| 摘要 |
PROBLEM TO BE SOLVED: To more accurately detect a characteristic value of a detecting object from the next time by changing the detecting timing of the detecting object by a detecting means on the basis of dispersion in the characteristic value detected every time when a correcting means performs detection even when a position of the detecting object is dislocated by disturbance such as an environement or the like. SOLUTION: A printer control part 201 investiages whether or not an AIDC sensor 210 accurately detects a reference patch before a toner sticking quantity of the reference patch is specified. When the AIDC sensor 210 accurately detects only the reference patch, its detecting value is supposed to fluctuate only in a certain range. Then, a variation |A1-A2|, |Al-A3 I,..., |A1-A10| (detecting points are ten points in total) in a detecting value at a first sampling point A1 and a detecting value at the other sampling point is found, and a predetermined first reference value and a variation in these values are compared with each other. |
