JPS5691261A - Developing device - Google Patents

Abstract

PURPOSE:To make stable and uniform developing by the use of a one-component type high resistance nonmagnetic toner by moving the toner from a developing roller by an AC magnetic field to the electrostatic image holding body opposing at a gap wider than the toner coating layer thickness. CONSTITUTION:From a hopper 7, a one-component type high resistance nonmagnetic toner 8 is supplied intermittently via a constant rate replenishing member 10 and is conveyed while it is being held among the nylon or other flocks 9b a conveying roller 9. At this time, the toner 8 is frictionally charged by the friction between the flocks 9b and a developing roller 11, and the amount is regulated by a toner amount regulating member 13 or the like, whereby the charged toner 8 of predetermined thickness is coated on the developing roller 11. A photosensitive drum is opposed to the roller 11 at a gap wider than the coating layer thickness of said toner 8, and if an AC magnetic field for one reciprocation of the toner 8 is applied via an AC power source 15, the toner 8 reciprocatively moves between the drum 1 and the roller 11 according to the latent image of the drum 1. As a result, the stable and uniform development in which no photographic fogs and the like are caused is accomplished by using the one-component type high resistance nonmagnetic toner.