JP2020071095A - Magnetic sensor - Google Patents

Abstract

To reduce spatial unevenness of detection sensitivity of a magnetic sensor using a magnetic material that is larger than a sensor chip.SOLUTION: A magnetic sensor 10A comprises a sensor chip 30 and a magnetic material 40A for collecting a magnetic flux φ to a magnetic detection element of the sensor chip 30. The length of the magnetic material 40A in the X direction is greater than the length of the sensor chip 30 in the X direction. The thickness of the magnetic material 40A in the Y direction differs depending on its position in the X direction. According to the present invention, the magnetism collection capacity of the magnetic material 40A is relatively high at its thicker portion and relatively low at its thinner portion. Therefore, it is possible to reduce spatial unevenness of detection sensitivity by increasing the thickness of a portion where sensitivity is low when the thickness of the magnetic material is uniform or decreasing the thickness of a portion where sensitivity is excess when the thickness of the magnetic material is uniform.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a magnetic sensor, and more particularly to a magnetic sensor including a magnetic body for collecting magnetic flux in a magnetic detection element.

  Magnetic sensors are widely used in ammeters, magnetic encoders, bill sensors, and the like. As described in Patent Documents 1 and 2, a magnetic sensor may be provided with a magnetic body for collecting magnetic flux in a magnetic detection element. When the magnetic sensor is provided with a magnetic material, the magnetic detection sensitivity is improved and the directivity can be provided.

Japanese Patent No. 5500785 JP, 2016-170028, A

  However, the magnetism collecting ability of the magnetic material is not always uniform, and in some cases, the magnetism collecting ability may be locally high or may be locally low. Unevenness occurs. Such a phenomenon becomes particularly remarkable when a magnetic body having a size larger than that of the sensor chip is used.

  Therefore, it is an object of the present invention to reduce spatial unevenness of detection sensitivity in a magnetic sensor using a magnetic body having a size larger than that of a sensor chip.

  A magnetic sensor according to the present invention has a sensor chip having an element formation surface on which a magnetic detection element is formed, and a first direction parallel to the element formation surface as a longitudinal direction, which is parallel to the element formation surface and orthogonal to the first direction. Is a plate-shaped member having a second direction as a thickness direction, and has a magnetic body that collects magnetic flux in the magnetic detection element, and the length of the magnetic body in the first direction is the length of the sensor chip in the first direction. And the thickness of the magnetic body in the second direction varies depending on the position in the first direction.

  According to the present invention, since the thickness of the magnetic body is different depending on the position in the first direction, the magnetism collecting ability of the thick portion is relatively high, and the magnetism collecting ability of the thin portion is relatively high. It becomes low. Therefore, if the thickness of the part where the sensitivity decreases when the thickness of the magnetic substance is constant is increased, or if the thickness of the part where the sensitivity is excessive when the thickness of the magnetic substance is constant is decreased, the detection sensitivity is reduced. It is possible to reduce the spatial unevenness of.

  In the present invention, regarding the thickness of the magnetic body in the second direction, the thickness in the first region that overlaps with the sensor chip when viewed from the third direction orthogonal to the element formation surface is the second region that does not overlap with the sensor chip. It may be thicker than the thickness in the region. According to this, it becomes possible to enhance the magnetism collecting ability in the substantially central portion which overlaps with the sensor chip.

  In this case, the thickness of the magnetic substance in the first region in the second direction may be larger at the upper end portion away from the element formation surface than at the lower end portion close to the element formation surface. According to this, the chip size of the sensor chip can be further reduced. Further, in this case, when viewed from the third direction, the magnetic detection element may not overlap the lower end portion of the magnetic body, and may overlap the upper end portion of the magnetic body. According to this, the chip size of the sensor chip can be further reduced.

