Keyswitch with decoupling diode

• US 4,568,918 A
• Filed: 06/12/1984
• Issued: 02/04/1986
• Est. Priority Date: 06/29/1983
• Status: Expired due to Fees

• Current Assignee: Siemens AG
• Original Assignee: Siemens AG
• Inventors: Edel, Bernhard
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): NOT, DEFINED
• Application Number:
  US06/619,935
• Time in Patent Office: 602 Days
• Field of Search: 340/365 E, 340/815.13, 340/815.14, 340/815.12, 340/365 L, 340/365 R, 200/314, 200/159 R, 200/159 B, 200/5 A
• US Class Current: 341/24
• 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 2229/04 Solder problems
• CPC Class Codes: H01H 2239/02 Other elements in moving part
• CPC Class Codes: H03M 11/02 Details

Abstract

A keyswitch for use with keyboards for connecting intersecting row and column wires of a circuit board for the keyboard has a decoupling diode for preventing the generation of false signals which may prevent a clear identification of the keyswitch which has been activated upon the simultaneous actuation of several keyswitches. The decoupling diode is integrated in the movable contact bridge of the keyswitch so that no soldering need be undertaken on the circuit board for the keyboard.

Claims

1. In an actuator in a keyswitch formed by a keyboard having a matrix of intersecting row wires and column wires disposed on a circuit board, one said actuator being disposed at each point of intersection between a row wire and a column wire for making a connection therebetween upon depression of said actuator, said actuator having an elastomeric sheet with a contact bridge carried on an underside thereof for making an electrical connection between a row wire and a column wire upon actuation of said keyswitch, the improvement comprising:

a decoupling diode integrated in said contact bridge and disposed for making a series connection between said row wire and said column wire upon depression of said actuator for preventing generation of a false contact signal upon the simultaneous actuation of more than one actuator.

2. The improvement of claim 1 wherein said row wire has a contact pad associated therewith and said column wire has a contact pad associated therewith on said circuit board, said contact bridge having two contact surfaces respectively disposed above said contact pads, said contact surfaces being interconnected by said diode.

3. The improvement of claim 2 wherein said contact bridge is a monolithically integrated circuit and wherein said contact bridge is mounted on an insulating carrier plate.

4. The improvement of claim 2 wherein said contact surfaces each comprise a flat cubic member of conductive material having respective end faces in registry with said contact pads, said diode being a housing-free diode interconnected between said cubic members.

5. The improvement of claim 2 wherein said contact surfaces are semicircular in shape and are respectively mounted on spacers interconnecting said diode with axial connecting wires.

6. The improvement of claim 2 wherein said contact bridge has an insulating material plate having two oppositely disposed edges respectively surrounded by U-shaped contact bars, each contact bar having a lower leg forming said contact surfaces, and each contact bar having an upper leg connected to said diode, and wherein said diode is a diode of the type utilized in film circuits.

7. The improvement of claim 2 wherein said contact surfaces are two respective metal plates, said diode having axial connecting wires to which said metal plates are welded.