JP2006024974A - Condenser microphone - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a condenser microphone with high sensitivity in spite of its low profile. <P>SOLUTION: The condenser microphone 10 is configured with a housing 12 wherein an insulating bush 14, a capacitor unit 16, a contact spring 18, three electronic chip components 20, 22, 24, and a circuit board 26 are accommodated. A communicating groove 12b1 for communicatively connecting a communicating groove 14a1 provided to the insulating bush 14 to an external space of the condenser microphone 10 is provided to a lower end part 12b of the housing 12. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a condenser microphone, and more particularly to the structure of an electronic chip installation chamber.

  In general, a condenser microphone has a capacitor part in which a vibration film and a back electrode plate are arranged to face each other, and an electronic chip component such as an impedance conversion element that converts an impedance of the capacitor part into an electric impedance is provided. The structure is mounted on a circuit board.

  In this case, “Patent Document 1” describes a condenser microphone in which an electronic chip installation air chamber is provided on the outer peripheral side of a capacitor portion, and an electronic chip component is arranged there.

JP 2001-157297 A

  In a condenser microphone mounted on a mobile phone or the like, it is strongly demanded to reduce its thickness. With this reduction in thickness, it has become difficult to make a large space behind the capacitor portion. When the back space is narrowed, the acoustic load increases and the sensitivity of the condenser microphone decreases. Therefore, in the conventional condenser microphone, as described in the above-mentioned “Patent Document 1”, in order to make a large back space of the capacitor portion, the air space where the electronic chip is installed is sealed, It was comprised so that it could connect and form one back space.

  However, with conventional condenser microphones, there is a limit to securing the back space in a limited space while being forced to reduce the thickness. As a result, the necessary back space cannot be secured and the acoustic load increases. There is a problem that a condenser microphone having sufficient sensitivity cannot be realized.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a highly sensitive condenser microphone even in a thin condenser condenser microphone.

  The present invention is intended to achieve the above-mentioned object by devising the structure of the air chamber where the electronic chip is installed.

  That is, the capacitor microphone according to the present invention is mounted on the outer peripheral side of the capacitor part, the capacitor part in which the diaphragm and the back electrode plate are arranged to face each other, at least one electronic chip part, and the electronic chip part. In a condenser microphone comprising a circuit board, a back air chamber provided between the circuit board and the capacitor unit, and an electronic chip installation air chamber in which the electronic chip is installed, the back air chamber and The electronic chip installation chamber is communicated by a rear air chamber communication section, and the electronic chip installation chamber and the outside of the condenser microphone are communicated by an external communication section.

  The type of the “at least one electronic chip component” is not particularly limited, and for example, an impedance conversion element, a capacitor, a resistor, or the like can be employed.

  Further, the back air chamber communication part is provided at one end of the electronic chip installation air chamber, and the external communication part is provided at the other end of the electronic chip installation air chamber. The electronic chip is installed so as to separate one end and the other end of the electronic chip installation air chamber.

  Furthermore, the electronic chip component is an impedance conversion element.

  As shown in the above configuration, in the condenser microphone according to the present invention, the back air chamber and the electronic chip installation air chamber communicate with each other through the back air chamber communication portion, and the electronic chip installation air chamber and the outside of the condenser microphone communicate with each other. Therefore, a condenser microphone with reduced acoustic resistance and high sensitivity can be obtained.

  In the above configuration, the electronic chip installation air chamber is provided with a rear air chamber communication portion, the other end is provided with an external communication portion, and the electronic chip installation air chamber is separated from one end and the other end. By connecting the back of the capacitor unit to the external space, the sound that enters from the external space through the external communication unit is reflected and attenuated by the electronic chip installation chamber in front of the electronic chip. Can be prevented.

  Further, in the above configuration, since the electronic chip component is an impedance conversion element that is the largest electronic chip in the condenser microphone, a large wall is formed in the air chamber where the electronic chip is installed, and sound directly enters the back air chamber from the outside. Therefore, the effect of preventing the occurrence of directivity can be enhanced.

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

  FIG. 1 is a side sectional view showing a condenser microphone 10 according to an embodiment of the present invention, and FIG. 2 is a sectional view taken along line II-II in FIG.

  As shown in these drawings, the condenser microphone 10 is a small electret condenser microphone, and has a low profile and a substantially cylindrical outer shape with a height of about 0.6 mm and a diameter of about 4 mm. .

  In the condenser microphone 10, an insulating bush 14, a capacitor portion 16, a contact spring 18, three electronic chip components 20, 22, and 24, and a circuit board 26 are accommodated in a housing 12. .

