JP2009192261A - Linear displacement detector - Google Patents

Abstract

An inexpensive and highly accurate linear displacement detection device is provided.
A linear displacement detector 30 detects a magnetic field and a magnetic material 20 in which N pole and S pole magnetic pole regions 21, 22, 23, 24, and 25 are alternately arranged in a straight line on a surface 20a. The magnetic material has a magnetic surface, and the magnetic sensitive surface is arranged so as to face the surface 20a of the magnet material 20. The magnetic material 20 and the magnetic field detection device 10 have N poles of the magnet material 20. Relative movement is possible in parallel along the arrangement direction of the magnetic pole regions 21, 24, 25 and the magnetic pole regions 22, 23 of the S pole.
[Selection] Figure 1

Description

  The present invention relates to a linear displacement detection device capable of detecting a linear displacement of an object.

  As an apparatus for detecting a linear displacement of an object, for example, there is a linear displacement detection apparatus described in Non-Patent Document 1. The linear displacement detection apparatus described in Non-Patent Document 1 includes a magnet material in which N-pole regions and S-pole regions are alternately arranged in a line on the surface, and magnetic field detection means for detecting a magnetic field formed by the magnet material. The magnet material and the magnetic field detecting means are configured to be relatively movable in parallel along the arrangement direction of the N-pole region and the S-pole region of the magnet material. Specifically, the magnetic field detection means used in the linear displacement detection device described in Non-Patent Document 1 is MLX90316 manufactured by Melexis.

  FIG. 18 is a diagram illustrating a specific positional relationship between the magnet material and the magnetic field detection unit included in the linear displacement detection device 100 described in Non-Patent Document 1. The magnetic field detection means 10 can be realized by a Hall IC mounted on the substrate 11. FIG. 2 is a diagram for explaining the configuration of the magnetic field detection means 10. The magnetic field detection means 10 is provided with a soft magnetic plate 12 having a magnetosensitive surface 12 a and a plurality of Hall elements 13 disposed in the vicinity of the end of the soft magnetic plate 12. The magnetic field detection means 10 is arranged so that the magnetic sensitive surface 12a of the magnetic field detection means 10 is orthogonal to the surface 20a of the magnet material 20 in which the N pole regions 21, 24, 25 and the S pole regions 22, 23 are arranged. Has been. That is, the magnetic detection means 10 described in Non-Patent Document 1 detects a magnetic field parallel to the magnetosensitive surface 12a (parallel to the XY plane of FIG. 2). And the magnetic detection means 10 detects the magnetic field component of the two directions in the magnetosensitive surface 12a in the Hall element 13, calculates the direction of the magnetic field applied to the Hall element from them, and outputs a signal according to the magnetic field angle. Output. The range of magnetic field angles that can be detected is 360 ° (less than).

Japan Society for Invention and Innovation Open Technical Bulletin No. 2006-503396

However, when the positional relationship between the magnetic field detection means 10 and the magnet material 20 is as shown in FIG. 18, the gap G between the magnetic material 20 and the Hall element 13 is at least the package size of the magnetic field detection means 10. 1/2 or more is necessary. Considering the layout of wiring on the substrate 11, a gap G of at least about 4 mm is required. In order to apply a sufficient magnetic field from the magnet material 20 to the Hall element 13 provided with a gap G of about 4 mm, an expensive magnet having a strong magnetic force such as NdFeB is required. As a result, the linear displacement detection device 100 is used. There is a problem that the cost of the increases.
In addition, when realizing a linear displacement detector having a resolution high enough to detect a small stroke (several millimeters) of relative movement, the width of the N-pole region and the S-pole region is narrowly arranged according to the detection stroke. (It is possible to widen the detection magnetic field angle range within the detection stroke). However, if the widths of the N-pole region and the S-pole region are narrowed, the magnetic field that can be detected by the Hall element becomes small, and the detection accuracy may be lowered.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an inexpensive and highly accurate linear displacement detection device.

In order to achieve the above object, the linear displacement detection device according to the present invention is characterized by a magnet material in which N pole and S pole magnetic pole regions are alternately arranged in a straight line on the surface, and
A magnetic field detecting means having a magnetic sensitive surface for detecting a magnetic field, the magnetic sensitive surface being arranged facing the surface of the magnet material,
The magnet material and the magnetic field detection means are capable of relative movement in parallel along the arrangement direction of the N-pole magnetic pole region and the S-pole magnetic pole region of the magnet material.

According to the above characteristic configuration, since the magnetic sensitive surface of the magnetic field detecting means is arranged to face the surface of the magnet material, the gap between the magnetic sensitive surface of the magnetic field detecting means and the surface of the magnet material can be freely adjusted. . In particular, the gap can be made smaller than in the prior art. Therefore, even if the magnetic force of the magnet material is small, the magnetic field distribution formed by the magnet material can be detected well by the magnetic field detection means by adjusting the gap. That is, since the magnetic force of the magnet material may be small, an expensive magnet with strong magnetic force such as NdFeB is not required.
Therefore, an inexpensive and highly accurate linear displacement detector can be provided.

  Another characteristic configuration of the linear displacement detection device according to the present invention is that the distribution of the magnetization strength of the magnet material in the direction along the arrangement direction of the N-pole magnetic pole region and the S-pole magnetic pole region is sinusoidal. There is a point.

  According to the above characteristic configuration, the distribution of magnetization intensity in the magnet material is sinusoidal, that is, the center of each magnetic pole region has the strongest magnetization intensity, and the magnetization gradually weakens toward the periphery. Therefore, the distribution of the strength of the magnetic field formed outside the magnet material also becomes a sine wave distribution along the relative movement direction. Therefore, since the strength of the magnetic field does not change abruptly according to the relative movement amount between the magnet material and the magnetic field detection means, the accuracy of the magnetic field angle derived by the magnetic field detection means that detects the magnetic field becomes high, and the derived magnetic field angle Based on this value, it is possible to accurately derive the relative position of the two.

  Another characteristic configuration of the linear displacement detection device according to the present invention is that the magnet material has a non-magnetized region between the N-pole magnetic pole region and the S-pole magnetic pole region.

