JP4867391B2 - Paper sheet identification sensor - Google Patents

Description

  The present invention relates to a paper sheet identification sensor that detects and identifies residual magnetism of a magnetized paper sheet.

  Paper identification sensors shown in FIGS. 6 to 8 are known as identification sensors for identifying paper sheets such as banknotes printed using magnetic ink. 6 is a perspective view showing the configuration of a known paper sheet identification sensor, FIG. 7 is an explanatory diagram for explaining the positional relationship between the magnetized body and the magnetic detection element shown in FIG. 6, and FIG. It is a side view which shows the structure of the magnetic body shown in (2).

  As shown in FIG. 6, the paper sheet identification sensor 101 identifies the paper sheet B by detecting the residual magnetism of the inserted paper sheet B, and includes a magnetized body 102, a magnetic detection element, and the like. 103, a holder 105 that houses the magnetized body 102 and the magnetic detection element 103.

  The magnetized body 102 is arranged on the upstream side of the transport path for transporting the inserted paper sheet B, and can magnetize the paper sheet B while the paper sheet B is transported. The magnetized body 102 is attached in a manner perpendicular to the detection surface Sd that is the lower surface of the holder 105. The magnetized body 102 is composed of a permanent magnet 121 and a soft magnetic body 122. The permanent magnet 121 has a quadrangular prism shape, and is disposed so that a rectangular end surface on the detection surface Sd side is an S pole. The soft magnetic body 122 has a U-shape when viewed from the side and has a rectangular cross section. For example, the soft magnetic body 122 is made of a soft magnetic material such as permalloy or ferrite. The soft magnetic body 122 is combined with the permanent magnet 121 so as to straddle the magnetic pole side (N pole side) opposite to the detection surface of the permanent magnet 121. Therefore, the magnetized body 102 forms a substantially E shape with the permanent magnet 121 disposed in the center, and the two rectangular end faces on the detection surface Sd side of the soft magnetic body 122 form an N pole. Then, the magnetic flux flows from the end face (N pole) of the soft magnetic body 122 to the end face (S pole) of the permanent magnet 121. As a result, in the magnetized body 102, the magnetic flux concentrates in the direction connecting the end face of the permanent magnet 121 and the open end face of the soft magnetic body 122 (direction perpendicular to the transport direction Y). Therefore, as shown in FIG. 7, the magnetic field components H1 and H2 in the direction orthogonal to the transport direction Y are strengthened, and the magnetic field components flowing in the transport direction Y are suppressed.

  The open end face of the magnetic body 102 thus configured, that is, the end face of the permanent magnet 121 and the two end faces of the soft magnetic body 122 are exposed on the detection surface Sd and are transported on the transport path as shown in FIG. It can contact or approach the surface of the paper sheet B. Therefore, the side close to the permanent magnet 121 of the paper sheet printed with magnetic ink is magnetized to the N pole, and the side close to the soft magnetic body 122 is magnetized to the S pole.

  The magnetic detection element 103 can detect the magnetic field components H1 and H2 in the direction orthogonal to the transport direction among the magnetic fields formed by the residual magnetism remaining on the paper sheet B (see FIG. 7). The magnetic detection element 103 is attached in a manner perpendicular to the detection surface Sd. The magnetic detection element 103 is configured, for example, by connecting two magnetic impedance elements 131A and 131B electrically in series. The magnetic impedance elements 131A and 131B can detect the magnetic field by utilizing the fact that the impedance changes according to the external magnetic field when a high frequency current is applied. The magneto-impedance elements 131A and 131B are configured by forming a zigzag linear pattern made of a high magnetic permeability magnetic thin film such as alpha moss or permalloy on a nonmagnetic substrate made of glass, ceramic or the like.

  The magnetic detection element 103 has a bias magnet 132 above the magnetic impedance elements 131A and 131B. The bias magnet 132 is composed of a permanent magnet and applies a magnetic field (bias magnetic field Hb) to the magnetic impedance elements 131A and 131B.

