	US 7,596,345 B2
	Image forming apparatus with a developer comprising at least a toner and a first external additive
Fumitake Hirobe, Ushiku (Japan); Yuichiro Toyohara, Fujisawa (Japan); Tatsuomi Murayama, Toride (Japan); and Akihiro Noguchi, Toride (Japan)
Assigned to Canon Kabushiki Kaisha, Tokyo (Japan)
Filed on Aug. 23, 2006, as Appl. No. 11/466,600.
Claims priority of application No. 2005-251658 (JP), filed on Aug. 31, 2005.
Prior Publication US 2007/0048021 A1, Mar. 01, 2007
Int. Cl. G03G 15/08 (2006.01)

U.S. Cl. 399—223 [399/227; 430/123.51]

6 Claims

1. An image forming apparatus, comprising:

a developing apparatus for developing an electrostatic image with a developer comprising at least a toner and a first external additive, said developing apparatus including a plurality of developing devices, wherein the plurality of developing devices includes at least a developing device containing a dark color toner and a developing device containing a light color toner which has an identical hue to that of the dark color toner and has a higher lightness than that of the dark color toner, and wherein the developing device containing the light color toner is subjected to a developing operation prior to another developing device;

a first transfer apparatus for sequentially transferring toner images, which have been developed by the plurality of developing devices, onto an intermediary transfer member; and

a second transfer apparatus for transferring the toner images from the intermediary transfer member all together onto a transfer medium;

wherein the first external additive comprises particles having an aspect ratio of not less than 1.0 and not more than 1.5 and a number average particle size of not less than 0.06 μm and not more than 0.3 μm, and has a toner coverage thereof with respect to the light color toner larger than that with respect to the dark color toner in a transferred state on the intermediary transfer member.