Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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COUNTERFEIT-RESISTANT, METAL-FORMED IMAGES AND
SECURITY DEVICES AND SECURITY DOCUMENTS EMPLOYING SAME
RELATED APPLICATION
[0001] This application claims priority from U.S. Provisional Patent
Application
Serial No. 60/559,583, filed April 5, 2004.
FIELD OF THE INVENTION
[0002] This invention relates generally to counterfeit-resistant, metal-formed
images for use with security documents such as banknotes and the like. In
particular, the invention is directed to metal-formed images that are
difficult (if not
impossible) to effectively simulate using metallic inks, foil transfer, or hot
stamping
techniques. Security devices that employ at least one such metal-formed image
are
also considered part of the subject invention as are security documents that
have at
least one metal-formed image located on a surface thereof or that have at
least one
security device at least partially embedded therein or mounted thereon.
BACKGROUND OF THE INVENTION
[0003] Security threads are used extensively in banknotes and other
documents of high value, providing visual and/or mechanical means for
verifying the
authenticity of these documents. Generally constituting a metallized polyester
strip
measuring between 1.0 and 5.0 millimeters in width, these threads are
chemically
etched to form indicia that are readily discernable in reflective and/or
transmitted
light. Security threads may be either fully or partially embedded in these
documents.
For partially embedded security threads, the threads are embedded into paper
during manufacture and alternately rise to the surface of the paper at regular
intervals. These so-called "windowed" threads can be found in banknotes
throughout the world and are therefore a target of simulation by
counterfeiters. In
fact, it is generally known in the banknote industry that counterfeiters
simulate the
surface portions of the "windowed" security threads by applying metallized
foil to the
surface of the counterfeit.
[0004] One such metal foil simulation technique uses a conventional laser
printer to print the intended foil pattern on the surface of the counterfeit.
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Conventional, adhesiveless metallized artistic foils can be applied to the
pattern and
heated with a heating element such as a household iron. Under heat, the laser
printer's toner acts as an adhesive, pulling the metal layer from the foil
carrier
according to the printed pattern. As the foil is pulled away from the surface
of the
counterfeit, the silvery metallic surface of the foil adheres only to the
printed areas
simultaneously reproducing the simple text and patterns and reflective
appearance
of typical demetallized security threads. This technique can be further
enhanced by
using commercially available, color variable, novelty films to simulate color-
shifting or
holographic windowed security threads.
[0005] Alternatively, counterfeiters have been known to produce hot stamping
dies according to the desired pattern and then foil stamp counterfeit
documents
using traditional hot stamp materials and methods.
[0006] The present invention serves to frustrate or defeat these ongoing
attempts by counterfeiters to replicate the appearance of security threads in
"windowed" banknotes by providing a metal-formed image that is difficult (if
not
impossible) to effectively simulate using metallic inks, foil transfer, or hot
stamping
techniques.
[0007] Also being provided by way of the present invention is a counterfeit-
resistant security device that employs or displays one or more such metal-
formed
images, as well as a security document having one or more such metal-formed
images located on a surface thereof or that have one or more such security
devices
at least partially embedded therein or mounted thereon.
SUMMARY
[0008] The present invention more specifically provides a metal-formed image
that incorporates one or more visible patterns of alternating metal and metal-
free
regions that may take the form of lines, dots, swirls, or combinations
thereof, wherein
when the metal-formed image is simulated using metallic inks, foil transfer,
or hot
stamping techniques; ink or foil bridges and/or is missing from portions of at
least
some of the metal regions of the visible patterns) thereby rendering portions
of the
simulated image indistinct or blurred.
[0009] In a preferred embodiment, the visible patterns) comprises alternating
metal and metal-free lines, the width of the metal-free lines within the
patterns)
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ranges from about 0.05 to about 0.10 millimeters, while the frequency of metal-
free
lines ranges from about 4 to about 14 lines per millimeter (i.e., line
frequency equal
to from about 0.07 to about 0.25 mm).
[0010] The present invention also provides a counterfeit-resistant,
demetallized security device that comprises: a carrier substrate having
opposing
planar surfaces; and at least one metal-formed image, as described above,
located
on at least one surface of the substrate.
[0011] The present invention further provides a security document that
employs at least one metal-formed image and/or at least one counterfeit-
resistant,
demetallized security device, both as described above.
[0012] Other features and' advantages of the invention will be apparent to one
of ordinary skill from the following detailed description and accompanying
drawings.
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. All publications, patent applications, patents and
other
references mentioned herein are incorporated by reference in their entirety.
In case
of conflict, the present specification, including definitions, will control.
