JP2005234626A - Sensor and device for paper sheet discrimination - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sensor and a device for paper sheet discrimination for improving the discrimination capability of the sensor by detecting shading itself of magnetic-ink on paper sheet and also preventing a highly forged paper sheet from being erroneously recognized. <P>SOLUTION: A sensor for paper sheet discrimination 1 is composed of a core body 10 formed of magnetic material and winding coils 11, 12 wound around the core body 10. A magnetism sensitive part (a part where the coil 11 is wound around) of the core body 10 is disposed toward a conveying path of a medium (paper sheet) 2. An edge section of a whole of or a part of an end face of the core body 10 at the magnetism sensitive part is chamfered. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a paper sheet identification sensor and a paper sheet identification device for detecting magnetic substances printed on the surface of paper sheets such as checks and banknotes, and in particular, to improve the identification accuracy. It is possible to do that.

  Conventionally, a magnetic sensor detects the presence or absence of magnetic ink (printing ink containing a magnetic substance) embedded in paper sheets such as banknotes and checks, thereby identifying the authenticity and type of the paper sheets. There is a paper type identification sensor of the type.

  FIG. 7 is a diagram showing a state in which paper sheets are identified by a sensor having as constituent elements a magnet that forms a bias magnetic field and an MR element that performs magnetic detection. In FIG. 7A, when a paper sheet in which three magnetic inks are embedded is conveyed in the left direction of FIG. 7A, leakage magnetic flux from these magnetic inks is detected by a sensor, and FIG. ) Is obtained. According to FIG. 7B, it can be seen that this output waveform greatly changes in an impulse shape when the magnetic pole position (N pole or S pole of the magnetic ink) having the highest magnetic flux density passes just below the sensor. . Therefore, in the sensor shown in FIG. 7A, the authenticity of the paper sheet can be identified by measuring the magnitude and timing of this change (edge detection).

  Also, as disclosed in, for example, Patent Document 1 and Patent Document 2, two magnetosensitive parts are provided by MR elements or MI elements, and a differential output is obtained from these magnetosensitive parts, thereby enabling the paper sheet There is one that can increase the sensitivity of class identification (Patent Document 1) and can simultaneously detect a conductor and a magnetic material (Patent Document 2). In the winding type sensors disclosed in these documents, an ideal detection output cannot be obtained even if the magnetic ink of the detection target (paper sheet) is detected by the two magnetic sensing portions. Similar to the sensor shown in Fig. 5, the authenticity of the paper sheet is identified by performing edge detection for measuring the magnitude and timing of the extreme value of the output waveform.

Japanese Patent Laid-Open No. 2002-350405 JP 2000-268224 A

  However, since the conventional sensor that performs edge detection as described above cannot detect the density of the magnetic ink, there is a possibility that a highly accurate counterfeit paper sheet may be erroneously recognized as a genuine paper sheet.

  That is, in the conventional sensor, since the edge detection for measuring the magnitude and timing of the extreme value of the output waveform is performed, only the outline of the magnetic ink on the paper sheet can be detected. For example, if the edge of the forged paper sheet B is identified by edge detection, the outline of the magnetic paper sheet A is the same as that of the magnetic paper sheet A, but the inside of the printed paper sheet B is not filled (non-magnetized), etc. An identification result similar to that of the true paper sheet A is obtained. Therefore, if only the outline of the magnetic ink of the paper sheet can be detected, there is a possibility that a highly accurate counterfeit paper sheet (for example, the counterfeit paper sheet B) may be erroneously recognized as a genuine paper sheet.

  In addition, since the conventional sensor performs edge detection, in the situation where the magnetic sensitive part is completely applied to the magnetic ink (the situation where the magnetic ink edge and the magnetic sensitive part are not opposed), the detection output There is a problem that does not come out. That is, there is a problem that the detection output is not obtained despite the presence of magnetic ink.

