JP4540535B2 - Condenser microphone - Google Patents

Description

  The present invention relates to a condenser microphone, and more particularly to a microphone unit fixing structure in a unidirectional condenser microphone.

  The tie pin type microphone and the headset type microphone need to be made as small as possible for functional reasons and are required to be inconspicuous. Therefore, a microphone unit case (hereinafter referred to as “unit case”) is manufactured by cutting, and the unit case is coated and used. The components that make up the microphone unit need to be fixed to the unit case by applying an appropriate pressure so that the position does not shift due to vibration or the like. 3 and 4 show examples of this type of conventional condenser microphone.

  3 and 4, reference numeral 10 indicates a unit case made of brass or the like. The unit case 10 has a bottomed cylindrical shape, and an appropriate number of sound introduction holes 101 are formed in a portion corresponding to the bottom plate. A diaphragm ring 13 having a diaphragm 14 is disposed at the bottom of the unit case 10. The outer peripheral edge of the diaphragm 14 is fixed to one surface of the diaphragm ring 13, and a gap corresponding to the thickness of the diaphragm ring 13 is formed between the bottom surface of the unit case 10 and the diaphragm 14. A ring-shaped spacer is fixed to the outer peripheral edge portion on the opposite surface side of the diaphragm 14, and the fixed pole 15 is disposed under the spacer. A gap corresponding to the thickness of the spacer is formed between the diaphragm 14 and the fixed pole 15, but the thickness of the spacer is very thin and the gap is very small and is not clearly shown in the drawing. The components including the diaphragm ring 13, the diaphragm 14, the spacer, and the fixed pole 15 constitute a condenser microphone unit, and this microphone unit is housed in the unit case 10.

  An insulating seat 16 is disposed and fixed on the opposite side of the fixed pole 15 from the diaphragm 14. The insulating seat 16 has a disc shape as a whole, and the surface facing the fixed pole 15 is formed in the shape of a jetty with a circular outer peripheral edge, and this jetty-shaped portion presses the outer peripheral edge of the fixed pole 15 and A gap is formed between the portion other than the outer peripheral edge portion 16 and the fixed pole 15. A concentric cylindrical protrusion is integrally formed on the surface of the insulating seat 16 opposite to the fixed pole 15, and a plug-shaped electrode 18 is fitted to the protrusion. A female screw 20 is formed on the inner peripheral surface of the unit case 10, and the components constituting the microphone unit and the insulating seat 16 are accommodated in the unit case 10. A lock ring 17 is screwed into the female screw 20. The lock ring 17 presses the insulating seat 16 with an appropriate tightening force and positions and fixes the condenser microphone unit in the unit case 10.

  The condenser microphone unit, the insulating seat 16 and the lock ring 17 are arranged in a part of the length of the central axis of the unit case 10, and the shield mesh 21 is arranged in the rear part which is the remaining part of the unit case 10. . The shield mesh 21 is obtained by rounding a conductive mesh made of metal or the like into a cylindrical shape, and is fixed to the inner peripheral surface of the unit case 10 by adhesion. The rear portion of the unit case 10 is a microphone output lead-out portion including the electrode 18. Since the output lead-out portion has a very high impedance, it is easily affected by external electromagnetic waves and the like. When electromagnetic waves enter from this portion, they are detected by the semiconductor constituting the microphone circuit and generate noise. Therefore, a cylindrical shield mesh 21 is fixed to the rear inner peripheral surface of the unit case 10 to prevent electromagnetic waves from entering.

  A cylindrical member 26 integrally having a circuit board plate 25 is screwed into the female screw 20 and fixed to the rear open end of the unit case 10. A cap 11 having a plurality of audio introduction slits 12 is fitted from the front end side of the unit case 10, and the cap 11 covers the outer peripheral surface of the unit case 10 leaving the rear part of the unit case 10. The rear end portion of the unit case 10 is fitted into and coupled to the front end opening portion of the microphone case 23. A cylindrical coupling member 22 is embedded in the open front end portion of the microphone case 23 by integral molding or the like, and a female screw formed on the inner peripheral portion of the front end of the coupling member 22 is formed on the outer peripheral surface of the cylindrical member 26. The unit case 10 and the microphone case 23 are coupled by being screwed into the male screw. The front end portion of the microphone case 23 covers the outer peripheral surface of the rear end portion of the unit case 10. A leaf spring electrode 19 is supported on the circuit board plate 25 via an electrode support, the leaf spring electrode 19 is in pressure contact with the electrode 18, and the leaf spring electrode 19 and the electrode 18 are electrically connected. . These electrodes 18 and 19 are for extracting the output signal of the condenser microphone unit to the outside. The circuit board 25 constitutes an impedance conversion circuit including an FET or the like.

