JP2005129973A - Plate spring terminal and electret condenser microphone - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plate spring terminal with a low profile for producing a uniform press contact force in place of a coil spring terminal and to provide a small-sized electret condenser microphone with a low profile using the plate spring terminal. <P>SOLUTION: A gate spring 22 being the plate spring terminal has two parallel straight line sides and is provided with a base part 22b having a base part 22c to connect the two straight line sides, a cut and raise part 22a cut and raised from the inside of the straight line part of the base part 22b, the base part 22c being folded nearly in a turned down shape, and the cut and raise part 22a being provided with a cut and raise end part 22d folded nearly in a turned down shape around the end. Since the two parallel straight line sides of the gate spring 22 acting like contacts can depress an object of the gate spring 22, each contact applies a uniform force to the object so as to support the object without causing deviation. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a leaf spring terminal for contact and an electret condenser microphone having the leaf spring terminal.

  In general, an electret condenser microphone includes an electret condenser section and an impedance conversion element that converts the change in capacitance of the electret condenser section into an electrical impedance, and the electret condenser section and the impedance conversion element must be electrically connected. I must.

  Therefore, in order to establish electrical connection between the electret capacitor unit and the impedance conversion element, a lead wire or the like is used, or, as described in, for example, “Patent Document 1”, a conductive process is performed by a coil spring terminal. There are many.

JP 2003-189396 A

  In recent years, electret condenser microphones have been reduced in size, and the conventional electret condenser section and the impedance conversion element have been connected with lead wires, but the lead wires must be soldered or bonded, The workability has been getting worse with downsizing, and it has been troublesome. In addition, when workability is reduced, there is a problem that products vary and consequently stable performance cannot be obtained.

  On the other hand, when the coil spring terminal is used, as described in the above-mentioned “Patent Document 1”, bonding, soldering, or the like is unnecessary, and variations in products are eliminated. Furthermore, the back electrode plate of the electret capacitor section can be uniformly supported only by the coil spring terminal, and it is possible to manufacture a stable product with no characteristics such as deformation of the back electrode plate. Since a lot of spring expansion / contraction space is required, it was in a situation where it could not be used in further downsizing and thinning.

  Under these circumstances, it is necessary to use a leaf spring terminal instead of a coil spring terminal. However, a flat spring spring terminal cannot provide a uniform pressure contact force like a coil spring terminal. The back electrode plate is inclined, or there is a possibility that poor conduction due to poor contact due to insufficient pressure contact force is a problem.

  The present invention has been made in view of such circumstances, and provides a thin leaf spring terminal that generates a uniform pressure contact force instead of a coil spring terminal, and further uses the leaf spring terminal. An object of the present invention is to provide a small and thin electret condenser microphone.

  In the present invention, the structure of the leaf spring terminal is devised and an electret condenser microphone is configured using the leaf spring terminal to achieve the above object.

That is, the leaf spring terminal and the electret condenser microphone according to the present invention have two parallel straight portions, a base having a connecting portion for connecting the two straight portions, and a straight portion of the base. And a cut and raised portion cut and raised from the inside, wherein the connecting portion is bent into a substantially U-shape.
In addition, the cut and raised portion is bent in a substantially U-shape near the end portion.

Further, an electret condenser microphone using the leaf spring terminal, wherein the condenser part includes a diaphragm and a back plate for converting vibration due to sound or the like into a change in capacitance, and the capacitance change converted by the capacitor part. A circuit board including an impedance conversion element for converting the signal into an electric signal, and a conduction part for electrically connecting the capacitor part and the circuit board, and the leaf spring terminal is connected to the conduction part. It is characterized by being used.
The leaf spring terminal is characterized in that the two parallel sides of the straight portion are brought into contact with the capacitor portion, and the end portion of the cut and raised portion is brought into contact with the circuit board.

  As shown in the above configuration, the leaf spring terminal according to the present invention has two straight sides parallel to each other, a base having a connecting portion for connecting the two straight sides, and a straight portion of the base. Since the cut and raised part cut from the inside of the inside and the connecting part are bent in a substantially U shape, and the cut and raised part is bent in a substantially U shape near the end, the following Such effects can be obtained.

