Latent-image formation stage During the latent-image formation stage, the laser/scanner forms an invisible image on the photosensitive drum in the print cartridge. Primary charging Step 1 : dc and ac biases are applied to the primary charging roller, which transfers a uniform negative potential to the photosensitive drum. Figure 1-16 Primary charging Primary charging roller DC bias Photosensitive drum Laser beam exposure Step 2 : The laser beam scans the photosensitive drum to neutralize negative charges on parts of the drum surface. An electrostatic latent image is formed on the drum where negative charges were neutralized.
Figure 1-17 Laser beam exposure Laser beam 24 Chapter 1 Theory of operation ENWW Unexposed area Exposed area