Developing device and image forming apparatus having operation mode for cleaning

A developing device comprising:

• a developer holder configured to supply developer to an image carrier on which an electrostatic latent image is formed;
• a removing member configured to remove the developer that has not been supplied to the image carrier and remains on the developer holder;
• a transport unit comprising a helical rotating body,
• wherein the transport unit is configured to rotate the helical rotating body to transport the developer and supply the developer to the developer holder;
• an accommodating unit that accommodates the developer holder, the removing member, and the transport unit;
• and
• a drive mechanism configured to operate the developer holder and the transport unit together in a first operation mode for image formation and to operate the developer holder and the transport unit individually in a second operation mode for cleaning an inside of the accommodating unit by removing the developer,
• wherein the drive mechanism is configured to, in the second operation mode, operate the helical rotating body of the transport unit in a forward direction and a reverse direction a predetermined number of times, and then operate the transport unit while a discharge port provided in the accommodating unit is opened, thereby discharging the developer through the discharge port, and
• wherein the drive mechanism is configured to, in the second operation mode, operate the transport unit while the developer holder is stopped at least when the helical rotating body of the transport unit is operated in the forward direction and the reverse direction the predetermined number of times.