Note: Descriptions are shown in the official language in which they were submitted.
10S86~g8
BACKGROUND OF THE INVENTION
This invention relates generally to copier apparatus,
and, more particularly, to a roll fusing system for fixing elec-
troscopic toner material to a support member.
In the process of xerography, a light image of an
original to be copied is typically recorded in the form of a
latent electrostatic image upon a photosensitive member with
subsequent rendering of the latent image visible by the appli-
cation of electroscopic marking particles, commonly referred
to as toner. The visual image can be either fixed directly
upon the photosensitive member or transferred from the member
to a sheet of plain paper with subsequent affixing of the
image thereto.
There are various ways of fusing or affixing the
toner particles to the support member, one of which is by the
employment of heat. In order to permanently affix or fuse
electroscopic toner material onto a support member by heat, it
is necessary to elevate the temperature of the toner material
to a point at which the constituents of the toner material
coalesce and become tacky. This àction causes the toner to
be absorbed to some extent into the fibers of the support member
which, in many instances, constitute plain paper. Thereafter,
as the toner material cools, solidification of the toner material
occurs causing the toner material to be firmly bonded to the
support member. In both the xerographic as well as the electro-
graphic recording arts, the use of thermo energy for fixing
toner images onto a support member is old and well known.
One approach to thermofusing of electroscopic toner
images onto a support has been to pass the support with the
toner images thereon between a pair of opposed roller members,
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at least one of which is either externally or internally h~ated.
During operation of a fusing system of this type, the support
member to which the toner images are electrostatically adhered
is moved through the nip formed between the rolls with the
toner images contacting the fuser roll to thereby effect heating
of the toner images within the nip. In order to enhance fusing
of the toner i~ages in the foregoing manner, the backup roll
of the fuser roll pair is usually constructed so that the fuser
roll creates a depression in the backup roll as the result of
a biasing force which forces the rolls into engagement. To
this end the backup roll comprises a rigid core having a rela-
tively thick elastomeric layer affixed thereto and an outer
layer or sleeve of abhesive material. The abhesive material
exhibits a low affinity for tackified toner. The aforementioned
depression is continually formed as different portions of the
backup roll move into and out of engagement resulting in a
large number of flexures of the outer layer. The useful life
of such backup rolls depends to a large degree on the ability
of the material forming the outer layer to withstand the strain
of continued flexing.
A BRIEF SUMMARY OF THE INVENTION
In accordance with one aspect of this invention
there is provided fuser member for a roll fusing apparatus
utilized in fixing toner images to support sheets, said member
comprising: a rigid core; a layer of resilient material adhered
to said rigid core; and an outer layer over said resilient layer,
said outer layer comprising a copolymer of perfluoroalkyl per-
fluorovinyl either with tetrafluoroethylene, said ether ~a~ ~
la Cn 2n+1 C CF2.
In accordance with another aspect of this invention there
is provided fuser apparatus for utilization in fixing toner images
to copy sheets, said apparatus comprising: a heated fuser roll
structure; a backup roll supForted for pressure engagement with
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said fuser roll structure to thereby form a nip through which
said copy sheets pass with said images contacting said heated
fuser roll structure; said backup roll comprising: a rigid core;
a layer of resilient material adhered to said rigid core; and
an outer sleeve fabricated from a copolymer of perfluoroalkyl
perfluorovinyl ether with tetrafluoroethylene, said ether
having the formula CnF2n+l-o-cF=cF2.
In accordance with another aspect of this invention
there is provided copier apparatus including structure for
forming toner images on copy sheets and structure utilized in
fixing the toner images to the copy sheets wherein the latter
structure comprises: a backup roll comprising: a rigid core;
a layer of resilient material adhered to said rigid core; and
an outer sleeve fabricated from a copolymer of perfluoroalkyl
perfluorovinyl ether with tetrafluoroethylene, said ether
having the formula CnF2n+l-O-CF=CF2~
By way of added explanation, in accordance with
an aspect of this invention there is provided a
backup roll which comprises a composite
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scructure including a rigid core supporting an outer layer
of abhesive material and an intermediate layer of silicone
rubber. The thickness of the rubber and the abhesive material
are such as to readily yield to the force of the fuser roll
structure.
