LIGHT EMITTING DEVICE

• US 3,774,021 A
• Filed: 05/25/1972
• Issued: 11/20/1973
• Est. Priority Date: 05/25/1972
• Status: Expired due to Term

• Current Assignee: Bertrand Harold Johnson
• Original Assignee: Bertrand Harold Johnson
• Inventors: Johnson, Bertrand Harold
• Primary Examiner(s): Sheer, Richard M.
• Application Number:
  US05/256,800
• Time in Patent Office: 544 Days
• Field of Search: 240/1EL,2.1,2.17,41.1,8.16 313/18D,113
• US Class Current: 362/23.16
• CPC Class Codes: G02B 6/0018 Redirecting means on the surface of the light guide
• CPC Class Codes: G02B 6/002 by shaping at least a portion of the light guide, e.g. with collimating, focussing or diverging surfaces
• CPC Class Codes: G02B 6/0021 for housing at least a part of the light source, e.g. by forming holes or recesses
• CPC Class Codes: H01H 2219/062 Light conductor
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 25/0753 the devices being arranged next to each other
• CPC Class Codes: H01L 2924/00012 Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/181 Encapsulation
• CPC Class Codes: H01L 2924/1815 Shape
• CPC Class Codes: H01L 33/54 having a particular shape
• CPC Class Codes: Y10S 362/80 Light emitting diode

Abstract

A light emitting diode module with a dome encapsulant in which the geometry is designed to maximize the light output in the plane of the junction. The module is adapted to couple light into a planar light guide, such as a telephone dial faceplate, so that discrete remote regions of the faceplate can be illuminated. The objective generally is to illuminate several such regions with a lesser number of light emitting elements.

Claims

1. An illuminated faceplate in which a number of discrete regions of the faceplate are illuminated with light from a lesser number of light emitting elements comprising:

a substantially planar sheet of transparent plastic having a plurality of spaced-apart regions to be illuminated, the sheet having at least one approximately circular opening through its thickness, at least one light emitting device fitted within each opening of the sheet, each light emitting device comprising;

at least one light emitting diode, electrical leads for contacting the diode, a transparent plastic dome encapsulating the diode and a portion of the electrical leads while leaving a portion of the electrical leads exposed, the plastic dome having a peripheral geometry corresponding approximately to that of the opening in the sheet, and when inserted within the opening having a top surface exposed through the opening in the surface of the sheet, the top surface having a depression therein extending toward the light emitting diode to form an approximately conically shaped, internally reflecting surface with respect to the light emitting diode, the conically shaped surface having an apex angle such that all of the light incident on the dome except that essentially at the apex will be internally reflected and coupled into the sheet and the periphery of the plastic dome having a geometry with respect to the light emitting diode such that substantially all the light incident on the periphery is coupled into the sheet.

2. The faceplate of claim 1 in which the transparent plastic dome encapsulating the diode has a cylindrical shape with the depression formed into the top surface.

3. The faceplate of claim 1 in which the transparent plastic dome encapsulating the diode has the shape of a truncated cone with the depression formed into the top surface.

4. The faceplate of claim 1 in which the discrete regions of the faceplate to be illuminated comprise holes in the faceplate with pushbuttons extending through the holes.

5. The faceplate of claim 4 including two light emitting elements.

6. The faceplate of claim 5 having 12 holes arranged in a 3 X 4 matrix with the two light emitting elemEnts coupled to the sheet approximately at the center of the two squares formed by connecting nearest neighbors of the two middle rows of three holes in the matrix.

7. The illuminated faceplate of claim 1 in which the edges of the sheet are provided with re-entrant portions that internally reflect light incident on these portions and reduce light loss.