Note: Descriptions are shown in the official language in which they were submitted.
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METHOD OF PROTECTING SECURITY ELEMENTS FROM HEAT DEGRADATION
DURING A HEAT-SEALING PROCESS
RELATED APPLICATION
[0001] This application is an International Patent Cooperation Treaty
(PCT) application
which is based on and which claims priority to U.S. Patent Application Serial
No. 16/881,493, filed
May 22, 2020, and U.S. Patent Application Serial No. 16/361,372, filed March
22, 2019, each of
which are fully incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present invention relates, generally, to a method of
protecting security
elements imprinted on, or adhered to a substrate from heat degradation during
a heat-sealing
process.
BACKGROUND OF THE INVENTION
[0003] Coatings, i.e., films, are widely used as physical barriers to
seal items into their
packaging. Often, they are known as "lidding films", such as when used in
connection with blister
packs in the packaging of pharmaceutical medicaments. As is understood by
those of ordinary
skill, the presence of the film serves to provide a physical barrier to the
egress of, e.g., the
medicament from the individual blister cavities in the aforementioned blister
pack. Puncturing of
the physical film is therefore required before any of the product housed
within the closed cavities
may be dispensed. Such a physical barrier not only securely holds the product
against undesired
egress, but also provides a measure of tamper-evident security protection, as
an intended user
may observe any deterioration of the physical barrier and know thereby that
tampering or damage
may have affected the sealed product.
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[0004] Beyond concerns over the physical integrity of the packaging as
accomplished by
the lidding/sealing barrier, additional various mechanisms have been created
so as to give a
visual indication of, e.g., the source of the packaged goods, and/or the
unadulterated condition of
the goods themselves. Thus, in certain industries, such as the pharmaceutical
or electronics
industries, security insignia and other visual markings are often imprinted or
deposited onto the
physical barrier/film to serve as an indication of whether, e.g., the drugs
contained in a blister
pack are authentic and unadulterated. To this end a number of security
elements designed to
deter would-be counterfeiters may be incorporated into, or deposited upon, the
film. One such
known security deposition is holographic or other fine-structured imagery or
elements. As will
therefore be appreciated, a premium is placed on maintaining the integrity of
the security
elements.
[0005] Problems exist, however, for packaging that utilizes, e.g.,
holographic or other
deposited and/or imprinted security elements, in that these elements are often
distorted or
otherwise damaged during the heat-sealing process that is integral to many
packaging
procedures. That is, in many known packaging systems that utilize a lidding or
physical barrier,
e.g., medicament blister packs, the progenitor physical barrier/film is first
imprinted or deposited
with various security elements, e.g., holographic elements, before the
imprinted film is thereafter
sealed to the blister pack. The sealing process typically involves utilizing a
heated sealing die to
press upon, and thereby seal, the physical barrier/film to the packaging of
the blister pack.
[0006] It has long been known that this type of sealing process may tend
to destroy the
integrity of any, e.g., holographic element(s) imprinted or deposited upon the
physical barrier/film,
and so the relevant art is replete with differing die structures, each having
specialized cavities and
areas of differing heat profiles, all in an effort to protect those areas of
the physical barrier/film
having security elements from localized, excessive heat and the resultant
degradation that would
otherwise be incident upon these security elements during the sealing process
(see, e.g., U.S.
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Patent Appl. No. 15/792,248 to Claude Scott Devens). As will be appreciated,
the use of
specialized sealing dies adds many levels of complexity and expense to the
manufacturing and
sealing process.
[0007] For their part, those of ordinary skill in the deposition or
imprinting of security
elements, i.e., holographic elements, have long utilized a series of various
coatings and films so
as to cover the deposited security elements from physical degradation during
manufacture and
shipping. That is, security forms/elements are typically deposited or
imprinted upon, e.g., a lidding
sheet or other substrate when positioned on a planar platen, before being
rolled up for eventual
storage and/or shipping. These rolls of coated substrate can be quite large,
weighing over a ton
or more, and so induce a great amount of pressure upon the surface of the
coated substrate,
including upon the holographic elements thereon.
