BINARY DEVELOPER, IMAGE FORMING DEVICE AND METHOD FOR FORMING IMAGE

摘要

PROBLEM TO BE SOLVED: To provide a binary developer which does not cause scattering of the toner or skin dirt on an image but is excellent in reproducibility for thin lines and halftone and moreover, to provide the binary developer which can form preferable images even after long-term use. SOLUTION: The binary developer consists of a magnetic toner comprising at least a binder resin and a magnetic material and of a magnetic carrier comprising at least a magnetic material. The particle size distribution of the magnetic toner sows that (1) the weight average particle size ranges from 6.0 to 10.0μm and that (2) the proportion of magnetic toner particles having <=5μm particle size is 5 to 60% in number and that (3) the proportion of magnetic toner particles having >=12.7μm particle size is >=2 vol.%. Moreover, the magnetic toner shows 10 to 25 emu/g magnetization in 5 kOe magnetic field.