Patent ID: 7650086

Claim:
An image forming apparatus to perform an image forming processing to form toner images of colors different from each other, comprising: photoconductive bodies, each photoconductive body comprising a developing unit, the developing unit being configured to develop an electrostatic latent image on the surface of the photoconductive body and collect a residual toner remaining on the photoconductive body; image forming units for each color which superimpose the toner image on the photoconductive body on an intermediate transfer body moved in a specified direction, the intermediate transfer body transferring the superimposed toner image to a recording medium, a residual toner remaining on the intermediate transfer body after transferring the toner image to the recording medium being collected by a black developing unit via the photoconductive body, the image forming units for each color other than black transferring necessary toners to the intermediate transfer body based on detected amounts of plural color toners, and the black developing unit collecting the toners via the photoconductive body of the black image forming unit; a toner collecting unit configured to collect toners remaining on the intermediate transfer body; a ratio judgment unit configured to judge a mixing ratio of toners of plural colors included in the toners collected by the toner collecting unit; and a toner replenishing unit configured to replenish an insufficient color toner to the toners collected by the toner collecting unit based on the mixing ratio judged by the ratio judgment unit so that the mixing ratio becomes a specified ratio.