Electrophotography – Image formation – Development
Reexamination Certificate
2001-12-07
2003-10-07
Beatty, Robert (Department: 2852)
Electrophotography
Image formation
Development
Reexamination Certificate
active
06631250
ABSTRACT:
This invention relates generally to a development apparatus for ionographic or electrophotographic imaging and printing apparatuses and machines, and more particularly is directed to a developer filtration module.
Generally, the process of electrophotographic printing includes charging a photoconductive member to a substantially uniform potential so as to sensitize the surface thereof. The charged portion of the photoconductive surface is exposed to a light image from either a digital imaging system [for example a scanning laser beam] or an original document being reproduced. This records an electrostatic latent image on the photoconductive surface. After the electrostatic latent image is recorded on the photoconductive surface, the latent image is developed. Two component and single component developer materials are commonly used for development. A typical two component developer comprises magnetic carrier granules having toner particles adhering triboelectrically thereto. A single component developer material typically comprises toner particles. Toner particles are attracted to the latent image forming a toner powder image on the photoconductive surface, the toner powder image is subsequently transferred to a copy sheet, and finally, the toner powder image is heated to permanently fuse it to the copy sheet in image configuration.
The electrophotographic marking process given above can be modified to produce color images. One color electrophotographic marking process, called image on image processing, superimposes, that is sequentially develops, toner powder images of different color toners onto the photoreceptor prior to the transfer of the composite toner powder image onto the substrate. While the image on image process has advantages over other methods for producing color images, it has its own unique set of requirements. One such requirement for noninteractive development systems is that those do not scavenge or otherwise disturb a previously toned image.
Since development systems, such as conventional two component magnetic brush development and AC jumping single component development are known to disturb toner images, they are not in general suited for use in an image on image system. Thus there is a need for noninteractive development systems. There are several types of noninteractive development systems that can be selected for use in an image on image system. Most use a donor roller for transporting charged toner to the development nip; the development nip is defined as the interface region between the donor roller and photoconductive member. In the development nip, the toner is developed on the latent image recorded on the photoconductive member by a combination of mechanical and/or electrical forces. It is the method by which the toner is induced to leave the donor member which primarily differentiates the several options from each other; both single component and two component methods can be utilized for loading toner onto the donor member.
In one version of a noninteractive development system, a plurality of electrode wires are closely spaced from the toned donor roller in the development zone. An AC voltage is applied to the wires to generate a toner cloud in the development zone. The electrostatic fields associated with the latent image attract toner from the toner cloud to develop the latent image. It is this configuration which is utilized in both “Scavengeless Development” and “Hybrid Scavengeless Development”.
In another version of noninteractive development, interdigitated electrodes are provided within the surface of a donor roller. The application of an AC bias between the adjacent electrodes in the development zone causes the generation of a toner cloud.
Another type of development technology, known as jumping development, may also be configured to be noninteractive. In jumping development, voltages are applied between a donor roller and the substrate of the photoreceptor member. In one version of jumping development, only a DC voltage is applied to the donor roller to prevent toner deposition in the non-image areas. In the image areas, the electric field from the closely spaced photoreceptor attracts toner from the donor. In another version of jumping development, an AC voltage is superimposed on the DC voltage for detaching toner from the donor roller and projecting the toner toward the photoconductive member so that the electrostatic fields associated with the latent image attract the toner to develop the latent image.
In the system herein before described, it has become highly desirable to have a toner filtering system to remove contamination, particularly in the form of clothing and paper fibers, before the toner reaches the developer housing, to obviate copy quality and machine reliability problems. Also it is desirable to prevent toner particles from adhering together into large scale clumps which ride on the top of the developer material in the developer housing negatively effecting the blending and admixing of the incoming toner.
SUMMARY OF THE INVENTION
One aspect of the invention provides an electrophotographic printing machine, wherein an electrostatic latent image recorded on a photoconductive member is developed to form a visible image thereof, said electrophotographic printing machine including a system, for removing contaminates from toner in a developer housing, the system including a filter system, positioned in a path of flowing developer material, said filter system having a screen for permitting developer material to travel therethrough while inhibiting contaminants from traveling therethrough when vibrated; said screen being inclined to the path of flowing developer material a vibration driver, operatively connected to said screen, for vibrating said screen.
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Drinkwater Wayne D.
Enderle Jan M.
Franzen James J.
Playfair David B.
Beatty Robert
Dean, II Lloyd F.
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