  The illustrated example is an example of a unidirectional condenser microphone, and the sound introduction slit 12 of the cap 11 and the sound introduction hole 101 of the unit case 10 constitute a front acoustic terminal that guides sound to the front side of the diaphragm 14. A rear acoustic terminal having the following configuration is also formed on the rear surface side of the diaphragm 14. That is, an appropriate number of sound introduction holes 102 are formed on the peripheral surface of the unit case 10, and sound introduction holes are also formed in the lock ring 17, the insulating seat 16 and the fixed pole 15, and these sound introduction holes serve as rear acoustic terminals. Is configured. If the voice introduction hole 102 of the unit case 10 is blocked by the shield member, it cannot have unidirectionality, and thus the shield mesh 21 is used as the shield member as described above.

  The diaphragm ring 13, the diaphragm 14, the spacer, the fixed pole 15, etc. constituting the condenser microphone unit need to be fixed to the unit case 10 by applying an appropriate pressing force so as not to be displaced due to vibration or the like. If the pressing force is too small, the microphone unit components will rattle when vibration is applied to the microphone, generating noise. When the pressing force is too large, the components of the microphone unit are deformed, and the performance as a microphone is impaired, such as the deterioration of frequency response and the sensitivity. Therefore, as in the example shown in FIGS. 3 and 4, conventionally, a male screw on the outer periphery of the lock ring 17 is screwed into a female screw 20 formed on the unit case 10, and the above components are pressed against the bottom of the unit case 10 and fixed. is doing. The tightening torque of the lock ring 17 is managed within a predetermined range so that the pressing force by the lock ring 17 becomes an appropriate pressure.

  According to the conventional example shown in FIGS. 3 and 4, structural improvements are made so that a desired performance can be obtained as a unidirectional condenser microphone. However, while adopting a configuration to manage the pressing force of the microphone unit parts against the unit case, on the other hand, measures are individually taken to shield external electromagnetic waves, so the structure is complicated and there are many components. It becomes the structure which becomes. Further, a female screw for screwing the lock ring is formed on the inner peripheral surface of the unit case 10, and this female screw needs to be formed by cutting due to the circumstances described above. The metal powder due to the cutting process of the case 10 may remain and deteriorate the performance as a condenser microphone.

  Therefore, it has been proposed that the metal powder produced by the above-described cutting process does not deteriorate the performance as a condenser microphone. A unit part including a diaphragm ring having a diaphragm, a spacer ring, and a fixed pole supported by an insulating seat is stored in a metal unit case, and the unit part is directed from the rear side of the unit case toward the insulating seat. In the condenser microphone unit that is fixed by the tightening force of the metal lock ring to be screwed in, an example is a structure in which an elastic ring made of a rubber material compressed by the lock ring is interposed between the insulating seat and the lock ring. Yes (see, for example, Patent Document 1).

According to the invention described in Patent Document 1, it is possible to eliminate the adverse effect of metal powder generated by cutting a metal unit case.
However, if the microphone unit can be fixed to the unit case with an appropriate pressing force without cutting the metal unit case, there is no need to take into account the adverse effects of the metal powder generated by the cutting process. There is also room for improvement in the shield structure against electromagnetic waves.

JP 2004-343368 A

The present invention has been made in view of the prior art described above, and by devising a shield structure against electromagnetic waves, the microphone unit is fixed to the unit case with an appropriate pressing force without cutting the unit case. It is an object of the present invention to provide a condenser microphone that does not require any consideration of the adverse effects of metal powder caused by cutting.
Another object of the present invention is to provide a low-cost condenser microphone by reducing the number of parts and the number of manufacturing steps.

  According to the first aspect of the present invention, a condenser microphone unit part including a diaphragm and a fixed pole facing the diaphragm is accommodated in the unit case, and the unit case has a cylindrical shape. The most important feature is that the molded metal mesh for shielding is inserted and prevented from being pulled out, and the condenser microphone unit component is pressed against the unit case by the elastic force of the metal mesh.

  The metal mesh functions as a shield against electromagnetic waves entering from the outside and also functions as a member for fixing the microphone unit component to the unit case, so that the number of components can be reduced. In addition, since the metal mesh presses the microphone unit component against the unit case with its elastic force, the microphone unit component can be appropriately attached to the unit case simply by attaching the metal mesh to the unit case by appropriately designing the dimensions of the metal mesh. It can be pressed with a pressing force of. Since the metal mesh has an elastic force, it can be prevented from coming off by being attached to the unit case using the elastic force, and it is not necessary to form a screw in the unit case. Accordingly, it is possible to solve the problem of remaining metal powder due to cutting.