  According to the above characteristic configuration, by providing the non-magnetized region between the N-pole magnetic pole region and the S-pole magnetic pole region, the non-magnetized region between the N-pole magnetic pole region and the S-pole magnetic pole region The change of the magnetic field in the vicinity becomes relatively slow. Therefore, since the strength of the magnetic field does not change abruptly according to the relative movement amount between the magnet material and the magnetic field detection means, the accuracy of the magnetic field angle derived by the magnetic field detection means that detects the magnetic field becomes high, and the derived magnetic field angle Based on this value, it is possible to accurately derive the relative position of the two.

Another characteristic configuration of the linear displacement detection device according to the present invention is such that the widths in the direction along the arrangement direction of the magnetic pole regions arranged other than the end of the magnet material are the same,
The width in the direction along the arrangement direction of the magnetic pole region arranged at the end of the magnet material is the width in the direction along the arrangement direction of the magnetic pole region arranged at a position other than the end of the magnet material. It is in the point which is 1/2 to 2/3.

  According to the above characteristic configuration, the magnetic field generated by the magnetic pole region provided at the end is suppressed from being dominant. That is, it is possible to prevent the magnetic field distribution formed outside the magnet material from becoming non-uniform.

<First Embodiment>
The linear displacement detection device 30 according to the first embodiment will be described below with reference to the drawings.
FIG. 1 is a diagram illustrating a specific positional relationship between the magnet material 20 and the magnetic field detection means 10 included in the linear displacement detection device 30 of the first embodiment. FIG. 2 is a diagram for explaining the configuration of the magnetic field detection means 10. The linear displacement detection device 30 includes a magnet material 20 and a magnetic field detection means 10. In the present embodiment, the magnetic field detection means 10 can be realized by a Hall IC mounted on the substrate 11. For example, a Hall IC such as MLX90333 manufactured by Melexis can be used. The magnet material 20 is formed using a ferrite magnet or the like, and N pole and S pole magnetic pole regions 21, 22, 23, 24, and 25 are arranged alternately and linearly on the surface 20 a. FIG. 1 illustrates a magnet material 20 composed of five magnetic pole regions. The tip side of the arrow drawn in each magnetic pole region is the N pole. Therefore, in the example shown in FIG. 1, three N-pole regions (N-pole magnetic pole regions) 21, 24, 25 and two S-pole regions (S-pole magnetic pole regions) 22, 23 are arranged alternately. The surface 20 a of the magnet material 20 facing the magnetic field detection means 10. Each magnetic pole region is obtained by magnetizing an anisotropic magnet.

  The magnetic field detection means 10 has a magnetosensitive surface 12a for detecting a magnetic field. Specifically, the magnetic field detection means 10 includes a soft magnetic plate 12 that is formed of a circular soft magnetic material and forms the magnetosensitive surface 12a, and a plurality of magnetic plates that are disposed in the vicinity of the end of the soft magnetic plate 12. Hall element 13 (13a, 13b, 13c, 13d). In the present embodiment, four Hall elements 13 are provided on the chip 14 in such a form that they are located directly below the end of the soft magnetic plate 12. The soft magnetic plate 12 is provided on the chip 14 so as to cover a part of each Hall element 13 from above. As shown in the figure, the four Hall elements 13 are arranged at 90 ° intervals around the circular soft magnetic plate 12. A pair of Hall elements 13a and 13b are arranged along the X axis, and another pair of Hall elements 13c and 13d are arranged along the Y axis. The magnetosensitive surface 12a of the soft magnetic plate 12 is parallel to the XY plane.

  In the present embodiment, the magnetic field detection means 10 is arranged such that the magnetosensitive surface 12 a faces the surface 20 a of the magnet material 20. Further, the magnet material 20 and the magnetic field detection means 10 are relatively movable in parallel along the arrangement direction of the N pole regions 21, 24, 25 and the S pole regions 22, 23 of the magnet material 20. Referring to FIGS. 1 and 2, the magnet material 20 and the magnetic field detection means 10 are relatively movable in parallel to the X-axis direction shown in FIG. Therefore, the magnetic field detection means 10 has the strength of the magnetic field component in the direction parallel to the relative movement direction detected by the Hall elements 13a and 13b (X-axis direction) and the direction perpendicular to the relative movement direction detected by the Hall elements 13a and 13b. The direction of the magnetic field (magnetic field angle) is derived from the strength of the magnetic field component in the (Z-axis direction), and the relative position between the magnet material 20 and the magnetic field detection means 10 in the magnetic field direction is detected.

  Specifically, a magnetic field distribution is formed around the magnet material 20. Since the magnetic material 20 is formed by alternately arranging the N pole regions 21, 24, 25 and the S pole regions 22, 23 in a straight line, the magnetic field distribution to be formed is also the N pole regions 21, 24, 25. And it changes periodically corresponding to the arrangement state of the S pole regions 22 and 23. Therefore, the magnetic flux density detected by the magnetic field detection means 10 is represented by the sum (W1 + W2) of the width W1 of the N pole regions 21, 24, 25 and the width W2 of the S pole regions 22, 23 in the relative movement direction. The displacement changes as one cycle. Therefore, if the magnetic field detection means 10 memorize | stores the relationship between the relative position of the magnet material 20 and the magnetic field detection means 10, and the magnetic field angle in the relative position, both will be based on the value of the derived magnetic field angle. It is possible to derive the relative position.

Next, the principle of magnetic field detection in the three directions of X axis, Y axis, and Z axis orthogonal to each other by the magnetic field detection means 10 will be described. In the present embodiment, magnetic field detection in the X-axis direction and magnetic field detection in the Z-axis direction are performed. FIG. 3 is a cross-sectional view of the magnetic field detection means 10 and shows the state of the magnetic flux according to the applied magnetic field with a solid line.
The magnetic field component in the Y-axis direction is detected as follows. That is, as shown in FIG. 3B, when a magnetic field component in the Y-axis direction is applied, the magnetic flux is bent by the soft magnetic plate 12, and a pair of Hall elements 13c and 13d arranged along the Y-axis direction. Generates a magnetic field component in the Z-axis direction perpendicular to the soft magnetic plate 12. At this time, the magnitude of the magnetic field component in the Z-axis direction is proportional to the magnitude of the external magnetic field, and the direction of the generated magnetic field component is opposite in the Hall element 13c and the Hall element 13d. Therefore, the magnetic field component proportional to the magnitude of the external magnetic field in the Y-axis direction can be detected by calculating the difference between the output voltages of the pair of Hall elements 13c and 13d.

