| 摘要 |
PURPOSE:To obtain an excellent image at low cost by a small-sized bipolar magnetic field producing means by specifying the amount of charges per unit gram of a developer coating layer after control, the coating weight per unit square centimeter, and their product. CONSTITUTION:When the amount of charges per unit gram is Q (coulomb) and the coating weight per unit square centimeter is G (gram) as to a developer on a developing sleeve after the layer thickness is controlled, conditions such as 4.5X10<-9=G.Q<=15X10<-9>(Coul/cm<2>), 3X10<-6=Q<=15<-6>(Coul/g), and 0.5X10<-3=G<=3X10<-3>(g/cm<2>) are set. The Q is varied by varying the friction condition of a developer and the G is varied by varying the intensity of a magnet directed to a developer container; and the G decreases as the Q increase and increases as the Q decreases and thus the G and Q are put in a constant- value relation. Consequently, an excellent image is obtained by using a smaller- diameter bipolar magnet roll and the device is reduced in size on the whole. |
