JP5269659B2 - Condenser microphone unit, method of manufacturing capacitor microphone unit, and capacitor microphone - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a condenser microphone unit capable of effectively preventing the electrolytic corrosion of an electric contact part in the inside and the formation of an oxide skin, to provide a method of manufacturing the condenser microphone unit, and to provide a condenser microphone. <P>SOLUTION: In the condenser microphone unit 1, built-in components including a diaphragm 5 which vibrates in response to sound waves and a counter electrode 7 facing the diaphragm 5 at an interval are built inside a unit case 2 made of a conductive metal. The parts of the unit case 2 and the built-in components to be in electric contact with each other, which are also the parts where dissimilar metals are brought into contact with each other, are covered with a hot melt adhesive 16. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a condenser microphone unit, a method of manufacturing a condenser microphone unit, and a condenser microphone that can effectively prevent electrolytic corrosion and oxide film formation at an internal electrical contact portion.

  The condenser microphone includes a condenser microphone unit that constitutes a kind of condenser in which a diaphragm that vibrates by sound waves and a counter electrode (also referred to as a “back electrode”) are arranged to face each other via a spacer.

  This capacitor microphone unit further includes a built-in component in a unit case, an FET (field effect transistor) as an impedance converter, and a circuit board on which the FET is mounted.

  A conventional condenser microphone unit is configured as shown in FIG. 5, the condenser microphone unit 1 includes a cylindrical conductive unit case 2 having an end plate 21 at the front end (lower side in FIG. 5). An opening 23 is provided at the center of the end plate 21, and the opening 23 forms the front acoustic terminal 3. In the unit case 2, built-in components such as a diaphragm holder 4, a diaphragm 5, a spacer 6, a counter electrode 7, an insulating holder 8, an acoustic resistance material 10, and a fixed plate 11 are fitted in order from the front end side. .

  The diaphragm 5 is made of, for example, a resinous thin film and vibrates by receiving sound waves. The diaphragm holder 4 is a conductive ring-shaped member, and the periphery of the diaphragm 5 is fixed to the back surface of the diaphragm holder 4 with an appropriate tension. Between the diaphragm 5 and the counter electrode 7, a spacer 6, which is an insulating member, is interposed, and a space corresponding to the thickness of the spacer 6 is generated. The diaphragm 5 or the counter electrode 7 is formed with electret elements, that is, a thin layer made of a polymer compound that stores charge semipermanently on these opposing surfaces, and the diaphragm 5 and the counter electrode 7 constitute a capacitor.

  When the diaphragm 5 receives a sound wave and vibrates, the capacitance of the capacitor formed by the diaphragm 5 and the counter electrode 7 changes, and an electric signal resulting from the capacitance change is impedance-converted by the FET 120 and provided on the fixed plate 11. It is transmitted to the electric circuit pattern.

  The insulating holder 8 is a cylindrical member having an insulating property fitted inside the unit case 2, and is a member for electrically insulating the unit case 2 from the counter electrode 7 and the FET 120. An FET 120 is disposed in a hole 81 formed through the insulating holder 8. One lead electrode 121 of the FET 120 has a bent portion 122 at the end, and the bent portion 122 is in contact with the counter electrode 7. An end of the other lead electrode 123 of the FET 120 extends to the outside of the unit case 2 through a hole 116 provided in the unit case 2, and the end is formed on the fixing plate 11 by the solder 118. It is electrically connected to the pattern. Further, the insulating holder 8 includes an appropriate number of holes 82 formed through the insulating holder 8 along the axial direction of the cylinder, and a jetty 83 provided at the outer peripheral edge of the front end of the insulating holder 8. . The jetty 83 is inserted into a gap formed between the inner peripheral surface of the unit case 2 and the outer peripheral surface of the counter electrode 7, so that the above-described insulating state is formed.

  The rear end portion of each hole 82 has a large diameter, and the acoustic resistance material 10 is embedded in the large diameter portion. The acoustic resistance material 10 is a member for adjusting the acoustic characteristics of the microphone unit 1 by adjusting the sound propagation speed, and is made of an elastic material such as a nonwoven fabric or a sponge.

  The fixing plate 11 is fitted into the open end of the cylindrical unit case 2, and the end of the unit case 2 is fixed inside the unit case 2 by being caulked inward, and directed toward the inside of the unit case 2. Is pressed. The diaphragm holder 4, the diaphragm 5, the spacer 6, the counter electrode 7, the insulating holder 8, and the acoustic resistance material 10 housed in the unit case 2 are attached to the unit case 2 by the pressing force of the fixing plate 11 described above. It is pressed and positioned toward the end plate 21. An electric circuit pattern is printed on the surface of the fixed plate 11 to form an electric circuit including the impedance conversion circuit including the FET 120 described above. The fixing plate 11 is provided with an opening 112 communicating with the hole 82 of the insulating holder 8 through the acoustic resistance material 10, and the opening 112 constitutes a rear acoustic terminal 114.

