Patent ID: 7860438

Claim:
An image forming apparatus, comprising: a plurality of image carriers including an image carrier configured to bear a toner image; an endless belt configured to sequentially contact a front surface thereof with the plurality of image carriers to form respective transfer nips; a plurality of bias applying rollers provided at positions corresponding to the respective image carriers, including a bias applying roller configured to apply a transfer bias to a back surface of the endless belt to transfer the toner image from the image carrier to the endless belt, wherein the toner image is formed of a toner including an external additive at an additive burial rate of not less than 40 percent and a mother particle including a binder resin and a colorant, wherein at least one of the bias applying rollers is located so as to satisfy the following relationship L> ( A /2)+( B /2)+ C where A is a diameter of the image carrier, B is a diameter of the bias applying roller, C is a thickness of the endless belt, and L is a distance between axis centers of the image carrier and the bias applying roller on a virtual plane perpendicular to an axis direction of the image carrier, and wherein each of the bias applying rollers is placed so as to satisfying the following relationship D< ( Wd/ 10) where D is a distance between the axis centers of each of the image carrier and the corresponding bias applying roller in a moving direction of the endless belt and Wd is a distance between centers of the image carriers.