JP4867480B2 - Magnetic detection device and discrimination device - Google Patents

Description

  The present invention relates to a magnetic detection device that detects a magnetic substance provided on a subject between a pair of magnetic detection units, and a discrimination device that discriminates the authenticity of the subject from the detection result.

  When identifying paper, such as banknotes, securities, and gift certificates printed with letters, symbols, and figures with ink containing magnetic material, as the subject, the letters and symbols printed with these magnetic inks A method of magnetically detecting a figure (hereinafter referred to as “magnetic printing portion”) by a magnetic detection unit and comparing the detection result with a pre-registered reference determination value to verify whether or not they match. Has been applied. Specifically, the magnetic detection part and the paper sheet as the subject are relatively moved, and the magnetic printing part is detected by the voltage change of the signal output from the magnetic detection part during this time.

  The magnetic detection unit uses a magnetoelectric conversion element that changes the voltage value of the output signal due to a change in the external magnetic field, such as a magnetoresistive element, a magnetic impedance element, and a thin film fluxgate type magnetic detection element. As described above, the voltage value ΔV generally changes greatly with respect to the minute change Δd in the distance from the subject. For this reason, when detecting the magnetic print portion of the subject, it is necessary to relatively move both of them while maintaining a constant distance between the subject and the magnetic detection unit. In other words, if the interval between the subject and the magnetic detection unit changes during detection, whether the voltage change in the signal output from the magnetic detection unit is due to the detection of the magnetic print portion, Since it becomes difficult to determine whether the interval has changed, it is necessary to keep the interval between the two constant.

  As a solution to such a problem, a method is provided in which the passage region of the subject is constrained and the subject is allowed to pass while being in contact with the detection surface of the magnetic detection unit. However, in the method of passing the subject in contact with the detection surface of the magnetic detection unit, there is not only a problem of wear on both the magnetic detection unit and the subject, but also there is a fold or wrinkle in the subject. In such a case, there is a possibility that the detection accuracy may be lowered or the subject may be clogged.

  As a method of preventing the problem of wear and clogging of the subject, a pair of magnetic detectors are arranged in a state of ensuring a distance from each other, and the subject is passed between the magnetic detectors and magnetic detection is performed. A pair of magnetic detectors are arranged so as to add and amplify the output signals from the units (see, for example, Patent Document 1) or in a manner in which the outputs are mutually inverted and the outputs are mutually inverted. There is provided a device that allows a subject to pass between them and differentially amplifies an output signal from a magnetic detection unit (for example, see Patent Document 2). That is, according to the device described in Patent Document 1, a region in which the voltage value of the output signal is constant is defined between the magnetic detection units. Further, according to the device described in Patent Document 2, the magnetic detection unit A region where the voltage value of the output signal is constant is defined between them, and the S / N ratio of the output signal is improved. Therefore, it is necessary to bring the subject into contact with the detection surface of the magnetic detection unit. This eliminates the problem of wear and clogging of the subject.

Japanese Utility Model Publication No. 62-41266 JP 2001-21631 A

  By the way, like the ones described in Patent Document 1 and Patent Document 2, the output signals from the pair of magnetic detection units are added and amplified, or the inverted output signals from the pair of magnetic detection units are differentially amplified. However, as shown in FIG. 9, the region R in which the voltage value of the output signal can be made constant between the magnetic detection units D is limited to only a part. Therefore, when the subject passes outside this region R, it may still be difficult to accurately detect the magnetic print portion.

  In view of the above circumstances, the present invention provides a magnetic detection device and a discrimination device that can accurately detect a magnetic body regardless of whether a subject passes between a pair of magnetic detection units. The purpose is to do.

