Flat panel lens

• US 7,660,047 B1
• Filed: 09/03/2008
• Issued: 02/09/2010
• Est. Priority Date: 09/03/2008
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Emerton, Neil, Travis, Adrian, Large, Timothy A.
• Primary Examiner(s): Collins; Darryl J
• Application Number:
  US12/203,167
• Publication Number:
  US 20100053771A1
• Time in Patent Office: 524 Days
• Field of Search: 359726-729, 359/732
• US Class Current: 359/726
• CPC Class Codes: G02B 6/0046 Tapered light guide, e.g. wedge-shaped light guide
• CPC Class Codes: G06F 3/042 by opto-electronic means

Abstract

A flat panel lens system as a tapered light guide that has minimal or no margin for fan out. The tapered light guide includes a thin end, and a thick end of which is a bevelled mirror or an optical equivalent. Light is injected into the thin end and the mirror is such that rays injected through a point at the thin end emerge collimated from one of the light guide surfaces, and that collimated rays injected at an appropriate angle through one of the light guide surfaces emerge from a point at the thin end. Bragg gratings can be utilized for color implementations as well. The tapered light guide can be fabricated as a single piece, by extrusion, injection molding, or the combination/variation of extrusion and injection molding, as well as other commonly known techniques.

Claims

1. A lens system, comprising:

a tapered light guide having first and second surfaces that taper from a thick end to a thin end;

a receiving face at the thin end for receiving light injected into the light guide; and

a reflecting face at the thick end of the light guide for deflecting incident light back to the first and second surfaces, the deflected light exiting the first surface before reaching the receiving face.

2. The system of claim 1, wherein the reflecting face is formed at an angle such that the injected light deflected off the reflecting face exits the first surface or the second surface as collimated light.

3. The system of claim 1, wherein the reflecting face is formed at an angle such that collimated light received at the first surface or the second surface exits the receiving face at a point.

4. The system of claim 1, wherein the injected light fans out from the receiving face and deflects from the reflecting face to illuminate the first surface in its entirety.

5. The system of claim 1, wherein the reflecting face is spherically curved according to a uniform radius of curvature and an angle formed between the first surface and the curved reflecting face is equivalent to an angle formed between the second surface and the curved reflecting face.

6. The system of claim 1, wherein the first and second surfaces are flat and the thick end is twice as thick as the thin end.

7. The system of claim 1, wherein the injected light entering the receiving face includes rays that all undergo a same number of reflections from exiting the receiving face to exiting the light guide.

8. The system of claim 1, wherein the reflecting face is a reflecting grating having layers with refractive indexes that alternate between two index values and thickness that alternates between two thickness values.

9. A lens system, comprising:

a tapered light guide having a display surface and a second guide surface that taper from a thick end to a thin end, the thick end twice in thickness as the thin end;

a receiving face at the thin end for receiving light injected into the light guide; and

a reflecting face at the thick end of the light guide for deflecting incident light back to the display surface, the reflecting face tilted to reduce angles of specular rays relative to a plane of the light guide so that the specular rays exit the display surface before reaching the receiving face.

10. The system of claim 9, wherein the tilted reflecting face is a Fresnellated surface.

11. The system of claim 9, wherein the tilted reflecting face is curved about a point distant from the thin end by one light guide length in a direction parallel to an axis of the taper.

12. The system of claim 9, wherein the reflecting face includes one or more reflecting gratings having layers with refractive indexes that alternate between two index values and thickness that alternates between two thickness values, the one or more reflective grating eliminate aperture diffraction.

13. The system of claim 9, wherein the reflecting face is spherically curved according to a uniform radius of curvature, and an angle formed between the display surface and the curved reflecting face is equivalent to an angle formed between the second surface and the curved reflecting face.

14. The system of claim 13, wherein the display surface and the second guide surface each form a right angle to the reflecting face at the thick end.

15. The system of claim 9, wherein the reflecting face is comprised of three sets of Bragg gratings for illuminating the display surface using red, green and blue colors.

16. The system of claim 9, wherein the light is injected into a center of the thin end to eliminate a blank margin for fan out.

17. The system of claim 9, wherein the reflecting face deflects the incident light such that the specular light exits the display surface at a point dependent on an angle of injection of the light.

18. A lens system, comprising:

a wedge-shaped light guide having a display surface and a second guide surface that taper from a thick end to a thin end;

a receiving face at the thin end for receiving light injected into the light guide; and

a reflecting surface at the thick end of the light guide for deflecting incident light back to the display surface, the reflecting surface tilted and curved about a point distant from the thin end of the light guide by one light guide length in a direction parallel to an axis of the taper.

19. The system of claim 18, wherein the display surface and the second guide surface transition to a section at the thick end where the display surface is parallel to the second guide surface, and the thick end is twice as thick as the thin end.

20. The system of claim 19, wherein the reflecting surface is a Fresnellated surface having alternating planes of reflective surfaces at correspondingly alternating angles, the planes having normals that share a same component resolved in a plane of the light guide and equal but opposite components perpendicular to the plane of the light guide.