Note: Descriptions are shown in the official language in which they were submitted.
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APPARATUS FOR REGISTERING INDICIA WITH LINES OF TERMINATION IN A TRANSPORTED
SHEET
FIELD OF THE INVENTION
The present invention relates to registering indicia with lines of termination
in a sheet. The lines of termination may be perforations or a chop-off, which
ends a first sheet and starts a second sheet, which sheets are typically
presented in roll form. The indicia may be visual, such as printed inks or
embossments, or may be functional, such as adhesive.
BACKGROUND OF THE INVENTION
Sheets for household use are well known in the art. It is often desired to
decorate such sheets, such as by printing. Printing imparts an aesthetically
pleasing pattern to the sheet. Alternatively, the sheet may be embossed to
impart an aesthetically pleasing pattern which is also tactually discernible.
Such sheets are typically made in continuous form, then later cut to
discrete lengths as desired. Such cutting to discrete lengths may occur at the
point of use, such as is caused by the consumer detaching one sheet from the
balance thereof at a line of termination. For this purpose, the line of
termination
typically comprises a line of weakness, such as a perforation. Alternatively,
the
continuous sheet may be cut into discrete portions prior to the point of use.
Such an arrangement often occurs in individual napkins which are cut during
manufacture and purchased by the consumer as discrete units.
It has been relatively facile in the prior art to register indicia with the
cross
machine direction of such sheets while such sheets are transported in a
continuous fashion during manufacture. However, it is more difficult to
register
the indicia in the machine direction, and particularly difficult to register
the indicia
with lines of termination.
One manner with which the foregoing difficulty has been addressed is by
keeping the length of the sheet of the continuous sheet path between the point
at which the indicia are applied and the point at which the lines weakness are
imparted to the sheet relatively short. However, this approach does not
provide
for feasibility in the manufacturing process, requires smaller sized
equipment,
and is simply infeasible where the modules necessary to impart the lines of
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weakness or apply the indicia themselves comprise a web path which is large
enough to cause improper spacing between the indicia and the lines of
weakness.
Another attempt to address this difficulty has been to keep the length of the
path relatively short between the point at which the latter of the indicia and
the
lines of termination are applied or imparted, respectively, to the continuous
sheet and the point at which the continuous sheet is cut to separate it into a
discrete unit at the point of manufacture. This approach works well where
relatively short discrete sheet lengths are desired, as for example with an
individual table napkin.
However, this approach is infeasible where a relatively longer sheet length
is desired as, for example, with a roll product, such as toilet tissue or
paper
toweling. Such difficulty is due to the cumulative error which occurs over the
length of the continuous sheet between the point at which the indicia are
applied
and the lines of perforation imparted to the sheet. By way of example, if a
misregistration of 0.001 inches occurs at a first repeating unit of the
continuous
sheet a misregistration of one inch will occur after 1,000 sheets are
manufactured.
For example, referring to Fig. 1, the cumulative error of discrete napkins,
each having a machine direction length of about 12 inches is about 0.125
inches. Conversely, the prior art cumulative error over 700 inches of
continuous
sheet, as for example the approximate length of an ordinary roll of paper
toweling, is about 0.5 inches. This greater cumulative error makes it
infeasible
to use prior art processes to manufacture such rolls of paper toweling.
An even bigger problem occurs in the prior art when the parent roll is
exhausted and a new parent roll started. The parent roll is the large roll of
product later converted to multiple individual sheets by the apparatus and
process disclosed herein. Different parent rolls have different properties
which
affect the transport of the sheet through the apparatus. For example, the
amount of stretch in the sheet as it travels through the apparatus frequently
varies greatly between parent rolls. As these properties vary, so does the
registration of the indicia with the lines of termination. Such variations in
registration must be accounted for in the manufacturing process.
Each vertex of the two graphs in Fig. 1 represents a chop-off cut, where
the sheet is cut into a discrete unit from the succeeding sheet. The greater
CA 02250012 2003-04-29
length of the paper toweling sheet results in proportionally greater
cumulative
error in the sheet.
As used herein, a "unit" is defined as that portion of the sheet which is
discrete as delivered to the consumer, as, for example, a single table napkin
or a single roll of paper toweling or toilet tissue. It will be apparent that
the
length of the paper toweling or toilet tissue is significantly greater than
the
length of the discrete table napkin. The cumulative error will, of course, be
greater in the; paper toweling or toilet tissue, in an amount proportional to
the
difference in 'the sheet le~nc~th.
