Light guide device and a backlight module using the same

• US 7,334,934 B2
• Filed: 11/02/2005
• Issued: 02/26/2008
• Est. Priority Date: 11/12/2004
• Status: Active Grant

• Current Assignee: Hon Hai Precision Industry Co., Ltd., Tsinghua University
• Original Assignee: Hon Hai Precision Industry Co., Ltd., Tsinghua University
• Inventors: Feng, Di, Jin, Guo-Fan, Fan, Shou-Shan, Yan, Ying-Bai
• Primary Examiner(s): Sawhney; Hargobind S.
• Application Number:
  US11/265,427
• Publication Number:
  US 20060104092A1
• Time in Patent Office: 846 Days
• Field of Search: 362/626
• US Class Current: 362/626
• CPC Class Codes: G02B 6/0016 Grooves, prisms, gratings, scattering particles or rough 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 6/0061 to provide homogeneous light output intensity

Abstract

A light guide device includes a main body and a plurality of parallel elongate first V-shaped microstructures. The main body has an incident surface; an emitting surface adjoining the incident surface; and a reflecting surface opposite to the emitting surface. The first V-shaped microstructures are provided on the reflecting surface. Each of the first V-shaped microstructures has a triangular cross-section having a first base angle nearest the incident surface, a second base angle furthest from the incident surface and a vertex angle. A pitch between adjacent microstructures is configured to be substantially constant. A size of each of the first V-shaped microstructures is defined by the equation is y=9.2637×10⁻⁶x²−0.0003x+0.0232, wherein x is a distance from a given first V-shaped microstructures to the incident surface (in units of micrometers), and wherein y is a base width of the given first V-shaped microstructures (in units of micrometers).

Claims

1. A light guide device, comprising:

a main body including;

an incident surface;

an emitting surface adjoining the incident surface;

a reflecting surface opposite to the emitting surface;

a plurality of parallel elongate first V-shaped microstructures provided on the reflecting surface; and

each first V-shaped microstructures having a triangular cross-section, the triangular cross-section having a first base angle nearest the incident surface, a second base angle furthest from the incident surface and a vertex angle, a distance between adjacent first V-shaped microstructures defining a first pitch, the first pitch being configured to be substantially constant between each particular pair of adjacent first V-shaped microstructures, a base width of the first V-shaped microstructures being defined by the equation y=9.2637×

10<sup>−

6</sup>x²−

0.0003x+0.0232, wherein x is the distance between a given first V-shaped microstructure and the incident surface, in units of micrometers, and wherein y is the base width of the given first V-shaped microstructure, in units of micrometers.

2. The light guide device according to claim 1, wherein each of the first V-shaped microstructures has a same height.

3. The light guide device according to claim 1, wherein the first base angle is about in the range from 70 to 90 degrees, the second base angle is in the approximate range from 15 to 50 degrees, and the vertex angle is in the range of about from 40 to 95 degrees.

4. The light guide device according to claim 1, wherein the base width of each of the first V-shaped microstructures is about in the range from 10 to 300 micrometers.

5. The light guide device according to claim 1, further comprising a plurality of second V-shaped microstructures formed on the emitting surface thereof, the second V-shaped microstructures being oriented in a direction essentially perpendicular to the incident surface thereof.

6. The light guide device according to claim 5, wherein each second V-shaped microstructure has at least one of the following characteristics:

a given second V-shaped microstructure has a triangular cross-section having a vertex angle that is in the range from 50 to 150 degrees; and

a given second V-shaped microstructure has a height in the range from above about 0 to about 500 micrometers.

7. The light guide device according to claim 1, further comprising a plurality of third V-shaped microstructures formed on the incident surface thereof, the third V-shaped microstructures being oriented in a direction perpendicular to the reflecting surface thereof.

8. The light guide device according to claim 7, wherein each of the third V-shaped microstructures has at least one of the following characteristics:

a given third V-shaped microstructure has a triangular cross-section having a vertex angle that is in the range from 50 to 150 degrees; and

a given third V-shaped microstructure has a height in the range from above about 0 to about 500 micrometers.

9. The light guide device according to claim 1, further comprising a high reflectivity film formed on the exterior of the first V-shaped microstructures and on the intermediate reflective surface portions of the main body.

10. The light guide device according to claim 9, wherein the high reflectivity film is one of a metal film and a dielectric film.

11. The light guide device according to claim 10, wherein the high reflectivity film is a metal film, the metal film being one of an aluminum film and a silver film.

12. The light guide device according to claim 1, comprising three sidewalls with a high reflectivity film formed on the three sidewalls.

13. The light guide device according to claim 1, wherein the light guide device is one of a flat sheet and a wedge-shaped body.

14. The light guide device according to claim 1, wherein the light guide device is comprised of a material selected from a group consisting of polymethyl methacrylate, polycarbonate, and a combination thereof.

15. A backlight module comprising:

a light source; and

a light guide device comprising a main body comprising;

an incident surface disposed adjacent the light source;

an emitting surface adjoining the incident surface;

a reflecting surface opposite to the emitting surface;

a plurality of parallel elongate first V-shaped microstructures formed on the reflecting surface, each of the first V-shaped microstructures having a triangular cross-section each triangular cross-section including a first base angle nearest the incident surface, a second base angle furthest from the incident surface and a vertex angle, a distance between adjacent first V-shaped microstructures defining a pitch, the pitch being configured to be substantially constant between each particular pair of adjacent first V-shaped microstructures, a base width of the first V-shaped microstructures progressively increasing as a distance between the first V-shaped microstructures and the incident surface increasing; and

wherein the base width is defined by the equation;

y=9.2637×

10<sup>−

6</sup>x²−

0.0003x+0.0232, wherein x is a distance from a given first V-shaped microstructure to the incident surface, in units of micrometers, and wherein y is the base width of the given first V-shaped microstructure, in units micrometers.

16. The backlight module according to claim 15, further comprising a plurality of third V-shaped microstructures formed on the incident surface thereof, the third V-shaped microstructures being oriented in a direction perpendicular to the reflecting surface thereof.

17. The backlight module according to claim 15, further comprising a reflector partly surrounding the light source.