JP2011135481A - Unidirectional capacitor microphone unit, and close-talking capacitor microphone - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a unidirectional capacitor microphone unit which exhibits an excellent directional frequency response, and in which a rear sound terminal is hardly exposed to an external electric field as a noise source even in any posture, and to provide a close-talking capacitor microphone using the same. <P>SOLUTION: The unidirectional capacitor microphone unit includes a diaphragm 11, a diaphragm holder 6 to which the diaphragm 11 is fixed, a fixed electrode 6, a printed circuit board 10, an insulation seat 7 provided to the back side of the fixed electrode 6, and a unit case 3, wherein the printed circuit board 10 and insulation seat 7 form a rear sound terminal formed of at least one hole. A both-side through hole plating 22 is applied to the hole of the printed circuit board 10 forming the rear sound terminal to electrically connect plating on both surfaces of the printed substrate 10 to a plating 23 on the peripheral wall of the hole of the printed circuit board 10, and conductive cloth 21 is fitted to the hole of the printed circuit board 10. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a unidirectional condenser microphone unit suitable for use in a close-talking condenser microphone and a close-talking condenser microphone using the same.

  As a so-called vocal microphone during sports performance or music performance, there is a headset having a microphone and a pair of left and right speakers as shown in FIG. A conventional headset 19 shown in FIG. 7 has an ear speaker 17 that is in contact with both ears of a user, a headband 18, a flexible pipe 2, and a close talk attached to the tip of the flexible pipe 2 (gooseneck). A type condenser microphone 16 is provided. In addition, the headset 19 extends the flexible pipe 2 from the ear speaker 17 and one ear speaker 17 of a general headphone composed of the headband 18 to the position of the user's mouth. The close-talking condenser microphone 16 used for such a headset 19 incorporates a unidirectional condenser microphone unit as mainly described in Patent Document 1.

  FIG. 8 shows an example of a close-talking condenser microphone 16 used in a conventional headset. The close-talking condenser microphone 16 mainly includes a unidirectional condenser microphone unit 15, a microphone case 12 that houses the unidirectional condenser microphone unit 15, and a shield wire 14 for conducting an audio signal and the like outside the microphone. And the flexible pipe 2 that protects the shield wire 14.

  In FIG. 8, the unidirectional condenser microphone unit 15 housed in the microphone case 12 is interposed between the diaphragm 11, the diaphragm holder 5, the fixed pole 6, and the diaphragm 11 and the fixed pole 6. A spacer (not shown), a printed circuit board 10, an insulating seat 7 provided on the back side (lower side in FIG. 8) of the fixed pole 8, and a sound wave introduction hole on the front side (upper side in FIG. 8) On the side (the lower side in FIG. 8), there is a unit case 3 in which the printed circuit board 10 is arranged. Each component in the unit case 3 is positioned by a fixed pole 6 and an insulating seat 7 made of an insulating material. The insulating seat 7 is formed with an acoustic terminal hole 8 that communicates from the back side of the fixed pole 6 (the lower side in FIG. 8) to the outside of the unit case 3.

  The printed circuit board 10 is disposed on the back side of the insulating seat 7 (the lower side in FIG. 8), and the bent part of the open end edge of the unit case 3 presses the rear surface of the printed circuit board 10. The unit case 3 is positioned and fixed. On the front side of the printed board 10 (upper side in FIG. 8), an FET 9 constituting an impedance converter is disposed. In order to electrically connect the FET 9 and the fixed electrode 6, the terminal of the FET 9 is brought into contact with the connection portion 4 extending from the fixed electrode 6.

  The shield wire 14 is surrounded by the flexible pipe 2, and the flexible pipe 2 communicates with the microphone case 12. The shield wire 14 is routed downward along the outer peripheral surface of the unit case 3 in FIG. 8 and connected to a predetermined wiring pattern on the lower surface of the printed circuit board 10. The shield wire 14 is made of a shield-coated wire, and its wiring is composed of three lines: a signal line, a power line, and a shield line. The microphone case 12 has a cylindrical shape in which the front side (upper side in FIG. 8) and the rear side (lower side in FIG. 8) are open, and the protection member 13 is covered on the front side and the rear side. These protective members 13 are made of a net-like member, for example, and have sound wave introducing holes.