  In addition, considering that counterfeit banknotes are becoming a social problem in response to the recent economic recession, there is a possibility that counterfeit banknotes will become more accurate in the future, and further improvement in sensor identification capability is required. ing.

  The present invention has been made in view of the above points, and an object of the present invention is to improve the discrimination ability of the paper sheet identification sensor by detecting the density of the magnetic ink of the paper sheet itself, and thus to improve the advanced level. An object of the present invention is to provide a paper sheet identification sensor and a paper sheet identification device capable of preventing erroneous recognition of a forged paper sheet.

  In order to solve the above-described problems, the present invention provides a paper sheet identification sensor that includes a core body and a winding coil, and is arranged with a magnetic sensing portion of the core body facing a paper sheet conveyance path. The chamfering process is performed on all or a part of the edge of the core body end face in the magnetic sensitive part.

  More specifically, the present invention provides the following.

  (1) A core body formed of a magnetic material and having a magnetic sensing part for detecting magnetic flux, and a winding coil wound around the core body, and the magnetic sensing part is used as a conveyance path for paper sheets In the paper sheet identification sensor disposed toward the paper sheet, the concentration of the magnetic flux formed by the winding coil is reduced at least at the edge portion of the core body end surface of the magnetic sensing section in the paper sheet conveyance direction. A paper sheet identification sensor which is chamfered.

  According to the present invention, a core body that is formed of a magnetic material such as iron, ferrite, and permalloy and has a magnetic sensing portion that detects a leakage magnetic flux from a magnetic substance of a paper sheet, and a winding wound around the core body. In a paper sheet identification sensor comprising a wire coil and having a magnetic sensing part of a core body facing a paper sheet conveyance path, at least a paper sheet conveyance direction on an end surface of the core body in the magnetic sensing part Since the chamfering process for relaxing the concentration of the magnetic flux formed by the winding coil is applied to the edge portion of the magnetic core, it is possible to prevent the magnetic flux concentration (density increase) on the end face of the core body in the magnetic sensitive portion. .

  That is, when magnetic detection of magnetic ink is performed by a magnetic sensing part before chamfering (magnetic flux concentration at the edge part cannot be avoided), magnetic flux concentration is concentrated at the edge part. There will be a difference between the output at the flat part at the center of the core bottom of the core and the output at the edge of the end face of the core in the magnetosensitive part. When magnetic detection of magnetic ink is performed with a relaxed magnetic sensing part, there is almost no difference between the output at the flat part at the center of the core bottom of the magnetic sensitive part and the output at the edge of the core body end face at the magnetic sensitive part. Will not occur. Therefore, according to the present invention, since it is possible to detect the magnetic field without being affected by the magnetic flux concentration on the end surface of the core body in the magnetic sensitive part of the core body, not only the outline of the magnetic ink on the paper sheet but also the density can be more accurately detected. Therefore, the identification ability of the paper sheet identification sensor can be improved.

  Here, as the “paper sheet identification sensor”, a separately excited type sensor in which a coil excited by an AC signal supplied from a power supply circuit and a coil detected as an electromagnetic signal are formed by separate coils, impedance, A self-excited sensor, in which a coil that is excited by an AC signal supplied from a power supply circuit and a coil that is detected as an electromagnetic signal are configured by the same coil, is considered. The invention is not intended to be limited to any one of other examples and self-excited types.

  “Chamfering” refers to processing so that a predetermined shape is formed at a corner where one surface and another surface intersect, for example, processing that forms a slope shape (C chamfering processing). ) And a rounded shape (R chamfering).

  (2) A paper sheet identification apparatus comprising: the paper sheet identification sensor according to (1); and a sensor signal processing circuit that processes output data from the paper sheet sensor by pattern matching.

  According to the present invention, the paper sheet identification device includes the above-described paper sheet identification sensor and a sensor signal processing circuit capable of performing image processing by pattern matching on output data from the paper sheet identification sensor. Therefore, it is possible to more accurately identify not only the outline of the magnetic ink of the paper sheet but also its density, and thus the identification ability of the paper sheet identifying apparatus can be improved.

