| 摘要 |
PROBLEM TO BE SOLVED: To obtain a developer with which a good image can be formed without causing filming, splashing of a toner and image fog by specifying the shape of toner particles containing a positive electrification controlling agent, negative electrification agent, etc. SOLUTION: This developer contains toner particles in which at least two kinds of electrification controlling agents of a positive electrification controlling agent and a negative electrification controlling agent. The toner particles have 7 to 10μm 50% average diameter and 0.93 to 1.0 average circularity. Toner particles having <=0.93 circularity are included by 7 to 20% and the 10% average diameter in the distribution of particle size in accumulated number is 45 to 80% of the 50% average particle size. If the circularity is <0.93, the toner shows high aggregation degree to decrease the fluidity, which causes lack of the developing amt. of the toner on a photoreceptor and decreases the image density. Moreover, the cleaning property deteriorates and triboelectrification with the carrier is not enough to cause insufficient electrification. As a result, this causes filming of the toner on a drum, splashing of the toner in a copying machine and increase in image fog. |
