SCANNING OPTICAL DEVICE AND ITS CONTROLLING METHOD

摘要

PROBLEM TO BE SOLVED: To obtain a scanning optical device and its controlling method capable of printing a high-quality image by correcting the condensing position of light beams in addition to changing the spot diameter of the light beam with switching of printing density in a multi-beam scanning system. SOLUTION: This optical device image-forms and scans laser beams LBa and LBb emitted from laser diodes 10a and 10b at prescribed intervals corresponding to printing density in the sub-scanning direction on a photoreceptor surface 50. A beam spot diameter on the surface 50 is adjusted by changing a slit through which the beams LBa and LBb pass by driving an opening regulating plate 14. A beam interval in the sub-scanning direction is adjusted by controlling the tilt angle of a prism 11 and a condensing position is adjusted by controlling the lens interval of collimator lenses or that of cylinder lenses.