JP6315802B2 - Magnetic sensor device - Google Patents

Description

  The present invention relates to a magnetic sensor device for identifying paper sheets such as banknotes and securities printed using magnetic ink.

2. Description of the Related Art Conventionally, magnetic sensor devices for identifying the authenticity and type of paper sheets such as banknotes and securities printed using magnetic ink containing a magnetic material have been put into practical use.
A general magnetic sensor device includes a magnetoelectric conversion element such as a Hall element that generates a potential difference due to magnetism or a magnetoresistive element whose resistance value changes, and a permanent magnet that generates magnetic flux, and a sheet passes through a conveyance path. At the same time, the phenomenon that the magnetic substance contained in the paper sheet changes the magnetic flux is detected by converting it into an electric signal.

  A conventional magnetic sensor device has a gap for passing a paper sheet as a conveyance path for paper sheets, a magnetoelectric conversion element and a permanent magnet are provided on one side of the conveyance path, and the conveyance path is sandwiched between them. A pressing rotation roller is provided at the opposed position. The pressure rotating roller conveys the paper sheet while pressing it toward the magnetoelectric conversion element in the conveyance path, thereby suppressing a decrease in detection sensitivity due to the distance between the paper sheet and the magnetoelectric conversion element.

  However, it is difficult to transport the paper sheet at a high speed in a state where the paper sheet is completely adhered to the magnetoelectric conversion element side in the transport path, and the paper sheet is slightly separated from the magnetoelectric conversion element side. In addition, by providing the pressing roller, there is a concern that the conveyance performance of the folded paper sheets and the broken paper sheets deteriorates and a conveyance jam occurs. In order to convey at high speed, it is necessary to convey paper sheets in a non-contact state with the magnetoelectric transducer.

When transporting in a non-contact state, there is a problem that the paper sheets are greatly separated from the magnetoelectric conversion element side, and the detection sensitivity is greatly reduced.
In order to solve the problem, various methods have been tried in the past, such as not only arranging the permanent magnet on the magnetic sensor side but also arranging the permanent magnet on the opposite side of the conveyance path facing the magnetoelectric conversion element ( Patent Documents 1 and 2).

5 and 6, the transport path 8 through which the paper sheet is transported is on the xy plane, and the paper sheet is transported in the x direction. The magnetoelectric conversion element is represented by “5”.
FIG. 5 is a view showing the arrangement of magnetic flux generating members (permanent magnets) 100 and 101 provided on both sides of the conveyance path in the magnetic sensor device described in Patent Document 1, and FIG. It is a figure which shows arrangement | positioning of the magnetic flux generation member (permanent magnet) 102,103 provided in the both sides of the conveyance path in a sensor apparatus. N and S indicate the polarities of the permanent magnets.

  With these arrangements, a substantially uniform magnetic field can be applied in the z direction perpendicular to the conveyance path within the conveyance path, and a magnetic flux that does not weaken the magnetic flux density even when the paper sheet is separated from the magnetoelectric conversion element can be provided. . Therefore, when conveying paper sheets at a high speed, it is possible to suppress a decrease in detection sensitivity due to the separation of the paper sheets from the magnetoelectric transducer.

JP 2001-21631 A JP 2012-255770 A

In the configuration in which the permanent magnets are arranged on both sides of the conveyance path as described above, at least one set of the permanent magnets is necessary on the upper and lower sides, so that the entire magnetic sensor device becomes large and expensive.
In particular, claim 1 of Patent Document 2 describes a configuration in which magnets are arranged only on one side of the magnetoelectric conversion element and the conveyance path, but the specific configuration is not explicitly described in the specification. In the description of the embodiment of the specification of Patent Document 2, a permanent magnet is provided above and below across the conveyance path, or a permanent magnet is provided on the upper side and a magnetic body is provided on the lower side. Becomes large and expensive.

In both Patent Documents 1 and 2, it is possible to suppress a decrease in detection sensitivity when the paper sheet is separated from the magnetoelectric conversion element by a substantially uniform magnetic flux in the z direction perpendicular to the conveyance path. If the magnetic flux at a far place is made stronger than the place near the magnetoelectric conversion element in the z-axis direction, the amount of decrease in detection sensitivity can be further suppressed.
Therefore, the problem to be solved by the present invention is that the signal output of the magnetic substance contained in the paper sheet is achieved even when the paper sheet is transported at an arbitrary vertical position in the transport path by a smaller and cheaper magnetic flux generating member. It is providing the magnetic sensor apparatus which can suppress the fall amount of this.

