Magnetic sensor unit

Abstract

The magnetic sensor unit comprises: a magnet; a magnetic sensor arranged to be opposite to the lower surface of the magnet; a magnetic shield arranged to surround the magnetic sensor in a lateral direction intersecting the vertical direction of the magnetic sensor; and a yoke covering the upper surface and side surfaces of the magnet. The magnet comprises: a first magnetized region magnetized in the vertical direction, and a second magnetized region magnetized in a direction opposite to the first magnetized region. The first and second magnetized regions form a first magnetic pole and a second magnetic pole, respectively, on the lower surface of the magnet. The distance LA from the center of the first magnetic pole to the center of the second magnetic pole, the distance LB from the center of the first magnetic pole to the magnetic shield, and the distance LC from the center of the second magnetic pole to the magnetic shield satisfy the relationship LA<LB+LC. The magnetic sensor unit has magnetic shielding properties and is small.

Description

Technical Field

[0001] The present disclosure relates to a magnetic sensor unit for detecting a rotation angle of a rotation shaft. Background Art

[0002] The magnetic sensor unit that detects the rotation angle of the rotating shaft is equipped with a magnetic shield to suppress the influence of the external magnetic field. For example, Patent Document 1 discloses a structure in which a yoke is arranged on a magnet to increase the magnetic flux density and obtain a magnetic shielding effect. Patent Document 2 discloses a structure in which a shielding shell covering the magnet and the magnetic sensor is provided.

[0003] Prior Art Literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2007-263585

[0006] Patent Document 2: Japanese Patent Application Laid-Open No. 2-99823 Summary of the invention

[0007] The magnetic sensor unit comprises: a magnet; a magnetic sensor arranged to be opposed to the lower surface of the magnet; a magnetic shield surrounding the magnetic sensor in a lateral direction intersecting the vertical direction of the magnetic sensor; and a magnetic yoke covering the upper surface and side surfaces of the magnet. The magnet has a first magnetized region magnetized in the vertical direction and a second magnetized region magnetized in a direction opposite to the first magnetized region. The first magnetized region and the second magnetized region form a first and a second magnetic pole, respectively, on the lower surface of the magnet. The distance LA from the center of the first magnetic pole to the center of the second magnetic pole, the distance LB from the center of the first magnetic pole to the magnetic shield, and the distance LC from the center of the second magnetic pole to the magnetic shield satisfy the relationship LA<LB+LC.

[0008] The magnetic sensor unit has magnetic shielding properties and is small. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 : is a schematic cross-sectional view of the magnetic sensor unit in the embodiment.

[0010] Figure 2 It is a cross-sectional view of the magnetic sensor of the magnetic sensor unit in the embodiment.

[0011] Figure 3 yes Figure 2 The block diagram of the circuit module of the magnetic sensor is shown.

[0012] Figure 4 Yes means Figure 2 FIG. 1 is a diagram showing the signal processing operation in the control circuit of the magnetic sensor shown.

[0013] Figure 5 This is a graph showing the relationship between the magnetic field strength and the angle accuracy of various magnetic sensors.

[0014] Figure 6 It is a bottom view of the magnet of the magnetic sensor unit in the embodiment.

[0015] Figure 7 yes Figure 6 A cross-sectional view of the magnet shown along line VII-VII.

[0016] Figure 8 It is a diagram showing the magnetic field distribution of the magnet in the embodiment.

[0017] Fig. 9 It is a figure which shows the magnetic density distribution of the lower surface of the magnet in embodiment.

[0018] Fig.10 It is a figure which shows the magnetization method of the magnet in embodiment.

[0019] Fig.11 It is a diagram showing the magnetic field distribution of a magnet attached with a yoke in the embodiment.

[0020] Fig.12 yes Figure 1 An enlarged cross-sectional view of a magnetic sensor unit is shown.

[0021] Fig.13 It is an enlarged cross-sectional view of another magnetic sensor unit in the embodiment. DETAILED DESCRIPTION

[0022] Hereinafter, the magnetic sensor unit involved in the embodiment of the present disclosure is described using the accompanying drawings. In addition, the embodiments described below all represent a preferred specific example of the present disclosure. Therefore, the shape, structural elements, configuration of structural elements, and connection methods shown in the following embodiments are examples and are not intended to limit the present disclosure. Therefore, among the structural elements in the following embodiments, the structural elements that are not recorded in the independent claims representing the highest concept of the present invention are described as arbitrary structural elements.

