JP2010199888A - Condenser microphone - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a condenser microphone capable of preventing the plastic deformation of a contact spring caused by a large impact applied from the outside by falling or the like and improving reliability against an impact. <P>SOLUTION: In the condenser microphone, a vibration membrane 30 is disposed oppositely to a circuit board 23, a spacer 29 is interposed, a back electrode 31 is disposed at the side of the circuit board 23 of the vibration membrane 30, the back electrode 31 is elastically abutted against the spacer 29 by the contact spring 33 disposed between the circuit board 23 and the back electrode 31, and the circuit board 23 and the back electrode 31 are made conductive. In this configuration, the condenser microphone 21 is provided on a casing base frame 24 with an abutting part 42 as a displacement limiting means for restricting displacement to the side of the circuit board 23 of the back electrode 31 by the impact applied from the outside. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a back electret condenser microphone.

  Conventionally, as this type of technology, for example, there is one disclosed in Patent Document 1. In the configuration of Patent Document 1, the back electrode is disposed to face the vibrating membrane supported in the housing via a spacer. The back electrode is urged toward the vibrating membrane by a contact spring interposed in a compressed state between the circuit board and the back electrode, and is held in contact with the spacer and is electrically connected to the circuit board. Yes. And the capacitor | condenser part is comprised with the back electrode as a back electrode with which the electretized film was integrated, and the vibrating membrane in which the conductive layer was formed. According to such a configuration, the load applied to the contact portion with the spacer in the back electrode does not exceed the biasing force of the contact spring, so that the dielectric layer is not crushed at the contact portion, and the sensitivity of the condenser microphone is reduced. Will improve.

JP 2008-141409 A

  By the way, in the configuration as in Patent Document 1, excessive acceleration is instantaneously applied to the back electrode as when a device such as a mobile phone equipped with the condenser microphone having the above-described configuration is dropped on a hard floor or a paved road surface. If a large impact is applied, the back electrode may be displaced toward the circuit board against the biasing force of the contact spring. Then, the back electrode may be greatly displaced toward the circuit board side, causing plastic deformation of the contact spring. In such a case, the urging force applied to the back electrode from the contact spring decreases from the set value, and as a result, the distance between the back electrode and the vibration membrane increases from the set value, or the back electrode and the circuit board There is a possibility that conduction through the contact spring may be poor.

  The present invention has been made paying attention to such problems existing in the prior art. An object of the present invention is to provide a condenser microphone that can prevent plastic deformation of a contact spring due to a large impact applied from the outside due to dropping or the like, and can improve reliability against the impact.

  In order to achieve the above object, according to the first aspect of the present invention, a vibration film is disposed opposite to a circuit board, a back electrode is disposed with a spacer interposed on the circuit board side of the vibration film, and the circuit board and In a condenser microphone in which the back electrode is elastically brought into contact with the spacer by the contact spring disposed between the back electrode and the circuit board and the back electrode are electrically connected, a certain amount of the back electrode to the circuit board side is determined. Displacement limiting means for limiting the above displacement is provided.

  The invention according to claim 2 includes a housing base frame that is interposed between the circuit board and the spacer and has an opening that accommodates the back electrode, and the displacement limiting means includes the back electrode. The contact portion is formed on the inner peripheral side of the housing base frame so as to face the outer peripheral edge portion, and is a contact portion with which the outer peripheral edge portion contacts when the back electrode is displaced toward the circuit board.

The invention described in claim 3 is characterized in that a layered elastic portion for buffering a collision with the back electrode is provided on a surface of the contact portion facing the outer peripheral edge of the back electrode. To do.
According to a fourth aspect of the present invention, the housing base frame is integrated with the first base frame body to be joined to the circuit board, and the back electrode is accommodated in the first base frame body. It is comprised by the 2nd base frame joined to the said spacer, The said contact part is comprised by the inner peripheral part of the said 1st base frame, It is characterized by the above-mentioned.

