Paper sheet identification device, paper sheet handling device, and paper sheet identification method

Abstract

To prevent a paper sheet identification device from reducing the accuracy of paper sheet identification.SOLUTION: A paper sheet identification device for identifying a paper sheet includes: a magnetic noise source that generates a fluctuating magnetic field; a plurality of magnetic detection elements arranged perpendicularly to the surface of a paper sheet being conveyed on a conveyor path and detecting the magnetism of the paper sheet; a magnetic member having a magnetic permeability equal to or higher than a specified value and arranged between the plurality of magnetic detection elements and the magnetic noise source; and an arithmetic unit that differentially calculates a magnetic detection value of the paper sheet being conveyed on the conveyor path based on each detection signal detected by each magnetic detection element.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a paper sheet recognition device, a paper sheet handling device, and a paper sheet recognition method. [Background technology]

[0002] For example, banknote handling devices such as automated teller machines (ATMs) and automated cash sorters have banknote identification devices that determine the denomination of banknotes, their authenticity, and damage to banknotes such as stains, bends, and tears. Some banknote identification devices use magnetic sensors as one of the means for realizing the function of determining the denomination and authenticity of banknotes. For example, Patent Document 1 discloses a device that detects the magnetism of banknotes by taking the differential between two magnetic sensor elements and removing magnetic noise from external magnetic fields. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6209674 Summary of the Invention [Problem to be solved by the invention]

[0004] Magnetic noise that affects banknote validator devices includes magnetic noise from a uniform external magnetic field as well as magnetic noise from a fluctuating external magnetic field. However, while the conventional technology disclosed in Patent Document 1 can remove magnetic noise from a uniform external magnetic field, it may not be able to remove magnetic noise caused by a fluctuating external magnetic field and may still detect it. As a result, the magnetic noise is superimposed on the detected magnetism of the banknote, and if a highly sensitive magnetic sensor is used, the magnetic noise will also be detected.

[0005] In other words, detecting a portion of a banknote that should not have a magnetic output as if it does has a magnetic output, which can reduce the accuracy of identifying banknotes and result in rejecting banknotes that should be accepted or accepting banknotes that should be rejected. For this reason, there has been a demand for a way to neutralize or reduce any disturbance magnetic fields and prevent a decrease in the accuracy of identifying banknotes.

[0006] In view of the above-mentioned problems, an object of the present invention is to suppress a decrease in the accuracy of paper sheet recognition by a paper sheet recognition device. [Means for solving the problem]

[0007] In order to solve such problems, in the present invention, a paper sheet identification device for identifying paper sheets is characterized by having a magnetic noise source that generates a fluctuating magnetic field, a plurality of magnetic detection elements that are arranged perpendicular to the surface of the paper sheets transported on a transport path and detect the magnetism of the paper sheets, a magnetic member that has a magnetic permeability equal to or higher than a predetermined value and is arranged between the plurality of magnetic detection elements and the magnetic noise source, and an operator that performs differential calculations on the magnetic detection values ​​of the paper sheets transported on the transport path based on each detection signal detected by each of the magnetic detection elements. [Effects of the Invention]

[0008] According to the present invention, for example, it is possible to suppress a decrease in the accuracy of paper sheet recognition by a paper sheet recognition device. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is an external perspective view of an automated teller machine according to an embodiment; [Figure 2] 1 is a diagram showing an outline of an internal configuration of an automated teller machine according to an embodiment; [Figure 3] 1 is a side view showing a main part of the configuration of a banknote validator according to an embodiment; [Figure 4] 1 is a plan view showing a main part of the configuration of a banknote validator according to an embodiment; [Figure 5] FIG. 1 is a functional block diagram showing the configuration of a banknote validator according to an embodiment. [Figure 6] FIG. 10 is a diagram for explaining a fluctuating magnetic field in which a bill validator is placed (when there is no magnetic phase shift mitigation plate). [Figure 7] 1 is a diagram for explaining the magnetic flux of a fluctuating magnetic field passing through a differential magnetic sensor of a bill validator (when there is no magnetic phase shift mitigation plate); [Figure 8] FIG. 1 is a diagram for explaining the component decomposition of magnetic flux of a fluctuating magnetic field detected by a differential magnetic sensor of a banknote validator (when there is no magnetic phase shift mitigation plate). [Figure 9] 1 is a diagram for explaining the magnetic flux of a fluctuating magnetic field passing through two magnetic sensor elements of a differential magnetic sensor of a banknote validator (when there is no magnetic phase shift mitigation plate); [Figure 10] 10 is a diagram for explaining magnetic flux fluctuations of a fluctuating magnetic field detected by two magnetic sensor elements of a differential magnetic sensor of a banknote validator (when there is no magnetic phase shift mitigation plate). FIG. [Figure 11] FIG. 10 is a diagram for explaining a fluctuating magnetic field in which a bill validator is placed (when a magnetic phase shift mitigation plate is provided). [Figure 12] FIG. 1 is a diagram for explaining the magnetic flux of a fluctuating magnetic field passing through a differential magnetic sensor of a bill validator (when a magnetic phase shift mitigation plate is present). [Figure 13] FIG. 1 is a diagram for explaining the component decomposition of magnetic flux of a fluctuating magnetic field detected by a differential magnetic sensor of a banknote validator (when a magnetic phase shift mitigation plate is present). [Figure 14] FIG. 10 is a diagram for explaining the magnetic flux of a fluctuating magnetic field passing through two magnetic sensor elements of a differential magnetic sensor of a banknote validator (when a magnetic phase shift mitigation plate is present). [Figure 15] 1 is a diagram for explaining magnetic flux fluctuations of a fluctuating magnetic field detected by two magnetic sensor elements of a differential magnetic sensor of a banknote validator (when a magnetic phase shift mitigation plate is present). DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The following embodiments, including the drawings, are merely examples and are not intended to limit the present invention. In the drawings used to explain the following embodiments, the same reference numerals indicate components or processes having the same or similar functions, and subsequent explanations will be omitted. Furthermore, each embodiment and each modified example can be combined in part or in whole within the scope and consistency of the technical concept of the present invention.

