Note: Descriptions are shown in the official language in which they were submitted.
CA 02669200 2009-06-12
CONTROL OF ELECTROMAGNETIC SIGNALS OF COINS THROUGH MULTI-PLY
PLATING TECHNOLOGY
The present patent application claims the priority of United States Patent
Application No.
61/061,287 filed June 13, 2008, which is hereby incorporated by reference.
FIELD OF THE INVENTION
[0001] The present invention relates to novel metallic composites that are
suitable as
coinage materials for the minting industry. More particularly, the present
invention is
directed to metallic composites designed for the specific purpose of affecting
their
electromagnetic properties, in particular their electromagnetic signature
(EMS), and
includes a method of making coins as well as the coins themselves.
BACKGROUND OF THE INVENTION
[0002] Coins are commonly used as a means of payment in vending or similar
automatic
machines. In this function, the coin needs to be recognized and identified by
the machine
and either accepted or rejected. This discrimination process is carried out by
a device
called a coin acceptor and generally consists of measuring various physical
properties of
the coin as it move's through the acceptor's mechanism.
[0003] Most coin acceptors presently in use rely on signals that result when a
coin disturbs
a variable electromagnetic field. For example, a coin moves between two coils
acting as
emitting and receiving antennae, respectively. The signal picked up by the
receiving coil
is then analyzed using a proprietary algorithm to produce what is called an
electromagnetic signature (EMS) of the coin. Based on its EMS, the coin is
either
accepted or rejected.
[0004] A common problem affecting coin acceptors is the fact that
electromagnetic
signatures (EMSs) may be very similar for different coins. When the EMSs of
coins of
different denominations or coins issued in different jurisdictions are
similar, there is an
opportunity for fraud.
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[0005] As referenced above, EMS values are not calculated by any physical,
chemical or
mathematical formula. Rather, they are a set of numbers generated by software
and
algorithms devised by each coin acceptor mechanism manufacturer. EMSs are unit-
less
and are made up of a set of figures which are purported to determine the
diameter, the
edge thickness, the weight, the alloy composition, etc., of a coin at
different frequencies.
Moreover, these values are not single repetitive values which identify the
characteristics of
the coin. Rather than being exact; the values vary from coin to coin within a
certain range.
Accordingly, that range is critical for coin acceptor manufacturers, since
even perfectly
valid coins may be rejected. The range of values must therefore be established
so as to
properly characterize the specific properties that identify the particular
features of a coin,
such as its diameter, edge thickness or alloy.
[0006] Perhaps one of the best ways to relate an EMS to a known physical
measurement
is through the metal's conductivity. Commercial instruments are available to
measure
conductivity, such as the Dr. Foerster'STM Sigma D conductivity meter and the
Fischer
Sigmascope SMP10 conductivity meter.
[0007] With base metals increasing in price over the last 30 years, people
working in the
minting industry have come up with ideas on how to reduce the cost of
producing coins,
including finding metal substitutes for more expensive base metals, such as
nickel and
copper. Substitutes include mono-ply plated steel products. Mono-ply plated
steel
consists of plating a single layer of a metal or an alloy over steel. This is
to be
distinguished from multi-ply plated steel, which consists of plating several
layers on steel.
[0008] Sample patent applications and patents that describe mono-ply plated
steel include
the following: Canadian Patent Application No. 2,137,096, Canadian Patent No.
2,271,654, United States Patent No. 4,089,753, United States Patent No.
4,247,374 and
United States Patent No. 4,279,968. Alternatives include coins in which the
core is made
of a metal, such as nickel or copper, which is mono-ply plated with either
another metal or
an alloy. Sample patents of this type include United States Patent No.
3,753,669, United
States Patent No. 4,330,599 and United States Patent No. 4,599,270.
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[0009] Inconveniently, coin acceptor mechanisms in the vending industry often
cannot
differentiate between coins from different countries that are made of the same
alloy and
have approximately the same diameter, thickness and weight. In addition, mono-
ply
plated steel coins have EMSs that are so variable and so close to that of
steel that many
vending machines cannot be calibrated to differentiate between regular steel
and mono-
ply plated steel.
