| 摘要 |
PURPOSE:To obtain a copy pictures excellent in quality with a simple-structure developing device by using a powdery material of two kinds of specific magnetic powdery material which can be charged frictionally in polarity opposite to each other, as a developer. CONSTITUTION:A powdery material (insulating powdery material) consisting of insulating magnetic particles which has >=10<14>OMEGAcm volume resistance is used as a toner, and magnetic characteristics of this insulating powdery material are so controlled that saturated magnetization (sigmas) is 4-30emu/gr. Another powdery material (conductive powdery material) consisting of magnetic particles which can be charged with a polarity oppsite to that of particles of said powdery material and have a saturated magnetization stronger than that of particles of said powdery material is added to said insulating powdery material to adjust the developer. When this developer to which the conductive powdery material is mixed is used, both powdery materials are held on a developing magnet roll and are charged frictionally till they are carried to a developing part, and they have electric charges of polarities opposite to each other. A mixture ratio of (A):(B)= (40-80):(20-60) by weight is preferable for mixing the insulating powdery material A with the conductive powdery material B. |
