EP1149363B1 - Sensor for evaluating dielectric properties of specialized paper - Google Patents

Sensor for evaluating dielectric properties of specialized paper Download PDF

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Publication number
EP1149363B1
EP1149363B1 EP99904649A EP99904649A EP1149363B1 EP 1149363 B1 EP1149363 B1 EP 1149363B1 EP 99904649 A EP99904649 A EP 99904649A EP 99904649 A EP99904649 A EP 99904649A EP 1149363 B1 EP1149363 B1 EP 1149363B1
Authority
EP
European Patent Office
Prior art keywords
electrode
arrangement
generating
receiving
channel
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP99904649A
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German (de)
English (en)
French (fr)
Other versions
EP1149363A1 (en
Inventor
Vladymir Barchuk
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Cashcode Co Inc
Original Assignee
Cashcode Co Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Cashcode Co Inc filed Critical Cashcode Co Inc
Priority claimed from PCT/CA1999/000117 external-priority patent/WO2000046760A1/en
Publication of EP1149363A1 publication Critical patent/EP1149363A1/en
Application granted granted Critical
Publication of EP1149363B1 publication Critical patent/EP1149363B1/en
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Classifications

    • G—PHYSICS
    • G07—CHECKING-DEVICES
    • G07D—HANDLING OF COINS OR VALUABLE PAPERS, e.g. TESTING, SORTING BY DENOMINATIONS, COUNTING, DISPENSING, CHANGING OR DEPOSITING
    • G07D7/00—Testing specially adapted to determine the identity or genuineness of valuable papers or for segregating those which are unacceptable, e.g. banknotes that are alien to a currency
    • G07D7/02—Testing electrical properties of the materials thereof
    • G07D7/026—Testing electrical properties of the materials thereof using capacitive sensors

