U.S. patent application number 12/853361 was filed with the patent office on 2011-02-10 for digital printing device with improved pre-printing textile surface treatment.
This patent application is currently assigned to Kornit Digital Technologies Ltd.. Invention is credited to Uri DUSHY, Asaf KAPLAN, Eli KEDAR, Jacob MOZEL.
Application Number | 20110032319 12/853361 |
Document ID | / |
Family ID | 43302110 |
Filed Date | 2011-02-10 |
United States Patent
Application |
20110032319 |
Kind Code |
A1 |
KAPLAN; Asaf ; et
al. |
February 10, 2011 |
DIGITAL PRINTING DEVICE WITH IMPROVED PRE-PRINTING TEXTILE SURFACE
TREATMENT
Abstract
A digital printing machine prints textiles. The machine
comprises a wetting unit for wetting fabric to be printed prior to
printing, a printing head for printing on said fabric and a
flattening unit located between the wetting unit and the printing
head for exerting pressure on the fabric to flatten outwardly
extending fibers of the fabric after wetting and before printing.
The flattening provides a smoothed surface for digital
printing.
Inventors: |
KAPLAN; Asaf; (Moshav
Ein-Sarid, IL) ; KEDAR; Eli; (Beit-Dagan, IL)
; DUSHY; Uri; (Moshav Ein-Sarid, IL) ; MOZEL;
Jacob; (Kfar-Saba, IL) |
Correspondence
Address: |
MARTIN D. MOYNIHAN d/b/a PRTSI, INC.
P.O. BOX 16446
ARLINGTON
VA
22215
US
|
Assignee: |
Kornit Digital Technologies
Ltd.
Rosh HaAyin
IL
|
Family ID: |
43302110 |
Appl. No.: |
12/853361 |
Filed: |
August 10, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61245333 |
Sep 24, 2009 |
|
|
|
61272436 |
Sep 24, 2009 |
|
|
|
61232494 |
Aug 10, 2009 |
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Current U.S.
Class: |
347/101 |
Current CPC
Class: |
C09D 11/54 20130101;
D06P 5/001 20130101; D06P 5/30 20130101; D06P 5/2077 20130101; C09D
11/107 20130101; Y10T 428/24802 20150115; D06P 5/2083 20130101;
D06P 1/0096 20130101; B41J 2/2117 20130101; C09D 11/102 20130101;
D06P 5/02 20130101; B41J 11/06 20130101; B41J 3/4078 20130101; C09D
11/30 20130101; C09D 11/322 20130101; D06P 1/0032 20130101; B41J
2/2107 20130101; B41J 2202/03 20130101; D06P 5/2011 20130101 |
Class at
Publication: |
347/101 |
International
Class: |
B41J 2/01 20060101
B41J002/01 |
Claims
1. A digital printing machine for printing textiles, the textiles
comprising fabric woven within a plane, the fabric comprising
fibers extending outwardly from said plane, the machine comprising:
a. a wetting unit for wetting fabric to be printed prior to
printing; b. a printing head for printing on said fabric; and c. a
flattening unit for exerting pressure on said fabric to flatten
said outwardly extending fibers to said fabric after wetting and
before printing, thereby smoothing said fabric for printing.
2. The digital printing machine of claim 1; wherein said flattening
unit is located between said wetting unit and said printing
head.
3. The digital printing machine of claim 1; wherein said flattening
unit causes said outwardly extending fibers to stick to said
fabric.
4. The digital printing machine of claim 1, further comprising a
printing table assembly for bringing said fabric to be printed
under said flattening unit while said fabric is wet from said
wetting unit, thereby causing the fibers to stick to the
fabric.
5. The digital printing machine of claim 1, further comprising a
controller for coordinating relative motion between said printing
table-assembly and said flattening unit.
6. The digital printing machine of claim 1, wherein said flattening
unit comprises one member of a group consisting of a polymeric or
metal curtain, a metal or polymeric roller, an Air knife, a
Polymeric squeegee made of PVC, silicone, viton, polyurethane,
neoprene or Natural rubber, a thin flexible metal squeegee or a
brushing strip.
