Note: Descriptions are shown in the official language in which they were submitted.
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A FUSER WICK
This invention relates generally to a fusing system used in an
electrophotographic printing machine, and more particularly concerrLs a fluid
5 applicating wick for applying release materi~l to the surface of a fuser
member used for permanently affixing toner to a copy sheet.
A typical electrophotographic printing machine employs a
photoconductive member that is charged to a substantially uniform potential
so as to sensitize the surface thereof. The charged portion of the
10 photoconductive member is exposed to a light image of an ori~nal document
being reproduced. Expo6ure of the charged photoconductive member
selectively dissappates the charge thereon, in the irradiated areas. This
records ~n electrostatic latent image on the photoconductive membe~
corresponding to the informationsl at areas contained within the original
15 document. After the electrostatic latent image is recorded on the
photoconductive member, the latent image is developed by bringing a
developer material into contact therewith. Generally, the developer material
comprised toner particles adhering triboelectrically to carrier granuals. The
toner particles are attracted from the carrier granuals to the latent image
20 forms a toner powder image on the photoconductive member. Toner powder
image is then transferred from the photoconductive member to a copy sheet.
Thereafter, the toner particles are heated to permanently fuse the powder
image to the copy sheet.
In order to fuse the toner partides to the copy sheet by heat, it is
25 necess~ry to elevate the temperature of the toner material to a point at which
the constituents thereof coalesce and become tacky. This action causes the
toner partides to flow, to some extent, into the fibers or pores of the copy
sheet. Thereafter, as the toner material cools, solidification of the toner
material occurs causing the toner material to be firmly bonded to the copy
30 sheet.
Herebefore, the toner particles have been permanently fused to the
copy sheet by the simulanteous application of heat and pressure by a pair of
rollers. The rollers are in pressure contact with one another with one of the
rollers being heated. Fusing of the toner particles takes place when the proper
35 combination of heat and contact pressure are provided. During the operation
of the fusing system, the copy sheet with the toner powder image thereon,
adv~es ~ra~ ~e rnp dehrEd l~y the ~ated fi~ ro11 a~l ~L~p ro11.
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Occasionally, toner particles will be offset from the copy sheet to the fuser
roll. These toner particles are then subsequently transferred to the surface of
the backup roll which is in pressure contact with the fuser roll, during periodsof time when no copy sheet passes through the nip. When subsequent copies
5 are advanced through the nip, these residual toner particles adhering to the
backup roll and fuser roll may be deposited on the copy sheet degradations the
copy thereof. One approach for minimizing this problem has been to provide
an outer layer on the fuser roll made frorn polytetrafluorethylene, best known by
the tradename Teflon which is a trademark of E. 1. du Pont de Nemours and
la Company of Wilmington, Delaware. Various fluid polymer release materials
which oxidize or which contain functional groups, can be utilized to prevent
offsetting of the toner particles to the fuser roll. In system of this type, a
release fluid is applied to the fuser roll by means of a wick. The wick is
generally used to dispense silicone oil, functional siloxane fluids, mineral oil,
15 and many other release fluids upon the external surface of the fuser member.
By way of example, the fuser wick may be a pad overlying and in contact with
the heated fuser roll. Generally, the wick is made from two different layers,
one layer comes in contact with the surface of the fuser roller, metering
precise amounts of fluid thereon. The upper layer, in contact with the first
20 layer, has high release fluid retention capabilities for supplying the first layer
with fluid. Various types of wicks have been devised to meter the release fluid
onto the surface of the fuser roller. The following disclosures appear to be
relevant:
25U.S. Patent Number 3,745,972
Patentee: Thettu
Issued: July 17, 1973
U.S. Patent Number 4,083,322
Patentee: Beckman, Jr.
Issued: April 11, 1978
U.S. Patent Number 4, 309,957
Patentee: Swift
Issued: ~anuary 12, 1982
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U.S. Patent Number 4,336,766
Patentee: Maher, et al
Issued June 29, 1982
The pertained portions of the foregoing disclosures may be briefly
summarized as follows:
Thettu describes a fusing system including a heated fuser roller and
a backup pressure roller. An applicator roller conveys a thin film of silicone
oil from a pan to a wick. The wick includes a Teflon layer contacting the
10 heated fuser roll and a Nomex layer contactin~ the applicator roU. ~ ~~ i` '
Beckman, Jr. discloses a fusing system including a heated fuser
roUer and a backup roller. A wick assembly comprises a Nomex layer, a wool
layer, and a porous wiper pad. The wiper pad contacts the fuser roll with the
Nomex roUer engaging both the wiper pad and an applicator roll. The
15 applicator roU rotates in an oil reservoir. The wool layer contacts the surface
of the Nomex layer opposed to the wiper pad. Both the Nomex layer and wool
layer meter oil to the wiper pad which passes oil to the fuser roll.