  As described above, the paper sheet identification sensor and the paper sheet identification device according to the present invention include C chamfering and R chamfering on all or part of the edge of the core body end face in the magnetic sensitive section of the core body. Since chamfering such as processing is performed, it is possible to detect the density of the magnetic ink of the paper sheet itself, thereby preventing misrecognition of advanced counterfeit paper sheets and improving the identification ability. it can.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

[Schematic structure]
FIG. 1 is a diagram showing a schematic structure of a paper sheet identification apparatus 100 according to an embodiment of the present invention.

  In FIG. 1, a paper sheet identification apparatus 100 according to an embodiment of the present invention includes a paper sheet identification sensor 1 and a signal line 13a for energizing a winding coil wound around the paper sheet identification sensor 1. , 13b, bobbins 14a, 14b for fixing the paper sheet identification sensor 1 and the signal lines 13a, 13b, a case 15, and an epoxy resin 16 filled in the case 15. An excitation current is supplied to the winding coil wound around the paper sheet identification sensor 1 via signal lines 13a and 13b, and a medium 2 in which magnetic ink is embedded immediately below the paper sheet identification sensor 1 is provided. Is passed, the output signal can be taken out by utilizing the inductance change of the winding coil. Details thereof will be described with reference to FIG.

  FIG. 2 is an enlarged view showing a schematic structure of the paper sheet identification sensor 1 according to the embodiment of the present invention.

  In FIG. 2, a paper sheet identification sensor 1 according to an embodiment of the present invention includes a core body 10, a plurality of winding coils 11 wound around a part of the core body and arranged adjacent to each other, The winding coil 11 includes a plurality of winding coils 12 which are paired with the winding coil 11 and are provided at positions opposite (on the upper side of the core body 10) with the core body 10 interposed therebetween.

  The core body 10 is formed by cutting a magnetic material, and has an integrated structure in which a plurality of magnetic poles are integrated. The plurality of magnetic poles are arranged in a row in a direction substantially orthogonal to the conveyance direction of the medium 2. In FIG. 2, the direction of the magnetic flux is opposite between the winding coils adjacent in the horizontal direction. However, the present invention is not limited to this. For example, the magnetic flux is generated between the winding coils adjacent in the horizontal direction. The directions may be the same. In the present embodiment, a structure in which a plurality of magnetic poles are integrated from the viewpoint of increasing the number of channels and improving the identification resolution is provided. However, the present invention is not particularly limited to this, and includes a single magnetic pole. It may have a structure.

  The winding coil 11 has a function as a magnetic sensing unit that senses magnetic ink printed on the medium 2. Here, the winding coil 11 and the winding coil 12 are supplied with an exciting current through the signal lines 13a and 13b so that the balance of both inductances is maintained. Then, when the medium 2 in which magnetic ink is embedded passes directly under the paper sheet identification sensor 1, the inductance balance of the winding coil 11 and the winding coil 12 is lost due to the inductance change of the winding coil 11, and as a result. An output signal can be obtained.

[Chamfering]
Next, in FIG. 2, chamfering is performed on the end surface (edge portion A surrounded by a dotted line) of the core body 10 in the magnetic sensing portion (the portion around which the winding coil 11 is wound) of the paper sheet identification sensor 1. Processing will be described. FIG. 3 is a diagram showing a state in which a chamfering process is performed on the end surface of the core body 10 in the magnetic sensing portion (portion where the winding coil 11 is wound) of the paper sheet identification sensor 1 according to the embodiment of the present invention. It is. In addition, the conveyance direction of the medium 2 is the left-right direction in Fig.3 (a)-FIG.3 (d). In FIG. 3, the edge portion A in the sheet conveyance direction is chamfered. However, the present invention is not limited to this, and the edge in a direction perpendicular to the sheet conveyance direction is used. Part B (see FIG. 2) may be chamfered.