  This magnetic detection element 103 can differentially detect an external magnetic field configured according to the amount of residual magnetism of the paper sheet B by the two magnetic impedance elements 131A and 131B. That is, since the residual magnetic fields H1 and H2 of the paper sheet B are superimposed on the bias magnetic field Hb, one of the magnetic impedance elements 131A and 131B is affected by the magnetic field of Hb−H1, and the other magnetic impedance element is the magnetic field of Hb + H2. to be influenced. Then, based on the impedance in the absence of an external magnetic field, the impedance of one magnetic impedance element 131A changes in proportion to -H1 (decreases in this example), and the impedance of the other magnetic impedance element 131B. Changes in proportion to + H2 (increases in this example). Therefore, one end (for example, one magnetic impedance element 131A side) of one magnetic impedance element 131A and the other magnetic impedance element 131B is grounded, and a predetermined voltage is applied to the other end (for example, the other magnetic impedance element 131B side). Then, the voltage at the midpoint of the series connection changes by a voltage proportional to the external magnetic field (H1 + H2) with respect to the voltage (referred to as a reference voltage) when no external magnetic field exists.

  Using this principle, the voltage applied to the series connection is a high-frequency voltage, and the voltage (referred to as the comparison voltage Vref) indicating the baseline in the waveform of the transverse wave output (referred to as Vs) of the voltage at the midpoint of the series connection is Since this corresponds to the reference voltage when it does not exist, the comparison voltage Vref is extracted from the detection output Vs via the peak hold circuit (or minimum hold circuit), and further, the comparison voltage Vref and the detection output via the DC differential amplifier circuit. A voltage proportional to the external magnetic field (H1 + H2), that is, a magnetic field constituted by the residual magnetism of the paper sheet can be detected by a method of extracting a voltage difference from Vs.

  In the magnetic detection element 103 described above, the disturbance magnetic field is accompanied by a change in the bias magnetic field Hb and affects one magnetic impedance element 131A and the other magnetic impedance element 131B, but one magnetic impedance element 131A and the other magnetic impedance are affected. The voltage proportional to the external magnetic field (H1 + H2) taken out from the midpoint of the series connection connecting the element 131B hardly changes, and the influence of a minute disturbance magnetic field is canceled out.

  The detection of the external magnetic field (H1 + H2) is a so-called differential detection in which the difference between the voltages at both ends of one magnetic impedance element 131A and the other magnetic impedance element 131B is obtained in principle. As such differential detection, in addition, the middle point of the series connection connecting the one magnetic impedance element 131A and the other magnetic impedance element 131B is grounded, and the magnetic impedance elements 131A, 131A, There is a type in which a high-frequency current equal to each of 131B is passed, and voltages generated in one magnetic impedance element 131A and the other magnetic impedance element 131B are detected, and then the detected voltages are DC-differential amplified.

  Further, when it is necessary to further suppress the magnetic field propagation from the magnetized body 102 to the magnetic detection element 103, for example, as shown in FIG. 6, a magnetic shield member 106 such as a screen-shaped permalloy or amorphous is magnetically detected with the magnetized body 102. It arrange | positions between the elements 103 (for example, refer patent document 1).

  In addition, as shown in FIG. 9, the paper sheet identification sensor may employ an electromagnet 123 instead of the permanent magnet 121 to constitute the magnetized body 102. Further, the bias magnet 132 may be replaced with a permanent magnet, and an electromagnet 133 may be employed. When the magnetized body 102 and the bias magnet 132 are configured using the electromagnets 123 and 133 instead of the permanent magnet 121, a separate paper sheet detection sensor is provided, and the electromagnet is only detected when the paper sheet B is detected. 123 and 133 are preferably operated (see, for example, Patent Document 2).

JP 2000-105847 A JP 2004-206316 A

  However, the above-described paper sheet identification sensor has a magnetic field such as a screen-shaped permalloy or amorphous as shown in FIG. A shield member 106 is disposed between the magnetized body 102 and the magnetic detection element 103. Since the magnetic shield member 106 cannot surround all directions of the magnetic detection element 103, the magnetic field of the magnetized body 102 cannot be completely shielded, and a leakage magnetic field is generated. This is not a problem when the magnitude of the leakage magnetic field is very small within the magnetic field detection range of the magnetic detection element 103 and compared with the magnetic field to be detected (magnetic field constituted by residual magnetism). However, a detection error occurs when the size is not negligible compared to the magnetic field to be detected, and detection itself is impossible when the magnetic field detection range is exceeded.

  Therefore, when increasing the magnetizing magnetic field of the magnetized body 102, for example, when it is desired to improve the spacing characteristics between the magnetism detecting element 103 and the paper sheet, the leakage magnetic field to the magnetism detecting element 103 becomes a restriction, and the desired magnetic field. It was not possible to have a magnetizing force.

