Patent ID: 8160483

Claim:
An image forming apparatus comprising: a plurality of image bearing members spaced apart from each other and comprising a first image bearing member and a second image bearing member being disposed adjacent to the first image bearing member; an exposure unit to form a latent image on each of the image bearing members; a developing unit to form a visible image on each of the image bearing members; a transfer unit to transfer the visible image onto a printing medium, comprising a plurality of transfer rollers, which are respectively disposed opposite to the plurality of image bearing members and to form a transfer nip between each transfer roller and each image bearing member, and a plurality of erasers, which are respectively disposed between the plurality of transfer rollers and to erase a transfer voltage in a printing medium; and a fixing unit to fix the visible image on the printing medium, wherein the plurality of transfer rollers comprises a first transfer roller and a second transfer roller which are disposed opposite to the first image bearing member and the second image bearing member, respectively, and at least one of the plurality of erasers being disposed between the first transfer roller and the second transfer roller in a zone Z 1 satisfying the following formula: D 1≦ Z 1≦ D−D 3 D 1 =4.5 mm D 3 =4.5 mm 9.0 mm<D where D 1 is an allowable minimum distance between an end part of the eraser and a center of a first transfer nip formed between the first image bearing member and the first transfer roller; D 3 is an allowable minimum distance between the end part of the eraser and a center of a second transfer nip formed between the second image bearing member and the second transfer roller; and D is a distance between the center of the first transfer nip and the center of the second transfer nip.