  According to a fifth aspect of the present invention, the displacement limiting means extends from the contact spring to the circuit board side, contacts the circuit board when the back electrode is displaced to the circuit board side, and determines a certain amount of the back electrode. It is a contact piece which restrict | limits the above displacement, It is characterized by the above-mentioned.

  The invention according to claim 6 is characterized in that the contact spring is formed by punching from a metal plate, and the contact piece is integrally formed with the contact spring.

  According to a seventh aspect of the present invention, the displacement limiting means extends from the outer peripheral edge of the back electrode to the circuit board side, and abuts against the circuit board when the back electrode is displaced to the circuit board side. It is a contact part which restrict | limits the displacement more than fixed amount of an electrode, It is characterized by the above-mentioned.

(Function)
When the back electrode is displaced to the circuit board side with deformation of the contact spring due to a large impact applied to the condenser microphone from the outside, the displacement is limited by the displacement limiting means. For this reason, excessive deformation of the contact spring due to displacement of the back electrode is restricted, and plastic deformation is prevented. As a result, enlargement of the distance between the back electrode and the diaphragm from the set value and poor conduction between the back electrode and the circuit board via the contact spring are prevented.

  According to the present invention, it is possible to prevent plastic deformation of the contact spring due to a large impact applied from the outside due to dropping or the like, and to improve the reliability against the impact.

The longitudinal cross-sectional view which shows the condenser microphone of 1st Embodiment. Similarly disassembled perspective view. The top view which shows the positional relationship of the conductive pattern on a circuit board, and a resist. (A) is a top view which shows the conductive pattern of the upper surface side of a circuit board, (b) is a top view which similarly shows a resist. The top view which shows the conductive pattern of the lower surface side of a circuit board. The top view which shows the upper surface of a housing | casing base frame. The longitudinal cross-sectional view which shows the condenser microphone of 2nd Embodiment. The perspective view of a partial fracture | rupture which shows a back electrode. The longitudinal cross-sectional view which shows the condenser microphone of 3rd Embodiment. The perspective view which shows a contact spring.

(First embodiment)
Next, a first embodiment embodying the present invention will be described with reference to FIGS.
As shown in FIGS. 1 and 2, the housing 22 of the condenser microphone 21 of this embodiment includes a flat circuit board 23, a square frame-shaped housing base frame 24, a flat top cover substrate 25, and the like. Are laminated and fixed integrally by adhesive sheets 27A and 27B. The circuit board 23, the casing base frame 24, and the top cover board 25 are made of an electric insulator made of resin such as epoxy resin. In this embodiment, although the said member is comprised with the glass cloth base material epoxy resin, it is not limited to an epoxy resin.

  As shown in FIG. 4A, conductive patterns 23a, 23b, and 23c made of copper foil are formed on the upper surface of the circuit board 23. In FIG. 4A, the conductive patterns 23a, 23b, and 23c are hatched for convenience of explanation.

  The conductive pattern 23a has a first end 50 located on the upper surface of the circuit board 23 near one end in the longitudinal direction and one end on the short side, and a second end 51 thereof. The upper surface of the circuit board 23 extends toward the center. And the 1st end part 50 of the conductive pattern 23a is made into the conduction | electrical_connection part 50a.

  Here, for convenience of explanation, as shown in FIG. 4A, assuming a central axis O penetrating in the thickness direction of the circuit board 23, an axis in the short direction perpendicular to the central axis O on the upper surface of the circuit board 23. Is the x-axis, and similarly the longitudinal axis is the y-axis. Then, on the upper surface of the circuit board 23, a region P1 that is line symmetric with respect to the conductive portion 50a having the x axis as the symmetric axis, a line symmetric region P2 of the conductive portion 50a having the symmetric axis as the y axis, The point-symmetrical region P3 of the conduction part 50a with the axis O as the center point is included in a region where no conductive pattern is provided (hereinafter referred to as a non-conductive pattern region). The non-conductive pattern region is a region on the upper surface of the circuit board 23 that is surrounded by the conductive pattern 23c and excludes the conductive patterns 23a and 23b. In this embodiment, a plurality of conductive patterns 23b (four in this embodiment) are provided.