  The lead electrode 121 of the FET 120 is in contact with the counter electrode 7 and is electrically connected to the counter electrode 7 and constitutes one terminal of the capacitor constituted by the diaphragm 5 and the counter electrode 7. The diaphragm 5 is electrically connected to the unit case 2 via the diaphragm holder 4, and the unit case 2 constitutes the other terminal of the capacitor.

  An appropriate number of holes 71 are formed in the counter electrode 7, and the space formed by the diaphragm 5 and the counter electrode 7 passes through the holes 71 and further opens the holes 82 of the insulating holder 8 and the fixing plate 11. It communicates with the outside via the section 112.

  When the diaphragm 5 receives a sound wave and vibrates, the capacitance of the capacitor formed by the diaphragm 5 and the counter electrode 7 changes, and an audio signal due to a voltage change passes through an electric circuit including an impedance conversion circuit including the FET 120 and the like. Is output.

  The unit case 2, the diaphragm holder 4, and the pattern provided on the fixed plate 11 are each a conductive member, and are formed of different kinds of metals suitable for each purpose.

  Since the unit case 2 fixes the built-in component in the inside thereof by caulking the open end portion, aluminum that is easily plastically processed is generally used as the material. As a material of the diaphragm holder 4, a copper alloy such as brass is plated with nickel. The circuit pattern material provided on the fixing plate 11 is a general copper foil. The electrical connection between the unit case 2 and the diaphragm holder 4 and between the unit case 2 and the fixed plate 11 is performed by direct contact of these dissimilar metals (for example, Patent Document 1). reference).

JP 2003-018696 A

  By the way, when moisture adheres to the contact portion when different metals are in contact with each other, corrosion (electric corrosion) due to a potential difference between the metals occurs. For example, when the microphone unit 1 is used under high temperature and high humidity, moisture enters the inside of the unit case 2, and the gap between the crimped open end of the unit case 2 and the diaphragm holder 4 (hereinafter referred to as “contact portion 14”). Or the moisture easily adheres between the pattern of the unit case 2 and the fixing plate 11 (hereinafter referred to as “contact portion 15”). In these places, the attached moisture tends to remain, so that electric corrosion is likely to occur, and the electrical connection may be impaired.

  In addition, since aluminum, which is the material of the unit case 2, tends to form an oxide film due to humidity, when using the microphone unit 1 under high temperature and high humidity, the oxide film is formed on the portions located in the contact portions 14, 15. May be formed, and the electrical connection may be impaired.

  The present invention has been made in view of the above-mentioned problems, and is a condenser microphone unit capable of effectively preventing the formation of an electrolytic corrosion and an oxide film on an internal electrical contact portion, a method of manufacturing a condenser microphone unit, It is another object of the present invention to provide a condenser microphone.

  (1) The present invention is a capacitor in which a built-in component including a diaphragm that vibrates by receiving a sound wave and a counter electrode that is opposed to the diaphragm with a gap is incorporated in a unit case made of a conductive metal. The microphone unit is characterized in that the unit case and the built-in component are portions that are in electrical contact with each other and that are in contact with dissimilar metals and are covered with a hot melt adhesive. .

  Although it does not specifically limit in this invention, It is preferable that the said hot-melt-adhesive is soluble in the organic solvent.

  Although not particularly limited in the present invention, it is preferable that the hot melt adhesive is interposed in a gap between the inner peripheral surface of the unit case and the built-in component.

  Further, although not particularly limited in the present invention, the unit case has an end plate on one end side, the other end is an open end, and the open end of the unit case is bent, whereby the built-in component Is preferably pressed toward the end plate.

  Further, although not particularly limited in the present invention, it is preferable that a portion where the bent release end and the built-in component come into contact is covered with a hot melt adhesive.

  Further, although not particularly limited in the present invention, the end plate located on the inner peripheral side of the diaphragm holder comes into contact with the end plate of the unit case and an annular diaphragm holder to which the diaphragm is attached. It is preferable that the hot melt adhesive is applied to the inner surface of the film.

