Patent ID: 9020404
Filing Date: 2015-04-28
Classification: G03G

Abstract:
1. A developing unit comprising, in order, from an upstream toner movement side to a downstream toner movement side of the unit: a toner storage portion for containing toner; a development portion for receiving the toner from the toner storage portion and including an auxiliary supply roller, a toner-supply roller, and a developing roller to supply the toner to a photosensitive body, the supply roller and the auxiliary supply roller rotating while facing each other to supply the toner downstream to the developing roller, wherein an inequality that |D−(R1+R2)|≦1.0 mm is satisfied, where a distance between centers of the auxiliary supply roller and the supply roller in a first region where the auxiliary supply roller and the supply roller face each other is D, a radius of the supply roller is R1, and a radius of the auxiliary supply roller is R2, wherein the supply roller faces the developing roller at a second region, wherein the auxiliary supply roller is located at a downstream side of the supply roller with respect to a rotation direction of the developing roller, wherein the auxiliary supply roller and the supply roller deliver the toner from the toner storage portion through the first region to the second region so that a toner pressure is supplied to the second region, wherein the auxiliary supply roller is separated from the developing roller by a space, and wherein some of the toner moves from the second region, through the space and back to the toner storage part, wherein the supply roller and the auxiliary supply roller rotate such that surfaces of the supply roller and the auxiliary supply roller move in the same direction in the first region, and the supply roller and the developing roller rotate such that surfaces of the supply roller and the developing roller move in opposite directions in the second region, and wherein the center of the auxiliary supply roller is located between a vertical straight line passing through the center of the supply roller and a vertical straight line passing through a center of the developing roller.