  That is, by forming such a leaf spring terminal, the connecting portion is bent into a substantially U shape with respect to an object to be pressed by the leaf spring terminal, and the parallel straight portions of the two sides are pressed as contacts. Therefore, an equal force is applied from each contact point to the object, and the object can be supported without being biased. In addition, by bending the vicinity of the end of the cut and raised portion into a substantially U shape, the fulcrum can be moved from the end to the inside of the spring, so that it is possible to apply a force in the direction of bending of the spring compared to the end. It becomes possible to obtain a stronger spring force. Furthermore, since the flat part or R part can be formed at the end part by bending the vicinity of the end part of the cut-and-raised part into a substantially U-shape, the contact partner is surely brought into contact without being damaged. Is possible.

  In addition, the electret condenser microphone according to the present invention uses the leaf spring terminal as a conductive portion for electrically connecting the capacitor portion and the circuit board, and in particular, the leaf spring terminal is parallel to the capacitor portion. By bringing the linear portions of the two sides into contact with each other and bringing the end portions of the cut and raised portions into contact with the circuit board, the following operational effects can be obtained.

  That is, by applying the leaf spring terminal to the electret condenser microphone, the capacitor portion can be pressed in a stable posture by the leaf spring terminal. Further, since the leaf spring terminal can be formed thinner than the coil spring terminal, it is possible to reduce the thickness of the electret condenser microphone as a whole by adapting this. Further, since the connecting portion of the leaf spring terminal is bent in a substantially U shape, the linear portions on two sides parallel to the capacitor portion are brought into contact with each other, and the end portion of the cut and raised portion is brought into contact with the circuit board. Further, it becomes possible to apply a uniform pressing force to both ends of the capacitor portion, the capacitor portion is not inclined, and a uniform product can be manufactured. In addition, since the end of the cut-and-raised part is brought into contact with the circuit board, it is possible to press the circuit board with a large pressure contact force, and there is no concern about poor conduction, and a more uniform product with a high yield is manufactured. It becomes possible.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a side cross-sectional view showing an electret condenser microphone according to an embodiment of the present invention in an upwardly arranged state. FIG. 2 is a perspective view showing the electret condenser microphone disassembled into main components and viewed obliquely from the rear.

  As shown in these figures, the electret condenser microphone 10 according to the present embodiment is a small surface-mount microphone having a height of about 1.8 mm and having a substantially square outer shape with a side of about 4.5 mm when viewed from the front. A microphone assembly 14, a junction-type field effect transistor 16 (impedance conversion element), two capacitors 18 and 20, and a gate spring 22 are accommodated in a housing 12 formed in a substantially rectangular parallelepiped shape. Yes.

  In the housing 12, a liquid crystal polymer base housing 52 opened forward and a liquid crystal polymer top housing 54 opened rearward are fixed by ultrasonic welding.

  In the microphone assembly 14, a diaphragm subassembly 34, a spacer 36, a back electrode plate 38, and an insulating bush 40 are accommodated in a short, substantially rectangular cylindrical metal cover 32 extending in the front-rear direction.

  FIG. 3 is a perspective view showing the microphone assembly 14 disassembled for each component and seen from the oblique rear side together with the gate spring 22.

  As shown also in this figure, the metal cover 32 is made of a stainless steel cover body 32A having a sound hole 32a formed in the front wall, and a stainless steel welded to the open rear edge 32b of the cover body 32A. The contact frame 32B.

  In the diaphragm sub-assembly 34, the diaphragm 34A is stretched and fixed on the rear surface of the support ring 34B (the diaphragm support member). The vibration film 34A is formed by depositing a metal (eg, gold or nickel alloy) vapor deposition film on the front surface of a circular polymer film (eg, PPS (polyphenylene sulfide) film) having a thickness of about 1.5 μm. The support ring 34 </ b> B is configured by a stainless steel ring member having an outer diameter substantially inscribed in the metal cover 32.

  Then, the vibration film 34A is stretched and fixed to the support ring 34B in such a manner that a PPS film having a metal vapor deposition film formed on the lower surface is stretched with a predetermined tension by the weight of the jig, and is reactively cured on the upper surface. This is performed by pressing and adhering to the support ring 34B to which the agent A1 is applied and removing unnecessary portions of the PPS film.

  The spacer 36 is composed of a stainless steel thin plate ring having a plate thickness of about 25 μm, and the outer diameter thereof is set to be approximately the same as the outer diameter of the support ring 34B.