7. The digital printing machine of claim 1, wherein said flattening
unit is located on a side to be printed of said fabric.
8. The digital printing machine of claim 1, wherein said flattening
unit further comprising a pressure regulation mechanism for
regulating flattening pressure applied to said fabric.
9. The digital printing machine of claim 8, wherein said pressure
regulation mechanism for said fabric is one member of a group
consisting of a counter balance, adjustable mechanical spring and a
pneumatic adjustable pressure unit.
10. The digital printing machine of claim 1, wherein said fabric to
be printed is a garment.
11. The digital printing machine of claim 1, wherein said fabric is
a one member of the group consisting of felt, leather, suede,
fibrous materials, porous materials, materials having high surface
tension with the ink liquid, weaves, weaves of natural fibers,
weaves of synthetic fibers, weaves of natural and synthetic fibers,
weaves comprising mixtures of natural and synthetic fibers, weaves
comprising wool, cotton, linen or nylon.
12. The digital printing machine of claim 1, wherein said printing
head comprises a plurality of inkjet nozzles for performing digital
printing; wherein said inkjet nozzles further comprise a
drop-on-demand piezoelectric inkjet nozzle or a continuous
piezoelectric inkjet nozzle.
13. The printing machine of claim 1, wherein said printing machine
is a carousel.
14. The printing machine of claim 1, wherein said printing machine
is a matrix.
15. The printing machine of claim 1, further comprising additional
printing heads and/or additional flatting units and/or additional
wetting units.
16. The printing machine of claim 4, wherein said flattening unit
is releasably tensioned to press on said table for said
flattening.
17. A method of digital printing on fabric; comprising: a. wetting
said fabric; b. exerting flattening pressure on a surface to be
printed of said fabric after said wetting; and c. performing
digital printing on said surface of said fabric after said exerting
flattening pressure and whilst said fabric is still wet from said
wetting.
18. The method of claim 17, wherein said exerting flattening
pressure after said wetting is to an extent sufficient to cause
outwardly extending fibers of said fabric to adhere back to said
fabric, thereby to provide a smooth surface for printing.
19. The method of claim 18, wherein said printing is performed
while said fibers continue to adhere to said fabric.
20. The method of claim 17, further comprising adjusting said
flattening pressure in accordance with a type of fabric being
printed.
Description
RELATED APPLICATIONS
[0001] This application claims the benefit of priority under 35 USC
119(e) of U.S. Provisional Patent Application Nos. 61/245,333 and
61/272,436, both filed on Sep. 24, 2009, and of 61/232,494 filed on
Aug. 10, 2009. The contents of the above applications are hereby
incorporated by reference as if fully set forth herein.
FIELD AND BACKGROUND OF THE INVENTION
[0002] The present invention relates to a digital printing device
for printing and, more particularly, but not exclusively to a
digital printing device for printing on textile surfaces, with
pre-printing treatment to improve the textile as a printing
surface.
[0003] Digital ink jet printing employs a printing head having
several ink injectors, each injector applying one color, a
controller for coordinating relative motion between the printing
head and the printed substrate and for instructing the ink
injectors when and where precisely to inject ink. To speed up the
printing process, a digital printing system may comprise several
printing heads working concurrently, wherein a printing head may
comprise hundreds of injectors of the same color.
[0004] Digital printing on a textile is complicated as textile
fabrics are notoriously difficult surfaces for printing. Until
recently, screen-printing was the main way of printing on textiles,
as the textile surface was considered unsuitable for inkjet
printing. The fabrics, of which a garment is made of, are porous;
furthermore, they are made of layers of threads and holes greater
then one order of magnitude relative to the inkjet drops. This
attribute of the fabric causes large-scale absorption of drops into
the fabric body, especially in the case of dark fabrics, and thus
requires relatively large amounts of ink, which eventually cause
bleeding, smearing, paddling and feathering of the fabric.
[0005] USA patent application 2005-0179708-A1 discloses a
pre-printing assembly for wetting the substrate prior to printing.
This wetting sub-system typically comprises an array of spraying
nozzles that applies a wetting composition over the textile surface
to be printed. This wetting composition interferes with the
engagement of the ink with the material to be printed so as to
limit the spread of the ink over, or within, the material.