The outer layer comprises a fluorocarbon resin manu-
factured by E.I. DuPont de Nemours and Co. (Inc.) which is
designated "Teflon"* PFA Fluorocarbon Resin. This type of
resin is a melt fabricable perfluoropolymer which combines
the carbon-fluorine backbone in the main chain with perfluoro-
alkoxy side chains.
Other aspects and advantages of the present invention
will become apparent when read in conjunction with the accom-
panying drawings:
Figure 1 is a schematic representation of a xero-
graphic reproducing apparatus incorporating the contact fusing
system of this invention;
Figure 2 is a cross-sectional view of the fusing
8ystem forming this invention;
Figure 3 is a cross-sectional view taken along the
line III-III of Figure 2;
Figure 4 is a side elevational view of the fuser
forming the present invention with the backup roll and fuser
rolls disengaged;
Figure 5 is an elevational view of the fuser system
similar to Figure 4 but with the fuser roll and backup roll
engaged;
Figure 6 (second sheet of drawings) is a fragmentary
view of a flexible drive coupling; and
Figure 7 (third sheet of drawings) is a top plan view
of the fuser assembly illustrated in Figure 2.
* trade mark
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DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to the drawings, especially Figure 1,
there i8 disclosed an automatic xerographic reproducing machine 9
incorporating the roll fuser system of the present invention.
The automatic xerographic reproducing machine includes a xero-
graphic plate, or surface 10, formed in the shape of a drum.
The plate has a photoconductive layer or light sensitive surface
on a conductive backing journaled in a frame to rotate in a
direction indicated by the arrow. The rotation will cause the
plate surface to sequentially pass a series of xerographic
processing stations.
For purposes of the present disclosure the several
xerographic processing stations in the path of movement of the
plate surface may be described functionally as follows:
;` 15 a charging station A where a uniform electrostatic
charge is deposited onto the photoconductive plate;
an exposure station B, at which light or radiation
patterns of copies to be reproduced is projected onto the plate
surface to dissipate the charge in the exposed areas thereof,
to thereby form latent electrostatic images of the copies to
be reproduced;
a developing station C, at which xerographic develop-
ing material including toner particles having an electrostatic
charge opposite to that of the latent electrostatic images
is cascaded over the latent electrostatic images to form powder
images in configuration of the copy being reproduced;
a transfer station D, where the powder images are
electrostatically transferred from the plate surface to a
transfer material such as paper, which then is passed through
a heated pressure fusing system according to the present
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invention as will be described hereinafter; and
a drum cleaning and discharge station E, at which
the plate surface is brushed to remove residual toner particles
remaining thereon after image transfer and at which the plate
is exposed to a relatively bright light source to effect sub-
stantially complete discharge of any residual electrostatic
charge remaining thereon.
For further details of the xerographic processing
stations discussed above, reference may be had to U.S. Patent
No. 3,578,859.
A combination pressure and heat fusing system 12
as specifically disclosed in Figures 2 and 3, comprises a
heated fuser roll 16 and a backup roll 18.
The fuser roll structure 16 comprises a rigid cylin-
drical member 20, preferably fabricated from steel, to which
end caps or closures 22 and 22' have been affixed in any suit-
able manner, for example, by brazing. The member 20 in one
operative embodiment has an outside diameter of 2 3/8 inches.
The end cap or closure 22' (Fig. 2) is supported by a bearing
24 carried by a side frame member 26 of the roll fusing assembly
12. The end cap or closure 22 is retained by the hub 28 of a
fuser roll drive gear 30 which hub is, in turn, retained or
supported by a support bearing 32 disposed in a side frame
member 26'.
