JP5627386B2 - Method for manufacturing condenser microphone unit and condenser microphone unit - Google Patents

Description

  The present invention relates to a method for manufacturing a condenser microphone unit, and more particularly to a technique for coaxially positioning a built-in component including an acoustoelectric converter housed in a unit case with respect to the unit case.

  FIG. 5 shows a general form of a condenser microphone unit. As a basic configuration, the condenser microphone unit includes a unit case 10, an electrostatic acoustoelectric converter 20, and a circuit board 30 for outputting an audio signal. Since the acoustoelectric converter 20 and the circuit board 30 are built in the unit case 10, they may be referred to as “built-in components” in this specification.

  In FIG. 5, the sound collection axis is in a vertically downward direction, but the unit case 10 has a sound wave introduction port as the front acoustic terminal 11 in the front end wall 10 a and the rear end portion 10 b side is open. It consists of a cylindrical body. The unit case 10 is usually made of an aluminum material, but may be made of another metal material such as a brass alloy.

  The electrostatic acoustoelectric transducer 20 includes a diaphragm 21 stretched on a support ring (diaphragm ring) 22, an electrically insulating spacer ring 23, and a disk-shaped insulating seat 25 made of an electrically insulating material. A fixed pole 24 supported on one surface side is included.

  The diaphragm 21 and the fixed pole 24 are disposed to face each other via the spacer ring 23, and the inner diameter of the spacer ring 23 is designed to be slightly larger than or equal to the inner diameter of the support ring 22.

  A circular substrate is used as the circuit board 30 and is disposed on the other surface side (the anti-fixed pole 24 side) of the insulating seat 25. An FET (field effect transistor) 31 as an impedance converter is mounted on the inner surface side of the circuit board 30 (the surface side facing the insulating seat 25). Further, a ground pattern 32 as a ground terminal is formed on the outer peripheral portion of the circuit board 30.

  Each of the built-in components described above (the support ring 22 having the diaphragm 21, the spacer ring 23, the insulating seat 25 including the fixed pole 24, and the circuit board 30) are provided in the unit case 10 with the inner diameter surface of the unit case 10 as a guide. Then, the unit case 10 is fixed by curling with the rear end portion 10b of the unit case 10 facing inward. FIG. 6 shows the state after the curling process.

  The built-in components are assembled coaxially with the axis of the unit case 10, that is, in order to obtain high assembly accuracy, the gap between the outer diameter of each built-in component and the inner diameter of the unit case 10 should be smaller. However, such a design makes it difficult to assemble and extremely reduces productivity.

  Therefore, a certain amount of clearance is allowed in consideration of productivity, but in such a case, eccentricity may occur between the built-in components. FIG. 6 shows, as an example, a state where the support ring 22 having the diaphragm 21 and the spacer ring 23 are assembled eccentrically.

  As described above, the inner diameter of the spacer ring 23 is designed to be slightly larger than or equal to the inner diameter of the support ring 22, but when eccentricity occurs, as shown in the enlarged sectional view of the circled portion in FIG. The inner diameter end 23 a of the spacer ring 23 is displaced inward from the inner diameter of the support ring 22 and is disposed on the effective vibration portion of the diaphragm 21.

  In this state, as described above, when the rear end portion 10b of the unit case 10 is curled, a part of the effective vibration portion of the diaphragm 21 is pressed in the arrow Y direction by the inner diameter end 23a of the spacer ring 23. Therefore, the tension of the diaphragm 21 is changed to a higher one, and the characteristics of the condenser microphone unit are deteriorated.

  In order to solve such a problem, even if the width of the support ring 22 is widened and an eccentricity occurs with the spacer ring 23, the inner diameter end 23a of the spacer ring 23 does not reach the effective vibration portion of the diaphragm 21. In this case, the area of the effective vibration portion of the diaphragm 21 is reduced, and the sensitivity and the S / N ratio are reduced, which is not a preferable solution.

  In order to solve this point, the present applicant has proposed the invention described in Patent Document 1. In Patent Document 1, as shown in FIGS. 7 and 8, a leaf spring 40 is provided between the inner diameter surface of the unit case 10 and the outer diameter surfaces of the acoustoelectric transducer 20 and the circuit board 30 that are built-in components. I try to put it in.

