Note: Descriptions are shown in the official language in which they were submitted.
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LASER-ETCHED PULL TAB CONTAINER OPENING DEVICES AND
METHODS OF MAKING THE SAME
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present application relates to container opening devices and methods
ofmaking
the same. More particularly, the present invention relates to laser-etched
pull tabs and
methods of making the same.
2. Description of the Related TechnoloQy
Pull tab container opening devices have not been utilized by the food and
beverage
industry for package enhancement, brand identification, promotional, or
informational
purposes. Most existing pull tab designs only serve the function of allowing a
user to open
the container. In recent years, the industry has drifted towards an open, ring-
shaped
configuration for pull tabs. See U.S. Patent Des. 289,017 and U.S. Patents
4,465,204 and
4,530,631. These tabs are preferred not only because they have an aperture for
accepting
the finger of a user (which aids the opening process), but also because they
allow the
industry to use less material in producing the tabs. However, ring-shaped tabs
have proven
ineffective for accepting indicia thereon, (whether produced by ink jet
printing, stamping,
mechanical etching, or otherwise), due to the limited surface area of the tab.
To overcome the surface area problem, some prior artisans have attempted to
place
promotional pieces in the finger hole of prior art tabs but have had limited
success due to
the relative expense and slowness of such plug operations. See U.S. Patents
3,958,354 and
5,191,695.
Other artisans have attempted to use a closed-tab configuration to provide
additional
surface area for accepting promotional or decorative materials thereon. See
U.S. Patent
4,363,179. The prior art teaches that closed-end tabs can receive ink printing
to place
indicia on the tab, and denotes an ink jet printer loaded with a metal-
compatible ink as the
process. See Australian Patent 81794/94. As noted, printing onto a metal
surface requires
metal-compatible inks, and these are solvent-based inks. However, it is
impossible to use
these inks with an ink jet printer. The inherent heat and electrical controls
of the ink jet
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printer cause instability and combustion of the inks, and results in
destruction of the
equipment.
It is possible to use pressurized ink-sprayers of these solvent based inks,
but the
process lacks both predictability and permanence (see figure 3A and 3B).
Solvent-based
inks have a low co-efficient of friction and are easily moved by micro-air
currents during
their deposition and also easily move once applied to the metal substrate. The
inability to
repeatedly produce the same clear image on a small substrate is systemic in
the ink-spray
process.
Moreover, solvent-based inks, by their very nature, also easily removed from
most
substrates by everyday solvents. Taken in combination, counterfeiters could
easily remove
any contest-based indicia from a pull-tab and apply their own ink indicia in
place thereof;
making such contests impractical for ink-spray printed tabs. Accordingly, ink-
j et printing
using solvent-based inks is technically impossible and ink-spray printing has
proven not
only logistically and technically prohibitive but also unduly costly and of
limited utility.
As noted in Australian Patent 81794/94, it is also impractical to consider any
other
printing processes using inks or paints for the container tab or end. If
applied prior to
container tab or end forming, they are subject to break down by cracking or
peeling, and
will suffer image distortion during the subsequent forming operation. These
same inks or
paints could not be applied after the forming operation as both the container
tab and end are
a contoured surface and cannot be printed upon by other than an ink-spray
process, which
is subject to the severe limitations as noted above.
The foregoing underscores the problems associated with conventional prior art
tabs
and methods of decorating the same. Furthermore, the foregoing highlights the
long, yet
unresolved need in the art to provide an effective and cost efficient means of
providing
container opening devices having high definition and permanent indicia for
informational,
promotional or decorative purposes.
SUNINIARY OF THE INVENTION
The present invention overcomes the practical problems described above and
offers
new advantages as well. The present invention is based on the realization that
laser-etching
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pull tabs to a depth that ablates a portion of the tab substrate provides
consistent, high-
definition indicia which is surprisingly tamper-resistant and permanent.
In order to overcome the aforementioned deficiencies of the prior art,
Applicant
previously disclosed a method of providing coated tab stock in which
decorative,
promotional, or informative indicia is laser-etched thereon. For example,
Applicant's
previous applications: U.S. Serial No. 08/917,516, filed August 26, 1997 and
U.S. Serial
No. 09/061,227, filed April 17, 1998, which are hereby incorporated by
reference in their
entirety, teach laser-etching pull tabs in order to provide high definition,
high clarity indicia
thereon.
Applicant's previous applications highlighted Applicant's then preferred
embodiments wherein pull tabs having one or more coating layers had portions
of such
layers selectively removed to form indicia on said pull tab. According to the
invention a
pull tab is provided having selective removal of not only the coating layer or
layers, but also
a portion of the substrate itself. According to Applicant's presently
preferred method of
laser engraving a coated pull tab, the substrate itself may be permanently
etched with at
least a portion of the intended indicia, thereby preventing counterfeit or
easy disfiguration
of the pull tab's indicia.