[0010] Metal disks, especially coins, have been produced so as to be
distinguishable and
separable from one another on the basis of their magnetic properties. As
proposed by
German Patent Application DE 3207822 and US Patent No. 3,634,890, laminate
metallic
claddings suitable for coin production include magnetizable metals (such as
nickel) as well
as non-magnetizable metals (such as a copper-nickel alloy containing 5 to 60
percent
nickel). Along the same lines, US Patent No. 4,973,524 describes a method of
making
coins that are a suitable as an alternative to nickel- containing coins, the
method
comprising the steps of forming a laminated composite comprising a core layer
of a first
corrosion-resistant steel, such as ferritic-chromium steel, and cladding
layers on opposite
sides of this core layer with a second corrosion-resistant steel, such as
austenitic nickel-
chromium steel.
[0011] Despite the above, counterfeiters are actively finding ways to get past
the electronic
devices used in vending machines, and therefore fraud continues to be a major
problem.
There thus remains a need for novel coins that combine metals that are favored
by
manufacturers of legal tender but that may be discriminated on the basis of
their EMSs.
[0012] The present invention seeks to meet this and related needs.
SUMMARY OF THE INVENTION
[0013] The shortcomings associated with current coin technology can result in
a breach of
security and revenue when vending machines cannot distinguish coins from two
different
countries, or when the vending machines cannot differentiate between a mono-
plated
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steel coin and a steel slug. In order not to jeopardize the vending machine
industry, many
coin acceptors simply do not accept any mono-ply plated steel coins.
[0014] The present invention provides an alternative to coinage materials that
are currently
available. Specifically, the present invention relates to novel multi-ply
metallic composites
and their use in the manufacture of coins.
[0015] On the condition that one or more of the plated layers is/are non-
magnetic if the
core is steel or made of another magnetic material such as nickel, or on the
condition that
the plated layer is of a magnetic material if the core is non-magnetic, the
intensity of the
induced current can be modulated through the control of the thickness of the
layers of the
paired combination of magnetic and non-magnetic materials in such a way that
the coin
will generate totally different induced current features. This permits coin
acceptor
mechanisms to differentiate, recognize and identify coins as being different,
even though
they may have the same or a very similar diameter, thickness and weight. The
ability to
discriminate two coins having the same physical features even though they have
different
designs is a unique and very powerful tool to control the misuse of coins of
one country in
another country. Unlike human beings, coin acceptor mechanisms in their
present
technological state do not look at the visual or graphical features of coins
to identify them.
As indicated above, acceptor mechanisms work on current waveform data and
defined
feature points.
[0016] It has been found that by judiciously choosing the type of metals
deposited through
electrogalvanic (plating), and by manipulating the plating deposit thicknesses
of the metal
layers, the type of induced current generated by a coin can be modulated. If
one or more
of the plated layers are non-magnetic, and the core is made of a magnetic
material such
as steel or nickel, the intensity of the induced current can be modulated.
Alternatively, if
one or more layers are magnetic, and the core is made of a non-magnetic
material, such
as copper, zinc, tin, aluminum, silver, gold, indium, brass or bronze, the
intensity of the
induced current can also be modulated. Specifically, by controlling the
thickness of the
layers of the paired combination of magnetic and non-magnetic materials, the
coin will
generate completely different induced currents, which in turn allow coin
acceptor
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mechanisms to distinguish coins even though they may have the same diameter,
thickness and either an identical or similar weight.
[0017] Single layer plating, particularly with metals having magnetic
properties, such as
nickel and cobalt, was found to have inherent limitations that render
manipulation of the
EMS of a coin difficult, even by modifying such features as the coin's
thickness.