[0023] In addition, each drawing is a schematic diagram and is not necessarily a strictly illustrated drawing. In each drawing, the same reference numerals are given to substantially the same structure, and repeated descriptions are omitted or simplified.

[0024] Figure 1: is a cross-sectional view of a magnetic sensor unit in an embodiment. The magnetic sensor unit 100 has a magnet 10, a magnetic sensor 20, a yoke 30, and a magnetic shield 40. The magnet 10 is connected to the front end of a rotating shaft 1 extending along a rotating axis 1a extending in the up-down direction D1, and rotates together with the rotating shaft 1. The magnetic sensor 20 detects the direction of the magnetic field formed by the magnet 10 in the detection area, which is the area between the magnet 10 and the magnetic sensor 20, that is, the detection magnetic field. The magnetic shield 40 blocks the external magnetic field acting from the outside of the magnetic sensor unit 100 so that it does not penetrate the magnetic shield 40 and prevents it from reaching the magnetic sensor 20. The yoke 30 increases the magnetic flux density in the magnet 10 applied to the magnetic sensor 20.

[0025] Figure 2 2 is a cross-sectional view of the magnetic sensor 20. The magnetic sensor 20 includes a magnetoresistive element 21 and a circuit element 22. Figure 2 , as a specific structure of the magnetic sensor 20, a magnetoresistive element 21 and a circuit element 22 are arranged inside a resin molded body 23 and integrated as an example. The circuit element 22 is mounted on a die pad 24. The magnetoresistive element 21 is mounted on the circuit element 22. The magnetoresistive element 21 and the circuit element 22 are electrically connected by a bonding wire 25. The circuit element 22 is connected to a lead 26 by the bonding wire 25.

[0026] Figure 3 2 is a block diagram of a circuit module of the magnetic sensor 20 . Figure 4: This is a diagram showing the signal processing action in the circuit module. The magnetoresistive element 21 has a bridge circuit BR1 and a bridge circuit BR2 including magnetoresistive elements MR1 ​​to MR8. The magnetoresistive elements MR1 ​​to MR8 have resistances that change according to the applied magnetic field. The bridge circuits BR1 and BR2 are Wheatstone bridge circuits. The bridge circuit BR1 has: a series body BR1a composed of magnetoresistive elements MR1 ​​and MR2 connected in series at a connection point N13, and a series body BR1b composed of magnetoresistive elements MR3 and MR4 connected in series at a connection point N14. The series bodies BR1a and BR1b are connected in parallel with the connection points N11 and N12 between the connection points N11 and N12. The bridge circuit BR2 has: a series body BR2a composed of magnetoresistive elements MR5 and MR6 connected in series at a connection point N23, and a series body BR2b composed of magnetoresistive elements MR7 and MR8 connected in series at a connection point N24. The series bodies BR2a and BR2b are connected in parallel with the connection points N21 and N22 between the connection points N21 and N22. The connection points N11 and N21 are connected to the reference potential Vc, and the connection points N12 and N22 are connected to the ground (GND). In addition, the magnetic resistances MR1 ​​to MR8 are formed by anisotropic magnetic resistances. The anisotropic magnetic resistances can be formed by a metal pattern with a magnetic resistance effect including an iron-nickel alloy. The resistance of the anisotropic magnetic resistance changes according to the change in the direction and size of the detected magnetic field. The circuit element 22 detects the potential of the connection points N13 and N14 of the bridge circuit BR1 and the potential of the connection points N23 and N24 of the bridge circuit BR2.

[0027] In the magnetic sensor 20, the bridge circuit BR1 may be replaced by using only one of the series body BR1a and the series body BR1b. The bridge circuit BR2 may be replaced by using only one of the series body BR2a and the series body BR2b. For example, when the magnetic sensor 20 does not include the series bodies BR1b and BR2b but includes the series bodies BR1a and BR2a, the circuit element 22 detects the potentials of the connection points N13 and N23.

