Dell 1600n - Multifunction Laser Printer B/W Service Manual page 31

Summary of Product
4.2.6 LSU (Laser Scanner Unit)
The LSU unit is controlled by the video controller. It scans the video data received from video controller
with laser beam by using a rotating polygon mirror to create the latent image on the OPC drum.
The OPC drum rotates as the same speed as the paper feeding speed. When it hits the corner of the poly-
gon mirror, it generates the /HSYNC signal. The CPU forms the left margin of the image using this signal.
After detecting the /HS YNC signal, the image data is sent to the LSU to arrange the its left margin on the
paper.
Each surface of the polygon mirror provides one line for scanning.
Service Manual
4-8