| 摘要 |
PURPOSE:To hold the toner concn. in a developer constant and eliminate the uneveness of image quality by providing a magnetic permeability conversion type automatic toner concn. controller with a humidity compensating circuit, developer deterioration compensating circuit, and reference voltage generating circuit. CONSTITUTION:A detecting circuit 9 is connected to the detection sensor 9 for magnetic permeability in a casing 1 to obtain a DC voltage corresponding to the toner concn. in the developer. The detection voltage is compared by a comparator 10 with the reference voltage of a reference voltage generating circuit 11. When the detected voltage is higher than the reference voltage, the toner concn. is low and a motor control circuit 12 drives a toner supply motor 7. The sensor 13a of the humidity detecting circuit 13 is provided in the casing 1 and connected to the circuit 11 through a humidity detector 14b to compensate variation in toner concn. due to humidity. Further, the circuit 11 is provided with a deterioration compensating circuit 14 for the developer and the circuit 14 counts the quantity of copies; when the quantity increase attains to such a quantity that the deterioration of the developer causes variation in the detection voltage of the toner concn. the voltage is shifted to perform compensation. |