[0028] Magnetic sensors using anisotropic magnetoresistance can detect areas with greater magnetic field strength than magnetic sensors using other elements. In addition, as the magnetic field strength increases, the deformation of the output waveform is eliminated, and the detected electrical signal is close to the ideal value. Therefore, in areas with greater magnetic field strength, magnetic sensors using anisotropic magnetoresistance (AMR) have higher angle detection accuracy than magnetic sensors using giant magnetoresistance (GMR), magnetic sensors using tunnel magnetoresistance (TMR), and magnetic sensors using Hall elements.

[0029] Figure 5The relationship between the strength of the magnetic field applied to the magnetic sensor using different types of elements and the accuracy of the detected angle is shown in FIG. Figure 5 As shown, the angle accuracy of the magnetic sensor using AMR increases as the magnetic field strength increases. The angle accuracy of the magnetic sensor using GMR decreases when the magnetic field strength is 80mT or more. This is a problem caused by the ideal magnetic field strength range of 60 to 80mT for the pin layer of GMR. The angle accuracy of the magnetic sensor using TMR decreases when the magnetic field strength is 80mT or more. This is also a problem caused by the ideal magnetic field strength range of 30 to 50mT for the pin layer of TMR elements. The magnetic sensor using Hall elements requires multi-stage amplification processing because the detection output is small. Therefore, there is a problem that the deviation of the measured angle becomes larger relative to the change of the detection magnetic field. Therefore, the magnetic sensor using anisotropic magnetoresistor can set the detection magnetic field larger, so the influence of the interference magnetic field is relatively small. As a result, the magnetic sensor can perform high-precision detection with a large S / N.

[0030] The series body of the magnetic resistance MR1 and the magnetic resistance MR2, and the series body of the magnetic resistance MR3 and the magnetic resistance MR4 of the bridge circuit BR1 are connected in series between the reference potential Vc and the ground GND. The potential of the connection point N13, which is the middle potential between the magnetic resistances MR1 ​​and MR2, is output as a detection signal sin+. The potential of the connection point N14, which is the middle potential between the magnetic resistances MR3 and MR4, is output as a detection signal sin-.

[0031] The series body of the magnetic resistor MR5 and the magnetic resistor MR6, and the series body of the magnetic resistor MR7 and the magnetic resistor MR8 of the bridge circuit BR2 are connected in parallel between the reference potential Vc and the ground GND. The potential of the connection point N23, which is the middle potential between the magnetic resistors MR5 and MR6, is output as the detection signal cos+. The potential of the connection point N24, which is the middle potential between the magnetic resistors MR7 and MR8, is output as the detection signal cos-.

[0032] In addition, the bridge circuit BR1 and the bridge circuit BR2 are configured such that the phase of the detection signal cos+ is 90° different from the detection signal sin+ and the phase of the detection signal cos- is 90° different from the detection signal sin- with respect to the rotation of the detection magnetic field.

[0033] The circuit element 22 includes differential amplifiers 27a and 27b and an arithmetic processing unit 28. In the description of the circuit element 22, only the minimum configuration necessary for the description of the present disclosure is described, and the circuit element 22 is not limited to this configuration.

[0034] The signal sin+ and the signal sin- output from the bridge circuit BR1 are input to the differential amplifier 27a. The differential amplifier 27a generates and outputs an amplified signal sin based on the input signal sin+ and the signal sin-. In the embodiment, the differential amplifier 27a generates the amplified signal sin by subtracting the signal sin- from the signal sin+.

[0035] The signal cos+ and the signal cos- output from the bridge circuit BR2 are input to the differential amplifier 27b. The differential amplifier 27b generates and outputs the amplified signal cos based on the input signal cos+ and the signal cos-. In the embodiment, the differential amplifier 27b generates the amplified signal cos by subtracting the signal cos- from the signal cos+.

[0036] The signal sin output from the differential amplifier 27a and the signal cos output from the differential amplifier 27b are input to the operation processing unit 28. The operation processing unit 28 performs arctan operation on the input signal sin and the signal cos. The operation processing unit 28 outputs the signal arctan subjected to the arctan operation. In the embodiment, the operation processing unit 28 outputs the quotient obtained by dividing the signal cos by the signal sin as the signal arctan. The magnetic sensor 20 outputs the signal arctan from the circuit element 22. The signal arctan has rotation information including the rotation angle of the magnet 10.