[0011] In the following embodiments, the vertical direction (upward, upward) of the automatic teller machine's housing is the positive direction of the Z axis, the direction from the user's side (front side, forward) of the automatic teller machine's housing to the opposite side (back side, rear) is the positive direction of the Y axis, and the direction from the left side to the right side of the automatic teller machine as viewed from the user's side is the positive direction of the X axis. The following description of the embodiments uses a positive XYZ coordinate system in which the X, Y, and Z axes are orthogonal to each other. In the following embodiments, directions and positions expressed by terms such as "up," "down," "left," "right," "front," "rear," and "back" are merely relative, and the XYZ coordinate system does not limit the orientation, shape, or size of the automatic teller machine, banknote handling machine, or other components. The number of components in the descriptions and illustrations of the embodiments is merely an example.

[0012] In the following embodiments, an automated teller machine or a banknote handling machine that handles banknotes as paper sheets and a banknote recognition device will be described as examples of a paper sheet handling device and a paper sheet recognition device. However, the present invention is not limited to these, and various other paper sheets such as checks and gift certificates can also be handled in the same manner.

[0013] (Overall configuration of the automated teller machine 1) Fig. 1 is an external perspective view of an automated teller machine 1 according to an embodiment. The automated teller machine 1 uses cash cards, banknotes, receipts, etc. as transaction media and processes cash deposits, payments, transfers, etc. in response to user operations. The upper part of the device housing of the automated teller machine 1 is provided with a passbook processing mechanism (not shown) that processes the user's passbook and prints and dispenses transaction details, and a card and receipt processing mechanism (not shown) that processes the user's card and prints and dispenses transaction details.

[0014] The passbook processing mechanism processes the user's passbook inserted through slot 2 on the front of the automated teller machine 1, prints a transaction statement, and discharges it. The card and statement processing mechanism processes the user's card inserted through slot 3 on the front of the automated teller machine, prints a transaction statement, and discharges it together with the card. At the front of the automated teller machine 1 is provided a screen operation unit 4 that displays the details of the user's transaction and allows the user to input various information and items for the transaction.

[0015] A banknote handling device 10 for processing banknotes is provided at the bottom of the device housing of the automated teller machine 1. Banknote deposit and withdrawal transactions are carried out in response to the opening and closing of a shutter 5a provided in a deposit / withdrawal unit 5 of the banknote handling device 10.

[0016] A coin processing device (not shown) that processes coins may be provided inside the device housing of the automated teller machine 1. Coin deposit and withdrawal transactions are carried out in response to the opening and closing of a shutter (not shown) provided in a deposit and withdrawal section of the coin processing device.

[0017] (Internal configuration of the automated teller machine 1) FIG. 2 is a diagram showing an outline of the internal configuration of the automated teller machine 1 according to the embodiment. A processing mechanism for banknotes to be traded is disposed above the lower housing of the automated teller machine 1, and a banknote storage mechanism is disposed below. Above the lower housing of the banknote handling device 10, on the front side (the side facing the user: upper right side in FIG. 2), is a deposit / withdrawal unit 5 that accepts banknotes deposited by users in a substantially upright position and dispenses the banknotes set in a substantially upright position for the user to remove. Also, a banknote recognition device 30 that distinguishes banknotes is disposed in the center, and on the rear side (upper left side in FIG. 2) is a temporary holding unit 40 that temporarily stores banknotes deposited by users until the transaction is completed. These mechanical units are connected by a bidirectional transport path.

