| 摘要 |
A raster output scanner having a movable imaging member and high intensity imaging beam for exposing the imaging member to create images thereon. A rotating polygon scans the beam across the imaging member in line by line fashion while a modulator astride the beam path modulates the beam in accordance with image signals or pixels input thereto. A clock provides clock pulses for clocking the image pixels to the modulator. To assure uniform image size despite variations in the velocity of the imaging member, a control signal representative of imaging member velocity is used to control polygon velocity and maintain a predetermined velocity relationship between imaging member and polygon. Means are provided to servo clock frequency with polygon rotation, with a control to shift the clock servo midpoint frequency in response to changes in imaging member velocity.
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