Transparent capacitance membrane switch

• US 4,431,882 A
• Filed: 08/12/1982
• Issued: 02/14/1984
• Est. Priority Date: 08/12/1982
• Status: Expired due to Fees

• Current Assignee: W H Brady Company
• Original Assignee: W H Brady Company
• Inventors: Frame, Norman J.
• Primary Examiner(s): Scott, J. R.
• Application Number:
  US06/407,450
• Time in Patent Office: 551 Days
• Field of Search: 200/5 R, 200/5 A, 200/159 B, 200/DIG. 1, 361/416, 361/322, 340/365 B, 340/365 S, 340/365 A, 340/365 C, 178/17 C
• 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 2201/028 Indium tin oxide [ITO]
• CPC Class Codes: H01H 2219/03 in transparent keyboard
• CPC Class Codes: H01H 2227/006 Spacer
• CPC Class Codes: H01H 2227/018 Printed contacts; Metal foil
• CPC Class Codes: H01H 2229/012 Vacuum deposition
• CPC Class Codes: H01H 2239/006 Containing a capacitive switch or usable as such
• CPC Class Codes: H01H 2239/01 combined with other elements on the same substrate

Abstract

A more transparent capacitance membrane switch in which capacitance elements are offset from their associated switch locations so as to be out of the transparent field of view through the switch.

Claims

1. A capacitance membrane switch, comprising

a substrate supporting a first contact portion,

a flexible membrane supporting a second contact portion aligned over said first contact portion,

means for spacing said membrane from said substrate in the absence of an actuating force on said flexible membrane,

said first and second contact portions, substrate, flexible layer, and means for spacing being together at least partially transparent to light travelling therethrough, thereby defining a zone of transparency surrounding and including said contact portions, and

a capacitance element electrically connected to one of said first and second contact portions, said capacitance element being offset from said contact portions so as to be located outside said zone of transparency.

2. The switch of claim 1 wherein said capacitance element comprises

a first vacuum-deposited conductive film,

a dielectric film vacuum-deposited over at least a portion of said first conductive film, and

a second conductive film vacuum-deposited over at least a portion of said dielectric film and first conductive film so as to form a capacitive region in which all three films overlap, and

wherein said first contact portion is integral with or electrically connected to one of said first and second conductive films.

3. The switch of claim 2 wherein said first and second contact portions are vacuum-deposited thin films.

4. The switch of claim 2 wherein there are a plurality of said first and second portions forming a plurality of switch locations, said zone of transparency surrounding all of said plurality, and there are a plurality of said capacitance elements each electrically connected with one or more of said first or second contact portions, all of said capacitance elements being located outside said zone of transparency.

5. The switch of claim 4 wherein

said first contact portions are elongated, vacuum-deposited, conductive films arranged in spaced-apart rows,

said second contact portions are elongated, vacuum-deposited, conductive films arranged in spaced-apart columns transverse to said rows, and

said capacitance elements reside on said substrate and each is connected with one of said first contact portions.

6. The switch of claim 5 wherein each said first contact portion and one of said conductive films of each said capacitance element are integral extensions of the same vacuum-deposited, conductive film.

7. The switch of claim 2 wherein said substrate is the face of a visual display.