WO2006095946A1 - Improved condenser microphone - Google Patents

Improved condenser microphone Download PDF

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Publication number
WO2006095946A1
WO2006095946A1 PCT/KR2005/002620 KR2005002620W WO2006095946A1 WO 2006095946 A1 WO2006095946 A1 WO 2006095946A1 KR 2005002620 W KR2005002620 W KR 2005002620W WO 2006095946 A1 WO2006095946 A1 WO 2006095946A1
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WO
WIPO (PCT)
Prior art keywords
diaphragm
back electret
condenser microphone
electret
edge portion
Prior art date
Application number
PCT/KR2005/002620
Other languages
French (fr)
Inventor
Jun Lim
Eek Joo Chung
Original Assignee
Bse Co., Ltd.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Bse Co., Ltd. filed Critical Bse Co., Ltd.
Publication of WO2006095946A1 publication Critical patent/WO2006095946A1/en

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R19/00—Electrostatic transducers
    • H04R19/01—Electrostatic transducers characterised by the use of electrets
    • H04R19/016—Electrostatic transducers characterised by the use of electrets for microphones
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R1/00—Details of transducers, loudspeakers or microphones
    • H04R1/02—Casings; Cabinets ; Supports therefor; Mountings therein
    • H04R1/04—Structural association of microphone with electric circuitry therefor
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R31/00—Apparatus or processes specially adapted for the manufacture of transducers or diaphragms therefor
    • H04R31/006—Interconnection of transducer parts