  The housing 12 is a cylindrical metal member having a lower end opened, and the lower end 12b of the peripheral wall is bent to the inner peripheral side in a state in which each member is covered from the upper side. A caulking is fixed to the peripheral edge of the substrate 26. A plurality of sound holes 12 a are formed in the upper surface portion of the housing 12. The housing 12 is provided with a communication groove 12b1 in the lower end portion 12b for communicating a communication groove 14a1 provided in an insulating bush 14 described later and the external space of the condenser microphone 10.

  The insulating bush 14 is a synthetic resin member, and has a ring-shaped peripheral wall portion 14 a formed along the inner peripheral surface of the housing 12, and is slightly closer to the inner peripheral side of the peripheral wall portion 14 a than the peripheral wall portion 14 a. The partition wall portion 14b is formed at a low height, and the peripheral wall portion 14a and the partition wall portion 14b form four space portions C1, C2, C3, and C4.

  The space portion C1 is a space that accommodates the capacitor portion 16, and is formed as a relatively large circular space portion. The space portions C2, C3, and C4 are arranged so as to surround the space portion C1 in an arc shape. Formed as a relatively small space portion. At that time, the space portions C3 and C4 communicate with the space portion C1 through a communication groove 14b1 formed on the upper surface of the partition wall portion 14b, thereby expanding the back pressure space of the capacitor portion 16. Yes. The space portion C2 communicates with the space portion C1 via a communication groove 14b2 formed on the upper surface of the partition wall portion 14b, and further communicates with the external space via an external communication passage 14a1 provided in the peripheral wall portion 14a. is doing.

  The capacitor unit 16 includes a diaphragm subassembly 32, a spacer 34, and a back electrode plate 36.

  The vibration membrane subassembly 32 has a vibration film 32A stretched and fixed on the lower surface of a metal support ring 32B, and the vibration film 32A is composed of a polymer film having a metal vapor deposition film formed on the upper surface. . The spacer 34 is composed of a metal thin plate ring. The back electrode plate 36 includes a metal electrode plate main body 36A and an electret layer 36B heat-sealed to the upper surface of the electrode plate main body 36A. The back electrode plate 36 is formed in a substantially cross shape in plan view, but its outer diameter is set to be substantially the same as the outer diameter of the support ring 32B.

  In the capacitor section 16, the vibration film 32 </ b> A of the vibration film subassembly 32 and the electret layer 36 </ b> B of the back electrode plate 36 are opposed to each other with a predetermined minute interval.

  Of the three electronic chip components 20, 22, and 24, the electronic chip component 20 is a junction-type field effect transistor (hereinafter referred to as “FET”), and converts the change in capacitance of the capacitor unit 16 into electrical impedance. Is provided as an impedance conversion element. The remaining two electronic chip components 22 and 24 are two types of capacitors having different electrostatic capacities, and are provided for noise removal. The two capacitors 22 and 24 are both mounted on the circuit board 26 while being accommodated in the space C3.

  The FET 20 is mounted on the circuit board 26 while being accommodated in the space C2, and is disposed in the vicinity of the substantially central portion of the space C2. The space portion C2 is divided into an internal communication space portion C21 and an external communication space portion C22 by arranging the FET 20 in the central portion. The internal communication space portion C21 and the external communication space portion C22 are communicated with the inner wall of the space portion C2 such as the electronic chip side surface path 20a1 on the side surface of the FET 20 and the electronic chip upper surface path 20a2 on the upper surface through the gap between the FETs 20. In addition, the internal communication space C21 communicates with the back air chamber C11 of the capacitor unit 16 through a communication groove 14b2 provided at one end of the space C2. Further, the external communication space C22 communicates with the external space of the condenser microphone 10 via the external communication path 14a1, the outer peripheral gap 12c, and the external communication path 12b1 provided at the other end of the space C2. Further, a soundproofing material such as urethane for preventing directivity may be further disposed on the electronic chip side surface path 20a1 and the electronic chip upper surface path 20a2.

  The external communication path 14a1 is a V-groove having a width of about 80 to 120 μm and a depth of about 40 to 60 μm. The external communication path 14a1 is formed in the insulating bush 14 and is provided at one end of the space C2, and through the outer circumferential clearance 12c. It is in communication with part C22. The external communication path 14a1 may be formed in the circuit board 26.

  The outer peripheral clearance 12 c is a clearance of about 5 to 20 μm formed between the inner peripheral surface of the housing 12 and the outer peripheral surface of the insulating bush 14, and is the clearance between the housing 12 and the insulating bush 14. It is formed over the circumference. The outer peripheral clearance 12c is basically a closed space, and only the external communication path 14a1 and the external communication path 12b1 communicate with other spaces. The outer peripheral gap 12c may be omitted, and in this case, the external communication path 12b1 may be extended to directly communicate with the external communication path 14a1.

