Patent ID: 7310484

Claim:
An image forming apparatus, comprising: a cyan color image formation unit which uses a cyan color toner to form a cyan color image; a magenta color image formation unit which uses a magenta color toner to form a magenta color image; a yellow color image formation unit which uses a yellow color toner to form a yellow color image; a black color image formation unit which uses a black color toner to form a black color image; an invisible image formation unit which uses an invisible toner to form an invisible image; and a control apparatus which stops respective image formation operations of the cyan color image formation unit, the magenta color image formation unit, and the yellow color image formation unit when only the black color toner and the invisible toner are used for formation of an image, by lowering charging output of respective chargers in the cyan color image formation unit, the magenta color image formation unit and the yellow color image formation unit to a prescribed level.