Developing apparatus and image forming apparatus including the same

An image forming apparatus comprising:

• a photosensitive drum having an outer circumferential surface on which an electrostatic latent image is formed;
• and
• a developing apparatus for developing the electrostatic latent image formed on the outer circumferential surface of the photosensitive drum,
• wherein the developing apparatus comprises:
• a developing roller disposed facing the photosensitive drum on which the electrostatic latent image is formed, and to supply a developer, formed of carrier and toner and attached to an outer circumferential surface of the developing roller, to the photosensitive drum;
• a mixing transfer unit disposed facing the developing roller, and comprising:
• a first mixing transfer unit to supply the developer to the developing roller;
• and
• a second mixing transfer unit to mix the developer transferred by the first mixing transfer unit and supply toner and to transfer the mixture to the first mixing transfer unit;
• and
• an auxiliary mixing transfer unit disposed on a transfer path from the first mixing transfer unit to the second mixing transfer unit and to mix the developer transferred by the first mixing transfer unit and the supply toner,
• wherein the auxiliary mixing transfer unit comprises:
• a vertical transfer unit to vertically upward transfer the developer transferred by the first mixing transfer unit;
• and
• a mixing unit to mix the developer transferred by the first mixing transfer unit and the supply toner injected from an upper side of the mixing unit and to connect the second mixing transfer unit to a through hole formed in a lower portion of the mixing unit.

A developing apparatus comprising:

• a mixing transfer unit to transfer a developer to a developing roller, the mixing transfer unit comprising:
• a first mixing transfer unit;
• and
• a second mixing transfer unit connected to the first mixing transfer unit;
• and
• an auxiliary mixing transfer unit disposed in a path from the first mixing transfer unit to the second mixing transfer unit, the auxiliary mixing transfer unit comprising:
• a vertical transfer unit to lift the developer from the first mixing transfer unit;
• and
• a mixing unit to receive, in a upper portion of the mixing unit, the developer from the vertical transfer unit and a supply toner, to mix the developer and the supply toner, and to transfer the mixture through a lower portion of the mixing unit to the second mixing transfer unit.