Electret microphone shield
US4424419A · kind A · utility
24Cited by
2References
9Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Oct 19, 1981 |
| Grant date | Jan 3, 1984 |
| Priority date | — |
| Expiry date | Oct 19, 2001 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04R19/01
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An electret microphone has a metal shield around it in order to guard against electromagnetic interference. Acoustic waves reach the electret element through a passage in the shield. The electret response is undesirably affected by an electric field produced by body capacitance when the microphone is brought close to a user's mouth. To overcome this effect, the microphone has a conductive film, transparent to acoustic waves, positioned between the passage and the electret element, the film contacting a grounded part of the casing. The conductive film can form an integral part of a microphone moisture barrier.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.