| 摘要 |
PURPOSE:To prevent the degradation of the image quality of a visual image and to improve the reproducibility of of a half-tone image by applying an alternating current bias voltage on a toner carrier, and setting frequency and peak- to-peak values whose minimum voltage value is subtracted from the maximum voltage value within a specific range. CONSTITUTION:As the toner carrier, a fine closing electric field is formed in the vicinity of the surface of the carrier by selectively holding a charge on the surface, and the toner carrier 5 attracting electrifying toner 4 by a closing electric field and carrying it is used. The alternating current bias voltage is applied on the toner carrier 5, its frequency is set at 200Hz <= 500Hz, and the peak-to-peak values whose minimum voltage value is subtracted from its maximum voltage value is set at 200V <= 500V. Therefore, the occurrence of the leakage of the charge so as to disturb an electrostatic latent image on a photosensitive body 1 between the photosensitive body 1 and a developing roller 5 is prevented. Thus, the degradation of the image quality of the visual image is prevented, and the reproducibility of the half tone image is improved. |
