Apparatus for controlling image disturbing effects of a sheet motion opposing force

A sheet transport apparatus for transporting an image carrying sheet into a fusing apparatus without image disturbances from a sheet motion opposing force. The sheet transport apparatus includes a baffle plate positioned along a line of sheet movement into the fusing apparatus, and active means for moving the image carrying sheet over and towards the baffle plate. The sheet transport apparatus also includes a generally triangular member having a flat base positioned on the baffle plate, and an upstream flank as well as a downstream flank forming an apex thereof for creating a convex buckle in the image carrying sheet prior to the image carrying sheet being subjected to a sheet motion opposing force from contact with the fusing apparatus.

BACKGROUND OF THE INVENTION 
This invention relates generally to an electrostatographic printing 
machine, and more particularly concerns an apparatus for controlling 
unfused image disturbing effects of a sheet motion opposing force during a 
sheet transport. 
In an electrostatographic printing machine, a photoconductive member is 
charged to a substantially uniform potential to sensitize the surface 
thereof. The charged portion of the photoconductive member is exposed to a 
light image of an original document being reproduced. Exposure of the 
charged photoconductive member selectively dissipates the charge thereon 
in irradiated areas. This records an electrostatic latent image on the 
photoconductive member corresponding to the informational areas contained 
within the original document being reproduced. After the electrostatic 
latent image is recorded on the photoconductive member, the latent image 
is developed by bringing toner, for example, black toner, into contact 
therewith. This forms a toner powder image on the photoconductive member 
which is subsequently transferred to a copy sheet. The copy sheet is then 
separated from the photoconductive member and the toner powder is fed on 
the copy sheet through a fusing apparatus where it is heated to 
permanently affix it to the copy sheet, thus forming a black and white 
copy of the original document. 
Multi-color electrostatographic printing which uses multi-colored toners is 
substantially identical to the foregoing process of black and white 
printing using only black toner. However, rather than forming a single 
latent image on the photoconductive surface, successive single color 
latent images corresponding to color separated light images of the 
original document are recorded thereon. Each single color electrostatic 
latent image is developed with toner particles of a color complimentary 
thereto. This process is repeated a plurality of cycles for differently 
colored images using their respective complimentarily colored toner 
particles to form color toner images. Each single color toner powder image 
is transferred to a copy sheet in superimposed registration with the other 
toner powder images. This creates a composite multi-layered toner powder 
image on the copy sheet. The copy sheet is separated from the 
photoconductive member and, thereafter, the multi-layered toner powder 
image on the sheet is fed through a fusing apparatus and permanently 
affixed to the copy sheet, thus creating a color copy of the original 
multi-color document. 
In a black and white or multi-color electrostatographic printing machine, 
the copy sheet is typically brought into moving contact with the 
photoconductive member during toner powder image transfer to the copy 
sheet. A sheet transport apparatus is typically provided for receiving the 
copy sheet incrementally as it is incrementally separated from the 
photoconductive member, and for transporting the copy sheet towards and 
into the fusing apparatus. A typical fusing apparatus includes a rotatable 
heated roller and a rotatable back up roller which form a fusing nip for 
contacting, engaging and frictionally driving the copy sheet with the 
toner powder image thereon through the fusing nip. 
In transporting the copy sheet into the fusing nip, there is a specific 
kind of toner powder image disturbance or smear that occurs only once, and 
only at a particular instance. This specific kind of image disturbance or 
smear is a copy defect that is created at the instance when the lead edge 
of the copy sheet contacts any part of the fusing apparatus. This is 
because when the lead edge of the copy sheet contacts the fusing 
apparatus, an instantaneous backward force is generated by the fusing 
apparatus in the copy sheet regardless of the speeds of the sheet or the 
fusing apparatus. This backward force as such is in opposition to the 
forward motion of the copy sheet. This opposition occurs only during a 
small, short period of time (t). During such time period (t) motion, the 
opposing force virtually brings the lead edge to a complete stop, all 
prior to driving engagement of the lead edge by the fusing nip. As a 
consequence, the whole sheet also virtually stops instantaneously during 
such period (t), thus causing slippage of the separating sheet against the 
photoreceptor, and resulting in the specific image disturbance or smear 
described above. 
