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AssigneeNitto Denko Corporation
InventorsHiroyuki Yoshimi, Tatsuki Nagatsuka, Yasuo Fujimura, Tatsuya Osuka
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A birefringent film in which molecules oriented in a direction parallel to the film plane and molecules oriented in the direction of the thickness of the film are present in a mixed state. Also, a process for producing the birefringent film, which comprises laminating a resin film on one or both sides thereof with a shrinkable film, thereby preparing a laminate, and then heat stretching the laminate, thereby performing stretching treatment of the resin film while imparting to the resin film the ability to shrink in the direction crossing the stretching direction. A retardation film is formed by using at least one birefringent film and has refractive indexes, n.sub.x and n.sub.y, in two directions parallel to the plate plane and crossing each other at right angles and a refractive index, n.sub.z, in the direction of the thickness of the plate, said refractive indexes n.sub.x, n.sub.y, and n.sub.z satisfying the following equation: 0<(n.sub.x -n.sub.z)/(n.sub.x -n.sub.y)<1 provided that n.sub.x >n.sub.y. Also, an elliptically polarizing plate comprises a laminate of the retardation film with a polarizing plate. Additionally, a liquid crystal display comprises a liquid crystal cell and a polarizing plate disposed at least on one side of said liquid crystal cell through the retardation film.
A birefringent film formed of a single resin in which molecules oriented in a direction parallel to the film plane and molecules oriented in the direction of the thickness of the film are present in a mixed state, which birefringent film has refractive indexes, n.sub.x and n.sub.y, in two directions parallel to the film plane and crossing each other at right angles and a refractive index, n.sub.z, in the direction of the thickness of the film, wherein n.sub.x >n.sub.z >n.sub.y.
A process for producing a birefringent film, which process comprises laminating a resin film on one or both sides thereof with a shrinkable film, thereby preparing a laminate, and then heat stretching the laminate, thereby performing stretching treatment of the resin film while imparting to the resin film the ability to shrink in the direction crossing the stretching direction in which molecules oriented in a direction parallel to the film plane and molecules oriented in the direction of the thickness of the film are present in a mixed state.
Dependencies are inferred from the claim text.