  The conductive pattern 23 c is a ground conductive pattern, and is provided in a frame shape so as to face the frame shape of the housing base frame 24. The conductive patterns 23a and 23b are conductive patterns for connecting components, and are used for power supply input and signal extraction.

  Further, as shown in FIGS. 3 and 4B, a part of the conductive patterns 23 a to 23 c and a surface including the regions P <b> 1 to P <b> 3 in the non-conductive pattern region are covered with a resist 52. 3 and 4B, the resist 52 is hatched for convenience of explanation.

  The resist 52 is made of an insulating member such as an epoxy resin, but is not limited to this material, and may be any insulating synthetic resin. In addition, the resist 52 is formed to have the same film thickness over the whole and has the same thickness as the conductive portion 50a of the conductive pattern 23a. That is, the portion of the resist 52 located in the regions P1 to P3 and the conductive portion 50a are set to have the same height (that is, thickness) with respect to the upper surface of the circuit board 23. The thickness of the conductive part 50a and the resist 52 is normally set to about 20 μm to 40 μm. In this embodiment, the thickness of the conductive portion 50a and the resist 52 is set to 30 μm.

  The resist 52 is formed with a notch 52a that exposes the conductive portion 50a, and a notch 52c that exposes the non-conductive pattern region at a position symmetrical to the notch 52a with the x axis as a symmetry axis. ing. Further, in the resist 52, windows 52b are respectively provided in portions corresponding to the second end portion 51 of the conductive pattern 23a, one end portion of each conductive pattern 23b, and a part of the conductive pattern 23c. It is exposed through the window 52b.

The frame-shaped peripheral portion of the conductive pattern 23 c is an exposed portion that is not covered with the resist 52 and is opposed to the housing base frame 24.
As shown in FIG. 5, a plurality of conductive patterns 23d and 23e made of copper foil are formed on the lower surface of the circuit board 23. In FIG. 5, for convenience of explanation, the conductive patterns 23d and 23e are indicated by hatching.

  As shown in FIGS. 4A and 5, a plurality of through holes 23g are provided in the outer peripheral portion of the circuit board 23, and a conductive layer (not shown) is formed in the inner periphery of the through hole 23g. . The conductive pattern 23c and the conductive pattern 23d are electrically connected via the conductive layer of the through hole 23g. A part of the conductive pattern 23d serves as a ground terminal.

  A plurality of through holes 23h are formed in the central portion of the circuit board 23, and a conductive layer is formed on the inner periphery of these through holes 23h. The conductive patterns 23a and 23b and the conductive pattern 23e are electrically connected via the conductive layer of the through holes 23h. The conductive pattern 23e is connected to a signal output terminal and a power input terminal (not shown).

  As shown in FIG. 1, an intermediate layer 23f made of copper foil is provided inside the circuit board 23, and this intermediate layer 23f is connected to each through hole 23g that electrically connects the conductive pattern 23c and the conductive pattern 23d. Are electrically connected.

  On the upper surface of the circuit board 23, an impedance conversion element made of a field effect transistor 26 or the like is mounted. The impedance conversion element is electrically connected to the second end portion 51 of the conductive pattern 23a and some of the conductive patterns 23b.

  As shown in FIGS. 1 and 2, the housing base frame 24 has a first base frame body 40 disposed on the circuit board 23 side, an opening larger than the first base frame body 40, and a top cover. It is formed by laminating and integrating the second base frame body 41 arranged on the substrate 25 side. A step-shaped contact portion 42 as a displacement limiting means is formed on the entire inner peripheral side of the housing base frame 24 by the inner peripheral edge portion of the first base frame body 40. On the upper surface 42a of the contact portion 42, for example, a layered elastic portion 43 made of a resist material or polydimethylsiloxane used for a photoresist or a solder resist is formed. The layered elastic portion 43 is formed by screen printing, for example.

