JP4642541B2 - Microphone - Google Patents

Description

  The present invention relates to a microphone having a structure in which generation of noise caused by leakage current is suppressed and a sensitivity and frequency response are not varied.

Normally, a condenser microphone unit includes a condenser unit including a diaphragm and a back electrode plate that are opposed to each other via a spacer as disclosed in Patent Document 1, for example. The capacitor portion is disposed in the vicinity of the front acoustic terminal hole in a cylindrical metal case. In addition, an impedance converter for converting a capacitance change of the capacitance of the capacitor unit into an electrical impedance is housed on the opening side located behind the metal case. The impedance converter is incorporated in a metal case under a state of being integrally mounted on a printed circuit board. Specifically, the impedance converter is curled with the open edge side of the metal case facing inward. The opening side is sealed by a printed circuit board by caulking.
Registration No. 3017118 Utility Model Gazette

  FIG. 3 is a longitudinal sectional view showing a structural example of a conventional electret type condenser microphone unit, and FIG. 4 is a plan view of a printed circuit board which is a constituent member thereof.

  According to these drawings, the condenser microphone unit 1 is interposed between the diaphragm 3 formed by stretching the diaphragm 3b on the diaphragm ring 3a and the diaphragm ring 3a, but is disposed so as to face each other with the spacer 5 interposed therebetween. The capacitor part 2 comprised with the back electrode plate 4 as a fixed pole is provided, and this capacitor | condenser part 2 is arrange | positioned in the position near the front acoustic terminal hole 9a in the metal case 9 formed in the cylinder shape. Yes.

  Further, an impedance converter (FET) 6 c that converts the capacitance change of the capacitor unit 2 into an electrical impedance is accommodated and disposed on the opening 9 b side that is located behind the metal case 9. The impedance converter 6c is mounted on the printed circuit board 6 and incorporated in the metal case 9, and specifically, curls with the open edge 9c side of the metal case 9 facing inward. By crimping in this way, the printed board 6 is housed in a state where the opening 9b side is sealed.

  Thus, when the printed circuit board 6 seals the opening 9 b side of the metal case 9, the outer peripheral surface of the back electrode plate 4 is in contact with the inner surface of the cylindrical insulating sleeve 7. Moreover, the back electrode plate 4 is supported in the circumferential direction by a cylindrical conductive sleeve 8 that is located between the lower surface side of the printed circuit board 5 and is disposed along the inner surface of the insulating sleeve 7. Will be.

  In this case, as shown in FIG. 4, the printed circuit board 6 is formed with an annular pattern layer 6a at a contact position with the conductive sleeve 7, and the annular pattern layer 6a is connected to the impedance converter 6c via the connection pattern layer 6b. Conductive with each other.

  Therefore, the condenser microphone unit 1 shown in FIG. 3 includes a back electrode plate 4 → conductive sleeve 8 → annular pattern layer 6a → connection pattern layer 6b → impedance converter between the back electrode plate 4 and the impedance converter 6c. A conductive path of 6c is secured.

  By the way, according to the condenser microphone unit 1 shown in FIG. 3, the conductive path secured between the printed circuit board 6 and the conductive sleeve 8 is on the metal case 9 side, although the insulating sleeve 7 is interposed. It is in a close distance relationship.

  For this reason, when it is taken out to a place with a temperature difference to cause condensation including rainwater on the metal case 9 side, the insulation resistance on the surface of the printed circuit board 6 is reduced due to the condensation and leakage current is generated. There is a disadvantage that noise caused by the leakage current is likely to occur.

  In addition, this type of condenser microphone unit 1 has a thickness of the insulating sleeve 7 from the viewpoint of increasing the sensitivity by ensuring the effective area of the back electrode plate 4 as much as possible and increasing the S / N ratio. Tend to try to make it as thin as possible. When the thickness of the insulating sleeve 7 is reduced due to such a request, there is a problem that noise due to the leakage current is easily generated.

  On the other hand, the metal case 9 before caulking has a variation in the hem length of the open edge portion 9c including the open end edge, and the distance from the conductive sleeve 8 is also short. Unevenness is likely to occur. Such crimping unevenness also causes unevenness in the stress applied to the peripheral portion of the back electrode plate 4 via the conductive sleeve 8, and this unevenness in stress also causes variations in sensitivity and frequency response.

  An object of the present invention is to provide a condenser microphone unit that suppresses the generation of noise due to leakage current and does not cause variations in sensitivity and frequency response.