[0018] The banknote recognition device 30 can distinguish the denomination and authenticity of banknotes conveyed on the conveying path 30a from either direction, from the front or the rear. The banknote recognition device 30 can distinguish the denomination and authenticity of banknotes conveyed in both the deposit and withdrawal directions, and can determine whether a banknote can be accepted or withdrawn. The depositing and dispensing unit 5 has, at the front and rear, a banknote feeding unit 5b that feeds banknotes inserted from above downward, and a banknote stacking unit 5c that stacks banknotes conveyed from below to be withdrawn or returned.

[0019] A plurality of storage units 70 for storing banknotes by denomination are arranged below the banknote handling device 10. The storage units 70 include one that stores, by denomination, banknotes that have been determined to be acceptable by the banknote recognition device 30, one that temporarily stores banknotes that have been determined to be unacceptable by the banknote recognition device 30, one that stores banknotes that have been determined to be undispensable by the banknote recognition device 30, and one that is used when replenishing banknotes from outside for dispensing.

[0020] (Configuration of the banknote validator 30) Fig. 3 is a side view showing a main part of the configuration of the banknote validation device 30 according to the embodiment. Fig. 4 is a plan view showing a main part of the configuration of the banknote validation device 30 according to the embodiment. In addition to the components shown in Figs. 3 and 4, the banknote validation device 30 also includes various sensors such as a thickness sensor, drive motors for the transport rollers, other transport rollers, etc., which are not shown in the drawings.

[0021] The banknote recognition device 30 includes a conveyance guide 30b, a recognition sensor 31, conveyance rollers 32a and 32b, drive rollers 32a1, 32b1, and 32c1, and magnetic phase shift mitigation plates 33a and 33b. A plurality of conveyance rollers 32a are provided on the positive Y-axis side of the recognition sensor 31, lined up in the X-axis direction. A plurality of conveyance rollers 32b are provided on the negative Y-axis side of the recognition sensor 31, lined up in the X-axis direction.

[0022] Conveyance rollers 32a and 32b are rotated by drive rollers 32a1 and 32b1, which are driven by a drive motor (not shown). Banknotes on conveyance path 30a are sandwiched between conveyance rollers 32a and 32b and drive rollers 32a1 and 32b1 facing conveyance rollers 32a and 32b, and conveyed in the positive and negative directions of the Y axis. Conveyance rollers 32a and 32b are magnetized magnetic bodies, such as bearing rollers, and rotation around the rotation axis causes magnetic poles to rotate, generating a fluctuating magnetic field.

[0023] The recognition sensor 31 has multiple differential magnetic sensors 31a each equipped with magnetic detection elements 31a1 and 31a2 arranged side by side in the Z-axis direction. The Z-axis direction is perpendicular to the surface of the banknote being transported on the transport path 30a and is the magnetic detection direction of the differential magnetic sensors 31a (magnetic detection elements 31a1 and 31a2). The multiple differential magnetic sensors 31a are arranged in an array in the X-axis direction within the recognition sensor 31 to form a sensor array 31A. The drive roller 32c1 presses down on the recognition sensor 31 with a gap large enough to prevent jamming, allowing the banknote to be transported.

[0024] The magnetic phase shift mitigation plates 33a and 33b are provided between the identification sensor 31 and the conveying rollers 32a and 32b, respectively. The magnetic phase shift mitigation plates 33a and 33b are made of plate-shaped magnetic material with a predetermined magnetic permeability or higher, and are arranged so that their longitudinal axes extend in a direction (X-axis direction, direction of the sensor array 31A) perpendicular to the magnetic detection direction (Z-axis direction, magnetic field detection direction) of the magnetic detection elements 31a1 and 31a2.

[0025] The magnetic phase shift mitigation plates 33a and 33b are disposed between the conveying rollers 32a and 32b and the magnetic detection elements 31a1 and 31a2 at positions where the magnetic flux paths formed by the conveying rollers 32a and 32b that reach the magnetic detection elements 31a1 and 31a2 are bent in the most uniform direction and aligned. The magnetic phase shift mitigation plates 33a and 33b are disposed in a direction perpendicular to the magnetic field detection direction of the magnetic detection elements 31a1 and 31a2 so that the magnetic flux paths formed by the conveying rollers 32a and 32b that reach the magnetic detection elements 31a1 and 31a2 are bent in the most uniform direction and aligned. This eliminates the need to dispose the magnetic phase shift mitigation plates 33a and 33b near the magnetic detection elements 31a1 and 31a2. Furthermore, by aligning the magnetic flux in a direction perpendicular to the arrangement direction of the magnetic detection elements 31a1, 31a2, the magnetic field acting on the magnetic detection elements 31a1, 31a2 can be diverted and reduced. Even without reducing the magnetic flux reaching the magnetic detection elements 31a1, 31a2 by placing a magnetic material (a so-called magnetic shield) very close to the magnetic detection elements 31a1, 31a2, the phase shift can be effectively reduced and the differential effect can be increased.

