| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus wherein excessive deterioration of a developer is suppressed without formation of as toner band, even when a low-coverage continuous printing state continues over a long period. <P>SOLUTION: The image forming apparatus includes a developing device which is allowed to select one of two image forming operation modes of a cost-per-print priority mode and an image quality priority mode. In the cost-per-print priority mode, a fundamental amount B (mg) of carrier is supplied at intervals of a prescribed time. In the image quality priority mode, if the amount of toner supplied to a developer storage section for a prescribed time is smaller than a prescribed amount A(mg), an amount C (mg) of carrier calculated by formula (1): (the amount C of carrier to be supplied) = ä(A-(amount (mg) of toner supplied to the developer storage section))<SP>2</SP>/k}+B (wherein k is a coefficient selected to be in the range of 0.2Dw≤k≤2Dw, wherein Dw(g) is the amount of the two-component developer in the developer storage section) is supplied at intervals of a prescribed time. <P>COPYRIGHT: (C)2011,JPO&INPIT |
