JP6359858B2 - Magnetic field detection device and magnetic identification device - Google Patents

Description

  The present invention performs magnetic detection on a printed material of magnetic ink containing a magnetic material such as banknotes or a paper-like medium incorporating a magnetic foil strip, for example, magnetic identification for performing type discrimination or authenticity determination. Regarding technology.

  Conventionally, a magnetic ink printed on a banknote is magnetized by a magnetic field application means such as a magnet in a magnetic sensor, a change in the magnetic field to the surroundings is detected by a magnetic detection element, and a magnetic pattern is recognized, whereby the type of banknote Discrimination and authenticity determination are performed. In such a conventional banknote identification method, the amount by which the output of the magnetic sensor swings in one direction from the base line when collating the optical pattern read from the optical line sensor with the magnetic pattern read from the magnetic sensor. It is desirable to have a typical waveform.

  For example, in Patent Document 1, a magnetic sensor in which one pole of a magnet is applied to a medium to be detected and a magnetic detection element is arranged on a plane passing through the midpoint of the N pole and the S pole and having the NS direction as a normal line. Proposed. The principle of the magnetic substance detection method according to Patent Document 1 is as follows.

  That is, when a magnetic body approaches or comes into contact with one of the magnetic poles of the magnet, the magnetic field from the magnet changes, but the magnetic body detection sensor passes through the midpoint of the N and S poles in a direction perpendicular to the NS direction. Perform magnetic field detection. The reason why the detection surface of the magnetic detection element is placed on a plane passing through the midpoint between the north and south poles is to use a high-sensitivity magnetic detection element that is likely to be magnetically saturated against a magnet having a large magnetic force such as a rare earth magnet. is there.

  As a highly sensitive magnetic detection element, for example, there is a method of driving a magnetic detection element in which a magnetic thin film disclosed in Patent Document 2 and a coil are laminated with a circuit disclosed in Patent Document 3. This magnetic detection element has sensitivity in the longitudinal direction of the magnetic thin film and is suitable for use in a magnetic sensor.

  When the magnetic material is close to the magnetic pole of the magnet, the magnetic flux flow of the magnet changes, and it appears as a magnetic field change even in the environment near the zero magnetic field where the magnetic detection element is placed, and this magnetic field change is converted into an electric signal by the highly sensitive magnetic detection element. Converted.

Japanese Patent No. 4541136 Japanese Patent No. 4695325 Japanese Patent No. 4160330

  However, in recent years, further improvement in bill identification accuracy has been demanded. In a portion where the density of magnetic ink is low, the change in the magnetic field is small, so that identification may be difficult.

  In addition, the demand for increasing the resolution by increasing the number of detection channels in a multi-channel sensor has a problem in that each channel is subdivided and the magnet cannot be enlarged and the generated magnetic field cannot be increased.

  In order to solve these problems, a device for increasing the efficiency of the magnetic field generated by the magnetic medium is required.

  In addition, if there is a variation in sensitivity within the detection range of the sensor, a dead zone is formed.For example, when identifying a thin linear magnetic material, a sensitivity difference occurs depending on the position through which the magnetic material passes, resulting in a detection error. There was a risk that this would occur.

  The various problems described above are merely examples, and in any case, a highly sensitive magnetic field detection device is desired.

  In one embodiment of the present invention, a plurality of magnets are alternately arranged with magnetic poles reversed, and between adjacent magnets, a magnetic field change formed by each adjacent magnet is formed between adjacent magnets. A magnetic field detection device comprising magnetically sensitive elements each receiving a change in magnetic field.

  Here, in one aspect of the present invention, the magnetosensitive element is arranged on a plane including the midpoint of the magnet and the midpoint of the magnet and the NS direction of the magnet as a normal line. It is preferable to use a magnetic field detection device as a feature.

