| 摘要 |
PROBLEM TO BE SOLVED: To prevent deteriorated toner from remaining in a developing device and, therefore, to prevent secular image-density-decrease by composing so that when the number of sheets detected by a means which detects the number of sheets reaches a specific number, electric potential between a latent-image carrier and developer carrier which is outside an image forming area is increased. SOLUTION: A controller controls the entire system so that when the number of sheets counted by the counter 12b of the means 12 which detects the number of sheets reaches the specific number, the electric potential between the photoreceptor 1 and developing roller 4b which is outside the image forming area on the photoreceptor 1 increases. This prevents toner from sticking to the outside of the image forming area on the photoreceptor 1, and the toner is recovered by cleaners 6 and 11 without being used for image formation. That is, from the number of the transfer sheets 9 which have been used, the deteriorated state of the toner 8 is detected, and the toner in the developing device 4 is forcibly consumed before the toner deterioration advances. |