[0008] A collection of known chemical coatings/films have long been
recognized as being
able to protect any deposited or imprinted forms/elements from frictional and
pressure damage,
and these coatings are typically applied for this purpose during the
deposition stage, so as to
protect the security forms/elements from damage when the substrate is rolled
and thereafter
stored or shipped.
[0009] The present invention has recognized that some of the coatings
typically utilized
to protect security elements from damage during shipping may also provide
sufficient heat
resistance to security elements when made using or so coated with the same.
[0010] Thus, it is a primary aspect of the present invention to propose a
method and
apparatus that can effectively protect deposited or imprinted security
elements from damage
during a heat-sealing process, without the need for structurally complex and
expensive sealing
dies.
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SUMMARY OF THE INVENTION
[0011] According to one embodiment of the present invention, a method of
protecting
security elements deposited on a substrate from heat degradation during a heat-
sealing process
is provided that includes defining a security element on the substrate,
coating the security element
with a heat resistant coating formed from a semi-crystalline or amorphous
polymer, and sealing
the coated substrate to a package housing.
[0012] According to another embodiment of the present invention, a method
of protecting
security elements deposited on a substrate from heat degradation during a heat-
sealing process
is provided that includes defining a security element on the substrate,
coating the security element
with a heat resistant coating formed from a semi-crystalline or amorphous
polymer, defining a
thickness of the polymer in dependence upon a predetermined heat profile to be
used during the
heat-sealing process, and sealing the coated substrate to a package housing
with the
predetermined heat profile.
[0013] According to yet another embodiment of the present invention, a
blister pack is
provided that includes a housing having a plurality of cavities and a cover
sealed to the housing
and enclosing the cavities. The cover includes a base layer, a security layer
including at least
one security element, and a heat protection layer. The heat protection layer
is comprised from
one of an amorphous polymer and a semi-crystalline polymer in order to provide
for heat
resistance during the sealing of the cover to the blister pack housing.
[0014] In another embodiment, a method of using a semi-crystalline or
amorphous
polymer material having a glass transition temperature ("Tg") of greater than
or equal to about
85 C (preferably from about 85 to about 165 C, more preferably from about 120
to about 150 C) is
provided, the method comprising using the polymer material to form at least
one of a security layer
and a heat protection layer of a blister pack, the blister pack including a
housing having a plurality
of cavities, and a cover sealed to the housing and enclosing the cavities, the
cover including a base
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layer, the security layer, which includes at least one security element, and
optionally, the heat
protection layer. Tg, as used herein, is determined in accordance with ISO
11357-2:2020 (Plastics
- Differential scanning calorimetry (DSC) - Part 2: Determination of glass
transition temperature
and glass transition step height).
[0015] In a further embodiment, a multi-layer film is provided, which is
suitable for use in a
blister pack, and which comprises a base layer, a security layer including at
least one security
element, and optionally, a heat protection layer, wherein at least one of the
security layer and the
heat protection layer comprises a semi-crystalline or amorphous polymer
material having a Tg of
greater than or equal to about 85 C (preferably from about 85 to about 165 C,
more preferably
from about 120 to about 150 C).
[0016] In yet a further embodiment, a blister pack is provided that
includes a housing having
a plurality of cavities, and a cover sealed to the housing and enclosing the
cavities, the cover
including a base layer, a security layer including at least one security
element, and optionally, a heat
protection layer, wherein at least one of the security layer and the heat
protection layer comprises
a semi-crystalline or amorphous polymer material having a Tg of greater than
or equal to about
85 C (preferably from about 85 to about 165 C, more preferably from about 120
to about 150 C).
[0017] In one such embodiment, the security layer of the blister pack
comprises a semi-
crystalline or amorphous polymer material having a Tg of greater than or equal
to about 85 C.
[0018] In another such embodiment, the blister pack includes a heat
protection layer that
comprises a semi-crystalline or amorphous polymer material having a Tg of
greater than or equal
to about 85 C.
[0019] In yet another such embodiment, the blister pack includes a heat
protection layer
and both the heat protection layer and the security layer each comprise a semi-
crystalline or
amorphous polymer material having a Tg of greater than or equal to about 85 C.
