JP2013192030A - Condenser microphone unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a condenser microphone unit that can continuously adjust directivity.SOLUTION: A condenser microphone unit 1 is constituted by housing a diaphragm assembly 20, formed by arranging a diaphragm 22 and a fixed electrode 24 opposite each other with a spacer member 23 interposed, in a unit case 10. The diaphragm assembly 20 has a sound passage formed extending from a rear acoustic terminal hole 27a to a back side of the diaphragm 22, and an acoustic resistance material 26 is disposed at a part of the sound passage. A lock member 33 whose tip portion compresses the acoustic resistance material 26 is disposed in the rear acoustic terminal hole 27a, and the lock member 33 has a lock portion 33b which is knocked down in a reverse hook shape while inserted into the rear acoustic terminal hole from the back side and locked to an inner surface of the acoustic terminal hole to stop the lock member from coming out to the back side.

Description

  The present invention relates to a condenser microphone unit in which directivity can be continuously adjusted individually by adjusting an acoustic resistance disposed in the vicinity of a rear acoustic terminal.

The unidirectional condenser microphone is configured to incorporate a bi-directional component into the back surface of the diaphragm via an acoustic resistor disposed near the rear acoustic terminal. In this case, the microphone is adjusted closer to omnidirectional if the acoustic resistance of the acoustic resistor is high, and is adjusted closer to bidirectional if the acoustic resistance of the acoustic resistor is low.
In many of the condenser microphone units (hereinafter sometimes referred to simply as “microphone units”), a diaphragm assembly in which a diaphragm and a fixed pole are combined to face each other via a spacer member is made of metal. A configuration housed in the unit case is employed.

  In this case, in the electret type model, a circuit board (PCB) is arranged on the rear end side of the unit case, and an FET (field effect transistor) functioning as an impedance converter is mounted. The rear end of the unit case is caulked inward to fix the diaphragm assembly in the unit case, and a part of the unit case is connected to the reference potential point (earth line) of the circuit board by the caulking. It is composed.

  In the unidirectional microphone unit, as described above, in addition to the front acoustic terminal, a rear acoustic terminal is provided in order to cause sound waves from the sound source to act on the back side of the diaphragm. For example, in most cases, an opening as a rear acoustic terminal is formed in the circuit board because the cost is high when the opening is formed on the side surface of the unit case by, for example, pressing. I am doing so. A unidirectional condenser microphone unit according to the example will be described with reference to FIGS.

FIG. 5 is an exploded cross-sectional view showing a part of the microphone unit, and FIG. 6 is a cross-sectional view showing a state in which the microphone unit is assembled to adjust the acoustic resistance of the rear acoustic terminal in the microphone unit. It is sectional drawing explaining a means.
In the drawings described below, parts that perform the same function are indicated by the same reference numerals. However, in some drawings, representative parts are indicated by reference numerals for convenience of space, and other reference numerals are indicated. Sometimes omitted.

As shown in FIG. 5, this unidirectional microphone unit has an opening 11 constituting a front acoustic terminal on the front side facing the sound source, and the rear side is opened in a cylindrical shape to constitute a rear acoustic terminal. For example, the unit case 10 made of an aluminum material is provided, and the diaphragm assembly 20 is accommodated in the unit case 10. The diaphragm 22 constituting the diaphragm assembly 20 is attached to the diaphragm support ring 21 with a predetermined tension, and is disposed immediately after the opening 11 constituting the front acoustic terminal.
A ring-shaped spacer member 23 is disposed on the back side of the diaphragm 22, and a fixed pole 24 is disposed so as to face the diaphragm 22 through the spacer member 23.

When the microphone unit is of the electret type, an electret film (not shown) that has been subjected to polarization treatment is attached to the surface of the fixed pole 24 that faces the diaphragm 22.
The fixed pole 24 is supported by an insulating insulator 25, and a ring-shaped acoustic resistance material 26 is accommodated in an annular recess 25a formed on the back side of the insulator 25. A circuit board (PCB) 27 is attached to the back surface of the insulator 25 so as to cover the acoustic resistance material 26.

  Then, by caulking the rear opening edge 12 of the unit case 10 inward, the diaphragm assembly 20 is held by the unit case 10 as shown in FIG. Is connected to a reference potential point (earth line) formed on the circuit board 27.

