Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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BANKNOTE DENOMINATION READER SYSTEM FOR THE BLIND
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to a system for
recognizing banknote denominations, and particularly a
system for indicating the value oE specially marked
bankno-tes or currency bills. More particularly s-till,
the system is directed to serving blind individuals by
announcing the electronically read denomination of a
marked bill after insertion into a handheld~ battery
operated, device.
Description of the Related Art
A plethora of prior art patents exists, which
is mainly directed to recognition and validation of
currency banknotes or bills.
Canadian Patent No. 696,596 discloses a device
~here the amount of light transmitted through certain
portions of a bill is detected and compared to the re-
ference transmission characteristics of a genuine bill.
Canadian Patent No. 1,177,172 discloses a
currency note validator where the reflectance and opacity
of a number of laterally spaced sample areas are detected
and compared to stored reference values. The note is
accepted if it has the correct length and if the re1ec-
tance and opacity data exhibit less than a predetermined
maximum nonconformity. The note is propelled along its
length past the detectors. The device is microprocessor
controlled and a simple flow chart is shown ln figure 10
Canadian Patent No. 1,190,651 discloses a
device for scanning a sheet with a pattern (i.e. a
banknote). The device moves the note and illumina-tes
a strip perpendicular to the direction of movement. The
reflected light from the strip is summed and a
characteristic intensity waveform is created as the note
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is moved, which is compared to a stored reference
waveform.
In United States Patent No. 4,349,111, a bill-
handling device provides relative movement between a
sensor and a U.S. bill or other object to permit that
sensor to sense longitudinally-spaced areas on that U.S.
bill or other object which correspond to areas, on
authentic U.S. bill or counterfeits thereof, where
significant data is found. Data which is obtained during
the sensing of those areas is stored, and subsequently is
analyzed to determine the authenticity and denomination
of the U.S. bill -- if it is one of a plurality of bills
of specifically-different denominations.
United States Patent No. 4,127,194 is directed
to a device for selecting mail accordiny to Zip Codes.
As the piece of mail is moved, a detector detects the
light radiated by stimulation from illuminated Zip Code
bars and compares it to that obtained from a non-
radiating reference bar. A valid code bar is recognized
if the difference exceeds a minimum value.
In all of the above patents for the validation
of banknotes, the note is propelled past the detectors
and does not have a special marking or code. Since the
purpose is to authenticate a bill by comparing its
charact~ristics to those of known genuine
characteristics, the systems and devices are necessarily
complex.
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SUMMA~Y OF THE INVENTION
The present invention is not intended for
currency authentication, but, rather, for use by blind
individuals to identify the denomination of paper
currency or bank notes. This is achieved by providiny a
portable or hand-held banknote reader in which the user
places a banknote in the reader and the reader audibly
announces the denomination of the note. The reader
requires currency which is coded with special code
markings. In order to read the note, the reader
transmits light through the note from one side and senses
the intensity of light passing through the note from the
other side. It converts intensity readings to a series
of signals representative of the presence or absence of
codes on the note, compares the series of signals against
known codes to determine the denomination of the note and
then activates a voice synthesizer to announce the
denomination.
~O Thus, the present invention is generally
defined as a portable banknote reader for determining the
denomination of currency notes having an array of
discrete opaque markings, indicative of the denomination
of the notes, at some or all of predetermined code
locations on the notes, the reader comprising a housing
for receiving a banknote in a prede~ermined position
therein; light source means in the housing for
transmitting light through at least the predetermined
locations of a banknote disposed in the housing; means
disposed in the housing in opposed relation to the light
source means for receiving light transmitted thereby and
responsive thereto for producing a series of signals
representative of the array of markings on a banknote
disposed in the housing; means for comparing the series
of signals against each of a plurality predetermined
signals indicative of denominations of banknotes and
producing an output signal indicative of the actual
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denomination of a note in the housing when the series of
signals matches one of the plurality of predetermined
signals; and means responsive to the comparing means
output signal for producing an audible signal indicative
of the denomination of a note in the housing.
