Lighted telephone dial

• US 4,349,705 A
• Filed: 05/06/1981
• Issued: 09/14/1982
• Est. Priority Date: 05/06/1981
• Status: Expired due to Term

• Current Assignee: Nortel Networks Limited (Nortel Networks Corporation)
• Original Assignee: Northern Telecom Limited (Nortel Networks Corporation)
• Inventors: Kuhfus, Gerd
• Primary Examiner(s): Brigance, Gerald L.
• Application Number:
  US06/260,889
• Time in Patent Office: 496 Days
• Field of Search: 179/90 L, 179/81 C, 179/84 L, 179/178, 340/365 R, 200/310, 200/313, 200/314, 200/317, 362/24, 362/30, 362/84
• US Class Current: 379/361
• CPC Class Codes: G02B 6/0018 Redirecting means on the surface of the light guide
• CPC Class Codes: G02B 6/0068 Arrangements of plural sources, e.g. multi-colour light sources
• CPC Class Codes: G02B 6/0073 Light emitting diode [LED]
• CPC Class Codes: H01H 2219/044 Edge lighting of layer
• CPC Class Codes: H01H 2219/062 Light conductor
• CPC Class Codes: H04M 1/22 Illumination; Arrangements for improving the visibility of characters on dials

Abstract

A pushbutton dial having pushbuttons arranged in three columns and four rows has the buttons illuminated by four LED'"'"'s positioned in a light-guide plate having apertures which surround the pushbuttons. The LED'"'"'s are in recesses at intersections of the outer columns and top and bottom rows, each recess between four adjacent apertures. Guide grooves at the edges of the plate redirect light issuing from the LED'"'"'s and passing between apertures. The plate is transparent and the buttons translucent, the buttons being illuminated from all round their peripheries.

Claims

1. A light telephone dial of the pushbutton type, comprising;

a printed circuit board having a conductor pattern on a top surface of the board, the conductor pattern defining a plurality of switch positions, each position having a plurality of contact areas;

a switch member on said printed circuit board and having a plurality of switches, a switch aligned with each of said switch positions, each switch having a plurality of cantilever contacts members, a member aligned with each contact area;

a pushbutton member on said switch member and having a plurality of translucent cantilevered pushbuttons, a button aligned with each switch, the switch positions, switches and buttons arranged in four rows and three columns;

a translucent light guide plate positioned over said pushbutton member and having a plurality of apertures, an aperture for each pushbutton, the pushbuttons extending up through the apertures;

four recesses in a lower surface of the light guide plate, a recess at each intersection between a top row and the columns and between a bottom row and the columns, each recess positioned between four adjacent apertures;

grooves in the lower surface of the light guide plate, one along each of the top and bottom edges and at least one along each of the side edges, projections in the grooves extending in towards the spaces between rows and columns and having rearwardly inclined inner surfaces to present pointed ends towards said recesses, outwardly and rearwardly inclined surfaces behind said projections, an inclined surface on each side of a center line through a said pointed end, and further portions extending from said inclined surfaces parallel to said edges;

a light emitting diode positioned in each of said recesses, and means for supplying electrical power to the diodes;

the arrangement such that light from the diodes travels through the light-guide plate, part of the light transferred directly from the plate to the pushbuttons, that part of the light passing between apertures entering said grooves in said light-guide plate and being deflected sideways along the grooves and re-entering the light-guide plate to transfer to the pushbuttons, the pushbuttons illuminated on all sides.

2. A dial as claimed in claim 1, including further recesses in the lower surface of the light-guide plate, a recess between each pair of recesses and of approximately square plan form.

3. A dial as claimed in claim 1, including two grooves at each side edge, each groove having a projection extending towards a recess.

4. A dial as claimed in claim 3, including a single groove at top and bottom edges, each groove having two spaced apart projections, each projection extending towards a recess.

5. A dial as claimed in claim 1, including an opaque bezel positioned over said light-guide plate, said bezel including a plurality of apertures, an aperture for each pushbutton.

6. A dial as claimed in claim 1, said means for supplying electrical power to the diodes comprising a lead frame positioned between said light-guide plate and said pushbutton member.