[0006] The above is useful for printing over materials that usually
cause the ink to smear and spread over the material, such as
fibrous materials, porous materials and other ink absorbing
materials, and materials having high surface tension with the ink
liquid.
[0007] US Provisional Patent Application by the present assignee,
which is co-filed with the present application and titled "Inkjet
compositions and processes for stretchable substrates" (Attorney
Docket No. 45698), discloses multi-part ink compositions and a
process for inkjet printing of color images on various stretchable
substrates such as colored and absorptive or impregnable materials.
The multi-part ink composition allows for immediate immobilization
of the ink droplets on the surface of the substrate before curing
and without pretreatment of the substrate. The process is
characterized by heightened efficiency in process time, ink and
energy consumption, and yields textiles having stretchable yet
durable, wash-fast and abrasion-fast high-resolution color images
printed thereon.
[0008] In some cases, particularly when printing on a dark garment
there is a need for printing a light background color before
printing a colored image. In such a case, an opaque white layer is
printed on the garment as an undercoat that covers exactly the dark
surface under the printed image and does not extend beyond the area
of the image to be printed by the color ink. The colored image is
then digitally printed over the undercoat. The undercoat may also
serve as white color or white highlight where needed.
[0009] Wetting may optionally be applied prior to printing of the
colored image if performed on white or light colored fabric.
[0010] A fabric generally consists of fibers, which are woven
together. The fibers of the weave tend to have smaller fibers
extending outwardly from the fibers of the weave. In inkjet
printing, drops of ink are jetted from printer nozzles to land at
specific points on the fabric. However the outwardly extending
fibers tend to intercept the drops along their paths so that drops
do not reach their precise targets, or not in their entirety. The
result is a blurring of the image.
[0011] As well as woven fabrics, non-woven fabrics such as felt
also have hairs which stand out from the plane of the fabric and to
which the same considerations apply.
SUMMARY OF THE INVENTION
[0012] The present embodiments thus provide a printing machine,
which causes outwardly extending fibers to stick to the fabric
before printing, and thereby provides a smoother plane for
printing. A flattening unit presses on the fabric of an item to be
printed to flatten the fibers of the fabric after wetting and
before printing. Such an operation of flattening after wetting and
before printing presses the extending fibers against the fabric and
keeps the extending fibers adhering to the fabric during printing
so that they no longer interfere with the paths of the ink drops.
Thus, the thin fibers no longer stand out from the fabric or catch
drops of ink on their way to the fabric. Such a process of pressing
may also have the effect of eliminating the need for ironing the
textile before printing.
[0013] According to embodiments of the present invention there is
provided a digital printing machine for printing textiles, the
textiles comprising fabric woven within a plane, the fabric
comprising fibers extending outwardly from the plane, the machine
comprising: [0014] a. a wetting unit for wetting fabric to be
printed prior to printing; [0015] b. a printing head for printing
on the fabric; and [0016] c. a flattening unit for exerting
pressure on the fabric to flatten the outwardly extending fibers to
the fabric after wetting and before printing, thereby smoothing the
fabric for printing.
[0017] In an embodiment, the flattening unit is located between the
wetting unit and the printing head.
[0018] In an embodiment, the flattening unit causes the outwardly
extending fibers to stick to the fabric.
[0019] Embodiments may comprise a printing table assembly for
bringing the fabric to be printed under the flattening unit while
the fabric is wet from the wetting unit, thereby causing the fibers
to stick to the fabric.
[0020] An embodiment may comprise a controller for coordinating
relative motion between the printing table-assembly and the
flattening unit.
[0021] In an embodiment, the flattening unit comprises one member
of a group consisting of a polymeric or metal curtain, a metal or
polymeric roller, an Air knife, a Polymeric squeegee made of PVC,
silicone, viton, polyurethane, neoprene or Natural rubber, a thin
flexible metal squeegee or a brushing strip.
[0022] In an embodiment, the flattening unit is located on a side
to be printed of the fabric.
[0023] In an embodiment, the flattening unit further comprising a
pressure regulation mechanism for regulating flattening pressure
applied to the fabric.