  A plurality of holes 10 </ b> A are provided in the printed circuit board 10, and the rear acoustic terminal is formed together with the acoustic terminal hole 8. On the front side of the printed board 10 (upper side in FIG. 8), an FET 9 constituting an impedance converter is disposed. In order to electrically connect the FET 9 and the fixed electrode 6, the terminal of the FET 9 is brought into contact with the connection portion 4 extending from the fixed electrode 6. When an unnecessary electric field is applied to the rear acoustic terminal, the electric field is electrostatically coupled to the unit component (for example, the fixed electrode 6), and noise is generated. Therefore, it is necessary to electrostatically shield the plurality of holes 10A of the printed circuit board 10. Generally, as a countermeasure, a method of reducing the opening area of the plurality of holes 10A is taken. In such a case, the acoustic capacity of the space in which the FET 9 is built and the acoustic mass of the plurality of holes 10A of the printed board 10 resonate. Degraded directional frequency response.

  In general, in the close-talking condenser microphone 16, the unidirectional condenser microphone 15 needs to point the sound collection axis of the close-talking condenser microphone 16 toward the mouth during use. Therefore, the unidirectional condenser microphone unit 15 used for the close-talking condenser microphone 16 is usually used in a posture in which the back surface is angled (tilted) with respect to the horizontal plane, and the rear acoustic terminal serves as a noise source. It becomes easy to be exposed to an external electric field. The front acoustic terminal on the diaphragm 11 side can electrostatically shield the noise source by the unit case 3 and the diaphragm 11, but the plurality of holes 10 </ b> A of the printed circuit board 10 that is the rear acoustic terminal are not sufficiently shielded. . In recent years, with the spread of mobile phones and the like, a noise source has become familiar, and electromagnetic waves from this noise source enter through the hole 10A to generate large noise.

JP 2008-72583 A

  The present invention makes it difficult for the rear acoustic terminal to be exposed to an external electric field that becomes a noise source, is sufficiently shielded, can prevent noise caused by electromagnetic waves emitted from a mobile phone, etc. Unidirectionality that prevents resonance of the acoustic mass between the capacitor and the hole in the printed circuit board, has a good directional frequency response, and is not exposed to an external electric field that causes the rear acoustic terminal to be a noise source in any position The object is to provide a condenser microphone unit and a close-talking condenser microphone using the same.

  The present invention includes a diaphragm, a diaphragm holder to which the diaphragm is fixed, a fixed pole that is disposed opposite to the diaphragm with a gap therebetween and constitutes a capacitor, and an impedance converter. A printed circuit board to be disposed; an insulator provided on the back side of the fixed pole; and a unit case in which these members are incorporated and a sound wave introduction hole is provided on the front side and the printed circuit board is disposed on the back side. The printed circuit board and the insulator are unidirectional condenser microphone units forming a rear acoustic terminal composed of at least one hole, and are formed in the holes of the printed circuit board forming the rear acoustic terminal. Double-sided through-hole plating is applied so that the plating on both sides of the printed circuit board and the peripheral wall of the hole in the printed circuit board are conducted, and the conductive cloth is attached to the hole in the printed circuit board. And required features.

  According to the present invention, the holes of the printed circuit board are subjected to double-sided through-hole plating and the conductive cloth is attached, so that the rear acoustic terminal is not easily exposed to an external electric field that becomes a noise source, and the rear acoustic terminal is sufficiently electrostatic. It is possible to provide a unidirectional condenser microphone that is shielded and can prevent a large noise caused by electromagnetic waves emitted from a mobile phone or the like. In addition, the conductive cloth also acts as an acoustic resistance, which can damp the resonance between the acoustic capacity of the space in which the FET is built-in and the acoustic mass of the printed circuit board opening. However, it is possible to provide a unidirectional condenser microphone and a close-talking condenser microphone in which the rear acoustic terminal is not easily exposed to an external electric field that becomes a noise source.

It is sectional drawing which shows the Example of the unidirectional condenser microphone concerning this invention. It is a front view of the said Example. It is sectional drawing which shows the close-talking type | mold condenser microphone concerning this invention. It is a rear view which shows the Example of the unidirectional condenser microphone unit concerning this invention. It is a side view of the said Example. It is sectional drawing which shows the other aspect of the unidirectional microphone and close-talking-type condenser microphone concerning this invention. It is a front view which shows an example of the conventional headset. It is sectional drawing which shows an example of the conventional close-talking type | mold condenser microphone.

  Embodiments of a unidirectional condenser microphone unit according to the present invention will be described below with reference to the drawings. The unidirectional condenser microphone unit and the close-talking condenser microphone according to the present invention are not particularly limited to the configuration of this embodiment. Moreover, the same code | symbol was attached | subjected to the component similar to FIG. 7, FIG.

