example. To do. Thereby, the front acoustic terminal hole and the rear acoustic terminal hole formed on both surfaces of the unit case are sealed by the front plate and the rear plate.
Since the fixed pole in the unit case is supported by the elastic support and has an inertial mass, the vibration on the unit case and the diaphragm side accompanying bone conduction is output as a change in capacitance, and the bone Functions as a conduction microphone.

  In addition, by releasing the pressing of the front plate against the human body, the front acoustic terminal hole and the rear acoustic terminal hole formed on both sides of the unit case have their respective sound passage holes formed on the front plate and the rear plate. It communicates with the outside through. Thus, the acoustoelectric converter in the unit case functions as an air conduction type unidirectional microphone unit, and can provide a microphone that is less susceptible to noise.

In this case, since the natural vibration frequency of the fixed pole via the elastic support and the natural vibration frequency of the diaphragm facing the fixed pole are set to coincide with each other, in response to the acceleration applied to the unit case, Relative movement of the fixed pole and the diaphragm is suppressed.
Therefore, in the state of operating as a unidirectional microphone, the generation of vibration noise caused by vibration applied to the microphone can be effectively suppressed.

It is sectional drawing which shows the state which made the microphone which concerns on this invention contact | abut to a human body, and was made to function as a bone-conduction type | mold microphone. It is sectional drawing which shows the state similarly separated from the human body and functioning as an air conduction type microphone.

A microphone according to the present invention will be described based on an embodiment shown in the drawings.
The microphone 1 according to the present invention is constituted by a bottomed cylindrical microphone case 2 whose outer shell is relatively shallow, and the opening 2a of the short-axis microphone case 2 has a human body H (particularly bone conduction sound). 1 functions as a bone conduction microphone as shown in FIG. 1, and the opening 2a is separated from the human body H as an air conduction microphone as shown in FIG. Function.
An opening 2c as a circular sound passage hole having a relatively large diameter is formed at the center of the bottom 2b of the microphone case 2.

  In the microphone case 2, a disk-shaped rear plate 5, a cylindrical unit case 4, and a disk-shaped front plate are accommodated in this order from the bottom 2b of the microphone case 2 toward the opening 2a. . Between each of the back plate 5, the unit case 4, and the front plate 3, a connecting member 6 is attached at the peripheral portion thereof, and these three members constitute a connecting body that can be expanded and contracted in the axial direction. The back plate 5 is attached to the bottom 2b of the microphone case 2 by using means such as adhesion.

When the connecting member 6 functions as an air conduction microphone as shown in FIG. 2, a space is formed between each of the front plate 3, the unit case 4, and the back plate 5. Power is held.
The front plate 3 is provided with a plurality of sound passage holes 3a at equal intervals along the circumference, and the back plate 5 is also provided with a plurality of sound passage holes 5a at equal intervals along the circumference. It is installed.

A vibration plate 7 is disposed on the front side of the unit case 4, and the vibration plate 7 is stretched around a predetermined tension by a circular support ring 8.
A fixed pole 9 is disposed on the back side of the diaphragm 7 so as to face the diaphragm 7. The fixed pole 9 is attached to the inner surface of a cylindrical support 11 through a ring-shaped elastic support 10 at the periphery. The cylindrical support 11 is attached along the inner peripheral surface of the unit case 4, and the front end edge is in contact with the support ring 8, thereby positioning the diaphragm 7 and the fixed pole 9.
The fixed pole 9 has a plurality of openings 9a formed at equal intervals along the circumference.

  Each member of the diaphragm 7, the support ring 8, the fixed pole 9, the elastic support body 10, and the cylindrical support body 11 constitutes an electrostatic acoustoelectric converter. And this electrostatic acoustoelectric converter comprises an electret dielectric microphone on either one of the diaphragm 7 or the fixed pole 9 to constitute an electret condenser microphone.

An opening 4a is formed at the front center of the unit case 4, and this opening 4a constitutes a front acoustic terminal hole of the electrostatic acoustoelectric transducer. An opening 4b is formed in the center of the back surface of the unit case 4, and this opening 4b constitutes a rear acoustic terminal hole of the electrostatic acoustoelectric transducer.
The acoustic resistor 12 is attached to the inner side surface of the opening 4b constituting the rear acoustic terminal hole so as to close the opening 4b.

As an embodiment of the present invention, the natural vibration frequency of the fixed pole 9 disposed in the unit case 4 via the elastic support 10 and the diaphragm 7 to which a predetermined tension is applied by the support ring 8 are provided. The natural vibration frequencies are set so as to substantially match.
In this case, the mass ratio between the fixed pole 9 and the diaphragm 7 is 1000> 1, and therefore, by adjusting the compliance of the elastic support 10 according to the mass ratio and the tension applied to the diaphragm 7 by the support ring 8, The natural vibration frequency can be adjusted.

  In the microphone 1 configured as described above, the front plate 3 disposed on the side of the opening 2 a of the microphone case 2 comes into contact with the human body H by pressing the opening 2 a of the microphone case 2 against the human body H. Thereby, the front plate 3 is pushed into the microphone case 2 while bending the connecting member 6 together with the unit case 4, and the microphone 1 functions as a bone conduction microphone as shown in FIG.

