Light guide

• US 5,083,240 A
• Filed: 05/01/1991
• Issued: 01/21/1992
• Est. Priority Date: 08/24/1989
• Status: Expired due to Term

• Current Assignee: Nokia Corporation
• Original Assignee: Technophone Corporation (Nokia Corporation)
• Inventors: Pasco, Ian K.
• Primary Examiner(s): Husar, Stephen F.
• Application Number:
  US07/694,466
• Time in Patent Office: 265 Days
• Field of Search: 40/337, 40/546, 200/314, 200/317, 362/23, 362/24, 362/26, 362/27, 362/31, 362/95, 362/85
• US Class Current: 362/26
• CPC Class Codes: B60K 2360/139 Clusters of instrument input devices
• CPC Class Codes: B60K 2370/139 Clusters of input devices
• CPC Class Codes: B60K 35/10 Input arrangements, i.e. from user to vehicle, associated with vehicle functions or specially adapted therefor
• CPC Class Codes: G02B 6/003 Lens or lenticular sheet or layer
• CPC Class Codes: G02B 6/0055 Reflecting element, sheet or layer
• CPC Class Codes: G02B 6/006 to produce indicia, symbols, texts or the like
• CPC Class Codes: G02B 6/0095 Light guides as housings, housing portions, shelves, doors, tiles, windows, or the like
• CPC Class Codes: G09F 9/305 being the ends of optical fibres G09F9/302 takes precedence
• CPC Class Codes: H01H 13/70 having a plurality of operating members associated with different sets of contacts, e.g. keyboard mounting together a plurality of independent switches H02B
• CPC Class Codes: H01H 2219/062 Light conductor
• CPC Class Codes: H01H 2219/0622 only an illuminated ring around keys

Abstract

A light guide for illuminating a keyboard or keypad from behind comprises a transparent grid-like plate having an array of apertures in each of which is accommodated a respective key of the keyboard/keypad. Means are provided for reflecting light from an external source into the plan of the light guide. The individual apertures are surrounded by an upstanding rib formed integrally with the light guide. The top (outer) face of the rib is rendered optically imperfect to promote the escape of light thereform, thus providing an illuminated ring around each key.

Claims

1. A light guide for illuminating an information-bearing member, comprising a transparent plate having

at least one aperture associated with the information-bearing member,

means for reflecting light from an external light source into a plane of the plate, and

means for directing the light to provide an illuminated ring around a periphery of said at least one aperture, said means for directing comprises an integral protrusion around said periphery of said at least one aperture.

2. A light guide as claimed in claim 1, wherein the protrusion is in the form of an upstanding rib having a substantially flat top face remote from the plate, said top face being roughened to promote the escape of light therefrom.

3. A light guide as claimed in claim 1, wherein the protrusion is in the form of an upstanding rib having chamfered side faces.

4. A light guide as claimed in claim 1, wherein the protrusion is in the form of an upstanding rib having a substantially flat top face remote from the plate, said top surface being rendered optically imperfect to promote the escape of light therefrom.