POLARIZING PLATE AND OPTICAL DISPLAY DEVICE
Provided are a polarizing plate and an optical display device comprising same, the polarizing plate comprising: a polarizer and a phase retardation layer laminated on one surface of the polarizer, wherein the phase retardation layer has in-plane phase retardation of 0 nm to 10 nm and thickness-wise phase retardation of −30 nm to −3 nm at a wavelength of 550 nm, and, in the polarizing plate, the light transmittance ratio of equation 1 is greater than 0.445 and less than 0.470 and the light transmittance ratio of equation 2 is greater than 0.710 and less than 0.730.
1 . A polarizing plate comprising: a polarizer; and a retardation layer stacked on one surface of the polarizer,
wherein the retardation layer has an in-plane retardation of 0 nm to 10 nm and an out-of-plane retardation of −30 nm to −3 nm at a wavelength of 550 nm, and the polarizing plate has a light transmittance ratio of greater than 0.445 and less than 0.470, as calculated according to Equation 1, and a light transmittance ratio of greater than 0.710 and less than 0.730, as calculated according to Equation 2:
Light
transmittance
ratio
=
TS
390
/
TS
550
[
Equation
1
]
Light
transmittance
ratio
=
TS
400
/
TS
550
[
Equation
2
]
(in Equation 1 and Equation 2,
TS550 denotes a light transmittance (unit: %) of the polarizing plate at a wavelength of 550 nm,
TS390 denotes a light transmittance (unit: %) of the polarizing plate at a wavelength of 390 nm, and
TS400 denotes a light transmittance (unit: %) of the polarizing plate at a wavelength of 400 nm).
2 . The polarizing plate as claimed in claim 1 , wherein the polarizing plate has a light transmittance of 10% to 20% at a wavelength of 390 nm and a light transmittance of 25% to 35% at a wavelength of 400 nm.
3 . The polarizing plate as claimed in claim 1 , wherein the polarizing plate has a light transmittance ratio of greater than 0.795 and less than 0.805, as calculated according to Equation 3, and a light transmittance ratio of greater than 0.835 and less than 0.850, as calculated according to Equation 4:
Light
transmittance
ratio
=
TS
410
/
TS
550
[
Equation
3
]
Light
transmittance
ratio
=
TS
420
/
TS
550
[
Equation
4
]
(in Equation 3 and Equation 4,
TS550 denotes a light transmittance (unit: %) of the polarizing plate at a wavelength of 550 nm,
TS410 denotes light transmittance (unit: %) of the polarizing plate at a wavelength of 410 nm, and
TS420 denotes light transmittance (unit: %) of the polarizing plate at a wavelength of 420 nm).
4 . The polarizing plate as claimed in claim 1 , wherein the polarizing plate has a light transmittance of 33% to 35% at a wavelength of 410 nm and a light transmittance of 36% to 38% at a wavelength of 420 nm.
5 . The polarizing plate as claimed in claim 1 , wherein the retardation layer is a negative C layer or a positive C layer.
6 . The polarizing plate as claimed in claim 1 , wherein the retardation layer has a higher light transmittance at a wavelength of 390 nm, 400 nm, 410 nm, 420 nm, or 550 nm than the polarizer.
7 . The polarizing plate as claimed in claim 1 , wherein the retardation layer has a light transmittance of 45% to 62% at a wavelength of 390 nm, a light transmittance of 70% to 90% at a wavelength of 400 nm, a light transmittance of 75% to 95% at a wavelength of 410 nm, and a light transmittance of 75% to 95% at a wavelength of 420 nm.
8 . The polarizing plate as claimed in claim 1 , wherein the retardation layer comprises a film or coating layer containing a polymer with a positive inherent birefringence.
9 . The polarizing plate as claimed in claim 1 , wherein the retardation layer comprises triacetylcellulose (TAC), cyclic olefin polymer (COP), or cyclic olefin copolymer (COC).
10 . The polarizing plate as claimed in claim 1 , wherein the retardation layer has a thickness ratio of 90% or more with respect to a thickness of total retardation layers stacked on the lower surface of the polarizer.
11 . The polarizing plate as claimed in claim 1 , wherein a slow axis of the retardation layer is tilted at an angle of −5° to 5° with respect to a light absorption axis of the polarizer, when the light absorption axis of the polarizer is 0°.
12 . The polarizing plate as claimed in claim 1 , further comprising: a second protective layer stacked on the other surface of the polarizer.
13 . The polarizing plate as claimed in claim 12 , wherein the second protective layer has an in-plane retardation of 3,000 nm or more at a wavelength of 550 nm.
14 . An optical display device comprising the polarizing plate as claimed in claim 1 .