Note: Descriptions are shown in the official language in which they were submitted.
CA 02179261 2003-02-03
COIN DISCRI1VBNATOR
Field of the Invention
This invention relates to a method and apparatus for discriminating between
coins,
Tokens or similar articles.
Background of the Invention
Coin-ope~raud apparaws are being increasingly used throughout the world to
provide goods and servicxs. Such apparatus includes amusement machines,
vending
machines for a wide variety of products, gaming machines (such as "poker
machines") and
PaY Phones.
As a sub-group, vending machines dispensing such varied products as public
transport tickets, confectionery, video cassettes and bread sticks are
increasingly apparent
in developed countries due to the high cost of labour and a demand for twenty-
four-hour
access to such products.
In addition, public telephones or pay phones arc becoming more sophisticated.
Although. there is a trend towards pay telephones which operate only on a
debit card or
credit card, it is likely that future pay telephones will be modelled on those
currently in use
in Italy, in which one may use coins, cards or gettoni (telephone tokens).
Although there are in use banknote validators, the problems inherent in
"reading"
banknotes (particularly mutilated or worn banknotes) coupled with the trend in
most
countries to replace lower denomination banknotes with coins, means that in
all of the
abovementioned applications, a coin validator will be required.
To be acceptable in one of the abovementioned applications, a coin
discriminator
must quickly and accurately discriminate between coins of different
denominations, between
coins of different countries and between genuine coins and bogus coins.
Existing coin
discriminators have been unable to discriminate adequately, in some cases,
between a low
value coin of a foreign country and a higher value coin of the country in
which the validator
is located. Particularly in a region such as Europe, coin discriminators
additionally cannot
cope with the large number of migratory coins from various European countries.
One example of a prior art coin validator is provided by US-A-3,918,565, which
discloses coin selection methods and apparatus in which data representative of
a coin is
compared with data stored in a programmable memory.
In US-A-3,918,565, a numerical value of a signal produced by interrogating a
coin,
such as frequency, is compared with acceptable numerical values for genuine
coins which
are stored is the programmable memory.
CA 02179261 2003-02-03
A
2
Another prior art coin.validator is disclosed in AU-B-24242J84, which
discloses the
use of pulsing coils which indux eddy ~cturents in a coin. Monitoring means is
used to
monitor the decay of the eddy curnents, and a comparison between the output of
the
monitoring means and stored refennoe values, enable discrimination to take
,place. It is
considered that the approach of AU-B-2424?l84 is unnecxssarily complicated,
and would
not permit as adcgustely rapid discrimination to take place. .
In U.S. Patent 5,020,653 to Shimizu there is disclosed a device for
discriminating
between different coins, such a real or counterfeit coins, without contacting
the coins.
Shimizu uses a coil to provide a pulse of a magnetic field into the coin, and
then detects the
decaying curve of the back F.1VIF created by the eddy currents is the coin.
The
characterstics of that decaying curve are determined by the material of the
coin, its
diameter and thickness, and any surface treatement. Therefore, for non-
identical coins, the
decaying curves are also non-identical.
After detecting the decaying curves Shimizu then subjects the decaying curve
to
. series of manipulations prior to comparing the characteristics of the
decaying curve with
the known characteristics for known coins. Those manipulations include the use
of a
switched-gain amplifier, and an analogue-to-digital converter. Also, Shimizu
uses a binary
counter to determine the end of each cycle so the amplification factor can be
increased for
the following half cycle.
This creates an analysis regime which is unnecessarily complex. It also means
that
the inherent characteristics of the decaying curve are not used, but rattarr a
digital signal
derived from a modified form of the curve. In this way, certain inherent
characteristics of
the coin being tested may not as accurately be determined. Furthermore, with
Shimizu, an
amplified and digitised repr~es~entation of the decaying waveform is fed into
the
microprocessor for direct comparison with the known waveforms of particular
coins.
In Australian Patent Application No. AU81826191, another approach is disclosed
using pulsing of coins. In particular, it included the steps of, (i)
energising detect coils,
with a single pulse, between which at least part of a coin is located, (ii)
extracting from at
least one portion of the back EMF curve of the decaying pulse information to
provide a
definiti~ of the coin, each portion of said back F.1VIF curvt being ink and
amplified,
and (iii) comparing in a microprocessor the definition of the coin with a
reference
de5nition, to determine whether the coin is acceptable or unacceptable. The
definition is in
the form of a period of time, or a number of system clock counts, which counts
represent a
period of time. The period of time relates to the time between a predetermined
time,
between the de-energisation of said coils, and the intersection of said back »
curve with
a reference voltage.