  The magnetic sensor device of the present invention includes a magnetic flux generating member provided on one side of a transport path, and a magnetic material of a paper sheet provided opposite to the magnetic flux generating member across the transport path and transported through the transport path. A magnetic-electric conversion element that converts a change in magnetic flux from the magnetic flux generation member due to the component into an electrical signal, and the magnetic flux generation member includes at least two first permanent magnets and a second permanent magnet, The direction of magnetic polarization of the permanent magnet and the direction of magnetic polarization of the second permanent magnet are opposite to each other.

  According to the magnetic sensor device, the following operation is obtained. In order to compensate for the detection sensitivity that suddenly decreases as the paper leaves the magnetoelectric conversion element, when the paper passes near the magnetoelectric conversion element in the transport path near the magnetoelectric conversion element, it is generated from the magnetic flux generating member. When the magnetic flux is weak and passes far away from the magnetoelectric conversion element, the magnetic flux generated from the magnetic flux generating member is strengthened, and the paper sheet detection sensitivity does not decrease even if the paper sheet is away from the element compared to the prior art. Can be.

If the direction of magnetic polarization of the first permanent magnet and the direction of magnetic polarization of the second permanent magnet are parallel to the transport direction of the transport path, the paper sheet transports the magnetic flux in the transport path. The distance from the magnetoelectric conversion element in the direction perpendicular to the surface to be applied can be increased rapidly.
The direction of magnetic polarization of the first permanent magnet and the direction of magnetic polarization of the second permanent magnet may be perpendicular to the transport direction of the transport path.

  The magnetic flux generating member is composed of at least three first permanent magnets, second permanent magnets, and third permanent magnets, and the second permanent magnets include the first permanent magnets and the third permanent magnets. The direction of the magnetic polarization of the first permanent magnet is the same as the direction of the magnetic polarization of the third permanent magnet, and the direction of the magnetic polarization of the second permanent magnet is the first and third The direction of the magnetic polarization of the permanent magnet may be opposite.

In this case, the direction of magnetic polarization of the first, second, and third permanent magnets is preferably perpendicular to the transport direction of the transport path.
When the magnetic flux generating member is viewed in a cross section perpendicular to the surface on which the paper sheet is conveyed and including the conveying direction, the central portion of the tip of the magnetic flux generating member is directed toward the magnetoelectric conversion element as compared with its peripheral portion. It is desirable that the shape be thin. By adopting such a shape, it is possible to increase the concentration of magnetic flux at a position where the paper sheet is away from the magnetoelectric conversion element, and to increase the magnetic flux density.

  According to the present invention, (1) the magnetic sensor device is downsized, and (2) the paper sheet is transported on the side close to the magnetoelectric conversion element in a state where a certain gap is provided in the paper sheet transport path. Compared to the case, the two problems that are difficult to achieve at the same time, that is, suppressing the decrease in the output of the magnetoelectric conversion element when transported on the far side can be solved at the same time. Therefore, in a small magnetic sensor device, there is an excellent effect that it is possible to accurately identify bills and securities printed using magnetic ink or the like.

The first permanent magnet 21 and the second permanent magnet 22 are set so that the direction of the magnetic polarization P1 of the first permanent magnet 21 and the direction of the magnetic polarization P2 of the second permanent magnet 22 are opposite to each other. It is side sectional drawing which shows the magnetic sensor apparatus which employ | adopted the magnetic flux generation member 2 made to contact | abut. The first permanent magnet 21, the second permanent magnet 22, and the third permanent magnet 23 are included, and the second permanent magnet 22 is interposed between the first permanent magnet 21 and the third permanent magnet 23. The direction of the magnetic polarization of the first permanent magnet 21 is the same as the direction of the magnetic polarization of the third permanent magnet 23, and the direction of the magnetic polarization of the second permanent magnet 22 is the same as that of the first and permanent magnets. It is a sectional side view which shows the magnetic sensor apparatus which employ | adopted the magnetic flux generation | occurrence | production member 2 contacted in the direction opposite to the direction of magnetic polarization. It is a block diagram which shows the outline | summary of the circuit which detects magnetic flux (phi). The magnetic flux generating member so that the direction of the magnetic polarization P1 of the first permanent magnet 21 and the direction of the magnetic polarization P2 of the second permanent magnet 22 are opposite to each other and perpendicular to the transport direction x of the transport path. FIG. It is a sectional side view which shows the conventional magnetic sensor apparatus. It is a sectional side view which shows the conventional magnetic sensor apparatus.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
The scope of the present invention is defined by the terms of the claims, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.
<Magnetic sensor device>
FIG.1 and FIG.2 is a sectional side view which shows the principal part of the magnetic sensor apparatus 1 which detects the magnetic pattern F formed in paper sheets S, such as securities and a banknote.

