Optical film, brightness enhancement film, backlight unit with brightness enhancement film, and liquid crystal display device

摘要

An optical film having a cholesteric layer of a discotic liquid crystal composition containing a discotic liquid crystal compound, the cholesteric layer exhibiting a cholesteric liquid crystal phase, and the fluctuation of the helical pitch in the film thickness direction of the cholesteric layer is 2% or more A liquid crystal compound having a cholesteric liquid crystal phase and a wide reflection bandwidth; a brightness enhancement film; a backlight unit with a brightness enhancement film; a liquid crystal display device.