JP2012098190A - Rectilinear displacement detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rectilinear displacement detector capable of making the detection range having a longer stroke, compared with the conventional detectors.SOLUTION: A rectilinear displacement detector 1 includes: a magnet material 2 on the surface of which magnetic pole regions 21, 22, 23 of N pole and S pole are arranged alternately in an array; and magnetic field detection means 3 which has a magnetosensitive surface for detecting a magnetic field and in which the magnetosensitive surface is arranged at a certain separation distance to the surface of the magnet material 2. While maintaining a separation distance, the magnet material 2 and the magnetic field detection means 3 are relatively rectilinearly displaceable in a displacement direction (direction of displacement path 4 in inclination angle α) inclined with respect to region boundary lines 24, 25 which divide the magnetic pole regions of N pole and S pole of the magnet material 2, and a relative displacement amount of the displacement direction between the magnet material 2 and the magnetic field detection means 3 is obtained based on a magnetic field detected by the magnetic field detection means 3.

Description

  The present invention relates to a linear displacement detection device that detects a relative linear displacement, and more particularly to a linear displacement detection device that detects a change in a magnetic field.

  Various types of detection devices such as linear encoders have been put to practical use as linear displacement detection devices, and are properly used depending on the application. The applicant of the present application discloses, in Patent Document 1, a linear displacement detection device that detects a change in a magnetic field as a non-contact detection type device having high accuracy and good temperature characteristics. The linear displacement detection apparatus disclosed in Patent Document 1 includes a magnet material in which N-pole and S-pole magnetic pole regions are alternately arranged on the surface, and a magnetic field detection unit having a magnetosensitive surface that faces the surface of the magnet material and detects a magnetic field. The magnetic material and the magnetic field detecting means are relatively movable in parallel along the arrangement direction of the magnetic pole regions. As a result, it is possible to detect the linear displacement by obtaining the magnetic field vector, and it is possible to provide an inexpensive and highly accurate linear displacement detector.

JP 2009-192261 A

  By the way, when it is intended to increase the detection range by the linear displacement detection device of Patent Document 1, the number of N pole and S pole magnetic pole areas is increased or the width of the magnetic pole area is increased. However, if the number of magnetic pole regions is increased, a magnetic field vector change cycle is repeatedly generated in the relative displacement direction, which necessitates counting the number of repetitions of the cycle when obtaining the relative displacement amount. In addition, a function for maintaining the number of repetitions of the cycle is required even when the operation power source of the linear displacement detection device is turned off, which increases the device cost.

  On the other hand, if the width of the magnetic pole region is widened, the strength and direction of the magnetic field are made uniform near the center of the width of the magnetic pole region, the change in the magnetic field vector becomes small, and the relative displacement detection accuracy decreases. In order to solve this problem, if a magnetic pole region having a magnetic field strength distribution in which the magnetic field vector changes to near the center of the width is formed, the absolute value of the magnetic field strength near the center of the width exceeds the usable range of the magnetic field detection means. Unusable.

  The present invention has been made in view of the above-mentioned problems of the background art, and an object to be solved is to provide a linear displacement detection device capable of making the detection range a longer stroke than in the past.

  An invention of a linear displacement detection device according to claim 1 for solving the above-mentioned problem has a magnet material on which a magnetic pole region of N poles and S poles are alternately arranged on the surface, and a magnetosensitive surface for detecting a magnetic field, A magnetic field detecting means arranged with a certain separation distance from the surface of the magnet material, the magnet material and the magnetic field detection means, the magnetic material and the magnetic field detection means, while maintaining the separation distance, Relative linear displacement is possible in a displacement direction inclined with respect to a region boundary line separating the magnetic pole regions of the N pole and the S pole, and the magnetic material and the magnetic field detection are based on the magnetic field detected by the magnetic field detection means. A relative displacement amount in the displacement direction with the means is obtained.

  The invention according to claim 2 is the magnetic plate according to claim 1, wherein the magnetic field detection means is formed of a magnetic material and has the magnetosensitive surface extending in a direction perpendicular to the region boundary line, and the magnetic plate. And two first Hall elements respectively disposed at both ends in a direction orthogonal to the region boundary line.

  According to a third aspect of the present invention, in the first aspect, the magnetic field detection means includes a magnetic plate formed of a magnetic material and having the magnetosensitive surface extending in the relative displacement direction, and the relative displacement direction of the magnetic plate. And two first Hall elements respectively disposed at both ends.