  In addition, as described above, when the magnetized body 102 is configured by using an electromagnet instead of a permanent magnet, after the magnetism is applied to the paper sheet B, the residual magnetism of the paper sheet B is detected. By interrupting the power supply to the electromagnet 123, it is possible to eliminate the magnetic field spreading of the magnetized body 102 to the magnetic detection element 103. However, the electromagnet 123 needs to have a magnetizing ability of about 1 k Gauss, and the electromagnet 123 becomes large in order to stably detect the magnetic field constituted by the residual magnetism of the paper sheet B.

  In view of the above circumstances, an object of the present invention is to provide a small paper sheet identification sensor capable of suppressing the influence of a magnetic field of a magnetized body on a magnetic detection element and arbitrarily setting the magnetic field strength of the magnetized body. .

In order to achieve the above object, a paper sheet identification sensor according to claim 1 of the present invention is disposed upstream of a transport path for transporting paper sheets, and first magnetizes the paper sheets. A magnetizing unit; a magnetism detecting unit for detecting residual magnetism of the paper sheet magnetized by the first magnetizing unit; and the magnetizing unit downstream of the conveyance path and with the magnetism detecting unit as a boundary. The magnetic detecting means is disposed at a position opposite to the conveying direction of the sheet and the paper sheet, and has a polarity opposite to the magnetism of the first magnetizing means in a manner to cancel the magnetism of the first magnetizing means in the magnetic detecting means. And second magnetizing means for magnetizing the paper sheet .

  Since the magnetic force of the second magnetizing means has a polarity opposite to that of the first magnetizing means, the magnetic force of the first magnetizing means and the magnetic force of the second magnetizing means cancel each other in the magnetic detecting means, and the first magnetizing means The influence of the magnetic force exerted on the magnetic detection means by the magnetic means and the second magnetizing means can be suppressed.

  In addition, since the first magnetizing means is provided on the upstream side and the second magnetizing means is provided on the downstream side, the first magnetizing means magnetizes the paper sheets when the paper sheets are inserted into the transport path. When magnetizing and returning the paper sheet from the transport path, the second magnetizing means magnetizes the paper sheet. For this reason, it is possible to detect the residual magnetism remaining on the paper sheet both when the paper sheet is inserted and when it is returned. As a result, the paper sheet can be identified both when the paper sheet is inserted and when it is returned.

  According to a second aspect of the present invention, there is provided a paper sheet identification sensor according to the first aspect, wherein the first magnetizing means and the second magnetizing means are at least equal to or greater than the coercive force of the paper sheet to be identified. It is characterized by comprising a permanent magnet having a magnetic field strength of.

  Since the first magnetizing means and the second magnetizing means are constituted by permanent magnets, the size can be reduced as compared with the case where the first magnetizing means and the second magnetizing means are constituted by electromagnets. For example, when paper sheets such as banknotes printed with magnetic ink are to be identified, the first magnetizing means and the second magnetizing means are composed of permanent magnets having a magnetic field strength of 1 k gauss or more.

  A paper sheet identification sensor according to a third aspect of the present invention is characterized in that, in the first or second aspect, the magnetic detection means is a thin film fluxgate magnetic detection element or a magnetic impedance element.

  The magneto-impedance element utilizes the fact that the impedance changes according to the external magnetic field when a high-frequency current is applied, and can detect the residual magnetism remaining on the paper sheet.

  A paper sheet identification sensor according to a fourth aspect of the present invention is the paper sheet identification sensor according to any one of the first to third aspects, wherein the first magnetizing means and the magnetic detecting means and the magnetic detecting means are A magnetic shield member is disposed between the second magnetizing means and the second magnetizing means.

  It is preferable that the first magnetizing means and the second magnetizing means have completely equal magnetic field strengths and opposite polarities. However, in reality, the first magnetizing means is considered in consideration of individual variations in the magnetic field generated by the magnet and mounting errors. The case where the magnetic force of a means and the magnetic force of a 2nd magnetization means cannot be canceled is assumed. In this case, as described above, since the magnetic shield member is disposed between the first magnetizing means and the magnetic detecting means and between the magnetic detecting means and the second magnetizing means, the influence of the leakage magnetic field is reduced. Can be suppressed.

  A paper sheet identification sensor according to a fifth aspect of the present invention is characterized in that, in any one of the first to third aspects, the magnetic detection means is surrounded by a magnetic shield member.

