Variable intensity light beam scanning apparatus with feedback

Claim 1

A light beam scanning apparatus in which light beams are modulated with large information signals and the modulated light beams are radiated onto a photosensitive body comprising: a light source for producing light beams in which the light energy distribution displays a normal distribution; a first means for causing light beams produced by said light source to effect scanning with respect to said photosensitive body in a first direction; a second means for causing light beams produced by said light source to effect scanning in a second direction which is perpendicular to said first direction; an image formation means for forming an image constituted by continuous or discontinuous dots on said photosensitive body after scanning in said first and second directions; and a light quantity detection means for detecting the quantity of light of a light beam produced by said light source and for outputting a voltage proportional to detected light quantity; a light quantity setting means for producing a reference voltage; a comparison and amplification means for comparing the output voltage from said light quantity detection means and the reference voltage output by said light quantity setting means and for outputting an analog level voltage corresponding to the voltage from said light quantity setting means; a sampling hold means for holding output voltage from said comparison and amplification means and for continuously outputting held voltage; a current amplification means for amplifying the current proportional to the input voltage from said sampling hold means and for outputting an analog level current; and a light source drive means for lighting said light source by supplying current from said current amplification means thereto in accordance with image information signals and for varying the dot diameter of said light beam.