Note: Descriptions are shown in the official language in which they were submitted.
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METHOD AND APPARATUS FOR DOCUMENT
H)ENTIFICATION AND AUTHENTICATION
FIELD OF THE INVENTION
The present invention relates, in general, to document identification. More
specifically, the present invention relates to an apparatus and method for
detecting
magnetic attributes of currency bills exhibiting magnetic properties.
BACKGROUND OF THE INVENTION
A variety of techniques and apparatus have been used to satisfy the
requirements
of automated currency handling systems. At the lower end of sophistication in
this area of
technology are systems capable of handling only a specific type of currency,
such as a
specific dollar denomination, while rejecting all other currency types. At the
upper end
are complex systems which are capable of identifying and discriminating among
and
automatically counting multiple currency denominations.
Recent currency discriminating systems rely on comparisons between a scanned
pattern obtained from a subject bill and sets of stored master patterns for
the various
denominations among which the system is designed to discriminate. For example,
it has
been found that scanning U.S. bills of different denominations along a central
portion
thereof provides scanning patterns sufficiently divergent to enable accurate
discrimination
between different denominations. Such a discrimination device is disclosed in
U.S. Pat.
No. 5,295,196. However, currencies of other countries can differ from U.S.
currency and
from each other in a number of ways. For example, while all denominations of
U. S.
currencies are 'the same size, in many other countries currencies vary in size
by
denomination. Furthermore, there is a wide variety of bill sizes among
different countries.
In addition to size, the color of currency can vary by country and by
denomination.
Likewise, many other characteristics may vary between bills from different
countries and
of different denominations. Such as, for example, the placement of a currency
thread
within the currency bills. The location of a security thread within the
currency bill can
vary for different countries and different denominations as well as for
different series of
denominations.
Many types of currency bills possess magnetic attributes exhibiting magnetic
properties which can be used to uniquely identify and/or authentic the
currency bills.
Examples of magnetic attributes include security threads exhibiting magnetic
properties
and ink exhibiting magnetic properties with which portions of some bills are
printed.
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Many of these magnetic attributes have a very small dimension(s). For example,
many
security threads have a width of about one millimeter. In prior art currency
devices, the
ability of the device to detect the presence of a magnetic attribute was
dependent on a
sensor pre-positioned along a bill transport path corresponding to a known
location on or
within a currency bill. Therefore, a new sensor would be added so that the
device could
evaluate other types of currency bills having magnetic attributes position in
other
locations.
SUM1MARY OF THE INVENTION
A currency evaluation device for receiving a currency bill having a magnetic
l0 attribute and evaluating the currency bill comprises a magnetic scanhead
disposed
adjacent to a bill evaluation region, a memory adapted to store master
magnetic
characteristic information corresponding to a plurality of types of currency
bills, and an
evaluating unit. The scanhead includes a plurality of closely spaced magnetic
sensors each
adapted to detect the presence of a magnetic attribute of the bill. The
plurality of magnetic
sensors cover a substantial portion of a dimension of a bill. The scanhead is
adapted to
retrieve magnetic characteristic information from the currency bill. The
evaluating unit is
adapted to evaluate the currency bill by comparing the retrieved magnetic
characteristic
information to the stored master magnetic characteristic information and to
generate an
error signal when the retrieved magnetic characteristic information does not
favorably
compare to the stored master magnetic characteristic information.
BRIEF DESCRIPTION OF THE DRAWINGS
Other objects and advantages of the invention will become apparent upon
reading
the following detailed description in conjunction with the drawings in which:
FIG. 1 is a perspective view of a currency scanning and counting machine
embodying the present invention;
FIG. 2 is a functional block diagram illustrating a currency discriminating
system
having a single scanhead;
FIG. 3 is a functional block diagram of an alternate currency scanning and
counting machine;
3o FIG. 4a is a diagrammatic perspective illustration of the successive areas
scanned
during the traversing movement of a single bill across an optical sensor
according to one
embodiment of the present invention;
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FIG. 4b is a perspective view of a bill and a preferred area to be optically
scanned
on the bill;
FIG. 4c is a diagrammatic side elevation view of the scan area to be optically
scanned on a bill according to one embodiment of the present invention;
FIG. 5 is a top view of a staggered scanhead arrangement according to one
embodiment of the present invention;
FIGS. 6a and 6b are a flowchart of the operation of a currency discrimination
system according to one embodiment of the present invention;
FIG. 7 is a block diagram of one embodiment of a system for detecting
counterfeit
currency according to the present invention;
FIG. 8 is a flow diagram that illustrates the operation of a counterfeit
detector
according to an embodiment of the present invention;
FIG. 9 is a graphical representation of the magnetic data points generated by
both
a genuine one hundred dollar bill and a counterfeit one hundred dollar bill;
FIG. 10 is a functional block diagram illustrating a currency discriminating
and
authenticating system according to the present invention;
FIGS. 11a and 1 1b comprise a flowchart illustrating the sequence of
operations
involved in implementing the discrimination and authentication system of FIG.
15;
FIGS. 12a and 12b are top views of U.S. currency illustrating the location of
various magnetic features;
FIGS. 13-15 are top views of sensor arrangements according to several
embodiments of the present invention;
FIGS. 16a and 16b are top views of U. S. currency illustrating various
scanning
areas according to an embodiment;
FIGS. 17a-17d are top views of sensor arrangements according to several
embodiments of the present invention;
FIG. 18 is a top view of thread sensors of a document
discriminating/authenticating system according to one embodiment of the
present
invention;
FIG. 19 is a top view of a magnetic scanhead of a document
discriminating/authenticating system according to one embodiment of the
present
invention;
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FIG. 20 is a flowchart illustrating the steps performed in determining the
denomination of a bill based on the location of a security thread;
FIG. 21 is a flowchart illustrating the steps performed in magnetically
determining
the denomination of a bill;
FIG. 22 is a flowchart illustrating the steps performed in optically
denominating a
bill and magnetically authenticating the bill;
FIG. 23 is a flowchart illustrating the steps performed in magnetically
denominating a bill and optically authenticating the bill; and
FIG. 24 is a flowchart illustrating the steps performed in denominating a bill
both
optically and magnetically.
DETAILED DESCRIPTION OF THE EMBODIMENTS
According to one embodiment of the present invention, multiple scanheads or
sensors per side are used to scan a bill. FIG. 1 is a perspective view of a
currency
processing device 10 embodying the present invention according to one
embodiment.
Currency bills are fed, one by one, form a stack of currency bills in an input
receptacle 12
into a transport mechanism (not shown). The transport mechanism guides the
bills to a
output receptacle 14. Before reaching the output receptacle 20, the transport
mechanism
guides the.bills past an evaluation region.(not shown), which comprises one or
more
sensors, where a bill can be for example, analyzed, authenticated denominated,
counted,
and/or otherwise processed. The results of the above process or processes are
communicated to a user of the currency processing device 10 via a user
interface 15. The
results of the above process or processes may be used to determine to
operation of the
currency handing device 10 (e.g. whether to suspend operation of the device
when a
counterfeit bills is detected). While the currency processing device 10
illustrated in FIG.
1 contains only one output receptacle 16, the present invention is applicable
to currency
processing machines containing more than one output receptacle such as the
mufti-pocket
currency handing machine disclosed in U.S. Patent Application Serial No.
09/502,666
entitled "Currency Handling Machine Having Multiple Output Receptacles" filed
on
February 1 l, 2000 or the currency scanning and counting machine 10
illustrated in FIG. 2i
of U. S. Patent No. 5,992,601. Furthermore, while the ensuing discussion
entails the
scanning of currency bills, the system of the present invention is applicable
to other
documents as well. For example, the system of the present invention may be
employed in
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conjunction with other documents such as stock certificates, bonds, and
postage and food
stamps. One embodiment of the currency handling system of FIG. 1 is designed
to
transport and process bills at a rate in excess of 800 bills per minute. In an
alternative
embodiment, the currency handling system of FIG. 1 is designed to transport
and process
5 bills at a rate in excess of 1000 bills per minute. In another alternative
embodiment, the
currency handling system of FIG. 1 is designed to transport and process bills
at a rate in
excess of 1200 bills per minute. In still another alternative embodiment, the
currency
handling system of FIG. 1 is designed to transport and process bills at a rate
in excess of
1500 bills per minute.
l0 Referring now to FIGS. 2 and 3, there are shown a functional block diagrams
illustrating currency discriminating systems having one and two scanheads,
respectively.
The systems 10 includes a bill accepting station 12 where stacks of currency
bills that
need to be identified and counted are positioned. Accepted bills are acted
upon by a bill
separating station 14 which functions to pick out or separate one bill at a
time for being
sequentially relayed by a bill transport mechanism 16, according to a
precisely
predetermined transport path, across scanhead 18 (FIG. 2) or scanheads 18a and
18b
(FIG. 3) where the currency denomination of the bill is scanned and
identified. Scanhead
18 is an optical scanhead that scans for characteristic information from a
scanned bill 17
which is used to identify the denomination of the bill. Likewise for scanheads
18a and
18b. The scanned bill 17 is then transported to a bill stacking station 20
where bills so
processed are stacked for subsequent removal.
The optical scanheads (18 of FIG. 2; l8a,b of FIG. 3) comprise at least one
light
source 22 directing a beam of light downwardly onto the bill transport path so
as to
illuminate a substantially rectangular light strip 24 upon a currency bill 17
positioned on
the transport path below the scanhead 18 and between the scanheads 18a and
18b. Light
reflected offthe illuminated strip 24 is sensed by a photodetector 26
positioned directly
above the strip. The analog output of photodetector 26 is converted into a
digital signal
by means of an analog-to-digital (ADC) convertor unit 28 whose output is fed
as a digital
input to a central processing unit (CPU) 30.
While scanheads 18, 18a, and 18b are optical scanheads, it should be
understood
that they may be designed to detect a variety of characteristic information
from currency
bills. Additionally, the scanheads may employ a variety of detection means
such as
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magnetic, optical, electrical conductivity, and capacitive sensors. Use of
such sensors is
discussed in more detail below, for example, in connection with FIG. 10. For
example,
the scanheads may employ a magnetoresistive sensor or a plurality of such
sensors
including an array of such sensors. Such a sensor or sensors may, for example,
be used to
detect magnetic flux.