[0018] With all of the above in mind, the present invention provides:
1) A multi-ply plating process that produces metallic composites which
overcome the
problem of being unable to differentiate between two coins comprising the same
alloy and of the same size;
2) A multi-ply plating process that produces metallic composites which
overcome the
inability and the difficulty of calibrating vending machines precisely and
accurately
in order to recognize a mono-ply steel plated coin, particularly when the
plated
material is magnetic such as nickel or cobalt.
3) A multi-ply plating process that prevents counterfeiting of coins made of
plated
materials because the order of the clad metal layers and the plating
thicknesses of
the layers can be defined and controlled in a reproducible manner in order for
the
coin to generate the same induced current, that is, the same EMS.
4) A multi-ply plating process that produces metallic composites whereby the
core
may be steel over which nickel and then a non-magnetic metal such as copper,
or
brass, or bronze can be deposited as a layered pair, and the EMS is controlled
by
defining the thickness of the deposited metal layers.
Alternatively, the magnetic and non-magnetic pair may be plated in the reverse
order, that is, copper over steel followed by nickel. The key is in
controlling the
thicknesses of the layers of metals deposited.
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5) A multi-ply plating process whereby (1) a magnetic metal such as nickel or
cobalt is
plated over a magnetic steel core, then (2) a non magnetic metal such as, but
not
limited to, copper, brass, bronze or zinc is deposited and (3) an external
layer of
nickel is plated in order to control the electro-magnetic signal of the
metallic
composite product. This is achieved through control of the thicknesses of the
metals deposited. The external layer of nickel may be any other metal, either
magnetic (such as chromium) or non-magnetic, for visual color effect and/or
wear
resistance.
6) A multi-ply plating process whereby a magnetic metal such as nickel or
cobalt is
deposited over a non-magnetic metal core, such as copper, brass or bronze, to
form a paired magnetic and non-magnetic metal combination in order to control
the
EMS. This is achieved by controlling the thickness of the nickel or cobalt
that is
deposited.
7) A multi-ply plating process whereby (1) a magnetic metal, such as nickel,
is
deposited over a steel core, then (2) a non magnetic metal such as copper,
zinc,
brass, bronze is deposited, and (3) another layer of magnetic metal such as
nickel
is deposited. A final layer of silver or gold is deposited in order to control
the
electromagnetic signal of the composite product. This is achieved through
control
of the thicknesses of the metals deposited. The external layer of silver or
gold is
deposited to give a value-added appearance and to modify the conductivity or
the
color of the composite product combination (nickel - silver or nickel - gold),
in
addition to the first pair of magnetic - non magnetic combination (nickel-
copper).
[0019] Other objects, advantages and features of the present invention will
become
apparent upon reading of the following non-restrictive description of
embodiments thereof,
given by way of example only with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Figure 1: Conductivity of different metallic composites.
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[0021] Figure 2: Plating Processes (A) Single ply technology has one coating
of metal
over a steel blank, such as nickel over steel for white coins, copper over
steel for red coins
and bronze or brass over steel for yellow coins; (B) The Royal Canadian Mint
(RCM)
multi-ply technology utilizes more than one layer of coating, for example, in
the case of red
and yellow coins, nickel over steel followed by copper, bronze or brass,
depending on the
colour chosen for the coin; and (C) In one embodiment, the RCM multi-ply
technology
utilizes three layers for the production white coins, wherein the first layer
is nickel, the
second layer is copper and the third layer is nickel plated over the copper,
creating a
sandwich of layers.
[0022] Figure 3: EMSs of different metallic composites at 60KHz.
[0023] Figure 4: Copper layer and EMSs of Plated Blanks.
[0024] Figure 5: Correlation between copper thickness and the Internal
Conductivity 1
(IC1).
[0025] Figure 6: Conductivity analyses of IC1 by population.
DETAILED DESCRIPTION OF THE INVENTION
[0026] All coin acceptors are designed to work on the induction principle. A
coin acceptor
is designed to have live coils (sensors) under power at 2 or 3 different
frequencies
(normally, 2 frequencies, high (240KHz and higher) and low (60KHz and lower)).
