| 摘要 |
PURPOSE:To keep the toner particle concentration of a developer constant and to perform constant-density development by supplying concentrated toner to the developer according to a residual potential detection signal after an electrostatic latent image is developed. CONSTITUTION:A residual potential corresponding to reference toner particle concentration is stored as a reference value V0 in a comparing circuit 37 and the residual potential after development is detected by a potential sensor 24 with a mark 25, amplified 36, and compared by the circuit 37 with the value V0. When the detected value is larger than the value V0, a solenoid valve 26 is opened for a specific time to reduce the pressure in a pipe 29 and the concen trated toner 31 in the container 31 is sucked up and supplied to a developer tank 23 to increase the toner particle concentration of a developer 32. When the detected value is smaller than the value V0, on the other hand, the valve 26 is not opened. Thus, the toner particle concentration of the developer 32 is held constant to maintain constant development density. |
