| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus which can prolong the service life of developer and achieve stability in image density by evading an excessive variation in developer concentration and reducing the load applied to the developer. <P>SOLUTION: A recognition means 60 for recognizing that the image forming apparatus is abnormal when the output of a detecting sensor 42 for detecting the information corresponding to the ratio of mixture of toner and carrier in a developing means is varied exceeding the specified abnormal level is provided. The level of abnormality is made variable according to an image density signal. <P>COPYRIGHT: (C)2004,JPO |
