| 摘要 |
PURPOSE:To reduce the press-contacting pressure of the elastic body when a device is not in operation, and to prevent a developer interposed between an elastic body and a developer carrier from sticking to the elastic body or developer carrier by providing a pressure control means. CONSTITUTION:The pressure control means 38 reduces the press-contacting force of the elastic body 36 to the developer carrier 35 when the device is not in operation and presses the elastic body 36 against the carrier 35 with specific press-contacting force when the device is in operation. This pressure adjusting means 38 used a solenoid; and a holder 31 supported rotatably so that the elastic body 36 leaves the surface of the carrier 35 is rotated by attraction when the solenoid is excited to press the elastic body 36 against the carrier 35 at the specific pressure, and the contact-pressing pressure is reduced by the restitutive force of the elastic body 36 when the solenoid is not excited. The solenoid 38 is provided with position adjusters 39A and 39B to perform a fine adjustment of the displacement extent of the holdfer 31. The holder 31 constitutes a part of the housing 34 of the developing device which contains a developer T. Consequently, the developer T is prevented from sticking to the elastic body 36 or carrier 35 when the device is no in operation and forms a thin layer on the surface of the carrier 35 when the device is in operation. |
