Patent ID: 8384633

Claim:
An optical writing display apparatus comprising: a display medium comprising, between a pair of electrodes, a photoconductive layer comprising a first charge generating layer, a charge transporting layer and a second charge generating layer, and a cholesteric liquid crystal; a voltage application unit that applies a voltage to the pair of electrodes; an exposure unit that exposes the photoconductive layer to an exposure light; a one-shot exposure unit that exposes at one time the entire photoconductive layer to an exposure light; and a control unit that performs: a first initialization process including controlling the voltage application unit to apply a first voltage having a first polarity to the pair of electrodes, the first voltage applying a first partial voltage to the cholesteric liquid crystal layer, the first partial voltage being more than a threshold at which the state of the cholesteric liquid crystal layer changes from focal conic to homeotropic when the exposure is conducted, and controlling the one-shot exposure unit to irradiate the photoconductive layer with the exposure light; a second initialization process including controlling the voltage application unit to stop the application of the first voltage to the pair of electrodes for a predetermined time and controlling the one-shot exposure unit to expose the photoconductive layer while the application of the first voltage is stopped; and an image writing process including controlling the voltage application unit to apply to the pair of electrodes a second voltage having a second polarity opposite to the first polarity, the second voltage applying a second partial voltage to the cholesteric liquid crystal layer, the second partial voltage being not more than a threshold at which the state of the cholesteric liquid crystal layer changes from focal conic to homeotropic when the exposure is not conducted, but more than the threshold when the exposure is conducted, controlling the exposure unit to selectively irradiate with the exposure light a portion of the photoconductive layer corresponding to a portion of the cholesteric liquid crystal layer on which an image is to be formed or an image is not to be formed, and controlling the voltage application unit to stop the application of the second voltage to the pair of electrodes.