US Patent 7092647 Image forming apparatus

This invention realizes and provides an image forming apparatus in which the presence or absence of a toner remaining in a toner storing portion is judged by a patch detecting method, characterized in that the wrong detection of the judgment of the presence or absence of the toner can be prevented and the lowering of image density can be suppressed. In an image forming apparatus having a first toner supply controller for controlling the driving time of a toner supplying portion on the basis of the video count number of the density signal of an image information signal, and a second toner supply controller for correcting the driving time of the toner supplying portion determined by the first toner controller, and designed such that the presence or absence of the toner remaining in the toner storing portion is judged on the basis of the density signal of a standard toner image, when the density signal of the standard toner image is equal to or less than a predetermined value, the driving time of the toner supplying portion additionally corrected per image by the second toner supply controller is made longer than when the density signal of the standard toner image is greater than the predetermined value.