  The magnetic sensor according to the present invention further includes a magnetic shield that covers the sensor chip and the magnetic body, and the magnetic shield includes first and second side wall portions that sandwich the sensor chip from the second direction, and one end of the first side wall portion. A first top plate portion connected to the magnetic body and extending in the second direction toward the magnetic body, and a first side plate portion connected to one end of the second side wall portion and extending in the second direction toward the magnetic body. And a magnetic body in a gap formed by the tip of the first top plate portion and the tip of the second top plate portion without contacting the first and second top plate portions. It may be placed in. According to this, it becomes possible to improve the detection selectivity with respect to the magnetic pattern located immediately below (or immediately above) the magnetic body. Therefore, if the member to be measured is scanned in the second direction, for example, it is possible to improve the resolution especially in the scanning direction.

  In this case, the thickness of the magnetic body in the second direction is larger in the third region that does not overlap with the sensor chip than in the first region that overlaps with the sensor chip when viewed from the third direction orthogonal to the element formation surface. The thickness may be thicker. According to this, it becomes possible to enhance the magnetism collecting ability of the end portion in the first direction in which the magnetism collecting ability is likely to decrease due to the presence of the magnetic shield.

  As described above, according to the present invention, it is possible to reduce the spatial unevenness of the detection sensitivity in the magnetic sensor using the magnetic body having a larger size than the sensor chip.

FIG. 1 is a schematic perspective view for explaining the structure of a magnetic sensor 10A according to the first embodiment of the present invention. FIG. 2 is a schematic top view for explaining the structure of the magnetic sensor 10A according to the second embodiment of the present invention. FIG. 3 is a circuit diagram for explaining the connection relationship of the magnetic detection elements R1 to R4. FIG. 4 is a graph showing the sensitivity distribution in the x direction of the magnetic sensor 10A according to the first embodiment. 5A and 5B are views showing a long magnetic sensor in which a plurality of magnetic sensors 10A according to the first embodiment are arranged in the x direction. FIG. 5A is a schematic side view seen from the y direction, and FIG. It is a schematic top view seen from the direction. FIG. 6 is a schematic perspective view for explaining the structure of the magnetic sensor 10B according to the second embodiment of the present invention. FIG. 7 is a schematic top view for explaining the structure of the magnetic sensor 10B according to the second embodiment of the present invention. FIG. 8 is a yz sectional view for explaining the structure of the magnetic sensor 10B according to the second embodiment of the present invention. FIG. 9 is a graph showing the sensitivity distribution in the x direction of the magnetic sensor 10B according to the second embodiment. FIG. 10 is a schematic perspective view showing the outer appearance of the magnetic sensor 10C according to the third embodiment of the present invention. FIG. 11 is a schematic perspective view showing a state in which the magnetic shield 50C is removed from the magnetic sensor 10C. FIG. 12 is a yz sectional view of the magnetic sensor 10C according to the third embodiment. FIG. 13 is a graph for explaining the effect of the magnetic sensor 10C according to the third embodiment. FIG. 14 is a graph showing the sensitivity distribution in the x direction of the magnetic sensor 10C according to the third embodiment. FIG. 15 is a schematic perspective view showing a long magnetic sensor using the magnetic sensor 10C according to the third embodiment. FIG. 16 is a schematic perspective view for explaining the structure of the magnetic sensor 10D according to the fourth embodiment of the present invention. FIG. 17 is a schematic top view for explaining the structure of the magnetic sensor 10D according to the fourth embodiment of the present invention.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

<First Embodiment>
1 and 2 are views for explaining the structure of the magnetic sensor 10A according to the first embodiment of the present invention, FIG. 1 is a schematic perspective view, and FIG. 2 is a schematic top view.

  As shown in FIGS. 1 and 2, the magnetic sensor 10A according to the first embodiment has a substantially rectangular parallelepiped shape, and the sensor chip 30 mounted in the mounting region 21 of the substrate 20 and the x direction as the longitudinal direction. It is composed of a plate-shaped magnetic body 40A. Four magnetic detection elements R1 to R4 and a plurality of terminal electrodes 32 are formed on the element forming surface 31, which is the upper surface of the sensor chip 30, and these terminal electrodes 32 are provided on the substrate 20 via the bonding wires BW. It is connected to the provided terminal electrode 22. As the magnetic detection elements R1 to R4, it is preferable to use a magnetoresistive effect element (MR element) whose electric resistance changes according to the direction of the magnetic field. The magnetization fixed directions of the magnetic detection elements R1 to R4 are all aligned with the direction indicated by the arrow P in FIG. 2 (the y direction).

