Image analysis – Applications – Reading paper currency
Reexamination Certificate
1998-04-15
2002-05-21
Au, Amelia M. (Department: 2623)
Image analysis
Applications
Reading paper currency
C382S228000, C902S006000
Reexamination Certificate
active
06393140
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to bill identifying devices for use in automatic bending machines, money changing machines, game machines and the like, and more particularly to a paper-like piece identifying method and device for validating (i.e., testing authenticity of) a variety of paper-like pieces, such as bills (bank notes), checks, credit slips, tickets and securities, having distinctive designs or patterns (drawings, characters, etc.) borne on their surfaces as by printing.
Bill identifying or validating devices are known from, for example, Japanese Patent Publication Nos. SHO-63-26918 and SHO-64-5354, which are designed to acquire sample data or detected data by use of sensors to identify types and densities of colors on various regions of a bill as well as magnetic powder contained in the bill in synchronism with transport of the bill and then compare the thus-acquired detected data to a known standard pattern to thereby determine the authenticity or genuineness of the bill. In these known bill identifying devices, an “authentic bill” signal for a given denomination is issued only when all the data sampled from individual positions of the bill fall within an allowable tolerance from the known standard pattern for the denomination. Reliability of the thus-identified denomination and authenticity depends only on an evaluated difference between values of the detected data for each of the positions and the standard pattern data. Thus, in order for the bill identifying devices to reliably exclude false bills, it is necessary to set a considerably narrow tolerance as the determination standard; however, too-narrow tolerances could result in the problem that an authentic bill is erroneously determined to be “false” even when values of detected data for the individual positions have been shifted uniformly by presence of a large stain on the virtually whole surface of the bill.
Further, in the case of bills, such as U.S. dollar bills, having closely similar or approximate printed designs among various denominations, the tolerances for the different denominations would often overlap, which would therefore prevent accurate identification of the bills.
Japanese Patent Publication No. SHO-58-9990 proposes an improved bill identifying device, which is designed to compare detected data for the individual positions to a standard pattern after modifying or adjusting the detected data by use of an average of the data, in order to appropriately deal with undesirable variations in detected data due to stains and aging of a bill and drift of detected data values due to ambient temperature variations. But, the proposed bill identifying device would also erroneously determine and reject an authentic bill as false when the bill has a partial stain thereon presenting a partial detected data variation. Further, Japanese Patent Laid-open Publication No. HEI-2-148383 proposes another improved bill identifying device which prestores relations between standard data and frequency distribution data for each denomination and makes the bill identification on the basis of the fuzzy logic. But, the proposed bill identifying device can not appropriately deal with stains and aging of bills, sensors, etc., because, even when there has occurred a variation in detected data themselves, no specific adjustment is made at all to retain their correspondence with the frequency distribution data.
Because a multiplicity of detected data are generally necessary for accurate identification of denomination and authenticity of a bill, it has been conventional to use optical and magnetic sensors in combination, which, however, would require separate determination circuits for the optical sensors and magnetic sensors, thereby making the overall structure of the device very complex.
Other bill identifying techniques pertinent to the present invention are known from Japanese Patent Laid-open Publications Nos. HEI-3-292589 and HEI-4-102187.
According to the approach disclosed in the HEI-3-292589 publication, sensor-detected data are averaged for subsequent normalization of the data, a ratio of the average value of the sensor-detected data to a predetermined standard average value is determined as an adjustment coefficient, and then the data normalization is effected by multiplying the sensor-detected data by the determined ratio. However, the data normalization employed here is a very simple one and hence would be adversely influenced by various error factors such as stains on individual sensors employed, different operating characteristics and assemblage errors of the sensors and stains on individual bills to be tested.
According to the approach disclosed in the HEI-4-102187 publication, each bill to be tested is divided into a plurality of regions or blocks, a difference is calculated between an average value of detected data for each of the blocks and standard average value data for that block, and the thus-calculated differences for the individual blocks are summed. The sums of such differences are calculated for all denominations, and then one of the denominations for which the calculated sum is the smallest is determined as the denomination of the tested bill. However, because the differences are calculated from an average of absolute values of the detected data, this approach would present the drawback that identification accuracy tends to be poor because bills to be tested have different types and degrees of stains and the like.
SUMMARY OF THE INVENTION
It is therefore an object Of the present invention to provide a paper-like piece identifying method and device capable of validating a paper-like piece with increased accuracy by minimizing determination errors that would be caused by detected data variations due to aging of and partial stains on a paper-like piece and by eliminating adverse influences of determination errors due to unique errors and aging of bill-characteristic detecting sensors.
It is another object of the present invention to provide a paper-like piece identifying method and device which achieve appropriate normalization of sample data detected via characteristic-detecting sensors, by performing accurate data adjustment based on extraction of printed design characteristics from the sample data.
It is still another object of the present invention to provide a paper-like piece identifying method and device which achieve accurate validation of a paper-like piece in consideration of uniqueness of the paper-like piece, using statistical totalization of sample data.
It is still another object of the present invention to provide a paper-like piece identifying method and device which can perform validation of paper-like pieces as accurately as possible even when the paper-like pieces are closely similar in design borne thereon.
It is still another object of the present invention to provide a paper-like piece identifying method and device which can perform high-accuracy validation of a paper-like piece only with an optical sensor, without using a magnetic sensor.
According to a first aspect of the present invention, there is provided an paper-like piece identifying method which comprises: a first step of detecting characteristics of a particular paper-like piece to be identified by use of a sensor, to provide detected data for a plurality of predetermined positions on the paper-like piece; a second step of converting the detected data for each of the predetermined positions into relative value data to a predetermined value; a third step of normalizing the relative value data by use of a predetermined normalization parameter, to thereby provide adjusted sample data for each of the predetermined positions; and a fourth step of statistically evaluating the adjusted sample data for each of the predetermined positions by use of a standard average and standard deviation previously set for each of the predetermined positions, to thereby identify the paper-like piece.
By converting the detected data from the sensor into relative value data, it is possible to provide data repre
Au Amelia M.
Miller Martin
Morrison & Foerster / LLP
Nippon Conlux Co., Ltd.
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