| 摘要 |
PURPOSE:To provide a copying machine not having the scattering of toner and the degradation of image quality by stabilizing the concentration of toner in a developing unit regardless of a change in developing capacity in the developing unit. CONSTITUTION:When the developing capacity in the developing unit 4 is changed, a toner image for detecting 16 is formed and a toner sticking quantity on the toner image for detecting 16 is detected by a P-sensor 5. For instance, when the developing capacity is increased and the toner sticking quantity is increased, a CPU 6 changes a grid voltage to make a potential by electrification at the time of forming an electrostatic latent image for detecting low or a developing bias voltage at the time of forming the toner image for detecting high. On the other hand, when the developing capacity is reduced and the toner sticking quantity is decreased, the CPU 6 changes the grid voltage to make the potential by the electrification at the time of forming the electrostatic latent image for detecting high or the developing bias voltage at the time of forming the toner image for detecting 16 low. |
