JP2001339795A - Electret-condenser microphone - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electret-condenser microphone capable of controlling a reduction of sensitivity even though at the occurrence of cutting remaining of a diaphragm. SOLUTION: A case 2 of an electret-condenser microphone 1 has a bottom surface part 3 used for a front surface board at an end of it, and also the case 2 is composed of a metallic and cylindrical-shaped member at the other end. At the bottom surface part 3 of the case 2, a determined shaped opening part 4 is formed. A diaphragm subassembly 11 has a diaphragm 12 and a diaphragm frame 13. A diameter of outer edge of the frame 13 is settled less than that of inner edge of the case 2. On the other side surface that is opposite of the side surface attached the diaphragm 12 of the frame 13, a ring-shaped projection part 15 for positioning is formed in one body. The projection part 15 is placed at the position responding to an opening part 4 of the bottom surface part 3, so that at arrangement of the frame 13 in the case 2, the projection part 15 is fitted to the opening part 4 of the surface part 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an electret condenser microphone.

[0002]

2. Description of the Related Art As an electret condenser microphone of this type, for example, Japanese Utility Model Registration No. 301104
No. 8 is known. The electret condenser microphone disclosed in Japanese Utility Model Registration No. 30101048 has a cylindrical case having one end face closed by a front plate. A sound hole is formed in the center of the front plate. A diaphragm attached to the diaphragm ring is accommodated in the case, and the front surface of the diaphragm ring is in contact with the front plate of the case. Further, the outer peripheral surface of the diaphragm ring is in contact with the inner peripheral surface of the case, whereby positioning when the diaphragm ring is disposed in the case is performed.

A back electrode plate as a fixed electrode is opposed to the rear of the diaphragm at a predetermined interval via a spacer. A capacitor portion is formed by the diaphragm and the back electrode plate.

In general, a diaphragm is attached to a diaphragm frame by applying a predetermined tension to a sheet-like PET film or the like that constitutes the diaphragm (vibrating membrane). ) Is adhered, and the sheet is cut along the outer shape of the diaphragm frame with the diaphragm frame and the diaphragm adhered.

[0005]

However, in the electret condenser microphone disclosed in Japanese Utility Model Registration No. 3011048, when the sheet is cut along the outer shape of the diaphragm frame, the electret condenser microphone is placed outside the diaphragm frame. If the protruding sheet (vibration membrane) is left uncut, the outer peripheral surface of the diaphragm frame is in contact with the inner peripheral surface of the case, so the diaphragm is cut when the diaphragm frame is inserted into the case. The remaining portion is bent toward the spacer, and is sandwiched between the diaphragm frame and the back electrode plate or the spacer. As described above, when the remaining portion of the vibration film is sandwiched between the vibration film frame and the back electrode plate or the spacer, the gap between the vibration film and the back electrode plate is enlarged and the vibration film and the back electrode plate become The capacitance changes between
It has been found that the sensitivity characteristics may be reduced.

In the electret condenser microphone disclosed in Japanese Utility Model Registration No. 30101048, when the case is formed by pressing, the front face of the diaphragm frame is brought into contact with the front face plate. It has been found that it is necessary to newly form a relief portion or the like at the corner between the and the side surface, which also has a problem that the manufacturing process becomes complicated.

The present invention has been made in view of the above points, and has as its object to provide an electret condenser microphone that can suppress a decrease in sensitivity characteristics even when the diaphragm remains uncut. .

[0008]

According to the present invention, there is provided an electret condenser microphone comprising: a cylindrical case having a bottom portion used as a front plate; and a diaphragm frame on which a diaphragm is attached. Is an electret condenser microphone disposed in the case, an opening of a predetermined shape is formed in a bottom portion of the case, and the diaphragm is fitted in the opening of the bottom portion in the diaphragm frame. A positioning projection for positioning the ring member with respect to the case when the frame is disposed in the case is formed. When the diaphragm frame is disposed in the case, the outer peripheral surface of the diaphragm frame is provided. And a predetermined gap is provided between the case and the inner peripheral surface of the case.

