Patent ID: 8406664

Claim:
An image forming apparatus comprising: a plurality of image carriers, each of which carries a unicolor image of a corresponding color; and a plurality of developing units corresponding to each of the image carriers, each of the developing units including a toner container that contains a first toner, the toner container including a developing chamber that houses a mixture of the first toner and a second toner, a supply chamber that houses the first toner, and a backflow prevention member that prevents flow of the mixture from the developing chamber into the supply chamber, a toner carrier, disposed in the developing chamber, that picks the first toner from the toner container and carries the first toner to a corresponding image carrier thereby developing a latent image on the corresponding image carrier with the first toner into a unicolor toner image, and the toner carrier collects the second toner, which remains on the corresponding image carriers, into the developing unit after the toner image has been transferred from the corresponding image carrier onto a transfer target member, and a regulating member configured to regulate a thickness of the first toner on the toner carrier, wherein the supply chamber is arranged laterally adjacent to the developing chamber, and wherein the backflow prevention member is disposed so as to divide the supply chamber and the developing chamber and has a height higher than positions at which the toner carrier and the regulating member are in contact.