COPYRIGHT © 2000 CANON INC. 2000 2000 2000 2000 CANON iR5000/iR6000 REV.0 JULY 2000CHAPTER 3 LASER EXPOSURE SYSTEM3-1 P1. Outline of Operations1.1 OutlineThe laser exposure system consists of a laser unit and a laser scanner: the laser unit is thesource of laser light, while the laser scanner serves to generate a scanning laser beam bymeans of a polygon mirror.The video signals from the controller unit are converted into laser drive signals by the DCcontroller PCB; they are then turned into laser intensity signals by the laser driver PCB,used to direct the laser beam from the laser unit.The collimator lens turns the laser beam into a parallel beam possessing an oval cross sec-tion; the cylindrical lens then changes it to a flat, band-like parallel beam.The resulting laser beam is directed through an imaging lens and is reflected by a polygonmirror, which is rotating at a high and by, upon by which the beam is turned into a scanningbeam possessing a specific direction.The laser beam is then led through an imaging lens for removal of distortion, and is di-rected to the positively charged photosensitive drum (areas representing white) for the for-mation of a static image.The laser beam is also used to blank out the non-image area.T03-101-01ItemLaser intensity controlLaser scanningLaser scanner motor controlDescription1. Executes laser power auto control (APC control)2. Executes optimum intensity control to suit the surfacepotential of the drumBy semiconductor laserMain scanning direction: control by BD signalSub scanning direction: control by laser write start signal1. Executes constant speed rotation control2. Switches between full-speed rotation and in-wait rota-tion