Furthermore, according to the invention, laser ablation of a portion of the
substrate
allows for an uncoated pull tab to be etched with a laser to create a visually
contrasting
image due to the sublimation and oxidation of the substrate. Also, according
to a related
aspect of the invention, laser ablation of the substrate surface to a
specified depth allows
for a physical relief of the substrate whereby the indicia is not only visible
but also
detectable by touch. For example, according to the invention, Braille language
letters can
be etched into the tab to identify the contents of the container.
According to the invention, and as will be appreciated by one of ordinary
skill in
the art armed with Applicant's specification, the substrate can be ablated or
etched to any
desired depth.
In accordance with one aspect of the invention, there is provided a pull tab
container
opening device having informational, promotional or decorative materials laser
ablated into
the surface of the pull tab substrate. According to another aspect of the
invention, there is
provided a pull tab container opening device having at least one substantially
permanent
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coating layer thereon and having informational, promotional or decorative
materials
thereon, wherein said materials are formed by the selective laser removal of
at least a
portion of said coating layer and a portion of said substrate.
In accordance with another aspect of the present invention, there are provided
methods of making the aforementioned pull tab container opening devices having
laser
etched indicia thereon.
The pull tabs of the present invention may be made of any suitable material
which
is capable of functioning of as a pull tab for a container including aluminum,
steel, plastic,
other metals, and/or any natural, synthetic, composite, or other suitable
material. The
selection of suitable materials are well within the ability of one of ordinary
skill in the art.
The tabs may also include a ring-shaped aperture for receiving the finger of a
user.
Construction of suitable pull tabs according to the invention is well within
the ability of one
of ordinary skill in the art. The invention should not be understood as being
limited by the
shape, size or material of the pull tab substrate.
In accordance with a presently preferred embodiment, there is provided a pull
tab
comprising an aluminum alloy wherein said tab is contacted with the emission
of an optical
device capable of ablating the surface of said tab such that the surface of
said tab is
permanently etched. The etching may be of any depth desired. Preferable depths
are
between 5 and 50 microns, and more preferably, between 15 and 30 microns.
In accordance with another presently preferred embodiment, there is provided a
pull
tab having a coating layer thereon, wherein said pull tab has indicia
generated thereon by
the laser ablation of a portion of a said coating layer to reveal at least a
portion of said
substrate which is also selectively ablated by the laser to any suitable
depth. In accordance
with yet another presently preferred embodiment, there is provided a pull tab
having a
plurality of coating layers thereon. In accordance with this aspect of the
invention, the pull
tab according to the invention has an image of multiple colors generated
thereon, wherein
said image is generated by the selective removal (through selective laser
ablation) of said
coating layers and the surface of said substrate such that at least a portion
of said image is
permanently etched in said substrate to a desired depth.
Suitable coatings for pull tabs according to the invention include any
coatings
capable of selective removal by laser ablation. In accordance with one aspect
in the
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invention, the coatings used on a substrate should be more susceptible to
laser ablation, by
sublimation or otherwise, than the surface of the substrate. Thus, the
operator of a laser
etching apparatus according to the invention, can remove the coatings without
affecting the
surface of the pull tab unintentionally.
S Representative coatings include those readily accessible by those of
ordinary skill
in the art. For example, Alcoa supplies tab stock with suitable coatings
supplied by
Valspar, Dexter, BASF, and numerous others. The coating type is not limited to
epoxy,
vinyl or other organic coating. It may be preferable to use a coating that
contrasts with the
underlining substrate, which may be aluminum, other materials, or another
coating layer.
In addition, multiple layers of contrasting coatings may be used so that
selective removal
of portions of the layers may reveal a multiple color design. The present
invention should
not be understood to be limited by the number or color of coatings supplied,
nor by the
substrate to which indicia is to be applied.
The present invention is also not limited by the laser-etching method used to
decorate pull tabs according to the invention. As will be appreciated by one
of ordinary
skill in the art, there are a variety of methods of generating images on a
substrate via laser.
All of such methods are equally understood as being within the scope of the
invention.
One presently preferred method for laser-etching a design into a pull tab is
computer-aided laser etching. In accordance with this method, a design is
laser-etched into
a substrate with the aid of a computer and computer peripherals, wherein the
laser-etching
device is controlled by a computer program which controls the orientation and
path of the
laser beam to generate an ablated pattern. Any laser device suitable for
computer-aided
laser etching may be used according to the invention. The work piece, in this
case a pull
tab, preferably includes a surface upon which a single layer or multiple
layers of coating
material, such as an oxidizable paint or organic coating, has been applied.
According to the present invention, a presently preferred method is performed
by
the following steps: a design is input into a computer memory by use of a
scanner or other
input device; the design is then scaled to the desired size; the intensity of
the laser beam is
selected so that only the desired layer or layers of material are removed to a
specific depth;
and the control program is allowed to direct the laser beam to etch away
appropriate
portions of the layer or layers of the ablatable materials, thus exposing
and/or etching the
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underlining surface or coating to form the desired image. In accordance with
this method,
multiple color and multiple layer designs may be formed by programming the
laser beam
to remove different portions and depths of each layer to create a mufti-
colored or multi-
layered design.