Referring again to FIG. 2 and FIG. 3, the bill transport path is defined in
such a
way that the transport mechanism 16 moves currency bills with the narrow
dimension of
the bills being parallel to the transport path and the scan direction.
Alternatively, the
system 10 may be designed to scan bills along their long dimension or along a
skewed
l0 dimension. As a bill 17 moves on the transport path past the scanhead(s),
the light strip
24 effectively scans the bill across the narrow dimension of the bill. As
depicted, the
transport path is so arranged that a currency bill 17 is scanned by the
scanhead(s)
approximately about the central section of the bill along its narrow
dimension, as shown in
FIGS. 2 and 3. The scanheads function to detect light reflected from the bill
as it moves
across the illuminated light strip 24 and to provide an analog representation
of the
variation in light so reflected which, in turn, represents the variation in
the dark and light
content of the printed pattern or indicia on the surface of the bill. This
variation in light
reflected from the narrow dimension scanning of the bills serves as a measure
for
distinguishing, with a high degree of confidence, among a plurality of
currency
denominations which the system of this invention is programmed to handle.
A series of such detected reflectance signals are obtained across the narrow
dimension of the bill, or across a selected segment thereof, and the resulting
analog
signals are digitized under control of the CPU 30 to yield a fixed number of
digital
reflectance data samples. The data samples are then subjected to a digitizing
process
which includes a normalizing routine for processing the sampled data for
improved
correlation and for smoothing out variations due to contrast fluctuations in
the printed
pattern existing on the bill surface. The normalized reflectance data so
digitized
represents a characteristic pattern that is fairly unique for a given bill
denomination and
provides sufficient distinguishing features among characteristic patterns for
different
currency denominations. This process is more fully explained in commonly owned
U. S.
Patent No. 5,295,196 for a "Method and Apparatus for Currency Discrimination
and
Counting" filed on May 19, 1992 which is incorporated herein by reference in
its entirety.
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In order to ensure strict correspondence between reflectance samples obtained
by
narrow dimension scanning of successive bills, the initiation of the
reflectance sampling
process is preferably controlled through the CPU 30 by means of an encoder 32
which is
linked to the bill transport mechanism 16 and precisely tracks the physical
movement of
the bill 17 across the scanhead(s). In one embodiment of the present
inventions, the
encoder 32 is an optical encoder. More specifically, the encoder 32 is linked
to the rotary
motion of the drive motor which generates the movement imparted to the bill as
it is
relayed along the transport path. In addition, the mechanics of the feed
mechanism (not
shown, see United States Patent No. 5,295,196 referred to above) ensure that
positive
contact is maintained between the bill and the transport path, particularly
when the bill is
being scanned by the scanhead(s). Under these conditions, the encoder 32 is
capable of
precisely tracking the movement of the bill 17 relative to the light strip 24
generated by
the scanhead(s) by monitoring the rotary motion of the drive motor.
The output of photodetector 26 is monitored by the CPU 30 to initially detect
the
presence of the bill underneath the scanhead 18 and between the scanheads 18a
and 18b
and, subsequently, to detect the starting point of the printed pattern on the
bill, as
represented by the thin borderline 17a which typically encloses the printed
indicia on
currency bills. Once the borderline 17a has been detected, the encoder 32 is
used to
control the timing and number of reflectance samples that are obtained from
the output of
the photodetector 26 as the bill 17 moves across the scanhead(s) and is
scanned along its
narrow dimension.
The use of the encoder 32 for controlling the sampling process relative to the
physical movement of a bill 17 across the scanhead(s) is also advantageous in
that the
encoder 32 can be used to provide a predetermined delay following detection of
the
borderline prior to initiation of samples. The encoder delay can be adjusted
in such a way
that the bill 17 is scanned only across those segments along its narrow
dimension which
contain the most distinguishable printed indicia relative to the different
currency
denominations.
In the case of U. S. currency, for instance, it has been determined that the
central,
approximately two-inch (approximately 5 cm) portion of currency bills, as
scanned across
the central section of the narrow dimension of the bill, provides sufficient
data for
distinguishing among the various U. S. currency denominations on the basis of
the
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correlation technique disclosed in United States Patent No. 5,295,196 referred
to above.
Accordingly, the encoder 32 can be used to control the scanning process so
that
reflectance samples are taken for a set period of time and only after a
certain period of
time has elapsed since the borderline 17A has been detected, thereby
restricting the
scanning to the desired central portion of the narrow dimension of the bill.
FIGs. 4a-4c illustrate the scanning process of scanheads in more detail.
Referring
to FIG. 4b, as a bill 17 is advanced in a direction parallel to the narrow
edges of the bill,
scanning via a wide slit in the scanhead(s) is effected along a segment S of
the central
portion of the bill 17. This segment S begins a fixed distance D inboard of
the borderline
17a. As the bill 17 traverses the scanhead(s), a strip s of the segment S is
always
illuminated, and the photodetector 26 produces a continuous output signal
which is
proportional to the intensity of the light reflected from the illuminated
strip s at any given
instant. This output is sampled at intervals controlled by the encoder, so
that the sampling
intervals are precisely synchronized with the movement of the bill across the
scanhead(s).
As illustrated in FIGs. 4a and 4c, it is preferred that the sampling intervals
be
selected so that the strips s that are illuminated for successive samples
overlap one
another. The odd-numbered and even-numbered sample strips have been separated
in
FIGS. 4a and 4c to more clearly .illustrate this overlap. For example, the
first and second
strips s1 and s2 overlap each other, the second and third strips s2 and s3
overlap each
other, and so on. Each adjacent pair of strips overlap each other. For U. S.
currency, this
is accomplished by sampling strips that are 0.050 inch (0.127 cm) wide at
0.029 inch
(0.074 cm) intervals, along a segment S that is 1.83 inch (4.65 cm) long (64
samples).
The optical sensing and correlation technique is based upon using the above
process to generate a series of stored intensity signal patterns using genuine
bills for each
denomination of currency that is to be detected. According to one embodiment,
two or
four sets of master intensity signal samples are generated and stored within
system
memory, preferably in the form of an EPROM 34 (see FIGS. 2 and 3), for each
detectable
currency denomination. The sets of master intensity signal samples for each
bill are
generated from optical scans, performed on the green surface of the bill and
taken along
both the "forward" and "reverse" directions relative to the pattern printed on
the bill.
Alternatively, the optical scanning may be performed on the black side of U.S.
currency
bills or on either surface of bills from other countries. Additionally, the
optical scanning
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may be performed on both sides of a bill, for example, by placing a scanhead
on each side
of the bill transport path as described in more detail in commonly owned U. S.
Patent No.
5,467,406 entitled "Method and Apparatus for Currency Discrimination" filed on
March
08, 1994 and incorporated herein by reference in its entirety.
In adapting this technique to U.S. currency, for example, sets of stored
intensity
signal samples are generated and stored for seven different denominations of
U. S.
currency, i.e., $1, $2, $5, $10, $20, $50 and $100. For bills which produce
significant
pattern changes when shifted slightly to the left or right, such as the $2 and
the $10 bill in
U. S. currency, it is preferred to store two patterns for each of the
"forward" and "reverse"
directions, each pair of patterns for the same direction represent two scan
areas that are
slightly displaced from each other along the long dimension of the bill.
Accordingly, a set
of a number of different master characteristic patterns is stored within the
system memory
for subsequent correlation purposes. Once the master patterns have been
stored, the
pattern generated by scanning a bill under test is compared by the CPU 30 with
each of
the master patterns of stored intensity signal samples to generate, for each
comparison, a
correlation number representing the extent of correlation, i.e., similarity
between
corresponding ones of the plurality of data samples, for the sets of data
being compared.
The CPU 30 is programmed to identify the denomination of the scanned bill as
corresponding to the set of stored intensity signal samples for which the
correlation
number resulting from pattern comparison is found to be the highest. In order
to preclude
the possibility of mischaracterizing the denomination of a scanned bill, as
well as to reduce
the possibility of spurious notes being identified as belonging to a valid
denomination, a
bi-level threshold of correlation is used as the basis for making a "positive"
call. Such a
method is disclosed in United States Patent No. 5,295,196 referred to above.
If a
"positive" call can not be made for a scanned bill, an error signal is
generated.
Using the above sensing and correlation approach, the CPU 30 is programmed to
count the number of bills belonging to a particular currency denomination as
part of a
given set of hills that have been scanned for a given scan batch, and to
determine the
aggregate total of the currency amount represented by the bills scanned during
a scan
batch. The CPU 30 is also linked to an output unit 36 (FIG. 1b and lc) which
is adapted
to provide a display of the number of bills counted, the breakdown of the
bills in terms of
currency denomination, and the aggregate total of the currency value
represented by
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counted bills. The output unit 36 can also be adapted to provide a print-out
of the
displayed information in a desired format.
A procedure for scanning bills and generating characteristic patterns is
described
in United States Patent No. 5,295,196 referred to above and incorporated by
reference in
5 its entirety and in commonly owned U.S. Patent No. 5,633,949 entitled
"Method and
Apparatus for Currency Discrimination" filed on May 16, 1994.
The optical sensing and correlation technique described in United States
Patent
No. 5,295,196 permits identification of pre-programmed currency denominations
with a
high degree of accuracy and is based upon a relatively short processing time
for digitizing
l0 sampled reflectance values and comparing them to the master characteristic
patterns. The
approach is used to scan currency bills, normalize the scanned data and
generate master
patterns in such a way that bill scans during operation have a direct
correspondence
between compared sample points in portions of the bills which possess the most
distinguishable printed indicia. A relatively low number of reflectance
samples is required
in order to be able to adequately distinguish among several currency
denominations.