Hereinafter, embodiments of a condenser microphone according to the present invention will be described with reference to the drawings.
1 and 2, reference numeral 30 denotes a unit case made of brass or the like. The unit case 30 has a bottomed cylindrical shape, and an appropriate number of sound introduction holes 32 as front acoustic terminals are formed in a front plate 31 corresponding to the bottom plate. An appropriate number of openings 34 as rear acoustic terminals are formed in the peripheral wall of the unit case 30 at positions close to the rear end on the open end side. The unit case 30 also has a female thread 35 formed on the inner periphery of the rear end portion, and a circumferential groove 33 is formed adjacent to the inner side of the female thread 35. This circumferential groove 33 functions as an engaging recess for retaining and attaching a metal mesh 50 described later to the unit case 30.

  A condenser microphone unit 40 is accommodated in the unit case 30. The condenser microphone unit 40 is fixed to a diaphragm ring 41, a diaphragm 42 fixed to the rear surface of the diaphragm ring 41, and a ring spacer having an appropriate thickness to the rear surface of the diaphragm 41. The fixed pole 43 and the insulating seat 45 fixed to the rear surface of the fixed pole 43 are mainly configured. A gap corresponding to the thickness of the spacer is formed between the vibration plate 42 and the fixed pole 44. However, the thickness of the spacer is very thin and the gap is very small, and is not clearly shown in the drawing. In the microphone unit 40, the diaphragm ring 41 is in contact with the front plate 31 of the unit case 30. Therefore, the diaphragm ring 41 is interposed between the front plate 31 and the diaphragm 42 of the unit case 30. Is stored in the unit case 30 with a gap corresponding to the thickness of the unit case 30.

  The insulating seat 45 has a disc shape as a whole, and the outer peripheral edge portion is formed in a circular jetty shape on the side facing the fixed pole 43, and this jetty shape portion abuts on the outer peripheral edge portion of the fixed pole 43. A gap is formed between the portion other than the outer peripheral edge of the insulating seat 45 and the fixed pole 43. A concentric cylindrical protrusion is integrally formed on the surface of the insulating seat 45 opposite to the fixed pole 43, and a plug-shaped electrode 48 is fitted to the protrusion. In a state in which the components constituting the microphone unit 40 are housed in the unit case 30, a metal mesh 50 for shielding is inserted into the unit case 30 so as to cover approximately half of the rear end side. The metal mesh 50 is formed by pressing a metal mesh plate into a cylindrical shape, and the whole has an elastic force. The metal mesh 50 also has a gently tapered shape with a diameter decreasing from the rear end side toward the front end side, with the front end 51 formed in an inward flange shape and the rear end 52 formed in an outward flange shape. ing.

  In the metal mesh 50, the inward flange-shaped front end 51 presses the rear outer peripheral edge of the insulating seat 45, which is a condenser microphone unit component, and the outward flange-shaped rear end 52 is on the inner peripheral surface of the unit case 30. By being fitted into the formed circumferential groove 33, the unit case 30 is prevented from coming off. The metal mesh 50 has elasticity as a whole, and the outward flange-like rear end 52 is fitted in the circumferential groove 33 of the unit case 30 as described above using the elasticity. That is, the flange-shaped rear end 52 can be fitted into the circumferential groove as described above by inserting the unit case 30 in a radially compressed state and releasing the compression force. Further, the metal mesh 50 has an outward flange-like rear end 52 fitted in the circumferential groove 33 of the unit case 30, and the flange-like rear end 52 of the metal mesh 50 is engaged with the rear side wall surface of the circumferential groove 33. The dimension in the central axis direction is designed so that a repulsive force in the central axis direction is generated in the state. Therefore, the microphone unit 40 is housed in the unit case 30 and the metal mesh 50 is compressed and attached in the direction of the central axis, and is prevented from being detached. The plate 31 is pressed and positioned with an appropriate pressing force. The metal mesh 50 is also positioned by fitting the outward flange-like rear end 52 of the metal mesh 50 into the circumferential groove 33 of the unit case 30, that is, the recess. The engagement relationship between the rear end of the metal mesh 50 and the unit case 30 may be a relationship in which the concave and convex are reversed. That is, the rear end of the metal mesh 50 may be engaged with the inward convex portion formed on the inner peripheral surface of the unit case 30.

