The present invention generally relates to an image forming system, and more particularly to a toner supplying device of an image forming system, which device includes a cleaner portion for removing a residual toner from a photosensitive medium and an integrally formed toner supplying portion for supplying toner to a developing unit so that a toner image is formed on a copy sheet.
In image forming systems such as facsimile machines, printers and copiers, a cleaner toner magazine (CTM) unit is used in order to remove a residual toner on a photosensitive medium and store the residual toner, and to supply new toner to a developing unit so that a toner image is formed on a copy sheet. FIG. 12 shows a CTM unit used in an image forming system. In FIG. 12, the CTM unit includes a cleaner part 3 for removing the residual toner from a photosensitive medium (not shown) and a toner supplying part 5 for supplying new toner to a developing unit (not shown); these two parts are built into the one-piece unit. The cleaner part 3 includes a cleaning blade 1 for removing the residual toner, and a compartment 2 for storing the residual toner which is received from the photosensitive medium due to the cleaning blade 1. The toner supplying part 5 includes a toner transport screw 4 for supplying new toner to the developing unit.
In an image forming system of a different type having no CTM unit, the photosensitive medium, the developing unit, a replenishment toner storage tank, and a used toner storage tank are permanently united into a one-piece unit. When the replenishment toner in the storage tank is used up, it is necessary to replace the photosensitive medium or the developing unit, which is still usable and has not reached the end of its operating life. The image forming system with the CTM unit as described above has an advantageous feature in that the CTM unit, singly, can be replaced with a new CTM unit when the toner is used up, thus allowing the running cost per copy to be lowered.
However, when the CTM unit is replaced, for the replenishment of toner, there is a problem in that the replenishment toner partially sticks to an inside wall of the toner supplying part 5. The sticking of the toner may occur due to the changes of the chemical characteristics of the toner (e.g., the flowability or the adsorption characteristics) under certain environmental conditions or due to the physical arrangement of the CTM unit within the image forming system. For this reason, the amount of usable toner in the CTM unit is unsuitably reduced. Thus, it is desirable to make effective use of the replenishment toner in the CTM unit.