The specific kind of instantaneous image disturbance or smear described 
here is believed to be different from on-going image smear that occurs due 
to a mismatch between the velocities or speeds of the fusing nip and the 
photoconductive member. Such on-going image smear is of concern, of 
course, only after the lead edge of the copy sheet is already in driving 
engagement within the fusing nip. On the other hand, the specific kind of 
instantaneous smear or "fuser smear" being addressed by the present 
invention occurs at the instance of lead edge contact within the fusing 
apparatus. Such contact as can be appreciated occurs prior to driving 
engagement of the lead edge by the fusing nip, and, consequently, the 
"fuser smear" defect would appear to be independent of speed or velocity. 
Conventionally, however, "fuser smear" and on-going smear have been treated 
as being caused by speed or velocity mismatches between the sheet and 
fusing apparatus. As such, various devices and schemes have been proposed 
for preventing smearing, by matching the speed or velocity of the fusing 
nip and that of the sheet being transported thereinto. For example: 
U.S. Pat. No. 3,902,645 describes a machine which includes rolls between 
which a flexible sheet is passed. After passing from one section, the 
flexible sheet falls downwardly to form a loop, the other side of which 
passes upwardly into another section of the machine. A motor drives a roll 
which advances the sheet from one section to the other section. A 
pivotable plate contacts the lowermost region of the loop. The direction 
that the plate pivots depends upon the whether the loop is increasing or 
decreasing. The direction that the plate pivots matches speeds by 
controlling the speed of the motor advancing the sheet. 
U.S. Pat. Nos. 4,017,065 and 4,058,306 disclose a vacuum support interposed 
between the fuser and the photoreceptor. When the lead edge of the copy 
sheet enters the fuser roll nip, the vacuum is turned off and a buckle 
forms in the sheet due to the speed mismatch between the fuser and the 
photoreceptor. 
U.S. Pat. No. 4,561,581 describes a web accumulator positioned between a 
variable speed drive and an intermittent drive. A portion of a web in the 
accumulator is curved into a downward extending loop by a curved support 
and the force of gravity acting on the web. 
U.S. Pat. No. 5,294,965 issued Mar. 15, 1994, (Xerox) discloses an 
oscillating prefuser vacuum sheet transport which has a pivoting 
downstream end for compensating for a velocity mismatch between a fuser 
roll and an image receiver. The pivoted end of the transport forms a 
controlled buckle in an image carrying sheet after the sheet contacts the 
fuser roll. 
U.S. 5,166,735 issued Nov. 24, 1992, discloses a prefuser sheet transport 
system that includes a buckle sensor and is offset from a linear path to 
the fuser nip. A signal from the buckle sensor is used to control the 
speed of the fuser to a matching value. 
U.S. Pat. No. 4,905,052 issued May 22, 1990, discloses a copier/printer 
that has an image transfer station and a fusing station operating at 
different speeds in order to create a buckle in a sheet. A sensor located 
therebetween senses the size of the buckle, and at predetermined sizes 
thereof, adjusts the speeds of the stations. 
U.S. Pat. No. 4,905,052 issued Feb. 27, 1990, discloses apparatus for 
compensating for velocity mismatches between adjacent sheet transports 
including a first or upstream transport which advances the sheet faster 
than a second downstream transport. The apparatus further includes a 
pivotable plate between the adjacent transports that pivots away from the 
sheet when the sheet contacts the second or downstream transport, thus 
allowing the sheet to buckle. 
U.S. Pat. No. 4,561,756 issued Dec. 31, 1985, discloses a transport system 
for a short prefuser paper path. Speed mismatch compensation is provided 
by intentionally driving the fuser roller nip at a mismatching speed to 
create a downward buckle. The transport system includes a multiple baffle 
arrangement which allows the downward buckle to form prior to entering the 
fuser nip. The downward buckle is supposed to absorb speed mismatches 
thereby preventing image smearing. 
SUMMARY OF THE INVENTION 
In accordance with one aspect of the present invention, there is provided a 
reproduction machine including means for forming and transferring a toner 
image onto an image-side of an image carrying sheet and a fusing apparatus 
for contacting the image carrying sheet to fuse the toner image thereonto. 
The reproduction machine also includes a buckling device for preventing 
the image bearing member from smearing the toner image by creating an 
image-side convex buckle in the image carrying sheet prior to contact 
between the image carrying sheet and the fusing apparatus. 