In the electret condenser microphone according to the present invention, when the diaphragm frame is disposed in the case, a predetermined gap is provided between the outer peripheral surface of the diaphragm frame and the inner peripheral surface of the case. Therefore, even in the case where the remaining portion of the diaphragm is cut, the remaining portion of the cut is suppressed from being sandwiched between the diaphragm frame and the back electrode plate or the spacer, and the gap between the diaphragm and the back electrode plate is reduced. It is possible to prevent the capacitance between the vibrating membrane and the back electrode plate from changing due to enlargement. As a result, it is possible to prevent the sensitivity characteristics of the electret condenser microphone from deteriorating.

An opening having a predetermined shape is formed in the bottom of the case, and the diaphragm is fitted into the opening of the bottom in the diaphragm so that the diaphragm can be disposed in the case. Since the positioning projection for positioning the ring member with respect to the case is formed, even when a predetermined gap is provided between the outer peripheral surface of the diaphragm frame and the inner peripheral surface of the case, the positioning projection is formed. The diaphragm frame can be arranged at an appropriate position with respect to the case by fitting the opening and the opening.

Further, the positioning projection is formed in a ring shape, and is provided on an inner peripheral portion of the positioning projection of the diaphragm.
Preferably, a sound hole is formed. As described above, the positioning protrusion is formed in a ring shape, and the sound hole is formed in the inner peripheral portion of the positioning protrusion of the diaphragm frame, so that the diaphragm frame is positioned at an appropriate position with respect to the case. The structure of the positioning projection that can be securely arranged can be realized simply and at low cost.

Preferably, the case is formed into a tubular shape having a bottom portion by press working. Thus, the case can be easily formed by forming the case into a cylindrical shape having a bottom portion by pressing. Further, even when the case is formed by press working, since a predetermined gap is provided between the outer peripheral surface of the diaphragm frame and the inner peripheral surface of the case, a corner between the front plate and the side surface is provided. Without newly forming escape parts etc.
The vibrating membrane frame can be brought into contact with the front plate (bottom portion). As a result, it is possible to prevent the manufacturing process of the electret condenser microphone from becoming complicated.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of an electroacoustic transducer according to the present invention will be described below in detail with reference to the drawings. In the description of the drawings, the same elements will be denoted by the same reference symbols, without redundant description.

FIGS. 1 and 2 are perspective views showing the overall appearance of an electret condenser microphone according to an embodiment of the present invention. FIG. 3 is a sectional view of the electret condenser microphone, and FIGS. Is
FIG. 2 is an exploded perspective view showing the structure of the electret condenser microphone.

Electret condenser microphone 1
Has a case 2. The case 2 has a bottom surface 3 used as a front plate at one end, and a cylindrical metal (eg, stainless steel or the like) having an open end at the other end.
Bottom part 3 (front panel) by pressing
And has a cylindrical shape. Bottom part 3 of case 2
Is formed with an opening 4 having a predetermined shape (for example, a circular shape). In the case 2, the diaphragm subassembly 11, the spacer 21, the back electrode 31, the insulating bush 41, the substrate 51, and the fixing ring 61 are accommodated and arranged.

The diaphragm subassembly 11 is shown in FIG.
As shown in (1), it has a diaphragm 12 (diaphragm) and a diaphragm frame 13. The vibration film 12 is made of PET (Polyethylene Terephthalate) having a thickness of about 1.5 μm.
ate) A film is attached to the diaphragm 13. Au is vapor-deposited on the surface of the vibration film 12 on the side adhered to the vibration film frame 13. The electret condenser microphone 1 is located at the center of the diaphragm 12.
A vent hole (through-hole) 14 for adjusting the atmospheric pressure inside and outside of the vehicle is provided. In the present embodiment, the vent hole 1
The diameter of 4 is set to about 65 μm.

The diaphragm 13 is made of a substantially disk-shaped metal (for example, phosphor bronze). The outer diameter of the diaphragm 13 is set smaller than the inner diameter of the case 2. I have. In the present embodiment, the outer diameter of the diaphragm 13 is set to about 8.2 mm, and the inner diameter of the case 2 is set to about 8.5 mm.

A ring-shaped positioning projection 15 is integrally formed on the surface (back surface) of the vibration film frame 13 opposite to the surface on which the vibration film 12 is adhered. The positioning projection 15 is provided at a position corresponding to the opening 4 of the bottom surface 3, and fits into the opening 4 of the bottom surface 3 when the diaphragm 13 is disposed in the case 2. In this way, the positioning of the diaphragm subassembly 11 (vibrating membrane frame 13) with respect to the case 2 is performed by fitting the positioning projection 15 into the opening 4 of the bottom surface portion 3. Further, a sound hole 16 is formed in the inner peripheral portion of the positioning projection 15 of the diaphragm 13.

