Movement detector

Abstract

To provide a detector which is downsized by efficiently applying a high-cycle alternating magnetic field to a magnetic wire using a plurality of magnetic field generation sources.SOLUTION: A detector 400 detects the motion of a moving body 410 using a power generation sensor 420. The power generation sensor includes a magnetic wire 421 and a coil 422, and the moving body includes a soft magnetic body part 411 and a plurality of magnetic field generation sources 412. The power generation sensor is arranged in the vicinity of a trajectory drawn by the magnetic field generation sources by motion of the moving body. When the magnetic field generation sources approach the power generation sensor, the movement direction of the magnetic field generation sources is perpendicular to the axial direction of the magnetic wire, and the magnetization direction of the magnetic field generation sources is parallel to the axial direction of the magnetic wire, at least a portion of the magnetic wire from an axial middle part to an axial first end part facing the middle part of the magnetic field generation sources, at least a portion of the magnetic wire from the at least a portion to an axial second end part facing the soft magnetic body part.SELECTED DRAWING: Figure 8A

Description

[Technical field]

[0001] The present invention relates to a detector that detects the motion of a moving object by using a power generation sensor. [Background technology]

[0002] A magnetic wire with a large Barkhausen effect (large Barkhausen jump) is known as a Wiegand wire or a pulse wire. This magnetic wire has a core and a skin surrounding the core. One of the core and the skin is a soft layer in which the magnetization direction is reversed even in a weak magnetic field, while the other is a hard layer in which the magnetization direction is not reversed unless a strong magnetic field is applied. When the hard layer and the soft layer are magnetized in the same direction along the axial direction of the wire, the magnetization direction of the soft layer is reversed when the external magnetic field strength in the opposite direction to the magnetization direction increases and reaches a magnetic field strength at which the magnetization direction of the soft layer is reversed. At this time, the large Barkhausen effect is manifested, and a pulse signal is induced in the coil wound around the magnetic wire. The magnetic field strength at which the magnetization direction of the soft layer is reversed is referred to in this specification as the "operating magnetic field." The magnetic wire and coil are collectively referred to as the power generation sensor. When the external magnetic field strength is further increased and reaches a magnetic field strength at which the magnetization direction of the hard layers is reversed, the magnetization direction of the hard layers is reversed. The magnetic field strength at which the magnetization direction of the hard layers is reversed is referred to as the "stabilizing magnetic field" in this specification. In order for the Large Barkhausen effect to occur, it is necessary that the magnetization direction of only the soft layer is reversed, assuming that the magnetization directions of the hard layer and soft layer are the same. Even if the magnetization direction of only the soft layer is reversed when the magnetization directions of the hard layer and soft layer are not the same, no pulse signal is generated, or if it is generated, it is very small.

[0003] The output voltage from this magnetic wire is constant regardless of the speed at which the magnetic field changes, and has hysteresis characteristics with respect to the input magnetic field, meaning that there is no chattering. For this reason, this magnetic wire is also used in position detectors in combination with magnets and counter circuits. In addition, the output energy from the magnetic wire can be used to operate peripheral circuits without the need for an external power supply.

[0004] When an alternating magnetic field is applied to the power generating sensor, two pulse signals are generated per cycle: one positive pulse signal and one negative pulse signal. The magnet that generates the magnetic field is used as the moving body, and the magnetic field applied to the power generating sensor changes depending on the positional relationship between the magnet (moving body) and the power generating sensor, making it possible to detect the movement of the moving body. However, if only a single power generation sensor is used, it is not possible to identify the direction of motion of the moving object when the direction of motion changes. As shown in Fig. 1 of Patent Document 1, if multiple power generation sensors are used, the direction of motion can be identified, but this leads to an increase in the size and cost of the detector. Patent Document 2 describes the use of a single power generation sensor and another sensor element that is not a power generation sensor. The document further describes the use of a single magnet (two poles) and the use of multiple magnets (multi-pole) to improve resolution. Also, FIG. 1 in Patent Document 3 is an example of a structure for detection using a single magnet (FIG. 2 in Patent Document 2). A structure in which a two-pole magnet and a power generation sensor face each other is suitable for miniaturization because the diameter can be reduced to the full length of the power generation sensor. FIG. 1 in Patent Document 4 is an example of a structure for increasing the resolution (FIG. 3 in Patent Document 2). The main use of this type of motion detector is to detect the number of rotations per revolution. Motion detectors using power generation sensors have the problem that, in some cases, pulse signals that should be output are not output, and a single magnet (two poles) structure that outputs only two pulses per revolution usually lacks precision and is unable to correctly detect the number of rotations. Patent Document 5 describes a method for determining the magnetization direction of the magnetic wire in a power generation sensor by passing a current through a coil in the power generation sensor to generate a magnetic field and monitoring the output state. The document states that by determining the magnetization direction in this way, it is possible to identify the rotation speed even when a single magnet is used. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 5511748 [Patent Document 2] Patent No. 4712390 [Patent Document 3] U.S. Patent No. 9,528,856 [Patent Document 4] U.S. Patent No. 8,283,914 [Patent Document 5] Patent No. 5730809 Summary of the Invention [Problem to be solved by the invention]

