| 摘要 |
PURPOSE:To perform development free from ground stains by forming a pressure roller with expandable material. CONSTITUTION:The pressure roller 3 of a pressure development device 2 which develops electrostatic latent images formed on a photosensitive drum 1 is formed by covering a thin film 32 composed of conductive material on the surface of a roller body 31 composed of expandable conductive elastic material. If with this arrangement the force for pressing the pressure roller 3 to the photosensitive surface of the photosensitive drum 1 is set relatively large, the pressure being exerted per unit area of the photosensitive surface becomes extremely small, whereby the occurrence of the physical deposition of developer is prevented. Hence, when the magnetic brush formed on the ouside circumferntial surface of a sleeve 43 is deposited on the surface of the pressure roller 3 and the developer is deposited on the electrostatic latent images formed on the photosensitive surface through contact with the photosensitive surface of the photosensitive drum 1, the stable development free from ground stains as against mechanical vibrations of the device is accomplished. |
