CN201242779Y - Dynamic multi-frequency detector for coin magneto-electric characteristic parameter - Google Patents
Dynamic multi-frequency detector for coin magneto-electric characteristic parameter Download PDFInfo
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- CN201242779Y CN201242779Y CNU200820035971XU CN200820035971U CN201242779Y CN 201242779 Y CN201242779 Y CN 201242779Y CN U200820035971X U CNU200820035971X U CN U200820035971XU CN 200820035971 U CN200820035971 U CN 200820035971U CN 201242779 Y CN201242779 Y CN 201242779Y
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Abstract
The utility model relates to a dynamic multi-frequency test instrument for electromagnetic characteristic parameter of coin, belonging to the technical field of coin discrimination. In the test instrument, an output end of a coin in-place detection circuit is connected with a microprocessor; a frequency control output end of the microprocessor is connected with a controllable end of a variable frequency signal generator; an output of the variable frequency signal generator is connected with an input of a detection winding; an output of the detection winding is connected with a signal input of an operational circuit, an output of the operational circuit is connected with an input end of the microprocessor after modulus conversion. The utility model can detect the change of magnetic conduction rate and average electric conduction rate of coin on frequency representing coin difference best by adopting multi-frequency detection method, thereby determining the electromagnetic characteristic parameters under wide frequencies.
Description
Technical field
The present invention relates to a kind of detector of coin parameter, belong to coin authentication detection technology field.
Background technology
In the facility of automatic vending machine and so on, generally adopt coin to conclude the business.In the automatic identifying of coin, the magnetoelectricity feature is one of main foundation of distinguishing coin kind and denomination.For the comprehensive presentation of coin in automatic recognition system that makes same value of money has uniqueness mutually, should guarantee that at first the magnetoelectricity feature of coin has uniqueness in range of application.Therefore, detecting the magneto-electric behavior of coin in a general frequency range has great importance.
The current vortex detection technique is used widely in the coin recognizing method field, its ultimate principle as shown in Figure 1, according to Faraday's electromagnetic induction law, when magnetic test coil passed to exchange current, the coil surrounding space certainly led to alternating magnetic field Hp, under the effect of this alternating magnetic field, induce current vortex in the coin in the magnetic field, current vortex produces the alternating magnetic field Hs that makes new advances again, and it is opposite with former magnetic field H p direction, thereby the apparent impedance of coil is changed.Its intensity of variation depends on factors such as the physical dimension, resistivity, magnetic permeability, pattern structure, excitation frequency of coin.Domestic and international most Coin validator all uses the current vortex detection technique, and just each Coin validator has different aspect processing in input.This technology has utilized coin can make the equivalent inductance of magnetic test coil and resistance produce the principle of significant change, and these change to adopt the circuit indirect detection, discern the type of coin thus.
Publication number is that the Chinese patent application of CN1445726 discloses a kind of Coin validator, and this recognizer is not made any distinction between by the influence of current vortex to coin conductivity and magnetic permeability, but according to coin coin is differentiated in the influence of amplitude in the oscillatory circuit and frequency.Oscillatory circuit in this recognizer is connected in series a pair of magnetic test coil.When coin entered detection zone, the complex impedance of magnetic test coil will change, and the amplitude of oscillatory circuit and frequency are also done corresponding variation, recognizer is done certain processing to these variations, form corresponding recognition mode, and then compare, thereby judge its true and false and value of money with the pattern of storing.Because the current vortex frequency range of this Coin validator is single, frequency stability is poor, for distinguishing at the close coin of this frequency magnetoelectricity feature presentation.
In addition, publication number is that the Chinese patent application of CN1856808 discloses another kind of Coin discriminator, and this Discr. uses continuous wave method or pulse method to differentiate the true and false and the value of money of coin.Wherein the continuous wave method uses two alternating signals of high and low frequency to drive single coil simultaneously, adopts phase sensitive detector to detect amount relevant with the coin Facing material and the amount relevant with the coin main material.Calculate the ratio of these two amounts again.These values are compared with the value of machine stored, thereby determine its true and false and value of money.This Discr. still can not fundamentally be eliminated the predetermined single error that causes of frequency of coin.
In a word, above prior art is all powerless for the identical different Currency Types of the magnetoelectricity feature presentation that may exist at specific frequency, can not discern.In addition, because detected parameters is less relatively, and is indirect physical quantity, quantity of information is little, is difficult to carry out data analysis and handles, and is not suitable for the machine-readable magnetoelectricity Feature Extraction of coin, has limited coin manufacturing and the false proof useful information that provides are provided.
Summary of the invention
The present invention wants the technical solution problem to be: at the shortcoming of above prior art existence, a kind of Coin magnetoelectric characteristic parameters dynamic multi-frequency detector is proposed, this instrument can be got rid of the extraneous factor influence, and effectively difference is included in the identical different Currency Types of specific frequency magnetoelectricity feature presentation at interior various coins.
