Light Guide Plate and Backlight Module using the same

• US 20100091520A1
• Filed: 11/25/2008
• Published: 04/15/2010
• Est. Priority Date: 10/15/2008
• Status: Active Grant

• Current Assignee: AU Optronics Corporation
• Original Assignee: AU Optronics Corporation
• Inventors: Liao, Super
• Granted Patent: US 7,967,493 B2
• Time in Patent Office: Days
• US Class Current: 362/616
• 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

Abstract

A light guide plate has a light incident surface, a light emitting surface and a bottom surface. The bottom surface or the light emitting surface has a plurality of light guide units disposed thereon. Each of the light guide units has a first curved surface and a second curved surface connected with the first curved surface. Both of the first curved surface and the second curved surface are concave surfaces or convex surfaces. In a cross section perpendicular to the light incident surface and passing through the first curved surface and the second curved surface, the first curved surface and the cross section intersect in a first curved line, and the second curved surface and the cross section intersect in a second curved line. A curvature radius of the first curved line is greater than that of the second curved line.

Claims

1. A light guide plate having a light incident surface, a light emitting surface and a bottom surface, the bottom surface being opposite to the light emitting surface, the light incident surface being connected between the light emitting surface and the bottom surface, the bottom surface or the light emitting surface having a plurality of light guide units disposed thereon, each of the light guide units having a first curved surface and a second curved surface connected with the first curved surface, both of the first curved surface and the second curved surface being concave surfaces or convex surfaces, in a cross section perpendicular to the light incident surface and passing through the first curved surface and the second curved surface, the first curved surface and the cross section intersecting in a first curved line, the second curved surface and the cross section intersecting in a second curved line, and a curvature radius of the first curved line being greater than a curvature radius of the second curved line.

2. The light guide plate as claimed in claim 1, wherein a joint of the first curved surface and the second curved surface is located at a first reference plane parallel with the light incident surface.

3. The light guide plate as claimed in claim 2, wherein the curvature radius of the first curved line is R1, and 100 micrometers<

R1<

∞

; and

the curvature radius of the second curved line is R2, and 100 micrometers<

R2<

300 micrometers.

4. The light guide plate as claimed in claim 3, wherein an included angle defined between a tangent of any one of points on the first curved line and a second reference plane parallel with the bottom surface and the light emitting surface is in the range from 0.1 degrees to 15 degrees, and an included angle defined between a tangent of any one of points on the second curved line and the second reference plane is in the range from 10 degrees to 60 degrees.

5. The light guide plate as claimed in claim 4, wherein the light guide units are protruded out from the bottom surface, in each of the light guide units, the second curved line is nearer to the light incident surface relative to the first curved line, and both of the first curved line and the second curved line are convex lines.

6. The light guide plate as claimed in claim 4, wherein the light guide units are concaved in the bottom surface, in each of the light guide units, the first curved line is nearer to the light incident surface relative to the second curved line, and both of the first curved line and the second curved line are concave lines.

7. The light guide plate as claimed in claim 4, wherein the light guide units are protruded out from the light emitting surface, in each of the light guide units, the first curved line is nearer to the light incident surface relative to the second curved line, and both of the first curved line and the second curved line are convex lines.

8. The light guide plate as claimed in claim 4, wherein the light guide units are concaved in the light emitting surface, in each of the light guide units, the second curved line is nearer to the light incident surface relative to the first curved line, and both of the first curved line and the second curved line are concave lines.

9. The light guide plate as claimed in claim 2, wherein a maximum length of each of the light guide units along a first direction is L1, a maximum length of each of the light guide units along a second direction is L2, the first direction is parallel with a long axis of the light incident surface, the second direction is perpendicular to the first direction, and 1≦

L1/L2≦

∞

.

10. The light guide plate as claimed in claim 1, wherein the light guide units are spaced from each other.

11. The light guide plate as claimed in claim 10, wherein intervals between each two adjacent light guide units are different.

12. The light guide plate as claimed in claim 1, wherein each two adjacent light guide units abut against each other.

13. A backlight module comprising:

a light guide plate having a light incident surface, a light emitting surface and a bottom surface, the bottom surface being opposite to the light emitting surface, the light incident surface being connected between the light emitting surface and the bottom surface, the bottom surface or the light emitting surface having a plurality of light guide units disposed thereon, each of the light guide units having a first curved surface and a second curved surface connected with the first curved surface, both of the first curved surface and the second curved surface being concave surfaces or convex surfaces, in a cross section perpendicular to the light incident surface and passing through the first curved surface and the second curved surface, the first curved surface and the cross section intersecting in a first curved line, the second curved surface and the cross section intersecting in a second curved line, and a curvature radius of the first curved line being greater than a curvature radius of the second curved line;

a light source disposed adjacent to the light incident surface; and

an optical sheet disposed above the light emitting surface.

14. The backlight module as claimed in claim 13, wherein a joint of the first curved surface and the second curved surface is located at a first reference plane parallel with the light incident surface.

15. The backlight module as claimed in claim 14, wherein the curvature radius of the first curved line is R1, and 100 micrometers<

R1<

∞

; and

the curvature radius of the second curved line is R2, and 100 micrometers<

R2<

300 micrometers.

16. The backlight module as claimed in claim 15, wherein an included angle defined between a tangent of any one of points on the first curved line and a second reference plane parallel with the bottom surface and the light emitting surface is in the range from 0.1 degrees to 15 degrees, and an included angle defined between a tangent of any one of points on the second curved line and the second reference plane is in the range from 10 degrees to 60 degrees.

17. The backlight module as claimed in claim 16, wherein the light guide units are protruded out from the bottom surface, in each of the light guide units, the second curved line is nearer to the light incident surface relative to the first curved line, and both of the first curved line and the second curved line are convex lines.

18. The backlight module as claimed in claim 16, wherein the light guide units are concaved in the bottom surface, in each of the light guide units, the first curved line is nearer to the light incident surface relative to the second curved line, and both of the first curved line and the second curved line are concave lines.

19. The backlight module as claimed in claim 16, wherein the light guide units are protruded out from the light emitting surface, in each of the light guide units, the first curved line is nearer to the light incident surface relative to the second curved line, and both of the first curved line and the second curved line are convex lines.

20. The backlight module as claimed in claim 16, wherein the light guide units are concaved in the light emitting surface, in each of the light guide units, the second curved line is nearer to the light incident surface relative to the first curved line, and both of the first curved line and the second curved line are concave lines.

21. The backlight module as claimed in claim 14, wherein a maximum length of each of the light guide units along a first direction is L1, a maximum length of each of the light guide units along a second direction is L2, the first direction is parallel with a long axis of the light incident surface, the second direction is perpendicular to the first direction, and 1≦

L1/L2≦

∞

.

22. The backlight module as claimed in claim 13, wherein the light guide units are spaced from each other.

23. The backlight module as claimed in claim 22, wherein intervals between each two adjacent light guide units are different.

24. The backlight module as claimed in claim 13, wherein each two adjacent light guide units abut against each other.

25. The backlight module as claimed in claim 13, further comprising a reflective sheet disposed under the bottom surface of the light guide plate.