Liquid crystal display device with 2 adjacent biaxial retardation plates having Ny <Nz <Nx

Claim 1

A liquid crystal display device of a twisted nematic type, comprising: a pair of substrates having opposing surfaces on which electrodes and aligning films covering said electrodes are respectively formed, said aligning films having undergone aligning treatment in predetermined directions; a liquid crystal material existing between said pair of substrates and having molecules twisted at an angle of about 90° from one substrate to the other substrate of said pair of substrates; a polarizer having a polarizing axis and arranged on an incident side of a liquid crystal cell, the liquid crystal cell being composed of said pair of substrates and said liquid crystal material; an analyzer having a polarizing axis and arranged on an exit side of said liquid crystal cell; and two biaxial retardation plates arranged on one side of said liquid crystal cell between said polarizer and said analyzer and having a refractive index n X in an extending direction of said retardation plate, a refractive index n Y in a direction perpendicular to the extending direction, and a refractive index n Z in a direction of thickness, which satisfy n Y <n Z <n X , the directions being perpendicular to each other, each of said retardation plates having a phase delay axis, and wherein: a relationship between said polarizing axis of said polarizer and a direction of the aligning treatment of an adjacent one of the aligning films is one of the following: (a) perpendicular to each other, and (b) parallel with each other; a relationship between said polarizing axis of said analyzer and a direction of the aligning treatment of the other of the aligning films is one of the following: (a) perpendicular to each other, and (b) parallel with each other; a relationship between the phase delay axis of each of said biaxial retardation plates and the polarizing axis of an adjacent one of said polarizer and analyzer is one of the following: (a) perpendicular to each other, and (b) parallel with each other; a product Δn·d of a refractive index anisotropy Δn and a thickness d of each of said biaxial retardation plates falls within a range of approximately 200 to 600 nm; and a product of Δn·d of a refractive index anisotropy Δn and a thickness d of said liquid crystal material falls within a range of approximately 350 to 700 nm.