| 摘要 |
PURPOSE:To form the unipolar latent image of the whole picture in unicolor copying, and to form latent images while giving a difference in polarity by colors in bicolor copying, by exercising switching control over the charging condition and exposure condition by using a photoreceptor made of not less than two layers, photoconductive layer and insulating layer. CONSTITUTION:In black-and-white bicolor picture copying, primary charging 6 is kept negative siumltaneously with the white light exposure of lamp 16, and while the opposite positive charging is done as secondary charging 7, picture exposure to red light is done with shielding cyan filter 17. Next, an original is lightened via red filter 18 to hold the red part at the negative polarity, and development and transfer are carried out with two kinds of toner charged at the positive and negative polarities. In unicolor copying, charging is performed with the opposite polarity to primary charging 6 and while secondary charging 7 of the opposite polarity is done, the filter 17 is no used to perform simultaneous picture exposure 9 of the entire surface in white; and a black toner picture is formed in the 2nd development 11 and then transferred. Thus, two kinds of development, namely, red toner development 10 and black toner development 11 are enabled. |
