LIGHT GUIDE PLATE AND BACKLIGHT UNIT HAVING THE SAME

• US 20090316433A1
• Filed: 01/15/2009
• Published: 12/24/2009
• Est. Priority Date: 06/19/2008
• Status: Active Grant

• Current Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Original Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Inventors: Kwon, Jae-Joong, Baek, Seung-In, Hwang, In-Sun, Kim, Hyoung-Joo, Shim, Sung-Kyu
• Granted Patent: US 8,182,131 B2
• Time in Patent Office: Days
• US Class Current: 362/613
• 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 6/0053 Prismatic sheet or layer; Brightness enhancement element, sheet or layer
• CPC Class Codes: G02B 6/0055 Reflecting element, sheet or layer
• CPC Class Codes: G02B 6/0061 to provide homogeneous light output intensity
• CPC Class Codes: G02B 6/0068 Arrangements of plural sources, e.g. multi-colour light sources

Abstract

In accordance with one or more embodiments of the present disclosure, a light guide plate includes a first light incident surface receiving a first external light, a second light incident surface receiving a second external light and opposite to the first light incident surface, a light exit surface connecting the first and second light incident surfaces to output the first and second external lights, a reflective surface reflecting the first and second external lights in opposition to the light exit surface, and optical path changing portions each of which having a first inclined surface and a second inclined surface. The optical path changing portions are provided on the reflective surface with a predetermined interval and recessed toward the light exit surface to reflect the first and second external lights to the light exit surface.

Claims

1. A light guide plate comprising:

a first light incident surface onto which a first external light is incident;

a second light incident surface onto which a second external light is incident, the second light incident surface being opposite to the first light incident surface;

a light exit surface that connects the first light incident surface to the second light incident surface to output the first and second external lights;

a reflective surface that reflects the first and second external lights in opposition to the light exit surface; and

a plurality of optical path changing portions that are provided on the reflective surface with a predetermined interval and recessed toward the light exit surface to reflect the first and second external lights to the light exit surface,

wherein each of the optical path changing portions comprises;

a first inclined surface having a width that is dependent upon its position relative to the first light incident surface, wherein the width of the first inclined surface increases as a distance from the first light incident surface increases for corresponding ones of the first inclined surfaces; and

a second inclined surface having a width that is dependent upon its position relative to the second light incident surface, wherein the width of the second inclined surface increases as a distance from the second light incident surface increases for corresponding ones of the second inclined surfaces, and wherein the second inclined surface is connected to the first inclined surface.

2. The light guide plate of claim 1, wherein the optical path changing portions are provided symmetrically to each other about a first reference line extending from a center of the light exit surface perpendicularly to the light exit surface.

3. The light guide plate of claim 2, wherein a first distance between an end of the first inclined surface connected to the reflective surface and the light exit surface is increased in a direction opposite to the first light incident surface, and a second distance between an end of the second inclined surface connected to the reflective surface and the light exit surface is increased in a direction opposite to the second light incident surface.

4. The light guide plate of claim 3, wherein the first inclined surface is inclined at a first angle with respect to the light exit surface, the second inclined surface is inclined at a second angle with respect to the light exit surface, and the first angle is different from the second angle.

5. The light guide plate of claim 2, wherein a first distance between an end of the first inclined surface connected to the reflective surface and the light exit surface is decreased in a direction of the first light incident surface and the second light incident surface on a basis of the first reference line, and a second distance between an end of the second inclined surface connected to the reflective surface and the light exit surface is decreased in a direction of the first light incident surface and the second light incident surface on a basis of the first reference line.

6. The light guide plate of claim 5, wherein the first inclined surface is inclined at a first angle with respect to the light exit surface, the second inclined surface is inclined at a second angle with respect to the light exit surface, and the first angle is equal to the second angle.

7. The light guide plate of claim 2, wherein a first distance between an end of the first inclined surface connected to the reflective surface and the light exit surface is increased in a direction of the first reference line in a first region between the first light incident surface and the first reference line, the first distance being constant in a second region between the first reference line and the second light incident surface, and

a second distance between an end of the second inclined surface connected to the reflective surface and the light exit surface is increased in a direction of the first reference line in the second region, the second distance being constant in the first region as the distance approaches to the first reference line from the second light incident surface, the distance being constant between the first reference line and the first light incident surface.

8. The light guide plate of claim 7, wherein the first inclined surface is inclined at a first angle with respect to the light exit surface, the second inclined surface is inclined at a second angle with respect to the light exit surface, and the first angle is different from the second angle.