[0026] The longitudinal (X-axis) lengths of the magnetic phase shift mitigation plates 33a and 33b are within a range that maintains the characteristics of the differential magnetic sensor 31a at a certain level regardless of the DC magnetic field caused by the magnetic poles generated in the magnetic phase shift mitigation plates 33a and 33b. The longer the magnetic phase shift mitigation plates 33a and 33b are in the longitudinal (X-axis) direction, the more they can bend the magnetic flux reaching the magnetic detection elements 31a1 and 31a2 in a direction perpendicular to the arrangement direction of the magnetic detection elements 31a1 and 31a2. However, the longer the plates are, the more likely magnetic poles are formed at both ends, causing the magnetic field to travel farther, which may prevent the characteristics of the differential magnetic sensor 31a from being maintained in the DC magnetic field. Therefore, the longitudinal (X-axis) lengths are selected within a range that maintains the characteristics. The transverse (Z-axis) lengths and thicknesses (Y-axis directions) of the magnetic phase shift mitigation plates 33a and 33b may be within a range that does not interfere with other components inside the housing of the banknote identification device 30 and does not cause magnetic saturation.

[0027] The magnetic phase shift mitigation plates 33a and 33b are made of a soft magnetic material with a certain level of magnetic permeability or higher, selected from a group of materials including permalloy and non-oriented silicon steel. The soft magnetic material is preferably heat-treated to reduce its coercive force and make it less likely to form longitudinal magnetic poles.

[0028] (Functional configuration of the banknote validator 30) 5 is a functional block diagram showing the configuration of the banknote validation device 30. In addition to the configuration described above, the banknote validation device 30 has amplifiers 331 and 332 such as operational amplifiers, AD (Analog to Digital) converters 341 and 342, and a computing unit 35 such as a microcomputer.

[0029] Amplifier 331 amplifies the detection signal of magnetic detection element 31a1. Amplifier 332 amplifies the detection signal of magnetic detection element 31a2. AD converter 341 digitizes the detection signal amplified by amplifier 331. AD converter 342 digitizes the detection signal amplified by amplifier 332. Calculator 35 calculates banknote magnetic detection value α1×V1(nT)−α2×V2(nT) based on AD conversion values ​​V1(nT) and V2(nT) of the detection signals digitized by AD converters 341 and 342. Here, n is the sampling order number and is a natural number starting from 0, T is the sampling period, and α1 and α2 are predetermined numbers.

[0030] As will be described later, the banknote magnetic detection value α1×V1(nT)−α2×V2(nT) in this embodiment is a value obtained by correcting the sensitivity of the magnetic detection elements 31a1 and 31a2 and canceling magnetic noise from the uniform magnetic field and the fluctuating magnetic field.

[0031] (Regarding the phase difference of magnetic flux in the magnetic detection direction) Hereinafter, how this embodiment reduces the phase difference between magnetic fluxes in the magnetic detection directions of the magnetic detection elements 31a1 and 31a2 will be described with reference to Figures 6 to 10 and Figures 11 to 15. Figures 6 to 10 show a case where the magnetic phase shift mitigation plates 33a and 33b are not present (prior art), while Figures 11 to 15 show a case where the magnetic phase shift mitigation plates 33a and 33b are present (this embodiment).

[0032] (When magnetic phase shift mitigation plates 33a and 33b are not present) First, with reference to FIGS. 6 to 10, a case where there are no magnetic phase shift mitigation plates 33a and 33b (prior art) will be described.

[0033] With regard to the magnetic flux of a banknote passing on the conveyance path 30a near the magnetic detection elements 31a1 and 31a2, the detection value V1(nT) of the upper magnetic detection element 31a1, which is closer to the banknote, is greater than the detection value V2(nT) of the lower magnetic detection element 31a2, which is farther from the banknote. Therefore, in general, by calculating the difference in the detection values ​​V1(nT)-V2(nT), a detection signal of the magnetic flux of the banknote passing on the conveyance path 30a near the magnetic detection elements 31a1 and 31a2 can be obtained.