  The back electrode plate 38 includes an electrode plate main body 38A and an electret layer 38B thermally fused to the front surface of the electrode plate main body 38A, and the outer diameter thereof is set to a value slightly smaller than the outer diameter of the support ring 34B. ing. A cylindrical back pressure adjusting hole 38 a having a diameter of about 0.8 mm is formed in the center of the back electrode plate 38.

  The electrode plate body 38A is made of a stainless steel plate having a thickness of about 0.15 mm. On the other hand, the electret layer 38B is formed of an FEP (fluorinated ethylene propylene) film having a thickness of about 25 μm. The electret layer 38B is subjected to a polarization process by corona discharge or the like, thereby applying a predetermined surface potential (for example, −125 V).

  In the metal cover 32, the vibration film 34 </ b> A and the electret layer 38 </ b> B are opposed to each other with a predetermined minute interval through the spacer 36, thereby constituting the capacitor unit C.

  FIG. 4 is a front view showing the insulating bush 40 and the contact frame 32 </ b> B together with the gate spring 22 in the microphone assembly 14.

  As shown also in this figure, the insulating bush 40 is a frame member made of liquid crystal polymer formed in a substantially rectangular shape, and is formed on the front part of the inner peripheral surface thereof along the outer shape of the back electrode plate 38. An arcuate recess 40a is formed at a location. The back electrode plate 38 is fitted and fixed to the arcuate recess 40 a of the insulating bush 40.

  5A is a perspective view showing the gate spring 22, FIG. 5B is a front view thereof, and FIG. 5C is a side view thereof. FIG. 5D is a diagram showing a contact point between the back electrode plate 38 and a land portion 58 to be described later when the gate spring 22 is disposed in the electret condenser microphone 10.

  As shown in these figures, the gate spring 22 is a leaf spring terminal formed in an inverted “h” shape by punching a stainless steel plate into a substantially rectangular ring shape and bending a part thereof. is there. As shown in FIG. 4, the gate spring 22 is integrally formed with a cut and raised portion 22a extending obliquely rearward toward the internal space.

  Further, as shown in FIGS. 5 (c) and 5 (d), the gate spring 22 serves as a base portion of the gate spring 22, and the tip portion thereof has a back electrode when disposed in the electret condenser microphone 10. A base portion 22b to be a contact point 22f with the plate 38 is formed.

  Further, a base portion 22c configured on the same plane as the cut and raised portion 22a is formed at a position connecting the base portion 22b and the cut and raised portion 22a. The connecting portion between the base portion 22b and the base portion 22c is bent into a substantially U shape. Further, the tip of the base portion 22c is a contact 22g with the back electrode plate 38 like the base portion 22b.

  Further, a cut and raised end portion 22d that is bent substantially parallel to the base portion 22b is formed at the tip of the cut and raised portion 22a. The cut-and-raised end portion 22d is a contact point 22h with a land portion 58, which will be described later, when the cut-and-raised portion 22a and the cut-and-raised end portion 22d are bent in the electret condenser microphone 10. It should be noted that all the surfaces of the cut and raised end portion 22d facing the land portion 58 can be used as contacts according to the bending angle of the cut and raised end portion 22d.

  Further, as shown in FIG. 5B, the contact point 22f is formed on a straight line portion on one side of the gate spring 22, and similarly, the contact point 22g is formed on a straight line portion on one side of the same plane. The

  As described above, the gate spring 22 has the cut-and-raised portion 22a cut so that the cut-and-raised portion 22a and the base portion 22c are formed on the same plane, and the base portion 22b and the cut-and-raised end portion 22d are formed. Constructed approximately parallel. Further, by pressing with the contact 22h, a pressing force is evenly applied to the parallel contacts 22f and 22g formed on the linear portion, and for example, the back electrode plate 38 supported by the contact 22f and the contact 22g is stably pressed. It becomes possible to press.

  The contact frame 32B is formed by punching a stainless steel plate into a substantially rectangular ring shape and bending a part thereof. Cover body contact portions 32c that are in contact with the open rear end edge 32b of the cover body 32A and are welded to the cover body 32A are formed on the outer periphery of the four sides of the contact frame 32B. Positioning pieces 32d for inscribed engagement with the cover main body 32A to position the open rear end edge 32b of the cover main body 32A and the cover main body abutting portion 32c are provided at the four corners of the contact frame 32B. Is formed. Further, elastic pieces 32e extending obliquely rearward are formed by cutting and raising at the inner periphery of the four sides of the contact frame 32B.