  When a magnetic field component in the X-axis direction is applied, a magnetic field component in the Z-axis direction perpendicular to the soft magnetic plate 12 is generated in the same manner as when a magnetic field component in the Y-axis direction is applied. Therefore, the magnetic field detection means 10 can detect the magnitude of the magnetic field component in the X-axis direction by calculating the difference between the output voltages of the pair of Hall elements 13a and 13b arranged along the X-axis direction.

When detecting the magnetic field component in the Y-axis direction, the magnetic field component in the Z-axis direction is removed as follows. As shown in FIG. 3A, when a magnetic field component in the Z-axis direction is applied, the pair of Hall elements 13c and 13d arranged along the Y-axis direction has a Z-axis direction perpendicular to the soft magnetic plate 12. The magnetic field component of is generated. At this time, the direction of the generated magnetic field component is the same in the Hall element 13c and the Hall element 13d. Therefore, the magnetic field component in the Z-axis direction can be removed by calculating the difference between the output voltages of the pair of Hall elements 13c and 13d.
Similarly, when detecting the magnetic field component in the X-axis direction, the magnetic field component in the Z-axis direction can be removed by calculating the difference between the output voltages of the pair of Hall elements 13a and 13b.

  On the other hand, the magnetic field component in the Z-axis direction is detected as follows. That is, as described above, when a magnetic field component in the Z-axis direction is applied, the directions of the magnetic field components generated in the pair of Hall elements 13c and 13d arranged along the Y-axis direction are the same direction. Therefore, the magnetic field detection means 10 can detect the magnitude of the magnetic field component in the Z-axis direction by calculating the sum of the output voltages of the pair of Hall elements 13c and 13d arranged along the Y-axis direction.

  When detecting the magnetic field component in the Z-axis direction, the magnetic field component in the Y-axis direction is removed as follows. That is, as described above, when a magnetic field component in the Y-axis direction is applied, the direction of the generated magnetic field component is opposite in the pair of Hall elements 13c and Hall element 13d arranged along the Y-axis direction. . Accordingly, the magnetic field component in the Y-axis direction can be removed by calculating the sum of the output voltages of the pair of Hall elements 13c and 13d. The same is possible when removing the magnetic field component in the X-axis direction.

  As described above, the magnetic field detection means 10 can separately detect the magnetic field component in the X-axis direction, the magnetic field component in the Y-axis direction, and the magnetic field component in the Z-axis direction, so that the magnetic field detection in the XY plane, the XZ plane, and the YZ plane can be performed. It becomes possible separately.

Below, the detection result of the linear displacement using the linear displacement detection apparatus 30 of 1st Embodiment is demonstrated.
As shown in FIG. 1, the magnet material 20 has three N-pole regions 21, 24, 25 and two S-pole regions 22, 23 alternately. In this embodiment, the widths in the direction along the arrangement direction of the magnetic pole regions of the magnet material 20 are the same. That is, the width W1 of the N-pole regions 21, 24, 25 and the width W2 of the S-pole regions 22, 23 are equal to each other, and both are 6 mm. Each magnetic pole region has a height L of 3 mm and a depth of 5 mm. Therefore, the linear displacement detection device 30 can detect a linear displacement (that is, relative movement between the magnet material 20 and the magnetic field detection means 10) within a range of 12 mm.
FIG. 4 is a graph (simulation result) of magnetic flux density detected by the magnetic field detection means 10 while relatively moving the magnetic material 20 and the magnetic field detection means 10 using such a magnetic material 20. Since this measurement was performed by changing the gap G between the surface 20a of the magnet material 20 and the Hall element 13 of the magnetic field detection means 10, the result is also shown. The horizontal axis of FIG. 4 shows the amount of displacement in the relative movement direction between the magnet material 20 and the magnetic field detection means 10. A state where the center of the soft magnetic plate 12 and the center of the N-pole region 21 of the magnet material 20 are opposed to each other is the origin (displacement amount = 0). The vertical axis of FIG. 4 shows the magnetic flux density detected by the magnetic field detection means 10.

  As shown in FIG. 4, when the gap G is changed between 1.5 mm and 7 mm, the magnetic flux density that can be detected by the magnetic field detection means 10 decreases as the gap G increases. A desirable magnetic flux density range for detection for the magnetic field detection means 10 used in the present embodiment is about 0.02T to about 0.07T. As apparent from the graph of FIG. 4, the magnetic flux density is substantially uniform within a range of 12 mm (−6 mm to +6 mm in the figure), which is a detection target range of the linear displacement of the linear displacement detector 30. Therefore, when the magnetic field detection means 10 of 1st Embodiment is used, the magnetic flux density in the magnetic flux density range desirable for the said detection can be detected in the range where the gap G is 2 mm to 3.5 mm.

  FIG. 5A shows the relationship between the amount of displacement in the relative movement direction between the magnetic material 20 and the magnetic field detection means 10 and the magnetic field angle (deg: °) calculated from the detection result (simulation) of the magnetic field detection means 10. It is a graph to show. As apparent from FIG. 5A, the relationship between the displacement and the magnetic field angle is a relatively linear shape, and the magnetic material 20 and the magnetic field detection means 10 are derived from the magnetic field angle derived by the magnetic field detection means 10. It can be seen that the relative position can be derived. This result is commonly obtained when the gap G is 1.5 mm to 2.5 mm. FIG. 5B shows the amount of displacement in the relative movement direction between the magnet material 20 and the magnetic field detection means 10 and the fluctuation of the magnetic field angle from an arbitrary reference line, that is, the non-linearity (deg :) of the magnetic field angle. It is a graph which shows a relationship with (degree). When the relationship between the displacement and the magnetic field angle is completely linear, the non-linearity shown in FIG. 5B shows 0, but in the example shown in FIG. 5B, there is some non-linearity. You can see that

  As described above, by using the linear displacement detection device 30 of the first embodiment, the magnetically sensitive surface 12a of the magnetic field detection means 10 can be disposed so as to face the surface 20a of the magnetic material 20, so that the magnetic field detection means 10 The gap between the magnetosensitive surface 12a and the surface 20a of the magnet material 20 can be freely adjusted. In particular, the gap can be made smaller than in the prior art. Therefore, even if the magnetic force of the magnet material 20 is small, the magnetic field distribution formed by the magnet material 20 can be detected well by the magnetic field detection means 10 by adjusting the gap. That is, since the magnetic force of the magnet material 20 may be small, an expensive magnet having a strong magnetic force such as NdFeB is not required.