Accordingly, approaches which are feasible when dealing with discrete
articles of r~slatively short unit length are not sufficient for dealing with
registration clifficulties which occur in longer sheet lengths. Sheet length
is
defined as the length of product, taken in the machine direction as presented
to the consumer. For example, the sheet length of a discrete napkin or
placemat is the machine direction length of one napkin or placemat. The
sheet length of a roll of perforated paper toweling is the machine direction
length of the entire roll, taken from the point of core attachment to the tail
seal.
It is therefore an abject of an aspect of this invention to provide a
mechanism for overcoming the problems associated with misregistration
between indicia and lines of termination in products having longer unit
length,
and more particularly in core wound paper products, presented to the
consumer in roll form. It is also an object of an aspect of this invention to
provide for adjustment of such spacing while the sheet is being transported
during manufacture.
StJP~IMARY OF THE INVENTION
The invention comprises an apparatus for registering indicia with lines
of termination in a sheet. The registration occurs while the sheet is being
transported nhrough the apparatus. The apparatus comprises a means for
transporting a sheet in a first direction, and means for applying indicia to
the
sheet from a system rroovable relative to the sheet. The apparatus further
comprises a means for imparting lines of termination to the sheet. The
apparatus further comprises a means for adjusting the spaced relationship
between the indicia and the lines of termination. The adjustment may be
made by changing the phase of the indicia or the lines of termination on the
sheet.
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Preferably the lines of termination comprise perforations extending in a
direction
generally orthogonal to the direction of transport.
In one embodiment, the apparatus may comprise a transport mechanism
for transporting the sheet through the apparatus and a blade which imparts a
line of termination to the sheet as it is being transported. The apparatus may
further comprise a system for applying indicia to the sheet, the indicia being
sized to fit between adjacent lines of termination and disposed in spaced
relationship thereto. One of the systems for applying the indicia and the
blade is
adjustable relative to the sheet as it is transported, so that the spacing of
the
indicia relative to the lines of termination can be adjusted while the sheet
is
being transported.
In another embodiment, the invention comprises a process for registering
indicia and lines of termination in a moving sheet. The process comprises the
steps of providing a generally planar sheet. The sheet is transported at a
first
velocity. Indicia are applied to the sheet from a means for applying the
indicia
which is movable relative to the sheet at a second velocity. Lines of
termination
are imparted to the sheet, preferably from a blade movable relative to the
sheet
at a third velocity. The process finally comprises the steps of varying one of
the
first, second or third velocities to adjust or maintain the predetermined
spacing.
In another embodiment, the invention comprises a sheet having indicia and
lines of termination registered with the indicia. The sheet comprises a
generally
planar sheet transportable in a first direction and the indicia applied to the
sheet
as it is transported. The sheet further comprises lines of termination being
in
spaced relationship with the indicia as taken in the first direction. The
spaced
relationship is variable in the first direction while the sheet is
transported. Such
variation allows the lines of termination and the indicia to become closer
together or further apart, without interruption of the transport of the sheet.
In another embodiment, the sheet may have a principal direction coincident
the machine direction of manufacture. The sheet has a length, taken in the
principal direction, of at least 500 inches. The sheet further comprises
indicia
and lines of termination, the indicia and lines of termination being in spaced
relationship relative to one another. The spaced relationship is maintained at
a
tolerance of ~ 0.125 inches throughout the entire length of the sheet.
Preferably
the tolerance is maintained within ~ 0.063 inches.
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In accordance with a further aspect of the present invention, there is
provided an apparatus for registering indicia with lines of termination in a
transported sheet, the apparatus comprising a means for transporting a sheet
in a first direction at a constant velocity; a means for applying spaced
indicia
to the sheet at predetermined repeating intervals and at a first rate; a means
for imparting lines of termination to the sheet at a second rate, the lines of
termination being in spaced relationship to the indicia: and a means for
adjusting them spaced relationship between the indicia and the lines of
termination by adjusting one of said first rate and said second rate.
In accordance with another aspect of the present invention, there is
provided an apparatus for registering indicia with lines of termination in a
sheet, the sheet being transported in a first direction, said apparatus
comprising ~~ transport mechanism for transporting the sheet through the
apparatus at a constant velocity; a blade which imparts a line of termination
to
the sheet, the line of termination being generally orthogonal to the first
direction of transport of the sheet, whereby the sheet has leading and
trailing
edges defrned by the lines of termination; a component for applying indicia to
the sheet, the indicia braing sized to fit within the leading and trailing
edges
and disposed in spaced relationship thereto, one of the component and the
blade being adjustable relative to the sheet as it is transported in the first
direction whereby the spacing of first indicia in the first direction relative
to the
leading and trailing edges can be adjusted while the sheet is being
transported.
