Backlighting transmissive displays

• US 20030048639A1
• Filed: 09/10/2001
• Published: 03/13/2003
• Est. Priority Date: 09/10/2001
• Status: Active Grant

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Miller, Richard A., Boyd, Gary Timothy, Whitney, Leland Ray, Kotchick, Keith Michael
• Granted Patent: US 6,663,262 B2
• Time in Patent Office: Days
• US Class Current: 362/296
• CPC Class Codes: G02B 6/0031 Reflecting element, sheet or layer
• CPC Class Codes: G02F 1/133615 Edge-illuminating devices, i.e. illuminating from the side

Abstract

A backlight assembly for use in a transmissive display system is described. The backlight assembly includes a light source that illuminates a light chamber. A transmissive display is positioned adjacent the light chamber so that light that exits the chamber illuminates the transmissive display. The backlight assembly may include one or more specular reflectors and one or more other optical elements to ensure that the light that exits the light chamber has the desired spatial uniformity, polarization, color, and/or angular distribution

Claims

1. A backlight assembly for a transmissive display device comprising:

a light chamber;

a light source that emits light into the light chamber;

a first conditioner disposed between the light source and the light chamber, wherein the first conditioner alters light entering the light chamber;

a reflector within the light chamber that reflects light altered by the first conditioner; and

a second conditioner that alters light reflected by the reflector, wherein light exists the light chamber through the second conditioner.

2. The backlight assembly of claim 1, wherein the light source comprises at least one light emitting diode.

3. The backlight assembly of claim 2, wherein the light source comprises a number of light emitting diodes.

4. The backlight assembly of claim 1, wherein the first conditioner includes a diffuser film.

5. The backlight assembly of claim 1, wherein the first conditioner includes a horn shaped cavity formed with a hole on a first side of the cavity, wherein light from the light source enters the cavity through the hole.

6. The backlight assembly of claim 5, wherein inner walls of the cavity are reflective.

7. The backlight assembly of claim 5, further comprising a diffuser film positioned on a second side of the cavity, wherein the second side is opposite the first side.

8. The backlight assembly of claim 7, further comprising a Fresnel lens adjacent the diffuser film.

9. The backlight assembly of claim 5, wherein the cavity is filled with a diffuser material.

10. The backlight assembly of claim 1, wherein the chamber is filled with diffuser material.

11. The backlight assembly of claim 1, wherein inner walls of the chamber are reflective.

12. The backlight assembly of claim 1, wherein the reflector comprises a specular reflective film.

13. The backlight assembly of claim 1, wherein the reflector is a reflective polarizer.

14. The backlight assembly of claim 1, wherein the reflector comprises a specular reflective coating.

15. The backlight assembly of claim 1, wherein the reflector has a substantially smooth surface.

16. The backlight assembly of claim 1, wherein the second conditioner includes a Fresnel lens.

17. The backlight assembly of claim 1, wherein the second conditioner includes a reflective polarizer to reflect light having undesired polarization back into the chamber.

18. The backlight assembly of claim 1, wherein the second conditioner includes at least one prismatic film.

19. The backlight assembly of claim 1, wherein the second conditioner includes a diffuser film.

20. The backlight assembly of claim 1, wherein the second conditioner includes a polarizer film.

21. The backlight assembly of claim 1, wherein the chamber is divided into two chamber regions separated by a third conditioner.

22. The backlight assembly of claim 21, wherein the third conditioner includes a diffuser film.

23. The backlight assembly of claim 21, wherein the third conditioner includes a polarizer film.

24. The backlight assembly of claim 21, further comprising a second reflector, wherein the reflectors reside respectively within the two chamber regions.

25. The backlight assembly of claim 21, wherein the light source and the second conditioner are positioned on a same side of the chamber.

26. The backlight assembly of claim 21, wherein the light source and the second conditioner are positioned on opposing sides of the chamber.

27. A transmissive display system comprising:

a backlight assembly including;

a light chamber,

a light source that emits light into the light chamber,

a first conditioner disposed between the light source and the light chamber that alters light that enters the light chamber,

a reflector within the light chamber that reflects the light altered by the first conditioner, and

a second conditioner that alters light reflected by the reflector; and

a display adjacent the second conditioner.

28. A transmissive display system comprising:

a light source;

a light chamber; and

a display, wherein the light source illuminates the light chamber and the light chamber illuminates the display, and wherein the light source and the display are positioned along a common side of the light chamber.

29. The transmissive display system of claim 28, wherein the light chamber includes a first chamber region and a second chamber region, and wherein the light source is positioned adjacent the first chamber region and the display is positioned adjacent the second chamber region.

30. The transmissive display system of claim 28, wherein the light chamber includes at least one reflector that reflects light emitted from the light source toward the display.

31. The transmissive display system of claim 28, further comprising at least one conditioner that alters light emitted from the light source.

32. A transmissive display system comprising:

a light source;

a light chamber; and

a display, wherein the light source illuminates the light chamber and the light chamber illuminates the display, and wherein the light source and the display are positioned along opposite sides of the light chamber.

33. The transmissive display system of claim 32, wherein the light chamber includes a first chamber region and a second chamber region, and wherein the light source is positioned adjacent the first chamber region and the display is positioned adjacent the second chamber region.

34. The transmissive display system of claim 32, wherein the light chamber includes at least one reflector that reflects light emitted from the light source toward the display.

35. The transmissive display system of claim 32, further comprising at least one conditioner that alters light emitted from the light source.

36. A backlight assembly for a transmissive display device comprising:

a light chamber including first and second light chamber regions,

a light source that emits light into the first light chamber region,

a first conditioner that alters light that enters the first light chamber region,

a first reflector within the first light chamber region that reflects light altered by the first conditioner,

a third conditioner that alters light reflected by the first reflector, the third conditioner positioned between the first and second light chamber regions,

a second reflector within the second light chamber region that reflects light altered by the third conditioner, and

a second conditioner that alters light reflected by the second reflector.

37. The backlight assembly of claim 36, wherein the first conditioner and the second conditioner are positioned on a common side of the chamber.

38. The backlight assembly of claim 36, wherein the first conditioner and the second conditioner are positioned on opposing sides of the chamber.

39. A backlight assembly for a transmissive display comprising:

a light chamber,

a light source means adjacent the light chamber for emitting light into the light chamber,

a first conditioning means for altering light that enters the light chamber,

a reflecting means within the light chamber for reflecting light altered by the first conditioner, and

a second conditioning means for altering light reflected by the reflector means, wherein light exists the light chamber through the second conditioning means.

40. A backlight assembly for a transmissive display comprising:

a light chamber;

at least one light emitting diode that emits light into the light chamber;

a first conditioner disposed between the light source and the light chamber, wherein the first conditioner includes a horn shaped cavity formed with a hole on a first side of the cavity, wherein light from the light source enters the cavity through the hole, and wherein the first conditioner includes a first diffuser film positioned on a second side of the cavity, wherein the second side is opposite the first side.

a specular reflector within the light chamber that reflects light altered by the first conditioner; and

a second conditioner that alters light reflected by the reflector, wherein the second conditioner includes a Fresnel lens, a prismatic film, a second diffuser film, a reflective polarizer, and a polarizer.

41. A backlight assembly for a transmissive display comprising:

a first light chamber,

a first light source that illuminates the first light chamber,

a second light chamber,

a second light source that illuminates the second light chamber, and

a diffuser film adjacent both the first and second light chambers.