  1 and 2, the transport path 8 through which the paper sheet S is transported is in the xy plane, and the transport direction of the paper sheet S is the x direction. The transport path 8 includes a flat lower guide plate 6 disposed perpendicular to the z-axis perpendicular to the transport path 8 and a flat upper guide plate 7 disposed in parallel with the lower guide plate 6 at a distance D. And formed by. In order to smoothly insert and remove the sheet S from the conveyance path 8, the end of the lower guide plate 6 on the downstream side and the end on the upstream side of the lower guide plate 6 are bent downward. Thus, the end side on the transport downstream side of the upper guide plate 7 and the end side on the transport upstream side are bent upward.

  The upper guide plate 7 and the lower guide plate 6 are preferably formed of a non-magnetic material such as resin so as not to prevent the magnetoelectric conversion element 5 from accurately detecting the magnetic flux φ. Any material may be used for the non-magnetic material, and a synthetic resin plate may be used. However, in view of wear resistance with banknotes, a material having a high surface strength is desirable. In particular, metals such as brass and copper are desirable, and it is more desirable to increase the surface strength of these metals by surface treatment or plating. Moreover, even in the case of a synthetic resin plate, if plating is performed and the surface hardness is increased, integration with the apparatus housing becomes possible, which is advantageous in terms of cost.

The substrate 3 is fixed to the lower guide plate 6 below the lower guide plate 6. Mounted on the substrate 3 are a magnetoelectric conversion element 5, a power supply circuit (not shown) for driving the magnetoelectric conversion element 5, and an electronic component 24 that processes a signal from the magnetoelectric conversion element 5.
The magnetoelectric conversion element 5 is an element that detects the magnetic flux φ and outputs an electrical signal. The type is not limited. For example, a Hall element that generates a potential difference due to the magnetic flux φ or a magnetoresistive element whose resistance value changes can be used. The power supply circuit is a circuit element that applies a bias voltage or a bias current to the magnetoelectric conversion element 5 so that the magnetoelectric conversion element 5 can operate with optimum sensitivity. The electronic component 24 is configured by an IC or the like that amplifies the signal of the magnetoelectric conversion element 5 and extracts a signal corresponding to a change in magnetic flux caused by paper sheets.

<Magnetic flux generating member>
FIG. 1 shows a magnetic flux generating member 2 composed of a first permanent magnet 21 and a second permanent magnet 22 installed at a position facing the magnetoelectric conversion element 5 across the transport path 8.
The material of the first permanent magnet 21 and the second permanent magnet 22 is not limited, but a material that can provide a large magnetic polarization with a small volume and is inexpensive is desirable. For example, sintered magnets such as resin magnets (plastic magnets) that contain NdFeB magnetic powder in nylon resin, metal alloy magnets such as alnico, ferrite magnets, Sm magnets, and Nd magnets that can be easily processed in shape. Can be used. Of these, those having good temperature characteristics are desirable.

Although FIG. 1 shows a cross section and cannot be illustrated, the magnetic flux generating member 2 extends long in the width direction. One magnetoelectric conversion element 5 or a plurality of magnetoelectric conversion elements 5 are arranged in a one-dimensional array in the width direction within a plane on which paper sheets are conveyed.
The magnetic flux generating member 2 preferably has a width larger than the width of the magnetoelectric conversion element 5 in order to generate the magnetic flux φ as uniform as possible in the width direction.

  The magnetic flux generating member 2 has a chamfered shape such that the central portion of the tip thereof becomes narrower toward the magnetoelectric conversion element 5 than the peripheral portion thereof when viewed in cross section along the xz plane. With this chamfered shape, the magnetic flux can be concentrated and strengthened even if the paper sheet is at a position away from the magnetoelectric transducer 5. Further, by changing the chamfering width w and the angle θ shown in FIG. 1, the distribution of the magnetic flux according to the magnetoelectric conversion element to be used can be finely adjusted.

The magnetic polarization from the S pole to the N pole of the first permanent magnet 21 is indicated by P1, and the magnetic polarization from the S pole to the N pole of the second permanent magnet 22 is indicated by P2. P1 and P2 are vectors having magnitude and direction. Both the direction of the magnetic polarization P1 and the direction of the magnetic polarization P2 are in the x direction.
The magnetic polarization P1 and the magnetic polarization P2 are opposite to each other.
According to this embodiment, the first permanent magnet 21 and the second permanent magnet 22 have their N pole faces in contact with each other. On the contrary, the first permanent magnet 21 and the second permanent magnet 22 may have their S pole faces in contact with each other. In short, the magnetic polarization P1 and the magnetic polarization P2 only need to be opposite to each other.

