JP2007174475A - Diaphragm for capacitor microphone and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent an edge part of a diaphragm material from being easily released from a support ring in a diaphragm for capacitor microphone which is configured by sticking the diaphragm material comprised of a thin film using an adhesive material while giving a predetermined tension to the support ring. <P>SOLUTION: In a diaphragm for capacitor microphone configured by sticking a diaphragm material 10 comprised of a thin film through an adhesive material 30 to one side surface of a support ring 20, an edge part 10e of the diaphragm material 10 is disposed inside rather than an outer diameter end 20b of the support ring 20 all over the full circumference. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a diaphragm for a condenser microphone and a method for manufacturing the same, and more particularly to a diaphragm for a condenser microphone in which an end portion of the diaphragm is difficult to peel from a support ring and a method for manufacturing the same.

  The condenser microphone includes an electroacoustic transducer in which a diaphragm that vibrates by sound waves and a fixed pole are disposed to face each other via a spacer, and converts sound waves into capacitance and outputs the sound signals. Therefore, the diaphragm is an important component that governs the characteristics of the condenser microphone.

  As shown in FIG. 4, the diaphragm 1 of the condenser microphone has a diaphragm material 10 made of a thin film, with an appropriate tension applied to one side of a circular support ring 20 made of metal, with an adhesive 30 interposed therebetween. The diaphragm material 10 is arranged opposite to the fixed pole via a spacer.

  In the actual manufacturing process, as shown in FIG. 5, a large number of diaphragms 1 are taken from a mother thin film 11 larger than the support ring 20. As the mother thin film 11, a plastic film having a thickness of about 1.2 to 16 μm and having a metal vapor deposition film 12 serving as one electrode of a capacitor on one side is usually used.

  In a state where a predetermined tension is applied to the mother thin film 11, a support ring 20 is attached to the metal vapor deposition film 12 side via an adhesive 30, and the adhesive 30 is cured, and then the mother thin film 11 Is cut along the outer diameter of the support ring 20 indicated by the arrow in FIG. 5 to take out (cut out) the diaphragm 1 from the mother thin film 11.

  By the way, the support ring 20 is formed in a circular ring shape by a press or the like, and when flatness is required, surface polishing is performed. Then, plating is performed for rust prevention. In this plating process, a plating process called glass plating is performed exclusively from the viewpoint of productivity.

  That is, in glass plating, a large number of support rings 20 are placed in a plating basket, and the plating basket is rotated or swung in the plating solution in order to prevent uneven plating. At that time, the corners 20a of the support ring 20 are rounded as shown in FIG. This roundness is applied to most support rings.

  The rounded support ring 20 is attached to the mother thin film 11 through the adhesive 30. However, in the case of an inexpensive condenser microphone for mobile phone use, the diaphragm material 10 is relatively free. A thick film having a thickness of, for example, about 4 to 16 μm is used, and the support ring 20 is adhered in a state where a high tension is applied to the film (the resonance frequency of the diaphragm is about 10 kHz to 20 kHz).

  In this case, since the tension of the diaphragm material 10 is high, the thickness of the adhesive 30 is also increased. However, in the case of an inexpensive condenser microphone for the above-described use, there is no risk of deterioration of characteristics. Further, the displacement of the diaphragm material 10 due to the shrinkage of the adhesive 30 is not a problem because the tension of the diaphragm material 10 is high.

  Further, when the diaphragm 1 is taken out by cutting the mother thin film 11, the microphone is thick even if the diaphragm material 10 is thick, the layer thickness of the adhesive 30 is thick, and mechanical stress is applied to the support ring 20. Since the change in characteristics is small, cutting by a press can be applied.

  At this time, as described above, even if the corner portion 20a of the support ring 20 is rounded in the plating process, the periphery of the diaphragm material 10 is peeled off from the support ring 20 because the layer thickness of the adhesive 30 is thick. There is almost no end.

  However, for example, in a unidirectional condenser microphone, a very thin film of about 1.2 to 4 μm is used for the diaphragm material 10 and is attached to the support ring 20 with a low tension. Further, the layer thickness of the adhesive 30 is also reduced.

  Thus, when the diaphragm 1 is used for a unidirectional condenser microphone, for example, the diaphragm material 10 is very thin, the layer thickness of the adhesive 30 is thin, and the tension of the diaphragm material 10 is low. In addition, since the corner portion 20a of the support ring 20 is rounded as described above, when the diaphragm 1 is taken out from the mother thin film 11, the mother thin film 11 is cut by a press and then illustrated after cutting. When returning the press die to the initial position, as shown in FIG. 7, the peripheral edge 10 a of the diaphragm material 10 may be peeled off from the support ring 20 by the press die.

