U.S. patent application number 10/441522 was filed with the patent office on 2004-11-25 for method of inkjet printing in high efficiency production of hygienic articles.
This patent application is currently assigned to The Procter & Gamble Company. Invention is credited to Salacz, Philipp Oskar Imre.
Application Number | 20040233241 10/441522 |
Document ID | / |
Family ID | 33299576 |
Filed Date | 2004-11-25 |
United States Patent
Application |
20040233241 |
Kind Code |
A1 |
Salacz, Philipp Oskar Imre |
November 25, 2004 |
METHOD OF INKJET PRINTING IN HIGH EFFICIENCY PRODUCTION OF HYGIENIC
ARTICLES
Abstract
Disclosed is a method of inkjet printing of tone and/or color
images at a high efficiency production of hygienic articles. The
method provides a reliable system of combining inkjet-printing
operations with converting operations on a converting line
producing hygienic articles having tone and/or color print images.
The method utilizes at least two-inkjet print heads capable of
switching between the print heads during malfunctions or
maintenance procedures of one of the print heads to provide
production continuity at a minimum production loss of hygienic
articles.
Inventors: |
Salacz, Philipp Oskar Imre;
(Baden-Wurtemberg, DE) |
Correspondence
Address: |
THE PROCTER & GAMBLE COMPANY
INTELLECTUAL PROPERTY DIVISION
WINTON HILL TECHNICAL CENTER - BOX 161
6110 CENTER HILL AVENUE
CINCINNATI
OH
45224
US
|
Assignee: |
The Procter & Gamble
Company
|
Family ID: |
33299576 |
Appl. No.: |
10/441522 |
Filed: |
May 20, 2003 |
Current U.S.
Class: |
347/12 |
Current CPC
Class: |
B41J 3/407 20130101;
B41J 3/543 20130101; A61F 13/15577 20130101 |
Class at
Publication: |
347/012 |
International
Class: |
B41J 029/38 |
Claims
1. A method of inkjet printing in a high efficiency production of
hygienic articles, having a print image, on a converting line
including at least two ink-jet print heads, the method comprising
the steps of: (a) providing a substrate moving in a web direction
at a first velocity; (b) printing on the substrate a first
plurality of images by a first inkjet print head disposed in
proximity to the substrate, the images being separated from each
other in the web direction at a pitch interval; (c) switching from
the first inkjet print head to a second inkjet print head while the
substrate continues its movement; and (d) printing on the substrate
a second plurality of images by a second inkjet print head disposed
in proximity to the substrate, the images being separated from each
other at the pitch interval, wherein the first plurality of images
is separated from the second plurality of images by an unprinted
region in the web direction, wherein the unprinted region is no
greater than 50 times the pitch interval.
2. The method of claim 1, wherein the unprinted region is no
greater than 10 times the pitch length.
3. The method of claim 1, wherein the unprinted region is no
greater than 1 time the pitch length.
4. The method of claim 1, wherein the step of switching further
comprises the steps of: a. initiating a second start signal to a
converter controller for starting the second ink-jet print head; b.
ceasing sending a first output signal from the converter controller
to the ink-jet controller; and c. sending a second output signal
from the converter controller to the inkjet controller.
5. The method of claim 1, wherein the step of switching further
comprises the steps of: a. ceasing sending a first OK signal from
the inkjet controller responding to a fail mode of the first inkjet
print head; b. ceasing sending a first output signal from the
converter controller to the ink-jet controller; and c. starting
sending a second output signal from the converter controller to the
ink-jet controller.
6. The method of claim 1, wherein the first velocity of the moving
substrate is at least 2 meters/second, at least 3 meters/second, at
least 4 meters/second, at least 5 meters/second, or at least 6
meters/second.
7. The method of claim 1, wherein the first inkjet print head or
the second ink-jet print head prints at least 600
images/minute.
8. The method of claim 1, wherein the substrate is a film, a
non-woven material, a woven material, a foam material, or any
combination thereof.
9. The method of claim 1, wherein the substrate is part of a
topsheet, a secondary topsheet, an insert, a backsheet, an
absorbent core, or any combination thereof.
10. The method of claim 1, wherein the hygienic articles are
feminine hygiene articles, baby diapers, baby pull-on articles,
baby swim articles, adult incontinence articles, and dining
bibs.
11. (Canceled)
12. (Canceled)
13. (Canceled)
Description
FIELD OF INVENTION
[0001] This invention relates to a method of inkjet printing in
high-efficiency production of hygienic articles having print
images.
BACKGROUND OF THE INVENTION
[0002] Hygienic articles, such as disposable absorbent articles,
including feminine hygiene articles, baby diapers, baby pull-on
articles, adult incontinence articles, and the like, including
images printed on inner and/or outer surfaces thereof have been
disclosed in a copending, commonly assigned U.S. application Ser.
No. 10/025,059, filed on Dec. 19, 2001, which is hereby
incorporated herein by reference.
[0003] The print images can be single-tone, multi-tone,
single-color, or multi-color. These images should be visible to the
consumer in order to provide the consumer with a variety of desired
benefits including improved aesthetics, product functional
benefits, or consumer awareness of how good the product is. For
example, a two-tone image, shown in FIGS. 1-3, emits a perception
of depth, which can be important for the consumer expecting
satisfactory liquid absorption and retention capabilities from the
product. The perception of depth indicates that although the
product is thin, the performance of the product will not be
compromised by the thinness.
[0004] The print images are generally provided by printing ink on
substrate materials by various printing methods, such as
flexographic printing, rotogravure printing, screen-printing,
ink-jet printing, and the like. Typically, the printing operations
are accomplished on high-speed printing lines, separately from the
converting lines that are dedicated to manufacturing disposable
absorbent articles. After printing on the printing lines, the
printed substrates are delivered to the converting lines, typically
in a form of continuous webs comprising printed images thereon.
However, the above practice of separately printing the substrates
off the converting lines typically requires additional cost
associated with handling, winding and unwinding, storing and
shipping of the substrates. In addition, the above steps can
negatively affect the quality of the printed substrate, resulting
in uneven and often excessive deformations of the wound layers of
the substrate inside the roll due to uneven distribution of the
compression forces inside the roll.
[0005] Furthermore, the separately printed substrates often require
special registration control methods to ensure proper phasing of
the printed images with the converting operations to effect a
desired and consistent positioning of the printed image in the
produced article.
[0006] However, combining the printing operations with converting
operations on the converting lines producing disposable absorbent
articles at a high-speeds and a high production efficiency can
result in substantial production losses, as overall efficiency of
the converting line is often compromised. This is due generally to
the multiplicity and complexity of the converting operations,
wherein any malfunction of any of the converting operations can
affect the performance of the printing operation, and vice versa,
any malfunction of the printing operation can affect the converting
operations. In addition, the printing operations often require
periodic maintenance procedures that can also affect the production
efficiency of the converting lines. Because converting lines can be
high-speed operations, producing hundreds or thousands of hygienic
articles per minute, any interruption of the production process can
result in substantial production losses.
[0007] Therefore, it would be beneficial to provide a reliable
method of combining printing operations with converting operations
on a converting line for high-efficiency production of hygienic
articles having print images.
SUMMARY OF THE INVENTION
[0008] The present invention can provide a method of inkjet
printing in a high efficiency production of hygienic articles,
having print images, on a converting line including at least two
inkjet print heads. The method includes the steps:
[0009] (a) providing a substrate moving in the web direction at a
first velocity;
[0010] (b) printing on the substrate a first plurality of images by
a first inkjet print head disposed in proximity to the substrate,
the images are separated from each other in the web direction at a
pitch interval;
[0011] (c) switching from the first inkjet print head to a second
inkjet print head while the substrate continues its movement;
and
[0012] (d) printing on the substrate a second plurality of images
by a second inkjet print head disposed in proximity to the
substrate, the images are separated from each other at the pitch
interval, wherein the first plurality of images is separated from
the second plurality of images by an unprinted region in the web
direction, wherein the unprinted region is no greater than 50 times
the pitch interval.
[0013] In another aspect of the invention, the unprinted region is
no greater than 10 times of the pitch interval. In yet another
aspect of the invention, the unprinted region is no greater that 1
time of the pitch interval.
[0014] In one aspect of the invention, the step of switching from
the first inkjet print head to a second inkjet print head can
include the following steps:
[0015] (a) initiating a second start signal by an operator to a
converter controller for starting the second inkjet print head;
[0016] (b) ceasing sending a first output signal from the converter
controller to the inkjet controller; and
[0017] (c) sending a second output signal from the converter
controller to the ink-jet controller.
[0018] In another aspect of the invention, the step of switching
from the first inkjet print head to a second inkjet print head can
include the following steps:
[0019] (a) ceasing sending a first OK signal from the inkjet
controller responding to a fail mode of the first inkjet print
head;
[0020] (b) ceasing sending a first output signal from the converter
controller to the inkjet controller; and
[0021] (c) starting sending a second output signal from the
converter controller to the inkjet controller.
[0022] In one aspect of the invention, the high efficiency
production of hygienic articles, having print images, on a
converting line including at least two inkjet print heads is at
least 60% efficiency. In another aspect of the invention, the high
efficiency production of hygienic articles, having printed images,
on a converting line including at least two inkjet print heads is
at least 70% efficiency. In yet another aspect of the invention,
the high efficiency production of hygienic articles, having print
images, on a converting line including at least two inkjet print
heads is at least 85% efficiency.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] While the specification concludes with claims particularly
pointing out and distinctly claiming the subject matter which is
regarded as forming the present invention, it is believed that the
invention will be better understood from the following descriptions
which are taken in conjunction with the accompanying drawings in
which like designations are used to designate substantially
identical elements, and in which:
[0024] FIG. 1 is a perspective view of an exemplary hygienic
article having a print image;
[0025] FIG. 2 is a plan view of the hygienic article of FIG. 1;
[0026] FIG. 3 is a plan view of an alternative embodiment of a
hygienic article;
[0027] FIG. 4 is an exemplary two-tone image shown as a gray scale
image;
[0028] FIG. 5 is the two-tone image of FIG. 4 shown as a pcx
image;
[0029] FIG. 6 is a magnification of a portion of the pcx image of
FIG. 5;
[0030] FIG. 7 illustrates a side-by-side comparison of various gray
scale and pcx scale images;
[0031] FIG. 8 is a simplified elevation view of one embodiment of
the method of the present invention designed to manufacture the
hygienic articles of FIGS. 1, 2 and 3, as well as any other
hygienic article defined herein;
[0032] FIG. 9 is a block diagram of one embodiment of the control
system of the method of present invention;
[0033] FIG. 10 is a block diagram of a switching logic between the
operating modes of the inkjet print heads according to the method
of the present invention;
[0034] FIG. 11 is a top view of a portion of a substrate having a
first plurality of images and a second plurality of images
separated by an unprinted region B from the first plurality of
images;
[0035] FIG. 12 illustrates a print image having a gray level A at a
resolution X;
[0036] FIG. 13 illustrates a print image having a gray level A at a
resolution X-30%; and
[0037] FIG. 14 illustrates a print image having gray level A+30 at
a resolution X-30%.