The
coils are sufficiently removed from each other so that no significant current
is picked up by
a current analyser connected to the live coils.
[0027] When a coin is dropped into a coin acceptor, the (space) gap between
the coins is
quickly and temporarily closed and a current is induced as the coin goes past
the coils
(sensors). The inductance of the sensors combined with the eddy current in the
coin
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generates two (2) sinusoidal electric currents, due to two (2) different sets
of coils at two
(2) different frequencies.
[0028] The current analyser combines the 2 currents, which are then analysed
at various
points which are identified as EMS signals.
[0029] The captured EMSs are analysed with proprietary algorithms specific to
each coin
acceptor model and brand. The EMSs are converted to data identified as
parameters.
[0030] The EMSs are dependent on the size (diameter), mass (edge thickness and
weight) and type of metals (or alloys) used to make the coins.
[0031] Accordingly, coins of the same alloy and approximately of the same
diameter
cannot be differentiated by the coin acceptors. For example, the US five (5)
cent coin and
the Canadian five (5) cent coin (dated prior to 1999) are both made of
cupronickel (75%
copper 25% nickel) and cannot be differentiated by the existing coin acceptors
in the
market.
[0032] The shortcomings of today's coin recognition and discrimination
technology can
have serious consequences for the economy of a country. In the case of the US
(5) cent
and the Canadian (5) cent coins, the problem is accepted because their face
values are
approximately the same. For other countries, however, the economical
ramifications can
be very serious if their exchange rates are far apart, because if the coins of
two countries
are exactly or almost of the same diameter, size, thickness, weight and/or
same alloy,
they can be used interchangeably in vending machines. This opens the door to
fraud and
counterfeiting, because vending machine sensors do not rely on the pictorial
or visual
designs to recognize and to differentiate the coins.
[0033] The object of this invention is the creation of metallic composites
that are suitable
for coin production. The resulting coinage products are unique since they help
to
eliminate the problems associated with look-alike coins which have plagued
many
European, North American and Asian economies. Many nations have a broad base
of
automated merchandising services that rely in the use of coins, including
automatic candy
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machines, sandwich machines, telephones, soft drink dispensers, coffee
machines, public
or common transit services, parking meters, road tolls, casinos and gaming
machines.
The novel coins of the present invention should be useful for such services.
[0034] Since coin acceptors have different means and ways of capturing and
recording the
EMSs, the best way to illustrate and to explain the concept is to relate the
metallic
characteristics to its current conductivity measured in IACS% (international
annealed
copper standard percentage).
[0035] Figure 1 shows the typical conductivity of different alloys at
different frequencies.
The coin identification number (coin number 1 to coin number 80) appears on
the X axis
and conductivity of the metal measured in IACS% appears on the Y axis. The
measurements were done using a Dr. Foerster'STM conductivity meter at
different
frequencies.
[0036] Figure 1 shows that each metal product, for example, cupronickel or
stainless steel,
has its own conductivity at a fixed frequency. The product identified as RCM
(for Royal
Canadian Mint) Ni-Cu-Ni (5-15-5) is a product consisting of a low carbon steel
core (SAE
1006) plated with a layer of nickel of 5 microns, then a layer of copper of 15
microns, then
a final nickel layer of 5 microns.
The difference between single layer blanks and RCM Multi-layer Blanks is shown
in Figure
2. Canadian Patent No. 2,019,568 (Truong et al.), which corresponds to United
States
Patent No. 5,139,886 and United States Patent No. 5,151,167, describes an
electroplating
process that is suitable for the purposes of the present invention. All of
these patents are
hereby incorporated by reference.
[0037] Returning now to Figure 1, the RCM Multi-ply blanks (7.5-20-7.5) show
that they
have a small range of conductivity values, at the 60KHz frequency, between 20
and 28
IACS%. It will be recalled that the X axis represents a sample coin number.