[0024] In an embodiment, the pressure regulation mechanism for the
fabric is one member of a group consisting of a counter balance,
adjustable mechanical spring and a pneumatic adjustable pressure
unit.
[0025] In an embodiment, the fabric to be printed is a garment.
[0026] In an embodiment, the fabric is a one member of the group
consisting of felt, leather, suede, fibrous materials, porous
materials, materials having high surface tension with the ink
liquid, weaves, weaves of natural fibers, weaves of synthetic
fibers, weaves of natural and synthetic fibers, weaves comprising
mixtures of natural and synthetic fibers, weaves comprising wool,
cotton, linen or nylon.
[0027] In an embodiment, the printing head comprises a plurality of
inkjet nozzles for performing digital printing; wherein the inkjet
nozzles further comprise a drop-on-demand piezoelectric inkjet
nozzle or a continuous piezoelectric inkjet nozzle.
[0028] In an embodiment, the printing machine is a carousel.
[0029] In an embodiment, the printing machine is a matrix.
[0030] An embodiment may comprise additional printing heads and/or
additional flatting units and/or additional wetting units.
[0031] In an embodiment, the flattening unit is releasably
tensioned to press on the table for the flattening.
[0032] According to a second aspect of the invention there is
provided a method of digital printing on fabric; comprising: [0033]
a. wetting the fabric; [0034] b. exerting flattening pressure on a
surface to be printed of the fabric after the wetting; and [0035]
c. performing digital printing on the surface of the fabric after
the exerting flattening pressure and whilst the fabric is still wet
from the wetting.
[0036] In an embodiment, the exerting flattening pressure after the
wetting is to an extent sufficient to cause outwardly extending
fibers of the fabric to adhere back to the fabric, thereby to
provide a smooth surface for printing.
[0037] In an embodiment, the printing is performed while the fibers
continue to adhere to the fabric.
[0038] An embodiment may comprise adjusting the flattening pressure
in accordance with a type of fabric being printed.
[0039] Unless otherwise defined, all technical and scientific terms
used herein have the same meaning as commonly understood by one of
ordinary skill in the art to which this invention belongs. The
materials, methods, and examples provided herein are illustrative
only and not intended to be limiting.
[0040] The word "exemplary" is used herein to mean "serving as an
example, instance or illustration". Any embodiment described as
"exemplary" is not necessarily to be construed as preferred or
advantageous over other embodiments and/or to exclude the
incorporation of features from other embodiments.
[0041] The word "optionally" is used herein to mean "is provided in
some embodiments and not provided in other embodiments". Any
particular embodiment of the invention may include a plurality of
"optional" features unless such features conflict.
[0042] Implementation of the method and/or system of embodiments of
the invention can involve performing or completing selected tasks
manually, automatically, or a combination thereof.
BRIEF DESCRIPTION OF THE DRAWINGS
[0043] The invention is herein described, by way of example only,
with reference to the accompanying drawings. With specific
reference now to the drawings in detail, it is stressed that the
particulars shown are by way of example and for purposes of
illustrative discussion of the preferred embodiments of the present
invention only, and are presented in order to provide what is
believed to be the most useful and readily understood description
of the principles and conceptual aspects of the invention. In this
regard, no attempt is made to show structural details of the
invention in more detail than is necessary for a fundamental
understanding of the invention, the description taken with the
drawings making apparent to those skilled in the art how the
several forms of the invention may be embodied in practice.
[0044] In the drawings:
[0045] FIG. 1 is a schematic diagram illustrating a digital
printing machine with a wetting unit, a flattening unit and a
printing head, according to a first embodiment of the present
invention.
[0046] FIG. 2a is a schematic diagram of an exemplary printing
machine with a roller-flattening unit according to a further
embodiment of the present invention.
[0047] FIG. 2b is a schematic diagram of an exemplary printing
machine with a curtain-flattening unit, according to a further
embodiment of the present invention.
[0048] FIG. 3 is a schematic diagram of an exemplary
carousel-printing machine using a flattening unit according to an
embodiment of the present invention.
[0049] FIG. 4 is a schematic diagram of an exemplary
matrix-printing machine using a flattening unit, according to an
embodiment of the present invention.