Definitions

  • the present invention relates to a condenser microphone, and in particular, to a condenser microphone wherein a concaved portion is formed in a center portion of a back electret to eliminate a need for a spacer.
  • FIG. 1 is cross-sectional view schematically illustrating a typical condenser microphone.
  • the typical condenser microphone 10 comprises a metal casing 11 having a cylinder shape and having an acoustic hole lla disposed on a front plate thereof, a polar ring 12b consisting of a conductive material, a diaphragm 12a, a spacer 13, a ring-shaped first base 14 (alternately referred to as an "insulation base") consisting of an insulating material, a back electret 15 (alternately referred to as an "fixed electrode”) opposing the diaphragm 12a and having the spacer 13 therebetween, a sec ond base 16 (alternately referred to as an "conductive base”) consisting of a conductive material, and a PCB 17 having a circuit component and a connection terminal disposed thereon.
  • a metal casing 11 having a cylinder shape and having an acoustic hole lla disposed on a front plate thereof
  • a polar ring 12b consisting of a conductive material
  • the condenser microphone 10 is manufactured by sequentially stacking the components and curling an end of the casing 11.
  • the polar ring 12b and the diaphragm 12a are bonded together as a single body 12, and the back electret 15 has a structure wherein a high molecular film 15b is coated on metal plate 15a to form an electret in case of an electret type microphone.
  • the conventional condenser microphone the spacer 13 is inserted between the diaphragm 12a and the back electret 15 in order to form an air gap for a formation of an electrode.
  • the air gap maintains a distance between the diaphragm 12a and the back electret 15 to be constant from a center to an edge of the diaphragm.
  • a condenser microphone comprising: a cylinder-shape metal casing having an acoustic hole through a front plate thereof; polar ring consisting of a conductor; a diaphragm; a ring-shape first base consisting of an insulating material; a back electret consisting of a metal plate having a high molecule film coated thereon, the back electret having an edge portion contacting the diaphragm, wherein a surface of the high molecule film opposing that of the diaphragm includes a concaved surface deepening away from the edge portion to a center portion thereof; a second base consisting of a conductor; and a PCB having a circuit component mounted thereon and a connection terminal formed thereon.
  • a condenser microphone comprising: a cylinder-shape metal casing having an acoustic hole through a front plate thereof, the front plate having a step for supporting a diaphragm; the diaphragm; a ring-shape first base consisting of an insulating material; a back electret including a structure wherein a metal plate has a high molecule film coated thereon to form an electret, the back electret having the diaphragm attached to an edge portion thereof, wherein a surface of the high molecule film opposing that of the diaphragm includes a concaved surface deepening away from the edge portion to a center portion thereof; a second base consisting of a conductor; and a PCB having a circuit component mounted thereon and a connection terminal formed thereon.
  • a condenser microphone comprising: a cylinder-shape metal casing having an acoustic hole through a front plate thereof, the front plate having a step for supporting a diaphragm; the diaphragm; a back electret having the diaphragm attached to an edge portion thereof, wherein a surface of the back electret opposing that of the diaphragm includes a concaved surface deepening away from the edge portion to a center portion thereof; a ring-shape first base consisting of an insulating material for supporting the back electret; a second base consisting of a conductor; and a PCB having a circuit component mounted thereon and a connection terminal formed thereon.
  • a center portion of a back electret is subjected to a series of processes such as a pressing to render a surface of a high molecular film of the back electret opposing a diaphragm into a concaved surface similar to a vibrating form of the diaphragm so that a conversion of a displacement of the diaphragm to an electrical signal is maximized to improve a sensitivity and that the spacer for forming an insulation space is eliminated to reduce the number of components and the manufacturing cost.
  • FIG. 1 is schematic diagram illustrating a conventional typical condenser microphone.
  • FIG. 2 is a cross-sectional view illustrating a condenser microphone in accordance with a first embodiment of the present invention.
  • FIG. 3 is a cross-sectional view illustrating a condenser microphone in accordance with a second embodiment of the present invention.
  • FIG. 4 is a cross-sectional view illustrating a condenser microphone in accordance with a third embodiment of the present invention. Best Mode for Carrying Out the Invention