  In FIG. 1, a unidirectional condenser microphone unit 15 includes a diaphragm 11 made of a disk-shaped thin film, a ring-shaped diaphragm holder 5 to which the peripheral edge of the diaphragm 11 is fixed, and a spacer. By doing so, a disk-shaped fixed pole 6 which is disposed to face the diaphragm 11 with a gap and constitutes a capacitor with the diaphragm 11, a disk-shaped printed board 10 on which an impedance converter is disposed, and a fixed pole 6 and an insulating seat 7 made of an insulator provided on the back side (lower side in FIG. 1), and these members are incorporated, and a sound wave introduction hole is provided on the front side (upper side in FIG. 1). 1 has a unit case 3 on which a printed circuit board 10 is disposed. The shape of the unit case 3 to be used can be selected as appropriate, and may be a cylindrical shape as envisaged in the embodiment of FIG. 1, or may be another shape, for example, a polygonal shape.

  When the bent portion 3B formed on the open end side of the unit case 3 pushes the back surface (the lower side in FIG. 1) of the printed circuit board 10, the printed circuit board 10, the insulating seat 7, the fixed pole 6, the spacer (not shown), and the diaphragm 11 are pressed toward the inner bottom surface of the unit case 3 in this order, and these members are positioned and fixed in the unit case 3. The insulating seat 7 is left with a peripheral wall up to a height at which the FET 9 can be provided, and a space 20 </ b> A is provided by the peripheral wall of the insulating seat 7 and the printed board 10. The insulating seat 7 is provided with a recessed portion 7A on the front surface (upper surface in FIG. 1) in contact with the fixed pole 6 and the rear surface on the opposite side (lower surface in FIG. 1). The front and rear recessed portions 7A communicate with the space 20A in the unit case 3 formed by the printed circuit board 10 and the peripheral wall of the insulating seat 7. By pressing the back surface of the printed circuit board 10, a space 20 </ b> A created by the end portion of the peripheral surface portion of the insulating seat 7, the printed circuit board 10, and a space 21 outside the unit case 3 are sorted. The insulating seat 7 is formed with an acoustic terminal hole 8 that communicates from the back side of the fixed pole 6 (the lower side in FIG. 1) to the outside of the unit case 3. The acoustic terminal hole 8 is formed in a cylindrical shape. As shown in FIG. 2, the unit case 3 has a circular center hole on the front side thereof and a sound wave introducing hole including four holes formed radially outward from the center hole. The sound wave introduction holes of the unit case 3 are not limited to those described above, and can be designed to have an appropriate shape and number.

  In FIG. 4, a plurality of circular holes 10 </ b> A are formed in the printed circuit board 10 so as to surround the center of the printed circuit board 10. The plurality of holes 10 </ b> A constitute a rear acoustic terminal together with the acoustic terminal hole 8. The number of the plurality of holes 10A can be set to an appropriate number according to the design concept of the microphone. On the front side of the printed circuit board 10, an FET 9 constituting an impedance converter is disposed. There is a connecting portion 4 on the lower surface of the fixed pole 6, and the connecting portion 4 makes the terminal of the FET 9 contact the connecting portion 4 extending from the fixed pole 6 in order to electrically connect the FET 9 and the fixed pole 6. .

  In FIG. 1, a printed circuit board 10 is arranged on the back side (lower side in FIG. 1) of the insulating seat 7. Double-sided through-hole plating is applied from the entire back surface (lower side in FIG. 1) excluding the connection portion with the shield wire 14 of the printed circuit board 10 to the front side (upper side in FIG. 1) of the plurality of holes 10A of the printed circuit board 10. Has been. Double-sided through-hole plating can be performed by an appropriate method such as using a photoresist. As a result, the plating 22 is applied to almost the entire back surface of the printed circuit board 10, the plating of a predetermined pattern is also applied to the front surface, and the plating 23 is also applied to the peripheral walls of the plurality of holes 10A. By this plating 23, the plating 22 on the back surface of the printed circuit board 10 and the plating on the front surface are electrically connected. In addition, a conductive cloth 21 is fitted into the plurality of holes 10A so as to close these holes 10A. By doing so, the plurality of holes 10A of the printed circuit board 10 can be reliably electrostatically shielded, and noise can be prevented by preventing the penetration of an external electric field or electromagnetic waves. Furthermore, the conductive cloth 21 also acts as an acoustic resistance, and can resonate between the acoustic capacitance of the space in which the FET 9 is built and the acoustic mass of the plurality of holes 10A that are the openings of the printed circuit board 10, so that the directional frequency response A good unidirectional condenser microphone can be provided. The number of the plurality of holes 10A can be selected as appropriate, and may be one.

