Patent ID: 7965957

Claim:
A developing device having a toner housing unit within a chassis thereof, comprising: a first rib formed projecting from a first main wall surface, which is a side surface with the maximum area in the chassis; and a second rib formed projecting from a second main wall surface, the second main wall surface is disposed opposite to the first main wall surface, wherein the first rib is disposed higher than the second rib in a vertical direction, wherein the chassis is formed integrally by joining a first case disposed in a higher position in the vertical direction and a second case disposed in a lower position, and a part of the joint surface forms the first rib and the second rib, wherein the first case has a depression shape formed in at least one of the first main wall surface and the second main wall surface such that a portion of the first case with the depression shape is narrower in a width direction between the first main wall surface and the second main wall surface than a nominal portion of the first case, wherein a developing roller disposed near a bottom of the developing device is directly visible from the depression shape when viewed downward from a top of the developing device, and wherein a partitioning member which partitions the toner housing unit into a first section and second section within the chassis is provided between the first case and the second case, the first section is separate from the second section.