Kyocera Document Solutions Inc.

Eriko Takeuchi

Tamotsu Shimizu

Masashi Fujishima

Asami Sasaki

An image forming apparatus includes a developer, a development device, and an image bearing member. The developer includes an initial developer containing an initial carrier and a replenishment developer containing a replenishment carrier. The initial carrier has a surface roughness Sa1 of at least 0.3 μm and no greater than 1.0 μm. A ratio Sa1/Sa2 of the surface roughness Sa1 of the initial carrier to a surface roughness Sa2 of the replenishment carrier is at least 1.2 and no greater than 3.4. The packing volume Vp calculated from equation (1)'Vp=100×Y/(Z×DS)' was at least 40% and no greater than 70%. In equation (1), Y represents an amount of the developer conveyed by a developer bearing member. Z represents an apparent density of the initial developer. DS represents a width of a space between the developer bearing member and the image bearing member.

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Osaka, Japan

Eriko Takeuchi