In accordance with another aspect of the present invention, there is 
provided in a reproduction machine including a fusing apparatus and means 
for forming and transferring a toner image onto an image carrying sheet, a 
sheet transport apparatus for transporting the image carrying sheet into 
the fusing apparatus without image disturbances from a sheet motion 
opposing force. The sheet transport apparatus includes a baffle plate 
positioned along a line of sheet movement into the fusing apparatus, and 
active means for moving the image carrying sheet over and towards the 
baffle plate. The sheet transport apparatus also includes a generally 
triangular member having a flat base positioned on the baffle plate, and 
an upstream flank as well as a downstream flank, both forming an apex 
thereof for creating a convex buckle in the image carrying sheet prior to 
the image carrying sheet being subjected to a sheet motion opposing force 
from contact with the fusing apparatus. 
Other features of the present invention will become apparent from the 
following drawings and description.

DETAILED DESCRIPTION OF THE INVENTION 
While the present invention will 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 
appended claims. 
For a general understanding of the features of the present invention, 
reference is made to the drawings. In the drawings, like reference 
numerals have been used throughout to designate identical elements. FIG. 1 
schematically depicts the various components of an illustrative 
electrostatographic reproduction or printing machine incorporating the 
sheet transport apparatus of the present invention therein. It will become 
evident from the following discussion that the apparatus of the present 
invention is equally well suited for use in a wide variety of printing 
machines, and is not necessarily limited in its application to the 
particular electrophotographic printing. 
Inasmuch as the art of electrostatographic printing is well known, the 
various processing stations employed in the FIG. 1 printing machine will 
be shown hereinafter only schematically and their operation described only 
briefly with reference thereto. 
As shown in FIG. 1, the electrostatographic printing machine 8 employs a 
photoconductive belt 10. Preferably, the photoconductive belt 10 is made 
from a photoconductive material coated on a grounding layer, which, in 
turn, is coated on an anti-curl backing layer. The photoconductive 
material is made from a transport layer coated on a generator layer. The 
transport layer transports positive charges from the generator layer. The 
interface layer is coated on the grounding layer. The transport layer 
contains small molecules of di-m-tolydiphenylbiphenyldiamine dispersed in 
a polycarbonate. The generation layer is made from trigonal selenium. The 
grounding layer is made from a titanium coated Mylar. The grounding layer 
is very thin and allows light to pass therethrough. Other suitable 
photoconductive materials, grounding layers, and anti-curl backing layers 
may also be employed. As shown, belt 10 is moved in the direction of arrow 
12 to advance successive portions of the photoconductive surface 
sequentially through the various processing stations disposed about the 
path of movement thereof. Belt 10 is entrained about idler roller 14 and 
drive roller 16. Idler roller 14 is mounted rotatably so as to rotate with 
belt 10. Drive roller 16 is rotated by a motor coupled thereto by suitable 
means such as a belt drive. As roller 16 rotates, it advances belt 10 in 
the direction of arrow 12. 
Initially, a portion of photoconductive belt 10 passes through charging 
station. At charging station, two corona generating devices, indicated 
generally by the reference numerals 18 and 20 charge photoconductive belt 
10 to a relatively high, substantially uniform potential. Corona 
generating device 18 places all of the required charge on photoconductive 
belt 10. Corona generating device 20 acts as a leveling device, and fills 
in any areas missed by corona generating device 18. 
Next, the charged photoconductive surface is rotated to exposure station 
BB. Exposure station BB includes a moving lens system, generally 
designated by the reference numeral 22, and a color filter mechanism, 
shown generally by the reference numeral 24. An original document 26 is 
supported stationarily upon platen and is illuminated by means of a moving 
lamp assembly, shown generally by the reference numeral 30. Mirrors 32, 34 
and 36 reflect the light rays through lens 22. Lens 22 is adapted to scan 
successive areas of illumination of platen 28. The light rays from lens 22 
are reflected by mirrors 38, 40, and 42 to be focused on the charged 
portion of photoconductive belt 10. Lamp assembly 30, mirrors 32, 34 and 
36, lens 22, are moved with respect to the movement of photoconductive 
belt 10 to produce a flowing light image of the original document on 
photoconductive belt 10 in a non-distorted manner. During exposure, filter 
mechanism 24 interposes selected color filters into the optical light path 
of lens 22. The color filters operate on the light rays passing through 
the lens to record an electrostatic latent image, i.e. a latent 
electrostatic charge pattern, on the photoconductive belt corresponding to 
a specific color of the flowing light image of the original document. 
