| 摘要 |
PROBLEM TO BE SOLVED: To recover, in case the detected concentration of toner in a developing device becomes different from the actual concentration of the toner, linearity between them. SOLUTION: An addition time S that is added to a stirring time being a reference is set to 10 sec. (step S12), 100 sec. (step S14), 300 sec. (step S16), or 500 sec. (step S18) according to a value (voltage value) obtained by subtracting the value of toner concentration βdetected previous time from toner concentration α in the developing device detected this time, which has been stored in a nonvolatile memory. Then, a stirring time S to which the addition time S has been added is stored in the nonvolatile memory. When an image forming operation is carried out, two-component developer in the developing device is stirred, but the time is extended according to the length of the stirring time stored in the nonvolatile memory. |