Second Embodiment
The linear displacement detection device 50 of the second embodiment is different from the linear displacement detection device of the first embodiment in the configuration of the magnet material. The configuration of the linear displacement detection device 50 of the second embodiment will be described below, but the description of the same configuration as that of the first embodiment will be omitted.

  FIG. 6 is a diagram for explaining a specific positional relationship between the magnet material 40 and the magnetic field detection means 10 included in the linear displacement detection device 50 according to the second embodiment. The configuration of the magnetic field detection means 10 is the same as that described in the first embodiment. The magnet material 40 is formed by using an anisotropic magnet, and the N pole region 41 is arranged on the surface 40a by alternately arranging the N pole and S pole magnetic pole regions 41, 42, 43, 44, and 45 in a straight line. , 44, 45 and the S pole regions 42, 43 have a non-magnetized region 46. Specifically, the width W1 of the N-pole regions 41, 44, 45 and the width W2 of the S-pole regions 42, 43 are equal to each other, and all are 3 mm. Further, the width W3 of the non-magnetized region 46 was 3 mm. The height L of each region is 3 mm and the depth is 5 mm.

  FIG. 7A shows the relationship between the amount of displacement in the relative movement direction between the magnet material 40 and the magnetic field detection means 10 and the magnetic field angle (deg: °) calculated from the detection result (simulation) of the magnetic field detection means 10. It is a graph to show. FIG. 7B shows the amount of displacement in the relative movement direction between the magnet material 40 and the magnetic field detection means 10 and the fluctuation of the magnetic field angle from an arbitrary reference line, that is, the non-linearity (deg :) of the magnetic field angle. It is a graph which shows a relationship with (degree).

  By providing the non-magnetized region 46 between the N pole regions 41, 44, 45 and the S pole regions 42, 43 as in the present embodiment, the N pole regions 41, 44, 45 and the S pole regions 42, 43 are provided. In the vicinity of the non-magnetized region 46 between the two, the magnetic field direction does not change abruptly. As a result, as is clear from FIGS. 7A and 7B, the relationship between the displacement and the magnetic field angle is more linear than in the first embodiment. It can be seen that the relative position between the magnet material 40 and the magnetic field detection means 10 can be derived appropriately from the magnetic field angle derived by. This result is commonly obtained in any case where the gap G is 1.5 mm to 2.5 mm.

  As described above, by providing the non-magnetized region 46 between the N-pole regions 41, 44, 45 and the S-pole regions 42, 43, the N-pole regions 41, 44, 45 and the S-pole regions 42, 43 The change in the magnetic field direction in the vicinity of the non-magnetized region 46 between the two becomes relatively gradual. Therefore, the accuracy of the magnetic field angle derived by the magnetic field detection means 10 is increased. Therefore, the magnetic field detection means 10 can accurately derive the relative position of both based on the derived magnetic field angle value.

<Third Embodiment>
The linear displacement detection device of the third embodiment is characterized in that the distribution of the magnetization intensity of the magnet material in the direction along the arrangement direction of the N-pole magnetic pole region and the S-pole magnetic pole region is sinusoidal. Specifically, an isotropic magnet is used, and magnetization is performed so that the magnetization intensity distribution inside the magnet material 20 becomes a sine wave distribution along the relative movement direction. For example, the magnetic field is magnetized so that the center of each magnetic pole region has the strongest magnetization and gradually becomes weaker toward the periphery. As a result, as will be described later, the distribution of the strength of the magnetic field formed outside the magnet material 20 is also sinusoidal along the relative movement direction.
The apparatus configuration other than the magnet material 20 is the same as that of the linear displacement detection apparatus of the first embodiment.

  FIG. 8 is a graph showing the relationship between the position in the relative movement direction between the magnet material 20 and the magnetic field detection means 10 and the strength (simulation result) of the magnetic field component in the direction from the magnet material 20 toward the magnetic field detection means 10. Specifically, FIG. 8A is a simulation result when the anisotropic magnet described in the first embodiment is used, and FIG. 8B is a case where the isotropic magnet of this embodiment is used. This is a simulation result. In addition, only the magnetic field component by the part of S pole area | region 22, N pole area | region 21, and S pole area | region 23 is illustrated.

  Regardless of whether an anisotropic magnet or an isotropic magnet is used, the strength of the magnetic field component is positive at a position corresponding to the N pole region (width W1 = 6 mm) between about -3 mm and about +3 mm. Thus, the strength of the magnetic field component becomes negative at a position corresponding to the S pole region (width W2 = 6 mm) between about −9 mm and about −3 mm and between about +3 mm and about +9 mm.

  When the magnet material 20 is formed using an anisotropic magnet, as shown in FIG. 8A, the vicinity of the boundary between the N pole regions 21, 24, 25 and the S pole regions 22, 23 (the position is − In the vicinity of 3 mm and +3 mm), the intensity of the magnetic field component changes abruptly. On the other hand, the magnetic field around the center of the N-pole regions 21, 24, 25 (around 0mm) and around the center of the S-pole regions 22, 23 (around -6mm and + 6mm) is changed even if the position changes. The strength of the ingredients has not changed significantly. That is, when the magnetic material 20 is formed using an anisotropic magnet, the intensity of the magnetic field component in the direction from the magnetic material 20 toward the magnetic field detection means 10 does not change uniformly according to the change in position. Specifically, the strength of the magnetic field component does not change greatly according to the change in the region (near the boundary between the N-pole region and the S-pole region) where the strength of the magnetic field component changes greatly according to the change in the position. Regions (the central portion of the N-pole region and the central portion of the S-pole region) exist.

