Patent ID: 8339528

Claim:
An erasing device used for erasing an image pattern recorded on an optical writing type display medium that includes a display function layer in a structure in which a laminate including a photoconductive layer and n-layers (n is a natural number) of cholesteric liquid crystal layers is sandwiched between a pair of electrodes, the erasing device comprising a signal generating section that applies an erasing voltage for erasing the image pattern to the pair of electrodes, wherein in a state where Vm is determined according to each resistance of the n-layers of the cholesteric liquid crystal layers and resistance of the photoconductive layer, the erasing voltage is set to satisfy Vm≧Vthm in all cases where m is an integer of 1 to n, provided that m takes any integers from 1 to n, a voltage applied to the m-th layer of the cholesteric liquid crystal layer when the erasing voltage is applied between the pair of electrodes is Vm, and a threshold voltage with which the m-th layer of the cholesteric liquid crystal layer changes to an homeotropic alignment is Vthm.