| 摘要 |
In a constitution provided with no primary-transfer roller, in order to ensure a contact length between each of photosensitive drums and an intermediary transfer belt, the photosensitive drums are disposed in entering amounts at a plurality of levels with respect to a stretching surface of the intermediary transfer belt, and therefore an apparatus is upsized in a height direction. In order to avoid this, four image bearing members are arranged, along the intermediary transfer belt, in the same entering amount with respect to the stretching surface of the intermediary transfer belt, and a depressing member for depressing a belt surface between two central image bearing members toward an outside is provided. |
| 主权项 |
1. An image forming apparatus comprising:
a movable endless intermediary transfer belt; a plurality of supporting rollers, including a first supporting roller and a second supporting roller, for supporting said intermediary transfer belt; first to fourth photosensitive drums which are arranged along said intermediary transfer belt between the first supporting roller and the second supporting roller in the order of said first photosensitive drum, said second photosensitive drum, said third photosensitive drum and said fourth photosensitive drum from an upstream side toward a downstream side with respect to a direction in which said intermediary transfer belt moves, and which contact said intermediary transfer belt, wherein toner images transferred from said first, second, third and fourth photosensitive drums on said intermediary transfer belt at first, second, third and fourth transfer portions, respectively, are transferred from said intermediary transfer belt onto a recording material, and wherein said first to fourth photosensitive drums are disposed at positions where a plane of said intermediary transfer belt is disposed inwardly of a phantom common tangential line, of the first supporting roller and the second supporting roller, formed on a photosensitive drum side in a plane perpendicular to rotation centers of said photosensitive drums; and a depressing member for outwardly depressing the plane of said intermediary transfer belt between said second photosensitive drum and said third photosensitive drum. |
