Light modulation medium and light modulation method

摘要

A light modulation medium comprises a light modulation element having a pair of substrates and plural light modulation layers arranged between the substrates to form a multilayer structure and made of cholesteric liquid crystal adapted to change the liquid crystal orientation in response to application of a predetermined electric field, in which the ratio of the threshold electric field at which the liquid crystal orientation is moved from a planar state to a focal conic state of a first light modulation layer of the light modulation element to that of a second light modulation layer is not less than 0.3 and the ratio of the dielectric constant in a planar state of liquid crystal orientation of the first light modulation layer to that of the second light modulation layer is not less than 4.