| 摘要 |
PROBLEM TO BE SOLVED: To maintain the accuracy of an optical sensor fixed at an image forming device main body even by attaching and detaching of a developing unit to/from the image forming device main body in an image forming device measuring the toner concentration of an attachable/detachable developing unit by the optical sensor. SOLUTION: The toner concentration (Vb) at the developing unit is measured before detaching the developing unit (a step S5), and a measured Vb value is stored (steps 3 and 4). Then, in the case that the developing unit attached is an original unit (the developing unit judged in a step S5 as the detached unit) (no in a step S7), the calibration of a toner concentration measuring part is executed (steps S9, S10 and S11) by taking the measured Vb value as a reference value. On the other hand, in the case that the developing unit attached is an unused unit (yes in the step S7), the calibration of the toner concentration measuring part is executed (steps S16, S17 and S18) by taking a toner concentration value Vn specified for an unused developing unit as the reference value. |
