CIRCULARLY POLARIZED LIGHT SEPARATING PLATE, ITS PRODUCTION, OPTICAL ELEMENT, POLARIZATION LIGHT SOURCE DEVICE AND LIQUID CRYSTAL DISPLAY DEVICE

摘要

PROBLEM TO BE SOLVED: To provide a circularly polarized light separating plate which exhibits a wide band of reflection wavelengths regions with a smaller number of superposition of cholesteric liquid crystal polymers(CLCP) layers by superposing these layers without the intervention of adhesive layers. SOLUTION: This circularly polarized light separating plate 1 is produced by forming the tightly adhered laminate of >=2 layers of the CLCP layers 11, 12 varying in spiral pitches between the upper and layer layers by an operation to coat the surface of the oriented CLCP layer with another kind of CLCP and subjecting both layers to a heating orientation treatment or an adhering operation of adhering the oriented CLCP layers to each other by thermal press bonding or interposing a volatile liquid or the volatile liquid dissolved in a liquid crystal polymer therebetween. The circularly polarized light separating plate of the spiral pitch changing in multiple stages in the thickness direction is produced by having the CLCP layer which is formed by mixing the CLCPs forming the upper and lower layers and varies in the spiral pitch between the upper layer and lower layer at the tight contact boundary of the tight contact laminate described above. The optical element is formed by providing the separating plate described above with a quarter-wave plate and/or polarizing plate. The polarization light source device has the separating plate or the optical element on a light transmission plate. The liquid crystal display device has the polarization light source device described above on the visible rear surface side of the liquid crystal cell.