| 摘要 |
PROBLEM TO BE SOLVED: To miniaturize an image forming apparatus without degrading image quality by adding specified fine ferrite particles and a fluidity enhancer to toner particles. SOLUTION: This developer contains as external additives the fluidity enhancer and the Mn-Zn type ferrite particles represented by the formula in which each of (x) and (y) is a molar fraction and (x) is 0.01-0.3 and (y) is 0.001-0.3, preferably, 0.01-0.3. This ferrite particles have, preferably, octahedral forms, awnd if they are no octahedral forms, but for example, spherical forms, their scraping grinding effect is lessened, and when acicular forms, they are ready to be attached to a photoreceptor or its developing sleeve and stain an image. It is preferred that the ferrite particles have an average particle diameter of 0.1-1.0 μm, especially 0.3-0.7 μm, and if below this range, they are apt to be attached to the photoreceptor, and if over this, striations occur. |
