Electrophotography – Cleaning of imaging surface – Blade
Reexamination Certificate
2002-07-22
2004-11-02
Lee, Susan (Department: 2852)
Electrophotography
Cleaning of imaging surface
Blade
C399S123000
Reexamination Certificate
active
06813466
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to removing toner and other residue from the photosensitive drum in an electrophotographic apparatus by means of a cleaning blade consisting of a rigid holder coupled with an elastic wiper. The edge of the elastic wiper is caused to bear against the surface of the photosensitive drum, thus wiping toner and other residue off the drum as it rotates.
Two popular types of cleaning blades are distinguished by the method of forming and attaching an elastic wiper, usually polyurethane, to a rigid holder typically made of stamped steel sheet or extruded aluminum. The first type of cleaning blade is molded whereby liquid polyurethane is introduced into a mold with the rigid holder affixed therein. The assembly is oven cured to obtain the desired physical characteristics of the urethane, which is then precision trimmed to form the surface to be placed in contact with the rotating drum. The second type of cleaning blade is fabricated by attaching a polyurethane strip cut from a preformed sheet to the rigid holder using an adhesive, preferably double-sided adhesive tape.
In the family of electrophotographic apparatus, which includes copy machinery and laser printers, the diversity of geometries have spawned the development of approximately four hundred and fifty different cleaning blade configurations. The design of these systems has typically not considered the use of standardized cleaning blade configurations in different applications, leading to this proliferation of cleaning blade configurations.
In the prior art, the cleaning blades are specifically designed for a particular application without regard to using a standardized cleaning blade configuration interchangeably in different electrophotographic machines. Currently, there are no means available to locate and secure a standard configuration cleaning blade to preserve its geometric relationship with the photosensitive drum for different machines, nor to allow for interchangeability of a standard cleaning blade in different machines.
In the prior art, the cleaning blade is attached directly to a mounting area integral to the particular electrophotographic apparatus, normally using screws to secure the cleaning blade in position. Note that hereafter in this specification this mounting area described will be referred to as a “primary mounting” or alternatively as a “cleaning blade mount.” The primary mounting often has ears, tabs, or other locating provisions, which cooperate with notches on one or both ends of a blade holder to locate the cleaning blade with respect to the photosensitive drum. Thus, for each apparatus, a uniform pressure, contact area, and contact angle of the wiper is maintained relative to the photosensitive drum.
Examples of prior art cleaning blades are shown in
FIGS. 1 and 2
of the accompanying drawings. The cleaning blades (collectively
1
A and
2
A or
1
B and
2
B) are attached directly to a primary mounting
4
, the geometry of which is dependant upon the particular machine design, to maintain a desired pressure, contact area, and geometric relationship, primarily parallelism, of the elastic wiper to the photosensitive drum being cleaned.
FIG. 1
illustrates an example of a cleaning blade with an elastic wiper blade
2
A molded onto a holder
1
A, the blade having a flat surface abutting the surface of the photosensitive drum
3
to be cleaned and a sloped (or tapered) surface on the side opposite from the flat surface.
FIG. 2
illustrates an example of a cleaning blade with an elastic wiper blade
2
B of rectangular cross-section adhesively affixed to a holder
1
B.
The cleaning blades shown in
FIGS. 1 and 2
are mounted so the edge of the elastic wiper bears against the photosensitive drum in opposed relationship with the movement thereof (i.e. in the direction of the arrow) to remove toner and other residue. It should be noted that the cleaning blades of
FIGS. 1 and 2
are not reversible and cannot be selectively mounted so that either opposite edges of the wiper blades clean the drum.
A disadvantage of the prior art is that the configurations of the various cleaning blades are very specific because they are designed only to mate with corresponding cleaning blade mounts without any regard for standardization or interchangeability. In other words, the prior art does not disclose or even suggest using a common cleaning blade configuration for different or multiple applications since the prior art does not teach or suggest any uniform means for locating and stabilizing the cleaning blade to preserve its geometric relationship to the photosensitive drum for differing cleaning blade mount configurations.
Moreover, the design and manufacture of prior art cleaning blades prevents their wiper blades from being reused in the event of a worn or defective wiper blade. The molded wiper blades cannot be removed without damaging them, thus preventing their replacement on a holder, and the adhesive on the adhesively attached wiper blades prohibits their removal and re-use on the rigid holder.
Furthermore, the configuration of the elastic wipers used in prior art are such that the thickness of the elastic wiper at the edge placed in contact with the photosensitive drum is less than or equal to the thickness of the elastic wiper at all points in the direction of the rigid holder. As the edge of the elastic wiper wears down, the contact pressure against the photosensitive drum diminishes, rendering the cleaning blade prematurely ineffective.
This invention overcomes the above-discussed problems and provides a universally usable cleaning blade which is preferably reversible for twice the useful life, and preferably has additional features which make it longer lasting. These advantages and attributes of this invention and others will be readily understood upon a reading of the text hereinafter.
SUMMARY OF THE INVENTION
It is an object of this invention to provide a cleaning blade system for electrophotography.
It is another object of this invention to provide a standardized and interchangeable cleaning blade configuration for the system.
It is another object of this invention to provide the system for use on new or existing electrophotography machines.
It is another object of this invention to provide an mounting adapter for the system which is capable of holding a cleaning blade in a plurality of positions enabling its use on a variety of electrophotographic machines.
It is another object of this invention to provide a reversible cleaning blade, whether symmetrical or non-symmetrical, so either edge of the wiper blade may be selectively used for cleaning the photosensitive drum used in electrophotographic apparatus, thus extending the useful life of the cleaning blade.
It is another object of this invention to provide a cleaning blade system cooperating with secondary mounting components, adapters, or shims to allow a particular cleaning blade configuration to be used in a variety of applications, including new or existing machines, thus providing a high degree of interchangeability.
It is another object of this invention to provide a cleaning blade system having mounting adapters with uniform means for holding a common or standardized cleaning blade, while also having multiple means for attaching such mounting adapters to different configurations of cleaning blade mount inherent in specific machine designs.
It is another object of this invention to provide a cleaning blade system using mounting adapters to provide a means to locate and stabilize the position of a specific cleaning blade configuration in a variety of applications, thus maintaining the desired pressure, contact area, and geometric relationship, especially parallelism, of the wiper blade to the photosensitive drum for different cleaning blade mount configurations.
It is another object of this invention to provide a cleaning blade system wherein the cleaning blade and the mounting adapter are configured in such a manner as to cooperate with one another to effectively register and adjust the position
Lee Susan
Tarr, Esq. Howard C.
Tighe, Esq. Thomas J.
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