In accordance with a further aspect of the present invention, there is
provided a process for registering indicia and lines of termination in a
moving
sheet, said process comprising the steps of providing a generally planar
sheet; transporting said sheet in a first direction at a predetermined first
velocity; applying indicia to said sheet from a printer movable relative to
said
sheet at a sf~cond velocity imparting lines of termination to said sheet from
a
blade mova~~le relative t~o aaid sheet at a third velocity said lines of
termination
being spaced apart from said indicia in a predetermined spacing, and varying
one of said :>econd or third velocities to maintain said predetermined
spacing,
and preferably varying said velocity of said movable blade, and wherein said
first velocity remains constant.
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5a
BRIEF l:)E:SCRIPTION OF THE DRAWINGS
Figure 1 is a graphical representation of cumulative error in spacing
between indicia and lime;~ of termination in discrete length table napkins
(bottom absicca) and rolls of paper toweling (top absicca).
Figure 2 is a fragmentary top plan view of a sheet according to the
present invention, the sheet being part of a web having at least two roll
positions.
Figure 3 is a schematic perspective view of an apparatus according to
the present invention having control signals designated by a dashed line and
mechanical connections designated by solid lines.
DETAILED DESCRIPTION OF THE DRAWINGS
Referring to Figure 2, the sheet 14 according to the present invention is
generally planar, soft and absorbent. The sheet 14 is suitable for use in
application, :,uch as toilet tissue, paper toweling, placemats, napkins, etc.
The sheet 1~1 is preferably wound in roll form. The sheet 14 is cellulosic,
and
preferably paper. Sheets according to the present invention may be made
according to commonly assigned U.S. Patents 4,191,609 issued March 4,
1980 to Trokhan; 4,6;:.7,,859 issued January 20, 1987 to Trokhan; and
5,245,025 issued September 14, 1993 to Trochan et al.
As illustrated by the foregoing patents, the sheet 14 is preferably
manufactured in a continuous process, then later cut into discrete units
according to how the final product will be distributed to the consumer.
Discrete units include roll products (such as paper toweling and bath tissue)
and individual sheets (suc;h as table napkins). The sheet 14 is presented to
the consumer as an individual unit having a sheet length.
The product is preferably presented to the consumer in roll form,
wound in a spiral about a core to yield a core wound paper product. The core
wound paper product f~nas a length taken in the principal, or first direction.
Indicia 30 and lines of termination 20 are disposed in spaced relation
throughout the sheet 14. The indicia 30 may be intermediate or straddle the
lines of termiination 20.
The length of a sheet 14 as its unfolded dimension taken in a first
direction. Tlhe first direction in coincident the machine direction of the
sheet
14 during its manufacture and while in continuous form. The first direction is
also the
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principal direction of the sheet length. Plies or layers making up the sheet
14
are not separated when determining its length.
The leading and trailing edges 16, 18 of the sheet 14 are defined by lines
of termination 20. The lines of termination 20 are the lines separating the
sheet
14, as presented to the consumer, into discrete units - if such separation has
not
been performed at the time of manufacture. Typical lines of termination 20
include both perforations 21 and chop-off cuts 22. Perforations 21 are lines
of
weakness which allow separation of the sheet 14 into discrete units by the
consumer as needed. Chop-off cuts 22 separate an individual sheet 14 from the
adjacent sheet 14 in the manufacturing process, or terminate one roll and
start
the succeeding roll in the manufacturing process. Coincident with each line of
termination is a leading edge and a trailing edge 16, 18 of the sheet 14, the
leading edge 16 being ahead of the trailing edge 18 in the manufacturing
process.
Preferably the lines of termination 20, particularly the perforations 21, are
oriented in the cross-machine direction and are transverse to the first
direction of
transport of the sheet 14. Alternatively, it will be recognized that lines of
termination 20 having a diagonal orientation or having any other spaced
relationship in the machine direction may be utilized.
Two longitudinal edges 28 connect the leading and trailing edges 16, 18.
The longitudinal edges 28 are oriented substantially in the longitudinal, or
first,
direction. While the embodiment in Figure 2 shows the longitudinal edges 28
being straight and parallel, and the leading and trailing edges 16, 18 being
straight and parallel, it will be recognized by one of ordinary skill that
depending
upon the arrangement used to cut the longitudinal edges 28 from the trim of
the
sheet 14, the longitudinal edges 28 need not be either straight or parallel as
shown in the preferred embodiment. Likewise, the leading and trailing edges
16, 18 need not be straight~and parallel as shown.
