Organic belt photoreceptors are used by competitors for monochrome and color electrophotographic printing products. Solution coating of the active transport layer on the front side of a belt photoreceptor induces belt curl when the solvent evaporates. An anti-curl backcoating reduces the curl problem, but the backcoating needs to be transparent for electrical erase of the photoreceptor. Since typical conductive agents (e.g., carbon black) are optically absorbing, conductive fillers are not used in the backcoating. Consequently, an active neutralizing device is used to eliminate charge on the backcoating which otherwise increases belt drag. To eliminate the need for such devices, a transparent, conductive composite is desired for the backcoating. Thus, the proposal herein should be of value to both Xerox and competitors.
Since the backside transparent coatings used for photoreceptors in the Xerox iGen3 and Nuvera printers are insulating, active charge neutralizing devices are required to prevent electrostatic charge accumulation due to rubbing of the belt backside against drive and idler rolls, as well as backer bars that maintain critical gaps for different xerographic subsystems.
The backside of belt organic photoreceptors as used in monochrome and full-color electrophotographic printers is continually being contacted and rubbed by drive and idler rolls, as well as backer bars that maintain critical gaps between the photoreceptor and various electrophotographic subsystems. The active layers on the front side of the photoreceptor are typically coated from polymeric solvent solutions. The coatings are applied to a polymeric substrate for which a transparent conductive film has been deposited on the topside of the substrate. As the solvent evaporates from coatings, stresses are induced in the belt that causes it to undesirably curl. To counter the curling tendency, a solution coating is applied to the back of the substrate. This is referred to as an anti-curl backcoating. The backcoating typically consists of polycarbonate which is similar to the transport layer polymer for the front side coating, except the backside coating does not require the addition of hole transporting molecules. Thus, the thickness of the backcoating is typically only about half of the front coating such as, for example, ˜15 mm versus ˜30 mm.
To reduce drag forces acting on the backside of the belt moving against backerbars, additives on usually included in the anti-curl backcoating to increase the lubricity. Additives such as silica or Teflon in the range of 2 to 4% (percent) loading are typically used. Since the matrix polymeric material and additives tend to be insulating, the anti-curl backcoating will triboelectic charge. The charging increases the electrostatic drag force between the back side of the belt and stationary members such as the backer bars. The charging can be sufficient to actually cause belt slip on the drive rolls. To minimize this problem, active charge neutralizing devices are used to reduce the charging level of the anti-curl backcoating. For the iGen3 product, a carbon fiber brush in rubbing contact with the anti-curl backcoating is connected to a power supply to reduce the undesired triboelectric charging. For the Nuvera product, a conductive roll that can also be cleaned contacts the anti-curl backcoating.
Thus, there is a need for the present invention.