[0006] When detecting motion, using multiple power generating sensors tends to increase the size of the detector itself, while even if a single power generating sensor is used, determining the magnetization direction of the magnetic wire in the power generating sensor may involve complex processing.

[0007] SUMMARY OF THE PRESENT EMBODIMENTS An object of the present invention is to provide a detector that is miniaturized by efficiently applying a high-frequency alternating magnetic field to a magnetic wire using a single power generating sensor and multiple magnetic field generating sources. [Means for solving the problem]

[0008] The detector according to the present invention detects the motion of a moving body using a power generating sensor. The power generating sensor includes a magnetic wire that exhibits the large Barkhausen effect and a coil wound around the magnetic wire. The moving body includes a soft magnetic part and a plurality of magnetic field generating sources attached to the soft magnetic part, each of the plurality of magnetic field generating sources having a pair of N and S poles, a magnetization direction parallel to a mounting direction for the soft magnetic part, and the magnetic poles on the outer side of the mounting direction of two adjacent magnetic field generating sources are opposite poles. The power generating sensor is disposed near a trajectory drawn by the plurality of magnetic field generating sources due to the motion of the moving body. The motion direction of the magnetic field generating source when the magnetic field generating source approaches the power generating sensor is perpendicular to the axial direction of the magnetic wire, and the magnetization direction of the magnetic field generating source when the magnetic field generating source approaches the power generating sensor is parallel to the axial direction of the magnetic wire. When the magnetic field generating source is brought close to the power generating sensor, at least a portion of the magnetic wire from the axial center to the first axial end faces the center of the magnetic field generating source, and at least a portion of the magnetic wire from the at least a portion of the magnetic wire from the second axial end faces the soft magnetic material portion. Effect of the Invention

[0009] According to the present invention, a detector that is miniaturized can be provided by efficiently applying a high-frequency alternating magnetic field to a magnetic wire using a plurality of magnetic field generating sources. [Brief description of the drawings]