In order to achieve the above object, a magnetic detection device according to claim 1 of the present invention is a magnetic detection device that detects a magnetic material provided on a subject between a pair of magnetic detection units, An addition processing means for adding the output signals from the magnetic detection section, an output ratio calculation means for calculating the output ratio of the two when the output signals are given from the pair of magnetic detection sections, and an output ratio calculation means An addition signal correction unit that estimates the distance from the magnetic detection unit to the subject according to the output ratio result, corrects the addition processing result of the addition processing unit according to the estimated distance, and outputs the corrected value as the detection result It is characterized by comprising.

In addition, the discrimination apparatus according to claim 2 of the present invention detects a magnetic body provided on the subject between the pair of magnetic detection units, and discriminates the authenticity of the subject based on the detection result. An addition processing means for adding the output signals from the individual magnetic detection sections, an output ratio calculation means for calculating the output ratio of the two when the output signals are given from the pair of magnetic detection sections, and an output The distance from the magnetic detection unit to the subject is estimated according to the output ratio result calculated by the ratio calculation means, the addition processing result of the addition processing means is corrected according to the estimated distance, and this corrected value is used as the detection result. An addition signal correction unit that outputs and a comparison unit that compares the correction signal output from the addition signal correction unit with a reference determination value registered in advance to check whether or not both match each other. To do.

  According to the present invention, after adding the output signals from the individual magnetic detection units, the addition processing result is further corrected in accordance with the output ratio result of the both. The influence of the change in the distance between the magnetic detection unit and the subject can be eliminated, and the magnetic substance can be accurately identified regardless of whether the subject passes between the pair of magnetic detection units. It becomes possible to detect.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of a magnetic detection device and a discrimination device according to the present invention will be described in detail with reference to the accompanying drawings as appropriate.

  FIG. 1 shows a discrimination apparatus according to an embodiment of the present invention. The discrimination apparatus exemplified here performs discrimination using paper M such as banknotes, securities, and gift certificates printed with characters, symbols, and figures using ink containing a magnetic material as an object. A pair of magnetic sensors 20a and 20b are provided in the transport path 10 for transporting M.

  The magnetic sensors 20a and 20b are configured to include magnetized magnets 21a and 21b and magnetic detectors 22a and 22b, respectively. The magnetic detectors 22a and 22b are opposed to each other, and the respective magnetized magnets 21a and 21b. Are arranged in a manner located in the upstream side of the magnetic detection units 22a and 22b in the transport path 10. In this Embodiment, it is comprised so that the mutual distance of the magnetic detection parts 22a and 22b in a pair of magnetic sensors 20a and 20b may be 1.0 mm.

  The magnetized magnets 21a and 21b are used to magnetize characters, symbols, and figures (hereinafter referred to as “magnetic printing portions”) printed with magnetic ink when the paper sheet M passes through the conveyance path 10. Is. As the magnetized magnets 21a and 21b, rare earth magnets having excellent magnetic properties such as samarium / cobalt magnets and neodymium magnets can be used. The magnetizing magnetic fields of the magnetized magnets 21a and 21b must have at least a magnetic field strength equal to or greater than the coercive force (50 to 500G) of the magnetic printing portion, and have a magnetic field strength equal to or greater than the saturation magnetic field (1000G) of the magnetic printing portion. It is preferable that

  The magnetic detectors 22a and 22b detect a residual magnetic field generated from a magnetic printing portion of the paper sheet M magnetized by the magnetized magnets 21a and 21b. The magnetoresistive element, the magnetic impedance element, and the thin film fluxgate type A magnetoelectric conversion element in which the voltage value of the output signal changes due to a change in the external magnetic field, such as a magnetic detection element, is applied. In the present embodiment, the magnetic detection units 22a and 22b of the magnetic sensors 20a and 20b are configured to have the same magnetic detection performance. In the following, for the sake of convenience, the magnetic sensor 20a positioned above and its components in FIG. 1 will be denoted by “first”, and the magnetic sensor 20b positioned below and its components will be denoted by “second”. To explain.

