LAMINATED OPTICAL FILM, AND LIQUID CRYSTAL PANEL AND LIQUID CRYSTAL DISPLAY APPARATUS USING THE LAMINATED OPTICAL FILM

• US 20090257012A1
• Filed: 03/27/2009
• Published: 10/15/2009
• Est. Priority Date: 04/09/2008
• Status: Active Grant

• Current Assignee: Nitto Denko Corporation
• Original Assignee: Nitto Denko Corporation
• Inventors: BITOU, Masato, KOISHI, Naoki, SABAE, Misaki, TOMONAGA, Masatoshi
• Granted Patent: US 8,587,756 B2
• Time in Patent Office: Days
• US Class Current: 349/118
• CPC Class Codes: G02B 5/3033 in the form of a thin sheet or foil, e.g. Polaroid
• CPC Class Codes: G02B 5/3083 Birefringent or phase retarding elements G02B5/3008, G02B5/3016 take precedence; systems for polarisation control G02B27/286; manufacturing phase modulating patterns by lithographic processes G03F7/001
• CPC Class Codes: G02F 1/133528 Polarisers
• CPC Class Codes: G02F 1/133634 the refractive index Nz perpendicular to the element surface being different from in-plane refractive indices Nx and Ny, e.g. biaxial or with normal optical axis

Abstract

A laminated optical film according to an embodiment of the present invention includes a polarizer; a first optical compensation layer which has a refractive index ellipsoid showing a relationship of nx>ny>nz; and a second optical compensation layer which has a refractive index ellipsoid showing a relationship of nz>nx>ny, wherein the polarizer and the first optical compensation layer are placed so that an absorption axis of the polarizer is parallel to or perpendicular to a slow axis of the first optical compensation layer, and the polarizer and the second optical compensation layer are placed so that an absorption axis of the polarizer is parallel to or perpendicular to a slow axis of the second optical compensation layer.

Claims

1. A laminated optical film, comprising:

a polarizer;

a first optical compensation layer which has a refractive index ellipsoid showing a relationship of nx>

ny>

nz; and

a second optical compensation layer which has a refractive index ellipsoid showing a relationship of nz>

nx>

ny,

wherein the polarizer and the first optical compensation layer are placed so that an absorption axis of the polarizer is parallel to or perpendicular to a slow axis of the first optical compensation layer, and

the polarizer and the second optical compensation layer are placed so that an absorption axis of the polarizer is parallel to or perpendicular to a slow axis of the second optical compensation layer.

2. A laminated optical film according to claim 1, wherein an Nz coefficient of the second optical compensation layer is −

1.0 or less.

3. A laminated optical film according to claim 1, wherein an in-plane retardation Re₂ of the second optical compensation layer satisfies a relationship of 0 nm<

Re₂≦

70 nm.

4. A laminated optical film according to claim 1, further comprising a third optical compensation layer which has a refractive index ellipsoid showing a relationship of one of nx>

ny=nz and nx>

ny>

nz.

5. A laminated optical film according to claim 4, wherein an in-plane retardation Re₃ of the third optical compensation layer is 80 to 200 nm.

6. A laminated optical film according to claim 1, further comprising a fourth optical compensation layer which has a refractive index ellipsoid showing a relationship of nx=ny>

nz.

7. A liquid crystal panel comprising a liquid crystal cell and the laminated optical film according to claim 1.

8. A liquid crystal panel according to claim 7, wherein the liquid crystal cell is in a VA mode.

9. A liquid crystal display apparatus comprising the liquid crystal panel according to claim 7.