  Since the magnetic detection means is surrounded by the magnetic shield member, the influence of the leakage magnetic field can be suppressed even when the magnetic force of the first magnetizing means and the magnetic force of the second magnetizing means cannot be offset.

  According to a sixth aspect of the present invention, there is provided the paper sheet identification sensor according to the fourth or fifth aspect, wherein all of the first magnetization means, the magnetic detection means, the second magnetization means, and the shield member are provided. It is attached to the holder.

  Since the first magnetizing means, the magnetism detecting means, the second magnetizing means, and the magnetic shield member are all attached to the same holder, the handling of the paper sheet identification sensor can be improved.

  In the paper sheet identification sensor according to the present invention, since the magnetic force of the second magnetizing means has a polarity opposite to that of the first magnetizing means, the magnetic force of the first magnetizing means and the second magnetizing means in the magnetic detecting means. The first magnetic means and the second magnetic means can suppress the influence of the magnetic force on the magnetic detection means.

  In addition, since the first magnetizing means is provided on the upstream side and the second magnetizing means is provided on the downstream side, the first magnetizing means magnetizes the paper sheets when the paper sheets are inserted into the transport path. When magnetizing and returning the paper sheet from the transport path, the second magnetizing means magnetizes the paper sheet. For this reason, it is possible to detect the residual magnetism remaining on the paper sheet both when the paper sheet is inserted and when it is returned. As a result, the paper sheet can be identified both when the paper sheet is inserted and when it is returned.

  In the paper sheet identification sensor according to the present invention, the first magnetizing means and the second magnetizing means are constituted by permanent magnets, and therefore the first magnetizing means and the second magnetizing means are constituted by electromagnets. It can be smaller than the case.

  Further, if a magnetic shield member is provided between the first magnetizing means and the magnetic detecting means and between the magnetic detecting means and the second magnetizing means, the influence of the leakage magnetic field (noise magnetic field) can be further suppressed. Further, even if the magnetic detection means is surrounded by the magnetic shield member, the influence of the leakage magnetic field (noise magnetic field) can be further suppressed.

  In addition, since the first magnetizing means, the magnetic detecting means, the second magnetizing means, and the magnetic shield member are all attached to the same holder, the handling of the paper sheet identification sensor can be improved.

  Exemplary embodiments of a paper sheet identification sensor according to the present invention will be described below in detail with reference to the accompanying drawings. Note that the present invention is not limited to the embodiments.

(Embodiment)
In the present embodiment, a paper sheet identification sensor for identifying a paper sheet printed with magnetic ink as a paper sheet will be described as an example, and the paper sheet identification sensor according to the present invention will be described. 1 is a conceptual perspective view showing the configuration of the banknote identification sensor according to the embodiment of the present invention, FIG. 2 is a conceptual plan view illustrating the configuration of the banknote identification sensor shown in FIG. 1, and FIG. It is a conceptual diagram which shows the magnetization state of the banknote by the shown 1st magnetizing body. FIG. 4 is a conceptual diagram showing the magnetic field that the first magnetized body forms on the banknote, in which the horizontal component of the magnetic field is represented by contour lines, and FIG. 5 shows the first magnetized body and the second magnetized body. Is a conceptual diagram showing a magnetic field that constitutes a bill, in which the horizontal component of the magnetic field is represented by contour lines.

  As shown in FIG. 1, the banknote identification sensor 1 stores a first magnetized body 2, a magnetic detection element 3, and a second magnetized body 4 in one holder 5.

  The first magnetized body 2 is disposed on the upstream side (insertion side) of the transport path for transporting the inserted bill B, and can magnetize the bill B while the bill B is being transported. The first magnetized body 2 is attached in a manner perpendicular to the detection surface Sd that is the lower surface of the holder 5. The first magnetized body 2 includes a permanent magnet 21 and a soft magnetic body 22. The permanent magnet 21 has a quadrangular prism shape, and is disposed such that a rectangular end surface on the detection surface Sd side is an S pole. The permanent magnet 21 has a magnetic field strength equal to or greater than the holding power of the bill to be identified, that is, a magnetic field strength equal to or greater than 1 kGauss. The soft magnetic body 22 has a U-shape when viewed from the side, and has a rectangular cross section. The soft magnetic body 22 is made of, for example, a soft magnetic material such as permalloy or ferrite. The soft magnetic body 22 is combined with the permanent magnet 21 so as to straddle the magnetic pole side (N pole side) opposite to the detection surface of the permanent magnet 21. Accordingly, the first magnetized body 2 has a substantially E shape with the permanent magnet 21 disposed in the center, and the two rectangular end faces on the detection surface side of the soft magnetic body 22 form an N pole. Then, the magnetic flux flows from the end face (N pole) of the soft magnetic body 22 to the end face (S pole) of the permanent magnet. As a result, in the first magnetized body 2, the magnetic flux is concentrated in a direction (direction orthogonal to the transport directions Y <b> 1 and Y <b> 2) connecting the end face of the permanent magnet 21 and the open end face of the soft magnetic body 22. Therefore, the magnetic field component in the direction orthogonal to the transport direction Y1-Y2 is strengthened, and the magnetic field component in the transport direction Y1-Y2 is suppressed.