  The microphone assembly 14 is manufactured in a state in which the cover body 32A of the metal cover 32 is arranged upside down with respect to FIG. 3, and within the cover body 32A, the diaphragm subassembly 34, the spacer 36, and the back electrode plate 38. The insulating bush 40 is dropped in this order, and the contact frame 32B is welded to the open rear end edge 32b of the cover body 32A.

  FIG. 6 is a front view showing the base housing 52 of the housing 12 together with the field effect transistor 16 and the capacitors 18 and 20.

  As shown in this figure, the base housing 52 includes a substantially square rear wall 52A and an outer peripheral wall 52B extending forward from the outer peripheral edge thereof, and four terminal members 56A, 56B1, 56B2, 56C are formed by insert molding. And is formed integrally. These four terminal members 56A, 56B1, 56B2, and 56C are formed as inserts by punching and bending a strip-shaped conductive member.

  One end portions of the terminal members 56A, 56B1, 56B2, and 56C are exposed as three land portions 56Aa, 56Ba, and 56Ca that constitute a part of the conductive pattern P on the inner surface of the rear wall 52A. On the other hand, the other end portions of the terminal members 56A, 56B1, 56B2, and 56C are exposed as four external connection terminal portions 56Ab, 56B1b, 56B2b, and 56Cb on the outer surface of the rear wall 52A. Each of the external connection terminal portions 56Ab, 56B1b, 56B2b, 56Cb is formed in an L shape so as to go from the outer surface of the rear wall 52A to the outer surface of the outer peripheral wall 52B in the vicinity of each corner portion of the rear wall 52A. At that time, each external connection terminal portion 56Ab, 56B1b, 56B2b, 56Cb is formed flush with the outer surface of the rear wall 52A by insert molding with respect to the rear wall 52A, and is inserted with respect to the outer peripheral wall 52B. It is formed so as to protrude from the outer surface of the outer peripheral wall 52B by a thickness by cutting and bending after molding.

  Of the four terminal members 56A, 56B1, 56B2, and 56C, the terminal member 56A is an output terminal that is connected to a power source via a load resistor when mounted on the external substrate, and the terminal members 56B1 and 56B2 are ground terminals. The remaining one terminal member 56C is a dummy terminal.

  A through hole 52 a that divides the conductive pattern P is formed in the rear wall 52 </ b> A of the base housing 52. The through hole 52a is formed by dividing the conductive pattern P by inserting a pin or irradiating a laser beam. As a result, a new land portion 58 electrically separated from the land portions 56Aa and 56Ca is formed on the inner surface of the rear wall 52A of the base housing 52. The through hole 52a of the rear wall 52A is filled with a reactive curable adhesive A3 as a sealant for isolating the space in the base housing 52 from the external space. As this reaction curable adhesive A3, a two-component reaction curable adhesive is used.

  The field effect transistor 16 and the capacitors 18 and 20 are mounted on the base housing 52 at predetermined portions of the conductive pattern P.

  The field effect transistor 16 is an element that converts the change in capacitance of the electret capacitor portion C into an electrical impedance, and the drain electrode D is electrically connected to the land portion 56Aa of the terminal member 56A, and the source electrode S is connected to the terminal member 56B. The land portion 56Ba is electrically connected, and the gate electrode G is electrically connected to the land portion 58. Capacitors 18 and 20 are two types of capacitors having different electrostatic capacities provided for noise removal, and are arranged in parallel so as to straddle land portion 56Aa of terminal member 56A and land portion 56Ba of terminal member 56B. Implemented in.

  As shown by a two-dot chain line in the drawing, the land 58 is in contact with the tip of the cut and raised portion 22 a of the gate spring 22. In the no-load state, the dimension of the gate spring 22 in the front-rear direction is set to a value that is somewhat larger than the distance between the rear surface of the back electrode plate 38 and the inner surface of the rear wall 52A of the base housing 52. At the stage of completing the assembly of the electret condenser microphone 10, the cut-and-raised portion 22a is bent and elastically presses the back electrode plate 38 forward. As a result, the gate electrode G of the field effect transistor 16 is reliably conducted to the back electrode plate main body 38A via the land portion 58 and the gate spring 22.