Swift describes a wick for applying release fluids to a fuser roller.
The wick includes a layer of fiberous Teflon needled into a layer of Nomex.
20 The Teflon layer contacts the surface of the fuser roller with the Nomex layer
engaging an applicator roll disposed in an oil reservoir.
Maher disclosed a two ply wick. One layer of the wick is relatively
thick with the other layer being relatively thin. The thick layer feeds oil to
the thin layer contacting the fuser roll . Both layers are made from Nomea~.
In accordance with one aspect of the features of the present
invention, there is provided a fluid applicating wick having a fluid retaining
material and a covering material. The covering material is disposed in contact
with at least one surface of the fluid retaining material and comprises at leasta first layer of fibers and a second layer of fibers. A thin loosely woven layer30 of material is interposed between the first layer of fibers and the second layer
of fibers with at least a portion of the fibers of the first layer and second
layer being interlocked with the layer of loosely woven material interposed
therebetween.
Pursuant to another aspect of the features of the present
35 invention, there is provided an apparatus for substantiaUy permanently fusinga toner image to a sheet. A backup roll is operatively associated with a fuser
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roll to define a nip through which the sheet with the unfused toner powder
image thereon passes to fuse the toner image to the sheet. A wick meters oil
onto the fuser roll from the oil reservoir. The wick has an oil retaining
material in communication with an oil reservoir. The covering material has
one surface thereof contacting at least one surface of the oil retaining
material with the other surface thereof contacting the fuser roll to meter oil
thereon. The covering material has at least a first layer of fibers and a secondlayer of fibers with a thin loosely woven layer of material interposed
therebetween. At least a portion of the fibers of the first layer and the
10 second layer are interlocked with the layer of loosely wovern material
interposed therebetween.
Other aspects of the present invention will become apparent as the
following description proceeds and upon reference to the drawings, in which:
Figure 1 is a schematic, elevational view depicting a fusing
15 apparatus incorporating the features of the present invention therein;
Figure 2 is an enlarged, fragmentary, sectional elevational view
showing the fluid applieating wick used in the Figure 1 fusing system; and
Figure 3 is an e~arged, fragmentary, sectional elevational view
illustrating the cover of the Figure 2 applicating wick.
While the present invention will hearafter be described in
connection with a preferred embodiment thereof, it will be understood that it
is not intended to limit the invention to that embodiment. On the contrary, it
is intended to cover all alternatives, modifications, and equivalents as may be
included within the spirit and scope of the invention as defined by the
25 appended claims.
Inasmuch as the art of electrophotographic printing is well known,
the various processing stations employed in the printing machine and their
operation will be described briefly hereinafter.
An exemplary electrophotographic printing machine includes a belt
30 have a photoconductive surface deposited on a conductive substrate. The belt
advances successive portions of the photoconductive surface to various
processing stations disposed about the path of movement thereof. Initially, a
portion of the belt passes through a charging station. At the charging station,
a corona generating device charges the photoconductive surface of the belt to
35 a relatively high, substantially uniform potential. Thereafter, the charged
portion of the photoconductive surface is advanced through the imaging
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station. At the imaging station, an original document is positioned on a
transparent piaten. Lamps flash light rays onto the original document. The
light rays reflected from the original document are transmitted through a lens
forming a light image thereof. The lens focuses the light image onto the
5 charged portion of the photoconductive surface to selectively dissipate the
charge thereonO This records an electrostatic latent image on the
photoconductive surface which corresponds to the informational areas
contained within the original document disposed upon the platen. Thereafter,
the belt advances the electrostatic latent image recorded on the
10 photoconductive surface to a development station. At the development
station, a magnetic brush development system transports the developer
mixture of carrier granuals and toner particles into contact with the
electrostatic image recorded on the photoconductive surface. The toner
particles are attracted from the carrier granuals to the electrostatic latent
15 image forming a toner powder image on the photconductive surface of the
belt. After development, the toner powder image is advanced to a transfer
station. At the transfer station, a copy sheet is moved into contact with the
toner powder image. A corona generating device sprays ions onto the backside
of the copy sheet to attract the toner powder image thereto. After transfer,
20 the copy sheet advances to the fusing station. At the fusing station, the copy
sheet passes between a heater fuser foll and a backup roll with the toner
powder image contacting the heated fuser roll. In this manner, the toner
powder image is permanently fused to a copy sheet. The detailed structure of
the fusing apparatus employed in the fusing station will be described
25 hereinafter with reference to Figures 1 through 3, inclusive. After exiting the
fusing station, the copy sheet advances to a catch tray where the operator
removes the completed copy therefrom.
