LIQUID CRYSTAL PANEL AND LIQUID CRYSTAL DISPLAY APPARATUS

• US 20090231517A1
• Filed: 04/05/2007
• Published: 09/17/2009
• Est. Priority Date: 05/09/2006
• Status: Active Grant

• Current Assignee: Nitto Denko Corporation
• Original Assignee: Nitto Denko Corporation
• Inventors: Shiraogawa, Miki, Inagaki, Junichi
• Granted Patent: US 7,777,836 B2
• Time in Patent Office: Days
• US Class Current: 349/75
• CPC Class Codes: G02F 1/133632 with refractive index ellipsoid inclined relative to the LC-layer surface
• CPC Class Codes: G02F 1/133633 using mesogenic materials
• 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
• CPC Class Codes: G02F 2413/105 with varying inclination in thickness direction, e.g. hybrid oriented discotic LC

Abstract

There is provided a liquid crystal display apparatus having a high contrast ratio in an oblique direction and small color change depending upon a viewing angle.

A liquid crystal panel according to an embodiment of the present invention includes: a liquid crystal cell; a first polarizer placed on one side of the liquid crystal cell; a second polarizer placed on the other side of the liquid crystal cell; a first O-plate placed between the liquid crystal cell and the first polarizer; a second O-plate placed between the liquid crystal cell and the second polarizer; a first biaxial retardation layer placed between the liquid crystal cell and the first O-plate; and a second biaxial retardation layer placed between the liquid crystal cell and the second O-plate. The first and the second O-plates are solidified layers or cured layers of a bar-shaped liquid crystal compound arranged in a hybrid alignment; and a tilt angle (θ_P) of the bar-shaped liquid crystal compound on the polarizer side is larger than a tilt angle (θ_B) thereof on the biaxial retardation layer side.

Claims

1. A liquid crystal panel, comprising:

a liquid crystal cell;

a first polarizer placed on one side of the liquid crystal cell;

a second polarizer placed on the other side of the liquid crystal cell;

a first O-plate placed between the liquid crystal cell and the first polarizer;

a second O-plate placed between the liquid crystal cell and the second polarizer;

a first biaxial retardation layer placed between the liquid crystal cell and the first O-plate; and

a second biaxial retardation layer placed between the liquid crystal cell and the second O-plate, wherein;

the first and the second O-plates are solidified layers or cured layers of a bar-shaped liquid crystal compound arranged in a hybrid alignment; and

a tilt angle (θ

_P) of the bar-shaped liquid crystal compound on the polarizer side is larger than a tilt angle (θ

_B) thereof on the biaxial retardation layer side.

2. A liquid crystal panel according to claim 1, wherein a difference (θ

_P−

θ

_B) between the tilt angle (θ

_P) of the bar-shaped liquid crystal compound on the polarizer side and the tilt angle (θ

_B) thereof on the biaxial retardation layer side is 20°

to 90°

.

3. A liquid crystal panel according to claim 1, wherein the tilt angle (θ

_P) of the bar-shaped liquid crystal compound on the polarizer side is 20°

to 90°

.

4. A liquid crystal panel according to claim 1, wherein:

the liquid crystal cell includes a liquid crystal layer, a first substrate placed on the liquid crystal layer on the first polarizer side, and a second substrate placed on the liquid crystal layer on the second polarizer side; and

the first substrate and the second substrate respectively have an alignment film on the liquid crystal layer side.

5. A liquid crystal panel according to claim 4, wherein the liquid crystal layer contains liquid crystal molecules arranged in a twist alignment in the absence of an electric field.

6. A liquid crystal panel according to claim 1, wherein an absorption axis of the first polarizer is substantially perpendicular to an absorption axis of the second polarizer.

7. A liquid crystal panel according to claim 1, wherein a slow axis of the first O-plate is substantially parallel to the absorption axis of the first polarizer, and a slow axis of the second O-plate is substantially parallel to the absorption axis of the second polarizer.

8. A liquid crystal panel according to claim 1, wherein a direction in which a director direction of the bar-shaped liquid crystal compound is projected onto the liquid crystal cell surface is substantially the same as an alignment treatment direction of the liquid crystal cell.

9. A liquid crystal panel according to claim 1, wherein an in-plane retardation value (Re[590]) at a wavelength of 590 nm of the first O-plate and/or the second O-plate is 50 nm to 200 nm.

10. A liquid crystal panel according to claim 1, wherein the slow axis of the first biaxial retardation layer is substantially perpendicular to the absorption axis of the first polarizer, and the slow axis of the second biaxial retardation layer is substantially perpendicular to the absorption axis of the second polarizer.

11. A liquid crystal panel according to claim 1, wherein an in-plane retardation value (Re[590]) at a wavelength of 590 nm of the first biaxial retardation layer and/or the second biaxial retardation layer is 50 nm to 200 nm.

12. A liquid crystal panel according to claim 1, wherein an Nz coefficient of the first biaxial retardation layer and/or the second biaxial retardation layer is 1.1 to 6.0.

13. A liquid crystal panel according to claim 1, wherein the first biaxial retardation layer and/or the second biaxial retardation layer includes a retardation film containing norbornene-based resin.

14. A liquid crystal display apparatus, comprising the liquid crystal panel according to claim 1.