Transreflectors, transreflector systems and displays and methods of making transreflectors

• US 7,806,539 B2
• Filed: 02/05/2009
• Issued: 10/05/2010
• Est. Priority Date: 12/05/2001
• Status: Expired due to Fees

• Current Assignee: Innovative Display Technologies LLC (Acacia Research Corporation)
• Original Assignee: Rambus International Ltd (Rambus Inc.)
• Inventors: McCollum, Timothy A., Parker, Jeffery R.
• Primary Examiner(s): Sember; Thomas M
• Application Number:
  US12/365,916
• Publication Number:
  US 20090161385A1
• Time in Patent Office: 607 Days
• Field of Search: 362/19, 362606-615, 362624-627, 362/634, 349/61, 349/62, 349/65, 359/483, 359494-496
• US Class Current: 362/19
• CPC Class Codes: G02B 6/0021 for housing at least a part of the light source, e.g. by forming holes or recesses
• 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 6/005 provided by one optical element, or plurality thereof, placed on the light output side of the light guide
• CPC Class Codes: G02B 6/0053 Prismatic sheet or layer; Brightness enhancement element, sheet or layer
• CPC Class Codes: G02B 6/0056 for producing polarisation effects, e.g. by a surface with polarizing properties or by an additional polarizing elements
• CPC Class Codes: G02B 6/0061 to provide homogeneous light output intensity
• CPC Class Codes: G02B 6/0065 Manufacturing aspects; Material aspects
• CPC Class Codes: G02B 6/0073 Light emitting diode [LED]
• CPC Class Codes: G02F 1/133555 Transflectors
• CPC Class Codes: G02F 1/133615 Edge-illuminating devices, i.e. illuminating from the side

Abstract

Optical assembly includes a hollow backlight having at least one light input edge and at least one light source positioned adjacent to the at least one light input edge. A back reflector is positioned at or in close proximity to a first side of the hollow backlight for reflecting the light through the hollow backlight and out through a second side of the hollow backlight superimposed on the first side, and a reflective polarizer is positioned at or in close proximity to the second side of the backlight.

Claims

1. An optical assembly comprising:

a hollow backlight having a first side, a second side superimposed on the first side, and at least one light input edge;

at least one LED light source positioned adjacent the at least one light input edge, the at least one light source being quite small in relation both to a length and to a width of the optical assembly, the light from the at least one light source being transmitted in the hollow backlight;

a back reflector positioned at or in close proximity to the first side of the hollow backlight for reflecting the light through the hollow backlight and out through the second side;

a reflective polarizer having opposite sides, one of the sides being attached to the second side of the hollow backlight, the reflective polarizer having multiple layers, each layer having a refractive index that is different from adjacent layers of the reflective polarizer;

and a display or a sheet, film or substrate in close proximity to the other side of the reflective polarizer with an air gap between the reflective polarizer and the display or the sheet, film or substrate;

wherein optical deformities that are projections or depressions on or in one or both sides of the reflective polarizer are shaped to redirect the light in a predetermined manner; and

wherein at least some of the optical deformities on or in the one side of the reflective polarizer comprise a plurality of light transmissive surfaces and light reflective surfaces, the light reflective surfaces having a reflective coating for redirecting reflected light within the reflective polarizer back toward the other side of the reflective polarizer.

2. The optical assembly of claim 1, wherein the back reflector reflects most of the light that is incident on the back reflector, thereby improving the light output efficiency of the optical assembly.

3. The optical assembly of claim 1, wherein the back reflector is attached to the first side of the hollow backlight.

4. The optical assembly of claim 1, wherein a frame, tray, or housing forms at least a portion of the hollow backlight.

5. The optical assembly of claim 4, wherein the back reflector forms an integral portion of the frame, tray, or housing.

6. The optical assembly of claim 4, wherein the reflective polarizer forms an integral portion of the frame, tray, or housing.

7. The optical assembly of claim 1, comprising a pattern of well defined optical elements for extracting the light from the backlight, each of the optical elements of the pattern being quite small in relation both to the length and to the width of the optical assembly.

8. The optical assembly of claim 7, wherein the pattern of well defined optical elements is located on or in the hollow backlight.

9. The optical assembly of claim 1, wherein the hollow backlight contains air.

10. The optical assembly of claim 1, wherein one of the layers of the reflective polarizer is an optical coating.

11. The optical assembly of claim 1, wherein the reflective polarizer is made of a thermo-formable material.

12. The optical assembly of claim 1, wherein the reflective polarizer is made of an ultraviolet-curable polymer.

13. The optical assembly of claim 1, wherein the light transmissive and light reflective surfaces are sloped or angled surfaces.

14. The optical assembly of claim 1, comprising a plurality of LED light sources positioned adjacent to the at least one light input edge.

15. The optical assembly of claim 14, additionally comprising a transition region that is in close proximity to the at least one light input edge and configured to spread and mix the light from the light sources.

16. The optical assembly of claim 14 wherein at least some of the light sources are different color light sources.

17. The optical assembly of claim 1, wherein the at least one light input edge is located at or near a corner of the optical assembly.

18. A liquid crystal display apparatus, comprising a liquid crystal light valve array that is illuminated by the optical assembly of claim 1.

19. A membrane switch device that is illuminated by the optical assembly of claim 1.

20. The optical assembly of claim 1, wherein at least some of the optical deformities are projections on the other side of the reflective polarizer that create the air gap between the reflective polarizer and the display or the sheet, film or substrate.