The system can conveniently be programmed to set a flag when a scanned pattern
does not correspond to any of the master patterns. The identification of such
a condition
can be used to stop the bill transport drive motor for the mechanism. Since
the encoder is
tied to the rotational movement of the drive motor, synchronism can be
maintained
between pre- and post-stop conditions. Additionally, a bill meeting or failing
to meet
some other criteria, such as being identified to be a suspect bill, may be
flagged in a
similar manner by stopping the transport mechanism.
The mechanical portions and the operation of a currency discrimination and
counting machine such as that of FIG. 1, 2, and 3 are described in detail in
commonly
owned U.S. Patent No. 5,992,601 entitled "Method and Apparatus for Document
Identification and Authentication" filed on February 14, 1997 which
incorporated herein
by reference in its entirety. One scanhead or a plurality of scanheads may be
used in
various alternative embodiment of the present invention. The physical
arrangement of the
scanhead(s) may also vary according to various alternative embodiments of the
present
invention. For example, the scanheads may be aligned along the same lateral
axis.
Referring now to FIG. 5, alternatively, the scanheads may be, for example,
staggered upstream and downstream from each other. FIG. 5 is a top view of a
staggered
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scanhead arrangement according to one embodiment of the present invention. As
illustrated in FIG. 5, a bill 130 is transported in a centered manner along
the transport
path 132 so that the center 134 of the bill 130 is aligned with the center 136
of the
transport path 132. Scanheads 140a-h are arranged in a staggered manner so as
to permit
scanning of the entire width of the transport path 132. The areas illuminated
by each
scanhead are illustrated by strips 142a, 142b, 142e, and 142f for scanheads
140a, 140b,
140e, and 140f, respectively. Based on size determination sensors, scanheads
140a and
140h may either not be activated or their output ignored. While the scanheads
140a-h
of FIG. 5 are arranged in a non-overlapping manner, they may alternatively be
arranged in
an overlapping manner. By providing additional lateral positions, an
overlapping
scanhead arrangement may provide greater selectivity in the segments to be
scanned. This
increase in scanable segments may be beneficial in compensating for currency
manufacturing tolerances which result in positional variances of the printed
indicia on bills
relative to their edges. Additionally, in one embodiment, scanheads positioned
above the
transport path are positioned upstream relative to their corresponding
scanheads
positioned below the transport path. In addition to size and scanned
characteristic
patterns, color may also be used to discriminate bills. For example, while all
U.S. bills are
printed in the same colors, e.g., a green side and a black side, bills from
other countries
often vary in color with the denomination of the bill. For example, a German
50 deutsche
mark bill-type is brown in color while a German 100 deutsche mark bill-type is
blue in
color. Alternatively, color detection may be used to determine the face
orientation of a
bill, such as where the color of each side of a bill varies. For example,
color detection
may be used to determine the face orientation of U. S. bills by detecting
whether or not the
"green" side of a U.S. bill is facing upwards. Separate color sensors may be
added
upstream of the scanheads described above. According to such an embodiment,
color
information may be used in addition to size information to preliminarily
identify a bill.
Likewise, color information may be used to determine the face orientation of a
bill which
determination may be used to select upper or lower scanheads for scanning a
bill
accordingly or compare scanned patterns retrieved from upper scanheads with a
set of
master patterns generated by scanning a corresponding face while the scanned
patterns
retrieved from the lower scanheads are compared with a set of master patterns
generated
by scanning an opposing face. Alternatively, color sensing may be incorporated
into the
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scanheads described above. Such color sensing may be achieved by, for example,
incorporating color filters, colored light sources, and/or dichroic
beamsplitters into the
currency discrimination system of the present invention. Various color
information
acquisition techniques are described in U.S. Patent Nos. 4,841,358; 4,658,289;
4,716,456;
4,825,246; and 4,992,860.
The operation of a currency discriminator according to one embodiment of the
present invention may be further understood by referring to the flowchart of
FIGS. 6a and
6b. In the process beginning at step 100, a bill is fed along a transport path
(step 102)
past sensors which measure the length and width of the bill (step 104). Next
at step 106,
it is determined whether the measured dimensions of the bill match the
dimensions of at
least one bill stored in memory, such as EPROM 34 of FIGS. 2-3. If no match is
found,
an appropriate error is generated at step 108. If a match is found, the color
of the bill is
scanned for at step 110. At step 112, it is determined whether the color of
the bill
matches a color associated with a genuine bill having the dimensions measured
at step
104. An error is generated at step 114 if no such match is found. However, if
a match is
found, a preliminary set of potentially matching bills is generated at step
116. Often, only
one possible identity will exist for a bill having a given color and
dimensions. However,
the preliminary set of step 116 is not limited to the identification of a
single bill-type, that
is, a specific denomination of a specific currency system; but rather, the
preliminary set
may comprise a number of potential bill-types. For example, all U.S. bills
have the same
size and color. Therefore, the preliminary set generated by scanning a U.S. $5
bill would
include U. S. bills of all denominations.
Based on the preliminary set (step 116), selected scanheads in a stationary
scanhead system may be activated (step 118). For example, if the preliminary
identification indicates that a bill being scanned has the color and
dimensions of a German
100 deutsche mark, the scanheads over regions associated with the scanning of
an
appropriate segment for a German 100 deutsche mark may be activated. Then upon
detection of the leading edge of the bill by sensors 68 of FIG. 4, the
appropriate segment
may be scanned. Alternatively, all scanheads may be active with only the
scanning
information from selected scanheads being processed. Alternatively, based on
the
preliminary identification of a bill (step 116), moveable scanheads may be
appropriately
positioned (step 118).
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Subsequently, the bill is scanned for a characteristic pattern (step 120). At
step
122, the scanned patterns produced by the scanheads are compared with the
stored master
patterns associated with genuine bills as dictated by the preliminary set. By
only making
comparisons with master patterns of bills within the preliminary set,
processing time may
be reduced. Thus for example, if the preliminary set indicated that the
scanned bill could
only possibly be a German 100 deutsche mark, then only the master pattern or
patterns
associated with a German 100 deutsche mark need be compared to the scanned
patterns.
If no match is found, an appropriate error is generated (step 124). If a
scanned pattern
does match an appropriate master pattern, the identity of the bill is
accordingly indicated
(step 126) and the process is ended (step 128).
While some of the embodiments discussed above entailed a system capable of
identifying a plurality of bill-types, the system may be adapted to identify a
bill under test
as either belonging to a specific bill-type or not. For example, the system
may be adapted
to store master information associated with only a single bill-type such as a
United
Kingdom 5 pound bill. Such a system would identify bills under test which were
United
Kingdom 5 pound bills and would reject all other bill-types.
The scanheads of the present invention may be incorporated into a document
identification system capable of identifying a variety of documents. For
example, the
system may be designed to accommodate a number of currencies from different
countries.
Such a system may be designed to permit operation in a number of modes. For
example,
the system may be designed to permit an operator to select one or more of a
plurality of
bill-types which the system is designed to accommodate. Such a selection may
be used to
limit the number of master patterns with which scanned patterns are to be
compared.
Likewise, the operator may be permitted to select the manner in which bills
will be fed,
such as all bills face up, all bills top edge first, random face orientation,
and/or random top
edge orientation. Additionally, the system may be designed to permit output
information
to be displayed in a variety of formats to a variety of peripherals, such as a
monitor, LCD
display, or printer. For example, the system may be designed to count the
number of each
specific bill-types identified and to tabulate the total amount of currency
counted for each
of a plurality of currency systems. For example, a stack of bills could be
placed in the bill
accepting station 12 of FIGS. 2-3, and the output unit 36 of FIGS. 2-3 may
indicate that a
total of 370 British pounds and 650 German marks were counted. Alternatively,
the
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output from scanning the same batch of bills may provide more detailed
information about
the specific denominations counted, for example one 100 pound bill, five 50
pound bills,
and one 20 pound bill and thirteen 50 deutsche mark bills.
Alternatively to employing optical scanheads as described above, a magnetic
sensor or sensors may be employed such as the Gradiometer available from NVE
Nonvolatile Electronics, Inc., Eden Praire, MN. For example, a
magnetoresistive sensor
may be employed to detect, for example, magnetic flux. Examples of
magnetoresistive
sensors are described in, for example, U.S. Pat. Nos. 5,119,025, 4,683,508,
4,413,296,
4,388,662, and 4,164,770. Additionally, other types of magnetic sensors may be
employed for detecting magnetic flux such as Hall elect sensors and flux
gates.
A variety of currency characteristics can be measured using magnetic sensing.
These include detection of patterns of changes in magnetic flux (U.S. Pat. No.
3,280,974), patterns of vertical grid lines in the portrait area of bills
(LJ.S. Pat. No.
3,870,629), the presence of a security thread (U.S. Pat. No. 5,151,607), total
amount of
magnetizable material of a bill (U.S. Pat. No. 4,617,458), patterns from
sensing the
strength of magnetic fields along a bill (U.S. Pat. No. 4,593,184), and other
patterns and
counts from scanning different portions of the bill such as the area in which
the
denomination is written out (U.S. Pat. No. 4,356,473). An additional type of
magnetic
detection system is described in U.S. Pat. No. 5,418,458.
FIG. 7 shows a block diagram of a counterfeit detector 210. A microprocessor
212 controls the overall operation of the counterfeit detector 210. It should
be noted that
the detailed construction of a mechanism to convey bills through the
counterfeit detector
210 is not related to the practice of the present invention. Many
configurations are well-
known in the prior art. An exemplary configuration includes an arrangement of
pulleys
and rubber belts driven by a single motor. An encoder 214 may be used to
provide input
to the microprocessor 212 based on the position of a drive shaft 216, which
operates the
bill-conveying mechanism. The input from the encoder 214 allows the
microprocessor to
calculate the position of a bill as it travels and to determine the timing of
the operations of
the counterfeit detector 210.
A stack of currency (not shown) may be deposited in a hopper 218 which holds
the currency securely and allows the bills in the stack to be conveyed one at
a time
through the counterfeit detector 210. After the bills are conveyed to the
interior of the
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counterfeit detector 210, a portion of the bill is optically scanned by an
optical sensor 220
of the type commonly known in the art. The optical sensor generates signals
that
correspond to the amount of light reflected by a small portion of the bill.