[0034] Since the magnetic noise source of the uniform magnetic field is located farther away than the banknotes passing on the conveyance path 30a near the magnetic detection elements 31a1 and 31a2, the distances from the magnetic noise source to the magnetic detection elements 31a1 and 31a2 are approximately equal. Therefore, the magnetic noise of the uniform magnetic field can be considered to be uniformly superimposed on the detection values ​​V1(nT) and V2(nT) of the magnetic detection elements 31a1 and 31a2, and is canceled out by taking the difference between the detection values, V1(nT) - V2(nT).

[0035] Even if there is variation in sensitivity between the upper and lower magnetic detection elements 31a1 and 31a2, a uniform magnetic field is applied in the detection direction of the magnetic detection elements 31a1 and 31a2, and the correction coefficients α1 and α2 for correcting the sensitivity are calculated in advance so that the amplitude values ​​V1 and V2 of the detection signals from the magnetic detection elements 31a1 and 31a2 become the same. Then, by calculating α1 × V1(nT) - α2 × V2(nT), a detection signal with corrected sensitivity and canceled magnetic noise can be obtained.

[0036] Fig. 6 is a diagram for explaining the fluctuating magnetic field in which the banknote recognition device 30 is placed (in the case where the magnetic phase shift mitigation plates 33a, 33b are not present). However, as shown in Fig. 6, if the structure of the conveyance path 30a requires that a weakly magnetized rotating body (conveyance roller 32b in Fig. 6) be placed near the differential magnetic sensor 31a, a phase difference occurs in the magnetic fluxes reaching the upper and lower magnetic detection elements 31a1, 31a2, making it impossible to cancel out the disturbance noise.

[0037] The reason why a phase difference occurs between the magnetic fluxes reaching the upper and lower magnetic detection elements 31a1 and 31a2 is as follows. FIG. 7 is a diagram for explaining the magnetic flux of the fluctuating magnetic field passing through the differential magnetic sensor 31a of the banknote identification device 30 (when the magnetic phase shift mitigation plates 33a and 33b are not present). As shown in FIG. 7, the direction and magnitude of the magnetic field vector H caused by the magnetic flux passing near the sensor center Δ=0 (the center line of the magnetic detection elements 31a1 and 31a2) between the magnetic detection elements 31a1 and 31a2 changes depending on the rotation angle θ of the conveyance roller 32b. This change occurs because the direction and magnitude of the magnetic field vector H are determined by the distance from the magnetic poles S and N of the conveyance roller 32b. The closer the distance from the magnetic poles S and N, the larger the magnetic field vector H.

[0038] Fig. 8 is a diagram for explaining the decomposition of the magnetic flux component of the fluctuating magnetic field detected by the differential magnetic sensor 31a of the banknote recognition device 30 (when the magnetic phase shift mitigation plates 33a, 33b are not present). However, in Fig. 8, the component of the magnetic field vector H in the direction of the sensor array 31A is omitted. As shown in Fig. 8, the magnetic field vector H can be decomposed into a component vector Hy in the banknote conveyance direction on the conveyance path 30a and a component vector Hz in the magnetic field detection direction of the differential magnetic sensor 31a.

[0039] The direction and magnitude of the magnetic field vector H are determined by the distance L from the magnetic poles S and N of the transport roller 32b (see FIG. 7). The distance L varies periodically according to the rotation angle θ of the transport roller 32b (θ is the angle between the S→N magnetization direction of the transport roller 32b and the positive direction of the Z axis). Therefore, the direction and magnitude of the magnetic field vector H and the magnetic field detection direction component vector Hz vary periodically according to the rotation angle θ of the transport roller 32b.

[0040] 9 is a diagram illustrating the magnetic flux of a fluctuating magnetic field passing through two magnetic detection elements 31a1 and 31a2 of the differential magnetic sensor 31a of the banknote recognition device 30 (in the case where magnetic phase shift mitigation plates 33a and 33b are not present). Magnetic detection elements 31a1 and 31a2 are spaced apart from the sensor center Δ=0 by an inter-element distance of ±Δd / 2 in the magnetic field detection direction (Z-axis direction). Due to the difference in their positions, the orientations of the magnetic field vector H1 of magnetic detection element 31a1 and the magnetic field vector H2 of magnetic detection element 31a2 differ from the magnetic field vector H at the sensor element center.

[0041] For this reason, for example, when the rotation angle θ=0°, the magnitude |H1z| of the magnetic field detection direction component vector H1z of the magnetic field vector H1 of the magnetic detection element 31a1 is smaller than the magnitude |Hz| of the magnetic field detection direction component vector Hz of the magnetic field vector H at the sensor center Δ=0. Also, when the rotation angle θ=0°, the magnitude |H2z| of the magnetic field detection direction component vector H2z of the magnetic field vector H2 of the magnetic detection element 31a2 is larger than the magnitude |Hz| of the magnetic field detection direction component vector Hz of the magnetic field vector H at the sensor center Δ=0. This difference is determined by the effect of the surrounding magnetic moment.