  With such a configuration of the magnetic flux generating member 2, the magnetic flux φ emitted from the N pole of the magnetic polarization P1 advances in the −z direction while turning to the S pole side of P1, and changes its direction to z. In the direction, it returns to the south pole of the magnetic polarization P1. Further, the magnetic flux φ from the N pole of the magnetic polarization P2 advances in the −z direction while turning to the S pole side of the P2 in the transport path 8, changes its direction, advances in the z direction, and moves to the S pole side of the magnetic polarization P2. Come back.

Since the center part of the front-end | tip of the magnetic flux generation member 2 has a shape which becomes thin toward the magnetoelectric conversion element 5 compared with the peripheral part, the 1st permanent magnet 21 and the 2nd permanent magnet 22 The magnetic flux φ from the N pole is concentrated near the N pole, and its density is high.
Therefore, such a configuration of the magnetic flux generation member 2 weakens the magnetic flux φ in the vicinity of the magnetoelectric conversion element 5 along the z direction when the paper sheet passes near the magnetoelectric conversion element 5. The magnetic flux density can be increased abruptly as the distance of 5 is increased and the paper sheet is separated from the magnetoelectric conversion element.

As a result, even when the paper sheet S being transported passes through the transport path 8 between the lower guide plate 6 and the upper guide plate 7 at a position arbitrarily separated from the magnetoelectric transducer 5 in the z direction. A decrease in detection sensitivity of the conversion element 5 can be suppressed.
FIG. 2 shows a magnetic flux generating member 2 including a first permanent magnet 21, a second permanent magnet 22, and a third permanent magnet 23 installed at a position facing the magnetoelectric conversion element 5. The second permanent magnet 22 is interposed between the first permanent magnet 21 and the third permanent magnet 23.

As in FIG. 1, the magnetic flux generating member 2 has a shape such that the central portion at the tip thereof becomes narrower toward the magnetoelectric conversion element 5 than the peripheral portion.
The magnetic polarization from the S pole of the first permanent magnet 21 to the N pole is indicated by P1, the magnetic polarization of the second permanent magnet 22 from the S pole to the N pole is indicated by P2, and the S of the third permanent magnet 23 is displayed. The magnetic polarization from the pole to the N pole is denoted by P3. P1, P2, and P3 are vectors having magnitude and direction. The direction of the magnetic polarization P1, the direction of the magnetic polarization P2, and the direction of the magnetic polarization P3 are all in the z direction perpendicular to the transport path 8.

  The direction of the magnetic polarization P1 of the first permanent magnet 21 is the same as the direction of the magnetic polarization P3 of the third permanent magnet 23, and the direction of the magnetic polarization P2 of the second permanent magnet 22 is the first and second directions. The direction of magnetic polarization P1 and P3 of the third permanent magnet 23 is opposite. In FIG. 2, the direction of the magnetic polarization P2 is the S pole at the end in the z direction and the N pole at the end in the -z direction. Conversely, the end in the z direction is the N pole and the end in the -z direction is It may be the S pole.

With such a configuration of the magnetic flux generating member 2, the magnetic flux φ emitted from the N pole of the magnetic polarization P2 advances in the -z direction while turning left and right in the transport path 8 to the S pole side of P1 and P3. And change in the z direction to return to the S poles of the magnetic polarizations P1 and P3, respectively.
Since the central portion of the tip of the magnetic flux generating member 2 has a shape that becomes narrower toward the magnetoelectric conversion element 5 than the peripheral portion thereof, the magnetic flux φ coming out from the N pole of the second permanent magnet 22. Are concentrated in the vicinity of the N pole and the density thereof is high.

  Preferably, the relationship between the magnitude of the magnetic polarization P1 of the first permanent magnet 21 and the magnitude of the magnetic polarization P2 of the second permanent magnet 22 is | P1 | ≦ | P2 | The relationship between the magnitude of the magnetic polarization P3 and the magnitude of the magnetic polarization P2 of the second permanent magnet 22 is | P3 | ≦ | P2 |. That is, it is preferable that the magnitude of the magnetic polarization P2 of the second permanent magnet 22 at the center is the maximum.

By satisfying such a relationship, the magnetic field in the vicinity of the N pole of the magnetic polarization P2 can be concentrated more than in the vicinity of the magnetoelectric conversion element 5.
Therefore, with such a configuration of the magnetic flux generating member 2, a magnetic flux φ that rapidly increases from the near position where the paper sheets are conveyed along the z direction to the far position in the vicinity of the magnetoelectric conversion element 5 can be obtained.