[0037] Figure 6 It is a bottom view of the magnet 10 . Figure 7 yes Figure 6 1 is a cross-sectional view of the magnet 10 shown at line VII-VII. The magnet 10 includes a disk-shaped permanent magnet having a circular upper surface 10a and a lower surface 10b. The magnet 10 has a side surface 10c connected to the upper surface 10a and the lower surface 10b and surrounding the upper surface 10a and the lower surface 10b as a whole. The magnet 10 has a magnetized region 11 and a magnetized region 12 connected to each other. The magnetized region 11 is a semicircular portion that divides the magnet 10 into two when viewed from above. The magnetized region 12 is the other semicircular portion in the magnet 10 when viewed from above. The magnetized regions 11 and 12 are arranged in a parallel direction D2a that is orthogonal to the up-down direction D1.

[0038] The magnetized region 11 is magnetized in a magnetization direction 11d which is a lower direction D12 in the upper and lower directions D1. An upper region 11a of the magnetized region 11 is an S pole, and a lower region 11b of the magnetized region 11 is an N pole.

[0039] The magnetized region 12 is magnetized in a magnetization direction 12d of the upper direction D11 of the upper and lower directions D1. The magnetization direction 12d of the magnetized region 12 is opposite to the magnetization direction 11d of the magnetized region 11. The region 12b on the lower side of the magnetized region 12 is an S pole, and the region 12a on the upper side of the magnetized region 12 is an N pole. In addition, although the regions are distinguished by dotted lines in the figure, the regions are distinguished by the distribution of magnetic poles. Figure 7 As shown, the magnetized region 11 forms an N pole, namely, the magnetic pole P1b, on the lower surface 10b of the magnet 10, and the magnetized region 12 forms an S pole, namely, the magnetic pole P2b, which is the opposite polarity of the magnetic pole P1b, on the lower surface 10b of the magnet 10. Similarly, the magnetized region 11 forms an S pole, namely, the magnetic pole P1a, on the upper surface 10a of the magnet 10, and the magnetized region 12 forms an N pole, namely, the magnetic pole P2a, which is the opposite polarity of the magnetic pole P1a, on the upper surface 10a of the magnet 10.

[0040] Figure 8 , the magnetic field distribution of the magnet 10 is shown in the figure. The magnetic force lines Ma on the upper surface side of the magnet 10 in the figure are from the magnetic pole P2a of the region 12a in the magnetization region 12 toward the magnetic pole P1a of the region 11a in the magnetization region 11. The magnetic force lines Mb on the lower surface side of the magnet 10 in the figure are from the magnetic pole P1b of the region 11b in the magnetization region 11 toward the magnetic pole P2b of the region 12b in the magnetization region 12. The magnetic force lines Mc1 on the left side of the magnet 10 in the figure are from the region 11b in the magnetization region 11 toward the region 11a. The magnetic force lines Mc2 on the right side of the magnet 10 in the figure are from the region 12a in the magnetization region 12 toward the region 12b. In this way, the magnetic field distribution of the magnet 10 spreads less to the side.

[0041] Fig. 9 : represents the magnetic density distribution at the lower surface 10b of the magnet 10. Fig. 9 As shown, the center 11c of the magnetic pole P1b of the magnetized region 11 is the part with the largest magnetic density in the magnetic pole P1b of the magnetized region 11. The center 12c of the magnetic pole P2b of the magnetized region 12 is the part with the largest magnetic density in the magnetic pole P2b of the magnetized region 12. The center 11c of the magnetic pole P1b can be regarded as being located at a distance of 1 / 2 of the radius Rr of the lower surface 10b from the center of the lower surface 10b of the magnet 10 in the juxtaposition direction D2a in which the magnetized regions 11 and 12 are arranged. The center 12c can be set to be located at a distance of 1 / 2 of the radius Rr from the center of the lower surface 10b in the juxtaposition direction D2a.

