Elastomer membrane enhanced electrostatic transducer

• US 4,885,783 A
• Filed: 04/10/1987
• Issued: 12/05/1989
• Est. Priority Date: 04/11/1986
• Status: Expired due to Term

• Current Assignee: Sound Cheers Limited
• Original Assignee: University of British Columbia
• Inventors: Clark, Robert L., Curzon, Francis L., Whitehead, Lorne A.
• Primary Examiner(s): Brigance, Gerald
• Assistant Examiner(s): OBERLEY, ALVIN E
• Application Number:
  US07/037,265
• Time in Patent Office: 970 Days
• Field of Search: 381/191, 381/190, 307/400, 361/312, 361/313, 361/323, 361/326
• US Class Current: 381/191
• CPC Class Codes: B06B 1/0292 Electrostatic transducers, e.g. electret-type
• CPC Class Codes: H04R 19/00 Electrostatic transducers

Abstract

A transducer having opposed first and second conductive plates for application of an electrical potential difference therebetween. An elastomeric dielectric material such as neoprene rubber is disposed between the plates and in contact therewith. The dielectric material has a plurality of pockets of approximate average depth "d" such that, for a given gas maintained within the pockets at a pressure "P", the product Pd is significantly less than the value required to achieve the minimum breakdown voltage for the gas in the pockets. Alternatively, the elastomeric dielectric material disposed between the plates may take the form of a plurality of strips or nodules which separate the plates by a distance "d" as above.

Claims

1. A transducer, comprising:

(a) opposed first and second conductive plates for application of an electrical potential therebetween; and

,

(b) an elastomeric dielectric material disposed between said plates and in contact therewith;

said dielectric material having a plurality of pockets of approximate average depth "d" such that, for a gas existing within said pockets at a pressure "P", the product Pd is significantly less than the value required to achieve the minimum breakdown voltage of said gas.

4. A transducer as defined in claim 1, 2 or 3, further comprising an electrical insulating material disposed between each of said plates and said elastomeric dielectric material.

5. A transducer as defined in claim 1, 2 or 3 wherein said gas is air, "P" is normal atmospheric pressure, and "d" is less than about 16 microns.

6. A transducer is defined in claim 1, 2 or 3 wherein said dielectric material is neoprene rubber.

7. A transducer as defined in claim 1, 2 or 3 wherein said gas is an electronegative gas, "P" is normal atmospheric pressure and "d" is less than about 10 microns.

8. A transducer as defined in claim 1, 2 or 3 wherein said gas is a mixture of electronegative and non-electronegative gases.

9. A transducer as defined in claim 1, 2 or 3 wherein said plates are formed of aluminized mylar.

10. A transducer as defined in claim 1, 2 or 3, wherein said dielectric material is disposed at a plurality of sites between said plates, leaving said gas between and in contact with said plates at regions other than said sites.

12. A transducer as defined in claim 1, 2 or 3, wherein said dielectric material is a composite structure of elastomeric and non-elastomeric material.

2. A transducer, comprising:

(a) opposed first and second conductive plates for application of an electrical potential therebetween; and

,

(b) an elastomeric dielectric material disposed between said plates and in contact therewith, for separating said plates by a distance "d" and for allowing a gas to exist between said plates at a pressure "P", wherein the product Pd is significantly less than the value required to achieve the minimum breakdown voltage of said gas.

11. A transducer as defined in claim 2 or 3, wherein:

(a) a first plurality of strips of elastomeric dielectric material are disposed between said plates in a first direction; and

,

(b) a second plurality of strips of elastomeric dielectric material are disposed between said plates in a second direction different than said first direction.

3. A transducer, comprising:

(a) a plurality of conductive plates arranged in a stack for application of an electrical potential between each pair of opposed plates comprising said stack; and

,

(b) an elastomeric dielectric material disposed between and in contact with each pair of opposed plates comprising said stack;

said dielectric material separating each of said pairs of opposed plates by a distance "d" and for allowing a gas to exist between said plates at a pressure "P", wherein the product Pd is significantly less than the value required to achieve the minimum breakdown voltage of said gas.