Cholesteric liquid crystal layer, and optical element, lighting device and liquid crystal display comprising the same

摘要

The invention, improving the luminance of the liquid crystal display device, and also a phenomenon that looks colored when viewing from an oblique direction is suppressed and the cholesteric liquid crystal layer having excellent viewing angle (viewing angle) characteristic; And to the brightness and visibility it can be formed with superior liquid crystal display device such as an optical element and a lighting device. The cholesteric liquid crystal layer (1) is a quarter-wave plate changes in the direction of the thickness of the helical pitch, and circular dichroism is, a width of 50nm over the wavelength region including a wavelength of 520nm (quarter-wavelength plate) a the linearly polarized light obtained through exhibited a maximum degree of polarization at a wavelength of 520nm or less, it represents a short wavelength side of a high integration degree of polarization than the longer wavelength side than the wavelength of 520nm 520nm more. The relevant optical element includes a multilayer structure consisting of at least one optical layer made of a cholesteric liquid crystal layer and phase difference compensation plate, a polarizing plate, a light guide plate or a quarter-wave plate is Nz of -0.8 to -2.0. The relevant lighting device or liquid crystal display device includes a cholesteric liquid crystal layer or optical element on one side of the surface light source or the liquid crystal cell. ; The cholesteric liquid crystal layer, optical element, the illumination device, the liquid crystal display device