  According to another aspect of the present invention, there is provided a magnetic field detection device that detects a change in a magnetic field of a magnet by the magnetic medium by relatively moving a magnetic medium including a magnetic material, and the magnetic field detection device includes a plurality of magnetic field detection devices. Magnets and a plurality of magnetosensitive elements are alternately arranged on a substantially straight line, and the plurality of magnets have an NS direction substantially perpendicular to a surface of the magnetic medium transported, and The plurality of magnets are arranged at substantially equal intervals in a direction perpendicular to the conveyance direction of the magnetic medium, and the plurality of magnets are arranged so that magnetic poles in contact with the magnetic medium are alternately switched, and the plurality of magnetosensitive elements are The plurality of sensations are arranged in a plane that has a magnetic field detection direction in the substantially linear direction, and has a NS direction of the plurality of magnets as a normal line and includes a substantially midpoint of the N and S poles of the plurality of magnets. Arrange so that the magnetic field detector of the magnetic element is located. Each of the plurality of magnetosensitive elements includes a magnetic field change of the two magnets generated when the magnetic body is close to the magnetic poles of two magnets adjacent to the element, and the magnetic poles of the two magnets. A magnetic field detection device that simultaneously detects a change in the magnetic field of the two magnets due to the magnetization of the magnetic material that occurs when the magnetic material comes close to each other.

According to another aspect of the present invention, there is provided a magnetic identification device having a plurality of channels constituted by the magnetic field detection device, wherein a high-frequency current is applied to a magnetic thin film that is the magnetic field detection unit of the magnetosensitive element. a current applying unit, and the sense of the to voltage acquisition unit eject the voltage of the sensing element by the detection circuit from the coil stacked on the magnetic thin film of the magnetosensitive, an amplifying circuit for amplifying the pre-Symbol voltage, The magnetic identification device includes a multiplexer that switches between the plurality of channels, and an arithmetic unit that performs arithmetic processing by digitizing an output from the multiplexer.

  According to the present invention, highly sensitive magnetic field detection can be realized. As an example, when a plurality of magnets and a magnetosensitive element arranged between the magnets are arranged in a substantially straight line, the magnetic poles of the magnets and the magnets adjacent to each other are arranged. The magnetic field change between the magnetic poles can be detected by each magnetosensitive element, and a large magnetic field change can be detected as compared with the conventional one. In addition, according to the present invention, since it is possible to realize a configuration in which there is almost no dead zone, detection errors are greatly reduced.

1 is an example of a perspective external view of a magnetic field sensor according to a first embodiment of the present invention. It is a figure which shows an example of the enlarged view of the detection surface of the magnetosensitive element (magnetic detection element) in the magnetic field sensor which concerns on the 1st Embodiment of this invention. It is a figure which shows an example of the magnetic field detection characteristic of the magnetosensitive element (magnetic detection element) in the magnetic field sensor which concerns on the 1st Embodiment of this invention. It is a figure explaining the positional relationship of the magnetosensitive element (magnetic detection element) and magnet in the magnetic field sensor which concerns on the 1st Embodiment of this invention. It is a figure explaining the effect by the composition of the magnetic field sensor concerning a 1st embodiment of the present invention. It is a figure explaining the effect by the composition of the magnetic field sensor concerning a 1st embodiment of the present invention. It is a figure explaining the effect by the composition of the magnetic field sensor concerning a 1st embodiment of the present invention. It is a figure which shows an example of the output waveform at the time of performing a magnetic measurement about a banknote with the magnetic field sensor which concerns on the 1st Embodiment of this invention. It is a figure explaining the arrangement | sequence of the magnet of the magnetic sensor which concerns on the 1st Embodiment of this invention, and a magnetic sensing element (magnetic detection element). It is a figure which shows an example of the magnetic sensor which concerns on the 2nd Embodiment of this invention. It is a figure which shows an example of the circuit structure of the multichannel sensor which concerns on the 2nd Embodiment of this invention. It is a figure which shows the structural example at the time of mounting the magnetic sensor which concerns on the 2nd Embodiment of this invention in an automatic teller machine, and implement | achieving a banknote identification device. It is a figure which shows the other usage example of the magnetic sensor which concerns on the 2nd Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, in each figure referred in the following description, in principle, the same part as another figure is shown with the same code | symbol.

(Embodiment 1)
(Configuration of magnetic sensor)
FIG. 1 is a perspective external view showing an example of a magnetic sensor which is an example of a magnetic field detection apparatus according to the present embodiment. FIG. 1 shows a state when the magnetic sensor 10 of the present embodiment identifies the magnetic medium 1.

