| 摘要 |
PURPOSE:To form a developed image having high picture quality and high image density and to make the device high speed and small by specifying volume occupied by magnetic particles to the volume of a space between a latent image carrier and a developer carrier. CONSTITUTION:A developer container 21 that contains a developer having toner particles 28 and magnetic particles 27, a developer carrying member 22, the first magnetic field generating means 23a, 23d, a developer controlling member 24, the second magnetic field generating means 23b, 23c and an alternating electric field forming means 34 are provided. The volume occupied by magnetic particles 27 is made to 10% to 50% of the volume of space constituted of an electrostatic latent image carrier 1 and the developer carrying member 22 and the quantity of application of the developer on the developer carrying member 22 in the downstream of a controlling member 4 is made >5.0X10<-2>g/cm<2> and <=10.0X10<-2>/cm<2>. Thus, crest of scattered state is formed, and developing characteristic is improved by its action. Further, it is made possible to heighten the speed of developing and to reduce the diameter of the sleeve.
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