Subsequent to the recording of the electrostatic latent image on 
photoconductive belt 10, belt 10 advances the electrostatic latent image 
to development station CC. Development station CC includes four individual 
developer units generally indicated by the reference numerals 44, 46, 48 
and 50. The developer units are of a type generally referred to in the art 
as "magnetic brush development units." Typically, a magnetic brush 
development system employs a magnetizable developer material including 
magnetic carrier granules having toner particles adhering 
triboelectrically thereto. The developer material is continually brought 
through a directional flux field to form a brush of developer material. 
The developer particles are continually moving so as to provide the brush 
consistently with fresh developer material. Development is achieved by 
bringing the brush of developer material into contact with the 
photoconductive surface. Developer units 44, 46, and 48, respectively, 
apply toner particles of a specific color which corresponds to the 
compliment of the specific color separated electrostatic latent image 
recorded on the photoconductive surface. 
The color of each of the toner particles is adapted to absorb light within 
a preselected spectral region of the electromagnetic wave spectrum 
corresponding to the wave length of light transmitted through the filter. 
For example, an electrostatic latent image formed by passing the light 
image through a green filter will record the red and blue portions of the 
spectrums as areas of relatively high charge density on photoconductive 
belt 10, while the green light rays will pass through the filter and cause 
the charge density on the photoconductive belt 10 to be reduced to a 
voltage level ineffective for development. The charged areas are then made 
visible by having developer unit 44 apply green absorbing (magenta) toner 
particles onto the electrostatic latent image recorded on photoconductive 
belt 10. Similarly, a blue separation is developed by developer unit 46 
with blue absorbing (yellow) toner particles, while the red separation is 
developed by developer unit 48 with red absorbing (cyan) toner particles. 
Developer unit 50, on the other hand, contains black toner particles and 
may be used to develop the electrostatic latent image formed from a black 
and white original document. 
Each of the developer units is moved into and out of an operative position. 
In the operative position, the magnetic brush is closely adjacent the 
photoconductive belt, while, in a non-operative position, the magnetic 
brush is spaced therefrom. During development of each electrostatic latent 
image only one developer unit is in the operative position, the remaining 
developer units are in the non-operative position. This insures that each 
electrostatic latent image is developed with toner particles of the 
appropriate color without co-mingling. In FIG. 1, developer unit 44 is 
shown in the operative position with developer units 46, 48 and 50 being 
in the nonoperative position. 
After development, the toner image is moved to transfer or detack station 
DD where the toner image is transferred to a copy sheet 52, such as plain 
paper amongst others. At transfer station DD, a transfer conveyor, 
indicated generally by the reference numeral 54, moves copy sheet 52 into 
contact with photoconductive belt 10. Photoconductive belt 10, for 
example, is being moved at a velocity of about 7.5 inches per second in 
the direction of arrow 12. Transfer conveyor 54 has a pair of spaced belts 
56 entrained about three rolls 58, 60 and 62. A gripper 64 extends between 
belts 56 and moves in unison therewith. Sheet 52 is advanced from a stack 
of sheets 72 disposed in tray 74. Feed roll 77 advances the uppermost 
sheet from stack 72 into the nip defined by forwarding rollers 76 and 78. 
Forwarding rollers 76 and 78 advance sheet 52 to transfer conveyor 54. 
Sheet 52 is advanced by forwarding rollers 76 and 78 in synchronism with 
the movement of gripper 64. In this way, the leading edge of sheet 52 
arrives at a preselected position to be received by the open gripper 64. 
The gripper then closes securing the sheet thereto for movement therewith 
in a recirculating path. The leading edge of the sheet is secured 
releasably by gripper 64. As the belts move in the direction of arrow 66, 
sheet 52 moves into contact with the photoconductive belt, at a transfer 
zone 68 in synchronism with the toner powder image developed thereon. 
Transfer conveyor 54 advances sheet 52 at about 7.5 inches per second. A 
corona generating device 70 sprays ions onto the backside of the sheet so 
as to charge the sheet to the proper magnitude and polarity for attracting 
the toner powder image from photoconductive belt 10 thereto. 
Sheet 52 remains secured to gripper 64 so as to move in a recirculating 
path for three cycles. In this way, three different color toner powder 
images are transferred to sheet 52 in superimposed registration with one 
another. Thus, the aforementioned steps of charging the photoconductive 
surface, exposing the photoconductive surface to a specific color of the 
flowing light image of the original document, developing the electrostatic 
latent image recorded on the photoconductive surface with appropriately 
colored toner, and transferring the toner images to the sheet of support 
material are repeated a plurality of cycles to form a multi-color copy of 
a colored original document. During transfer of the toner powder images to 
sheet 52, sheet 52 is electrostatically tacked to photoconductive belt 10 
and moves therewith. After the last transfer operation, the lead edge of 
sheet 52 is stripped from photoconductive belt as it approaches roller 14. 
