Low noise electret microphone

Abstract

An electret microphone having reduced noise due to reduced leakage current is provided. The microphone includes a flexible diaphragm, and sensor member disposed in opposing, spaced relation to the diaphragm and comprising a semi-conductor channel. At least one electret surface, comprised of a dielectric material having a permanently-embedded static electric charge, is disposed on one of the diaphragm and the sensor member. In turn, the semi-conductor channel of the sensor member has an electrical conductivity dependent upon relative movement of the diaphragm and support member responsive to acoustic signals incident upon the diaphragm, wherein the channel provides an output signal indicative of the acoustic signals. The electret surface may be disposed on the diaphragm. Alternatively, the electret surface may be disposed on the sensor member in spaced, face-to-face relation to an electrically conductive surface located on the diaphragm.

1 . An electret microphone comprising:
 a flexible diaphragm;   a sensor member disposed in opposing, spaced relation to said diaphragm and including a semi-conductor channel; and,   an electret surface, the electret surface being disposed on one of said diaphragm and said sensor member, wherein the channel of said sensor member has an electrical conductivity dependent upon relative movement of the diaphragm and sensor member responsive to acoustic signals incident upon said diaphragm, and wherein the channel provides an output signal indicative of the acoustic signals.   
     
     
         2 - 4 . (canceled) 
     
     
         5 . The electret microphone of  claim 1 , further comprising:
 a plurality of electret surfaces each having a permanently embedded static charge and being at least one of sized, located and differentially charged to weight predetermined frequency range components of said output signal.   
     
     
         6 . The electret microphone of  claim 1 , said sensor further comprising:
 a plurality of semi-conductor channel portions having corresponding outputs, wherein said outputs may be separately employed to weight predetermined frequency range components of said output signal.   
     
     
         7 . The electret microphone of  claim 1 , said sensor further comprising a hermetically-sealed, enclosed volume, wherein the diaphragm and sensor member define a space therebetween that is disposed between the enclosed volume. 
     
     
         8 - 10 . (canceled) 
     
     
         11 . The electret microphone of  claim 1 , further comprising a hermetically-sealed, enclosed volume, wherein the diaphragm and sensor member define an air-gap therebetween that is disposed in the enclosed volume. 
     
     
         12 . An electret microphone comprising:
 a first portion including a flexible diaphragm; and   a second portion including an electrical current channel, wherein   the electret microphone is configured to provide an output signal indicative of acoustic signals impinging upon the flexible diaphragm via interaction of components of the microphone, the interacting components forming a gateless transistor.   
     
     
         13 . The electret microphone of  claim 12 , wherein:
 the output signal is an output signal of the components forming the gateless transistor.   
     
     
         14 . The electret microphone of  claim 12 , further comprising:
 an electret surface comprising a dielectric material having a permanently-embedded static electric charge, said electret surface being a part of the first portion or the second portion, wherein the current channel is configured to have an electrical conductivity dependent upon relative movement of the first portion and second portion responsive to acoustic signals incident upon said diaphragm, and wherein the channel provides an output signal indicative of the acoustic signals, thereby forming the gateless transistor.   
     
     
         15 . The electret microphone of  claim 14 , wherein:
 the first portion does not contact the second portion.   
     
     
         16 . The electret microphone of  claim 14 , further comprising a sensor member, wherein the sensor member forms at least a portion of the electrical current channel. 
     
     
         17 . The electret microphone of  claim 16 , further comprising:
 an electret surface that is a part of the first portion or the second portion, wherein the channel of said sensor member has an electrical conductivity dependent upon relative movement of the first portion and second portion responsive to acoustic signals incident upon said diaphragm, and wherein the channel provides an output signal indicative of the acoustic signals, thereby forming the gateless transistor.   
     
     
         18 . The electret microphone of  claim 12 , wherein:
 the electret microphone is an implantable electret microphone.   
     
     
         19 . An electret microphone comprising:
 a first portion including a flexible diaphragm;   a second portion including a semi-conductor channel; and   an electret surface, said electret surface being a part of the first portion or the second portion, wherein   the electret microphone is configured such that deflection of the flexible diaphragm towards the sensor member results in a current output signal across the semi-conductor channel indicative of acoustic signals impinging upon the flexible diaphragm.   
     
     
         20 . The electret microphone of  claim 19 , wherein:
 the second portion includes a sensor member including the semi-conductor channel   
     
     
         21 . The electret microphone of  claim 19 , wherein:
 the electret surface comprises a dielectric material having a permanently-embedded static electric charge.   
     
     
         22 . The electret microphone of  claim 19 , wherein:
 the channel has an electrical conductivity dependent upon relative movement of the first portion and second portion responsive to acoustic signals incident upon said diaphragm; and   the channel provides an output signal indicative of the acoustic signals.   
     
     
         23 . The electret microphone of  claim 19 , wherein:
 the first portion does not contact the second portion.   
     
     
         24 . The electret microphone of  claim 19 , wherein:
 said channel defines a first surface portion of a sensor member; and   said electret surface is disposed on a second surface portion of the sensor member that is spaced from said first surface portion thereof.   
     
     
         25 . The electret microphone of  claim 19 , wherein:
 the channel and the electret surface form a gateless transistor, output of the gateless transistor corresponding to an output signal indicative of acoustic signals impinging upon the first portion.   
     
     
         26 . The electret microphone of  claim 1 , said sensor further comprising a housing, wherein the flexible diaphragm and the housing are configured to form a hermetically-sealed, enclosed volume bounded at least in part by the housing and the flexible diaphragm.