During operation of the fuser assembly 12 a support
copy or sheet 34 (Fig. 3) is moved through the nip 36 formed
by engagement of the fuser roll structure 16 and the backup
roll structure 18 such that the toner images are contacted by
the fuser roll structure 16. In order to provide thermal energy
for raising the temperature of the toner particles to a suitable
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fusing temperature, a heater element 38 is supported internally
of the cylindrical member 20 by heater sockets 23 and 23 ' . The
heater element may comprise a quartz heater structure including
a quartz envelope having a tungsten resistance heating element
disposed internally thereof. In practice power on the order
of 1475 watts is supplied to the resistance heating element via
electrical connections 39 to thereby raise the surface tempera-
ture of the fuser roll to approximately 380F.
In order to provide the fuser roll structure 16 with
an outer surface which has a relatively low affinity for tackified
toner particles, a fluorocarbon polymer layer 40 of, for example,
tetrafluoroethylene (abbreviated TFE) is provided on the rigid
cylindrical member 20. The TFE layer may be on the order of
1.2 - 1.5 mils thick and the member 20 is preferably fabricated
from a thermally conductive material such as copper or aluminum.
When copper is employed it should be coated with aluminum or
nickel prior to the application of the TFE. The particular
manner in which the fuser roll structure 16 is fabricated forms
no part of the present invention. Accordingly, such fabrication
thereof may be in accordance with well-known processes, for
example, those set forth in U.S. Patents 3,437,032 and 3,776,760.
While the fuser structure is disclosed as having a TFE layer
it may be fabricated without the layer and may simply comprise
a bare metal surface.
By controlling the heat transfer to the toner, virtually
no offset of the toner particles from the copy sheet to the
fuser roll is experienced under normal conditions. This is
because the heat applied to the surface of the roller is in-
sufficient to raise the temperature of the surface of the roller
above the "hot offset~ temperature of the toner, whereat the
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toner particles in the image areas of the toner would liquify
and cause a shearing action in the molten toner to thereby
result in "hot offset". Shearing occurs when the inter-
particle or cohesive forces holding the viscous toner mass
together are less than the adhesive forces tending to offset
it to a contacting surface such as a fuser roll.
Occasionally, however, toner particles will be offset
to the fuser roll by an insufficient application of heat to
the surface thereof (i.e. "cold" offsetting); by imperfections
in the properties of the surface of the rolls; or by the toner
particles insufficiently adhering to the copy sheet by the
electrostatic forces which normally hold them there. In such
a case, toner particles may be transferred to the surface of
the fuser roll with subsequent transfer to the backup roll
during periods of time when no copy paper is in the nip.
Moreover, toner particles can be picked up by the
fuser and/or backup roll during fusing of duplex copies or
simply from the surroundings of the reproducing apparatus.
To minimize the chanc~ of offsetting toner to the
fuser roll a thin layer of organosiloxane polymer or other
suitable material is applied to the surface of the fuser roll
structure 16 to thereby form an interface between the roll
surface and the toner images carried on the support material.
Thus a low surface energy layer is presented to the toner as
it passes through the fuser nip and thereby minimizes the
degree of offsetting of toner to the fuser roll surface.
For the purpose of applying the organosiloxane polymer
material, commonly known as silicone oil, to the fuser roll
structure 16, a quantity of silicon oil 42 is contained in a
sump housing or oil pan 44 forming a part of the fusing assembly
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12. Approximately 0.65 liters of silicone oil in the sump
provides a level therein which extends to the tops of a
plurality of rib members 45. An applicator member 46 is
supported within the housing 44 by means of a support member
48 such that the applicator contacts both the silicone oil
and the surface of the fuser roll 16. As illustrated in Fig. 3,
one end of the applicator member is physically attached to the
support member 48 as indicated at 49 while the other end
thereof extends into the silicone oil and actually touches
the bottom of the sump 44.