  The condenser microphone according to the above embodiment is a unidirectional condenser microphone, and has an opening for a front acoustic terminal and an opening for a rear acoustic terminal. The number of openings for the front acoustic terminals is configured by a number of openings 32 formed in the front plate 31 of the unit case 30 as appropriate, and the number of openings for the rear sound terminals is a number of openings formed in the peripheral wall of the unit case 30 as appropriate. 34, an opening 46 formed through the insulating seat 45 in the thickness direction as appropriate, and an opening 44 formed through the fixed electrode 43 in the thickness direction. When the metal mesh 50 is attached to the unit case 30 as described above, the metal mesh 50 functions as a shield member that shields electromagnetic waves entering from the outside, and the microphone unit 40 is placed on the front side of the unit case 30 with an appropriate pressing force. It also functions as a member that presses against the plate 31 and positions the microphone unit 40. Further, the metal mesh 50 overlaps the opening 34 and functions as an acoustic resistance.

A cap 55 having a plurality of audio introduction slits 56 is fitted from the front end side of the unit case 30, and the cap 55 covers the outer peripheral surface of the unit case 30, leaving the rear part of the unit case 30. A microphone case (not shown) is coupled to the rear end portion of the unit case 30 by appropriate coupling means, for example, using the female screw 35.
A concentric cylindrical protrusion is integrally formed on the surface of the insulating seat 45 opposite to the fixed pole 43, and a plug-shaped electrode 48 is fitted into the protrusion. The electrode 48 is for extracting the output signal of the condenser microphone unit 40 to the outside. The structure of this signal lead-out portion may be the same as the conventional structure shown in FIGS.

According to the embodiment described above, the following effects can be obtained.
(1) Since the metal mesh 50 has a function as a shield member and a function as a member for pressing and positioning the microphone unit 40 against the unit case 30, it is possible to reduce the number of components and reduce the cost. be able to.
(2) The metal mesh 50 may be attached to the unit case 30 using its elasticity, and an operation such as screwing is not required, so that the assembly is easy and the assembly cost can be reduced.
(3) If the dimensions of the metal mesh 50 are set in advance, the microphone unit 40 is positioned by pressing it with an appropriate pressing force that is neither too strong nor too weak against the unit case 30 simply by being attached to the unit case 30. Therefore, it is not necessary to adjust the pressing force.
(4) The metal mesh 50 only needs to be secured to the unit case 30, and for example, the metal mesh 50 only needs to be engaged with each other. Therefore, the unit case 30 needs to be threaded by conventional cutting. In addition, there is no residual metal powder due to cutting, and it is possible to eliminate problems such as performance deterioration as a condenser microphone due to metal powder.

It is a longitudinal cross-sectional view which decomposes | disassembles and shows the principal part of the Example of the unidirectional condenser microphone concerning this invention. It is a longitudinal cross-sectional view which shows the principal part of the said Example. It is a longitudinal cross-sectional view which shows the example of the conventional unidirectional condenser microphone. It is a longitudinal cross-sectional view which shows the principal part of the said conventional condenser microphone.

Explanation of symbols

30 Unit case 32 Opening as front acoustic terminal 33 Circumferential groove 34 Opening as rear acoustic terminal 40 Condenser microphone unit 41 Diaphragm ring 42 Diaphragm 43 Fixed pole 50 Metal mesh 51 Front end of metal mesh 52 Rear end of metal mesh

Claims (6)

  A condenser microphone unit part including a diaphragm and a fixed pole facing the diaphragm is housed in the unit case, and a metal mesh for shielding formed in a cylindrical shape is inserted into the unit case and prevented from coming off. The condenser microphone unit part is pressed against the unit case by the elastic force of the metal mesh.   2. A unidirectional condenser microphone in which an acoustic terminal is provided at a rear portion of a microphone unit, wherein an opening for an acoustic terminal is formed in a unit case, and a metal mesh for shielding is overlapped on the opening. Condenser microphone.   The condenser microphone according to claim 1, wherein the metal mesh is positioned in the unit case by engaging a rear end portion of the metal mesh with a concave portion or a convex portion on the inner periphery of the unit case.   2. The condenser microphone according to claim 1, wherein the metal mesh for shielding is formed into a cylindrical shape by pressing a metal mesh plate.   2. The condenser microphone according to claim 1, wherein the shielding metal mesh has a front end formed in an inward flange shape, and the inward flange-like front end presses the condenser microphone unit component. The shield metal mesh has a rear end formed in an outward flange shape, and this outward flange-like rear end fits into a circumferential groove formed in the inner peripheral surface of the unit case, so that the metal mesh is unitized. The condenser microphone according to claim 1, wherein the condenser microphone is positioned in a case.

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