| 摘要 |
PURPOSE:To detect an accurate toner concentration by providing a toner concentration sensor detecting and outputting the strength of magnetic flux in the vicinity of a magnetic roller and a peak value detecting means, and using a peak value obtained by the peak value detecting means as a toner concentration in a prescribed rotational range. CONSTITUTION:The toner concentration sensor 3 detecting and outputting the magnetic flux force in the vicinity of the magnetic roller 2, and the peak value detecting means 4 detecting the detected/outputted peak value of the toner concentration sensor 3 in its rotational range at every prescribed rotational quantity of the magnetic roller 2. Then, the magnetic roller 2 is rotated, so that the strength of the magnetic flux in the vicinity of it is detected by the concentration sensor 3, and the peak value detected/outputted by the concentration sensor 3 in the prescribed rotational range of the magnetic roller 2 is detected by the peak value detecting means 4, and its peak value is used as the toner concentration at every prescribed rotational range of the magnetic roller 2. Thus, the toner concentration is accurately measured, and a stable optimum printing density is obtained. |
