Hollow backlight with tilted light source

• US 8,757,858 B2
• Filed: 06/01/2009
• Issued: 06/24/2014
• Est. Priority Date: 06/04/2008
• Status: Expired due to Fees

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Aastuen, David J. W., Epstein, Kenneth A., Ko, Byung-Soo, Wheatley, John A.
• Primary Examiner(s): Makiya, David J
• Application Number:
  US12/995,368
• Publication Number:
  US 20110134659A1
• Time in Patent Office: 1,849 Days
• Field of Search: 362/609, 362/623
• US Class Current: 362/609
• CPC Class Codes: G02B 6/002 by shaping at least a portion of the light guide, e.g. with collimating, focussing or diverging surfaces
• CPC Class Codes: G02B 6/0031 Reflecting element, sheet or layer
• CPC Class Codes: G02B 6/0096 the lights guides being of the hollow type
• CPC Class Codes: G02F 1/133605 including specially adapted reflectors
• CPC Class Codes: G02F 1/133615 Edge-illuminating devices, i.e. illuminating from the side

Abstract

In one embodiment, the invention provides backlight comprising a front reflector (102) and a back reflector (104) disposed to form a hollow light cavity (106) with a first light source (108) proximate one end of the front reflector (102) and having a tilt angle (110) of from 5° to 90°, and a first asymmetric light collimator (116) extending between at least the first light source (108) and the back reflector (104) for directing light from the first light source (108) into the hollow light cavity (106).

Claims

1. A backlight, comprising:

a front reflector and a back reflector disposed to form a hollow light cavity;

a first light source proximate one end of the front reflector and having a tilt angle of from 45°

to 90°

, wherein the tilt angle is defined by an intersection of a line parallel with a tangent to a plane of the front reflector and a line normal to and bisecting an aperture plane of the first light source; and

a first asymmetric light collimator for directing light from the first light source into the hollow light cavity, wherein the first light collimator has a curvature that extends from the aperture plane of the first light source to a point on the back reflector where a line tangent to the first light collimator is horizontal.

2. The backlight of claim 1, wherein the asymmetric light collimator is parabolic.

3. The backlight of claim 1, wherein the first light source comprises a light element and a light element reflector in the shape of a pair of involutes.

4. The backlight of claim 1, further comprising a side reflector surrounding a periphery opposite the light source.

5. The backlight of claim 1, wherein the light source comprises a light element comprising a CCFL.

6. The backlight of claim 1, wherein the light source comprises a light element comprising an LED.

7. The backlight of claim 1, further comprising a second asymmetric light collimator extending between the first light source and the front reflector.

8. The backlight of claim 1, wherein the first asymmetric light collimator and the back reflector are unitary.

9. The backlight of claim 1, wherein the back reflector comprises a scattering reflective material.

10. The backlight of claim 1, wherein the back reflector further comprises a linear lens film.

11. The backlight of claim 1, wherein the front reflector comprises multiple layers.

12. The backlight of claim 1, further comprising a second light source proximate another end of the front reflector and having a tilt angle of from 5°

to 90°

; and

a second asymmetric light collimator extending between the second light source and the back reflector for directing light from the second light source into the hollow light cavity.

13. The backlight of claim 1, wherein the front reflector comprises at least one of a diffuser plate, a gain diffuser, a brightness enhancement film, a reflective polarizer, or any combination of any of them.

14. The backlight of claim 1, wherein the light source comprises a light element reflector and the light element reflector has a cross-sectional shape that is ovoid, rectangular, or trapezoidal.

15. The backlight of claim 1, wherein the light source comprises an LED and a heat sink.

16. The backlight of claim 2, wherein a vertex of a parabola formed by the first light collimator is at an intersection of the aperture plane of the first light source.

17. The backlight of claim 2, wherein a focus of a parabola formed by the first light collimator is at an intersection of the aperture plane of the first light source and the plane of the front reflector.

18. The backlight of claim 2, wherein an axis of a parabola formed by the first light collimator is parallel to the aperture plane of the first light source.

19. The backlight of claim 1, wherein the back reflector comprises a semi-specular material.

20. A backlight comprising:

a front reflector and a back reflector disposed to form a hollow light cavity;

a light source proximate one end of the front reflector, wherein the light source has a tilt angle of from 5°

to 90°

, wherein the tilt angle is defined by an intersection of a line parallel with a tangent to a plane of the front reflector and a line normal to and bisecting an aperture plane of the light source; and

an asymmetric, parabolic light collimator extending between at least the light source and the back reflector for directing light from the light source into the hollow light cavity, wherein a vertex of a parabola formed by the light collimator is at an intersection of the aperture plane of the light source.

21. The backlight of claim 20, wherein an axis of the parabola formed by the light collimator is parallel to the aperture plane of the light source.

22. The backlight of claim 20, wherein a focus of the parabola formed by the light collimator is at an intersection of the aperture plane of the light source and a plane of the front reflector.

23. The backlight of claim 20, wherein a focus of the parabola formed by the light collimator is at an intersection of the aperture plane of the light source and a plane of the front reflector.

24. The backlight of claim 20, further comprising a second asymmetric light collimator extending between the light source and the front reflector.