RETARDATION PLATE, ELLIPTICALLY POLARIZING PLATE, DISPLAY DEVICE USING THE SAME, AND POLYMERIZABLE DICHROIC DYE FOR RETARDATION PLATE

摘要

PROBLEM TO BE SOLVED: To provide a retardation plate excellent in optical reliability, which is made of a monolayer film having 'negative dispersion' characteristics in an extraordinary ray refractive index ne or a birefringence Δn while minimizing reduction in the transmittance.SOLUTION: The retardation plate is made of a film comprising a polymer produced by polymerizing a polymerizable liquid crystal composition and at least one type of polymerizable dichroic dye. The polymerizable liquid crystal composition shows homogeneous alignment as liquid crystal alignment. The polymerizable dichroic dye has an absorption maximum wavelength in a region from 400 to 800 nm measurement wavelength, and a ratio of retardation values of the retardation plate at specific wavelengths satisfies expressions (4) 0.80<Δn*d(500)/Δn*d(550)<1.10 and (5) 1.00<Δn*d(580)/Δn*d(550)<1.15, where Δn*d(500), Δn*d(550), and Δn*d(580) represent retardation values of the retardation plate at wavelengths of 500 nm, 550 nm, and 580 nm, respectively.SELECTED DRAWING: Figure 1