OPTICAL FILM, ITS PRODUCTION, LAMINATED POLARIZING PLATE AND LIQUID CRYSTAL DISPLAY DEVICE

摘要

PROBLEM TO BE SOLVED: To prevent the lowering of visibility caused by the change of a visual angle in a liquid crystal display device and to easily and stably form a large area substance by specifying a phase difference by double refraction in right and left obliquely transmitted light beams on a normal plane based on a specified tilt angle with the normal plane on a phase lagging axis or a phase advancing axis as reference. SOLUTION: As for this optical film 1; the difference of the phase difference by the double refraction in the right and the left obliquely transmitted light beam 12 and 13 on the normal plane 11 is >=50nm in a state where the tilt angle θ with the normal plane 11 in either or both of the phase lagging axis and the phase advancing axis as reference is 40 deg.. The film 1 is produced by a method in which a flay plate is brought into contact with the front and back surfaces of a light transmissive film and different shearing stress is imparted to the front and back surface of the light transmissive film under a heating condition through the flay plate. The liquid crystal display device excellent in the visibility such as contrast or black-and-white display by the film 1 showing asymmetric phase difference characteristic is obtained.