On the other hand, when the magnet material 20 is formed using an isotropic magnet, as shown in FIG. 8B, the change in the strength of the magnetic field component is sinusoidal. The intensity of the magnetic field component in the direction from the magnet material 20 toward the magnetic field detection means 10 changes relatively uniformly according to the change in position. Further, even if the gap G is reduced, the strength of the magnetic field component changes relatively clearly when the position changes.
Therefore, when the magnet material 20 is formed using an isotropic magnet, the accuracy of the magnetic field angle derived by the magnetic field detection means 10 is increased. Therefore, based on the value of the derived magnetic field angle, the relative position between the two is determined. Can be accurately derived. In the case where the strength of the magnetic field component in the direction from the magnet material 20 to the magnetic field detection means 10 does not change uniformly according to the change in position, as in the case where the magnet material is formed using an anisotropic magnet. Even if correction is made, the accuracy of deriving the magnetic field angle can be improved.
In the present embodiment, an example in which the magnet material 20 is formed using an isotropic magnet has been described. However, the magnetic material 20 is oriented by orienting the magnetic powder so that the distribution of the strength of magnetization becomes a sinusoidal distribution. There is also a method of forming, and the obtained effect is the same as when an isotropic magnet is used. Further, also in the magnet material 40 of the linear displacement detection device of the second embodiment, the distribution of the magnetization intensity of the magnet material in the direction along the arrangement direction of the N pole magnetic region and the S magnetic pole region is sinusoidal. You may make it become.

<Fourth embodiment>
In the fourth embodiment, the width W1 of the N-pole regions 21, 24, 25 and the width W2 of the S-pole regions 22, 23 of the magnet material 20 shown in FIG. 1 are compared to the case described in the first embodiment. This is an example of a linear displacement detection device that is also narrow. Specifically, the width W1 of the N pole regions 21, 24, 25 is 2 mm, and the width W2 of the S pole regions 22, 23 is 2 mm. Therefore, in this linear displacement detection device, the linear displacement within the range of 4 mm (that is, the relative movement between the magnet material 20 and the magnetic field detection means 10) can be detected with high accuracy. However, the magnetic field formed outside the magnetic pole region is also reduced by the reduction of each magnetic pole region, so that the small magnetic field needs to be accurately detected by the magnetic field detection means 10.

  FIG. 9 is a graph (simulation result) of magnetic flux density detected by the magnetic field detection means 10 while relatively moving the magnetic material 20 and the magnetic field detection means 10 using such a magnetic material 20. Since this measurement was performed by changing the gap G between the surface 20a of the magnet material 20 and the Hall element 13 of the magnetic field detection means 10, the result is also shown. The horizontal axis of FIG. 9 shows the amount of displacement of the magnet material 20 and the magnetic field detection means 10 in the relative movement direction. A state where the center of the soft magnetic plate 12 and the center of the N-pole region 21 of the magnet material 20 are opposed to each other is the origin (displacement amount = 0). The vertical axis of FIG. 9 shows the magnetic flux density detected by the magnetic field detection means 10.

  A desirable magnetic flux density range for detection by the magnetic field detection means 10 is about 0.02T to about 0.07T. As is clear from the graph of FIG. 9, the magnetic flux density is substantially uniform within a range of 4 mm (−2 mm to +2 mm in the figure), which is a linear displacement detection target range of the linear displacement detector. Therefore, as is apparent from FIG. 9, when the magnetic field detection means 10 of the fourth embodiment is used, the magnetic flux within the magnetic flux density range desirable for the above detection if the gap G is in the range of 1.6 mm to 2.0 mm. Can detect density. Therefore, a linear displacement detector capable of detecting the linear displacement with high accuracy is obtained.

<Fifth Embodiment>
In the fifth embodiment, the widths in the direction along the direction of arrangement of the magnetic pole regions other than the ends of the magnet material are the same as each other, and the arrangement of the magnetic pole regions arranged at the ends of the magnet material This is an example of a linear displacement detection device in which the width in the direction along the direction is smaller than the width in the direction along the arrangement direction of the magnetic pole regions arranged at the portions other than the end portions.
In the following description, a case where a magnet material is formed using an anisotropic magnet will be described. However, in the arrangement direction of the N-pole magnetic pole region and the S-pole magnetic pole region as described in the third embodiment. Even in the magnet material in which the distribution of the magnetization strength of the magnet material in the direction along the sine wave is sinusoidal, the widths in the direction along the arrangement direction of the magnetic pole regions arranged other than the ends of the magnet material are the same, You may make it the width | variety of the direction along the arrangement direction of the magnetic pole area | region arranged at the edge part of a magnet material become smaller than the width | variety along the arrangement direction of the magnetic pole area | region arrange | positioned other than an edge part.

[When there are three magnetic pole regions]
FIG. 10 is a diagram illustrating a magnet material 60 having three magnetic pole regions. As shown in the figure, S pole regions (S pole magnetic pole regions) 62 and 63 (width W2) are arranged at the ends of the magnet material 60, and N pole regions (N pole magnetic pole regions) 61 other than the ends. (Width W1) is arranged. Other apparatus configurations such as the magnetic field detection means 10 are the same as those in the above embodiment.