  According to this, the eccentricity between the built-in components can be eliminated, but the assembly of the built-in components is eccentric with respect to the axis of the unit case 10. In such a state, when the built-in component is fixed by curling the rear end portion 10b of the unit case 10, the stress applied to the peripheral edge of the built-in component is partially biased.

  In the unidirectional condenser mylophone unit, the tension of the diaphragm 21 is lowered in order to reduce the low-frequency sound collection limit, but it is partially biased with respect to the support ring 22 of the diaphragm 21. When the stress is applied, the tension of the diaphragm 21 may change to a higher one.

  Since the bias of the internal stress is not constant, if the tension of the diaphragm is different for each unit, individual differences occur in the low-frequency sound collection limit, which is not preferable for quality control. Further, the contact pressure of the rear end portion 10b of the unit case 10 with respect to the ground pattern 32 of the circuit board 30 is also partially biased, which may impair the reliability of electrical connection.

JP 2007-31279 A

  Accordingly, an object of the present invention is to provide a built-in component with respect to the unit case without requiring a separate positioning component in a condenser microphone unit in which an electrostatic acoustoelectric converter and a circuit board are built in the unit case. It is to be able to position coaxially.

In order to solve the above problems, the present invention provides a diaphragm, spacer ring, and insulating seat stretched on a support ring as a built-in component in a unit case made of a metal cylindrical body having a sound wave introduction port on a front end wall. An electrostatic acoustoelectric converter including a supported fixed pole and a circuit board having an impedance converter and having a ground pattern formed on the periphery thereof are housed in this order, and the rear opening end of the unit case In the method of manufacturing a condenser microphone unit formed by fixing the built-in component in the unit case by curling the edge and electrically connecting the unit case to the ground pattern.
After the acoustoelectric converter and the circuit board as the built-in parts are housed in the unit case, the axial direction of the unit case is at least three places in the circumferential direction of the cylindrical portion of the unit case. A rib that abuts against the outer diameter surface of the built-in component is formed by applying a pressing force from the outer peripheral surface side over the range where the built-in component exists to plastically deform the cylindrical portion partially inward in the radial direction. The built-in component is positioned coaxially with respect to the unit case, and then curled on the rear opening edge of the unit case.

  According to a preferred aspect of the present invention, the ribs are formed at three locations at intervals of 120 ° in the circumferential direction of the cylindrical portion.

  The rib is formed separately for a portion for the acoustoelectric converter and a portion for the circuit board.

  The rib is formed by a claw of the collet chuck for holding the unit case used when the curling process is performed.

  The present invention also includes a condenser microphone unit manufactured by the above manufacturing method.

According to the present invention, the acoustoelectric converter and the circuit board as the built-in components are housed in the unit case, and are then built in at least three places in the circumferential direction of the cylindrical portion of the unit case in the axial direction of the unit case. By applying a pressing force from the outer peripheral surface side over the range where the part exists, the cylindrical part is plastically deformed partially inward in the radial direction to form a rib that contacts the outer diameter surface of the built-in part. In addition, the built-in components can be arranged coaxially and the built-in components can be positioned coaxially with respect to the unit case without requiring positioning components.

The top view which looked at the state before curling processing of the capacitor | condenser microphone unit which concerns on one Embodiment of this invention from the rear-end opening part side of the microphone case. AA sectional view taken on the line AA of FIG. Sectional drawing similar to FIG. 2 which shows the state after a curling process. Sectional drawing similar to FIG. 2 which shows the capacitor | condenser microphone unit which concerns on another embodiment of this invention. Sectional drawing which shows the general form of a capacitor | condenser microphone unit. Sectional drawing which shows the state after a curling process with the capacitor | condenser microphone unit of FIG. The top view similar to FIG. 1 which shows the condenser microphone unit provided with the positioning component as a prior art example. Sectional drawing which shows the state after a curling process with the capacitor | condenser microphone unit of FIG.

  Next, an embodiment of the present invention will be described with reference to FIGS. 1 to 4, but the present invention is not limited to this. In the description of this embodiment, the same reference numerals are used for the constituent elements that do not need to be changed from the conventional example described in FIG.

