| 摘要 |
PURPOSE:To obtain stable proper picture density by detecting the ground-part density of a photoreceptor and calculating the ratio to an initially detected value, multiplying this calculated value by the density detected value of a toner image in a nonpicture area, and controlling the toner density on the basis of the product. CONSTITUTION:A density detector 22 detects the density of a toner image of a picture pattern formed in the nonpicture area of the photosensitive drum 1 and the density of a ground part which is a nonpicture area where no toner image is formed and inputs them to a density detecting circuit 23. A correcting circuit 24 inputs the ground-part density detection signal VG from the density detecting circuit 23 and also inputs a ground-part density detection signal VGO in an initial state wherein the density detector 22 is not stained to calculate their ratio, thereby outputting a correcting signal Vx. A multiplying circuit 25 multiplies the image part density detection signal Vp from the density detector 23 by the correcting signal Vx and outputs the product result as a toner supplement amount signal TH to a main control circuit 2. |