In addition, the
materials, methods, and examples are illustrative only and not intended to be
limiting.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] Particular features of the disclosed invention are illustrated by
reference to the accompanying drawings in which:
FIG. 1 is a top plan view of a preferred holographic embodiment of a
security thread according to the present inventive, on an enlarged scale, as
seen in
transmitted light, showing negative or reverse-image letters having a pattern
of metal
and metal-free lines incorporated therein, while FIGS. 1A and 1 B are partial
top plan
views of the FIG. 1 security thread, both on an enlarged scale, detailing the
appearance of the thread when viewed at different angles in reflective light;
FIG. 2 is a top plan view of another preferred embodiment of the
present inventive security thread, on an enlarged scale, as seen in either
transmitted
or reflective light, showing letters that have a crosshatch pattern of lines
incorporated
therein, and metal numbers surrounded by a fine metal-free outline; and
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FIG. 3 is a pictorial representation of an attempt to simulate the
security thread of FIG. 1 using conventional foil transfer or hot stamping
techniques.
BEST MODE FOR CARRYING OUT THE INVENTION
[0014] The metal-formed images of the present invention increase the
effectiveness without compromising the fundamental advantages of demetallized
security devices (e.g., security threads) and security documents (e.g.,
banknotes).
By carefully studying foil transfer and hot stamping techniques, as well as
metallic
ink printing techniques, the present inventors have determined the limitations
(i.e.,
dimensional breakpoints) of these techniques and using this information, while
balancing readability and production °feasibility, have designed finely
resolved
demetallized patterns or images that are difficult (if not impossible) to
effectively
simulate. In fact, any attempt at imitation or replication by means of
metallic inks, foil
transfer or hot stamping will result in a simulation that is readily
discernable (by the
untrained and naked eye) from the original (or authentic) security device or
security
document in that the aesthetics of the security device or document are
distorted,
omitted or otherwise completely destroyed in the simulation.
[0015] Also considered by the present inventors was the ability of the
inventive metal-formed image to function effectively as an optical reflector
in
"windowed" security papers or banknotes. As is well known to the skilled
person,
metal layers may serve as optical reflectors in numerous optically variable
devices
(OVD and DOVD) and interference filter optical devices. It was therefore
deemed
advantageous for such applications to preserve as much of the metal as
possible
while incorporating demetalization features.
[0016] As noted above, the metal-formed images of the present invention
incorporate one or more visible patterns of alternating metal and metal-free
regions
which may take the form of, for example, complex or simple patterns of lines,
dots,
swirls, or combinations thereof. The resolution and spacing of each component
of
the patterns) are chosen to avoid effective simulation by metallic inks, foil
transfer
and hot stamping techniques. More specifically, when the metal-formed image is
simulated using these techniques, metallic ink or foil will bridge or link
and/or will be
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missing from portions of at least some of the metal regions of the visible
pattern(s).
As a result, portions of the simulated image become indistinct or blurred.
[0017] Examples of metal or metallic materials, which are suitable for use in
forming the counterfeit-resistant images of the present invention, include,
but are not
limited to, aluminum (AI), chromium (Cr), cobalt (Co), copper (Cu), gold (Au),
iron
(Fe), nickel (Ni), silver (Ag), or alloys of two or more of the aforementioned
materials.
In a preferred embodiment, the metal or metallic material is aluminum.
[0018] For those embodiments of the counterfeit-resistant images that
incorporate alternating metal and metal-free lines, the width of the metal-
free lines
within the patterns) ranges from about 0.05 to about 0.10 millimeters (mm)
(preferably, from about 0.06 to about 0.07 mm); while the metal-free line
frequency
ranges from about 0.07 to 0.25 mm (preferably, from about 0.16 to about 0.17
mm).
[0019] In one such embodiment, the metal-formed image comprises negative
or reverse-image characters (e.g., symbols, letters and/or numerals) that have
one
or more patterns of alternating metal and metal-free lines incorporated
therein. For
this embodiment, metal-free line frequencies that fall below the lower end of
the
noted frequency range (i.e., < 0.07 mm) cause the character or text areas to
appear
grayish similar to forgeries produced by metallic inks, while metal-free line
frequencies that exceed the upper end of the noted frequency range (i.e, >
0.25 mm)
cause the character or text areas to appear as traditional negative text (as
shown
and described in U.S. Patent No. 4,943,093 to Melting et al.) and thus prone
to
simulation via metallic ink and foil transfer.