The sheet 14 is transported through the apparatus 10 by any suitable
means. Typically the sheet 14 is drawn through the apparatus 10 under tension.
Tension may be applied to the sheet 14 by winding it about a rotatable reel.
The
rotatable reel may be cylindrical and driven by an electric motor at a
predetermined angular velocity. A suitable electric motor is a direct current
synchronous motor delivering about 30 horsepower at 3000 rpm. A particularly
preferred motor is available from the Reliance Electric Co. of Cleveland, OH.
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7
Juxtaposed ~Nith the leading and trailing edges 18 of the sheet 14, and
generally oriented in a second direction which is within the plane of the
sheet 14
and generally orthogonal to the first direction are indicia 30. The indicia 30
are
spaced from the lines of termination 20 so that a spaced relationship is
formed
therebetween. The space relationship is predetermined and may be adjusted
during manufacture. The indicia 30 may be aesthetically pleasing and printed,
either in a single color or in a plurality of colors. Alternatively, the
indicia 30 may
be embossed.
Preferably the indicia 30 are applied to the sheet 14 while it is being
transported through the apparatus 10 described below. The indicia 30 may be
applied to the sheet 14 by any means known in the art suitable for applying
spaced indicia 30~ at predetermined repeating intervals. In a preferred
embodiment, the indicia 30 are printed onto the sheet 14 from a rotatable
cylinder. The rotatabie cylinder is driven about a central axis at a
predetermined
angular velocity. Suitable printing processes known in the art include gravure
printing and flexographic printing. A suitable apparatus 10 for applying the
indicia 30 to the substrate is disclosed in commonly assigned patent 5,213,037
issued May 25, 1993 to Leopardi, II,
The print cylinder 34, or' other means for applying the indicia 32 to the
sheet 14, may be driven by army suitable means, such as an electric motor. A
suitable electric motor is a direct current synchronous motor delivering about
25
- 125 horsepower at a predeterrruned angular velocity of 1700 to 1800 rpm.
If it is desired to emboss the indicia 30 onto the sheet 14, any embossing
technique welt known in the art is suitable. Suitable embossing techniques
include those described in commonly assigned U.S. Patents 3,414,459 issued
December 3, 1968 'to Wells; 3,556,907 issued January 19, 1971 to Nystrand;
and 5.294,475 issued March 15, 1994 to McNeil.
In an altemat'rve embodiment, the indicia 30 may impart functional
properties to the sheet 14 rather than visual or aesthetically pleasing
properties.
In such an embodiment, the indicia 30 may comprise adhesive, as, for example,
would be used to join two plies together to form a sheet 14 having a double
thickness. Alternatively, functional indicia 30 can be used to change
properties
at one portion of the sheet 14 relative to another portion of the sheet 14.
For
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8
example, adhesives used to joi;~ the tail of a core wound product to the
periphery
of the product may be applied to the sheet 14, as well as adhesive used to
join
the leading edge of a sheet 14 to the core about which the sheet 14 is wound.
Alternatively, known additives which increase the softness, wet strength,
temporary wet strength, hydrophobicitylhydrophilicity, or which functionally
affects any other property of the sheet 14 may be applied thereto. A device
which may be used in intermiktent operation and suitable for applying
functional
indicia 30, such as adhesive, to the sheet 14 is disclosed in commonly
assigned
U.S. Patent 5,143,776 issued September 1, 1992 to Givens,
Typically the means for applying the indicia 32 need only have the
capability of applying the indicia 30 in spaced apart relationship .in the
first
direction and to apply the indicia 30 at a frequency yielding indicia 30 at
predetermined repeating intervals. The indicia 30 may be applied by any
suitable system. A suitable system comprises a rotatable cylinder, driven to
rotate about a central axis.
In addition to indicia 30 applied at repeating intervals spaced apart in the
first direction and in spaced relationship to the lines of termination 20,
indicia 30
may be juxtaposed with one or both of the longitudinal edges 28. If each of
the
leading, trailing and longitudinal edges 28 have indicia 30 juxtaposed
therewith,
a border is formed in the sheet 14. This border can define and enhance the
appearance, or functionality, of the sheet.