  A plurality of rear acoustic terminal holes 27a provided in the circuit board 27, a through hole 25b provided so as to penetrate the insulator 25, an air chamber 25c secured on the front side of the insulator 25, and the fixed A sound passage communicating with the back surface of the diaphragm 22 is formed by a through hole 24 a provided in the pole 24. The acoustic resistance material 26 is disposed in a part of the sound path.

  In addition, an FET (field effect transistor) 28 that functions as an impedance converter is accommodated in a space formed at the center of the insulator 25, and one terminal of the FET 28 is connected to the fixed pole 24. In addition, the other terminal of the FET 28 is connected to the circuit board 27 by soldering or the like.

In the conventional microphone unit 1 described above, in order to adjust the directivity, the acoustic resistance of the rear acoustic terminal is adjusted. In this case, normally, as shown in FIG. 6, a plurality of rear acoustic terminal holes 27a are selectively provided by affixing a sealing material or acoustic resistance material 31 to the rear acoustic terminal holes 27a provided in the circuit board 27. A means for closing is adopted.
However, the directivity adjustment by the above-described means is performed in stages according to the number of the plurality of rear acoustic terminal holes 27a, and fine adjustment, that is, direct adjustment of directivity is impossible.

  Therefore, one disc-shaped acoustic resistance material that can cover all the rear acoustic terminal holes 27a is provided, and the pressure contact force to the rear acoustic terminal holes 27a by the disc-shaped acoustic resistance material can be adjusted. The proposed microphone unit has also been proposed, and is described in Patent Documents 1 and 2 shown below.

  However, according to the microphone units described in Patent Documents 1 and 2, as a means for adjusting the pressure contact force of the acoustic resistance material, the center portion of the insulator 25 is provided with a male screw shaft that protrudes from the back surface, and is screwed into the male screw shaft. The internal threaded nut requires a configuration in which the acoustic resistance material is pressed from the back, and this configuration raises the manufacturing cost and increases the size of the entire microphone unit.

JP 2006-115251 A JP 2010-288047 A

  The present invention has been made paying attention to the problems of the conventional microphone unit described above, and solves the problem of the above-mentioned increase in manufacturing cost and the problem that the entire microphone unit is enlarged, and directivity. It is an object of the present invention to provide a condenser microphone unit that can adjust continuously.

  The condenser microphone unit according to the present invention, which has been made to solve the above-described problems, includes a diaphragm in a unit case having a front acoustic terminal on the front side facing the sound source and a rear acoustic terminal on the rear side. And a fixed electrode and a condenser microphone unit in which a diaphragm assembly formed by facing a spacer through a spacer member is accommodated, and the diaphragm assembly includes a rear acoustic terminal hole and a rear surface of the diaphragm. A sound path leading to the side is formed, an acoustic resistance material is disposed in a part of the sound path, and the rear acoustic terminal hole is inserted into the rear acoustic terminal hole, and a tip portion thereof is A locking member for compressing the acoustic resistance material is provided.

  In this case, in a preferred embodiment, the locking member is formed in a reverse hook shape in a state of being inserted into the rear acoustic terminal hole from the back side, and is locked to the inner side surface of the acoustic terminal hole. It is desirable that a locking portion for preventing the rear side from slipping out is formed.

In a more preferred embodiment, a configuration in which the diaphragm assembly is held in the unit case by caulking the rear opening edge of the unit case inward is employed.
In addition, a configuration in which a circuit board is disposed on the back side of the diaphragm assembly and a plurality of rear acoustic terminal holes are formed in the circuit board can be suitably employed.

  Further, according to one preferable mode of the locking member, the plurality of short fibers are planted on the outer peripheral surface of the shaft body, and the plurality of the locking members are inserted from the back side into the rear acoustic terminal hole. The short fibers fall in an inverted saddle shape to constitute the locking portion.

  According to another preferable embodiment of the locking member, the locking member is entirely formed of a soft material such as a rubber material, and the locking portion has a sawtooth shape in an axial cross-sectional shape. However, a large number is formed in the axial direction along the peripheral side surface.

  According to the above-described condenser microphone unit according to the present invention, the acoustic resistance is arranged in the sound path where the front end of the locking member reaches the back side of the diaphragm by inserting the locking member into the rear acoustic terminal hole. Operates to compress the material. Thereby, the acoustic resistance of the acoustic resistance material is adjusted, and the directivity of the microphone unit can be adjusted.

