| 摘要 |
PURPOSE:To improve the responsibility of picture density control not only by adjusting the toner density of a developer, but also by controlling the revolving speed of a developing roll. CONSTITUTION:When picture density decreases below set density by some extent, a controller A13 applies a voltage higher than a reference voltage to a motor 5, whose revolving speed increases. Therefore, the revolving speed of the developing roll 2 also increases and the amount of the developr 8 supplied to a developed area on the surface of a photosensitive body increases to make the picture density higher. Simultaneously, a controller B14 engages a motor 16 with a toner feeder 11 through a clutch 12 and toner is supplied to increase the toner density of the developer, increasing the picture density. Then, the revolving speed of the developing roll 2 is returned to a reference speed when the toner almost reaches the developed area of the photosensitive body to hold the set picture density. |