[0010] [Figure 1A] FIG. 1 is a perspective view of a linear type detector according to a first embodiment. [Figure 1B] FIG. 2 is a top view of the linear-type detector according to the first embodiment. [Figure 2A] FIG. 2 is an explanatory diagram showing a magnetic wire and a moving body. [Figure 2B] This is a magnetic simulation diagram. [Figure 2C] FIG. 11 is another magnetic simulation diagram. [Figure 2D]1A to 1D are explanatory diagrams showing the positional relationship between a magnetic wire and a moving body. [Figure 3A] FIG. 11 is a perspective view of a rotary type detector based on a second embodiment. [Figure 3B] FIG. 11 is a side view of a rotary-type detector according to a second embodiment. [Figure 4A] FIG. 13 is a perspective view of a rotary type detector based on a first modified example of the second embodiment. [Figure 4B] FIG. 13 is a perspective view of a rotary type detector based on a second modified example of the second embodiment. [Figure 4C] FIG. 13 is a perspective view of a multi-pole magnetized magnet according to a modified example of the second embodiment. [Figure 5A] FIG. 11 is a perspective view of a rotary type detector based on a third embodiment. [Figure 5B] FIG. 13 is a perspective view of a rotary type detector based on a first modified example of the third embodiment. [Figure 6] FIG. 13 is a perspective view of a multi-pole magnetized magnet according to a modified example of the third embodiment. [Figure 7A] FIG. 13 is a perspective view of a rotary type detector based on a second modified example of the third embodiment. [Figure 7B] FIG. 13 is a top view of a rotary-type detector based on a second modified example of the third embodiment. [Figure 8A] FIG. 13 is a perspective view of a rotary-type detector based on a fourth embodiment. [Figure 8B] FIG. 13 is a top view of a rotary-type detector based on a fourth embodiment. [Figure 9A] 13 is an explanatory diagram showing a magnetic field applied to a power generation sensor according to a fourth embodiment and an output signal. FIG. [Figure 9B] 13 is an explanatory diagram showing a magnetic field applied to a magnetic sensor according to a fourth embodiment and an output signal. FIG. [Figure 9C] 13A is an explanatory diagram showing a combination of the detection results of the power generation sensor and the magnetic sensor according to the fourth embodiment, and FIG. 13B is an explanatory diagram showing synchronization between the power generation sensor and the magnetic sensor and the rotating coordinates of the output signal based on the fourth embodiment. [Figure 9D] FIG. 13 is an explanatory diagram showing the count number of an output signal based on the fourth embodiment. [Figure 10] FIG. 13 is a perspective view of a rotary type detector based on a modified example of the fourth embodiment. [Figure 11A] FIG. 13 is a perspective view of a rotary-type detector according to a fifth embodiment. [Figure 11B] FIG. 13 is a top view of a rotary-type detector according to a fifth embodiment. [Figure 12A] 13 is an explanatory diagram showing a magnetic field applied to a power generation sensor and an output signal based on a fifth embodiment. FIG. [Figure 12B] 13 is an explanatory diagram showing a magnetic field applied to a magnetic sensor and an output signal based on a fifth embodiment. FIG. [Figure 12C] 13 is an explanatory diagram showing a combination of detection results of a power generation sensor, a first magnetic sensor, and a second magnetic sensor according to a fifth embodiment. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, the present invention will be described based on the illustrated embodiment, however, the present invention is not limited to the embodiment described below.

[0012] [First embodiment] 1A and 1B show a detector 100 based on a first embodiment. The detector 100 includes a moving body 110 that moves linearly and one power generation sensor 120. The moving body 110 includes a slender rectangular parallelepiped soft magnetic material part 111 and multiple magnets (magnetic field generating sources) 112. The longitudinal direction 111a of the soft magnetic material part 111 is parallel to the x-axis, the width direction is parallel to the y-axis, and the height direction is parallel to the z-axis. The multiple magnets 112 are arranged and attached along the longitudinal direction 111a on a first end surface 111b in the width direction of the soft magnetic material part 111. The attachment direction is parallel to the width direction of the soft magnetic material part 111. Examples of attachment methods include embedding, fitting, and adhesion. The magnets 112 are magnetized in the width direction of the soft magnetic material part 111, and have a pair of N and S poles. The magnets 112 have outer magnetic poles 112a located outside the width direction of the soft magnetic material part 111. The multiple magnets 112 are arranged such that adjacent outer magnetic poles 112a have opposite poles. The power generation sensor 120 has a magnetic wire 121 that exhibits the large Barkhausen phenomenon, and a coil 122 wound around the magnetic wire 121. The power generation sensor 120 is disposed near the path drawn by the multiple magnets 112 when the moving body 110 moves linearly along the longitudinal direction 111a of the soft magnetic material part 111 so as not to interfere with the moving body 110. The axial direction 121a of the magnetic wire 121 is parallel to the width direction of the soft magnetic material 111 (the magnetization direction of the magnets 112). 2A, when the moving body 110 moves linearly, the central portion 112b of each magnet 112 passes under a region between the axial central portion 121b and the first axial end portion 121c of the magnetic wire 121. The soft magnetic material portion 111 is located at a position that blocks the gap between the second axial end portion 121d of the magnetic wire 121 and the magnet 112 (at a position that fills the magnetic path between the second axial end portion 121d and the magnet 112). The first axial end 121c is the end on the side where the magnet 112 is attached, as viewed from the soft magnetic material portion 111. The second axial end 121d is the end on the opposite side, as viewed from the soft magnetic material portion 111, to the side where the magnet 112 is attached. In this manner, when the moving body 110 moves linearly, the magnet 112 passes under the first axial end 121c of the magnetic wire 121, but does not pass under the second axial end 121d. When the moving body 110 reciprocates along the longitudinal direction 111a of the soft magnetic material portion 111, an output signal is induced in the coil 122. In other words, the detector 100 is a linear type detector.

