Electrophotography – Machine operation – Electrical connection
Reexamination Certificate
2000-02-17
2001-06-19
Moses, Richard (Department: 2852)
Electrophotography
Machine operation
Electrical connection
C399S286000, C399S119000, C492S015000, C492S042000
Reexamination Certificate
active
06249659
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a toner cartridge for an electrophotographic printer or copier, and more particularly, to a toner cartridge with a plastic drive hub having a conductive interconnection for a developer roller mounted in the cartridge.
BACKGROUND OF THE INVENTION
An electrophotographic printing device such as a printer or copier prints an image on media such as sheets of paper or labels from toner contained in a toner cartridge. A developer roller or sleeve is mounted within the toner cartridge in proximity to a photoconductive drum. The photoconductive drum is charged, and a laser scans the charged photoconductive drum with a laser beam to discharge the surface and form a latent image thereon. The developer roller magnetically attracts statically charged toner from the toner container. An AC bias voltage is applied to the developer roller to insure uniform distribution of the toner, while a DC bias voltage is applied to establish print density. Toner is transferred from the developer roller to the photoconductive drum to develop the latent image formed on the photoconductive drum. The developed image is then transferred to statically charged media, such as paper. Heat then fixes the visible image on the media.
A pair of hubs positioned at the ends of the developer roller rotatably mount the roller within the toner cartridge. At least one of the hubs is electrically conductive, and provides an electrical connection for the bias voltage applied to the developer roller.
The hubs are usually made of aluminum metal. The aluminum in the hubs provides an electrical connection for the bias voltage and a rigid support for the rotating developer roller. The aluminum hubs are assembled into the toner cartridge by press fitting into the ends of the developer roller.
However, the use of aluminum hubs in a toner cartridge has significant disadvantages. The press fitting of the hubs into the ends of the developer roller requires accuracy, and is difficult to perform without deforming the developer sleeve. The hubs are then not concentrically mounted with the developer roller, resulting in uneven development during the image transfer process, and consequently, low quality images. Aluminum is not a durable bearing material, and wear shortens the life of the toner cartridge. Aluminum hubs are also expensive, thus increasing the cost of a toner cartridge.
SUMMARY OF THE INVENTION
A toner cartridge in accord with the present invention overcomes the foregoing problems by using hubs made of an inexpensive nonconductive durable plastic material. One of the hubs is made conductive by having a wire disposed in an axially aligned passage to provide an electrical connection for the developer roller. The toner cartridge includes an electrophotographic drum, a toner container, a fixed electrode for receiving a developing bias voltage, and a developer roller. The hubs are press fit into the ends of the developer roller. The conductive hub has a unitary nonconducting plastic body, with a plug portion for elastically and slidably press-contacting the end of the developer roller, an elongated axle portion with an uninterrupted outer bearing surface, a shoulder portion for supporting a coil spring, and a longitudinal passage running through the axle and shoulder portions. The wire is disposed in the passage and makes an electrical connection between the coil spring and the developer roller.
An object of this invention is to provide a toner cartridge for a printer or copier that is long lasting.
Another object of this invention is to provide a toner cartridge for a printer or copier that is inexpensive to manufacture.
An even further object of this invention is to provide a toner cartridge for a printer or copier that produces high quality images.
A further object of this invention is to provide a toner cartridge for a printer or copier that is easy to assemble.
A still further object of this invention is to provide a toner cartridge for a printer or copier that has enhanced bearing life.
Other objects of this invention will be readily perceived from the following description, claims, and drawings.
REFERENCES:
patent: 5283619 (1994-02-01), Nomura et al.
patent: 5305062 (1994-04-01), Sato et al.
patent: 5634175 (1997-05-01), Michlin et al.
patent: 5648838 (1997-07-01), Michlin et al.
patent: 5768658 (1998-06-01), Watanabe et al.
patent: 5815782 (1998-09-01), Yokomori et al.
patent: 6064841 (2000-05-01), Matsuzaki
Brady John A.
Lexmark International Inc.
Moses Richard
LandOfFree
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