[0042] Fig.10An example of a magnetizing method of the magnet 10 is shown by a schematic diagram. The magnet 10 can be magnetized by magnetizing a magnetic body 10x formed into a disk shape by a magnetic material such as ferrite. The magnetizing device 50 includes a magnetizing portion 51 and a magnetizing portion 52. The magnetizing portion 51 on the left side of the figure can apply a downward magnetic field 51a to the left half of the magnetic body 10x. The magnetizing portion 52 on the right side of the figure can apply an upward magnetic field 52a to the right half of the magnetic body 10x. By magnetizing the magnetic body 10x using the magnetizing device 50, a magnetic body having Figure 7 A magnet 10 of the polarity shown.

[0043] Fig.11 The figure shows the magnetic field distribution of the magnet 10 equipped with the yoke 30. The yoke 30 includes a ferromagnetic body such as pure iron. The yoke 30 is configured to cover the entire upper surface 10a and the side surface 10c so as to abut against the upper surface 10a and the side surface 10c of the magnet 10. In other words, the outer surface of the magnet 10 except the lower surface 10b of the magnet 10 facing the magnetic sensor 20 is covered. By covering the magnet 10 with the yoke 30, the magnetic field of the covered part passes through the inside of the yoke 30, and the diffusion of the magnetic field can be suppressed. Furthermore, at the exposed lower surface 10b of the magnet 10, the magnetic flux density of the detection magnetic field Md becomes larger. For example, the magnetic field strength at the detection area of ​​the magnet 10 equipped with the yoke 30, the magnet 10 not equipped with the yoke 30, and the two-pole magnet not equipped with the yoke 30 are compared. In the detection area separated by 3mm from the magnet, the magnetic field strength of the magnet 10 equipped with the yoke 30 is about 120mT. The magnetic field strength of the magnet 10 without the yoke 30 is about 90 mT. The magnetic field strength of the two-pole magnet without the yoke 30 is about 40 mT. Thus, the magnet 10 with the yoke 30 in the present disclosure can apply a large detection magnetic field Md to the magnetic sensor 20.

[0044] By increasing the magnetic field strength of the detection magnetic field Md applied to the magnetic sensor 20, the influence of the disturbance magnetic field becomes relatively small. As a result, the magnetic sensor 20 can perform high-precision detection with a large S / N. However, since the detection magnetic field Md becomes large, it is preferable to use anisotropic magnetoresistance for the magnetic sensor 20.

[0045] The magnetic shield 40 is made of a ferromagnetic material such as pure iron. The magnetic shield 40 is arranged to surround the magnetic sensor 20 in a lateral direction D2 perpendicularly intersecting the vertical direction D1 of the magnetic sensor 20. The magnetic shield 40 has an annular shape surrounding the magnetic sensor 20 in a plan view. Fig.121 is an enlarged cross-sectional view of the magnetic sensor unit 100. The center 11c of the magnetic pole P1b of the magnetized region 11 is separated from the center 12c of the magnetic pole P2b of the magnetized region 12 by a distance LA. The center 11c of the magnetic pole P1b of the magnetized region 11 is separated from the magnetic shield 40 by a distance LB. The center 12c of the magnetic pole P2b of the magnetized region 12 is separated from the magnetic shield 40 by a distance LC. In the magnetic sensor unit 100, the distances LA, LB, and LC satisfy the relationship LA<LB+LC. By satisfying this relationship in the positional relationship between the magnet 10 and the magnetic shield 40, the magnetic shield 40 can be made small.

[0046] That is, the detection magnetic field Md in the magnetic sensor unit 100 is as follows: Fig.11 As shown, from the center 11c of the magnetic pole toward the center 12c of the magnetic pole. The detection area that forms the detection magnetic field Md is formed in the air, so the magnetic permeability of the detection area is 1. On the other hand, the magnetic shield 40 is formed by a ferromagnetic body, and its magnetic permeability exceeds 1000. Therefore, the influence of the magnetic resistance of the magnetic shield 40 can be ignored. Therefore, the magnetic resistance in the air from the center 11c of the magnetic pole P1b to the center 12c of the magnetic pole P2b is smaller than the magnetic resistance from the center 11c of the magnetic pole P1b through the magnetic shield 40 to the center 12c of the magnetic pole P2b. Thus, the magnetic saturation of the magnetic shield 40 caused by the magnetic field formed by the magnet 10 can be suppressed, so that the radial miniaturization of the magnetic shield 40 can be achieved. Specifically, by satisfying the above-mentioned relationship LA<LB+LC, as Figure 1 As shown, the outer peripheral end of the magnetic shield 40 can be arranged on the inner side than the outer peripheral end of the yoke 30 in a plan view.