  FIG. 3 shows an embodiment of a close-talking condenser microphone according to the present invention. 3, the close-talking condenser microphone 1 is mainly composed of a unidirectional condenser microphone unit 15 and a condenser microphone case 12 that houses the unidirectional condenser microphone unit 15, as in the conventional example of FIG. 8. A shield wire 14 for conducting an audio signal or the like to the outside of the microphone and a flexible pipe 2 for protecting the shield wire 14 are provided. The unidirectional condenser microphone unit 15 is arranged in the microphone case 12 with its center axis direction aligned with the center axis direction of the cylindrical microphone case 12. Both ends of the microphone case 12 in the central axis direction (vertical direction in FIG. 3) are open, and the protective members 13 are covered on open surfaces at both ends of the central axis direction. The protection member 13 is made of, for example, a net-like member, has a sound wave introducing hole, and is formed in a dish shape.

  A flexible pipe 2 is connected to the outer peripheral wall of the microphone case 12, and a hole 12B penetrating the outer peripheral wall of the microphone case 12 and a central hole 2A of the flexible pipe 2 communicate with each other, and a shield wire 14 is connected to the communication hole. Has been taken over. At both ends in the central axis direction of the microphone case 12, the inner peripheral side is cut in the thickness direction, and a protruding portion 12A protruding toward the inner peripheral side is formed at an intermediate portion in the central axial direction. The protection members 13 at both ends are fitted on the inner peripheral sides of both ends in the central axis direction of the microphone case 12 and are in contact with and fixed to the protrusion 12A. Note that the shape and configuration of the microphone case 12 are not limited to those described above, and an appropriate structure can be selected. The shield wire 14 can be connected to the printed circuit board 10 from the lower side in FIG. 3 by an appropriate method. For example, as shown in FIG. 4, the printed circuit board 10 and the shield wire 14 can be connected to a connection portion 22 </ b> A formed on a portion of the printed circuit board 10 that is not subjected to through-hole plating.

  5 and 6 show another embodiment of the unidirectional condenser microphone unit and the close-talking condenser microphone according to the present invention. The unit case 3 has an opening 3A on the side surface of the peripheral surface. Compared with the conventional example of FIG. 8 or the embodiment of FIGS. 1 and 3, the unidirectional condenser microphone unit 15 in FIG. 6 is provided with a space communicating from the opening 3A to the printed circuit board 10, and from the opening 3A. The difference is that the shield wire 14 is inserted. Three wires of the shield wire 14 are connected to the printed board 10. The insulating seat 7 is left with a peripheral wall up to a height corresponding to the opening 3 </ b> A, and a space is provided by the end portion of the peripheral wall of the insulating seat 7 and the printed board 10. The opening 3A is provided between the front surface of the printed circuit board 10 (upper side in FIG. 6) and the back surface of the fixed electrode 6 (lower side in FIG. 6) in the height direction of the unit case 3 (vertical direction in FIG. 6). It has been.

  As shown in FIG. 6, the bent portion 3 </ b> B formed on the open end side of the unit case 3 pushes the back surface (the lower side of FIG. 6) of the printed circuit board 10, thereby Built-in components such as a spacer (not shown) and the diaphragm 11 are pressed toward the inner bottom surface of the unit case 3 in this order, and these members are positioned and fixed in the unit case 3. In addition, when the back surface of the printed circuit board 10 is pressed, a space 20 formed by the end portion of the peripheral surface portion of the insulating seat 7 and the printed circuit board 10 and a space 21 outside the unit case 3 are sorted. The peripheral surface portion of the insulating seat 7 is formed by cutting out the surface in contact with the opening 3A in the circumferential direction. The space 20 that communicates from the position of the opening 3A to the printed circuit board 10 is provided in the unit case 3, so that the central hole of the flexible pipe 2 and the opening 3A of the unit case 3 that communicates with the central hole are provided. The shield wire 14 is inserted, and the three wires of the shield wire 14 are connected to a predetermined wiring pattern formed on the front side of the printed board 10. An acoustic terminal hole 8 is formed in the insulating seat 7 so as to communicate with the outside of the unit case 3 from the back surface of the fixed pole 6 (the lower side in FIG. 6). The acoustic terminal hole 8 is formed in a cylindrical shape and toward the outside of the unit case 3. The insulating seat 7 is provided with a recessed portion 7A on the front surface in contact with the fixed pole 6 and on the back surface on the opposite side. Each recessed portion 7 </ b> A communicates with the acoustic terminal hole 8, and further communicates with the space 20 in the unit case 3, which is formed by the peripheral wall of the back surface of the insulating seat 7 and the printed circuit board 10.