  (2) The present invention is a capacitor in which a built-in component including a diaphragm that vibrates by receiving a sound wave and a counter electrode that is opposed to the diaphragm with a gap is incorporated in a unit case made of a conductive metal. A method for manufacturing a microphone unit, wherein the unit case and the built-in component apply a hot melt adhesive to a portion in electrical contact with each other, and a curing step that cures the applied hot melt adhesive. A fixing step in which the built-in components are assembled into the unit case after the curing step and the built-in components are pressurized and fixed in the unit case, and heated to a temperature at which the hot melt adhesive is dissolved after the fixing step, And a heating / cooling step of cooling after that.

  Although not particularly limited in the present invention, the hot melt adhesive used in the coating step is a hot melt adhesive in a state dissolved in an organic solvent, and the curing step is performed from the dissolved hot melt adhesive. It is preferable to carry out by volatilizing the organic solvent.

  Although not particularly limited in the present invention, it is preferable that the hot melt adhesive is applied to the inner surface of the unit case in the application step.

  Further, although not particularly limited in the present invention, the unit case has an end plate on one end side and the other end is an open end, and in the fixing step, the open end of the unit case is bent. It is preferable to pressurize the built-in component toward the end plate.

  (3) The present invention is mainly characterized in that it is a condenser microphone including the above-described condenser microphone unit.

  ADVANTAGE OF THE INVENTION According to this invention, the capacitor | condenser microphone unit which can prevent the electric corrosion of an internal electrical contact part effectively, the manufacturing method of a capacitor | condenser microphone unit, and a condenser microphone can be provided.

It is sectional drawing which shows the capacitor | condenser microphone unit which concerns on embodiment of this invention. It is sectional drawing which shows the application | coating process and hardening process of the manufacturing method of the capacitor | condenser microphone unit which concerns on embodiment of this invention. It is sectional drawing which shows the fixing process of the manufacturing method of the capacitor | condenser microphone unit which concerns on embodiment of this invention. It is sectional drawing which shows the heating / cooling process of the manufacturing method of the capacitor | condenser microphone unit which concerns on embodiment of this invention. It is sectional drawing which shows the conventional condenser microphone unit.

  Embodiments of a condenser microphone unit, a method of manufacturing a condenser microphone unit, and a condenser microphone according to the present invention will be described below with reference to the drawings. In addition, the same code | symbol was attached | subjected about the same component as the conventional condenser microphone unit mentioned above.

<Condenser microphone unit>
As shown in FIG. 1, the condenser microphone unit according to the present embodiment includes a contact portion 14 between the unit case 2 and the diaphragm holder 4, a contact portion 15 between the pattern of the unit case 2 and the fixed plate 11, And the peripheral portion thereof is covered with the hot melt adhesive 16 and the cushion member 12 is interposed between the insulating holder 8 and the fixing plate 11, and the conventional capacitor shown in FIG. The structure is similar to that of the microphone unit. Therefore, hereinafter, an embodiment of the present invention will be described focusing on the contact portions 14 and 15 and their peripheral portions and the cushion member 12.

  The entire surface of the fixed plate 11 and the diaphragm holder 4 cannot be made completely flat at the time of manufacture, and fine irregularities are generated. Among such fine irregularities, a plurality of protruding portions penetrate the hot melt adhesive 15 and are in contact with each other. Therefore, electrical contact between the fixed plate 11 and the unit case 2 and between the diaphragm holder 4 and the unit case 2 is established. Moreover, the peripheral part of the protrusion part which established the said contact is covered with the melted hot melt adhesive 16, so that the contact parts 14 and 15 and the periphery thereof establish electrical contact between these members. It is sealed.

  As described above, the contact portions 14 and 15 are portions where moisture easily remains when moisture enters the unit case 2 and moisture adheres thereto. However, in the microphone unit 1 according to the present embodiment, the contact portions 14 and 15 and their peripheral portions are covered with the hardened hot melt adhesive 16 and sealed, so that moisture does not enter.

  Thus, by effectively preventing moisture from entering, it is possible to effectively prevent occurrence of the problem that the electrical connection is lost due to the occurrence of electrolytic corrosion or oxide film, which has conventionally occurred in the contact portions 14 and 15. Can be prevented.

  The hot-melt adhesive 16 used in the condenser microphone unit 1 according to the present embodiment is a polyester-based hot-melt adhesive that is insulative and soluble in an organic solvent, and is a paste in a state dissolved in the organic solvent. It can be cured by evaporating the organic solvent. In addition, even after the organic solvent evaporates and hardens, the hot melt adhesive 16 has a property of being melted by being heated to a melting point or higher and being cured again by being cooled to a temperature lower than the melting point. Furthermore, the hot melt adhesive 16 has a property that it is soluble in an organic solvent even after curing. In this embodiment, a hot melt adhesive having a melting point of about 150 ° C. is used.

