| 摘要 |
PROBLEM TO BE SOLVED: To provide an image forming apparatus, appropriately transferring a toner image of image to an intermediate transfer body or recording material in a transfer part even after the ratio of toner in a binary developer reaches a predetermined lower limit value. SOLUTION: When toner density (T/D ratio) is within the range of 5-12%, the toner supply quantity to a developing device 23a is controlled according to the patch density of control toner image detected by a patch detection sensor 24a. When the toner density (T/D ratio) is below 5%, the control toner image is formed while maintaining the toner supply quantity constant, and the charging performance of a pre-transfer charging device 25a is changed according to the patch density measurement result of the control toner image formed in a predetermined development contrast. The reduction in charging quantity Q/M of toner image due to deterioration of the binary developer is recovered, and deterioration of transfer efficiency of toner image in a primary transfer part and a secondary transfer part are avoided. COPYRIGHT: (C)2010,JPO&INPIT |
