Prism sheet, backlight unit and liquid crystal display

• US 7,710,512 B2
• Filed: 09/28/2006
• Issued: 05/04/2010
• Est. Priority Date: 05/09/2006
• Status: Active Grant

• Current Assignee: LG Chem Limited (LG Corporation)
• Original Assignee: LG Electronics, Inc. (LG Corporation)
• Inventors: Lee, Jung Hoon
• Primary Examiner(s): Le; Uyen-Chau N
• Assistant Examiner(s): Peace; Rhonda S
• Application Number:
  US11/528,417
• Publication Number:
  US 20070263412A1
• Time in Patent Office: 1,314 Days
• Field of Search: 349/112, 349/113, 349/61, 349/62, 349/64, 349/65, 349/95, 349/67
• US Class Current: 349/64
• CPC Class Codes: G02B 5/04 Prisms
• 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 6/0053 Prismatic sheet or layer; Brightness enhancement element, sheet or layer
• CPC Class Codes: G02F 1/133606 including a specially adapted diffusing, scattering or light controlling members

Abstract

The present invention relates to a liquid crystal display having excellent brightness without moiré patterns. The present invention also relates to a prism sheet and backlight unit which may improve the brightness of the liquid crystal display while removing the moiré patterns. A prism sheet comprises a protective layer including a base material consisting of a light-transmissive resin; and a plurality of diffusion particles distributed in the protective layer to scatter the light input into the base material; a base film disposed on a surface of the protective layer, wherein the light emitted from the protective layer is input into the base film; and a plurality of linear prisms having a pitch of between about 32 μm and about 38 μm and disposed in parallel on a surface of the base film.

Claims

1. A backlight unit configured to illuminate a liquid crystal panel, comprising:

at least one light source;

at least one prism sheet disposed at the back of the liquid crystal panel; and

a light guide plate including a light incidence surface disposed adjacent to the light source and a light emitting surface disposed substantially in parallel with the prism sheet,

wherein the prism sheet including;

a protective layer including a base material and a plurality of diffusion particles distributed in the base material, wherein the base material includes a light-transmissive resin;

a base film disposed on a surface of the protective layer, wherein the light emitted from the protective layer is input into the base film; and

a plurality of linear prisms disposed in parallel on a surface of the base film,

wherein the diffusion particles comprise a plurality of beads having a size of between about 2 μ

m and about 10 μ

m, and the plurality of linear prisms have a pitch of between about 32 μ

m and about 36 μ

m, and

wherein the at least one prism sheet includes at least two prism sheets disposed in such a manner that the axes of the linear prisms of the two prism sheets are disposed to cross each other.

2. The backlight unit of claim 1, wherein the prism sheet further comprises a prism base disposed between the base film and the plurality of linear prisms.

3. The backlight unit of claim 1, wherein the plurality of beads are substantially of the same size.

4. The backlight unit of claim 1, wherein the cross-section of the linear prism includes an isosceles triangle or a scalene triangle.

5. A liquid crystal display comprising:

a liquid crystal panel displaying images according to electrical signals provided from the outside device; and

a backlight unit configured to illuminate a liquid crystal panel, comprising;

at least one light source;

at least one prism sheet disposed at the back of the liquid crystal panel; and

a light guide plate including a light incidence surface disposed adjacent to the light source and a light emitting surface disposed substantially in parallel with the prism sheet,

wherein the prism sheet including;

a protective layer including a base material and a plurality of diffusion particles distributed in the base material, wherein the base material includes a light transmissive resin;

a base film disposed on a surface of the protective layer, wherein the light emitted from the protective layer is input into the base film; and

a plurality of linear prisms disposed in parallel on a surface of the base film,

wherein the diffusion particles comprise a plurality of beads having a size of between about 2 μ

m and about 10 μ

m, and the plurality of linear prisms have a pitch of between about 32 μ

m and about 36 μ

m, and

wherein the at least one prism sheet includes at least two prism sheets disposed in such a manner that the axes of the linear prisms of the two prism sheets are disposed to cross each other.

6. The liquid crystal display of claim 5, wherein the plurality of beads are substantially of the same size.

7. The liquid crystal display of claim 5, wherein the cross-section of the linear prism taken normal to an axis of the linear prism includes an isosceles triangle or a scalene triangle.