| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of detecting an abnormal state of an inductance sensor for detecting the proportion of toner in developer and abnormal states other than that of the inductance sensor by detecting the magnetic permeability of the developer. <P>SOLUTION: The developing unit 141 includes: the inductance sensor 142 for detecting the proportion of toner in developer from the magnetic permeability of the developer as a sensor output voltage Vo; a toner supply motor 146 for supplying toner to the developing unit 141; and a development drive motor 145 for discharging toner. If the sensor output voltage Vo corresponding to a reference voltage Vref is not obtained even when the reference voltage Vref for the inductance sensor 142 is altered, it is determined that the inductance sensor 142 is in an abnormal state. If the inductance sensor 142 is determined to be normal, toner is supplied. Alternatively, if there is no change in the sensor output Vo as a result of discharging toner, it is determined that a toner supply motor 146 or developing drive motor 145 is determined to be in an abnormal state. <P>COPYRIGHT: (C)2011,JPO&INPIT</p> |
