Optical printer with micromirror device

摘要

An optical printer has a DMD as a spatial light modulator. An optical image corresponding to a fraction of a picture frame is projected from the DMD onto a photographic paper at a predetermined time interval. The photographic paper is advanced intermittently by a length corresponding to an exposure area for one optical image. A fluctuation value from a set advanced length for one advancing step is detected at each advancing step and accumulated. The DMD is mounted on a swinging plate whose angle is controllable by a piezoelectric element, to shift the exposure position on the photographic paper. In accordance with an accumulated fluctuation value, drive voltage to the piezoelectric element is changed from a reference value to correct the exposure position so as to print the picture frame without any gap or overlap between the fractions.