  On the element forming surface 31 of the sensor chip 30, a magnetic body 40A made of a high magnetic permeability material such as ferrite is fixed. The magnetic body 40A is a plate-shaped member having the x direction as the longitudinal direction and the y direction as the thickness direction, and plays a role of collecting the magnetic flux φ in the sensor chip 30. The length L1 of the magnetic body 40A in the x direction is longer than the length L0 of the sensor chip 30 in the x direction, and the thicknesses T1 and T2 of the magnetic body 40A in the y direction are larger than the width T0 of the sensor chip 30 in the y direction. thin. The magnetic body 40A has a first region 41 that overlaps with the sensor chip 30 when viewed from the z direction, and a second region 42 that does not overlap with the sensor chip 30 when viewed from the z direction, and in the y direction in the first region 41. Of the second region 42 is thicker than the thickness T2 of the second region 42 in the y direction.

  In the example shown in FIGS. 1 and 2, the region having the thickness T1 is enlarged to the position where it does not overlap the sensor chip 30, but this point is not essential in the present invention. On the contrary, the region having the thickness T2 may be enlarged to a position where it overlaps with the sensor chip 30. That is, the thickness of the central portion in the x direction where the magnetic detection elements R1 to R4 are provided is T1, and the thickness of both end portions in the x direction is T2 (<T1).

  The first region 41 of the magnetic body 40A is arranged between the magnetic detection elements R1 and R3 and the magnetic detection elements R2 and R4. Here, the magnetic detection elements R1 and R3 have the same position in the y direction, and the magnetic detection elements R2 and R4 have the same position in the y direction. Further, the magnetic detection elements R1 and R4 have the same position in the x direction, and the magnetic detection elements R2 and R3 have the same position in the x direction. The magnetic body 40A plays a role of collecting the magnetic flux φ in the vertical direction (z direction), and the magnetic flux φ collected by the magnetic body 40A is substantially evenly distributed in the y direction. Therefore, the magnetic flux φ in the vertical direction is applied to the magnetic detection elements R1 to R4 substantially evenly.

  FIG. 3 is a circuit diagram for explaining the connection relationship of the magnetic detection elements R1 to R4.

  As shown in FIG. 3, the magnetic detection elements R2 and R1 are connected in series between the terminal electrode 32 supplied with the power supply potential Vdd and the terminal electrode 32 supplied with the ground potential Gnd. Similarly, the magnetic detection elements R3 and R4 are also connected in series between the terminal electrode 32 supplied with the power supply potential Vdd and the terminal electrode 32 supplied with the ground potential Gnd. The potential Va at the connection point between the magnetic detection element R1 and the magnetic detection element R2 is output to the outside through a predetermined terminal electrode 32, and the potential Vb at the connection point between the magnetic detection element R3 and the magnetic detection element R4 is at another terminal. It is output to the outside through the electrode 32.

  The magnetic detection elements R1 and R3 are arranged on one side (the upper side in FIG. 2) when viewed from the magnetic body 40A in a plan view, and the magnetic detection elements R2 and R4 are the other side (when viewed from the magnetic body 40A in a plan view). Since the magnetic detection elements R1 to R4 form a differential bridge circuit, the magnetic detection elements R1 to R4 can detect changes in the electrical resistance of the magnetic detection elements R1 to R4 according to the magnetic flux density with high sensitivity. It will be possible. That is, since the magnetic detection elements R1 to R4 all have the same magnetization fixed direction, the resistance change amount of the magnetic detection elements R1 and R3 located on one side when viewed from the magnetic body 40A in plan view and the plane There is a difference between the resistance change amounts of the magnetic detection elements R2 and R4 located on the other side when viewed from the magnetic body 40A. This difference is amplified by the differential bridge circuit shown in FIG. However, it is not essential to use the four magnetic detection elements R1 to R4 in the present invention, and for example, two magnetic detection elements (R1 and R4) may be used.