The applicator preferably comprises a material which
is heat resistant and which is capable of wicking silicone oil
from the sump to the fuser roll structure. To this end, the
applicator material is preferably a copolymer of meta-phenylene-
diamine and isophthaloyl chloride which corresponds to a heat-
resistant nylon material known under the trademark, Nomex
(E.I. du Pont de Nemours & Co.). In addition to applying
silicone oil to the fuser roll, the applicator cleans toner
therefrom. It has been observed that after extended operation,
for example, fusing of 25 thousand copies, the portion of the
applicator contacting the fuser structure becomes coated with
toner but continues to apply silicone oil to the fuser roll.
The support member 48 comprises an elongated con-
struction which is coextensive with the longitudinal axis
of the fuser roll structure 16 and has a pair of sidewardly
projecting pins 50 and 50' which are received in a pair of
upstanding ribs or channels 52 integrally formed or otherwise
provided in the sump 44, thereby locating the support member 48
relative to the fuser roll structure. The ribs prevent excessive
surging of the oil in the oil pan when the pan is moved and they
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also act as stiffeners for the oil pan. A pair of bias springs
54 (only one being shown) are also received in the channels 52
for biasing the support member upwardly with a total force of
approximately 6 pounds for effecting proper engagement of the
applicator with the fuser roll structure.
The periphery of the support member 48 is provided
with a plurality of concave areas or surfaces 56 each of which
cooperates with only a portion of the applicator 46. When the
portion of the applicator contacting the fuser roll becomes so
toner laden as to lose its effectiveness as either an applicator
or a cleaner, the support member 48 can be reoriented such that
a clean portion of the applicator is moved into alignment with
the fuser roll structure. To accomplish such reorientation the
oil pan 44 is removed from the fuser frame 57 by moving the pan
from the right to left as viewed in Fig. 3.
A doctor blade 58 and support 60 therefore are dis-
posed within the sump 44 such that the blade 58 contacts the
fuser roll structure 16 after the oil has been applied by the
applicator 46. The support 60 is provided with a pair of pin
members 62 received in apertures in the sump 44. Spring members
64 received in standoffs 65 serve to bias the support 60 and
therefore the blade 58 into contact with the fuser roll with
sufficient force (i.e. 8 lbs. total) that the oil applied to
the roll is metered to a thickness such that 6 u liters per
copy of 8 1/2 x 11" paper is utilized. The doctor blade
which may be fabricated from any suitable material for such
purposes, for example, a fluorosilicone elastomer having a
durometer on the order of 80 Shore A, is received in an
elongated channel 66 of the support member.
The backup roll 18 (Figures 2 and 3) which has
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approximately the same overall dimensions as the fuser roll
structure 16 comprises a rigid, generally cylindrical member
68 having an outside diameter of 1 3/4 inches and a 3/16 of
an inch wall thickness and a pair of end caps 70 and 70'
received in the terminal portions of the member 68. A 0.315
inch layer 72 of elastomeric material, preferably a heat-
resistant, organosiloxane polymer commonly known as silicone
rubber, is adhered to the member 68. A 0.019 inch outer layer
or sleeve 74 of high heat-resistant material having a relatively
low affinity for tackified toner is provided over the silicone
rubber layer. The combined thickness and durometer of the
layers 72 and 74 is such as to allow for deformation thereof
by the fuser roll structure in order to yield a suitable length
for the nip 36 (i.e. an area coextensive with the concave
portion of the backup roll). A felt pad 75 and support 77
therefor are supported to the fuser assembly frame so that
the pad contacts the surface of the backup roll. Thu8, any
contamination such as toner is removed from the backup roll
during its rotation.
