| 摘要 |
<P>PROBLEM TO BE SOLVED: To reduce occurrence of image failure even in a case where image formation is carried out under condition in which an immovable layer may be formed. <P>SOLUTION: An image forming apparatus checks whether or not a developing sleeve 28 has been continuously rotating for a predetermined time or longer after the start of its rotation. Also, the apparatus simultaneously calculates the average image proportion in a case where image formation is carried out a predetermined number of times from image data input from the image input section 73. If the developing sleeve 28 has been continuously rotating for the predetermined time or longer and the average image proportion is a predetermined value or below, the developing sleeve 28 and first and second conveyance screws 25 and 26 are stopped. Thus, the height of the level of a developer in a developing device 4 changes, and an immovable layer is not easily formed or can be crushed even if it is formed. Accordingly, occurrence of image failure can be reduced. <P>COPYRIGHT: (C)2012,JPO&INPIT |
