JPS56137374A - Developing device - Google Patents

Abstract

PURPOSE:To control the amount of magnetic toner on a sleeve by providing a nonmagnetic plate which opens and closes a toner replenishing port according to the toner amount on the sleeve. CONSTITUTION:A magnet roll 1 and a nonmagnetic cylindrical sleeve 2 both rotate in the (x) direction, by which the magnetic toner 43 is conveyed in (y) direction. If the revolution ratio between the magnet roll and the sleeve is kept at >=20, the layer 44 of the toner of a fixed thickness is formed from the proximate position of a photosensitive drum 5 and the sleeve toward the direction of a toner replenishing device 3. The layer 44 grows successively and arrives at a nonmagnetic plate 6. The nonmagnetic plate 6 in the state free from any force is positioned in the position shown by the solid lines. The nonmagnetic plate has plural openings 61 at prescribed intervals in the longitudinal direction near the leading end part, and the successively grown toner goes round onto the nonmagnetic plate through these openings. The toner having thus gone round is sucked by the magnet roll, and the nonmagnetic plate assumes the position of the broken lines.