[0042] The magnetic field detection direction component vector H1z undergoes similar periodic changes compared to the magnetic field detection direction component vector Hz, but the timing at which they reach the same magnitude is delayed, so the magnetic field detection direction component vector H1z appears to be lagging in phase with the magnetic field detection direction component vector Hz. Furthermore, the magnetic field detection direction component vector H2z undergoes similar periodic changes compared to the magnetic field detection direction component vector Hz, but the timing at which they reach the same magnitude is earlier, so the magnetic field detection direction component vector H2z appears to be leading in phase with the magnetic field detection direction component vector Hz.

[0043] 10 is a diagram (in the absence of magnetic phase shift mitigation plates 33a, 33b) for explaining magnetic flux fluctuations of the fluctuating magnetic field detected by the two magnetic detection elements 31a1, 31a2 of the differential magnetic sensor 31a of the banknote recognition device 30. As shown in FIG. 10, a phase difference occurs in the fluctuating magnetic field due to the rotation of the conveyance roller 32b between the magnetic field detection direction component vectors H1z, H2z of the magnetic detection element 31a1 and the magnetic detection element 31a2.

[0044] Therefore, the banknote magnetic detection value α1×V1(nT) - α2×V2(nT) calculated using the detection value V1(nT) of the magnetic field detection direction component vector H1z and the detection value V2(nT) of the magnetic field detection direction component vector H2z will contain magnetic noise from external noise sources that generate fluctuating magnetic fields, remaining in the amount of the phase difference.

[0045] (When magnetic phase shift mitigation plates 33a and 33b are present) Next, with reference to FIGS. 11 to 15, a case where magnetic phase shift mitigation plates 33a and 33b are provided (this embodiment) will be described.

[0046] 11 is a diagram illustrating the fluctuating magnetic field in which the banknote recognition device 30 is placed (when magnetic phase shift mitigation plates 33a and 33b are provided). As shown in Fig. 11, in this embodiment, a magnetic phase shift mitigation plate 33b is provided between the differential magnetic sensor 31a and the conveyance roller 32b. In this case, the magnetic flux detected by the differential magnetic sensor 31a is attracted to the magnetic phase shift mitigation plate 33b and distorted as it tries to become parallel to the longitudinal direction (X-axis direction) of the magnetic phase shift mitigation plate 33b.

[0047] 12 is a diagram (in the case where magnetic phase shift mitigation plates 33a and 33b are present) for explaining the magnetic flux of the fluctuating magnetic field passing through the differential magnetic sensor 31a of the banknote recognition device 30. As a result, as shown in FIG. 12, the magnetic field vector H' caused by the magnetic flux passing through the vicinity of the sensor center Δ=0 between the magnetic detection elements 31a1 and 31a2 attempts to become parallel to the magnetic phase shift mitigation plate 33b and faces in the longitudinal direction of the magnetic phase shift mitigation plate 33b.

[0048] Fig. 13 is a diagram for explaining the decomposition of the magnetic flux component of the fluctuating magnetic field detected by the differential magnetic sensor 31a of the banknote recognition device 30 (when magnetic phase shift mitigation plates 33a, 33b are present). However, in Fig. 13, the component of the magnetic field vector H' in the direction of the sensor array 31A is omitted. As shown in Fig. 13, the magnetic field vector H' can be decomposed into a component vector H'y in the banknote conveyance direction on the conveyance path 30a and a component vector H'z in the magnetic field detection direction of the differential magnetic sensor 31a.

[0049] The direction and magnitude of the magnetic field vector H' and magnetic field detection direction component vector H'z, like the magnetic field vector H and magnetic field detection direction component vector Hz, vary periodically according to the rotation angle θ of the conveying roller 32b. Furthermore, the magnitude |H'z| of the magnetic field detection direction component vector H'z is smaller than the magnitude |Hz| of the magnetic field detection direction component vector Hz in the absence of the magnetic phase shift mitigation plates 33a and 33b. |H'z| is smaller than |Hz| because the magnetic phase shift mitigation plates 33a and 33b attract magnetic flux, reducing the magnetic field lines and bringing distant magnetic flux, which is originally weak, closer to the element.

