JP2016206068A - Magnetic sensor device - Google Patents

Abstract

A magnetic sensor device capable of detecting a magnetic pattern with high accuracy is provided. A magnetic sensor device (5) includes magnetic sensing elements (22A, 22B) arranged facing a medium conveyance path (3) and a facing surface (31) facing the magnetic sensing elements (22A, 22B), and penetrates the facing surface (31). A permanent magnet 30 for applying a direction bias magnetic field to the medium transport path 3, a magnetizing magnet 16 for magnetizing the medium transported in the medium transport direction Y toward the magnetic reading position A by the magnetic sensing elements 22A and 22B, The permanent magnet 30 that applies a bias magnetic field includes a recess 33 that opens at the facing surface 31. Alternatively, a through portion may be provided instead of the concave portion 33. [Selection] Figure 4

Description

  The present invention relates to a magnetic sensor device that reads a magnetic pattern of a medium.

  The magnetic sensor device includes a magnetic field detection unit that detects a change in the magnetic field when the medium passes. The magnetic field detection unit includes a magnetosensitive element such as a magnetoresistive element (MR element) and a magnet that applies a bias magnetic field to a medium passing through a detection region of the magnetosensitive element. The magnetic sensor device reads the magnetic pattern of the medium by performing processing such as collating the detected waveform of the magnetosensitive element with the reference waveform.

  Patent Document 1 discloses a magnetic sensor including two magnetosensitive elements (magnetoresistance elements). With the bias magnetic field applied to the detection area of these two magnetosensitive elements, the detection waveform that eliminates the influence of disturbances and the like is obtained by obtaining the differential component of the outputs of the two magnetosensitive elements when the medium passes. Can be obtained.

JP-A-6-43254

  In order to improve the detection accuracy of the magnetic sensor device, it has been studied to use a highly sensitive magnetosensitive element. FIG. 6 is an explanatory view showing a magnetic field detector of the magnetic sensor of Patent Document 1. FIG. 6 (a) is a cross-sectional view schematically showing the arrangement of the magnetosensitive element and the permanent magnet, and FIG. FIG. 6C shows the resistance value-magnetic flux density characteristic of the magnetosensitive element. As shown in FIG. 6A, the magnet 201 has the south pole facing the medium conveyance path 202, and forms a bias magnetic field in the medium conveyance path 202 in a direction penetrating the facing surface 201 a facing the medium conveyance path 202. To do. Between the facing surface 201a and the medium conveyance path 202, the two magnetosensitive elements 203A and 203B are arranged apart from each other in the medium conveyance direction Y.

  As shown in FIG. 6B, the position at which the highest detection accuracy is obtained in the bias magnetic field by the magnet 201 (that is, the most sensitive position) is the slopes on both sides of the peak of the resistance value-magnetic flux density characteristic. Thus, the positions QA and QB have the largest rate of change in resistance value. In the magnetic sensor of Patent Document 1, magnetic sensitive elements 203A and 203B are arranged at these two points. When the medium 204 passes through the medium conveyance path 202, the magnetic sensitive elements 203A and 203B detect a change in the magnetic field due to the medium 204 with a predetermined time difference.

  In the configuration as shown in FIG. 6A, when a magnetosensitive element having higher sensitivity than in the case of FIG. 6B is used in order to increase detection accuracy, the resistance value-magnetic flux density characteristic is shown in FIG. ) Is a narrow curve as shown in FIG. That is, when the sensitivity of the magnetosensitive element is increased, the position with the highest sensitivity approaches the peak position. Therefore, in order to detect at the position with the high sensitivity, the interval between the magnetosensitive elements must be narrowed. However, when reading the magnetic pattern on the medium from the differential waveforms of the two magnetosensitive elements, the output waveforms of the two magnetosensitive elements will overlap if the element spacing is small relative to the size of the magnetic pattern to be detected. As a result, the differential waveform becomes small, so that the detection accuracy cannot be increased.

  In view of the above, an object of the present invention is to provide a magnetic sensor device that can detect a magnetic pattern with high accuracy.

  In order to solve the above problems, a magnetic sensor device of the present invention includes a plurality of magnetosensitive elements arranged along a medium conveyance path, and an opposing surface at a position facing the magnetosensitive element. And a permanent magnet that forms a bias magnetic field in the medium transport path in a direction penetrating the medium, and a concave portion or a penetrating portion is opened in the facing surface.

  In order to solve the above problems, a magnetic sensor device of the present invention includes a magnetic sensing element disposed along a medium conveyance path, and a first facing surface at a position facing the magnetic sensing element, A first permanent magnet for forming a bias magnetic field in a direction penetrating the first opposing surface in the medium transport path; and a second opposing surface located on the same plane as the first opposing surface, wherein the second opposing surface is A second permanent magnet that forms a bias magnetic field in a penetrating direction in the medium conveyance path, wherein the first permanent magnet and the second permanent magnet include the first opposing surface and the second opposing surface. It is characterized by being arranged with a gap in the direction along

  According to the present invention, a concave portion or a penetrating portion is opened in the surface (opposing surface) of the permanent magnet that faces the magnetosensitive element, or two permanent magnet surfaces (the first opposing surface and the opposing surface) that oppose the magnetosensitive element. By providing a gap opening between the second opposing surfaces), the direction of the bias magnetic field penetrating the surface of the permanent magnet is perpendicular to the medium conveyance direction outside the recess, the penetrating portion, or the region where the gap is opened. Direction. As a result, the resistance value-magnetic flux density characteristic of the magnetosensitive element with respect to the bias magnetic field becomes a curve having two peaks on both sides of the concave portion, the penetrating portion, or the region where the gap is opened. The position where the sensitivity of the magnetosensitive element is good (the position where the resistance value changes greatly with respect to the change of the magnetic flux) exists on both sides of the peak of the resistance value-magnetic flux density characteristic. There is always a position with good sensitivity. In this way, by opening a recess, a penetration, or a gap on the surface of the permanent magnet that faces the magnetosensitive element, a position where the sensitivity of the magnetosensitive element is good can be set outside these open areas. it can. Therefore, the magnetic pattern can be detected with high accuracy.

  In the case where the first permanent magnet and the second permanent magnet are arranged with a gap in the direction along the first opposing surface and the second opposing surface, a recess or a through hole is provided. Two peaks can be given to the resistance value-magnetic flux density characteristics without using a complicated permanent magnet having a portion. Therefore, the processing cost for forming a recessed part and a penetration part in a permanent magnet can be reduced.

  In the present invention, it is desirable that the magnetosensitive element is opposed to the first opposed surface on the outer peripheral side of the concave portion or the through portion. In this way, since the magnetosensitive element can be arranged at a position with high sensitivity, the magnetic pattern can be detected with high accuracy.

  In the present invention, it is desirable that the magnetosensitive element includes a first magnetosensitive element located on one side and a second magnetosensitive element located on the other side of the concave portion or the through portion. If it does in this way, both magnetic sensitive elements can be arrange | positioned in a position with a sufficient sensitivity, without narrowing the arrangement | positioning space | interval of a 1st, 2nd magnetic sensitive element. Therefore, it is possible to avoid the element interval from becoming smaller than the size of the magnetic pattern to be detected, and to avoid the overlapping of the output waveforms of the two magnetosensitive elements. Therefore, it is possible to obtain a detection waveform that eliminates the influence of disturbance and the like using the differential components of the two magnetosensitive elements, and to detect the magnetic pattern with high accuracy.

In the present invention, when the first permanent magnet and the second permanent magnet are arranged with a gap in a direction along the first opposing surface and the second opposing surface, the magnetic sensing It is desirable for the element to face the first facing surface or the second facing surface outside the gap in the width direction. In this way, since the magnetosensitive element can be arranged at a position with high sensitivity, the magnetic pattern can be detected with high accuracy.

  In the present invention, when the first permanent magnet and the second permanent magnet are arranged with a gap in a direction along the first opposing surface and the second opposing surface, the magnetic sensing The element preferably includes a first magnetosensitive element facing the first opposing surface on one side in the width direction of the gap, and a second magnetosensitive element opposing the second opposing surface on the other side. . If it does in this way, both magnetic sensitive elements can be arrange | positioned in a position with a sufficient sensitivity, without narrowing the arrangement | positioning space | interval of a 1st, 2nd magnetic sensitive element. Therefore, it is possible to avoid the element interval from becoming smaller than the size of the magnetic pattern to be detected, and to avoid the overlapping of the output waveforms of the two magnetosensitive elements. Therefore, it is possible to obtain a detection waveform that eliminates the influence of disturbance and the like using the differential components of the two magnetosensitive elements, and to detect the magnetic pattern with high accuracy.

  In the present invention, it is desirable that the first permanent magnet and the second permanent magnet are arranged apart from each other in the medium transport direction. In this way, a change in the magnetic field when the medium passes can be detected with a predetermined time difference. Therefore, it is possible to obtain a detection waveform that eliminates the influence of disturbance and the like using the differential components of the two magnetosensitive elements, and to detect the magnetic pattern with high accuracy.

  In the present invention, when the first permanent magnet and the second permanent magnet are arranged with a gap in a direction along the first facing surface and the second facing surface, It is desirable that a yoke is provided, and the first permanent magnet and the second permanent magnet are positioned via the yoke. If it does in this way, the position of two permanent magnets can be stabilized.

  In the present invention, a plurality of the magnetosensitive elements are arranged in an arrangement direction intersecting the medium conveyance direction, the permanent magnet is a long magnet having the arrangement direction as a longitudinal direction, and the magnetosensitive element is the It is desirable to extend in a range aligned in the arrangement direction. In this way, it is possible to reduce variations in sensitivity due to the position of the magnetic sensitive elements in the direction in which the magnetic sensitive elements are arranged. Therefore, it is possible to avoid variations in the detection accuracy of the magnetic pattern in the arrangement direction of the magnetosensitive elements.

  In the present invention, a plurality of the magnetosensitive elements are arranged in an arrangement direction intersecting the medium conveyance direction, the permanent magnet is a long magnet having the arrangement direction as a longitudinal direction, and the magnetosensitive element is the When extending in a range aligned in the arrangement direction and the concave portion is opened on the facing surface, the concave portion is a range in which the plurality of magnetosensitive elements are arranged in the arrangement direction and the longitudinal direction. It is desirable to extend continuously. If it does in this way, compared with the case where a crevice is formed for every magnetosensitive element, the shape of a permanent magnet can be simplified. Therefore, it is possible to reduce the cost of forming the concave portion in the permanent magnet.

  In the present invention, the magnetosensitive element is preferably a magnetoresistive element.

  According to the present invention, a concave portion or a penetrating portion is opened in the surface (opposing surface) of the permanent magnet that faces the magnetosensitive element, or two permanent magnet surfaces (the first opposing surface and the opposing surface) that oppose the magnetosensitive element. By providing a gap opening between the second opposing surfaces), the shape of the resistance value-magnetic flux density characteristic can be made into a shape having two peaks without increasing the size of the permanent magnet. Therefore, the position where the sensitivity of the magnetosensitive element is good can be set outside the region where the concave portion, the penetrating portion, or the gap opens. Therefore, the magnetic pattern can be detected with high accuracy.

It is explanatory drawing of the magnetic pattern detection apparatus carrying the magnetic sensor apparatus of this invention. It is explanatory drawing of the magnetic sensor apparatus of this invention. It is a perspective view which shows a magnetic field detection part typically. It is explanatory drawing of a magnetic field detection part. It is the top view and sectional drawing which show typically the magnetic field detection part of another form. It is explanatory drawing of the magnetic field detection part with which the conventional magnetic sensor apparatus is provided.

  Hereinafter, a magnetic pattern detection device equipped with a magnetic sensor device to which the present invention is applied will be described with reference to the drawings.

(overall structure)
FIG. 1 is an explanatory diagram of a magnetic pattern detection device equipped with a magnetic sensor device to which the present invention is applied. As shown in FIG. 1, the magnetic pattern detection apparatus 1 includes a medium transport mechanism 4 that transports a sheet-like medium 2 such as banknotes and securities along a medium transport path 3, and magnetic reading on the medium transport path 3. A magnetic sensor device 5 that detects the magnetic pattern of the medium 2 at the position A is included. The three directions XYZ shown in FIG. 1 are orthogonal to each other, the X direction indicates the width direction of the medium transport path 3, the Y direction indicates the medium transport direction, and the Z direction indicates the vertical direction (thickness direction of the medium 2).

  The magnetic sensor device 5 includes a magnetic field detector 8 that applies a bias magnetic field to the medium 2 that passes through the magnetic reading position A and detects a change in the magnetic field when the medium 2 passes. The magnetic field detection unit 8 extends in the X direction in the range through which the medium 2 passes. The magnetic pattern detection device 1 determines the magnetic pattern of the medium 2 by comparing the detection waveform from the magnetic field detection unit 8 with the reference waveform, and determines the authenticity and type of the medium 2.

(Magnetic sensor device)
FIG. 2 is an explanatory view of the magnetic sensor device of the present invention, FIG. 2 (a) is a perspective view of the magnetic sensor device 5, and FIG. 2 (b) is a schematic sectional view of the magnetic sensor device 5. As shown in FIG. 2A, the magnetic sensor device 5 includes a frame 10 on which the magnetic field detection unit 8 is mounted and a cover plate 11 attached to the upper end portion of the frame 10. The frame 10 is made of a nonmagnetic material such as resin. The cover plate 11 is formed of a nonmagnetic material such as stainless steel. The surface (upper surface) of the cover plate 11 is a medium conveyance surface 11 a that constitutes the medium conveyance path 3. Since the cover plate 11 is formed with slopes along both edges in the medium transport direction Y, the medium 2 transported in the first direction Y1 or the second direction Y2 and passing through the magnetic reading position A is not easily caught. There is an advantage.

  3 and 4 are explanatory views of the magnetic field detector 8, and FIG. 3 is a perspective view schematically showing the magnetic field detector. 4A is a schematic sectional view of the magnetic field detector 8 (BB sectional view of FIG. 3), and FIG. 4B is a resistance value-magnetic flux density characteristic of the magnetosensitive element. As shown in FIGS. 2A and 3, the magnetic field detection unit 8 includes a plurality of magnetosensitive element units 20 arranged at positions along the medium conveyance path 3 and a magnetosensitive element as viewed from the medium conveyance path 3. A permanent magnet 30 is provided on the back side of the unit 20. A plurality of magnetosensitive element units 20 are arranged in a direction (width direction X) orthogonal to the medium transport direction Y. Each magnetosensitive element unit 20 includes a substrate 21 and two magnetosensitive elements 22A and 22B mounted on the substrate 21.

  In this embodiment, the two magnetosensitive elements 22A and 22B are magnetoresistive elements. The magnetic sensitive elements 22A and 22B are arranged at positions separated by a predetermined dimension in the medium transport direction Y, and overlap when viewed in the medium transport direction Y. As the magnetosensitive elements 22A and 22B, for example, an AMR element (an anisotropic magnetoresistive element (an anisotropic magnetoresistive element formed with a magnetoresistive pattern made of a thin film ferromagnetic metal)) mounted on the substrate 21 is used. Can do. Alternatively, a semiconductor magnetoresistive element, Hall element, MI element (Magneto-Impedance element), fluxgate type magnetic sensor, or the like may be used.

  The permanent magnet 30 is a long magnet that is long in the direction (width direction X) orthogonal to the medium transport direction Y, and is located on the opposite side of the medium transport path 3 with respect to the magnetosensitive element unit 20 (FIG. 2 ( b)). The permanent magnet 30 extends over the entire range in which the plurality of magnetosensitive element units 20 are arranged. The permanent magnet 30 is a permanent magnet such as a ferrite or neodymium magnet. The permanent magnet 30 includes a facing surface 31 facing the side where the magnetic sensing elements 22 </ b> A and 22 </ b> B are located, and a counter-facing surface 32 located on the opposite side of the facing surface 31. The facing surface 31 is formed at a position facing the magnetosensitive elements 22A and 22B. In the present invention, “facing” means that another member (for example, a member arranged between the substrate and the substrate and the permanent magnet) is interposed, or a medium conveyance path is interposed therebetween. Including. As shown in FIG. 4B, the permanent magnet 30 is magnetized so that the direction in which the S and N poles face each other and the medium transport direction Y are orthogonal to each other, and the S pole is on the medium transport path 3 side. To position. Therefore, the permanent magnet 30 forms a bias magnetic field in the medium conveyance path 3 in a direction penetrating the facing surface 31.

  The permanent magnet 30 includes a recess 33 that is recessed in a direction from the facing surface 31 toward the non-facing surface 32. The recess 33 opens at a substantially center of the facing surface 31 in the medium transport direction Y, and extends linearly in the width direction X with a constant width and a constant depth. The range in which the recess 33 extends is a range in which a plurality of magnetosensitive element units 20 are arranged. In this embodiment, the recess 33 extends in a range from one end to the other end in the width direction X of the facing surface 31. The two magnetic sensing elements 22 </ b> A and 22 </ b> B of the magnetic sensing element unit 20 face the facing surface 31 on the outer peripheral side of the recess 33. Specifically, the magnetosensitive elements 22A and 22B are opposed to the facing surface 31 on both sides in the medium transport direction Y with the recess 33 interposed therebetween.

  As shown in FIG. 4A, the bias magnetic field generated by the permanent magnet 30 is perpendicular to the medium transport direction Y on the outer peripheral side of the recess 33. The direction of the magnetic lines of force at each position along the medium transport direction Y is as shown in FIG. 4A, with the position perpendicular to the medium transport direction Y on the outer peripheral side of the recess 33 as the boundary. The inner side is inclined inward toward the center of the recess 33 and the outer side is inclined outward. As a result, the resistance value-magnetic flux density characteristic of the magnetosensitive element with respect to the bias magnetic field by the permanent magnet 30 is a curve having two peaks as shown in FIG.

