Patent ID: 7683919

Claim:
A graduation control device applied to an optical system comprising: two or more optical transmission elements optically arranged in series having a plurality of optical transmission sections capable of independently controlling a transmission state and non-transmission state of incident light in a predetermined direction, and the transmission state and non-transmission state of the two or more optical transmission elements being controlled by a control signal corresponding to each bit of a bit string that indicates a number of gradations; and a signal delay unit that delays the timing by which the control signal is supplied to another optical transmission element by a predetermined amount of time beyond the timing by which the control signal is supplied to any one of the two or more optical transmission elements, and controls a transmission time of light to a target location by utilizing a time difference of the control signal that is supplied to the two or more optical transmission elements, whereby a number of gradations that are displayed can be expanded beyond a number of gradations that could be displayed by synchronous control of the two or more optical transmission elements.