  In the condenser microphone unit 1 according to this embodiment, a cushion member 12 made of an elastic body made of a resin such as rubber is interposed between the insulating holder 8 and the fixed plate 11. The fixing plate 11 is fitted inside the unit case 2 so as to compress and compress the cushion member 12 and the acoustic resistance material 10. Therefore, the built-in component of the unit case 2 is urged and positioned so as to be pressed toward the inner peripheral surface of the unit case 2 by the repulsive force of the cushion member 12 and the acoustic resistance material 10.

<Manufacturing method of condenser microphone unit>
A method for manufacturing a condenser microphone unit according to the present embodiment will be described with reference to FIGS.

  First, as shown in FIG. 2, the hot melt adhesive 16 is applied to the inner peripheral surface side of the unit case 2 (hereinafter, this process is referred to as “application process”). This hot-melt adhesive 16 is the same as the hot-melt adhesive used in the above-described condenser microphone unit embodiment, and a paste-like one dissolved in an organic solvent is used. A brush, a spray, etc. are used for application | coating of the hot-melt-adhesive 16 in an application | coating process.

  Next, the hot-melt adhesive 16 is cured by evaporating the organic solvent from the paste-like hot-melt adhesive 16 applied in the application process (hereinafter, this process is referred to as a “curing process”). The evaporation of the organic solvent is performed by leaving it at room temperature for a predetermined time, heating it at a temperature lower than the melting point of the hot melt adhesive for a predetermined time, or leaving it in a low pressure or vacuum state for a predetermined time.

  Next, as shown in FIG. 3, in the unit case 2, in order from the front end side, the diaphragm holder 4, the diaphragm 5, the spacer 6, the counter electrode 7, and the insulating holder in which the FET 120 is disposed in the internal hole 81. 8, the acoustic resistance material 10, the cushion member 12, and the fixing plate 11 are fitted, and the open ends of the unit case 2 are caulked so that these components are fitted into the unit case 2 (hereinafter, this process is referred to as “step”). This is referred to as “fixing step”). The outer peripheral edge of the fixing plate 11 is pushed toward the inside of the unit case 2 by the release end portion of the unit case 2 that is crimped, and the acoustic resistance material 10 and the cushion member 12 that are in contact with the fixing plate 11 are compressed. Then, due to the repulsive force of the acoustic resistance material 10 and the cushion member 12 that have been compressed, the fixed plate 11 is moved toward the open end of the crimped unit case 2, and other built-in components are directed toward the end plate 21 of the unit case 2. It is positioned inside the unit case 2 while being always energized.

  Next, as shown in FIG. 4, the hot melt adhesive 16 is melted by heating the condenser microphone unit 1 after the fixing step, and the hot melt adhesive 16 is cooled by cooling the condenser microphone unit 1 after melting. Is re-cured (hereinafter, this process is referred to as “heating and cooling process”).

  The overheating is performed for a predetermined time at a temperature that is equal to or higher than the melting point of the hot melt adhesive 16 and that does not damage components such as the FET 120 in the condenser microphone unit 1. By melting the hot melt adhesive 16 in this way, the release end of the unit case 2 and the fixed plate 11, and the unit case 2 and the diaphragm holder 4 are brought into contact by the repulsive force of the acoustic resistance material 10 and the cushion member 12. . The repulsive force of the acoustic resistance material 10 and the cushion member 12 remains without being completely released, and the fixed plate 11 and the diaphragm holder 4 continue to receive the pressing force by the acoustic resistance material 10 and the cushion member 12.

  The fixed plate 11, the diaphragm holder 4, and the open ends of the unit case 2 cannot have a smooth flat surface at the time of manufacturing, and fine irregularities are generated. Among such fine irregularities, a plurality of protruding portions penetrate the molten hot melt adhesive 16 in the contact portions 14 and 15 and come into contact with each other, so that the fixed plate 11, the unit case 2, and the vibration plate Electrical contact between the holder 4 and the unit case 2 is established. Further, the peripheral portion of the protruding portion where the contact is established is covered with the melted hot melt adhesive 16.

  Next, by cooling the condenser microphone unit 1 in which the electrical contact between the fixed plate 11 and the unit case 2 and the diaphragm holder 4 and the unit case 2 is established, the dissolved hot melt adhesive 16 is again removed. Harden. By curing the hot-melt adhesive 16, the contact portion 14 between the fixed plate 11 and the unit case 2 and the contact portion 15 between the diaphragm holder 4 and the unit case 2 are completely sealed.