Each coin
number has a IACS% value at a frequency. For example, coin 4 has a value of 24
IACS%
and coin 7 has a value of 22 IACS%. The small variation is due to the fact
that it is very
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difficult to control the exact thickness of plated nickel deposit and of
copper deposit
because the deposit is done through electro-galvanic plating, a process that
is known to
those of skill in the art. The plating deposit may vary somewhat from coin to
coin.
[0038] Figure 1 also shows that the product RCM Ni-Cu-Ni (15-2-15) has a
different range
of conductivity. It was plated with 15 microns nickel, 2 microns copper, 15
microns of
nickel.
[0039] Figure 3 shows the EMS of steel, of special multi-ply Ni-Cu-Ni RCM
plating and of
cupronickel at 60KHz.
[0040] In comparison, the EMS of a mono-layer of nickel on steel at 60 KHz
gravitates
around 110% IACS, which is the approximate EMS of steel. The range of values
reflects
the strong magnetic nature of steel and nickel. Practically speaking, the
variations
associated with mono-layer products are too numerous to be considered usable
by
vending machine manufacturers to calibrate coin acceptors. In addition, steel
cannot be
considered as a coinage material for the following reasons: it rusts, it is a
very common
material and if a coin is made of steel only, it may be readily counterfeited
by anyone
equipped to cut a steel disc of the correct size.
[0041] As indicated above, steel and nickel are magnetic, and nickel plated
steel is also
magnetic. In order to make a metal alloy less magnetic and in order to give it
a more
stable EMS signal so that it can be used in the ranges devised by vending
machine
manufacturers for calibration, one has to stabilize the EMS value within a
narrow range
desired by the vending industry.
[0042] A plated material that can substantially affect the electrical current
conductivity of a
coin and that can be changed by modifying the thickness of material provides
means for
controlling and varying the conductivity, and therefore, the EMSs of coins.
Furthermore, if
a metal can negate the effects of magnetism, the levels of magnetism can be
varied and
therefore EMS values can be modulated.
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[0043] Pure copper is very conductive, offers very low resistance to
electrical current flow
and is non magnetic. Other metals or alloys which can be considered for the
production of
coins are, without limitation, aluminum, zinc, tin, silver, gold, indium,
brass and bronze.
[0044] When a non-magnetic metal is plated over steel, the overall magnetic
value of the
paired "non-magnetic metal - steel" combination can be altered. This is an
important
consideration for the modulation of the magnetic intensity of a metallic
composite, allowing
flexibility in changing the EMS values of the metals formed. Moreover, by
varying the
thickness of the deposit of the non-magnetic metal layer over steel, various
degrees of
magnetism can be imparted to the combined non-magnetic - steel pair. These
significant
discoveries can serve as a powerful tool in the control of the EMS values of
coins and
hence, in the prevention of fraud.
[0045] In addition, the degree of electrical conductivity can significantly
influence the
intensity of the electrical current going through the non-magnetic -steel
pair. In other
words, the EMS of coins can be controlled through the judicious selection of
the thickness
of the metals or alloys, or combination of metals or alloys, deposited on
steel. For
example, by combining metals such as copper, nickel and steel, the magnetic
properties
and electrical conductivity of these metals can be advantageously combined to
change the
EMS of the resulting coins in order to give to each type of coin a range of
specific values
which can be used by coin acceptors to recognize, differentiate, discriminate
and
ultimately, to either accept or reject the coins.
EXAMPLE 1
[0046] To illustrate the control that can be exerted on the electromagnetic
signals of coins
of the present invention, a series of plating experiments were conducted.
Different
thicknesses of deposits of nickel and copper, in alternate layers, on steel
blanks were
made. The conductivity of the combined effect of the layers of nickel and
copper at
different frequencies was measured, and different results were obtained, as
anticipated.
[0047] Figure 4 illustrates the difference in the electro-magnetic properties
of metals by
combining layers of nickel and copper. Specifically, this graph shows the
resistivity of the
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multi-layered plated blanks as the level of copper content was varied while
the nickel
layers were held constant. The X axis shows the coin blank number while the Y
axis
shows the resistivity of the coins measured at 60KHz with a Dr. Foerster
conductivity
meter.