  According to the bone conduction microphone shown in FIG. 1, the front plate 3 and the back plate 5 are in close contact with each other with the unit case 4 in the center in the microphone case 2. Accordingly, the front acoustic terminal hole 4a formed in the unit case 4 is sealed by the central sealing surface 3b where the sound passage hole 3a in the front plate 3 is not drilled. Further, the rear acoustic terminal hole 4b formed in the unit case 4 is sealed by a central sealing surface 5b where the sound passage hole 5a in the back plate 5 is not formed.

  When the front acoustic terminal hole 4a formed in the unit case 4 is sealed by the front plate 3, the stiffness of the air chamber formed between the front surface of the diaphragm 7 and the unit case 4 becomes dominant. Even if acceleration is applied to the unit case 4, the vibration of the diaphragm 7 with respect to the unit case 4 can be suppressed. That is, the diaphragm 7 is integrated with the unit case 4.

On the other hand, the fixed pole 9 is supported by the elastic support 10 in the unit case 4 and has an inertial mass, and the fixed pole 9 has an opening 9a. As shown in FIG. 7, the vibration is not suppressed by the stiffness with respect to the unit case 4.
Accordingly, the microphone 1 at this time receives vibration due to bone conduction from the human body H, and the diaphragm 7 together with the unit case 4 vibrates relative to the stationary fixed pole 9. A change in electrostatic capacitance generated between the diaphragm 7 and the fixed pole 9 due to the relative vibration becomes an output from the bone conduction microphone.

  On the other hand, when the pressing of the front plate 3 against the human body H is released, the front plate 3 and the unit case 4 move from the inside of the microphone case 2 toward the outside of the opening 2a via the connecting member 6. Thereby, the microphone 1 functions as an air conduction type microphone as shown in FIG.

According to the configuration shown in FIG. 2, spaces S1 and S2 are formed between the unit case 4 and the front plate 3, and between the unit case 4 and the back plate 5, respectively. Therefore, the front acoustic terminal hole 4a formed in the front surface of the unit case 4 communicates with the outside through the sound hole 3a formed in the front plate 3 through the space S1 as indicated by the arrow.
Further, the rear acoustic terminal hole 4b formed on the back surface of the unit case 4 has a sound passage hole 5a formed in the back plate 5 and an opening formed in the microphone case 2 through the space S2, as indicated by an arrow. It communicates with the outside through the hole 2c.

Therefore, the acoustoelectric converter in the microphone case 2 functions as an air conduction type unidirectional microphone unit in which the rear acoustic terminal hole 4b is opened, and can be used as a microphone that is hardly affected by noise.
In this case, since the natural vibration frequency of the fixed pole 9 through the elastic support 10 and the natural vibration frequency of the diaphragm 7 facing the fixed pole 9 are set to coincide with each other, the acceleration applied to the unit case 4 Thus, the relative movement of the fixed pole 9 and the diaphragm 7 is suppressed, and the generation of vibration noise can be effectively prevented.

DESCRIPTION OF SYMBOLS 1 Microphone 2 Microphone case 2a Opening opening 2b Bottom part 2c Opening 3 Front plate 3a Sound passage hole 3b Sealing surface 4 Unit case 4a Opening (front acoustic terminal hole)
4b Opening (rear acoustic terminal hole)
DESCRIPTION OF SYMBOLS 5 Back plate 5a Sound passage hole 5b Sealing surface 6 Connection member 7 Diaphragm 8 Support ring 9 Fixed pole 9a Opening 10 Elastic support body 11 Cylindrical support body 12 Acoustic resistance body H Human body S1, S2 Space

Claims (5)

A unit case that accommodates an electrostatic acoustoelectric transducer having a fixed pole supported by an elastic support and facing the diaphragm, and having an opening formed in the fixed pole;
A front plate disposed on the front side of the unit case and opening and closing a front acoustic terminal hole formed in the unit case;
A back plate disposed on the back side of the unit case to open and close a rear acoustic terminal hole formed in the unit case;
A microphone case that houses the front plate and the back plate before and after the unit case in the center,
When the function of the bone conduction microphone is selected, the front acoustic terminal hole and the rear acoustic terminal hole formed in the unit case are sealed by the front plate and the rear plate, and the air conduction microphone When the function is selected, the front acoustic terminal hole and the rear acoustic terminal hole formed in the unit case are unsealed.   The microphone according to claim 1, wherein the natural vibration frequency of the fixed pole via the elastic support and the natural vibration frequency of the diaphragm are matched. The front plate and the rear plate have sound holes, respectively. When the function of the air conduction microphone is selected, the front acoustic terminal hole and the rear acoustic terminal hole formed in the unit case are And communicate with the outside through the sound holes formed in the back plate,
When the function of the bone conduction type microphone is selected, the front acoustic terminal hole and the rear acoustic terminal hole formed in the unit case are sealed with the surface where the sound passage hole is not formed in the front plate and the rear plate. The microphone according to claim 1 or 2, wherein   A bottomed cylinder having the unit case in the center, the front plate and the back plate connected to each other through a connecting member before and after the unit case, and the connected front plate, unit case, and back plate having an opening at the bottom The microphone according to any one of claims 1 to 3, wherein the microphone is housed in a shaped microphone case.   When the back plate is disposed on the bottom side of the microphone case, the front plate is disposed on the open mouth side of the microphone case, and the function of the bone conduction microphone is selected, the front plate disposed on the open mouth side is The microphone according to claim 4, wherein the microphone is at a contact portion with a human body.

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