Optical compensation polarizing film achieving a higher viewing angle
View Patent ↗An LCD device includes first and second compensation polarizing films sandwiching therebetween a homogeneously-oriented liquid crystal layer. The first compensation polarizing film includes a polarizing film having an in-plane retardation of 35 to 245 nm, wherein n1≧nz>n2, wherein n1 and n2 are refractive indexes of optical axes extending perpendicular to each other within the first retardation film and nz is a thickness-direction refractive index of the first retardation film. The second compensation polarizing film has a protection layer, a polarizing film and a retardation film having an in-plane retardation of 0 to 10 nm and thickness-direction retardation of 0 to 35 nm.
1. An optical compensation polarizing film pair comprising:
a first compensation polarizing film including a first protecting layer, a first polarizing layer, a first retardation film and a negative-uniaxial second retardation film, which are arranged in this order: and
a second compensation polarizing film used in pair with said first compensation polarizing film and including a second protecting layer, a second polarizing layer, and a third retardation film, which are arranged in this order:
said first retardation film having a birefringence wherein an in-plane retardation is 35 to 245 nm, and refractive indexes therein satisfy the following relationship: n1≧nz>n2, given n1 and n2 being refractive indexes of optical axes extending perpendicular to each other within said first retardation film and given nz being a thickness-direction refractive index of said first retardation film, one of said optical axes of said first retardation film having said refractive index of n1 extending normal to an absorption axis of said first polarizing layer;
said second retardation film having a birefringence wherein an in-plane retardation is 0 to 15 nm, and a thickness-direction retardation is 50 to 123 nm, said second retardation film having an optical axis normal to a surface of said first polarizing layer;
said third retardation film having a birefringence wherein an in-plane retardation is 0 to 10 nm and a thickness-direction retardation is 0 to 35 nm.
2. The optical compensation polarizing film pair according to claim 1 , wherein said in-plane retardation of said second retardation film is 0 to 10 nm, and said thickness-direction retardation nc 1 of said second retardation film satisfying the following relationship:
57.0−0.23 ×nil+ 0.11 ×nil 2 ≦ncl≦ 120.0−0.42 ×nil− 0.08 ×nil 2
for the case where said in-plane retardation of said third retardation film is 0 to 7 nm and said thickness-direction retardation of said third retardation film is 0 to 17 nm.
3. The optical compensation polarizing film pair according to claim 1 , wherein said second retardation film includes a plurality of layers.
4. The optical compensation polarizing film pair according to claim 3 , wherein at least one of said plurality of layers in said second retardation film configures a protection layer protecting said first polarizing layer.
5. The optical compensation polarizing film pair according to claim 4 , wherein said protection layer includes triacetylcellulose (TAC).
6. A liquid crystal display (LCD) device comprising the optical compensation film pair according to claim 1 , and a homogeneously-oriented liquid crystal layer sandwiched between said optical compensation film pair, wherein said first polarizing layer has an absorption axis normal to an absorption axis of said second polarizing layer.
7. The LCD device according to claim 6 , wherein another of said optical axes of said first retardation film having said refractive index of n2 is parallel to an optical axis of said homogeneously-oriented liquid crystal layer.