  • the present invention is characterized in that a center portion of a back electret is subjected to a series of processes such as a pressing to render a surface of the back electret opposing a diaphragm into a concaved surface similar to a vibrating form of the diaphragm so as to maximize a conversion of a displacement of the diaphragm to an electrical signal as well as to eliminate the spacer, thereby reducing the number of components.
  • an air gap forming an electrode of the condenser microphone is formed in such a manner that a center thereof is large and an edge thereof is small to increase the sensitivity of the condenser microphone by maximizing the conversion of the displacement of the diaphragm to the electrical signal.
  • such structure does not require a use of the spacer for forming the air gap employed in the conventional condenser microphone, and the diaphragm may be bonded to the back electret as a single body, resulting in a condenser microphone having a simpler structure.
  • the condenser microphone having the structure wherein the concaved surface is formed on the back electret to eliminate the spacer.
  • Embodiments of the present invention will be described by three preferred embodiments, namely a first embodiment which is related to a basic structure, a second embodiment wherein a step is formed in a casing to eliminate a polar ring as well as the spacer, and a third embodiment wherein a conductive film surrounds the back electret as a single body.
  • FIG. 2 is a cross-sectional view illustrating a condenser microphone in accordance with the first embodiment of the present invention, wherein the spacer is removed by forming a concaved surface which deepens at a center on a surface of the back electret opposing a diaphragm.
  • the condenser microphone 100 in accordance with the first embodiment of the present invention comprises a cylinder-shape casing 102 having an acoustic hole 102a through a front plate thereof, a polar ring 104b consisting of a conductor, a diaphragm 104a, a ring-shape first base 106 consisting of an insulating material, a back electret 108 having an edge portion thereof contacting the diaphragm 104a, wherein a surface of the back electret 108 opposing that of the diaphragm 104a includes a concaved surface which deepens away from the edge portion to a center portion thereof, a second base 110 consisting of a conductor, and a PCB 112 having a circuit component mounted thereon and a connection terminal formed thereon.
  • the condenser microphone 100 is manufactured by sequentially stacking the above components in the casing 102 and then curling an end portion of
  • the polar ring 104b and the diaphragm 104a may be bonded to each other to form a single body type vibrating plate 104
  • the back electret 108 includes a structure wherein a metal plate 108a is bonded to a high molecule film 108b to form an electret.
  • 108c of Fig. 2 denotes an acoustic hole formed in the back electret 108.
  • a first power supply (-) of the PCB is applied to the diaphragm 104a through the casing 102 and the polar ring 104b, and a second power supply (+) is applied to the metal plate 108a of the back electret through the second base 110 to form a capacitor between the back electret 108 and the diaphragm 104a.
  • An insulation is maintained between the diaphragm 104a and the back electret 108 by the first base 106 and the high molecular film 108b of the back electret.
  • a concaved surface similar to a vibrating form of the diaphragm is formed on a surface of the back electret 108 opposing the diaphragm 104a to maximize a conversion of the displacement of the diaphragm to the electrical signal.
  • FIG. 3 is a cross-sectional view illustrating a condenser microphone in accordance with a second embodiment of the present invention, wherein a surface of a back electret 208 opposing a diaphragm 204 is formed to be a concaved surface which deepens from an edge portion to a center portion and the diaphragm 204 is attached to the back electret 208 as a single body.
  • the condenser microphone 200 in accordance with the second embodiment of the present invention comprises a cylinder-shape metal casing 202 having an acoustic hole 202a through a front plate thereof, the front plate having a step 202b for supporting a diaphragm, the diaphragm 204, a ring-shape first base 206 consisting of an insulating material, a back electret 208 having the diaphragm 204 attached to an edge portion thereof, wherein a surface of the back electret 208 opposing that of the diaphragm 204 includes a concaved surface which deepens away from the edge portion to a center portion thereof, a second base 210 consisting of a conductor and a PCB 212 having a circuit component mounted thereon and a connection terminal formed thereon.
  • the condenser microphone 200 is manufactured by sequentially stacking the above components in the casing 202 and then curling an end portion of the casing 202.