BRIEF DESCRIPTION OF T~IE DRAWINGS
The preferred embodiment of the invention will
now be described in conjunction with the attached
drawings, in which
Figure 1 shows an example Canadian $20 banknote
in outline with special code markings according to the
present invention;
Figure 2 is a perspective depicting the hand-
held device according to the present invention;
Figure 3 is a block schematic of the circuit in
the hand-held device for reading and interpreting the
code markings of Figure 1 according to the present
invention;
Figure 4A, 4B and 4C is a flow chart for the
program operating the device of Figure 2; and
Figure 5 is a flow chart for the French
language subroutine when requested by the user of the
device.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Figure 1 of the drawings shows in outline a
paper currency note 10 for the denomination Canadian
$20.00 having adjacent its narrow edges code markings in
the form of two sets of black squares 11/12 and 13/14
made by printing the currency note 10 with a heavy
intaglio ink. The marking code actually consists of four
binary positions corresponding to four squares on either
side of the note 10. The code for the denomination 20 is
that the outer two most squarss 11, 12, 13 and 14 are
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inkedO The position of the remaining squares is shown
in dotted outline as squares 15, 16, 17 and 18. ~ny four
position binary code is sufficient to identify seven
denominations, ranging from $1.00 to ~100.00, of Canadian
banknotes. The s~uares 11 etc. are made large enouyh to
account for the tolerances during the operation o~
reading of the note 10. A blind person who wishes to ~now
the denomination of the note 10 places the same in a
hand-held device 19, shown in Figure 3 in perspective,
and closes the cover 20. Once the cover 20 is closed,
light emitting panels 21 and 22 face the code squares
11/12 and 13/14. Light emanating from panels 21 and 22
is transmitted through the note 10 and received by four
photosensors (not shown) one opposite each of the squares
11, 12, 15 and 16. Another set of four photosensors is
likewise positioned opposite the squares 13, 14, 17 and
18.
Figure 3 of the drawings shows the opto-
electronic circuitry housed in the device 19, which com-
prises in addition to the light panels 21 and 22 andtwo sets of photosensors 23 and 24, an analague-to-
digital converter 25 for converting the voltage developed
at each of the photosensors into a digital representation.
The analogue-to-digital converter 25 delivers the
digitized voltage values to a microprocessor 26, which
controls the operation of the device by means of a program
stored in a memory 27. A decoder/driver 28, in response
to the microprocessor 26, controls the light panels 21
and 22, the analogue-to-digital converter 25, the memory
27 and a power ON and hold circuit 29 which develops the
necessary power +5 volts and -5 volts from the battery.
A voice synthesis processor 30 is controlled by the
microprocessor 26 to announce the proper value, once
determined by the microprocessor 26, of the note 10 via
an audio amplifier 31 and loud speaker 32. ~he operation
of the circuit shown in Figure 3 will be described with
reference to the flow chart shown in Figures 4A, 4B and 4C.
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In the circuit of Figure 3, a suitable micro-
processor is CMOS CPU part number MC146805E2P, and a
speech synthesizer part number TMS5220NL. The analogue-
to-digital converter could suitably be an 8 bit converter
wi-th 8 channel multiplexer part number ACD808NL. The
eight photosensors in the two sets 23 and 2~ are cadmiwm
sulfide light sensors part number CL1986, which are pre-
ferably driven by a constant current source, one after
the other, as the voltage drop there across is being
sampled by the analogue-to-digital converter 25. In the
alternative, eight matched current sources could be used
one for each photosensor resistor in the arrays 23 and
24. The light panels 21 and 22 are preferably blue-green
electro-luminesent panels manufactured by Luminesent
Systems Inc. This electro-luminesent light panels have
proven sufficient in compensating for the colour
differences between banknotes of different denominations.
It is, of course, possible to use simple incandescent
light, but at the cost of less reliability in differen-
tiating between different notes, possibl~ due to the large
infrared content of the incandescent light. The electro-
luminesent panels require a power supply of 100 volt AC
at approximately 500 Hz, which is not difficult to generate
from the 9 volt battery powering the device.
Negative reference voltage -VREF applied to
the analogue-to-digital converter 25 is ~1.5 V and equals
the lowest value expected as a voltage drop across the
photosensors in the arrays 23 and 24. The highest
possible value is the supply voltage or ~5 V. Accordingly,
the voltage range is 3.5 V, and given an 8-bit resolution
yielding 256 quantisation steps, the resolution is
13.7mV/bit. This provides sufficient digital distance
between the ink and no ink signals as the code markings
on the note 10 are sensed.
