Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
PE~ESSURE ROLL CLEANER 212 5 ~ 8 ~
BACKGROUND OF THE INVENTION
Field of the Invention
This invention relates generally to fusers used in the electrophotographic process,
and more particularly to a pressure roll cleaner for removing residue from the
surface of a pressure roll.
Description of the Related Art
The basic xerographic process comprises exposing a charged photoconductive
member to a light image of an original document. The irradiated areas of the
photoconductive surface are discharged to record an electrostatic latent image
corresponding to the original document. A development system moves a developer
mix of carrier granules and toner particles into contact with the photoconductorsurface. The toner particles are attracted electrostatically from the carrier granules
to the latent image forming a toner powder image thereon. The toner powder
image is then transferred to a sheet of paper or other support material. This sheet of
paper advances to a fuser which permanently affixes the toner powder image to the
paper.
The fuser generally comprises a fuser roll, a pressure roll, and an oiling system. The
fuser and pressure rolls each have circumferential surfaces in contact with eachother. Toner powder is affixed to the paper as the paper passes through a nip
between the fuser roll and the pressure roll. The oiling system applies oil to the
surface of the fuser roll for lubrication. As the fuser roll contacts the pressure roll, a
portion of the oil on the surface of the fuser roll is transferred to the surface of the
pressure roll. Similarly, the fuser roll surface will contain other contaminants such as
residual toner powder and paper fibers which are also transferred to the surface of
the pressure roll. The oil and other contaminants must be removed from the surface
of the pressure roll to prevent this residue from being transferred to the paper as it
passes through the nip between the fuser roll and pressure roll. If not, this residue
will form a copy quality defect on the paper. As a result, it is desirable to provide an
apparatus for removing the residue from the circumferential surface of the pressure
roll.
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in an attempt to clean the circumferential surface of the pressure roll, a pressure roll
cleaner 100, as shown in FIG. 6, was added to the fuser assembly. The conventional
pressure roll cleaner 100 consisted of a sheet 11 of absorbent material having a front
surface 101 in contact with the surface of the pressure roll. The edges 102 of the
absorbent sheet 11 were folded over and stitched to a back surface 103. The pockets
between the folded-over edges 102 and seams 104 formed by the stitches received
support rods 20, 21 which held the pressure roll cleaner 100 in contact with thepressure roll. An area on the front surface 101 between the two seams 104 of thepressure roll cleaner 100 formed a cleaning surface which collected residue while the
pressure roll rotated.
One of the main problems with the conventional pressure roll cleaner 100 was itsshort user life Once the front surface 101 became saturated with residual oil and
other contaminants, the conventional pressure roll cleaner 100 was discarded andreplaced with a new one. The back surface 103 could not be used as a cleaning
surface since the folded-over edges 102 formed an irregular surface unsuitable for
cleaning. Furthermore, the location of the two seams 104 limited the cleaning area
on the front surface 101. The two seams 104 increased the stiffness of the absorbent
sheet at these locations, which resulted in inefficient contact with the pressure roll.
As a result, the absorbent sheet 1 1 could not collect residue at areas near the seams
104.
Due to these drawbacks, the conventional pressure roll cleaner had to be replaced
frequently (approximately 6-9 times per 1 million prints). The costs associated with
the frequent maintenance for replacing the used pressure roll cleaners and the costs
associated with stockpiling sufficient numbers of replacement pressure roll cleaners
made the design of the conventional pressure roll cleaner undesirable.
The asymmetrical design of the conventional pressure roll cleaner was also
disadvantageous if installed improperly. For example, if a user inadvertently
installed the conventional pressure roll cleanerwith the back surface 103 facing the
circumferential surface of the pressure roll, ineffective cleaning would occur and
further maintenance would be necessary to reinstall the pressure roll cleaner
properly.
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SUMMARY OF THE INVENTION
Accordingly, it is an object of an aspect of the present invention to provide a
pressure roll cleaner which has a longer user life.
It is an object of an aspect of the invention to provide a pressure roll cleanerwhich has a larger effective cleaning surface.
It is an object of an aspect of the invention to provide a pressure roll cleanerwhich is easy to install and replace while eliminating the likelihood of installation
error.
Additional objects and advantages of the invention will be set forth in the
description which follows and in part will become obvious from the description,
or may be learned by practice of the invention. The objects and advantages of
the invention may be realized and attained by means of the instrumentalities andcombinations, particularly pointed out in the appended claims.
