Wave guide for improving light sensor angular response

• US 8,319,764 B2
• Filed: 06/29/2009
• Issued: 11/27/2012
• Est. Priority Date: 06/29/2009
• Status: Active Grant

• Current Assignee: Malikie Innovations Limited (Key Patent Innovations Limited)
• Original Assignee: Blackberry Limited
• Inventors: Broga, Matthew, Lee, Hsin Chin
• Primary Examiner(s): Shankar, Vijay
• Application Number:
  US12/493,329
• Publication Number:
  US 20100328283A1
• Time in Patent Office: 1,247 Days
• Field of Search: 345 76- 84, 345 87- 96, 345204-215
• US Class Current: 345/207
• CPC Class Codes: G01J 1/04 Optical or mechanical part supplementary adjustable parts
• CPC Class Codes: G01J 1/0407 Optical elements not provided otherwise, e.g. manifolds, windows, holograms, gratings
• CPC Class Codes: G01J 1/32 adapted for automatic variation of the measured or reference value regulation of light intensity G05D25/00
• CPC Class Codes: G01J 1/4204 with determination of ambient light solar light G01J2001/4266
• CPC Class Codes: G01J 2001/0485 Cosinus correcting or purposely modifying the angular response of a light sensor
• CPC Class Codes: G09G 2320/0626 for control of overall brightness
• CPC Class Codes: G09G 2360/144 the light being ambient light
• CPC Class Codes: G09G 5/10 Intensity circuits

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.

Claims

1. A display assembly comprising:

a display;

a light sensor module mounted proximally to said display;

a controller connected to said light sensor module and configured to receive an electronic signal representing a measurement of ambient light incident on said display;

said controller connected to said display and configured to adjust brightness of said display based on said electronic signal;

said light sensor module comprising;

a window for transmitting ambient light;

a light sensor for receiving said ambient light and configured to generate said electronic signal;

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;

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.

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

3. The display assembly 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 display assembly of claim 3 wherein said substrate is affixed via an adhesive.

5. The display assembly of claim 3 wherein said geometric structure is further configured according to a material and thickness of said substrate.

6. The display assembly of claim 1 wherein said textured surface is integrally formed into said window.

7. The display assembly of claim 1 wherein said textured surface comprises a plurality of bosses.

8. The display assembly of claim 7 wherein said bosses are trapeziums.

9. The display assembly of claim 7 wherein said bosses are partial-spheroids.

10. The display assembly of claim 7 wherein said bosses are four-sided pyramids.

11. The display assembly of claim 7 wherein the bosses are regularly spaced.

12. The display assembly of claim 7 wherein the bosses are irregularly spaced.

13. The display assembly of claim 1 wherein said textured surface is made from one of polymethyl methacrylate, polyethylene terephthalate, acrylic, or epoxy.

14. The display assembly of claim 1 wherein said wave guide is made from a material having a refractive index of between about 1.4 and about 1.7.

15. The display assembly of claim 1 wherein said function has a lower tolerance of about −

5%.

16. The display assembly of claim 1 wherein said function has an upper tolerance of about +5%.

17. The display assembly of claim 1 wherein said light sensor module further comprises a light emitter configured to emit light at a first angle;

said wave guide configured to scatter light emitted from said light emitter out of said window at angle wider than said first angle.

18. The display assembly of claim 17 wherein said display assembly is configured for incorporation into a portable electronic device and said light emitter is configured to indicate a status of said portable electronic device.

19. 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;

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;

wherein said wave guide is made from a material having a refractive index of between about 1.4 and about 1.7; and

wherein said function has a lower tolerance of about −

5% and an upper tolerance of about +5%.

20. 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;

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;

wherein said wave guide is made from a material having a refractive index of between about 1.4 and about 1.7; and

wherein said function has a lower tolerance of about −

5% and an upper tolerance of about +5%.