9. The light guide plate of claim 1, wherein the first inclined surface is curved.

10. The light guide plate of claim 9, wherein a tangential line making contact with the first inclined surface forms an angle of about 24 degrees to about 65 degrees with respect to a second reference line parallel to the light exit surface.

11. The light guide plate of claim 1, further comprising a reflective film coated on the reflective surface and a rear surface of the optical path changing portions.

12. A backlight unit comprising:

a first light source that generates a first light;

a second light source that generates a second light; and

a light guide plate that guides and emits the first and second lights,

wherein the light guide plate comprises;

a first light incident surface on which the first light is incident;

a second light incident surface on which the second light is incident, the second light incident surface being opposite to the first light incident surface;

a light exit surface that connects the first light incident surface to the second light incident surface to output the first and second lights;

a reflective surface that reflects the first and second external lights towards the light exit surface; and

a plurality of optical path changing portions provided on the reflective surface with a predetermined interval and recessed toward the light exit surface to reflect the first and second lights to the light exit surface, and

wherein each of the optical path changing portions comprises;

a first inclined surface having a width that is dependent upon its position relative to the first light incident surface, wherein the width of the first inclined surface increases as a distance from the first light incident surface increases for corresponding ones of the first inclined surfaces; and

a second inclined surface having a width that is dependent upon its position relative to the second light incident surface, wherein the width of the second inclined surface increases as a distance from the second light incident surface increases for corresponding ones of the second inclined surfaces, and wherein the second inclined surface is connected to the first inclined surface.

13. The backlight unit of claim 12, wherein the optical path changing portions are provided symmetrically to each other about a first reference line extending from a center of the light exit surface perpendicularly to the light exit surface.

14. The backlight unit of claim 13, wherein a first distance between an end of the first inclined surface connected to the reflective surface and the light exit surface is increased in a direction opposite to the first light incident surface, and a second distance between an end of the second inclined surface connected to the reflective surface and the light exit surface is increased in a direction opposite to the second light incident surface.

15. The backlight unit of claim 14, wherein the first inclined surface is inclined at a first angle with respect to the light exit surface, the second inclined surface is inclined at a second angle with respect to the light exit surface, and the first angle is different from the second angle.

16. The backlight unit of claim 13, wherein a first distance between an end of the first inclined surface connected to the reflective surface and the light exit surface is decreased in a direction of the first light incident surface and the second light incident surface on a basis of the first reference line, and a second distance between an end of the second inclined surface connected to the reflective surface and the light exit surface is decreased in a direction of the first light incident surface and the second light incident surface on a basis of the first reference line.

17. The backlight unit of claim 16, wherein the first inclined surface is inclined at a first angle with respect to the light exit surface, the second inclined surface is inclined at a second angle with respect to the light exit surface, and the first angle is equal to the second angle.

18. The backlight unit of claim 13, wherein a first distance between an end of the first inclined surface connected to the reflective surface and the light exit surface is increased in a direction of the first reference line in a first region between the first light incident surface and the first reference line, the first distance being constant in a second region between the first reference line and the second light incident surface, and

a second distance between an end of the second inclined surface connected to the reflective surface and the light exit surface is increased in a direction of the first reference line in the second region, the second distance being constant in the first region.

19. The backlight unit of claim 18, wherein the first inclined surface is inclined at a first angle with respect to the light exit surface, the second inclined surface is inclined at a second angle with respect to the light exit surface, and the first angle is different from the second angle.

20. The backlight unit of claim 12, wherein the first inclined surface is curved.

21. A backlight unit comprising:

a first light source that generates a first light;

a second light source that generates a second light; and

a light guide plate that guides and emits the first and second lights,

wherein the light guide plate comprises;

a first light incident surface on which the first light is incident;

a second light incident surface on which the second light is incident, the second light incident surface being opposite to the first light incident surface;

a light exit surface that connects the first light incident surface with the second light incident surface, the light exit surface having a concave-convex shape extending between the first and second light incident surfaces, the light exit surface having a plurality of first inclined surfaces that reflect light, and wherein a width of the first inclined surface increases as a distance from the first incident light surface increases for corresponding ones of the first inclined surfaces; and

a reflective surface that connects the first light incident surface with the second light incident surface in opposition to the light exit surface, the reflective surface having a convex-concave shape extending between the first and second light incident surfaces, the reflective surface having a plurality of second inclined surfaces that reflect light, and wherein a width of the second inclined surface increases as a distance from the second incident light surface increases for corresponding ones of the second inclined surfaces.

22. The backlight unit of claim 21, further comprising a reflective sheet provided below the light guide plate to reflect at least one of the first and second lights emitted from the reflective surface.