The present invention has been made to achieve the above object, and electrically connects a back electrode plate that forms a capacitor part with a diaphragm and an impedance converter mounted on a printed circuit board via a conductor. In a condenser microphone unit that is electrically connected to and housed in a metal case, the surface region located substantially at the central portion of the printed circuit board is electrically connected to an impedance converter mounted in the vicinity thereof via an intervening pattern layer. The pattern layer is provided with a creepage distance that can correspond to a decrease in insulation resistance on the surface of the printed circuit board between the metal case and the conductor is provided over the entire periphery of the peripheral portion of the back electrode plate. and the enlarged diameter portion in contact with a pressure of approximately isobaric less and a reduced diameter portion in contact with the pattern layer substantially through the flat contact surface of the same surface size as the pattern layer The most important feature that is formed by a conductive member which also has. In this case, the conductor is preferably formed of a conductive member made of a hollow metal material having a substantially frustoconical shape.

  According to the present invention, the conductive contact between the conductor side and the printed board side is performed between the pattern layer formed in the surface region of the central portion of the printed board and the reduced diameter portion of the conductor. Even if the insulation resistance on the surface of the substrate is lowered, a sufficient creepage distance can be secured, so that it is possible to effectively prevent the occurrence of noise due to leakage current.

  Moreover, when the open end edge of the metal case is crimped and sealed with the printed circuit board, the reduced diameter portion of the conductor is formed on the pattern layer located in the central portion by the elasticity accompanied by the bending generated on the printed circuit board side. Stable stress can be applied to the back electrode plate side through the enlarged diameter portion side with the side in close contact, so that the pressure applied to the back electrode plate is evenly applied to the spacer or diaphragm side Thus, the sensitivity and frequency response can be stabilized.

  FIG. 1 is a longitudinal sectional view showing an example of the present invention, and FIG. 2 is a plan view of a printed circuit board which is a constituent member thereof.

  According to these figures, the condenser microphone unit 11 is disposed between the diaphragm 13 formed by stretching the diaphragm 13b on the diaphragm ring 13a and the diaphragm ring 13a, but is disposed so as to be opposed to each other through the spacer 15. The capacitor portion 12 is formed of a back electrode plate 14 as a fixed pole, and the capacitor portion 12 is disposed in the vicinity of the front acoustic terminal hole 33 in a cylindrical metal case 32. Yes.

An impedance converter (FET) 23 that converts a capacitance change of the capacitance of the capacitor unit 12 into an electrical impedance is housed and disposed on the side of the opening 34 located behind the metal case 32.

The impedance converter 23 is mounted on the printed circuit board 22 and incorporated in the metal case 32. Specifically, the impedance converter 23 is curled with the open edge 35 side of the metal case 32 facing inward. By crimping as described above, the printed board 22 is housed in a state where the opening 34 side is sealed.

  Thus, when the printed circuit board 22 seals the opening 34 side of the metal case 32, the outer peripheral surface 14 a of the back electrode plate 14 including the electret layer is in contact with the inner surface 16 a of the cylindrical insulating sleeve 16. Will be maintained. In addition, the back electrode plate 14 is supported by a conductor 26 disposed between the lower surface 16 b side and the printed circuit board 22.

That is, the surface area located substantially at the center portion of the printed circuit board 22, the pattern layer 24 to conduct through the Ah Louis impedance converter 23 and the intervening patterned layer 25 by mounting its vicinity shapes approximately small round Is formed.

  The conductor 26 is a conductive material such as a copper alloy having at least a diameter-expanded portion 27 that contacts the peripheral edge portion 15 located on the lower surface 14a side of the back electrode plate 14 and a reduced-diameter portion 29 that contacts the pattern layer 24 side. It is formed of a sex member.

  More specifically, the conductor 26 is formed of a hollow conductive metal material having a substantially frustoconical shape, and the enlarged diameter portion 27 side has a required length from the enlarged edge 26a side. It is formed through a skirt portion 28 suspended from the bottom.

  Further, the reduced diameter portion 29 located on the wharf side is formed with a flat contact surface 30 having substantially the same surface size as the pattern layer 24 on the surface thereof, and the printed circuit board 22 via the contact surface 30 is formed. The pattern layer 24 can be contacted. In order to reduce the weight, it is desirable to form the conductor 26 with the smallest possible thickness as long as necessary rigidity is obtained.

  Next, the operation and effect of the present invention having the above configuration will be described with reference to FIGS. 1 and 2. The open edge 35 of the metal case 32 is crimped and the opening 34 is sealed by the printed circuit board 22. In this case, the diameter-expanded portion 27 is in a state in which the diameter-reduced portion 29 side of the conductor 26 is in close contact with the pattern layer 24 located at the central portion due to the elasticity generated on the printed circuit board 22 side. Stable stress can be applied to the back electrode plate 14 side through the side.