It will be appreciated that as portions of the backup
roll pass throuqh the nip area, the layers 72 and 74 are mechan-
ically stressed due to the flexing thereof. At the present time
the useful life of a structure such as the backup roll 18 ap-
pears to be limited by the failure of the layer or sleeve 74,
the main mode of failure being the splitting or cracking
thereof. Heretofore it has been standard practice to utilize
a heat resistant polymer material such as fluoronated ethylene
propylene (abbreviated FEP) for the outer layer of the backup
roll. For certain machines, the FEP sleeves appear to be
quite satisfactory. However, as operating parameters of copiers,
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such as copier speed increase significantly, it has been found
that the flex fatigue life of FEP sleeves is not satisfactory.
Flex fatigue life is defined as the number of cycles
an FEP or other material strip will undergo before splitting
when flexed 90 degrees under 10% strain between two 20 mil
radius gripper jaws at 330F. Known materials such as the
FEP employed in the production of backup rolls provide rolls
having sleeves or outer layers whose flex life is on the order
of lOK to 60K.
In order to improve the fatigue life of the backup
roll of the present invention, the layer or sleeve 74 has
been fabricated from a material having a flex life far in
excess of the foregoing. Accordingly, the sleeve 74 is fab-
ricated from a copolymer of perfluoroalkyl perfluorovinyl ether
with tetrafluoroethylene wherein the ether has the formula
CnF2n+l-0-CF=CF2 where n could probably be a number from 1-10
inclusive but i9 preferably 1-5 inclusive.
A backup roll 18 is fabricated with a layer of 74
PFA yielded 1.5 million flex fatigue cycles as compared to the
50 thousand cycles obtained with the FEP sleeves.
The end caps 70 and 70' of the backup roll i8 are
supported in a pair of side frame or bracket members 76, 76'
by bearings 78, 78'. The backup roll together with the bearings
and frame members can be readily removed from the fuser assembly
12. To this end, the side frames 76, 76' are provided in the
uppermost portions thereof with hook-like members 80, 80' which
are received in recesses 82, 82' provided in a pair of pivot
arms 84, 84'. The pivot arms support the backup roll for
movement into and out of engagement with the fuser roll struc-
ture 16 in a manner to be discussed hereinafter. A pair of
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bolts 86, 86' fasten the lowermost portions of the side frames
to the pivot arms 84, 84'. The pivot arms are supported by
the machine frame through stub shafts 85.
To install the backup roll 18, the hook-like members
80, 81' are inserted into the recesses 82, 82' with subsequent
installation of the bolts 86, 86'. To remove the backup roll
the foregoing procedure is simply reversed. Both installation
and removal of the backup roll can be accomplished quickly
with a minimum of handling. The hook-like members 80, 80'
replace bolts similar to the bolts 86, 86'. It should be
appreciated that during removal of the backup roll when the
bolts 86, 86' have been removed, the hook-like members support
the backup roll on the pivot arms 84, 84' so that the backup
roll need not be handled until after bolt removal. When the
backup roll i8 hot the foregoing aspect of the backup assembly
i8 ~ignificant. With prior art devices where four bolts are
employed, it is necessary to handle the backup roll while
removing the bolts.
As viewed in Figure 4, the fuser roll structure 16
and the backup roll 18 are supported out of engagement which
corresponds to either an inoperative condition of the copier
apparatus 9 or a warmup period which follows an initiation of
the operation of the copier. The warmup period is required
among other things in order to allow the fuser roll temperature
to rise to a predetermined level suitable for fusing toner
particles on the support member 34. When the rolls 16 and 18
are disengaged rotational movement of the backup roll 18 is
accomplished by means of a flexible shaft 90 which couples a
drive gear 88 to the backup roll 18. Rotational movement is
imparted to the fuser roll structure 16 by virtue of the driven
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gear 30 meshing with the drive gear 88. A shear pin 91 or
other safety drive device secured in the hub of the gear 88
is provided for drivingly coupling the gear to the main drive
motor (not shown) of the machine via a chain (also not shown).
The ends of the flexible drive shaft 90 which are
rectangular in cross-section are received in the end cap 70
and a clutch bearing 92, the latter of which is contained in
the driven gear 88 for a purpose to be discussed hereinafter.