Referring to Fig. 3, the fines of termination 20 may be applied by any
suitable means for imparting lines of termination 20 to the sheet 14. The
suitable means must also apply the lines of termination 20 at a frequency
which
yields predetermined repeating intervals, As noted above, the lines of
tem~ination 20 may totally separate the continuous sheet into discrete units,
or
may provide lines of weakness, such as perforations 21. Suitable means for
imparting the lines of termination 20 include blades which are generally
orthogonal to and impart lines of termination 20 generally orthogonal to the
first
direction of transport: of the sheet 14, and which define adjacent leading and
trailing edges 18 of successive sheets 14.
A suitable means for imparting the line of termination comprises a rotatable
blade 36 driven about a central axis at a predetermined angular velocity on a
perforator roil. Of course, one or more rotatable blades 36 may be driven on a
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9
common shaft, as. is well kno~Nn in the art. A rotatable blade 36 suitable for
imparting perforatuons 21 to the sheet 14 is disclosed in commonly assigned
1;.~. Potent 5.114.,771 issued May 19, 1992 to Ogg et a(,
If the line of termination is the chop-off, it may be accomplished by two
rotatable rolls juxtaposed together, a chop off roll and a bed roll 48, as is
well
known in the art. Of course. even if the lines of termination 20 which are the
subject of the present invention are perforations 21, the apparatus 10 will
likely
still comprise a chop-off roll 46 and a bed roll 48 to separate adjacent
sheets,
each having a plurality of perforations 21. A particularly preferred
embodimerit
of chop off and bed rolls 48 is disclosed in commonly assigned patent
4,919,351
issued April 24, 1990 to McNei~, .
The rotatable~ blade 38, or other means for imparting the lines of
termination 20 to the sheet, may also be driven by any suitable means, such as
an electric motor, as set forth above. If both a perforator blade and chop-off
blade are used in the apparatus 10, they may be driven by independent motors,
or by a common motor.
Generally two types of rnotors are used with the present apparatus 10.
The first type of motor is described above. This type comprises one or more
draw or drive motors which impart angular velocity to one or more rotatable
components of the apparatus 10. This first type of motor is generally more
powerful and coarser in adjustment than the second type of motor. The first
type of motor is connected to the rotatable component through a differential
50.
Generally, the draw or drive motors) also transport the sheet 14 through the
apparatus 10, due to the angular velocity imparted to the sheet 14 by the
rotatable components of the apparatus 10.
The differential 50 comprises a mechanical drive capable of altering the
angular velocity of the output shaft 52 within a resolution of at least 0.001
percent of the baseline angular velocity of the output shaft 52. Preferably
this
resolution is maintained over a range of ~, 4 percent of the baseline angular
velocity of the output shaft 52. 'typically, the output shafts 52 have an
angular
velocity of 200 to 1500 rpms. The differential 50 provides for angular
adjustment of less than 1 rpm.
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The differential 50 comprises an output shaft 52 coupled to the rotatable
component. The output shaft 52 rotates with respect to the cage 54 of the
differential 50, which houses and rotatably mounts the output shaft 52. A
suitable phasing differential 50 is supplied by Andantex, Inc. of Wanamassa,
New Jersey as a Model No. SA30 epicyclic unit.
The second type of motor is a correction motor, typically a servo-motor.
This second type of motor drives the cage 54 of the differential 50, so that
the
angular velocity of the cage 54 is superimposed with the angular velocity of
the
input shaft 51. Such superposition yields a very accurate and well controlled
angular velocity at the output shaft 52. The correction motors typically are
about
2 to 4 hp.
The correction motors can be precisely and accurately adjusted to a
particular angular velocity, independent of the angular velocity of the draw
or
drive motor. Moreover, as the angular velocity of the draw or drive motor
changes, compensation can be made by the correction motor as the sheet 14 is
being transported through the apparatus 10, without interruption of the
transport
of the sheet. Compensation can also be made as the sheet 14 is being
transported through the apparatus 10, and without interruption of the
transport of
the sheet, should web tension change, or should any other factor change the
spaced relationship between the lines of termination 20 and the indicia 30.
The lines of termination 20 and indicia 30 may be imparted and applied to
the sheet, respectively, in any desired order. However, the latter of the
lines of
termination 20 and indicia 30 to be imparted or applied to the sheet 14
constitutes the operation controlled by the apparatus 10 to maintain the
desired
spaced relationship therebetween.