CA 02179261 2003-02-03
3
The inversion and amplification of the back EMF curve was required to produce
a
measurable signal capable of properly being used for validation purposes.
However in so
manipulating the curve, its ability to discriminate between extremely similar
coin types is
Further investigations have bean directed to optimising this type of
discrimination
method with emphasis oa the significance of the back E1VlF oscillation curve.
DesQIption of a Preferred Form of the Invention
In one prefetnd fona of the invention an unmodified back emf oscillating
waveform from a single pulse of a token/coin is used to provide information
for
discriminating coinshokeas. The unmodified back emf oscillating waveform is of
increased
significance in discrimination as it does not have important distinguishing
characteristics
excluded by subsequent manipulation of the type currently known. Preferably,
and in direct
contrast to Shimi~zu, from the unmodifed decaying wave are extracted a number
c~f
variables which are processed to provide values proportional to those
variables, with those
IS values being fed into a microprocessor for comparison with the
corresponding values of
those variables for coins of known denomination stored in the microprocessor
to enable the
category of the coin under test to be determined. Advantageously, the values
are time
values.
In particular, an improved method of coinltoken discrimination is possible by
non
dampening of decay oscillation of the detect coil field. Such reference data
being
assembled on the basis of the unmodified oscillating waveform can be
representative of a
particular type of coin/tokea to the exclusion of very similar other
coins/tokens.
Particularly characteristic data may be extracted from the unmodified back emf
oscillating waveform to enhance discrimination between coins/tokens. Such
characteristic
data for a coid'tohen may include:
(i) superimposing a mean amplitude curve;
(ii) the phase and/or change in phase of each oscillating waveform;
)
(a) the curves plotted by the peaks of either or both of the positive andlor
negative
portions of the oscillating waveform; and
(b) the amplitude of the negative andlor positive peaks of each oscillating
waveform;
(iv) the an-,a of the curves beneath the peaks of each oscillating waveform;
(v) the frequency and/or change in frequency of each oscillating waveform;
(vi) the decay of peaks of each oscillating waveform in a predetermined-time;
and
(vii) any combination of the above.
CA 02179261 2004-10-26
4
Accordingly by analysing such details a refined signature can be attributed to
a type
of coin/token. By allowing appropriate variation, it is possible to accurately
discriminate
between coins/tokens.
More specifically, one aspect of the invention provides a method of validating
S coins/tokens, including the steps of:
(a) energising detect coils, between which at least a part of a coin/token is
located, with a
single pulse,
(b) detecting the back EMF curve of the decaying pulse information to provide
a
definition of said coin/token, said back EMF curve being substantially
unmodified,
(c) comparing said definition of said coin/token with at least one of a number
of
reference definitions to determine into which category of a number of pre-
determined
categories said coin/token falls.
In accordance with another aspect of the present invention, there is provided
a method
of categorizing coins/tokens, including the steps of:
(a) energizing detect coils, between which at least part of a coin/token is
located,
with a single pulse,
(b) detecting the unmodified back EMF curve of the decaying pulse,
(c) analysing said unmodified back EMF curve to measure at least one
characteristic of said unmodified back EMF curve, and
(d) comparing said at least one characteristic with the corresponding
characteristics) of a reference unmodified back EMF curve to determine
therefrom into
which category of a number of predetermined categories said coin/token falls.
In accordance with another aspect of the present invention, there is provided
a method
of categorising coins/tokens, including the steps of:
(a) energising detect coils, between which at least a part of a coin/token is
located, with a single pulse,
(b) detecting the back EMF curve of the decaying pulse,
(c) analysing the unmodified back EMF curve to extract therefrom values
representative of a number of variables, and
(d) comparing said values of said coin/token with a number of reference values
to determine into which category of a number of pre-determined categories said
coin token
falls; said comparison being made using the formula
V(t)=Ae-QT sin (Wr+-cE)+Be-ar
wherein:
V(t) is the voltage at time t
CA 02179261 2004-10-26
4a
A is the amplitude of the oscillating waveform
B is the amplitude of the direct current component
d~ is the phase angle of the response triggering delay
ca is 2~rf
f is the frequency of oscillation
Q is the decay associated with the oscillating waveform
a is the decay associated with the direct current component.
