MAGNETIC SENSOR DEVICE

Abstract

Magnetic sensor device comprising: a magnet (1, 2, 2a, 2b, 3) extending in a longitudinal direction orthogonal to a conveying direction (10) of a measuring object (6) with a magnetic material, wherein the magnet (1, 2, 2a, 2b, 3) has magnetic poles that are different in a direction perpendicular to the conveying direction (10); and anisotropic magnetoresistive elements (51, 52) arranged linearly in the longitudinal direction on a measuring-object-side magnetic pole of the magnet (1, 2, 2a, 2b, 3), wherein the length of the magnet (1, 2, 2a, 2b, 3) in the direction perpendicular to the conveying direction (10) is longer for an end region in the longitudinal direction than for a central region in the longitudinal direction.

Description

Technical FieldThe present invention relates to a magnetic sensor device for detecting a fine magnetic pattern formed on a paper sheet-like medium such as paper money and the like.Relevant Prior ArtA magnetic sensor device is a sensor device using a plurality of magnetoresistive elements whose resistance value characteristics change with a change in magnetic flux density. In a magnetic sensor device for simultaneous multi-channel detection of a magnetic pattern contained in a paper sheet-like medium such as paper money and the like, the amount of magnetization of the magnetic pattern is small.Therefore, in order to be able to detect the magnetic pattern with a good sensitivity, anisotropic magnetoresistive elements having a higher sensitivity than semiconductor magnetoresistive elements are used in a magnetic environment in which each of the plurality of anisotropic magnetoresistive elements is highly sensitive without magnetic saturation, and a paper sheet-like medium such as paper money and the like is required to pass through the highly magnetic environment.The scanning direction of the anisotropic magnetoresistive element is the short-side direction, and reading of magnetic ink is achieved by applying a bias magnetic flux density that increases sensitivity most in the detection direction. A magnetic sensor device using an anisotropic magnetoresistive element is disclosed in Japanese Unexamined Patent Application Publication JP 2012-255 770 A (Patent Literature 1).Prior Art ListPatent LiteraturePatent Literature 1: Japanese Unexamined Patent Application Publication JP 2012-255 770 A.DESCRIPTION OF THE INVENTIONTechnical ProblemHowever, the magnetic sensor device described in Patent Literature 1 ideally has a structure that does not apply the magnetic flux in the non-magnetic sensitive direction (longitudinal direction) of the anisotropic magnetoresistive element, and therefore the magnetic vector is directed only in the detection direction (short-side direction). However, since the length of the magnet is limited in an actual product, the magnetic flux is applied along the longitudinal direction of the magnet in each of the directions outward from the magnet center, and the magnetic flux density is also applied in the non-magnetic sensitive direction (longitudinal direction) of the anisotropic magnetoresistive element.The application of the magnetic flux density in the non-magnetic sensitive direction (longitudinal direction) occurs due to various factors such as variations in the magnetic force of the magnet, variations in the shape of the magnet or the magnetic material, variations in manufacturing, and the like.Due to these factors, the anisotropic magnetoresistive element has a magnetic vector inclined toward the magnetic flux density applied in the non-magnetic sensitive direction (longitudinal direction). However, the non-magnetic direction (longitudinal direction) may change (turn over) depending on the mounting position.In a case where a magnetic pattern inclined in a planar direction is read, a problem arises because the location where the anisotropic magnetoresistive element is attached changes the magnitude of the output due to the relationship between the direction of the non-magnetic sensitive direction (longitudinal direction) of the magnetic vector of the anisotropic magnetoresistive element and the non-magnetic sensitive direction (longitudinal direction) of the magnetic vector generated by the magnetic pattern.The present invention has been developed to solve the above problem. It has an object to uniformize the directions of the bias magnetic flux density applied in the non-magnetic sensitive direction (longitudinal direction) of the anisotropic magnetoresistive element. In addition, it has an object to provide a magnetic sensor device capable of obtaining a stable output of each of the linearly-mounted anisotropic magnetoresistive elements without the magnetic sensor device being affected by the shape of the magnetic pattern.Solution of the ProblemThe magnetic sensor device of the present invention includes: a magnet extending in a longitudinal direction orthogonal to a conveyance direction of a magnetic material measurement object, the magnet having magnetic poles different in a direction perpendicular to the conveyance direction; and anisotropic magnetoresistive elements linearly arranged in the longitudinal direction on a magnetic pole side of the magnet facing toward the measurement object, the length of the magnet in the direction perpendicular to the conveyance direction being longer for an end portion in the longitudinal direction than for a central portion in the longitudinal direction.Advantageous Effect of the InventionAccording to the present invention, an end portion of a magnet in the longitudinal direction has a length in a direction perpendicular to a conveying direction that is greater than a length of the magnet in the direction perpendicular to the conveying direction in the longitudinal direction of a central portion. Therefore, it becomes possible to apply a high bias magnetic flux density in the same direction as the non-magnetic sensitive direction (longitudinal direction) of each of the anisotropic magnetoresistive elements arranged and mounted linearly. This enables stable output of the plurality of anisotropic magnetoresistive elements at the same level even when the magnetic pattern is inclined in the planar direction.Brief Description of the DrawingsIn the drawings, there are shown: FIG. 1 is a side view of a longitudinal direction of a magnetic sensor device according to Embodiment 1 of the invention; FIG. 2 is a plan view of the magnetic sensor device from above according to Embodiment 1; FIG. 3 is a diagram showing the distribution of magnetic field lines of the magnetic sensor device according to Embodiment 1 of the invention, as viewed in the X-Z plane; FIGS. 4 ato 4 c show an illustration of the magnetic line vector for describing the detection principles of the magnetic sensor device; FIG. 5 is a diagram showing the distribution of magnetic field lines as shown in FIG. 1; FIG. 6 shows an illustration of the magnetic sensor according to FIG. 1 after removal of a second magnet 2; FIG. 7 is a graph of a by-component applied to the anisotropic magnetoresistive elements of FIG. 6 ; FIG. 8 is a cross-sectional view of the configuration of FIG. 6 as viewed from above and showing the bias flux vectors applied to each anisotropic magnetoresistive element; FIG. 9 is an output diagram of each of the anisotropic magnetoresistive elements of FIG. 8; FIG. 10 is a diagram showing the magnetic flux detection vectors for the configuration of FIG. 6 when the magnetic ink is conveyed in the X-Y plane rotated counterclockwise; FIG. 11 is an output diagram of each of the anisotropic magnetoresistive elements of FIG. 10; FIG. 12 is a graph showing the by component applied to the anisotropic magnetoresistive elements according to Embodiment 1 of this invention; FIG. 13 is a diagram showing the bias flux vectors and the magnetic flux detection vectors according to Embodiment 1 of this invention when magnetic ink is conveyed perpendicular to the Y direction; FIG. 14 is a diagram showing vectors for magnetic flux detection according to Embodiment 1 of this invention when magnetic ink is conveyed in the X-Y plane rotated counterclockwise; FIG. 15 is a plan view of the magnetic sensor device of FIG. 2 viewed from above using T-shaped bridges in bridge-method type anisotropic magnetoresistive elements; FIG. 16 is a side view of a longitudinal direction of the magnetic sensor device according to Embodiment 2 of the invention; FIG. 17 is a top plan view of the magnetic sensor device according to Embodiment 3 of the invention; FIG. 18 is a top plan view of the magnetic sensor device according to Embodiment 4 of the invention; FIG. 19 is a side view of a longitudinal direction of the magnetic sensor device according to Embodiment 5 of the invention; FIG. 20 is a side view of a longitudinal direction of the magnetic sensor device according to Embodiment 6 of the invention; FIG. 21 is a graph showing the by component applied to the anisotropic magnetoresistive elements according to Embodiment 6 of the invention; FIG. 22 is a graph showing the by component applied to the anisotropic magnetoresistive elements according to Embodiment 6 of the invention; FIG. 23 is a longitudinal direction side view of a magnetic sensor device according to Embodiment 7 of the invention; FIG. 24 is a diagram showing the distribution of magnetic field lines of the magnetic sensor device according to Embodiment 7 of the invention, as viewed in the X-Z plane; and FIG. 25 is a side view of a longitudinal direction of another magnetic sensor device according to Embodiment 7 of the invention.DESCRIPTION OF THE EMBODIMENTSEmbodiment 1In all the embodiments of the invention including Embodiment 1, the conveyance direction of a measurement object, that is, the short-side direction of the magnetic device is set as an X direction. The longitudinal direction of the magnetic sensor device (the linear direction) perpendicular to the conveyance direction of the measurement object is set as a Y direction. The direction (direction perpendicular to the conveyance direction) perpendicular to the short side direction (conveyance direction) and perpendicular to the longitudinal direction (linear direction) of the magnetic sensor device is set as a Z direction.FIG. 1 is a longitudinal direction side view of the magnetic sensor device according to Embodiment 1 of the invention. FIG. 2 is a plan view (viewed from above) of the magnetic sensor device according to Embodiment 1 of the invention. In FIGS. 1 and 2, the magnetic sensor device includes:a first magnet 1 extending in the longitudinal direction, having magnetic poles located in mutually opposite directions perpendicular to a conveyance direction 10 of a magnetic material measurement object 6, and having a length in the direction perpendicular to the conveyance direction 10 remaining the same along the longitudinal direction;a chip 5 having anisotropic magnetoresistive (AMR) elements, comprising anisotropic magnetoresistive (AMR) elements 51 linearly arranged in the longitudinal direction and offset at predetermined positions in the conveying direction 10, from the central portion in the conveying direction 10 of the first magnet 1; anda second magnet 2 arranged as a small magnet at an end portion in the longitudinal direction of the first magnet 1 in the direction orthogonal to the conveyance direction 10, wherein the second magnet 2 has magnetic poles located in mutually opposite directions perpendicular to the conveyance direction 10, and wherein the magnetic pole of the side contacting the first magnet 1 is different from the magnetic pole of the first magnet 1.In FIGS. 1 and 2, the chip 5 having anisotropic magnetoresistive (AMR) elements is arranged on the side of the first magnet 1 facing toward the measurement object 6. The magnetic poles of the first magnet 1 and the second magnet 2 are arranged such that the sides facing toward the anisotropic magneto-resistive element chip 5 (sides facing toward the anisotropic magneto-resistive (AMR) elements 51) are N poles. Accordingly, the magnetic poles of the first magnet 1 and the second magnet 2 are arranged such that the opposite sides facing in an opposite direction of the anisotropic magneto-resistive element chip 5 (sides facing in an opposite direction of the anisotropic magneto-resistive (AMR) elements 51) are S poles.Referring to FIGS. 1 and 2, the first magnet 1 applies a bias magnetic flux to a magnetic ink 61 adisposed on the measurement object 6 and the anisotropic magnetoresistive (AMR) elements 51 ( 51 aand 51 b) disposed on the anisotropic magnetoresistive element chip 5. With the aim of absorbing variations of the first magnet 1 and applying a uniform biasing magnetic flux to the anisotropic magnetoresistive (AMR) elements 51, the anisotropic magnetoresistive (AMR) element chip 5 is mounted on a first magnetic material yoke 4, and the first magnetic material yoke 4 is disposed on the N pole side of the first magnet 1.As the second magnet 2, the small magnet is provided at an end portion of the S pole side of the first magnet with the aim of applying a component By of the magnetic flux vector in the Y direction in a fixed direction. Moreover, the N pole of the second magnet 2 and the S pole of the first magnet 1 are opposite to each other. The measurement object 6 is conveyed in the X direction of FIGS. 1 and 2, and the magnetic tine 61 ais detected while the measurement object 6 passes over the anisotropic magnetoresistive (AMR) elements 51. Further, the anisotropic magnetoresistive (AMR) element chip 5 is disposed slightly offset from the center of the X direction of the first magnet 1 in the X direction.Moreover, components that would exist in an actual product are omitted from the figures. These components may be, for example, a case for housing the aforementioned first magnet 1 and the like, or a substrate that receives an output from the anisotropic magnetoresistive (AMR) elements 51 ( 51 aand 51 b) and applies the electric energy to the anisotropic magnetoresistive (AMR) elements 51 ( 51 aand 51 b). Further, such a component may also be a shield cover disposed to prevent contact with the magnetoresistive elements 51 during conveyance of the measurement object 6.FIG. 3 is a diagram showing the distribution of magnetic field lines of the magnetic sensor device according to Embodiment 1 of the invention, as viewed in the X-Z plane. Here, FIG. 3 illustrates the magnetic field lines 7 formed by the first magnet 1, the second magnet 2, and the first yoke 4 made of magnetic material. At the position of the anisotropic magnetoresistive (AMR) elements 51 ( 51 aand 51 b), the magnetic field lines are slightly inclined in the X direction, and an X direction component Bx of the magnetic flux vector is applied to the anisotropic magnetoresistive (AMR) elements 51.In this case, the X direction component Bx of the magnetic flux vector is a small magnetic field having a strength of several mT. Further, a magnetic flux of several hundreds mT is applied to the measurement object 6 having a Z-direction component Bz as a main component of the magnetic flux vector. The magnetic ink 61a is magnetized, and the anisotropic magnetoresistive (AMR) elements 51 (51a and 51b) detect the magnetization component of the magnetic ink 61a.The detection of the measurement object 6 will be described in more detail with reference to FIGS. 3 and 4. FIGS. 4 ato 4 care diagrams of a magnetic field line vector for describing the detection principles of the magnetic sensor device. In FIG. 3, the magnetic flux vectors 8 of the magnetic field lines 7 are inclined slightly in the direction of the conveying direction (X direction) from the perpendicular direction (Z direction).Here, the component Bx of the magnetic flux vector 8 acts in the conveyance direction (X direction) as a bias magnetic flux for the anisotropic magnetoresistive (AMR) elements 51 ( 51 a, 51 b). The tilting of the magnetic flux vectors 8 of the magnetic field lines 7 occurs due to slight X-direction separation of the anisotropic magnetoresistive (AMR) element 51 ( 51 a, 51 b) from the central axis of the conveyance direction length of the first magnetic material yoke 4 as illustrated in FIG. 4 a.As the measurement object 6 approaches, as illustrated in FIG. 4 b, as if it were drawn into the measurement object 6, the magnetic flux vector 8 is inclined toward the measurement object side, so that the component of the magnetic flux vector 8 in the conveyance direction (X direction) (Bx) becomes smaller. As illustrated in FIG. 4 c, when the measurement object 6 moves away, the magnetic flux vector 8 as if it were pulled by the measurement object 6 is inclined toward the measurement object 6 side, so that the component of the magnetic flux vector 8 in the conveyance direction (X direction) (Bx) becomes larger.Thus, a change in the resistance value of the anisotropic magnetoresistive (AMR) element 51 ( 51 a, 51 b) magnetically sensitive to the X direction component enables the detection of the measurement object 6.In other words, the component of the magnetic flux vector 8 in the conveyance direction (X direction) (Bx) changes due to passing through the measurement object 6, thus changing the resistance value of the anisotropic magnetoresistive (AMR) element 51 ( 51 a, 51 b) magnetically sensitive to the X direction component, thus enabling detection of the measurement object 6. In FIGS. 4 band 4 c, the dashed arrows that cross the magnetic flux vectors 8 indicate the positions of the magnetic flux vectors 8 according to FIG. 4 a.FIG. 5 is a Y-Z plane distribution diagram of the magnetic field lines of FIG. 1, and illustrates the magnetic field lines 7 formed by the first magnet 1, the second magnet 2, and the first yoke 4 made of magnetic material. A magnetic flux in the positive By direction (component of the magnetic flux vector in the positive Y direction) is applied to most of the anisotropic magnetoresistive (AMR) elements 51 ( 51 a, 51 b).Here, the general operation of the magnetic sensor will be described with reference to FIGS. 6 to 11. FIG. 6 illustrates the magnetic sensor of FIG. 1 with the second magnet 2 removed. FIG. 7 is a graph illustrating the by component (Y direction component of the magnetic flux vector) applied to the anisotropic magnetoresistive elements of FIG. 6. In FIG. 7, the broken line indicates the center position in the longitudinal direction (Y direction) of the magnetic sensor device.Moreover, both ends in the Y direction of the graph correspond to both ends of the magnetic sensor device in the longitudinal direction (Y direction). At this time, as indicated by the description with reference to FIG. 3, an X-direction component Bx of the bias magnetic flux is applied to the anisotropic magnetoresistive (AMR) elements 51. Here, the first magnet 1 has a finite length, so that the by-component (Y-direction component of the magnetic flux vector) as shown in FIG. 7 is also applied to the anisotropic magnetoresistive (AMR) elements 51, and so that the by-component has a polarity opposite in the lateral direction and is symmetrical with respect to the center of the magnet. Further, although a Bz component (Z direction component of the magnetic flux vector) of several hundreds mT is also applied to the anisotropic magnetoresistive (AMR) elements 51 ( 51 a, 51 b), the Bz component has no influence on detecting the magnetic flux change, and thus is omitted from the description.FIG. 8 is a cross-sectional top view of the structure of FIG. 6 and is a diagram illustrating the bias flux vector applied to each of the anisotropic magnetoresistive (AMR) elements. A top plan view of the structure of Fig. 6 is shown in Fig. 8, wherein the illustrated bias flux vectors 8 are applied to each of the anisotropic magnetoresistive (AMR) elements through the first magnet 1 and the first magnetic material yoke 4.Due to the action of the By component (Y-direction component of the magnetic flux vector), a magnetic flux vector 8 ainclined in the negative Y direction is applied to the anisotropic magnetoresistive (AMR) elements in the negative Y direction from the center. Moreover, thereby, a magnetic flux vector 8 binclined in the positive Y direction is applied to the anisotropic magnetoresistive (AMR) elements in the positive Y direction from the center. FIG. 9 is also a diagram illustrating the output of each of the anisotropic magnetoresistive (AMR) elements of FIG. 8. In addition, the respective output of each of the anisotropic magnetoresistive (AMR) elements of FIG. 8 is shown in FIG. 9.In FIG. 8, in the case of conveying the magnetic ink 61 aparallel to the Y direction, since the magnetic ink 61 ais parallel to the Y direction, a magnetic flux change 611 ain the direction perpendicular (X direction) to the magnetic ink 61 aappears. Moreover, a magnetic flux change in the X direction occurs for both a vector for the bias flux 8 athat is inclined in the negative Y direction and a vector for the bias flux 8 bthat is inclined in the positive Y direction.Vector rotation (change toward an opposite direction after passing through the magnetic ink 61a) occurs, resulting in a vector for magnetic flux detection 81a inclined in the negative Y direction and a vector for magnetic flux detection 81b inclined in the positive Y direction. The output shown in FIG. 9 is obtained from each of the magnetoresistive elements 51 ( 51 a, 51 b).Next, with reference to FIGS. 10 and 11, a case where the magnetic ink 61 bis conveyed rotated counterclockwise in the X-Y plane will be described. FIG. 10 is a diagram illustrating the vector for magnetic flux detection when the magnetic ink is conveyed rotated counterclockwise in the X-Y plane for the configuration of FIG. 6, FIG. 11 is a diagram illustrating an output of each of the anisotropic magnetoresistive (AMR) elements of FIG. 10.As shown in FIG. 10, a magnetic flux change 611 bis generated by the magnetic ink 61 bin the direction perpendicular to the magnetic ink 61 b. The direction of the magnetic flux change 611 bis almost the same as that of the bias magnetic flux vector 8 athat is inclined in the negative Y direction. Therefore, in the anisotropic magnetoresistive (AMR) elements 51 ( 51 a, 51 b) arranged from the center in the negative Y direction, the difference between the bias magnetic flux vectors 8 aand the magnetic flux detection vectors 82 ainclined in the negative Y direction becomes small. Therefore, the output becomes small as shown in Fig. 11.On the other hand, in the anisotropic magnetoresistive (AMR) elements 51 ( 51 a, 51 b) distributed in the positive Y direction, the difference between the bias magnetic flux vectors 8 band the magnetic flux detection vectors 82 bwhich are inclined in the positive Y direction becomes large. Therefore, as shown in FIG. 11, the output becomes large.When the direction of the vectors for the bias flux in the Y direction differs from element to element of the anisotropic magnetoresistive (AMR) elements 51 ( 51 a, 51 b) in this type, variations occur in the resultant output of the measurement object 6 for the anisotropic magnetoresistive (AMR) elements 51 ( 51 a, 51 b).The operation and effects of the magnetic sensor device according to Embodiment 1 of the invention shown in FIGS. 1 to 3 will be described below with reference to FIGS. 12 to 15. FIG. 12 illustrates the by component (Y direction component of the magnetic flux vector) applied to the anisotropic magnetoresistive (AMR) elements 51 ( 51 a, 51 b) according to Embodiment 1 of the invention. FIG. 13 illustrates the bias flux vectors 8 ( 8 a, 8 b) and the magnetic flux detection vectors 81 ( 81 a, 81 b) according to Embodiment 1 of the invention when the magnetic ink 61 ais conveyed perpendicularly to the Y direction.Fig. 14 illustrates the vectors for magnetic flux detection 82 (82a, 82b) according to Embodiment 1 of the invention when the magnetic ink 61a is conveyed rotated counterclockwise in the X-Y plane. The by-component applied to the anisotropic magnetoresistive (AMR) elements 51 ( 51 a, 51 b) is to be understood as being directed in a predetermined direction for the main part of the region through the second magnet. Due to this effect, even when the magnetic ink is rotated in the X-Y plane, stable read-out of the output of each of the anisotropic magnetoresistive (AMR) elements 51 (51a, 51b) becomes possible, except for the end portion.Moreover, the present configuration enables application of at least one fixed bias flux of a fixed direction in the Y direction. For example, when a ferromagnetic material is detected, the magnetization vector directed in the non-magnetically sensitive direction of the anisotropic magnetoresistive (AMR) elements rotates (longitudinal direction or, in this case, Y direction) and does not snap back.This causes a problem in that the resistance value of the anisotropic magnetoresistive (AMR) element changes from the original value. Applying the bias flux having at least a fixed value and a fixed direction in the Y direction by the present configuration enables suppression of the reversal of the magnetization vector.Moreover, although the anisotropic magnetoresistive (AMR) elements 51 ( 51 a, 51 b) are arrayed in parallel in the present configuration, second detection elements 51 bof the anisotropic magnetoresistive (AMR) elements 51 do not necessarily need to be arrayed in parallel with the first detection elements 51 a. Further, as illustrated in FIG. 15, a similar effect can be obtained by applying T-type bridges as first detection elements 51 aand second detection elements 51 b, the longitudinal direction being to be understood as an X direction in FIG. 15.In Embodiment 1 of the invention, a configuration is also adopted in which the first magnetic material yoke 4 is arranged with the aim of applying a uniform bias magnetic flux to the anisotropic magnetoresistive (AMR) elements 51. However, the position of the first magnetic material yoke 4 and the position of a non-magnetic metal or substrate capable of supporting the anisotropic magnetoresistive (AMR) elements 51 can be interchanged, if a sufficiently uniform bias magnetic flux can be applied to the anisotropic magnetoresistive (AMR) elements 51 even without the first magnetic material yoke.Embodiment 2Embodiment 2 of the invention will be described in more detail below with reference to the figures. Here, FIG. 16 is a longitudinal direction side view of the magnetic sensor device according to Embodiment 2 of the present invention. In FIG. 16, a tapered magnet 3 is formed such that the width of the magnetic pole direction (Z direction) in the linear direction (Y direction) decreases. In FIG. 16, the width decreases linearly. Constituent elements in FIG. 16 that are the same as or equivalent to those in FIG. 1 are denoted by the same reference numerals, and description of such elements will be omitted.In FIG. 16, the following components are provided: the magnetic ink 16 adisposed on the measurement object 6, the tapered magnet 3 for applying the bias magnetic flux to the anisotropic magnetoresistive (AMR) elements 51 ( 51 a, 51 b) disposed on the anisotropic magnetoresistive (AMR) element chip 5, and the first magnetic material yoke 4.The first yoke 4 made of magnetic material serves to intercept variations of the first magnet 1 and to apply a uniform bias magnetic flux to the anisotropic magnetoresistive (AMR) elements 51 ( 51 a, 51 b). The measurement object 6 is conveyed in the X direction of the figures, and the magnetic ink 61 ais detected as it passes over the anisotropic magnetoresistive (AMR) elements 51 ( 51 a, 51 b).Moreover, in the configuration illustrated in FIG. 16, application of a bias magnetic flux in a fixed direction relative to the Y direction by the magnet 3 is possible in the same manner as in Embodiment 1 of the invention. Thereby, the same effects as in Embodiment 1 of the invention are obtained. Although a linear slope is used for the tapered magnet 3 of FIG. 16, the shape of the slope is not necessarily linear, and a stepped shape may also be used.Embodiment 3FIG. 17 is a plan view of the magnetic sensor device according to Embodiment 3 of the invention when viewed from above. Fig. 17 illustrates, as viewed in the conveying direction, in a side view the same configuration as that shown in Fig. 6. Constituent elements in FIG. 17 that are the same as or equivalent to those in FIG. 1 are denoted by the same reference numerals, and description of such elements will be omitted. In this case, the X-direction components of the bias flux vectors 8 are assumed to be applied to first detection elements 52 aand second detection elements 52 bin the positive X direction.In the present configuration, anisotropic magnetoresistive (AMR) elements 52 ( 52 a, 52 b) are mounted in two rows in the X-Y plane, having the same inclination from the longitudinal direction (Y direction) toward the conveying direction (X direction). In this configuration, it is possible for either the first detection elements 52 aand the second detection elements 52 bto apply magnetic flux in a predetermined direction in the positive Y direction of the anisotropic magnetoresistive (AMR) elements (non-magnetically sensitive direction).At this time, the magnetic flux density in the Y direction generated by the first magnet 1 or the like can be canceled out, and the application of By in the same direction becomes possible. Thereby, it becomes possible to obtain the same effects as in Embodiment 1.The effect of the combination of embodiment 1 or 2 of the invention with embodiment 3 is synergistic. At this time, applying the uniform By in the positive Y direction along the entire longitudinal direction of the first magnet 1 to the anisotropic magnetoresistive (AMR) elements 52 has an effect of obtaining a stable output from the magnetic sensor device because the directions of the vectors for the bias magnetic flux are the same for all of the linearly arranged anisotropic magnetoresistive (AMR) elements 5 ( 52).Embodiment 4FIG. 18 is a plan view of the magnetic sensor device according to Embodiment 4 of the invention when viewed from above. The side view of FIG. 18 viewed in the conveying direction has the same configuration as that of FIG. 6. Constituent elements in FIG. 18 that are the same as or equivalent to those in FIG. 17 are denoted by the same reference numerals, and description of such elements will be omitted. In this case, the X-direction components of the vectors for the bias magnetic flux 8 are applied to the first detection elements 52 ain the positive X direction and applied to the second detection elements 52 bin the negative X direction.In the present configuration, the anisotropic magnetoresistive (AMR) elements 52 are mounted in two rows in the X-Y plane and inclined in the direction of the conveyance direction (X direction) from the longitudinal direction (Y direction), so that a configuration results in which the first detection elements 52 aand the second detection elements 52 bare mirror-symmetrical to the Y axis. Moreover, the Y axis extends through the central region of the first magnet 1 as viewed in the conveying direction (X direction), wherein the Y axis is the mirror axis of the first detection elements 52 aand the second detection elements 52 b.In this configuration, since the bias magnetic flux in the positive X direction relative to the first detection elements 52 aand the bias magnetic flux in the -X direction relative to the second detection elements 52 bare allowed to be applied to both the first detection elements 52 aand the second detection elements 52 bin a fixed direction in the longitudinal direction of the anisotropic magnetoresistive (AMR) element in the positive Y direction (non-magnetically sensitive direction). At this time, the magnetic flux density in the Y direction generated by the first magnet 1 and the like can be canceled out, and application of By in the same direction becomes possible. Accordingly, the same effects as those of Embodiment 1 of the invention are obtained.The effects of the combinations of Embodiment 1 or 2 of this invention with Embodiment 4 of this invention are synergistic. In addition, applying the uniform By in the positive Y direction to the anisotropic magnetoresistive (AMR) elements 52 along the entire length of the first magnet 1 has an effect that a stable output can be obtained from the magnetic sensor device because the directions of the vectors for the bias magnetic flux are the same for all the linearly arranged anisotropic magnetoresistive (AMR) elements 5 ( 52).Embodiment 5FIG. 19 is a longitudinal direction side view of the magnetic sensor device according to Embodiment 5 of the invention. Constituent elements in FIG. 19 that are the same as or equivalent to those in FIG. 1 are denoted by the same reference numerals, and description of such elements will be omitted. In the present invention, with the aim of enabling contactless conveyance of the measurement object 6, the first magnet 1 and the second magnet 2 are arranged above the measurement object.In addition, with the aim of imparting a uniform bias magnetic flux, the anisotropic magneto-resistive element chip 5 and a magnetic material carrier 9 are disposed over the measurement object 6. Also in the case of this configuration, the effects obtained are similar to those obtained by arranging magnets or mounting the anisotropic magnetoresistive (AMR) elements with inclination, and thus are comparable to the configurations of Embodiments 1 to 4 of the invention.Embodiment 6FIG. 20 is a longitudinal direction side view of the magnetic sensor device according to Embodiment 6 of the invention. FIG. 21 is a graph of the by component applied to the anisotropic magnetoresistive (AMR) elements in Embodiment 6 of the invention. FIG. 22 is a graph of the by component applied to the anisotropic magnetoresistive (AMR) elements in Embodiment 6 of the invention. Constituent elements in FIG. 20 that are the same as or equivalent to those in FIG. 1 are denoted by the same reference numerals, and description of such elements will be omitted.As in Embodiment 1 of the invention, the second magnet 2 is disposed at an end portion of the first magnet 1. In Embodiment 6 of the invention, on the other hand, each of the small magnets 2a and 2b is disposed at a corresponding end portion of the first magnet 1. In FIG. 20, each of the N poles of the second magnets 2 aand 2 bis opposed to the S pole of the first magnet 1. by using this configuration, as illustrated in FIG. 21, the Y direction component By of the magnetic flux vectors at both end portions of the first magnet 1 becomes zero.The broken line 8 cillustrated in FIG. 21 is the Y direction component By of the magnetic flux vectors when the small second magnets 2 aand 2 bare not provided; and the solid line 8 dis the Y direction component By of the magnetic flux vectors when the small second magnets 2 aand 2 bare provided. Thus, the bias flux vectors applied to the anisotropic magnetoresistive (AMR) elements 51 in Embodiment 6 of the invention cause the Y-direction component By of the magnetic flux vectors to uniformly become nearly zero along the entire length of the first magnet 1.Moreover, the configuration of the anisotropic magnetoresistive (AMR) elements 5 ( 52) in FIG. 20 is the configuration in which the anisotropic magnetoresistive (AMR) elements 52 ( 52 a, 52 b) are inclined in the same direction in the X-Y plane as illustrated in FIG. 17. On the other hand, the configuration may also be the configuration in which the first detection elements 52 aand second detection elements 52 bare inclined in the X-Y plane mirror-symmetrically to the Y axis, as illustrated in FIG. 18.As illustrated in FIG. 22, by arranging the anisotropic magnetoresistive (AMR) elements 5 ( 52) in this manner, a uniform Y-direction component By of the magnetic flux vector is applied over the entire length of the first magnet 1, on the positive side in the Y-direction of the anisotropic magnetoresistive (AMR) elements 52.The broken line 8 ein FIG. 22 is the Y direction component By of the magnetic flux vectors when the anisotropic magnetoresistive (AMR) elements 52 ( 52 a, 52 b) are not inclined; and the solid line 8 fis the Y direction component By of the magnetic flux vectors when the anisotropic magnetoresistive (AMR) elements 52 ( 52 a, 52 b) are inclined in the X-Y plane.In Embodiment 6 of the invention, a configuration is adopted in which each of the second magnets 2 aand 2 bis disposed at a corresponding end portion of the first magnet 1. However, a configuration may be adopted in which a tapered magnet 3 is used (as in Embodiment 2 (FIG. 16 ) of the invention) and the width in the pole direction (Z direction) decreases from both end portions toward the central portion in the linear direction (Y direction).Embodiment 7FIG. 23 is a longitudinal direction side view of the magnetic sensor device according to Embodiment 7 of the invention. The magnetic sensor device in Embodiment 7 includes a second yoke 11 made of magnetic material disposed on the surface at the S pole of the first magnet 1 of the magnetic sensor device according to Embodiment 1 of the invention as illustrated in FIG. 1, where the second magnet 2 is not disposed. Constituent elements in FIG. 23 that are the same as or equivalent to those in FIG. 1 are denoted by the same reference numerals, and description of such elements will be omitted.FIG. 24 is a diagram showing the distribution of magnetic field lines when the magnetic sensor device according to Embodiment 7 of the invention is viewed in the X-Z plane. Constituent elements in FIG. 24 that are the same as or equivalent to those in FIG. 3 are denoted by the same reference numerals, and description of these elements will be omitted. On one side of the S pole of the first magnet 1 of the magnetic sensor device in FIG. 24, in the direction perpendicular and orthogonal to the conveying direction 10, the second yoke of magnetic material 11 is disposed on the surface except for the region where the second magnet 2 is disposed.The magnetic flux (magnetic field lines 7) from the S pole of the first magnet concentrates in the second magnetic yoke 11, and the magnetic flux (magnetic field lines 7) from the first magnetic yoke 4 concentrates in and penetrates the longitudinal direction sides 11 aand 11 bof the second magnetic yoke 11 to form a magnetic circuit.That is, the magnetic path between the first magnetic yoke 4 provided at the N pole of the first magnet 1 and the S pole of the first magnet 1 becomes shorter as compared with the configuration of FIG. 1 of the magnetic sensor device in Embodiment 1 of the invention. Thus, the unnecessary loss of the magnetic flux (magnetic field lines 7) decreases, and as a result, the magnetic flux density (density of the magnetic field line 7) of the first magnetic yoke 4 and the Z component of the magnetic flux vectors 8 become large, with the first magnetic yoke 4 disposed at the N pole of the first magnet 1. Thus, such a configuration has an effect of improving the detection sensitivity of the measurement object 6 compared to the magnetic sensor device according to Embodiment 1 of the invention.In the same manner, the magnetic sensor according to Embodiment 6 illustrated in FIG. 20 has the same function effect by disposing the second yoke 11 made of magnetic material in the direction orthogonal to the conveyance direction side of the S pole of the first magnet 1 between the second magnet 2 aand the second magnet 2 b. FIG. 25 is a longitudinal direction side view of another magnetic sensor device according to Embodiment 7 of the invention.Here, the second yoke 11 made of magnetic material is provided in the direction orthogonal to the conveyance direction side of the S pole of the first magnet 1 for the magnetic sensor according to Embodiment 6 of the invention, between the second magnet 2 aand the second magnet 2 b. Constituent elements in FIG. 25 that are the same as or equivalent to those in FIG. 20 are denoted by the same reference numerals, and description of these elements will be omitted.In Embodiments 1 to 7 of the invention, for the magnetic poles of the first magnet 1 and the second magnet 2, cases where the anisotropic magnetoresistive element chip 5 side (anisotropic magnetoresistive (AMR) element 51 side 52) is set as the N pole will be described. The side opposite to the anisotropic magneto-resistive element chip 5 side (the anisotropic magneto-resistive (AMR) elements 51, 52) is given as S pole.However, the same advantageous effect can be obtained by inverting the N-S pole orientation of the magnets (first magnet 1 and second magnet 2), more specifically, by setting the side of the anisotropic magneto-resistive element chip 5 (anisotropic magneto-resistive (AMR) element 51 side, 52) as the S pole and setting the side opposite to the anisotropic magneto-resistive element chip 5 side (anisotropic magneto-resistive (AMR) element 51 side, 52) as the S pole.The present application claims the benefit of Japanese Patent Application No. 2014-99724 filed on May 13, 2014. Herein, the entire specification, claims, and drawings of Japanese Patent Application No. 2014-99724 are incorporated herein by reference.List of reference characters1 First magnet 2 Second magnet 2 aSecond magnet 2 bSecond magnet 3 Tapered magnet 4 First yoke made of magnetic material 5 Chip with anisotropic magnetoresistive elements 51 Anisotropic magnetoresistive element 51 a Anisotropic magnetoresistive element (first detection element) 51 b Anisotropic magnetoresistive element (second detection element) 52 Anisotropic magnetoresistive element 52 a Anisotropic magnetoresistive element (first detection element) 52 b Anisotropic magnetoresistive element (second detection element) 6 Measurement object 61 a Magnetic ink 61 b Magnetische ink 611 a Magnetfluss flux change 611 b Magnetfluss flux change 7 Magnetic field lines 8 Vector for bias flux 8 a Vector for bias flux 8 b Vector for bias flux 8 c Gestrichelte lines 8 d Durchgezogene lines 8 e Gestrichelte lines 8 f Durchgezogene lines 81 Vector for magnetic flux detection 81a Vector for magnetic flux detection 81b Vector for magnetic flux detection 82 Vector for magnetic flux detection 82a Vector for magnetic flux detection 82b Vector for magnetic flux detection 9 Magnetic material support 10 Conveyance direction 11 Second yoke of magnetic material 11a Side surface 11b Side surface

Claims

A magnetic sensor device comprising: a magnet (1, 2, 2a, 2b, 3) extending in a longitudinal direction orthogonal to a conveyance direction (10) of a measurement object (6) including a magnetic material, the magnet (1, 2, 2a, 2b, 3) having magnetic poles different in a direction perpendicular to the conveyance direction (10); and anisotropic magnetoresistive elements (51, 52) linearly arranged in the longitudinal direction on a measurement object-side magnetic pole of the magnet (1, 2, 2a, 2b, 3), wherein the length of the magnet (1, 2, 2a, 2b, 3) in the direction perpendicular to the conveyance direction (10) is longer for an end portion in the longitudinal direction than for a central portion in the longitudinal direction.The magnetic sensor device according to claim 1, further comprising a yoke (4) made of magnetic material disposed between the anisotropic magnetoresistive elements (51, 52) and the magnet (1, 2, 2a, 2b, 3).The magnetic sensor device according to any one of claims 1 and 2, wherein the magnet (1, 2, 2a, 2b, 3) includes: a first magnet (1) in which the length in the direction perpendicular to the conveyance direction (10) along the longitudinal direction is the same; and a second magnet (2, 2a, 2b) having mutually different magnetic poles in the direction perpendicular to the conveyance direction (10), wherein the second magnet (2, 2a, 2b) is provided at an end of the range in the longitudinal direction of the first magnet (1), and wherein a magnetic pole of a surface of the second magnet (2, 2a, 2b) contacting the first magnet (1) has an opposite polarity to a magnetic pole of the first magnet (1) opposing the measurement object (6).The magnetic sensor device according to claim 3, further comprising a second yoke (11) made of magnetic material disposed on a surface that is the magnetic pole of the first magnet (1) on the side opposite to the measurement object (6) except for the location where the second magnet (2, 2a, 2b) is disposed.The magnetic sensor device according to claim 1 or 2, wherein the length of the magnet (1, 2, 2a, 2b, 3) in the direction perpendicular to the conveying direction (10) becomes shorter from the end portion toward the central portion in the longitudinal direction.The magnetic sensor device according to any one of claims 1 to 5, wherein the anisotropic magnetoresistive elements (51, 52) are inclined at predetermined angles from the longitudinal direction toward the conveying direction (10) side.A magnetic sensor device, comprising: a magnet (1, 2, 2a, 2b, 3) extending in a longitudinal direction perpendicular to a conveyance direction (10) of a magnetic material measurement object (6), wherein the magnet (1, 2, 2a, 2b, 3) has magnetic poles different in a direction perpendicular to the conveyance direction (10); and a plurality of anisotropic magnetoresistive elements (51, 52) linearly arranged in the longitudinal direction on a measurement-object-side magnetic pole of the magnet (1, 2, 2a, 2b, 3), wherein the anisotropic magnetoresistive elements (51, 52) are inclined at predetermined angles from the longitudinal direction toward the conveying direction (10) side, and wherein the direction of a component in the longitudinal direction of a magnetic field generated by the magnet (1, 2, 2a, 2b, 3) and applied to each of the anisotropic magnetoresistive elements (51, 52) faces the same direction except for the anisotropic magnetoresistive elements (51, 52) arranged at an end portion of the plurality of anisotropic magnetoresistive elements (51, 52) in the longitudinal direction.The magnetic sensor device according to any one of claims 1 to 7, wherein the anisotropic magnetoresistive elements (51, 52) are arranged in two rows along the longitudinal direction.The magnetic sensor device according to claim 8, wherein a center of the two rows of anisotropic magnetoresistive elements (51, 52) as viewed in the conveying direction (10) is offset to a predetermined position in the conveying direction (10) from a central position of the magnet (1, 2, 2a, 2b, 3) as viewed in the conveying direction (10).The magnetic sensor device according to claim 8, wherein the one row of the anisotropic magnetoresistive elements (51, 52) is shifted from a central portion of the magnet (1, 2, 2a, 2b, 3) as viewed in the conveying direction (10) toward the one end side of the magnet (1, 2, 2a, 2b, 3) in the conveying direction (10); and wherein the other row of the anisotropic magnetoresistive elements (51, 52) is shifted from the central portion of the magnet (1, 2, 2a, 2b, 3) as viewed in the conveying direction (10) toward the other end side of the magnet (1, 2, 2a, 2b, 3) in the conveying direction (10).The magnetic sensor device according to claim 6 or 7, wherein the anisotropic magnetoresistive elements (51, 52) are arranged in two rows along the longitudinal direction; wherein the one row of the anisotropic magnetoresistive elements (51, 52) is offset from a central portion of the magnet (1, 2, 2a, 2b, 3) toward the one end side of the magnet (1, 2, 2a, 2b, 3) in the conveying direction (10) as viewed in the conveying direction (10); wherein the other row of the anisotropic magnetoresistive elements (51, 52) is offset from the central position of the magnet (1, 2, 2a, 2b, 3) toward the other end side of the magnet (1, 2, 2a, 2b, 3) in the conveying direction (10) as viewed in the conveying direction (10); and wherein the inclination directions of the rows are different from each other.The magnetic sensor device according to claim 11, wherein the anisotropic magnetoresistive elements (51, 52) are arranged mirror-symmetrically with respect to the longitudinal direction passing through the central position as viewed in the conveying direction (10).

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