Studies show that, because the manufacturing of coin generally includes multiple working procedures such as the blanking of base cake, plating, stamp, so different coins has specific magneto-electric behavior usually.Though can reflect these characteristics by the current vortex phenomenon, but because it is more to influence the factor of Coin magnetoelectric feature, the for example electrology characteristic of main material, magnetism characteristic, the electricity of coating material, magnetism characteristic, therefore the manufacturing process of coin and structure etc. will know very difficulty of its comprehensive presentation by inference by the characteristic of unlike material and the constituted mode of coin.When the coil formation that is connected with exchange current is close in the alternating electromagnetic field of coin face, can in coin, cause eddy current, its result makes the apparent impedance of coil that variation take place, and the variation characteristic of apparent impedance depends on the frequency of magnetic permeability, conductivity, proportion of composing and the alternating magnetic field of coin.
The inventor herein recognizes in above research process gradually, when in that the apparent impedance variation under coin or the influence of its equivalent combinations body accurately detects to coil on the predetermined effective frequency, will open up a feasible way that solves the invention described above technical matters.Conclude through summing up, it is as follows that the applicant draws Coin magnetoelectric characteristic parameters dynamic multi-frequency detection method step of the present invention:
1), when defeated coin mechanism is transported to effective surveyed area of magnetic test coil with coin, provides the coin signal that puts in place; 2), the pumping signal of at least two predetermined frequencies successively is loaded into magnetic test coil, make the apparent impedance generation respective change that produces corresponding eddy current in the coin and cause magnetic test coil; 3), write down the corresponding apparent impedance delta data that magnetic test coil causes because of the counter field effect on each predetermined frequency; 4), the apparent impedance delta data that records is carried out Signal Pretreatment by pre-defined algorithm; 5), with the performance data of data pre-service result as coin to be measured, compare with the corresponding calibration characteristic data of series standard coin, thereby draw the detection result of determination.
Because theoretical research fully proves, when coin is in alternating magnetic field, the electric eddy current density of wherein inducting is along with from the increase of surface distance and reduce, it changes conductivity and the magnetic permeability that depends on excitation frequency and coin fully, therefore method of the present invention has scientific basis, practical, can be used as the machine-readable magnetoelectricity feature of coin to be measured magnetic permeability and average conductivity feature under different frequency.In order to eliminate the influence of edge effect to testing result, the diameter of magnetic test coil should be less than 1/2nd of coin diameter.
The Coin magnetoelectric characteristic parameters dynamic multi-frequency detector that is used to realize said method mainly is made up of put in place testing circuit, microprocessor, variable ratio frequency changer signal generator, magnetic test coil, computing circuit of coin; Put in place the output termination microprocessor of testing circuit of described coin is transferred to microprocessor in order to signal that coin is put in place; The controlled end of the described variable ratio frequency changer signal generator of frequency control output termination of described microprocessor is in order to control the pumping signal that the variable ratio frequency changer signal generator successively sends at least two predetermined frequencies; The output of described variable ratio frequency changer signal generator connects the input of magnetic test coil, is loaded into magnetic test coil in order to the pumping signal with each predetermined frequency; The output of described magnetic test coil connects the signal input part of computing circuit, behind the corresponding apparent impedance variable signal input computing circuit that coin to be measured is caused at the counter field that produces on each predetermined frequency, carries out Signal Pretreatment by pre-defined algorithm; The output of described computing circuit connects the input end of microprocessor after analog to digital conversion, in order to the characteristic of Signal Pretreatment result as coin to be measured, compare with the corresponding demarcation characteristic of series standard coin, draws the detection result of determination.
Because different Currency Types are minimum two identical possibilities of predetermined frequency magnetoelectricity feature presentation, this possibility trends towards zero when frequency further increases, therefore testing result of the present invention not only can be avoided such as the influence of other extraneous factors such as temperature to coin recognizing method, and can effectively distinguish in the identical different Currency Types of specific frequency magnetoelectricity feature presentation, the technical level and the accuracy of coin false distinguishing have obviously been improved, compared with prior art, have outstanding substantive distinguishing features and obvious improvement.
Description of drawings
The present invention is further illustrated below in conjunction with accompanying drawing.
The basic principle schematic that Fig. 1 detects for current vortex.
Fig. 2 is the schematic block circuit diagram of one embodiment of the invention.
Fig. 3 is the circuit theory diagrams corresponding with Fig. 2.