[0050] FIG. 5 is a schematic diagram from the side, of a printing
machine comprising a wetting unit, a roller type flattening unit
and a printing unit.
[0051] FIG. 6 is a simplified flow chart describing an exemplary
printing procedure for printing on a dark garment using a digital
printing machine with a flattening unit according to an embodiment
of the present invention.
[0052] FIG. 7 is a schematic side view of a digital printing
machine comprising an exemplary flattening unit in operative
state.
[0053] FIG. 8 is a schematic side view of an exemplary digital
printing machine comprising an exemplary flattening unit in
non-operating state.
[0054] FIG. 9 is a schematic view of an exemplary flattening unit
in operative state.
[0055] FIG. 10 is a schematic view of an exemplary flattening unit
in non-operative state.
[0056] FIG. 11 is a close up view of an exemplary digital printing
machine comprising an exemplary flattening unit in operative
state.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0057] The present embodiments thus provide a digital printing
machine for textiles, that presses and flattens the face of the
fabric to be printed after wetting and before printing, when the
fabric is still wet from the wetting process. Pressing causes
uniform spread of the wetting solution and the outwardly extending
fibers of a textile fabric to adhere to the fabric through surface
tension due to the wetting, which adhering lasts until printing.
Pressing may be provided by a flattening unit. The flattening unit
applies or exerts mechanical pressure on the fabric to flatten the
fibers of the fabric after wetting and before printing. Adhering
the fibers to the fabric at this stage may eliminate the need for
ironing the textile before printing.
[0058] The principles and operation of an apparatus and method
according to the present invention may be better understood with
reference to the drawings and accompanying description.
[0059] Before explaining at least one embodiment of the invention
in detail, it is to be understood that the invention is not limited
in its application to the details of construction and the
arrangement of the components set forth in the following
description or illustrated in the drawings. The invention is
capable of other embodiments or of being practiced or carried out
in various ways. Also, it is to be understood that the phraseology
and terminology employed herein is for the purpose of description
and should not be regarded as limiting.
[0060] Reference is now made to FIG. 1 which is a schematic diagram
illustrating a digital printing machine with a flattening unit
according to embodiments of the present invention.
[0061] According to embodiments of the present invention, there is
provided a digital printing machine 100 for printing textiles. The
textiles may comprise garments or other textile items made of
fabric woven within a plane, the fabric itself comprising fibers
extending outwardly from the plain. The fabric may be based on any
conventional or unconventional textile material. The fabric may for
example comprise felt, leather, fibrous materials, porous
materials, materials having high surface tension with the ink
liquid, weaves of natural and synthetic fibers, weaves of mixtures
of natural and synthetic fibers, natural fibers including wool,
cotton, linen and synthetic fibers including nylon or suede. The
fabric is essentially planar with smaller fibers, hairs, extending
outwardly from the plane. The machine comprises a wetting unit 101
for wetting an item to be printed prior to printing. Wetting is
performed for ink drop immobilization, thus limiting the
penetration of the ink into the depth of the fabric, which may
cause dull coloring of the garment, mixing of colors and
blurring.
[0062] A printing head 103 prints on the item to be printed. A
printing head comprises at least one inkjet nozzle (not shown). The
printing head can be any conventional printing head, such as those
marketed by Spectra, Inc., New Hampshire, USA, and others known in
the industry.
[0063] When using conventional ink-jet type printing on textile
without the use of the present embodiments, the outwardly extending
fibers intercept the drops from the nozzle before they arrive at
their intended destinations, as discussed above.
[0064] Pressing or flattening unit 102 may be located between
wetting unit 101 and printing head 103, though other locations are
possible. Pressing or flattening unit 102 exerts mechanical
pressure on the item to be printed to flatten the outwardly
extending fibers to the fabric after wetting and before printing.
Flattening unit 102 may employ static pressure. Flattening unit 102
may be disengaged from the item to be printed (not shown) after
flattening has been completed. The pressure of flattening unit 102
on the fabric, after wetting and before printing, causes the
extending fibers or hairs to bend back towards the fabric before
printing. The water from the wetting unit provides the fabric and
the fibers with enough liquid to keep the outwardly extending
fibers to temporarily remain stuck to the fabric. The fibers
sticking to the fabric render the fabric as a smoother surface for
printing without any interference of outwardly extending
fibers.
