| 1. A developer container, comprising a cylindrical section containing developer therein, the cylindrical section having an
inner circumferential surface provided with a plurality of protruding portions raised inward along the cylindrical section,
which is arranged such that when the cylindrical section is driven to rotate on a central axis of the cylindrical section,
the developer stored in the cylindrical section is conveyed along the central axis by the plurality of protruding portions
so as to be discharged from an outlet of the cylindrical section, wherein the plurality of protruding portions are tilted
at an angle of not less than 10° nor more than 40° from the direction perpendicular to the central axis toward the developer
conveying direction, wherein a height of the protruding portions ranges between approximately 5.9% and 9.4% of an inner diameter
of the cylindrical section, and
wherein when cross-sections perpendicular to the central axis of the cylindrical section are projected from a longitudinal
direction of the cylindrical section, the cylindrical section has an inner circumference provided with one or more regions
where the protruding portions are not projected, and wherein those regions of the inner circumference of the cross-section
of the cylindrical section where the plurality of protruding portions are not projected occupy not less than 4% nor more than
13% of an entire length of the inner circumference of the cylindrical section.
|