  As described above, the magnetic body 40A plays a role of collecting the magnetic flux φ in the z direction, but as shown in FIG. 1, since more magnetic flux φ collects from the surroundings at both ends in the x direction of the magnetic body 40A, The magnetic detection sensitivity in this portion may be locally increased. However, in the magnetic sensor 10A according to the first embodiment, the thickness T1 of the first region 41 located in the central portion of the magnetic body 40A in the x direction is selectively increased, thereby enhancing the magnetism collecting ability of this portion. Therefore, the magnetism collecting ability is made more uniform. As a result, spatial unevenness of detection sensitivity is reduced.

  FIG. 4 is a graph showing the sensitivity distribution in the x direction of the magnetic sensor 10A according to the first embodiment, in which the length L1 of the magnetic body 40A in the x direction is 8.0 mm and the thicknesses T1 and T2 in the y direction are respectively. 0.45 mm and 0.15 mm, the height in the z direction is 1.3 mm, and the width W1 in the x direction of the first region 41 is 0.25 mm, 0.5 mm, 1 mm, 1.5 mm, and 2 mm. The simulation result of is shown. The length L0 of the sensor chip 30 in the x direction is 1 mm. The horizontal axis of the graph shows the position in the x direction when the central portion of the magnetic body 40A in the x direction is 0, and the vertical axis of the graph is the detection sensitivity when the highest sensitivity is 100%. This point is the same in the following graphs.

  As shown in FIG. 4, in the magnetic sensor 10A according to the first embodiment, the sensitivity is slightly reduced in the central portion in the x direction, but the reduction amount is large in the width W1 of the first region 41 in the x direction. It turns out that it is alleviated. In particular, when the width W1 of the first region 41 in the x direction is larger than the length L0 of the sensor chip 30 in the x direction, it can be seen that a flatter characteristic is obtained.

  As described above, in the magnetic sensor 10A according to the first embodiment, the thickness T1 of the first region 41 located in the substantially central portion of the magnetic body 40A in the x direction is selectively increased, so It is possible to compensate for the decrease in the magnetic detection sensitivity in the part. As a result, it becomes possible to obtain flatter characteristics. Moreover, since the magnetic body 40A used in the first embodiment has a relatively simple shape, it is possible to suppress an increase in manufacturing cost. As a method of manufacturing the magnetic body 40A, ferrite or the like may be integrally formed, or a simple plate-shaped body made of ferrite or the like may be prepared, and another ferrite member may be provided in a portion corresponding to the first region 41. It may be produced by pasting.

  As shown in FIG. 5, the magnetic sensor 10A according to the first embodiment can form a long type magnetic sensor by arranging a plurality of magnetic sensors in the x direction. According to this, it is possible to scan the magnetic pattern provided on the member to be measured (not shown) that moves in the y direction. Although not particularly limited, bills may be used as the member to be measured. The bill may be scanned in either the short side direction or the long side direction. When a plurality of magnetic sensors 10A are arranged in the x direction, it is necessary to separate two magnetic bodies 40A adjacent to each other in the x direction through a slight gap Gx, as shown in FIG. The length of the sensor chip 30 in the x direction is sufficiently smaller than the length of the magnetic body 40A in the x direction, and therefore two sensor chips 30 adjacent to each other in the x direction are sufficiently separated from each other.

  The gap Gx is a portion where the magnetic pattern cannot be detected or the detection sensitivity is significantly reduced. Therefore, it is preferable to design the width of the gap Gx in the x direction as narrow as possible. However, when two magnetic bodies 40A adjacent to each other in the x direction come into contact with each other, magnetic interference occurs between the adjacent magnetic sensors 10A, so it is necessary to lay out the two so that they do not come into direct contact with each other.

<Second Embodiment>
6 to 8 are views for explaining the structure of the magnetic sensor 10B according to the second embodiment of the present invention. FIG. 6 is a schematic perspective view, FIG. 7 is a schematic top view, and FIG. 8 is a yz cross-sectional view. Is.

  As shown in FIGS. 6 to 8, the magnetic sensor 10B according to the second embodiment is different from the magnetic sensor 10A according to the first embodiment in that the magnetic body 40A is replaced by the magnetic body 40B. .. Since the other basic configuration is the same as that of the magnetic sensor 10A according to the first embodiment, the same reference numerals are given to the same elements, and duplicate description will be omitted.

