Patent ID: 7894101

Claim:
A color image forming apparatus comprising: an image forming unit configured to form a toner image; an image bearing member configured to bear the toner image of a plurality of colors; a light-emitting element configured to perform irradiation using light; a photodetector configured to receive reflected light; a position detecting unit configured to determine a position of a position detection toner image on the basis of a detection result of the photodetector according to emission of the light onto the position detection toner image by the light-emitting element, the position detection toner image being of a plurality of colors and being formed on the image bearing member; a density detecting unit configured to detect density on the basis of a detection result of the photodetector according to emission of the light by the light-emitting element onto a density detection toner image formed on the image bearing member; and a light quantity adjusting unit configured to determine a light-emission quantity that is set when detecting the density, on the basis of a detection result of the photodetector according to emission of the light by the light-emitting element onto a light quantity adjustment toner image formed on the image bearing member, wherein the image forming unit forms the position detection toner image and the light quantity adjustment toner image within a one-rotation length of the image bearing member, wherein the position detecting unit determines positional displacement between the colors on the basis of a detection result of the position detection toner image formed within the one-rotation length, and wherein the light quantity adjusting unit determines the light-emission quantity that is set when detecting the density, on the basis of a detection result of the light quantity adjustment toner image formed within the one-rotation length, the detection result of the light quantity adjustment toner image formed within the one-rotation length being provided when the light-emitting element emits the light with a light-emission quantity that is set when the light emitting element emits the light onto the position detection toner image.