In accordance with another aspect of the present invention, there is provided
a method
of categorizing coins/tokens, including the steps of:
(a) energizing detect coils, between which at least part of a coin/token is
located,
with a single pulse;
(b) detecting the back EMF curve of the decaying pulse;
(c) analysing the unmodified back EMF curve to extract therefrom values
representative of one or more variables; and
(d) comparing said values of said coin/token with at least one of a number of
reference values to determine into which category of a number of predetermined
categories
said coin/token falls, wherein the step of analysing the unmodified back EMF
curve
comprises the steps of:
comparing said unmodified back EMF curve to a reference unmodified back EMF
curve; and
determining said values by calculating the difference between values
representative of
said one or more variables corresponding to said unmodified back EMF curve and
said
reference unmodified back EMF curve.
In accordance with another aspect of the present invention, there is provided
an
apparatus for categorizing coins/tokens, comprising:
(a) detect coils arranged to receive at least part of a coin/token
therebetween,
said detect coils being arranged for energization with a single pulse;
(b) detecting means for detecting the unmodified back EMF curve of the
decaying pulse;
(c) analysing means for analysing said unmodified back EMF curve to measure
at least one characteristic of said unmodified back EMF curve; and
(d) comparing means for comparing said at least one characteristic with the
corresponding characteristics) of a reference unmodified back EMF curve to
determine
therefrom into which category of a number of predetermined categories said
coin/token falls.
CA 02179261 2004-10-26
4b
Description of the Drawings
Embodiments of the invention will be illustrated in detail hereinafter with
reference to
the accompanying drawings, in which:
Fig. 1 is an end elevation of an elevation of an embodiment of a coin
validator body
according to the invention;
Fig. 2 is a top plan view of the coin validator of Fig. 1;
Fig. 3 is an underneath view of the coin validator of Fig. l;
Fig. 4 is an elevation of a subsidiary body element of the body of Fig. 1;
Fig. 5 is a section along the lines 5-5 of Fig. 4;
Fig. 6 is an elevation of a main body element of the body of Fig 1;
Fig. 7 is a section along the lines 7-7 of Fig. 6;
Fig. 8 is an enlarged view of part of Fig. 7;
Fig. 9 is a section along the lines 9-9 of Fig. 6;
Fig. 10 is a section along the lines 10-10 of Fig. 1;
Fig. 11 is a non dampened back EMF oscillating waveforms of two coins A and B;
Fig. 12 is a back EMF oscillating waveform of coin A of Fig. 11 with an upper
mean
amplitude curve;
Fig. 13 is the signal of Fig. 12 with a lower mean amplitude curve;
Fig. 14 is the signal of coin A of Fig. 11. with upper and lower mean
amplitude
curves;
Pt~TlA1J94100777
wp 95116978 ~ ~~
Fig. 15 is the signal of Fig. 14 with measurements after a first clock count;
Fig. 16 is a back emf oscillating waveform with mean curves for a further
coin.
Figs. 17 to 25 are examples of oscillating waveforms for different cons;
Figs. 26 to 35 are graphic representations of the ability of the principal
variables to
5 distinguish the coin sets of Figs. 17 to 25; and
Figs. 36 is a circuit diagram illustrating one embodiment used to conduct the
discrimination of the present invention.
In Figs. 1 to 10, "hardware" aspects of a known validator is disclosed to
which the
invention may be applied.
As shown the coin validator is a self contained unit locatable in a particular
apparatus, such that a coin introduced into the apparatus - whatever the;
apparatus may be -
will travel past a detect coil in the validator, will be validated or
invalidated, and as a
consequence will emerge from one outlet or another outlet of the. validator,
and the
appropriate signal will be sent to the particular apparatus for further
action.
Referring firstly to Figs. 1 to 3, the coin validator 10 of includes a body 12
which
has two body portions 14 (main body) and 15 (subsidiary body), which are
hinged together,
as shown at 18.
Within subsidiary body portion 16 there is a printed circuit board assembly
98, and
a cover 100 is secured to body portion 16 by screws or the like, one of which
is shown at
28 in Fig. 5.
Main body portion 14 has a printed circuit board assembly 102 located therein,
and
a cover 104 is secured to body portion 14 by screws or the like.
On printed circuit board assemblies 98, 102 may be located all the electrical
and
electronic components to operate, monitor and control the validator 10.
