Transmission type liquid crystal display device

Claim 1

A transmission type liquid crystal display device comprising: a liquid crystal cell having a liquid crystal layer in which a nematic liquid crystal containing an optically active substance and having a positive dielectric anisotropy forms a twisted structure with a twist angle α ranging from 220° to 300° and is disposed between a pair of parallel electrode substrates each having a transparent substrate and provided thereon an electrode layer and an alignment layer so that the respective alignment layers contact the liquid crystal layer; a pair of front and rear polarizing plates each disposed on the side of the substrate opposite to the alignment layers; and a backlight source of illumination including red, green and blue light, said source being disposed on the side of the rear polarizing plate opposite to the substrate, wherein: (1) the produce Δn·d, in which Δn is a refractive anisotropy of the nematic liquid crystal and d is a thickness of the liquid crystal layer, is 0.65 to 0.90 μm; (2) in the relation to the twist angle α, angles β and γ defined by the intersection of polarizing axes of the pair of polarizing plates and the directions of aligning treatments of the alignment layers on the electrode substrates adjacent to the respective polarizing plates, and a correction angle δ satisfy the following Equations (a) and (b): α+β-γ-180°=90°-δ0°<δ<30.degree. Equation (a) β+γ=+90°or -90°; Equation (b) (3) a pretilt angle θ 0 defined by the intersection of the electrode substrate and a director of the nematic liquid crystal molecules contacting the electrode substrate is not less than 10°; (4) luminous intensity ratios of red light to green light and red light to blue light in the backlight source are 1.2 or more; and (5) a luminous intensity of the backlight source is not less than 200 cd/m 2 .