Solid state condenser and microphone devices
First Claim
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1. A solid state condenser device comprising:
- a backplate constituting a fixed electrode in a parallel plate condenser;
a diaphragm having a thickness, said diaphragm being sensitive to incident sound pressure waves, said diaphragm constituting a moveable electrode in said parallel plate condenser; and
means comprising a keeper, said keeper being formed of a thin-film dielectric and having a keeper gap to receive said diaphragm in operative positional relationship with said backplate, said keeper gap having a thickness greater than the thickness of said diaphragm to retain said diaphragm without physical attachment thereto, to avoid applying appreciable tension to said diaphragm.
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Abstract
A solid state miniature condenser and condenser microphone of good sensitivity is disclosed. The microphone comprises a fixed perforated backplate that constitutes a fixed electrode in a parallel plate condenser, a diaphragm sensitive to incident sound pressure waves that constitutes a moveable plate in the parallel plate condenser, keepers to position the diaphragm in relationship to the backplate without applying appreciable tension to the diaphragm, and FET circuitry which provides an output proportional to the change in capacitance of the condenser when the diaphragm moves in relationship to the backplate.
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Citations
22 Claims
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1. A solid state condenser device comprising:
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a backplate constituting a fixed electrode in a parallel plate condenser; a diaphragm having a thickness, said diaphragm being sensitive to incident sound pressure waves, said diaphragm constituting a moveable electrode in said parallel plate condenser; and means comprising a keeper, said keeper being formed of a thin-film dielectric and having a keeper gap to receive said diaphragm in operative positional relationship with said backplate, said keeper gap having a thickness greater than the thickness of said diaphragm to retain said diaphragm without physical attachment thereto, to avoid applying appreciable tension to said diaphragm. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A solid state condenser device comprising:
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a fixed backplate constituting a fixed electrode in a parallel plate condenser; a diaphragm having a thickness, said diaphragm being sensitive to incident sound pressure waves, said diaphragm constituting a moveable electrode in said parallel plate condenser; and means comprising a plurality of keepers, each of said keepers being formed of a thin-film dielectric and having a keeper gap to receive said diaphragm in operative positional relationship with said backplate, said keeper gap having a thickness greater than the thickness of said diaphragm to retain said diaphragm, without physical attachment thereto to avoid applying appreciable tension to said diaphragm. - View Dependent Claims (12, 13, 14, 15, 17)
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16. A solid state condenser device comprising:
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a fixed perforated backplate which constitutes a fixed electrode in a parallel plate condenser; a diaphragm sensitive to incident sound pressure waves which constitutes a moveable electrode in said parallel plate condenser; and means to retain said diaphragm in operative relation to said backplate without applying appreciable tension to said diaphragm, said retaining means comprising a plurality of keepers, each of said keepers being formed of a thin-film dielectric and having a keeper gap to receive said diaphragm, said keeper gap having a thickness greater than the thickness of said diaphragm to retain said diaphragm. - View Dependent Claims (18)
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19. A solid state condenser microphone device prepared on a single silicon wafer which comprises:
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a fixed perforated backplate, prepared from said silicon wafer, which constitutes a fixed electrode in a parallel plate condenser; a diaphragm sensitive to incident sound pressure waves which constitutes a moveable electrode in said parallel plate condenser; means to retain said diaphragm in operative relation to said backplate without applying appreciable tension to said diaphragm, wherein the diaphragm is retained in relation to said backplate by a plurality of thin-film dielectric keepers fixed to the backplate; and a Field Effect Transistor circuit electrically connected to said backplate and said diaphragm to provide an output when said diaphragm moves in relationship to said backplate. - View Dependent Claims (20, 21, 22)
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Specification