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BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Features and advantages of embodiments of the present invention
will become
apparent on reading the detailed description below with reference to the
drawings, which are
illustrative but non-limiting, wherein:
[0021] FIGURE 1 is a cross-sectional view of an embodiment of a heat
resistant multi-
layer film.
[0022] FIGURE 2 is a flow chart illustrating a method of making a heat
resistant multi-
layer film according to an embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0023] Reference will be made below in detail to exemplary embodiments of
the invention,
examples of which are illustrated in the accompanying drawings. Wherever
possible, the same
reference characters used throughout the drawings refer to the same or like
parts, without
duplicative description.
[0024] While embodiments disclosed herein are described with respect to
heat stable
coatings and films used to protect security elements integrated into the
lidding material of
pharmaceutical blister packs, the present invention is not so limited in this
regard. In particular, it
is contemplated that the inventive coatings and films may be utilized in any
application where heat
protection of a deposited or printed element on a substrate is desired
including, but not limited to,
security papers, product packaging, lidding, and the like.
[0025] As used herein, the terms "substantially," "generally," and
"about" indicate
conditions within reasonably achievable manufacturing and assembly tolerances,
relative to ideal
desired conditions suitable for achieving the functional purpose of a
component or assembly.
[0026] Moreover, the term "multi-layer film" or "film" refers to a multi-
leveled material that
usually takes the form of a sheet when assembled. Individual layers may be of
uniform material
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or have multiple materials incorporated into a single layer. An individual
layer may also be
comprised of sub-layers with individual properties. Materials comprising the
various layers may
be formed and bound together in any number of orders using any of the various
techniques
known in the art. Certain layers may be a continuous sheet at time of
application, other layers
may be formed by discrete deposition (e.g., sprayed on inks or polymers,
floating a liquid that
then cures, etc.).
[0027] The term "primer", as used herein, refers to a material applied to
a layer in order to
prepare it for a subsequent step. A primer may also be an individual layer as
part of a multi-layer
film, part of a layer, or in between layers. In some embodiments a primer
material may serve more
than one particular function (e.g., to prepare a surface for printing while
serving as a protective
barrier). Primer material may be formed or deposited on an adjacent surface.
In certain
embodiments the primer may be a polymer sheet. In certain other embodiments
the primer may
be sprayed on and cured.
[0028] Also, as used herein the term "blister pack" refers to a type of
packaging wherein
cavities formed in a first material are subsequently sealed using a lidding
film. A lidding film may
be a multi-layer film or may be composed of a single material.
[0029] Also, as used herein the term "security element" refers to
elements designed
and/or configured to combat counterfeiting, thus providing assurance to the
consumer that
products contained in packaging sealed by the film are genuine and
unadulterated. In some
embodiments the counterfeit-deterrence measure may be a hologram. In some
embodiments the
counterfeit-deterrence measure may be microprinted words or images that may
also be a part of
a hologram. In other embodiments an embossed pattern may be imposed over the
surface of a
layer. In other embodiments a security strip (e.g., a micro-optic security
strip) may be embedded
in the layer. The above examples may appear alone or in combination with each
other and other
similar measures. A counterfeit-deterrence measure may be part of a layer or
sub-layer with
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multiple measures alone or in combination appearing as either an individual
layer, part of a sub-
layer, or in combinations thereof.
[0030] As used herein, the term "semi-crystalline" polymer refers to a
material comprised
of a collection of polymer macromolecule chains having a morphology consisting
of crystalline
lamellae separated by amorphous regions. Such a material may be in the form of
a sheet or
otherwise formed or deposited in place as part of a multi-layer film.
Alterations to side-chain
groups and the presence or absence of plasticizing agents may affect the final
structure and
distribution of the crystalline lamellae and amorphous regions in the semi-
crystalline polymer
material. Semi-crystalline polymers are characterized by a Tg at which the
semi-crystalline
polymer material undergoes a second order transition with a concomitant change
in heat capacity.
In some embodiments, at or above Tg, significantly more heat may be added to
the polymer
without a greater rise in temperature. Likewise, "amorphous" polymers have no
crystalline
lamellae and also undergo a glass transition change at a glass transition
temperature Tg.