  As an example, the magnetic medium 1 is a paper-like medium containing a magnetic material. More specifically, for example, the magnetic medium 1 is obtained by printing ink containing a magnetic material on paper like a banknote. The magnetic medium 1 may be one in which a magnetic foil strip is woven. Further, the magnetic material may be a hard magnetic material having a large coercive force and a soft magnetic material having almost no coercive force.

  Here, in the example shown in FIG. 1, the magnetic medium 1 has a magnetic printing unit 2 on which magnetic ink is printed, and the magnetic printing unit 2 has a width w in the medium transport direction (Y direction) indicated by an arrow. It is narrow and has a linear shape extending in a direction perpendicular to the transport direction (X direction).

  For example, in the present embodiment, the magnetic sensor 10 serving as the magnetic field detection device includes a plurality of magnets 3a, 3b, and 3c and magnetic detection elements 5a and 5b that are an example of a plurality of magnetosensitive elements arranged alternately. Has been. Specifically, the magnetic detection element 5a is arranged between the magnets 3a and 3b, the magnetic detection element 5b is arranged between the magnets 3b and 3c, and each is arranged on a substantially straight line. In addition, the magnets 3a, 3b, 3c are arranged so that N poles and S poles are alternately arranged with their magnetic poles reversed. That is, one magnetic field detection module (magnetic field detection device) is substantially constituted by a pair of adjacent magnets 3a and 3b and the magnetic detection element 5a arranged therebetween, and the magnetic field detection modules are linearly arranged. Thus, a band-shaped magnetic field detection region is formed.

  Each of the magnets 3a, 3b, 3c is a Ne-Fe-B or Sm-Co rare earth magnet, an iron oxide ferrite magnet, or the like, and is formed in a rectangular parallelepiped shape.

  Further, the NS direction of the magnets 3a and the like is perpendicular to the medium transport surface (XY plane) and is arranged so as to have a polarity opposite to that of the magnet adjacent to itself. In FIG. 1, as an example, they are arranged in the order of S, N, and S when viewed from the medium conveyance surface. The magnets 3a, 3b, 3c are arranged at a pitch p in the X-axis direction perpendicular to the medium transport direction (Y direction).

  Further, in the magnetic detection elements 5a and 5b in the present embodiment, the respective detection surfaces 6a and 6b pass through substantially the midpoints of the NS poles of the magnets 3a, 3b, and 3c, and the NS direction of the magnet 3a and the like is a normal line. They are arranged so as to be substantially the same as the plane 4 (this point will be described in detail later). In order to share the plane 4 with the three magnets 3a, 3b, 3c, it is preferable that the magnets have the same size and material. If necessary, the magnet position may be finely adjusted individually in the NS direction (Z direction).

  FIG. 2 is a diagram illustrating an example of an enlarged view of the detection surface 6 of the magnetic detection elements 5a and 5b. In addition, the detection surface 6 of the magnetic detection element 5 has an insulation (not shown) composed of a long magnetic thin film 7 having a high magnetic permeability such as permalloy, amorphous, or microcrystalline structure, and a planar coil 8 made of a conductive metal thin film such as copper or aluminum. The films are stacked via a film, and each is led out to the electrode 9.

  The magnetic detection elements 5a and 5b of the present embodiment are orthogonal flux gates. In addition, the magnetic detection element 5 applies a high-frequency current to the magnetic thin film 7 and takes out a change in magnetic flux in the magnetic thin film 7 from the planar coil 8 as a sensor signal converted into a voltage. The magnetic field detection direction is the longitudinal direction of the magnetic thin film 7. In the sensor configuration shown in FIG. 1, the magnetic detection elements 5a and 5b are arranged so that this is in the X-axis direction. The magnetic detection elements 5a and 5b do not require a bias magnetic field and have sensitivity with zero magnetic field, which is suitable for the magnetic sensor 10 of this embodiment.

