Backlight unit and liquid crystal display module including the same

• US 8,212,964 B2
• Filed: 12/18/2008
• Issued: 07/03/2012
• Est. Priority Date: 04/16/2008
• Status: Active Grant

• Current Assignee: LG Display Co., Ltd.
• Original Assignee: LG Display Co., Ltd.
• Inventors: Yun, Seong-Hyun
• Primary Examiner(s): CHIEN, LUCY P
• Application Number:
  US12/338,804
• Publication Number:
  US 20090262281A1
• Time in Patent Office: 1,293 Days
• Field of Search: None
• US Class Current: 349/64
• CPC Class Codes: G02F 1/133606 including a specially adapted diffusing, scattering or light controlling members
• CPC Class Codes: G02F 1/133607 the light controlling member including light directing or refracting elements, e.g. prisms or lenses

Abstract

A backlight unit includes a reflection sheet, lamps arranged over the reflection sheet and with a first distance between adjacent lamps, a first diffuser plate disposed over the lamps and spaced apart from the reflection sheet with a second distance, the first diffuser plate having a first surface facing the reflection sheet and a second surface opposite to the first surface, wherein the first surface is flat and the second surface includes first patterns, and a second diffuser plate disposed over the first diffuser plate, the diffuser plate having a third surface facing the first diffuser plate and a fourth surface opposite to the third surface, wherein the third surface is flat and the second surface includes second patterns, wherein a ratio of the first distance over the second distance is within a range of more than 0 and less than and/or equal to 2.75.

Claims

1. A backlight unit, comprising:

a reflection sheet;

a plurality of lamps arranged over the reflection sheet and with a first distance between adjacent lamps;

a first diffuser plate disposed over the plurality of lamps and spaced apart from the reflection sheet with a second distance, the first diffuser plate having a first surface facing the reflection sheet and a second surface opposite to the first surface, wherein the first surface is flat and the second surface includes first patterns; and

a second diffuser plate disposed over the first diffuser plate, the diffuser plate having a third surface facing the first diffuser plate and a fourth surface opposite to the third surface, wherein the third surface is flat and the second surface includes second patterns,

wherein a ratio of the first distance over the second distance is within a range of more than 1.35 and less than and/or equal to 2.75,

wherein ones of the first patterns and the second patterns have lenticular lenses, and others of the first patterns and the second patterns have prisms, and wherein each of the prisms has an unevenness at a peak along a first direction parallel to the lamps.

2. The backlight unit according to claim 1, wherein the prisms have a same height.

3. The backlight unit according to claim 1, wherein adjacent prisms have different heights.

4. The backlight unit according to claim 1, wherein each prism has a plurality of heights.

5. The backlight unit according to claim 1, wherein the first patterns and the second patterns have heights of about 20 μ

m to about 500 μ

m and pitches of about 50 μ

m to about 500 μ

m.

6. The backlight unit according to claim 5, wherein the heights of the first patterns are equal to each other and the heights of the second patterns are equal to each other.

7. The backlight unit according to claim 5, wherein the pitches of the first patterns are equal to each other and the pitches of the second patterns are equal to each other.

8. The backlight unit according to claim 1, wherein the lenticular lenses have a bar shape extending along the first direction parallel to the lamps and have a length corresponding to the lamps.

9. The backlight unit according to claim 1, wherein the lenticular lenses are spaced apart from each other along the first direction parallel to the lamps and along a second direction perpendicular to the lamps.

10. The backlight unit according to claim 1, wherein each of the first and second diffuser plates has a thickness of about 0.6 mm to about 3 mm and includes one of PMMA (polymethyl methacrylate), PS (polystyrene), PC (polycarbonate), COC (cyclo-olefin copolymers), PET (polyethylene terephthalate), PBT (polybutylene terephtalate) and plastic alloys.

11. The backlight unit according to claim 1, further comprising a plurality of optical sheets over the second diffuser plate and support sides supporting respective ends of each lamp.

12. A liquid crystal display device, comprising:

a backlight unit including;

a reflection sheet;

a plurality of lamps arranged over the reflection sheet and with a first distance between adjacent lamps;

a first diffuser plate disposed over the plurality of lamps and spaced apart from the reflection sheet with a second distance, the first diffuser plate having a first surface facing the reflection sheet and a second surface opposite to the first surface, wherein the first surface is flat and the second surface includes first patterns; and

a second diffuser plate disposed over the first diffuser plate, the diffuser plate having a third surface facing the first diffuser plate and a fourth surface opposite to the third surface, wherein the third surface is flat and the second surface includes second patterns;

a liquid crystal panel over the backlight unit;

a support main under the liquid crystal panel and over the backlight unit; and

a top case covering edges of an upper surface of the liquid crystal panel and side surfaces of the support main,

wherein a ratio of the first distance over the second distance is within a range of more than 1.35 and less than and/or equal to 2.75,

wherein ones of the first patterns and the second patterns have lenticular lenses, and others of the first patterns and the second patterns have prisms, and wherein each of the prisms has an unevenness at a peak along a first direction parallel to the lamps.

13. The device according to claim 12, wherein the first patterns and the second patterns have heights of about 20 μ

m to about 500 μ

m and pitches of about 50 μ

m to about 500 μ

m.

14. The device according to claim 13, wherein the heights of the first patterns are equal to each other and the heights of the second patterns are equal to each other.

15. The device according to claim 13, wherein the pitches of the first patterns are equal to each other and the pitches of the second patterns are equal to each other.

16. The device according to claim 12, wherein the lenticular lenses have a bar shape extending along the first direction parallel to the lamps and have a length corresponding to the lamps.

17. The device according to claim 12, wherein the lenticular lenses are spaced apart from each other along the first direction parallel to the lamps and along a second direction perpendicular to the lamps.

18. The device according to claim 12, further comprising:

a cover bottom under the reflection sheet;

a plurality of optical sheets over the second diffuser plate;

support sides supporting respective ends of each lamp;

gate and data printed circuit boards connected to the liquid crystal panel; and

an inverter unit connected to the lamps and disposed under the cover bottom.