Liquid crystal display device
View Patent ↗A liquid crystal display device of a transverse electric field type has characteristics in the following respects. A liquid crystal layer is sandwiched between two substrates. Two polarizing plates are provided on a side of the two substrates opposite to the liquid crystal layer such that the light transmission axes thereof are orthogonal to each other. A first electrode and a second electrode are formed on one of the two substrates. The liquid crystal is driven by an electric field generated between the first electrode and the second electrode. The polarizing plate, formed on one of the two substrates, is formed of a protective film, a polarizer, and two negative biaxial films. The two negative biaxial films include first and second negative biaxial films. The first negative biaxial film and the second negative biaxial film are entirely overlapped, and are disposed on a side of one or the other substrate.
1. A liquid crystal display device of a transverse electric field type, comprising:
a pair of substrates;
a liquid crystal layer sandwiched between the pair of substrates;
a pair of polarizing plates provided on a side of the pair of substrates opposite to the liquid crystal layer such that the light transmission axes of the pair of polarizing plates are orthogonal to each other;
a first electrode;
a second electrode;
wherein the first electrode and the second electrode are formed on a first substrate of the pair of substrates; the liquid crystal layer is driven by an electric field generated between the first electrode and the second electrode;
one of the pair of the polarizing plates, which is formed on the first substrate, is formed of a protective film, a polarizer, and two negative biaxial films; the two negative biaxial films include a first negative biaxial film and a second negative biaxial film; and the first negative biaxial film and the second negative biaxial film are overlapped and disposed on a side of the first substrate or a second substrate of the pair of substrates,
wherein the first negative biaxial film satisfies a relationship of nx>ny>nz, and wherein nx, ny and nz represent refractive indices of the respective axis directions, d represents a thickness of a retardation plate, an in-plane phase difference Ro thereof is represented by 0 nm<(nx−ny)*d ≦20 nm, and a large-thickness-direction phase difference Rth thereof is represented by 50 nm ≦{(nx+ny)/2−nz}*d≦100 nm, and
wherein the second negative biaxial film satisfies a relationship of nx>nz>ny, an in-plane phase difference Ro thereof is represented by 100 nm≦(nx−ny)*d≦200 nm, and a birefringence coefficient Nz thereof represented by (nx−nz)/(nx−ny) is in a range of 0 to 0.3.
2. The liquid crystal display device according to claim 1 , wherein the first negative biaxial film is disposed on a side of a polarizer of the polarizing plate, an optical axis of the second negative biaxial film is set to be parallel with an initial orientation direction of the liquid crystal, and an optical axis of the first negative biaxial film is set to be parallel with or be orthogonal to the initial orientation direction of the liquid crystal.
3. The liquid crystal display device according to claim 1 , wherein the second negative biaxial film is disposed on a side of a polarizer of the polarizing plate, an optical axis of the second negative biaxial film is set to be orthogonal to an initial orientation direction of the liquid crystal, and an optical axis of the first negative biaxial film is set to be parallel with or be orthogonal to the initial orientation direction of the liquid crystal.
4. The liquid crystal display device according to claim 1 , wherein both the first negative biaxial film and the second negative biaxial film are formed of a stretched film such as triacetyl cellulose, polycarbonate, or polynorbornene.