$ In accordance with this aspect of the invention, a presently preferred
embodiment
involves use of a yttrium aluminum garnet ("YAG") laser marker. The YAG
marking
process works by steering the laser beam with a pair x and y galvanometers
which are
controlled by software and hardware interfaces. In accordance with this
embodiment of the
invention, indicia are inscribed on to the substrate with extremely fine
resolution and
clarity, thereby providing striking contrast and resolution as compared to
prior art ink-
printed substrates.
Another presently preferred method for laser-etching a design into a pull tab
is
mask-etching. In accordance with this method, COz lasers, or other similar
high gain
optically pumped laser devices, suited for laser marking may be used. COz and
like lasers,
may use a mask or stencil for etching purposes. In accordance with this aspect
of the
invention, a presently preferred embodiment contemplates use of a laser device
in which
a mask defining a desired pattern is placed in the laser's optical cavity. The
output power
or energy emanating from the laser should be sufficient to affect physical
alterations of
surfaces such that the desired pattern from the mask is engraved into the
surface of the
substrate contacted by the output of the laser device. Alternatively, the mask
structure may
be disposed between the output of the laser device and the surface of the
substrate anywhere
along the output's path. Accordingly, one of ordinary skill in the art will
appreciate that
various configurations of where the mask or stencil is positioned between the
laser source
and the substrate surface are within the scope of the invention.
As will be appreciated by one of ordinary skill in the art, suitable mask
structures
include those having cut-out portions defining the desired pattern to be
engraved on the
substrate. Furthermore, one of ordinary skill in the art will appreciate that
equivalent
patterns can be formed by providing masks having portions that are simply
transmissive to
the particular wave length of laser light involved. Accordingly, the term "cut-
out portions"
is meant to include any equivalent means of defining patterns on the mask such
that the
pattern is capable of being etched into the surface of the substrate being
worked upon.
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Generally, mask structures are used with lasers when a pattern having a
uniform depth is
desired. Mask structures are not as susceptible to altering the intensity or
depth of various
portions of the indicia to be generated on a substrate. However, as will be
appreciated by
one of ordinary skill in the art, multiple masks and/or multiple laser devices
may be used
for generating indicia having varying depths of ablation or multiple layers to
be selectively
ablated. A presently preferred embodiment involves a single mask and a single
layer
whereby a coated pull tab has the pattern of the mask ablated through the
coating layer and
into the substrate to a depth of up to 30 microns. Such an embodiment allows
for the rapid
engraving of numerous tabs at production speeds. Accordingly, COz laser
etching is
primarily suited to generating indicia on pull tabs having a single coating
layer or having
no coating layer at all.
However, as will be appreciated by one of ordinary skill in the art, assembly-
line
type laser etching stations may be set up along the production line such that
as a substrate
passes each station a different portion of the indicia is quickly laser-etched
onto the
substrate.
The invention as described and claimed herein should become evident to a
person
of ordinary skill in the art given the following enabling description and
drawings. The .
aspects and features of the invention believed to be novel and other elements
characteristic
of the invention are set forth with particularity in the appended claims. The
drawings are
for illustration purposes only and are not drawn to scale unless otherwise
indicated. The
drawings are not intended to limit the scope of the invention. The following
enabling
disclosure is directed to one of ordinary skill in the art and presupposes
that those aspects
of the invention within the ability of the ordinarily skilled artisan are
understood and
appreciated.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a top view of an aluminum can top according to one embodiment of
the invention.
FIG. 2A shows a substrate having a coating layer and a design laser-etched
thereon
according to one embodiment of the invention.
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FIG. 2B shows a substrate having multiple layers and having a multi-layer
design
laser-etched thereon according to one embodiment of the invention.
FIG. 3A-B are photomicrographs of a prior art, ink-spray printed aluminum can.
FIG. 4A-B are photomicrographs of a laser-etched coated aluminum substrate
according to one embodiment of the invention.
FIG. SA-C are photomicrographs of a laser-ablated surface of an aluminum
substrate according to one embodiment of the invention.
FIG. 6 is a top view of an apparatus for manufacturing laser-etched pull tabs
according to one embodiment of the invention.
FIG. 7 is a top view of an alternative apparatus for manufacturing laser-
etched pull
tabs according to another embodiment of the invention.
FIG. 8 is a top view of another alternative apparatus for manufacturing laser-
etched
pull tabs according to another embodiment of the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 illustrates a novel, laser-etched container opening device according to
the
present invention. As depicted on FIG. 1, a representative aluminum can top
120, or other
container top, is provided for receiving a container opening device. Can tops,
or container
lids, are typically formed into a desired shape for receiving a container
opening device and
for attachment to a container body within a conversion press (not shown).
During the can
top formation process, various bubbles and deformations known as "coins" are
imparted
into the can top in order to enhance the strength thereof. The can top of FIG.