By way of example, the indicia 30 are applied to the sheet. Then the lines
of termination 20 are imparted to the sheet. If the sheet 14 has both
perforations 21 and a chop-off cut, typically the perforations 21 are imparted
prior to the chop-off cut. In the above described system having the indicia 30
first applied, the desired spacing of the lines of termination 20 relative to
the
indicia 30 is achieved and maintained by adjusting the placement of the lines
of
termination 20, rather than by adjusting the placement of the indicia 30.
The apparatus 10 may particularly comprise a sheet length correction
motor 45. The sheet length correction motor 45 controls the angular velocities
of the perforator roll, chop-off roll 46 and bed roll 48. If the product is
supplied
CA 02250012 2003-04-29
as a core wound product, as for example is common with toilet tissue and paper
toweling, the sheet length correction motor 45 may further control the angular
velocity of the indexing turret and core loading functions of that turret. The
turret
winds the product onto the core and performs the other functions ancillary to
core winding, such as core loading onto the mandrel, applying adhesive to the
core, chop-off of the sheet, applying tail seal adhesive to the end of the
sheet,
etc.
A preferred system having a sheet length correction motor 45 is illustrated
in commonly assigned patent 4,687,153 issued Aug. 18, 1987 to McNeil. A
differential 50 is disposed functionally intermediate the sheet length
correction
motor 45 and the means for imparting the lines of termination 20 to the sheet.
The apparatus 10 further comprises a means for determining the position
of the means for imparting lines of termination 20 or the means for applying
indicia 30 to the sheet 14, whichever occurs later in the manufacturing
process.
A typical means for determining position is a position resoiver 38 linked to
the
rotatable blade 3fi, or other component, such as the print cylinder 34, to be
controlled in response to the error signal.
A suitable position resoiver 38 is capable of determining angular position
within at least 0.1 degrees. A preferred position resolver 38 has 4,096 poises
per rotation. A suitable position resolver 38 is available from the Reliance
Electric Co. of Cleveland, ~hio as Model No. MIN 57C360 and is typically
designated by the motor which drnres the rotatable component from which the
signal is taken. The resoiver may be used in conjunction with a resolver input
module, such as is available from Reliance Electric as Part No. M7N 57C411. If
desired, an encoder can be substituted for the position resolver 38, provided
one uses the appropriate control logic, as is well known in the art.
The apparatus 10 further comprises a means for sensing the position of
the indicia 30 to the sheet. Preferably the determination is made by sensing
the
difference in reflectance between the indicia 30 and the sheet.
Two such means for sensing position 40 should be provided. Preferably
the means are located on opposite sides of the sheet, at coincident locations
as
taken in the cross machine direction. Each such means determines the position
of the indicia 30 on its respective side of the sheet. The positions of the
indicia
30 are compared for skew, and cross machine direction skew is corrected as
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necessary, using means well known in the art such as cocking rolls or other
members which influence path length. For purposes of maintaining the desired
spaced relationship discussed above, the two positions of the indicia 30
sensed
on the opposite sides of the sheet 14 are averaged and a single position is
used
in generating the error signal.
Of course, the indicia 30 may not provide adequate contrast with the sheet.
In this case a registration mark 31 may be applied to the sheet 14 in register
with the indicia 30. If a registration mark 31 is applied to the sheet,
preferably it
is applied to the trim of the sheet. Trim refers to that portion of the sheet
14 at
the outboard edges, and which is later removed from the portion of the sheet
14
which is presented to the consumer. Since the trim is not presented to the
consumer, the registration mark 31 may be of any size and shape suitable for
indicating its position to the sensing means. Preferably the registration mark
31
is printed onto the sheet 14 by the same printing plate used to print the
indicia
30. In this manner the spacing of the registration mark 31 relative to the
indicia
30, or any part thereof, is known. Thus, the desired spacing of the indicia
30 relative to the lines of termination 20 is likewise known. The desired
spacing
may be zero, whereby the registration mark 31 (or portion of the indicia 30
detected by the sensing means) is coincident the lines of termination 20.
Alternatively, the registration mark 31 (or portion of the indicia 30 detected
by
the sensing means) may be offset in either direction from the lines of
termination
20.
The apparatus 10 may further comprise a signal comparator 44. The
signal comparator 44 is capable of subtracting two input signals to produce an
error signal. The first input signal to the signal comparator 44 is the actual
spacing between the indicia 30 (or the registration mark 31 ) and lines of
termination 20. This input signal may be provided in seconds, based upon the
distance between the indicia 30 and lines of termination 20 and the speed at
which the sheet 14 is transported through the apparatus 10. A suitable signal
comparator is a Reliance Electric AutoMax Processor Module comprising the
resolver photo eyes and resolver input cards.