  The locking member inserted into the rear acoustic terminal hole is formed in a reverse hook shape in a state of being inserted into the rear acoustic terminal hole from the back side, and is locked to the inner side surface of the acoustic terminal hole and back side A locking portion for preventing the slipping out is formed. Accordingly, the degree of compression of the acoustic resistance material can be adjusted according to the degree of pushing of the locking member into the rear acoustic terminal hole, whereby the microphone unit can obtain appropriate directivity.

  And in the state which adjusted the pushing degree of the said locking member, and obtained appropriate directivity, the remaining part of the back side of the said locking member is cut | disconnected using a nipper etc., for example, The said locking member Can be prevented from being pushed further, and the appropriate directivity of the adjusted microphone unit can be maintained.

  Moreover, the locking member can use, for example, an electrostatic flocking (floky process) of a number of short fibers on the outer peripheral surface of the shaft body made of synthetic resin. Since it can be used while being cut, it is possible to solve the problem of manufacturing cost and the problem that the whole unit is enlarged as the problem to be solved by the invention.

It is sectional drawing which showed a mode that the locking member was mounted | worn in the rear acoustic terminal hole of a microphone unit. It is sectional drawing which showed the structure of the microphone unit with which the securing member was mounted | worn. It is the expanded sectional view which showed a mode that the latching member of another structure was mounted | worn in a rear acoustic terminal hole. It is the expanded sectional view which showed a mode that the latching member of another structure was mounted | worn in a rear acoustic terminal hole. It is sectional drawing which partially decomposed | disassembled and showed an example of the conventional microphone unit. It is sectional drawing explaining the means to adjust the acoustic resistance of the microphone unit shown in FIG.

  Hereinafter, a condenser microphone unit according to the present invention will be described based on an embodiment shown in the drawings. The microphone unit used in the embodiment of the present invention employs the same configuration as the microphone unit already described with reference to FIG. Therefore, a detailed description of the basic configuration of the microphone unit is omitted.

As already described, the microphone unit 1 shown in FIG. 1 has a sound path extending from the plurality of rear acoustic terminal holes 27a to the back side of the diaphragm 22. Then, the acoustic resistance material 26 formed in a ring shape is accommodated in the annular recess 25a of the insulator 25 so as to be in contact with the circuit board 27 in which the rear acoustic terminal hole 27a is formed.
In this embodiment, the acoustic resistance member 26 is compressed by the distal end portion of the locking member by inserting the locking member locked to the acoustic terminal hole 27a into the rear acoustic terminal hole 27a from the back side. Then, the directivity of the microphone unit 1 is adjusted by controlling the acoustic resistance of the acoustic resistance material 26 formed of a so-called sponge or the like.

  In the embodiment shown in FIGS. 1 and 2, a locking member 33 configured by flocking (flocking) a large number of short fibers (pile) 33 b on the outer peripheral surface of the shaft 33 a is used. Electrostatic flocking is known as one means for flocking a large number of short fibers 33b on the shaft body 33a. In this electrostatic flocking, an adhesive is applied in advance to the surface of the object (shaft body 33a) to be flocked, and short fibers (pile) 33b to be flocked (attached) are arranged on an electrode plate (not shown), A high DC voltage is applied between the object and the electrode plate.

For example, when an anode (positive) potential is applied to the object and a negative (minus) potential is applied to the electrode plate, polarization occurs in the short fiber, and the minus charge of the short fiber is attracted to the object and is planted, The flocked state is mechanically maintained by the curing of the adhesive.
When the above-described electrostatic flocking is used, the top ends of the short fibers implanted have the same polarity (positive potential), so that the top ends of the respective short fibers repel each other, thereby causing each short fiber to repel. Are implanted so as to stand perpendicular to the flocked surface.

  In this case, although the dimension of the locking member 33 is set corresponding to the inner diameter of the rear acoustic terminal hole 27a, the inner diameter of the rear acoustic terminal hole 27a is, for example, 0.5 to 1.0 mm. For example, as the shaft 33a of the locking member 33 inserted into the rear acoustic terminal hole 27a, a synthetic resin material having a diameter of 0.4 to 0.6 mm is used, and the length as the short fiber (pile) 33b is used. The thing of about 0.2-0.3 mm is utilized. And as a raw material of the short fiber (pile) 33b, rayon, polyamide, polyester fiber, etc. can be utilized suitably.