DETAILED DESCRIPTION OF THE INVENTION
[0038] The present invention will be described with respect to a
disposable absorbent article, having a multi-tone signal of at
least one color printed on a topsheet surface of the absorbent
article, disclosed in a copending and commonly assigned U.S. patent
application Ser. No. 10/025,059, filed Dec. 19, 2001. Specifically,
the present invention will be described with respect to a feminine
hygiene article disclosed in the above patent application. However,
the present invention can be applicable to any disposable absorbent
article having single-color and/or multi-color and/or single-tone
and/or multi-tone images printed on the outer and/or inner surfaces
to provide a variety of desired benefits including improved product
performance, product aesthetics, consumer awareness, consumer
perception, and the like.
[0039] Definitions
[0040] The term "hygienic article," "disposable absorbent article,"
or "absorbent article" refers herein to a device that normally
absorbs and retains fluids. In certain instances, the phrase refers
to devices that are placed against or in proximity to the body of
the wearer to absorb and contain the excreta and/or exudates
discharged from the body, and includes such personal care articles
as feminine hygiene articles, baby diapers, baby pull-on articles,
baby swim articles, adult incontinence articles, and the like. In
other instances, the phrase refers to protective articles, such as,
for example, dining bibs that have the ability to absorb food items
to prevent staining of the wearer's clothing. In still other
instances, the phrase refers to devices providing some therapeutic
benefit, such as, for example, pain relief, wound coverage or to
hold another device or article near the body.
[0041] The term "disposable" is used herein to describe products
which generally are not intended to be laundered or otherwise
restored or extensively reused in their original function, i.e.,
preferably they are intended to be discarded after several uses or
after a single use.
[0042] The term "substrate" is meant herein any material,
preferably in a form of a continuous web, suitable for printing an
image on at least one of the opposite surfaces thereof. The term
"substrate" can include a film (breathable or non-breathable), a
non-woven material, a woven material, a foam material, or any
combination thereof. The substrate can be a single layer or
multiple layers, comprising synthetic and/or natural materials. The
substrate can also include a dry lap material including wood pulp,
and the like, having a single layer or multiple layers.
Furthermore, the substrate can be part of any component of a
hygienic article, such as, for example, a topsheet, a secondary
topsheet, an insert, a backsheet, an absorbent core, or any
combination thereof.
[0043] The term "color" as referred to herein includes any primary
color, i.e., white, black, red, blue, violet, orange, yellow,
green, and indigo as well as any declination thereof or mixture
thereof. The term `non-color` or `non-colored` refers to the color
white which is further defined as those colors having an L* value
of at least 90, an a* value equal to 0+2, and a b* value equal to
0.+-.2. The color scale values utilized herein can be made with a
Hunter Color reflectance meter, a description of which can be found
in an article by R. S. Hunter, `Photoelectric color difference
Meter`, Journal of the Optical Society of America, Vol. 48,
pp.985-95, 1958. Devices specially designed for the measurement of
color on the Hunter scales are described in U.S. Pat. No. 3,003,388
to Hunter et al., issued Oct. 10, 1961.
[0044] The term "feminine hygiene article" refers herein to
sanitary napkins, panty liners, tampons, and incontinence articles
worn by women to absorb and contain menses as well as other vaginal
and incontinent exudates. Non-limiting examples of feminine hygiene
articles that can be provided with a multi-tone signal that
operates to create depth perception include those manufactured by
The Procter & Gamble Company of Cincinnati, Ohio as:
ALWAYS.RTM. Pantiliners with DriWeave.RTM. manufactured according
to U.S. Pat. Nos. 4,324,246; 4,463,045; and 6,004,893; ALWAYS.RTM.
Ultrathin Slender Maxi with Wings manufactured according to U.S.
Pat. Nos. 4,342,314, 4,463,045, 4,556,146, BI 4,589,876, 4,687,478,
4,950,264, 5,009,653, 5,267,992, and Re. 32,649; ALWAYS.RTM.
Regular Maxi; ALWAYS.RTM. Ultra Maxi with Wings; ALWAYS.RTM. Maxi
with Wings; ALWAYS.RTM. Ultra Long Maxi with Wings; ALWAYS.RTM.
Long Super Maxi with Wings; and ALWAYS.RTM. Overnight Maxi with
Wings, each aforesaid publication being incorporated by reference
herein.
[0045] The term "pitched unit operation" refers herein to any
device on a converting line, having a pitch-related function for
working one or more webs in the manufacture of disposable absorbent
articles. For example, the unit operation can include, but is not
limited to such pitched-related web-working devices as a cutting
device (e.g., a final knife), a discrete patch placing device
(e.g., a cut-and-slip unit, a cut and placement unit), an embossing
device having a pitched embossing pattern, a web activator device
(e.g., incremental-stretch activation devices disclosed in U.S.
