Compensation film, and optical film and display device including the same
A compensation film includes a first retardation layer comprising a polymer having negative birefringence, and a second retardation layer comprising a polymer having negative birefringence, where the first retardation layer has an in-plane retardation (R e1 ) in a range of about 180 nanometers to about 300 nanometers for incident light having a wavelength of about 550 nanometers, the second retardation layer has an in-plane retardation (R e2 ) in a range of about 60 nanometers to about 170 nanometers for the incident light having the wavelength of about 550 nanometers, and the entire in-plane retardation (R e0 ) of the first retardation layer and the second retardation layer for incident light having wavelengths of about 450 nanometers and about 550 nanometers satisfies the following inequation: R e0 (450 nm)<R e0 (550 nm).
1. A compensation film comprising:
a first retardation layer comprising a polymer, and
a second retardation layer comprising a polymer,
wherein
the first retardation layer has an in-plane retardation (R e1 ) in a range of about 180 nanometers to about 300 nanometers for incident light having a wavelength of about 550 nanometers,
the second retardation layer has an in-plane retardation (R e2 ) in a range of about 60 nanometers to about 170 nanometers for the incident light having the wavelength of about 550 nanometers,
an entire in-plane retardation (R e0 ) of the first retardation layer and the second retardation layer for incident light having wavelengths of about 450 nanometers and about 550 nanometers satisfies the following inequation: R e0 (450 nm)<R e0 (550 nm),
the first retardation layer comprises an elongated polymer film comprising the polymer of the first retardation layer,
refractive indices of the first retardation layer satisfy the following Inequation: n x1 <n y1 ≤n z1 or n x1 <n z1 ≤n y1 , wherein n x1 denotes a refractive index in an elongation direction of the polymer film of the first retardation layer, n y1 denotes an in-plane refractive index in a direction perpendicular to a direction of the n x1 , and n z1 denotes an out-of-plane refractive index in a direction perpendicular to both directions of n x1 and n y1 ,
the second retardation layer comprises an elongated polymer film comprising the polymer of the second retardation layer, and
refractive indices of the second retardation layer satisfy the following inequation: n x2 <n y2 ≤n z2 , or n x2 <n z2 ≤n y2 , wherein n x2 denotes a refractive index in an elongation direction of the polymer film of the second retardation layer, n y2 denotes an in-plane refractive index in a direction perpendicular to a direction of the n x2 , and n z2 denotes an out-of-plane refractive index in a direction perpendicular to both directions of n x2 and n y2 .
2. The compensation film according to claim 1 , wherein the entire in-plane retardation (R e0 ) of the first retardation layer and the second retardation layer for the incident light having the wavelengths of about 450 nanometers and about 550 nano meters satisfies the following inequation: 0.7≤R e0 (450 nm)/R e0 (550 nm)<1.0.
3. The compensation film according to claim 1 , wherein an angle between a slow axis of the first retardation layer and a slow axis of the second retardation layer is from about 20° to about 85°.
4. The compensation film according to claim 1 , wherein an angle between a slow axis of the first retardation layer and a slow axis of the second retardation layer is from about 25° to about 80°.
5. The compensation film according to claim 1 , wherein an angle between a slow axis of the first retardation layer and a slow axis of the second retardation layer is from about 30° to about 70°.
6. The compensation film according to claim 1 , wherein an angle between a fast axis of the first retardation layer and a fast axis of the second retardation layer is from about 20° to about 80°.
7. The compensation film according to claim 1 , wherein an angle between a fast axis of the first retardation layer and a fast axis of the second retardation layer may be from about 25° to about 75°.
8. The compensation film according to claim 1 , wherein each of the polymer of the first retardation layer and the polymer of the second retardation layer independently comprises at least one of polystyrene, poly(styrene-co-maleic anhydride), polymaleimide, poly(meth)acrylic acid, polyacrylonitrile, polymethyl(meth)acrylate, cellulose ester, poly(styrene-co-acrylonitrile), poly(styrene-co-maleimide), poly(styrene-co-methacrylic acid), a derivative thereof, a copolymer thereof, and a mixture thereof.