[0050] 14 is a diagram (in the case where magnetic phase shift mitigation plates 33a and 33b are provided) for explaining the magnetic flux of the fluctuating magnetic field passing through the two magnetic detection elements 31a1 and 31a2 of the differential magnetic sensor 31a of the banknote recognition device 30. When the magnetic phase shift mitigation plate 33b is provided between the differential magnetic sensor 31a and the conveyance roller 32b, a force acts to uniformly align the direction of the magnetic field passing through the two magnetic detection elements 31a1 and 31a2 toward the sensor array 31A regardless of the position within ±Δd / 2.

[0051] Therefore, for example, when the rotation angle θ is 0°, the magnitude |H1'z| of the magnetic field detection direction component vector H1'z of the magnetic field vector H1 of the magnetic detection element 31a1, the magnitude |H'z| of the magnetic field detection direction component vector H'z of the magnetic field vector H' at the sensor center, and the magnitude |H2'z| of the magnetic field detection direction component vector H2'z of the magnetic field vector H2 of the magnetic detection element 31a2 are all approximately the same. Furthermore, these |H1'z|, |H'z|, and |H2'z| are smaller than the values ​​|H1z|, |Hz|, and |H2z| when the magnetic phase shift mitigation plates 33a and 33b are not provided (prior art). The reason why |H1'z|, |H'z|, and |H2'z| are smaller than |H1z|, |Hz|, and |H2z| is that the magnetic phase shift mitigation plates 33a and 33b attract magnetic flux, reducing the magnetic field lines and causing distant magnetic flux, which is originally at a low level, to approach the element.

[0052] Therefore, compared to the case where the magnetic phase shift mitigation plates 33a and 33b are not present (prior art), the magnetic field detection direction component vectors H1'z and H2'z change periodically in the same manner as the magnetic field detection direction component vector H'z, and the phase difference is also approximately zero.

[0053] 15 is a diagram (in the case where magnetic phase shift mitigation plates 33a and 33b are provided) for explaining the magnetic flux fluctuation of the fluctuating magnetic field detected by the two magnetic detection elements 31a1 and 31a2 of the differential magnetic sensor 31a of the banknote recognition device 30. That is, as shown in FIG. 15, the phase difference between the magnetic field detection direction component vectors H1'z and H2'z of the magnetic flux generated by the conveyance roller 32b and detected by the magnetic detection elements 31a1 and 31a2 is approximately zero.

[0054] Therefore, using the detection value V1(nT) obtained by detecting the magnetic field detection direction component vector H1'z and the detection value V2(nT) obtained by detecting the magnetic field detection direction component vector H2'z, magnetic noise from an external noise source that generates a fluctuating magnetic field can be canceled by calculating the banknote magnetic detection value α1×V1(nT)−α2×V2(nT) in the same manner as in the conventional method. In other words, the banknote validation device 30 has the same configuration as the conventional banknote validation device, except for the addition of magnetic phase shift mitigation plates 33a and 33b.

[0055] Experiments have shown that the longer the magnetic phase shift mitigation plates 33a and 33b are in the direction of the sensor array 31A, the more uniform the direction of the magnetic field between the magnetic detection elements 31a1 and 31a2 in the range Δ≦±Δd / 2 becomes in the direction of the sensor array 31A. From this, it can be said that the longer the magnetic phase shift mitigation plates 33a and 33b are in the direction of the sensor array 31A, the greater the effect of reducing external noise from external noise sources that generate fluctuating magnetic fields.

[0056] (Other embodiments) As another embodiment, a paper sheet recognition method performed by a paper sheet recognition device will be described.

[0057] The paper sheet recognition device (e.g., banknote recognition device 30) includes a magnetic noise source (e.g., conveying rollers 32a, 32b, drive rollers 32a1, 32b1) that generates a fluctuating magnetic field, a conveying path (e.g., conveying path 30a) that conveys paper sheets (e.g., banknotes), a plurality of magnetic detection elements (e.g., magnetic detection elements 31a1, 31a2) that are arranged perpendicular to the surface of the paper sheets conveyed on the conveying path and detect the magnetism of the paper sheets, and an arithmetic unit (e.g., arithmetic unit 35) that calculates a differential detection value based on each detection signal detected by each magnetic detection element.

[0058] In the paper sheet identification method in this paper sheet identification device, a magnetic member (e.g., magnetic phase shift mitigation plates 33a, 33b) having a magnetic permeability equal to or higher than a predetermined value and having a shape extending longitudinally in the width direction of the conveying path is arranged between the plurality of magnetic detection elements and a magnetic noise source, and the plurality of magnetic detection elements detect the magnetism of the paper sheets being conveyed on the conveying path, and a calculator calculates a differential detection value of the paper sheets being conveyed on the conveying path based on the detection signals detected by each magnetic detection element.

