| 摘要 |
PURPOSE:To prevent a toner image developed by the first developing device, from being omitted from on a recording body in case of a development by the second developing device, by using a magnetic toner as a developer of the second developing device. CONSTITUTION:In order to execute printing by the second color, a photosensitive body 1 is exposed by the second exposing light source 18 for carrying the second information again after a development by the first color is completed, and also must be developed to the second color by the second developing device 19. In such a case, when a magnetic toner 24 is used as a developer, and a magnetic brush is formed by applying a deviation voltage to the extent of the surface potential of an unexposed part of the photosensitive drum 1 by a deviation voltage source 25, the magnetic brush is softer than that which has used a two-component toner, and it is unnecessary to make it abut firmly onto the latent image surface. In such a way, a mechanical force for scraping the first toner image is made small, also an electrostatic attracting force of the second carrier and the first toner 21 does not work, and an electrostatic field operate in the direction for pressing the first toner 21 against the latent image surface by a comparatively high deviation voltage of the time of an inversion development, therefore, the first toner is scarcely omitted. |