The memory 27, in addition to storing the
program for the microprocessor 26, also stores the data
for the speech synthesis processor 30.
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The microprocessor 26 has a shared 8-bit
address and data bus, an 8-bit address/data latch is
therefore required to temporarily store the lower eigh-t
addresses for the memory 27. One of the two 8-bit by-
directional ports of the microprocessor 26 is used as a
data bus Eor the voice synthesis processor 30, and the
other 8-bit port is used for timing -the voice processor
30 and for providing other necessary control functions.
The microprocessor 26 also has 112 bytes of user RAM
memory, which are used to store the data from the
analogue-to-digital converter 25 as well as an overlay
area for program execution. The latter use is necessary
because the microprocessor 26 has a limited ability of
index addressing of only 0 - 255, but the program requires
the entire 4K address range to be index addressed. To
accommodate this requirement, a program is transferred
from the memory 27 to the RAM memory in the micro-
processor 26, then modified and finally executed.
The program shown in flow chart form in Figures
4A, 4B and 4C occupies only about 600 memory locations in
the program memory 27. 2,400 memory locations in the
memory 27 are occupied by -the speech data for the voice
synthesis processor 30. The announcements synthesized
are the denominations ranging from $1 - $100, phrases
"not readable" and "battery low". The remaining 1,000
memory locations in the memory 27 are used for instruc-
tions, constants and other data necessary for the
operation for the microprocessor 26.
In order to initiate a note-reading operation,
the user depresses momentarily the read button which
triggers an SCR rectifier in the power ON/hold unit 29.
The microprocessor 26 then latches up and holds the
power ON and continues to initiate and control the
reading operation until it is terminated at the end of
the phrase announced through the loud speaker 32.
Turning now to Figures 4A, 4B and 4C of the draw-
ings, the cycle of operation is started when the read button is
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pressed and power is applied to the system. The micro-
processor 26 performs an automatic power-up reset and the
direction of each bit of the two by-directional ports is
set. The internal timer i5 initialized and no interrupts
are allowed. If the bat-tery voltage is below 7.5 V, which
is too low for stable operation, no note reading is
at-tempted and the system exits by announcing a "poT~er low"
condition.
Next the data from the analogue-to-digital
converter 25 is read into the RAM of the microprocessor
26, which tests each of the eight readings corresponding
to the eight photosensors to see if all of them are low
enough to indicate that there is no note in the notereader,
in which case the voltage vaLues would be between 0 and
~0.25V. The CPU 26 then looks for the lowest value on
each end of 9 sensors, if all are above ~0.25V, this is
then recognized as the paper only value, meaning that at
that code position there is no ink. Having located the
no ink or paper only signal from the row data, a new
2~ table is created by subtracting the paper only signal
from the four raw readings of each of the two sets of
photosensors. This in effect leaves only the ink signals
in the new table. A threshhold calculation is then per-
formed separately for each of the two sets of photosensors
23 and 24. ~he threshhold is calculated as the ink only
signal divided by 2, which if found to be less than
0.25V, causes the rejection of that threshhold as a
minimum threshhold and replaces it with the minimum
threshhold of 0.25V. Once the minimum threshhold is
determined, an ink map is prepared by setting a bit
within a four bit code ~or every sensor which exceeds
the minimum threshhold. We now have two sets of four
bits each representative of the presence and absence of
ink squares on either side of the currency note. The
two four bit codes are compared with each other and if
they do not match a "not readable" announcement is
generated.
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If there is a match between the two four bit
codes in the ~, then the four bit code is used to
retrieve the denomination from a code/denomination table
or matrix stored ln 27. If the four-bi-t code is not
found in the table, -then a "not readable" announcement is
generated.
In the above description in all cases where
the announcement is to be made in the French language
because such was selected by the operator, a minor sub-
routine shown in Figure 5 causes all announcements to be
made in French.
Once an announcement has been completed by
the voice synthesis processor 30, the microprocessor 26
causes the power to be turned off.
