Blacklight with structured surfaces

• US 7,046,905 B1
• Filed: 07/11/2000
• Issued: 05/16/2006
• 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., Gardiner, Mark E., Cobb, Sanford
• Primary Examiner(s): Smith, Zandra V.
• Assistant Examiner(s): Valentin, II, Juan D
• Application Number:
  US09/613,313
• Time in Patent Office: 2,135 Days
• Field of Search: 361/33, 361/31, 361/330, 361/333, 361/336, 361/337, 385/146
• US Class Current: 385/146
• CPC Class Codes: G02B 6/0001 specially adapted for lighting devices or systems lighting or signalling on vehicles using light guides B60Q1/00; lighting devices for vehicle dashboards B60Q3/10; lighting devices for vehicle interior using light guides B60Q3/62; lighting devices mounted on the vehicle rear part using light guides F21S43/235; measuring arrangements having light conducting pointers G01D13/265; illumination of liquid crystal displays G02F1/1336; illuminated signs G09F13/00
• CPC Class Codes: G02B 6/0036 2-D arrangement of prisms, protrusions, indentations or roughened surfaces
• 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 6/0046 Tapered light guide, e.g. wedge-shaped light guide
• CPC Class Codes: G02B 6/0055 Reflecting element, sheet or layer
• CPC Class Codes: G02B 6/0061 to provide homogeneous light output intensity
• CPC Class Codes: Y10S 385/901 Illuminating or display apparatus

Abstract

A backlight includes a lightguide, a light source disposed with respect to the lightguide to introduce light into the lightguide and a turning film. Optical structures are formed in one of an output surface and a back surface of the lightguide. The optical structures are arranged to extract light from the lightguide. A back reflector is disposed adjacent the back surface. The optical structures are formed to include a varying pattern arranged to mask non-uniformities in the output of the lightguide.

Claims

1. A lightguide comprising:

a first surface;

a second surface opposing the first surface;

an input edge surface extending between the first surface and the second surface;

a plurality of prism grooves formed in the first surface, the prism grooves each having a groove axis and each groove axis being substantially parallel to each other groove axis, wherein the groove axes are arranged to be disposed substantially perpendicular to the input edge surface; and

each of the plurality of prism grooves having a characteristic affecting the optical properties of the prism groove, the characteristic at least being one of amplitude, aspect ratio and pitch of the prism groove, and the characteristic varying as a function of the location along the groove axis extending from the input edge surface.

2. The lightguide of claim 1, wherein variation in the characteristic of adjacent prism grooves is one of in-phase and out-of-phase.

3. The lightguide of claim 1, wherein the characteristic is arranged to have a greater value along the groove axis at a location arranged to be nearer the input edge surface.

4. The lightguide of claim 1, wherein the characteristic comprises discrete variations of the characteristic along the length of the groove axis.

5. The lightguide of claim 1, wherein the comprises comprise continuous variations of the characteristic along the length of the groove axis.

6. The lightguide of claim 1, wherein the characteristic is related to the optical power of the prism groove and the optical power tapers from a first value to a second value, lesser than the first value along the groove axis from a location on the groove axis arranged to be nearer the input edge to a location on the groove axis arranged to be farther from the input edge.

7. The lightguide of claim 1, comprising optical structures formed in the second surface.

8. A lightguide comprising a surface, a first edge and an opposing second edge, grooves formed in the surface extending from the first edge to the second edge, each groove having a groove axis and the groove axes being substantially aligned, each groove having a characteristic, the characteristic affecting the optical power to the groove, and the characteristic varying along the groove as a function of the location on the groove between the first edge and the second edge, wherein the characteristic is arranged to have a greater value along the groove axis at a location arranged to be nearer the first edge.

9. The lightguide of claim 8, comprising optical structures formed in the second surface.

10. The lightguide of claim 8, wherein the characteristic comprises one of the group of characteristics comprising:

amplitude, pitch and aspect ratio.

11. The lightguide of claim 8, wherein the characteristic comprises amplitude, and wherein the amplitude varies along the groove axis.

12. The lightguide of claim 8, wherein variation in the characteristic of adjacent prism grooves is one of in-phase and out-of-phase.

13. The lightguide of claim 8, wherein the optical power is arranged to be greater along the groove axis at a location arranged to be nearer the input edge surface.

14. The lightguide of claim 8, wherein the characteristic varies discretely along a length of the groove axis.

15. The lightguide of claim 8, wherein the characteristic varies continuously along a length of the groove axis.

16. The lightguide of claim 8, wherein the optical power tapers from a first value to a second, lesser than the first value along the groove axis from a location on the groove axis arranged to be nearer the input edge to a location on the groove axis arranged to be farther from the input edge.

17. A lightguide comprising:

an input edge and a second edge opposing the input edge, a first surface and a second surface;

grooves formed in each of the first surface and the second surface extending from the input edge to the second edge, each groove having a groove axis and the groove axes being substantially aligned, each of the grooves having a characteristic affecting optical power of the groove, and the varying along the groove as a function of the location along the groove between the input edge and the second edge; and

wherein the characteristic is arranged to have a greater value along the groove axis at a location arranged to be nearer the input edge.

18. The lightguide of claim 17, wherein the characteristic comprises one of the group of characteristics comprising:

amplitude, pitch and aspect ratio.

19. The lightguide of claim 17, wherein the characteristic comprises amplitude, and wherein the amplitude varies along the groove axis.

20. The lightguide of claim 17, wherein variation of the characteristic of adjacent prism grooves is one of in-phase and out-of-phase.

21. The lightguide of claim 17, wherein the characteristic is arranged to have a greater affect on optical power at a location along the groove nearer the input edge surface.

22. The lightguide of claim 17, wherein the characteristic varies discretely along a length of the groove axis.

23. The lightguide of claim 17, wherein the characteristic varies continuously along a length of the groove axis.

24. The lightguide of claim 17, wherein the optical power tapers from a first value to a second, lesser than the first value along the groove axis from a location on the groove axis arranged to be nearer the input edge to a location on the groove axis arranged to be farther from the input edge.