Developing device and image forming apparatus that uses this developing device

An image forming apparatus for forming images using a developing device, comprising a top cover whose front side opens and closes about an axis disposed in the far side when viewed from the front surface of a main body of the image forming apparatus, and configured so that the developing device can be inserted and removed from an aperture formed by opening the top cover upwards,

• wherein the developing device comprises:
• a toner housing unit within the chassis thereof;
• a first rib formed projecting from a first main wall surface, which is the side surface with the maximum area in the chassis;
• and
• a second rib formed projecting from a second main wall surface, which is the side surface in opposition to the first main wall surface,
• the first rib being disposed in a position higher than the second rib in the height direction, and
• the first main wall surface of the developing device being disposed to the far side of the image forming apparatus.

A process cartridge, comprising a developing device integrally formed with at least a photosensitive member,

• wherein the developing device comprises:
• a toner housing unit within the chassis thereof;
• a first rib formed projecting from a first main wall surface, which is the side surface with the maximum area in the chassis;
• and
• a second rib formed projecting from a second main wall surface, which is the side surface in opposition to the first main wall surface,
• the first rib being disposed in a position higher than the second rib in the height direction.