ELECTROSTATIC CHARGE IMAGE DEVELOPING CARRIER, ELECTROSTATIC CHARGE IMAGE DEVELOPER AND IMAGE FORMING METHOD

摘要

PROBLEM TO BE SOLVED: To prevent a drop-out at the gradation boundary part and image chipping which occur in a two-component magnetic brush development method and to improve the quality of color photographic image and graphic image by multicolor superposition development. SOLUTION: The saturation magnetization of nuclear body particles of the electrostatic charge image developing carrier obtd. by forming coating layers on the nuclear body particles is 50 to 70emu/g, the average particle size thereof is 30 to 40μm and the weight ratio of the particle size of <=22μm is 2.0 to 17.0wt.%. As to the shape coefft. defined by the equation: shape coefft. (SF)=(circumferential length of the projected image)<2>÷(4π×projection area), the shape coefft. of the particles having the average particle size or below is larger than the shape coefft. of the particles exceeding the average particle size.