  According to a fourth aspect of the present invention, in the second or third aspect, the magnetic field detection unit is spaced apart in a direction perpendicular to a line segment connecting the two first Hall elements, and is disposed at another end of the magnetic plate. A magnetic field intensity detected by the two second Hall elements by dividing the sum of the magnetic field intensities detected by the two first Hall elements by 2; Is divided by 2 to obtain the perpendicular magnetic field strength in the direction perpendicular to the surface of the magnet material at the center of the magnetic plate, and the difference in magnetic field strength detected by the two first Hall elements is calculated. By dividing by 2 or by dividing by 2 the difference in magnetic field strength detected by the two second Hall elements, it is parallel to the surface of the magnet material at the central portion of the magnetic plate. The horizontal magnetic field strength in the direction is obtained, and the maximum value of the vertical magnetic field strength and the maximum value of the horizontal magnetic field strength when the magnet material and the magnetic field detecting means are relatively linearly displaced are made equal to or close to each other. The angle formed by the line segment connecting the two first Hall elements and the displacement direction or the angle formed by the line segment connecting the two second Hall elements and the displacement direction is adjusted.

  According to a fifth aspect of the present invention, in the magnetic material according to any one of the first to fourth aspects, the N pole and the S are disposed on the surface within a certain distance from a displacement path in which the magnetic field detecting unit is relatively linearly displaced. A pole region of one of the poles is inclined in the displacement path and arranged in a strip shape, and a pole region of the other of the N and S poles is arranged on both sides of the one pole region. It is characterized by being configured.

  In the invention of the linear displacement detection device according to the first aspect, the magnet material and the magnetic field detection means are capable of relative linear displacement in a displacement direction inclined with respect to the region boundary line of the magnet material while maintaining a separation distance. That is, in contrast to the conventional technique in which relative linear displacement is possible in the displacement direction orthogonal to the region boundary line, the present invention uses the tilted displacement direction, so that the detection range can be extended according to the tilt angle. For example, when the width of the magnetic pole region of the magnet material is constant, a long stroke of 1.41 times can be achieved if the tilt angle is 45 °, and a double stroke is achieved if the tilt angle is 30 °. Can be achieved. At this time, since the magnetic field strength distribution in the magnetic pole region of the magnet material may be the same as the conventional one, there is no possibility that the absolute value of the magnetic field strength exceeds the usable range of the magnetic field detecting means. Further, the conventional technique can be applied to a magnetic field vector detection method and a relative displacement calculation algorithm.

  In the invention according to claim 2, the magnetic field detecting means includes a magnetic plate formed of a magnetic material and having a magnetosensitive surface extending in a direction perpendicular to the region boundary line, and a direction perpendicular to the region boundary line of the magnetic plate. And two first Hall elements respectively disposed at both ends. In the invention according to claim 3, the magnetic field detecting means is respectively disposed on the magnetic plate formed of a magnetic material and having a magnetosensitive surface extending in the relative displacement direction, and at both ends of the magnetic plate in the relative displacement direction. And two first Hall elements. By combining the magnetic plate and the two first Hall elements, the direction of the magnetic field vector, that is, the magnetic field angle can be detected, and the relative displacement can be obtained with high accuracy based on the magnetic field angle.

  In the invention according to claim 4, the vertical magnetic field strength is obtained from the magnetic field strengths detected by the two first Hall elements or the two second Hall elements, and the horizontal magnetic field strength is calculated from the magnetic field strengths detected by the two first Hall elements. Can be adjusted so that the maximum values of the vertical and horizontal magnetic field strengths are equal or close to each other. Thereby, the linearity between the magnetic field angle and the relative displacement amount is improved, and the detection accuracy of the relative displacement amount is further improved.

  In the invention according to claim 5, the magnet material is formed in a belt-like shape in which the magnetic pole region of one of the N and S poles is inclined to the displacement path on the surface within a certain distance from the displacement path where the magnetic field detecting means is relatively linearly displaced. And the other pole pole region is arranged on both sides thereof. That is, the total number of the magnetic pole regions is three, and the magnetic pole region located at a distance of a certain distance or more from the displacement path is not necessary because it does not affect the detection accuracy of the magnetic field vector. Thereby, a magnet material can be simplified and reduced in size.