  As described above, the contact portions 14 and 15 and the peripheral portion thereof are covered and sealed with the hot melt adhesive 16, so that the electric corrosion and the generation of the oxide film that have been generated in the contact portions 14 and 15 are electrically generated. Occurrence of the problem that the connection is lost can be effectively prevented.

<Condenser microphone>
The condenser microphone according to the present embodiment is configured by housing the condenser microphone unit described in the above-described embodiments in a microphone case. A connector for connecting a microphone cable may be provided in the microphone case as necessary.

  According to the condenser microphone according to the present embodiment, the fixed portion of the built-in condenser microphone and the contact portion of the unit case, the contact portion of the diaphragm holder and the unit case, and the peripheral portion thereof are covered with a hot melt adhesive and sealed. Therefore, it is possible to effectively prevent the occurrence of the problem that the electrical connection is lost due to the occurrence of electrolytic corrosion or oxide film. Further, since the electrical connection is not impaired, it is possible to effectively prevent the performance failure of the condenser microphone and the generation of noise.

  In each of the above-described embodiments, a paste-like polyester-based hot melt adhesive dissolved in an organic solvent is used as the hot melt adhesive 16, but the present invention is not limited to such an aspect. . For example, a solid hot melt adhesive may be used after being dissolved by a glue gun or the like. Moreover, you may use the hot-melt-adhesive containing an electroconductive carrier.

  In each of the embodiments described above, the contact portion between the fixed plate and the unit case and the contact portion between the diaphragm holder and the unit case are covered with the hot melt adhesive. Not limited to. For example, only the contact portion between the fixed plate and the unit case or only the contact portion between the vibration plate holder and the unit case may be covered with a hot melt adhesive. Or you may make it also cover the contact part of other metal parts.

DESCRIPTION OF SYMBOLS 1 Capacitor microphone unit 2 Unit case 4 Diaphragm holder 5 Diaphragm 6 Spacer 7 Counter electrode 8 Insulating holder 121, 123 Extraction electrode 10 Acoustic resistance material 11 Fixing plate 12 Cushion member 14, 15 Contact part 16 Hot melt adhesive 120 FET

Claims (11)

In a unit case made of a conductive metal, a condenser microphone unit in which a built-in component including a diaphragm that vibrates by receiving a sound wave and a counter electrode that is opposed to the diaphragm at an interval is built-in,
A condenser microphone unit in which a portion of the unit case and the built-in component that are in electrical contact with each other and in contact with dissimilar metals are covered with a hot melt adhesive.   The condenser microphone unit according to claim 1, wherein the hot melt adhesive is soluble in an organic solvent.   The condenser microphone unit according to claim 1 or 2, wherein the hot melt adhesive is interposed in a gap between an inner peripheral surface of the unit case and the built-in component.   The unit case has an end plate on one end side, and the other end is an open end, and the built-in component is pressed toward the end plate by bending the open end of the unit case. The condenser microphone unit according to claim 1.   The condenser microphone unit according to claim 4, wherein a portion where the bent open end and the built-in component come into contact is covered with a hot-melt adhesive.   The end plate of the unit case is in contact with an annular diaphragm holder to which the diaphragm is attached, and the hot melt adhesive is applied to the inner surface of the end plate on the inner peripheral side of the diaphragm holder. The condenser microphone unit according to claim 1. This is a method of manufacturing a condenser microphone unit in which a built-in component including a diaphragm that vibrates in response to a sound wave and a counter electrode that is opposed to the diaphragm at an interval is contained in a unit case made of a conductive metal. And
An application step of applying a hot melt adhesive to a portion where the unit case and the built-in component are in electrical contact with each other;
A curing step of curing the applied hot melt adhesive;
A fixing step of incorporating the built-in component into the unit case after the curing step and pressurizing the built-in components together to fix the unit case in the unit case;
A heating and cooling step of heating to a temperature at which the hot melt adhesive is dissolved after the fixing step, and then cooling;
A method of manufacturing a condenser microphone unit comprising:   The hot melt adhesive used in the coating step is a hot melt adhesive dissolved in an organic solvent, and the curing step is performed by volatilizing the organic solvent from the dissolved hot melt adhesive. A method for manufacturing a condenser microphone unit according to claim 7.   The method for manufacturing a condenser microphone unit according to claim 7 or 8, wherein, in the applying step, the hot melt adhesive is applied to an inner surface of the unit case.   The unit case has an end plate on one end side and the other end is an open end. In the fixing step, the built-in component is added to the end plate by bending the open end of the unit case. 10. A method for manufacturing a condenser microphone unit according to claim 7, wherein the condenser microphone unit is pressed.   A condenser microphone comprising the condenser microphone unit according to claim 1.

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