The flexible drive shaft 90 allows for vertical dis-
placement, as viewed in Figure 2, of the backup roll 18 which
displacement is effected by a latching mechanism generally in-
dicated 94 (see Figures 4 and 5). During engagement of the
backup roll and the fuser roll, the backup roll is driven by
the fuser roll and the one-way clutch bearing 92 insures that
the backup roll can be overdriven by the fuser roll.
While other flexible shafts may be employed, the
specific shaft 90 contemplated can be obtained from Stow
Manufacturing Co. under the designation Core # Type 8990-100.
This particular shaft is fabricated by spirally winding wire
~ rope to form a multi-layered structure having a generally
cylindrical cross section. The ends of the shaft are crimped
in order to form them into a generally square configuration.
In operation the rotation of the shaft is in a direction which
tends to tighten the windings thereof and therefore render the
shaft more rigid yet sufficiently flexible to allow for the
aforementioned displacement.
A modified form of the flexible coupling 90, as
illustrated in Figure 6, comprises a double slider coupling
commonly referred to as an Oldham coupling. In order to pro-
vide such an arrangement for coupling the backup roll to a
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drive gear, the end cap 70 is replaced by an end cap 96 having
a slot 98 in the face thereof. A shaft support disposed in-
ternally of the clutch bearing 92 is replaced by coupling
member 100 which has a slot 102 in the ciroular face thereof
similar to the slot 98 but oriented at a 90 angle thereto.
An interposer member 104 replaces the shaft 90 and drivingly
couples the end cap 96 to the coupling member 100. To this
end the interposer member comprises a generally cylindrical
body portion having a tongue portion 106, 106' formed inte-
grally with each of the faces thereof. This type of coupling
can, as in the case of the flexible shaft 90, permit displace-
ment of the backup roll 18, but it also permits quick removal
of the backup roll 18 from the fuser assembly.
The latching mechanism 94, as best viewed in Figures
4 and 5, comprises a four pivot linkage arrangement which is
actuated by solenoid means 108 mounted on support bracket
means 110 which is a part of the side frame members 26, 26'.
Each of the pivot arms 84 supports a differential screw 112
which in turn supports a moving pivot member 114. The pivot
member 114 operatively connects a link 116 to a link member
118 via a moving pivot 120 and a stationary pivot 122. The
stub shafts 85 supporting the pivot arms 84, 84' act as a
stationary pivot and form one of the four pivots of the linkage
arrangement.
The link 118 has affixed thereto a cam follower in
the form of a roller 124. The core 126 of the solenoid 108
acts as a cam, bearing against the roller 124 to thereby
effect clockwise rotation of the link 118 about the pivot 122.
Simultaneously, the moving pivot 120 moves to the right as
viewed in Figure 4 to a point that is substantially in a
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straight line with a line drawn through the center of the
pivots 114 and 122. An adjustable bumper 128 acts as
stop member by virtue of its contacting the pivot arm 84
as viewed in Figure 5. In this manner the bumper 128 limits
the degree of travel of the pivot 120 to a position just to
the left of the aforementioned line drawn through the center
of the pivots 114 and 122.
A pair of bias springs 130 (only one shown), one
for each of the pivot arms, assist the forces exerted by the
fuser roll structure 16 to effect disengagement of the backup
from the fuser roll when the latching mechanism 94 is inopera-
tive, in other words when the solenoid means 108 is de-energized.
The springs apply a total of approximately 8 lbs. of force.
It will be appreciated that the amount of force required of
the solenoid to maintain the backup and fuser rolls in nip
is quite small. The holding power requirement as opposed to
the latching power requirement for the solenoid is on the
order of 20 watts compared to 320 watts required for effecting
engagement between the rolls so as to create a total force of
800 lbs. during hot nip (i.e. when the fuser roll is at or near
its operating temperature). A second adjustable bumper or
stop 132 integral with the link 118 limits the counterclockwise
travel of the link 118 through its engagement with the solenoid
means 108.