[0013] The positional relationship between the magnetic wire 121 and the moving body 110 will be described in more detail. 2B shows the results of a magnetic simulation using the soft magnetic material part 111, the magnet 112, and the magnetic wire 121. Due to the magnetic flux collecting effect and the shielding effect of the soft magnetic material part 111, a magnetic field is applied intensively to the first axial end 121c of the magnetic wire 121 facing the magnet 112. When a magnetic field is applied locally to the first axial end 121c, a reversal magnetic field propagates in the magnetic wire 121 from the first axial end 121c to the second axial end 121d, and a single magnetic domain is formed throughout the entire magnetic wire. On the other hand, Fig. 2C shows the results of a magnetic simulation using a non-magnetic material portion 191 and a magnet 112 provided instead of the soft magnetic material portion 111, and a magnetic wire 121. Unlike Fig. 2B, a magnetic field is applied to the axial center portion 121b in addition to the axial first end portion 121c. Therefore, it becomes difficult to form a single magnetic domain throughout the entire magnetic wire. In addition, the magnetic wire 121, the magnet 112, and the soft magnetic material portion 111 form a magnetic circuit as shown by the arrow in Fig. 2D(A). Therefore, a stabilizing magnetic field is applied to the magnetic wire in a wider range than the conventional method of applying a magnetic field to one end of the magnetic wire, and in the same manner as applying a magnetic field to the entire magnetic wire. Therefore, a single magnetic domain is formed throughout the entire magnetic wire, and a high-output pulse signal is obtained. 2D(B), the width of the soft magnetic material part 111 may be increased in the direction opposite to the magnet 112 (negative y-axis direction) so that the second widthwise end face 111c of the soft magnetic material part 111 and the second axial end face 121d are located at substantially the same y-axis position. In this case, the magnetic resistance of the magnetic circuit becomes smaller, the applied magnetic field propagates more easily along the entire axis, and the output of the pulse signal is further increased.

[0014] As shown in Fig. 2D(C), the y-axis positions of the first axial end 121c of the magnetic wire 121 and the end face of the outer magnetic pole 112a of the magnet 112 may be approximately aligned. Alternatively, as shown in Fig. 2D(D), the y-axis positions of the axial center portion 121b of the magnetic wire 121 and the center portion 112b of the magnet 112 may be approximately aligned. In both Fig. 2D(C) and Fig. 2D(D), the same magnetic circuit as in Fig. 2D(A) and Fig. 2D(B) is formed. In this way, when the magnet 112 approaches the magnetic wire 121, at least a portion of the magnetic wire 121 from the axial central portion 121b to the first axial end portion 121c faces the central portion 112b of the magnet 112, and at least a portion of the magnetic wire 121 from the above-mentioned portion to the second axial end portion 121d faces the soft magnetic material portion 111. That is, the size of the magnet 112 along the width direction of the soft magnetic body 111 can be less than half the axial length of the magnetic wire 121. By appropriately determining the material of the magnet 112, the magnet 112 can be made small enough to apply a stabilizing magnetic field to the magnetic wire 121, and the allowable range for installation of the magnet 112 along the y-axis direction can be widened. In addition, a magnetic field is applied to the magnetic wire 121 from the side of the magnet 112 (the surface facing the magnetic wire 121). Therefore, by adjusting the distance between the magnet 112 and the magnetic wire 121 when passing through, the strength of the magnetic field applied to the magnetic wire 121 can be easily adjusted. This provides a stable pulse signal.

[0015] The magnets 112, which are magnetic field generating sources of multiple NS pole pairs, are arranged on the rear and front sides of the paper in Fig. 2B and Fig. 2C. The influence of magnetic interference occurring between adjacent magnets on the magnetic wire 121 is also reduced by the magnetic flux collecting effect of the soft magnetic material portion 111 and by applying a magnetic field to the first axial end 121c of the magnetic wire 121. Therefore, it is possible to bring adjacent magnetic field generating sources closer to each other and increase the pole density of the magnets. In other words, the detector 100 can be made more compact.

[0016] By applying a magnetic field to one axial end of the magnetic wire 121, it is not necessary to apply a magnetic field of equal strength to both axial ends of the magnetic wire or to the entire magnetic wire, which allows for a high degree of freedom in placement. The shape of the soft magnetic material part can be changed to a ring or disk shape to form a hollow type, shaft type radial gap type, axial gap type rotary type, or other detector. These various forms are described below.