  First, referring to FIG. 1 and FIG. 2, the condenser microphone unit according to this embodiment is basically composed of a unit case 10 and an electrostatic acoustoelectric transducer as in the conventional example described above. 20 and a circuit board 30 for outputting an audio signal. The acoustoelectric converter 20 and the circuit board 30 are built-in components housed in the unit case 10.

  In FIG. 2, the sound collection axis is in a vertically downward direction, but the unit case 10 has a sound wave inlet as the front acoustic terminal 11 in the front end wall 10a, and the rear end 10b side is open metal It consists of a cylindrical body. The unit case 10 is preferably made of an aluminum material that is inexpensive and can be plastically deformed, but other metal materials may be used as long as the plastic deformation is possible.

  The electrostatic acoustoelectric transducer 20 includes a diaphragm 21 stretched on a metal support ring (diaphragm ring) 22, an electrically insulating spacer ring 23, and a disk-shaped insulation made of an electrically insulating material. A fixed pole 24 supported on one surface side of the seat 25 is included. The insulating seat 25 is sometimes called a cylinder.

  A synthetic resin film having a metal vapor deposition film on one side is used for the vibration plate 21, and the metal vapor deposition film side is adhered to the support ring 22 with an adhesive or the like. For the fixed electrode 24, for example, an electrode plate made of an aluminum material is used.

  In the case of the electret condenser microphone unit of the back electret type, an electret dielectric film is provided on the fixed electrode 24, and in the case of the film electret type, an electret dielectric film is used for the diaphragm 21.

  The diaphragm 21 and the fixed pole 24 are disposed to face each other via the spacer ring 23, but the inner diameter of the spacer ring 23 may be designed to be slightly larger than or equal to the inner diameter of the support ring 22.

  A circular substrate is used as the circuit board 30 and is disposed on the other surface side (the anti-fixed pole 24 side) of the insulating seat 25. An FET (field effect transistor) 31 as an impedance converter is mounted on the inner surface side of the circuit board 30 (the surface side facing the insulating seat 25).

  Further, a ground pattern 32 as a ground terminal is formed on the outer peripheral portion of the circuit board 30. The ground pattern 32 is electrically and mechanically connected to the unit case 10 by curling on the rear end side of the unit case 10 described later.

  Since the condenser microphone unit according to this embodiment is unidirectional, the circuit board 30 is provided with a rear acoustic terminal 33, and the insulating seat 25 is provided with a sound wave passage 251 communicating with the rear acoustic terminal 33. Has been. An acoustic resistance material 253 such as a felt material is disposed in the sound wave passage 251.

  A back air chamber 252 having a predetermined volume connected to the sound wave passage 251 is formed on the back side of the fixed pole 24, and the back air chamber 252 is interposed through a sound hole 241 formed in the fixed electrode 24. And communicated with a thin air layer existing on the back side of the diaphragm 21.

  Thereby, the sound wave from the front acoustic terminal 11 acts on the front surface of the diaphragm 21, and the sound wave from the rear acoustic terminal 33 acts on the back surface of the diaphragm 21, and the condenser microphone unit operates as a single directivity. To do.

  According to the present invention, a condenser microphone unit is manufactured as follows. The unit case 10 is formed in such a size that a predetermined gap is formed between the unit case 10 and the built-in component in consideration of productivity (assembly).

  First, the acoustoelectric converter 20 and the circuit board 30 as built-in components are housed in the unit case 10. That is, the support ring 22, the spacer ring 23 on which the diaphragm 21 is stretched, the insulating seat 25 having the fixed pole 24, and the circuit board 30 are housed in the unit case 10 in this order.

  Next, a rib 50 for coaxially positioning the built-in component with respect to the axis of the unit case 10 is formed in the cylindrical portion (body portion) 10c of the unit case 10, and the inner diameter of the unit case 10 is substantially reduced. Diameter.

As shown in FIG. 1, the ribs 50 are preferably provided at three locations at 120 ° intervals in the circumferential direction of the cylindrical portion 10c, but may be formed at four locations at 90 ° intervals.

  Each rib 50 is formed along the axial direction of the unit case 10. The length is a range where the built-in components exist, that is, a range from the support ring 22 portion to the circuit board 30 as shown in FIG.