Hereinafter, in the magnet material 60 of FIG. 10, the case where the width of the S pole regions 62 and 63 at the end: W2 = ½ × W1 will be described.
FIG. 11A shows a magnet material 60 and a magnetic field using the magnet material 60 in which the widths of the south pole regions 62 and 63 at the ends: W2 = 1/2 × W1 in the magnet material 60 of FIG. It is a graph (simulation result) of the magnetic flux density detected by the magnetic field detection means 10 while moving the detection means 10 relatively. However, W1 = 2 mm and W2 = 1 mm. Each magnetic pole region has a height L of 3 mm and a depth of 5 mm. Therefore, this linear displacement detection device is configured to detect a linear displacement within a range of 4 mm (within a range of −2 mm to +2 mm in the drawing). Moreover, since this measurement was performed by changing the gap G between the surface 60a of the magnet material 60 and the Hall element 13 of the magnetic field detection means 10, the result is also shown. The horizontal axis of FIG. 11A shows the amount of displacement in the relative movement direction between the magnet material 60 and the magnetic field detection means 10. The state where the center of the soft magnetic plate 12 and the center of the N-pole region 61 of the magnet material 60 are opposed to each other is the origin (displacement = 0). The vertical axis of FIG. 11A shows the magnetic flux density detected by the magnetic field detection means 10.

  As shown in FIG. 11A, when the gap G is changed between 0.8 mm and 2.4 mm, the magnetic flux density that can be detected by the magnetic field detection means 10 decreases as the gap G increases. A desirable magnetic flux density range for detection for the magnetic field detection means 10 used in the present embodiment is about 0.02T to about 0.07T. As is clear from the graph of FIG. 11A, when the gap G is reduced, the magnetic flux density is within a range of 4 mm (-2 mm to +2 mm in the figure), which is a detection target range of the linear displacement of the linear displacement detector. Is almost uniform. Therefore, in this case, the magnetic flux density within the magnetic flux density range desirable for the detection can be detected when the gap G is in the range of 1.8 mm to 2.2 mm.

  FIG. 11B shows the relationship between the amount of displacement in the relative movement direction between the magnet material 60 and the magnetic field detection means 10 and the magnetic field angle (deg: °) calculated from the detection result (simulation) of the magnetic field detection means 10. It is a graph to show. As is clear from FIG. 11B, the relationship between the displacement and the magnetic field angle is substantially linear, and the relative position between the magnet material 60 and the magnetic field detection means 10 from the magnetic field angle derived by the magnetic field detection means 10. It can be seen that can be derived appropriately.

Next, in the magnet material 60 of FIG. 10, the case where the width of the S pole regions 62 and 63 at the end portion is W2 = 2/3 × W1 will be described.
FIG. 12A shows a magnetic material 60 and a magnetic field using the magnetic material 60 in which the widths of the south pole regions 62 and 63 at the ends: W2 = 2/3 × W1 in the magnetic material 60 of FIG. It is a graph (simulation result) of the magnetic flux density detected by the magnetic field detection means 10 while moving the detection means 10 relatively. However, W1 = 2 mm and W2 = 1.33. Therefore, this linear displacement detection device is configured to detect a linear displacement within a range of 4 mm (within a range of −2 mm to +2 mm in the drawing). Moreover, since this measurement was performed by changing the gap G between the surface 60a of the magnet material 60 and the Hall element 13 of the magnetic field detection means 10, the result is also shown. The horizontal axis of FIG. 12A shows the amount of displacement in the relative movement direction between the magnet material 60 and the magnetic field detection means 10. The state where the center of the soft magnetic plate 12 and the center of the N-pole region 61 of the magnet material 60 are opposed to each other is the origin (displacement = 0). The vertical axis in FIG. 12A indicates the magnetic flux density detected by the magnetic field detection means 10.

  As shown in FIG. 12A, when the gap G is changed between 0.8 mm and 2.4 mm, the magnetic flux density that can be detected by the magnetic field detection means 10 decreases as the gap G increases. A desirable magnetic flux density range for detection for the magnetic field detection means 10 used in the present embodiment is about 0.02T to about 0.07T. As is clear from the graph of FIG. 12A, when the gap G becomes small, the magnetic flux density falls within the range of 4 mm (-2 mm to +2 mm in the figure), which is the detection range of the linear displacement of the linear displacement detector. Is almost uniform. Therefore, in this case, the magnetic flux density within the magnetic flux density range desirable for the detection can be detected when the gap G is in the range of 1.6 mm to 2.4 mm.

  FIG. 12B shows the relationship between the amount of displacement in the relative movement direction between the magnetic material 60 and the magnetic field detection means 10 and the magnetic field angle (deg: °) calculated from the detection result (simulation) of the magnetic field detection means 10. It is a graph to show. As apparent from FIG. 12B, the relationship between the displacement and the magnetic field angle is substantially linear, and the relative position between the magnet material 60 and the magnetic field detection means 10 from the magnetic field angle derived by the magnetic field detection means 10. It can be seen that can be derived appropriately.

  On the other hand, in the magnetic material 60 of FIG. 10, when the width of the S pole regions 62 and 63 at the ends: W2 = W1, the magnetic field due to the S pole regions 62 and 63 at the ends becomes dominant. The distribution of the magnetic field formed in the magnetic field becomes non-uniform around each magnetic pole region. FIG. 13A shows the magnet material 60 and the magnetic field detection means 10 using the magnet material 60 in which the width of the S pole regions 62 and 63 at the ends: W2 = W1 in the magnet material 60 of FIG. Is a graph (simulation result) of the magnetic flux density detected by the magnetic field detection means 10 while relatively moving. However, W1 = W2 = 2 mm.

  A desirable magnetic flux density range for detection for the magnetic field detection means 10 used in the present embodiment is about 0.02T to about 0.07T. As is clear from the graph of FIG. 13A, the magnetic flux density greatly fluctuates within the range of 4 mm (−2 mm to +2 mm in the figure) which is the detection target range of the linear displacement of the linear displacement detector. It is not uniform. Therefore, in this case, only when the gap G is 2.0 mm, the magnetic flux density within the desired magnetic flux density range can be detected.

  FIG. 13B shows the relationship between the amount of displacement in the relative movement direction between the magnet material 60 and the magnetic field detection means 10 and the magnetic field angle (deg: °) calculated from the detection result (simulation) of the magnetic field detection means 10. It is a graph to show. As is clear from FIG. 13B, the relationship between the displacement and the magnetic field angle is not linear.

