Different laser printers have different printing functions, but their working principles are basically the same. They all go through seven processes: charging, exposure, development, transfer printing, power elimination, cleaning, and fixing, five of which are around the photoreceptor drum. When the text or image to be printed is input into the computer, it is preprocessed by computer software. Then, the printer driver is converted into a print command (printer language) that can be recognized by the printer and sent to the high-frequency drive circuit to control the opening and closing of the laser transmitter to form a dot matrix laser beam. Then, the sensitive drum in the electronic imaging system is axially scanned and exposed through the scanning rotating mirror. The longitudinal scanning is realized by the rotation of the sensitive drum itself.