Thereafter, grippers 64 open and release sheet 52. 
In accordance with the present invention, a sheet transport, indicated 
generally by the reference numeral 80, then acquires the lead edge of 
sheet 52. Sheet transport 80 is mounted preferably in a substantially 
horizontal orientation, and includes a driven belt, and a vacuum transport 
section 81 so that the sheet is secured releasably to the belts of the 
transport by the vacuum applied thereon. Sheet transport 80 transports 
sheet 52, in the direction of arrow 82. The surface of sheet 52 opposed 
from the surface having the toner powder images transferred thereto is in 
contact with the belts of transport section 81. Thus, the unfused toner 
powder images on the image-side of sheet 52 remain undisturbed. The sheet 
transport apparatus 80 also includes a baffle plate 83 that is positioned 
along a line of sheet movement into fusing apparatus 85 at fusing station 
EE, and guides the lead edge of sheet 52 into the fusing nip defined by 
fuser roller 84 and pressure roll 86 for fusing. Sheet transport 80 as 
such thus can secure and move the sheet 52 with a steady forward motion 
force towards the fuser 85. 
Referring now to FIGS. 2 to 4, the sheet transport 80 importantly includes 
a buckling device 120 for preventing image bearing member or 
photoconductive belt 10 from smearing the unfused toner powder image on 
the sheet 52, at the moment of contact between the sheet and the fusing 
apparatus. The buckling device does so by creating an image-side convex 
buckle 122 in the image carrying sheet 52 prior to such sheet making 
contact with the fusing apparatus 85. As shown, buckling device 120 
preferably is a generally triangular member having a flat base 124 
positioned on the baffle plate 83. The buckling device 120 as shown thus 
includes an upstream flank 126 as well as a downstream flank 128 that 
together form an apex 130 thereof. The apex 130 is preferably located at a 
predetermined distance "L" upstream (relative to movement of the sheet 52) 
from the fusing apparatus. The lead edge of sheet 52 thus can be moved up 
the upstream flank 126 (FIG. 3) so as to project beyond the apex 130 
without making contact with the fusing apparatus 85, and until the force 
of gravity pulls such lead edge and projecting section of the sheet 52 
downwards into contact with the downstream flank 128. Depending on the 
bond weight of the sheet 52, the distance "L" which is required to cause 
the projecting section of the sheet to drop gravitationally onto the 
downstream flank as such, preferably is within a range of 35 mm for 
lighter weight sheets, and 65 mm for heavier sheets. The height "h" of the 
apex 130 is preferably within a range of 0.5-2.0 mm at such a distance "L" 
from the fusing apparatus 85 in order to provide a significant initial 
convex buckle over the apex. As such, the buckling device 120 can 
effectively create the convex buckle 122 in the image carrying sheet 52 
prior to the image carrying sheet being subjected to a sheet motion 
opposing force (FIG. 5) from contact with the fusing apparatus 85. 
The transport apparatus 80 also includes a substantially horizontal sheet 
active transport assembly 140 which for example includes driven belts 150 
and vacuum means 160 for securing and moving the image carrying sheet 52 
with a steady forward motion force onto the buckling device 120. The 
buckling device 120 is mounted downstream of the transport assembly 140. 
The purpose of the transport apparatus of the present invention is to 
prevent instantaneous toner smear occurring on the sheet 52 within a nip 
formed by the sheet 52 and the photoreceptor 10 as the sheet is being 
separated therefrom. The buckling device 120 operates to create an 
anti-gravity buckle prior to the lead edge of the sheet 52 making contact 
with the fusing apparatus 85. As such, the anti-gravity buckle acts to 
prevent the entire section of the sheet between the contacting fusing 
apparatus and the image transfer nip from transmitting the effects of the 
sheet motion opposing force from the fusing apparatus back to into the nip 
between the sheet and the photoreceptor. 