  As shown in FIG. 4B, the positions PA and PB where the resistance value changes greatly with respect to the change in magnetic flux density in the resistance value-magnetic flux density characteristics of the magnetosensitive element are located on the slopes outside the two peaks. The magnetosensitive elements 22A and 22B are arranged at these two points. The positions PA and PB are located on both sides of the medium transport direction Y with the recess 33 interposed therebetween. Since there is a position where the change in the resistance value is large with respect to the change in the magnetic flux density inside the two peaks, it is possible to arrange the magnetosensitive elements 22A and 22B at that position, but at that position, The element interval between the two magnetosensitive elements 22A and 22B becomes narrow. Therefore, in this embodiment, the magnetosensitive elements 22A and 22B are arranged at positions PA and PB outside the two peaks. Since the positions PA and PB are located outside the opening edges 33a and 33b of the recess 33, the magnetosensitive elements 22A and 22B are arranged outside the opening edges 33a and 33b.

  The magnetic pattern detection operation by the magnetic pattern detection device 1 is performed as follows. In the magnetic pattern detection device 1 shown in FIG. 1, the medium 2 is transported along the medium transport path 3 in the first direction Y1 or the second direction Y2. The medium 2 passes through the magnetic reading position A by the magnetic field detector 8.

  In the magnetic field detector 8, as shown in FIG. 4B, the magnetosensitive elements 22 </ b> A and 22 </ b> B are arranged at two locations that are spaced apart from each other by a predetermined distance in the medium transport direction Y with the recess 33 interposed therebetween. A bias magnetic field by the permanent magnet 30 is formed in the detection areas of the magnetic sensitive elements 22A and 22B. When the medium 2 passes through the magnetic reading position A, signals corresponding to changes in the magnetic field are output from the magnetosensitive elements 22A and 22B with a predetermined time difference. A differential waveform is obtained from the output waveforms of the magnetosensitive elements 22A and 22B, and the differential waveform is collated with a reference waveform stored and held in advance. Thereby, the magnetic pattern of the medium 2 is discriminated, the authenticity of the medium 2 is determined, the type of the medium 2 is discriminated, and the like.

(Function and effect)
As described above, in this embodiment, the concave portion 33 opened at the facing surface 31 is formed in the permanent magnet 30 that forms the bias magnetic field, and the resistance value-magnetic flux density characteristic of the magnetosensitive element has two peaks. Yes. Since the positions of the two peaks are on the outer peripheral side of the recess 33, specifically, outside the opening edges 33a and 33b, the sensitive positions PA and PB existing on the slopes outside the two peaks are The interval is at least larger than the width of the recess 33. That is, by forming the recesses 33 on the facing surface 31, the magnetosensitive elements 22 </ b> A and 22 </ b> B can be arranged at an element interval that is at least larger than the width of the recesses 33. Thus, the sensing operation is performed by arranging the magnetosensitive elements 22A and 22B at positions with high sensitivity without increasing the outer shape of the permanent magnet 30 and without narrowing the element spacing of the magnetosensitive elements 22A and 22B. be able to.

  As described above, by opening the recess 33 in the facing surface 31 of the permanent magnet 30, the peak position of the resistance value-magnetic flux density characteristic can be moved to a position corresponding to the position of the recess 33. Therefore, without changing the shape of the facing surface 31 of the permanent magnet 30 or the depth dimension of the permanent magnet 30 (thickness in the direction perpendicular to the facing surface 31), the sensitive position of the magnetosensitive element can be changed to various elements. Can be set at intervals. Therefore, the arrangement of the magnetosensitive element and the shape of the permanent magnet 30 are less limited than those of the prior art while the magnetic pattern can be detected with high accuracy.

  When the interval between the two magnetosensitive elements 22A and 22B has to be narrowed, the time lag of these detected waveforms is reduced and approaches the same waveform, so the outputs of the two detected waveforms are canceled and the differential waveforms The output becomes smaller. In this embodiment, even when the sensitive magnetic elements 22A and 22B are used, it is not necessary to narrow the element interval. Therefore, it can be avoided that the detection waveforms of the magnetic sensitive elements 22A and 22B are greatly overlapped and the detection accuracy is lowered. In the magnetic patterns of various banknotes used all over the world, there is an optimum element spacing for detection. However, if the magnetic sensor device 5 of this embodiment is used, the magnetic pattern can be changed without changing the optimum element spacing. It is possible to improve detection accuracy.

