Patent ID: 8322753

Claim:
An identification medium which is observed via a linearly polarizing filter, comprising: a first liquid crystal layer for changing a wavelength of light according to a rotational angle of the linearly polarizing filter; a cholesteric liquid crystal layer; and a light absorbing layer provided below the cholesteric liquid crystal layer, wherein the first liquid crystal layer includes a reflection layer and at least one twisted nematic liquid crystal layer, wherein the twisted nematic liquid crystal layer includes liquid crystal molecules in which a product of a birefringent value and a spiral pitch is at least 3.5 times greater than the wavelength of light having a wavelength of 400 to 800 nm, and the twisted nematic liquid crystal layer does not cause a selective reflection by Bragg diffraction and also satisfies a Mauguin condition, in which a linearly polarized light passes through the twisted nematic liquid crystal layer in parallel or perpendicularly to long axes of the liquid crystal molecules and also passes along a spiral structure of the liquid crystal molecules with the linearly polarized light maintained in a polarized state.