In a state where the diaphragm subassembly 11 (vibrating membrane frame 13) is disposed in the case 2 and the positioning projection 15 is fitted to the opening 4, as shown in FIG. A predetermined gap is provided between the outer peripheral surface and the inner peripheral surface of the case 2. When the positioning projection 15 is fitted into the opening 4 of the bottom surface 3, the surface of the vibration film frame 13 opposite to the surface on which the vibration film 12 is adhered and the bottom surface 3 come into contact with each other. The diaphragm 13 and the case 2 are electrically connected.

The vibrating membrane 12 is attached to the vibrating membrane frame 13 by a sheet-like P which constitutes the vibrating membrane 12.
A plurality of diaphragm frames 13 are adhered to each other while a predetermined tension is applied to the ET film.
2 is cut by cutting the sheet along the outer shape of the diaphragm frame 13 in a state where they are bonded to each other.

The back electrode portion 31 is disposed on the rear side of the diaphragm sub-assembly 11, that is, on the opening (the other end) side of the case 2 with respect to the diaphragm sub-assembly 11, and as shown in FIG. It has a plate 32 and an electret 33. The electret 33 is F
It consists of EP (Fluorinated Ethylene Propylene) film. The back electrode plate 32 is made of a substantially triangular metal (for example, stainless steel) member, and has an electret 33 thermally fused (laminated) on one surface. The back electrode portion 31 is disposed such that the surface of the back electrode plate 32 on which the electret 33 is thermally fused faces the vibrating film 12 of the diaphragm subassembly 11.
The back electrode plate 32 is disposed in the case 2 so that the center position of the back electrode portion 31 (back electrode plate 32) matches the center position of the case 2, and the inner peripheral surface of the case 2 and the back electrode plate The size is set so that a predetermined gap (for example, about 0.1 mm) is formed between the end portion 32 and the end portion.

The back electrode portion 31 is formed by punching a base material constituting the back electrode plate 32 obtained by heat-sealing an electret 33 into a substantially triangular shape. After performing the punching process to form the back electrode portion 31, the electret 33 is corona-charged so as to have a predetermined surface charge (for example, about -360 V).

A spacer 21 is provided between the back electrode portion 31 and the diaphragm subassembly 11. The spacer 21 is made of stainless steel or the like.
Is set to about 40 μm. This allows
A predetermined distance (about 40 μm) between the vibration film 12 and the back electrode plate 32 (electret 33) via the spacer 21
Will be provided. The vibrating membrane 12 and the back electrode plate 32 form a capacitor section.

The insulating bush 41 is made of resin, elastomer or the like, and is pressed into the case 2. In the present embodiment, the insulating bush 41 is made of PTFE (Polytetrafluid).
oroethylene). The insulating bush 41 is disposed on the rear side of the back electrode portion 31, that is, on the opening side of the case 2 with respect to the back electrode portion 31.
Abuts on the surface on the opening side.

The insulating bush 41 is deformed by applying a predetermined force from the opening side of the case 2 as described later, and is formed between the inner peripheral surface of the case 2 and the end of the back electrode plate 32. Fit into the gap. When the insulating bush 41 is fitted between the inner peripheral surface of the case 2 and the end of the back electrode plate 32, the back electrode plate 32 and the case 2 are electrically insulated from each other. (Back electrode part 31) is case 2
Will be positioned with respect to.

The substrate 51 has a JEF as an impedance converter for converting a change in capacitance between the vibrating membrane 12 and the back electrode plate 32 (capacitor portion) into an electrical impedance.
T (Junction Field-Effect Transistor) chip 52
Has been implemented and arranged. On the upper surface of the JEFT chip 52, a gate electrode 53 is formed.
Numeral 3 is bonded and fixed to the back electrode plate 32 with a conductive adhesive 54, and is electrically connected to the back electrode plate 32 via the conductive adhesive 54.

