Lightguide having a directly secured reflector and method of making the same

• US 6,447,135 B1
• Filed: 10/08/1999
• Issued: 09/10/2002
• Est. Priority Date: 10/08/1999
• Status: Expired due to Term

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Kretman, Wade D., Epstein, Kenneth A., Gardiner, Mark E., Wortman, David L., Cobb, Sanford
• Primary Examiner(s): O'Shea, Sandra
• Assistant Examiner(s): Sawhney, Hargobind S.
• Application Number:
  US09/414,124
• Time in Patent Office: 1,068 Days
• Field of Search: 362/31, 362/326, 362/327, 362/330, 362/349
• US Class Current: 362/623
• CPC Class Codes: G02B 6/0038 Linear indentations or grooves, e.g. arc-shaped grooves or meandering grooves, extending over the full length or width of the light guide
• CPC Class Codes: G02B 6/0043 provided on the surface of the light guide
• CPC Class Codes: G02B 6/0055 Reflecting element, sheet or layer

Abstract

A lightguide includes an input edge surface, a back surface and an output surface. A reflector is directly secured to the back surface by, for example, adhesive bonding.

Claims

1. A lightguide comprising:

an optically transmissive monolith having an input edge, a back surface and an output surface; and

a reflector directly secured to the back surface by a patterned layer of adhesive, wherein the patterned layer of adhesive is arranged to extract light from the lightguide.

2. The lightguide of claim 1, wherein the reflector is laminated to the back surface.

3. The lightguide of claim 1, wherein the reflector comprises a substantially non-absorbing specular reflecting film.

4. The lightguide of claim 1, further comprising a diffuser formed in the output surface.

5. The lightguide of claim 4, wherein the diffuser comprises a plurality of programmed optical structures providing preselected differing amounts of optical power at preselected differing locations on the output surface.

6. The lightguide of claim 1, wherein the monolith includes diffusive particles distributed within a volume of the monolith.

7. The lightguide of claim 1, wherein the monolith comprises one of a slab, a wedge and a pseudo-wedge.

8. The lightguide of claim 1, wherein the patterned layer of adhesive comprises a dot pattern.

9. The lightguide of claim 1, wherein the adhesive is diffuse.

10. An illumination device comprising:

a light source including a light source reflector forming a light source cavity about the light source;

an optically transmissive monolith having an input edge, a back surface and an output surface, wherein the light source is disposed to provide light to the input edge; and

a reflector secured to the back surface by a patterned layer of adhesive.

11. The illumination device of claim 10, wherein the reflector comprises a substantially non-absorbing specular reflecting film.

12. The illumination device of claim 10, further comprising a diffuser formed in the output surface.

13. The illumination device of claim 12, wherein the diffuser comprises a plurality of programmed optical structures providing preselected differing amounts of optical power at preselected differing locations on the output surface.

14. The illumination device of claim 10, wherein the monolith includes diffusive particles distributed within a volume of the monolith.

16. The illumination device of claim 10, wherein the patterned layer of adhesive comprises a dot pattern.

17. The illumination device of claim 10, wherein the adhesive comprises a diffuse adhesive.

18. The illumination device of claim 10, further comprising a polarizer directly secured to the output surface.

19. The illumination device of claim 18, wherein the polarizer is secured by a continuous layer of adhesive.

20. The illumination device of claim 19, further comprising a polarization retarder disposed between the polarizer and the reflector.

15. The illumination device of claim wherein the monolith comprises one of a slab, a wedge and a pseudo-wedge.

21. method of making a lightguide comprising:

providing an optically transmissive monolith having an input edge, a back surface and an output surface;

providing a reflector, the reflector being sized to substantially cover the entire back surface;

disposing an adhesive in a distributed pattern having a density and a spacing of the adhesive on the back surface to provide substantially uniform extraction of light from the lightguide; and

bonding the reflector to the back surface using the adhesive.

22. The method of claim 21, wherein the reflector comprises a substantially non-absorbing specular reflecting film.

23. A lightguide comprising:

an optically transmissive monolith having an input edge, a back surface and an output surface; and

a polarizer directly secured to the output surface by a patterned layer of adhesive.

24. A lightguide comprising:

an optically transmissive monolith having an input edge, a back surface and an output surface; and

a polarizer directly secured to the output surface by a continuous layer of adhesive.