  Further, the discrimination device includes a signal processing means 30. The signal processing means 30 determines the authenticity of the paper sheet M on the basis of these output signals when output signals are given from the first magnetic sensor 20a and the second magnetic sensor 20b, as shown in FIG. In addition, a first amplifying unit 31, a second amplifying unit 32, a signal adding unit (addition processing unit) 33, a ratio calculating unit (output ratio calculating unit) 34, and an authenticity determining unit 35 are provided.

  The first amplifying unit 31 amplifies the output signal output from the first magnetic sensor 20a and outputs a first amplified signal, and the second amplifying unit 32 amplifies the output signal output from the second magnetic sensor 20b. Thus, the second amplified signal is output. The gain of the first amplifying unit 31 and the gain of the second amplifying unit 32 are the same.

  The signal adding unit 33 performs addition processing when the first amplification signal and the second amplification signal are given from the respective amplification units 31 and 32, and outputs the addition processing result as an addition signal.

  When the first amplified signal and the second amplified signal are given from the respective amplifying units 31 and 32, the ratio calculating unit 34 calculates the output ratio of both, and outputs this as a ratio calculation result. Specifically, when the first amplified signal ≧ the second amplified signal, the ratio calculation result is calculated by the first amplified signal / the second amplified signal, and when the first amplified signal <the second amplified signal, the second The ratio calculation result is calculated based on the amplified signal / first amplified signal.

  The authenticity determination unit 35 determines the authenticity of the paper sheet M based on the output results from the signal addition unit 33 and the ratio calculation unit 34, and includes an addition signal correction unit (addition signal correction unit) 36 and a comparison unit (comparison). Means) 37. When the addition signal is given from the signal addition unit 33 and the ratio calculation result is given from the ratio calculation unit 34, the addition signal correction unit 36 generates a correction value based on the ratio calculation result, and the generated correction value Thus, the addition signal is corrected. When the correction signal is given from the addition signal correction unit 36, the comparison unit 37 compares the reference determination value registered in the memory 38 in advance to check whether or not they match.

  In the discrimination apparatus configured as described above, when the paper sheet M is transported by a suitable transporting means such as a transporting roller or a transporting belt (not shown) in the transporting path 10, the magnetic printing portion thereof becomes the first magnetized magnet 21a. And the second magnetized magnet 21b, and thereafter reach between the first magnetic detection unit 22a and the second magnetic detection unit 22b. As a result, the residual magnetic field generated by the magnetic printing portion is detected by the first magnetic detection unit 22a and the second magnetic detection unit 22b, and the respective output signals are added via the first amplification unit 31 or the second amplification unit 32. To the unit 33 and the ratio calculation unit 34.

  The signal adder 33 to which the first amplified signal and the second amplified signal are given executes these addition processes and gives the added signal to the added signal correcting unit 36. On the other hand, the ratio calculation unit 34 to which the first amplification signal and the second amplification signal are given executes these ratio calculations and gives the ratio calculation result to the addition signal correction unit 36. As a result, a correction signal after correction based on the ratio calculation result is given from the ratio calculation unit 34 to the comparison unit 37, and this correction signal matches the reference determination value registered in the memory 38 in advance. It is verified whether or not. Thereby, if it matches with the reference determination value, it can be identified that the paper sheet M is true, while if it does not match the reference determination value, it can be determined that the paper sheet M is false.

  FIG. 3 shows the distance dA from the detection surface of the first magnetic detector 22a to the paper sheet M in the first magnetic sensor 20a and the output of the signal (amplified signal) output from the first magnetic sensor 20a. The relationship between the voltage and the output voltage relative value of the amplified signal when the maximum value is used as a reference is shown. In FIG. 3, the solid line relates to the first amplified signal obtained by amplifying the output signal from the first magnetic detector 22a, and the broken line relates to the second amplified signal obtained by amplifying the output signal from the second magnetic detector 22b. is there.