  In the magnetic body 40B used in the second embodiment, the thickness of the first region 41 is not constant in the z direction, and the thickness of the lower end portion 41b near the element forming surface 31 is the same as the thickness T2 of the second region 42. It is considered to be the thickness. The thickness of the upper end portion 41a away from the element forming surface 31 is T1 (> T2), which is the same as in the first embodiment. With this configuration, the distance between the magnetic detection elements R1 and R4 and the magnetic detection elements R2 and R3 in the y direction can be shortened, so that the size of the sensor chip 30 in the y direction can be further reduced. In particular, as shown in FIG. 8, the magnetic detection elements R1 to R4 may not overlap the lower end portion 41b when viewed from the z direction, and the magnetic detection elements R1 to R4 may overlap the upper end portion 41a when viewed from the z direction. preferable. That is, it is preferable that the magnetic detection elements R1 to R4 be covered with the overhang portion formed by the boundary between the upper end portion 41a and the lower end portion 41b. According to this, the size of the sensor chip 30 in the y direction can be further reduced.

  FIG. 9 is a graph showing the sensitivity distribution in the x direction of the magnetic sensor 10B according to the second embodiment, in which the height of the upper end portion 41a of the magnetic body 40B in the z direction is 1.2 mm and the lower end portion 41b of the magnetic body 40B. Is the same as the simulation condition in FIG. 4 except that the height in the z direction is 0.1 mm.

  As shown in FIG. 9, it is understood that the magnetic sensor 10B according to the second embodiment further alleviates the decrease in sensitivity at the central portion in the x direction. Particularly, as the width W1 of the upper end portion 41a of the first region 41 in the x direction increases, the decrease in sensitivity is alleviated, and when the width W1 is 1 mm or more, the decrease in sensitivity in the central portion is suppressed to 4% or less. Has been done.

<Third Embodiment>
FIG. 10 is a schematic perspective view showing the outer appearance of the magnetic sensor 10C according to the third embodiment of the present invention.

  As shown in FIG. 10, the magnetic sensor 10C according to the third embodiment includes a magnetic shield 40C that covers the substrate 20, the sensor chip 30, and the magnetic body 40C while the magnetic body 40A is replaced by the magnetic body 40C. The magnetic sensor 10A differs from the magnetic sensor 10A according to the first embodiment in that Since the other basic configuration is the same as that of the magnetic sensor 10A according to the first embodiment, the same reference numerals are given to the same elements, and duplicate description will be omitted. The magnetic shield 50C is a member for increasing the directivity of the magnetic sensor 10C by blocking magnetic flux that becomes noise, and it is preferable to use a magnetic metal material having a high magnetic permeability such as permalloy.

  FIG. 11 is a schematic perspective view showing a state in which the magnetic shield 50C is removed from the magnetic sensor 10C.

  As shown in FIG. 11, the magnetic body 40C included in the magnetic sensor 10C includes a first region 41 that overlaps the sensor chip 30 when viewed in the z direction and a third region that does not overlap the sensor chip 30 when viewed in the z direction. 43, the thickness T3 at both ends in the x direction of the third region 43 is thicker than the thickness T1 in the first region 41. Although not particularly limited, in the third embodiment, the thickness of the third region 43 is not constant in the z direction, and the thickness of the upper end portion located between the gaps of the magnetic shield 50C is T3 (> T1). ) And the thickness of the lower end portion is T1, which is the same as that of the first region 41. However, the thickness of the third region 43 may be T3 from the upper end to the lower end.

  FIG. 12 is a yz sectional view of the magnetic sensor 10C according to the third embodiment.