  • the back electret 208 includes a structure wherein a metal plate 208a has a high molecule film 208b attached thereto to form an electret.
  • the diaphragm 204 is attached to the edge portion of the back electret having a spherical surface to eliminate a need for the polar ring required for fixing the diaphragm 204 to the conventional condenser microphone.
  • the step should be formed at a center of the casing 202 so that the diaphragm does not touch the casing 202.
  • 208c of Fig. 3 denotes an acoustic hole formed in the back electret 208.
  • a first power supply (-) of the PCB is applied to the diaphragm 204a through the step 202b of the casing 202, and a second power supply (+) is applied to the metal plate 208a of the back electret through the second base 210 to form a capacitor between the diaphragm 204 and the back electret 208.
  • An insulation is maintained between the diaphragm 204 and the back electret 208 by the first base 206 and the high molecular film 208b of the back electret.
  • a displacement of the diaphragm 204 is the largest at a center thereof and the displacement gets smaller as it gets close to the edge portion thereof when the diaphragm 204 is vibrated by externally induced the sound wave a primary resonance occurs.
  • a concaved surface similar to a vibrating form of the diaphragm is formed on a surface of the back electret 208 opposing the diaphragm 204 to maximize a conversion of the displacement of the diaphragm to the electrical signal.
  • FIG. 4 is a cross-sectional view illustrating a condenser microphone in accordance with a third embodiment of the present invention, wherein a surface of a back electret 308 opposing a diaphragm 304 is formed to be a concaved surface which deepens from an edge portion to a center portion and the diaphragm 304 is attached to the back electret 208 to surround a side surface of the back electret 308. As shown, an area of the diaphragm 304 is larger than that of the back electret 308 so that an edge portion of the diaphragm covers the side surface of the back electret.
  • the diaphragm/ back electret integrated structure insulates the back electret from the casing when inserted in the casing of the condenser microphone, thereby not requiring an additional component for insulating the back electret 308 from the casing 202.
  • the condenser microphone 300 in accordance with the third embodiment of the present invention comprises a cylinder-shape metal casing 302 having an acoustic hole 302a through a front plate thereof, the front plate having a step 302b for supporting a diaphragm, the diaphragm 304, a ring-shape first base 306 consisting of an insulating material for supporting a back electret 308, the back electret 308 having the diaphragm 304 attached to an edge portion thereof, wherein a surface of the back electret 308 opposing that of the diaphragm 304 includes a concaved surface which deepens away from the edge portion to a center portion thereof, a second base 310 consisting of a conductor, and a PCB 312 having a circuit component mounted thereon and a connection terminal formed thereon.
  • the condenser microphone 300 is manufactured by sequentially stacking the above components in the casing 302 and then curling an end portion of the casing 302.
  • the back electret 308 includes a structure wherein a metal plate 308a has a high molecule film 308b attached thereto to form an electret.
  • the diaphragm 304 is attached to the edge portion of the back electret having a spherical surface to eliminate a need for the polar ring required for fixing the diaphragm 304 to the conventional condenser microphone.
  • 308c of Fig. 4 denotes an acoustic hole formed in the back electret 308.
  • a first power supply (-) of the PCB is applied to the diaphragm 304 through the step 302b of the casing 302, and a second power supply (+) is applied to the metal plate 308a of the back electret through the second base 310 to form a capacitor between the back electret 308 and the diaphragm 304.
  • An insulation is maintained between the diaphragm 304 and the back electret 308 by the first base 306 and the high molecular film 308b of the back electret and a high molecular film of the diaphragm.
  • a displacement of the diaphragm 304 is the largest at a center thereof and the displacement gets smaller as it gets close to the edge portion thereof when the diaphragm 304 is vibrated by externally induced the sound wave a primary resonance occurs.
  • a concaved surface similar to a vibrating form of the diaphragm is formed on a surface of the back electret 308 opposing the diaphragm 304 to maximize a conversion of the displacement of the diaphragm to the electrical signal.
  • a condenser microphone wherein a concaved portion is formed in a back electret to form an air gap between a diaphragm and the back electret without a spacer, thereby improving a sensitivity is provided.