Definitions

  • the present invention relates to validators having sensors for evaluating dielectric properties of specialized papers.
  • the invention has particular application for paper currency evaluation and security appear evaluation.
  • Currency validators are designed to receive a banknote and move the banknote through an evaluator channel prior to accepting and storing of the accepted banknote. From time to time a banknote can become jammed in the validator which creates problems, particularly for unsupervised installations.
  • the capacitive sensor can determine the "humidity" of currency paper and can be used to evaluate the authenticity of the paper, as the currency paper is being evaluated by the validator.
  • the design of automatic validators makes contradictory demands.
  • the size of the sensor should be small. It should be designed in such a way that it can be placed anywhere inside the validator channel. Rigid mechanical and electrical connections between the sensor elements placed on the opposite sides of the validator channel lead to complex configurations. The measurement results should not significantly vary with wobble of the paper in the validator channel. It is also desirable for the validator to reject bills which are likely to become jammed in the validator.
  • the present invention is directed to an arrangement for sensing the dielectric properties of a paper substrate as the paper substrate moves through an evaluation channel, as described in claim 1.
  • the arrangement further includes a screening electrode located on the first side of the channel and connected to the electronic processing arrangement in a manner to diminish capacitance due to direct coupling of the generating electrode and the receiving electrode.
  • the generating electrode is provided with an alternating voltage high frequency signal.
  • the passive conducting electrode has no electrical connection with the electronic processing arrangement.
  • the processing arrangement converts any high frequency signal received by the receiving electrode into a d.c. voltage which provides a measure of the capacitive coupling of the generating and receiving electrodes which is greatly changed in accordance with the banknote currency.
  • the electronic processing arrangement uses the d.c. voltage to assess the humidity of a substrate located in the evaluation channel.
  • the electronic processing arrangement in a preferred aspect of the invention uses a measurement of capacitance for determining the humidity of the substrate and rejects the substrate when the determined humidity is grater than a predetermined level. It also rejects dry fraudulent bills with deviations of the dielectric properties relative to known dielectric properties of authentic bills.
  • Currency or banknote validators move a banknote along a particular path and assuming the banknote is accepted, typically store the banknote in a stacking arrangement.
  • the pathway through the validator has a number of sensors placed there along for evaluating the banknotes as it passes the sensor.
  • Various drive wheels advance the banknote from the entrance to the validator to the banknote stacking arrangement.
  • An example of such a validator is shown in our United States Patent 5,657,846.
  • a capacitive sensor 2 is shown in Figure 1 and is located in the channel 4 through which the banknote 7 is passed for evaluation in the direction of arrow B.
  • the channel 4 includes opposed channel walls 5 and 6 which are made of a plastic or similar dielectric isolating material.
  • the channel walls 5 and 6 include slots therein for receiving the generator electrode 11 and the receiving electrode 12 as well as the screening electrode 14 in the channel wall 5.
  • a large flat passive electrode 13 located in a slot in the channel wall 6. This flat passive electrode 13 is situated directly over and is parallel to the generator electrode 11 and the receiving electrode 12.
  • the passive electrode 13 is sized and placed within the channel walls 6 such that the projection of electrode 13 on the wall 5 of the channel covers both the generator electrode 11 and the receiving electrode 12.
  • the purpose of the passive electrode is to couple the electrodes in a manner to be directly influenced by the change in capacitance caused by the dielectric properties of the banknote 7 passing between the electrodes.
  • the screening electrode 14 serves to reduce the direct coupling between the generating electrode 11 and receiving electrode 12.
  • the banknote 7 As the banknote 7 is transported along the channel 4, it is located between the electrodes, and thus significantly effects the magnitude of the capacitive coupling of the electrodes. Generally, the banknote is parallel to electrodes 11, 12 and 13, however, it may be nonparallel because of some wobble on the banknote.
  • the exact position of the banknote between the electrodes is not critical as the net is tolerable because capacitance is mainly dependent on the presence of the banknote between the electrodes and the exact location of the banknote between the electrodes is not as significant.
  • the sensing arrangement of Figure 1 is quite compact and rugged and there is no requirement to electrically hard wire the passive electrode 13 to the processing circuitry.
  • the components on one side of the.pathway remain stationary and components on the opposite side of the pathway move when the validator is opened.
  • the channel wall 5 can be located in the stationary part of the validator and thus, its electrical connection to the processing circuitry is simple and straightforward, and does not have to accommodate movement for service.
  • the passive electrode 13 is located in the moving part of the housing.
  • a high frequency generator 9 is connected with the generating electrode 11; the feed of the high frequency generator is also provided to the lock-in detector 20 and is used as a reference signal.
  • the receiving electrode 12 is connected with one of the differential inputs of the lock-in detector 20.
  • Another differential input of the lock-in detector 20 is supplied with the compensating high frequency signal formed by the capacitance divider C1-C2.
  • the screening electrode 14 is connected with the ground of the system.
  • the signal formed by the lock-in detector 10 is amplified by amplifier 11 and is subsequently converted to a digital signal which may be analyzed by the program of the central processing unit 25. At certain levels of the signal, the banknote is rejected as having too high a moisture level, otherwise the signal is compared to the appropriate standard of authentic currency.
  • FIG 3 shows a schematic of the capacitance of the various electrodes of the sensor and the elements of the electronic processing arrangement that are directly associated with the electrodes.
  • C11-12 is the capacitance between the generating electrode 11 and passive electrode 12;
  • C13-12 is the capacitance between the passive electrode 13 and receiving electrode 12.
  • these capacitances are the ones of plane capacitors.
  • C11-12 is negligibly small in the case of installed screening electrode 14.
  • Figure 3 also illustrates capacity divider C1, C2 for the signal of the high frequency generator 9, input capacitance C and input active resistances R of the inputs of the lock-in detector 20. It can be seen that the capacitors form a capacitance bridge with generator 9; the outputs of the bridge are connected to the inputs of the lock-in detector 10.
  • the bridge may be balanced by adjusting capacitance divider C1, C2.
  • a d.c. voltage is produced at the output of the lock-in-detector 10.
  • the resulting voltage is a direct function of the unbalanced state of the bridge.
  • the interelectrode capacitances are small, generally not exceeding 10 pF.
  • the input capacitances of the lock-in detector are of the same order of magnitude. To achieve a useful sensitivity, a high generating frequency is used. It has been determined that the preferred frequency range is between 50 - 150 MHz. At these frequencies, the impedances of the bridge capacitances are smaller than the input active resistances R of lock-in detector and, therefore, the input resistances only marginally effect the phase and amplitude characteristics of the bridge.
  • the elements C1 and C2 can be excluded from the circuit if their absence does not saturate lock-in detector 20. In their absence, the system can be balanced by varying the input voltage shift of d.c. amplifier 11.
  • the capacitances of C11-13 and C13-12 increase and unbalance the capacitance bridge.
  • the magnitude of the disbalance signal is isolated from effects of wobble the paper in the validator channel and essentially depends on the dielectric properties of the currency paper.
  • the system determines the authenticity of the dielectric properties of the currency paper.
  • the dielectric constant of water is approximately 10 times larger than the dielectric constant of dry currency paper.
  • currency paper having high humidity provides high capacitance and produces a large signal in the sensor.
  • the magnitude of the output signals gives information about the humidity of the currency paper. If the measured signal is too high, the banknote is rejected.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)
  • Inspection Of Paper Currency And Valuable Securities (AREA)
EP99904649A 1999-02-01 1999-02-17 Sensor for evaluating dielectric properties of specialized paper Expired - Lifetime EP1149363B1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
CA002261081A CA2261081C (en) 1999-02-01 1999-02-01 Sensor for evaluating dielectric properties of specialized paper
CA2261081 1999-02-01
PCT/CA1999/000117 WO2000046760A1 (en) 1999-02-01 1999-02-17 Sensor for evaluating dielectric properties of specialized paper