[0047] In addition, although there is a gap between the magnetic shield 40 and the magnet 10 , the external magnetic field Me is absorbed by the magnetic shield 40 and the yoke 30 having large magnetic permeability, and thus has no influence on the detection area.

[0048] In addition, by miniaturizing the magnetic shield 40, the magnetic sensor 20 and the magnetic shield 40 can be mounted on the base substrate 60. This can suppress the variation in the interval between the magnetic sensor 20 and the magnetic shield 40. In other words, in assembling a plurality of magnetic sensor units 100, the variation in the detection accuracy of each magnetic sensor unit 100 can be reduced.

[0049] The yoke disclosed in Patent Document 1 contains a ferromagnetic metal, which can enhance the detection magnetic field. However, the yoke is magnetically saturated by the magnetic field of the magnet, so the magnetic shielding effect cannot be expected. The shielding shell disclosed in Patent Document 2 needs to be separated from the detection magnet in order to suppress the influence of the magnetic field of the magnet, which makes the device larger.

[0050] Next, a modification of the magnetic sensor unit 100 will be described.

[0051] (Variation Example)

[0052] Fig.13 FIG. 2 is an enlarged cross-sectional view of another magnetic sensor unit 200 which is a modified example of the embodiment. Fig.13 In, with Figures 1 to 12 The same reference numerals are used for the same parts as the magnetic sensor unit 100 and the description thereof is simplified. The magnetic sensor unit 200 includes a magnetic shield 70 instead of the magnetic shield 40 of the magnetic sensor unit 100 , and the other structures of the magnetic shield 70 are the same as those of the magnetic sensor unit 100 .

[0053] The inner diameter of the magnetic shield 70 in the magnetic sensor unit 200 is larger than the outer diameter of the yoke 30, and is configured so that the magnetic shield 70 surrounds the outer periphery of the yoke 30 in a plan view. In addition, the upper end of the magnetic shield 70 is configured to be located higher than the lower end of the yoke 30. In other words, in the magnetic sensor unit 200, the detection area is surrounded by the magnetic shield 70. In addition, the partially narrow portion RL of the magnetic shield 70 facing the yoke 30 forms a labyrinth structure. The labyrinth structure formed by the magnetic shield 70 and the yoke 30 can prevent dust such as iron powder from intruding into the detection area from the external space of the magnetic sensor unit 200.

[0054] In addition, in the structure where the magnetic shield 70 surrounds the yoke 30, if the interval LR between the inner periphery of the magnetic shield 70 and the outer periphery of the yoke 30 is large, the dustproof effect becomes small. In addition, if the interval LR is small, it becomes difficult to assemble the magnetic sensor unit 200. In addition, in particularizing these conditions, by satisfying the two conditions of LE×1.5>LD>LE×1.2 and LG×0.5>LF>0 for the inner diameter LD of the magnetic shield 70, the outer diameter LE of the yoke 30, the height difference LF from the lower end of the yoke 30 to the upper end of the magnetic shield 70 in the vertical direction D1, and the height LG of the magnet 10 in the vertical direction D1, it is possible to take into account both the dustproof effect and the ease of assembly.

[0055] In addition, the structure of the magnetic shield 70 also satisfies the relationship LA<LB+LC described by the magnetic sensor unit 100, and the magnetic saturation of the magnetic shield 70 can be suppressed. In addition, the magnetic field of the upper surface 10a and the side surface 10c of the magnet 10 in contact with the yoke 30 is as follows: Fig.11 As shown, the magnetic shield 70 is enclosed inside the yoke 30. Therefore, as long as the magnetic shield 70 and the yoke 30 are not in contact, magnetic saturation of the magnetic shield 70 can be suppressed.