Abstract

The present invention relates to a condenser microphone wherein a spacer is eliminated by forming a concaved portion at a center portion of a back electret. The condenser microphone in accordance with the present invention comprises a cylinder-shape metal casing having an acoustic hole through a front plate thereof; polar ring consisting of a conductor; a diaphragm; a ring-shape first base consisting of an insulating material; a back electret consisting of a metal plate having a high molecule film coated thereon, the back electret having an edge portion contacting the diaphragm, wherein a surface of the high molecule film opposing that of the diaphragm includes a concaved surface deepening away from the edge portion to a center portion thereof; a second base consisting of a conductor; and a PCB having a circuit component mounted thereon and a connection terminal formed thereon. Therefore, in accordance with the present invention, a center portion of a back electret is subjected to a series of processes such as a pressing to render a surface of a high molecular film of the back electret opposing a diaphragm into a concaved surface similar to a vibrating form of the diaphragm so that a conversion of a displacement of the diaphragm to an electrical signal is maximized to improve a sensitivity and that the spacer for forming an insulation space is eliminated to reduce the number of components and the manufacturing cost.

Description

Description
IMPROVED CONDENSER MICROPHONE
Technical Field
[1] The present invention relates to a condenser microphone, and in particular, to a condenser microphone wherein a concaved portion is formed in a center portion of a back electret to eliminate a need for a spacer. Background Art
[2] Fig. 1 is cross-sectional view schematically illustrating a typical condenser microphone.
[3] The typical condenser microphone 10 comprises a metal casing 11 having a cylinder shape and having an acoustic hole lla disposed on a front plate thereof, a polar ring 12b consisting of a conductive material, a diaphragm 12a, a spacer 13, a ring-shaped first base 14 (alternately referred to as an "insulation base") consisting of an insulating material, a back electret 15 (alternately referred to as an "fixed electrode") opposing the diaphragm 12a and having the spacer 13 therebetween, a sec ond base 16 (alternately referred to as an "conductive base") consisting of a conductive material, and a PCB 17 having a circuit component and a connection terminal disposed thereon. The condenser microphone 10 is manufactured by sequentially stacking the components and curling an end of the casing 11. The polar ring 12b and the diaphragm 12a are bonded together as a single body 12, and the back electret 15 has a structure wherein a high molecular film 15b is coated on metal plate 15a to form an electret in case of an electret type microphone.
[4] As described above, the conventional condenser microphone the spacer 13 is inserted between the diaphragm 12a and the back electret 15 in order to form an air gap for a formation of an electrode. The air gap maintains a distance between the diaphragm 12a and the back electret 15 to be constant from a center to an edge of the diaphragm.
[5] However, in accordance with the conventional structure, an unnecessary air gap exists at the edge of the diaphragm where the diaphragm hardly moves. Therefore, a sensitivity of the condenser microphone is degraded.
[6] Moreover, in accordance with the conventional microphone, a separate spacer is required to form a space between the diaphragm and the back electret. If the spacer is eliminated, a manufacturing process is simplified and a manufacturing cost is reduced. Disclosure of Invention Technical Problem
[7] It is an object of the present invention to provide a condenser microphone wherein a concaved portion is formed in a back electret to form an air gap between a diaphragm and the back electret without a spacer, thereby improving a sensitivity. Technical Solution
[8] In order to achieve the above object of the invention, there is provided a condenser microphone comprising: a cylinder-shape metal casing having an acoustic hole through a front plate thereof; polar ring consisting of a conductor; a diaphragm; a ring-shape first base consisting of an insulating material; a back electret consisting of a metal plate having a high molecule film coated thereon, the back electret having an edge portion contacting the diaphragm, wherein a surface of the high molecule film opposing that of the diaphragm includes a concaved surface deepening away from the edge portion to a center portion thereof; a second base consisting of a conductor; and a PCB having a circuit component mounted thereon and a connection terminal formed thereon.
[9] In order to achieve the above object of the invention, there is provided a condenser microphone comprising: a cylinder-shape metal casing having an acoustic hole through a front plate thereof, the front plate having a step for supporting a diaphragm; the diaphragm; a ring-shape first base consisting of an insulating material; a back electret including a structure wherein a metal plate has a high molecule film coated thereon to form an electret, the back electret having the diaphragm attached to an edge portion thereof, wherein a surface of the high molecule film opposing that of the diaphragm includes a concaved surface deepening away from the edge portion to a center portion thereof; a second base consisting of a conductor; and a PCB having a circuit component mounted thereon and a connection terminal formed thereon.
[10] In order to achieve the above object of the invention, there is provided a condenser microphone comprising: a cylinder-shape metal casing having an acoustic hole through a front plate thereof, the front plate having a step for supporting a diaphragm; the diaphragm; a back electret having the diaphragm attached to an edge portion thereof, wherein a surface of the back electret opposing that of the diaphragm includes a concaved surface deepening away from the edge portion to a center portion thereof; a ring-shape first base consisting of an insulating material for supporting the back electret; a second base consisting of a conductor; and a PCB having a circuit component mounted thereon and a connection terminal formed thereon.
Advantageous Effects
[11] As described above, in accordance with the present invention, a center portion of a back electret is subjected to a series of processes such as a pressing to render a surface of a high molecular film of the back electret opposing a diaphragm into a concaved surface similar to a vibrating form of the diaphragm so that a conversion of a displacement of the diaphragm to an electrical signal is maximized to improve a sensitivity and that the spacer for forming an insulation space is eliminated to reduce the number of components and the manufacturing cost.