Signals from the
optical sensor 220 are sent to an amplifier circuit 222, which, in turn, sends
an output to
5 an analog-to-digital convertor 224. The output of the ADC is read by the
microprocessor
212. The microprocessor 212 stores each element of data from the optical
sensor 220 in
a range of memory locations in a random access memory ("RAM") 226, forming a
set of
image data that corresponds to the object scanned.
As the bill continues its travel through the counterfeit detector 210, it is
passed
10 adjacent to a magnetic sensor 228, which detects the presence of magnetic
ink. The
magnetic sensor 228 desirably makes a plurality of measurements along a path
parallel to
one edge of the bill being examined. For example, the path sensed by the
magnetic sensor
228 may be parallel to the shorter edges of the bill and substantially through
the bill's
center. The output signal from the magnetic sensor 228 is amplified by an
amplifier
15 circuit 230 and digitized by the ADC 224. The digital value of each data
point measured
by the magnetic sensor 228 is read by the microprocessor 212, whereupon it is
stored in a
range of memory in the RAM 226. The digitized magnetic data may be
mathematically
manipulated to simplify its use. For example, the value of all data points may
be summed
to yield a checksum, which may be used for subsequent comparison to expected
values
computed from samples of genuine bills. As will be apparent, calculation of a
checksum
for later comparison eliminates the need to account for the orientation of the
bill with
respect to the magnetic sensor 228. This is true because the checksum
represents the
concentration of magnetic ink across the entire path scanned by the magnetic
sensor 228,
regardless of variations caused by higher concentrations in certain regions of
the bill.
The image data stored in the RAM 226 is compared by the microprocessor 212 to
standard image data stored in a read only memory ("ROM") 232. The stored image
data
corresponds to optical data generated from genuine currency of a plurality of
denominations. The ROM image data may represent various orientations of
genuine
currency to account for the possibility of a bill in the stack being in a
reversed orientation
compared to other bills in the stack. Tf the image data generated by the bill
being
evaluated does not fall within an acceptable limit of any of the images stored
in ROM, the
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bill is determined to be of an unknown denomination. The machine stops to
allow
removal of the document from the stack of currency.
If the image data from the bill being evaluated corresponds to one of the
images
stored in the ROM 232, the microprocessor 212 compares the checksum of the
magnetic
data to one of a plurality of expected checksum values stored in the ROM 232.
An
expected checksum value is stored for each denomination that is being counted.
The
value of each expected checksum is determined, for example, by averaging the
magnetic
data from a number of genuine samples of each denomination of interest. If the
value of
the measured checksum is within a predetermined range of the expected
checksum, the
l0 bill is considered to be genuine. If the checksum is not within the
acceptable range, the
operator is signaled that the document is suspect and the operation of the
counterfeit
detector 210 is stopped to allow its retrieval.
If the bill passes both the optical evaluation and the magnetic evaluation, it
exits
the counterfeit detector 210 to a stacker 234. Furthermore, the counterfeit
detector 210
may desirably include the capability to maintain a running total of genuine
currency of
each denomination.
It should be noted that the magnetic checksum is only compared to the expected
checksum for a single denomination (i.e. the denomination that the optical
data
comparison has indicated). Thus, the only way in which a bill can be
classified as genuine
is if its magnetic checksum is within an acceptable range for its specific
denomination.
For a counterfeit bill to be considered genuine by the counterfeit detector of
the present
invention, it would have to be within an acceptable range in the denomination-
discriminating optical comparison and have a distribution of magnetic ink
within an
acceptable range for its specific denomination.
To summarize the operation of the system, a stack of bills is fed into the
hopper
218. Each bill is transported adjacent to the optical sensor 220, which
generates image
data corresponding to one side of the bill. The bill is also scanned by a
magnetic sensor
228 and a plurality of data points corresponding to the presence of magnetic
ink are
recorded by the microprocessor 212. A checksum is generated by adding the
total of all
magnetic data points. The image data generated by the optical sensor 220 is
compared to
stored images that correspond to a plurality of denominations of currency.
When the
denomination of the bill being evaluated has been determined, the checksum is
compared
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to a stored checksum corresponding to a genuine bill of that denomination. The
microprocessor 212 generates a signal indicating that the bill is genuine or
counterfeit
depending on whether said data is within a predetermined range of the expected
value.
Bills exit the counterfeit detector 210 and are accumulated in the stacker
234.
FIG. 8 is a flow diagram of an exemplary system according to an embodiment of
the present invention. At step 236, the presence of a bill approaching the
optical sensor
220 is detected by the microprocessor 212, which initiates an optical scanning
operation
238. Image data generated by the optical scanning operation are stored in RAM
226.
The number of optical samples taken is not critical to the operation of the
present
invention, but the probability of accurate classification of the denomination
of a hill
increases as the number of samples increases.
At step 240, the microprocessor 212 initiates the magnetic scanning operation.
.
The data points obtained by the magnetic scanning operation may be stored in
the RAM
226 and added together later to yield a checksum, as shown in step 244.
Alternatively,
the checksum may be calculated by keeping a running total of the magnetic data
values by
adding each newly acquired value to the previous total. As with the optical
scanning
operation, the number of data points measured is not essential, but the
chances of
accurately identifying a counterfeit bill based on the concentration of
magnetic ink
improve as the number of samples increases. At step 242, the microprocessor
determines
the denomination of the bill by comparing the image data to a plurality of
known images,
each of which corresponds to a specific denomination of currency. The bill is
identified as
belonging to the denomination corresponding to one of the known scan patterns
if the
correlation between the two is within an acceptable range. At step 246, the
checksum
resulting from the summation of the magnetic data points is compared to an
expected
value for a genuine bill of the denomination identified by the comparison of
the image data
to the stored data.
The expected value may be determined in a variety of ways. One method is to
empirically measure the concentration of magnetic ink on a sample of genuine
bills and
average the measured concentrations. Another method is to program the
microprocessor
to periodically update the expected value based on magnetic data measurements
of bills
evaluated by the counterfeit detector over a period of time.
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If the checksum of the bill being evaluated is within a predetermined range of
the
expected value, the bill is considered to be genuine. Otherwise, the bill is
considered to
be counterfeit. As will be apparent, the choice of an acceptable variation
from the
expected checksum determines the sensitivity of the counterfeit detector. If
the range
chosen is too narrow, the possibility that a genuine bill will be classified
as counterfeit is
increased. On the other hand, the possibility that a counterfeit bill will be
classified as
genuine increases if the acceptable range is too broad.
FIG. 9 is a graphical representation of the magnetic data points generated by
both
a genuine pre-1996 series one hundred dollar bill (solid line) and a
counterfeit one
hundred dollar bill (broken line). As previously noted, bills are desirably
scanned along a
path that is parallel to one of their short edges. The graph shown in FIG. 14
shows
magnetic data obtained by scanning a path passing approximately through the
center of
the bill. The measurements in the region designated "a" correspond to the area
at the top
of the bill. The area designated "b" corresponds to the central region of the
bill and the
region designated "c" corresponds to the bottom of the bill. The magnetic
measurements
for the genuine bill are relatively high in region a because of the high
concentration of
magnetic ink near the top of the bill. The concentration of magnetic ink in
region b is
relatively small and the concentration in region c is generally between the
concentrations
in regions a and c.
It should be noted that the concentration of magnetic ink in a typical
counterfeit
bill is uniformly low. Thus, the sum of the all data points for a counterfeit
bill is generally
significantly lower than for a genuine bill. Nonetheless, as counterfeiting
techniques
become more sophisticated, the correlation between genuine bills and
counterfeits has
improved.
The system described above increases the chances of identifying a counterfeit
bill
because the denomination of a bill being evaluated is determined prior to the
evaluation of
the bill for genuineness. The checksum of the bill being evaluated is only
compared to the
expected checksum for a bill of that denomination. The process of identifying
the
denomination of the bill prior to evaluating it for genuineness minimizes the
chance that a
"good" counterfeit will generate a checksum indicative of a genuine bill of
any
denomination.
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Alternatively, to the operation of the magnetic sensor described above in
connection with FIGS. 7-9, the magnetic sensor 228 may be a magnetoresistive
sensor or
a plurality of such sensors, including an array of such sensors, as described
above and
below.
Referring next to FIG. 10, there is shown a functional block diagram
illustrating
one embodiment of a currency discriminating and authenticating system similar
to that
depicted in FIGS. 2 and 3 but illustrating the presence of a second detector.
The currency
discriminating and authenticating system 250 includes a bill accepting station
252 where
stacks of currency bills that need to be identified, authenticated, and
counted are
l0 positioned. Accepted bills are acted upon by a bill separating station 254
which functions
to pick out or separate one bill at a time for being sequentially relayed by a
bill transport
mechanism 256, according to a precisely predetermined transport path, across
two
scanheads 260 and 262 where the currency denomination of the bill is
identified and the
genuineness of the bill is authenticated. In the embodiment depicted, the
scanhead 260 is
15 an optical scanhead that scans for a first type of characteristic
information from a scanned
bill 257 which is used to identify the bill's denomination. The second
scanhead 262 scans
for a second type of characteristic information from the scanned bill 257.
While in the
illustrated embodiment scanheads 260 and 262 are separate and distinct, it is
understood
that these may be incorporated into a single scanhead. For example, where the
first
20 characteristic sensed is intensity of reflected light and the second
characteristic sensed is
color, a single optical scanhead having a plurality of detectors, one or more
without filters
and one or more with colored filters, may be employed (U.S. Pat. No. 4,992,860
incorporated herein by reference). The scanned bill is then transported to a
bill stacking
station 264 where bills so processed are stacked for subsequent removal.
25 The optical scanhead 260 of the embodiment depicted in FIG. 10 comprises at
least one light source 266 directing a beam of light downwardly onto the bill
transport
,.
path so as to illuminate a substantially rectangular light strip 258 upon a
currency bill 257
positioned on the transport path below the scanhead 260. Light reflected off
the
illuminated strip 258 is sensed by a photodetector 268 positioned directly
above the strip.