[0065] Flattening unit 102 may be any construction that
mechanically presses the fibers to the fabric as the fabric passes
the unit. Flattening unit 102 may be implemented using for example
a downwardly pressing curtain such as a PVC curtain, a mechanical
roller such as a metal or polymeric roller, an Air knife, a
squeegee, including for example a polymeric squeegee such as PVC or
Natural or artificial rubber, silicon and, a thin flexible metal
squeegee, a brushing strip and the like. Flattening unit 102 may
replace the ironing unit (not shown), since there may be no need to
iron the fabric. Flattening unit 102 may be adjusted before
flattening for achieving a desired level of pressure. For example,
different types of fabric or different levels of wetting may
require different levels of pressure. Such pressure adjustment may
be performed by using a counter balance (not shown), adjustable
mechanical spring (not shown) or by pneumatic pressure adjustment
(not shown).
[0066] The item to be printed (not shown) may be a garment or any
other fabric, such as leather or suede.
[0067] Printing head 103 comprises an array of inkjet nozzles for
performing digital printing. The inkjet nozzles may comprise a
drop-on-demand piezoelectric inkjet nozzle or a continuous
piezoelectric inkjet nozzle. Additional heads may provide
post-printing and may comprise, a curing unit for curing ink, an
ironing unit for ironing the item to be printed, or a heat press.
The curing unit may be an infrared curing unit, a hot air blowing
curing unit or a microwave-curing unit. Printing machine 100 may
comprise an external head for stencil printing.
[0068] Printing machine 100 may comprise a printing table (not
shown) for holding the items to be printed. Printing machine 100
may be a carousel, a matrix, or any other printing machine, as will
be discussed in greater detail below.
[0069] Machine 100 may comprise additional printing heads and/or
additional flatting units and/or additional wetting units.
[0070] Machine 100 may comprise a controller for coordinating
relative motion between the table assembly (not shown) and the
flattening unit 102.
[0071] FIG. 2a is a schematic diagram of an exemplary printing
machine with a roller-flattening unit. Printing machine 200
comprises a wetting unit 201, a flattening unit 202, and a printing
head 203. Flattening unit 202, according to the exemplary diagram,
is a roller, which is capable of exerting pressure on the item to
be printed to flatten outwardly extending fibers to the fabric
after wetting and before printing. In the exemplary diagram, the
flattening unit is located before the printing head and after the
wetting unit, though the units may be arranged in a different
order.
[0072] FIG. 2b is a schematic diagram of an exemplary printing
machine with a polymeric or metal curtain-flattening unit. Digital
printing machine 300 comprises a wetting unit 301, a flattening
unit 302 and a printing head 303. Flattening unit 302 comprises a
polymeric, silicone, polyethylene or metal curtain, which
mechanically pushes downward on passing fabrics, thus exerting
mechanical pressure on the item to be printed to flatten outwardly
extending fibers to the fabric after wetting and before printing.
In the exemplary diagram, the flattening unit is located before the
printing head and after the wetting unit, though the units may be
arranged in a different order.
[0073] Reference is now made to FIG. 3, which is a schematic
diagram of a carousel-printing machine 46 in which one of the
stations 47 is a wetting and flattening unit which includes a
flattening unit 50 according to an embodiment of the present
invention. The garment printing apparatus 46 comprises other
stations such as a stencil-printing station 24, and digital
printing station 25. A combination of stencil printing and digital
printing may be used for printing a background color on the garment
before performing the digital printing.
[0074] The wetting apparatus, which is part of digital printing
station 47, comprises a wetting unit 48 comprising sprinklers and a
tank part 49. The wetting unit may spray a wetting and immobilizing
solution onto the textile or garment.
[0075] In use, a garment is placed on one of a series of printing
trays, which go around the carousel and stop at stations as needed.
