JP2010199889A - Condenser microphone - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a condenser microphone capable of improving the reliability on impact, by preventing integrated circuits from being damaged by large impact applied from the outside due to falling, or the like. <P>SOLUTION: A vibrating membrane 30 is disposed opposite to a circuit board 23. A spacer 29 is interposed on a side of the circuit board 23 of the vibrating membrane 30 to dispose a back electrode 31. A contact spring 33, disposed between the circuit board 23 and the back electrode 31, allows the back electrode 31 to elastically abut against the spacer 29 to allow the circuit board 23 to be continuous to the back electrode 31. In this constitution, a contacting member 41 is provided to the circuit board 23 to prevent impact to the integrated circuit 40 of the contact spring 33, based on a displacement to the side of the circuit board 23 of the back electrode 31 caused by the impact applied from the outside to the condenser microphone 21. <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, since the load applied to the contact portion with the spacer in the back electrode does not exceed the biasing force of the contact spring, the dielectric layer is not crushed at the contact portion even if there is a load. The sensitivity of the condenser microphone is maintained.

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 urging force of the contact spring. And there exists a possibility that a back electrode may apply a strong pressure to the integrated circuit on a circuit board, and may damage an integrated circuit.

  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 damage to an integrated circuit 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 on which an integrated circuit is mounted, and a back electrode is provided by interposing a spacer on the circuit board side of the vibration film. In the condenser microphone in which the circuit board and the back electrode are electrically connected by elastically contacting the back electrode to the spacer by the contact spring disposed between the circuit board and the back electrode, the back electrode A collision prevention means for preventing a collision with the integrated circuit is provided.

  According to a second aspect of the present invention, the collision preventing means is provided on the circuit board, and comes into contact with the contact spring or the back electrode when the back electrode is displaced a certain amount or more toward the circuit board. It is a contact member which regulates the displacement of an electrode.

The invention according to claim 3 is characterized in that the abutting member is made of an elastic material that cushions the collision of the back electrode or the contact spring.
According to a fourth aspect of the present invention, the contact member has a frame shape surrounding the integrated circuit from the periphery on the circuit board.

The invention described in claim 5 is characterized in that the contact member is a chip component mounted on the circuit board.
(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, strong pressure on the integrated circuit of the contact spring or back electrode is prevented by the collision preventing means. For this reason, damage to the integrated circuit can be prevented.

  According to the present invention, it is possible to prevent damage to the integrated circuit 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 upper surface of a circuit board. (A) is a top view which shows the conductive pattern formed on the upper surface of a circuit board, (b) is a top view which shows a resist. The top view which shows the conductive pattern formed on the back surface of a circuit board. The top view which shows the upper surface of a housing | casing base frame. Sectional drawing which shows the mounting state of an integrated circuit. The longitudinal cross-sectional view which shows the condenser microphone of 2nd Embodiment. The perspective view which similarly shows a back electrode, a contact spring, and a circuit board. The longitudinal cross-sectional view which shows the condenser microphone of 3rd Embodiment.

(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 with respect to the conductive portion 50a having the symmetric axis as the y axis, and the center 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.

  As shown in FIGS. 1 and 2, an application specific integrated circuit (ASIC) 40 constituting an impedance conversion circuit is mounted on the upper surface of the circuit board 23. The integrated circuit 40 is electrically connected to the second end 51 (shown in FIGS. 3 and 4A) of the conductive pattern 23a and the conductive pattern 23b.

  The integrated circuit 40 has a configuration of BGA (Ball Grid Array) or CSP (Chip Size Package), and includes solder balls 42 instead of leads in a QFP (Quad Flatpack Package) as shown in FIG. On the other hand, a nickel-gold plating layer 43 is formed on the surfaces of the conductive patterns 23a to 23c on the circuit board 23, and further on this, an OSP for ensuring good mechanical and electrical connection with the solder balls 42 is formed. (Organic Solderbility Preservative: Organic Solderability Preservative) Coating 44 is applied. The integrated circuit 40 soldered to the upper surface of the circuit board 23 is fixed to the circuit board 23 by filling an underfill agent made of, for example, a one-component thermosetting epoxy resin with the upper surface of the circuit board 23. The Therefore, by adopting the integrated circuit 40 made of BGA or CSP, the condenser microphone 21 is reduced in size, weight, function, and speed. Further, the adoption of the OSP coating 44 can remove phosphorus remaining in the nickel-gold plating layer 43, thereby avoiding troubles during soldering with phosphorus. Further, the use of the underfill agent improves the connection reliability between the circuit board 23 and the integrated circuit 40 against thermal stress and physical stress.