  As shown in FIG. 1, continuous conductive patterns 24 a, 24 b, and 24 c made of copper foil are formed on the upper and lower surfaces and side wall outer surfaces of the housing base frame 24. As shown in FIG. 2, the conductive pattern 24 a is provided in an annular shape with respect to the periphery of the upper opening of the housing base frame 24. Further, although not shown, the conductive pattern 24b is provided in an annular shape with respect to the peripheral edge of the upper opening of the housing base frame 24 in the same manner as the conductive pattern 24a.

  The conductive pattern 24c is formed by applying a conductive paste to the recess 24i provided on the outer side surface of the side wall of the casing base frame 24 except for the outer side surfaces of the four corner portions C of the casing base frame 24. Alternatively, the conductive patterns 24a and 24b are electrically connected to each other by performing metal foil plating such as copper foil plating.

  As shown in FIG. 1, the conductive pattern 24b on the lower surface side is electrically connected to the conductive pattern 23c on the upper surface of the circuit board 23, and the conductive pattern 23d on the lower surface of the circuit board 23 is connected via the conductive pattern 23c. Is electrically connected. A filling portion 24j made of an insulating synthetic resin such as an epoxy resin is formed in the recess 24i.

  As shown in FIGS. 2 and 6, the four corner portions C of the housing base frame 24 are each provided with a through hole 24 k having a circular cross section. A conductive layer (not shown) is formed on the inner periphery of the through hole 24k, and the through hole 24k is filled with a conductive agent made of, for example, a conductive paste.

  As shown in FIGS. 1 and 2, the peripheral edge of the opening at the bottom of the housing base frame 24 is integrally bonded to the circuit board 23 by a rectangular annular adhesive sheet 27A disposed outside the conductive pattern 23c. It is fixed. The electrical components such as the field effect transistor 26 on the circuit board 23 are accommodated in the housing base frame 24.

  As shown in FIGS. 1 and 2, conductive patterns 25 a and 25 b made of copper foil or the like are formed on the upper and lower surfaces of the top cover substrate 25. The top cover substrate 25 is formed with a sound hole 28 for taking in sound from the outside. The top cover substrate 25 is bonded and fixed to the periphery of the opening at the top of the housing base frame 24 by a square annular adhesive sheet 27B disposed outside the conductive pattern 24a.

  As shown in FIGS. 1 and 2, an annular spacer 29 made of an insulating film is sandwiched and fixed between the housing base frame 24 and the top cover substrate 25. The spacer 29 is bonded to the conductive pattern 24a of the housing base frame 24 with a conductive adhesive. A vibration film 30 made of an insulating synthetic resin thin film such as a PPS (polyphenylene sulfide) film is stretched on the upper surface of the spacer 29 by adhesion, and a conductive layer 30a is formed on the lower surface of the vibration film 30 by gold vapor deposition. Is formed. At the four corners of the vibration film 30, folded portions 30b are formed by partially turning the film upside down. Accordingly, the conductive layer 30a is disposed above the folded portion 30b.

  A through hole (not shown) is provided in the vibration film 30 and the spacer 29, and the conductive layer 30a is conductive through a conductive paste filled in the through hole and a conductive adhesive between the spacer 29 and the conductive pattern 24a. It is electrically connected to the pattern 24a.

  As shown in FIG. 1, a plurality of through holes 36 are formed in the top cover substrate 25, and conductive patterns 25 c continuous with the conductive patterns 25 a and 25 b are provided on the inner peripheral surfaces of the through holes 36. Yes. The through hole 36 is filled with a conductive adhesive 37a, and a conductive portion 37 is formed by the conductive adhesive 37a and the conductive pattern 25c. The conductive portion 37 is electrically connected to the conductive layer 30 a of the folded portion 30 b of the vibration film 30.

  As shown in FIGS. 1 and 2, in the first base frame body 40 of the housing base frame 24, a back electrode 31 is disposed opposite to the lower surface of the vibration film 30 with a spacer 29 interposed therebetween. The back electrode 31 is configured by attaching a film 31b such as PTFE (polytetrafluoroethylene) to the upper surface of a plate body 31a made of a stainless steel plate. The film 31b is subjected to polarization treatment by corona discharge or the like, and the film 31b is electretized by this polarization treatment. That is, the condenser microphone 21 of this embodiment is a back electret type in which an electret is provided on the back electrode 31.