The second input signal to the signal comparator 44 is the position of the
means for imparting tines of termination 20 to the sheet 14. The signal
comparator 44 subtracts the two input signals to yield an error signal. When
the
error signal exceeds a preset value, the apparatus 10 makes correction. The
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preset value is the desired spacing between the indicia 30 (or registration
mark
31 ) and lines of termination 20. Suitable preset values for use with the
present
invention are ~ 0.125 inches (for a total range of 0.25 inches), and
preferably ~
0.063 inches (for a total range of 0.125 inches) over the entire length of the
' sheet 14.
To make correction, the apparatus 10 activates the appropriate motor,
such as the sheet length correction motor 45. The appropriate motor adjusts
the
placement of the lines of termination 20 on the sheet, so that the lines of
termination 20 may be brought closer to or further from the indicia 30,
thereby
changing the spaced relationship therebetween. Such correction occurs while
the sheet 14 is being transported through the apparatus 10 and without
interruption of the transport. This moving correction is feasible because the
appropriate motor is adjusted while it turns at a predetermined angular
velocity.
In an alternative embodiment, the means for changing the spaced
relationship between the indicia 30 and the lines of termination 20 may be any
means which changes the path length of the sheet 14 between the means for
applying the indicia 32 and the means for imparting the lines of termination
20.
The path length of the sheet 14 may be changed by using an idler roll 60 which
moves in a direction having a component orthogonal to the machine direction,
as indicated by arrow 61, and preferably orthogonal to the path of the sheet
14
at the particular position of the idler roll 60. Suitable idler rolls 60 are
available
in well known tracking systems, and are available from the Fife Company and
the Mount Hope Company. Alternatively, the sheet path length may be changed
by deflecting the web 11 with air jets or other non-contacting means.
Another means for changing the sheet path length is to change the length
of the sheet 14 within the path. Using this means, the tension applied to the
sheet 14 (such as by the draw motor) is changed as the sheet 14 is transported
between the means for imparting the lines of termination 20 and the means for
applying the indicia 32. Sheet tension may be changed throughout this portion
of the apparatus 10, as is well known in the art, by using driven rolls at
positions
intermediate such means, or by constantly increasing the draw of the sheet 14
through the apparatus 10 (for example by using the draw motor).
Yet another means to change the spaced relationship between the indicia
30 and the lines of termination 20 comprises incrementally changing the
angular
velocity of either or both of the means for imparting the lines of termination
20 or
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14
the means for applying the indicia 32. This may be accomplished by discrete
adjustments to the phasing of such means on an as-needed basis, given the
instantaneous value of the error signal discussed above.
One of ordinary skill will recognize that any of the three foregoing means
for changing the spaced relationship between the indicia 30 and the lines of
termination 20 can be collectively considered as a means for changing the
phase of the lines of termination 20 relative to the indicia 30 or vice versa.
Such
change of phase is accomplished by changing the phase of one or both of the
means for imparting the lines of termination 20 or the means for applying the
indicia 32.
In operation, the sheet 14 is moved relative to the apparatus 10, preferably
by holding the apparatus 10 stationary and drawing the sheet 14 through the
apparatus 10 in the machine direction. The sheet 14 may be drawn through the
apparatus 10 with a motor driving any suitable roll or rolls which
frictionally
engage the sheet 14 as it is drawn through the apparatus 10. A draw motor is
typically used in conjunction with a draw correction motor for this purpose.
Preferably the first step performed by the apparatus 10 is to apply the
indicia 30 to the sheet. The indicia 30 may be applied by a rotatable print
cylinder 34 having a predetermined angular velocity, such as is used in
flexographic or gravure printing. The rotatable print cylinder 34 is
preferably
driven independently from the draw motor and draw correction motor used to
transport the sheet 14 through the apparatus 10. The indicia 30 may include
registration marks 31 which are later trimmed from the sides of the sheets.
The
registration marks 31, or a point on the indicia 30 which are presented to the
consumer, are optically detectable.
The second step performed by the apparatus 10 is detection of the indicia
30 (or registration mark 31). Detection is performed by a photocell 41, based
upon the difference in reflectance between the indicia 30 and the background.
For accuracy, the photocell 41 is preferably disposed just before the
rotatable
blade 36.
The third step performed by the apparatus 10 is to impart the tines of
termination 20 to the sheet. The lines of termination 20 are placed on the
sheet
14 in spaced relationship to the indicia 30. The spacing is in the first, or
machine direction. The lines of termination 20 are preferably perforations 21,
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but may be the chop-off cut 22. The lines of termination 20 are preferably
oriented in the cross machine direction.