30 The analog output of the photodetector 268 is converted into a digital
signal by means of
an analog-to-digital (ADC) convertor unit 270 whose output is fed as a digital
input to a
central processing unit (CPU) 272.
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The second scanhead 262 comprises at least one detector 274 for sensing a
second
type of characteristic information from a bill. The analog output of the
detector 274 is
converted into a digital signal by means of a second analog to digital
converter 276 whose
output is also fed as a digital input to the central processing unit (CPU)
272.
5 While scanhead 260 in the embodiment of FIG. 10 is an optical scanhead, it
should
be understood that the first and second scanheads 260 and 262 may be designed
to detect
a variety of characteristic information from currency bills. Additionally
these scanheads
may employ a variety of detection means such as magnetic or optical sensors.
Retrieved characteristic information can include reflected light properties
such as
10 reflected light intensity characteristics, light transmissivity properties,
various magnetic
properties of a bill, the presence of a security thread embedded within a
bill, the color of a
bill, the thickness or other dimension of a bill, etc.
For example, a variety of currency characteristics can be measured using
magnetic
sensing. These include detection of location of magnetic ink, detection of
patterns of
15 changes in magnetic flux (U.S. Pat. No. 3,280,974), patterns of vertical
grid lines in the
portrait area of bills (U. S. Pat. No. 3, 870,629), the presence of a security
thread (U. S.
Pat. No. 5,151,607), thread location, thread metal content, thread material
construction,
thread magnetic characteristics, covert thread features such as coatings, bar
codes, and
microprinting, total amount of magnetizable material of a bill (U. S. Pat. No.
4,617,458),
20 patterns from sensing the strength of magnetic fields along a bill (U. S.
Pat. No.
4,593,184), and other patterns and counts from scanning different portions of
the bill such
as the area in which the denomination is written out (U.S. Pat. No.
4,356,473).
Additionally, a magnetoresistive sensor or a plurality of such sensors
including an array of
magnetoresistive sensors may be employed to detect, for example, magnetic
flux.
Examples of magnetoresistive sensors are described in, for example, U. S. Pat.
Nos.
5,119,025, 4,683,508, 4,413,296, 4,388,662, and 4,164,770. Another example of
a
magnetoresistive sensor that may be used is the Gradiometer available from NVE
Nonvolatile Electronics, Inc., Eden Praire, MN. Additionally, other types of
magnetic
sensors may be employed for detecting magnetic flux such as Hall effect
sensors and flux
gates.
With regard to optical sensing, a variety of currency characteristics can be
measured such as detection of density (ITS. Pat. No. 4,381,447), color (U.S.
Pat. Nos.
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21
4,490,846; 3,496,370; 3,480,785), size including length and width, thickness
(IT.S. Pat.
No. 4,255,651), the presence of a security thread (U.5. Pat. No. 5,151,607)
and holes
(U.5. Pat. No. 4,381,447), and other patterns of reflectance and transmission
(U.5. Pat.
No. 3,496,370; 3,679,314; 3,870,629; 4,179,685), the detection of security
threads and
characteristics of security threads such as location, color, (e.g., under
normal and/or
ultraviolet illumination), thread material construction, covert thread
characteristics such as
coating, bar codes, microprinting, etc. Color detection techniques may employ
color
filters, colored lamps, andlor dichroic beamsplitters (U.5. Pat. Nos.
4,841,358; 4,658,289;
4,716,456; 4,825,246, 4,992,860 and EP 325,364). Furthermore, optical sensing
can be
l0 performed using ultraviolet light to detect reflected ultraviolet light
and/or fluorescent
light including detection of patterns of the same. Furthermore, optical
sensing can be
performed using infrared light including detection of patterns of the same. An
optical
sensing system using ultraviolet light is described in the applicant's issued
U.S. patent
5,640,463, filed October 4, 1994, and incorporated herein by reference, and
described
below.
In addition to magnetic and optical sensing, other techniques of detecting
characteristic information of currency include electrical conductivity
sensing, capacitive
sensing (U.5. Pat. No. 5,122,754 [watermark, security thread]; 3,764,899
[thickness];
3,815,021 [dielectric properties]; 5,151,607 [security thread]), and
mechanical sensing
(IT.S. Pat. No. 4,381,447 [limpness]; 4,255,651 [thickness]).
Referring again to FIG. 10, the bill transport path is defined in such a way
that the
transport mechanism 256 moves currency bills with the narrow dimension of the
bills
parallel to the transport path and the scan direction. Alternatively, the
system 250 may be
designed to scan bills along their long dimension or along a skewed dimension.
As a bill
257 moves on the transport path on the scanhead 260, the light strip 258
efI'ectively scans
the bill across the narrow dimension of the bill. In the embodiment depicted,
the transport
path is so arranged that a currency bill 257 is scanned by scanhead 260
approximately
about the central section of the bill along its narrow dimension, as best
shown in FIG. 10.
The scanhead 260 functions to detect light reflected from the bill as it moves
across the
illuminated light strip 258 and to provide an analog representation of the
variation in light
so reflected which, in turn, represents the variation in the dark and light
content of the
printed pattern or indicia on the surface of the bill. This variation in light
reflected from
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the narrow dimension scanning of the bills serves as a measure for
distinguishing, with a
high degree of confidence, among a plurality of currency denominations which
the system
of this invention is programmed to handle.
A series of such detected reflectance signals are obtained across the narrow
dimension of the bill, or across a selected segment thereof, and the resulting
analog
signals are digitized under control of the CPU 272 to yield a fixed number of
digital
reflectance data samples. The data samples are then subjected to a digitizing
process
which includes a normalizing routine for processing the sampled data for
improved
correlation and for smoothing out variations due to "contrast" fluctuations in
the printed
l0 pattern existing on the bill surface. The normalized reflectance data so
digitized
represents a characteristic pattern that is fairly unique for a given bill
denomination and
provides sufficient distinguishing features between characteristic patterns
for dii~erent
currency denominations. This process is more fully explained United States
Patent No.
5,295,196, filed on May 19, 1992 for "Method and Apparatus for Currency
Discrimination and Counting," which is incorporated herein by reference in its
entirety.
In order to ensure strict correspondence between reflectance samples obtained
by
narrow dimension scanning of successive bills, the initiation of the
reflectance sampling
process is preferably controlled through the CPU 272 by means of an encoder,
such as an
optical encoder 278, which is linked to the bill transport mechanism 256 and
precisely
tracks the physical movement of the bill 257 across the scanheads 260 and 262.
More
specifically, the encoder 278 is linked to the rotary motion of the drive
motor which
generates the movement imparted to the bill as it is relayed along the
transport path. In
addition, the mechanics of the feed mechanism (not shown, see United States
Patent No.
5,295,196 referred to above) ensure that positive contact is maintained
between the bill
and the transport path, particularly when the bill is being scanned by
scanheads 260 and
262. Under these conditions, the encoder 278 is capable of precisely tracking
the
movement of the bill 257 relative to the light strip 258 generated by the
scanhead 260 by
monitoring the rotary motion of the drive motor.
The output of photodetector 268 is monitored by the CPU 272 to initially
detect
the presence of the bill underneath the scanhead 260 and, subsequently, to
detect the
starting point of the printed pattern on the bill, as represented by the thin
borderline 257a
which typically encloses the printed indicia on currency bills. Once the
borderline 257a
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23
has been detected, the encoder 278 is used to control the timing and number of
reflectance samples that are obtained from the output of the photodetector 268
as the bill
257 moves across the scanhead 260 and is scanned along its narrow dimension.
The detection of the borderline 257a serves as an absolute reference point for
initiation of sampling. If the edge of a bill were to be used as a reference
point, relative
displacement of sampling points can occur because of the random manner in
which the
distance from the edge to the borderline 257a varies from bill to bill due to
the relatively
large range of tolerances permitted during printing and cutting of currency
bills. As a
result, it becomes difficult to establish direct correspondence between sample
points in
successive bill scans and the discrimination efficiency is adversely affected.
Embodiments
triggering off the edge of the bill are discussed above, for example, in
connection with
FIGs. 5a and Sb.
The use of the encoder 278 for controlling the sampling process relative to
the
physical movement of a bill 257 across the scanhead 260 is also advantageous
in that the
encoder 278 can be used to provide a predetermined delay following detection
of the
borderline prior to initiation of samples. The encoder delay can be adjusted
in such a way
that the bill 257 is scanned only across those segments along its narrow
dimension which
contain the most distinguishable printed indicia relative to the different
currency
denominations.
As a result of the first comparison described above based on the reflected
light
intensity information retrieved by scanhead 260, the CPU 272 will have either
determined
the denomination of the scanned bill 257 or determined that the first scanned
signal
samples fail to sufficiently correlate with any of the sets of stored
intensity signal samples
in which case an error is generated. Provided that an error has not been
generated as a
result of this first comparison based on reflected light intensity
characteristics, a second
comparison is performed. This second comparison is performed based on a second
type
of characteristic information, such as alternate reflected light properties,
similar reflected
light properties at alternate locations of a bill, light transmissivity
properties, various
magnetic properties of a bill, the presence of a security thread embedded
within a bill, the
color of a bill, the thickness or other dimension of a bill, etc. The second
type of
characteristic information is retrieved from a scanned bill by the second
scanhead 262.
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The scanning and processing by scanhead 262 may be controlled in a manner
similar to
that described above with regard to scanhead 260.
In addition to the sets of stored first characteristic information, in this
example
stored intensity signal samples, the EPROM 280 stores sets of stored second
characteristic information for genuine bills of the different denominations
which the
system 250 is capable of handling. Based on the denomination indicated by the
first
comparison, the CPU 272 retrieves the set or sets of stored second
characteristic data for
a genuine bill of the denomination so indicated and compares the retrieved
information
with the scanned second characteristic information. If sufEcient correlation
exists
l0 between the retrieved information and the scanned information, the CPU 272
verifies the
genuineness of the scanned bill 257. Otherwise, the CPU generates an error.
