| 摘要 |
PROBLEM TO BE SOLVED: To provide an image forming device for properly controlling toner concentration on the basis of the estimated amount of carrier in a developing unit.SOLUTION: In supplying toner, output values Vdb and Vda of a toner concentration sensor 48 before and after toner supply are acquired (S1 to S5). A current correction value of an environment correction value table 79 is added to Vda-Vdb to calculate Vdh (S6). A difference &Dgr;V between Vdh and Vdh_std(=Vda-Vdb+0(an initial value of the environment correction value is 0)) is determined (S7). If |&Dgr;V|<100 mV is satisfied, processing is terminated. If |&Dgr;V|≥100 mV is satisfied, the amount of carrier is decided from &Dgr;V by use of a control voltage correction value table 80. A control voltage for the toner concentration sensor 48 is increased with a voltage correction value based on the decided amount of carrier, thereby increasing an output of the toner concentration sensor 48. |