[0031] Turning now to Figure 1, a multi-layer construct 100 showing use
of a heat resistant
coating or protection layer 103 according to one embodiment of the present
invention, is
illustrated. The multi-layer construct 100 includes a base
layer/substrate/housing 101, a security
layer 102, and the heat resistant protection layer 103. As shown in Figure 1,
the multi-layer
construct 100 reflects a blister pack having a plurality of wells 104 for
retaining product 105
therein. As will be appreciated, the layers shown in Figure 1 are not drawn to
scale and sizes are
exaggerated to better illustrate component parts. Moreover, it will also be
appreciated that the
product 105 may be anything that can be sealed in such a package. Examples can
include:
pharmaceuticals, electrical components, and sterilized medical supplies,
amongst others.
[0032] As will be appreciated by one of ordinary skill, the base layer
101 may be made of
any material without departing from the broader aspects of the present
invention. Indeed, the
base layer 101 may be made of paper of various weights, thicknesses, and
surface finishes. In
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other embodiments base layer 101 may be a metallic foil, likewise of various
weights, thicknesses,
and surface finishes, or base layer 101 may be a paper/foil laminate. In an
embodiment,
adhesives (e.g., heat-seal coatings or heat-activated adhesives) may be
applied to base layer
101 in order to adhere the base layer 101 onto a surface (e.g., the material
of the blister pack).
The adhesives may be heat activated, optically activated (e.g., UV light
cured); or configured for
attachment to blister pack 104 by mechanical means (e.g., "knurled" or
textured together; or,
flowing and freezing into textured surface crevices).
[0033]
As also shown in Figure 1, the security layer 102, which is adhered to layer
101,
contains discreet security elements 106 that are imaged, printed or otherwise
deposited thereon
(e.g., a metalized, embossed holographic structures). The security layer 102
as well as the heat
resistant protection layer 103 described below may be formed using one or more
essentially
colorless polymers including, but not limited to, acrylic, polyester,
polypropylene, polyethylene,
polyethylene terephthalate, polyvinyl chloride and polyurethane polymers,
nitrocellulose, and the
like, and combinations thereof. In an exemplary embodiment, the security layer
is formed using
one or more heat stable amorphous or semi-crystalline polymers (e.g., acrylic,
polyester and
polyurethane polymers) having a Tg of greater than or equal to about 85 C,
such as poly(methyl
methacrylate) or PMMA and has a thickness of greater than or equal to 0.8
microns (preferably,
from about 0.8 to about 4.0 microns). Such heat stable PMMA materials are
available from Sun
Chemical Corporation, 35 Waterview Boulevard, Parsippany, NJ 07054-1285.
In other
embodiments, the security layer 102, itself, may define a security element.
Specifically, security
elements 106 do not need to be discreet, and instead, for example, may extend
across all or
substantially all of the upper surface of security layer 102. As will be
readily appreciated by the
skilled person, this would obviate the need to register security elements 106
to wells 104.
Regardless, and as shown in the embodiment of Figure 1, the security elements
106, are located
above the opening of the wells 104, although one or more security elements 106
may be placed
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at any location within security layer 102 and with respect to the wells 104,
without departing from
the broader aspects of the present invention.
[0034] Heat resistant protection layer 103, which safeguards the physical
integrity and
visual appearance of security layer 102, may be transparent, translucent,
tinted, or pigmented
and may provide additional functionality for security and authentication
purposes. For its part, in
an exemplary embodiment, the heat resistant protection layer 103, which
conforms to the surface
topography of the underlying security layer 102 and which has a minimum
thickness of about 0.8
microns (preferably, from about 0.8 to about 4.0 microns) is composed of a
semi-crystalline
polymer material (e.g., acrylic, polyester and polyurethane polymer materials)
having a Tg of
greater than or equal to about 85 C, preferably having crystalline lamellae
separated by
amorphous regions. It is an important recognition of the present invention
that controlling the
ratio, composition, and nature of the crystalline lamellae (e.g., high turned,
or tilt-angled), as
compared to the amorphous regions, essentially controls the Tg of a particular
polymer material.
In other embodiments, the heat resistant protection layer 103 is composed of a
substantially
homogeneous amorphous polymer material with a Tg of greater than or equal to
about 85 C.
[0035] In use, a plurality of security elements 106 are printed,
impregnated or otherwise
deposited upon the base layer or substrate of a package, such as the base
layer 101 of the blister
pack shown in Figure 1. This combined base layer 101 plus security elements
106 must then be
sealed to the material of the blister pack. Typically, this sealing process
involves the application
of heat, to melt or otherwise cause the material of the base layer 101 to
become affixed to the
material of the blister pack housing. It will be readily appreciated that it
is of utmost importance
that the heat-sealing process does not destroy or otherwise deform or degrade
the security
elements 106, during the sealing process.
[0036] By applying heat at a temperature at or below the Tg of the
polymer material and
above the activation temperature of the adhesive, the layer(s) formed using
the polymer material
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(i.e., the heat resistant protection layer 103 and/or the security layer 102)
does not deform and in
the case of the protection layer 103, also serves to lock in or secure the
fine surface structure of
the underlying security layer 102, thus preserving the structure of security
elements 106. At
temperatures above Tg the heat capacity of the semi-crystalline or amorphous
polymer material
increases, providing additional thermal protection should any process
deviations occur (e.g.,
unexpected increase in temperature).
[0037] It is therefore an important aspect of the present invention that
it is possible to
protect security elements formed on a substrate from the damaging effects of a
heat-sealing
operation by using a semi-crystalline or amorphous polymer material having a
Tg of greater than
or equal to about 85 C to form at least one of the security layer 102 and the
heat resistant
protection layer 103, alone. In this manner, the security elements 106 are
adequately protected
from the heat of the sealing process, all without the need for sophisticated
heating dies, having
complex architecture and differing areas of heat conductivity, as is currently
known and
employed in the art.
[0038] In some embodiments, the security layer 102 is composed of a semi-
crystalline
polymer material such as PMMA or an amorphous polymer material, the polymer
material having
a Tg of greater than or equal to about 85 C (preferably from about 85 to about
165 C, more
preferably from about 120 to about 150 C). Such a heat stabilized polymer
material allows the
holographic or other fine-structured imagery of the security elements 106 to
remain unaltered or
substantially unaltered during a heat-sealing process, thus preserving the
optical effect of
security elements 106. This same effect may also be achieved by using one or
more such
polymer materials to form protection layer 103, or by using one or more such
polymer materials
to form both the protection layer 103 and the security layer 102.
[0039] In other embodiments the protection layer 103 is composed of a
semi-crystalline
polymer such as PMMA or an amorphous polymer material, the polymer material
having a Tg of
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greater than or equal to about 85 C. As an example, a multi-layer construct
100 with a heat
resistant protection layer 103 composed of PMMA having a Tg of 165 C is
applied to a blister pack
104 using an application temperature range of 135-160 C and commonly at a
temperature of about
147 C (dependent upon blister pack material composition, adhesives (if
present), and specific multi-
layer construct 100 composition). This is lower than the Tg of 165 C of the
PMMA. Indeed,
dependent upon other co-polymers, side chain compositions, presence of
plasticizers, free volume
of the polymer material, etc. PMMA formulations may have a Tg in the range of
85-165 C. Thus,
in practice, a protective film (and/or the security layer) may be formed from
polymer materials
chosen to have a Tg above the application temperature range.
[0040] The heat resistant protection layer 103 may further serve and be
configured as a
primer enabling the deposition of inks or other materials. Thus, in some
embodiments, inks may
be "overprinted" on top of the protection layer 103. As will also be
appreciated, the protection
layer 103 may be the final layer in the multi-layer film, or it may be beneath
or between one or
more layers. In some embodiments, the protection layer 103 may vary in
thickness with thicker
or thinner areas corresponding to areas needing more or less protection. In
some embodiments
the protection layer 103 may contain an embossed design that also serves as a
counterfeit
deterrence measure on its own or as part of security elements 106. In still
other embodiments
protection layer 103 may contain two or more polymer materials with two or
more Tgs. The two
or more polymer materials may be in discrete patches or may be continuous
and/or contiguous
with each other with either blended transitions between polymer materials or
defined transitions.
