Light beam scanning apparatus capable of changing the scanning density

Claim 1

A light beam scanning apparatus that uses a light beam deflected in the direction of main scanning in order to perform two-dimensional scanning of a sheet-like subject to be scanned that is moving in a sub-scanning direction which is generally perpendicular to said direction of main scanning, said apparatus comprising: a light beam source that emits said light beam; means for altering the speed at which said sheet-like subject moves in the sub-scanning direction in order to change the density of scanning lines formed by said light beam; a memory unit containing at least two versions of data representing the intensity of said light beam in association with the density of said lines, said at least two versions of data varying from the beginning to the end of each scanned line and comprising standard light intensity data for each scanning position of a single scan, a first version of data representing a high density mode for producing an image of a first quality and a second version of data representing a lesser density mode for producing an image of a second quality; and selection means for selecting one of said at least two versions of data from said memory unit in accordance with the desired density of said scanning lines, wherein said selected version of data causes said intensity of said light beam to be modulated in accordance with clock pulses corresponding to image data, such that said intensity is increased as said scanning density is decreased and said intensity is decreased as said scanning density is increased.