It is a top view which illustrates typically the linear displacement detector of a 1st embodiment of the present invention. It is a PQ direction arrow directional cross-sectional view of FIG. 1 which illustrates typically the linear displacement detection apparatus of 1st Embodiment. It is a perspective view explaining the Hall IC chip which constitutes a magnetic field detection means. It is a figure explaining the state where the magnetic field of the perpendicular direction upward is acting on a magnetic field detection means. It is a figure explaining the state which the magnetic field of a horizontal direction is acting on a magnetic field detection means. It is a figure which shows the result of having simulated the vertical magnetic field intensity | strength and horizontal magnetic field intensity | strength (magnetic field vector) which a magnetic field detection means detects when a magnet material is displaced on a displacement path relatively linearly. It is a vector diagram explaining the method of calculating | requiring a magnetic field angle from the detected vertical magnetic field strength and horizontal magnetic field strength. It is the graph which showed the relationship between the magnetic field angle obtained from FIG. 6 and FIG. 7, and relative displacement amount. It is a top view which illustrates typically the linear displacement detection apparatus of 2nd Embodiment of this invention. It is a top view which illustrates typically the linear displacement detection apparatus of 3rd Embodiment of this invention.

  A linear displacement detection apparatus according to a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a plan view schematically illustrating a linear displacement detection apparatus 1 according to the first embodiment of the present invention. The linear displacement detection device 1 includes a magnet material 2, magnetic field detection means 3, and the like. The linear displacement detection device of the present invention can be used in any installation posture, and it is arbitrary which of the magnet material 2 and the magnetic field detection means 3 moves. In the first embodiment, in order to simplify the description, the case where the magnet material 2 is fixed and the surface thereof is horizontally disposed, and the magnetic field detection means 3 is linearly displaced in the horizontal direction above the surface by a certain distance G is illustrated. explain.

  The magnet material 2 has a long rectangular shape as shown in the figure, and is formed by arranging three magnetic pole regions 21, 22, and 23 that are equally divided into three by a width W and extend in a band shape in the longitudinal direction. Yes. The central magnetic pole region 22 is an N-pole region 22, and the magnetic pole regions 21 and 23 on both sides are a first S-pole region 21 and a second S-pole region 23. The boundary between the N pole region 22 and the first S pole region 21 is a first region boundary line 24, and the boundary between the N pole region 22 and the second S pole region 23 is a second region boundary line 25. The magnet material 2 can be manufactured, for example, by magnetizing a magnetic material such as ferrite. A displacement path 4 in which the magnetic field detection means 3 is linearly displaced in a displacement direction that is separated from the surface of the magnet material 2 by a certain separation distance G and is inclined at an inclination angle α with respect to the first and second region boundary lines 24 and 25. Is set.

  FIG. 2 is a cross-sectional view taken in the direction of arrows PQ in FIG. 1 for schematically explaining the linear displacement detection device 1 of the first embodiment. The white arrow in the figure indicates the direction of the magnetic field in the magnet material 2, the broken arrow indicates the magnetic field line, and the thick solid arrow indicates the magnetic field vector B (magnetic field direction). As shown in the drawing, above the center in the width direction of the N-pole region 22 of the magnet material 2, the magnetic field vector B1 is directed vertically upward. In the following description, the upper vertical direction is used as the reference for the magnetic field angle θ (the magnetic field angle θ of the magnetic field vector B1 = 0 °).

  In the range above the first region boundary line 24 from the center in the width direction of the N pole region 22, the magnetic field vector B is directed to the upper left in the figure, and the magnetic field angle θ changes in the range of 0 ° to −90 °. Immediately above the first region boundary line 24, the magnetic field vector B2 is horizontally oriented to the left in the figure to be a magnetic field angle θ = −90 °. Further, in the upper range beyond the first region boundary line 24 to the center in the width direction of the first S pole region 21, the magnetic field vector B is directed to the lower left in the figure, and the magnetic field angle θ is −90 ° to −180 °. It varies in the range. Similarly, in the range above the second region boundary line 24 from the center in the width direction of the N pole region 22, the magnetic field vector B is directed to the upper right in the figure, and the magnetic field angle θ changes in the range of 0 ° to 90 °. . Just above the second region boundary line 24, the magnetic field vector B3 is directed horizontally to the right in the figure, and the magnetic field angle θ = 90 °. Further, the magnetic field vector B is directed to the lower right in the drawing and the magnetic field angle θ is in the range of 90 ° to 180 ° in the upper range beyond the second region boundary line 25 to the center in the width direction of the second S pole region 23. It changes with.

