| 摘要 |
PURPOSE:To prevent an edge effect on a toner image, by adding a charge neutralizing substance into the first developing fluid in developing the latent images having different polarities on a latent image bearing body with toners different in polarity and color. CONSTITUTION:For example, when the part of the latent image of photoreceptor 1 corresponding to the black part of an original is developed with black toner TBL and the red part with red toner TR, and after developing the latent image with positively charged toner TR, it is developed with negatively charged toner TBL, red boarder R1 is caused around black toner image BL1 with white ground W1 left between them. In order to prevent border R1, to a red developing fluid are added a polar solvent, such as methanol or water as a charge neutralizing material, an anionic or cationic surfactant having hydrophilic groups and hydrophobic groups, a hydrophilic aliphatic acid, such as oleic acid, etc., so as to adjust electric resistivity of the developing fouid in the range of 10<5>-10<10>OMEGAcm. The edge effect is prevented in the last development by neutralizing the charge of the first developing fluid. |