  When chamfering is applied to both edge portions of the edge portion A and the edge portion B, mutual interference between adjacent magnetic poles of the core body 10 can be reduced. Moreover, you may give the same chamfering process to the end surface of the core body 10 by the side of the winding coil 12. FIG. Thus, when the shape of the both end surfaces of the core body 10 is equalized, the magnetic balance of the winding coil 11 side and the winding coil 12 side can be taken, and a temperature characteristic can be improved.

  In FIG. 3A, the edge portion A (conventional structure) before the chamfering process has an angle of 90 °. At this time, the magnetic flux formed by the exciting current supplied to the winding coil 11 is concentrated in the vicinity of the edge portion A, and the amount of magnetic flux in the edge portion A is larger than that in the vicinity of the bottom center of the core body 10. Therefore, the output is different when the portion of the medium 2 in which the magnetic ink is embedded passes just below the edge portion A and when the portion passes near the center of the bottom surface of the core body 10.

  On the other hand, as shown in FIG. 3B, by applying C chamfering to the end face of the core body 10 (by forming the edge portion A ′), the exciting current supplied to the winding coil 11 The concentration of the formed magnetic flux on the edge portion A ′ can be reduced. Thereby, the output can be made the same when the portion of the medium 2 in which the magnetic ink is embedded passes just below the edge portion A ′ and when the portion passes near the center of the bottom surface of the core body 10. As a result, magnetic detection that is not affected by the magnetic flux concentration on the end face of the core body 10 becomes possible.

  In addition, as shown in FIG.3 (c), by performing R chamfering process (for example, R = 0.2mm) to the end surface of the core body 10 (by forming edge part A ''), the winding coil It is possible to alleviate the concentration of the magnetic flux formed by the exciting current supplied to 11 on the edge portion A ″, and, as shown in FIG. Chamfering is performed (edge portion A ′ is formed), and the other end surface of the core body 10 is subjected to R chamfering processing (by forming edge portion A ″) to be supplied to the winding coil 11. The concentration of the magnetic flux formed by the excitation current applied to the edge portion A ′ (A ″) can be reduced.

  Thus, in consideration of the property that the leakage magnetic flux is most increased in the sharp part of the magnetic body, by performing chamfering on the sharp part, magnetic detection that is not affected by the magnetic flux concentration on the end face of the core body 10 becomes possible. Become.

[Processing operation]
FIG. 4 is an electric circuit diagram for explaining the processing operation of the paper sheet identification sensor 1 according to the embodiment of the present invention.

In FIG. 4, the drive circuit 41 of the paper sheet identification sensor 1 is a self-excited differential magnetic head S composed of two winding coils 11 and 12 (see FIG. 2) provided at opposite positions across the core body. composed of ₁ ~S _4. Further, a power supply circuit 43 (AC power supply) is connected to the drive side of the drive circuit 41, and a sensor signal processing circuit 42 including four identification circuits is connected to the detection side of the drive circuit 41.

The four self-excited differential magnetic heads S _{1 to} S ₄ are arranged adjacent to each other in a direction substantially orthogonal to the paper sheet transport direction. However, “adjacent” here includes not only that the _four self-excited differential magnetic heads S _{1 to} S ₄ are in contact with each other, but also that they are arranged at regular intervals. To do. Although the drive circuit 41 in the case where the number of self-excited differential magnetic heads is four is shown here, the present invention is not limited to four self-excited differential magnetic heads. It may be 12 pieces or 24 pieces used for.

The power supply circuit 43 provided on the drive side of the drive circuit 41 is connected to the ground via two winding coils 11 and 12 in each of the self-excited differential magnetic heads S _{1 to} S ₄ . The connection point between the two winding coils is connected to a sensor signal processing circuit 42 provided on the detection side of the drive circuit 41.