  As shown in FIG. 12, most of the substrate 20, the sensor chip 30, and the magnetic body 40C that form the magnetic sensor 10C are covered with the magnetic shield 50C. The magnetic shield 50C is connected to the first and second side wall portions 51 and 52 that sandwich the sensor chip 30 from the y direction, and one end of the first side wall portion 51 in the z direction, and extends in the y direction toward the magnetic body 40C. A first top plate portion 53 that extends and a second top plate portion 54 that is connected to one end of the second side wall portion 52 in the z direction and extends in the y direction toward the magnetic body 40C; Has a bottom plate portion 55 that connects the other end of the side wall portion 51 in the z direction and the other end of the second side wall portion 52 in the z direction. The 1st and 2nd side wall parts 51 and 52 comprise an xz plane, and the 1st and 2nd top plate parts 53 and 54 and the bottom plate part 55 comprise an xy plane.

  If a magnetic metal material such as permalloy is used as the material for the magnetic shield 50C, the magnetic shield 50C can be manufactured by bending one magnetic metal plate. However, the magnetic shield 50C does not have to be integrated, and a plurality of magnetic members may be bonded together. Further, the space surrounded by the magnetic shield 50C and the substrate 20 may be molded with a resin material. As described above, since the magnetic shield 50C is a substantially cylindrical body, the magnetic sensor 10C can be manufactured by inserting the substrate 20 on which the sensor chip 30 and the magnetic body 40C are mounted into the cylindrical magnetic shield 50C. it can. In this case, the magnetic shield 50C itself can be used as a housing of the magnetic sensor 10C. However, the magnetic shield 50C does not have to be a substantially cylindrical body, the bottom plate portion 55 is omitted, and the portion including the first side wall portion 51 and the first top plate portion 53, the second side wall portion 52, and the second side wall portion 52 and the first side wall portion 52 are omitted. The portion composed of the two top plate portions 54 may be configured by another member.

  As shown in FIG. 12, in the third embodiment, the magnetic body 40C is arranged in the gap G formed by the tip of the first top plate portion 53 and the tip of the second top plate portion 54. Although not particularly limited, the upper surface of the magnetic body 40C is preferably located on the same plane as the first and second top plate portions 53 and 54. This is because, as viewed from the first and second top plate portions 53, 54, the magnetic field detection sensitivity decreases as the upper surface of the magnetic body 40C retracts toward the rear side, while the protruding amount of the upper surface of the magnetic body 40C increases. This is because it is easy to be affected by noise. Further, the magnetic body 40C is not in contact with the first and second top plate portions 53 and 54, and has a predetermined space S with respect to the first and second top plate portions 53 and 54. A non-magnetic member such as resin may be interposed between the magnetic body 40C and the first and second top plate portions 53 and 54.

  The member 60 to be measured is also shown in FIG. The member 60 to be measured has magnetic patterns M1 and M2 arranged in the y direction. When the member 60 to be measured is scanned in the y direction, the magnetic patterns M1 and M2 pass under the magnetic body 40C in the y direction. It will be. In the scan of the member to be measured 60, the member to be measured 60 may be moved in the y direction while the magnetic sensor 10C is fixed, and conversely, when the member to be measured 60 is fixed, the magnetic sensor 10C is moved to the y direction. It may be moved in any direction. Further, the vertical position of the magnetic sensor 10C and the member to be measured 60 may be reversed. Then, when the magnetic patterns M1 and M2 pass immediately below the magnetic body 40C in the y direction, magnetic flux generated by the magnetic patterns M1 and M2 is given to the magnetic detection elements R1 to R4 via the magnetic body 40C, whereby the magnetic pattern. M1 and M2 are read.

  In FIG. 12, since the magnetic pattern M1 is located immediately below the magnetic body 40C, the magnetic flux generated by the magnetic pattern M1 is read at this timing. However, since another magnetic pattern M2 exists in the vicinity of the magnetic pattern M1 in the y direction, a part of the magnetic flux generated by this magnetic pattern M2 is also read at the same timing. The magnetic flux generated by the magnetic pattern M2 is noise at the timing of reading the magnetic pattern M1.

  However, the magnetic sensor 10C according to the third embodiment includes the magnetic shield 50C, and the magnetic flux of the magnetic pattern (M2 in FIG. 12) that is not located immediately below the magnetic body 40C can be blocked by the magnetic shield 50C. That is, the magnetic flux in the y-direction that becomes noise is blocked by the first and second side wall portions 51 and 52 having the xz plane, and the magnetic flux in the z-direction that becomes noise is the first and the second side walls having the xy plane. It is shut off by the top plate portions 53 and 54 of. Thereby, the magnetic flux generated from the magnetic pattern (M1 in FIG. 12) located immediately below the magnetic body 40C can be more selectively read, and the spatial resolution can be improved.

