Illumination system employing an array of microprisms

• US 5,739,931 A
• Filed: 08/01/1996
• Issued: 04/14/1998
• Est. Priority Date: 01/11/1994
• Status: Expired due to Term

• Current Assignee: Advanced Display Technologies of Texas LLC (Advanced Display Technologies)
• Original Assignee: Alliedsignal Inc. (Honeywell International Inc.)
• Inventors: Schweyen, John C., Zimmerman, Scott M., Beeson, Karl W., Hou, Janpu
• Primary Examiner(s): Thomas, Tom
• Assistant Examiner(s): Abraham, Fetsum
• Application Number:
  US08/691,072
• Time in Patent Office: 621 Days
• Field of Search: 359/42, 359/48, 359/49, 359/69, 359/40
• US Class Current: 359/619
• CPC Class Codes: F21V 5/02 of prismatic shape F21V5/04 takes precedence
• CPC Class Codes: F21Y 2103/00 Elongate light sources, e.g. fluorescent tubes
• CPC Class Codes: G02B 6/0053 Prismatic sheet or layer; Brightness enhancement element, sheet or layer

Abstract

An optical illumination system comprising a waveguide that accepts light generated by a diffuse light source and transmits the light via total internal reflection. Attached on one face of the waveguide is an array of microprisms, with each microprism having an light input surface parallel to a light output surface and at least two sidewalls tilted at an angle from the direction normal to the surface of the waveguide such that light escapes from the waveguide, reflects off the tilted sidewalls and emerges from the microprism as a spatially directed light source. An array of microlenses may be positioned to accept the output of the microprisms so that the light exiting from the microlenses is a substantially collimated light source. The optical illumination system is advantageous for any application that requires a non diffuse or substantailly collimated that is both energy efficient and contained in a low profile assembly.

Claims

1. An illumination assembly comprising:

(a) a light transmitting means having at least one light accepting surface;

(b) reflecting means comprising an array of microprisms wherein at least one microprism comprises;

(i) a light input surface optically coupled to said light transmitting means;

(ii) a light output surface distal from said light input surface and having a surface area at least equal to the surface area of said light input surface;

(iii) a first pair of sidewalls disposed between said light input surface and said light output surface and at least one of said sidewalls forms a first tilt angle with respect to the normal of the surface of said light transmitting means; and

(iv) a second pair of sidewalls disposed between said light input surface and said light output surface and at least one of said sidewalls forms a second tilt angle with respect to the normal of the surface of said light transmitting means.

2. The illumination assembly of claim 1 wherein said light output surface is convex.

3. An illumination assembly comprising:

(a) a light transmitting means having means for accepting light;

(b) an array of microprisms wherein at least one microprism comprises;

(i) an input surface optically coupled to said light transmitting means for receiving a portion of light transmitting through said light transmitting means; and

(ii) at least one sidewall having an edge defined by said light input surface and positioned for effecting total internal reflection of a portion of light received by said light input surface.

4. An illumination assembly comprising:

(a) a light transmitting means for accepting light from a light source and causing light to transmit therethrough;

(b) an array of microprisms wherein each microprism comprises;

(i) a light input surface optically coupled to said light transmitting means for receiving a portion of light transmitting through said light transmitting means;

(ii) a first pair of sidewalls with each having an edge defined by said light input surface and at least one of said sidewalls is positioned for effecting total internal reflection of a portion of light received by said light input surface;

(iii) a second pair of sidewalls with each having an edge defined by said light input surface and at least one of said sidewalls is positioned for effecting total internal reflection of a portion of light received by said light input surface; and

(iv) a light output surface for transmitting light reflected by said sidewalls out of said microprism.

5. The illumination assembly of claim 4 further comprising an array of microlenses wherein at least one microlens is optically coupled to at least one of said light output surfaces.

6. The illumination assembly of claim 5 wherein said array of microprisms and array of microlenses are integrally formed.

7. An illumination assembly comprising:

(a) a light transmitting means having means for accepting light;

(b) an array of microprisms wherein each microprism comprises;

(i) a light input surface optically coupled to said light transmitting means;

(ii) a light output surface having a surface area greater than the surface area of said light input surface;

(ii) at least one sidewall having an edge defined by said light input surface and positioned for effecting total internal reflection of a portion of light received by said light input surface.

8. The illumination assembly of claim 7 wherein said output surface is concave.

9. The illumination assembly of claim 7 wherein said reflecting means further comprises an array of microlenses, wherein the light output of each microprism is directed to at least one corresponding microlens.

10. The illumination assembly of claim 9 wherein said array of microprisms and array of microlenses are integrally formed.

11. The illumination assembly of claim 7 wherein said output surface is parallel to said input surface.

12. An illumination assembly comprising:

(a) a light transmitting means;

(b) an array of microprisms wherein each microprism comprises;

(i) a light input surface optically coupled to said light transmitting means;

(ii) a concave-shaped light output surface distal from said light input surface;

(iii) a first pair of sidewalls with each sidewall having one edge defined by said light input surface and at least one of said sidewalls is positioned for effecting total internal reflection of light; and

(iv) a second pair of sidewalls with each sidewall having an edge defined by said light input surface and at least one of said sidewalls is positioned for effecting total internal reflection of light.