| 摘要 |
A reversal image development type electrophotographic printing system including a rotatable drum (1) coated with a light sensitive layer and an image developing roller (31) co-rotatable with the drum and using a printing medium composed of carriers and toner. To prevent superfluous toner during start-up, a predetermined bias voltage (-VB) differing to a normal bias voltage (+VB) is supplied to the image developing roller and the drum, and the image developing roller, a precharger (2), and power supplies (52, 53) for supplying the initial and normal bias voltages are energized in a predetermined start sequence. In addition, to prevent carrier extraction at a stop condition, the drum, the image developing roller, the precharger, and the power supply (53) are deenergized in a predetermined operation stop sequence. A printing medium including a resin toner comprising a mixed resin and magnetized powder and a charge control medium mixed with the resin toner may be used, and prevention of the surplus resin toner extraction in the start-up condition also may be achieved. |