2~ Main body cover 104 is adapted to hook into slots ( 108,110) on main body
portion
14, and as stated before rnay be secured via screws such as 106.
To secure validator 10 to or in apparatus such as a vending machine, pins 112,
116,
118 may be used to attach the validator 10 to a bracket (not shown) in tlhe
apparatus.
The upper view of the generally cuboidal body 12 (Fig. 2) shows a coin
entrance
20, and the underneath view (Fig. 3) shows an'accept' outlet 22 and a'reject'
outlet 24.
Turning now to Fig. 4, S and 6, in particular Fig. 5, a coin path 26 extends
from
inlet 20. The width W of the coin path is selected to be the minimums
consistent with the
thickness of the coins likely to be introduced into the validator 10 the width
W is 3.Smm,
to accommodate the thickest known coin.
SUBSTIT'IfTE SHEET (Rule 26)
WO 95I1G978 7 PCT/AU94/00777
6
A first optical sensor 28 is located close to the start of coin path 26, the
first part of
which 30 is a downwardly inclined (Figs. 4,5) and is angled from the vertical
(Fig. 5).
In Fig. 5, the base 32 of the coin path portion 30 of the embodiment of the
present
invention has an inclination, relative to side wall 36. As a coin (for example
small coin X
S shown in Fig. 5) is dropped into outlet 20, it will fall to portion 30.
Under the influence of
gravity, it will roll down the incline of portion 30, but the lower periphery
of the coin will
also slide down the lateral inclination of the base 32, as such a part of a
lower peripheral
edge of the coin will make point contact on base 32, and will locate between
the lower end
of base 32 and the lower end of side wall 34. This causes the coin, again
under the
influence of gravity, to fall to the position shown in Fig. 5, where the top
peripheral edges
makes a point contact with side wall 36 of coin path 26. Successive coins
passing through
area 38 on coin path 26, will each adopt an orientation where point contact
will be made
between a peripheral edge and wall 36, and a peripheral edge and base 32. This
orientation
is more stable and thus more reproducible in successive coins passing through
region 38.
IS Coin Y, being a larger-diameter coin, will have a slightly different rest
angle to that
of coin X, but the angle is substantially the same for all coins. This has
been found to
assist in accurate validation, different coins may adopt different
orientations at the area 38
of interrogation (to be described hereinafter) through rattling or wobbling as
they pass the
area, or as a result of the coins being wet or sticky, which leads to a
reduction in accurate
discrimination.
Located on respective sides of coin path 26 at area 38 is one set of inductive
(pot)
coils 40,42. Coils 40,42 are connected in a detect circuit (such as, for
example, the circuit
of Fig. 11 ) and form a singular inductive field. The coils (40,42) are
adapted to be
energised with a single pulse, for each coin validation operation, by a
generally
conventional switching circuit (not shown).
The coils 40,42 are physically connected to respective body portions 14,16
preferably with an adhesive. From Fig. 5 it can be seen that the coils 40,42
are located
generally parallel to the plan of coin path 26, and as near as practicable are
separated by
about the coin path width W.
Located just adjacent to coils 40,42 in a position on the edge of the detect
area 38,
is a pair of optical sensors 44,46 (Figs. 4, 6 and 7).
In Fig. 7 there is also shown a reject lever 48, which may be pushed down to
release
a jammed coin entering coin path 26.
Located at the base of body portion 14 is a coin acceptlreject mechanism 50,
shown
in more detail in Fig. 8.
SUBSTITUTE SI3EET (Rule 26)
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WO 95116978 PC'.TlAU94100777
7
The mechanism 50 provides a fast acting means for allowing an accepted, that
is, a
validated coin to move into an 'accept' chancel, whilst preventing a rejected
coin from
passing into the accept channel. The rejected coin is diverted into a'reject'
channel.
The mechanism 50 includes an accept/reject arm 62 which is pivoted on a
'floating'
pivot 64, to be activated by a solenoid which has a U-shaped electro magnet 52
secured to
body portion 14 by a screw or the like 54. The floating pivot 64 is adapted
for limited
movement, for example, it may be located in a groove in portion 14" to
facilitate rapid
movement of arm 62 between positions.
Arm 62 is normally held by spring means 58 in the 'reject' position shown in
Fig. 7,
where surface 84 of the arm 62 constitutes a continuation of base 32 of coin
path 26.
