| 摘要 |
A colour image forming apparatus includes coloured toner image forming devices each developing an electrostatic image with coloured toner (Y,M,C) to form a coloured toner image and a transparent toner image forming device developing an electrostatic image with transparent toner (T) to form a transparent toner image whereby the superimposed and transferred toner images are fixed on a transfer medium (S). An image forming operation by the transparent toner image forming device is controlled in such a manner that the heights (h 1 ,h 2 ,h 3 ,h 4 ,H) of the superimposed toner images (R) fixed by the fixing device are substantially constant. The transparent toner has an absolute value for a charge amount per unit weight smaller than an absolute value for the charge amount of each of the coloured toners per unit weight so that thickness irregularities and gloss unevenness of the output toner image (SR) is prevented by using a standard developing bias contrast. |
