Liquid crystal display device and polarizing plate
Provided is a liquid crystal display in which occurrence of iridescent unevenness is suppressed, even when a film with high level of mechanical properties, chemical resistance and water-barrier properties is used as a polarizer-protective-film. Also, disclosed is a polarizing plate to be used in the liquid crystal display. The liquid crystal display includes a liquid crystal cell, a light source, a first polarizing plate placed between the liquid crystal cell and the light source, and a second polarizing plate placed on a viewer side of the liquid crystal cell. The first polarizing plate includes a polarizer and a first protective film placed on a light source side principal surface of the first protective film, and the first protective film satisfies following relations: (i) 0 nm≦Re 1 ≦3000 nm; (ii) Nz 1 ≧5; and (iii) Rth 1 >2500 nm.
1. A liquid crystal display, comprising:
a liquid crystal cell;
a light source;
a first polarizing plate placed between the liquid crystal cell and the light source; and
a second polarizing plate placed on a viewer side of the liquid crystal cell,
wherein the first polarizing plate comprises a polarizer and a first protective film placed on a light source side principal surface thereof,
wherein, among protective films included in first polarizing plate and the second polarizing plate, only the first protective film satisfies following relations:
(i) 0 nm≦Re 1 ≦3000 nm;
(ii) Nz 1 ≧5; and
(iii) Rth 1 >2500 nm,
wherein Re 1 , Rth 1 and Nz 1 are defined by following equations:
Re 1 =( nx 1 −ny 1 ) d 1 ;
Rth 1 =( nx 1 −nz 1 ) d 1 ; and
Nz 1 =Rth 1 /Re 1 ,
wherein
d 1 represents a thickness of the first protective film,
nx 1 represents a refractive index in a direction of an in-plane slow axis of the protective film,
ny 1 represents a refractive index in a direction of an in-plane fast axis of the protective film, and
nz 1 represents a refractive index in a direction of the thickness of the protective film, and
each refractive index being measured at 23° C. at a measurement wavelength of 590 nm;
wherein light emitted from the light source is incident on the first polarizing plate in the form of substantially natural light with an Im/Ix ratio of 0.90 or more,
wherein Ix and Im represents maximum and minimum, respectively, of light intensity measured by rotating analyzer method, in which analyzer is rotated by 360°.
2. The liquid crystal display according to claim 1 , wherein the first protective film comprises aromatic polyester as a main component.
3. The liquid crystal display according to claim 2 , wherein the aromatic polyester is polyethylene terephthalate or polyethylene naphthalate.
4. The liquid crystal display according to claim 1 , wherein neither reflective polarizing film nor absorptive polarizing film is provided between the light source and the first polarizing plate.
5. The liquid crystal display according to claim 1 , wherein the first polarizing plate has no protective film on a liquid crystal cell side principal surface of the polarizer.
6. The liquid crystal display according to claim 1 , wherein the first polarizing plate further comprises a second protective film on a liquid crystal cell side principal surface of the polarizer.
7. The liquid crystal display according to claim 1 , wherein the first protective film has a haze of less than 10%.