Patent ID: 7943392

Claim:
A discrimination medium comprising: a first adhesive layer; a cholesteric liquid crystal layer provided on the first adhesive layer, the cholesteric liquid crystal layer having a circular polarization light selectivity of reflecting predetermined circularly polarized light as a first reflection light, the cholesteric liquid crystal layer having a side to which natural light may enter; a second adhesive layer provided on an outer surface of the cholesteric liquid crystal layer parallel to the first adhesive layer; and a multilayer film provided on the second adhesive layer, the multilayer film having a stacked structure in which a plurality of first light transparent films having a first refraction index and a plurality of second light transparent films having a second refraction index are alternately laminated in a thickness direction, each first light transparent film and the each second light transparent film having an interface therebetween, each interface reflecting light so as to generate interfering light, wherein the cholesteric liquid crystal layer and the multilayer film are arranged in a direction in which natural light may enter, the multilayer film reflects the interfering light as a second reflection light, and the discrimination medium is discriminated by using the first reflection light and the second reflection light, the first reflection light is circularly polarized light having a predetermined center wavelength and a predetermined polarization direction, the second reflection light includes circularly polarized light having a circularly polarized direction opposite to that of the first reflection light, the second reflection light shows a blue shift in which a color of the reflection light is changed when a viewing angle is changed, when the discrimination medium is viewed at a predetermined angle, the first reflection light reflected by the cholesteric liquid crystal layer and the second reflection light reflected by the multilayer film are approximately equal to each other in color, when the discrimination medium is viewed through a circularly polarized light filter allowing the first reflection light to selectively pass therethrough, the second reflection light is not viewed but the first reflection light is selectively viewed, and when the discrimination medium is viewed through a circularly polarized light filter allowing circularly polarized light having a circularly polarized direction opposite to that of the first reflection light to selectively pass therethrough, the first reflection light is not viewed but the second reflection light is selectively viewed.