  FIG. 4 shows the addition of the distance dA from the detection surface of the first magnetic detector 22a to the paper sheet M in the first magnetic sensor 20a and the signals (amplified signals) output from the magnetic sensors 20a and 20b. It shows the relationship between the output voltage of the resultant addition signal and the relative value of the output voltage of the addition signal when the maximum value is used as a reference.

  As shown in FIG. 3, the first amplified signal output from the first amplifying unit 31 decreases in output voltage as the distance dA from the detection surface of the first magnetic detection unit 22a to the paper sheet M increases, and vice versa. The second amplified signal output from the second amplifying unit 32 from the detection surface of the second magnetic detection unit 22b decreases as the distance dA from the detection surface of the first magnetic detection unit 22a to the paper sheet M decreases. Since the distance dB to M (= 1.0−dA) increases, the output voltage decreases. Therefore, if the output signal from the first magnetic sensor 20a (or the second magnetic sensor 20b) is used alone, when the distance dA from the paper sheet M becomes 1.0 mm, the paper sheet M is detected on the detection surface. As a result, the output voltage is reduced by about 80% compared to the case where the contact is made.

  As described above, when the output voltage fluctuates greatly according to the distances dA and dB with the paper sheet M, the reference determination value registered in the comparison unit 37 also depends on changes in the distances dA and dB with the paper sheet M. The output fluctuation must be allowed, and as a result, the collation result is significantly lowered.

  On the other hand, as shown in FIG. 4, when the signals output from the magnetic detection units 22a and 22b are added, that is, the output voltage of the addition signal output from the signal addition unit 33 is the magnetic detection unit. The influence due to the change in the distances dA and dB from the detection surfaces 22a and 22b to the paper sheet M can be reduced. However, when the paper sheet M passes near the middle part between the first magnetic sensor 20a and the second magnetic sensor 20b (around dA = 0.5 mm), the paper sheet M is in contact with the detection surface. Compared to the case, the output voltage is reduced by about 30%.

  Here, FIG. 5 shows the relationship between the distance dA from the detection surface of the first magnetic detection unit 22a to the paper sheet M in the first magnetic sensor 20a and the ratio calculation result output from the ratio calculation unit 34. Is. As is apparent from FIG. 5, the distance dA from the detection surface of the first magnetic detection unit 22a to the paper sheet M and the ratio calculation result output from the ratio calculation unit 34 have a unique relationship. Therefore, if the ratio calculation result can be calculated, it is possible to estimate the distance dA from the detection surface of the first magnetic detection unit 22a to the sheet M, and if the addition signal is corrected based on the ratio calculation result, The influence of the change in the distance dA from the detection surface of the first magnetic detection unit 22a to the paper sheet M can be eliminated. That is, the correction value generated by the addition signal correction unit 36 described above is based on the results shown in FIGS. 4 and 5, and the output voltage of the addition signal × correction value = constant (dA = 0.0 to 1.0 mm, dB = 1.0 to 0.0 mm), which is a function of the ratio calculation result.

  FIG. 6 is a linear approximation of the relationship between the ratio calculation result and the correction value. In the present embodiment, the signal correction formula: correction value = −0.09 × ratio calculation result + 1.49 is acquired from FIG. 6, and this is set in the addition signal correction unit 36 in advance. As a result, the correction signal output from the addition signal correction unit 36 is the first magnetic regardless of the change in the distance dA from the detection surface of the first magnetic detection unit 22a to the paper sheet M, as shown in FIG. An output result is obtained in which the fluctuation of the output voltage is ± 3% over the entire range (= 1.0 mm) between the first magnetic detection unit 22a in the sensor 20a and the second magnetic detection unit 22b in the second magnetic sensor 20b. It becomes possible.

  Therefore, it is not necessary to consider the output fluctuation due to the change in the distance dA from the paper sheet M as the reference determination value registered in the memory 38 in the comparison unit 37, and as a result, the accuracy of the collation result can be improved. become able to. In addition, since there is no need to contact the paper sheet M with the detection surfaces of the magnetic detection units 22a and 22b of the magnetic sensors 20a and 20b, there is a problem of wear on the detection surface and the paper sheet M. There is no possibility of causing a situation where the paper sheet M is jammed in the conveyance path 10.