  The magnetic field detection means 3 is guided by a guide member (not shown) and linearly displaces on the displacement path 4 while maintaining a separation distance G from the magnet material 2. For example, the magnetic field detection means 3 moves from the position 41 of FIG. It is displaced to. For reference, the displacement path 4X orthogonal to the first and second region boundary lines 24, 25 in FIG. 1 and the positions 4X1, 4X2, 4X3 (shown by broken lines in the figure) on the displacement path 4X are the displacement directions in the prior art. Is shown.

  The magnetic field detection means 3 is configured by mounting a Hall IC chip (an integrated circuit component incorporating a Hall element) 32 on a substrate 31. FIG. 3 is a perspective view for explaining the Hall IC chip 32 constituting the magnetic field detection means 3. As illustrated, the Hall IC chip 32 includes a soft magnetic plate 33 and four Hall elements 34, 35, 36, and 37. The soft magnetic plate 33 is a magnetic plate formed of a disk-like soft magnetic material, and is disposed on the upper surface of the chip body portion 321 of the Hall IC chip 32 in FIG. The surface opposite to the chip body 321 of the soft magnetic plate 33 (the upper surface in FIG. 3) is a magnetosensitive surface 331.

  Four Hall elements 34, 35, 36, and 37 are embedded at a 90 ° pitch between an end portion around the soft magnetic plate 33 and the chip main body portion 321. Of these, the two opposing Hall elements 34 and 36 correspond to the two first Hall elements 34 and 36, and the remaining two opposing Hall elements 35 and 37 correspond to the two second Hall elements 35 and 37. Here, a direction connecting the two first Hall elements 34 and 36 is a main detection direction (X direction), and a direction connecting the two second Hall elements 35 and 37 is a Y direction orthogonal to the main detection direction (X direction). And the direction orthogonal to the XY plane is the Z direction. In the present embodiment, the main detection direction (X direction) connecting the two first Hall elements 34 and 36 is orthogonal to the first and second region boundary lines 24 and 25 as shown in FIG. The four Hall elements 34, 35, 36, and 37 are sensitive to a magnetic field in the vertical direction (Z direction) and output a signal corresponding to the strength of the magnetic field.

  The Hall IC chip 32 has a digital signal processor inside the chip body portion 321, and obtains a relative displacement amount by performing arithmetic processing described later on the output signals of the Hall elements 34, 35, 36, and 37. ing. The Hall IC chip 32 is mounted by soldering eight leads 322 coming out of the chip main body 321 to the substrate 31. As shown in FIG. 2, the Hall IC chip 32 is mounted such that the magnetic sensitive surface 331 of the soft magnetic plate 33 faces in parallel to the surface of the magnet material 2. This also keeps a constant separation distance G between the Hall elements 34, 35, 36, and 37 and the magnet material 2. The eight leads 322 supply power to the hall elements 34, 35, 36, and 37 and the digital signal processor, and output the calculation result of the relative displacement amount.

  Next, the principle of detection of the magnetic field vector B by the magnetic field detection means 3 will be described. FIG. 4 is a diagram for explaining a state in which a vertically upward magnetic field (vertical magnetic field strength BV0) is acting on the magnetic field detecting means 3. FIG. The soft magnetic plate 33 has a higher magnetic permeability than the surrounding space and the chip body portion 321, so that it has an action of drawing magnetic lines of force, and the parallel magnetic field is slightly deformed as shown by the broken lines of magnetic force. Magnetic field vectors B4 and B5 that are generally upward in the vertical direction act on the two first Hall elements 34 and 36. The two first Hall elements 34 and 36 detect the vertical components of the magnetic field vectors B4 and B5 and output signals of the same sign. The magnitude of the signal is substantially proportional to the strength of the upward magnetic field in the vertical direction (vertical magnetic field strength BV0). The average value obtained by calculating the sum of two signals having the same sign and dividing by two means the strength of the magnetic field in the vertical direction at the center of the soft magnetic plate 33.