  Further, as shown in FIGS. 1 and 2, a contact member 41 made of an elastic material formed in a frame shape surrounding the integrated circuit 40 from the periphery is provided on the upper surface of the circuit board 23. As the elastic material, a rubber-based material, a synthetic resin, or a thermoplastic elastomer is employed. The height H 1 of the contact member 41 on the circuit board 23 is set to be the same as the height H 2 of the integrated circuit 40. The contact member 41 is fixed to the upper surface of the circuit board 23 as follows. First, the contact member 41 is temporarily fixed at a predetermined position on the upper surface of the circuit board 23. Next, the underfill agent is filled in the gap between the contact member 41 and the circuit board 23 as well as the underfill agent is filled in the gap between the integrated circuit 40 and the circuit board 23. And the contact member 41 is fixed to the upper surface of the circuit board 23 by hardening of the underfill agent by heating.

  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. Electrical components such as the integrated circuit 40 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, a back electrode 31 is disposed opposite to the lower surface of the vibration membrane 30 with a spacer 29 interposed in the housing base frame 24. 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 shape in a planar shape having an outer peripheral shape smaller than the inner peripheral shape of the housing base frame 24, and a gap K is formed 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.

  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.

  The contact spring 33 is formed into a substantially square frame shape by punching and forming a plate material formed by gold plating on both the front and back surfaces of a stainless steel plate. Four leg portions 33b projecting obliquely from both ends of each facing portion 33a toward both lower sides. A space S is formed below the contact spring 33, and the integrated circuit 40 and the like on the circuit board 23 are disposed in the space S. Further, both facing portions 33 a of the contact spring 33 are located above the contact member 41 and are not located above the integrated circuit 40.

  Two spherical contact portions 34 that abut against the lower surface of the back electrode 31 are formed on the upper surface of the opposite surface portions 33a of the contact spring 33, and spherical contact surfaces are formed on the lower surfaces of the tips of the leg portions 33b. Each 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 integrated circuit 40 on the circuit board 23 and outputted.

  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 distance, the lower surfaces of both facing portions 33 a of the contact spring 33 come into contact with the upper surface of the contact member 41. Due to this contact, the displacement of the back electrode 31 is restricted by the contact member 41 along with the deformation of the contact spring 33. Here, the total dimension of the thickness T1 of the facing portion 33a of the contact spring 33 that contacts the upper surface of the contact member 41 and the height H1 of the contact member 41 is larger than the height H2 of the integrated circuit 40. . Therefore, the collision of the back electrode 31 with the integrated circuit 40 is prevented. Further, when the contact spring 33 contacts the contact member 41, the contact member 41 made of an elastic material is elastically deformed, so that the impact applied to the contact spring 33 and the back electrode 31 is buffered. Therefore, the impact applied to each part of the condenser microphone 21 is mitigated.

This embodiment described in detail above has the following effects.
(1) When the back electrode 31 is displaced toward the circuit board 23 due to an impact applied to the condenser microphone 21 from the outside, the contact member provided on the circuit board 23 causes the back electrode 31 to collide with the integrated circuit 40. 41 prevents. For this reason, it is possible to prevent the integrated circuit 40 from being damaged by an external impact.

  (2) Since the contact member 41 is made of an elastic material, the impact applied to the back electrode 31 when the contact spring 33 collides with the contact member 41 is reduced. Therefore, adverse effects on the bonding portion between the circuit board 23 and the housing base frame 24 and between the housing base frame 24 and the top cover substrate 25 are suppressed.

(Second Embodiment)
Next, a second embodiment embodying 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. 8 and 9, on the upper surface of the circuit board 23 in this embodiment, a pair of chip components 43 constituting an impedance conversion circuit together with the integrated circuit 40 is provided on the integrated circuit 40 in place of the contact member 41. It is arrange | positioned at both sides. The height H3 of both the chip components 43 is set to be the same as the height H1 of the integrated circuit 40. The chip component 43 is a chip resistor or a chip capacitor. This chip resistance may be 0Ω. In the case of using a chip capacitor in the case of a microphone used in a mobile phone, a chip capacitor for noise filter corresponding to the carrier wave of the mobile phone may be disposed and used also as the chip component 43. Both facing portions 33 a of the contact spring 33 are located above both chip components 43.

  When the back electrode 31 is displaced toward the circuit board 23 with deformation of the contact spring 33 as shown by a two-dot chain line in FIG. Both facing portions 33 a abut against the upper surface of the chip component 43. By this contact, deformation of the contact spring 33 and displacement of the back electrode 31 toward the circuit board 23 are restricted. Here, the total dimension of the thickness T1 of the facing portion 33a of the contact spring 33 contacting the upper surface of the chip component 43 and the height H1 of the chip component 43 is larger than the height H2 of the integrated circuit 40. Therefore, the collision of the back electrode 31 with the integrated circuit 40 is prevented.

