| 摘要 |
<P>PROBLEM TO BE SOLVED: To normally form an image without deteriorating image quality or without causing image formation disabled state, even when nonconformities occurs in voltage adjustment of a developing bias. <P>SOLUTION: When a toner concentration adjusting operation starts (101), a toner image is formed, in a state where a charge bias and exposure amount are fixed and the developing bias is variable (102); then, the toner image is read by a sensor (103). The developing bias for a target voltage is calculated from the output voltage read by the sensor (104), then the calculated developing bias is compared with the lower limit value of the developing bias (105). If the calculated developing bias is equal to or more than the lower limit value as a result of the comparison result, the toner consumption is regarded as being in the normal range, and the toner consumption is predicted, based on the toner deposition amount corresponding to the target voltage (106); and then the toner image is formed with the developing bias for the target voltage (107). Meanwhile, if the calculated developing bias is not equal to or is larger than the lower limit value, that is, below the lower limit value, this means that the toner consumption is out of the normal range, then the toner consumption is predicted based on the largest toner deposition amount (108); and the toner image is formed with the last developing bias, when the toner concentration adjusting operation is successful (109). <P>COPYRIGHT: (C)2009,JPO&INPIT |