  FIG. 5 is a diagram for explaining a state in which a horizontal magnetic field (horizontal magnetic field strength BH0) acts on the magnetic field detection means 3. Due to the action of the magnetic lines 33 pulling the magnetic lines of force, the parallel magnetic field is greatly deformed as indicated by the broken lines of magnetic lines (the lines of magnetic force inside the soft magnetic plate 33 are omitted). Thereby, the magnetic field vectors B6 and B7 in the oblique direction act on the two first Hall elements 34 and 36. The two first Hall elements 34 and 36 detect the vertical components (vertical magnetic field strengths B6V and B7V) of the magnetic field vectors B6 and B7 in the oblique direction, and output signals with different signs because the directions are different. The magnitude of the absolute value of the signal is approximately proportional to the strength of the magnetic field in the right direction in the horizontal direction (horizontal magnetic field strength BH0). Therefore, the value obtained by calculating the difference between two signals having different signs and dividing by two means the strength of the horizontal magnetic field in the central portion of the soft magnetic plate 33.

  Further, when a magnetic field in an oblique direction is acting on the magnetic field detection means 3, that is, when the vertical magnetic field strength BV0 and the horizontal magnetic field strength BH0 are superposed, the sum and difference of the two signals are calculated as described above. By obtaining, the strength of the magnetic field can be obtained by decomposing in the vertical direction and the horizontal direction. That is, each of the two first Hall elements 34 and 36 can detect only the magnetic field in the vertical direction, but the magnetic field vector B, by combining the above-described operation of the soft magnetic plate 33 and the calculation of the sum and difference of the two signals. That is, the vertical magnetic field strength BV and the horizontal magnetic field strength VH can be detected. Based on the vertical magnetic field strength BV and the horizontal magnetic field strength VH, the digital signal processor obtains a relative displacement amount as described later. In addition, by using the two second Hall elements 35 and 37, the magnetic field vector B can be detected by being decomposed in the vertical Z direction and the horizontal Y direction.

  Next, the operation of the linear displacement detector 1 of the first embodiment will be described. In this embodiment, the effective detection range is from the center in the width direction of the first S pole region 21 to the center in the width direction of the second S pole region 23 through the N pole region 22. This is because the magnetic field angle θ of the magnetic field vector makes one rotation during this period, so that an accurate relative displacement amount can be obtained by obtaining the magnetic field angle θ. In FIG. 1, when the positions 41, 42, 43 on the displacement path 4 of the present embodiment are translated along the first and second region boundary lines 24, 25, the positions 4X1, 4X2 on the displacement path 4X of the prior art are obtained. 4x3. Further, the magnetic field vector B detected by the magnetic field detection means 3 at the position 42 on the displacement path 4 coincides with the magnetic field vector B detected at the position 4X2 on the displacement path 4X. Therefore, the magnetic field vector B detected by the magnetic field detection means 3 at an arbitrary position on the displacement path 4 can be replaced with the magnetic field vector B detected at a position on the conventional displacement path 4X. At this time, if the relative displacement amount on the displacement path 4 is multiplied by the sine function value (sin α) of the inclination angle α, the relative displacement amount on the displacement path 4X can be converted.

  This means that in the first embodiment, even if the magnetic pole strength distribution in the magnetic pole regions 21, 22, and 23 of the magnet material 2 is the same as the conventional one, the same magnetic field detection accuracy as that of the conventional one can be obtained. That is, when the magnet material 2 is manufactured by magnetizing a magnetic material such as ferrite, the same manufacturing method as in the prior art can be used.

  FIG. 6 is a diagram showing the results of simulating the vertical magnetic field strength and the horizontal magnetic field strength (magnetic field vector) detected by the magnetic field detection means 3 when the magnet material 2 is relatively linearly displaced on the displacement path 4. The horizontal axis in the figure is the relative displacement amount on the displacement path 4, and the origin is the center in the width direction of the N-pole region 22. Therefore, the effective detection range is (−W / sin α) to (W / sin α). The vertical axis indicates the magnetic field strength. As shown in the figure, the vertical magnetic field strength BV, which is the vertical component of the magnetic field vector B detected by the magnetic field detection means 3, becomes a substantially cosine function waveform symmetrical about the origin, and the horizontal magnetic field strength BH, which is a horizontal component, is The waveform is generally sine function that is rotationally symmetric about the origin. Further, the maximum value BVmax of the vertical magnetic field strength BV is larger than the maximum value BHmax of the horizontal magnetic field strength BH.

  Next, the magnetic field angle θ is obtained from the vertical magnetic field strength BV and the horizontal magnetic field strength BH, and correction is performed at that time. FIG. 7 is a vector diagram illustrating a method for obtaining the magnetic field angle θ from the detected vertical magnetic field strength BV and horizontal magnetic field strength BH. The correction coefficient K used for correction is obtained by the following equation.