  FIG. 7A is a plan view showing the diaphragm 1 from which the peripheral edge 10a of the diaphragm material 10 has been peeled off, and FIG. 7B is an enlarged cross-sectional view showing the peeled portion. As shown in FIG. 7A, a part of the peripheral edge 10a of the diaphragm material 10 is peeled off in a crescent shape.

  Even in the case of cutting using a cutter instead of a press, the same peeling may occur with the cutter. Further, even if the diaphragm material 10 can be cut so as not to be peeled off, for example, due to contact with other parts in the transport process, contact with the case inner surface when incorporated into the microphone unit case, etc. The peripheral edge 10a of the diaphragm material 10 may be peeled off.

  When the peeled portion reaches the inside of the support ring 20, the tension of the diaphragm material 10 can no longer be maintained. Therefore, when the electroacoustic transducer is assembled, a problem occurs in the frequency response. In addition, when it is incorporated in the microphone unit case so that the peeled portion is folded back, the distance between the diaphragm and the fixed pole changes depending on the film thickness, and the designed frequency response cannot be obtained.

  In addition, the creeping distance between the metal vapor deposition film and the fixed electrode in the folded portion is reduced, so that a leakage current is likely to occur. Since this leakage current causes noise in the microphone, it is not preferable. In particular, when the humidity is high, the surface resistance of the insulating seat supporting the fixed electrode is lowered, which is a serious problem.

  Accordingly, an object of the present invention is to provide a diaphragm for a condenser microphone in which a diaphragm material made of a thin film is pasted with an adhesive in a state where a predetermined tension is applied to a support ring. The purpose is to prevent it from being easily removed from the ring.

  In order to solve the above problems, the invention according to claim 1 is directed to a condenser microphone diaphragm in which a diaphragm material made of a thin film is adhered to one side of a support ring via an adhesive. The peripheral edge of the plate material is arranged inside the outer diameter end of the support ring over the entire circumference.

  According to a second aspect of the present invention, there is provided a method for manufacturing a diaphragm for a condenser microphone in which a diaphragm material made of a thin film is adhered to one side of a support ring via an adhesive, and a predetermined tension is applied. Affixing the support ring to the thin film film through the adhesive, a portion of the adhesive is applied from above the inner diameter side to the outer diameter end of the support ring by a predetermined cutting means. It is characterized by oblique removal.

  The cutting means used in the second aspect of the present invention is a vibration-type cutting that makes the rotary cutting blade slightly vibrate in a direction orthogonal to the rotation axis as described in the third aspect in order to facilitate the cutting operation. It is preferable to use a tool.

  According to the first aspect of the present invention, the peripheral portion of the diaphragm material is arranged on the inner side of the outer diameter end of the support ring over the entire circumference, so that the diaphragm microphone unit can be used during conveyance of the diaphragm. At the time of incorporation into the case, the peripheral edge portion of the diaphragm material does not come into contact with other peripheral members, and therefore the peeling phenomenon of the peripheral edge portion of the diaphragm material hardly occurs.

  According to the invention described in claim 2, after attaching the support ring to the thin film to which a predetermined tension is applied via the adhesive, the thin film is attached to the inner diameter side of the support ring by a predetermined cutting means. The diaphragm according to claim 1 can be obtained by a simple operation in which a part of the adhesive material is cut obliquely from above to the outer diameter end.

  In the invention according to claim 2, the support ring is attached to the mother thin film to which a predetermined tension is applied via an adhesive, and the mother thin film is separated from the mother thin film by another cutting means (for example, press). It may be applied to the extracted diaphragm.

  Next, an embodiment of the present invention will be described with reference to FIGS. 1 to 3, but the present invention is not limited to this. 1 and 2 are enlarged cross-sectional views of main parts for explaining the manufacturing process of the diaphragm according to the present invention, and FIG. 3 is a plan view showing the diaphragm obtained by the present invention. The same reference numerals are used for the constituent elements described in the previous example and the constituent elements that do not need to be changed.

  First, as shown in FIG. 1, the support ring 20 is stuck through an adhesive 30 in a state where a predetermined tension is applied to the mother thin film 11. For the mother thin film 11, for example, a synthetic resin film such as PET (polyethylene terephthalate) is used. The film thickness is selected to be about 1.2 to 4 μm for unidirectional condenser microphone applications, for example, about 4 to 16 μm for inexpensive cellular phone applications.