  The external communication path 12b1, like the external communication path 14a1, is a V-groove having a width of about 80 to 120 μm and a depth of about 40 to 60 μm, and is formed at a position facing the circuit board 26 at the lower end portion 12b of the housing 12. . The external communication path 12b1 may be formed in the circuit board 26. The external communication path 12b1 only needs to communicate with the external space and the outer peripheral gap 12c, and may not be in the vicinity of the external communication path 14a1.

  The circuit board 26 includes a substrate body 42, conductive layers 44A, 44B, 44C formed in a predetermined pattern on the upper surface 42a of the substrate body 42, and conductive layers 46A, 46B formed on the lower surface 42b of the substrate body 42. It is made up of.

  At that time, the conductive layer 46A is formed at the center of the lower surface 42b of the substrate body 42, and the conductive layer 46B is formed in an annular shape at the outer peripheral edge of the lower surface 42b of the substrate body 42. The conductive layer 46A is electrically connected to the conductive layer 44C via a through hole (not shown), and the conductive layer 46B is electrically connected to the conductive layer 44B via a through hole (not shown).

  The substrate body 42 has a thickness of about 0.06 mm, and the conductive layers 44A, 44B, 44C, the conductive layers 46A, 46B, and the insulating layer 48 all have a thickness of about 0.04 mm. is doing.

  The contact spring 18 is a metal plate spring formed in a substantially annular cone shape. The contact spring 18 is in contact with the electrode plate main body 36A of the back electrode plate 36 at the upper end portion thereof, and the conductive layer of the circuit board 26 at the lower end portion thereof. 44A.

  The FET 20 includes a chip body 20A having a rectangular parallelepiped shape with a height of about 0.3 mm, and three terminal pieces 20G, 20S, and 20D projecting sideways from the chip body 20A.

  The terminal piece 20G is a terminal portion constituting a gate electrode, and the remaining two terminal pieces 20S and 20D are terminal portions constituting a source electrode and a drain electrode. The terminal piece 20G constituting the gate electrode is electrically connected to the electrode plate body 36A of the back electrode plate 36 via the conductive layer 44A and the contact spring 18, and the terminal piece 20S constituting the source electrode is electrically conductive (not shown). Via the conductive layer 44B, the housing 12 and the support ring 32B, the terminal strip 20D constituting the drain electrode is electrically connected to the conductive layer 46A via the conductive layer 44C. And continuity.

  As described above in detail, in the condenser microphone 10 according to the present embodiment, the back surface chamber C11 of the space portion C1 and the space portion C2 that is an air chamber in which the electronic chip is installed are communicated with each other through the communication groove 14b1. Since the portion C2 and the outside of the condenser microphone 10 are communicated with each other by the external communication path 14a1, the outer peripheral gap 12c, and the external communication path 12b1, the acoustic microphone is reduced and the highly sensitive condenser microphone 10 can be obtained.

  Further, a communication groove 14b1 is provided at one end of the space C2 that is an air chamber in which the electronic chip is installed, an external communication path 14a1 is provided at the other end, and the FET ( Since the electronic chip component) 20 is installed, it is possible to prevent the sound from entering from the external space and the directivity from being generated by connecting the back surface of the capacitor unit 16 to the external space. This is because the sound entering from the external space is once reflected and attenuated by the external communication space C22 in front of the FET 20, so that directivity can be reduced. Furthermore, the sound entering from the external space passes through the electronic chip side surface path 20a1 and the electronic chip upper surface path 20a2, which are narrow communication paths formed by the FET 20, the insulating bush 14, and the housing 12, and enters the internal communication space C21. Since the air passes through the communication groove 14b1 which is a narrow communication path again and reaches the rear air chamber C11 on the back surface of the capacitor unit 16, the arrival is further delayed and attenuated, and the effect of reducing the occurrence of directivity is enhanced.

  In particular, since the electronic chip component is composed of the FET 20, it becomes a large wall in the space C2, and the effect of preventing the occurrence of directivity can be enhanced.

Incidentally, it is also possible to use an external communication hole 42c as shown in FIG. 3 in place of the external communication path 14a1 and the external communication path 12b1 as shown in the above embodiment.
FIG. 3 is a cross-sectional view showing a modification of FIG. Note that a description of the same configuration as in FIG. 2 is omitted.

  A condenser microphone 100 shown in the figure is a small electret condenser microphone, similar to the condenser microphone 10, and has a short, substantially cylindrical outer shape having a height of about 0.6 mm and a diameter of about 4 mm. ing.