  As in the embodiment of FIGS. 1 and 3, in FIG. 6, the plating 10 is applied to the plurality of holes 10A of the printed board by an appropriate method such as using a photoresist or the like. Moreover, the conductive cloth 21 is attached to the plurality of holes 10A so as to close the holes. Other parts are the same as those of the embodiment of FIGS. 1 to 3, and the description thereof will be omitted below. By doing so, the plurality of holes 10A of the printed circuit board 10 can be reliably electrostatically shielded, and noise due to the entry of an external electric field or electromagnetic waves can be prevented. Furthermore, since the conductive cloth 21 also acts as an acoustic resistance and can damp resonance between the acoustic capacity of the space in which the FET 9 is built and the acoustic mass of the hole of the printed circuit board 10, the unidirectional with a good directional frequency response is achieved. A capacitive condenser microphone can be provided. Further, even if the posture of the microphone unit is tilted, the rear acoustic terminal is not easily exposed to an external electric field that becomes a noise source, so that a unidirectional condenser microphone suitable for a close-talking condenser microphone can be provided. In addition, since the connection portion between the condenser microphone unit 15 and the shield wire 14 is connected to the printed circuit board 10 inside the unit case 3, it is possible to prevent noise from being generated due to intrusion of electromagnetic waves from the outside. Further, since the bent portions of the shield wire 14 are few and the bent angle is small, the microphone portion can be easily assembled, and the shield wire 14 can be prevented from being broken and disconnected.

  The example of the embodiment of the present invention has been described above, but the present invention is not limited to this example. For example, the unidirectional condenser microphone according to the present invention may be used as a close-talking condenser microphone for a headset for communication when riding a motorcycle.

DESCRIPTION OF SYMBOLS 1 Close-talking type condenser microphone 2 Flexible pipe 3 Unit case 4 Connection part 5 Diaphragm holder 6 Fixed pole 7 Insulation seat 8 Acoustic terminal hole 9 FET
10 Printed Circuit Board 11 Diaphragm 12 Microphone Case 13 Microphone Case Ami 14 Shield Wire 15 Unidirectional Capacitor Microphone Unit 21 Conductive Cloth 22 Plating 23 Plating

Claims (6)

A diaphragm,
A diaphragm holder to which the diaphragm is fixed;
A fixed pole that is disposed opposite to the diaphragm with a gap and constitutes a capacitor with the diaphragm;
A printed circuit board on which the impedance converter is disposed;
An insulator provided on the back side of the fixed pole;
A unit case in which these members are incorporated and a sound wave introduction hole is provided on the front side and the printed circuit board is disposed on the back side,
The printed circuit board and the insulator are unidirectional condenser microphone units forming a rear acoustic terminal composed of at least one hole, and
The printed circuit board hole forming the rear acoustic terminal is subjected to double-sided through-hole plating, and the printed circuit board double-sided plating and the printed circuit board hole peripheral wall are electrically connected,
A unidirectional condenser microphone unit, wherein a conductive cloth is attached to the hole of the printed circuit board.   2. The unidirectional condenser microphone unit according to claim 1, wherein the back side of the printed board is plated over substantially the entire surface except for the holes of the printed board. 3.   The unit case has an opening between the front surface of the printed circuit board in the height direction and the back surface of the fixed pole, and a space that communicates from the opening to the front surface of the printed circuit board. The unidirectional condenser microphone unit according to claim 1 or 2.   The unidirectional condenser microphone unit according to claim 3, wherein a shield wire inserted from an opening of the unit case is connected to the front side of the printed circuit board.   A unidirectional condenser microphone unit according to any one of claims 1 to 4 is fixed inside, and a microphone case having sound wave introduction holes on the front side and the back side of the unit case is provided. Close-talking condenser microphone.   6. A flexible pipe is connected to the microphone case, a hole penetrating the peripheral wall of the microphone case and a central hole of the flexible pipe communicate with each other, and a shield wire is passed through the hole connecting these. Close-talking condenser microphone described in 1.

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