Liquid crystal display device having a light guiding plate with a novel structure

• US 6,593,980 B2
• Filed: 06/22/2001
• Issued: 07/15/2003
• Est. Priority Date: 06/23/2000
• Status: Active Grant

• Current Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Lee, Kyoung-Don, Lee, Keun-Woo
• Primary Examiner(s): DUDEK, JAMES A
• Application Number:
  US09/886,006
• Publication Number:
  US 20010055078A1
• Time in Patent Office: 753 Days
• Field of Search: 379/65, 379/112, 362/31
• US Class Current: 349/65
• CPC Class Codes: G02B 6/0041 provided in the bulk of the light guide
• CPC Class Codes: G02B 6/0043 provided on the surface of the light guide
• CPC Class Codes: G02B 6/0051 Diffusing sheet or layer
• CPC Class Codes: G02B 6/0081 Mechanical or electrical aspects of the light guide and light source in the lighting device peculiar to the adaptation to planar light guides, e.g. concerning packaging

Abstract

A liquid crystal display device has a light guiding plate with a novel structure. The liquid crystal display device has a back light assembly including a light source and the light guiding plate, a display unit for displaying an image and a case for fixedly receiving the back light assembly and the display unit. The light guiding plate is formed at a bottom portion thereof with a light diffusing pattern for uniformly outputting the incident light. A light dispersing member for dispersing the light in the light guiding plate is provided in the light guiding plate. The leaking light is outputted towards the display unit by contacting with the dispersing particles of the light dispersing member, so the light efficiency and the brightness are improved.

Claims

1. A liquid crystal display device, comprising:

a back light assembly including a light source and a light guiding plate positioned at a side of the light source, the light guiding plate including a light incident surface for receiving a light from the light source, a side surface positioned opposite to the light incident surface, a light output surface for outputting the light, and a rear surface positioned opposite to the light output surface, the rear surface being formed with a light diffusing portion for uniformly outputting the light generated from the light source towards the light output surface, the light guiding plate being formed at an inner portion thereof with a light dispersing member for dispersing the light inputted into the light guiding plate;

a display unit for displaying an image; and

a container module for receiving the back light assembly and the display unit.

2. The liquid crystal display device as claimed in claim 1, wherein the light diffusing portion is a screen printed pattern layer.

3. The liquid crystal display device as claimed in claim 2, wherein the light diffusing portion is comprised of polymethyl methacrylate.

4. The liquid crystal display device as claimed in claim 1, wherein the light diffusing portion is directly formed on the light guiding plate.

5. The liquid crystal display device as claimed in claim 4, wherein the light diffusing portion has a prism shape, a convex lens shape, a concave lens shape, a trapezoid shape or a hexagonal shape.

6. The liquid crystal display device as claimed in claim 1, wherein a density of the light diffusing portion becomes higher as the light diffusing portion is more remote from the light incident surface.

7. The liquid crystal display device as claimed in claim 1, wherein the light dispersing member is randomly distributed in the light guiding plate.

8. The liquid crystal display device as claimed in claim 7, wherein the light dispersing member is comprised of fine particles.

9. The liquid crystal display device as claimed in claim 7, wherein the light dispersing member is comprised of an organic polymer.

10. The liquid crystal display device as claimed in claim 7, wherein a total volume of the light dispersing member is no more than 10 percent of a total volume of the light guiding plate.

11. The liquid crystal display device as claimed in claim 7, wherein a density of the light dispersing member becomes higher as the light dispersing member is more remote from the light incident surface.

12. The liquid crystal display device as claimed in claim 1, further comprising a reflection plate for reflecting the light leaked from the rear surface towards the light output surface, the reflection plate being positioned at a lower portion of the light guiding plate.

13. The liquid crystal display device as claimed in claim 1, further comprising a light adjusting means for focusing the light inputted into the light guiding plate to a direction of the display unit, the light adjusting means being positioned adjacent to the display unit.

14. A back light assembly for a display device, comprising:

a light source; and

a light guiding plate positioned at a side of the light source, the light guiding plate including a light incident surface for receiving a light from the light source, a side surface positioned in opposite to the light incident surface, a light output surface for outputting the light, and a rear surface positioned in opposite to the light output surface, the rear surface being formed with a light diffusing portion for uniformly outputting the light generated from the light source towards the light output surface, the light guiding plate being formed at an inner portion thereof with a light dispersing member for dispersing the light inputted into the light guiding plate.

15. The back light assembly as claimed in claim 14, further comprising a reflection plate for reflecting the light leaking from the rear surface towards the light output surface, the reflection plate being positioned at a lower portion of the light guiding plate.

16. The back light assembly as claimed in claim 14, further comprising a light adjusting means for focusing the light outputted from the light guiding plate, the light adjusting means being positioned adjacent to the light output surface of the light guiding plate.