  Each rib 50 is formed by applying a pressing pressure from the outer peripheral surface side to a part of the cylindrical portion 10c so as to abut on the outer diameter surface of the built-in component, thereby plastically deforming the cylindrical portion 10c partially inward in the radial direction. To do. Thereby, the built-in component is positioned coaxially with respect to the axis of the unit case 10.

  Thereafter, the rear end portion 10b of the unit case 10 is subjected to curling processing, and as shown in FIG. 3, the rear end portion 10b of the unit case 10 is caulked to the peripheral edge portion of the circuit board 30 to fix the built-in components. The case 10 and the ground pattern 32 of the circuit board 30 are electrically and mechanically connected.

  Although not shown, since the curling machine is provided with a collet chuck for holding the unit case, the ribs 50 may be formed before the curling using the collet chuck.

  That is, the collet chuck is provided with a plurality of (for example, three) claws for centering and holding the unit case. Protrusions that pressurize the unit case are provided inside the claws, and the unit case is partially plastically deformed to form the ribs 50 described above, followed by curling, thereby efficiently providing a condenser microphone unit. Can be manufactured.

  Further, in order to ensure electrical and mechanical connection between the ground pattern 32 of the circuit board 30 and the rear end portion 10b of the unit case 10 that is caulked by curling, as shown in FIG. The first rib 51 for the acoustoelectric converter 20 and the second rib 52 for the circuit board 30 are preferably formed separately. According to this, the contact pressure between the rear end portion of the unit case 10 and the circuit board 30 can be further increased.

  According to the present invention, the eccentricity between the built-in components can be reduced, and the eccentricity with the unit case can also be reduced. Therefore, in the unidirectional condenser microphone, the change in the tension of the diaphragm can be reduced, and the low frequency range Individual differences in the sound collection limit can be reduced.

  In addition, as shown in FIG. 4, the vicinity of the circuit board of the unit case is strongly plastically deformed and then subjected to curling so that the electrical connection between the rear end of the unit case and the ground pattern of the circuit board is more reliable. Can be.

DESCRIPTION OF SYMBOLS 10 Unit case 10a Front end wall 10b Rear end part 10c Cylindrical part 11 Front acoustic terminal 20 Acoustoelectric converter 21 Diaphragm 22 Support ring 23 Spacer ring 24 Fixed pole 25 Insulation seat 30 Circuit board 31 FET
32 Ground pattern 50 Rib 51 First rib 52 Second rib

Claims (5)

Inside the unit case consisting of a metal cylindrical body having a sound wave inlet on the front end wall, as a built-in component, a diaphragm stretched on a support ring, a spacer ring, and a static pole supported by an insulating seat An acoustoelectric converter and a circuit board having an impedance converter and having a ground pattern formed on the periphery are accommodated in this order, and the built-in component is unitized by curling the rear opening edge of the unit case. In the manufacturing method of the condenser microphone unit, which is fixed in the case and electrically connected to the ground pattern, the unit case,
After the acoustoelectric converter and the circuit board as the built-in parts are housed in the unit case, the axial direction of the unit case is at least three places in the circumferential direction of the cylindrical portion of the unit case. A rib that abuts against the outer diameter surface of the built-in component is formed by applying a pressing force from the outer peripheral surface side over the range where the built-in component exists to plastically deform the cylindrical portion partially inward in the radial direction. A method of manufacturing a condenser microphone unit, wherein the built-in component is positioned coaxially with respect to the unit case, and then a curling process is performed on a rear opening edge of the unit case.   2. The method of manufacturing a condenser microphone unit according to claim 1, wherein the ribs are formed at three positions with a 120 [deg.] Interval in the circumferential direction of the cylindrical portion.   3. The method of manufacturing a condenser microphone unit according to claim 1, wherein the rib is formed by being divided into a portion for the acoustoelectric converter and a portion for the circuit board.   4. The method of manufacturing a condenser microphone unit according to claim 1, wherein the rib is formed by a claw of the collet chuck for holding the unit case used when the curling process is performed. .   A condenser microphone unit manufactured by the manufacturing method according to claim 1.

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