<Detection circuit>
FIG. 3 is a block diagram showing an outline of a circuit for detecting the magnetic flux φ when a Hall element is used for the magnetoelectric conversion element 5. A signal corresponding to the magnetic flux detected by the Hall element is amplified by the preamplifier 24a, the output of the preamplifier 24a passes through the high-pass filter 24b, and only a high frequency component is extracted, and a large amplitude signal is extracted by the power amplifier 24c. The magnetic pattern F formed on the paper sheet S can be detected by processing in a subsequent circuit (not shown) based on the large amplitude signal.

  Although the embodiments of the present invention have been described above, the embodiments of the present invention are not limited to the above embodiments. For example, as shown in FIG. 4, the direction of the magnetic polarization P1 of the first permanent magnet 21 and the direction of the magnetic polarization P2 of the second permanent magnet 22 are opposite to each other and perpendicular to the transport direction x of the transport path. Thus, the magnetoelectric conversion element 5 is installed directly below the first permanent magnet 21 (indicated by “5a”) or directly below the second permanent magnet 22 (indicated by “5b”). Alternatively, the magnetoelectric conversion element 5 may be installed directly below the first permanent magnet 21 and directly below the second permanent magnet 22. If such an arrangement is adopted, the density of the magnetic flux when the paper sheet is transported on the far side is improved compared with the case when the paper sheet is transported on the side close to the magnetoelectric conversion element 5a and / or 5b. The output drop of the element 5a and / or 5b can be suppressed.

DESCRIPTION OF SYMBOLS 1 Magnetic sensor apparatus 2 Magnetic flux generation member 3 Board | substrate 5,5a, 5b Magnetoelectric conversion element 6 Lower guide plate 7 Upper guide plate 21,22,23 Permanent magnet 24,24a, 24b, 24c Electronic component

Claims (8)

In a magnetic sensor device for detecting a magnetic body contained in a paper sheet conveyed through a conveyance path,
A magnetic flux generating member provided on one side of the conveying path;
Magnetoelectric conversion is provided opposite to the magnetic flux generation member across the conveyance path, and converts a change in magnetic flux from the magnetic flux generation member due to the magnetic material component of the paper sheet conveyed through the conveyance path into an electric signal. An element, and
The magnetic flux generating member includes at least two first permanent magnets and a second permanent magnet. The direction of magnetic polarization of the first permanent magnet and the direction of magnetic polarization of the second permanent magnet Are magnetic sensor devices characterized by being opposite to each other.   The magnetic sensor device according to claim 1, wherein a direction of magnetic polarization of the first permanent magnet and a direction of magnetic polarization of the second permanent magnet are parallel to a transport direction of the transport path.   The magnetic sensor device according to claim 1, wherein the direction of magnetic polarization of the first permanent magnet and the direction of magnetic polarization of the second permanent magnet are perpendicular to the transport direction of the transport path. The magnetic flux generating member comprises at least three first permanent magnets, second permanent magnets, and third permanent magnets,
The second permanent magnet is interposed between the first permanent magnet and the third permanent magnet,
The direction of magnetic polarization of the first permanent magnet is the same as the direction of magnetic polarization of the third permanent magnet, and the direction of magnetic polarization of the second permanent magnet is the first and third permanent magnets. The magnetic sensor device according to claim 1, wherein the magnetic sensor device has a direction opposite to a magnetic polarization direction of the magnet.   The magnetic sensor device according to claim 4, wherein a direction of magnetic polarization of the first, second, and third permanent magnets is perpendicular to a surface on which the paper sheet is conveyed.   The relationship between the magnitude of the magnetic polarization P1 of the first permanent magnet and the magnitude of the magnetic polarization P2 of the second permanent magnet is | P1 | ≦ | P2 |, and the magnitude of the magnetic polarization P3 of the third permanent magnet 6. The magnetic sensor device according to claim 4, wherein the relationship between the magnetic polarization P2 and the second permanent magnet is | P3 | ≦ | P2 |.   When the magnetic flux generating member is viewed in cross section in a cross section that is perpendicular to the surface on which the paper sheet is transported and includes the transport direction, the center portion of the tip of the magnetic flux generating member is compared with its peripheral portion, The magnetic sensor device according to claim 1, wherein the magnetic sensor device has a shape that narrows toward the magnetoelectric conversion element. The magnetoelectric conversion element is arranged in one or a plurality of arrays in a direction perpendicular to the conveyance direction (referred to as the width direction of the conveyance path) within the plane in which the paper sheet is conveyed,
The magnetic sensor device according to claim 1, wherein the magnetic flux generation member has a width that is greater than a width of the magnetoelectric conversion element in a width direction of the transport path.

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