LIGHTGUIDE DESIGN TECHNIQUES

• US 20140064660A1
• Filed: 08/29/2012
• Published: 03/06/2014
• Est. Priority Date: 08/29/2012
• Status: Active Grant

• Current Assignee: OSRAM Sylvania Inc. (Ams-Osram AG)
• Original Assignee: OSRAM Sylvania Inc. (Ams-Osram AG)
• Inventors: Li, Ming, Yang, Yi, Olsen, Joseph A., Huang, Qiong
• Granted Patent: US 9,063,262 B2
• Time in Patent Office: Days
• US Class Current: 385/31
• 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 6/0068 Arrangements of plural sources, e.g. multi-colour light sources

Abstract

Techniques are disclosed for obtaining a desired luminance and/or intensity distribution from any lighting fixture that is illuminated by a lightguide. The techniques can be used, for instance, to design a non-uniform surface texture (e.g., of light extraction features) for a lightguide, wherein the surface texture achieves a desired uniform or an intentionally non-uniform luminance distribution for a given lightguide shape/geometry, dimensions, and/or composition. In some embodiments, an iteration algorithm with illuminance distribution feedback is utilized to design a non-uniform surface texture (e.g., geometry, dimensions, quantity and/or spatial distribution of light extraction features) to achieve the target luminance distribution for a given lighting application.

Claims

1. A lightguide device comprising:

an input surface configured to receive light from a light source; and

at least one surface having a surface texture comprising a plurality of light extraction features configured to direct incident light out of the lightguide device, wherein the surface texture is divided into a plurality of zones including a first and a second zone, the first zone having light extraction features configured differently than light extraction features of the second zone, such that light is extracted from the first zone differently than from the second zone due to the difference in their corresponding light extraction features.

2. The lightguide device of claim 1, wherein a density of the light extraction features of the first zone is different than a density of the light extraction features of the second zone.

3. The lightguide device of claim 1, wherein a composition of the light extraction features of the first zone is different from a composition of the light extraction features of the second zone.

4. The lightguide device of claim 1, wherein the light extraction features of the first zone are of a different size than the light extraction features of the second zone.

5. The lightguide device of claim 1, wherein the light extraction features of the first zone are of a different shape than the light extraction features of the second zone.

6. The lightguide device of claim 1 further comprising one or more additional zones of light extraction features each of which is configured uniquely with respect to the other zones.

7. The lightguide device of claim 1, wherein the plurality of zones provides a continuously varying light extraction pattern.

8. A method of designing a lightguide device comprising:

dividing a lightguide surface having an initial distribution of light extraction features into a plurality of zones including a first and a second zone; and

adjusting the light extraction features of the first zone differently than the light extraction features of the second zone, such that light will be extracted from the first zone differently than from the second zone due to the difference in their corresponding light extraction features.

9. The method of claim 8, wherein adjusting the light extraction features of the first zone differently than the light extraction features of the second zone comprises:

calculating a light distribution parameter for the first zone;

comparing the resultant calculated light distribution parameter for the first zone to a target light distribution parameter for the first zone; and

adjusting the light extraction features of the first zone until the light distribution parameter for the first zone is within a given tolerance of the target light distribution parameter for the first zone.

10. The method of claim 9, wherein the light distribution parameter comprises spatial and/or angular distribution of at least one of luminance, illuminance, luminous intensity, color, color temperature, and/or color rendering index (CRI).

11. The method of claim 9, wherein the light distribution parameter for the first zone is different than a light distribution parameter for the second zone.

12. The method of claim 9, wherein adjusting the light extraction features of the first zone differently than the light extraction features of the second zone further comprises:

increasing light extraction feature density for the first zone if the calculated light distribution parameter is lower than the target light distribution parameter for the first zone;

or

decreasing light extraction feature density for the first zone if the calculated light distribution parameter is higher than the target light distribution parameter for the first zone.

13. The method of claim 9 further comprising repeating the calculating, comparing, and adjusting for the second zone.

14. The method of claim 8, wherein a density of the light extraction features of the first zone is different than a density of the light extraction features of the second zone.

15. The method of claim 8, wherein a composition of the light extraction features of the first zone is different than a composition of the light extraction features of the second zone.

16. The method of claim 8, wherein the light extraction features of the first zone are of a different size than the light extraction features of the second zone.

17. The method of claim 8, wherein the light extraction features of the first zone are of a different shape than the light extraction features of the second zone.

18. The method of claim 8, wherein the plurality of zones further comprises one or more additional zones of light extraction features each of which is configured uniquely with respect to the other zones.

19. The method of claim 8, wherein the plurality of zones provides a continuously varying light extraction pattern.

20. A lighting device comprising:

one or more light sources configured to emit light; and

a lightguide comprising;

an input surface configured to receive light from the one or more light sources; and

at least one surface having a surface texture comprising a plurality of light extraction features configured to direct incident light out of the lightguide, wherein the surface texture is divided into a plurality of zones including a first and a second zone, the first zone having light extraction features configured differently than light extraction features of the second zone, such that light is extracted from the first zone differently than from the second zone due to the difference in their corresponding light extraction features.

21. The lighting device of claim 20, wherein the lighting device has an optical efficiency of greater than or equal to about 80%.

22. The lighting device of claim 20 further comprising a back reflector operatively coupled to the lightguide and configured to ensure that substantially all of the light received by the lightguide is directed out of a single output surface of the lightguide.

23. The method of claim 20, wherein the plurality of zones provides a continuously varying light extraction pattern.