  Further, the back electrode 31 is formed so as to have a substantially oval planar shape that is smaller in outer peripheral shape than the inner peripheral shape of the first base frame body 40, and there is a gap between the inner and outer peripheral surfaces thereof. Is formed. A through-hole 32 for allowing air movement due to vibration of the vibrating membrane 30 is formed in the central portion of the back electrode 31. The back electrode 31 is formed by punching a stainless steel plate with a film attached from the film side. The back electrode 31 is configured such that the outer peripheral edge thereof faces the upper surface of the layered elastic portion 43 of the contact portion 42 in the first base frame body 40, and the back electrode 31 faces the circuit board 23 side. When a certain amount or more is displaced, the outer peripheral edge portion comes into contact with the upper surface of the contact portion 42 via the layered elastic portion 43.

  As shown in FIGS. 1 and 2, a contact spring 33 is interposed between the back electrode 31 and the circuit board 23 in a compressed state in the housing base frame 24. The contact spring 33 elastically abuts the back electrode 31 against the lower surface of the spacer 29 and electrically connects the circuit board 23 and the back electrode 31. With this configuration, the vibrating membrane 30 and the back electrode 31 are held at a predetermined interval, and a capacitor portion that secures a predetermined capacitance is formed between them. In this configuration, the lower surface of the outer peripheral portion of the back electrode 31 faces the upper surface of the layered elastic portion 43 on the contact portion 42 in the housing base frame 24 with a gap L therebetween.

  The contact spring 33 is formed by punching and forming a metal plate material obtained by performing gold plating on both the front and back surfaces of a stainless steel plate as a metal plate. And four leg portions 33b projecting obliquely toward the direction. A space S is formed between the leg portions 33b below the frame portion 33a, and the field effect transistor 26 on the circuit board 23 is disposed in the space S.

  Four spherical contact portions 34 that abut on the lower surface of the back electrode 31 protrude from the upper surface of the frame portion 33a of the contact spring 33, and four spherical surface shapes are formed on the lower surface of the distal end of each leg portion 33b. A contact portion 35 is formed to protrude. As shown in FIG. 3, of the four leg portions 33b, one leg portion 33b has its contact portion 35 in contact with the conduction portion 50a of the conductive pattern 23a on the circuit board 23, and another leg. The contact portion 35 of the portion 33b is in contact with the region P2 on the circuit board 23. Of the four legs 33b, the remaining two legs 33b are in contact with the upper surface of the resist 52 located on the regions P1 and P3 on the upper surface of the circuit board 23. . In other words, the plate body 31 a of the back electrode 31 and the conductive pattern 23 a of the circuit board 23 are electrically connected by the contact spring 33.

  In the condenser microphone 21 configured as described above, when the sound wave from the sound source reaches the vibration film 30 through the sound hole 28 of the top cover substrate 25, the vibration film 30 has a frequency, amplitude and waveform of sound. It is vibrated accordingly. As the vibration film 30 vibrates, the distance between the vibration film 30 and the back electrode 31 changes from the set value, and the impedance of the capacitor portion changes. This change in impedance is converted into a voltage signal by the impedance conversion element on the circuit board 23 and output.

  When acceleration from the upper side to the lower side in FIG. 1 is applied to the back electrode 31 due to an impact applied to the condenser microphone 21 from the outside, the back electrode 31 deforms the contact spring 33 as indicated by a two-dot chain line. Along with this, the circuit board 23 is displaced. At this time, when the back electrode 31 is displaced by a certain amount or more, the lower surface of the outer peripheral edge abuts against the layered elastic portion 43 on the abutting portion 42 of the housing base frame 24, and this abutment causes the circuit board 23 side. Displacement is regulated. For this reason, excessive deformation of the contact spring 33 based on the displacement of the back electrode 31 is prevented. Further, when the back electrode 31 comes into contact with the upper surface of the contact portion 42, the impact applied to the back electrode 31 is alleviated by elastic deformation of the layered elastic portion 43 formed on the upper surface.