1 shows
typical anti-buckle coins 121 produced within the conversion press. An
additional coin 126
is also shown on FIG. 1. The can top also includes a top opening score 122 to
allow the
container to be opened by a user, and a top rim 123 to allow the top to be
attached to a
suitable container body. Other deformations 127 may also be present in the
scored panel
128 to help provide access to the contents of the container. Preferably, there
is an
interruption (not shown) in the path of the top opening score 122 sun: ounding
the panel 128
so that the panel 128 remains attached to the can top 120 after opening.
s83zsa.vba7.oio - 8 -
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To aid the opening of the container by a user, a pull tab 124 is provided for
actuation by the user. As will be appreciated by one of ordinary skill in the
art, pull tabs
are typically formed from a thin sheet of tab stock material in a conversion
press. In a
conversion press, various cutting and stamping dies operate on the sheet of
tab stock
material to form a sheet of pull tabs capable of being pulled from the sheet
and attached to
a container top. For example, as depicted on FIG. 1, a tab 124 may be riveted,
or staked,
onto a button 125 in the can top by a re-strike action of the conversion
press.
As depicted on FIG. 1, today's typical pull tab comprises a grab portion 129
and a
nose portion 130. The grab portion 129 may be lifted to force the nose potion
130 into
intimate contact with the scored panel 128. When the pressure of the nose
portion 130
against the scored panel 128 is sufficient, the opening score 122 tears and
the panel 128
may be folded down to allow access to the contents of the container.
Preferably, an
interruption (not shown) in the opening score 122 prevents the panel 128 from
detaching
from the can top 120 and falling into the container. As shown on FIG. 1, a
slit 131 may be
advantageously provided in the pull tab 124 in order to facilitate its action
as a lever with
the staked button 125 acting as a fulcrum connection point. As will be
appreciated by one
of ordinary skill in the art, almost any tab of any size, shape, or
configuration may be
suitable for use in the present invention.
According to the embodiment depicted in FIG. 1, the grab portion is preferably
configured to not include an aperture for accepting the finger of a user, but
rather
configured to be a "closed-tab." Such a closed-tab configuration provides
additional
surface area upon which to apply promotional, informational or decorative
materials. For
example, the pull tab of FIG.1 exhibits a decoration 132 illustrated as a
"value mark" logo.
According to the invention, the decoration 132 is laser-etched into the
surface ofthe
pull tab substrate. The term "laser-etching" is intended to mean the process
by which a
selective portion of a material is removed by contact with a laser beam to
form a desired
pattern of a desired depth by localized sublimation, evaporation, burning,
oxidation, or
other process, of the contacted material or materials. Thus, for example, as
depicted in the
embodiment of FIG. 1, the logo "value mark" and the border surrounding the
logo are
preferably the result of the surface of the pull tab being contacted by the
beam of a laser
such that the contacted area is ablated in a predetermined pattern to a
predetermined depth.
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In the case of a presently preferred substrate, an aluminum pull tab, such
ablated areas
achieve, quite unexpectedly, remarkably visually-contrasting images due to the
oxidation
and sublimation of the substrate. In other words, the ablated areas are of a
surprisingly
different shade and/or color than the untreated areas. Such a stark visual
contrast in color
is not achievable by mechanical etching, stamping or chemical engraving of
aluminum pull
tabs. Furthermore, as will be appreciated by one of ordinary skill in the art,
laser-etching
allows images to be generated on substrates to almost any resolution; visually
perceptive
or otherwise. Such resolution is likewise not reliably achievable by prior art
methods.
The visual contrast achievable through laser-etching techniques can also be
used to
provide informational, promotional or decorative materials onto other parts of
the container.
For example, as depicted in FIG. 1, the can decoration 133 "brand equity" is
etched directly
into the can top 120. Such can decorations are preferably generated on can
tops that have
a colored coating on, or pigment in, the aluminum (or other material) of the
top, because
the visual contrast and the striking clarity systemic in the laser-etching
process are even
more striking.
Furthermore, laser-etched pull tabs according to the invention are preferably
etched
to a predetermined depth whereby a physical relief which may be detectable to
the touch
is generated on the pull tab. In a presently preferred embodiment such as
where the
substrate to be etched is an aluminum pull-tab container opening device for an
aluminum
beverage can, the etching is preferably to a depth of from about 5 microns to
50 microns,
and more preferably from about 15 microns to about 30 microns.
As will be appreciated by one of ordinary skill in the art, controlling the
depth to
which a laser ablates the surface of a substrate is dependent upon, and can be
controlled by,
the manipulation of multiple factors. For example, each of the type, power and
contact time
of the laser device allow the user to effect the depth of the etching. Also,
for example, the
type of substrate, coating, etc. allow the user to predetermine the depth of
etching through
trial and error or otherwise.
Furthermore, as will be appreciated by one of ordinary skill in the art upon
reading
Applicant's specification, once the workpiece materials and process parameters
are set,
laser-etching allows for rapid, high volume production of products having
virtually
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identical, highly-resolved indicia generated thereon. Such predictability and
repeatability
are not achievable by prior art printing techniques.
Two presently preferred laser-etching methods are computer-aided laser etching
and
mask etching. As will be understood by one of ordinary skill in the art,
computer-aided
etching typically entails the use of a computer and computer peripherals to
control the
orientation, path, and/or power of a laser's beam to generate an ablated
pattern on a
workpiece. According to a preferred method, a design is input into the memory
of a
computer through either a scanner, a keyboard, both, or any other device or
method of
inputting a design known in the art. The computer may then communicate the
design to a
laser engraving device which engraves the design onto the workpiece by use of
the devices
laser beam. The choice of a suitable laser device is well within the ability
of one of
ordinary skill in the art. A presently preferred embodiment makes use of a YAG
laser
device, and more preferably a 120 watt Nd:YAG laser device having a 530 nm
wavelength.
According to this method, the computer may be a typical personal computer,
such
as an IBM 486, Pentium or like computer, which has been programmed with a
laser control
program. For example, such a laser control program is the LUMONICS SOLO user
interface software which is available with a LUMONICS LIGHTWRITER SPE laser
engraving device, or the ROFIN-SINAR VISUALLASERMARKER-SOFTWARE used
with ROFIN-SINAR laser engraving devices. It should be understood that other
brands and
models of control software, engraving devices, etc., whether presently
existing or not,
which are capable of performing the method described herein are within the
scope of the
invention, and that the brands and models discussed are by way of example only
and should
not be deemed to limit the scope of the invention.
In operation, an operator enters an input design, such as "value mark" into
the
memory of a computer. The design may be entered into the memory of the
computer by
scanning the image into a scanner or by typing, or both, or otherwise entering
the image
with a computer keyboard. Preferably, the operator may be able to modify the
input design
in a variety of ways. For example, it is presently preferred that the operator
be able to scale
the design by any conventional technique such that the whole, or any part, of
the design is
capable of being made larger or smaller, or such that multiple images may be
combined in
whole or in part.
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The workpiece is then placed in a position that is within the path of the
laser beam.
The intensity of the laser beam is adjusted so that the etching will be to a
proper,
predetermined depth. The laser beam is then controlled by the computer to etch
the design
into the workpiece. According to a presently preferred method, computer
control of the
laser beam involves software and hardware interfaces which control a pair of X
and Y
galvanometers which steer the laser in a path corresponding to the output
design. The
output design etched should reflect the input design and any modifications
made by the
operator. As will be appreciated by one of ordinary skill in the art, the
depth of the etching
may be controlled by various means. A presently preferred method of
controlling the depth
of the etch is by varying the intensity of the beam, primarily but not limited
to variations
in the focal length and power level of the beam. It is well within the ability
of one skilled
in the art to know, or learn through trial and error or otherwise, the proper
settings for the
particular laser and laser beam utilized in view of the particular workpiece
involved.
Furthermore, the laser beam may be maneuvered by a galvo deflection system
used
1 S in a single or mufti-head configuration to achieve high speed vector
marking in an on-the-
fly system. The galvo head could also be configured with a miniature camera
for checking
on-line the workpiece configuration or the marking content.
Alternatively, the laser etching may be effectuated by the mask-etching
method. As
will be appreciated by one of ordinary skill in the art, this method typically
involves shining
a laser beam through a mask, and possibly other peripherals, prior to
contacting the surface
of a workpiece. The choice of a suitable laser device for this method of
etching is well
within the ability of the ordinarily skilled artisan. Presently preferred
devices include high
gain pump devices such as C02 lasers.
The mask material should be capable of resisting penetration of the laser
beam. The
mask may be disposed within the Tensing-system of the laser source, at the
output point of
the laser device, or otherwise disposed along the path of the laser beam.
Alternatively, the
mask may operate as a stencil which sits against the workpiece during the
marking process.
The mask typically includes cut-out portions in the shape of the desired
image, whereby the
only portions of the beam penetrating the mask are those in the shape of the
desired image.
As will be appreciated by one of ordinary skill in the art, suitable mask
structures
include not only those having cut-out portions defining the desired pattern to
be engraved
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on the substrate, but also those that have portions that are simply
transmissive to the
particular wave length of laser light involved. Accordingly, the term "cut-out
portions" is
meant to include any equivalent means of defining patterns on the mask such
that the
pattern is capable of being etched into the surface of the workpiece being
worked upon.
Generally, mask structures are used with suitable lasers when a pattern having
a
uniform depth are desired because mask structures are not as susceptible to
altering the
intensity or depth of various portions of the indicia to be generated on a
workpiece.
However, as will be appreciated by one of ordinary skill in the art, multiple
masks and/or
multiple laser devices may be used for generating indicia having varying
depths of ablation
or multiple layers to be selectively ablated. A presently preferred embodiment
involves a
single mask and a single layer whereby a coated pull tab has the pattern of
the mask ablated
through the coating layer and into the substrate to a depth of up to 30
microns. Such an
embodiment allows for the rapid engraving of numerous tabs at production
speeds.
Accordingly, mask-etching with a C02 or like laser is primarily suited to
generating indicia
on pull tabs having a single coating layer or having no coating layer at all.