[0017] [Second embodiment] 3A and 3B show a detector 200 according to a second embodiment. The detector 200 includes a moving body 210 that rotates and one power generation sensor 220. The moving body 210 includes a ring-shaped soft magnetic material part 211 and a plurality of magnets 212. The plurality of magnets 212 are arranged in a circumferential direction and fixed on one axial end face of the soft magnetic material part 211. The magnets 212 are magnetized in the axial direction of the soft magnetic material part 211 (the vertical direction on the paper surface of FIG. 3B) and have a pair of N and S poles. The magnet 212 has an outer magnetic pole 212a on the axial upper side of the soft magnetic material part 211. The plurality of magnets 212 are arranged such that adjacent outer magnetic poles 212a have different polarities. The moving body 210 rotates around a shaft 213 of the soft magnetic material part 211 extending in the vertical direction as a rotation axis. The power generation sensor 220 is disposed radially outside the moving body 210, and has a magnetic wire 221 that exhibits the large Barkhausen phenomenon, and a coil 222 wound around the magnetic wire 221. The magnetic wire 221 is disposed parallel to the rotation axis 213. Due to the rotational motion of the moving body 210, the multiple magnets 212 pass near the power generation sensor 220. When the magnet 212 approaches the magnetic wire 221, the direction of motion of the magnet 212 is perpendicular to the axial direction 221a of the magnetic wire 221. When the magnet 212 approaches the magnetic wire 221, at least a part of the magnetic wire 221 from the axial center 221b to the axial upper end 221c faces the central part 212b of the magnet 212. At this time, at least a part of the magnetic wire 221 from the at least a part of the magnetic wire 221 to the axial lower end 221d faces the soft magnetic material part 211. The soft magnetic material part 211 is located at a position that blocks the gap between the axial lower end 221d of the magnetic wire 221 and the passing magnet 212 (a position that fills the magnetic path). When 20 magnets 212 are provided at equal intervals along the circumferential direction of soft magnetic material portion 211, 10 positive pulse signals and 10 negative pulse signals are induced in coil 222 per one forward rotation of moving body 210. Also, 10 positive pulse signals and 10 negative pulse signals are induced per one reverse rotation of moving body 210. Thus, the detector 200 is a radial gap type detector, with the moving body 210 being hollow. The detector 200 is thin, since the axial thickness of the moving body 210 is equal to or smaller than the length of the magnetic wire 221. In addition, since the power generation sensor 220 is positioned radially outward of the moving body 210, the hollow portion of the hollow detector 200 can be made large.

[0018] [First Modification of the Second Embodiment] 4A, the power generation sensor 220 is disposed radially inward of the moving body 210 and spaced apart from the rotation axis 213. In this case, the outer diameter of the detector can be made small.

[0019] [Second Modification of the Second Embodiment] As shown in FIG. 4B, the detector 200-2 includes a substantially disk-shaped soft magnetic material portion 211a instead of the ring-shaped soft magnetic material portion 211 shown in FIG. 3A. A plurality of magnets 212 are disposed on the outer peripheral edge of the soft magnetic material portion 211a. A shaft 213a is attached to the axial lower end surface of the soft magnetic material portion 211a. In this manner, the moving body 210 can be a shaft type. The material of the shaft 213a may be a non-magnetic material or a magnetic material.

[0020] The multiple magnetic field generating sources may be magnets magnetized with multiple poles. As shown in Fig. 4C, when the upper and lower surfaces of the ring-shaped hard magnetic material part 215 are simultaneously magnetized by a magnetizing yoke having an area corresponding to a predetermined magnetization pitch λ, the hard magnetic material part 215 is magnetized in the direction of the rotation axis 213b, and magnetic poles appear on the upper and lower surfaces of the hard magnetic material part 215. A magnet magnetized with multiple poles in this manner may be fixed to the ring-shaped soft magnetic material part 211 or the disk-shaped soft magnetic material part 211a. By making the hard magnetic material part elongated, the first embodiment may also be applied.

