| 摘要 |
PURPOSE:To attain the gradation of a high density part and the adjustment of a lower density part by providing a means for adjusting a developing bias potential or an exposure quantity so as to adjust a low density picture and a means for adjusting an electrostatic potential so as to adjust the gradation in a high density area. CONSTITUTION:A lamp 12, a charger 24, developing rollers 281 and 282 are connected to voltage power sources 46, 44 and 48, which are adjusted by adjusting levers 50, 52 and 54. The electrostatic potential in case of copying an original having important information in intermediate and high density areas is dropped by the adjusting lever 50. However, information located in the low density area of the original is hardly copied. In order to copy said information, first the electrostatic potential is dropped, and the exposure amount is reduced by the adjusting lever 52, whereby the gradation from the low density part to high one of the original can be improved by a copied picture. Moreover the electrostatic potential is dropped and the developing bias potential is also reduced by the adjusting lever 54 to obtain the same result. |
