Patent ID: 7512358

Claim:
A developer supply device configured to be capable of supplying a developer to an image forming portion for forming an image with the developer by transferring the developer comprised of powder particles to a surface of an image carrier in a form of arrangement of the image, while moving the surface of the image carrier in a direction of conveyance, the developer supply device comprising: a developer container configured to be capable of accommodating therein the developer, the developer container having an opening which is formed to have a longitudinal direction defined by a width direction perpendicular to the conveyance direction; a developer carrier adapted to have a longitudinal direction defined by the width direction, and configured to be capable of carrying the developer on a peripheral surface thereof, the developer carrier being supported by the developer container so as to rotate at the opening in a predetermined rotational direction around an axis parallel to the width direction, thereby supplying the developer to the image forming portion; and a developer leakage restrainer constructed of a thin plate, wherein the leakage restrainer is attached to the developer container and arranged at the opening so as to be butted against the peripheral surface of the developer carrier at a downstream side of the rotational direction away from the image forming portion over the entire longitudinal direction of the developer carrier, wherein the developer is comprised of toner having a substantially spherical shape, in which, when a circle equivalent diameter means a diameter of a sphere object having the same projected area as that of the powder particle, a ratio of the powder particles having the circle equivalent diameter of 3 to 20 Î¼m and a circularity of 0.98 or more to the entire powder particles of the developer is 60% or more based on the number of the particles, and a ratio of the powder particles having a circle equivalent diameter of 3 Î¼m or less to the entire particles is 35% or less based on the number of particles.