ELECTROLUMINESCENT SEMICONDUCTOR DISPLAY APPARATUS AND METHOD OF FABRICATING THE SAME

• US 3,780,357 A
• Filed: 02/16/1973
• Issued: 12/18/1973
• Est. Priority Date: 02/16/1973
• Status: Expired due to Term

• Current Assignee: Roland H. Haitz
• Original Assignee: Roland H. Haitz
• Inventors: Haitz, Roland H.
• Primary Examiner(s): Edlow, Martin H.
• Application Number:
  US05/333,431
• Time in Patent Office: 305 Days
• Field of Search: 317/235N,235R,234E 313/18D
• US Class Current: 257/100
• CPC Class Codes: G09F 9/33 being semiconductor devices, e.g. diodes
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 2933/0091 Scattering means in or on the semiconductor body or semiconductor body package H01L33/22 takes precedence
• CPC Class Codes: H01L 33/60 Reflective elements

Abstract

This electroluminescent semiconductor display apparatus utilizes a light-emitting semiconductor device surrounded by a molded white plastic body and transparent material containing scattering centers for diffusing the light emitted from the semiconductor over a large area. The light-emitting device is placed on a base material and a white plastic body is positioned about the device to provide a corridor for light from the device to the upper surface of the body. This pathway is filled with transparent material containing scattering centers, e.g., a mixture of epoxy and glass powder. Light emitted from the device passes up through the corridor diffusely reflecting from the sides of the body and being scattered by the diffusion centers in the transparent material. Thus, at the upper surface of the body, the corridor appears as an essentially uniformly illuminated surface. In the above described manner, a very intense, nearly point source of light emitted from an electroluminescent semiconductor device is diffused to less intense, more uniform illumination over a much larger surface of a display apparatus, thereby obviating the need for large-area light-emitting devices.

Claims

1. Electroluminescent semiconductor display apparatus comprising:

a base;

a body of material of selected thickness having upper and lower surfaces and having an opening passing through the body from said upper surface to said lower surface, said lower surface of the body being substantially contiguous with said base for forming a cavity within said opening which has a bottom formed by said base and has sides formed by walls of said opening, at least the sides of said cavity forming non-specularly reflective surfaces;

an electroluminescent semiconductor attached to the base at the bottom of the cavity;

optically transmissive material containing discrete particles for the scattering of light passing through said material, said material and discrete particles being disposed throughout the cavity; and

means for supplying electrical signals to the electroluminescent semiconductor.

2. Apparatus as in claim 1 wherein at least the sides of said cavity are formed of substantially white optically opaque material.

3. Apparatus as in claim 1 wherein at least the upper surface of the body in the region surrounding the opening is substantially absorptively opaque for absorbing light leaving the cavity through the body.

4. Apparatus as in claim 3 wherein:

the shape of the opening at the upper surface of the body is a first polygon having at least one length a and one width b;

the shape of the opening at the lower surface of the body is a second polygon having at least one length a and one width c, where c is not less than b; and

the centroid of the first polygon lies approximately above the centroid of the second polygon.

5. Apparatus as in claim 3 wherein:

the shape of the opening at the upper surface of the body is a first rectangle of length d and width e;

the shape of the opening at the lower surface of the body is a second rectangle of length f and width g, where f is less than d, and g is greater than e;

the shape of the opening at a selected intermediate location between the upper surface of the body and the lower surface of the body is a third rectangle of length f and width e;

the centroids of the first, second and third rectangles lie approximately on a straight line;

the four sides of the opening between the upper surface and the selected intermediate location are each planar; and

the four sides of the opening between the lower surface and the selected intermediate location are each planar.

6. Apparatus as in claim 3 wherein the lower surface of the body in the region surrounding the opening is substantially absorptively opaque for absorbing light in the region of said lower surface.

7. The method of forming semiconductor display apparatus having a plurality of selectively shaped apertures forming illuminatable regions, the method comprising the steps of:

forming a body including the selectively shaped apertures, each of which traverses the thickness of the body from viewing surface through the body to a rear surface thereof;

filling the cavities of said body with a heat-curable, optically transparent liquid filler material having optical scattering centers dispersed therethrough;

embedding a light source in the liquid filler material within the aperture from the rear surface of the body; and

curing said liquid filler material to a substantially solid state.

8. The method according to claim 7 wherein the steps of filling the apertures of the body include the additional steps of:

forming a liquid-impervious barrier across the aperture substantially flush with the viewing surface of the body;

exerting force on the liquid filler material to completely fill the apertures within the region between the viewing surface and the rear surface of said body; and

introducing a light source and connections therefor into the liquid filler material near the rear side surface of the body in line with an aperture.

9. The method as in claim 8 wherein the step of exerting force on the liquid filler material includes the step of:

introducing centrifugal force on the liquid filler material aligned substantially normal to the viewing surface in a direction from the rear surface of the body toward the viewing surface of said body.

10. The method as in claim 9 wherein said step of exerting force includes:

introducing centrifugal force on the liquid filler material in excess of 10 G'"'"''"'"'s.