Without the buckle 122 to absolve both the forward feeding force effect of 
the transport assembly 140, and the motion opposing effect of lead edge 
contact of the sheet with fusing apparatus 85, the sheet 52 will be forced 
to reduce its velocity for an instant. An unbuckled sheet, or a concave 
buckle sheet ordinarily will completely transmit the net effects of the 
opposing force. This is because ordinary gravitational pull downwards on 
the sheet section forming the concave buckle would cause the buckling 
section to bottom out, thus leaving little or no room for additional 
buckling to absolve the simultaneous effects of sheet feeding and opposing 
forces. Such transmission of the net effects of an opposing force will 
thus compress the sheet 52 against the electrostatic force ordinarily 
holding it onto the photoconductive surface of belt 10 (FIG. 1), therefore 
resulting in the undesirable instantaneous smear. 
With continued reference to FIG. 1, as the sheet 52 continues to advance 
through the fusing nip, the buckle in the sheet is slowly eliminated and 
the trailing portion of the sheet is dragged off the sheet transport 80. 
After sheet 52 exits the fusing nip defined by fuser roller 84 and 
pressure roller 86, sheet 52 is advanced by a series of forwarding roll 
pairs 88 to catch tray 90 for subsequent removal therefrom by a machine 
operator. While the buckle 122 and trail edge of the copy sheet are being 
created by the sheet transport 80, the rest of the printing machine 10 
continues to process the next copy. Inasmuch as a full color copy takes 
three passes, there is sufficient time to remove the copy before the next 
copy makes the transition to sheet transport 80. Further details of the 
foregoing are shown in FIGS. 2 to 5. 
The last processing station in the direction of movement of belt 10, as 
indicated by arrow 12 is cleaning station FF. A rotatably mounted fibrous 
brush 92 is positioned in cleaning station FF and maintained in contact 
with photoconductive belt 10 to remove residual toner particles remaining 
after the transfer operation. Thereafter, lamp 94 illuminates 
photoconductive belt 10 in order to remove any residual charge remaining 
thereon prior to the start of the next successive cycle. 
Referring to FIGS. 2 to 5, there is shown the fusing apparatus 85 and part 
of the sheet transport 80 advancing an image carrying sheet 52 from 
photoconductive belt 10 towards the fusing apparatus 85. Sheet transport 
80 includes a plurality of driven belts 150 entrained about rollers 106 
and 108. Roller 106 is spaced from roller 108. A vacuum plenum 160 is 
positioned interiorly of belts 150 so as to reduce the pressure at the 
surface thereof to vacuum tack sheet 52 thereon. Roller 106 is driven by a 
motor (not shown) to move belts 150 in the direction of arrow 82. In this 
way, sheet 52, secured by the vacuum releasably on belts 150 is moved in 
unison therewith in the direction of arrow 82. As the lead edge of sheet 
52 advances towards the fusing apparatus. 85, it is guided by the buckling 
device 120 and plate 83 into the nip 112 defined by fuser roller 84 and 
pressure roller 86. First, the lead edge of the sheet 52 makes contact 
within the nip 112. The fuser roller 84 and pressure roller 86 then 
cooperate with one another to engage the lead edge and thereafter 
frictionally advance sheet 52 through nip 112. It is noted that during 
such engagement and frictional driving, mismatches between the speeds of 
the fusing rollers and of the sheet 52, would ordinarily result in ongoing 
image smearing, particularly where the sheet is longer than the distance 
between the detack station and the fusing nip 112. 
In recapitulation, a reproduction machine has been provided and includes a 
movable image bearing member, means for forming a toner image on the 
movable image bearing member, and means for supplying an image carrying 
sheet into contact with the movable image bearing member to receive the 
toner image thereon. The reproduction also includes detack means for 
separating the image carrying sheet and the toner image from the movable 
image bearing member, and a fusing apparatus forming a fusing nip for 
contactably receiving and fusing the toner image onto the image carrying 
sheet. The fusing apparatus is positioned downstream of the detack means 
relative to movement of the separated image carrying sheet. More 
importantly, the reproduction machine includes buckling means for 
preventing an instantaneous smear of a portion of the toner image by the 
detack means when the image carrying sheet initially contacts the fusing 
apparatus. The buckling means is positioned between the fusing nip and the 
detack means for creating a convex, image-side buckle in the image 
carrying sheet prior to the image carrying sheet making contact with the 
fusing apparatus. 
While this invention has been described in conjunction with a specific 
embodiment thereof, it is evident that many alternatives, modifications, 
and variations will be apparent to those skilled in the art. Accordingly, 
it is intended to embrace all such alternatives, modifications and 
variations that fall within the spirit and broad scope of the appended 
claims.