  The open end face of the first magnetized body 2 configured in this way, that is, the end face of the permanent magnet 21 and the two end faces of the soft magnetic body 22 are exposed on the detection surface Sd and are on the surface of the bill B being transported on the transport path. They can touch or approach. Therefore, as shown in FIG. 3, the side close to the permanent magnet 21 of the bill B printed with magnetic ink is magnetized to the N pole, and the side close to the soft magnetic body 22 is magnetized to the S pole. And the magnetic field is comprised as shown in FIG. 4 with the magnetism which remained in the part (henceforth "magnetization part") printed with the magnetic ink of the banknote B. As shown in FIG. That is, it passes through the center of the permanent magnet 21 and extends in opposite directions (from the conveyance direction axis) to both sides of the magnetized portion with a virtual axis (hereinafter referred to as “conveyance direction axis O”) extending in the conveyance direction Y1-Y2. A magnetic field in which magnetic flux flows in the direction of separation is formed.

The magnetic detection element 3 has a transfer direction Y1 among the magnetic fields formed by the residual magnetism remaining on the bill B.
The magnetic field components H11 and H12 in the direction orthogonal to −Y2 can be detected (see FIG. 2). As shown in FIG. 1, the magnetic detection element 3 is attached in a manner perpendicular to the detection surface Sd. The magnetic detection element 3 is configured by, for example, two magnetic impedance elements 31A and 31B being electrically connected in series. The magnetic impedance elements 31A and 31B can detect the magnetic field by utilizing the fact that the impedance changes according to the external magnetic field when a high frequency current is applied. The magneto-impedance elements 31A and 31B are configured by forming a zigzag linear pattern made of a high permeability magnetic thin film such as alpha moss or permalloy on a nonmagnetic substrate made of glass, ceramic or the like.

  The magnetic detection element 103 has a bias magnet (not shown) above the magnetic impedance elements 31A and 31B. The bias magnet is composed of a permanent magnet and applies a magnetic field (bias magnetic field Hb) to the magnetic impedance elements 31A and 31B.

  Therefore, the magnetic detection element 3 can differentially detect the external magnetic field configured according to the amount of residual magnetism of the bill B by the two magnetic impedance elements 31A and 31B. That is, since the residual magnetic fields H11 and H12 of the banknote are superimposed on the bias magnetic field Hb, one magnetic impedance element 31A is affected by the magnetic field Hb-H11, and the other magnetic impedance element 31B is affected by the magnetic field Hb + H12. Then, based on the impedance in the absence of an external magnetic field, the impedance of one magnetic impedance element 31A changes in proportion to -H11 (decreases in this example), and the impedance of the other magnetic impedance element 31B. Changes in proportion to + H12 (in this example, increases). Therefore, one end (for example, one magnetic impedance element 31A side) of one magnetic impedance element 31A and the other magnetic impedance element 31B is grounded, and a predetermined voltage is applied to the other end (for example, the other magnetic impedance element 31B side). When applied, the voltage at the midpoint of this series connection changes by a voltage proportional to the external magnetic field (H11 + H12) with respect to the voltage (referred to as the reference voltage) when no external magnetic field exists.

  Using this principle, the voltage applied to the series connection is a high-frequency voltage, and the voltage (referred to as the comparison voltage Vref) indicating the baseline in the waveform of the transverse wave output (referred to as Vs) of the voltage at the midpoint of the series connection is Since this corresponds to the reference voltage when it does not exist, the comparison voltage Vref is extracted from the detection output Vs via the peak hold circuit (or minimum hold circuit), and further, the comparison voltage Vref and the detection output via the DC differential amplifier circuit. A voltage proportional to the external magnetic field (H11 + H12), that is, a magnetic field constituted by the residual magnetism of the banknote B can be detected by a method of extracting a voltage difference from Vs.