  That is, the capacitor unit 12 disposed in the sealed metal case 32 and the impedance converter 23 mounted on the printed circuit board 22 are electrically connected in a stable state by a conductor 26 interposed therebetween. Can be connected to.

  In this case, the conductor 26 having a substantially frustoconical shape has a diameter-enlarged portion 27 secured on the skirt portion 28 side on the peripheral portion 15 of the back electrode plate 14 constituting the capacitor portion 12, The positioned reduced diameter portion 29 is brought into contact with the pattern layer 24 of the printed circuit board 22 through the contact surface 30, and the back electrode plate 14 → the enlarged diameter portion 27 of the conductor 26 → the reduced diameter portion 29 of the conductor 26 → A conductive path of the pattern layer 24 → impedance converter 23 of the printed circuit board 22 can be secured.

  That is, the conductive contact between the conductor 26 side and the printed circuit board 22 side is performed between the pattern layer 24 formed in the surface region of the central portion of the printed circuit board 22 and the reduced diameter portion 29 of the conductor 26. become.

  For this reason, even if the metal case 32 is dewed by taking it out to a place where there is a temperature difference, and the insulation resistance on the surface of the printed circuit board 22 may be reduced, the diameter of the conductor 26 is reduced. Since the pattern layer 24 in contact with the contact surface 30 of the portion 29 can ensure a sufficient creepage distance between the pattern layer 24 and the metal case 32 side, it is possible to effectively prevent the generation of noise due to leakage current. it can.

  Even if the insulation sleeve 19 is made thin in order to increase the sensitivity by securing the effective area of the back electrode plate 14 as much as possible and to increase the S / N ratio, the noise caused by the leakage current Can be difficult to generate.

  Furthermore, since the enlarged diameter portion 27 in the conductor 26 can apply a substantially equal pressure to the peripheral edge portion 15 of the back electrode plate 14, it can be applied evenly to the spacer 18 and the diaphragm 13 side. The sensitivity and frequency response can also be stabilized.

  The above is the description of the present invention based on the illustrated example, and the specific configuration is not limited thereto. For example, the conductor 26 may form the enlarged diameter portion 29 without providing the skirt portion 28 as long as it can reliably contact the peripheral edge portion 15 of the back electrode plate 14. The conductor 26 may have any specific shape as long as the conductor 26 includes the enlarged diameter portion 29 and the reduced diameter portion 29. Furthermore, the conductor 26 may be one in which a conductive layer is formed on the surface of a resin molded product as a base.

The longitudinal cross-sectional view which shows an example of this invention. The top view of the printed circuit board which is a structural member of the unit shown in FIG. The longitudinal cross-sectional view which shows the structural example of the conventional electret type | mold condenser microphone unit. The top view of the printed circuit board which is a structural member of the unit shown in FIG.

DESCRIPTION OF SYMBOLS 11 Condenser microphone unit 12 Condenser part 13 Diaphragm 13a Diaphragm ring 13b Diaphragm 14 Back electrode plate 14a Outer peripheral surface 14b Lower surface 15 Peripheral part 16 Through-hole 18 Spacer 19 Insulation sleeve 20 Inner side surface 22 Printed circuit board 23 Impedance converter 24 Pattern layer 25 Interposition Pattern layer 26 Conductor 26a Expanded edge 27 Expanded portion 28 Bottom portion 29 Reduced portion 30 Contact surface 32 Metal case 33 Front acoustic terminal hole 34 Open portion 35 Open edge

Claims (2)

In a condenser microphone unit in which a back electrode plate that forms a capacitor portion with a diaphragm and an impedance converter mounted on a printed circuit board are electrically connected via a conductor and housed in a metal case ,
A pattern layer that conducts through an intervening pattern layer and an impedance converter mounted in the vicinity of the surface region located at a substantially central portion of the printed circuit board corresponds to a decrease in insulation resistance on the surface of the printed circuit board. While providing and providing a creepage distance between the metal case ,
The conductor includes the enlarged diameter portion that is contacted by applying substantially equal pressure over the entire periphery of the peripheral portion of the back electrode plate, and the pattern layer through a flat contact surface having substantially the same surface size as the pattern layer. A condenser microphone unit, characterized in that it is formed of a conductive member having at least a reduced-diameter portion in contact with the electrode.   The condenser microphone unit according to claim 1, wherein the conductor is formed of a conductive member made of a hollow metal material having a substantially frustoconical shape.

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