| 摘要 |
PURPOSE:To obtain a high developing density and to reduce toner adhesion to the bright part of an electrostatic image by moving an electrostatic image carrier so that an electrostatic image formation surface is not contacted with a toner brush and impressing a bias voltage between the carrier and a cylindrical sleeve to visualize the electrostatic image. CONSTITUTION:While being violently agitated on the cylindrical sleeve 3 by the rotation of the sleeve 3 and a magnetic roll 4, toner grains forming toner brush 5' are carried to a developing part. Although the toner grains of good quality which are sufficiently positively charged by the AC component of a bias voltage can be reciprocated between the sleeve 3 and an electrostatic image formation surface 2, defective toner grains cannot be reciprocated. Consequently, only the toner grains of good quality are adhered to the surface 2 in accordance with the image pattern of the surface 2. Consequently, the bright part of the picture image can be prevented from the adhesion of defective toner grains and a picture image reduced at its ground fogging can be obtained. |