  This detection of the external magnetic field (H1l + H12) is so-called differential detection in which a difference between both end voltages of one magnetic impedance element 31A and the other magnetic impedance element 31B is obtained in principle. As such differential detection, in addition, the midpoint of the series connection connecting the one magnetic impedance element 31A and the other magnetic impedance element 31B is grounded, and the magnetic impedance elements 31A, 31A, There is a type in which a high-frequency current that is equal to each of 31B is passed, voltages generated in one magnetic impedance element 31A and the other magnetic impedance element 31B are detected, and then the detected voltages are DC-differential amplified.

  In the magnetic detection element 3, the disturbance magnetic field is accompanied by a change in the bias magnetic field Hb and affects one magnetic impedance element 31A and the other magnetic impedance element 31B, but the one magnetic impedance element 31A and the other magnetic impedance element 31B are The voltage proportional to the external magnetic field (H11 + H12) taken out from the midpoint of the connected series connection hardly changes, and the influence of a minute disturbance magnetic field can be offset.

  However, the disturbance magnetic field that can be canceled by such differential amplification is only the disturbance magnetic field in the same direction and the same intensity as the magnetic detection element 3. Accordingly, the leakage magnetic field applied to the magnetic detection element 3 by the magnetic field of the first magnetized body 2 is in the opposite direction with respect to the conveyance direction axis, so that the disturbance magnetic field cannot be canceled out only by differential amplification. For this reason, as shown in FIG. 4, the magnetic field of the first magnetized body 2 affects the magnetic detection element 3.

  Therefore, as shown in FIG. 1, the second magnetized body 4 is disposed on the downstream side (return side) of the conveyance path. The second magnetized body 4 cancels the magnetism of the first magnetized body in the magnetism detecting element 3, and the second magnetized body 4 according to the present embodiment has the first magnetized body 2 centered on the magnetism detecting element 3. It is arrange | positioned in the position symmetrical with the arrangement | positioning position. The second magnetized body 4 has a polarity opposite to the magnetic force of the first magnetized body 2 and has the same magnetic field strength. This means that the magnetic detection element 3 is disposed at a position where the magnetic force of the first magnetic body 2 and the magnetic force of the second magnetic body 4 cancel each other.

  The second magnetized body 4 can magnetize the banknote while the banknote B is being conveyed, like the first magnetized body 2 described above. Similar to the first magnetized body 2 described above, the second magnetized body 4 is attached in a manner perpendicular to the detection surface Sd that is the lower surface of the holder 5. The second magnetized body 4 is composed of a permanent magnet 41 and a soft magnetic body 42, and the permanent magnet 41 has the same magnetic field strength as the permanent magnet 21 used in the first magnetized body 2 described above. is there. Therefore, the permanent magnet 41 has a magnetic field strength equal to or higher than the holding power of the bill to be identified, that is, a magnetic field strength equal to or higher than 1 k gauss. The permanent magnet 41 has the same shape (square column shape) as the permanent magnet 21 used in the first magnetized body 2 described above, and is disposed so that the rectangular end surface on the detection surface Sd side is an N pole. It is. Similar to the soft magnetic body 22 used in the first magnetized body 2 described above, the soft magnetic body 42 has a U-shape when viewed from the side and has a rectangular cross section. The soft magnetic body 42 is made of a soft magnetic material such as permalloy or ferrite, for example, in the same manner as the soft magnetic body 22 used in the first magnetized body 2 described above. The soft magnetic body 42 is combined with the permanent magnet 41 so as to straddle the magnetic pole side (S pole side) opposite to the detection surface Sd of the permanent magnet 41. Therefore, the second magnetized body 4 forms a substantially E shape with the permanent magnet 41 disposed in the center, and the two rectangular end faces on the detection surface Sd side of the soft magnetic body 42 form an S pole. Then, magnetic flux flows from the end face (N pole) of the permanent magnet 41 to the end face (S pole) of the soft magnetic body 42. As a result, in the second magnetized body 4, magnetic flux concentrates in the direction connecting the end face of the permanent magnet 41 and the open end face of the soft magnetic body 42 (direction perpendicular to the transport direction Y). Therefore, the magnetic field component in the direction orthogonal to the transport direction Y is strengthened, and the magnetic field component in the transport direction Y is suppressed.