[0020] In another such embodiment, the metal-formed image comprises
positive characters that are formed by the one or more patterns of alternating
metal
and metal-free lines. For this embodiment, metal-free line frequencies that
fall below
0.07 mm cause the character or text areas to appear as traditional positive
text (as
shown and described in U.S. Patent No. 4,652,015 to Timothy T. Crane) and thus
more susceptible to simulation via metallic ink and foil transfer, while metal-
free line
frequencies that exceed 0.25 mm render the character or text areas difficult
to
visually detect and decipher.
[0021] For those embodiments that incorporate metal or metal-free dots, the
diameter of the dots within the patterns) ranges from about 0.05 to about 0.10
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millimeters, while the density (e.g., dots per inch) is selected such that the
dots do
not touch yet are close enough together to thwart simulation using metallic
ink, foil
transfer and hot stamping techniques.
[0022] The counterfeit-resistant images of the present invention may be used
alone, or in combination with, for example, optical marks, on a surface of a
banknote
or any document or means of identification for authentication purposes. In one
such
contemplated embodiment, the inventive images are formed on a release-coated
transfer film or sheet (typically, a metallized foil provided on a release
coated
polyester carrier film) and then transferred from the film or sheet onto a
surface of a
banknote or other security document using conventional transfer techniques. In
another such contemplated embodiment, the inventive images are formed on
optical
marks (e.g., diffractive gratings, hologram structures) contained on a release-
coated
transfer film or sheet (typically, a holographic foil secured to a release
coated
polyester carrier film) and the resulting combination transferred from the
film or sheet
onto a surface of a security document.
[0023] The counterfeit-resistant images of the present invention may also be
non-releasably or permanently formed on a surface of a plastic carrier
substrate
(e.g., a security strip or thread) and then used with banknotes or other
security
documents.
[0024] Referring now to the figures, in detail, the security device of the
present
invention is shown generally at 10, and basically comprises: a carrier
substrate 12
having opposing planar surfaces; and at least one metal-formed image 14
located on
at least one surface of substrate 12.
[0025] Carrier substrate 12 is a light-transmitting carrier substrate that has
a
thickness ranging from about 12 to about 26 microns (preferably from about 17
to
about 21 microns). Preferably, substrate 12 is formed using one or more
essentially
colorless polymers selected from the group of polyester, polypropylene,
polyethylene, polyethylene terephthalate, and mixtures thereof. In a more
preferred
embodiment, carrier substrate 12 is a polyester film.
[0026] In another preferred embodiment, carrier substrate 12 is colored and/or
luminescent and, in yet another preferred embodiment, substrate 12 contains
optical
marks such as diffractive gratings and/or hologram structures.
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[0027] Further to the above, carrier substrate 12 preferably provides adhesive
properties to bond security device 10 into or onto a security document such as
paper.
[0028] In one preferred embodiment, which is shown in FIG. 1, security device
10 is a security strip or thread that comprises: a carrier substrate 12 having
opposing planar surfaces; at least one metal-formed image 14 located on one
surface of substrate 12; and a holographic relief pattern (not shown) formed
on an
opposing surface of substrate 12. The metal-formed image 14, as viewed in
transmitted light, is made up of negative or reverse-image letters that have a
pattern
of alternating metal and metal-free lines 16, 18, incorporated therein.
[0029] Due to the presence of the holographic relief pattern, and as best
shown in FIGS. 1A and 1B, two different images will appear when this preferred
embodiment of security device 10 is viewed at different angles under
reflective light.
[0030] In another contemplated embodiment (not shown), security device 10
is a security strip or thread that comprises: a carrier substrate having a
holographic
relief pattern formed on a surface thereof;. and at least one metal-formed
image
formed on the holographic relief pattern.
[0031] FIG. 2 shows another preferred embodiment of security thread 10 that
does not employ a holographic relief pattern. In this embodiment, metal-formed
image 14, as seen in either transmitted or reflective light, consists of
letters that have
a crosshatch pattern of lines incorporated therein, and metal numbers
surrounded by
a fine metal-free outline. Security thread 10 also displays a series of
interruptions or
breaks 20 in the metal contained on substrate 12. As amply described in U.S.
Patent No. 5,486,022, the pattern of metal regions formed by these
interruptions or
metal breaks define a machine-readable code that provides yet a further means
for
verifying the authenticity of a banknote or other security document containing
the
thread, as well as a means for denominating the banknote.
[0032] In yet another preferred embodiment (not shown), image 14 consists of
letters and numbers that are formed by a pattern of metal dots.