  FIG. 1A shows a state in which the above-described locking member 33 is inserted from the back side of the microphone unit 1 toward the rear acoustic terminal hole 27a. Next, FIG. 1B shows a state in which the distal end portion of the locking member 33 is inserted into the rear acoustic terminal hole 27a. In this state, the distal end portion of the locking member 33 is the acoustic resistance material. 26, and acts to compress the acoustic resistance material 26.

  At this time, the short fibers 33b formed on the shaft body 33a of the locking member 33 are tilted in the reverse direction (rear side) to the insertion direction of the locking member 33 to form a reverse hook shape, and the acoustic terminal hole 27a It functions as a locking portion that is locked to the inner side surface and prevents the locking member 33 from coming out to the back side.

Therefore, the degree of compression received by the acoustic resistance material 26 can be adjusted according to the degree of pushing of the locking member 33 into the rear acoustic terminal hole 27a, whereby the microphone unit 1 obtains proper directivity. Can do.
In addition, although the figure has shown the state which inserts the latching member 33 with respect to one rear acoustic terminal hole 27a, according to the adjustment degree of the directivity of the microphone unit 1, this is the other rear acoustic terminal hole. The locking member 33 is also selectively inserted into 27a as appropriate.

  When proper directivity is obtained by adjusting the degree of pushing of the locking member 33 into the rear acoustic terminal hole 27a, the remaining amount on the back side of the locking member 33 is, for example, as shown in FIG. By cutting with a nipper or the like, the locking member 33 can be prevented from being pushed further into the rear acoustic terminal hole 27a. As a result, the appropriate directivity of the adjusted microphone unit 1 can be maintained, whereby the operational effects as described in the column of the effect of the invention described above can be obtained.

In particular, the present invention can take advantage of the characteristics of the microphone unit having a structure in which the diaphragm assembly is held in the unit case by caulking the rear opening edge of the unit case inward.
That is, in the microphone unit assembled by caulking the rear opening edge of the unit case, the diaphragm assembly cannot be removed from the unit case after assembly. Therefore, if the acoustic resistance of the acoustic resistance material 26 is set high by mistake, it becomes impossible to remove the locking member 33 and readjust the acoustic resistance, and this microphone unit immediately becomes a defective product.

  However, according to the microphone unit according to the present invention, the acoustic resistance can be gradually adjusted according to the degree of insertion of the locking member 33 into the rear acoustic terminal hole 27a, so that there is a problem of readjusting the acoustic resistance. There is no. Therefore, the present invention can be suitably applied to a microphone unit assembled by caulking of a unit case.

Next, FIG. 3 is a partially enlarged cross-sectional view showing a state in which the locking member 35 having the second configuration is mounted in the rear acoustic terminal hole 27a. As the locking member 35 shown in this example, the whole is integrally formed of a soft material such as a rubber material.
That is, the locking member 35 shown in FIG. 3 has a shaft hole 35a formed in the central portion (axial core), and a locking portion 35b formed in a sawtooth shape in the axial direction along the circumferential side surface. Many are formed in the axial direction.

According to the locking member 35 having the above-described configuration, by inserting the locking member 35 into the rear acoustic terminal hole 27a, the distal end portion of the locking member 35 comes into contact with the acoustic resistance material 26 and compresses the acoustic resistance material 26. Act on.
At this time, the locking portion 35b formed in a serrated shape on the locking member 35 is tilted in the reverse direction (rear side) to the insertion direction of the locking member 35 to form a reverse hook shape, and the acoustic terminal hole 27a It acts to be locked to the inner side surface and prevented from coming out to the back side.

  Therefore, the microphone unit 1 can obtain appropriate directivity by adjusting the degree of pushing of the locking member 35 into the rear acoustic terminal hole 27a. In this state, the locking unit 35 can be locked as in the example shown in FIG. The remaining portion on the back side of the member 35 is cut using, for example, a nipper or the like, so that the locking member 35 can be prevented from being further pushed into the rear acoustic terminal hole 27a.

  As a result, similar to the embodiment shown in FIGS. 1 and 2, the appropriate directivity of the microphone unit can be maintained, and the operational effects as described in the column of the effect of the invention can be obtained. .