Pat. No. 5,151,092 to Buell et al.; U.S. Pat. No. 5,156,793 to
Buell et al., and U.S. Pat. No. 5,518,801 to Chappell et al.), a
rotary printing device, and the like, all of which have in common
that they include a manufacturing cycle corresponding to a product
pitch length, which is the length of the product in a web form on a
converting line before the web is cut into individual products.
[0046] The term "efficiency" or "reliability" of a production
operation refers herein to a ratio, expressed in percents, of a
production output produced during a period of seven (7) consecutive
working days, 24 hours per day, to a theoretical production output
that could have been produced if there were no production outages
of any of the unit operations of the converting line due to
malfunctions, maintenance, and the like.
[0047] The term "high efficiency production" referrers herein to
the efficiency or reliability of a converting line producing
hygienic articles, wherein the efficiency of the converting line is
at least 60%, at least 70%, or at least 85%. The efficiency of the
converting line depends on the efficiency of each unit operation of
the converting line. For example, the efficiency of the printing
operation of the present invention is about 99.7%.
DESCRIPTION
[0048] FIG. 1 provides a perspective view of an absorbent article
10, which is presented herein in a form of a feminine hygiene
article. FIG. 2 provides a plan view of the absorbent article 10 of
FIG. 1. The absorbent article 10 herein has an upper surface or
user facing surface 13, a lower surface or garment facing surface
14, and a periphery 12. The absorbent article 10 comprises a
topsheet 25 having a viewing surface 28 facing upwardly towards the
upper surface 13. The absorbent article 10 further comprises a
backsheet 15 positioned oppositely to the topsheet 25. The
backsheet 15 is joined to the topsheet 25 preferably at least
partially at the periphery 12. The absorbent article 10 also
comprises an absorbent core 20 positioned between the topsheet 25
and the backsheet 15. In a preferred embodiment of the present
invention, the absorbent article 10 also includes a secondary
topsheet or an insert 26 positioned beneath the topsheet 25, i.e.,
at least partially, between the topsheet 25 and the absorbent core
20.
[0049] In the embodiment shown in FIG. 1 and in FIG. 2, the
absorbent article 10 has at least two portions, i.e., a colored
portion 40 and a non-colored portion 50. The colored portion 40 and
the non-colored portion 50 are viewable from the viewing surface 28
of the topsheet 25. The colored portion 40, which in a preferred
embodiment of the present invention is a print image 40, has at
least two shades: a first shade 42 and a second shade 44.
Preferably, but not necessarily, and as is shown in FIGS. 1 and 2,
the first shade 42 is positioned substantially within the second
shade 44. The second shade 44 is different, either in lightness,
darkness, and/or color, from the first shade 42. The multi-shades
operate to create a perception of depth within the absorbent
article by a user looking upon the viewing surface 28 of the
topsheet 25. In the embodiment shown in FIGS. 1 and 2, the first
shade 42 of the print image 40 is darker than the second shade 44
of the print image 40.
[0050] Alternatively, in another embodiment of the absorbent
article 10A, a print image or a colored portion 40A can comprise a
first shade 42A that is lighter than a second shade 44A, as shown
in FIG. 3. The lightness and darkness of the shades, whether two or
greater than two shades, are configured to create a perception of
depth by a user looking upon the viewing surface 28 of the
absorbent article 10A.
[0051] As described above, in one embodiment of the present
invention, the print image 40 can be the secondary topsheet or an
insert 26 positioned between the topsheet 25 and the absorbent core
20. In another embodiment, the colored portion 40 can form a part
of the topsheet 25. In yet another embodiment, the print image 40
can form a part of the absorbent core 20 whereby the print image 40
is viewable from the viewing surface 28 of the topsheet 25.
Alternatively, the printimage 40 can be a multi-layer insert
positioned beneath the topsheet 28.
[0052] Any topsheet material that allows the print image 40 to be
readily seen from the viewing surface 28 of the topsheet 25 is
suitable. For example, formed film materials, nonwoven materials,
or combinations thereof are suitable.
[0053] Alternatively to the color scale values described above, the
two-tone portions 40 and 40A can be shown as gray scale images. For
example, FIG. 4 illustrates a two-tone image 60 having a darker
portion 60A and a lighter portion 60B. The two-tone gray scale
images of the present invention were measured using Adobe
Illustrator.RTM. available from Adobe Systems Incorporated, the
headquarters of which is located in San Jose, Calif. In one
embodiment, the darker portion 60A was measured 45 on a gray scale
and a lighter portion 60B was measured 20 on a gray scale.
[0054] A gray scale image can be converted into a pcx image by
using Adobe Photoshop.RTM. also available from Adobe Systems
Incorporated. FIG. 5 shows an image 70 as a pcx image converted
from the gray scale image 60 of FIG. 4. Because a pcx image is
comprised of individual pixels and dots, the pcx image can be
useful in creating inkjet images, wherein each dot of a pcx image
represents an ink dot formed by an inkjet of a print head. FIG. 6
shows a magnified view of the image 70, wherein the darker portion
70A is composed of a greater number of dots than the lighter
portion 70B. For the reference purposes, FIG. 7 illustrates a
side-by-side comparison of several gray scale images having gray
scale values of 10, 25, 40, 55, 70, 85, and 100 to the
corresponding pcx images, where the gray scale value of a 100
represents a completely black image.