When the mechanism is provided with an 'accept' signal, instruci:ion or the
like, the
solenoid is energised. This causes arm 62 to be attracted to magnet 52. In
particular,
pivot 64 is attracted to the lower portion of magnet 52, eventually making
contact
therewith. At that stage the magnet 52/arm 62 combination enables more
magnetic flux to
be generated, and thus more magnetic force is applied to arm 62, to move it
more quickly
to the Fig. 8 position. It has been found that such an arrangement as the one
shown in
Fig. 8 enables extremely rapid retraction of arm 62.
The paths of both accepted and rejected coins will now be described in
relation to
Figs 1 to 10; they are best represented visually in Fig. 10.
Fig. 9 shows the body 12 of validator 10 in its open configuration, where body
portions 14, 16 have been pivoted apart at pivot points 18. Pivot point 18 is
preferably
constituted by two hinge pins located at either end of the body 12, generally
on the line of
the coin path 26.
The body portions 14, 16 and covers 98,102 are produced from a plastics
material
by injection moulding, and the coin path 26 is defined by internal mouldings
of the
portions. Thus, the one 'wall' of the coin path 26 is formed or. one portion,
and the other
'wall' on the other portion.
The hinged body arrangement, best shown in Fig. 9, enables the two portions
14,16
to be pivoted apart. The two portions are biased together, by spring means or
the like - in
order that the coin path 26 may be cleaned. Coin paths in validators often
become dirty
and/or clogged, due to residues carried by coins which pass therethrough,.
Furthermore, the portions 14 and 16 are pivoted apart in order that bent coins
or
slugs stuck in the device are able to drop free into the reject path.
The covers 98,102 fitted to body portions 14,16 also provide splash and dirt
protection for the electronic components.
SUBSTTT'UT'E SHEET (Rule 26)
Wo 95116978 ~ ~ ? '~ L ~ ~ PCTIAU94100777
8
A coin Z - in the representation of Fig. 10, an Australian fifty-cent coin -
enters
validator 10 through inlet 20. There is in use, a coin channel leading from
outside a
vending machine, for example, to inlet 20, through which the coin Z may
initially have to
pass.
When the coin Z reaches the position shown, in which it is between coils 40
and 42,
(S1,S2 of Figure 36) (see also Fig. 5, where coins X, Y are shown in that
position) the
presence of coin Z will be detected by optical sensors 44,46 (S9 Fig 36).
A 'coin detected' signal from sensors S9 Fig 36 44.,46 is sent to a
microprocessor S8
Fig 36 which causes coils 40,42 (S 1,52 Fig 36) to be energised with a single
pulse. After
analysing the results of that energisation or pulse, the microprocessor either
sends or does
not send an 'accept' signal to mechanism 50 (S 10 Fig. 36).
If an 'accept' signal is sent to mechanism 50, the solenoid will be energised,
arm 62
will be retracted, and coin Z will pass along the 'accept' channel, marked by
the arrowed
line 86.
If the analysis rejects the coin, arm 62 will stay in the 'reject' position
and coin Z
will be deflected by surface 84 of arm 62 into the 'reject' channel shown by
arrowed line
88.
Two further pairs of optical sensors are provided. They are check optical
sensors
90,92 and accept optical sensors 94,96 (S9 Fig. 36).
If coin Z is accepted, and keeps moving down the accept channel, it will first
pass
between check sensors 90, 92. Both the check and accept optical sensors are
continuously
monitored by the aforementioned microprocessor so as to ascertain the
direction of
movement of a coin within the validator 10. If the passage of the coin Z is
such so as to
trigger the accept optical sensors (90,92) before triggering the check optical
sensors (94,96)
then the passage of the coin Z is considered to be fraudulent and an alarm
signal is
generated or alternatively no outputs will be generated. This applies in cases
where a coin
on a piece of string or twine or other device is pulled in and out of the
validator in an
attempt to create fake credits.
The coin continues down the accept path until it reaches the accept optical
sensors
(92). Upon triggering the accept optical sensor the microprocessor considers
that the coin
Z has successfully travelled through the device and will give the appropriate
outputs.
The approach of the present invention to coin validation/discrimination data
used in
the validator 10 of Figs. 1 to 10, will now be described.
In Fig. 11 the unmodified back emf oscillating waveforms of 2 coins {A and B)
are
given and superimposed one on top of the other. These two different coins were
selected
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CA 02179261 2003-02-03
9
because of their close characteristics which makes them difficult to
differentiate using current
discrimination systems.