Embodiment
Embodiment one
The Coin magnetoelectric characteristic parameters dynamic multi-frequency detector basic comprising of present embodiment partly is made of put in place testing circuit, DSP microprocessor etc. of DDS variable ratio frequency changer signal generator, AMP broadband power driving circuit, I-V conversion equipment, ADC mould/number (A/D) change-over circuit, LPF low-pass filter circuit, coin as signal source as shown in Figure 2.Wherein, the each several part circuit can be integrated in respectively in the module chip (Module) as required.
The physical circuit of present embodiment is seen Fig. 3, mainly is made up of DSP microprocessor 7 (model ADS2100), DDS signal source chip (AD9854) 1, power driving circuit 2, magnetic test coil 3, I/V change-over circuit 4 and two-way LPF low-pass filter circuit 5 as the variable ratio frequency changer signal generator, A/D change-over circuit 6, the coin testing circuit 9 that puts in place.Whether the sensor 9 that coin puts in place in the testing circuit can arrive correct detection position by perception coin to be measured, its output termination microprocessor, after detecting the correct detection position of coin arrival, send the coin signal that puts in place to microprocessor, notice microprocessor 7 begins to carry out parameter detecting control.Controlled end in the frequency control of the microprocessor output termination signal generator sends pumping signal in order to control variable ratio frequency changer signal generator 1 (experimental results show that: predetermined frequency 98 KHz, 382 KHz, that 816 KHz detect effect is the most remarkable) on adjustable frequency scope (3 KHz are to 3 megahertzes) multiple spot frequency.Contain D/A and I/V change-over circuit in the frequency variation signal generator 1, therefore pumping signal is by D/A, I/V conversion back output, lead up to behind the LPF low-pass filter circuit 5, through A/D change-over circuit 6 input microprocessors 7, as reference signal, another road connects the input of magnetic test coil after by power driving circuit 2, is loaded into magnetic test coil 3 successively in order to the pumping signal that will be scheduled to frequency.
The output of magnetic test coil 3 is carried out Signal Pretreatment by I/V change-over circuit 4 and the 2nd LPF low-pass filter circuit, connect the signal input part of microprocessor again through A/D change-over circuit 6, in order to the effect that magnetic test coil is subjected to the counter field that coin to be measured produces on preset frequency and the apparent impedance change modeling amount that causes is converted into data volume, and send into microprocessor.Microprocessor as the characteristic of coin to be measured, carries out data pre-service by fourier transform algorithm with the data of input, compares with the corresponding calibration characteristic data of series standard coin, draws the detection result of determination.This microprocessor communicates to connect by usb communication interface 8 and host computer, can finish the transmission that detects data.
During detection, signal source itself for system provides the pumping signal with high frequency and phase stability, has guaranteed the accuracy of testing result by synthetic (DDS) technology of numerical frequency.The broadband power driving circuit carries out power amplification to the signal of signal source, for magnetic test coil provides enough detection electric currents; The I-V conversion equipment becomes the coin information current conversion that comprises in the magnetic test coil voltage of certain amplitude, the LPF circuit carries out filtering to the interference that exists in the detection signal, convert digital quantity to for the A/D change-over circuit, microprocessor carries out by the conversion of time domain to frequency domain detected information, obtain to detect under each frequency the real part and the imaginary part of voltage, and calculate the actual value of magnetic test coil apparent impedance under each frequency according to the output amplitude of signal source, send to PC, compare one by one with the corresponding demarcation characteristic of the series standard coin of previous mensuration, as identical with the demarcation characteristic of actual value and a certain standard coinage, then be judged to be this kind coin, otherwise be judged to be counterfeit money, thereby obtain the final decision result that the dynamic attitude multifrequency of required Coin magnetoelectric characteristic parameters detects.The real-time analysis of testing result both can be finished in PC by interface with processing, also can finish in microprocessor.
Test shows, when detect frequency greater than some values (this value corresponding to the skin depth of this Currency Type less than coin thickness 1/3rd) a scope in, mainly be the main material of coin to the influence of magnetic test coil apparent impedance; Along with detecting increasing of frequency, the influence of main material reduces gradually, and the material of coating and the influence of thickness are obvious gradually, and the technology of coating also shows certain feature; When frequency continued to increase, the decorative pattern height on coin surface had also shown influence in printing technology.No matter which kind of coin all has certain thickness, when frequency is low (this value to less than the skin depth of this Currency Type less than coin thickness 1/3rd), alternating magnetic field can penetrate coin, the apparent impedance variation of this moment has reflected thickness information, along with frequency reduces gradually, the influence of thickness is obvious gradually.
In a word, this embodiment adopts the multifrequency detection mode that is different from art methods, coin can be detected and variations such as magnetic permeability on a plurality of frequencies of its feature and average conductivity can be reflected, thereby determine the magnetoelectricity characteristic parameter of all kinds of coins under extensive frequency, to realize the false proof design and the detection of the machine-readable magnetoelectricity feature of coin, promptly can be coin anti-counterfeit and counterfeit distinguishing equipment and lay the foundation, also can be used for the machine-readable magnetoelectricity feature detection and the coin false distinguishing of coin circulation.
