| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus preventing a carrier sticking on an image carrier due to reduction in resistivity value of the carrier owing to long-term use of a developer without causing a decrease in picture quality of an output image. <P>SOLUTION: The image forming apparatus 1 includes a toner density control unit 24 which controls a toner hopper 40 to increase the toner density of a developer in a developing tank when a resistivity value determination unit 22 determines that a volume resistivity value measured by a resistivity value measuring unit 21 falls below a prescribed volume resistivity value stored in a prescribed resistivity value storage unit 23, and a display control unit 27 which warns a user to replace a developing unit or developer when a density determination unit 25 determines that detected toner density detected by a toner density sensor 15 exceeds prescribed toner density stored in a prescribed density storage unit 26. <P>COPYRIGHT: (C)2008,JPO&INPIT |
