US 5,845,185 A · Image forming apparatus

Abstract

An intermediate transfer drum has at least a drum main body having a volume resistivity of 10.sup.4 to 10.sup.8 .OMEGA.cm, and an insulating layer provided on an outer surface of the drum main body. A first transfer voltage applying roller is provided inside the intermediate transfer drum so as to be opposite to a photosensitive drum and so as to be in contact with an inner surface of the intermediate transfer drum. A transfer roller is provided inside the intermediate transfer drum so as to be opposite to a second transfer grounded roller and so as to be in contact with the inner surface of the intermediate transfer drum. By thus arranging an image forming apparatus wherein image formation is carried out with respect to recording paper through the intermediate transfer drum, an optimal first transfer voltage can be applied from the photosensitive drum to the intermediate transfer drum, while an optimal second transfer voltage can be applied from the intermediate transfer drum to the recording medium. As a result, the first transfer and the second transfer are individually and simultaneously carried out. Furthermore, since the intermediate transfer drum does not become large in size, it is avoidable that the image forming apparatus becomes bulkier, while the lowering of the copying speed can also be suppressed.

Claims48

Dependent claims

An image forming apparatus comprising:

at least one photosensitive drum;
an intermediate transfer medium onto which a toner image formed on said photosensitive drum is transferred;
pressing means for pressing a recording medium against said intermediate transfer medium;
at least one first electrode capable of causing a first potential difference to be generated between said first electrode and said photosensitive drum, said first electrode being provided inside said intermediate transfer medium so as to be opposite to said photosensitive drum and so as to be in contact with an inner surface of said intermediate transfer medium;
and
a second electrode capable of causing a second potential difference to be generated between said second electrode and said pressing means, said second electrode being provided inside said intermediate transfer medium so as to be opposite to said pressing means and so as to be in contact with the inner surface of said intermediate transfer medium,
wherein a first transfer and a second transfer are carried out so that image formation is carried out, during the first transfer a toner image being transferred from said photosensitive drum to said intermediate transfer medium in accordance with the first potential difference, during the second transfer a toner image being transferred from said intermediate transfer medium to the recording medium in accordance with the second potential difference.

4 more elements

Dependencies are inferred from the claim text.

Image forming apparatus

Life of this patent

Image forming apparatus

Life of this patent

Abstract

Claims48