Keypad for portable telephone and manufacturing method thereof

• US 6,423,171 B1
• Filed: 12/22/1999
• Issued: 07/23/2002
• Est. Priority Date: 12/31/1998
• Status: Expired due to Fees

• Current Assignee: Youeal Electronics Co. Ltd.
• Original Assignee: Youeal Electronics Co. Ltd.
• Inventors: Yang, Yoon-Hong
• Primary Examiner(s): MAYES, MELVIN C
• Application Number:
  US09/470,272
• Time in Patent Office: 944 Days
• Field of Search: 156/277, 156/242, 156/245, 156/256, 156/267, 156/297, 200/512, 200/514, 264/132, 264/135, 264/153, 264/155, 264/156, 379/422
• US Class Current: 156/245
• CPC Class Codes: B29K 2083/005 LSR, i.e. liquid silicone rubbers, or derivatives thereof
• 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 2219/028 Printed information
• CPC Class Codes: H01H 2219/03 in transparent keyboard
• CPC Class Codes: H01H 2229/047 Preformed layer in mould
• CPC Class Codes: H01H 2231/022 Telephone handset
• CPC Class Codes: Y10T 156/1051 by folding
• CPC Class Codes: Y10T 156/1062 Prior to assembly
• CPC Class Codes: Y10T 156/108 Flash, trim or excess removal

Abstract

A keypad for a portable telephone and manufacturing method thereof is disclosed. The method comprises the steps of printing characters on a transparent, planar film; pre-forming the planar film through a pressing process such that the planar film has a predetermined shape including a plurality of depressions; punching slits in the pressed planar film around the depressions; filling liquid silicone rubber into the depressions of the pressed planar film; forming a keypad by pressing the silicon rubber in a metal mold so as to fabricate an integrated keypad in which keys are interconnected; and trimming an outer periphery of the formed keypad according to a predetermined keypad shape.

Claims

1. A method comprising:

printing characters on a film;

applying an adhesive on a rear side of the film;

pressing the film to form a pre-formed film, wherein the pressing is achieved through a pressing process forming a plurality of depressions in the film of a predetermined shape having a concave surface, wherein the adhesive forms an adhesive layer on the concave surface of the plurality of depressions;

punching slits in the pre-formed film around the plurality of depressions;

inserting the pre-formed film into a first metal mold having the same shape as the pre-formed film;

filling liquid silicone rubber into the plurality of depressions of the pre-formed film;

forming a keypad by providing a second metal mold over the first metal mold causing the silicone rubber to overflow from the plurality of depressions, and pressing the silicone rubber such that the silicone rubber and the pre-formed film are united, thereby fabricating an integrated keypad wherein keys are interconnected; and

trimming an outer periphery of the formed keypad according to a predetermined keypad shape after curing the silicone rubber.

2. The method of claim 1, wherein the film is a synthetic resin.