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.
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. 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.
A currency evaluation device for receiving a currency bill having a magnetic 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.
Other objects and advantages of the invention will become apparent upon reading the following detailed description in conjunction with the drawings in which:
a 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;
b is a perspective view of a bill and a preferred area to be optically scanned on the bill;
c 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;
a and 6b are a flowchart of the operation of a currency discrimination system according to one embodiment of the present invention;
a and 11b comprise a flowchart illustrating the sequence of operations involved in implementing the discrimination and authentication system of
a and 12b are top views of U.S. currency illustrating the location of various magnetic features;
a and 16b are top views of U.S. currency illustrating various scanning areas according to an embodiment;
a-17d are top views of sensor arrangements according to several embodiments of the present invention;
According to one embodiment of the present invention, multiple scanheads or sensors per side are used to scan a bill.
Referring now to
The optical scanheads (18 of
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 magnetic, optical, electrical conductivity, and capacitive sensors. Use of such sensors is discussed in more detail below, for example, in connection with
Referring again to
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. Pat. 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.
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 U.S. Pat. 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 correlation technique disclosed in U.S. Pat. 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.
a-4c illustrate the scanning process of scanheads in more detail. Referring to
As illustrated in
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
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 U.S. Pat. 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 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 30 is also linked to an output unit 36 (
A procedure for scanning bills and generating characteristic patterns is described in U.S. Pat. No. 5,295,196 referred to above and incorporated by reference in its entirety and in commonly owned U.S. Pat. No. 5,633,949 entitled “Method and Apparatus for Currency Discrimination” filed on May 16, 1994.
The optical sensing and correlation technique described in U.S. Pat. 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 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
Referring now to
The operation of a currency discriminator according to one embodiment of the present invention may be further understood by referring to the flowchart of
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
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
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, Minn. 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 effect 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 (U.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.
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 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 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 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 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. If 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 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 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 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.
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.
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.
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.
Alternatively, to the operation of the magnetic sensor described above in connection with
Referring next to
The optical scanhead 260 of the embodiment depicted in
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.
While scanhead 260 in the embodiment of
Retrieved characteristic information can include reflected light properties such as 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 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), 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, Minn. 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 (U.S. Pat. No. 4,381,447), color (U.S. Pat. Nos. 4,490,846; 3,496,370; 3,480,785), size including length and width, thickness (U.S. Pat. No. 4,255,651), the presence of a security thread (U.S. Pat. No. 5,151,607) and holes (U.S. Pat. No. 4,381,447), and other patterns of reflectance and transmission (U.S. Pat. Nos. 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, and/or dichroic beamsplitters (U.S. 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 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 assignee's co-pending U.S. patent application Ser. No. 08/317,349, filed Oct. 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.S. Pat. No. 5,122,754 [watermark, security thread]; U.S. Pat. No. 3,764,899 [thickness]; U.S. Pat. No. 3,815,021 [dielectric properties]; U.S. Pat. No. 5,151,607 [security thread]), and mechanical sensing (U.S. Pat. No. 4,381,447 [limpness]; U.S. Pat. No. 4,255,651 [thickness]).
Referring again to
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 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 different currency denominations. This process is more fully explained in U.S. patent application Ser. No. 07/885,648, filed on May 19, 1992, now issued as U.S. Pat. No. 5,295,196 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 U.S. Pat. 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 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
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. 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 sufficient correlation exists 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
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
The interrelation between the use of the first and second type of characteristic information can be seen by considering
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 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 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 306), then the denomination of the scanned bill is indicated (step 310) and the process is ended (step 312).
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 in 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
Some of these magnetic characteristics vary by denomination. For example, in
Examples of arrangements of magnetic sensors that may be used to detect the above described magnetic characteristics are illustrated in
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
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
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
Alternatively, magnetic sensors 364a-d, 366a-g, and 374a-c may detect the 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
Another denominating or authenticating technique may be understood with reference to area 346 of
The sensors of
For example, the staggered arrangement of sensors 366 depicted in
Additionally, the location of the thread within the bill can be used as a security 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 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 disclosed in U.S. Pat. No. 5,992,601 incorporated by reference above. Referring to
Referring now to
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 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 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
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 bill perpendicular to the direction of travel. For example, referring to
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 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
The inventors have found that a magnetic scanhead 400 having a scanning length L1, 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 effectively 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
The sensors 402 of the magnetic scanhead 400 illustrated in
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
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.
This application is a continuation-in-part of copending U.S. patent application Ser. No. 09/450,187 filed Nov. 29, 1999. U.S. patent application Ser. No. 09/450,187 is a continuation of U.S. Pat. No. 5,992,601 filed Feb. 14, 1997. U.S. Pat. No. 5,992,601 claims the benefit of Provisional Patent Application Ser. Nos. 60/011,688 filed Feb. 15, 1996, now abandoned, and 60/018,563 filed May 29, 1996, now abandoned.
Number | Date | Country | |
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60/018,563 | May 1996 | US | |
60/011,688 | Feb 1996 | US |
Number | Date | Country | |
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Parent | 08/800,053 | Feb 1997 | US |
Child | 09/450,187 | Nov 1999 | US |
Number | Date | Country | |
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Parent | 09/450,187 | Nov 1999 | US |
Child | 09/684,103 | US |