Laser Printer Scan Length Servo
Original Publication Date: 1983-Sep-01
Included in the Prior Art Database: 2005-Feb-07
This article describes circuit means for synchronizing the writing rate of a laser beam to the scanning rate of the beam by writing pulses in inverse proportion to the time of scan. Fig. 1 shows a laser light source 10 providing a beam of light 11 to a rotating mirror 12 for reflecting the beam of light so as to scan a moving photoreceptive surface 15. The start of scan is sensed by redirecting the light beam at mirror 13 to a photodetector 14. As mirror 12 rotates in the direction A, the beam of light is scanned across photosensitive surface 15 to mirrors 16 and 16' where the beam of light is again redirected to detector 14. In that manner, the start of scan is detected from the beam of light reflected from mirror 13, and the end of scan is detected through deflection from mirrors 16 and 16'. Fig.