The DC controller detects the remaining toner level in a cartridge according to the TONER LEVEL signal. The DC controller determines a cartridge low warning or cartridge end of life when the toner level drops below a specified level and notifies the formatter. ● Cartridge-life detection The DC controller detects the cartridge life of components that wear out. The DC controller determines a cartridge end of life and notifies the formatter. Other image-formation functions Drum discharge The drum discharge is a feature to remove residual charge on the photosensitive drum surface for preventing the uneven image density.
The laser-beam strikes the surface of the photosensitive drum to remove the residual charge. The drum discharge is performed during LSTR period. Figure 1-22 Drum discharge Laser beam Photosensitive drum Transfer roller cleaning The transfer roller cleaning is a feature to remove residual toner on the transfer roller surface for preventing the back side toner stain of the paper. The residual toner reverse transfers to the photosensitive drum by applying the reverse transfer bias to the transfer roller. The residual toner is deposited in the toner collection box. ENWW Image-formation system 29