Keyboard switch

• US 4,652,704 A
• Filed: 12/30/1985
• Issued: 03/24/1987
• Est. Priority Date: 12/30/1985
• Status: Expired due to Term

• Current Assignee: Honeywell Incorporated (Honeywell International Inc.)
• Original Assignee: Sperry Corporation
• Inventors: Franklin, Gerald K.
• Primary Examiner(s): Scott, J. R.
• Application Number:
  US06/814,456
• Time in Patent Office: 449 Days
• Field of Search: 200/5 A, 200/159 B, 200/292, 200/11 DA
• US Class Current: 200/5.00A
• CPC Class Codes: H01H 13/702 with contacts carried by or formed from layers in a multilayer structure, e.g. membrane switches
• CPC Class Codes: H01H 13/785 characterised by the material of the contacts, e.g. conductive polymers
• CPC Class Codes: H01H 13/807 characterised by the spatial arrangement of the contact sites, e.g. superimposed sites
• CPC Class Codes: H01H 2201/032 Conductive polymer; Rubber
• CPC Class Codes: H01H 2203/02 Interspersed fingers
• CPC Class Codes: H01H 2203/054 for redundancy, e.g. several contact pairs in parallel
• CPC Class Codes: H01H 2225/01 Different switch sites under one actuator in same plane

Abstract

An improved multiple circuit keypad switch of the type in which a rigid key having a shorting puck on its underside is supported over exposed traces of a printed circuit card by a flexible membrane so that the puck shorts designated exposed traces to close all circuits when the key is depressed, the improvement arising from the layout of the exposed traces in which individual circuits are arranged in concentric rings and the shorting puck contains shorting elements arranged in corresponding concentric rings.

Claims

1. In a keypad switch of the type including a key having shorting pucks on its underside and supported above exposed trace patterns on a printed circuit card by a flexible membrane whereby pressure on the key collapses the membrane and permits the shorting pucks to contact with the exposed trace patterns thereby closing the switch, the improvement wherein said shorting pucks include a central circuit puck electrically isolated from an annular puck thereabout, said annular puck being co-planar and concentric with said circular puck, and wherein said exposed trace patterns are formed in a circular region and an annular region co-planar and concentric with said circular region, exposed trace patterns in said circular region being electrically isolated from trace patterns in said annular region, said circular region and said annular region being correspondingly aligned with said circular puck and said annular puck.

2. The switch of claim 1 wherein said exposed trace patterns include a plurality of electrically isolated exposed trace elements each having a switch terminal.

3. The switch of claim 2 wherein said exposed trace pattern in said circular region includes two trace elements formed along a circumferential border of said circular region, said two exposed trace elements each including a plurality of exposed trace fingers being further arranged so that said exposed trace fingers coupled to one of said two exposed trace elements are interposed between said exposed trace fingers coupled to the other of said two exposed trace elements, a third exposed trace element comprising electrically connected segments interposed between said exposed trace fingers of said two exposed trace elements and extending continuously in said circular region in a zigzag fashion.

4. The switch of claim 3 wherein said exposed trace fingers of said two exposed trace elements and said segments of said third exposed trace element are arranged to be a parallel relationship.

5. The switch of claim 2 wherein said plurality of exposed trace elements of said annular region includes a first trace element formed along an inner circumferential border of said annular region, a second exposed trace element formed along an outer circumferential border of said annular region, and a third exposed trace element extending in a continuous, undulating manner in said annular region between said first and second trace elements, said first and second trace elements further including exposed trace fingers alternately positioned in an interleaved manner in said annular region and said third trace element having electrically connected segments interposed between said exposed trace fingers of said first and second trace elements.

6. The switch of claim 5 wherein said exposed trace fingers of said first and second exposed trace elements and said segments of said third exposed trace element extend along radials of said annular region.