Polarizing plate comprising a polarizer and a retardation layer
Provided are a polarizing plate and a display. The illustrative polarizing plate may exhibit desired characteristics in a wide range of wavelengths, and have excellent reflection and visibility at an inclined angle. For example, the polarizing plate may be used in a reflective or transflective liquid crystal display or an organic light emitting device.
1. A polarizing plate for minimizing reflecting properties in an organic light emitting device, comprising:
a polarizer; and
a retardation layer that is laminated on one side of the polarizer, wherein a reflectivity measure on a side of the polarizer of the polarizing plate is 12% or less at an inclined angle of 50 degrees and the inclined angle is an angle between a normal line of a surface of a polarizing plate and an observation direction,
wherein the retardation layer comprises a negative biaxial retardation film having a first Rth value according to formula 6, and a C plate having a second Rth value according to formula 6, wherein the sum of the first and second Rth values is from 10 nm to 300 nm, and an angle between a slow axis of the negative biaxial retardation film and a light absorption axis of the polarizer is from 40 degrees to 50 degrees,
R th= d ×( Nz−Ny ) [Formula 6]
in Formula 6, d is a thickness of the negative biaxial retardation film or C plate, and Ny and Nz are refractive indexes in y and z axes of the negative biaxial retardation film or C plate, respectively, wherein the y axis is a direction parallel to a fast axis of the negative biaxial retardation film or C plate and z axis is a normal direction of a plane formed by the x and y axes, wherein the x axis may be a direction parallel to a slow axis of the negative biaxial retardation film or C plate, and
wherein one of the negative biaxial retardation film and the C plate contacts the polarizer.
2. The polarizing plate according to claim 1 , of which a reflectivity measure on a side of the polarizer of the polarizing plate at all radial angles measured at the inclined angle of 50 degrees is 12% or less.
3. The polarizing plate according to claim 1 , wherein the retardation layer satisfies the following Formula 7;
R (450)/ R (550)< R (650)/ R (550) [Formula 7]
where R(450) is in-plane retardation of the retardation layer with respect to light having a wavelength of 450 nm, R(550) is in-plane retardation of the retardation layer with respect to light having a wavelength of 550 nm, and R(650) is in-plane retardation of the retardation layer with respect to light having a wavelength of 650 nm.
4. The polarizing plate according to claim 1 , wherein the C plate is disposed closer to the polarizer than the negative biaxial retardation film, when the retardation layer comprises the negative biaxial retardation film and the C plate.
5. The polarizing plate according to claim 4 , wherein the sum of a thickness-direction retardation of the C plate and a thickness-direction retardation of the negative biaxial retardation film is from 70 nm to 250 nm.
6. The polarizing plate according to claim 1 , wherein the negative biaxial retardation film is disposed closer to the polarizer than the C plate, when the retardation layer comprises the negative biaxial retardation film and the C plate.
7. The polarizing plate according to claim 6 , wherein the sum of a thickness-direction retardation of the C plate and a thickness-direction retardation of the negative biaxial retardation film is from 50 nm to 250 nm.
8. A display comprising the polarizing plate of claim 1 .
9. The display according to claim 8 comprising an organic light emitting device.