Thin film electret microphone
US6806593B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | May 15, 2001 |
| Grant date | Oct 19, 2004 |
| Priority date | — |
| Expiry date | May 31, 2021 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T29/49226
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An electret formed by micro-machining technology on a support surface, including a self-powered electret sound transducer, preferably in the form of a microphone, formed by micro-machining technology. Each microphone is manufactured as a two-piece unit, comprising a microphone membrane unit and a microphone back plate, at least one of which includes an electret formed by micro-machining technology. When juxtaposed, the two units form a microphone that can produce a signal without the need for external biasing, thereby reducing system volume and complexity. The electret material used is a thin film of spin-on polytetrafluoroethylene (PTFE). An electron gun preferably is used for charge implantation. The electret has a saturated charged density in the range of about 2×10−5 C/m2 to about 8×10−4 C/m2. Thermal annealing is used to stabilize the implanted charge. An open circuit sensitivity of about 0.5 mV/Pa has been achieved for a hybrid microphone package.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.