# US 8,569,640 B2 · Key switch structure

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- Number: US 8,569,640 B2
- Document ID: US8569640B2
- Status: Granted
- Kind: B2
- Application number: 12/737,434
- Filed: 2009-05-28
- Published: 2011-05-12
- Granted: 2013-10-29
- Earliest claimed: 2008-07-14
- Assignees: Oki Electric Industry Co., Ltd.
- Applicants: Shigeru Yamada; Yasushi Takagi
- Inventors: Shigeru Yamada; Yasushi Takagi
- Web page: https://patentgrep.com/patent/US8569640B2

## CPC

- H01H 3/125: {using a scissor mechanism as stabiliser}
- H01H 13/86: characterised by the casing, e.g. sealed casings or casings reducible in size
- H01H 2223/003: Membrane embracing all keys
- H01H 2229/028: Adhesive
- Y10T 29/49105: Switch making
- H01H: ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES (contact cables H01B7/10; electrolytic self-interrupters H01G9/18; emergency protective circuit arrangements H02H; switching by electronic means without contact-making H03K17/00)
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

A key switch structure is provided whose waterproofing property is improved without affecting a contact of a membrane sheet. The upper surfaces of the membrane sheet, the embossed part and the circumferential bend part of a back plate are formed on one and the same plane, and a thermal sheet is welded to those upper surfaces. The thermal sheet comprises a thermally meltable, adhesive sheet, which will be heated and pressed with heat rollers to be welded to the upper surfaces. The back plate has an air vent hole formed in its bottom portion.

## Claims

### Claim 1

A key switch structure for closing a contact provided in a membrane sheet in response to a key top being depressed, comprising:
a thermally weldable waterproof sheet disposed over said membrane sheet, said membrane sheet having a through hole cut therein; and
a back plate member disposed under said membrane sheet, said back plate member having an outer circumference part protruding toward said waterproof sheet and a fixing embossed part protruding toward said waterproof sheet and disposed at a position corresponding to the through hole to be fitted in the through hole;
said waterproof sheet being thermally welded to an upper surface of said membrane sheet, an upper surface of said embossed part and an upper surface of said outer circumference part.

### Claim 2 (depends on 1)

The key switch structure in accordance with claim 1, wherein the upper surface of said membrane sheet, the upper surface of said embossed part and the upper surface of said outer circumference part are located on a same plane.

### Claim 3 (depends on 1)

The key switch structure in accordance with claim 1, wherein said back plate member has an air vent hole formed in a position opposing said membrane sheet.

### Claim 4

A method for manufacturing a key switch structure for closing a contact provided in a membrane sheet in response to a key top being depressed, comprising:
forming a base part constituted of a thermally weldable waterproof sheet disposed over the membrane sheet and a back plate member, disposed under the membrane sheet and having a fixing embossed part protruding toward the waterproof sheet and an outer circumference part protruding toward the waterproof sheet, with the embossed part being fitted into a through hole cut in the membrane sheet and with the waterproof sheet opposing an upper surface of the membrane sheet, an upper surface of the embossed sheet and an upper surface of the outer circumference part; and
heating the base part so that the waterproof sheet is thermally welded to the upper surface of the membrane sheet, the upper surface of the embossed part and the upper surface of the outer circumference part.

### Claim 5 (depends on 4)

The method in accordance with claim 4, further comprising pressing a welding pin of a holder into the embossed part of the base part to which the waterproof sheet has been thermally welded.

### Claim 6 (depends on 1)

The key switch structure in accordance with claim 1, wherein said membrane sheet has an additional through hole cut therein, said back plate member having an additional fixing embossed part protruding toward said waterproof sheet and disposed at a position corresponding to the additional through hole, the through holes being arranged around a position corresponding to the contact.

### Claim 7 (depends on 4)

The method in accordance with claim 4, wherein the membrane sheet has an additional through hole cut therein, the back plate member having an additional fixing embossed part protruding toward the waterproof sheet and disposed at a position corresponding to the additional through hole, the through holes being arranged around a position corresponding to the contact.