  At this time, a gap of about 0.05 mm to 0.1 mm is formed between the insulating bush 40 and the contact frame 32B. This is because the back electrode plate 38 and the insulating bush 40 are fitted, so that the back electrode plate main body 38A is pressed forward by the gate spring 22 and at the same time the insulating bush 40 moves away from the contact frame 32B. This is due to the displacement.

  In addition, as shown by a two-dot chain line in the figure, the tip portions of two elastic pieces 32e out of the four elastic pieces 32e of the contact frame 32B are in contact with the land portions 56Ba and 56Ca. The dimension in the front-rear direction of each elastic piece 32e is set to a value that is somewhat larger than the distance between the rear surface of the contact frame 32B and the inner surface of the rear wall 52A of the base housing 52, whereby the assembly of the electret condenser microphone 10 is performed. At the completion stage, each elastic piece 32e is bent. As a result, the source electrode S of the field effect transistor 16 is electrically connected to the vibration film 34A via the land portions 56Ba of the terminal members 56B1 and 56B2, the contact frame 32B, the cover body 32A, and the support ring 34B, and the terminal member 56C. The land portion 56Ca is also electrically connected so that the terminal member 56C can also be used as a ground terminal.

  A recess 52b having a predetermined shape is formed on the outer surface of the rear wall 52A of the base housing 52. A metal shield plate 60 thinner than the depth of the recess 52b is provided in the recess 52b. The land portions 56Ba and 56Ca are exposed on the outer surface of the recess 52b, and the shield plate 60 is brought into contact with the land portions 56Ba and 56Ca.

  The top housing 54 includes a front wall 54A having the same shape as the rear wall of the base housing 52, and an outer peripheral wall 54B extending rearward from the outer peripheral edge of the front wall 54A. A plurality of sound holes 54 a are formed in the front wall 54 </ b> A of the top housing 54.

  Further, a cover body 32A of the metal cover 32 is bonded and fixed to the inner surface of the front wall 54A of the top housing 54, so that the space in the housing 12 is divided forward and backward with the vibration film 34A as a boundary. It has become.

  The ultrasonic welding between the base housing 52 and the top housing 54 is performed as follows.

  That is, as shown in FIG. 6, in the base housing 52 before ultrasonic welding, the front end face 52c of the outer peripheral wall 52B is formed in a substantially pyramid shape over the entire circumference. On the other hand, the top housing 54 before ultrasonic welding has a rear end surface 54b of the outer peripheral wall 54B formed in a flat shape over the entire circumference. Then, by applying ultrasonic vibration in a state where the front end surface 52c of the outer peripheral wall 52B and the rear end surface 54b of the outer peripheral wall 54B are in surface contact over the entire periphery, mainly the vicinity of the front end surface of the outer peripheral wall 52B of the base housing 52 The portion is plastically deformed, and as shown in FIG. 1, the front end surface 52c of the outer peripheral wall 52B and the rear end surface 54b of the outer peripheral wall 54B are welded and fixed over the entire periphery.

As described above in detail, in the present embodiment, the gate spring 22 that is a leaf spring terminal has two parallel straight portions, and a base portion that has a connecting portion for connecting the two straight portions. 22b, the base portion 22c, the cut and raised portion 22a, and the connecting portion between the base portion 22b and the base portion 22c are bent in a substantially U shape, and the cut and raised portion 22a is near the end portion. A cut-and-raised end portion 22d that is bent into a substantially U-shape is provided. For this reason, with respect to the object pressed by the gate spring 22, the connecting portion is bent in a substantially U shape, and the parallel portions of the two sides can be pressed as contact points. An equal force is applied from the contact point, and the object can be supported without bias.
Also, by folding the vicinity of the end of the cut-and-raised part 22a into a substantially U-shape, the fulcrum can be moved from the end to the inside of the spring, so that it is possible to apply a force in the direction of spring bending compared to the end Thus, a stronger spring force can be obtained. Further, by bending the vicinity of the end of the cut-and-raised portion 22a into a substantially U shape, a flat portion or an R portion can be formed at the end, so that the contact partner can be reliably contacted without being damaged. It becomes possible.