[12] While the present invention has been particularly shown and described with reference to the preferred embodiment thereof, it will be understood by those skilled in the art that various changes in form and details may be effected therein without departing from the spirit and scope of the invention as defined by the appended claims. Brief Description of the Drawings
[13] Fig. 1 is schematic diagram illustrating a conventional typical condenser microphone.
[14] Fig. 2 is a cross-sectional view illustrating a condenser microphone in accordance with a first embodiment of the present invention.
[15] Fig. 3 is a cross-sectional view illustrating a condenser microphone in accordance with a second embodiment of the present invention.
[16] Fig. 4 is a cross-sectional view illustrating a condenser microphone in accordance with a third embodiment of the present invention. Best Mode for Carrying Out the Invention
[17] The present invention is characterized in that a center portion of a back electret is subjected to a series of processes such as a pressing to render a surface of the back electret opposing a diaphragm into a concaved surface similar to a vibrating form of the diaphragm so as to maximize a conversion of a displacement of the diaphragm to an electrical signal as well as to eliminate the spacer, thereby reducing the number of components.
[18] That is, in accordance with a shape of a moving diaphragm when an externally induced sound wave vibrates a vibrating plate of the condenser microphone, before a primary resonance of the diaphragm occurs, a displacement of the diaphragm is the largest at a center thereof and the displacement gets smaller as it gets close to an edge portion thereof because the edge portion of the diaphragm is fixed to a polar ring. Therefore, in accordance with the present invention, an air gap forming an electrode of the condenser microphone is formed in such a manner that a center thereof is large and an edge thereof is small to increase the sensitivity of the condenser microphone by maximizing the conversion of the displacement of the diaphragm to the electrical signal. Further, such structure does not require a use of the spacer for forming the air gap employed in the conventional condenser microphone, and the diaphragm may be bonded to the back electret as a single body, resulting in a condenser microphone having a simpler structure.
[19] As described above, various structures are possible for the condenser microphone having the structure wherein the concaved surface is formed on the back electret to eliminate the spacer. Embodiments of the present invention will be described by three preferred embodiments, namely a first embodiment which is related to a basic structure, a second embodiment wherein a step is formed in a casing to eliminate a polar ring as well as the spacer, and a third embodiment wherein a conductive film surrounds the back electret as a single body.
[20] Fig. 2 is a cross-sectional view illustrating a condenser microphone in accordance with the first embodiment of the present invention, wherein the spacer is removed by forming a concaved surface which deepens at a center on a surface of the back electret opposing a diaphragm.
[21] Referring to Fig. 2, the condenser microphone 100 in accordance with the first embodiment of the present invention comprises a cylinder-shape casing 102 having an acoustic hole 102a through a front plate thereof, a polar ring 104b consisting of a conductor, a diaphragm 104a, a ring-shape first base 106 consisting of an insulating material, a back electret 108 having an edge portion thereof contacting the diaphragm 104a, wherein a surface of the back electret 108 opposing that of the diaphragm 104a includes a concaved surface which deepens away from the edge portion to a center portion thereof, a second base 110 consisting of a conductor, and a PCB 112 having a circuit component mounted thereon and a connection terminal formed thereon. Preferably, the condenser microphone 100 is manufactured by sequentially stacking the above components in the casing 102 and then curling an end portion of the casing 102.
[22] In addition, the polar ring 104b and the diaphragm 104a may be bonded to each other to form a single body type vibrating plate 104, and the back electret 108 includes a structure wherein a metal plate 108a is bonded to a high molecule film 108b to form an electret. 108c of Fig. 2 denotes an acoustic hole formed in the back electret 108.
[23] In accordance with the first embodiment, a first power supply (-) of the PCB is applied to the diaphragm 104a through the casing 102 and the polar ring 104b, and a second power supply (+) is applied to the metal plate 108a of the back electret through the second base 110 to form a capacitor between the back electret 108 and the diaphragm 104a. An insulation is maintained between the diaphragm 104a and the back electret 108 by the first base 106 and the high molecular film 108b of the back electret.
[24] When an external sound wave is induced through the acoustic hole 102a of the casing in the opposing state, because an edge portion of the diaphragm 104a is fixed to the polar ring 104b, a displacement of the diaphragm 104a is the largest at a center thereof and the displacement gets smaller as it gets close to the edge portion thereof when the diaphragm 104 is vibrated by externally induced the sound wave before a primary resonance occurs. In accordance with the present invention, a concaved surface similar to a vibrating form of the diaphragm is formed on a surface of the back electret 108 opposing the diaphragm 104a to maximize a conversion of the displacement of the diaphragm to the electrical signal.
[25] Therefore, a sensitivity of the condenser microphone 100 in accordance with the present invention is improved and the spacer which is required in the conventional condenser microphone structure is eliminated to reduce the manufacturing cost. Mode for the Invention
[26] Fig. 3 is a cross-sectional view illustrating a condenser microphone in accordance with a second embodiment of the present invention, wherein a surface of a back electret 208 opposing a diaphragm 204 is formed to be a concaved surface which deepens from an edge portion to a center portion and the diaphragm 204 is attached to the back electret 208 as a single body.
