Light guide plates and backlight module

• US 8,070,345 B2
• Filed: 08/20/2009
• Issued: 12/06/2011
• Est. Priority Date: 12/12/2008
• Status: Active Grant

• Current Assignee: Hon Hai Precision Industry Co., Ltd., Tsinghua University
• Original Assignee: Hon Hai Precision Industry Co., Ltd., Tsinghua University
• Inventors: Zhang, He, Zhu, Jun, Zhao, Yan, Jin, Guo-Fan
• Primary Examiner(s): SHALLENBERGER, JULIE A
• Application Number:
  US12/544,709
• Publication Number:
  US 20100149787A1
• Time in Patent Office: 838 Days
• Field of Search: 362/617, 362/620, 362/619, 362/623, 362/628
• US Class Current: 362/619
• CPC Class Codes: G02B 6/0031 Reflecting element, sheet or layer
• CPC Class Codes: G02B 6/0036 2-D arrangement of prisms, protrusions, indentations or roughened surfaces
• CPC Class Codes: G02B 6/0043 provided on the surface of the light guide
• CPC Class Codes: G02B 6/0055 Reflecting element, sheet or layer
• CPC Class Codes: G02F 1/133545 Dielectric stack polarisers
• CPC Class Codes: G02F 1/133605 including specially adapted reflectors
• CPC Class Codes: G02F 1/133607 the light controlling member including light directing or refracting elements, e.g. prisms or lenses
• CPC Class Codes: G02F 1/133611 including means for improving the brightness uniformity

Abstract

A light guide plate includes a body having a bottom surface and a light output surface opposite to the bottom surface. A reflector is located on the light output surface opposite to the center of the bottom surface. The reflector is a cavity concaved from the light output surface to the inside of the body. A plurality of scattering dots are located on the bottom surface. The scattering dots are arranged in the form of a plurality of concentric circles around the center of the bottom surface. The number of the scattering dots is defined based on a radius of the circle they reside on, and the radius of the circle is greater than or substantially equal to 4 millimeter.

Claims

1. A light guide plate, comprising:

a body having a bottom surface having a center and a light output surface;

a reflector located on the light output surface and opposite to the center, the reflector is a cavity; and

a plurality of scattering dots located on the bottom surface, the scattering dots are arranged in the form of a plurality of concentric circles around the center, and the number of the scattering dots is defined based on a radius of the circle, the radius of the circle is greater than or substantially equal to 4 millimeter, wherein the number of the scattering dots for each concentric circle ‘

e’

is definded by the following formula;

e=|4[a1×

(r−

a2)×

(r−

a3)]|

where ‘

r’

is a radius of the circle and r≧

4 millimeter;

‘

a1’

, ‘

a2’ and

‘

a'"'"'’

are constant, 0.05≦

a1≦

0.1, a2≧

6, and a3≦

12.

2. The light guide plate of claim 1, wherein ‘

a1’

is about 0.1, ‘

a2’

is about 6, and ‘

a3’

is about 12.

3. The light guide plate of claim 1, wherein the cavity of the reflector is hemispherical, conical, or parabolic.

4. The light guide plate of claim 3, wherein a vertex of the conical cavity is aligned with the center;

a diameter of a bottom of the cone ranges from about 8.5 millimeters to about 9.2 millimeters and a height of the cone ranges from about 1.4 millimeters to about 1.6 millimeters.

5. The light guide plate of claim 1, wherein distances between adjacent circles is consistent.

6. The light guide plate of claim 1, wherein a distance between two adjacent circles decreases as distance from the center increases.

7. The light guide plate of claim 1, wherein the concentric circles are located equidistantly and a distance between the adjacent two circles is in a range from about 0.7 millimeters to about 1.5 millimeters.

8. The light guide plate of claim 1, wherein the scattering dots on the same circle are uniformly dispersed.

9. The light guide plate of claim 1, wherein the scattering dots are protruding, concave or a combination thereof.

10. The light guide plate of claim 1, wherein a shape of the scattering dots is spherical, hemispherical, conical or a combination thereof.

11. The light guide plate of claim 1, wherein the exposed surfaces of the scattering dots are coated with reflective material.

12. A light guide plate, comprising:

a body having a bottom surface having a center, and a light output surface opposite to the bottom surface; and

a plurality of scattering dots located on the bottom surface, the scattering dots are arranged in the form of a plurality of concentric circles around the center, and the number of the scattering dots for each concentric circle ‘

e’

is defined by the following formula;

e=|4[a1×

(r−

a2)×

(r−

a3)]|

wherein, ‘

e’

is the number of the scattering dots;

‘

r’

is the radius of the circle and r≧

4 millimeter;

‘

a1’

, ‘

a2’ and

‘

a3’

are constant, 0.05≦

a1≦

01, a2≧

6, and a3≦

12.

13. A backlight module comprising:

a light source;

a body having a bottom surface having a center and a light output surface opposite to the bottom surface, the light source is located adjacent to the center of bottom surface;

a reflector located on the light output surface opposite to the center, and the reflector; and

a plurality of scattering dots located on the bottom surface, the scattering dots are arranged in the form of a plurality of concentric circles around the center, and the number of the scattering dots is defined based on a radius of the circle, and the radius of the circle is greater than or substantially equal to 4 millimeter, wherein the number of the scattering dots for each concentric circle ‘

e’

is defined by the following formula;

e=|4[a1×

(r−

a2)×

(r−

a3)]|

wherein ‘

r’

is the radius of the circle and r≧

4 millimeter;

‘

a1’

, ‘

a2’ and

‘

a3’

are constant, 0.05≦

a1≦

01, a2≧

6, and a3≦

12.

14. The backlight module of claim 13, further comprising a reflective plate located between the light source and the bottom surface of the light guide plate.

15. The backlight module of claim 14, wherein the reflective plate comprises a reflective film located on a surface of the reflective plate.

16. The backlight module of claim 13, further comprising a brightness enhancement film located above the light output surface of the light guide plate.

17. The backlight module of claim 13, further comprising a microprism plate, a polarization plate and a diffusing plate.

18. The light guide plate of claim 13, wherein ‘

a1’

is 0.1, ‘

a2’

is 6, and ‘

a3’

is 12.