Electret capacitor microphone

• US 6,594,369 B1
• Filed: 08/11/2000
• Issued: 07/15/2003
• Est. Priority Date: 08/11/1999
• Status: Expired due to Fees

• Current Assignee: Kyocera Corporation
• Original Assignee: Kyocera Corporation
• Inventors: Une, Hiroshi
• Primary Examiner(s): BARNIE, REXFORD N
• Application Number:
  US09/637,419
• Time in Patent Office: 1,068 Days
• Field of Search: 381/174, 381/191, 381/113, 381/344, 381/345, 381/353, 381/369, 381/178, 381/355, 381/354, 381/190
• US Class Current: 381/174
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/3025 Electromagnetic shielding
• CPC Class Codes: H04R 19/016 for microphones

Abstract

An electret capacitor microphone is constituted by a surface conductive diaphragm, a fixed electrode provided opposite to the diaphragm at a regular interval and a solid state device for converting, into an electric signal, a voice given to the diaphragm with a change in an electrostatic capacity between the diaphragm and the fixed electrode. The microphone comprises a dielectric casing having a bottomed hollow portion for accommodating the diaphragm, the fixed electrode and the solid state device. Since the casing itself is dielectric, it does not deed to accommodate a special dielectric or a board for the solid state device but can be directly provided in the hollow portion. Therefore, the microphone can be very small-sized and thinned. The hollow portion of the casing has a stepped portion and the diaphragm or the fixed electrode is fixed onto the stepped portion. The hollow portion of the casing has a rectangular cross section and the external shape of the casing is rectangular, the parts can easily be provided in the hollow portion, an unnecessary space can be omitted, and a size can be reduced.

Claims

1. An electret capacitor microphone comprising:

a surface conductive diaphragm;

a fixed electrode provided opposite to the diaphragm at a fixed interval; and

a solid state device for converting a change in an electrostatic capacity between the diaphragm and the fixed electrode induced by a sound signal given to the diaphragm into an electric signal,

wherein the electret capacitor microphone is provided with a dielectric casing defining a bottomed hollow portion for accommodating the diaphragm, the fixed electrode and the solid state device, and

wherein a conductive path is applied to an outer surface of the dielectric casing, an upper surface of an opening of the dielectric casing is metallized, a spacer in contact with the diaphragm is provided on an inner surface, and the upper surface of the opening is bonded to a metal cover with a conductive adhesive, thereby electrically connecting the diaphragm and the conductive path.

2. The electret capacitor microphone according to claim 1, wherein the conductive adhesive has a curing temperature of 150°

C. or less.

3. An electret capacitor microphone comprising:

a surface conductive diaphragm;

a fixed electrode provided opposite to the diaphragm at a fixed interval; and

a solid state device for converting a change in an electrostatic capacity between the diaphragm and the fixed electrode induced by a sound signal given to the diaphragm into an electric signal,

wherein the electret capacitor microphone is provided with a dielectric casing defining a bottomed hollow portion for accommodating the diaphragm, the fixed electrode and the solid state device, and

wherein at least one conductive path connecting the diaphragm or the fixed electrode to the solid state device is applied to an inner surface of the dielectric casing and at least one pad electrode connected to the conductive path is provided on a bottom side of the casing.

4. The electret capacitor microphone according to claim 3, wherein the dielectric casing forms at least one stepped portion projecting into the hollow portion of the casing and the diaphragm or the fixed electrode is fixed into onto the stepped portion.

5. The electret capacitor microphone according to claim 3, wherein the hollow portion of the casing has a rectangular cross section.

6. The electret capacitor microphone according to claim 5, wherein an external shape of the casing has a rectangular cross section.

7. The electret capacitor microphone according to claim 3, wherein an opening of the hollow portion is covered with a metal cover through which a sound hole penetrates.

8. The electret capacitor microphone according to claim 7, wherein the cover is provided opposite to the diaphragm capable of being used as the fixed electrode.

9. The electret capacitor microphone according to claim 3, wherein a combination of the fixed electrode and the diaphragm is located on an opening side of the hollow portion and the solid state device is provided on a bottom side in the hollow portion of the dielectric casing.

10. The electret capacitor microphone according to claim 3, wherein the solid state device is provided in parallel to the combination of the fixed electrode and the diaphragm in one hollow portion of the dielectric casing.

11. The electret capacitor microphone according to claim 3, wherein the hollow portion and another hollow portion are provided in the casing in parallel, and the combination of the fixed electrode and the diaphragm and the solid state device are provided in each separate hollow portion, respectively.

12. The electret capacitor microphone according to claim 3, wherein the fixed electrode, the diaphragm and the solid state device are accommodated in the hollow portion of the dielectric casing, and a hole is provided on a wall part of the hollow portion in a position behind the diaphragm.

13. The electret capacitor microphone according to claim 12, wherein the hole is formed on an inside bottom portion of the hollow portion.

17. The electret capacitor microphone according to any of claims 3 to 16, wherein the pad electrode of the casing is bonded to a corresponding electrode on a printed circuit board with a conductive adhesive and is mounted on the printed circuit board.

14. An electret capacitor microphone comprising:

a surface conductive diaphragm;

a fixed electrode provided opposite to the diaphragm at a fixed interval; and

a solid state device for converting a change in an electrostatic capacity between the diaphragm and the fixed electrode induced by a sound signal given to the diaphragm into an electric signal,

wherein the electret capacitor microphone is provided with a dielectric casing defining a bottomed hollow portion for accommodating the diaphragm, the fixed electrode and the solid state device, and

wherein at least one conductive path connecting the diaphragm and the fixed electrode is applied to an inner surface of the dielectric casing and at least one pad electrode connected to the conductive path is provided on a bottom side of the casing.

15. An electret capacitor microphone comprising:

a surface conductive diaphragm;

a fixed electrode provided opposite to the diaphragm at a fixed interval; and

a solid state device for converting a change in an electrostatic capacity between the diaphragm and the fixed electrode induced by a sound signal given to the diaphragm into an electric signal,

wherein the electret capacitor microphone is provided with a dielectric casing defining a bottomed hollow portion for accommodating the diaphragm, the fixed electrode and the solid state device, and

wherein at least one conductive path connecting the diaphragm or the fixed electrode to the solid state device is applied to an outer surface of the dielectric casing and at least one pad electrode connected to the conductive path is provided on a bottom side of the casing.

16. An electret capacitor microphone comprising:

a surface conductive diaphragm;

a fixed electrode provided opposite to the diaphragm at a fixed interval; and

a solid state device for converting a change in an electrostatic capacity between the diaphragm and the fixed electrode induced by a sound signal given to the diaphragm into an electric signal,

wherein the electret capacitor microphone is provided with a dielectric casing defining a bottomed hollow portion for accommodating the diaphragm, the fixed electrode and the solid state device, and

wherein at least one conductive path connecting the diaphragm and the fixed electrode is applied to an outer surface of the dielectric casing and at least one pad electrode connected to the conductive path is provided on a bottom side of the casing.