  FIG. 13 is a graph for explaining the effect of the magnetic sensor 10C according to the third embodiment, where the horizontal axis represents the position in the y direction of the magnetic pattern with the magnetic body 40C as the reference, and the vertical axis represents the detected magnetic field. Shows strength. The intensity of the detected magnetic field is standardized with a peak value of 1. As shown in FIG. 13, it can be seen that the magnetic sensor 10C including the magnetic shield 50C has a sharper waveform of the detected magnetic field than the magnetic sensors 10A and 10B not including the magnetic shield 50C, and the spatial resolution is improved.

  FIG. 14 is a graph showing the sensitivity distribution in the x direction of the magnetic sensor 10C according to the third embodiment, in which the length L1 of the magnetic body 40C in the x direction is 8.0 mm and the thicknesses T1 and T3 in the y direction are respectively. 0.15 mm and 0.45 mm, the height in the z direction is 1.3 mm, and the width W2 of the third region 43 in the x direction is 0 mm, 0.25 mm, 0.5 mm, 1 mm, 1.5 mm and 2 mm. The simulation result in a certain case is shown.

  As shown in FIG. 14, when the width W2 of the third region 43 is 0 mm, that is, when the magnetic body 40C is a simple plate-like body and the thickness in the y direction is completely constant, in the x direction. The sensitivity decreases at both ends. Then, as the width W2 of the third region 43 is increased, the sensitivities of both ends in the x direction are improved, but when the width W2 of the third region 43 is too large, the sensitivities of both ends in the x direction are high. As a result, the sensitivity of the central portion in the x direction becomes relatively low. Under the above simulation conditions, the flattest characteristic is obtained when the width W2 of the third region 43 is 1 mm. Generally speaking, if the width W2 of the third region 43 is set in the range of 10% to 15% with respect to the length of the magnetic body 40C in the x direction, the flattest characteristic can be obtained.

  As described above, the magnetic sensor 10C according to the third embodiment selectively enlarges the thickness of the magnetic body 40C at both ends in the x direction, and thus compensates for the decrease in magnetic detection sensitivity at both ends. It becomes possible.

  The reason why the sensitivity at both ends is lowered when the magnetic body 40 that is a simple plate-like body is used is as follows.

  When the magnetic flux φ in the z direction exists with respect to the magnetic body 40 that is a simple plate-shaped body, the magnetic flux φ flows into the magnetic body 40 and the magnetic shield 50C. Further, the ratio of the magnetic flux φ flowing into the magnetic body 40 and the magnetic shield 50C is not constant in the position in the x direction, and tends to decrease at both ends of the magnetic body 40 as compared with the central portion of the magnetic body 40. This is because when the magnetic pattern M1 is located at the central portion of the magnetic body 40, the magnetic flux φ of the entire area flows into the magnetic body 40 with respect to the area of the magnetic flux generated from the magnetic pattern M1 in the x direction. When the magnetic patterns M1 are located at both ends of the magnetic substance, the magnetic flux φ flowing into the magnetic substance 40 becomes a region narrower than the entire region, and as a result, the amount of the magnetic flux passing through the magnetic substance 40 and given to the magnetic detection elements R1 to R4 decreases. Is. Due to such a mechanism, when the magnetic body 40 that is a simple plate-like body is used, the sensitivity at both ends is significantly reduced.

  On the other hand, in the magnetic sensor 10C according to the third embodiment, since the magnetic body 40C in which the thickness at both ends in the x direction is selectively increased is used, the decrease in sensitivity at both ends is compensated. As a result, it becomes possible to obtain flatter characteristics.

  Further, as shown in FIG. 15, by arranging a plurality of sensor chips 30 and magnetic bodies 40C in the magnetic shield 50C in the x direction, a long magnetic sensor can be configured. According to this, it is possible to scan a magnetic pattern provided on a member to be measured (not shown) such as a bill that moves in the y direction.

