Patent ID: 8190041

Claim:
An image forming apparatus that includes an image carrier, an image forming unit that forms a toner image on the image carrier by toner supplied from a developing device, and a container body into which waste toner collected by a cleaning mechanism after transfer of the toner image is sent from the cleaning mechanism, the image forming apparatus comprising: a waste-toner-amount detecting unit that detects that an amount of waste toner collected in the container body has reached a first amount that is smaller than an amount of filled waste toner in a full state; a storing unit that stores an accumulated pixel value accumulated by a pixel calculating unit and an accumulated printed-sheet value accumulated by a printed-sheet calculating unit; and a calculating unit that calculates a second amount of waste toner based on a first criteria that is an amount of used toner used in the developing device utilized after the waste-toner-amount detecting unit detects that the amount of waste toner in the container body has reached the first amount of filled waste toner, wherein, after the calculating unit determines that the amount of waste toner has reached the second amount of filled waste toner, image formation is continued, and the calculating unit calculates a residual filling amount based on a second criteria that is an amount of waste toner that causes the container body to attain the full state from the second amount state, resulted from the second amount of waste toner, and compares the accumulated printed-sheet value with the residual filling amount, wherein image formation is forcibly stopped when the accumulated printed-sheet value reaches a predetermined value corresponding to an amount of the waste toner equivalent to the residual filling amount, and wherein the second criteria, different from the first criteria, is calculated based on the accumulated printed-sheet value stored in the storing unit.