Modification of these back emf oscillating waveforms by lmown means such as
inversion and amplification have tended to eliminate distinguishing features
between them,
though of course, allowing ready discrimination with other types of coins with
clearly
different characteristics.
As will be readily apparent from Fig. 11, the superimposed oscillating
waveforms
whilst initially very similar, display significantly different amplitude and
frequency after a
relatively short period of time. By recording these differences for any type
of coin it is
possible to discriminate even between very similar coins. The recordal can be
by any suitable
means e.g. devising a resultant analog signal.
To compare these types of oscillating waveforms it is possible to measure and
record
various characteristics of the curves. For example such characteristics or
variables include:
(i) superimposing a mean amplitude curve [see Figs. 12 to 14];
(ii) the phase and/or change in phase of each oscillating waveform;
(iii) (a) the curves plotted by the peaks of either or both of the positive
and/or
negative portions of the oscillating waveform; and
(b) the amplitude of the negative and/or positive peaks of each
oscillating waveform;
(iv) the area of the curves beneath the peaks of each oscillating waveform;
(v) the frequency and/or change in frequency of each oscillating waveform;
(vi) the decay of peaks of each oscillating waveform in a predetermined time;
and
(vii) any combination of the above.
Some of these approaches are illustrated in Figs. 12 to 16.
The area of curves beneath the peaks of each oscillating waveform has the
advantage
of allowing for variations in the waveforms due to variations in
characteristics of coins of the
same denomination. By taking the area beneath the peaks, any variations in
waveform due to
variations in coin characteristics will be allowed for and consistent results
obtained.
In Figs. 12, 13 and 14 the back emf oscillating waveforms of a single coin is
shown.
Mean curves are drawn on the positive oscillation waveforms amplitudes,
negative oscifiation
waveform amplitudes and both respectively. Typically an analog signal for any
of these
waveforms can be established to provide a signature for the particular type of
coin.
Figs. 15 and 16 show other characteristics of the back emf oscillating
waveform of a
single coin which can be used. For example in Figs. 15 and 16 different mean
points of time
are established for when the oscillations have dissipated to a predetermined
amount.
CA 02179261 2003-02-03
9a
If one considers . the variables mentioned above in a specific combination, it
is
possible to discriminate between coins having very similar characteristics.
By use of a circuit which can functionally be defined as:
CA 02179261 2003-02-03
V(t) = Ae'~Sin (nut +~) + Bc'~
("the foranula")
where:
V(t) is the voltage at time t
5 A is the amplitude of the oscillation waveform
B is the ampliwde of the direct current component
~ is the phase angle of the response triggering delay
w is 2II f
f is the frequency of oscillation
10 a is the decay associated with the oscillating waveform
a is the decay associated with the direct current component,
one can subject a coin with a single pulse, consider the results of that
pulse, and compare
with the known data for known coins.
An analysis of captured data for a series of 34 coins is included in Table 1
below.1n
this analysis a curve-fitting program has been used to fit the captured data
to the formula.
This data represents the average data for a large set of captured samples, for
example, 100
of each coin type. The spread of the calculated variables from the samples is
calculated as a
Standard Deviation ("SD") expressed as a percentage. In the table "Sigma" is a
in the
. formula, and "Alpha" is a in the formula.
a is clear from Table 1 that A, a (Sigma) and f are three significant
variables. B
and a (Alpha) are relatively minor terms with a high range of sprrad. The
utilisation of
these additional two variables will allow for a higher degree of selectivity
of dins, and
improved accuracy. A and B may not be distinguished, if required. Also, a and
a may not
be distinguished. The net effect of the combination of A, B, a and a may be
considered.
Tlarrefore, by considering each of the variables alone, or in any combination,
the
back FMF of a coin can be compared with known criteria and its nature
determined.
An easmple of the oscillating waveform, together with the curve A a '~, and 10
times Be-~, for each of the coins numbered 1, 2, 3, 5, 7, 9, 11, 13 and 15
respectively, is
shown in Figures 17 to 25. The "noise" curve along the axis is a plot of 10
times the
difference between the measurai value and the calculated value from the curve.
After
taking into account the 10 times multiple, it is clear the curve fitting has
resulted in a high
degree of fit between measured and calculated values.