  Here, the sensor signal processing circuit 42 is configured by a half-wave rectification or full-wave rectification circuit, a low-pass filter, an operational amplifier, and the like, and amplifies the output signal from the self-excited differential magnetic head or outputs the output signal. Various signal processing related to paper sheet identification is performed based on this.

  The sensor signal processing circuit 42 has a function of processing output data from the paper sheet identification sensor 1 by pattern matching. More specifically, this sensor signal processing circuit has semiconductor elements such as a CPU, a ROM, and a RAM, and the CPU temporarily stores output data from the paper sheet identification sensor 1 in the RAM, The pattern matching process is executed by comparing the output data with the reference pattern data stored in the ROM as a whole or a partial comparison. As a result, not only the outline of the magnetic ink of the paper sheet but also its density can be identified as parameters, and the paper sheet identifying ability can be improved.

  Note that when the processing target of the pattern matching processing is the authenticity identification of the paper sheet, a large amount of image data needs to be processed in a short time (real time), so that the CPU of the sensor signal processing circuit 42 has a high speed. It is desirable to make it easier. For example, it may be speeded up by pipeline control that simultaneously fetches and executes instructions, and is highly effective in speeding up regular parallel processing, and is suitable for operations on array sets. Stream) may be used to increase the speed.

  FIG. 5 is an explanatory diagram of an embodiment of the present invention. More specifically, by performing R chamfering processing (R = about 0.2 mm) on all edge portions of the end surface of the core body in the magnetic sensitive portion, the density of the magnetic ink of the measurement medium can be detected more accurately. This is the experimental result.

  FIG. 5A shows an R surface on the edge B of the core body end surface in the direction perpendicular to the conveyance direction of the measurement medium 52 (front to back in the drawing) in the sensor 51 having three magnetic heads (ch1 to ch3). In addition to applying a cutting process (R = about 0.2 mm) (left of FIG. 5A), an R chamfering process is performed on the edge A of the end surface of the core body in the conveyance direction of the measurement medium 52 (left to right of the drawing). R = approx. 0.2 mm) is shown (right of FIG. 5 (a)). To such a sensor 51, a measurement medium 52 such as copy paper having a printing unit 53 is conveyed so that the arrangement direction of the three magnetic heads and the printing unit 53 are orthogonal to each other (FIG. 5B). Note that the air gap between the sensor 51 and the conveyance path is zero. That is, the measurement medium 52 is conveyed while being in sliding contact with the sensor 51.

  In FIG. 5B, when the printing unit 53 of the measurement medium 52 passes below the sensor 51 not subjected to the R chamfering process shown in FIG. 5A, it corresponds to three magnetic heads (ch1 to ch3). The combined output waveform shown in FIG. 5C is obtained from the identification circuit. On the other hand, in FIG. 5B, when the printing unit 53 of the measurement medium 52 passes below the sensor 51 subjected to the R chamfering process shown in FIG. 5A, three magnetic heads (ch1 to ch3). The combined output waveform shown in the lower part of FIG. In FIG. 5C, the horizontal axis indicates displacement [mm], and the vertical axis indicates output [V].

According to FIG. 5C, in the combined output waveform (the waveform without chamfering) shown in FIG. 5C, the printing unit 53 of the measurement medium 52 has an angle (at the end face of the core body in the conveyance direction of the measurement medium 52). at a timing of passing beneath the two), pointed pointed output T _g is two remarkably appear. This is due to the fact that the magnetic flux is concentrated on the corner of the end face of the core body. On the other hand, in the combined output waveform (the waveform with chamfering) shown in the lower part of FIG. 5C, the printing unit 53 of the measurement medium 52 has two edge portions A (see FIG. 5) on the end surface of the core body in the conveyance direction of the measurement medium 52. 5 even at a timing of passing beneath the (a) right), pointed kurtosis output T _g of the above does not appear. That is, the output when the printing unit 53 of the measurement medium 52 passes directly below the two edge portions A (the output D of the combined output waveform shown in FIG. 5C) and the printing unit of the measurement medium 52 It can be seen that the output is substantially the same as the output when 53 passes near the center of the bottom surface of the core body (output C in the combined output waveform shown in FIG. 5C). Thus, the core member end face, if Hodokose chamfering like the edge portion A (FIGS. 5 (a) right), suppress the kurtosis output The T _g due to the magnetic flux on the corner of the core body end faces are concentrated As a result, the density (ideal output waveform) of the magnetic ink 53 of the measurement medium 52 can be detected more accurately.

