Developing apparatus having a toner regulating member with an extended lifetime

摘要

A developing apparatus using monocomponent developer comprising: monocomponent magnetic toner; a developer carrying body for carrying and transporting the monocomponent magnetic toner; a magnetic field generation unit fixed inside the developer carrying body; a developer supply unit for supplying the developer carrying body with the monocomponent magnetic toner; and a developer trimming member furnished to the developer supply unit for pressed contact with the circumference of the developer carrying body. The developer trimming member is made of a spring material and tipped with a sliding part which contacts the circumference of the developer carrying body slidingly and which is made of a rubber material. In this setup, the following condition is met: aP>bP where, P stands for the initial point of contact of the sliding part with the developer carrying body, a for the upstream end position of the sliding part in the direction of sliding, b for the downstream end position of the sliding part in the direction of sliding, aP for the length of the line segment connecting the position a with the point P, and bP for the length of the line segment connecting the position b with the point P.