| 摘要 |
The developing apparatus includes a toner, a developing container, a developing roller, and a toner layer thickness controlling member,
wherein the toner contains toner particles containing a binder resin and a colorant, and silica fine particles; the covering rate X1 of the surface of each of the toner particles with the silica fine particles is 40.0 to 75.0 area %; and a diffusion index represented by X1/X2 satisfies a predetermined range where the theoretical covering rate with the silica fine particles is defined as X2,the developing roller includes a substrate, a base layer, and a coverage portion; and the volume resistivity of the coverage portion and the average thickness of the coverage portion are within predetermined ranges. |
| 主权项 |
1. A developing apparatus comprising:
a toner, a developing container accommodating the toner, a developing roller rotatably held, the developing roller carrying the toner fed from the developing container on the surface of the developing roller to form a toner layer and conveying the toner, and a toner layer thickness controlling member controlling the thickness of the toner layer, wherein the toner comprises toner particles containing a binder resin and a colorant, and silica fine particles, a covering rate X1 of the surface of each of the toner particles with the silica fine particles, which is determined with an X-ray electron spectroscope for chemical analysis (ESCA), is 40.0 area % or more and 75.0 area % or less, a diffusion index represented by Expression 1 satisfies Expression 2:
diffusion index=X1/X2 (Expression 1)diffusion index≧−0.0042×X1+0.62 (Expression 2)where a theoretical covering rate with the silica fine particles is defined as X2, and wherein
the developing roller comprises a substrate, a base layer on the outer peripheral surface of the substrate, and a coverage portion disposed, directly or via another layer, on an outer periphery of the base layer, the coverage portion has a volume resistivity of 1.0×108 Ω·cm or more, and has an average thickness of from 0.3 μm to 5.0 μm. |