[0048] Each layer exerts a certain influence on the EMS of the coins.
Different metals
have different influences. Tests have shown that changes in the thickness of
the copper
layer appear to affect the EMS the most.
[0049] The trend of the electrical conductivity change is very clear from
Figure 4. Multi 2
(7-14-7) with 14 microns of copper has, on average, a lower resistivity than
Multi 3 (7-12-
7) with 12 microns of copper. Multi 1 (7-20-7) has the lowest average
resistivity with 20
microns of copper.
EXAMPLE 2
[0050] In another set of experiments, the EMS values of a large number of
coins were
recorded. These coins, which were plated by a multi-ply plating process such
as that
described in Canadian Patent No. 2,019,568 (Truong et al.), were allowed to
pass through
a commercial coin sorter, Scan Coin 4000 (Figure 5). The recorded values,
identified as
IC1 (internal conductivity at coil 1) were plotted against the thickness of
copper found by
cross-sectioning the coins, mounting the coins for metallographical
observation and
measuring optically the thickness of the different layers of copper and nickel
in the coins.
[0051] The internal nickel layer is fairly constant at 6 microns and the
external nickel layer
is approximately between 10 and 11.5 microns. The copper layer varies between
4 to 24
microns.
[0052] Figure 5 shows a direct correlation between the thickness of copper and
the IC1
values recorded by the Scan Coin sorter.
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EXAMPLE 3
[0053] In another series of experiments, three (3) different types of blanks
were plated with
the following arrangements of plating thickness conditions:
Thickness of Plating
Blank Type Inside Nickel Copper Layer Outside Nickel
Layer Layer
Sample 1(red plot 7/1 12 N 5 N
Sample 2 (green 7 N 19 N 5 N
plot)
Sample 3 (blue 7/1 26 /1 5 N
plot)
[0054] The blanks were minted into coins and the coins were passed through the
commercial ScanCoin coin sorter, model 4000, which measures the coin
conductivity.
[0055] Figure 6 shows the conductivity analysis by population on the X axis
while the coin
Y axis shows the conductivity values for all 3 samples. The 3 representations
(at the right
hand corner of Figure 6) are typical bell curve distributions of the same data
for the 3
types of blanks. Once again, it may be seen that as the thickness of the
copper layer is
changed, the conductivity of the coins also changes, and these differences
allow the coin
reader of the ScanCoin coin sorter to differentiate, to recognize and to sort
the coins.
[0056] It should be noted that, for all practical purposes, the differences in
the weights of
the 3 coins are not perceptible because a difference of a few microns of
copper is of the
order of 0.005g to 0.01 g.
[0057] This invention thus provides a very powerful tool to change the EMS of
coins. It is
quite unique since the process makes it possible to alter the electrical
conductivity of
metallic coins which is not possible with conventional metallurgical alloys.
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[0058] The practical uses of this invention are enormous since this method
provides
means to alter the physical and electrical properties of coins without having
to
substantially change alloy compositions. The process is unique, very
economical and
provides an excellent method to create different electromagnetic signals for
coin
differentiation which is not possible by other means.
[0059] Each alloy has its own EMS. A small change in alloy composition over 1
percent
does not change the EMS of the alloy. In multi-ply electroplating, it is
possible to change
the EMS of the metal product significantly by making a judicious change of the
order of a
few microns in the copper layer deposit which represents a change of less than
0.005
percent of the weight of the coin.
[0060] This concept applies to a deposit of 2 or more layers of metals, at
least one of
which is non magnetic, such as copper, zinc, tin, aluminum, silver, gold,
indium, brass or
bronze.
[0061] The above-described embodiments of the invention are intended to be
examples
only. Variations, alterations and modifications can be made to the particular
embodiments
described herein by those of skill in the art without departing from the scope
of the
invention, as defined in the appended claims.
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