  FIG. 3 is a diagram illustrating an example of the magnetic field detection characteristics of the magnetic detection elements 5a and 5b. According to the example of FIG. 3, the magnetic detection element 5a and the like of the present example saturate when it exceeds 10 Gauss. Therefore, in this example, it is preferable to operate the sensor near the zero magnetic field. For this purpose, as described above, it is preferable to place the detection surfaces of the magnetic detection elements 5a and 5b on the plane 4 in FIG.

  More specifically, as shown in FIG. 4, a plane 4 that passes through approximately the midpoint of the NS poles of the magnets 3 a, 3 b, 3 c and that has the NS direction as a normal line is a magnetic thin film of the magnetic detection elements 5 a, 5 b. It is more preferable that the magnetic detection elements 5a and 5b are arranged so as to be a plane passing through. Here, the plane 4 is a plane that is ideal for installation of a highly sensitive magnetic sensor that is likely to be saturated, and that ideally has a magnetic field of zero in that plane. However, it is not strictly necessary that the plane 4 includes the midpoint of the NS of the magnet, and it is more preferable to operate the sensor at a position near the magnetic field substantially zero.

  In addition, the variation range of the magnetic field in the plane 4 is preferably within ± 10 gauss when the magnetic detection element of this example is used. Therefore, even if it is assumed that the sensitivity of the magnetic detection element is lowered and the magnetic field detection range is expanded, the variation range of the magnetic field in the plane 4 should be kept within a range of ± 30 gauss. is assumed.

(Operation principle of magnetic sensor)
As described above, in the magnetic sensor according to the present embodiment, the plurality of magnets 3a, 3b, 3c and the magnetic sensors 5a, 5b are arranged between the magnets. With such a configuration, the magnetic sensor according to the present embodiment is configured such that the magnetic field changes when the magnetic material is applied (approached) to the magnetic pole of the magnet and the generation of magnetization when the magnetic material is applied (approached) between the magnets. The point is that two physical phenomena overlap (hybrid phenomenon).

  Hereinafter, the operation principle of the magnetic sensor of this embodiment will be described. As a prior explanation, first, how the magnetic field changes when a magnetic body approaches the two magnets 3p and 3q will be described with reference to FIG. This will be described with reference to FIG.

  5 and 6 are views of the two magnets 3p and 3q arranged in the same manner as the magnetic sensor 10 according to the present embodiment shown in FIG. 1 and the magnetic sensor 5p arranged therebetween as viewed from the Y-axis direction.

  As shown in FIG. 5, the detection position of the magnetic detection element 5p (in this description, this position is referred to as the origin O) is located at a substantially midpoint height of the S and N poles of the magnet 3p.

  Therefore, when the magnetic body 2 ′ is not on the magnetic pole of the magnet 3 p, no magnetic field component is generated in the X-axis direction at the origin O as indicated by the dashed arrow 50. However, when the magnetic body 2 'is applied on the magnetic pole of the magnet 3a, the magnetic flux is pulled toward the magnetic body 2' (solid arrow 51), and a magnetic field in the X-axis direction is generated as a vector component. Similarly, a magnetic field is generated in the X-axis direction according to the same principle even when the magnetic body 2 'is placed on the magnet 3q.

  Here, assuming that the magnetic field in the right direction in FIG. 5 has a positive polarity, both the magnetic field of the magnet 3p and the magnetic field of the magnet 3q are directed rightward. That is, when the magnetic body 2 'is applied on the magnets 3p and 3q, the vector component in the X-axis direction of the magnetic field is in an additive relationship.

  This is due to the fact that in the magnetic sensor 10 of the present embodiment, the adjacent magnets 3a and 3b and the magnets 3b and 3c are arranged so as to have opposite polarities, respectively. If they are arranged so as to have the same polarity, this effect cannot be obtained.

  That is, by arranging a plurality of magnets 3a, 3b, and 3c alternately in reverse with magnetic poles reversed, the magnetic field between the N pole and the S pole in each magnet has a plurality of vector components (magnet side-by-side components, NS component of the magnet). Here, “a plurality of magnets are alternately arranged with their magnetic poles reversed” indicates that the N and S poles are alternately arranged in adjacent magnets.