[0041] In an embodiment, the heat resistant protection layer 103 may be
deposited
directly atop the base layer 101 or the security layer 102 (with security
elements 106) through the
use of a spray applicator or liquid coating. In other embodiments, it is
envisioned that the
protection layer 103 may be applied using a transfer film and/or a transfer
lamination process.
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[0042] Thus, the heat resistant protection layer 103 serves as a
protective brace and/or
heat sink. As noted above, the protection layer 103 conforms to the surface
topography of the
underlying security layer 102 and holds the surface microstructure of the
security elements 106 in
place, thus protecting the counterfeit-deterrence properties to an extent that
the integrity of the
security elements 106 will not be compromised (e.g., distort, degrade, break,
alter color, alter
texture, etc.). In some embodiments, the protection layer 103 may serve in the
same capacity
against other activation energies, for example, UV light.
[0043] Therefore, in those embodiments that use heat as the activation
energy, the
protection provided by protection layer 103 and/or security layer 102
eliminates the need for
specially configuring the heating/sealing plate/platen of the blister pack
packaging system. Indeed,
the protection layer and/or security layer enables the use of standard, flat,
heating plates to seal
the lidding film with integrated security elements 106 onto a blister pack
without degrading such
security elements. The manufacturing process is therefore substantially
simplified, rendering it
much more cost effective.
[0044] Turning now to Figure 2, a method 200 of manufacturing a multi-
layer film 100 having
a protection layer 103 is illustrated. In a first step 201, a base layer 101
is provided. In a second
step 202, a security layer 102 with a plurality of security elements 106 is
formed or deposited on top
of a base layer 101. In a third step 203, the protection layer 103 is formed
or deposited on top of
security layer 102. Optionally, protection layer 103 may also be formed on top
of base layer 101,
sandwiching anti-counterfeit layer 102 between two protection layers. In an
optional fourth step 204,
an additional layer of ink or other material may be deposited on top of the
protection layer 103.
[0045] With further reference to Fig. 2, additional steps may be employed
depending on
the end use for the film. For example, when using the film as a lidding
material for a blister pack,
in a fifth step 205, the multi-layer film 100 may be placed over the blister
pack. In practice, this
may be accomplished by unspooling/unwinding the multi-layer film 100 from a
roll and placing it
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in close proximity to a blister pack sheet 104 with wells 104 containing
product 105. As a sixth
step 206, the multi-layer film 100 with security elements 106 may be aligned
over the blister pack
shown in Figure 1 in such a fashion so that security elements 106 are aligned
with wells 104.
Finally, an activation energy (heat, UV rays, microwaves, mechanical pressure,
etc.), such as
heat applied from a heating plate/platen, is applied as a seventh step 207
sealing the multi-layer
construct 100 to blister pack.
[0046] It is further to be understood that the above description is
intended to be illustrative,
and not restrictive. For example, the above-described embodiments (and/or
aspects thereof) may
be used in combination with each other. Additionally, many modifications may
be made to adapt
a particular situation or material to the teachings of the invention without
departing from its scope.
[0047] In contrast to existing systems/methods, the multi-layer film
disclosed herein allows
for the use of security elements in blister packs and other applications
without the need for
customized tooling, molds, or manufacturing devices (such as specialized
heating plates). This
decreases the overhead required to start a manufacturing process and increases
the overall utility
of a multi-layer film.
[0048] Finally, the written description uses examples to disclose the
invention, including
the best mode, and also to enable any person skilled in the art to practice
the invention, including
making and using any devices or systems and performing any incorporated
methods. The
patentable scope of the invention is defined by the claims, and may include
other examples that
occur to those skilled in the art. Such other examples are intended to be
within the scope of the
claims if they have structural elements that do not differ from the literal
language of the claims, or
if they include equivalent structural elements with insubstantial differences
from the literal
language of the claims.
[0049] Since certain changes may be made in the above-described
invention, without
departing from the spirit and scope of the invention herein involved, it is
intended that all of the
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subject matter of the above description shown in the accompanying drawings
shall be interpreted
merely as examples illustrating the inventive concept herein and shall not be
construed as limiting
the invention.
