Electret transducer with variable effective air gap
US4429193A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 20, 1981 |
| Grant date | Jan 31, 1984 |
| Priority date | — |
| Expiry date | Nov 20, 2001 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T29/49226
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A directional electret transducer comprises an electret foil and a metalized backplate the effective air gap thickness therebetween varying according to a predetermined relationship. The sensitivity of the electret transducer is directly proportional to the effective air gap thickness. The effective air gap thickness is realized in three ways: first, a plurality of equal diameter holes are drilled to varying depths in the aforesaid backplate; second, a plurality of holes of varying diameters are drilled through the aforesaid backplate; third, a plurality of equal diameter holes are drilled through the aforesaid backplate, the density of the holes varying. In each of the aforesaid three ways, the variation is according to the predetermined relationship.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.