  As described above, in the magnetic material 60 of FIG. 10, the width of the S pole regions 62 and 63 at the end: W2 = 1/2 × W1 and the width of the S pole regions 62 and 63 at the end: W2 = 2. In the case of / 3 × W1, the magnetic flux density is substantially uniform within a range of 4 mm (−2 mm to +2 mm in the figure), which is a linear displacement detection target range of the linear displacement detector. That is, by reducing the size of the south pole regions 62 and 63 provided at the ends, the magnetic field due to the south pole regions 62 and 63 is suppressed from becoming dominant. Therefore, the widths in the direction along the direction of arrangement of the magnetic pole regions other than the ends of the magnetic material 60 are the same, and the width in the direction along the direction of arrangement of the magnetic pole regions arranged at the ends of the magnetic material 60 is the same. If the width is 1/2 to 2/3 of the width in the direction along the arrangement direction of the magnetic pole regions arranged at portions other than the end portions of the magnet material 60, the magnetic field formed outside the magnet material 60 will be described. It can suppress that distribution becomes non-uniform | heterogenous.

[When there are four magnetic pole areas]
FIG. 14 is a diagram illustrating a magnet material 80 having four magnetic pole regions. As shown in the figure, an N pole region (N pole magnetic pole region) 83 (width W5) and an S pole region (S pole magnetic pole region) 84 (width W4) are arranged at the end of the magnet member, except for the end. N pole region 81 (width W1) and S pole region 82 (width W2) are arranged. Other apparatus configurations such as the magnetic field detection means 10 are the same as those in the above embodiment.

In the following, the case of W4 = 2/3 × W1 (or W2) and W5 = 2/3 × W1 (or W2) in the magnet material 80 of FIG. 14 will be described.
FIG. 15A is a graph (simulation result) of magnetic flux density detected by the magnetic field detection unit 10 while relatively moving the magnetic material 80 and the magnetic field detection unit 10 using the magnetic material 80 of FIG. However, W1 = 2 mm, W2 = 2 mm, W4 = 1.33 mm, and W5 = 1.33 mm. Each magnetic pole region has a height L of 3 mm and a depth of 5 mm. Therefore, this linear displacement detection device is configured to detect a linear displacement within a range of 4 mm (within a range of −2 mm to +2 mm in the drawing). Further, since this measurement was performed by changing the gap G between the surface 80a of the magnet material 80 and the Hall element 13 of the magnetic field detection means 10, the result is also shown. The horizontal axis of FIG. 15A shows the amount of displacement in the relative movement direction between the magnet material 80 and the magnetic field detection means 10. A state where the boundary between the center of the soft magnetic plate 12 and the N-pole region 81 and the S-pole region 82 of the magnet material 80 faces each other is defined as the origin (displacement amount = 0). The vertical axis in FIG. 15A indicates the magnetic flux density detected by the magnetic field detection means 10.

  As shown in FIG. 15A, when the gap G is changed between 0.8 mm and 2.4 mm, the magnetic flux density detectable by the magnetic field detection means 10 decreases as the gap G increases. A desirable magnetic flux density range for detection for the magnetic field detection means 10 used in the present embodiment is about 0.02T to about 0.07T. As is apparent from the graph of FIG. 15A, the magnetic flux density is substantially uniform within a range of 4 mm (-2 mm to +2 mm in the figure), which is a detection target range of the linear displacement of the linear displacement detector. Therefore, in this case, the magnetic flux density within the magnetic flux density range desirable for the detection can be detected when the gap G is in the range of 1.6 mm to 2.0 mm.

  FIG. 15B shows the relationship between the amount of displacement in the relative movement direction between the magnet material 80 and the magnetic field detection means 10 and the magnetic field angle (deg: °) calculated from the detection result (simulation) of the magnetic field detection means 10. It is a graph to show. As apparent from FIG. 15B, the relationship between the displacement and the magnetic field angle is substantially linear, and the relative position between the magnet material 80 and the magnetic field detection means 10 from the magnetic field angle derived by the magnetic field detection means 10. It can be seen that can be derived appropriately.

[When there are 5 magnetic pole areas]
FIG. 16 is a diagram illustrating a magnet material 20 having five magnetic pole regions. As shown in the drawing, N pole regions 24 and 25 (width W5) are arranged at the ends of the magnet material 20, and N pole regions 21 (width W1) and S pole regions 22 and 23 (width W2) are arranged at the ends other than the ends. ) Are arranged. Other apparatus configurations such as the magnetic field detection means 10 are the same as those in the above embodiment.

Hereinafter, the case of W5 = 2/3 × W1 (or W2) in the magnet material 20 of FIG. 16 will be described.
FIG. 17A is a graph (simulation result) of magnetic flux density detected by the magnetic field detection unit 10 while relatively moving the magnetic material 20 and the magnetic field detection unit 10 using the magnetic material 20 of FIG. However, W1 = 2 mm, W2 = 2 mm, and W5 = 1.33 mm. Each magnetic pole region has a height L of 3 mm and a depth of 5 mm. Therefore, this linear displacement detection device is configured to detect a linear displacement within a range of 4 mm (within a range of −2 mm to +2 mm in the drawing). Moreover, since this measurement was performed by changing the gap G between the surface 20a of the magnet material 20 and the Hall element 13 of the magnetic field detection means 10, the result is also shown. The horizontal axis of FIG. 17A shows the amount of displacement in the relative movement direction between the magnet material 20 and the magnetic field detection means 10. The state where the center of the soft magnetic plate 12 and the center of the N-pole region 21 of the magnet material 20 are opposed to each other is the origin (displacement = 0). The vertical axis of FIG. 17A shows the magnetic flux density detected by the magnetic field detection means 10.

  As shown in FIG. 17A, when the gap G is changed between 0.8 mm and 2.4 mm, the magnetic flux density that can be detected by the magnetic field detection means 10 decreases as the gap G increases. A desirable magnetic flux density range for detection for the magnetic field detection means 10 used in the present embodiment is about 0.02T to about 0.07T. As is apparent from the graph of FIG. 17A, the magnetic flux density is substantially uniform within a range of 4 mm (-2 mm to +2 mm in the figure), which is a detection target range of the linear displacement of the linear displacement detector. Therefore, in this case, it is possible to detect the magnetic flux density within the magnetic flux density range desirable for the detection when the gap G is in the range of 1.6 mm to 2.2 mm.

