Unidirectional condenser microphone unit, unidirectional condenser microphone, and method of manufacturing unidirectional condenser microphone unit

Patent metadata

Field	Value
Publication number	US-9967678-B2
Application number	US-201615254374-A
Country	US
Kind code	B2
Filing date	Sep 1, 2016
Priority date	Sep 16, 2015
Publication date	May 8, 2018
Grant date	May 8, 2018

Abstract

A unidirectional condenser microphone unit is provided that have directionality unaffected by the external environment, and a method of manufacturing the unidirectional condenser microphone. The unidirectional condenser microphone unit having an interior and an exterior, the unidirectional condenser microphone includes a diaphragm, a fixed electrode facing the diaphragm, the fixed electrode constituting a capacitor with the diaphragm, an insulating base disposed in a back face side of the fixed electrode, the insulating base supporting the fixed electrode, an air chamber disposed in the back face side of the fixed electrode, and a gap disposed between the fixed electrode and the insulating base. The fixed electrode includes at least one sound hole in communication with the air chamber. The insulating base includes a communication hole establishing communication between the gap and the exterior of the microphone unit. The air chamber and the gap are in communication with each other.

First claim

The invention claimed is:

1. A unidirectional condenser microphone unit having an interior and an exterior, the unidirectional condenser microphone comprising:
a diaphragm;
a fixed electrode facing the diaphragm, the fixed electrode constituting a capacitor with the diaphragm;
an insulating base disposed in a back face side of the fixed electrode, the insulating base supporting the fixed electrode;
an air chamber disposed between the fixed electrode and the insulating base; and
a gap disposed between the fixed electrode and a central surface of the insulating base, the gap is disposed inward from the air chamber and above the central surface of the insulating base, and the air chamber is outside the central surface of the insulating base, wherein
the fixed electrode comprises at least one sound hole in communication with the air chamber,
the insulating base comprises a communication hole establishing communication between the gap and the exterior of the microphone unit, and
the air chamber and the gap are in communication with each other.

2. The unidirectional condenser microphone unit according to claim 1 , wherein
the gap accommodates an air layer, and
the air layer functions to transmit the acoustic waves from the communication hole as an acoustic resistor to the air chamber.

3. The unidirectional condenser microphone unit according to claim 1 , wherein
the fixed electrode has a shape of a plate, and
the at least one sound hole comprises a plurality of sound holes disposed along a circumferential direction of the fixed electrode.

4. The unidirectional condenser microphone unit according to claim 3 , wherein the air chamber constituted by a groove disposed in the insulating base along a circumferential direction of the insulating base.

5. The unidirectional condenser microphone unit according to claim 4 , wherein
the insulating base comprises a support,
the support comprises a step, and
the fixed electrode is fit with the step in the support and supported by the support.

6. The unidirectional condenser microphone unit according to claim 4 , wherein the air chamber surrounds an outer circumference of the gap.

7. The unidirectional condenser microphone according to claim 1 , wherein the gap has a smaller volume than the air chamber.

8. The unidirectional condenser microphone unit according to claim 1 , further comprising:
a unit case having a shape of a cylinder with an open end and a bottom end, the unit case accommodating the diaphragm, the fixed electrode, and the insulating base, wherein
the unit case has an opening covered by the insulating base,
the open end of the unit case has a curled portion,
the insulating base has a protrusion engaging with the curled portion, and
the protrusion is disposed on an outer circumference of a back face of the insulating base.

9. A unidirectional condenser microphone comprising:
a condenser microphone unit; and
a unit accommodating case accommodating the condenser microphone unit, wherein
the condenser microphone unit is the unidirectional condenser microphone unit according to claim 1 .

10. A method of manufacturing a unidirectional condenser microphone unit having an interior and an exterior comprising: a diaphragm;
a fixed electrode facing the diaphragm, the fixed electrode constituting a capacitor with the diaphragm;
an insulating base disposed in a back face side of the fixed electrode, the insulating base supporting the fixed electrode; and
a unit case having a shape of a cylinder with an open end and a bottom end, the unit case accommodating the diaphragm, the fixed electrode, and the insulating base,
the method comprising the steps of:
a) accommodating the diaphragm, the fixed electrode, and the insulating base in the unit case; and
b) curling the open end of the unit case, wherein step b) comprises:
forming an air chamber between the fixed electrode and the insulating base;
forming a gap between the fixed electrode and a central surface of the insulating base, the gap is disposed inward from the air chamber and above the central surface of the insulating base, and the air chamber is disposed outside the central surface of the insulating base;
establishing communication between the air chamber and the gap; and
wherein
the fixed electrode has a sound hole in communication with the air chamber,
the insulating base has a communication hole establishing communication between the gap and the exterior of the microphone unit, and
the sound hole is in communication with the communication hole after the step b).

11. A unidirectional condenser microphone unit having an interior and an exterior, the unidirectional condenser microphone comprising:
a diaphragm;
a fixed electrode facing the diaphragm, the fixed electrode constituting a capacitor with the diaphragm;
an insulating base disposed in a back face side of the fixed electrode, the insulating base supporting the fixed electrode;
an air chamber disposed between the fixed electrode and the insulating base; and
a gap disposed between the fixed electrode and the insulating base, the gap is disposed inward from the air chamber and has a smaller volume than the air chamber, wherein
the fixed electrode comprises at least one sound hole in communication with the air chamber,
the insulating base comprises a communication hole establishing communication between the gap and the exterior of the microphone unit, and
the air chamber and the gap are in communication with each other.

12. The unidirectional condenser microphone unit according to claim 11 , wherein
the gap accommodates an air layer, and
the air layer functions to transmit the acoustic waves from the communication hole as an acoustic resistor to the air chamber.

13. The unidirectional condenser microphone unit according to claim 11 , wherein
the fixed electrode has a shape of a plate, and
the at least one sound hole comprises a plurality of sound holes disposed along a circumferential direction of the fixed electrode.

14. The unidirectional condenser microphone unit according to claim 13 , wherein the air chamber constituted by a groove disposed in the insulating base along a circumferential direction of the insulating base.

15. The unidirectional condenser microphone unit according to claim 14 , wherein
the insulating base comprises a support,
the support comprises a step, and
the fixed electrode is fit with the step in the support and supported by the support.

16. The unidirectional condenser microphone unit according to claim 14 , wherein the air chamber surrounds an outer circumference of the gap.

17. The unidirectional condenser microphone unit according to claim 11 , further comprising:
a unit case having a shape of a cylinder with an open end and a bottom end, the unit case accommodating the diaphragm, the fixed electrode, and the insulating base, wherein
the unit case has an opening covered by the insulating base,
the open end of the unit case has a curled portion,
the insulating base has a protrusion engaging with the curled portion, and
the protrusion is disposed on an outer circumference of a back face of the insulating base.

18. A unidirectional condenser microphone comprising:
a condenser microphone unit; and
a unit accommodating case accommodating the condenser microphone unit, wherein
the condenser microphone unit is the unidirectional condenser microphone unit according to claim 11 .

Assignees

• Akino Hiroshi
• Audio Technica Kk

Inventors

• Akino Hiroshi

Classifications

• H04R31/00

  Apparatus or processes specially adapted for the manufacture of transducers or diaphragms therefor {(manufacture of microstructural arrangements of deformable or non-deformable structures in general B81C1/00182)} · CPC title

• H04R19/04 Primary

  Microphones (H04R19/01 takes precedence) · CPC title

• H04R19/016

  for microphones · CPC title

• H04R1/38

  in which sound waves act upon both sides of a diaphragm and incorporating acoustic phase-shifting means, e.g. pressure-gradient microphone · CPC title