| 摘要 |
PURPOSE:To faithfully reproduce density and a thin line by discriminating whether the cause of the lowering of image density is the set condition of a developing device or a pattern latent image forming condition and controlling the rotating speed of a developing sleeve or the electrostatic charging potential of a photosensitive body. CONSTITUTION:A pattern latent image is formed on a photosensitive body 1 and developed by a 1st developing device 10 to form a 1st toner pattern image TP1. Then, the density D1 of the TP1 is detected by a density sensor 17. Next, an electrostatic charger 2 is turned off and the bias of the developing device 10 is switched to +500V to form a 2nd toner pattern image TP2, and the density D2 is read by the sensor 17. When D1<DA and D2<DB hold between 1st reference density DA and 2nd reference density DB, the revolving speed of a motor 43 is made high to accelerate the revolving speed of the sleeve 22a so that a developing material carried to a developing area is increased to recover the image density. When D1<DA and D2>DB hold, the electrostatic charging potential of the photosensitive body 1 is made high. Thus, the density and the thin line are faithfully reproduced. |