This embodiment described in detail above has the following effects.
(1) The housing base frame 24 is provided with a contact portion 42 as a displacement restricting means for restricting a certain amount of displacement of the back electrode 31 toward the circuit board 23 due to an impact applied to the condenser microphone 21 from the outside. For this reason, excessive deformation of the contact spring 33 due to displacement of the back electrode 31 is restricted, and plastic deformation thereof is prevented. Therefore, a decrease in the urging force of the contact spring 33 against the back electrode 31 is prevented. As a result, it is possible to prevent the distance between the back electrode 31 and the vibration film 30 from being increased from the set value, and the poor conduction between the back electrode 31 and the circuit board 23 via the contact spring 33. . Therefore, the reliability of the condenser microphone 21 against an externally applied impact is improved.

  (2) The displacement of the back electrode 31 is limited by the contact portion 42 formed on the entire inner peripheral side of the housing base frame 24 so as to face the outer peripheral edge portion of the back electrode 31. Therefore, in order to limit the displacement of the back electrode 31 by the contact of the contact portion 42 with respect to the entire outer peripheral edge portion, the direction of acceleration applied to the back electrode 31 is inclined with respect to the central axis of the back electrode 31. Even so, the displacement of the back electrode 31 can be appropriately limited. Therefore, the reliability of the condenser microphone 21 is further improved.

  (3) On the upper surface of the contact portion 42, a layered elastic portion 43 that buffers the collision of the back electrode 31 is provided. Therefore, even if the back electrode 31 collides with the contact portion 42 with a large acceleration due to an excessive impact applied to the condenser microphone 21, the impact applied to the film 31b and the back electrode 31 is absorbed. For this reason, the back electrode 31 and the film 31b are not peeled off, the back electrode 31 is not deformed, and further, the film 31b is not damaged, thereby preventing the dielectric state of the electret from being weakened. Is done.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIGS. The following embodiments will be described with a focus on differences from the first embodiment.

As shown in FIGS. 7 and 8, in this embodiment, unlike the first embodiment, the housing base frame 24 is not provided with the abutting portion 42 and is formed by a single member.
On the other hand, the contact spring 33 is integrally formed with a pair of contact portions 33c as displacement limiting means extending downward from both sides of the frame portion 33a. The contact portion 33c abuts on the conductive pattern 23c of the circuit board 23 and restricts further deformation of the contact spring 33 when the contact spring 33 is compressed and deformed to the circuit board 23 side.

  When the back electrode 31 is displaced by a certain amount or more toward the circuit board 23 with deformation of the contact spring 33 as shown by a two-dot chain line in FIG. Both abutting portions 33 c of the spring 33 abut on the upper surface of the circuit board 23. As a result, further deformation of the contact spring 33 is restricted and displacement of the back electrode 31 is restricted, so that excessive deformation of the contact spring 33 based on the displacement of the back electrode 31 is prevented.

Therefore, this embodiment has the effect (1) of the first embodiment.
(Third embodiment)
Next, a third embodiment embodying the present invention will be described with reference to FIGS.

  As shown in FIGS. 9 and 10, in this embodiment, the entire outer peripheral edge portion of the back electrode 31 extends downward to form a contact portion 31c as a displacement limiting means. When the back electrode 31 is displaced toward the circuit board 23, the contact part 31 c comes into contact with the resist 52 of the circuit board 23 and restricts further displacement.

  If the back electrode 31 is displaced by a certain amount or more toward the circuit board 23 side with deformation of the contact spring 33 as shown in FIG. The contact portion 31c contacts the upper surface of the circuit board 23, and further displacement of the back electrode 31 is limited. For this reason, the excessive deformation | transformation of the contact spring 33 based on the displacement of the back electrode 31 is prevented. Further, since the contact portion 31 c of the back electrode 31 collides with the resist 52, the impact applied to the back electrode 31 due to the elastic deformation of the resist 52 is mitigated.