To achieve the objects in accordance with the purpose of the invention, as
embodied and broadly described herein, there is provided apparatus for cleaning
a pressure roll, comprising an absorbent sheet having longitudinal ends joined at
a first seam and having a generally folded edge along a central longitudinal axis
of the absorbent sheet, and means for supporting the absorbent sheet against
the rotatable cylindrical member.
In another embodiment of the invention, there is provided apparatus for cleaningthe pressure roll, comprising a seamless tube of absorbent felt and means for
supporting the tube against the pressure roll.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an illustration of the paper path of a typical electrophotographic
apparatus in which the present invention is used.
FIG. 2 is a side view of the fuser and pressure roll containing pressure roll
cleaner of the present invention.
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FIGS.3(a)-(c) are side views of several embodiments of the pressure roll cleaner of
the present invention.
FIG. 4 is a front exploded view of the components of the fuser, including the pressure
roll cleaner.
FIG. 5 is a front view of an embodiment of the pressure roll cleaner, including
apparatus for indexing the pressure roll cleaner.
FIG. 6 is a side view of a conventional pressure roll cleaner.
DETAILED DESCRIPTION OFTHE PREFERRED EMBODIMENTS
FIG.1 shows the paper path for a typical electrophotographic apparatus. A sheet of
paper exits one of the paper holding trays 30 and is transported to the
photoreceptor 40 by a paper transport system 32. Toner particles are attracted
electrostatically to a latent image formed on the photoreceptor 40. The
photoreceptor 40 then transfers the toner powder image to the sheet of paper. The
sheet of paper carrying the toner powder image isthen transported to a fuser 50
and the toner powder image is permanently affixed to the paper as it passes through
the nip between the fuser 50 and the pressure roll 55. The sheet of paper is then
transported to an output tray 60.
FIG.2 showsthe components of a fuser assembly, including the pressure roll cleaner
of the present invention. The fuser assembly generally comprises a fuser roll 50, a
pressure roll 55, an oiling system 52 for applying oil to the fuser roll, a diaphragm 53,
spring 54, and a loading arm 57 coupling the pressure roll 55 to the diaphragm 53
and spring 54. The pressure roll cleaner 10 is supported against a surface of the
pressure roll at a location which does not interfere with the passing of a sheet of
paper through the nip between the fuser roll 50 and the pressure roll 55.
The fuser assembly shown in FIG. 2 is used in electrophotographic apparatus such as
the Model Nos.1075 and 1090 copiers and Model Nos. 4050, 4650, 4090, and 4850
laser printers, all manufactured by Xerox Corporation. However, the pressure roll
cleaner of the present invention may be used in any similar fuser assembly or any
apparatus where the cleaning of a rotating member is desired.
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.
The fuser assembly operates in the following manner. The diaphragm 53 receives air
from a compressor (not shown) and expands. As the diaphragm 53 expands, the
spring 54 raises one end of the loading arm 57 to rotate the loading arm 57 around a
pivot point 58. The rotation of the loading arm 57 forces the pressure roll 55 against
the fuser roll 50 with sufficient force to permanently affix the toner powder image
to the sheet of paper as it passes through the nip. The pressure roll 55 rotates in a
clockwise direction and the fuser roll 50 rotates in a counterclockwise direction to
pull the paperthrough the nip.
An oiling system 52 applies oil to the surface of the fuser roll 50. A major portion of
the oil is transferred to the sheet of paper as it passes through the nip while the
remaining portion of the oil is transferred to the pressure roll 55 in contact with the
fuser roll 50. Additionally, other contaminants, such as residual toner, are
transferred to the pressure roll 55 as they collect on the fuser roll 50.
The pressure roll cleaner 10, as shown in FIGS.3 and 4, includes a sheet 11 of
absorbent material supported against the circumferential surface of the pressure roll
55 to absorb the oil and other contaminants collected on the radial surface of the
pressure roll.
As shown in FIG.3(a), the absorbent sheet 11 is folded in half longitudinally and the
unfolded ends 12 of the absorbent sheet 11 are joined together at two locations
with longitudinal stitches. A pocket isformed between two seams 14,14' for
receiving a support rod 20. The sides 18,19 of the absorbent sheet 11 between the
folded edge 15 and the lower seam 14' define a cleaning area which contacts the
pressure roll.
