Internal vent structure for waterproof microphone acoustic cavity

Patent metadata

Field	Value
Publication number	US-9930435-B2
Application number	US-201514887647-A
Country	US
Kind code	B2
Filing date	Oct 20, 2015
Priority date	Oct 20, 2015
Publication date	Mar 27, 2018
Grant date	Mar 27, 2018

Abstract

A method and apparatus are described for providing an acoustically-resistive air-permeable venting structure within a sealed microphone acoustic cavity. A microphone is mounted on a printed circuit board and positioned within a housing. A water-resistant membrane seals the microphone from an exterior of the housing, and a active acoustic cavity establishes an acoustical connection between the water-resistant membrane and the microphone. An acoustically-resistive air-permeable venting structure is formed in the body of the printed circuit board and connects to the active acoustic cavity either directly or via a separate vent path. The venting structure provides a viscous dampening effect by venting an active acoustic cavity of the electronic device to the rest of the enclosure sealed by the water-resistant membrane.

First claim

We claim:

1. An electronic device comprising:
a housing;
a microphone mounted on a printed circuit board within the housing;
a water-resistant membrane sealing the microphone from an exterior of the housing; and
the printed circuit board including an acoustically-resistive air-permeable venting structure formed in a body of the printed circuit board.

2. The electronic device of claim 1 , wherein the water-resistant membrane is positioned to form a venting cavity on an interior side of the water-resistant membrane,
the electronic device further comprising a primary acoustic input channel coupling the venting cavity to the microphone.

3. The electronic device of claim 2 , wherein the printed circuit board is positioned between the microphone and the water-resistant membrane, and
wherein the printed circuit board includes an acoustic input hole through the body of the printed circuit board coupling the primary acoustic input channel to the microphone.

4. The electronic device of claim 2 , further comprising a venting channel coupling the venting cavity to the acoustically-resistive air-permeable venting structure formed in the body of the printed circuit board.

5. The electronic device of claim 4 , wherein the acoustically-resistive air-permeable venting structure formed in the body of the printed circuit board provides for restricted air flow between the venting cavity and another portion of the electronic device sealed from the exterior of the housing by the water-resistant membrane.

6. The electronic device of claim 1 , wherein the acoustically-resistive air-permeable venting structure includes a plurality of pitched channels formed in the printed circuit board.

7. The electronic device of claim 6 , wherein the plurality of pitched channels are linearly parallel across a surface of the printed circuit board.

8. The electronic device of claim 6 , wherein the plurality of pitched channels are formed by selectively removing a copper and solder resist using an etching process.

9. The electronic device of claim 1 , wherein the acoustically-resistive air-permeable venting structure includes a plurality of cross-hatched lines etched into a surface of the printed circuit board.

10. The electronic device of claim 1 , wherein the acoustically-resistive air-permeable venting structure includes a channel formed by an etched alternating switchback pattern on a surface of the printed circuit board.

11. The electronic device of claim 1 , further comprising an active acoustic cavity sealed from the exterior of the housing by the water-resistant membrane, and wherein the acoustically-resistive air-permeable venting structure is configured to vent the sealed active acoustic cavity to provide a viscous dampening effect that affects the acoustic response of the microphone.

12. A printed circuit board assembly for a sealed electronic device comprising:
a microphone mounted on a printed circuit board;
a first acoustic input hole formed through the printed circuit board adjacent to the microphone; and
an acoustically-resistive air-permeable venting structure formed in the printed circuit board.

13. The printed circuit board assembly of claim 12 , wherein the printed circuit board assembly is configured to be enclosed in the sealed electronic device such that acoustic vibrations pass through a water-resistant membrane of the sealed electronic device and through the first acoustic input hole to reach the microphone, and wherein the acoustically-resistive air-permeable venting structure is configured to vent an active acoustic cavity of the sealed electronic device to provide viscous acoustic dampening.

14. The printed circuit board assembly of claim 13 , wherein the acoustically-resistive air-permeable venting structure formed in a body of the printed circuit board provides for restricted air flow between a venting cavity and another portion of the electronic device sealed from an exterior of a housing of the electronic device by the water-resistant membrane.

15. The printed circuit board assembly of claim 12 , wherein the acoustically-resistive air-permeable venting structure includes a plurality of pitched channels formed in the printed circuit board.

16. The printed circuit board of claim 15 , wherein the plurality of pitched channels are linearly parallel across a surface of the printed circuit board.

17. The printed circuit board of claim 12 , wherein the acoustically-resistive air-permeable venting structure includes a plurality of cross-hatched lines etched into a surface of the printed circuit board.

18. The printed circuit board of claim 12 , wherein the acoustically-resistive air-permeable venting structure includes a channel formed by an etched alternating switchback pattern on a surface of the printed circuit board.

Assignees

• Motorola Solutions Inc

Inventors

• Miehl Andrew P
• Gruenhagen Deborah A
• Lee Gary A
• Meyer David J
• Mueller Karl F
• Arledge John Kevin

Classifications

• H04R1/086 Primary

  Protective screens, e.g. all weather or wind screens · CPC title

• H04R2499/11

  Transducers incorporated or for use in hand-held devices, e.g. mobile phones, PDA's, camera's · CPC title

• H05K1/181

  associated with surface mounted components · CPC title

• H04R1/08

  Mouthpieces; {Microphones;} Attachments therefor · CPC title

• H05K5/0213

  Venting apertures; Constructional details thereof · CPC title