| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a two component developer which retards the deterioration of developing characteristics during use over an extended period of time so that it is possible to form high quality images of sufficient image density and high resolution over an extended period. Ž<P>SOLUTION: The two component developer comprises at least a toner and a carrier, wherein carrier particles comprise magnetic material powder dispersed in a phenol-formaldehyde resin, and have an average of the shape coefficient SF-1 of 1.0 to 1.2 and an average of the shape coefficient SF-2 of 1.1 to 2.5, and a volume based median diameter of from 10 to 100 μm. The toner includes: at least colored particles; and external additive particles comprising a complex oxide particle containing silicon atoms, and titanium atoms or aluminum atoms, and a ratio (R1)/(R2) is smaller than 1, where R2 is the existing ratio of the silicon atoms in the surface layer of the external additive particles and R1 is the existing ratio of the silicon atoms in the whole of the external additive particles. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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