| 摘要 |
PURPOSE:To obtain a device capable of detecting the density of a referential toner image with high accuracy and capable of executing optimization as to image formation without increasing required time for process controlling by forming a detection starting referential mark by means of the exposure of a black straight line as a referential mark to a photosensitive body, for example, with a light source for the image formation. CONSTITUTION:A straight line is provided on a place which is further nearer to a starting end side than the place of a standard white board 32 provided on the starting end side in the scanning direction of a copy lamp 4 as to an original placing platen 2. The straight line is drawn as a black straight line, and is used for forming a toner image as a start mark which is the detection starting referential mark. That is, the toner image as the start mark is formed just before toner patch on a photosensitive drum 1. Therefore, density detection with respect to an area to be detected can be accurately executed by starting the density detection of a toner patch forming part after a specified time from time when the start mark is previously detected by an optical sensor 16. |