Regardless of what type of laser etching is used, a presently preferred
embodiment
of the invention utilizes a pull tab having at least one coating layer
thereon. FIG. 2A
depicts a single coating layered, laser-etched substrate according to the
invention. In the
embodiment depicted in FIG. 2A, there is provided a substrate 150 having a
coating layer
151 thereon. Presently preferred coating layers include those readily
accessible by those
of ordinary skill in the art. For example, Alcoa supplies tab stock with
suitable coatings
supplied by Valspar, Dexter, BASF, and numerous others. The coating type is
not limited
to epoxy, vinyl or other organic coating. In accordance with this embodiment
of the
invention, the coating layer 151, and at least a portion of any part of the
substrate 150
revealed thereunder, are laser-etched to provide a permanent etched-area 160
capable of
defining an exceptional, visually striking image for promoting or decorating
the container.
As will be appreciated by one of ordinary skill in the art, the workpiece
materials
and process parameters can be chosen to cause ablation of the surfaces) of the
coating
layers) and substrate to be ablated in almost any desired pattern, to almost
any desired
depth.
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According to an advantageous embodiment, the substrate 150 may be an aluminum
tab, or some other container opening device to be decorated or marked.
According to this
embodiment, this substrate is an opening device for a food or beverage
container, however,
any other suitable substrate may also be marked. Presently preferred
substrates may be
made of any suitable material and may form a part of a pull tab, can top,
bottle cap,
container lid, or any other portion of a container device.
According to the invention, the substrate may be coated with more than one
layer.
FIG. 2B shows four layers of coatings on the substrate 150. As discussed
above, coatings
are preferably materials capable of laser ablation and more preferably,
materials more
susceptible to laser ablation by the intended laser than the underlying
substrate or
underlying layers and substrate. Presently preferred coating layers include
those readily
accessible by those of ordinary skill in the art. For example, Alcoa supplies
tab stock with
suitable coatings supplied by Valspar, Dexter, BASF, and numerous others. The
coating
type is not limited to epoxy, vinyl or other organic coating.
The coatings may be of any suitable colors. Preferably, the coatings are of
visually
differing or contrasting colors such that a multi-colored image may be
created. By way of
example, the mufti-coated substrate of FIG. 2B may comprise a cyan layer 151,
a magenta
layer 152, a yellow layer 153, and a black layer 154. When the substrate is
aluminum, a
removal of all four layers, such as an area 155 reveals a natural aluminum
color. Area 156
shows the removal of three layers revealing a cyan color. Area 157 shows the
removal of
two layers revealing a magenta color. Area 158 shows removal of a single layer
revealing
a yellow color. In this fashion virtually any color can be generated.
Furthermore, in
accordance with the invention, area 159 shows not only the removal of all four
layers, but
also the partial ablation of a portion of the substrate to a desired depth. By
such ablation
of the substrate, a permanent etched-area 160 may be created. Such an area
will continue
to serve to identify the tab even ifthe layers (151, 152, 153, 154) are
removed by chemical
means, physical means, or otherwise. As will be appreciated by one of ordinary
skill in the
art, such permanent ablation of the surface of a substrate can serve to
prevent counterfeiting
or prolong the informational, promotional or decorative power of the
substrate.
Permanence in the presence of chemical solvents is only one advantage of the
present invention over more conventional methods of marking aluminum or other
types of
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substrates with colors. For example, in the aluminum can industry, ink-spray
printing is
occasionally used to place source and date indicia on the bare aluminum of the
underside
of the can. FIG. 3A and FIG. 3B are photomicrographs of the ink-printed
characters
applied to the underside of a "Mountain Dew" soda can (produced by Pepsi-Cola
Company). FIG. 3A and 3B were taken by a Scanning Electron Microscope ("SEM")
at
1 SX and 30X, respectively. The solid line at the bottom right of the
micrographs represents
a length of one hundred microns. By contrast, FIG. 4A and 4B are
photomicrographs at
15X and 30X, respectively, of a laser-etched coated aluminum substrate
according to the
invention. More specifically, FIG.4A-B are photomicrographs of a piece of
5052H19
aluminum-alloy substrate having a 3msi (about 1.9 micron thick) Valspar 26839-
803 black
epoxy coating which was treated at production speeds with a 120 Watt-powered,
Nd:YAG-
type laser, having a 530 nm wavelength.
Comparing FIGS. 3A-B to FIGS. 4A-4B reveals that typical laser ablation
craters
generated by a Nd:YAG or similar laser are only approximately 60 microns in
diameter,
which is a full magnitude of difference smaller in size than a typical ink dot
(which
averages between about 600 to 700 microns) of an ink printing process.
Accordingly, as
will be appreciated by one of ordinary skill in the art, the resolution and
clarity capable of
being generated by laser etching is also a full magnitude of difference better
than that of the
ink printing process.
Also revealed is the fact that typical laser ablations are substantially
uniform in
shape, surface area and appearance; whereas ink dots are non-uniform in shape,
surface area
and appearance (which adversely affects clarity and resolution). Accordingly,
as will be
appreciated by one of ordinary skill in the art, laser etching inherently
results in an image
having better resolution and sharpness. Furthermore, typical laser ablations
are extremely
precise in location and predicable in occurrence, thereby promoting a visually
uniform and
virtually uninterrupted pattern of ablations as compared to the spotty
deposition of ink dots
which is systemic in the ink printing process. In addition, laser ablations
allow for a
visually clear demarcation between the color-coated area and the laser-treated
area as
compared to the unpredictable contours and ink-concentration of ink dots
generated in the
ink printing process.