[0055] FIG. 8 is a simplified elevation view of one embodiment of a
method 100 of the present invention designed to manufacture the
absorbent articles of FIGS. 1, 2 and 3, as well as any other
absorbent articles defined above and having any desired print
image, including multi-colored, multi-tone, or multi-gray
images.
[0056] The method 100 includes an inkjet printing station 101
capable of printing a desired image on a substrate 102. The
substrate 102 can be any substrate according to the definition of a
substrate provided above. Also, as described above, the substrate
102 can form any component or part of a disposable absorbent
article 10. However, in the preferred embodiment of the present
invention, the substrate 102 is a nonwoven web for use as the
secondary topsheet or the insert 26, as shown in FIGS. 1 and 2.
[0057] The substrate 102 can be provided to the printing station
102 by any suitable means, such as, for example a metering device
104 (e.g., an omega roll or an s-wrap device), a series of idle
rollers 106 and 108, and a metering device 110 (e.g., a vacuum
conveyor). Both the metering devices 104 and 110 create a desired
tension in the substrate 102 and move the substrate 102 in a web or
machine direction 111 at a desired linear velocity V, which in the
high-speed production method of the present invention can be as
high as about 6 meters/second or even greater. However, the present
invention is applicable at any other linear velocity V of the
substrate, such as, for example, at least 5 meters/second, at least
4 meters/second, at least 3 meters/second, at least 2
meters/second, and lower (which occurs during a startup of the
converting line when the converting line speed, including the
linear velocity V of the substrate 102, is gradually increasing
from a zero to a desired production speed).
[0058] As shown in FIG. 8, the printing station 101 preferably
includes a dual-head arrangement comprising a first inkjet print
head 112 and a second inkjet print head 114, disposed at a spatial
distance 116 extending in the web direction 111. However, it should
be noted that the first and the second print heads 112 and 114
could be disposed from each other at any desired spatial
distance.
[0059] The first and the second print heads 112 and 114 can be any
type that is suitable to print a desired image, and are preferably
non-contact inkjet print heads disposed at a certain suitable
distance from the substrate 102, i.e., from the first surface 118
of the substrate 102, facing the print heads 112 and 114.
[0060] The print heads 112 and 114 can be preferably supplied by
ink provided by a common ink source; although, if desired, separate
ink sources can be also utilized.
[0061] Each of the print heads 112 and 114 includes a multiplicity
of jets dispensing a multiplicity of substantially uniform ink
dots. In one embodiment of the present invention, each of the print
heads 112 and 114 includes 256 jets, forming a linear configuration
of about 2 inches long (about 50.8 mm). Therefore, each of the
print heads 112 and 114 can print an ink image containing 256 ink
dots extending linearly about 50.8 mm across the substrate 102.
This arrangement is sufficient for printing any image of up to
about 50.8 mm wide, as measured across the substrate 102 and shown
as a width W of the printed images 40 and 40A in FIGS. 1-2 and 3,
respectively. However, any number of jets per a print head can be
provided, if desired, to print a desired width W of a desired
image, which, for example, for feminine hygienic articles of the
present invention can vary from 5 mm to 85 mm. For other types of
hygienic articles listed above, the width W of the print image can
vary even greater.
[0062] With respect to the print heads having 256 jets, such print
heads are available from Videojet Technologies, Inc., which offices
are located in Wood Dale, Ill. The printing station 101 can be a
part of an inkjet printing system that is also available from
Videojet Technologies, Inc., as the PrintPro.TM. inkjet print
system including an ink source and a controller for providing ink
and controlling jets forming individual ink droplets.
[0063] In the PrintPro.TM. inkjet print system, the ink droplets
are dispensed from all of the jets of the print heads 112 and 114
continuously, but only certain ink droplets are allowed to reach
the substrate 102 at desired locations to form a printed image. The
other ink droplets can be prevented from reaching the substrate 102
by deflecting the ink droplets into a recycling flow for a
continuous re-use. The operation of the individual ink jets of each
print head can be controlled by a controller included in the
PrintPro.TM. system.
[0064] Alternatively to the continuous type of the inkjet printing
system of one embodiment of the present invention, the inkjet
printing system can be an on-demand type inkjet printing system,
wherein ink typically is not recycled, and wherein ink droplets are
not formed continuously, but on the demand basis, in a desired
order, to print a desired image.
[0065] Referring again to FIG. 8, in the method of the present
invention, each of the first and the second print heads 112 and 114
is capable of printing the images 40 and 40A of FIGS. 1-2, and 3,
or any other desired image, separately from each other. For
example, when the first print head 112 is in a print mode (i.e., is
printing the image 40 on the substrate 102 at a desired location on
the substrate 102), the second print head 114 can be in a standby
or idle mode (i.e., is not printing the image 40 on the substrate
102). Conversely, when the first print head 112 is in a standby
mode, the second print head 114 is in a print mode, printing the
image 40. As described above, in both modes of operation, the print
mode and the standby mode, the droplet formation by each of the 256
jets of each of the print heads 112 and 114 occurs continuously;
however, in the standby mode, all of the dispensed droplets are
deflected and recycled into a recycled ink flow, but in the print
mode the un-deflected droplets are deposited on the substrate 102
and the deflected droplets are recycled into the recycle ink
flow.