Claims (4)
1. Coin magnetoelectric characteristic parameters dynamic multi-frequency detector is characterized in that: mainly be made up of put in place testing circuit, microprocessor, variable ratio frequency changer signal generator, magnetic test coil, computing circuit of coin; Put in place the output termination microprocessor of testing circuit of described coin is transferred to microprocessor in order to signal that coin is put in place; The controlled end of the described variable ratio frequency changer signal generator of frequency control output termination of described microprocessor is in order to control the pumping signal that the variable ratio frequency changer signal generator successively sends at least two predetermined frequencies; The output of described variable ratio frequency changer signal generator connects the input of magnetic test coil, is loaded into magnetic test coil in order to the pumping signal with each predetermined frequency; The output of described magnetic test coil connects the signal input part of computing circuit, behind the corresponding apparent impedance variable signal input computing circuit that coin to be measured is caused at the counter field that produces on each predetermined frequency, carries out Signal Pretreatment by pre-defined algorithm; The output of described computing circuit connects the input end of microprocessor after analog to digital conversion, in order to the characteristic of Signal Pretreatment result as coin to be measured, compare with the corresponding demarcation characteristic of series standard coin, draws the detection result of determination.
2. Coin magnetoelectric characteristic parameters dynamic multi-frequency detector according to claim 1 is characterized in that: the diameter of described magnetic test coil is less than 1/2nd of coin diameter to be measured.
3. Coin magnetoelectric characteristic parameters dynamic multi-frequency detector according to claim 2 is characterized in that: described variable ratio frequency changer signal generator contains D/A and I/V change-over circuit; Lead up to after the described pumping signal output behind the LPF low-pass filter circuit, be input to microprocessor through the A/D change-over circuit, as reference signal; Another road, described pumping signal output back connects the input of magnetic test coil by power driving circuit, is loaded into magnetic test coil successively in order to the pumping signal that will be scheduled to frequency; The output of described magnetic test coil is by behind I/V change-over circuit, second low-pass filter circuit and the A/D change-over circuit, connect the signal input part of microprocessor, in order to the effect that magnetic test coil is subjected to the counter field that coin to be measured produces on preset frequency and the apparent impedance change modeling amount that causes is converted into data volume sends into microprocessor.
4. Coin magnetoelectric characteristic parameters dynamic multi-frequency detector according to claim 3 is characterized in that: described predetermined frequency is 98 KHz, 382 KHz, 816 KHz.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNU200820035971XU CN201242779Y (en) | 2008-05-22 | 2008-05-22 | Dynamic multi-frequency detector for coin magneto-electric characteristic parameter |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNU200820035971XU CN201242779Y (en) | 2008-05-22 | 2008-05-22 | Dynamic multi-frequency detector for coin magneto-electric characteristic parameter |
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| CN201242779Y true CN201242779Y (en) | 2009-05-20 |
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| CNU200820035971XU Expired - Lifetime CN201242779Y (en) | 2008-05-22 | 2008-05-22 | Dynamic multi-frequency detector for coin magneto-electric characteristic parameter |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101980306A (en) * | 2010-10-15 | 2011-02-23 | 南京中钞长城金融设备有限公司 | Method and tester for detecting magnetic characteristic of coin |
| CN104700490A (en) * | 2013-12-10 | 2015-06-10 | 北京华夏聚龙自动化股份公司 | Multi-model coin signal collecting device based on eddy current sensor |
| CN106296967A (en) * | 2016-08-04 | 2017-01-04 | 南京中钞长城金融设备有限公司 | A kind of based on monocoil double frequency detection Coin identifying apparatus and recognition methods |
-
2008
- 2008-05-22 CN CNU200820035971XU patent/CN201242779Y/en not_active Expired - Lifetime
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101980306A (en) * | 2010-10-15 | 2011-02-23 | 南京中钞长城金融设备有限公司 | Method and tester for detecting magnetic characteristic of coin |
| CN101980306B (en) * | 2010-10-15 | 2012-09-05 | 南京中钞长城金融设备有限公司 | Method and tester for detecting magnetic characteristic of coin |
| CN104700490A (en) * | 2013-12-10 | 2015-06-10 | 北京华夏聚龙自动化股份公司 | Multi-model coin signal collecting device based on eddy current sensor |
| CN106296967A (en) * | 2016-08-04 | 2017-01-04 | 南京中钞长城金融设备有限公司 | A kind of based on monocoil double frequency detection Coin identifying apparatus and recognition methods |
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| Date | Code | Title | Description |
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| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| AV01 | Patent right actively abandoned |
Granted publication date: 20090520 Effective date of abandoning: 20080522 |