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Furthermore, as discussed above, the laser etching process provides for a
substantially permanent image when the substrate itself is ablated to any
suitable or desired
depth, as compared to the more easily removed (whether physically removed or
chemically
removed) ink generated image of the ink printing process, which is inherently
incapable of
accumulating at any appreciable thickness above the surface of the substrate
due to its
solvent-Garner base. FIGS. SA-C are micrographs of the embodiment of FIG. 4 at
differing
positions and resolutions. As shown in the photomicrographs, the surface of
the aluminum
substrate below the coating may be ablated to a predetermined depth. In a
presently
preferred embodiment, the substrate is etched to a depth of about 5 to about
50 microns,
more preferably a depth of about 15 to about 30 microns. The substrate of FIG.
S is ablated
to a presently preferred depth of about 30 microns.
In view of the foregoing enabling disclosure, one of ordinary skill in the art
will
appreciate that laser-etching substrates such as pull tabs according to the
invention
overcomes many of the shortcomings and limitations of the prior art, and
satisfies a long-
felt, yet unresolved need.
As will be appreciated by one of ordinary skill in the art, laser-etching
processes can
be carned out at any suitable stage of an article of manufacture's life-span.
For example,
with pull tabs, the laser-etching process may be carried out prior to, during,
or after a tab
stock material is formed into pull tabs and connected to the top of a
container.
A representative apparatus for manufacturing pull tabs according to the
invention
is depicted in Figures 6-8. In a first embodiment, as shown in FIG. 6, the
apparatus
comprises a modified conversion press 70. Typical conversion presses for the
manufacture
of prior art tabs are commercially available from such companies as Dayton
Reliable Tool.
The modified press 70 includes a container end conveyer 71 for transporting
container ends
through the press 70. The container end conveyer 61 has an inlet 72 for
accepting untabbed
container shell ends and an outlet 73 through which tabbed container shell
ends may be
collected. The conveyer 71 transports container ends from the inlet 72,
through the press
70, to the outlet 73, where tabbed container ends may be collected.
As depicted in FIG. 6, the press 70 also includes a tab stock inlet 74 and a
formed
tab strip outlet 76. Interposed between the tab stock inlet 74 and tab strip
outlet 76, and
transversing the conveyer 71, is a die area 75. As generally known in the art,
the die area
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75 comprises a plurality of cutting and stamping dies (not shown) which
operate to form
and shape materials pressing therethrough into a desired configuration. The
die area 75
may treat container ends as they pass through the die area 75 on conveyer 71.
According
to the invention, tab stock 90 may enter the press 70 through the tab stock
inlet 74. As
depicted in FIG. 6, a strip of tab stock 90 enters through the inlet 74 and
then passes into
the die area 75 where it is cut and shaped into formed tabs. The formed tab
strip 91 may
then exit the press 70 through formed tab strip outlet 76.
In a preferred embodiment, the die area 75 is composed of a plurality of
interchangeable cutting dies and stamping dies. As will be appreciated by one
of ordinary
skill in the art, interchangeable parts allows a single press to be used in
manufacturing a
plurality of differently shaped tabs comprised of a plurality of different
materials. For
example, the die could be rigged to produce a tab lacking a finger aperture by
removing or
blocking the aperture cutting dies. Accordingly, numerous other modifications
to the die
area to produce differently configured tabs can be fully appreciated by the
skilled artisan
in view of Applicant's specification.
The formed tab strip 91 after exiting the press 70 through formed tab strip
outlet 76
may reenter the press 70 through the formed tab strip inlet 77. The formed tab
strip 91 is
then fed into a riveting area 78 adjacent the conveyer 71. In the riveting
area 78 formed
tabs are removed from the formed tab strip 91 and riveted to container ends
entering the
riveting area 78 via the conveyer 71. The formed tab strip scrap 92 then exits
the riveting
area 78 and, ultimately, the press 70 through the tab scrap outlet 79.
Container ends exit
the riveting area 78, having tabs riveted thereto, by means of the conveyer
71. The
conveyer ultimately feeds the tabbed container ends out of the press 70 at the
conveyer
outlet 73 where the container ends may be collected. The tab strip scrap 92
exiting the tab
scrap outlet 79 may also be collected and used for other purposes, such as
being recycled
into fresh tab stock 90.
Tab stock 90, according to the invention, may comprise any material capable of
use
as a pull tab container opening device. Exemplary materials include aluminum,
steel,
plastic, or any natural, synthetic, composite, or other suitable material.
Similarly,
combinations of materials as layers or otherwise may also be used.
Accordingly, one of
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ordinary skill in the art will understand that corresponding manipulation of
the modified
press 70 may be necessary to accommodate different materials.
In a preferred embodiment, the tab stock 90 comprises aluminum. As depicted in
FIG. 6, aluminum tab stock strips may be any suitable width and of any desired
length.