[0066] In the method of the present invention, by switching from
the print mode of the first print head 112 to the print mode of the
second print head 114, and vice versa, a desired continuity of the
production process can be provided. The switching between the print
heads 112 and 114 enables continuous, uninterrupted production of
hygienic articles on a converting line when a print head needs to
be taken out of the print mode for any reason, including any type
of malfunction or scheduled maintenance, for cleaning and the like.
The second print head provides a desired back up by automatically
switching from a standby mode to a production mode.
[0067] This continuity is important to maintain a high production
efficiency of a converting line producing hygienic articles at high
production speeds, which, as described above, can be as high as 6
meters/second and greater, and at high production rates, which can
be at least 600 products/minute, in order to avoid production
losses, which, at such high speeds and production rates, can be
substantial. (It should be noted that the method of the present
invention is also applicable to any production rate, lower or
greater of at least 600 products/minute, as high as 3,000 products
per minute.)
[0068] It is important for the disposable absorbent articles of the
present invention, to have a print image disposed at a desired,
predetermined, and consistent location of hygienic articles.
Therefore, in the method of the present invention, when the first
print head 112 stops printing and the second print 114 starts
printing, the second print head 114 can print in the identical
location as did the first print head 112. Further, in one
embodiment of the present invention, the switching between the
print heads occurs simultaneously, with preferably a minimum loss
of production of hygienic articles during the switching. This
operation will be described in more detail below.
[0069] Referring again to FIG. 8, after the inkjet printing, the
substrate 102 travels to a cut and placement device 120, capable of
severing the substrate 102 into individual sheets comprising the
secondary topsheet 26 and then placing the secondary topsheets 26
at a desired pitch interval P onto a topsheet web 122 moving in a
web direction 124 at a desired velocity. The topsheet web 122 can
be provided and metered at a desired velocity by any suitable means
known to one skilled in the art. Then, an absorbent core web 126
(which can be also provided and metered by any suitable means) is
cut into individual absorbent cores 20, which are then placed onto
the secondary topsheet 26, previously disposed on the topsheet web
122. The cutting and placing operations of the absorbent core 20
can be provided by a cut-and-slip device 128 or any suitable web
cutting and placing device known in the art. Further, a backsheet
web 130 (which can be also provided and metered by any suitable
means) is deposited onto the cores 20 to provide a sandwiched-type
web 132, which is subsequently bonded together and cut into
individual hygienic articles 10 of the present invention. The
bonding, cutting, and placing operations of the sandwiched-type web
132 can also be provided by any suitable means known in the art,
for example, by a final knife 134. The individual articles 10 then
can be transported by any suitable means, such as a conveyor 136,
to other downstream operations, such as folding, wrapping, and
packing.
[0070] FIG. 9 illustrates a block diagram 200 of one embodiment of
the control system of the present invention. The diagram 200
includes the printing station 101 having the first inkjet print
head 112 and the second inkjet print head 114. The block diagram
200 also includes an ink-jet controller 211 for calculating the
deflection of each ink droplet of each of the 256 nozzles of each
of the print heads 112 and 114. The calculated information is then
transferred from the ink-jet controller 211 to the inkjet print
heads 112 and 114, using a first communication link 230 and a
second communication link 231, respectively. The inkjet controller
211 also receives information from a first encoder 202 with respect
to a converter speed reference (e.g., a linear velocity of the
moving substrate 102), which can be provided from any suitable
speed reference representing the speed of the substrate 102. In one
embodiment of the present invention, the speed reference 212 is
provided from the cut and placement device 120 via the first
encoder 202 connected to the cut and placement device 120. The
inkjet controller 211 further receives triggering information with
respect to the print heads 112 and 114, wherein each print head 112
and 114 has its own triggering signal, i.e., a first triggering
signal 215 and a second triggering signal 216, respectively.
[0071] With respect to controlling the first print head 112, as
shown in FIG. 9, the first triggering signal 215 is a result of
information calculated by a first calculation unit 222 receiving a
first start cycle signal 217 and a first output signal 219. The
first calculation unit 222 can be any suitable electronic device
capable of calculating a binary AND logic function, for example, an
opto-couple device and the like. The first start cycle signal 217
is provided by a second encoder 203, which in the preferred
embodiment of the present invention, is connected to the final
knife 134. However, the second encoder 203 can be connected to any
pitched unit operation defined above, including the cut and
placement device 120 that can be attached to both the first encoder
202 and the second encoder 203. The first output signal 219 is
provided from a converter logic controller 210 (referred
hereinafter as a converter controller 210). In order to provide the
first output signal 219, the converter controller 210 receives both
a first OK signal 225 and a second OK signal 226 from the inkjet
controller 211.
[0072] Similarly, with respect to controlling the second print head
112, as shown in FIG. 9, the second triggering signal 216 is a
result of information calculated by a second calculation unit 223
receiving a second start signal 218 and a second output signal 220.
The second calculation unit 223, similarly to the first calculation
unit 222, can be any suitable electronic device capable of
calculating a binary AND logic function. The second start cycle
signal 218 is provided by the second encoder 203. The second output
signal 220 is provided from the converter controller 210. In order
to provide the second output signal 220, the converter controller
210 receives both the first OK signal 225 and the second OK signal
226 from the inkjet controller 211. The first start cycle signal
217 and the second start cycle signal 218 are related to each
other, representing the spatial distance 116 between the respective
nozzles of the first and the second print heads 112 and 114. The
spatial distance 240 presents a portion of a single product cycle
corresponding to a cycle distance between the first and the second
print heads 112 and 114.
