Phase difference plate, and circularly polarizing plate, liquid crystal display device, and organic EL display device provided with same

Abstract

Provided is a phase difference plate provided with: a first optically anisotropic layer in which a rod-like liquid crystal compound is aligned with the thickness direction as the spiral axis and which has an in-plane phase difference value (Re) substantially equal to 1/2 wavelength; and a second optically anisotropic layer which is an optically anisotropic layer in which the rod-like liquid crystal compound is aligned with the thickness direction as a spiral axis and which has an in-plane phase difference (Re) substantially equal to 1/4 wavelength. Wherein a third optically anisotropic layer, which satisfies the following formula (1), is provided between the first and second optically anisotropic layers: nxnult; nz (1) (In the formula, nx and ny represent refractive indexes in orthogonal plate plane directions, and nz represents a refractive index in a direction perpendicular to the plate plane direction).

Description

technical field [0001] The present invention relates to a retardation plate useful for a liquid crystal display device and an organic EL display device, and a circularly polarizing plate, a liquid crystal display device, and an organic EL display device having the retardation plate. Background technique [0002] The retardation plate for circularly polarizing plates is used in a wide range of applications for flat-panel displays. [0003] Conventionally, with regard to image display panels and the like, there has been proposed a method of arranging a circular polarizer on the surface of the image display panel, and reducing reflection of external light by the circular polarizer. This circular polarizing plate is composed of a linear polarizing plate and a 1 / 4 wavelength retardation plate (hereinafter also referred to as a λ / 4 plate). The linear polarizing plate converts the external light toward the display surface of the image display panel into linear polarized light. , a...

AI Technical Summary

Problems solved by technology

[0004] The retardation plate used in this circular polarizing plate has conventionally had the following problem due to the wavelength dependence (wavelength dispersion) of the retardation value: when used to prevent reflection of an organic EL display device, the retardation plate for each wavelength in the visible light region The band does not function as a λ / 4 plate, and produces coloration in a dark state (black screen)

The above problems become especially noticeable when viewing the display device with an oblique viewing angle

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