| 摘要 |
PROBLEM TO BE SOLVED: To provide an image forming apparatus and a method and a program for controlling a toner concentration in the apparatus, for always appropriately controlling the toner concentration regardless of changes in a carrier amount in a developing device.SOLUTION: An assumed output value of a toner concentration sensor 48 is set. In an embodiment, the toner concentration sensor 48 outputs 2.5 V at an output voltage (a) point responding to 200 g of a developer having 10% toner concentration in a new developing device 9; and when the toner concentration is increased to 11%, an assumed output value of the toner concentration sensor 48 for 202 g of the developer indicates 2.1 V at an output voltage (b) point. When the number of printed sheets exceeds a specified value under initial conditions, 2 g of the toner is supplied to the developing device and an output voltage of the toner concentration sensor 48 is checked. If the output voltage does not fall on the assumed output voltage (b) point but on (c) point, it means that the developer amount is decreased by G g. That is, 200 g of the developer amount with 10% toner concentration is decreased by G g. Consequently, the set output value (toner concentration detection voltage threshold) is changed to 2.4 V at (d) point. |