[Modification]
FIG. 6 is an explanatory view of another embodiment of the present invention. More specifically, when the measurement medium 52 having the four printing parts 53 is conveyed so that the arrangement direction of the plurality of magnetic heads and the printing parts 53 are orthogonal to each other (FIG. 6A), the core body When the end face is not chamfered, the combined output waveform shown in FIG. 6B is obtained from the identification circuit corresponding to the plurality of magnetic heads, and when the core body end face is chamfered, It is an experimental result that the composite output waveform shown in FIG. 6C is obtained from the identification circuit corresponding to a plurality of magnetic heads.

According to FIG. 6B, when the chamfering process is not performed on the end surface of the core body, each of the four printing parts 53 of the measurement medium 52 is subjected to corners of the end surface of the core body in the conveyance direction of the measurement medium 52 ( at a timing of passing beneath the two), kurtosis output the T _g above is 8 (2 × 4) pieces are remarkably appeared. On the other hand, according to FIG. 6 (c), when the core body end face is chamfered, each of the four printing parts 53 of the measurement medium 52 causes the core body end face in the transport direction of the measurement medium 52. even timing passing beneath the corner (2), kurtosis output the T _g above does not appear.

Thus, even if the printing section 53 of the measuring medium 52 is a plurality, it is possible to suppress all kurtosis output T _g, and thus the magnetic ink 53 in the measuring medium 52 shades the (ideal output waveform) More accurate detection is possible.

  The paper sheet identification sensor and the paper sheet identification device according to the present invention perform chamfering on all or a part of the edge part of the core body end face in the magnetic sensitive part of the core body, so that the density of the magnetic ink itself can be obtained. As a result, it is useful as a device capable of preventing erroneous recognition of advanced counterfeit paper sheets.

It is a figure which shows schematic structure of the paper sheet identification device which concerns on embodiment of this invention. It is an enlarged view which shows schematic structure of the paper sheet identification sensor which concerns on embodiment of this invention. It is a figure which shows a mode that chamfering is performed to the end surface of the core body in the magnetic sensing part of the paper sheet identification sensor which concerns on embodiment of this invention. It is an electric circuit diagram for demonstrating the processing operation of the paper sheet identification sensor which concerns on embodiment of this invention. It is explanatory drawing about the Example of this invention. It is explanatory drawing about the other Example of this invention. It is explanatory drawing for demonstrating a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Paper sheet identification sensor 2 Medium 10 Core body 11, 12 Winding coil 13a, 13b Signal line 14a, 14b Bobbin 15 Case 16 Epoxy resin 100 Paper sheet identification device

Claims (2)

A core body made of a magnetic material and having a magnetic sensing part for detecting magnetic flux, and a winding coil wound around the core body, the magnetic sensing part being directed toward a paper sheet conveyance path In the arranged paper sheet identification sensor,
A chamfering process for reducing concentration of magnetic flux formed by the winding coil is performed on at least an edge portion of the end surface of the core body in the magnetic sensing portion in a conveyance direction of the paper sheet. Paper sheet identification sensor. A paper sheet identification apparatus comprising: the paper sheet identification sensor according to claim 1; and a sensor signal processing circuit that processes output data from the paper sheet identification sensor by pattern matching.