The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jun. 05, 2001
Filed:
Apr. 18, 1997
California Institute of Technology, Pasadena, CA (US);
Abstract
A small, inexpensive, high quality electret formed by micro-machining technology on a support surface, and further including a small, inexpensive, high quality, 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 highly reliable, inexpensive microphone that can produce a signal without the need for external biasing, thereby reducing system volume and complexity. In the preferred embodiment, 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,C/m,to about 8×10,C/m,. Thermal annealing is used to stabilize the implanted charge. Two prototype micro-machined electret microphones have been fabricated and tested. An open circuit sensitivity of about 0.5 mV/Pa has been achieved for a hybrid microphone package.