[0059] According to the above-described embodiment, a magnetic member having a predetermined or higher magnetic permeability is disposed between the plurality of magnetic detection elements and the magnetic noise source. This allows for a simple configuration without changing the calculation method for the banknote magnetic detection value α1×V1(nT)−α2×V2(nT), and it is possible to suppress magnetic noise caused by magnetic noise sources that generate fluctuating magnetic fields, improve resistance to external magnetic noise, and accurately detect banknote magnetism. As a result, it is possible to improve the accuracy of banknote authenticity determination. It is also possible to increase the yield of magnetic sorting of transport mechanism components.

[0060] Furthermore, compared to magnetically shielding the element with a plate material with high magnetic permeability, the magnetic field of the sensor magnetic circuit is not disturbed, so the expected characteristics can be obtained even when using a highly sensitive magnetic detection element.

[0061] The present invention is not limited to the above-described embodiments and includes various modifications. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and are not necessarily limited to those including all of the described configurations. Furthermore, as long as there is no contradiction, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, or to add the configuration of one embodiment to the configuration of another embodiment. Furthermore, it is possible to add, delete, replace, integrate, and divide part of the configuration of each embodiment. Furthermore, each process shown in the embodiments may be appropriately distributed or integrated based on processing efficiency or implementation efficiency. [Explanation of symbols]

[0062] 1... automated teller machine, 10... banknote handling device, 30... banknote validator, 30a... conveyance path, 31a1, 31a2... magnetic detection elements, 32a, 32b... conveyance rollers, 32a1, 32b1... drive rollers, 33a, 33b... magnetic phase shift mitigation plates, 35... computing unit

Claims

1. A paper sheet identification device for identifying paper sheets, a magnetic noise source that generates a fluctuating magnetic field; a plurality of magnetic detection elements arranged in a direction perpendicular to the surface of the paper sheets transported on the transport path, for detecting magnetism of the paper sheets; a magnetic member having a magnetic permeability equal to or higher than a predetermined value and disposed between the plurality of magnetic detection elements and the magnetic noise source; a computing unit that performs differential calculation of magnetic detection values ​​of paper sheets transported on the transport path based on each detection signal detected by each of the magnetic detection elements; A paper sheet recognition device comprising:

2. The paper sheet recognition device according to claim 1, The paper sheet identifying device, wherein the magnetic noise source includes a transport roller that rotates following a drive roller to transport the paper sheet, and the drive roller.

3. The paper sheet recognition device according to claim 1, The paper sheet identifying device is characterized in that the magnetic member has a shape whose longitudinal direction extends in the width direction of the transport path.

4. The paper sheet recognition device according to claim 3, A paper sheet identifying device characterized in that the length of the magnetic member is within a range that allows the magnetic detection characteristics of the plurality of magnetic detection elements to be maintained at a certain level or higher regardless of a DC magnetic field caused by magnetic poles generated in the magnetic member.

5. The paper sheet recognition device according to claim 1, The paper sheet identification device is characterized in that the magnetic member is positioned in a position where it uniformly bends and aligns the path of the magnetic flux passing through the plurality of magnetic detection elements in the width direction of the conveying path, in a direction perpendicular to the arrangement direction of the plurality of magnetic detection elements.

6. The paper sheet recognition device according to claim 5, The paper sheet identifying device is characterized in that the magnetic member is arranged such that its longitudinal direction is in the width direction of the transport path and is perpendicular to the magnetic field detection direction of the plurality of magnetic detection elements.

7. The paper sheet recognition device according to claim 1, The paper sheet identifying device is characterized in that the magnetic member is a soft magnetic material selected from a group of materials including permalloy and non-oriented silicon steel plate.

8. The paper sheet recognition device according to claim 7, The paper sheet identifying device is characterized in that the soft magnetic material is heat-treated.

9. A paper sheet handling device comprising the paper sheet identifying device according to any one of claims 1 to 8.

10. A paper sheet identification method for identifying paper sheets, comprising: a magnetic noise source that generates a fluctuating magnetic field; a plurality of magnetic detection elements arranged in a direction perpendicular to the surface of the paper sheets transported on the transport path, for detecting magnetism of the paper sheets; a calculator that calculates a differential detection value of the paper sheets transported on the transport path based on each detection signal detected by each of the magnetic detection elements, a magnetic member having a magnetic permeability equal to or greater than a predetermined value and extending longitudinally in a width direction of the transport path perpendicular to a magnetic field detection direction of the magnetic detection elements is disposed between the plurality of magnetic detection elements and the magnetic noise source; the plurality of magnetic detection elements detect magnetism of the paper sheets transported on the transport path; The computing unit performs differential computation of magnetic detection values ​​of the paper sheets transported on the transport path based on the detection signals detected by the magnetic detection elements. A paper sheet identification method comprising:

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