  And in this embodiment, the magnet which can each receive the magnetic field change each formed by each adjacent magnet 3a, 3b, 3c and the magnetic field change formed between adjacent magnets 3a, 3b or between magnets 3b, 3c, respectively. Magnetic field detection elements 5a and 5b are respectively disposed in the gaps between them. With such a configuration, each of the magnetic field detection elements 5a and 5b can receive a plurality of magnetic field changes. Thereby, a highly sensitive magnetic field detection apparatus can be realized in a compact manner.

  Further, as shown in FIG. 6, when there is no magnetic material between the magnet 3p and the magnet 3q, the magnetic field Hmf on the transport surface side and the magnetic field Hmr on the opposite side to the transport surface are symmetric, and the origin O Then the magnetic field is just zero. When the magnetic body 2 ′ is applied between the S pole of the magnet 3 p and the N pole of the magnet 3 q, the magnetic body 2 ′ is magnetized by the magnetic field Hmf, and a magnetic field due to the magnetization is generated at the origin O. Also in this case, the polarity of the generated magnetic field is positive in the right direction (X-axis direction), and the magnetic field generated in the case where the magnetic body 2 ′ is applied on the magnet 3 p and the magnet 3 q described in FIG. The direction is the same as the vector component. Therefore, when the magnetic body 2 'is simultaneously applied on the magnetic poles of the magnets 3p and 3q and between the two magnets, the vector component in the X-axis direction of the generated magnetic field is substantially in an additive relationship.

  In other words, with the configuration shown in FIG. 1, the magnetic sensor of the present embodiment has two physical properties: a magnetic field change caused by the magnetic material being applied to the magnetic pole of the magnet, and a magnetic field change generated by the magnetic material being applied between the magnets. The hybrid structure is a combination of phenomena.

  In the case where the magnetic printing unit 2 is simultaneously applied to a plurality of magnets as shown in FIG. 1, the maximum effect can be obtained as described below. Hereinafter, a description will be given with reference to FIG.

  FIG. 7 is a diagram illustrating a verification example in the case of a differential configuration in which there are three magnets and two magnetic detection elements, similarly to the configuration of the magnetic sensor according to the present embodiment.

  In this verification example, the magnetic pole of the magnet is mounted with a rare earth (Ne-Fe-B system) magnet having a height of 1.45 mm and a height of 1.45 mm, and a magnetic thin film having a thickness of 2.times.1 mm and a thickness of 0.725 mm as a magnetic detection element. A fluxgate sensor was prepared. And the sensor was comprised by these in the layout similar to FIG. 1 (FIG. 7 (a)). The pitch p between the magnets was 3 mm. The sensitivity of the two magnetic detection elements was adjusted to 1 V / Gauss, and the final output was differentially amplified to 2 V / Gauss.

  As for the medium transport surface, although not shown, a copper alloy thin plate (t = 0.2 mm) was placed on the magnet to regulate the distance from the medium. On the magnetic material, a line 2 ′ having a width of 1 mm is printed on a paper medium with a magnetic toner, and the line 2 ′ is shifted in the X-axis direction while aligning the extending direction of the line 2 ′ with the Y-axis (FIG. 7 ( b)), the sensitivity distribution of the magnetic sensor was examined.

  According to the measurement data shown in FIG. 7A, the sensitivity at five points (A1, C, A2, B1, B2) on the magnetic poles of the magnets 3p, 3q, and 3r and directly above the center of the magnetic detection elements 5p and 5q. It can be seen that no insensitivity band appears in which the sensitivity drops over the whole. The peak at the position C is approximately twice the peak at the positions A1 and A2. The change in the magnetic field at the position C is applied to both the magnetic detection elements 5p and 5q. It is because it has become. Also, the sensitivity of the positions B1 and B2 between the magnets is moderate, and it can be said that the configuration of this example has a good interpolation relationship.

  Next, the output waveform at the time of performing a magnetic measurement about a certain banknote with the magnetic sensor which concerns on this embodiment is shown in FIG. The output result of the differential operation of the magnetic detection elements 5a and 5b was converted into a magnetic field at 2 V / Gauss, and the difference in magnetic field handled between the two elements was taken as the vertical axis. As a result, a maximum magnetic field of 0.25 gauss approaching the magnitude of geomagnetism was secured, and the sensitivity of the magnetic field one digit higher than that of the conventional magnetic sensor could be realized. Also, it can be understood that there is almost no output waveform roughness and that the S / N is good.

