Mechanism to prevent toner leakage from an image forming unit

摘要

An image forming unit includes structure to prevent leakage of initial developer containing magnetic carrier and magnetic toner from a case. The image forming unit includes a photoconductive drum, a developing sleeve, and a trimming blade. Auxiliary sealing members are attached to the opposite ends of the trimming blade to stop up gaps between side sealing members in sliding contact with the opposite ends of the developing sleeve, and a protective sheet is removably inserted in the gap between the developing sleeve and the trimming blade. Ferromagnetic strips capable of being magnetized by the magnet roller are attached to the reverse side of the protective sheet at the opposite sides of one end of the protective sheet. The ferromagnetic strips magnetically attract the developer that is about to leak through the gaps to completely prevent leakage of the developer.