POLARIZING PLATE AND LIQUID-CRYSTAL DISPLAY DEVICE

• US 20090195733A1
• Filed: 01/30/2009
• Published: 08/06/2009
• Est. Priority Date: 01/31/2008
• Status: Active Grant

• Current Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Original Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Inventors: Saitoh, Yukito
• Granted Patent: US 8,049,843 B2
• Time in Patent Office: Days
• US Class Current: 349/96
• CPC Class Codes: G02B 5/3016 involving passive liquid crystal elements optical properties of liquid crystals G02F1/0063; polarising elements associated with active liquid crystal devices G02F1/133528
• CPC Class Codes: G02B 5/3033 in the form of a thin sheet or foil, e.g. Polaroid
• CPC Class Codes: G02F 1/133538 with spatial distribution of the polarisation direction

Abstract

Disclosed is a polarizing plate comprising at least first and second polarizing elements and satisfying (1) kx₁>ky₁=kz₁, (2) kz₂>ky₂ and (3) (kx₁−ky₁)×d₁>(kz₂−ky₂)×d₂, wherein an x-axis and a y-axis are in-plane axes crossing perpendicularly to each other, and a z-axis is the axis crossing perpendicularly to the x-y axis plane; kx₁, ky₁ and kz₁ each are the absorption coefficient in the x-axis, y-axis and z-axis directions, respectively, of the first polarizing element; ky₂ and kz₂ each are the absorption coefficient in the y-axis and z-axis directions, respectively, of the second polarizing element; and d₁ and d₂ each are the thickness (unit: nm) of the first and second polarizing elements, respectively.

Claims

1. A polarizing plate comprising at least first and second polarizing elements and satisfying following formulae (1) to (3):

kx₁>

ky₁=kz₁  

 

(1)

kz₂>

ky₂  

 

(2)

(kx₁−

ky₁)×

d₁>

(kz₂−

ky₂)×

d₂  

 

(3)

wherein an x-axis and a y-axis are in-plane axes crossing perpendicularly to each other, and a z-axis is the axis crossing perpendicularly to the x-y axis plane;

kx₁, ky₁ and kz₁ each are the absorption coefficient in the x-axis, y-axis and z-axis directions, respectively, of the first polarizing element;

ky₂ and kz₂ each are the absorption coefficient in the y-axis and z-axis directions, respectively, of the second polarizing element; and

d₁ and d₂ each are the thickness (unit;

nm) of the first and second polarizing elements, respectively.

2. The polarizing plate of claim 1, wherein the second polarizing element satisfies following formula (2a):

kz₂>

kx₂=ky₂

wherein kx₂ is the absorption coefficient in the x-axis direction of the second polarizing element.

3. The polarizing plate of claim 2, wherein the second polarizing element satisfies following formula:

5 nm≦

(kz₂−

ky₂)×

d₂≦

80 nm.

4. The polarizing plate of claim 1, wherein the second polarizing element satisfies following formula (2b):

kz₂=kx₂>

ky₂  

 

(2b)

wherein kx₂ is the absorption coefficient in the x-axis direction of the second polarizing element.

5. The polarizing plate of claim 4, wherein the second polarizing element satisfies following formula:

5 nm≦

(kz₂−

ky₂)×

d₂≦

100 nm.

6. The polarizing plate of claim 1, wherein the second polarizing element comprises molecules having absorption anisotropy for visible light.

7. A liquid-crystal display device comprising at least a liquid-crystal cell and a polarizing plate as set forth in claim 1.