Method for making area actuated switch

• US 4,724,605 A
• Filed: 07/08/1982
• Issued: 02/16/1988
• Est. Priority Date: 10/01/1980
• Status: Expired due to Term

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Fiorella, Charles M.
• Primary Examiner(s): Echols, P. W.
• Application Number:
  US06/396,506
• Time in Patent Office: 2,049 Days
• Field of Search: 29/622, 156/307.7, 156/216, 156/227, 200/5 R, 200/5 A, 200/86 R, 200/159 B, 200/292, 200/293, 200/302, 361/398
• US Class Current: 29/622
• 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 13/703 characterised by spacers between contact carrying layers
• CPC Class Codes: H01H 13/785 characterised by the material of the contacts, e.g. conductive polymers
• CPC Class Codes: H01H 2201/026 non precious
• CPC Class Codes: H01H 2211/006 Individual areas
• CPC Class Codes: H01H 2217/004 Larger or different actuating area
• CPC Class Codes: H01H 2227/024 Spacer elements
• CPC Class Codes: H01H 2229/002 Screen printing
• CPC Class Codes: H01H 2229/028 Adhesive
• CPC Class Codes: H01H 2229/038 Folding of flexible printed circuit
• CPC Class Codes: H01H 2231/01 Toy
• CPC Class Codes: Y10T 156/1034 Overedge bending of lamina about edges of sheetlike base
• CPC Class Codes: Y10T 156/1051 by folding
• CPC Class Codes: Y10T 29/49105 Switch making

Abstract

Disclosed is an area actuated switch which can be used, by way of example, in a keyboard for a calculator, learning aid or the like. An area actuated switch array is formed using two insulating sheets made of polyester or polycarbonate; the insulating sheets overlie one another such that one side of each sheet faces one another. Groups of spaced conductors formed on each of the facing sides also overlie one another, and selected conductors traverse the periphery of the keyboard. A plurality of raised, insulating spacer areas or points are positioned on the facing sides and are in registration and contact with each other. An insulating substrate is formed over the conductors traversing the periphery and this insulating substrate has substantially the same thickness as the spacer points such that the spacer points and the insulating substrate prevent the spaced conductors from making electrical contact. An adhesive coating, which may be heat or pressure sensitive, is applied to the spacer points and the insulating substrate to bond these two parts together. The bond created by the adhesive coating over the insulating substrate prevents contamination of the keyboard from dust, humidity and the like. The keyboard structure, therefore, may have an infinite active area such that when pressure is applied anywhere within the periphery of the switch array, electrical contact is made.

Claims

1. A method of manufacturing an area actuated switch assembly comprising the steps of:

(a) forming two conductive patterns, each on a portion of a flexible insulating substrate means, each pattern having at least two sets of evenly spaced, elongated conductors, the conductors of one set intersecting the conductors of a second set forming a plurality of surfaces on the substrate means defined by the intersecting conductors, the conductors of the one pattern being alignable with the conductors of the other pattern,

(b) forming a plurality of insulating spacer areas on said substrate means, at least one on each surface defined by the intersecting conductors of at least one conductive pattern,

(c) forming an adhesive over each of said spacer areas, and

(d) placing the substrate so that one conductive pattern overlies and faces the other conductive pattern, aligning the conductors of the one pattern with the conductors of the other pattern and contacting said insulating spacer areas of the one pattern with corresponding surfaces of the other pattern in proper registration to form said switch assembly.

2. The method of claim 1 wherein said conductive patterns are formed on the flexible substrate means by selectively screening a conductive material thereon.

3. The method of claim 1 wherein said insulating spacer areas are formed on said flexible substrate means by selectively screening an insulating material thereon.

4. The method of claim 3 further including the step of selectively screening said insulating material as a coating around the periphery of said assembly.

5. The method according to claim 4 wherein said forming an adhesive comprises selectively screening an adhesive on each of said spacer areas and on said insulating material on the periphery of said assembly.

6. The method of claim 5 wherein said adhesive is pressure sensitive.

7. The method of claim 5 wherein said adhesive is thermally activated.

8. The method of claim 4 further including the step of ultraviolet curing of said insulating material forming said spacer areas and coating around the periphery of said assembly.

9. The method of claim 4 wherein the height of said coating and said spacer areas are substantially equal.

10. The method of claim 1 wherein said contacting step comprises folding a portion of said substrate back onto itself to form said switch assembly.

11. The method according to claim 1 wherein said flexible insulating substrate means is a plastic material selected from the group of polyester, polycarbonate or polyamide plastics.

12. The method of claim 1 wherein said conductive patterns are in a star configuration and selected spacer areas are positioned generally in the center of said star.

13. The method of claim 1 wherein said conductive patterns are in a diamond configuration and selected spacer areas are positioned generally in the center of said diamond.

14. The method according to claim 1 wherein said spacer areas are generally circular in configuration.

15. The method of claim 1 including forming the insulating spacer areas on the surfaces of both the one pattern and the other pattern.