Patent ID: 7764901

Claim:
A developing device comprising: a casing that accommodates a developing agent and has an opening portion formed therein extending in a longitudinal direction; a developing agent carrier that is rotatably provided in the casing so as to be exposed from the opening portion and carries the developing agent; a leakage preventing member that is arranged at each of both longitudinal end portions of the casing to prevent the developing agent from leaking out of the casing; and a layer-thickness regulating member that comes into pressure-contact with a surface of the developing agent carrier to form a thin layer of the developing agent on the surface of the developing agent carrier, wherein the developing agent carrier comprises, in a longitudinal direction thereof: a seal area that is rubbed with the leakage preventing member; a side end area adjacent to the seal area on a longitudinal inside of the developing agent carrier; and a central area sandwiched between the side end areas, the layer-thickness regulating member comprises: a thin plate member which is formed in a thin plate-like shape extending along a longitudinal direction of the opening portion, whose downstream end portion of a rotation direction of the developing agent carrier, orthogonal to the longitudinal direction of the opening portion, is fixed to the casing, and whose upstream end portion of the rotation direction of the developing agent carrier is a distal end; and a projection member that is provided at the distal end of the thin plate member and protrudes toward a direction approaching to the developing agent carrier, and the projection member comprises a first pressure contact portion that comes into pressure-contact with the seal area, a second pressure contact portion that comes into pressure-contact with the side end area, and a third pressure contact portion that comes into pressure-contact with the central area, wherein a notched portion is formed at a position of the distal end of the thin plate member where the second pressure contact portion is formed, by cutting the thin plate member from an end edge of the distal end toward a downstream side of the rotation direction of the developing agent carrier.