While the
embodiment illustrated in FIG. 15 depicts a single CPU 272 for making
comparisons of
first and second characteristic information and a single EPROM 280 for storing
first and
second characteristic information, it is understood that two or more CPUs
andlor
EPROMs could be used, including one CPU for making first characteristic
information
comparisons and a second CPU for making second characteristic information
comparisons.
Using the above sensing and correlation approach, the CPU 272 is programmed to
count the number of bills belonging to a particular currency denomination
whose
genuineness has been verified as part of a given set of bills that have been
scanned for a
given scan batch, and to determine the aggregate total of the currency amount
represented
by the bills scanned during a scan batch. The CPU 272 is also linked to an
output unit
282 which is adapted to provide a display of the number of genuine bills
counted, the
breakdown of the bills in terms of currency denomination, and the aggregate
total of the
currency value represented by counted bills. The output unit 282 can also be
adapted to
provide a print-out of the displayed information in a desired format.
According to other embodiments of the present invention, three or more types
.of
characteristics are retrieved from bills to be processed. These multiple types
of
characteristic information are used in various ways as described below to
authenticate
and/or denominate bills. According, the embodiment depicted in FIG. 15 may be
modified to add additional sensors to detect additional characteristic
information.
Likewise, given sensors may be employed to detect multiple types of
characteristic
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information. For example, an optical sensor may be employed both to generate
scanned
optical patterns but also to detect the presence, location, and/or color of
security threads.
The interrelation between the use of the first and second type of
characteristic
information can be seen by considering FIGS. 1 la and 11b which comprise a
flowchart
5 illustrating the sequence of operations involved in implementing a
discrimination and
authentication system according to one embodiment of the present invention.
Upon the
initiation of the sequence of operations (step 288), reflected light intensity
information is
retrieved from a bill being scanned (step 290). Similarly, second
characteristic
information is also retrieved from the bill being scanned (step 292).
Denomination error
l0 and second characteristic error flags are cleared (steps 293 and 294).
Next the scanned intensity information is compared to each set of stored
intensity
information corresponding to genuine bills of all denominations the system is
programmed
to accommodate (step 298). For each denomination, a correlation number is
calculated.
The system then, based on the correlation numbers calculated, determines
either the
15 denomination of the scanned bill or generates a denomination error by
setting the
denomination error flag (steps 300 and 302). In the case where the
denomination error
flag is set (step 302), the process is ended (step 312). Alternatively, if
based on this first
comparison, the system is able to determine the denomination of the scanned
bill, the
system proceeds to compare the scanned second characteristic information with
the stored
20 second characteristic information corresponding to the denomination
determined by the
first comparison (step 304).
For example, if as a result of the first comparison the scanned bill is
determined to
be a $20 bill, the scanned second characteristic information is compared to
the stored
second characteristic information corresponding to a genuine $20 bill. In this
manner, the
25 system need not make comparisons with stored second characteristic
information for the
other denominations the system is programmed to accommodate. If based on this
second
comparison (step 304) it is determined that the scanned second characteristic
information
does not sufficiently match that of the stored second characteristic
information (step 306),
then a second characteristic error is generated by setting the second
characteristic error
flag (step 308) and the process is ended (step 312). If the second comparison
results in a
sufficient match between the scanned and stored second characteristic
information (step
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306), then the denomination of the scanned bill is indicated (step 310) and
the process is
ended (step 312).
Table 1
Sensitivitv 1 2 3 4 5
Denomination
$1 200 250 300 375 450
$2 100 125 150 225 300
$5 200 250 300 350 400
$10 100 125 150 200 250
$20 120 150 180 270 360
$50 200 250 300 375 450
$100 100 125 150 250 350
An example of an interrelationship between authentication based on a first and
second characteristic can be seen by considering Table 1. Table 1 depicts
relative total
magnetic.content thresholds for various denominations of genuine bills.
Columns 1-5
represent varying degrees of sensitivity selectable by a user of a device
employing the
present invention. The values in Table 1 are set based on the scanning of
genuine bills of
varying denominations for total magnetic content and setting required
thresholds based on
the degree of sensitivity selected. The information iri Table 1 is based on
the total
magnetic content of a genuine $1 being 1000. The following discussion is based
on a
sensitivity setting of 4. In this example it is assumed that magnetic content
represents the
second characteristic tested. If the comparison of first characteristic
information, such as
reflected light intensity, from a scanned billed and stored information
corresponding to
genuine bills results in an indication that the scanned bill is a $10
denomination, then the
total magnetic content of the scanned bill is compared to the total magnetic
content
threshold of a genuine $10 bill, i.e., 200. If the magnetic content of the
scanned bill is less
than 200, the bill is rejected. Otherwise it is accepted as a $10 bill.
The magnetic characteristics of 1996 series $100 bills also incorporate
additional
security features. Referring to FIG. 12a, several areas of the bill 340 are
printed using
magnetic ink, such as areas A-K. Additionally, in some areas the strength of
the magnetic
field is stronger than it is in areas A-K. These strong areas of magnetics are
indicated, for
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example, at 344a and 334b. Some areas, such as area 346 contain magnetic ink
that is
more easily detected by scanning the bill along one dimension of the bill than
the other.
For example, a strong magnetic field is detected by scanning over area 346 in
the long or
wide dimension of the bill 340 and a weak field is detected by scanning area
346 in the
narrow dimension ofthe bill 340. The remaining areas of the bill are printed
with non-
magnetic ink.
Some of these magnetic characteristics vary by denomination. For example, in
FIG. 12b, in a new series $50 note 350, areas A', B', C', E', F', G' and K'
may be printed
with magnetic ink and areas 354a and 354b may exhibit even stronger magnetic
l0 characteristics. Accordingly, the non-magnetic areas also vary relative to
the $100 bill.
The use of magnetic ink in some areas of bills of one denomination and in
other
areas of bills of other denominations is referred to as magnetic zone
printing.
Additionally, magnetics are employed as a security feature by using ink
exhibiting
magnetic properties in some areas and ink that does not exhibit magnetic
properties in
adjacent areas wherein both the ink exhibiting and the ink not exhibiting
magnetic
properties appear visually the same. For example, the upper left-hand
numerical 100
appears visually to be printed with the same ink. Nonetheless, the "10" are
printed with
ink not exhibiting magnetic properties while the last "0" is printed with ink
that does
exhibit magnetic properties. For example, see area F of FIG. 12a.
Examples of arrangements of magnetic sensors that may be used to detect the
above described magnetic characteristics are illustrated in FIGS. 13, 14, and
15. FIGS.
13 and 14 illustrate bills 360 and 361 being transported past magnetic sensors
364a-d and
366a-g in the narrow dimension of the bill. FIG. 15 illustrates bill 370 being
transported
past magnetic sensors 374a-c in the long dimension of the bill. FIGs. 14 and
15 illustrate
a staggered arrangement of sensors. Magnetic scanning using these sensors may
be
performed in a manner similar to that described above in connection with
optical
scanning. For example, each sensor may be used to generate a magnetically
scanned
pattern such as that depicted in FIG. 9. Such patterns may be compared to
stored master
magnetic patterns. The scanning may be performed in conjunction with timing
signals
3o provided by an encoder such as described above in connection with optical
scanning.
Sensors 364, 366, and 374 may be magnetic sensors designed to detect a variety
of
magnetic characteristic such as those described above. These include detection
of
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patterns of changes in magnetic flux, total amount of magnetizable material of
a bill, and
patterns from sensing the strength of magnetic fields along a bill. An
additional type of
magnetic detection system is described in U.S. Pat. No. 5,418,458. For
example, sensors
364, 366, and 374 may be magnetoresistive sensors as described above. Examples
of
magnetoresistive sensors are described in, for example, U.S. Pat. Nos.
5,119,025,
4,683,508, 4,413,296, 4,388,662, and 4,164,770. Another example of a
magnetoresistive
sensor that may be used is the Gradiometer available from NVE Nonvolatile
Electronics,
Inc., Eden Praire, MN. Additionally, other types of magnetic sensors may be
employed of
detecting magnetic flux such as Hall effect sensors and flux gates.
Alternatively, instead of generating scanned magnetic patterns, the presence
or
absence of magnetic ink in various areas may be detected and compared the
stored master
information coinciding with several areas where magnetic ink is expected and
not
expected on genuine bills of various denominations. For example, the detection
of
magnetic ink at area F is be expected for a $100 bill but might not be for a
$50 bill and
vice versa for area F'. See FIGS. 12a and 12b. Accordingly, the detected
magnetic
information may be used to determine the denomination of a bill and/or to
authenticate
that a bill which has been determined to have a given denomination using a
different test,
such as via a comparison of an optically scanned pattern with master optical
patterns, has
the magnetic properties expected for that given denomination. Timing signals
provided
by an encoder such as described above in connection with optical scanning may
be
employed in detecting magnetic characteristics of specific areas of bills.
Additionally, for magnetic properties that are the same for all bills, such as
the
presence or absence of magnetic ink in a given location, such as the absence
of magnetic
ink in area 347 in FIGS. 12a and 12b, may be used as a general test to
authenticate
whether a given bill has the magnetic properties associated with genuine U. S.
currency.
An example of scanning specific areas for the presence or absence of magnetic
ink
and denominating or authenticating bills based thereon may be understood with
reference
to FIGs. 22a and 22b. In FIGs. 16a and 16b, areas Ml - M15 are scanned for the
presence
or absence of magnetic ink. For a 1996 series $100 bill as indicated in FIG.
16a, magnetic
ink should be present at areas M2, M3, M5, M~, M12, and M14 but not for the
other areas.
For a new series $50 bill as indicated in FIG. 16b, magnetic ink might be
expected at
areas Ml, M6, M8, M9, and M13 but not for the other areas. Similarly for other
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denominations, magnetic ink would be expected in some areas but not others. By
magnetically scanning a bill at areas Ml - Mls and comparing the results with
master
magnetic information for each of several denominations, the denomination of
the scanned
billed may be determined. Alternatively, where the denomination of a bill has
already be
determined, the authenticity of the bill can be verified by magnetically
scanning the bill at
areas Ml - M15 and comparing the scanned information to the master information
associated with the predetermined denomination. If they su~ciently match, the
bill passes
the authentication test.