  The open end face of the second magnetized body 4 configured in this way, that is, the end face of the permanent magnet 41 and the two end faces of the soft magnetic body 42 are exposed on the detection surface Sd and are on the surface of the bill B being transported on the transport path. They can touch or approach. Therefore, the side close to the permanent magnet 41 of the banknote printed by magnetic ink is magnetized to the S pole, and the side close to the soft magnetic body 42 is magnetized to the N pole. The magnetic field remaining in the magnetized portion forms a magnetic field as shown in FIG. That is, a magnetic field is formed in which magnetic flux flows through the center of the permanent magnet 41 in opposite directions (directions close to the conveyance direction axis) on both sides of the magnetized portion with the conveyance direction axis O as a boundary.

  Then, as shown in FIG. 5, the magnetic force of the first magnetized body 2 and the magnetic force of the second magnetized body 4 are offset, and the influence of the magnetic field of the first magnetized body 2 at the position where the magnetic detection element 3 is disposed, The influence of the magnetic field of the second magnetized body 4 is eliminated.

  Here, due to variations in the magnetic characteristics of the permanent magnet 21 of the first magnetized body 2 and the permanent magnet 41 of the second magnetized body 4, mounting errors, and the like, the first magnetized body 2 is disposed at the position where the magnetic detection element 3 is disposed. It is assumed that the influence of the magnetic field and the influence of the magnetic field of the second magnetized body 4 cannot be offset. For this reason, as shown in FIG. 1, a magnetic shield member 6 such as a screen-shaped permalloy or amorphous is placed between the first magnetized body 2 and the magnetic detecting element 3, and between the magnetic detecting element 3 and the second magnetized body 4. It is preferable to arrange between them.

  When the banknote B is inserted into the banknote identification sensor 1 described above, the banknote B is transported along the transport path in the arrow Y1 direction. Then, when the banknote B reaches the position facing the first magnetized body 2, the banknote B is magnetized by the first magnetized body 2. Accordingly, the magnetized portions of the bills B are sequentially magnetized, and the bills B are magnetized in a band shape as shown in FIG.

  As shown in FIG. 3, the magnetized portion of the bill B is magnetized in a direction perpendicular to the bill B, and the magnetic field constituted by the magnetized magnet is in the transport direction as shown in FIG. H11 direction component and H12 direction component that intersect at right angles to the direction.

  Therefore, when the banknote B reaches the position where it faces the magnetic detection element 3 thereafter, the magnetic detection element 3 differentially detects the magnetic field constituted by the residual magnetism remaining in the magnetized portion of the banknote B, and the banknote B can be identified. It becomes.

  On the other hand, when the banknote B is returned from the banknote identification sensor 1, the banknote B is conveyed along the conveyance path in the direction of arrow Y2. When the banknote B reaches the position facing the second magnetized body 4, the banknote B is magnetized by the second magnetized body 4. Accordingly, the magnetized portions of the bills B are sequentially magnetized, and the bills B are magnetized in a band shape in the same manner as when the bills B are inserted.

  As in the case where the bill B is inserted, the magnetized part of the bill B is magnetized in a direction perpendicular to the bill B, and the magnetic field constituted by the magnetized magnetism is in the transport direction. It has a component in the H22 direction and a component in the H22 direction that intersect at right angles.

  Therefore, when the banknote B reaches the position where it faces the magnetic detection element 3 thereafter, the magnetic detection element 3 differentially detects the magnetic field constituted by the residual magnetism remaining in the magnetized portion of the banknote B, and the banknote B can be identified. It becomes.

  In the banknote identification sensor 1 according to the above-described embodiment, the magnetic force of the second magnetized body 4 has the opposite polarity to the magnetic force of the first magnetized body 2. The magnetic forces of the two magnetized bodies 4 cancel each other, and the influence of the magnetic forces exerted on the magnetic detection element 3 by the first and second magnetized bodies 2 and 4 can be suppressed.

  Further, since the first magnetized body 2 is provided on the upstream side and the second magnetized body 4 is provided on the downstream side, the first magnetized body 2 magnetizes the bill B when the bill B is inserted into the transport path. When the banknote B is returned from the conveyance path, the second magnetized body 4 magnetizes the banknote B with magnetism. For this reason, the residual magnetism remaining on the bill B can be detected both when the bill B is inserted and when it is returned. As a result, the bill B can be identified both when the bill B is inserted and when it is returned.