On the back surface of the substrate 51 (the surface opposite to the surface on which the JEFT chip 52 is provided), power supply terminal pins 55,
An output terminal pin 56 and a ground terminal pin 57 are provided upright. The ground terminal pin 57 is electrically connected to the diaphragm 12 via the case 2. Power supply terminal pin 55
And the output terminal pin 56 are connected to the JEFT chip 52 respectively.
Are electrically connected to a drain electrode (not shown) and a source electrode (not shown).

The fixing ring 61 is disposed on the rear side of the substrate 51, that is, on the opening side of the case 2 with respect to the substrate 51, and the back surface of the substrate 51 (the surface opposite to the surface on which the JEFT chip 52 is disposed). ). This fixing ring 6
1 is made of stainless steel or the like. The fixing ring 61 and the case 2 are fixed to each other by laser welding or the like while applying a predetermined force to the fixing ring 61 from the opening side of the case 2.

Next, a method of assembling the electret condenser microphone 1 will be described.

First, the diaphragm subassembly 11 and the spacer 21 are sequentially inserted into the case 2. The diaphragm subassembly 11 is configured such that the positioning projection 15 of the diaphragm 13 fits into the opening 4 of the case 2,
Positioning with respect to case 2 is performed.

When the insertion of the diaphragm subassembly 11 and the spacer 21 into the case 2 is completed, the back electrode 31
And the insulating bush 41 are inserted by an automatic assembling machine.
The back electrode portion 31 detects the center position of the case 2 using an image recognition technique or the like, and detects the back electrode portion 31 (back electrode plate 32 ) Is inserted into the case 2 so as to match the center position. When the back electrode portion 31 is inserted, the insulating bush 41 is press-fitted (inserted) into the case 2 to a position where it comes into contact with the back electrode plate 32.

A JEFT chip 52 is mounted on a substrate 51, and a gate electrode 53 on the upper surface of the JEFT chip 52 is provided.
After applying an appropriate amount of the conductive adhesive 54 to the substrate 2, the substrate 51 is inserted into the case 2. After inserting the board 51 into the case 2,
The fixing ring 61 is inserted into the case 2, and a predetermined force (for example, about 49.0 N) is applied to the upper surface of the fixing ring 61 from the opening side of the case 2. The force applied to the fixing ring 61 is transmitted to the insulating bush 41 via the substrate 51, and the insulating bush 41 is deformed and fit between the inner peripheral surface of the case 2 and the end of the back electrode plate 32. Get stuck. As described above, the insulating bush 41 is fitted between the inner peripheral surface of the case 2 and the end of the back electrode plate 32, so that the back electrode plate 3
Back electrode plate 3 with case 2 and case 2 electrically insulated.
2 (back electrode portion 31) is positioned with respect to case 2.

Then, while a predetermined force (for example, about 49.0 N) is applied to the upper surface of the fixing ring 61 from the opening side of the case 2, the fixing ring 61 is applied from the outer peripheral side of the case 2 by a laser welding machine. The case 2 and the fixing ring 61 are fixed by welding by irradiating a laser beam to a position near the center with respect to the thickness. Welding points between the case 2 and the fixing ring 61 are set at four positions at approximately 90 ° intervals.

In this embodiment, the insulating bush 41 is press-fitted into the case 2 to a position where the insulating bush 41 comes into contact with the back electrode plate 32, and a force is applied to the fixing ring 61 from the opening side of the case 2. 2 and insulating bush 41
, And between the substrate 51 and the insulating bush 41. By forming the seal portion in this way, the airtightness of the space defined by the substrate 51 and the diaphragm subassembly 11 (vibrating film 12) can be increased.

As described above, in the electret condenser microphone 1 according to the present embodiment, the diaphragm subassembly 11 (diaphragm frame 13) is disposed in the case 2 and the positioning projection 15 is fitted to the opening 4. In this state, a predetermined gap is provided between the outer peripheral surface of the diaphragm 13 and the inner peripheral surface of the case 2. Is the diaphragm 13 and the back electrode plate 32
Alternatively, it is possible to prevent the capacitance between the vibration film 12 and the back electrode plate 32 from being changed by suppressing the sandwiching between the vibration film 12 and the back electrode plate 32 by expanding the gap between the vibration film 12 and the back electrode plate 32. be able to. As a result, it is possible to prevent the sensitivity characteristics of the electret condenser microphone 1 from deteriorating.

