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US 6,285,430 B1Granted
Liquid crystal display device
AssigneeInternational Business Machines Corporation
InventorYukito Saito
Life of this patent
Estimating the term…
Abstract
This LCD cell device configuration reduces the deterioration in contrast when the display surface of the active matrix type liquid crystal display device of the in-plane switching mode is viewed from the direction of azimuth 45° without decreasing the viewing characteristic from a frontal direction. This is accomplished using an optical compensation film having a retardation axis which is parallel to or vertical to the transmission axes of the polarizer plates at the lower and upper side. By so selecting the in-plane retardation and the retardation in the thickness direction of the optical compensation film, the optical compensation film performs the function of a λ/2 plate, to rotate the polarizing plane of the transmitted light.
Claims11
A liquid crystal display device comprising:
- a first polarizer plate, a first substrate, a liquid crystal layer, a second substrate and a second polarizer plate disposed in this order;
- an active matrix drive electrode group including a plurality of pairs of electrodes, each pair of which is assigned to one pixel, formed on a surface, which is adjacent to said liquid crystal layer, of one of said first substrate and said second substrate;
- and
- an optical compensation film disposed between said first polarizer plate and said first substrate;
- wherein one of said first polarizer plate and said second polarizer plate has a transmission axis which is parallel to a liquid crystal retardation axis of said liquid crystal layer in a state displaying a black, and the other has a transmission axis which is perpendicular to said liquid crystal retardation axis;
- and
- wherein a smaller angle of angles formed by a film retardation axis of said optical compensation film and said transmission axis of one of said first polarizer plate and said second polarizer plate is 0°˜2° or 88°˜90° wherein an in-plane retardation of said optical compensation film is 190 nm˜390 nm and a retardation in a direction of thickness of said optical compensation film is 0.3˜0.65.
4 more elements
A liquid crystal display device comprising:
- a first polarizer plate, a first substrate, a liquid crystal layer, a second substrate and a second polarizer plate disposed in this order;
- an active matrix drive electrode group including a plurality of pairs of electrodes, each pair of which is assigned to one pixel, formed on a surface, which is adjacent to said liquid crystal layer, of one of said first substrate and said second substrate;
- and
- an optical compensation film disposed between said first polarizer plate and said first substrate;
- wherein one of said first polarizer plate and said second polarizer plate has a transmission axis which is parallel to a liquid crystal retardation axis of said liquid crystal layer in a state displaying a black, and the other has a transmission axis which is perpendicular to said liquid crystal retardation axis;
- wherein a smaller angle of angles formed by a film retardation axis of said optical compensation film and said transmission axis of one of said first polarizer plate and said second polarizer plate is 0°˜2° or 88°∞90°;
- and
- wherein an in-plane retardation of said optical compensation film is
- {190+4 Δnz} nm˜{390+4 Δnz} nm,
- wherein saix Δn is an average value of retardations in a vertical direction of said dirst and second polarizer plates;
- and
- a retardation in a direction of thickness of said optical compensation film is
- {0.3+0.005 Δnz} nm˜{0.65+0.005 Δnz} nm (in the case of Δnz<20 nm), and
- {0.2+0.01 Δnz} nm˜{0.55+0.01 Δnz} nm (in the case of Δnz≧20 nm).
11 more elements
A liquid crystal display device comprising:
- a first polarizer plate, a first substrate, a liquid crystal layer, a second substrate and a second polarizer plate disposed in this order wherein one of said first polarizer plate and said second polarizer plate has a transmission axis which is parallel to a liquid crystal retardation axis of said liquid crystal layer in a black displaying state, and the other has a transmission axis which is perpendicular to said liquid crystal retardation axis;
- an active matrix drive electrode group including a plurality of pairs of electrodes, each pair of which is assigned to one pixel, formed on a surface, which is adjacent to said liquid crystal layer, of one of said first substrate and said second substrate to provide an in-plane switching (IPS) mode for the liquid crystal layer;
- an optical compensation film configured as a λ/2 plate to rotate the polarizing plane of transmitted light which optical compensation film is disposed between said first polarizer plate and said first substrate with a smaller angle of angles formed by a film retardation axis of said optical compensation film and said transmission axis of one of said first polarizer plate and said second polarizer plate between 0°˜2° or 88°˜90° to improve contrast in the 45° directions relative to the transmission axes of the first and second polarizer plates.
Dependencies are inferred from the claim text.