  Further, in the magnetic sensor device 5, when highly sensitive elements are used as the magnetosensitive elements 22A and 22B, as shown in the description of the prior art (see FIG. 6C), the optimum operating point (the most sensitive) is obtained. In order to measure at a good position, it is necessary to weaken the bias magnetic field. However, if the bias magnetic field is weakened so that it can be detected at the optimum operating point, the bias magnetic field cannot be applied with a strength higher than the saturation magnetic flux density of the medium 2, and as a result, depending on the magnetization state of the medium 2 before measurement. The outputs of the magnetic sensitive elements 22A and 22B change, and the magnetic pattern cannot be detected with high accuracy. However, by having two peaks in the resistance value-magnetic flux density characteristics as in this embodiment, even when using highly sensitive magnetosensitive elements 22A, 22B, it is possible to match the optimum operating point, and It is possible to provide a bias magnetic field having a strength higher than the saturation magnetic flux density of the medium 2. Therefore, it is possible to avoid variations in detection accuracy due to the magnetized state of the medium 2 before measurement.

In addition, the magnetic sensor device 5 of this embodiment includes a magnetic field detector 8 in which a plurality of magnetosensitive element units 20 are arranged in a direction intersecting the medium transport direction Y (width direction X of the medium transport path 3). The magnet 30 is a long magnet that extends over the entire region where the plurality of magnetosensitive element units 20 are arranged. When such an integrated permanent magnet 30 is used, there is less variation in the bias magnetic field in the direction in which the magnetosensitive element units 20 are arranged, compared to a configuration in which the magnet is divided for each magnetosensitive element unit 20. Accordingly, there is little variation in sensitivity depending on the position of the magnetic sensing elements 22A / 22B in the direction in which the magnetic sensing element units 20 are arranged (in this embodiment, the width direction X). Therefore, variations in the detection accuracy of the magnetic pattern in the direction in which the magnetic sensitive elements 22A / 22B are arranged can be reduced. Furthermore, in this embodiment, one continuous groove-shaped recess 33 is formed on the opposing surface 31 in the range where the plurality of magnetosensitive element units 20 are arranged. Therefore, the shape of the permanent magnet 30 is simpler than forming the recess 33 for each magnetosensitive element unit 20.

(Modification)
(1) In the above embodiment, the two magnetosensitive elements 22A and 22B are arranged at positions distant from each other in the medium transport direction Y and the differential waveform is obtained. However, the present invention provides two magnetosensitive elements 22A. , 22B can be arranged at positions separated in the width direction X of the medium conveyance path 3 and applied to a configuration in which the magnetic pattern is discriminated from the differential waveform.

(2) In the above configuration, the permanent magnet 30 and the magnetic sensitive elements 22A and 22B are positioned on the same side with respect to the medium conveying path 3 (that is, the permanent magnet 30 conveys the medium to the magnetic sensitive elements 22A and 22B). In the present invention, the permanent magnet 30 and the magnetosensitive elements 22A and 22B are arranged separately on both sides of the medium conveyance path 3 in the present invention. The present invention can also be applied to a configuration (that is, a configuration in which the permanent magnet 30 includes the facing surface 31 disposed on the same side as the medium conveyance path 3 with respect to the magnetic sensitive elements 22A and 22B).

(3) Although the said form forms the groove-shaped recessed part 33 extended continuously from one edge of the opposing surface 31 to the other edge, the recessed part 33 is extended in this one part area | region. It may be a thing. For example, the recess 33 may be divided in the width direction X. For example, one recess 33 is formed at a position corresponding to each of the plurality of magnetosensitive element units 20. In this case, the opening shape of the recess 33 in the facing surface 31 can be various shapes such as a rectangle, a circle, and an oval. In this case, the length of the recess 33 in the width direction X may be shorter than the magnetic sensitive elements 22A and 22B, but is preferably longer than the magnetic sensitive elements 22A and 22B. Further, the depth of the concave portion 33 may not be constant, and the inner peripheral wall of the concave portion 33 is not limited to a plane perpendicular to the facing surface 31.

(4) Although the said form was the structure which has two peaks in resistance value-magnetic-flux-density characteristic by forming the recessed part 33 opened by the opposing surface 31 of the permanent magnet 30, it is not the recessed part 33 but an opposing surface. You may form the penetration part which penetrates the permanent magnet 30 in the direction which goes to the anti-opposing surface 32 from 31. FIG. The penetrating portion may be formed at a position corresponding to each of the plurality of magnetosensitive element units 20, or may extend continuously in a range in which the plurality of magnetosensitive element units 20 are arranged. Since such a penetrating portion opens at the opposing surface 31, it is possible to have two peaks in the resistance value-magnetic flux density characteristics on the outer peripheral side of the penetrating portion, as in the case where the concave portion 33 is formed.