  In the condenser microphone 100, an insulating bush 140, a capacitor portion 16, a contact spring 18, three electronic chip components 20, 22, and 24, and a circuit board 260 are accommodated in a housing 120. .

  The housing 120 is a cylindrical metal member having a lower end opened, and the circuit is provided by bending the lower end 12b of the peripheral wall to the inner peripheral side in a state in which each member is covered from the upper side. The substrate 260 is caulked and fixed to the periphery. A plurality of sound holes 12 a are formed in the upper surface portion of the housing 120.

  The circuit board 260 includes a substrate body 420, conductive layers 44A, 44B, 44C formed in a predetermined pattern on the upper surface 42a of the substrate body 420, and conductive layers 46A, 46B formed on the lower surface 42b of the substrate body 420. It is made up of.

  The insulating bush 140 is a synthetic resin member, and is formed with a ring-shaped peripheral wall portion 14a formed along the inner peripheral surface of the housing 120, and slightly closer to the inner peripheral side of the peripheral wall portion 14a than the peripheral wall portion 14a. The partition wall portion 14b is formed at a low height, and the peripheral wall portion 14a and the partition wall portion 14b form four space portions C1, C2, C3, and C4.

  The spaces C1, C3, and C4 are the same as in the embodiment shown in FIG. The space portion C2 communicates with the space portion C1 through a communication groove 14b2 formed on the upper surface of the partition wall portion 14b, and further communicates with the external space through an external communication hole 42c provided in the circuit board 260. Yes.

  The external communication hole 42c is a through hole having a diameter of about 30 to 50 μm, is formed in the circuit board 260, is provided at one end of the space C2, and communicates with the external communication space C22. In addition, a conductive layer is formed on the surface of the external communication hole 42c, and the conductive layer 44A, 44B, etc. formed on the upper surface 42a of the substrate body 420 and the conductive layers 46A, 46B, etc. formed on the lower surface 42b serve as a conductive path. The through hole may also be used.

  In the above-described embodiment, the condenser microphone 100 according to this embodiment includes the back surface air chamber C11 of the space C1 and the space C2 that is an air chamber in which the electronic chip is installed communicated with each other through the communication groove 14b1. Since C2 and the outside of the condenser microphone 100 communicate with each other through the external communication hole 42c formed in the circuit board 260, the acoustic resistance is reduced and the condenser microphone 100 with high sensitivity can be obtained.

Side sectional view showing a condenser microphone according to an embodiment of the present invention II-II sectional view of Fig. 1 Sectional drawing which shows the modification of an external communication part

Explanation of symbols

DESCRIPTION OF SYMBOLS 10,100 Condenser microphone 12,120 Housing 12a Sound hole 12b Lower end edge part 12b1 External communication path 12c Outer peripheral clearance 14,140 Insulating bush 14a Peripheral wall part 14a1 External communication path 14b Bulkhead part 14b1 Communication groove 16 Capacitor part 18 Contact spring 20 FET (Electronic chip parts)
20a1 Electronic chip side surface path 20a2 Electronic chip upper surface path 20A Chip body 20D, 20G, 20S Terminal pieces 22, 24 Capacitors (electronic chip components)
22a, 22b Terminal portion 26, 260 Circuit board 32 Vibration membrane subassembly 32A Vibration membrane 32B Support ring 34 Spacer 36 Rear electrode plate 36A Electrode plate body 36B Electret layer 42, 420 Substrate body 42a Upper surface 42c External communication hole 42b Lower surface 44A, 44B , 44C, 46A, 46B Conductive layer 48 Insulating layer C1, C2, C3, C4 Space C11 Rear air chamber C21 Internal communication space C22 External communication space

Claims (3)

A capacitor part in which the diaphragm and the back electrode plate are arranged opposite to each other;
At least one electronic chip component;
A circuit board on which the electronic chip component is mounted on the outer peripheral side of the capacitor unit;
A back air chamber provided between the circuit board and the capacitor unit;
An electronic chip installation chamber in which the electronic chip is installed;
In a condenser microphone comprising:
The back air chamber and the electronic chip installation air chamber communicate with each other through a back air chamber communication portion, and the electronic chip installation air chamber and the outside of the condenser microphone communicate with each other through an external communication portion. Microphone. At one end of the electronic chip installation air chamber, the back air chamber communication portion is provided,
The other end of the electronic chip installation air chamber is provided with an external communication portion,
The condenser microphone according to claim 1, wherein the electronic chip is installed in the electronic chip installation chamber so as to separate one end and the other end of the electronic chip installation chamber.   3. The condenser microphone according to claim 1, wherein the electronic chip component is an impedance conversion element.

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