Canon LBP 2460 Service Manual - Page 78

CHAPTER 2 IV. IMAGE FORMATION SYSTEM A. Outline The image formation system is the central hub of the printer, and consists of the photosensitive drum, developing unit and charging roller etc. When the PRINT signal (/PRNT) is sent from the video controller to the DC controller, the DC controller drives the main motor to rotate the photosensitive drum with the laser diode, developing cylinder, primary charging roller, and transfer charging roller. The primary charging roller uniformly applies a negative charge on the surface of the photosensitive drum. To form a latent image on the photosensitive drum, the laser beam modulated by the VDO signal is exposed to the photosensitive drum surface. The latent image formed on the photosensitive drum is changed to a visible image by the toner on the developing cylinder then transferred onto paper by the transfer charging roller. Residual toner on the photosensitive drum surface is scraped off by the cleaning blade. The potential on the drum is made uniform by the primary charging roller in preparation for the next latent image. The cartridge has a toner sensor that detects whether there is enough toner remaining and whether the cartridge is installed. If the toner in the cartridge becomes lower than the prescribed level or there is no cartridge installed in the printer, the high-voltage power supply notifies the DC controller through the TONER LEVEL signal. 2 - 32