Abstract: 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.

Abstract: The present invention provides an electrophotographic toner containing, as a fixing resin, a styrene-acrylic copolymer in which styrene content and molecular-weight distribution are specified, and which contains a specific high-molecular-weight component.The electrophotographic toner of the present invention is improved in bending resistance while assuring excellent low-temperature fixing properties, resistance to off-set and heat resistance.

Abstract: The present invention relates to a system for making discriminations between cartridges for housing toners to be equipped on image forming apparatus such as electrostatic copiers, laser beam printers, facsimiles, etc. in which while a cartridge indicating means is provided on a part of a toner housing cartridge, an indication detecting means for detecting the aforementioned cartridge indicating means is provided on the image forming apparatus proper side, so that the suitability of the type or position of the cartridge inserted is detected by detecting the cartridge indicating means by the aforementioned detecting means, when the cartridge has been inserted into the cartridge inserting part of the image forming apparatus proper.

Abstract: Disclosed is a toner for the electrophotography, which comprises as a main component a styrene/acrylic copolymer having at least two molecular weight distribution peaks, the molecular weight (Mw) of the peak on the lowest molecular weight side being lower than 13000, wherein the toner contains a charge controlling agent dispersed therein at a concentration of at least 0.3% by weight and the charge controlling agent has such a particle size distribution that the area ratio of particles having a particle size larger than 2.5 .mu.m is at least 80% based on the section of the toner. If this toner is used, the fixing-possible temperature can be broadened while increasing the fixing ratio without reduction of the performances of the toner.

Abstract: The present invention relates to a system for making discriminations between cartridges for housing toners to be equipped on image forming apparatus such as electrostatic copiers, laser beam printers, facsimiles, etc. in which while a cartridge indicating means is provided on a part of a toner housing cartridge, an indication detecting means for detecting the aforementioned cartridge indicating means is provided on the image forming apparatus proper side, so that the suitability of the type or position of the cartridge inserted is detected by detecting the cartridge indicating means by the aforementioned detecting means, when the cartridge has been inserted into the cartridge inserting part of the image forming apparatus proper.