Generally, existing presses accommodate tab stock of either 1.9 or 2.8 inches
in width and
.009-.010 inches in thickness. According to the present invention, the depth
of the stock
can be increased, depending on the strength desired and the material used. A
preferred
embodiment contemplates an aluminum strip of about 1-3 inches in width and
about .0125
inches in depth.
Colored tab stock 90 may be used with the present invention if colored tabs
are
desired. To effectuate the coloring, pigmentation may be used while forming
the tab stock
90, or alternatively, the tab stock 90 may be coated with a colored material.
Similarly, as
will be appreciated by one of ordinary skill in the art, other colored or
coated materials,
such as plastics, may be used.
To further enhance the decorative or symbolic power of the tabs, a laser-
etching
station 100 may be used. The laser-etching station 100 may be an area within
the modified
press 70. Alternatively, the laser-etching station 100 may be located outside
the press 70,
although it may still be in-line or integral with the press 70.
In a preferred embodiment as depicted in FIG. 6, the laser-etching station 100
is
located at an area whereby the tab stock 90 can be decorated prior to entering
the tab stock
inlet 74. The laser-etching station 100 may be integral with the feed
mechanism that feeds
tab stock 90 into the tab stock inlet 74; or alternatively, the laser-etching
station 100 may
be situated at a location for treating tab stock 90 which is not even housed
in the area where
the press 70 is located. Such a location could be at the aluminum sheet
manufacturing
facility for rolling the aluminum tab stock sheet and coating the substrate.
In other words,
the tab stock 90 may be decorated and then brought to a location housing a
press 70.
FIG. 7 depicts an alternative embodiment of an apparatus for manufacturing
pull
tabs in accordance with the present invention. With reference to FIG. 6, like
reference
numerals refer to the same elements; however, in this embodiment the laser-
etching station
100 is located outside the press 70 but in-line with the tab stock 90 such
that the formed tab
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strip 91 exits the press 70 at tab strip outlet 76 and then passes through
laser-etching station
100 prior to reentering the press 70.
Although it is contemplated that the laser-etching station 100 may perform all
of the
decorating functions within the scope of the invention no matter where it is
housed,
placement of the laser-etching station 100 in-line and capable of receiving
the formed tab
strip 91 is a presently preferred process. First, the tabs are already formed
in the strip
which may enhance the speed and ability of the apparatus, through mechanical
orientation
or computer recognition, or otherwise, to provide substantially the same tab
decorations on
each tab. Secondly, the laser-etching station 100 may be used in connection
with an
accumulator (not shown) that may be used to allow the die area 75 to operate
at a faster
pace than can be accommodated by the laser-etching station 100.
FIG. 8 depicts another alternative embodiment of an apparatus for
manufacturing
tabs in accordance with the present invention. With reference to FIG. 6 and 7,
like
reference numerals refer to like elements; however, the laser-etching station
100 in FIG. 8
is located at an area for receiving tabbed container ends exiting the conveyer
71 at the
conveyor outlet 73. In the specific embodiment depicted in FIG. 8, the laser-
etching station
100 is of a generally cylindrical shape. Disposed within the laser-etching
station 100 is a
cylindrical track 101 for accepting a plurality of tabbed container ends. The
laser-etching
station 100 also has an interior section 102 encircled by the cylindrical
track 101.
In this embodiment, tabbed container ends exit the conveyor 71 at the conveyor
outlet 73 and are received by the cylindrical track 101 of the laser-etching
station 100. The
track 101 may be rotated in either direction such that the container ends may
be rotated to
or through one or more stations. With this arrangement, different tab
decorations can be
etched onto the tabs, or container ends; at different stations. Laser etching
equipment may
be disposed within the interior section 102 of the laser-etching station 100
and/or located
on the outer perimeter of the track 101. This embodiment may be preferred, or
in
combination with the previous embodiments, if decorations are to be supplied
not only to
the tabs, but also to the container ends. The laser-etching station 100 may be
integral with
the conveyor outlet 73; or alternatively, the laser-etching station 100 may be
situated at a
location for attaching tabbed container ends onto beverage or food can bodies,
which is not
even housed in the area where the press 70 is located. Such a location could
be a the filling
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or packing facility of a beverage or food company. In other words, the tab
stock 90 may
be decorated and then brought to a location housing a press 70.
The laser-etching station 100 of the present invention may be configured in
any
manner suitable for etching the tab stock, formed tab strip, or tabs before or
after
attachment to the container. The exact layout and design of the laser-etching
station will
vary according to the methods and materials to be used. The laser-etching
station may
further comprise an apparatus for embossing, debossing, inscribing or etching
tab
decorations, or any combination thereof. Similarly, the laser-etching station
may comprise
alone, or in combination with the above, any apparatus suitable for printing,
screening,
painting, adhering, gluing or otherwise placing or generating tab decorations
on tabs or tab-
making materials.
The laser-etching station may make use of mechanical orientation or computer
controlled artificial recognition systems to help ensure that the tab
decorations appear
substantially the same on the end product.. It is also within the scope of the
invention to
make use of a plurality of laser-etching stations, for example, a combination
of FIGS. 6-8.
It is understood that many modifications to this invention may be made without
departing from the spirit of the invention. The appended claims express the
scope of the
invention.
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