(Regarding the arrangement of magnets and magnetic detection elements)
FIG. 9 is a diagram illustrating the arrangement of magnets and magnetic detection elements of the magnetic sensor according to the present embodiment. The magnets 3a, 3b, 3c and the magnetic detection elements 5a, 5b are preferably arranged on a substantially straight line in the X-axis direction. “Substantially on a straight line” means that, as shown in FIG. 9A, the magnetic thin film 7a, 7b is included in a line having a width m in the medium transport direction (Y-axis direction). All the magnetic detection elements 5a and 5b are arranged so as to be aligned on a straight line (straight line l) substantially perpendicular to the transport direction, and the magnetic detection elements are arranged so that these lines are placed on the magnetic poles 3a, 3b and 3c of all the magnets. This means that 5a, 5b and magnetic poles 3a, 3b, 3c of magnets are arranged. Specific examples include FIGS. 9B to 9D.

  Specifically, as shown in FIGS. 9 (b) to 9 (d), each magnet 3a, 3b, 3c, so that at least a part of each magnet 3a, 3b, 3c exists in a substantially linear region. 3c is arranged, and magnetic detection elements 5a and 5b are arranged between the magnets 3a, 3b and 3c.

  That is, the magnets 3a, 3b, and 3c are aligned so as to form a belt-like magnetic field region (region illustrated by the width m) at least partially adjacent to each other, and the magnetic detection elements 5a and 5b are connected to the magnets 3a. , 3b, 3c are arranged between the magnets in the magnetic field region.

  As described above, in the magnetic field detection device according to the present embodiment, the layout of the magnets 3a, 3b, and 3c and the magnetic detection elements (magnetic sensitive elements) 5a and 5b is such that at least a part of the magnetic detection elements includes the magnets. It is the arrangement | positioning (in-line arrangement | positioning) which is each clearance gap and overlaps in a strip | belt-shaped magnetic field area | region. Thereby, highly sensitive magnetic field detection can be realized with a very compact layout.

(Embodiment 2)
FIG. 10A is a diagram showing an example of a magnetic sensor according to the second embodiment of the present invention. The magnetic sensor according to the present embodiment functions as a multi-channel sensor. FIG. 10A shows a configuration example in which the magnetic sensor includes nine magnets 3a to 3i and eight magnetic detection elements 5a to 5h so as to function as a 4-channel sensor.

  The basic configuration of the multichannel sensor according to the present embodiment is the same as the configuration of the magnetic sensor according to the first embodiment described above. That is, the arrangement of the magnets 3a and the like and the magnetic detection elements 5a and the like in the configuration example of FIG. 1 is further extended continuously in the X direction. As viewed from the medium conveying surface side, the same number of magnets as the required number of channels are arranged by alternately switching the S and N poles. Further, the magnetic detection elements adjacent to each other perform differential detection because the magnetic field from the medium is relatively in reverse phase. For example, if there is no problem with mechanical drive motor magnetic field, magnetism from bearings, shafts, etc., correct the point where the polarity is alternately reversed without performing differential detection, It is also possible to increase the number of channels twice.

  FIG. 10B is an example of a cross-sectional view when the magnetic sensor of the present embodiment is cut along a broken line D. The main body 15 is formed of a rigid aluminum die-cast or plastic material, and the electrode 9 of the magnetic detection element 5h is connected to the terminal pin 11 by wire bonding 12, and is pulled out opposite to the medium transport surface. In addition to the wire bonding, soldering may be used. As the sliding plate 13 that regulates between the medium conveying surface and the magnetic pole of the magnet, a thin plate of a nonmagnetic copper alloy such as phosphor bronze or white can be used. If necessary, wear-resistant plating may be applied.