Correction coefficient K = (BVmax / BHmax)
Using this correction coefficient K, the magnetic field angle θ can be obtained by the following equation using an arctangent function.

Magnetic field angle θ = arctan (K · BH / BV)
By using the correction coefficient K, there is an effect of equivalently aligning the maximum values of the vertical magnetic field strength BV and the horizontal magnetic field density BH shown in FIG. Thereby, the linearity at the time of calculating | requiring a relative displacement amount improves. FIG. 8 is a graph showing the relationship between the magnetic field angle θ obtained from FIGS. 6 and 7 and the relative displacement. The graph is generally a straight line going up to the right passing through the origin, and high linearity accuracy is obtained. Using this graph, the magnetic field angle θ obtained from the detection result of the magnetic field vector B can be converted into a relative displacement amount. In the case of FIG. 6, the correction coefficient K is larger than 1, but when the maximum value BVmax of the vertical magnetic field strength BV is smaller than the maximum value BHmax of the horizontal magnetic field strength BH, the correction coefficient K is greater than 1. Becomes smaller.

  As described above, according to the linear displacement detection apparatus 1 of the first embodiment, the magnetic field angle θ is obtained from the vertical magnetic field strength BV and the horizontal magnetic field strength BH detected by the magnetic field detection means 3, and relative relative to each other based on the magnetic field angle θ. The amount of displacement can be obtained with high accuracy. Further, the detection range can be increased to (1 / sin α) times longer stroke according to the inclination angle α formed by the displacement path 4 and the first and second region boundary lines 24 and 25. For example, a long stroke of 1.41 times can be achieved at an inclination angle α = 45 °, and double strokes can be achieved at an inclination angle α = 30 °. Moreover, since the magnetic field intensity distribution of each magnetic pole area | region 21,22,23 of the magnet material 2 may be the same as the past, the same manufacturing method can be used and in addition, a prior art can be applied to the calculation algorithm of a relative displacement amount.

  Next, the linear displacement detection apparatus 10 of 2nd Embodiment is demonstrated. FIG. 9 is a plan view schematically illustrating the linear displacement detection device 10 according to the second embodiment of the present invention. The configurations and functions of the magnet material 2, the magnetic field detection means 30, and the arithmetic processing unit of the linear displacement detection device 10 are the same as those in the first embodiment, and the direction of the magnetic field detection means 30 is different. As shown in FIG. 9, in the second embodiment, the main detection direction (X direction) of the magnetic field detection means 30 coincides with the displacement direction of the magnetic field detection means 3, that is, the direction of the displacement path 4. Also in the second embodiment, the algorithm for detecting the vertical magnetic field strength BV and the horizontal magnetic field strength BH to determine the magnetic field angle θ and the relative displacement is the same as in the first embodiment, and the effect is also the same.

  In the second embodiment, the vertical magnetic field strength BV detected by the magnetic field detection means 30 is substantially equal to that in the first embodiment. On the other hand, since the main detection direction (X direction) is not orthogonal to the first and second region boundary lines 24 and 25, the horizontal magnetic field strength BH detected by the magnetic field detection means 30 is smaller than in the first embodiment. Here, when the maximum value BVmax of the vertical magnetic field strength BV and the maximum value BHmax of the horizontal magnetic field strength BH do not coincide with each other, a method of adjusting the direction of the magnetic field detection means 30 is used instead of the correction calculation method using the correction coefficient K. You can also. Specifically, the angle formed by the main detection direction (X direction) and the displacement path 4 can be adjusted by rotating the magnetic field detection means 30 in FIG. As a result, the maximum value BHmax of the horizontal magnetic field strength BH changes, while the maximum value BVmax of the vertical magnetic field strength BV is substantially constant, so that they can be made equal or close to each other. High linearity accuracy can be obtained.

  Next, the linear displacement detection apparatus 100 of 3rd Embodiment is demonstrated. FIG. 10 is a plan view schematically illustrating the linear displacement detector 100 according to the third embodiment of the present invention. In the third embodiment, the magnet material 20 is downsized as compared with the first embodiment. More specifically, a range exceeding a certain distance D from the displacement path 4 in the magnet material 20 is omitted, and the width of the magnet material 20 is reduced to 2D. The magnetic pole region away from the displacement path 4 hardly affects the magnetic field intensity distribution on the displacement path 4, so that the relative displacement detection accuracy does not decrease even if the magnet material 20 is downsized.

