CAPACITIVE KEYSWITCH
First Claim
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1. A variable capacitance keyswitch comprising:
- first and second fixed plates;
a moveable plate;
said fixed and moveable plates having a non-planar shape and nesting one in the other when the plates exhibit a high capacitance; and
actuating means, mechanically coupled to said moveable plate, for differentially varying the capacitance between said moveable plate and said first and second fixed plates.
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Abstract
A variable capacitance keyswitch is disclosed in which a differential capacitor is formed by two fixed plates and a moveable plate therebetween. Each plate is in the shape of the frustum of a cone. Depression of the pushkey varies the capacitance between each fixed plate and the moveable plate over a range of about one order of magnitude, or greater. In addition, depression of the pushkey provides a push-pull capacitance variation between fixed and moveable plates, achieving an electrical snap action effect useful in typical bistable flipflop circuitry.
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Citations
3 Claims
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1. A variable capacitance keyswitch comprising:
- first and second fixed plates;
a moveable plate;
said fixed and moveable plates having a non-planar shape and nesting one in the other when the plates exhibit a high capacitance; and
actuating means, mechanically coupled to said moveable plate, for differentially varying the capacitance between said moveable plate and said first and second fixed plates.
- first and second fixed plates;
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2. A variable capacitance keyswitch as set forth in claim 1 wherein said plates are in the shape of the surface of the frustum of a cone.
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3. A variable capacitance keyswitch comprising:
- a first fixed plate;
a second fixed plate;
a moveable plate positioned between said first and second fixed plates;
said first, second and moveable plate being in the shape of the frustum of a cone and capable of nesting one within the other;
shaft means connected to said moveable plate for nesting said moveable plate with either of said first or second fixed plates;
first and second electrical conductors connected to said first and second fixed plates respectively;
base means having three apertures and having said first fixed plate attached thereto;
cover means having the second fixed plate attached thereto and an aperture through which said shaft means moves;
said base means and said cover means defining a volume in which said moveable plate moves; and
electrically conductive resilient means connected to said moveable plate and connected to a third electrical conductor;
said first, second and third electrical conductors passing through said three apertures.
- a first fixed plate;
Specification