JPS6474569A - Developing device for electrostatic latent image - Google Patents

Abstract

PURPOSE:To prevent the contamination of the surface of a magnetic brush by placing a conductive member so as to come into contact with a magnetic brush, and also, providing a magnet on this member. CONSTITUTION:A toner replenished from a hopper is converted to a thin layer by a blade 12 and brought to frictional electrification, and by a bias voltage, the toner on a roller 8 is fed to a carrier on a developing sleeve 4, and a magnetic brush 6 is formed. On the way feeding it to a developing area, it is brought to reciprocating stirring in the axial direction of the sleeve 7 by a screw 16 and 17 and equalized, and the toner is fed to the developing area by controlling its quantity by a blade 15. In the developing area, a tuft of the brush 6 comes into contact with an electrostatic latent image on a photosensitive drum 1 and the development is executed. In the downstream of the developing area, the inner wall of a casing 3 for covering the developing sleeve 4 comes into contact with a raised part of the brush 6, and moreover, brought into contact surely by attracting the brush 6 by a buried magnet 18. In such a way, a stronger stress is given to a developer, the frictional electrification is executed surely, an unnecessary charge for exerting an undesirable influence is always eliminated from the brush in advance, and the generation of the surface contamination can be prevented satisfactorily.