Therefore, this embodiment has the effects (1) and (3) of the first embodiment.
(Other embodiments)
In addition, the said embodiment can also be changed and actualized as follows.

  In the first embodiment, the upper surface 42a of the contact portion 42 is increased by increasing the height of the contact portion 42 (that is, the first base frame body 40) or increasing the thickness of the layered elastic portion 43. The gap L is not provided between the upper surface of the layered elastic portion 43 formed in the above and the lower surface of the outer peripheral portion of the back electrode 31.

In the first embodiment, the housing base frame 24 including the first base frame body 40 and the second base frame body 41 and having the contact portion 42 is configured by a single member.
In the first embodiment, as shown by a two-dot chain line in FIG. 2, the contact portions 42 of the first base frame body 40 are formed at a plurality of positions separated from each other on the inner peripheral side of the first base frame body 40. By doing so, it is composed of a plurality of mutually independent.

  -In 3rd Embodiment, as shown with a dashed-two dotted line in FIG. 10, the contact part 31c extended below from the outer-periphery edge part of the back electrode 31 is made into the several position mutually spaced apart in the outer periphery of the back electrode 31. By forming, it consists of a plurality of independent from each other.

  In the first and third embodiments, instead of the contact spring 33 made of a leaf spring, it is made up of one coil spring interposed between the circuit board 23 and the back electrode 31 so as to contain the field effect transistor 26. Use contact springs.

  The present invention is embodied in a condenser microphone having a configuration in which the housing base frame 24 and the top cover substrate 25 are integrated.

  DESCRIPTION OF SYMBOLS 21 ... Condenser microphone, 23 ... Circuit board, 24 ... Housing base frame, 29 ... Spacer, 30 ... Vibration film, 31 ... Back electrode, 31c ... Contact part as displacement limiting means, 33 ... Contact spring, 33c ... Displacement Contact pieces as limiting means, 40: first base frame, 41: second base frame, 42: contact part as displacement limiting means, 43: layered elastic part.

Claims (7)

A diaphragm is placed opposite the circuit board, a back electrode is placed with a spacer interposed on the circuit board side of the diaphragm, and the back electrode is placed against the spacer by a contact spring placed between the circuit board and the back electrode. In a condenser microphone that is elastically brought into contact with the circuit board and the back electrode,
A condenser microphone is provided, wherein displacement limiting means for limiting a certain amount of displacement of the back electrode toward the circuit board is provided. A housing base frame interposed between the circuit board and the spacer and having an opening for accommodating the back electrode;
The displacement limiting means is formed on the inner peripheral side of the housing base frame so as to face the outer peripheral edge of the back electrode, and the outer peripheral edge abuts when the back electrode is displaced toward the circuit board. The condenser microphone according to claim 1, wherein the condenser microphone is a contact portion.   3. The condenser microphone according to claim 2, wherein a layered elastic portion for buffering a collision with the back electrode is provided on a surface of the contact portion facing the outer peripheral edge of the back electrode. .   The housing base frame is joined to the spacer in a state of being integrated with the first base frame body and housing the back electrode while being joined to the circuit board. The condenser microphone according to claim 2, wherein the contact portion is formed by an inner peripheral edge portion of the first base frame body.   The displacement limiting means extends from the contact spring to the circuit board side, and contacts the circuit board when the back electrode is displaced to the circuit board side, and a contact piece that limits a certain amount of displacement of the back electrode. The condenser microphone according to claim 1, wherein:   6. The condenser microphone according to claim 5, wherein the contact spring is formed by punching from a metal plate material, and the contact piece is integrally formed with the contact spring.   The displacement limiting means extends from the outer peripheral edge of the back electrode to the circuit board side, and contacts the circuit board when the back electrode is displaced to the circuit board side to limit a certain amount of displacement of the back electrode. The condenser microphone according to claim 1, wherein the condenser microphone is a contact portion.

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