At each station, the printing trays go through the process being
offered at that station. In the case of wetting and flattening unit
47, the garment undergoes wetting, and then is flattened using
flattening unit 50 and then the tray is moved onwards to digital
printing station 25 for printing while still wet and with the
fibers still adhering.
[0076] In an embodiment, for each printed garment, the stencil
printing, if executed, is executed first, flash cured if required
(not shown), then the wetting, then the flattening and then the
digital printing. The execution of the stencil printing is optional
and may be used for printing background colors or standard
images.
[0077] The digital printing can be performed at any application
stage, while following the digital unit a flash cure unit may be
used to dry the digitally printed image.
[0078] FIG. 4 is a schematic drawing of a matrix-printing machine
using a flattening unit, according to an embodiment of the present
invention
[0079] Matrix 600 is a matrix of printing stations set out in
linear manner so that a garment is placed on a tray and passes down
a row of stations to be treated with a series of pre-printing,
printing and post-printing functions. The matrix 600 features rail
601 which bears function head 623 and function head 622, rail 602
which bears function head 621 and function head 620, rail 603 which
bears function head 619 and function head 618, rail 604 which bears
function head 617 and function head 616, rail 605 which bears
function head 615 and function head 614 and rail 606 which bears
function head 612 and function head 613. Matrix 600 also features
rail 608 which bears printing table (tray) 627, rail 609 which
bears printing table (tray) 626, rail 610 which bears printing
table (tray) 625, and rail 611 which bears printing table (tray)
624.
[0080] In the exemplary diagram, function head 622 is a wetting
head and function head 620 is a printing head. Flattening unit 628
is located between wetting head 622 and printing head 620
underneath rail 601. In alternative embodiments, the units may be
arranged in a different order.
[0081] Printing table 624, in the exemplary diagram, is first fed
under wetting unit 622 for wetting the garment and then is fed
under flattening unit 628 while the garment is still wet, thereby
causing the fibers to stick due to surface tension. The table then
passes to printing head 620, where digital printing takes
place.
[0082] In the matrix, unit 622 could alternatively be a
screen-printing station, in which case the wetting and digital
printing units would be moved one station further along.
[0083] Reference is now made to FIG. 5, which is a schematic
diagram showing a view from the side of a textile-printing machine
according to the present embodiments. Printing machine 500
comprises a wetting unit 501, a roller type flattening unit 502,
and a printing head 503. A garment first passes the wetting unit
501, then is pressed when wet by the roller type flattening unit
502 and finally is printed under the printing unit 503, while the
area being printed is still wet from the wetting unit and the
fibers around the textile material still adhere to the underlying
fabric.
[0084] FIG. 6 is a simplified flow chart illustrating an exemplary
printing process for printing on a dark textile, using digital
printing machine with a flattening unit according to the present
embodiments.
[0085] As discussed above, when printing on a dark garment, a white
undercoat may be printed on the garment prior to printing the
image. In such a case, extensive wetting may be needed before
printing the white undercoat. Thus, when printing an opaque layer,
extensive wetting of the garment is performed before printing the
white undercoat. Referring now to the drawing of FIG. 6, a process
700 of wetting, flattening and printing is shown which is suitable
for dark colored backgrounds. In box 701, the garment is
extensively wetted by a wetting unit in order to limit absorption
of the ink by the fiber. In box 702, a flattening unit exerts
pressure on the item to be printed in order to flatten outwardly
extending fibers to the fabric after wetting and before printing.
In box 703, the opaque undercoat is printed. In box 704, digital
printing of the image on the wetted opaque layer is carried out by
expelling drops of ink from nozzles of the printing head to desired
points on the fabric, for example using the CMYK color system.
Since the fibers of the fabric have been flattened and are clinging
to the fabric surface, the fibers no longer intercept the ink drops
and the drops thus land where intended on the fabric, leading to
sharper printing.
[0086] FIG. 7 is a schematic side view showing in greater detail an
exemplary digital printing machine comprising an exemplary
flattening unit in operative state. Digital printing machine 700
comprises chassis 704, scan axis 703 and flattening assembly 706.