Adjustment of the latching mechanism 94 is effected
through adjustment of the bumpers 128 and 132. With the
solenoid energized the bumper 128 should contact the pivot
arms 84, 84' such that the center of the pivot 120 is just
to the left of the center line through the pivots 114 and 122.
If, when the solenoid is energized, the foregoing is not the
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case then the bumper 128 can be moved toward or away from
the pivot arm, whichever is required.
Nip pressure can be varied through adjustment of
the differential screw 112 once the latching mechanism has
been adjusted. Suitable nip pressure is attained wh~n the
measured contact angle is equal to 0.45 in. This can be done
with standard carbon paper utilized in accordance with estab-
lished procedures for measuring the contact arc between the
backup roll and fuser roll structure.
It will be appreciated that the force exerted by
the fuser roll would normally tend to create a substantial
shear force on the bolts 86, 86'. Consequently, the side
frame members 76, 76' are constructed so as to direct the
aforementioned shear forces through the side frames in a
direction so that these forces are directed against inclined
surfaces 134 of the pivot arms 84, 84'.
The solenoid means 108 may consist of a single D.C.
solenoid, size 8EC available from Ledex Corporation or may
consist of a pair of D.C. solenoids, size 7EC also available
from the Ledex Corporation.
As illustrated in Figure 7, a torque transmission
shaft 136 couples pivot arms 84, 84', to insure proper latching
by the latch mechanism 94. To this end, the lower portions of
the pivot arms are provided with castellated protrusions 138,
138' formed integrally therewith. The shaft 136 supports a
pair of castellated collars 140, 140' which cooperatively engage
the protrusions 138, 138' whereby motion imparted to either of
the pivot arms is transmitted to the other of the arms. The
collar 140 is secured to the shaft by a set screw 142 while
the collar 140' carries a set screw 142' which rides in a
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slot 144 provided in the shaft 136. A coil spring 146 engages
a retaining ring 148 and the collar 140' in order to bias the
collars into engagement with the protrusions 138, 138'. Re-
val of the shaft can be effected by simply moving it to
the right, as viewed in Figure 7, against the force of the
spring 146.
Also illustrated in Figure 7 are a pair of fingers
150, 150' which as viewed in Figure 3 are positioned adjacent
the exit of the nip 36. The fingers effect re val of copy
sheets 34 from the fuser roll structure 16. As the copy sheet
leaves the nip it follows the rotation of the fuser roll
structure, where it comes into contact with the upper surface
of the stripper fingers. The fingers thus become interposed
between the sheet and the fuser roll to thereby redirect the
sheet along a predetermined path of travel away from the
fuser roll so that it can be picked up by a transport (not
shown). The finger may be fabricated from a TFE material
or the upper surface thereof may be coated with TFE in order
to minimize tendency for the copy to s`tick thereon or for
toner to be offset thereto.
As illustrated in Figure 3`, a thermistor 152 and
support 154 therefor are pivotally supported in contact with
the fuser roll structure 16. Fuser roll temperature control
by means of thermistors or other contact sensors is well
known in the art. The temperature of the fuser roll structure
can be controlled in conjunction with the output from the
thermistor by a control circuit such as disclosed in U.S.
Patent 3,327,096.
The entire fuser assembly 12 is supported within the
apparatus 9 by upper and lower slide structures and associated
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mounting brackets and hardware. Only the upper slide 160 is
illustrated. Suitable slides are sold by the Accuride Co.
and are identified by part number C-301-17-LC. The slide
structures and associated brackets support the fuser assembly
in a manner which enables sliding the assembly into and out
of the machine in a direction coincident with the longitudinal
extent of the rolls 16 and 18.
While the invention has been described with respect
to the best made contemplated, it will be appreciated that
various modifications may be made without departing from the
spirit of the invention. Accordingly, it is not intended that
the scope of the coverage sought be limited thereby.
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