| 摘要 |
PROBLEM TO BE SOLVED: To shorten the interval between density detecting toner images, which are formed on an image carrier and different from each other in color, and to shorten the density detecting time, by making the timing of switching a developing unit just after the formation of the density detecting toner image of a different color is completed. SOLUTION: At the time of forming the density detecting toner image, a photosensor detects one of marks, then, an image signal is outputted and the operation signal of a cleaning device is outputted. The density detecting toner image is formed by the output of the image signal and the density of this toner image is detected by the photosensor. When the output of the image signal of this color is turned off, a developing unit switching signal is outputted to switch the developing unit used. When the photosensor detects the mark, the image signal is outputted again on the basis of the detected mark and the formation of the density detecting toner image of the different color is started. The density of the formed density detecting toner image is detected by the photosensor. In the above-mentioned manner, in toners of all colors, the density detecting toner images are formed and their densities are detected. |