[0056] In the embodiments, terms indicating directions such as "upper surface", "lower surface", "upper and lower directions", and "looking down" indicate relative directions determined only by the relative positional relationship of the components of the magnetic sensor unit such as the magnet and the magnetic sensor, and do not indicate absolute directions such as the vertical direction.

[0057] Industrial Applicability

[0058] The magnetic sensor unit in the present disclosure has magnetic shielding properties and is small in size, and is particularly effective as a magnetic sensor unit for vehicle-mounted use.

[0059] -Explanation of symbols-

[0060] 1 Rotation axis

[0061] 1a Axis of rotation

[0062] 10 Magnet

[0063] 11, 12 Magnetized area

[0064] 20 Magnetic sensor

[0065] 30 Yoke

[0066] 40, 70 Magnetic Shielding Parts

[0067] 60 Base substrate

[0068] 100, 200 Magnetic Sensor Units

[0069] P1a, P1b, P2a, P2b Magnetic poles

[0070] MR1~MR8 Magnetic resistance

[0071] BR1, BR2 bridge circuit

[0072] BR1a, BR1b, BR2a, BR2b series.

Claims

1. A magnetic sensor unit, comprising: A magnet having an upper surface, a lower surface, and a side surface connected to the upper surface and the lower surface; a magnetic sensor configured to be opposite to the lower surface of the magnet; a magnetic shield configured to surround the magnetic sensor in a lateral direction intersecting the up-down direction of the magnetic sensor; and a yoke covering the upper surface and the side surface of the magnet, The magnetic sensor includes an anisotropic magnetoresistance to which a detection magnetic field generated by the magnet is applied, The magnet has: a first magnetized region, which is magnetized in the up-down direction and forms a first magnetic pole on the lower surface of the magnet; and a second magnetized region which is magnetized in a direction opposite to the first magnetized region and forms a second magnetic pole on the lower surface of the magnet; A distance LA from the center of the first magnetic pole to the center of the second magnetic pole, a distance LB from the center of the first magnetic pole to the magnetic shield, and a distance LC from the center of the second magnetic pole to the magnetic shield satisfy the relationship LA<LB+LC, In a plan view, an outer peripheral end of the magnetic shield is arranged on the inner side than an outer peripheral end of the yoke.

2. A magnetic sensor unit comprising: A magnet having an upper surface, a lower surface, and a side surface connected to the upper surface and the lower surface; a magnetic sensor configured to be opposite to the lower surface of the magnet; a magnetic shield configured to surround the magnetic sensor in a lateral direction intersecting the up-down direction of the magnetic sensor; and a yoke covering the upper surface and the side surface of the magnet, The magnetic sensor includes an anisotropic magnetoresistance to which a detection magnetic field generated by the magnet is applied, The magnet has: a first magnetized region, which is magnetized in the up-down direction and forms a first magnetic pole on the lower surface of the magnet; and The second magnetized region is magnetized in a direction opposite to the first magnetized region and forms a second magnetic pole on the lower surface of the magnet. A distance LA from the center of the first magnetic pole to the center of the second magnetic pole, a distance LB from the center of the first magnetic pole to the magnetic shield, and a distance LC from the center of the second magnetic pole to the magnetic shield satisfy the relationship LA<LB+LC, In a plan view, the outer peripheral end of the magnetic shield is arranged outside the outer peripheral end of the yoke. The upper end of the magnetic shield is located above the lower end of the magnetic yoke. The inner diameter LD of the magnetic shield, the outer diameter LE of the yoke, the height difference LF from the lower end of the yoke to the upper end of the magnetic shield in the vertical direction, and the height LG of the magnet satisfy the relationship of LE×1.5>LD>LE×1.2 and LG×0.5>LF>0.

3. The magnetic sensor unit according to claim 1 or 2, wherein: The magnetic sensor unit further includes a base substrate connected to the magnetic sensor and the magnetic shield.

4. The magnetic sensor unit according to claim 1 or 2, wherein: The magnet rotates around a rotation axis extending in the up-down direction.

5. The magnetic sensor unit according to claim 1 or 2, wherein: The yoke abuts against the upper surface and the side surface of the magnet.

6. The magnetic sensor unit according to claim 1 or 2, wherein: The magnet is connected to the front end of the rotating shaft.

Images