Environmentally sealed variable capacitance apparatus
First Claim
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1. A key actuatable capacitive circuit board comprising:
- flexible dielectric sheet means having first and second parallel proximate portions each with first and second surfaces arranged so that the first surfaces are adjacent and the second surfaces are separated by at least the first and second portions;
first and second patterns of electrically conductive material on the first surface of the first portion of said sheet means and the second surface of the second portion of said sheet means respectively, selected portions of said first and second patterns being aligned in a direction perpendicular to the portions of said sheet means so as to form first and second plates of an array of capacitors;
first spacer means interposed between the first surfaces of the first and second portions of said sheet means so as to normally maintain a predetermined separation between the first surfaces, said spacer means being of a design which permits the spacing between the first and second plates of capacitors in the array to be varied; and
sealing means for sealing the first and second portions of said sheet means and said first spacer means together so as to prevent exposure of the spaces between the first and second capacitor plates to the environment surrounding said sheet means.
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Abstract
An environmentally sealed key actuatable capacitively coupled circuit board is disclosed comprising first and second flexible dielectric sheets having electrically conductive patterns thereon which form an array of capacitors and connecting matrix of conductors. A spacer is sealed between the sheets and the patterns on the sheets include a first array of capacitor plates on an inner surface of the first sheet and a second array of capacitor plates on the outer surface of the second sheet. A third array of floating capacitor plates is formed by a third pattern on the inner surface of the second sheet.
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Citations
23 Claims
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1. A key actuatable capacitive circuit board comprising:
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flexible dielectric sheet means having first and second parallel proximate portions each with first and second surfaces arranged so that the first surfaces are adjacent and the second surfaces are separated by at least the first and second portions; first and second patterns of electrically conductive material on the first surface of the first portion of said sheet means and the second surface of the second portion of said sheet means respectively, selected portions of said first and second patterns being aligned in a direction perpendicular to the portions of said sheet means so as to form first and second plates of an array of capacitors; first spacer means interposed between the first surfaces of the first and second portions of said sheet means so as to normally maintain a predetermined separation between the first surfaces, said spacer means being of a design which permits the spacing between the first and second plates of capacitors in the array to be varied; and sealing means for sealing the first and second portions of said sheet means and said first spacer means together so as to prevent exposure of the spaces between the first and second capacitor plates to the environment surrounding said sheet means. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method of fabricating a key actuatable capacitive circuit board comprising the steps of:
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providing a sheet of flexible dielectric material having first and second surfaces which when folded on itself forms a circuit board of double thickness having the size and shape desired for the circuit board; applying a first pattern of electrically conductive material to the first surface of said sheet within a first field covering less than one-half of the sheet, portions of the first pattern being configured to form first plates of an array of capacitors; applying a second pattern of electrically conductive material to the second surface of said sheet within a second field not overlapping the first field, portions of the second pattern being configured to form second plates of an array of capacitors having spacing substantially identical to the spacing of the first plates and being located so that when the sheet is folded on itself the first and second plates are aligned in a direction perpendicular to the sheet; folding the sheet on itself so that the first plates are aligned with the second plates in a direction perpendicular to the sheet; providing first spacer means between the portions of the sheet folded on itself, said spacer means being of a design which permits the spacing between corresponding first and second plates to be varied; sealing the portions of the sheet folded on itself and the spacer means together so as to prevent exposure of the spaces between the first and second capacitor plates to the environment surrounding the circuit board. - View Dependent Claims (12, 13)
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14. Capacitively coupled apparatus comprising:
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a first sheet of dielectric material having first and second electrically conductive areas on opposite surfaces thereof, at least portions of the conductive areas being aligned along a first axis perpendicular to the surfaces so as to form at least one fixed capacitor between corresponding conductive areas on opposite surfaces; a second flexible sheet of dielectric material having third electrically conductive areas on a first surface thereof, the conductive areas on said second sheet being arranged and said first and second sheets being positioned so that the first surfaces thereof are in a proximate spaced relationship and so that the conductive areas thereon are at least partially aligned along the first axis; spacer means located between the first surfaces of said first and second sheets so as to permit the spacing between corresponding conductive areas on the first surfaces to be varied, thereby forming at least one variable capacitor between conductive areas on the first surfaces of said first and second sheets; and
,sealing means including means for fixing said first and second sheets and said spacer means together so as to seal the first surfaces of said first and second sheets from exposure to the environment surrounding the sheets. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22)
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23. Environmentally sealed variable capacitance apparatus comprising:
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a first sheet of dielectric material of a predetermined thickness having first and second surfaces thereon; a first electrically conductive pattern formed on the first surface of said first sheet, at least a portion of said first pattern comprising a first capacitor plate; a second electrically conductive pattern formed on the second surface of said first sheet, at least a portion of said second pattern comprising a second capacitor plate which is electrically insulated from the remainder of said second pattern and located in at least partial alignment with the first capacitor plate in a direction perpendicular to the first and second surfaces of said first sheet so as to provide a first fixed capacitor between the first and second capacitor plates; a second flexible sheet of dielectric material having a first surface thereon; a third electrically conductive pattern formed on the first surface of said second sheet, at least a portion of the third pattern forming a third capacitor plate; and first spacer means interposed between the second surface of said first sheet of dielectric material and the first surface of said second sheet of dielectric material so as to normally maintain the surfaces in a spaced parallel relationship so that the portion of said third pattern forming the third capacitor plate is in at least partial alignment with the first and second capacitor plates in a direction perpendicular to the surfaces of said first and second sheets, said spacer means having apertures therethrough to permit the spacing between the second and third capacitor plates to be varied, the second surface of said first sheet, the first surface of said second sheet and said first spacer means being environmentally sealed together to prevent exposure of the surfaces to the environment surrounding said first and second sheets.
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Specification