Alternatively, magnetic sensors 364a-d, 366a-g, and 374a-c may detect the
l0 magnitude of magnetic fields at various locations of a bill and perform
bill authentication
or denomination based thereon. For example, the strength of magnetic fields
may be
detected at areas J, 344a, and 348. See FIG. 12a. In a genuine $100 bill, no
magnetic ink
is present at area 348. One test to call a bill to be a $100 bill or
authenticate that a bill is a
$100 bill would be to compare the relative levels of magnetic field strength
detected at
these areas. For example, a bill may be determined genuine if a greater signal
is generated
by scanning area 344a than area J which in turn is greater than for area 348.
Alternatively, generated signals may be compared against expected ratios, for
example,
that the signal for area 344a is greater than 1.5 times the signal for area J.
Alternatively,
the signals generated by scanning various locations may be compared to
reference signals
2o associated with genuine bills for those locations.
Another denominating or authenticating technique may be understood with
reference to area 346 of FIG. 12a. It will be recalled that for this area of a
$100 bill a
strong magnetic signal is generated when this area is scanned in the long
dimension of the
bill and a weak signal is generated when this area is scanned in the narrow
dimension.
Accordingly, the signals generated by sensors 364 and 374 for this area can be
compared
to each other andlor to different threshold levels to determine whether a
particular bill
being scanned has these properties. This information may be then used to
assist in calling
the denomination of the bill or authenticating a bill whose denomination has
previously
been determined.
The sensors of FIGS. 13, 14, and 15 may be embodied as separate discrete
sensors. Alternatively, two or more of these sensors may be embodied in the
same
scanhead or array structure. For example, FIG. 17a depicts the arrangement of
FIG. 13 a
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except that sensors 364a-d are arranged in a single scanhead 365. In a like
manner, the
sensors of FIGS. 13 and 14 may be arranged in one or more scanheads. For
example, the
staggered arrangement of sensors 366 depicted in FIG. 14 may comprise two
scanheads,
each comprising a linear array of sensors (FIG. 17b, scanheads 367a, 367b).
For example
5 sensors 366a-d may be arranged in a first scanhead and sensors 366e-g may be
arranged
in a second scanhead. Other arrangements are illustrated in FIGS. 17c and 17d
which
include scanheads 369 and 371a and 271b. These scanheads of multiple sensors
may
comprise, for example, magnetoresistive sensors as described above.
Additionally, the location of the thread within the bill can be used as a
security
l0 feature. For example, the security threads in all $100 bills are located in
the same
position. Furthermore, the location of the security threads in other
denominations will be
the same by denomination and will vary among several denominations. For
example, the
location of security threads in $10s, $20s, $50, and $100 may all be distinct.
Alternatively, the location may be the same in the $20s and the $100s but
different from
15 the location of the security threads in the $50s. The use of security is
not limited to U. S.
currency bills; rather, many other currency denomination throughout the world
incorporated security threads.
The presence of a security thread can be detected using magnetic sensing,
optical
sensing, or capacitance sensing. Optical sensing, including the use of ultra
violet light, is
20 disclosed in U.S. Patent No. 5,992,601 incorporated by reference above.
Referring to
FIG. 18, a bill 330 is shown indicating three possible locations 332a-c for
security threads
in genuine bills depending on the denomination of the bill. Sensors 334a-c are
positioned
over the possible acceptable locations of security threads. In systems
designed to accept
bills fed in either the forward or the reverse direction, identical sensors
are positioned
25 over the same locations on each half of the bill. For example, sensors 334c
are positioned
a distance d5 to the left and right of the center of the bill 330. Likewise,
sensors 334b are
positioned a distance d6 to the left and right of the center of the bill 330
while sensors
334a are positioned a distance d~ to the left and right of the center of the
bill 330.
Additional sensors may be added to cover additional possible thread locations.
These
30 sensors may be designed to detect the magnetic characteristic of the
security threads.
Referring now to FIG. 19, an embodiment of a "full array" magnetic scanhead
400
comprising thirty-two individual magnetic sensors 402 is illustrated. The
illustrated
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31
embodiment of the magnetic scanhead 400 is capable of detecting a magnetic
attributes)
405 of a currency bill disposed most anywhere throughout or within the
currency bill.
Examples of magnetic attributes of a currency bill may include security
threads) 404a-c
exhibiting magnetic properties, the aforementioned magnetic print zones
including
portions of serial numbers or barcodes printed on the bill. As discussed
above, specific
portions of U.S. currency bills are printed with ink exhibiting magnetic
properties. U.K.
pound notes and Mexican peso notes contain security threads exhibiting
magnetic
properties. The magnetic attributes of a currency bill need not be limited to
security
threads or magnetic printing but can include other objects having magnetic
properties
l0 disposed within or on a currency bill. Examples of magnetic sensors which
may be used
in the magnetic scanhead are described in U.S. Patent Nos. 5,086,519;
5,418,458;
5,552,589; 4,122,505; and 5,196,681, each of which is incorporated herein by
reference in
its entirety. The inventors use the term "full array" to describe a sensor or
scanhead
which substantially extends across the full length of the currency bill. The
plurality of
magnetic sensors 402 are closely spaced together to minimize the gap G - the
physical
space between individual sensors 402. Reducing the gap G between the
individual
sensors reduces the dead spots in the magnetic scanhead 400. Conversely,
increasing the
gap G between individual sensors 402 can create dead spots or "holes" such
that a
magnetic attribute passing through the dead space could not be detected.
Therefore, it is
2o desirable to minimize the gap G between sensors 402 so that the magnetic
attributes 405
such as security threads, for example, in currency bills will not go
undetected.
The proximate disposition of the sensors 402 increases the ability of the
magnetic
scanhead to detect the presence of a magnetic attribute 405 which is located
at any
position on or within the currency bill 406. In one embodiment of the magnetic
scanhead
400, the sensors 402 are disposed at a distance such that the gap G between
each of the
sensors 402 is about one millimeter. In another embodiment, the sensors 402
are
disposed at a distance such that the gap G is less than about one millimeter.
In still
another embodiment, the sensors 402 are disposed at a distance such that the
gap G is
about 0.5 mm. Applicants have found that disposing the sensors 402 such that
the gap G
is less than about one millimeter, e.g. about 0.5 mm, substantially eliminates
dead spots
from the scanhead 400. This embodiment of the magnetic scanhead is capable of
detecting very discrete magnetic attributes of currency bills including
attributes having a
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dimension less than about one millimeter. In one embodiment of the currency
handing
device 10, the distance between the magnetic scanhead 400 and the surface of
the
currency bill 406, termed the "air gap," ranges between 0 inch and 0.040 inch.
In other
embodiments, the air gap is greater than 0.040 inch.
Using security threads as an example, the inventors have found that most
security
threads disposed within currency bills issued throughout the world, such as
the Mexican
200 peso note, have a width of at least about one millimeter. Accordingly,
where the
length of the magnetic scanhead is substantially equal to the length of a
currency bill and
the sensors are positioned with close proximity as described, the magnetic
scanhead 400
l0 will be able to detect the presence of a magnetic attribute of the currency
bill no matter
where the magnetic attribute is positioned on or within the currency bill.
Therefore, the
currency handling device 10 employing the magnetic scanhead 400 is suited to
process
currency bills having magnetic attributes positioned most anywhere within the
currency
bills. Further, the currency processing device 10 equipped with the magnetic
scanhead
400 is suited to processes new series of bills which may be introduced in the
future,
because the ability of the magnetic scanhead 400 to detect the presence of a
magnetic
attribute is not dependent on a sensor pre-positioned along a bill transport
path
corresponding to a known location on or within a currency bill. Rather, the
same sensor
can be used for currency from different countries having varying magnetic
attributes
locations.
The detection of a magnetic attribute of a currency bill is also not dependent
on
the direction of bill travel. For example, prior art sensors having larger
dead spots may be
able to detect the security threads 404 if the currency bill 406, illustrated
in FIG. 19, was
transported in a direction parallel to the long dimension of the currency bill
406.
However, prior art sensors having large dead spots would be unable to detect
the
presence of a security thread 404 if the currency 406 was transported in the
direction
indicated. Most security threads are rather narrow and may pass through the
large dead
spots of prior art magnetic sensors. Additionally, a prior art magnetic sensor
having large
dead spots may be unable to detect smaller magnetic attributes 405 regardless
of the
direction of bill travel.
The magnetic scanhead can detect the presence of a magnetic attribute as well
as
determine the proximate location of the magnetic attribute relative to the
dimension of the
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bill perpendicular to the direction of travel. For example, referring to FIG.
19, if the
fourth (from let to right in FIG. 19) individual sensor 402 detected a
magnetic attribute,
the CPU of the device 10 can quickly determine the distance between the
magnetic
attribute and the left edge of the bill from the physical dimension of the
bill. The locations
of the magnetic attribute(s), the presence of the magnetic attribute(s),
and/or the
characteristics of the magnetic attributes) can be compared with master
information
during the evaluation of the currency bill.
To adapt a device 10 equipped with a scanhead 400 to handle a new set of
currency, the device's 10 software can be simply reprogrammed to provide an
indication
l0 of authenticity and/or denomination based on preprogrammed new magnetic
attributes
and their respective locations. Master attribute information can be stored in
the system
memory. In one embodiment, the system memory is in the form of an EPROM 34
(see
FIGS. 2 and 3).
The inventors have found that a magnetic scanhead 400 having a scanning length
Ll, from the left-most sensor 402 to the right-most sensor 402, of about 159.5
mm (about
6.28 inches) is suitable for processing currency of many denominations from
many
countries. According to one embodiment, each of the thirty-two sensors 402
have a
length L2 of about 4.5 mm (about 0.177 inch) with a center to center spacing
of about 5
mm (0.197 inch) so that the gap G between sensors 402 is about 0.5 mm (about
0.020
inch).