  FIG. 17B shows the relationship between the amount of displacement in the relative movement direction between the magnet material 20 and the magnetic field detection means 10 and the magnetic field angle (deg: °) calculated from the detection result (simulation) of the magnetic field detection means 10. It is a graph to show. As is clear from FIG. 17B, the relationship between the displacement and the magnetic field angle is substantially linear, and the relative position between the magnet material 20 and the magnetic field detection means 10 from the magnetic field angle derived by the magnetic field detection means 10. It can be seen that can be derived appropriately.

  As described above, regardless of the number of magnetic pole regions constituting the magnet material, the widths in the direction along the arrangement direction of the magnetic pole regions other than the end portions of the magnet material are the same as each other, and the end portions of the magnet material The width in the direction along the arrangement direction of the magnetic pole regions arranged in the magnetic field is 1/2 to 2/3 of the width in the direction along the arrangement direction of the magnetic pole regions other than the end portions of the magnet material. If it does, it can suppress that the magnetic field distribution formed outside a magnet material becomes non-uniform | heterogenous.

<Another embodiment>
<1>
In the above embodiment, the specific dimensions of the magnetic pole region constituting the magnet material have been described. However, the dimensions of each magnet material vary depending on the required linear displacement detection target range, the strength of the magnetic force, and the like. It can be appropriately changed according to various conditions.

<2>
In the above embodiment, an example in which the relative position in the one-dimensional direction between the magnet material and the magnetic field detection means is detected using the magnet material extending in the one-dimensional direction has been described. However, in the two-dimensional direction (for example, a cross shape) The extended magnet material can be used to detect the relative position in the two-dimensional direction between the magnet material and the magnetic field detection means.

The figure explaining the specific positional relationship of the magnet material with which the linear displacement detection apparatus of 1st Embodiment is equipped, and a magnetic field detection means. The figure explaining the structure of a magnetic field detection means Cross section of magnetic field detection means Graph of magnetic flux density detected by magnetic field detection means while relatively moving magnet material and magnetic field detection means (A) is a graph which shows the relationship between the displacement amount of the relative movement direction of a magnet material and a magnetic field detection means, and the magnetic field angle computed from the detection result of a magnetic field detection means, (b) is a magnet material and A graph showing the relationship between the amount of displacement in the direction of relative movement with the magnetic field detection means and the fluctuation of the magnetic field angle from an arbitrary reference line The figure explaining the specific positional relationship of the magnet material with which the linear displacement detection apparatus of 2nd Embodiment is equipped, and a magnetic field detection means. (A) is a graph which shows the relationship between the displacement amount of the relative movement direction of a magnet material and a magnetic field detection means, and the magnetic field angle computed from the detection result of a magnetic field detection means, (b) is a magnet material and A graph showing the relationship between the amount of displacement in the direction of relative movement with the magnetic field detection means and the fluctuation of the magnetic field angle from an arbitrary reference line The graph which shows the relationship between the position of the relative movement direction of a magnet material and a magnetic field detection means, and the intensity | strength of the magnetic field component of the direction which goes to a magnetic field detection means from a magnet material Graph of magnetic flux density detected by magnetic field detection means while relatively moving magnet material and magnetic field detection means The figure explaining the magnet material which has three magnetic pole area | regions Graph of magnetic flux density detected by magnetic field detection means while relatively moving magnet material and magnetic field detection means Graph of magnetic flux density detected by magnetic field detection means while relatively moving magnet material and magnetic field detection means Graph of magnetic flux density detected by magnetic field detection means while relatively moving magnet material and magnetic field detection means The figure explaining the magnet material which has four magnetic pole area | regions Graph of magnetic flux density detected by magnetic field detection means while relatively moving magnet material and magnetic field detection means The figure explaining the magnet material which has five magnetic pole area | regions Graph of magnetic flux density detected by magnetic field detection means while relatively moving magnet material and magnetic field detection means The figure explaining the specific positional relationship of the magnet material and magnetic field detection means with which the conventional linear displacement detection apparatus is equipped.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Magnetic field detection means 11 Board | substrate 12 Soft magnetic plate 12a Magnetosensitive surface 13 Hall element 14 Chip 20 Magnet material 20a Surface 21, 24, 25 N pole area | region (N pole magnetic pole area | region)
22, 23 S pole region (sole pole region)
30 Linear displacement detection device 40 Magnet material 41, 44, 45 N pole region (N pole magnetic pole region)
42, 43 S pole region (sole pole region)
46 Non-magnetized area 50 Linear displacement detector 60 Magnet material 61 N-pole area (N-pole magnetic pole area)
62, 63 S pole region (sole pole region)
80 Magnet material 81, 83 N pole region (N pole magnetic pole region)
82,84 S pole region (sole pole region)

Claims (4)

A magnetic material in which N pole and S pole magnetic pole regions are alternately arranged in a straight line on the surface;
A magnetic field detecting means having a magnetic sensitive surface for detecting a magnetic field, the magnetic sensitive surface being arranged facing the surface of the magnet material,
The linear displacement detection device, wherein the magnet material and the magnetic field detection means are relatively movable in parallel along an arrangement direction of the N-pole magnetic pole region and the S-pole magnetic pole region of the magnet material.   The linear displacement detection device according to claim 1, wherein a distribution of magnetization intensity of the magnet material in a direction along an arrangement direction of the N-pole magnetic pole region and the S-pole magnetic pole region is sinusoidal.   The linear displacement detection device according to claim 1, wherein the magnet material has a non-magnetized region between the magnetic pole region of the N pole and the magnetic pole region of the S pole. The widths in the direction along the arrangement direction of the magnetic pole regions arranged other than the end of the magnet material are the same as each other,
The width in the direction along the arrangement direction of the magnetic pole region arranged at the end of the magnet material is the width in the direction along the arrangement direction of the magnetic pole region arranged at a position other than the end of the magnet material. The linear displacement detection device according to claim 1, wherein the linear displacement detection device is 1/2 to 2/3 of the above.

Images