  As the support ring 20, a metal ring punched into a circle by a press is used. The support ring 20 is subjected to planar polishing as necessary, and is plated for rust prevention. As described above, since the plating process called glass plating is applied to the plating, the corner portion 20a of the support ring 20 is rounded. The adhesive 30 may be, for example, an epoxy adhesive.

  When the diaphragm is taken out of the mother thin film 11 after the adhesive 30 is cured, in the present invention, as shown by a one-dot chain line C in FIG. 1, the mother thin film 11 is supported by a predetermined cutting means. From the upper side of the inner diameter side of 20 to the corner portion 20a of the outer diameter end, a part of the adhesive 30 is cut off obliquely.

  FIG. 2 shows the state after excision, and FIG. 3 shows the diaphragm 1A of the present invention taken out from the mother thin film 11. In this diaphragm 1A, the mother thin film 11 is obliquely disposed as described above. The peripheral edge portion 10e of the diaphragm material 10 is located on the inner side of the outer diameter end surface 20b of the support ring 20 over the entire circumference.

  Thereby, peeling and turning-up of the peripheral edge portion 10e of the diaphragm material 10 due to contact between the diaphragms or other parts at the time of conveyance or assembly can be significantly reduced. This means that it is possible to prevent the occurrence of performance deterioration such as frequency response, sensitivity, S / N, etc. of the condenser microphone due to the diaphragm assembly, and defective products are reduced, leading to a reduction in cost as a whole.

  1 is arbitrarily determined within the range of 0 ° <θ <90 °, where 0 ° is the parallel angle and 0 ° <θ <90 ° with respect to the outer diameter end face 20b of the support ring 20. However, if the size is too small, the peripheral edge portion 10e of the diaphragm material 10 approaches the outer diameter end surface 20b of the support ring 20, so that peeling easily occurs due to contact with other components, and on the other hand, it is too large. Then, the amount of scraping of the adhesive 30 increases, and the adhesive force may decrease. Therefore, the preferred angle of the crossing angle θ is about 3 to 10 °, more preferably about 7 °.

  The cutting means to be used may be a blade such as a knife. However, in order to scrape cleanly and carefully including a part of the adhesive 30, the rotary cutting blade is set in a direction perpendicular to the rotation axis. It is preferable to use a vibration type cutting tool that vibrates slightly. As this type of vibration-type cutting tool, for example, there is a PROXXON router (trade name) manufactured by Kiso Power Tool.

  As described above, the present invention has been described based on the illustrated example. However, as described in the above-described conventional example, the manufacturing method of the present invention supports a mother thin film to which a predetermined tension is applied via a support material via an adhesive. May be applied to the diaphragm taken out from the mother thin film by pressing.

The principal part expanded sectional view for demonstrating the manufacturing process of the diaphragm by this invention. The principal part expanded sectional view for demonstrating the manufacturing process of the diaphragm by this invention. The top view which shows the diaphragm obtained by this invention. Sectional drawing which shows the conventional common diaphragm. The exploded sectional view for explaining the conventional manufacturing method of a general diaphragm. The partial expanded sectional view of the support ring used for a diaphragm. (A) The top view which shows the diaphragm which peeling generate | occur | produced, (b) The partially expanded sectional view which shows the peeling part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1A Diaphragm 10 Diaphragm material 10e Peripheral part 11 Thin film of mother 20 Support ring 20b Outer end face 30 Adhesive

Claims (3)

In a diaphragm for a condenser microphone in which a diaphragm material made of a thin film is attached to one side of a support ring via an adhesive,
A diaphragm for a condenser microphone, characterized in that a peripheral portion of the diaphragm material is disposed inside the outer diameter end of the support ring over the entire circumference. In the method for manufacturing a diaphragm for a condenser microphone, in which a diaphragm material made of a thin film is adhered to one side of a support ring via an adhesive,
After sticking the support ring to the thin film to which a predetermined tension has been applied via the adhesive, the thin film is applied to the outer diameter end from above the inner diameter side of the support ring by a predetermined cutting means. A method of manufacturing a diaphragm for a condenser microphone, characterized in that a part of the adhesive material is cut off obliquely. 3. The method for manufacturing a diaphragm for a condenser microphone according to claim 2, wherein a vibration type cutting tool that finely vibrates the rotary cutting blade in a direction perpendicular to the rotation axis is used as the cutting means.

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