  In the above-described embodiment, an example is shown in which paper sheets M such as banknotes, securities, and gift certificates on which characters, symbols, and figures are printed with ink containing a magnetic material are used as an object for identification. However, it is not always necessary to use the paper sheet M as a subject, and the present invention can be applied to other types as long as it can detect a magnetic material provided in another subject.

  In the above-described embodiment, the distance between the pair of magnetic detectors 22a and 22b is 1 mm. However, the distance between the magnetic detectors 22a and 22b is not necessarily 1 mm. May be more or less than this. In this case, the signal correction formula does not necessarily match that of the above-described embodiment, but can be easily obtained by the same method.

  Further, in the above-described embodiment, the discrimination device including the comparison unit is exemplified. However, the comparison unit is not necessarily provided, and the magnetic detection device configured to directly output the correction signal from the addition signal correction unit. You may comprise as.

It is a conceptual diagram which shows the structure of the discrimination apparatus which is Embodiment 1 of this invention. It is a block diagram which shows the structure of the discrimination apparatus shown in FIG. It is the graph which showed the relationship between the distance from a 1st magnetic detection part to paper sheets, the output voltage from a magnetic detection part, and the output voltage relative value on the basis of the maximum value. It is the graph which showed the relationship between the distance from a 1st magnetic detection part to paper sheets, the output voltage from a magnetic detection part, and the output voltage relative value on the basis of the maximum value. It is the graph which showed the relationship between the distance from the detection surface of a 1st magnetism detection part to paper sheets, and the ratio calculation result output from a ratio calculation part. It is the graph which carried out the linear approximation of the relationship between a ratio calculation result and a correction value. 3 is a graph showing a relationship between a distance from a first magnetic detection unit to a paper sheet and an output voltage of a correction signal output from an addition signal correction unit illustrated in FIG. 2. It is a graph which shows the relationship between the distance to a subject and output voltage in a general magnetic detection part. It is a graph which shows the relationship between the distance to a subject and output voltage at the time of adding and amplifying the output signal from a pair of magnetic detection part in the conventional discrimination apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Carriage path 20a, 20b Magnetic sensor 21a, 21b Magnetized magnet 22a, 22b Magnetic detection part 30 Signal processing means 31 1st amplification part 32 2nd amplification part 33 Signal addition part 34 Ratio calculation part 35 Trueness determination part 36 Addition signal correction | amendment 36 Part 37 Comparison part 38 Memory M Paper sheets

Claims (2)

A magnetic detection device that detects a magnetic material provided on a subject between a pair of magnetic detection units,
Addition processing means for adding output signals from the individual magnetic detection units;
An output ratio calculating means for calculating an output ratio of both when an output signal is given from a pair of magnetic detection units;
The distance from the magnetic detection unit to the subject is estimated according to the output ratio result calculated by the output ratio calculation means, the addition processing result of the addition processing means is corrected according to the estimated distance, and the corrected value is detected. A magnetic detection device comprising: an addition signal correction means for outputting as a signal. A detection device that detects a magnetic body provided in a subject between a pair of magnetic detection units, and discriminates the authenticity of the subject based on the detection result,
Addition processing means for adding output signals from the individual magnetic detection units;
An output ratio calculating means for calculating an output ratio of both when an output signal is given from a pair of magnetic detection units;
The distance from the magnetic detection unit to the subject is estimated according to the output ratio result calculated by the output ratio calculation means, the addition processing result of the addition processing means is corrected according to the estimated distance, and the corrected value is detected. Addition signal correction means for outputting as
A comparison apparatus comprising: a comparison unit that compares a correction signal output from the addition signal correction unit with a reference determination value registered in advance to check whether or not both match.

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