For a general understanding of the features of the present
invention, reference is made to Figures 1 through 3, incluslve, of the drawings.30 In the drawings like reference numerals have been used throughout to
designate identical elements. Figure 1 schematically depicts the fusing
apparatus of the present invention. It will become evident from the following
discussion that this fusing apparatus is equally well suited for use in a wide
variety of printing machines, and is not necessarily limited in its application to
35 the particular embodiment depicted.
Referring now to Figure 1 of the drawings, the fusing apparatus
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includes a heated fuser roll, indicated generally by the reference numeral 10,
and a backup roller, indicated generally by the reference numeral 12. A
temperature sensor 14 contacts the exterior circumstantial surface of fuser
roller 10. Preferably, temperature sensor 14 is a thermistor wherein the
5 resistance thereof varies as a function of the detected temperature. The
output signal from temperature sensor 14 is a voltage. Fuser roller 10 is
composed of a hollow tube 16 having a thin covering 18 thereon. A heat
source 20 is disposed interiorly of tube 16. Tube 16 is made from a metal
material having the desired heat conductivity characteristics. By way of
10 example, aluminum, copper and other metals having a high thermal
conductivity are suitable for use as a tube. Preferably, covering layer 18 is
made from silicone rubber. Heating element 20 is preferably a halogen lamp.
Lamp 20 is connected to sensor 14 through a controller. Backup roller 12 has a
relatively thicl< layer of silicone rubber 22 on metal tube 24. Backup roller 1215 is mounted rotatably on bracket 26. Bracket 26 is actuated by a controller to- pivot so as to press backup roller 12 into contact with fuser roller 10 to define
a nip therebetween through which the copy sheet passes. Switch 28 detects
the presence or absence of the copy sheet in the fusing apparatus and indicates
the status thereof to the controller. Rollers 10 and 12 remain spaced from
20 each other whenever fusing is not occurring. When fusing is occurring,
roller 12 pivots so as to press against fuser roller 10. Backup roller 12 and
fuser roller 10 are adapted to rotate during the fusing operation so as to
advance the copy sheet therethrough. Heat source 20, which may be a halogen
lamp, or infared lamp, amongst others, is located internally of fuser roller 10.25 A lubricating assembly, indicated generally by the reference numeral 32,
applies a thin film of silicone oil to silicone layer 18 of fuser roll 10 to prevent
offsetting of toner particles thereto. Lubricating assembly 32 includes a fluid
applicating wick, indicated generally by the reference numeral 34, having a
portion thereof in oil reservoir 36 for receiving silicone oil therefrom. Fluid
30 applicating wick 34 includes a covered material 46 contacting a fluid retaining
material 48. The covering material has one surface thereof engaging fuser
roll 10 and is adapted to meter silicone oil thereon. Preferably, the covering
material of the fluid applicating wick has low friction and good wear
properties with little tendency to accumulate molton toner, as well as thermal
35 stability at elevated temperatures. Frame 44 holds both fluid retaining
material 48 and covering material 46 of fluid applicating wick 34 in their
operative positions. Inasmuch as covering material 46 is exposed to dirt,
accumulation, and wear, it is designed to be a replaceable component. It has
been found that a limiting factor in the life of the covering material is ~he
degredation and wear that occurs from contact with the rotating fuser roll.
As the covering material wears, fibers are pulled from the surface thereof
accumulating on the backup roller and downstream copy sheets. Ultimately,
this wear of the covering material can result in an accumulation of a fluff of
material extending from the surface thereof and sometimes protruding into
the entrance path of the copy sheet. To extend the life of the covering
10 material, it is necessary to eliminate these wear problems.