Publications (2)

Publication Number Publication Date
EP1149363A1 EP1149363A1 (en) 2001-10-31
EP1149363B1 true EP1149363B1 (en) 2004-01-07

Family

ID=4163261

Family Applications (1)

Application Number Title Priority Date Filing Date
EP99904649A Expired - Lifetime EP1149363B1 (en) 1999-02-01 1999-02-17 Sensor for evaluating dielectric properties of specialized paper

Country Status (8)

Country Link
EP (1) EP1149363B1 (ja)
JP (1) JP2002536751A (ja)
CN (1) CN1187719C (ja)
AU (1) AU772710B2 (ja)
BR (1) BR9917015A (ja)
CA (1) CA2261081C (ja)
DE (1) DE69914107T2 (ja)
ES (1) ES2214008T3 (ja)

Families Citing this family (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4599566B2 (ja) * 2004-08-31 2010-12-15 国立大学法人 新潟大学 不均一電場を使用した非極性複合分子の運動の電気的検出法
JP4622694B2 (ja) * 2005-06-16 2011-02-02 富士電機リテイルシステムズ株式会社 紙幣識別装置
DE102013205048A1 (de) * 2013-03-21 2014-09-25 Bundesdruckerei Gmbh Vorrichtung und Verfahren zur Echtheitsüberprüfung eines Wert- oder Sicherheitsdokuments
WO2015029904A1 (ja) * 2013-09-02 2015-03-05 アルプス電気株式会社 水分検出装置
KR101554253B1 (ko) 2013-12-20 2015-09-18 노틸러스효성 주식회사 금융자동화기기의 젖은 지폐 감지장치 및 감지방법
CN104049003A (zh) * 2014-06-10 2014-09-17 中国人民银行印制科学技术研究所 一种阵列电容式感应传感器及有价证券防伪检测方法
CN107393116B (zh) * 2017-07-06 2023-04-25 得力集团有限公司 一种验钞机及其验钞方法和电路结构
JP2019120582A (ja) * 2018-01-05 2019-07-22 株式会社リコー 特性検知装置、媒体供給装置および画像形成装置
CN109345685A (zh) * 2018-11-09 2019-02-15 威海华菱光电股份有限公司 纸质品鉴别方法和装置及存储介质
CN115932977A (zh) 2018-12-05 2023-04-07 三菱电机株式会社 静电电容检测装置及图像读取装置

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4355300A (en) * 1980-02-14 1982-10-19 Coulter Systems Corporation Indicia recognition apparatus
NO165697C (no) * 1988-03-10 1991-03-20 Inter Marketing Oy Ab Sensor for ekthetskontroll av sikkerhetspapir.
DE4232185A1 (de) * 1992-09-25 1994-03-31 Chemnitz Textiltech Forsch Verfahren und Vorrichtung zur berührungslosen Messung des Restfeuchtegehaltes von bewegten Materialbahnen

Also Published As

Publication number Publication date
CN1348573A (zh) 2002-05-08
AU772710B2 (en) 2004-05-06
CA2261081C (en) 2006-05-09
AU2506299A (en) 2000-08-25
JP2002536751A (ja) 2002-10-29
DE69914107D1 (de) 2004-02-12
EP1149363A1 (en) 2001-10-31
CN1187719C (zh) 2005-02-02
CA2261081A1 (en) 2000-08-01
BR9917015A (pt) 2002-01-15
ES2214008T3 (es) 2004-09-01
DE69914107T2 (de) 2004-10-21

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