An opening 4 is formed in the bottom portion 3 of the case 2, and the diaphragm frame 13 is fitted in the opening 4 of the bottom portion 3 to dispose the diaphragm frame 13 in the case 2. Since the positioning projection 15 for positioning the ring member with respect to the case 2 is formed, a predetermined gap is provided between the outer peripheral surface of the diaphragm 13 and the inner peripheral surface of the case 2. In the case where the diaphragm sub-assembly 11 is
The (vibrating membrane frame 13) can be disposed at an appropriate position with respect to the case 2.

The positioning projection 15 is formed in a ring shape, and a sound hole 16 is formed in the inner peripheral portion of the positioning projection 15 of the diaphragm 13.
In contrast, the structure of the positioning projection 15 that can securely dispose the diaphragm subassembly 11 (vibrating membrane frame 13) at an appropriate position can be realized simply and at low cost.

The case 2 is formed into a cylindrical shape having the bottom surface 3 by press working, so that the case 2 can be easily formed. Further, even when the case 2 is formed by press working, the diaphragm 1
Since a predetermined gap is provided between the outer peripheral surface of the case 3 and the inner peripheral surface of the case 2, the vibration film frame can be formed without newly forming a relief portion or the like at a corner between the front plate and the side surface. 13 can be brought into contact with the front plate (bottom part 3). As a result, it is possible to prevent the manufacturing process of the electret condenser microphone 1 from becoming complicated.

The present invention is not limited to the above-described embodiment, and the above-described numerical values, the shapes of the components, and the like can be appropriately changed and set.

[0040]

As described above in detail, according to the present invention, it is possible to provide an electret condenser microphone that can suppress a decrease in sensitivity characteristics even when the diaphragm remains uncut. it can.

[Brief description of the drawings]

FIG. 1 is a perspective view showing the overall appearance of an electret condenser microphone according to an embodiment of the present invention.

FIG. 2 is a perspective view showing the entire appearance of the electret condenser microphone according to the embodiment of the present invention.

FIG. 3 is a sectional view of an electret condenser microphone according to the embodiment of the present invention.

FIG. 4 is an exploded perspective view showing a configuration of an electret condenser microphone according to the embodiment of the present invention.

FIG. 5 is an exploded perspective view showing a configuration of an electret condenser microphone according to the embodiment of the present invention.

FIG. 6 is an exploded perspective view showing a configuration of a diaphragm subassembly included in the electret condenser microphone according to the embodiment of the present invention.

FIG. 7 is an exploded perspective view showing a configuration of a back electrode part included in the electret condenser microphone according to the embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Electret condenser microphone, 2 ... Case, 3 ... Bottom part, 4 ... Opening, 11 ... Diaphragm subassembly, 12 ... Vibration film, 13 ... Vibration film frame, 1
5 positioning protrusion, 16 sound hole, 21 spacer, 31
... back electrode part, 32 ... back electrode plate, 33 ... electret,
41: insulating bush, 51: substrate, 52: JFET chip, 61: fixing ring.

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[Procedure amendment]

[Submission date] September 12, 2000 (2009.1.
2)

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] Fig. 6

[Correction method] Change

[Correction contents]

FIG. 6

Continued on the front page (72) Inventor Tomoya Suzuki 20-10 Nakayoshida, Shizuoka-shi, Shizuoka Star Precision Co., Ltd. F-term (reference) 5D021 CC08

Claims (3)

[Claims] 1. An electret condenser microphone comprising: a cylindrical case having a bottom portion used as a front plate; and a diaphragm frame having a diaphragm attached thereto, wherein the diaphragm frame is disposed in the case. An opening having a predetermined shape is formed in the bottom portion of the case, and the diaphragm is fitted in the opening of the bottom portion so that the diaphragm frame is located in the case. A positioning projection for positioning the ring member with respect to the case when the diaphragm is disposed in the case; and an outer periphery of the diaphragm when the diaphragm is disposed in the case. An electret condenser microphone, wherein a predetermined gap is provided between a surface and an inner peripheral surface of the case. 2. The positioning projection is formed in a ring shape. An inner peripheral portion of the positioning projection of the diaphragm frame is
The electret condenser microphone according to claim 1, wherein a sound hole is formed. 3. The electret condenser microphone according to claim 1, wherein the case is formed into the cylindrical shape having the bottom surface by press working.