Wave guide for improving light sensor angular response

Patent metadata

Field	Value
Publication number	US-9041698-B2
Application number	US-201213654998-A
Country	US
Kind code	B2
Filing date	Oct 18, 2012
Priority date	Jun 29, 2009
Publication date	May 26, 2015
Grant date	May 26, 2015

Abstract

Electronic displays encounter visibility issues due to varying ambient light conditions. An ambient light sensor can be provided to sense ambient light and dynamically adjust display brightness to compensate for changes in ambient light. A wave guide for improving angular response in a light sensor is provided.

First claim

The invention claimed is:

1. A light sensor module comprising:
a window for transmitting ambient light;
a light sensor for receiving said ambient light;
a wave guide comprising a textured surface disposed between said window and said light sensor;
said textured surface having a geometric structure;
said geometric structure configured according to a material and a thicknesses of said window; and
said geometric structure further configured to guide said ambient light travelling through said window onto said light sensor such that an intensity of said ambient light that strikes said light sensor varies substantially proportionally according to a function comprising a cosine of an angle of incidence of ambient light striking said window.

2. The light sensor module of claim 1 , wherein said geometric structure is further configured such that said ambient light strikes said light sensor at an angle that is substantially normal to said light sensor regardless of said angle of incidence.

3. The light sensor module of claim 1 , further comprising a substrate; said textured surface applied to said substrate; said substrate for mechanically affixing said wave guide to said window.

4. The light sensor module of claim 3 , wherein said substrate is affixed via an adhesive.

5. The light sensor module of claim 3 , wherein said geometric structure is further configured according to a material and thickness of said substrate.

6. The light sensor module of claim 1 , wherein said textured surface is integrally formed into said window.

7. The light sensor module of claim 1 , wherein said textured surface comprises a plurality of bosses.

8. The light sensor module of claim 7 , wherein said bosses are trapeziums, partial-spheroids or four-sided pyramids.

9. The light sensor module of claim 7 , wherein the bosses are spaced either regularly or irregularly.

10. The light sensor module of claim 1 , wherein said textured surface is made from one of polymethyl methacrylate, polyethylene terephthalate, acrylic, or epoxy.

11. A wave guide comprising:
a textured surface for positioning between a window and a light sensor;
said textured surface having a geometric structure;
said geometric structure configured according to a material and a thicknesses of said window; and
said geometric structure further configured to guide ambient light travelling through said window onto said light sensor such that an intensity of ambient light that strikes said sensor varies substantially proportionally according to a function comprising a cosine of an angle of incidence of ambient light striking said window.

12. The wave guide of claim 11 , wherein said geometric structure is further configured such that said ambient light strikes said light sensor at an angle that is substantially normal to said light sensor regardless of said angle of incidence.

13. The wave guide of claim 11 , further comprising a substrate; said textured surface applied to said substrate; said substrate for mechanically affixing said wave guide to said window.

14. The wave guide of claim 13 , wherein said substrate is affixed via an adhesive.

15. The wave guide of claim 13 , wherein said geometric structure is further configured according to a material and thickness of said substrate.

16. The wave guide of claim 11 , wherein said textured surface is integrally formed into said window.

17. The wave guide of claim 11 , wherein said textured surface comprises a plurality of bosses.

18. The wave guide of claim 17 , wherein said bosses are trapeziums, partial-spheroids or four-sided pyramids.

19. The wave guide of claim 17 , wherein the bosses are spaced either regularly or irregularly.

20. The wave guide of claim 11 , wherein said textured surface is made from one of polymethyl methacrylate, polyethylene terephthalate, acrylic, or epoxy.

Assignees

• Research In Motion Ltd
• Blackberry Ltd

Inventors

• Lee Hsin Chin
• Broga Matthew

Classifications

• G01J2001/0485

  Cosinus correcting or purposely modifying the angular response of a light sensor · CPC title

• G01J1/4204

  with determination of ambient light (solar light G01J2001/4266) · CPC title

• G01J1/0407

  Optical elements not provided otherwise, e.g. manifolds, windows, holograms, gratings · CPC title

• G01J1/04

  Optical or mechanical part {supplementary adjustable parts} · CPC title

• G09G2320/0626

  for control of overall brightness · CPC title