Electroacoustic transducer of the so-called "electret" type, and a method of making such a transducer
First Claim
1. An electroacoustic transducer comprisinga substrate of a semi-conductor material with a recessed portion;
- a membrane across said recessed portion, set in vibration in response to an input signal comprising sound frequencies;
a pair of electrodes forming a capacitor and between which an electric field is present, said substrate comprising one of the electrodes of said pair of electrodes, the electrodes being so arranged relatively to the membrane that the capacitance of the capacitor can vary under the influence of vibrations of the membrane, so that acoustic signals are converted into electric signals; and
a layer of an electrically insulating material functioning as a carrier for an electric charge providing an auxiliary electric field between the electrodes, the substrate having a peripheral edge which is raised relatively to said recessed portion, said peripheral edge having a set of openings formed therein, each extending through the substrate; and
attachment means extending through said openings to attach the membrane to said peripheral edge.
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Accused Products
Abstract
This invention provides an electroacoustic transducer and a method of making it. The transducer according to the invention comprises a substrate of a semiconductor material with a recessed portion. A membrane is stretched across the recessed portion, which membrane is set in vibration in response to an input signal comprising audio and/or ultrasonorous frequencies. A pair of electrodes is provided, which form a capacitor, and between which an electric field is present. The electrodes are so arranged relatively to the membrane that the capacitance of the capacitor can vary under the influence of vibrations of the membrane, so that acoustic signals are converted into electric signals. A layer of an electrically insulating material functions as a carrier for an electric charge to provide an auxiliary electric field between the electrodes. The transducer is characterized in that the peripheral edge of the substrate, which is raised relatively to the recessed portion, has a set of openings formed in it, each extending through the substrate. The membrane is attached through the openings to the peripheral edge.
118 Citations
5 Claims
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1. An electroacoustic transducer comprising
a substrate of a semi-conductor material with a recessed portion; -
a membrane across said recessed portion, set in vibration in response to an input signal comprising sound frequencies; a pair of electrodes forming a capacitor and between which an electric field is present, said substrate comprising one of the electrodes of said pair of electrodes, the electrodes being so arranged relatively to the membrane that the capacitance of the capacitor can vary under the influence of vibrations of the membrane, so that acoustic signals are converted into electric signals; and a layer of an electrically insulating material functioning as a carrier for an electric charge providing an auxiliary electric field between the electrodes, the substrate having a peripheral edge which is raised relatively to said recessed portion, said peripheral edge having a set of openings formed therein, each extending through the substrate; and
attachment means extending through said openings to attach the membrane to said peripheral edge. - View Dependent Claims (2, 3, 4, 5)
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Specification