| 摘要 |
PURPOSE:To lower shifting frequency and to adjust image density while image quality is stable by allowing the shifting period to vary with the direction of humidity change when such reference data is shifted as an alternating electric field responding to the humidity change, a developing DC bias, or the peripheral speed of a developing sleeve. CONSTITUTION:The information of an environment sensor 19 is decided by a control means 18. When humidity is low, a large alternating electric field is applied to the developing sleeve 1 from a power source 1' and more toner is applied to development, whereas when the humidity is high, the scale of the alternating electric field is reduced within a range where a maximum density can be obtained, and toner is prevented from excessively sticking. When the alternating electric field is shifted, it is provided with hystericis characteristics according to the density change direction and controlled. As a result, shifting response to the humidity change in the vicinity environment is delayed, the alternating electric field shifting frequency is remarkably lowered, and the image quality is improved in stability. |