  FIG. 11 is a diagram illustrating an example of a circuit configuration of the multi-channel sensor according to the present embodiment. In the multi-channel sensor of this embodiment, the sensor unit 20 having the configuration shown in FIG. 10A is connected to an oscillation circuit 21 that applies a high-frequency current to the magnetic thin film 7 for the operation of the flux gate. The sensor unit 20 is connected to a detection circuit 22 for extracting an output from the coil 8 (see FIG. 2) of each magnetic detection element constituting the sensor unit 20. After that, the output signal taken out by the detection circuit 22 is transmitted to a microcomputer (CPU) 25 via a differential amplifier circuit 23 and a multiplexer 24 for switching channels, and is converted into a numerical value after AD conversion. Correction processing is performed.

  Here, the predetermined correction processing is to recognize the sensitivity of each of the magnetic detection elements 5a to 5h in an environment where a constant magnetic field is applied by a coil or the like, absorb the sensitivity difference, and adjust the sensitivity to a certain level. is there. By this process, the influence of the external magnetic field can be suppressed as much as possible.

  In the conventional magnetic sensor, when the sensitivity of the sensor is low, the output is greatly increased by the circuit gain, but the impedance fluctuation due to clock noise and vibration in the circuit is amplified, and its influence becomes a problem. There was a case. On the other hand, in the magnetic sensor according to the present embodiment, the circuit gain can be made smaller than that of the conventional one, not only can the influence of the disturbance magnetic field be relatively reduced, but also the noise factor in the circuit can be suppressed.

  FIG. 12 is a diagram illustrating a configuration example when the banknote identification device is realized by mounting the magnetic sensor according to the present embodiment on an automatic teller machine (ATM machine). The banknote identification device 60 of FIG. 12 incorporates the transport mechanism 26 of the banknote 30, and the magnetic sensor 27 of this embodiment shown in FIG. 10 and the optical line sensor 28a, 28b. The banknote identification device 60 collates the sensor output and performs authenticity determination and denomination determination of the banknote 30.

  Furthermore, FIG. 13 is a figure which shows the other usage example of the magnetic sensor which concerns on this embodiment. As shown in FIG. 13, an arm 31 having a magnetic body 32 such as permalloy or magnetic toner attached to the detection surface 6 side of the magnetic sensor 27 of the present embodiment is prepared and moved in the X-axis direction. It is also possible to determine the position. The magnet of the magnetic sensor 27 and the magnetic body 32 can be used with sufficient separation, and the utility value is great also as a non-contact type position detection device.

(Summary)
According to the above-described embodiment of the present invention, a hybrid configuration is employed in which a magnetic field change is detected when a magnetic material is applied to a magnet, and a magnetic field change is detected when a magnetic material is applied between the magnets. As a result, the magnetic field change of the magnetic material can be maximized, and the S / N can be greatly improved as compared with the conventional case. In addition, since these two magnetic detections are in an interpolating relationship, the dead zone as a whole can be substantially eliminated, and even if the magnetic material is minute, detection that is not missed, that is, highly accurate detection is possible. It becomes possible.

  In addition, the magnetic sensor according to the above-described embodiment is likely to be magnetically saturated by being configured such that the detection surface of the magnetic detection element is located in a plane including the midpoint of the NS of the magnet and having the NS direction as a normal line. A highly sensitive magnetic sensor has become available. In addition, the magnetic detection elements adjacent to each other are also suitable for differential operation because the magnetic field change of the magnet is relatively out of phase.

  In the above embodiment, the magnetic detection elements are arranged on a plane including the NS direction of the magnet as a normal line and the midpoint of the magnet NS, but the present invention is not limited to this. For example, as a magnetic detection element (magnetic sensing element), an element having a wide range in addition to the vicinity of the zero magnetic field in the magnetic field detection range is prepared. In this case, when the NS direction of the magnet is normal, except for the plane including the midpoint of the NS of the magnet, the magnetic field change of each adjacent magnet and the magnetic field change between adjacent magnets are received. Therefore, it is possible to detect a magnetic field with high sensitivity.

  Furthermore, the magnetic sensor according to the above-described embodiment is easily applied to a multi-channel sensor because the arrangement of magnets is alternately arranged to be S and N poles when viewed from the medium conveyance surface. It can be used as a line sensor for magnetic detection.