Turning now to figure 2, there is shown an enlarged, fragmentary,
sectional elevational view of fluid applicating wick 34. Fluid applicating
wick 34 has covering material 46 contacting fluid retaining material 48.
Covering material 46 is a composite material and will be described
15 hereinafter, in greater detail, with reference to Figure 3. By way of example,
fluid retaining material 48 may be made from polyester, Teflon, and and
Nomex. Teflon and Nomex are trademarks of E. I. du Pont de Nemours and
Company of Wilmington, Delaware. Nomex is an aramid, i.e. a highly
aromatic polyamide fiber, such as a copolymer of meta-phenylenediamine and
20 isophaloyd chloride. One skilled in the art will appreciate that any other
suitable material may be employed which retains oil therein in the desired
amount.
Referring now to Figure 3, there is shown the detailed structure of
covering material 46. Covering material 46 includes three relatively thick
25 layers of fiber batts 50, 52, and 54 with a thin, loosely woven gauze-like
cloth 56 and 58 interposed between each iayer of fiber batts. Thin loosely
woven cloth 56 and 58 is known as a scrim. Fiber batt layer 50 and fiber batt
layer 52 have a thin gauze-like layer of loosely woven cloth 56 interposed
therebetween. Similarly, fiber batt layer 52 and fiber batt layer 54 have a
30 thin gauze-like layer of loosely woven cloth 58 interposed therebetween.
After each of the layers are assembled in juxposition with one another, the
entire covering material is needle punched. The fiber of the layers of fiber
batts are interlocked with the fibers of the loosely woven layer of cloth
interposed therebetween. A typical prior art needling appara-tus is disclosed in35 U.S. Patent Number 3,112,552 issued to Smith II on December 3, 1963. The
needling apparatus described therein includes a plurality of barbed needles
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which are adapted to penetrate the composite covering material and then be
withdrawn therefrom. The barbed needles are designed to alternatively lift
and press the fibers between the layers so as to entangle them with one
another. Thus,the barbed needles cause the fibers of fiber batt layers 50 and
5 52 to be interlocked with the thin, loosely woven cloth layer 56 interposed
therebetween. Similarly, the needling operation also causes the fibers of fiber
batts 52 and 54 to be interlocked with loosely woven cloth 58 interposed
therebetween. Fiber batt layers 50, 52 and 54 may be made from any suitable
synthetic materials including a polyester, Teflon, i.e. polytetrafluorethylene,
10 Nomex or natural fibers, such as wool, or any other fiber or blends thereof
which are suitable for metering silicone oil. Similarly, the scrim, i.e. the
loosely woven gauze-like layers of cloth 56 and 58 interposed between fiber
batts 50 and 52, and 52 and 54, respectively, may also be made from any
suitable synthetic fibers including polyester, Teflon, i.e.
15 polytetrafluorethylene, or Nomex or natural fibers, such as wool, or any other
fibers or blends thereof. It has been found that the covering material of the
present invention meters precise quantities of silicone oil from the fluid
retaining material to the fuser roll while having significantly improved wear
- resistance and extended life. A covering material, having the layers of fiber
20 batts and the thin loosely woven cloth layers interposed therebetween made
from Nomex, is believed to have a life of approximately two times that of the
conventional covering material, i.e. of about 250,000 copies when used in an
electrophotographic printing machine.
In recapitulation, it is clear that the improved covering material
25 has a plurality of layers of fiber batts with a thin, loosely woven gauze-like
cloth layer interposed between each layer of fiber batts with the fibers of the
fiber batt layers being interlocked with the thin loosely woven cloth interposedtherebetween by a needling process. A covering material made in the
foregoing manner has significantly greater wear than covering materials
30 hereinbefore employed.
It is, therefore, evident that there has been provided in accordance
with the present invention a fluid applicating wick which fully satifies the
aims and advantages hereinbefore set forth. While this invention has been
described in conjunction with a specific embodiment thereof, it is evident that
35 may alternatives, modifications, and variations will be apparent to those
skilled in the art. Accordingly, it is intended to embrace all such alternatives,
g
modifications, and variations as fall within the spirit and broad scope of the
appended claims.
