| 摘要 |
PROBLEM TO BE SOLVED: To reduce possibility that toner consumption amount is wrongly measured in succession.SOLUTION: A first calculation part 41, until a predetermined switching condition is met, repeatedly calculates toner consumption amount by a first calculation method, and a second calculation part 42, after the switching condition is met, calculates toner consumption amount according to a predetermined formula by a second calculation method. A coefficient calculation part 43, based on the toner consumption amount that is calculated by the first calculation method, repeatedly calculates a parameter value in the second calculation method. The coefficient calculation part 43, in a case where the parameter value goes out of a tolerable range, makes calibration to be executed. Based on the toner consumption amount that is calculated by the first calculation method after the calibration, the parameter value in a formula is calculated. When the parameter value goes out of the tolerable range, even before the switching condition is met, calculation of the toner consumption amount is switched from the first calculation method to the second calculation method. |