  Moreover, since the magnet of the 1st magnetized body 2 and the magnet of the 2nd magnetized body 4 were comprised with the permanent magnets 21 and 41, the magnet of the 1st magnetized body 2 and the magnet of the 2nd magnetized body 4 are comprised with an electromagnet. It can be smaller than the case.

  Further, if the magnetic shield member 6 is disposed between the first magnetized body 2 and the magnetic detecting element 3 and between the magnetic detecting element 3 and the second magnetized body 4, the influence of the leakage magnetic field (noise magnetic field) is further increased. Can be suppressed.

  In addition, since the first magnetized body 2, the magnetic detection element 3, the second magnetized body 4, and the magnetic shield member 6 are all attached to the same holder 5, the handling of the banknote identification sensor 1 can be improved.

  In the above-described embodiment, the paper sheet identification sensor has been described by taking the banknote identification sensor 1 for identifying the banknote B as an example. However, the paper sheet is not limited to the banknote, and for example, a gift certificate, a bill Included are paper sheets that are printed with magnetic ink, such as checks.

  Further, as an example of the magnetic detection element 3, the one using the magnetic impedance elements 31A and 31B has been described, but a thin film fluxgate type magnetic detection element may be used instead of the magnetic impedance elements 31A and 31B.

  Further, the screen-shaped permalloy or amorphous magnetic shield member 6 is disposed between the first magnetized body 2 and the magnetic detecting element 3 and between the magnetic detecting element 3 and the second magnetized body 4. The magnetic shield member 6 may be formed in a cylindrical shape so as to surround the magnetic detection element 3.

  As described above, the paper sheet identification sensor according to the present invention is useful as a paper sheet identification sensor for detecting and identifying the residual magnetism of a magnetized paper sheet, for example, a banknote printed with magnetic ink It is suitable for a paper sheet identification sensor for identifying paper sheets such as.

It is a conceptual perspective view which shows the structure of the banknote identification sensor concerning embodiment of this invention. It is a conceptual top view explaining the structure of the banknote identification sensor shown in FIG. It is a conceptual diagram which shows the magnetization state of the banknote by the 1st magnetizing body shown in FIG. It is a conceptual top view which shows the magnetic field which the 1st magnetization body shown in FIG. 1 comprises on a banknote. It is a conceptual diagram which shows the magnetic field which the 1st magnetic body and 2nd magnetic body shown in FIG. 1 comprise on a banknote. It is a perspective view which shows the structure of a well-known paper sheet identification sensor. It is explanatory drawing for demonstrating the positional relationship of the magnetic body shown in FIG. 6, and a magnetic detection element. It is a side view which shows the structure of the magnetic body shown in FIG. It is a perspective view which shows the structure of a well-known paper sheet identification sensor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Banknote identification sensor 2 1st magnetized body 21 Permanent magnet 22 Soft magnetic body 3 Magnetic detection element 31A, 31B Magnetic impedance element 4 2nd magnetized body 41 Permanent magnet 42 Soft magnetic body 5 Holder 6 Magnetic shield member B Banknote

Claims (6)

A first magnetizing means disposed upstream of a transport path for transporting paper sheets and magnetizing the paper sheets;
Magnetic detection means for detecting residual magnetism of the paper sheets magnetized by the first magnetization means;
It is arranged downstream of the transport path and at a position opposite to the first magnetizing means and the transport direction of the paper sheet with the magnetic detecting means as a boundary, and the first magnetizing is performed in the magnetic detecting means. A paper sheet identification sensor comprising: a second magnetizing means for magnetizing a paper sheet with a magnetism having a polarity opposite to that of the first magnetizing means in a mode that cancels out the magnetism of the first magnetizing means. .   2. The paper sheet according to claim 1, wherein the first magnetizing means and the second magnetizing means are constituted by permanent magnets having a magnetic field strength at least equal to a coercive force of a paper sheet to be identified. Kind identification sensor.   The paper sheet identification sensor according to claim 1 or 2, wherein the magnetic detection means is a thin film fluxgate magnetic detection element or a magnetic impedance element.   4. A magnetic shield member is disposed between the first magnetizing means and the magnetic detecting means and between the magnetic detecting means and the second magnetizing means. The paper sheet identification sensor as described in one.   The paper sheet identification sensor according to any one of claims 1 to 3, wherein the magnetic detection means is surrounded by a magnetic shield member.   6. The paper sheet identification sensor according to claim 4, wherein all of the first magnetizing means, the magnetic detecting means, the second magnetizing means, and the shield member are attached to a holder.

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