Patent ID: 8478142
Filing Date: 2013-07-02
Classification: G03G

Abstract:
1. An image forming apparatus comprising: a control unit to generate a control signal; a developing unit including a toner/carrier compartment having toner and carrier therein and a toner supply compartment, the developing unit including a toner/carrier ratio sensor to receive the control signal and to generate an output signal corresponding to a toner/carrier ratio in the toner/carrier compartment of the developing unit; when an unused developing unit having an initial toner/carrier ratio of toner/carrier in the toner/carrier compartment is newly installed in the image forming apparatus, the control unit determines a value of the control signal which causes the toner/carrier ratio sensor of the developing unit to generate the output signal which is within a target value range corresponding to the initial toner/carrier ratio of toner/carrier in the toner/carrier compartment; a memory unit in the developing unit to store information from the control unit relating to the determined value of the control signal; and after the value of the control signal is determined and at least a portion of the toner in the toner/carrier compartment of the developing unit is consumed by the image forming apparatus, the control unit outputs the control signal having the determined value to the toner/carrier ratio sensor based on the information stored in the memory unit of the developing unit, which causes the toner/carrier ratio sensor of the developing unit to output an output signal corresponding to a changed toner/carrier ratio of toner/carrier in the toner/carrier compartment of the developing unit to the control unit, and the control unit controls supply of toner from the toner supply compartment to the toner/carrier compartment based on the output signal received from the toner/carrier ratio sensor, wherein the control unit determines whether an agitator to agitate the toner in the developing unit is normal or abnormal based on a detected periodic fluctuation of an output voltage of the toner/carrier ratio sensor, where the agitator is abnormal when a predetermined voltage is not periodically detected with the detected periodic fluctuation of the output voltage of the toner/carrier ratio sensor.