[27] Referring to Fig. 3, the condenser microphone 200 in accordance with the second embodiment of the present invention comprises a cylinder-shape metal casing 202 having an acoustic hole 202a through a front plate thereof, the front plate having a step 202b for supporting a diaphragm, the diaphragm 204, a ring-shape first base 206 consisting of an insulating material, a back electret 208 having the diaphragm 204 attached to an edge portion thereof, wherein a surface of the back electret 208 opposing that of the diaphragm 204 includes a concaved surface which deepens away from the edge portion to a center portion thereof, a second base 210 consisting of a conductor and a PCB 212 having a circuit component mounted thereon and a connection terminal formed thereon. Preferably, the condenser microphone 200 is manufactured by sequentially stacking the above components in the casing 202 and then curling an end portion of the casing 202. The back electret 208 includes a structure wherein a metal plate 208a has a high molecule film 208b attached thereto to form an electret. The diaphragm 204 is attached to the edge portion of the back electret having a spherical surface to eliminate a need for the polar ring required for fixing the diaphragm 204 to the conventional condenser microphone. In this case, the step should be formed at a center of the casing 202 so that the diaphragm does not touch the casing 202. 208c of Fig. 3 denotes an acoustic hole formed in the back electret 208.
[28] In accordance with the second embodiment, a first power supply (-) of the PCB is applied to the diaphragm 204a through the step 202b of the casing 202, and a second power supply (+) is applied to the metal plate 208a of the back electret through the second base 210 to form a capacitor between the diaphragm 204 and the back electret 208. An insulation is maintained between the diaphragm 204 and the back electret 208 by the first base 206 and the high molecular film 208b of the back electret.
[29] When an external sound wave is induced through the acoustic hole 202a of the casing in the opposing state, a displacement of the diaphragm 204 is the largest at a center thereof and the displacement gets smaller as it gets close to the edge portion thereof when the diaphragm 204 is vibrated by externally induced the sound wave a primary resonance occurs. In accordance with the present invention, a concaved surface similar to a vibrating form of the diaphragm is formed on a surface of the back electret 208 opposing the diaphragm 204 to maximize a conversion of the displacement of the diaphragm to the electrical signal.
[30] Therefore, a sensitivity of the condenser microphone 200 in accordance with the present invention is improved and the spacer which is required in the conventional condenser microphone structure is eliminated to reduce the manufacturing cost.
[31] Fig. 4 is a cross-sectional view illustrating a condenser microphone in accordance with a third embodiment of the present invention, wherein a surface of a back electret 308 opposing a diaphragm 304 is formed to be a concaved surface which deepens from an edge portion to a center portion and the diaphragm 304 is attached to the back electret 208 to surround a side surface of the back electret 308. As shown, an area of the diaphragm 304 is larger than that of the back electret 308 so that an edge portion of the diaphragm covers the side surface of the back electret. Therefore, the diaphragm/ back electret integrated structure insulates the back electret from the casing when inserted in the casing of the condenser microphone, thereby not requiring an additional component for insulating the back electret 308 from the casing 202.
[32] Referring to Fig. 4, the condenser microphone 300 in accordance with the third embodiment of the present invention comprises a cylinder-shape metal casing 302 having an acoustic hole 302a through a front plate thereof, the front plate having a step 302b for supporting a diaphragm, the diaphragm 304, a ring-shape first base 306 consisting of an insulating material for supporting a back electret 308, the back electret 308 having the diaphragm 304 attached to an edge portion thereof, wherein a surface of the back electret 308 opposing that of the diaphragm 304 includes a concaved surface which deepens away from the edge portion to a center portion thereof, a second base 310 consisting of a conductor, and a PCB 312 having a circuit component mounted thereon and a connection terminal formed thereon. Preferably, the condenser microphone 300 is manufactured by sequentially stacking the above components in the casing 302 and then curling an end portion of the casing 302. The back electret 308 includes a structure wherein a metal plate 308a has a high molecule film 308b attached thereto to form an electret. The diaphragm 304 is attached to the edge portion of the back electret having a spherical surface to eliminate a need for the polar ring required for fixing the diaphragm 304 to the conventional condenser microphone. 308c of Fig. 4 denotes an acoustic hole formed in the back electret 308.
[33] In accordance with the third embodiment, a first power supply (-) of the PCB is applied to the diaphragm 304 through the step 302b of the casing 302, and a second power supply (+) is applied to the metal plate 308a of the back electret through the second base 310 to form a capacitor between the back electret 308 and the diaphragm 304. An insulation is maintained between the diaphragm 304 and the back electret 308 by the first base 306 and the high molecular film 308b of the back electret and a high molecular film of the diaphragm.
[34] When an external sound wave is induced through the acoustic hole 302a of the casing in the opposing state, a displacement of the diaphragm 304 is the largest at a center thereof and the displacement gets smaller as it gets close to the edge portion thereof when the diaphragm 304 is vibrated by externally induced the sound wave a primary resonance occurs. In accordance with the present invention, a concaved surface similar to a vibrating form of the diaphragm is formed on a surface of the back electret 308 opposing the diaphragm 304 to maximize a conversion of the displacement of the diaphragm to the electrical signal.
[35] Therefore, a sensitivity of the condenser microphone 200 in accordance with the present invention is improved and the spacer which is required in the conventional condenser microphone structure is eliminated to reduce the manufacturing cost. Industrial Applicability
[36] A condenser microphone wherein a concaved portion is formed in a back electret to form an air gap between a diaphragm and the back electret without a spacer, thereby improving a sensitivity is provided.
[37]
[38]