Next, FIGS. 4A and 4B show third and fourth examples of the locking member, both of which are a single state of the locking member and the locking member in the rear acoustic terminal hole 27a. The state inserted in is shown in a sectional view.
The locking member 36 shown in FIG. 4A is formed in a columnar shape by integrally forming a porous material 36b having open cells around a shaft body 36a made of synthetic resin, for example. In the locking member 36 having this structure, the outer peripheral surface of the porous material 36b integrally formed around the shaft body 36a is locked by friction in the rear acoustic terminal hole 27a. That is, in this example, the outer peripheral surface of the porous material 36b functions as a locking portion.

And the front-end | tip part of the said shaft body 36a containing the porous material 36b contact | abuts to the acoustic resistance material 26, and it acts so that this acoustic resistance material 26 may be compressed.
Also in this example, the microphone unit 1 can obtain appropriate directivity by adjusting the degree of pushing of the locking member 36 into the rear acoustic terminal hole 27a, and the remaining portion on the back side of the locking member 36 can be reduced. For example, by cutting with a nipper or the like, the locking member 36 can be prevented from being further pushed into the rear acoustic terminal hole 27a.

The locking member 37 shown in FIG. 4B shows an example in which the whole is formed in a columnar shape by a porous material having open cells. Also in this locking member 37, the outer peripheral surface of the porous material formed in a columnar shape is locked by friction in the rear acoustic terminal hole 27a. That is, the outer peripheral surface of the porous material functions as a locking portion.
Also in the example shown in FIG. 4B, the microphone unit 1 can obtain appropriate directivity by adjusting the degree of pushing of the locking member 37 into the rear acoustic terminal hole 27a. The same effect as the stop members 33, 35, and 36 can be obtained.

1 Condenser microphone unit 10 Unit case 11 Opening (front acoustic terminal)
12 Rear opening edge (rear acoustic terminal)
DESCRIPTION OF SYMBOLS 20 Diaphragm assembly 21 Diaphragm support ring 22 Diaphragm 23 Spacer member 24 Fixed pole 24a Through-hole 25 Insulator 25a Annular recessed part 25b Through-hole 25c Air chamber 26 Acoustic resistance material 27 Circuit board (PCB)
27a Rear acoustic terminal hole 28 FET (impedance converter)
31 Sealing material (acoustic resistance material)
33 Locking member 33a Shaft body 33b Short fiber (locking part)
35 Locking member 35a Shaft hole 35b Locking portion 36 Locking member 36a Shaft body 36b Porous material 37 Locking member

Claims (6)

A diaphragm having a front acoustic terminal on the front side facing the sound source and a rear case and a rear acoustic terminal in a unit case with a diaphragm and a fixed pole facing each other via a spacer member A condenser microphone unit containing the assembly,
The diaphragm assembly is formed with a sound path from the rear acoustic terminal hole to the back side of the diaphragm, and an acoustic resistance material is disposed in a part of the sound path, and the rear acoustic terminal hole Is a condenser microphone unit comprising a locking member inserted into the rear acoustic terminal hole, the tip of which compresses the acoustic resistance material.   The locking member has a reverse hook shape in a state where it is inserted into the rear acoustic terminal hole from the back side, and is locked to the inner side surface of the acoustic terminal hole to prevent it from coming out to the back side. The condenser microphone unit according to claim 1, wherein a portion is formed.   The condenser microphone unit according to claim 1 or 2, wherein the diaphragm assembly is held in the unit case by caulking a rear opening edge of the unit case inward.   4. The circuit board according to claim 1, wherein a circuit board is disposed on a back side of the diaphragm assembly, and a plurality of rear acoustic terminal holes are formed in the circuit board. 5. Condenser microphone unit.   The locking member is configured by flocking a large number of short fibers on the outer peripheral surface of the shaft body, and the plurality of short fibers fall in an inverted saddle shape while being inserted from the back side into the rear acoustic terminal hole. The condenser microphone unit according to any one of claims 2 to 4, wherein the locking portion is configured.   The locking member is made of a soft material as a whole, and a plurality of locking portions having a sawtooth shape in the axial direction are formed in the axial direction along a peripheral side surface. The condenser microphone unit according to any one of claims 2 to 4.

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