| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus, preventing erroneous detection of toner concentration using an inductance-detecting sensor to always detect toner concentration detection with high accuracy. <P>SOLUTION: A vertical agitation type developing device has a test mode for determining whether or not a detection value of the inductance detecting sensor 20 detected in forming an image is proper. In the test mode, while the rotational speeds of first and second conveying screws 26, 25 vertically disposed are varied with the speed of a developing sleeve 28 kept constant, the detection values detected by the inductance detecting sensor 20 are monitored, and according to the results of the plurality of detection values monitored, the toner concentration detected in forming an image is controlled to a proper value based on the result of determining on whether or not the detection value detected in forming the image is proper. <P>COPYRIGHT: (C)2010,JPO&INPIT |
