Multi-chamber electro-photographic developing unit for image forming apparatus

摘要

A developing unit for use in image forming apparatus includes a unit housing divided in three chambers, i.e. a toner applying chamber facing a photoreceptor and first and second toner replenishing chambers, by respective partition walls each having an opening as a passage for toner. The first and second chambers have rotation frames, respectively. Each frame has a radially extending arm to the end of which a toner transporting sheet is connected. Each sheet is provided with a friction film. When each frame rotates, the sheet with the friction film is pulled by the frame for its rotation under the toner so as to be deformed in the form of a circular arc. The toner is transported forwardly by the friction force of the friction film. When the amount of toner is reduced in each chamber, each sheet may resiliently restore to its original shape to contact the inner surface of the corresponding chamber so that a small amount of toner on the bottom of each chamber can be carried forwardly.