(5) Although the said form has arrange | positioned the board | substrate 21 away from the opposing surface 31 of the permanent magnet 30, you may install the board | substrate 21 in the position mounted on the opposing surface 31. FIG. Alternatively, another member may be interposed between the substrate 21 and the facing surface 31.

(6) Although the said form uses the elongate magnet extended in the range in which the several magnetosensitive element unit 20 is located in line as the permanent magnet 30, you may arrange a some permanent magnet in the width direction X. . In this case, each of the plurality of permanent magnets has a facing surface facing a corresponding one of the plurality of magnetosensitive element units, and a concave portion or a penetrating portion may be formed on each facing surface. .

(Other embodiments)
In order to have two peaks in the resistance value-magnetic flux density characteristic, the magnetic field detection unit 108 having the form shown in FIG. 5 may be used. FIG. 5 is an explanatory diagram of a magnetic field detection unit 108 according to a modification. FIG. 5A is a schematic plan view of the magnetic field detection unit 108 viewed from the medium conveyance path 3 side, and FIG. 2 is a schematic cross-sectional view of a detection unit 108. FIG. Hereinafter, the same configurations as those in the above embodiment will be described using the same reference numerals, and only different portions will be denoted by different reference numerals.

The magnetic field detection unit 108 includes a rectangular parallelepiped first permanent magnet 130A and a second permanent magnet 130.
B, a yoke 140, and a magnetosensitive element unit 20 are provided. The first permanent magnet 130A and the second permanent magnet 130B are aligned in the medium transport direction Y, and are magnetized so that adjacent end portions have the same pole. The first permanent magnet 130 </ b> A includes a first facing surface 131 </ b> A that faces the magnetic sensing element unit 20, and the second permanent magnet 130 </ b> B includes a second facing surface 131 </ b> B that faces the magnetic sensing element unit 20. Yes. The first facing surface 131A and the second facing surface 131B are located on the same surface. The first facing surface 131A and the second facing surface 131B are located on the opposite side of the medium conveyance path 3 with respect to the magnetosensitive element unit 20. The first permanent magnet 130A and the second permanent magnet 130B are magnetized so as to form a bias magnetic field in the medium conveyance path 3 in a direction penetrating the first opposing surface 131A and the second opposing surface 131B.

  The first permanent magnet 130A and the second permanent magnet 130B are arranged with a gap 133 in the direction along the first facing surface 131A and the second facing surface 131B (that is, the medium transport direction Y). More specifically, a gap 133 extending in the width direction X is formed between the first permanent magnet 130 </ b> A and the second permanent magnet 130 </ b> B, and the yoke 140 is disposed in the gap 133. The first permanent magnet 130 </ b> A and the second permanent magnet 130 </ b> B are fixed to one surface and the other surface of the yoke 140, respectively, and are positioned with respect to each other via the yoke 140. The yoke 140 includes an end surface 141 that faces the magnetosensitive element unit 20, and the end surface 141 is located with respect to the magnetosensitive element unit 20 so as to recede from the first opposing surface 131 </ b> A and the second opposing surface 131 </ b> B. That is, a groove-shaped recess defined by the gap 133 and the yoke 140 is formed between the first permanent magnet 130A and the second permanent magnet 130B.

  The two magnetosensitive elements 22A and 22B included in the magnetosensitive element unit 20 are located outside the gap 133 in the width direction, and are arranged away from each other in the medium transport direction Y. The magnetosensitive element 22A located on one side in the width direction of the gap 133 faces the first opposing surface 131A, and the magnetosensitive element 22B located on the other side in the width direction of the gap 133 faces 131B.

  According to such a configuration, similarly to the above embodiment, the gap 133 can be sandwiched, and two peaks can be given to the resistance value-magnetic flux density characteristics on both sides thereof. Therefore, the two magnetosensitive elements 22A and 22B can be arranged at positions with good sensitivity on both sides of the gap 133, respectively, and the same effect as the above embodiment can be obtained. In addition, since both the first permanent magnet 130A and the second permanent magnet 130B are rectangular parallelepiped, there is no processing cost such as forming a concave portion or a penetrating portion in the magnet. In addition, by using the yoke 140, a magnetic path can be formed, and two magnets in which magnetic poles having the same polarity repel each other can be positioned. Therefore, the positions of the first permanent magnet 130A and the second permanent magnet 130B can be stabilized.