As shown in FIG. 4, the pressure roll cleaner 10 is supported against the surface of the
pressure roll 55 by two support rods 20,21. The top support rod 20, which is inserted
through the pocket formed between the two stitches 14,14' of the absorbent sheet11, is attached to a bracket 70 supporting the pressure roll 55. The bottom support
rod 21 rests againstthe inner folded edge 15 of the absorbent sheet 11. The lower
support rod 21 is attached to the bracket 70 with a spring 59 which urgesthe lower
support rod 21 holding the absorbent sheet 11 in contact with the surface of the
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pressure roll 55. The pressure roll cleaner 10 extends along the entire length of the
pressure roll 55.
While two support rods 20,21 are used to support the absorbent sheet 11 against
the pressure roll 55, other means can be used for supporting the absorbent sheetwhile providing the necessary longitudinal support for holding the absorbent sheet
in contact with the pressure roli.
The absorbent sheet 11 may be composed of any absorbent material, such as an
absorbent polyester or, preferably, an aramid felt. One type of aramid felt which
may be used is NOMEX, manufactured by Dupont. Additionally, when the fuser
assembly is used in apparatus which generates high temperatures during operation,
such asthe Model Nos.1075 and 1090 copiers and Model Nos.4050,4650,4090, and
4850 laser printers manufactured by Xerox Corporation, the absorbent sheet must
also be heat resistant. An aramid felt such as NOMEX is suitable for high
temperature uses.
In the preferred embodiment, a nonabsorbent barrier layer 17, shown in FIG.3(a), is
attached to an inner surface of either side of the absorbent sheet. The
nonabsorbent layer 17 preventsthe accumulated oil and toner from penetrating
th rough one side 18 of the absorbent sheet 11 and being absorbed by the second
side 19 of the absorbent sheet 11. The nonabsorbent layer 17 may include a
polytetrafluoroethylene (teflon) material or any nonabsorbent polyester material.
The nonabsorbent layer 17 must also be heat resistant if used in high temperature
environments.
The symmetrical design of the pressure roll cleaner 10 allows both sides of the
absorbent sheet 11 to be used. When one side 18 of the absorbent sheet has been
saturated with residual toner, oil, and other contaminants, the absorbent sheet 11
can be removed from the support rods 20,21, reversed, and reinserted. The secondside 19 can then be used to clean the pressure roll. As a result, the usage life of the
pressure roll cleaner of the present invention is twice as long as that of the
conventional pressure roll cleaner 100 since the second side of the conventionalpressure roll cleaner cannot be effectively used as a cleaning surface.
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FIG.3(b) shows a second embodiment of the pressure roll cleaner. The absorbent
sheet 11 is formed into a seamless web which is supported by the support rods 20,21.
The manner of supporting the absorbent sheet 11 againstthe pressure roll 55 is the
same asthatdisclosed in FIG.4.
FIG.3(c) shows a third embodiment of the pressure roll cleaner. In this embodiment,
the absorbent sheet 11 is folded and the unfolded edges 12 are stitched together to
form a seam 14 which is located above the top support rod 20. Unlike the
embodiment of FIG.3(a), this embodiment has only one seam.
In the second and third embodiments shown in FIGS.3(b) and (c), the absorbent
sheet 11 can be manually or automatically indexed to rotate about the support rods
20,21. As a result, the entire surface of the absorbent sheet 11 can be used to
further increase the usage life of the pressure roll cleaner. As shown in FIG. 5, in
order to incrementally rotate the absorbent sheet 11, one of the support rods 21 '
may be knurled to frictionally grip the absorbent sheet 11. An end of the knurled
rod 21' engagesa rachet mechanism 25. The knurled support rod 21' and absorbent
sheet 11 are rotated by indexing the rachet 25. Any conventional rachet mechanism
may be used to accomplish the indexing. Similarly, other indexing apparatus can
also be used.
In order to use these two embodiments, means must be included to preventthe
absorbent sheet 11 from freely rotating about the support rods as the pressure roll
55 rotates. For example, the rachet 25 or other device for indexing the absorbent
sheet 11, in conjunction with the knurled rod 21 ', can also serve as a means for
preventing free rotation of the absorbent sheet 11 about the support rods.
It will be apparent to those skilled in the art that various modifications and
variations can be made in the present invention without departing from the spirit or
scope of the present invention. Thus, it is intended that the present invention cover
the modifications and variations of this invention, provided that they come within
the scope of the claims.