  In each embodiment, the magnet materials 2 and 20 are fixed and the magnetic field detection means 3 and 30 are displaced. Conversely, the magnetic field detection means 3 and 30 are fixed and the magnet materials 2 and 20 are displaced. It may be a configuration. Moreover, although the magnetic field detection means 3 and 30 which have the soft-magnetic plate 33 and the four Hall elements 34, 35, 36, and 37 were illustrated, it is not limited to this. The magnetic field detection means only needs to be able to detect the magnetic field vector B. For example, the vertical component and horizontal component of the magnetic field may be detected by two independent Hall elements. The present invention can be applied in various other ways.

DESCRIPTION OF SYMBOLS 1, 10, 100: Linear displacement detection apparatus 2, 20: Magnet material 21: 1st S pole area | region (magnetic area | region) 22: N pole area | region (magnetic area | region)
23: Second S pole region (magnetic region)
24: First region boundary line (region boundary line) 25: Second region boundary line (region boundary line)
3, 30: Magnetic field detection means 31: Substrate 32: Hall IC chip 321; Chip main body 322: Lead 33: Soft magnetic plate (magnetic plate) 331: Magnetosensitive surface 34, 36: First Hall element 35, 37: First 2-Hall element 4: Displacement path 4X: Conventional displacement path W: Magnetic pole region width G: Separation distance α: Inclination angle D: Constant distance B, B1 to B7: Magnetic field vectors BV, BV0, B6V, B7V: Vertical magnetic field strength BH, BH0: horizontal magnetic field strength K: correction coefficient θ: magnetic field angle

Claims (5)

A magnet material in which N pole and S pole magnetic pole regions are alternately arranged on the surface;
A magnetic sensing surface that detects a magnetic field, and the magnetic sensing surface is arranged with a certain separation distance from the surface of the magnet material,
The magnet material and the magnetic field detecting means are capable of relative linear displacement in a displacement direction inclined with respect to a region boundary line that separates the magnetic pole regions of the N pole and the S pole of the magnet material while maintaining the separation distance. And
A linear displacement detection apparatus, wherein a relative displacement amount in the displacement direction between the magnet material and the magnetic field detection means is obtained based on the magnetic field detected by the magnetic field detection means.   2. The magnetic field detection means according to claim 1, wherein the magnetic field detection unit is made of a magnetic material and has the magnetosensitive surface extending in a direction orthogonal to the region boundary line, and is orthogonal to the region boundary line of the magnetic plate. A linear displacement detection device comprising two first hall elements respectively disposed at both ends of a direction.   2. The magnetic field detection means according to claim 1, wherein the magnetic plate is formed of a magnetic material and has the magnetosensitive surface that extends in the relative displacement direction, and is disposed at both ends of the magnetic plate in the relative displacement direction. A linear displacement detection device comprising two first Hall elements. In claim 2 or 3,
The magnetic field detection means further includes two second Hall elements respectively disposed at the other end portions of the magnetic plate and spaced apart from each other in a direction perpendicular to a line segment connecting the two first Hall elements.
By dividing the sum of magnetic field intensities detected by the two first Hall elements by 2, or by dividing the sum of magnetic field intensities detected by the two second Hall elements by 2, the magnetic plate Finding the perpendicular magnetic field strength in the direction perpendicular to the surface of the magnet material in the center of
By dividing the difference in magnetic field intensity detected by the two first Hall elements by 2, or by dividing the difference in magnetic field intensity detected by the two second Hall elements by 2, the magnetic plate A horizontal magnetic field strength in a direction parallel to the surface of the magnet material in the central portion of
The two first Hall elements so that the maximum value of the vertical magnetic field strength and the maximum value of the horizontal magnetic field strength when the magnet material and the magnetic field detecting means are relatively linearly displaced are equal or close to each other. A linear displacement detecting device, wherein an angle formed by a line segment connecting the two second Hall elements and an angle formed by the line segment connecting the two displacement directions is adjusted.   5. The magnetic material according to claim 1, wherein the magnetic material is a magnetic pole of one of the N pole and the S pole on the surface within a certain distance from a displacement path in which the magnetic field detecting means is relatively linearly displaced. A region is inclined in the displacement path and arranged in a band shape, and a magnetic pole region of the other pole of the N pole and the S pole is arranged on both sides of the magnetic pole region of the one pole, respectively. A linear displacement detector.

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