| 摘要 |
PURPOSE:To eliminate irregularity in the image density due to gap fluctuation by making the precharger potential higher than the discharge starting potential at the maximum gap to make the difference is potential between the texture and a latent image portion constant with the use of an after charge electrode. CONSTITUTION:The dielectric layer surface 3 of a drum 1 turning clockwise is charged uniformly with th precharge potential by a charger 4. The charged potential is made higher than the discharge starting voltage at the maximum gap because the gap between the dielectric surface 3 and a needle-shaped electrode 27 is fluctuated. The layer 3 has its preset portion discharged by means of the electrode 27 to form an electrostatic latent image, the potential of which is varied with the fluctuation in the gap to establish dispersion in the electrostatic contrast. An after charge electrode 28 is disposed in th vicinity of the electrode 27 to establish the discharge of such texture potential portion of the electrode grounded together with the surface 3 as has a higher than the discharge starting voltage at the gap, thereby to discharge the charges which are higher than the discharge starting voltage. As a result, the texture potential of the surface 3 is made equal to the discharge starting voltage to make the electrostatic contrast constant. |
