| 摘要 |
PURPOSE:To prevent toner from adhering to and accumulating in a charging brush, and to stably carry out the charging of an image holder, and good image formation, by using an image formation device in which the charging brush is connected to the surface of the image holder so as to charge the image holder. CONSTITUTION:A photosensitive material 1 is charged by connecting a charging brush 2 of the brush density of 5-200,000/inch<2> to the surface of the photosensitive material 1, and an electrostatic potential image is formed by an optical system 3, on the surface of the photosensitive material 1, while a toner 5, no less than 90% of which is a toner whose shape factor SF-1 is no more than 160 in an expression below, and less than 1% of which is a toner whose shape factor SF-1 is no less than 170, is supplied to the surface of the photosensitive material 1, from a developing device 4, and the electrostatic potential image is thus made visible. [shape factor SF-1]=(maximum length<2>/area)Xpi/4X100, where area is the average value of the projected area of powder, and maximum length is the average value of the maximum length of the projected image of the powder. |