CA 02179261 2003-02-03
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Figures 26 to 35 show a series of graphic representations that demonstrate the
ability of the principal variables A, f, Q (Sigma), B and a (Alpha) to
distinguish the various
coin sets. The ability of each variable to distinguish one coin from the other
is
demonstrated by plotting one variable against the other variable for the coin
sets. These
~ plots are based on using variables. Overlaps of the rectangles indicates a
lack of clear
discrimination. Total discrimination is achieved by using more than one
variable.
To achieve an equivalent to the combined efforts of AIB, intsof the
waveform for as odd number of half-cycles should be pcrfonmed asthe
integration of the
odd number of half waves is proportional to the magnitude of the first half
cycle wavcform.
Integration of an eves number of half-cycles is a measure of a/a as the
difference between
the first and second half cycle provides an indication of the rate of decay of
the waveform.
The measurement of the period for a number of cycles provides and indication
of the
frequency, f.
This methodology has been demonstrated to produce a high level of
discrimination
of the World Coin Sets.
To refer now to Figure 36, there is shown a circuit which can be used to
conduct the
discrimination referred to above.
Coils S 1 and S2 are connected in series and are magaedcally coupled.
Capacitor S3
is connected across the coils at the points S 11 and S21.
F..nergisation of the coils S 1 and S2 is controlled by switch S4 which in
turn is
controlled by output O1 of microprocessor S8. Microprocessor S8 makes the
decision with
rcspoct to the coil energisation upon rccxption of the trigger information
from the
optocouples block S9 through the input I4, I5 8c I6 of microprocessor S8.
After coil S1,S2 is switched off under the control of microprocessor S8 it
produces
a back EMF oscil)ating voltage waveform.
The waveform is applied to the zero-crossing detector at point S21 and logic
circuitry SS at point S51, to the half period waveform integrator S6 at S61
and to the decay
integrator of the even number of half periods S7 at S71.
The zero-crossing detector and logic current S65 produces three outputs. The
outputs are as follows:
i) at output S52 a signal proportional to the half period of tire oscillating
wavcform;
ii) at output S53 a signal proportional to the even number of half periods of
the
oscillating waveform:
iii) at output S54 a signal proportional to the period of the oscillating
waveform.
CA 02179261 2003-02-03
12
The half period waveform integrator S6 integrates the input waveform S61 for
the
duration that an output is present at S52 for the zero crossings and logic
circuit SS which is
present for an odd number of waveforms.
When S62 is deactivated a stored iategrated signal is S6 is dis~harg~l with a
prodetermiaed time constaai. The period of the discharge is proportional to
the integratioz!
of the area under the curve of the oscillating waveform. That information is
presented at
output S63 to the input II of the microprocessor S8.
The integration of an odd number of waveforms repmesents the combined effect
of
A aad B of the formula
At the same time the oscillating waveform is presented to S7 and S71 and the
signal
is integrated for the period that S72 is active. Upon the deactivation of S72,
the remaining
stored signal value in S7 is discharged at a constant rate such that the
period of discharge is
proportional to the dscay information of the oscillating waveform. This signal
is presented
at S73 to the microprocessor S8 at the input I2.
The integration of an even number of waveforms provides an indication of the
combined effects of a and a of the formula.
At the same time the zero crossing detector and logic circuit S5 produces an
output
signal S54 proportional to the period of the fnqueacy of oscillation of the
oscillating
waveform. This signal is presented at I3 to the micmprocessoi 58 at the input
I3.
The microprocessor S8 compares the signals at Il, I2 and I3 with a data base
of stored
denominations within the microprocessor S8 and establishes the validity and
denomination
of a coin against values stored into the microprocessor from reference data.
If a match is found, output 02 of microprocessor S8 is activated and presented
to
the output activation stage S 10 at point S 101.
It is to lx realised that the actual number of waveforms coa,~idered is not
important,
but the acxuracy of the results is higher for some of the variables by
selectiag a larger
number of cycles of the waveform. Also, it is prefered that the
deterlniaations are made on
the basis of time. When the initial. pulse applied to the coils stops, the
internal clock in the
microprocessor starts so that time, in the form of clock pulses, can be
measured. In the case
of frequency, for eatample, when a pndetamnned number of half wavy crossings
have
occurred a signal is applied to the microprocessor to note the number of clock
counts. That
number is proportional to the frequency of the waveform.
WO 95116978 ~ (~ P(:TIAU94100777
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