LCD device having an improved viewing angle characteristic
View Patent ↗A LCD device includes a pair of polarizing films sandwiching therebetween a LC cell. The light-incident-side polarizing film includes a polarizing layer and a first retardation film, whereas the light-emitting-side polarizing film includes a polarizing layer and second and third retardation films. A specific combination of the first and third retardation films provides an optical compensation for achieving a lower leakage light and a lower chromaticity shift upon display of a dark state in the LCD device.
1. A polarizing film pair comprising first and second polarizing films including first and second polarizing layers, respectively,
said first polarizing film being associated with a first retardation film disposed between said first polarizing layer and said second polarizing film, said first retardation film having a birefringence characteristic, an in-plane retardation of 0 to 10 nm and a thickness-direction retardation of 0 to 35 nm,
said second polarizing film being associated with second and third retardation films disposed between said second polarizing layer and said first polarizing film,
said second retardation film having a birefringence characteristic, an in-plane retardation of 35 to 245 nm, a first refractive index (n 1 ) along a first in-plane optical axis and a second refractive index (n 2 ) along a second in-plane optical axis where n 1 <n 2 , said second in-plane optical axis being parallel or perpendicular to an absorption axis of said second polarizing layer, and
said third retardation film having a birefringence characteristic, an in-plane retardation of 0 to 15nm, a thickness-direction retardation of 50 to 123 nm, a positive uniaxial optical characteristic, and an optical axis perpendicular to said second polarizing layer, wherein said first retardation film has an in-plane retardation of 0 to 7 nm and a thickness-direction retardation (ni1) of 0 to 17 nm, said third retardation film has an in-plane retardation of 0 to 10 nm and a thickness-direction retardation (nc1), and the following relationship holds:
57.0−0.23 × ni 1+0.11 × ni 1 2 ≦nc 1≦120.0−0.42× ni 1−0.08× ni 1 2 .
2. The polarizing film pair according to claim 1 , wherein said first polarizing film has a first protective layer, said first retardation film and said first protective layer sandwiching therebetween said first polarizing layer, and said second polarizing film has a second protective layer, said second and third retardation films and said second protective layer sandwiching therebetween said second polarizing layer.
3. The polarizing film pair according to claim 1 , wherein said second retardation film is disposed nearer to said first polarizing film than said third retardation film.
4. The polarizing film pair according to claim 1 , wherein said second retardation film is disposed further from said first polarizing film than said third retardation film.
5. A polarizing film pair comprising first and second polarizing films including first and second polarizing layers, respectively,
said first polarizing film being associated with a first retardation film disposed between said first polarizing layer and said second polarizing film, said first retardation film having a birefringence characteristic, an in-plane retardation of 0 to 10 nm and a thickness-direction retardation of 0 to 35 nm,
said second polarizing film being associated with second and third retardation films disposed between said second polarizing layer and said first polarizing film,
said second retardation film having a birefringence characteristic, an in-plane retardation of 35 to 245 nm, a first refractive index (n 1 ) along a first in-plane optical axis and a second refractive index (n 2 ) along a second in-plane optical axis where n 1 <n 2 said second in-plane optical axis being parallel or perpendicular to an absorption axis of said second polarizing layer, and
said third retardation film having a birefringence characteristic, an in-plane retardation of 0 to 15 nm, a thickness-direction retardation of 50 to 123 nm, a positive uniaxial optical characteristic, and an optical axis perpendicular to said second polarizing layer, wherein said first retardation film has a thickness-direction retardation (ni1) of approximately less than 17 nm, said third retardation film has a thickness-direction retardation (nc1), and the following relationship holds:
57.0−0.23× ni 1+0.11× ni 1 2 ≦nc 1≦120.0−0.42× ni 1−0.08× ni 1 2 .
6. The polarizing film pair according to claim 5 , wherein said first polarizing film has a first protective layer, said first retardation film and said first protective layer sandwiching therebetween said first polarizing layer, and said second polarizing film has a second protective layer, said second and third retardation films and said second protective layer sandwiching therebetween said second polarizing layer
7. The polarizing film pair according to claim 5 , wherein said second retardation film is disposed nearer to said first polarizing film than said third retardation film.
8. The polarizing film pair according to claim 5 , wherein said second retardation film is disposed further from said first polarizing film than said third retardation film.