Membrane switch assembly with improved spacer

• US 4,345,119 A
• Filed: 02/19/1981
• Issued: 08/17/1982
• Est. Priority Date: 02/19/1981
• Status: Expired due to Fees

• Current Assignee: EAC Technologies Corporation
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Latasiewicz, Leonard
• Primary Examiner(s): Truhe, J. V.
• Assistant Examiner(s): Ginsburg, Morris
• Application Number:
  US06/236,073
• Time in Patent Office: 544 Days
• Field of Search: 200/5 A, 200/159 B, 200/86 R, 428/158
• 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 2209/026 metallic
• CPC Class Codes: H01H 2213/012 Open-cell foam
• CPC Class Codes: H01H 2227/006 Spacer
• CPC Class Codes: H01H 2227/018 Printed contacts; Metal foil
• CPC Class Codes: H01H 2229/004 Conductive ink
• CPC Class Codes: H01H 2239/034 Environmental protection

Abstract

A resilient spacer for use in a membrane switch assembly is formed of an open-cell, non-reticulated foam felt layer, allowing air from the space between the upper and lower switch contacts to move into the foam material surrounding the contacts when a switch contact is made. The switch contacts remain protected from atmospheric contamination regardless of whether the assembly is edge sealed or not.

Claims

1. A membrane switch assembly comprising a flexible upper member bearing a plurality of contact areas on a first surface and a bottom member including at least one contact area on a first surface thereof and a foam felt spacer including a plurality of apertures in registration with at least the contact areas on the upper member, and wherein said spacer is adhesively attached to the first surface of the upper member, and to the first surface of the bottom member, and is composed of a resilient, non-conductive, open-cell, non-reticulated foam felt material.

2. A foam felt spacer according to claim 1 wherein the spacer material is a polyester urethane foam.

3. A foam felt spacer according to claim 1 wherein the spacer material has a density of approximately 12 pounds per cubic foot.

4. A foam felt spacer according to claim 1 wherein the range of open cell walls is between 20% and 30%.

5. A foam felt spacer according to claim 1 wherein the spacer material has substantially 80 cells per linear inch.