| 摘要 |
PURPOSE:To prevent changes in performance for a long-term use by using such resin particles that the projection face of the particle gives specified relation between the outer contact circle and inner contact circle each having at least three contact points with the projection face and between the peripheral length of the face and the circumference of the inner circle, and using magnetic particles having specified magnetic characteristics. CONSTITUTION:The inner contact circle of radius (r) and the outer contact circle of radius R, each having at least three contact points with the projection of the particle, satisfy the relation 1.00<R/r<=1.20. The peripheral length L of the projection face and the circumference l of the inner circle satisfy the relation 1.01l<l<2.00l. The magnetic characteristics of the magnetic particles are specified to >=40emu/g magnetization measured in 1,000Oe magnetic field. Thereby, the developer is almost free from deposition of carrier and has high durability in the performance as a developer. The high picture quality in the initial state can be maintained for a long time. |
