| 摘要 |
PROBLEM TO BE SOLVED: To enable recovery and recycling of untransferred toner on the surface of a photoreceptor by a developing means without provision of a cleaning means, by specifying surface potential of an unexposed portion and surface potential of an exposed portion and a relationship between two development bias voltages. SOLUTION: The surface potential SP1 (volt) of an unexposed portion of an electrified photoreceptor 1 in a developing area and the surface potential SP2 (volt) of an exposed portion of it in the developing area are set so that a development bias voltage V1 (volt) applied to a developing roller 51 located the furthest upstream in the direction of the movement of the photoreceptor and a development bias voltage V2 (volt) applied to a developing roller 52 located the furthest downstream in the direction of the movement of the photoreceptor are the same in polarity and a relationship expressed by |SP1|>|V 2|>450|V1|>=|SP2| is satisfied. Toner is reversely developed in the exposed portion. Thus, the development bias voltage to the developing roller 51 located upstream in the direction of the movement of the photoreceptor is set lower than the development bias voltage to the developing roller 52 located downstream. |
