CAPACITIVE KEYSWITCH

• US 3,760,243 A
• Filed: 09/21/1972
• Issued: 09/18/1973
• Est. Priority Date: 09/21/1972
• Status: Expired due to Term

• Current Assignee: Donald C. Peroutky
• Original Assignee: Donald C. Peroutky
• Inventors: Peroutky, Donald C.
• Primary Examiner(s): Goldberg, E. A.
• Application Number:
  US05/290,831
• Time in Patent Office: 362 Days
• Field of Search: 317/249R 200/DIG.1,159R
• US Class Current: 200/600
• CPC Class Codes: H01G 5/12 due to rotation of part-cylindrical, conical, or spherical electrodes

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.

Claims

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.

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.

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.