Therefore, this embodiment configured as described above has the effect described in (1) of the first embodiment.
(Third embodiment)
Next, a third embodiment of the present invention will be described with reference to FIG.

  As shown in FIG. 10, the condenser microphone 21 of this embodiment includes a support ring 62 in which a diaphragm 61 is stretched in a metal case 60 provided with a wall 60b having a sound hole 60a on one side. The spacer 63 and the cylindrical insulating bush 64 are vertically accommodated. That is, the spacer 63 is sandwiched between the support ring 62 and the insulating bush 64. A vapor deposition film (not shown) made of gold or nickel alloy is formed on the upper surface of the vibration film 61. Inside the insulating bush 64, a back electrode 66 on which an electret layer 65 is formed, and a coil-shaped contact spring 67 that contacts the lower surface of the back electrode 66 are disposed. Further, a circuit board 68 on which an impedance conversion circuit is formed is disposed in the lower surface opening of the case 60. The circuit board 68 caulks the lower peripheral edge of the case 60 inwardly, thereby insulating bushing 64. The contact spring 67 is fixed in the case 60 in contact with the lower surface thereof. In this state, the contact spring 67 is held in a compressed state between the back electrode 66 and the circuit board 68. The vibration film 61 on which the deposited film is formed is electrically connected to the impedance conversion circuit on the circuit board 68 through the case 60, and the back electrode 66 is electrically connected to the impedance conversion circuit through the contact spring 67. It is connected to the. The vibrating membrane 61 and the back electrode 66 form a capacitor portion.

  On the upper surface of the circuit board 68, an integrated circuit 40 which is a component of the impedance conversion circuit is disposed. A contact member 69 made of an elastic material formed in a frame shape surrounding the integrated circuit 40 from the periphery is provided on the upper surface of the circuit board 68. As the elastic material, a rubber-based material, a synthetic resin, or a thermoplastic elastomer is employed. The height H4 of the contact member 69 is set to be higher than the height H2 of the integrated circuit 40. The integrated circuit 40 and the contact member 69 are located at the inner center of the contact spring 67.

  When the back electrode 66 is displaced to the circuit board 68 side with deformation of the contact spring 67 as shown by a two-dot chain line in FIG. The lower surface contacts the upper surface of the contact member 69. By this contact, deformation of the contact spring 67 and displacement of the back electrode 66 toward the circuit board 68 are restricted. Here, the height H4 of the contact member 69 is higher than the height H2 of the integrated circuit 40. Therefore, the collision of the back electrode 66 with the integrated circuit 40 is prevented.

Therefore, this embodiment configured as described above has the effect described in (1) of the first embodiment.
(Other embodiments)
In the first embodiment, in place of the frame-shaped contact member 41, as shown by a two-dot chain line in FIG. 2, the contact member formed only of a portion facing both facing portions 33a of the contact spring 33. 41 may be provided.

  DESCRIPTION OF SYMBOLS 21 ... Condenser microphone, 23 ... Circuit board, 29 ... Spacer, 30 ... Vibration film, 33 ... Contact spring, 40 ... Integrated circuit, 41 ... Contact member as collision prevention means, 43 ... Chip component as collision prevention means, 61 ... vibrating membrane, 63 ... spacer, 66 ... back electrode, 67 ... contact spring, 68 ... circuit board, 69 ... contact member as collision preventing means.

Claims (5)

The vibration film is disposed opposite to the circuit board on which the integrated circuit is mounted, the back electrode is disposed with a spacer interposed on the circuit board side of the vibration film, and the contact spring disposed between the circuit board and the back electrode, In the condenser microphone in which the back electrode is elastically brought into contact with the spacer and the circuit board and the back electrode are electrically connected,
A condenser microphone comprising a collision preventing means for preventing the back electrode from colliding with the integrated circuit.   The collision preventing means is provided on the circuit board, and abutment member that abuts against the contact spring or the back electrode to regulate the displacement of the back electrode when the back electrode is displaced by a certain amount or more toward the circuit board side. The condenser microphone according to claim 1, wherein:   The condenser microphone according to claim 2, wherein the contact member is made of an elastic material that cushions a collision of the back electrode or the contact spring.   4. The condenser microphone according to claim 2, wherein the contact member has a frame shape surrounding the integrated circuit from the periphery on the circuit board.   The condenser microphone according to claim 2, wherein the contact member is a chip component mounted on the circuit board.

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