LINEAR TRANSLATING SYSTEM UTILIZING DITHER METHOD FOR IMPROVING IMAGE QUALITY OF TARGET IMAGE

摘要

PROBLEM TO BE SOLVED: To induce an irregular pattern of white noise artificially by controlling linear movement of a print head at a speed synchronized with rotation of a vacuum image drum and interrupting driving of a motor with a random lag when the vacuum image drum rotates. SOLUTION: A vacuum image drum 300 is related operationally with an encoder 344 and a rotation synchronizing pulse signal is generated for every revolution of the vacuum image drum 300 and delivered to a stepper motor controller 166. The stepper motor controller 166 drives a stepper motor 162 to move a print head with a constant uniform pulse train along the surface of the vacuum image drum 300 at a speed synchronized with the rotational speed thereof. When the vacuum image drum 300 rotates subsequently, the stepper motor 162 is stopped by interrupting the uniform pulse train causing a random lag in the linear movement of the print head during rotation of the vacuum image drum 300.