Patent ID: 8915437

Claim:
An identification medium comprising, in order, seen from a side reading is performed: a cholesteric liquid crystal layer having a hologram image and in which circularly polarized light of primary rotating direction is selectively reflected; an optical function layer having a structure in which a λ/4 plate and a linearly polarized light filter layer are laminated in this order, from an observing side, and an optical function which selectively penetrates circularly polarized light of a secondary rotating direction opposite to the primary rotating direction in a direction toward the cholesteric liquid crystal layer when natural light enters from an opposite side to the cholesteric liquid crystal layer side; and a code forming layer in which an objective code that is to be read is formed, the cholesteric liquid crystal layer, the optical function layer and the code forming layer being disposed relative to each other such that a path of light is formed, the path of light extending through the cholesteric liquid crystal layer, the λ/4 plate, the linearly polarized light filter layer, and the code forming layer in this order such that the natural light initially passes through the cholesteric liquid crystal layer, then through the λ/4 plate, and then through the linearly polarized light filter layer to become linearly polarized light upon exiting the linearly polarized light filter layer in a direction away from the cholesteric liquid crystal layer, the linearly polarized light reflecting in the code forming layer and subsequently passing through the optical function layer in the direction toward the cholesteric liquid crystal layer to become the circularly polarized light of the secondary rotating direction upon exiting the optical function layer in the direction toward the cholesteric liquid crystal layer, the hologram image being disposed relative to the code so as to inhibit reading of information of the code while an optical reading device reads the code and the hologram image at the same time.