Scan axis 703 comprises a rail which is placed on chassis 704 and
provides the rail for bearing tray 705. Tray 705 is used for
holding an item to be printed (not shown). The enlargement 706
shows in greater detail the assembly of the flattening unit. The
exemplary flattening assembly comprises rigid arm 707 which applies
a constant pressure in the on state, elastic flattening unit 701
which may be made of rubber, wetting unit 702, as counterweight
708, which is here shown as a variable counterbalance to the weight
applied by the rigid arm 707 to regulate the applied pressure, and
the reversible attachment unit 711 that attaches or separates the
flattening unit from the printing substrate.
[0087] Construction 710 holds the wetting spray units 702. Rigid
arm 707 is attached to counterweight 708 which is here embodied as
a variable counterbalance. Regulated counterbalance 708 imposes a
required level of flattening pressure on flattening unit 701.
Reversible attachment unit 711 comprises a piston that brings the
flattening 701 squeegee into contact with the printing substrate
and detaches it after flattening. Counterbalance 708 regulates the
pressure on the flattening unit to press against tray 705 for
flattening and detaches the flattening unit from tray 705 after
flattening and before printing. Arm 707 of the flattening unit is
hinged in order to allow pressure regulation unit 708 to regulate
the weight applied to the garment. Attachment detachment unit 711
may transfer the pressure to the flattening unit when switched on.
Adjusting the pressure on flattening unit 701 may be done for
achieving a desired level of pressure. For example, different types
of fabric or different levels of wetting may require different
levels of pressure. Wetting unit 702 is used for wetting the item
to be printed (not shown) before flattening. Wetting may be done,
for example, by using water or acid solution optionally composed
with wetting additive. Flattening unit 701 is shown in operative
mode flattening the item to be printed (not shown) after wetting
and before printing.
[0088] The item to be printed then passes under printing unit 709
to be printed while the fibers still adhere to the fabric.
[0089] FIG. 8 is a schematic side view of an exemplary digital
printing machine comprising the exemplary flattening unit of FIG. 7
in non-operating state. FIG. 8 comprises the same units that are
described in FIG. 7. By means of 711 piston the tension from
counterweight 708 is released and flattening unit 701 and arm 707
are withdrawn from tray 705, and thus from the item to be printed
(not shown). The garment etc is able to travel to the printing unit
709 to print on the item to be printed after wetting and
flattening.
[0090] FIG. 9 is a view of an exemplary flattening unit in
operative state. All units shown in FIG. 9 are shown and described
in FIG. 7. Flattening unit 701 is operated by reversible attachment
unit 711, for example a pneumatic piston (on/off) that either
attaches or separates 701 flattening unit from the printed object,
in order to press on the item to be printed with the desired
flattening pressure and to release as required.
[0091] FIG. 10 is a schematic view of the exemplary flattening unit
of FIG. 9 in non-operative state. All units shown in FIG. 10 are as
shown and described in FIG. 9. Flattening unit 701 and arm 707 are
horizontal to the tray (not shown) and are detached from the tray
in order to enable the printing unit (not shown) to print on the
item to be printed after wetting and flattening.
[0092] FIG. 11 is a close up view of the exemplary digital printing
machine of FIGS. 9 and 10 comprising an exemplary flattening unit
in operative state. Flattening unit 701 presses down on the item to
be printed. FIG. 11 shows also sprinklers 702 being used for
wetting before flattening.
[0093] It is appreciated that certain features of the invention,
which are, for clarity, described in the context of separate
embodiments, may also be provided in combination in a single
embodiment. Conversely, various features of the invention, which
are, for brevity, described in the context of a single embodiment,
may also be provided separately or in any suitable sub
combination.
[0094] Although the invention has been described in conjunction
with specific embodiments thereof, it is evident that many
alternatives, modifications and variations will be apparent to
those skilled in the art. Accordingly, it is intended to embrace
all such alternatives, modifications and variations that fall
within the spirit and broad scope of the appended claims. All
publications, patents, and patent applications mentioned in this
specification are herein incorporated in their entirety by
reference into the specification, to the same extent as if each
individual publication, patent or patent application was
specifically and individually indicated to be incorporated herein
by reference. In addition, citation or identification of any
reference in this application shall not be construed as an
admission that such reference is available as prior art to the
present invention.
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