The fourth step performed by the apparatus 10 is determination of the
position of the perforations 21, or other lines of termination 20. This
determination is made by knowing the position of the rotatable blade 36 which
imparts the perforations 21 to the sheet 14. The position of the rotatable
blade
36 is given by a resolver 38 which determines the position of the rotatable
blade
36, and hence the perforations 21 imparted by the rotatable blade 36.
The difference in position between the indicia 30 and the perforations 21 is
determined by a signal comparator 44. This difference constitutes an error
signal. If the difference exceeds, in either direction, a preset limit,
correction is
made.
Correction may be made by adjusting the angular velocity of the draw
correction motor, the sheet length correction motor 45, the rotatable blade
36, or
the rotatable print cylinder 34. Preferably the correction is made by
adjusting
the angular velocity of a sheet length correction motor 45. The sheet length
correction motor 45 controls the angular velocity of the rotatable blade 36
which
imparts the perforations 21, as well as the chop-off roll 46 and bed roll 48,
as
well as functions downstream of the apparatus 10.
Particularly, the correction is preferably done by adjusting the angular
velocity of the rotatable blade 36, relative to the velocity of the sheet.
This
angular velocity is increased or decreased, as needed, until the error signal
comes within the preset limit.
In a preferred embodiment, the sheet 14 according to the present invention
is presented to the consumer as a core wound or rolled paper product. Such a
product is suitable for use as paper toweling, placemats, etc.
The sheet 14 may have a length in the principal direction of at least 500
inches, preferably at least 700 inches, more preferably at least 900 inches,
and
most preferably at least 1100 inches.
Intermediate the lines of termination 20 which define the length of the
sheet, may be a plurality of lines of termination 20 which provide a fine of
weakness. Preferably such lines of weakness comprise perforations 21. The
perforations 21 may be spaced on a pitch of about 4.0 to 20 inches, with a
preferred pitch of about 4.5 to 14 inches, and a more preferred pitch of about
12.0 to 12.5 inches. The perforations 21 are generally oriented in the cross-
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16
machine direction, and are generally orthogonal to the direction of transport
of
the sheet 14 through the apparatus 10. Preferably, but not necessarily, the
perforations 27 extend throughout the width of the product, as measured
between the longitudinal edges 28 of the sheet.
In such an embodiment, the indicia 30 are maintained in spaced
relationship to the perforations 21. Preferably the indicia 30 are registered
between the perforations 21 and juxtaposed with both the leading and trailing
edges 18 of the sheet. In this manner, symmetry about the cross-machine
direction centerline of the sheet 14 is obtained. Optionally, indicia 30 may
be
registered with the longitudinal edges 28 of the sheet 14 so that symmetry
about
the machine direction centerline of the sheet 14 is also obtained.
Of course, it will be recognized by one skilled in the art that several sheets
according to the present invention may be made in parallel, by using multiple
roll
positions as is known in the art. In such a process, a single web 11 having a
width several times greater than the sheet 14 presented to the consumer is
transported through the apparatus 10. As used herein, a "web" comprises a
plurality of sheets integral with one another and simultaneously transported
through the apparatus 10 in parallel in the cross-machine direction.
The web 11 is later slit or cut, in the machine direction, into individual
sheets. Trim is also removed from the longitudinal edges 28 of the web 11, as
discussed above with respect to single sheet widths.
Multiple indicia 30 and multiple lines of termination 20 are imparted to the
sheet 14 in parallel across the width of the web 11. The web 11 is later slit
or
cut into individual sheets, as desired. Of course, it will be recognized by
one of
ordinary skill within such an embodiment, the means for sensing the position
40
of the indicia 30 on the sheet 14 will be in spaced relationship in the cross-
machine direction. If desired, one may add a plurality of additional means for
sensing the position 40 of the indicia 30 at intermediate positions across the
width of the web 11.
Of course, one of ordinary skill will recognize it may be desired to adjust
the cross-machine direction registration of the web 11. Misregistration of the
web 11 in the cross-machine direction causes skew in the aforementioned
spaced relationship. One may compensate for such skew by adjusting the path
length of the web 11, using means well known in the art. For example, bowed
rolls, curved axis rolls having fixed and variable radii of curvature, cocking
rolls,
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17
Mount Hope rolls, etc. may be used to change the path length of one portion of
the web 11, or even an individual sheet, relative to the balance of the web 11
or
sheet 14.
