Improving Resolution of a Scanning Laser Printer
Original Publication Date: 1983-Dec-01
Included in the Prior Art Database: 2005-Feb-08
This article describe a concept for stopping the movement of a laser beam spot on an electrophotographic medium during the exposure of each print element (pel). This is accomplished by varying the first order laser beam angle from the output of the acousto-optic modulator to cancel the movement caused by the rotating polygonal mirror. The horizontally scanning laser beam has a diameter of about one pel. If the beam is turned on for one pel and then off, it produces an elliptical exposure, as shown in Fig. 1. The elliptical shape is caused by the continuously rotating mirror's angular velocity in the direction A during the turn-on of the beam. Not only is the exposure wider but the slope of the intensity is less steep. Both these characteristics reduce the horizontal resolution.