Developing device and image forming apparatus provided with same

An image forming apparatus, comprising:

• an image bearing member configured such that an electrostatic latent image is to be formed on a circumferential surface;
• and
• a developing device for supplying developer to the image bearing member;
• wherein the developing device includes:
• a housing with a pair of wall portions;
• a developing roller rotatably supported in the housing between the pair of wall portions and configured to carry the developer;
• a developer supply path arranged along the developing roller and configured such that the developer is conveyed in a first direction and supplied to the developing roller;
• a developer conveyance path arranged along the developer supply path and configured such that the developer is conveyed in a second direction opposite to the first direction while being agitated;
• a pair of communication paths arranged at inner sides of the pair of wall portions and allowing communication between end parts of the developer conveyance path and end parts of the developer supply path;
• a supply-side conveying member including:
• a supply-side spiral member having a plurality of spiral revolutions formed about an axis and extending in the first direction and having a hollow interior formed radially inward of the spiral revolutions of the supply-side spiral member;
• a first rib member extending in the first direction and bridging adjacent ones of the spiral pieces of the supply-side spiral member;
• and
• a pair of supply-side shaft portions arranged at opposite end parts of the supply-side spiral member, rotatably supported on the wall portions and serving as a rotary shaft for the rotation of the supply-side conveying member, the supply-side conveying member being arranged in the developer supply path and configured to convey the developer in the first direction by being driven and rotated;
• an agitating-side conveying member including:
• an agitating-side spiral member having a plurality of spiral revolutions formed about an axis and extending in the second direction and having a hollow interior formed radially inward of the spiral revolutions of the agitating-side spiral member;
• a second rib member extending in the second direction and bridging adjacent ones of the spiral pieces of the agitating-side spiral member;
• a pair of agitating-side shaft portions arranged at opposite end parts of the agitating-side spiral member, rotatably supported on the wall portions and serving as the rotary shaft for the rotation of the agitating-side conveying member, the agitating-side conveying member being arranged in the developer conveyance path and configured to convey the developer in the second direction by being driven and rotated;
• and
• at least one of the supply-side conveying member and the agitating-side conveying member being formed with projecting members, the projecting members including at least one of:
• first projecting members extending in the first direction along an outer wall portion of the first rib member from a first area where the supply-side spiral member and the first rib member intersect and projecting radially outward in the rotation of the supply-side conveying member;
• and second projection members extending in the second direction along an outer wall portion of the second rib member from a second area where the agitating-side spiral member and the second rib member intersect and projecting radially outward in the rotation of the agitating-side conveying member, wherein
• the hollow interior of the supply-side conveying member is formed between the pair of the supply-side shaft portions,
• the hollow interior of the agitating-side conveying member is formed between the pair of the agitating-side shaft portions, and
• the supply-side conveying member and the agitating-side conveying member have no other shaft part in each of the hollow interiors thereof.