Membrane keyboard

• US 4,639,559 A
• Filed: 05/07/1985
• Issued: 01/27/1987
• Est. Priority Date: 01/29/1982
• Status: Expired due to Term

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Taguchi, Toshimichi
• Primary Examiner(s): SCOTT, JAMES R
• Application Number:
  US06/731,273
• Time in Patent Office: 630 Days
• Field of Search: 200/5 A, 200/86 R, 200/159 B, 200/308
• 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 13/703 characterised by spacers between contact carrying layers
• CPC Class Codes: H01H 2211/022 for larger actuation area
• CPC Class Codes: H01H 2217/004 Larger or different actuating area
• CPC Class Codes: H01H 2231/012 Household appliance

Abstract

A membrane keyboard containing a larger size key pad label and a smaller size key pad labels; a pair of laminate sheets carry confronting conductor electrodes, each of the conductor electrodes being shaped to exactly follow the corresponding key pad label; and spacer sheet disposed between the pair of laminate sheets for electrically separating the confronting conductor electrodes. The spacer sheet is provided with a plurality of openings formed at positions corresponding to each of the conductor electrodes. The openings corresponding to the larger size key pad labels are divided into at least two sections through the use of, for example, a bridge layer extending across the opening, thereby uniforming the key actuation condition.

Claims

1. A membrane keyboard comprising:

a first flexible sheet having key pad lables formed thereon, said key pad labels including at least one larger size key pad label and at least one smaller size key pad label;

a second flexible sheet disposed below said first flexible sheet, said second flexible sheet carrying conductor electrodes formed on the rear surface thereof, each of said conductor electrodes having a size substantially identical to the corresponding key pad label formed on said first flexible sheet;

a third flexible sheet disposed below said second flexible sheet, said third flexible sheet carrying counter conductor electrodes formed on the front surface thereof, each of said counter conductor electrodes having a size substantially identical to the corresponding conductor electrode formed on the rear surface of said second flexible sheet;

a spacer sheet disposed between said second and third flexible sheets, said spacer sheet including;

large and small openings formed at positions corresponding to the conductor electrodes formed on the rear surface of said second flexible sheet, each of said openings having a size substantially identical to the corresponding conductor electrode; and

a partition bridge member integral with the spacer sheet and formed across the larger opening which corresponds to said larger size key pad label, said partition bridge member dividing the larger opening into two sections, whereby additional support provided for said second flexible sheet by said partition bridge member prevents an erroneous connection between the conductor electrodes and counter conductive electrodes;

and a reinforcing plate disposed below said third flexible sheet.