| 摘要 |
PURPOSE:To change a picture quality of a reproducing picture in accordance with a kind of an original, by constituting so that a developing magnetic pole can be varied by an angle theta to the upstream side in the moving direction of a developer, and changing the Y characteristic. CONSTITUTION:When a lever 5 is rotated by an angle theta, a magnet roll 3 is rotated, and a developing magnetic pole N1 placed at the most adjacent point of an electrostatic latent image holding body 1 and a sleeve 2 is also rotated by theta and comes to a positon of N1'. As for a V-D curve in case when theta is set to 0-16 deg. by making a position of the magnetic pole N1 a reference, under the conditions that layer thickness of a magnetic toner 9 is about 120mum, the most adjacent interval between the electrostatic latent image holding body 1 and the sleeve 2 is 300mum, a magnetic flux density of the developing magnetic pole N1 by the magnet roll 3 is about 800G, a peripheral speed of the electrostatic latent image holding body 1 is 66mm./sec, a peripheral speed of the sleeve 2 is 63mm./sec, an alternating electric field impressed to the sleeve 2 is 650V amplitude, and 100V DC voltage is superposed on a sine wave of 160Hz frequency, an inclination of the V-D curve, namely, a Y value is small and a gradient is high in case when theta is 0 deg., but when theta is made large, Y bocomes large, picture reflection density rises, therefore, the gradient is bad but reproduction can be executed darkly without being fogged with a thin character. |
