Collimating light guide texture

• US 9,261,639 B1
• Filed: 12/20/2013
• Issued: 02/16/2016
• Est. Priority Date: 12/20/2013
• Status: Active Grant

• Current Assignee: Modilis Holdings LLC
• Original Assignee: Modilis Holdings LLC
• Inventors: Tuohioja, Tero Johannes
• Primary Examiner(s): CARTER, WILLIAM JOSEPH
• Application Number:
  US14/137,187
• Time in Patent Office: 788 Days
• Field of Search: 362600-634
• US Class Current: 1/1
• CPC Class Codes: G02B 6/0036 2-D arrangement of prisms, protrusions, indentations or roughened surfaces

Abstract

An optical display device comprises a light source, a pixelated display panel, and a light guide to collect light from the light source and to transport the light via total internal reflection. A first surface of the light guide includes recessed regions having a circular-based profile, such as a quarter-circle profile, to reflect the light from the light guide to the pixelated display panel. A first optical layer covering at least a portion of the first surface of the light guide fills the recessed regions included in the first surface of the light guide. A second optical layer covering at least a portion of a second surface of the light guide transmits the reflected light to the pixelated display panel.

Claims

1. A display device comprising:

a light source;

a display panel;

a light guide to collect light from the light source and to transport the light via total internal reflection, wherein a first surface of the light guide includes recessed regions having a surface with a circular-based profile to reflect at least a portion of the light from the light guide to the display panel, wherein material substantially filling the recessed regions has a first refractive index and the light guide has a second refractive index, and wherein the light that is reflected from the light guide reflects off the surface with the circular-based profile two or more times based, at least in part, on a difference between the first refractive index and the second refractive index;

a first layer covering at least a portion of the first surface of the light guide, wherein a portion of the first layer fills the recessed regions included in the first surface of the light guide; and

a second layer having a refractive index lower than a refractive index of the light guide, wherein the second layer covers at least a portion of a second surface of the light guide to transmit the reflected light to the display panel, and wherein the second surface of the light guide is opposite to the first surface of the light guide.

2. The display device of claim 1, wherein the reflected light is directed from the light guide to the display panel to at least approximately uniformly illuminate the display panel.

3. The display device of claim 1, wherein alignment of the recessed regions of the first surface of the light guide is dithered to be different from alignment of rows and columns of pixels of the display panel to avoid a Moire effect.

4. The display device of claim 1, wherein the material having the first refractive index completely fills the recessed regions.

5. A device comprising:

a light guide to collect light from one or more light sources and to transport the light via total internal reflection, wherein the light guide includes a first surface and a second surface opposite to the first surface; and

a first layer covering at least a portion of the first surface of the light guide, wherein the first layer includes microstructures with a surface having a circular-based profile in the first surface of the light guide, and wherein a light ray exiting the light guide is reflected by the surface having the circular-based profile two or more times based, at least in part, on a difference between a refractive index of the first layer and a refractive index of the light guide.

6. The device of claim 5, further comprising:

a display panel; and

a second layer having a refractive index lower than a refractive index of the light guide, wherein the second layer covers at least a portion of the second surface of the light guide to transmit the reflected light to the display panel.

7. The device of claim 6, wherein the reflected light is directed from the light guide to the display panel to at least approximately uniformly illuminate the display panel.

8. The device of claim 6, wherein alignment of the microstructures of the first layer is different from alignment of rows and columns of pixels of the display panel to avoid a Moire effect.

9. The device of claim 5, wherein the circular-based profile has a radius of curvature at least approximately equal to a depth that the microstructures extend into the first surface of the light guide.

10. The device of claim 5, wherein the lightguide has a thickness that is substantially uniform and wherein a depth that the microstructures protrude into the first surface of the light guide is less than about 2% the thickness of the light guide.

11. The device of claim 5, wherein the first layer includes more than about 100,000 microstructures that collectively comprise a textured surface at an interface between the first layer and the light guide.

12. The device of claim 5, wherein the circular-based profile comprises a quarter-circle profile.

13. The device of claim 5, wherein the refractive index of the first layer is less than the refractive index of the light guide.

14. The device of claim 5, wherein the device is incorporated in a display, the device further comprising:

one or more processors;

one or more memories; and

display software stored on the one or more memories and operable on the one or more processors to modulate the light exiting the light guide.

15. A method for fabricating a display device, the method comprising:

imprinting portions of a surface of a light guide to form recessed regions that include a surface having a circular-based profile that is configured to outcouple a light ray travelling in the light guide by reflecting the light ray two or more times;

substantially filling the recessed regions with a fill material having a refractive index that is lower than a refractive index of the light guide; and

at least partially covering the light guide with a layer having a refractive index that is lower than the refractive index of the light guide.

16. The method of claim 15, wherein the circular-based profile comprises a quarter-circle profile.

17. The method of claim 15, wherein the lightguide has a thickness that is substantially uniform and wherein a depth that the recessed regions protrude into the surface of the light guide is less than about 2% the thickness of the light guide.

18. The method of claim 15, wherein the refractive index of the layer is the same as the refractive index of the fill material.

19. The method of claim 15, wherein a depth of the recessed regions is at least approximately equal to a radius of curvature of the circular-based profile.