[0033] The security device 10 of the present invention may include additional
layers, coatings, or devices; provided however that any such additional layer,
coating, or device does not interfere with the visual perception of the
information
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conveyed by way of the metal-formed image 14, and/or the signals seen by
authenticity testing devices. Contemplated additional layers, coatings, or
devices
include, but are not limited to, magnetic layers, two-dimensional arrays of
non-
cylindrical lenses that serve to enlarge metal-formed image 14 (and
optionally, to
also affect the image's rotation, orthoparallactic movement, and/or apparent
visual
depth), optically variable devices, interference filter optical devices, outer
protective
layers, light-transmitting adhesive layers on either or both sides of device
10 that
facilitate the incorporation of the device 10 into or onto security documents,
and
fluorescent coatings made up of eosin, fluorescein, fluorspar, fuchsin,
sulphate of
quinine, calcium sulphide, Neodymium salicylate, Samarium gluconate, Yttrium
salicylate and the like.
[0034] In a preferred embodiment, security device 10 employs an outer
protective layer. The outer protective layer is a light-transmitting
protective layer that
may take the form of a protective film having a thickness ranging from about
3.0 to
about 12.0 microns (preferably from about 3.0 to about 6.0 microns) or a
printed
coating having a thickness ranging from about 1.0 to about 6.0 microns.
[0035] More preferably, the protective layer is formed using one or more
essentially colorless polymers selected from the group of polyester,
polypropylene,
polyethylene, polyethylene terephthalate, and mixtures thereof. In a most
preferred
embodiment, the protective layer is a laminated polyester film.
[0036] In another more preferred embodiment, the protective layer is colored
and/or luminescent and, in yet another more preferred embodiment, the
protective
layer provides adhesive properties to bond the security device 10 into or onto
paper.
[0037] The outer protective layer may be laminated to the metal layer by using
the light-transmitting adhesives described above.
[0038] Security device 10 may be manufactured using conventional
techniques. For example, the security thread shown in FIG. 1 may be
manufactured
by:
a) embossing or coating a relief pattern on one surface of a
polymeric (e.g., polyester) film;
b) coating an opposing surface of the polymeric film with a metal
(e.g., aluminum) layer;
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c) coating the metal layer with a resist material except where the
metal-free lines 18 (within each negative or reverse-image character) are to
be formed; and
d) applying a chemical to the printed metal layer to remove the
metal layer except where protected by the resist, so that the metal-free lines
18 become transparent regions in the opaque reflective metal surface.
[0039] By way of further example, when the metal-formed image 14 comprises
positive characters formed by the pattern of alternating metal and metal-free
regions
(e.g., lines, dots, swirls, or combinations thereof), the metal layer is
coated with resist
so as to protect the metal layer only in those regions in which the metal
regions of
the patterns) are to appear in the final thread.
[0040] The resist is preferably applied by a printing process such as flexo
printing, rotogravure or silk screening.
[0041] As noted above, any attempt to simulate the security device 10 of the
present invention using metallic inks, foil transfer or hot stamping
techniques will
result in a simulation that is readily discernable (by the untrained and naked
eye)
from the original device. As best shown in FIG. 3, which is a pictorial
representation
of an attempt to simulate the security thread of FIG. 1 using foil transfer or
hot
stamping techniques, the aesthetics of the thread are distorted by metal
bridging the
fine metal lines of the pattern within each letter. This effect results from
the inability
of the foil to transfer cleanly.
[0042] The security document of the present invention is preferably a security
paper and the security device 10, which is preferably in the form of a
security thread,
is either wholly or partially embedded within the paper. For partially
embedded
threads, portions thereof are exposed at the surface of the paper at spaced
intervals
along the length of the thread at windows or apertures in the paper.
[0043] As alluded to above, the security thread 10 may be at least partially
incorporated in security papers during manufacture by techniques commonly
employed in the papermaking industry. For example, the inventive thread 10 may
be
fed into a cylinder mold papermaking machine, cylinder vat machine, or similar
machine of known type, resulting in total or partial embedment of the thread
within
the body of the finished paper.
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[0044] In addition to the above, the security device 10 of the present
invention
may be mounted on the surface of security papers either during or post
manufacture.
Mounting of the device 10 may be achieved by any number of known techniques
including: applying a pressure-sensitive adhesive to a surface of the device
10 and
pressing the device 10 to the surface of the paper; and applying a heat
activated
adhesive to a surface of the device 10 and applying the device 10, using
thermal
transfer techniques, to the surface of the paper.
[0045] While various embodiments of the present invention have been
described above, it should be understood that they have been presented by way
of
example only, and not limitation. Thus, the breadth and scope of the present
invention should not be limited by any of the exemplary embodiments. w
[0046] Having thus described the invention, what is claimed is:
