JP4863167B2 - Magnet structure and position detection apparatus using the same - Google Patents

Description

  The present invention relates to a magnet structure and a position detection device using the same, and more particularly to improve the linearity of a combined magnetic field in a boundary region between adjacent magnetic poles of a multipole magnetized permanent magnet. Related to technology.

  Development of a position sensor (position detection device) that accurately converts the motion of a relatively moving object into an appropriate signal and accurately controls its position has been developed. For example, a position monitoring device using a magnetic detection means and a magnet is being developed. It has been proposed (see, for example, Patent Document 1).

  In Patent Document 1, a position monitoring device for monitoring the positional relationship between a pair of members in which one member is movable with respect to another member along a fixed path is a magnetic device fixed to the one member. An adjacent magnetic field of a reverse polarity having a constant magnetic field intensity that spreads at an angle with the path is generated, thereby being substantially linear on a path extending across the adjacent portion of the magnetic field. The magnetic device is adapted to realize a magnetic field strength, and is fixed to the other member so that it can move along the extended path in response to relative movement of the two members. A magnetic field strength sensor device comprising the magnetic field strength sensor device, wherein the sensor device is adapted to provide a substantially linear response during the relative movement of the two members. Been That.

  The position monitoring device described in Patent Document 1 forms a region in which the magnetic flux density of the combined magnetic field changes linearly at the boundary of a dipole permanent magnet, and enables position control using this region. It is. In this position monitoring device, the magnetic sensor device also functions as a part of the control element of the electromagnetic actuator. For example, in addition to the control system of machine tools, the position monitoring device can be applied to various fields such as AV equipment and OA equipment. Expected.

  However, when the method described in Patent Document 1 is adopted, since the boundary area of the two-pole permanent magnet is perpendicular to the moving direction, the range in which the magnetic flux density of the combined magnetic field changes linearly is narrow, and position detection is performed. The function cannot be fully exerted, and only a minute position change can be detected. Along with miniaturization of various electronic devices, miniaturization of components mounted on these electronic devices has been promoted. However, the actual situation is that the above-mentioned problem becomes a major obstacle and uses are restricted.

  From such a situation, it has been attempted to enlarge a region where the magnetic flux density changes linearly (see, for example, Patent Document 2). In Patent Document 2, the S-pole and N-pole magnets arranged adjacent to each other and a member that can move relative to the magnets are fixed so as to be positioned between the magnets in the initial state. And at least one magnetic detection means for detecting the relative position of the member, and according to the relative position detection guarantee range between the magnet and the member between the S-pole and N-pole magnets. There is disclosed a position detecting device characterized in that a non-magnetic pole portion having a size is provided.

  In the invention described in Patent Document 2, a non-magnetic pole portion having a size corresponding to the relative position detection guaranteed range is provided between the S pole and the N pole, and, for example, the S pole and the N pole according to the width of displacement of the Hall element. A method is adopted in which a non-magnetic pole portion between the poles is widened, and further, a portion having a good linearity of output of a plurality of Hall elements is switched and controlled.

Or the technique which enables the position detection with a comparatively long stroke by arrange | positioning a magnetic pole diagonally is proposed (for example, refer patent document 3). In the invention described in Patent Document 3, a rectangular N-pole region is diagonally disposed between two S-poles, and the Hall element is moved in the longitudinal direction of the N-pole region so that the position of the N-pole region in the width direction is changed. The position is detected based on the change in the magnetic field strength due to the change in the influence of the two south poles.
JP 59-88602 A JP-A-8-136207 JP-A-6-11303

  However, as in the invention described in Patent Document 2, when the non-magnetic pole portion between the S pole and the N pole is widened, a continuous change is obtained in the magnetic flux density of the combined magnetic field, but the region having linearity is There is a possibility that the problem of not spreading so much may arise. In addition, in the method of switching and controlling the portions with a good linearity of the outputs of the plurality of Hall elements, the device configuration becomes complicated and there is a risk of increasing costs.

  On the other hand, as in the invention described in Patent Document 3, a rectangular N-pole region is obliquely disposed between two S-poles, and a magnetic flux is guided to the Hall element in a direction parallel to the magnetic pole surface by a magnetic flux guide. In the structure in which position detection is performed by relatively moving the element within the width of the N-pole region, it is not only necessary to prepare three magnetic media or three-pole magnetization, which complicates the magnetizing operation. It is necessary to magnetize the south pole in a well-balanced manner, and a separate magnetic flux guide is required, which also raises a problem of cost increase due to complicated apparatus configuration.

  The present invention has been proposed in view of such a conventional situation, and provides a magnet structure capable of improving the linearity of a composite magnetic field in a boundary region where different magnetic poles are adjacent to each other. Accordingly, it is an object of the present invention to provide a position detecting device capable of detecting a wide range of positions and obtaining a sufficient driving magnetic field. It is another object of the present invention to provide a magnet structure and a position detection device that can achieve the above object without using a plurality of magnetic detection means (for example, Hall elements) and having a simple configuration. And

In order to achieve the above-described object, the magnet structure of the present invention has a permanent magnet that is magnetized in a plurality of poles, and magnetic flux detection means arranged opposite to the permanent magnet has different magnetic poles of the permanent magnet. A magnet structure that moves relative to each other across an adjacent boundary region and detects a magnetic flux density component perpendicular to the magnetic pole surface of the permanent magnet, wherein the boundary region is the magnetic flux detection means. The inclination angle θ of the boundary region satisfies the relationship of 0.5 ≦ L · tan θ ≦ 6 with respect to the position detectable range L in the movement direction of the magnetic flux detection means. The overall shape of the permanent magnet is rectangular and partially cylindrical, and the magnetic flux detecting means moves in the circumferential direction of the permanent magnet. Further, the position detection device of the present invention is configured such that a permanent magnet magnetized with a plurality of poles and a different magnetic pole of the permanent magnet, which are disposed opposite to the permanent magnet, move relatively across a boundary region adjacent to each other. A position detection device including a magnetic flux detection means for performing position detection, wherein the boundary region is formed obliquely with respect to a moving direction of the magnetic flux detection means, and an inclination angle θ of the boundary region is the magnetic flux detection Satisfying the relationship 0.5 ≦ L · tan θ ≦ 6 with respect to the position detectable range L in the movement direction of the means, the entire shape of the permanent magnet is a rectangular shape and a partial cylindrical shape, and the magnetic flux detection means Angle detection is performed by moving in the circumferential direction of the permanent magnet.

  In the magnet structure and the position detection device of the present invention, a major characteristic point is that the boundary region between the magnetic poles different from each other is formed obliquely with respect to the moving direction of the magnetic flux detection means. By forming the boundary region diagonally, the linearity is improved. As a configuration for improving the linearity, it is only necessary to change the direction of the boundary region, the magnetization is easy, and the magnetization jig is simple. Further, for example, by adjusting the tilt angle, the output of the magnetic flux detection element can be easily adjusted.

  As described above, by using a magnet structure in which a region having linearity is expanded, the position detectable range is expanded without using a plurality of magnetic detection means (for example, Hall elements), and the device configuration can be simplified. Cost reduction is realized.

  In addition, as an example of arranging the magnetic poles diagonally, the position sensor device described in Patent Document 3 can be given. As described above, in the invention described in Patent Document 3, both sides of the N pole arranged diagonally are provided. It is necessary to arrange the S pole at the center, and the magnetic flux is guided to the Hall element in the direction parallel to the magnetic pole surface by the magnetic flux guide, and the Hall element is moved in the longitudinal direction of the N pole area, thereby moving the width of the N pole area. The basic principle is that the position is detected based on the change in magnetic flux density induced by the magnetic flux guide due to the change in the position in the direction and the influence of the two south poles. On the other hand, in the present invention, it is assumed that the magnetic flux detecting means moves across the boundary area between adjacent magnetic poles and different magnetic poles detect the magnetic flux density component perpendicular to the magnetic pole surface of the permanent magnet. The basic principle is to use the change in the magnetic field between two poles with a gap between them.

  In the magnet structure of the present invention, since the boundary region where the different magnetic poles are adjacent to each other is formed obliquely, it is possible to improve the linearity of the combined magnetic field in the boundary region. Therefore, by using the magnet structure of the present invention, it is possible to provide a position detection device capable of expanding the position detectable range. Further, in the position detection device of the present invention, since the range in which position detection is possible is expanded, for example, it is not necessary to use a plurality of magnetic detection means (Hall elements, etc.), and the device configuration can be simplified. It is also possible to reduce the cost.

  Hereinafter, a magnet structure to which the present invention is applied and a position detection apparatus using the same will be described in detail with reference to the drawings.

(First embodiment)
First, the basic configuration and position detection principle of a position detection apparatus using the magnet structure of the present invention will be described. FIG. 1 is a schematic diagram showing a basic structure of a position detection device. As shown in FIG. 1, the position detection device uses a permanent magnet 1 magnetized in multiple poles (here, two poles) as magnetic field generating means (magnet structure), and the magnetic poles (N pole 1 a and It comprises magnetic flux detecting means (for example, a Hall element) 2 that moves relative to the non-magnetized region 1c between the S poles 1b).

  The permanent magnet 1 constituting the magnet structure is a flat permanent magnet here, and is multipolar magnetized (bipolar magnetized) in the horizontal direction. That is, the surface of the left part in the figure is magnetized so as to be the N pole 1a, and the surface of the right part in the figure is magnetized so as to be the S pole 1b. In the case of multipolar magnetization (bipolar magnetization), a so-called neutral zone (non-magnetized region 1c) is generated at the boundary between the N pole 1a and the S pole 1b. Inevitable at the boundary of 1b. Note that the non-magnetized region 1c can be substantially eliminated by configuring the N pole 1a and the S pole 1b by combining a plurality (two) of permanent magnets. Here, one set of N pole 1a and S pole 1b is arranged, but a plurality of combinations of these N pole 1a and S pole 1b are arranged in the moving direction of the magnetic flux detection means 2 (lateral direction in the figure). It may be. In the magnet structure (permanent magnet 1) of the present embodiment, the N pole 1a and the S pole 1b that are different from each other are adjacent to each other across the neutral zone (the non-magnetized region 1c) to form a boundary region 1d. . More specifically, it shows between the peak value of the N pole and the peak value of the S pole by measuring the magnetic flux density.

  In the position detection by the magnetic flux detection means 2, the position detectable range becomes wider as the range of the linear change region of the magnetic flux density is wider. In addition, as the linearity (hereinafter referred to as linearity) of the linear change region of the magnetic flux density is improved, the position can be accurately detected with a simple calculation process. When the linearity of the linear change region of the magnetic flux density is low, accurate position detection is difficult unless a complicated calculation according to the surface magnetic flux density waveform is performed.

  Therefore, in the present embodiment, as shown in FIG. 2, in the permanent magnet 1, the boundary region 1 d is formed obliquely with respect to the moving direction of the magnetic flux detection means 2, so that each magnetic pole (N pole) of the permanent magnet 1 is formed. The width of the linear change region of the magnetic flux density is widened without reducing the generated magnetic field in 1a and the S pole 1b).

  Here, the inclination angle θ of the non-magnetized region 1c is 0.5 ≦ L · tan θ with respect to the moving direction (horizontal direction in the figure) of the magnetic flux detecting means 2 when the position detectable range is L. It is preferable to satisfy ≦ 6, and it is more preferable to satisfy 1 ≦ L · tan θ ≦ 4. If L · tan θ is less than 1, the magnetic flux density on the boundary region 1d becomes low, which may make detection difficult. On the other hand, if L · tan θ exceeds 6, the linearity may not be sufficiently improved. Here, L indicates the length of 90% of the distance between each pole peak position in the magnetic flux density measurement. The inclination angle θ is preferably 3 ° to 45 °, more preferably 5 ° to 30 ° with respect to the moving direction of the magnetic flux detection means 2 (horizontal direction in the figure). When the inclination angle θ is less than 3 °, the magnetic flux on the non-magnetized region 1c is lowered, and there is a possibility that detection is difficult. On the other hand, when the tilt angle θ exceeds 45 °, the linearity may not be sufficiently improved.

  The width w of the non-magnetized region 1c can be arbitrarily designed, but is preferably 0.0 mm to 2.5 mm, and more preferably 0.5 mm to 2.0 mm. If the width w of the non-magnetized region 1c exceeds 2.5 mm, the generated magnetic flux may be reduced.

  As a result of various studies, the present inventors have found that forming the boundary region 1d obliquely is extremely effective in widening the width of the magnetic flux density linear change region. Specifically, an experiment as described in Examples described later was performed, and the effect of forming the boundary region 1d obliquely was confirmed.

  The permanent magnet 1 having the non-magnetized region 1c formed obliquely can be realized by magnetizing one magnet with multiple poles. In this case, the non-magnetized region 1c may be formed diagonally by installing the permanent magnet 1 diagonally using a normal magnetizing apparatus, or having a yoke divided diagonally. Magnetization may be performed using a magnetic device, and the non-magnetized region 1c may be formed obliquely. Alternatively, a plurality (two) of permanent magnets can be combined. In this case, the gap between the combined permanent magnets corresponds to the non-magnetized region 1c.

  When the magnet structure of the present embodiment is used in a position detection device having a drive mechanism, the drive mechanism needs to be driven by the magnetic force of a (small) magnet, and therefore the permanent magnet 1 to be used is formed of a rare earth magnet. Is preferred. In particular, an RTB-based (R is a rare earth element, T is a transition metal element, and B is boron) sintered magnet having high magnetic properties, other Sm-Co-based sintered magnets, and the like are preferable. In the case of a position detection device that does not include a drive mechanism, a magnet body such as a rubber magnet can also be used.

  The magnet structure described above can be used in the position detection device described above. As shown in FIG. 1, the position detection device includes the above-described magnet structure (permanent magnet 1) and magnetic flux detection means 2 for detecting the magnetic field of the permanent magnet 1, and the magnetic flux detection means 2 is not included in the above-described configuration. It moves in the direction crossing the magnetized region 1c and detects the position based on the detected magnetic field. As the magnetic flux detection means 2, an MR sensor or the like can be used in addition to a Hall element. In the detection by the Hall element, a voltage proportional to the magnetic flux density can be output by applying a direct current, so that the circuit becomes simple, and detection is possible by the magnetic flux from the permanent magnet 1 even at a stopped position. It becomes.

  In the position detection device, the magnetic flux detection means 2 moves relative to the permanent magnet 1 and calculates the position based on the magnetic field strength detected at each position. In this case, the permanent magnet 1 may be fixed and the magnetic flux detection means 2 may be moved. Conversely, the magnetic flux detection means 2 may be fixed and the permanent magnet 1 may be moved. Further, as shown in FIG. 1, since the direction of magnetization in the permanent magnet 1 is fixed, the moving means can be moved by moving the detecting means 2 in one direction perpendicular or parallel to the permanent magnet side with respect to the permanent magnet 1. Can be uniaxial, and a simple structure can be obtained. When the drive mechanism for the relative movement is provided, for example, as shown in FIG. 3, the magnetic flux detection means 2 is installed on the substrate (nonmagnetic) 3 and the drive coil 4 is installed adjacent to the magnetic flux detection means 2. Then, the magnetic interaction between the driving coil 4 and the permanent magnet 1 is used as a driving force for relative movement. In this case, the substrate 3 on which the magnetic flux detection means 2 is installed may be moved relative to each other with the movable member as the movable member or with the installation side of the permanent magnet 1 as the movable member.

  In the magnet structure and the position detection device having the above-described configuration, the non-magnetized region 1c between the magnetic poles constituting the boundary region 1d is formed obliquely, so that the linearity (linearity) of the combined magnetic field is achieved in the boundary region. The range in which position detection is possible can be expanded.

(Second Embodiment)
In the present embodiment, the shape of the permanent magnet 1 is a partial cylindrical shape, and the magnetic flux detection means 2 is opposed to the circumferential surface of the cylindrical permanent magnet 1 and moved in the circumferential direction, thereby enabling angle detection. It is. Here, the partial cylindrical shape includes all of the shape of a part of the cylinder, and includes, for example, a so-called C-shape having a circular arc cross section.

  In FIG. 4, the arrangement | positioning state of the magnet structure (permanent magnet 1) and the magnetic flux detection means 2 of this embodiment is shown. In the case of this embodiment, the permanent magnet 1 is a C-shaped magnet having a circular arc cross section, and the surface facing the magnetic flux detection means 2 is cylindrical. The cylindrical peripheral surface is magnetized in two poles so that the surface of the left part in the figure is magnetized to be the N pole 1a, and the surface of the right part in the figure is the S pole 1b. Is magnetized.

  Also in the present embodiment, the non-magnetized region 1c is formed obliquely as in the first embodiment. In the case of this embodiment, when the cylindrical permanent magnet 1 is viewed in a plane, the non-magnetized region 1c is formed obliquely in a straight line. The inclination angle of the non-magnetized region 1c is 3 ° to 45 °, preferably 5 ° to 30 ° with respect to the moving direction of the magnetic flux detecting means 2, and the width w of the non-magnetized region 1c is 0.5 mm to 2 mm. .5 mm.

  In the present embodiment, as described above, the magnetic flux detection means 2 is opposed to the peripheral surface of the cylindrical permanent magnet 1 and moved in the circumferential direction to detect the position. Therefore, as shown in FIG. 5, the rotation angle α can be detected and functions as an angle sensor. For example, if the permanent magnet 1 is mounted on a rotating shaft and the angle is detected by the magnetic flux detecting means 2, the rotation angle of the rotating shaft can be detected.

  When the permanent magnet 1 has a partial cylindrical shape, the shape of the yoke used for dipole magnetization needs to match the shape of the peripheral surface of the permanent magnet. FIG. 6 shows an example of the shape of a magnetizing yoke for magnetizing the permanent magnet 1 having a cylindrical peripheral surface with two poles. Specifically, a magnetizing device in which a coil 7 is wound around two divided magnetizing yokes 5 and 6 is used, but the opposing surfaces 5a and 6a of the magnetizing yokes 5 and 6 facing the permanent magnet 1 are surrounded. A cylindrical curved surface (concave surface) is formed in accordance with the surface shape. The non-magnetized region 1c is formed by the gap between the magnetized yokes 5 and 6. However, as shown in FIG. 6B, the gap between the magnetized yokes 5 and 6 is formed obliquely in a straight line. That's fine. By performing dipole magnetization using such a magnetizing device, the permanent magnet 1 can be magnetized as shown in FIG.

  Even in the magnet structure and the position detection device of this embodiment, it is possible to increase the linearity of the combined magnetic field in the inter-magnetic pole region without reducing the magnetic field strength, as in the first embodiment. The same is true, and the detectable angle range can be expanded.

  Hereinafter, the effects of the present invention will be verified by experiments.

Experiment 1
First, a flat NdFeB-based sintered magnet was used as a permanent magnet, and this was two-pole magnetized. The used permanent magnet has a length of 10 mm in the direction of detecting the position in the detection region A, a width of 5 mm in the direction perpendicular to the direction of detecting the position, and a thickness of 2 mm. In addition, in the dipole magnetization, the non-magnetized region is formed obliquely. The non-magnetized region width is 1.5 mm, and the inclination angle θ is 10 °. This was designated as permanent magnet a.

  Bipolar magnetization was performed on the same permanent magnet so that the non-magnetized region was formed perpendicular to the moving direction of the magnetic flux detecting means. Further, dipole magnetization was performed by changing the width of the non-magnetized region. The permanent magnet b1 has a non-magnetized area width of 0.8 mm, the permanent magnet b2 has a non-magnetized area width of 1.5 mm, and the non-magnetized area width is 2.0 mm. The permanent magnet b3 is a permanent magnet b4, the permanent magnet b4 is a non-magnetized region width 3.0 mm, and the permanent magnet b5 is a non-magnetized region width 4.0 mm. The width of the non-magnetized region is a value measured by checking with a magnet viewer.

  The permanent magnet a and the permanent magnets b1, b2, b3, b4, and b5 were magnet structures, the Hall elements were arranged facing each other, and changes in magnetic flux density due to the movement of the Hall elements were examined. FIG. 7 shows the relationship between the distance from the center of the non-magnetized region of the permanent magnet and the magnetic flux density. As is clear from FIG. 7, the linearity (linearity) is remarkably improved in the permanent magnet a in which the non-magnetized region is formed obliquely, and the linearity is wide over a wide range of ± 3 mm or more from the center. Maintained. On the other hand, in the permanent magnets b1, b2, b3, b4, and b5 in which the non-magnetized region is formed substantially orthogonal to the moving direction of the magnetic flux detection means, the range in which linearity is obtained is significantly reduced. Further, when the width of the non-magnetized region is increased to 3.0 mm or more, an inflection point of the magnetic flux density can be seen within a range of ± 3 mm from the center.

  Next, dipolar magnetization was performed on the same permanent magnet so that the non-magnetized region was formed obliquely and the tilt angle was changed. The permanent magnet having an inclination angle of 5 ° was designated as b6, the permanent magnet having an inclination angle of 15 ° as b7, and the permanent magnet having an inclination angle of 45 ° as b8. Note that L · tan θ = 1.21 of the permanent magnet a, L · tan θ = 0.60 for the permanent magnet b6, L · tan θ = 1.83 for the permanent magnet b7, and L · tan θ = 5. 76. Table 1 shows the values of L · tan θ with respect to these inclination angles θ.

  Further, dipole magnetization was performed with the inclination angle fixed at 10 ° and the width of the non-magnetized region changed. B9 is a permanent magnet having a non-magnetized area width of 0.8 mm, b10 is a permanent magnet having a non-magnetized area width of 2.0 mm, and b11 is a permanent magnet having a non-magnetized area width of 3.0 mm. It was.

  FIG. 8 shows how the magnetic flux density changes when the tilt angle of the non-magnetized region is changed. As is apparent from FIG. 8, it was found that the generated magnetic flux is increased by increasing the tilt angle of the non-magnetized region. However, if the tilt angle becomes too large, a decrease in linearity is observed, and at a tilt angle of 45 °, the range where the straightness can be obtained is slightly narrowed. FIG. 9 shows how the magnetic flux density changes when the width of the non-magnetized region is changed. As can be seen from FIG. 9, the magnetic flux generated decreases as the width w of the non-magnetized region in the non-magnetized region increases, and the magnetic flux generated to reduce the width w of the non-magnetized region as much as possible. It proved advantageous in securing.

Experiment 2
A flat ferrite rubber magnet was used as the permanent magnet, and this was two-pole magnetized. The used permanent magnet has a length in the direction of detecting the position of 100 mm, a width perpendicular to the direction of detecting the position of 5 mm, and a thickness of 2 mm. Others were evaluated in the same manner as Experiment 1 in terms of changes in magnetic flux density. That is, the change in magnetic flux density when the width w of the non-magnetized region is 1.5 mm and the tilt angle θ is 1.0 ° is the tilt angle θ corresponding to the conventional example θ = 90 ° (w = 0.8 mm to 4.0 mm) and the change in magnetic flux density. Further, the change in magnetic flux density was investigated when the tilt angle θ of the non-magnetized region was fixed at 1.0 ° and the width w was set to 0.8 mm to 4.0 mm. Furthermore, the change in the magnetic flux density was investigated when the width w of the non-magnetized region was fixed to 1.5 mm and the tilt angle θ was 0.5 ° to 5.0 °. The values of L · tan θ with respect to the inclination angle θ of the non-magnetized region in the permanent magnet are shown in Table 2.

  The evaluation results are shown in FIG. 10, FIG. 11 and FIG. Also in this experiment, it was found that the linearity (linearity) was remarkably improved in the permanent magnet in which the non-magnetized region was formed obliquely, and the linearity was maintained over a wide range. Further, the magnetic flux generated when the width w of the non-magnetized region in the non-magnetized region is increased is reduced, which is advantageous in securing the generated magnetic flux by reducing the width w of the non-magnetized region as much as possible. I found out. Furthermore, it was found that the generated magnetic flux increases by increasing the tilt angle of the non-magnetized region. However, when the tilt angle becomes too large, the linearity is reduced. In Experiment 2, the range in which linearity can be obtained even at the tilt angle of 5 ° is narrow.

Experiment 3
An NdFeB-based sintered magnet having a partial cylindrical shape was used as a permanent magnet, and its peripheral surface was magnetized in two poles. The size of the permanent magnet used is 1 mm thick, the radius of curvature of the outer R surface is 16 mm, the length in the direction of detecting the position is 16 mm, and the height in the direction perpendicular to the direction of detecting the position is 8 mm. In addition, in the dipole magnetization, the non-magnetized region is formed obliquely. The width of the non-magnetized region is 1.5 mm, and the inclination angle θ is 10 °. This was designated as a permanent magnet c.

  Bipolar magnetization was performed on the same permanent magnet so that the non-magnetized region was formed substantially perpendicular to the moving direction of the magnetic flux detecting means. Further, dipole magnetization was performed by changing the width of the non-magnetized region. The permanent magnet d1 has a non-magnetized area width of 0.8 mm, the permanent magnet d2 has a non-magnetized area width of 1.5 mm, and the non-magnetized area width is 2.0 mm. The permanent magnet was a permanent magnet d3, the permanent magnet having a non-magnetized region width of 3.0 mm was a permanent magnet d4, and the permanent magnet having a non-magnetized region width of 4.0 mm was a permanent magnet d5. The width of the non-magnetized region is a value measured by checking with a magnet viewer.

  Further, dipolar magnetization was performed on the same permanent magnet so that a non-magnetized region was formed obliquely and the inclination angle was changed. The permanent magnet with an inclination angle of 5 ° was d6, the permanent magnet with an inclination angle of 15 ° was d7, and the permanent magnet with an inclination angle of 45 ° was d8. Further, dipole magnetization was performed with the inclination angle fixed at 10 ° and the width of the non-magnetized region changed. A permanent magnet having a non-magnetized region width of 0.8 mm is d9, a permanent magnet having a non-magnetized region width of 2.0 mm is d10, and a permanent magnet having a non-magnetized region width of 3.0 mm is d11. A permanent magnet having a non-magnetized region width of 4.0 mm was defined as d12.

  The permanent magnet c and the permanent magnets d1, d2, d3, d4, and d5 are magnet structures, which are mounted on a rotating shaft, and Hall elements are arranged to face each other, and a change in magnetic flux density accompanying rotation of the rotating shaft. I investigated. The relationship between the rotation angle of the permanent magnet (magnet rotation angle) and the magnetic flux density is shown in FIG.

  As is apparent from FIG. 13, the linearity (linearity) is remarkably improved in the permanent magnet c in which the non-magnetized region is formed obliquely, and the linearity is maintained up to around the magnet angle of 20 °. On the other hand, in the permanent magnets d1, d2, d3, d4, and d5 in which the non-magnetized region is formed substantially orthogonal to the moving direction of the magnetic flux detecting means, the linearity is remarkably lowered. Further, when the width of the non-magnetized region is increased to 4.0 mm, the linearity is obtained up to about a magnet angle of about 5 °, but the magnetic flux density is greatly reduced.

  Further, the change in the magnetic flux density was investigated when the width w of the non-magnetized region was fixed to 1.5 mm and the inclination angle θ was 5 ° to 45 °. Furthermore, the change in magnetic flux density was investigated when the tilt angle θ of the non-magnetized region was fixed at 10 ° and the width w was 0.8 mm to 4.0 mm. The results are shown in FIGS. Table 3 shows the value of L · tan θ with respect to the inclination angle θ of the non-magnetized region in the permanent magnet. Here, L is obtained by converting the angle between the peak positions into the length in the circumferential direction.

  As is clear from FIG. 14, when the value of L · tan θ decreases as the tilt angle decreases, the decrease in magnetic flux density increases. On the other hand, as the inclination angle increases and the value of L · tan θ increases, the range having linearity becomes narrower. Further, as apparent from FIG. 15, when the width of the non-magnetized region is larger than 3 mm, the decrease in the magnetic flux density is increased.

  Although the embodiments and examples to which the present invention is applied have been described above, the magnet structure and the position detection device of the present invention are not limited to these embodiments and examples, and do not depart from the gist of the present invention. Needless to say, various changes can be made.

It is a schematic perspective view which shows typically the position detection apparatus of 1st Embodiment. It is a schematic plan view which shows the magnetization state of a permanent magnet. It is a perspective view which shows schematic structure of the position detection apparatus provided with the drive coil. It is a schematic perspective view which shows typically the position detection apparatus of 2nd Embodiment. It is a schematic plan view which shows the movement state of the magnetic flux detection means in 2nd Embodiment. An example of the magnetizing apparatus for magnetizing the permanent magnet which has a cylindrical surface 2 poles is shown, (a) is a schematic perspective view, (b) is a schematic plan view. In Experiment 1, the change in magnetic flux density when the width w of the non-magnetized region is 1.5 mm and the tilt angle θ is 10 ° is the tilt angle θ corresponding to the conventional example θ = 90 ° (w = 0.8 mm to It is a characteristic view shown in comparison with the change of the magnetic flux density in the case of 4.0 mm). In Experiment 1, it is a characteristic view which shows the change of the magnetic flux density when the width w of the non-magnetized region is fixed to 1.5 mm and the inclination angle θ is 5 ° to 45 °. In Experiment 1, it is a characteristic figure which shows the change of the magnetic flux density in case the inclination-angle (theta) of a non-magnetized area | region is fixed to 10 degrees, and width w is 0.8 mm-3.0 mm. In Experiment 2, the change in magnetic flux density when the width w of the non-magnetized region is 1.5 mm and the tilt angle θ is 1.0 ° is the tilt angle θ corresponding to the conventional example θ = 90 ° (w = 0.0). It is a characteristic view shown compared with the change of the magnetic flux density at the time of setting it as 8 mm-4.0 mm). In Experiment 2, it is a characteristic figure which shows the change of the magnetic flux density in case the inclination-angle (theta) of a non-magnetization area | region is fixed to 1.0 degree, and width w is 0.8 mm-4.0 mm. In Experiment 2, it is a characteristic view which shows the change of the magnetic flux density when the width w of the non-magnetized region is fixed to 1.5 mm and the tilt angle θ is 0.5 ° to 5 °. In Experiment 3, the change in magnetic flux density when the width w of the non-magnetized region is 1.5 mm and the tilt angle θ is 10 ° is the tilt angle θ corresponding to the conventional example θ = 90 ° (w = 0.8 mm to It is a characteristic view shown in comparison with the change of the magnetic flux density in the case of 4.0 mm). In Experiment 3, it is a characteristic view which shows the change of the magnetic flux density when the width w of the non-magnetized region is fixed to 1.5 mm and the inclination angle θ is 5 ° to 45 °. In Experiment 3, it is a characteristic figure which shows the change of the magnetic flux density in case the inclination-angle (theta) of a non-magnetization area | region is fixed to 10 degrees, and width w is 0.8 mm-4.0 mm.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Permanent magnet, 1a N pole, 1b S pole, 1c Non-magnetization area | region, 1d boundary area | region, 2 Magnetic flux detection means, 3 Board | substrate, 4 Drive coil, 5, 6 Magnetization yoke, 5a, 6a Opposite surface

Claims (3)

A magnetic flux detecting means having a permanent magnet magnetized on a plurality of poles and relatively moving across the boundary region where the different magnetic poles of the permanent magnet are adjacent to each other, A magnet structure in which position detection is performed by detecting a magnetic flux density component perpendicular to the magnetic pole surface,
The boundary area is formed obliquely with respect to the movement direction of the magnetic flux detection means, and the inclination angle θ of the boundary area is 0.5 ≦ L with respect to the position detectable range L in the movement direction of the magnetic flux detection means. Satisfies the relationship tan θ ≦ 6,
The magnet structure according to claim 1, wherein the permanent magnet has a rectangular shape and a partial cylindrical shape, and the magnetic flux detection means moves in a circumferential direction of the permanent magnet . A permanent magnet magnetized on a plurality of poles; and a magnetic flux detection means for detecting a position by moving relative to each other across a boundary region where the different magnetic poles of the permanent magnet are arranged opposite to each other and adjacent to the permanent magnet. A position detecting device,
The boundary area is formed obliquely with respect to the movement direction of the magnetic flux detection means, and the inclination angle θ of the boundary area is 0.5 ≦ L with respect to the position detectable range L in the movement direction of the magnetic flux detection means. Satisfies the relationship tan θ ≦ 6,
The position detection device according to claim 1, wherein the permanent magnet has a rectangular shape and a partial cylindrical shape, and angle detection is performed by moving the magnetic flux detection means in a circumferential direction of the permanent magnet . The position detecting device according to claim 2, wherein the magnetic flux detecting means is a Hall element.

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