9. The compensation film according to claim 1 , wherein
the first retardation layer has an in-plane retardation (R e1 ) in a range of about 200 nanometers to about 280 nanometers for the incident light having the wavelength of about 550 nanometers, and
the second retardation layer has an in-plane retardation (R e2 ) in a range of about 80 nanometers to about 150 nanometers for the incident light having the wavelength of about 550 nanometers.
10. An optical film comprising:
a polarizer; and
the compensation film according to claim 1 .
11. A display device comprising:
a display panel;
a compensation film disposed on the display panel; and
a polarizer disposed on the compensation film,
wherein the compensation film comprises:
a first retardation layer comprising a polymer; and
a second retardation layer comprising a polymer,
wherein
the first retardation layer has an in-plane retardation (R e1 ) in a range of about 180 nanometers (nm) to about 300 nm for incident light having a wavelength of about 550 nm,
the second retardation layer has an in-plane retardation (R e2 ) in a range of about 60 nm to about 170 nm for the incident light having the wavelength of about 550 nm,
an entire in-plane retardation (R e0 ) of the first retardation layer and the second retardation layer for the incident light having wavelengths of about 450 nm and about 550 nm satisfies the following inequality: R e0 (450 nm)<R e0 (550 nm),
the first retardation layer comprises an elongated polymer film comprising the polymer of the first retardation layer,
refractive indices of the first retardation layer satisfy the following inequation: n x1 <n y1 ≤n z1 or n x1 <n z1 ≤n y1 , wherein n x1 denotes a refractive index in an elongation direction of the polymer film of the first retardation layer, n y1 denotes an in-plane refractive index in a direction perpendicular to a direction of the n x1 , and n z1 denotes an out-of-plane refractive index in a direction perpendicular to both directions of n x1 and n y1 ,
the second retardation layer comprises an elongated polymer film comprising the polymer of the second retardation layer, and
refractive indices of the second retardation layer satisfy the following inequation: n x2 <n y2 ≤n z2 or n x2 <n z2 ≤n y2 , wherein n x2 denotes a refractive index in an elongation direction of the polymer film of the second retardation layer, n y2 denotes an in-plane refractive index in a direction perpendicular to a direction of the n x2 , and n z2 denotes an out-of-plane refractive index in a direction perpendicular to both directions of n x2 and n y2 .
12. The display device according to claim 11 , wherein the entire in-plane retardation (R e0 ) of the first retardation layer and the second retardation layer for the incident light having the wavelengths of about 450 nm and about 550 nm satisfies the following inequation: 0.7≤R e0 (450 nm)/R e0 (550 nm)<1.0.
13. The display device according to claim 11 , wherein an angle between a slow axis of the first retardation layer and a slow axis of the second retardation layer is from about 20° to about 85°.
14. The display device according to claim 11 , wherein an angle between a slow axis of the first retardation layer and a slow axis of the second retardation layer is from about 25° to about 80°.
15. The display device according to claim 11 , wherein an angle between a fast axis of the first retardation layer and a fast axis of the second retardation layer is from about 20° to about 80°.
16. The display device according to claim 11 , wherein an angle between a fast axis of the first retardation layer and a fast axis of the second retardation layer is from about 25° to about 75°.
17. The device according to claim 11 , wherein each of the polymer of the first retardation layer and the polymer of the second retardation layer independently comprises at least one of polystyrene, poly(styrene-co-maleic anhydride), polymaleimide, poly(meth)acrylic acid, polyacrylonitrile, polymethyl(meth)acrylate, cellulose ester, poly(styrene-co-acrylonitrile), poly(styrene-co-maleimide), poly(styrene-co-methacrylic acid), a derivative thereof, a copolymer thereof, and a mixture thereof.
18. The display device of claim 11 , wherein the display panel is a liquid crystal display panel or an organic light emitting display panel.