Xerox WorkCentre PE114e, Service Manual

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4-7
Summary of product
Service Manual
4.2.6 LSU (Laser Scanner Unit)
This is the core of the laser printer. It converts the video data received from the computer into an electrostatic
latent image on the surface of the OPC drum. This is achieved by controlling the laser beam and exposing the
surface of the OPC drum to the laser light. A rotating polygon mirror reflects the laser light onto the OPC and each
side of the mirror is one scan line. The OPC drum turns as the paper feeds to scan the image down the page.
The /HSYNC signal is created when the laser beam from LSU reaches the end of the polygon mirror and this
signal is sent to the controller. The controller detects the /HSYNC signal to adjust the vertical line of the image on
paper. In other words after the /HSYNC signal is detected the image data is sent to the LSU to adjust the left margin
on the paper.