The magnetic scanhead 400 is capable of scanning a substantially continuous
segment of a currency bill because the close proximity of the sensors 402
ei~ectively
eliminates the dead spots from the magnetic scanhead 400. The inventors use
the term
"substantially continuous" to describe the effective elimination of dead spots
from the
magnetic scanhead 400. Put another way, the scanhead 400 can scan a magnetic
attribute
405 (having dimension smaller than 1 mm) of a currency bill, such as a
security thread,
regardless of the location of the attribute within the segment of the currency
bill being
scanned. The width of the substantially continuous segment is dependant on the
number
of sensors employed in the scanhead 400. For example, if the scanhead 400
illustrated in
FIG. 19 employed only two sensors 402 (rather than the thirty-two illustrated
sensors
402), the scanhead would be able to substantially continuously scan a segment
of a bill
having a width of about 9.5 mm as the tip-to-tip length of the two sensor
scanhead is
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34
about 9.5 mm (two 4.5 mm sensors with a center-to-center distance of 5 mm).
Or,
according to the embodiment illustrated in FIG. 19, the magnetic scanhead is
able to
substantially continuous scan a segment of a bill having a width of about
159.5 mm as the
tip-to-tip length of the scanhead 400 is about 159.5 mm (thirty-two 4.5 mm
sensors with
a center-to-center distance of five mm.).
The sensors 402 of the magnetic scanhead 400 illustrated in FIG. 19 cover a
substantial portion ofthe bill 406. Using U.S. currency as an example, U.S.
currency bills
have a long dimension of about 155 mm (6.1 inch). The scanhead 400 has length
Ll of
159.5 mm (about 6.28 inch) and a total sensor length (4.5 mm x 32 sensors) of
144 mm
(about 5.76 inch). Accordingly, a the ratio of the length of a U. S. currency
bill to the
combined length of the sensors is about 97%. Thus, the magnetic scanhead 400
to is able
to cover a substantial portion of the long dimension of a U.S. currency bill.
The physical size of the magnetic scanhead and the individual sensors can vary
according to various alternative embodiments of the present invention. For
example, in
one embodiment, each of the individual sensors 400 may have a length of eight
millimeters. In an alternative embodiment, the scanhead may be made up of
sixty-four
sensors. Obviously, the physical dimensions of the sensors and scanhead can
vary
according to various alternative embodiments of the present invention.
In addition to the currency handling device 10 illustrated in FIG. 1, the full
array
magnetic scanhead 400, illustrated in FIG. 19, can be implemented into other
currency
and document evaluation devices. For example, the magnetic scanhead 400 can be
implemented in bill accepting mechanisms often used with vending machines or
bill
changing machines. Other devices include point of sale devices for evaluating
the
authenticity of currency bills. Further, the magnetic scanhead 400 can be
implemented in
most any device for evaluating documents having subtle (very small) magnetic
attributes.
FIGS. 20-24 are flowcharts illustrating several methods for using optical,
magnetic, and security thread information to denominate and authenticate
bills. These
methods may be employed with the various characteristic information detection
techniques described above including, for example, those employing visible and
ultraviolet
light and magnetics including, for example, those for detecting various
characteristics of
security threads. Additionally, the currency handling device 10 with the
magnetic
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scanhead 400 can scan a currency bill and generate a magnetic image of the
bill. The
magnetic image can be compared to master magnetic images obtained from known
genuine bills stored in a memory of the device 10 to evaluate the currency
bill.
FIG. 20 is a flowchart illustrating the steps performed in determining the
5 denomination of a bill based on the location of a security thread. At step
510, a bill is
scanned for the presence of a security thread. The presence of a security
thread may be
detected using a number of types of sensors such as optical sensors using
transmitted
and/or reflected light, magnetic sensors such as the full array magnetic
scanhead
illustrated in FIG. 19, and/or capacitive sensors. See, for example, U.S. Pat.
Nos.
10 5,151,607 and 5,122,754. If a thread is not present as determined at step
512, a suspect
code may be issued at step 514. This suspect code may indicate that no thread
was
detected if this level of detail is desirable. The lack of the presence of a
thread resulting in
a suspect code is particularly useful when all bills to be processed are
expected to have a
security thread therein. In other situations, the absence of a security thread
may indicate
15 that a scanned bill belongs to one or more denominations but not others.
For example,
assuming security threads are present in all genuine U. S. bills between $2
and $100
dollars, but not in genuine $1 bills, the absence of a security thread may be
used to
indicate that a scanned bill is a $1 bill. According to one embodiment, where
it is
determined that no security thread is present, a bill is preliminary indicated
to be a $1 bill.
20 Preferably, some additional test is performed to confirm the denomination
of the bill such
as the performance of the optical denominating methods. The optical
denominating steps
may be performed before or after the thread locating test. If at step 512 it
is determined
that a security thread is present, the location of the detected security
thread is then
compared with master thread locations associated with genuine bills at step
516. At step
25 518 it is determined whether as a result of the comparison at step S 16 the
detected thread
location matches one of the stored master thread locations. If the detected
thread
location does not sufficiently match one of the stored master thread
locations, an
appropriate suspect code is generated at step 520. This suspect code may
indicate that
detected thread was not in an acceptable location if such information is
desirable.
30 Otherwise, if the detected thread location does sufficiently match one of
the stored master
thread locations, the denomination associated with the matching master thread
location is
indicated as the denomination of the scanned bill at step 522. In other
embodiments, the
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36
device 10 is capable of processing many different types of currency including,
for
example, casino script and transit passes as well as currency issued by
different countries.
FIG. 21 is a flowchart illustrating the steps performed in magnetically
determining
the denomination of a bill. At step 558, a bill is magnetically scanned and
one or more
magnetic patterns are generated. Patterns generated may be, for example,
patterns of
magnetic field strength. Alternatively, instead of generating magnetically
scanned
patterns, a bill is magnetically scanned for the presence or absence of
magnetic ink at one
or more specific locations on the bill. Alternatively, instead of simply
detecting whether
magnetic ink is present at certain locations, the strength of magnetic fields
may be
measured at one or more locations on the bill. At step 560 the scanned
magnetic
information is compared to master magnetic information. One or more sets of
master
magnetic information are stored for each denomination that a system employing
the
methods of FIG. 21 is designed to discriminate. For example, where one or more
scanned
magnetic patterns are generated, such patterns are compared to stored master
magnetic
patterns. Where, the presence or absence of magnetic ink is detected at
various locations
on a bill, this information is compared to the stored master magnetic
information
associated with the expected presence and absence of magnetic ink
characteristics at these
various locations for one or more denominations of genuine bills.
Alternatively, measured
field strength information can be compared to master field strength
information. At step
562 it is determined whether as a result of the comparison of step 560 the
scanned
magnetic information sufficiently matches one of sets of stored master
magnetic
information. For example, the comparison of patterns may yield a correlation
number for
each of the stored master patterns. To sufficiently match a master pattern, it
may be
required that the highest correlation number be greater than a threshold
value. An
example of such a method as applied to optically generated patterns is
described in more
detail in U. S. Pat. No. 5,295,196 incorporated herein by reference. If the
scanned
magnetic information does not sufficiently match the stored master magnetic
information,
an appropriate suspect code is generated at step 564. Otherwise, if the
scanned magnetic
information does sufficiently match one of the sets of stored master magnetic
information,
the denomination associated with the matching set of master magnetic
information is
indicated as the denomination of the scanned bill at step 566.
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FIG. 22 is a flowchart illustrating the steps performed in optically
denominating a
bill and magnetically authenticating the bill. At step 588, a bill is
optically denominated,
for example, according to the methods described above in U.S. Patent
5,992,601,
incorporated herein by reference above. Provided the denomination of the bill
is optically
determined at step 588, the bill is then magnetically authenticated at step
590. The
magnetic authentication step 590 may be performed, for example, according to
the
methods described in connection with in FIG. 21. At step 590, however, the
detected
magnetic information is only compared to master magnetic information
associated with
the denomination determined in step 588. If the master magnetic information
for the
denomination indicated in step 588 matches (step 592) the detected magnetic
information
for the bill under test, the bill is accepted (at step 596) as being a bill
having the
denomination determined in step 588. Otherwise, an appropriate suspect code is
issued at
step 594.
FIG. 23 is a flowchart illustrating the steps performed in magnetically
denominating a bill and optically authenticating the bill. At step 598, a bill
is magnetically
denominated, for example, according to the methods described above in
connection with
FIG. 21. Provided the denomination of the bill is magnetically determined at
step 598, the
bill is then optically authenticated at step 600. The optical authentication
step 600 may be
performed, for example, according to the methods described in above in U. S.
Patent
5,992,601, incorporated herein by reference above. At step 600, however, the
detected
optical information (or pattern) is only compared to master optical
information (or pattern
or patterns) associated with the denomination determined in step 598. If the
master
optical information for the denomination indicated in step 598 matches (step
602) the
detected optical information for the bill under test, the bill is accepted (at
step 606) as
being a bill having the denomination determined in step 598. Otherwise, an
appropriate
suspect code is issued at step 604.
FIG. 24 is a flowchart illustrating the steps performed in denominating a bill
both
optically and magnetically. At step 618, a bill is optically denominated, for
example,
according to the methods described above in connection with FIG. 25. Provided
the
denomination of the bill is opticallya determined at step 618, the bill is
then denominated
magnetically at step 620, for example, according to the methods described in
connection
with FIG. 21. At step 620, the magnetic denominating is performed
independently of the
CA 02424663 2003-04-03
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38
results of the optical denominating step 618. At step 622, the denomination as
determined optically is compared with the denomination as determined
magnetically. If
both optical and magnetic denominating steps indicate the same denomination,
the bill is
accepted (at step 626) as being a bill having the denomination determined in
steps 618 and
620. Otherwise, an appropriate suspect code is issued at step 624.
Alternatively, the
order of steps 618 and 620 may be reversed such that the bill is first
magnetically
denominated and then optically denominated.
While the invention is susceptible to various modifications and alternative
forms,
specific embodiments thereof have been shown by way of example in the drawings
and
herein described in detail. It should be understood, however, that it is not
intended to
limit the invention to the particular forms disclosed, but on the contrary,
the intention is to
cover all modifications, equivalents, and alternatives falling within the
spirit and scope of
the invention as defined by the appended claims.