[0073] FIG. 10 shows a block diagram 300 illustrating logic for
switching between three operating modes of the first and the second
inkjet print heads 112 and 114, within the converter controller
210. The three operating modes of each of the print heads 112 and
114 are illustrated by three circles representing a standby or idle
mode 301, a run mode 302, and a fault mode 303.
[0074] In the standby mode 301, the first print head 112 or the
second print head 114 (or both print heads 112 and 114) are ready
for printing at any moment, while continuously forming and
re-circulating ink droplets into a recycled ink flow.
[0075] In the run mode 302, the first print head 112 or the second
print head 114 prints an image on the substrate 102. (As noted
above, in a preferred embodiment of the present invention, only one
of the print heads 112 or 114 can operate in the run mode 302 at
the time.) In both the standby mode 301 and the run mode 302, the
converter controller 210 receives the OK signal 215 or 216 and
sends the output signal 219 or 220 (see FIG. 9).
[0076] In the fault mode 303, the converter controller 210 does not
receive the OK signal 215 or 216 and does not send the output
signal 219 or 220 (see FIG. 9).
[0077] Referring to FIG. 10, from the standby mode 301, a print
head can switch to the run mode 302 by a transition 311 or to the
fault mode 303 by a transition 314. The transition 311 can happen
as a consequence of two different situations: (1) an operator
switching between print heads by initiating start signals 228 or
229 (see FIG. 9) for the first print head 112 or the second print
head 114, respectively, to the converter controller 210; or (2) the
transition 311 is an automated sequence happening immediately after
a transition 313 on the other print head, which switched from the
run mode 302 to the fault mode 303. With respect to the transition
314, it can also happen as a consequence of two different
situations: (1) an operator switching an idling print head to the
fault mode 303 when the idling print head needs maintenance, such
as cleaning and the like; or (2) an idling print head failing for
any reason, and, accordingly, not sending the OK signal 225 or 226
to the converter controller 210.
[0078] Referring to FIG. 10, from the run mode 302, a print head
can switch to the standby mode 301 by a transition 312, or to the
fault mode by a transition 313. The transitions 312 and 313 are
equal in priority, and, therefore, each one becomes executed
depending upon which of the transitions 312 or 313 occurs first.
The transition 312 can happen when an operator switches between the
print heads, and the transition 313 can happen when a print head
fails in the run mode 302 (i.e., does not send the OK signal 225 or
226 to the converter controller 210) and needs operator service.
When a print head fails in the run mode 302, the other, idling
print head, switches to the run mode 302 by the transition 311.
[0079] Referring to FIG. 10, from the fault mode 303, a print head
can switch only to the standby mode 301 by the transition 315. This
happens after a faulted print head has been serviced and is ready
for operation.
Operating Procedures
[0080] Referring again to FIGS. 9 and 10, below are described
various procedures for continuous operation of the first and the
second print heads 112 and 114.
[0081] At the start, the first and the second print heads 112 and
114 are preferably in the standby mode 301 controlled by the
converter PLC 210. When both print heads 112 and 114 are in the
standby mode 301, the inkjet controller 211 sends both OK signals
225 and 226 to the converter controller 210. Now the operator has
an option to select either one of the print heads 112 or 114 to
start printing by initiating the first start signal 228 for
starting the first print head 112 or the second start signal 229
for starting the second print head 114. If the operator selects to
start the first print head 112 by initiating the first start signal
228, the converter controller 210 sends the first output signal
219, which is combined with the first cycle start signal 217 in the
first calculation unit 222 sending the first triggering signal 215
to the inkjet controller 211 for starting the first print head 112.
During the printing by the first print head 112 in the run mode
302, the second print head 114 remains in the standby mode 301,
ready to be switched to the run mode 302 when needed. When the
first print head 112 is printing in the run mode 302 and the second
head 114 is in the standby mode 301, the inkjet controller 211 is
sending both the first and the second OK signal to the converter
controller 210.
[0082] When the first print head 112, becomes faulted, the inkjet
controller 211 switches the first print head 112 to the fault mode
303 and stops sending the first OK signal 225 to the converter
controller 211, which in response, stops sending the first output
signal 219 and starts sending the second output signal 220. The
second output signal 220 is then combined with the second start
cycle signal 219 in the second calculation unit 223 sending the
second triggering signal 216 to the inkjet controller 211 switching
the second print head 114 to the run mode 302.
[0083] Similarly, when the second print head 114, becomes faulted,
the inkjet controller 211 switches the second print head 114 to the
fault mode 303 and stops sending the first OK signal 225 to the
converter controller 211, which in response, stops sending the
first output signal 220 and starts sending the first output signal
219. The first output signal 219 is then combined with the first
start cycle signal 218 in the first calculation unit 222 sending
the first triggering signal 215 to the inkjet controller 211
switching the first print head 112 to the run mode 302.