Claims

Claims
[ 1 ] A condenser microphone comprising : a cylinder-shape metal casing having an acoustic hole through a front plate thereof; a polar ring consisting of a conductor; a diaphragm; a ring-shape first base consisting of an insulating material; a back electret consisting of a metal plate having a high molecule film coated thereon, the back electret having an edge portion contacting the diaphragm, wherein a surface of the high molecule film opposing that of the diaphragm includes a concaved surface deepening away from the edge portion to a center portion thereof; a second base consisting of a conductor; and a PCB having a circuit component mounted thereon and a connection terminal formed thereon.
[2] A condenser microphone comprising: a cylinder-shape metal casing having an acoustic hole through a front plate thereof, the front plate having a step for supporting a diaphragm; the diaphragm; a ring-shape first base consisting of an insulating material; a back electret including a structure wherein a metal plate has a high molecule film coated thereon to form an electret, the back electret having the diaphragm attached to an edge portion thereof, wherein a surface of the high molecule film opposing that of the diaphragm includes a concaved surface deepening away from the edge portion to a center portion thereof; a second base consisting of a conductor; and a PCB having a circuit component mounted thereon and a connection terminal formed thereon.
[3] A condenser microphone comprising: a cylinder-shape metal casing having an acoustic hole through a front plate thereof, the front plate having a step for supporting a diaphragm; the diaphragm; a back electret having the diaphragm attached to an edge portion thereof, wherein a surface of the back electret opposing that of the diaphragm includes a concaved surface deepening away from the edge portion to a center portion thereof; a ring-shape first base consisting of an insulating material for supporting the back electret; a second base consisting of a conductor; and a PCB having a circuit component mounted thereon and a connection terminal formed thereon.
[4] The condenser microphone in accordance with one of claims 2 and 3, wherein the diaphragm and the back electret are attached to each other as a single body.
PCT/KR2005/002620 2005-03-10 2005-08-11 Improved condenser microphone WO2006095946A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
KR1020050020185A KR100675508B1 (en) 2005-03-10 2005-03-10 Improved Condenser Microphone
KR10-2005-0020185 2005-03-10

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WO2006095946A1 true WO2006095946A1 (en) 2006-09-14

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EP2220875A1 (en) * 2007-11-20 2010-08-25 Otologics, LLC Implantable electret microphone
US8855350B2 (en) 2009-04-28 2014-10-07 Cochlear Limited Patterned implantable electret microphone
US9060229B2 (en) 2010-03-30 2015-06-16 Cochlear Limited Low noise electret microphone
CN105635865A (en) * 2014-10-30 2016-06-01 中芯国际集成电路制造(上海)有限公司 Microphone device and method for manufacturing same
CN111885470A (en) * 2020-06-16 2020-11-03 歌尔微电子有限公司 Capacitive micro-electro-mechanical system microphone, microphone monomer and electronic equipment

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CN101272637B (en) * 2008-04-22 2012-06-27 华英伦电子(宁波)有限公司 Electret capacitor type microphone with integral vocal cavity component

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US4016376A (en) * 1975-01-06 1977-04-05 General Signal Corporation Concave diaphragm for electro-acoustic transducer
JP2002171585A (en) * 2000-10-18 2002-06-14 Shochi Cho Directive microphone

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2220875A1 (en) * 2007-11-20 2010-08-25 Otologics, LLC Implantable electret microphone
EP2220875A4 (en) * 2007-11-20 2013-10-30 Cochlear Ltd Implantable electret microphone
US8855350B2 (en) 2009-04-28 2014-10-07 Cochlear Limited Patterned implantable electret microphone
US9060229B2 (en) 2010-03-30 2015-06-16 Cochlear Limited Low noise electret microphone
CN105635865A (en) * 2014-10-30 2016-06-01 中芯国际集成电路制造(上海)有限公司 Microphone device and method for manufacturing same
CN105635865B (en) * 2014-10-30 2019-04-05 中芯国际集成电路制造(上海)有限公司 A kind of microphone device and preparation method thereof
CN111885470A (en) * 2020-06-16 2020-11-03 歌尔微电子有限公司 Capacitive micro-electro-mechanical system microphone, microphone monomer and electronic equipment
CN111885470B (en) * 2020-06-16 2021-07-27 歌尔微电子有限公司 Capacitive micro-electro-mechanical system microphone, microphone monomer and electronic equipment

Also Published As

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KR100675508B1 (en) 2007-01-30

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