  In this embodiment, another spacer may be used instead of the yoke 140. Further, the first permanent magnet 130 </ b> A and the second permanent magnet 130 </ b> B may be positioned using other positioning means without placing an object in the gap 133.

  Further, the first permanent magnet 130 </ b> A and the second permanent magnet 130 </ b> B do not have to be located on the same side as the magnetic sensitive elements 22 </ b> A and 22 </ b> B with respect to the medium conveyance path 3, and are sensitive to the medium conveyance path 3. It may be located on the opposite side to the magnetic elements 22A and 22B.

DESCRIPTION OF SYMBOLS 1 ... Magnetic pattern detection apparatus 2 ... Medium 3 ... Medium conveyance path 4 ... Medium conveyance mechanism 5 ... Magnetic sensor apparatus 8 ... Magnetic field detection part 10 ... Frame 11 ... Cover board 11a ... Medium conveyance surface 20 ... Magnetosensitive element unit 21 ... Substrate 22A, 22B ... Magnetosensitive element 30 ... Permanent magnet 31 ... Opposing surface 32 ... Anti-opposing surface 33 ... Concave portion 33a-33d ... Opening edge 108 ... Magnetic field detector 130A ... First permanent magnet 130B ... Second permanent magnet 131A ... First opposing surface 131B ... second opposing surface 133 ... gap 140 ... yoke 141 ... end surface 201 ... magnet 201a ... opposing surface 202 ... media transport path 203A, 103B ... magnetic element 204 ... media A ... magnetic reading position X ... width direction Y: Medium transport direction Y1: First direction Y2: Second direction Z: Vertical direction

Claims (11)

A plurality of magnetosensitive elements disposed along the medium conveyance path;
A permanent magnet having a facing surface at a position facing the magnetosensitive element, and forming a bias magnetic field in a direction penetrating the facing surface in the medium transport path,
A magnetic sensor device, wherein a concave portion or a penetrating portion is opened in the facing surface.   The magnetic sensor device according to claim 1, wherein the magnetosensitive element faces the facing surface on an outer peripheral side of the concave portion or the through portion.   The magnetic sensing element comprises a first magnetic sensing element located on one side and a second magnetic sensing element located on the other side across the concave portion or the penetration portion. 2. The magnetic sensor device according to 2. A magnetic sensitive element disposed along the medium conveyance path;
A first permanent magnet provided with a first facing surface at a position facing the magnetic sensing element, and forming a bias magnetic field in a direction penetrating the first facing surface in the medium transport path;
A second permanent magnet having a second opposing surface located on the same plane as the first opposing surface, and forming a bias magnetic field in a direction penetrating the second opposing surface in the medium conveyance path,
The magnetic sensor device, wherein the first permanent magnet and the second permanent magnet are arranged with a gap in a direction along the first opposing surface and the second opposing surface.   5. The magnetic sensor device according to claim 4, wherein the magnetosensitive element faces the first opposing surface or the second opposing surface outside in the width direction of the gap.   The magnetosensitive element includes a first magnetosensitive element facing the first opposing surface on one side in the width direction of the gap, and a second magnetosensitive element opposing the second opposing surface on the other side. The magnetic sensor device according to claim 4, wherein the magnetic sensor device is a magnetic sensor device.   The magnetic sensor device according to any one of claims 4 to 6, wherein the first permanent magnet and the second permanent magnet are arranged apart from each other in the medium transport direction.   The yoke according to any one of claims 4 to 7, further comprising a yoke disposed in the gap, wherein the first permanent magnet and the second permanent magnet are positioned via the yoke. Magnetic sensor device. A plurality of the magnetic sensing elements are arranged in an arrangement direction intersecting the medium conveyance direction,
9. The permanent magnet according to claim 1, wherein the permanent magnet is a long magnet having the arrangement direction as a longitudinal direction, and the magnetosensitive elements extend in a range aligned in the arrangement direction. The magnetic sensor device according to 1. A plurality of the magnetic sensing elements are arranged in an arrangement direction intersecting the medium conveyance direction,
The permanent magnet is a long magnet whose longitudinal direction is the arrangement direction, and the magnetosensitive elements extend in a range aligned in the arrangement direction,
The concave portion is open on the facing surface,
4. The magnetic sensor device according to claim 1, wherein the recess extends continuously in the longitudinal direction within a range in which the plurality of magnetosensitive elements are arranged in the arrangement direction. 5. .   The magnetic sensor device according to claim 1, wherein the magnetosensitive element is a magnetoresistive element.

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