[0084] Alternatively to the automatic switching between the print
heads described above when one of the print heads becomes faulted,
the operator can switch between the print heads any time when the
converter PLC is receiving both OK signals 225 and 226. For
example, when the first print head 112 is working in the run mode
302 and the second print head 114 is in the standby mode 301 (in
such condition, the converter PLC is receiving both OK signals 225
and 226 from the inkjet controller 210), and the operator can
switch the printing from the first head 112 to the second print
head 114 at any time by initiating the second start signal 229. In
this case, the converter PLC stops sending the first output signal
219 and starts sending the second output signal 220, which is then
combined with the second start cycle signal 219 in the second
calculation unit 223 sending the second triggering signal 216 to
the inkjet controller 211 switching the second print head 114 to
the run mode 302. When the converter PLC 210 stops sending the
first output signal 219 above, in response, the inkjet controller
210 stops receiving the first triggering signal 215 and stops
sending the first OK signal 225 to the converter PLC 210. This
manual switching between the print heads by the operator may be
needed when the operator needs to do any service procedure (e.g.,
cleaning and the like) to a print head working in the run mode 302.
Also, the operator may need to switch print head when there is a
need to change the printing image by loading a new data. Such
capability enables the operator to change a printing image "on the
fly" without interrupting the production process on the
converter.
[0085] FIG. 11 shows a top view of a portion of the substrate 102
having a first plurality 351 of images 40 and a second plurality
352 of images 40. In the first plurality 351 of images 40 and in
the second plurality 352 of images 40, the images 40 are separated
from each other at a pitch interval P, which is the length of a
hygienic article. The pitch interval P can very depending on a
particular hygienic article, for example, generally from about 100
mm to about 400 mm. Specifically, with respect to feminine hygienic
articles, the pitch interval P can vary from about 220 mm to about
320 mm. (As noted before, in the embodiments of the present
invention, the length and the width of the print image 40 can vary.
Specifically, with respect to feminine hygiene articles of the
present invention, the length L of the print image 40 can vary from
about 10 mm to about 300 mm and the width of the print image 40 can
vary from about 5 mm to about 85 mm. However, any desired length
and width of the print image 40 can be used in the present
invention.)
[0086] Referring again to FIG. 11, the first plurality 351 of
images 40 is separated from the second plurality 352 of images 40
by an unprinted region B. The unprinted region B represents a
portion of the substrate 102 having no print images 40 by the
method disclosed herein. (It should be noted that the unprinted
region B can include one or more print images, however, the quality
of the print image(s) may not be sufficient.) The unprinted region
B also represents a portion of the substrate 102 that moved in
relation to the printing station 101 (see FIGS. 8 and 9) during the
switching between the first and the second print heads 112 and 114,
or vice versa. In one embodiment of the present invention, the
blank space B is no greater than 50 times the pitch interval P, or
no greater than 10 times the pitch interval P, or no greater than 1
time the pitch interval P.
[0087] It should be noted that the first plurality 351 of images
and/or the second plurality 352 of images could include the same
image 40 or different images, wherein the different images, which
have been stored in the inkjet controller 211, can be printed on
demand at any desired sequence.
Overcoming Limitations of Printing Equipment
[0088] In addition to providing an efficient, uninterrupted
operation of two inkjet print heads on a converting line producing
hygienic articles, the method of present invention provides an
efficient connection between a product designing stage and a
product production stage, especially, for the instances having to
do with certain limitations of a particular printing equipment
utilized for printing inkjet images on the converting line. For
example, at high substrate speeds, and, especially, when not one
but several ink drops per a dot (i.e., several ink drops, composing
a dot, are deposited into a single pixel on the substrate surface)
are needed, certain printing equipment may not be capable of
printing ink drops at a required rate, resulting in a decreased
resolution of the printed image, and, thus, in a decreased visual
impression by a consumer viewing the image. The method of the
present invention provides compensation for such a decrease of the
visual impression by the consumer by adjusting the visual level of
the lower resolution image, as shown in FIGS. 12, 13, and 14.
[0089] FIG. 12 shows an inkjet print image 400 having gray level A
at resolution X, which, assumingly, for the purpose of explanation,
cannot be provided by a given printing equipment at a certain high
speed of a substrate. To overcome this speed limitation, the
resolution X of the image 400 of FIG. 12 can be stretched, for
example, 30% or any other suitable number. FIG. 13 illustrates a
print image 500 having the same gray level A as the original image
400 at a lower resolution, X-30%. It can be clearly seen by
comparing grids of FIGS. 12 and 13, that the grid of FIG. 13 is
longer in one direction in comparison to the grid size in FIG. 12
(in this case about 30%), and, thus, the density of inkjet drops in
FIG. 13 is less than the density of drops in FIG. 12, resulting in
a less intense visual impression for the consumer. To compensate
for the loss of the visual impression, more drops can be deposited
in vacant pixels of the stretched grid of FIG. 13, as shown, for
example, in FIG. 14, illustrating a print image 600 having a gray
level A+30 (which is greater than the original gray level A of the
original image 400 of FIG. 12) at a resolution X-30% (which is less
than the original resolution X of the original image 400 of FIG.
12). The modified image 600 of FIG. 14 provides a similar visual
impression on the consumer as compared to the originally designed
image 400 of FIG. 12, thus, overcoming the above described speed
limitation of the printing equipment.
[0090] While particular embodiments of the present invention have
been illustrated and described, it would be obvious to those
skilled in the art that various other changes and modifications can
be made without departing from the spirit and scope of the
invention. It is therefore intended to cover in the appended claims
all such changes and modifications that are within the scope of
this invention.
* * * * *