Patent ID: 6366336
Filing Date: 2002-04-02
Classification: G03B

Abstract:
An apparatus for forming an image on a photosensitive surface by scanning the photosensitive surfaced with a laser beam modulated at an adjustable pixel rate in accordance with data representing the image, the apparatus comprising:a modulation control signal generator which establishes the pixel rate; a beam scanner for scanning the laser beam repeatedly across the photosensitive surface in a first direction to create a succession of lines of the image as the photosensitive surface is moved in a second direction; a first timing signal generator which generates a first timing signal when the laser beam illuminates a first position representing the beginning of each scan across the photosensitive surface; a second timing signal generator which generates a second timing signal when the laser beam illuminates a second position representing the end of each scan across the photosensitive surface, the interval between the first and second timing signals corresponding to the time required for the laser beam to scan from the first position to the second position; a scan interval signal generator which generates a scan interval signal representing the actual interval between the first and second timing signals; a comparison circuit which determines the difference between the actual scan interval and a reference scan interval value corresponding to the desired time for the modulated laser beam to scan from the first position to the second position; and a compensation circuit which adjusts the output of the modulation control signal generator to vary the pixel rate of the modulated beam as a function of the difference.