Electrophotography – Image formation – Development
Reexamination Certificate
1999-10-29
2001-07-17
Royer, William J. (Department: 2852)
Electrophotography
Image formation
Development
C399S281000
Reexamination Certificate
active
06263179
ABSTRACT:
The disclosures of each of the above mentioned patents and copending applications are incorporated herein by reference in their entirety. The appropriate components and processes of these patents may be selected for the apparatus and processes of the present invention in embodiments thereof.
BACKGROUND OF THE INVENTION
This invention relates generally to a xerographic development apparatus incorporating an improved agitation article which apparatus controllably and accurately conveys particulate imaging materials from a sump reservoir to an imaging member. More specifically the invention concerns a single component xerographic development apparatus and an agitation article therein which apparatus improves the flowability and the supply of imaging particulate materials, such as magnetic and non-magnetic toner particles, to a photoreceptor. The apparatus and article improve the overall imaging performance and imaging quality of printing machines that incorporate the improved hardware. The improved development apparatus solves the so-called “white banding” image defect problem.
The article, apparatus, and imaging method of the present invention solves important particulate transport and development problems and provides various advantages including: improved developer agitation; improved developer circulation; improved developer charging and developability; reduced or eliminated white banding image defects; increased development apparatus reliability; reduced downtime for blockage or leakage problems associated with the prior art development apparatus; preventing localized developer and toner agglomeration in the area near the donor roll; providing improved developer circulation between the sump and the surface of the donor roll; and improving developer charging stability.
One-component and two-component developer systems utilize toner that can be difficult to flow and charge controllably. This is particularly true of the toner used in one component systems. The toner tends to cake and bridge within the sump or within the developer housing. Also, this tendency to cake and bridge may cause soft blocked toner cakes to form within the developer housing which cakes can distort the charging of the toner and produce image defects in the printed images.
In addition, the developer on the donor roll often suffers severe high mechanical stress under low toner throughput condition. This is because the developer on the donor roll cannot readily get off the donor roll and circulate well with the developer in the housing. This stressed developer has poor powder flow, poor charging stability, and lower charge. Consequently, the solid area density of the prints decreases and the background grayness increases.
These and other problems are solved with the article, development apparatus, and imaging method of the present invention.
PRIOR ART
In U.S. Pat. No. 5,305,064, to Trott et al., issued Apr. 19, 1994, there is disclosed an electrophotographic apparatus in which toner particles are moved from the toner hopper or dispenser cartridge to the developer housing and onto the donor roller in a single component development system for use in color reprographic systems. A rotating holey tube toner agitator is modified to incorporate structure or grooves on the outer peripheral surface. Further, by placing a shrouded toner dispense auger inside the holey tube, the development system architecture stays compact and improved toner powder pushing through the pre-load of toner on the donor roller results, thereby insuring delivery of fresh toner evenly across the length of the developer housing. With more efficient pre-load, agitator rotational speed and bias can be reduced, leading to less toner effluents emanating from the developer housing without adversely affecting the cycle to cycle donor roller toner reload.
In U.S. Pat. No. 5,572,299, to Kato et al., issued Nov. 5, 1996, there is disclosed a developing device which has a vessel for holding a two-component developer composed of a toner component and a magnetic component. A magnetic roller is rotatably provided within the vessel to bring the developer to a developing zone for a development of an electrostatic latent image. An agitator also is provided within the vessel for agitating and circulating the developer to cause a triboelectrification between the toner component and the magnetic component and a uniform distribution of the toner component in the magnetic component. The agitator is arranged to present a uniform density mass of the developer to the magnetic roller for ensuring an even development of the latent image.
In the aforementioned commonly owned application U.S. Pat. No. 5,784,671, issued Mar. 30, 1999, to Damji et al., there is disclosed an electrostatographic process cartridge detachably mountable into a cavity defined by mated modules forming parts of an electrostatographic reproduction machine. The cartridge includes an elongate housing having walls defining a front end of the process cartridge, a rear end thereof, and a process chamber; a rotatable endless photoreceptive member having a closed loop path with the process chamber, and an image bearing surface for holding a formed toner image, and being mounted with the process chamber and towards the rear end for contacting a toner image receiving sheet moving along a machine sheet path for toner image transfer.
The disclosures of the aforementioned patents are incorporated herein by reference in their entirety.
SUMMARY OF THE INVENTION
Embodiments of the present invention, include:
An article comprising:
a rigid member, such as a rod or tube, with a first end and a second end where the ends are adapted to engage a developer housing and a drive train for continuously rotating the rod; and
a resilient flexible sheet attached to the rigid rod; and
An apparatus comprising:
a housing adapted for the conveyance of particulate developer materials from a sump to an imaging member;
a conveyor within the housing adapted for advancing the developer materials from the sump to a donor roll;
a donor roll situated at least partially within the housing adapted for advancing a charged and metered layer of the developer material on the donor roll from the donor roll to the imaging member;
a charge metering blade which flexibly contacts the surface of the donor roll and which blade is adapted to charge and meter a thin layer of developer material onto the donor roll; and
an agitator article including, for example, a rigid rod with a resilient flexible sheet appended thereto and situated within the housing and adapted for further advancing developer materials from the auger to the donor roll and charge metering members; and
An imaging process comprising:
developing a latent image on a photoconductive surface with a toner material with the foregoing development apparatus;
transferring the resulting developed image from the photoconductive surface to an image receiver; and
fixing the resulting transferred image to the image receiver.
These and other aspects are achieved, in embodiments, of the present invention as described and illustrated herein.
REFERENCES:
patent: 4926217 (1990-05-01), Bares
patent: 4947211 (1990-08-01), Ono et al.
patent: 5075728 (1991-12-01), Kobayashi et al.
patent: 5124752 (1992-06-01), Kanno et al.
patent: 5305064 (1994-04-01), Trott et al.
patent: 5572299 (1996-11-01), Kato et al.
patent: 5784671 (1998-07-01), Damki et al.
patent: 5797075 (1998-08-01), Saito et al.
Haack John L.
Royer William J.
Xerox Corporation
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