  The embodiments of the present invention have been described so far, but the present invention is not limited to the above-described embodiments, and it goes without saying that the present invention may be implemented in various forms within the scope of the technical idea.

  It should be noted that the scope of the present invention is not limited to the illustrated and described exemplary embodiments, but includes all embodiments that provide the same effects as those intended by the present invention. Further, the scope of the invention is not limited to the combinations of features of the invention defined by the claims, but may be defined by any desired combination of particular features among all the disclosed features. .

DESCRIPTION OF SYMBOLS 1 Magnetic medium 2 Magnetic printing part 4 Plane 3a, 3b, 3c Magnets 5a, 5b Magnetic detection element 6a, 6b Detection surface 7 Magnetic thin film 8 which passes through the middle point of NS poles, such as magnet 3a, and is normal to NS direction Planar coil 9 Electrode 10 Magnetic sensor 20 Magnetic sensor 21 Oscillation circuit 22 Detection circuit 23 Amplification circuit 24 Multiplexer 25 Microcomputer (CPU)
50, 51 magnetic field

Claims (6)

A magnetic field detection device that detects a change in the magnetic field of a plurality of magnets arranged by alternately moving a magnetic medium including a magnetic body and reversing a magnetic pole in a direction orthogonal to the moving direction ,
A magnetic field detecting device is provided between adjacent magnets, each of which is provided with a magnetosensitive element that receives a magnetic field change formed by each adjacent magnet and a magnetic field change formed between adjacent magnets. .   The magnetic field detection device according to claim 1, wherein the magnetosensitive element is arranged on a plane including a midpoint of the N pole and the S pole of the magnet with the NS direction of the magnet as a normal line. The magnetic sensing element includes a magnetic field change generated by the magnetic material and the magnet approaching each other, and an action of the magnetic field formed between the adjacent magnets. 3. The magnetic field detection device according to claim 1, wherein the magnetic field detection device receives a magnetic field change between adjacent magnets generated by the magnetic body that receives and magnetizes the magnetic field.   The magnetic sensitive element has the magnetic sensitive element when the magnetic field detection direction of the magnetic sensitive element is oriented in the orthogonal direction and the magnetic body is not close to the magnetic poles of two magnets adjacent to the magnetic element. A peak appears in the detection output immediately above the center of the magnetic sensing element in the detection output of the magnetic sensing element in the orthogonal direction by being arranged at a position where the detection magnetic field of the magnetic element becomes zero. The magnetic field detection apparatus according to any one of claims 1 to 3. Magnetic media containing the magnetic substance is moved, a magnetic field detecting apparatus for detecting a change in the magnetic field of a plurality of magnets arranged side by side alternately with poles reversed in a direction perpendicular to the moving direction of said magnetic medium,
A plurality of magnets and a plurality of magnetosensitive elements are alternately arranged on a substantially straight line,
The plurality of magnets are arranged substantially equidistantly in a direction perpendicular to the moving direction of the magnetic medium such that the NS direction thereof is substantially perpendicular to a surface moving the magnetic medium. The magnets are arranged so that the magnetic poles in contact with the magnetic medium are alternately switched,
The plurality of magnetosensitive elements are arranged to have a magnetic field detection direction in the substantially linear direction ,
Each of the plurality of magnetosensitive elements includes a magnetic field change of each of the two magnets generated when the magnetic body is close to the magnetic poles of the two magnets adjacent to the element, and the magnetic poles of the two magnets. A magnetic field detecting device for simultaneously detecting a change in magnetic field between the two magnets due to magnetization of the magnetic material, which is generated when the magnetic material is in proximity. A magnetic identification device having a plurality of channels constituted by the magnetic field detection device according to any one of claims 1 to 5,
A current applying unit that applies a high-frequency current to a magnetic thin film that is a magnetic field detecting unit of the magnetosensitive element;
A sensor voltage acquisition unit for extracting a sensor voltage of the magnetosensitive element by a detection circuit from a coil laminated on the magnetic thin film of the magnetosensitive element;
An amplifier circuit for amplifying the sensor voltage;
A multiplexer for switching the plurality of channels;
An arithmetic unit that performs arithmetic processing by digitizing the output from the multiplexer;
A magnetic identification device.

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