Developing device to form electrostatic latent images

A device to develop an electrostatic latent image in an imaging apparatus, the device comprising:

• a developer container including first and second passages coupled to each other through first and second openings to form a circulation passage;
• a first stir-and-transport member located in the first passage and including a first helical blade to stir and transport a developer from the first opening to the second opening along the first passage in a first direction and to supply the developer to a developing roller;
• a second stir-and-transport member located in the second passage and including a second helical blade to stir and transport the developer from the second opening to the first opening along the second passage in a second direction;
• and
• a developer discharge pipe coupled to the developer container to communicate with a downstream side of the first passage,
• wherein the first stir-and-transport member includes a first reverse helical blade located downstream of the first helical blade and located downstream of the second opening, the first reverse helical blade comprising two or more reverse helical blades, and
• wherein the pitch of the first reverse helical blade is between approximately 0.5 times and 1.5 times the pitch of the first helical blade, the pitch being a distance between adjacent spirals of a particular one of the two or more reverse helical blades in a direction of an axis of rotation.