  Further, in the present embodiment, the gate spring 22 is used for the conductive portion for electrically connecting the back electrode plate 38 and the land portion 58 on the circuit board. By contacting the contact 22f and the contact 22g, which are linear portions of two parallel sides of the spring 22, and bringing the cut-and-raised end portion 22d of the cut-and-raised portion 22a into contact with the land portion 58 of the circuit board, the back electrode plate 38 can be pressed in a stable posture by the gate spring 22. In addition, since the leaf spring terminal can be formed thinner than the coil spring terminal, the thickness of the electret condenser microphone 10 as a whole can be reduced by adapting this. Furthermore, the contact 22f and the contact 22g, which are two straight sides of the gate spring 22, that are parallel to the gate electrode 22 are brought into contact with the back electrode plate 38, and the contact 22h of the cut and raised end 22d is brought into contact with the land 58 of the circuit board. Further, it becomes possible to apply a uniform pressing force to both ends of the back electrode plate 38, the back electrode plate 38 is not tilted, and a uniform product can be manufactured. In addition, since the contact 22h of the cut and raised end 22d is brought into contact with the land portion 58 of the circuit board, it can be pressed against the land portion 58 of the circuit board with a large pressing force, and there is no fear of poor conduction and more uniform. It is possible to manufacture a product with high yield.

Side sectional view which shows the state which has arrange | positioned the electret condenser microphone used as the object of the manufacturing method which concerns on one Embodiment of this invention upwards upwards The perspective view which shows the said electret condenser microphone disassembled into main components and it sees from diagonally behind The perspective view which shows the microphone assembly of the above-mentioned electret condenser microphone disassembled for each component and is viewed obliquely from the rear together with the gate spring. The front view which shows an insulating bush and a contact frame with a gate spring among the said microphone assemblies. A perspective view (a) showing the gate spring 22, a front view (b) thereof, a side view thereof (c), and a back electrode plate 38 and a land portion 58 when the gate spring 22 is disposed in the electret condenser microphone 10. (D) which shows the contact with The front view which shows the base housing of the housing of the said electret condenser microphone with a field effect transistor and a capacitor | condenser The perspective view which shows the mode of the adhesion fixation of the cover main body of the metal cover with respect to the front part wall of the top housing of the said housing

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Electret condenser microphone 12 Housing 14 Microphone assembly 16 Field effect transistor (impedance conversion element)
18, 20 Capacitor 22 Gate spring 22a Cut and raised portion 22b and 22c Base portion 22d Cut and raised end portion 22f, 22g and 22h Contact 32 Metal cover 32A Cover body 32B Contact frame 32a Sound hole 32b Open rear edge 32c Cover body contact portion 32d Positioning piece 32e Elastic piece 34 Vibration film subassembly 34A Vibration film 34B Support ring (vibration film support member)
36 spacer 38 back electrode plate 38A back electrode plate main body 38B electret layer 40 insulating bush 40a arcuate recess 52 base housing 52A rear wall 52B outer wall 52a through hole 52b recess 52c front end surface 54 top housing 54A front wall 54B outer wall 54a sound Hole 54b Rear end face 56A, 56B1, 56B2, 56C Terminal member 56Aa, 56Ba, 56Ca Land portion 56Ab, 56B1b, 56B2b, 56Cb External connection terminal portion 58 Land portion 60 Shield plate C Electret capacitor portion D Drain electrode G Gate electrode P Conductive pattern S source electrode

Claims (4)

A base having two straight sides parallel to each other and having a connecting portion for connecting the two straight sides;
A cut and raised portion cut and raised from the inside of the straight portion of the base,
With
The leaf spring terminal, wherein the connecting portion is bent into a substantially U shape. 2. The leaf spring terminal according to claim 1, wherein the cut-and-raised portion is bent in a substantially U-shape near the end portion. An electret condenser microphone using the leaf spring terminal according to claim 1 or 2,
A capacitor part including a diaphragm and a back plate for converting vibration due to sound or the like into capacitance change;
A circuit board including an impedance conversion element for converting the capacitance change converted by the capacitor unit into an electrical signal;
A conduction part for electrically connecting the capacitor part and the circuit board;
Have
An electret condenser microphone using the leaf spring terminal as the conducting portion. 4. The electret according to claim 3, wherein the leaf spring terminal has the two straight sides parallel to the capacitor portion in contact with each other and the end portion of the cut-and-raised portion in contact with the circuit board. Condenser microphone.

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