<Fourth Embodiment>
16 and 17 are views for explaining the structure of the magnetic sensor 10D according to the fourth embodiment of the present invention, FIG. 16 is a schematic perspective view, and FIG. 17 is a schematic top view.

  As shown in FIGS. 16 and 17, the magnetic sensor 10D according to the fourth embodiment is different from the magnetic sensor 10C according to the third embodiment in that the magnetic shield 50C is replaced with the magnetic shield 50D. .. Since the other basic configuration is the same as that of the magnetic sensor 10C according to the third embodiment, the same elements will be denoted by the same reference symbols and redundant description will be omitted.

  In the magnetic shield 50D used in the fourth embodiment, the width of the gap G in the y direction is not constant, and the gap width matches the thickness of the magnetic body 40C. That is, at the position where the thin portion of the magnetic body 40C (the portion having the thickness T1) is sandwiched, the width of the gap G is narrow, and the portion where the thickness of the magnetic body 40C is thick (the portion having the thickness T3) is sandwiched. In, the width of the gap G is also wide. As a result, the space S shown in FIG. 12 can be narrowed (ideally, uniform), and the shield effect of the magnetic shield 50D can be enhanced.

  Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the gist of the present invention. It goes without saying that it is included in the range.

10A, 10B, 10C, 10D Magnetic sensor 20 Substrate 21 Mounting area 22 Terminal electrode 30 Sensor chip 31 Element forming surface 32 Terminal electrodes 40, 40A, 40B, 40C Magnetic body 41 First area 41a Upper end 41b Lower end 42 Second Region 43 third region 50C, 50D magnetic shield 51 first side wall part 52 second side wall part 53 first top plate part 54 second top plate part 55 bottom plate part 60 member to be measured BW bonding wire G, Gx Gap M1, M2 Magnetic patterns R1 to R4 Magnetic detection element S Interval φ Magnetic flux

Claims (7)

A sensor chip having an element formation surface on which a magnetic detection element is formed,
A plate-shaped member having a first direction parallel to the element formation surface as a longitudinal direction and a second direction parallel to the element formation surface and orthogonal to the first direction as a thickness direction, and a magnetic flux And a magnetic substance collected in the detection element,
The length of the magnetic body in the first direction is larger than the length of the sensor chip in the first direction,
The magnetic sensor, wherein the thickness of the magnetic body in the second direction varies depending on the position in the first direction.   Regarding the thickness of the magnetic body in the second direction, the thickness in the first region overlapping with the sensor chip when viewed from the third direction orthogonal to the element forming surface is the second region in which the thickness does not overlap with the sensor chip. 2. The magnetic sensor according to claim 1, wherein the magnetic sensor is thicker than the thickness in the region.   The thickness of the magnetic body in the second direction in the second direction is larger at the upper end portion away from the element formation surface than at the lower end portion near the element formation surface. The magnetic sensor according to claim 2.   When viewed from the third direction, the magnetic detection element has no overlap with the lower end portion of the magnetic body, and has an overlap with the upper end portion of the magnetic body. The magnetic sensor according to claim 3. Further comprising a magnetic shield covering the sensor chip and the magnetic body,
The magnetic shield is connected to first and second side wall portions sandwiching the sensor chip from the second direction and one end of the first side wall portion, and is directed toward the magnetic body in the second direction. A first top plate portion that extends, and a second top plate portion that is connected to one end of the second sidewall portion and that extends in the second direction toward the magnetic body,
The magnetic body is arranged in a gap formed by the tip of the first top plate portion and the tip of the second top plate portion without contacting the first and second top plate portions. The magnetic sensor according to claim 1, wherein:   The thickness of the magnetic body in the second direction is smaller than the thickness of the first region overlapping with the sensor chip when viewed from the third direction orthogonal to the element formation surface in a third region that does not overlap with the sensor chip. The magnetic sensor according to claim 5, wherein the region has a larger thickness.   The magnetic sensor according to claim 1, wherein the second direction is a scan direction of the member to be measured.

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