Condenser microphone and method for manufacturing the same

• US 20060140423A1
• Filed: 12/14/2005
• Published: 06/29/2006
• Est. Priority Date: 12/15/2004
• Status: Active Grant

• Current Assignee: Citizen Electronics Company Limited
• Original Assignee: Citizen Electronics Company Limited
• Inventors: Kanemaru, Atsushi, Tanabe, Haruhisa
• Granted Patent: US 7,620,191 B2
• Time in Patent Office: Days
• US Class Current: 381/174
• CPC Class Codes: H04R 19/016 for microphones
• CPC Class Codes: H04R 31/006 Interconnection of transducer parts of diaphragm and outer suspension by moulding H04R31/003

Abstract

A condenser microphone includes a housing and a microphone unit arranged within the housing. The microphone unit includes an annular retainer oriented in confronting relation to the front end wall of the housing, a movable diaphragm connected to the annular retainer, an annular spacer connected to one side of the movable diaphragm opposite the annular retainer, a substrate including a back electrode oriented in confronting relation to the movable diaphragm and having an electret thereon, and a printed circuit board having electronic components. The back electrode is operatively associated with the movable diaphragm to constitute a condenser. The condenser has a variable electric capacitance. The electronic components of the printed circuit board develop an electric signal in response to a change in the electrical capacitance between the movable diaphragm and the back electrode. A conductive adhesive is employed to sealingly hold the annular retainer against the front end wall of the housing.

Claims

1. A condenser microphone comprising:

a microphone unit; and

a housing shaped to enclose said microphone unit to mechanically protect said microphone unit,

said housing having a front end wall,

said microphone unit comprising;

an annular retainer having a front face oriented to face against said front end wall of said housing and a rear face;

a movable diaphragm having a front face, a rear face and a peripheral edge attached to said rear face of said annular retainer, said movable diaphragm being placed in confronting relation to said front end wall of said housing and vibrated in response to an incident sound pressure wave through said front end wall of said housing;

an annular spacer having a front face attached to said rear face of said movable diaphragm at the peripheral edge of said movable diaphragm and a rear face;

a substrate connected to said rear face of said annular spacer, said substrate including a back electrode having an electret thereon and oriented in confronting relation to said movable diaphragm, said back electrode being operatively associated with said movable diaphragm to constitute a condenser, said condenser having a variable electrical capacitance; and

a printed circuit board connected to said substrate and including an electronic component for generating an electric signal in response to said variable electrical capacitance,

said microphone unit being mounted in said housing so that said annular retainer is sealingly held against said front end wall of said housing.

2. The condenser microphone of claim 1, wherein said printed circuit board includes a ground terminal, and said microphone unit further includes an electrically conductive joining member through which said annular retainer is sealingly held against said front end wall of said housing, and electrically conducive adhesive layers for interconnecting said annular retainer, said movable diaphragm and said annular spacer, said annular retainer and said annular spacer being electrically conductive, said housing being made of a metallic material and electrically connected to said ground terminal of said printed circuit board through said electrically conductive joining member, said annular retainer, said movable diaphragm and said annular spacer.

3. The condenser microphone of claim 2, wherein said electrically conductive joining member is made from an electrically conductive adhesive.

4. The condenser microphone of claim 3, wherein said front end wall of said housing includes at least one sound inlet port, said condenser microphone further comprising a water repellent dust filter attached to one side of said front end wall of said housing opposite said microphone unit and positioned to cover said at least one sound inlet port.

5. A method for manufacturing a condenser microphone, comprising:

preparing a housing, said housing having a front end wall and a peripheral wall having a front end connected to said front end wall and an open rear end;

preparing a microphone unit by stacking an annular retainer, a movable diaphragm, an annular spacer, a substrate and a printed circuit board one above the other, said substrate including a back electrode oriented in confronting relation to said movable diaphragm and having an electret thereon, said back electrode being operatively associated with said movable diaphragm to constitute a condenser having a variable electrical capacitance, said printed circuit board including an electronic component for producing an electric signal in response to said variable electrical capacitance; and

inserting said electronic unit into said housing through said open rear end of said peripheral wall of said housing while keeping said annular retainer in the front of the microphone unit and sealingly joining said annular retainer to said front end wall of said housing by a joining member.

6. The method of claim 5, wherein said joining member is placed on said annular retainer before said microphone unit is inserted into said housing.

7. The method of claim 6, wherein said joining member is made of a thermosetting material, said joining member being heated after the joining member is pressed against said front end wall of said housing.