[0021] [Third embodiment] 5A shows a detector 300 according to the third embodiment. Unlike the second embodiment (FIG. 3A), multiple magnets 312 are fixed at equal intervals in the circumferential direction to the outer circumferential surface of a ring-shaped soft magnetic material part 311. The power generation sensor 320 is disposed perpendicular to the rotation axis 313, and the axial direction 321a of the magnetic wire 321 is parallel to the normal direction. The longitudinal center position 321b of the magnetic wire 321 is offset with respect to the rotation axis 313. The amount of offset is indicated by the symbol OF1. 5B, a plurality of magnets 312 may be fixed to the inner circumferential surface of the soft magnetic material portion 311. In this case, the offset amount between the longitudinal center position 321b of the magnetic wire 321 and the rotation axis 313 is indicated by symbol OF2. In this way, two types of hollow axial gap type detectors are obtained, each differing in the position of the power generation sensor 320. In either case, the power generation sensor can be placed horizontally on a substrate (not shown) on which electronic components constituting the detection circuit are mounted, providing high mounting stability.

[0022] [Modification of the third embodiment] As in the modified example of the second embodiment, the multiple magnetic field generating sources can be magnets magnetized with multiple poles. As shown in Fig. 6, when the outer and inner peripheral surfaces of the ring-shaped hard magnetic material part 315 are simultaneously magnetized by a magnetizing yoke having an area corresponding to a predetermined magnetization pitch λ, the hard magnetic material part 315 is magnetized along the rotation axis direction 313, and magnetic poles appear on the outer and inner peripheral surfaces of the hard magnetic material part 315. The magnet magnetized with multiple poles in this way can be fixed to the soft magnetic material part 311.

[0023] 7A and 7B show a detector 300-2 according to another modified example. The outer diameter of the moving body 310-2 is small, approximately the entire length of the magnetic wire 321. In the moving body 310-2, eight magnets 312-2 are arranged on the outer circumferential surface of the disk-shaped soft magnetic material part 311-2. The magnetic wire 321 intersects with the rotation axis of the moving body 310-2. One end 321a of the magnetic wire 321 of the power generation sensor 320 faces the outer circumferential part of the soft magnetic material part 311-2 in the axial direction, and the other end faces the inner circumferential part of the soft magnetic material part 311-2 in the axial direction. According to this structure, in the two magnets 312-2 facing each other in the radial direction, the two magnetic poles on the radial inside are the same polarity, but only one magnetic pole applies a magnetic field to the magnetic wire 321. Therefore, the magnetic wire 321 can exhibit the large Barkhausen phenomenon. According to this embodiment, an alternating magnetic field with multiple periods, the period of which is not limited, can be applied to the magnetic wire, and a stable high-output signal is induced in the coil wound around the magnetic wire. Furthermore, the radial dimension can be reduced.

[0024] [Multi-rotation function explanation] Next, we will explain detectors with multi-revolution detection capabilities. Power generation sensors are used for rough detection in units of one revolution when the power is cut off. For accurate position detection when the power is turned on, absolute angle detectors within one revolution are used. Power generation sensors output a total of two pulses, one positive and one negative, for one cycle of the alternating magnetic field, but it is not possible to distinguish between forward and reverse rotation with just these pulses. Therefore, the method shown below has traditionally been used. 1) Method of obtaining a phase difference signal by increasing the number of power generation sensors 2) How to add another detection method The former requires multiple power generation sensors, whereas the latter can be achieved with one power generation sensor and additional sensor elements, as described in Patent Document 2.

[0025] When using a single power generation sensor, the stabilizing magnetic field and the operating magnetic field must be applied to the magnetic wire in a set order to obtain a pulse signal of sufficient level. If the rotating body rotates in the reverse direction immediately after the operating magnetic field is applied to the magnetic wire and a pulse signal is output while the rotating body is rotating in the forward direction, the above order is not observed, and one pulse signal required for rotation detection is missed. In that case, the error exceeds ±180°, and the amount of rotation cannot be detected correctly.

[0026] It has been difficult to achieve both a multi-period alternating magnetic field and a compact detector. However, as a modification of the configuration shown in Figures 7A and 7B, the number of magnetic field generating sources can be increased to four, and two periods of the alternating magnetic field can be applied to the magnetic wire per rotation. In other words, a detector with multi-rotation detection function, small size, low cost, and stable pulse signal output can be obtained. The configuration is described in detail below.

[0027] [Fourth embodiment] 8A and 8B show a detector 400 with a multi-rotation detection function according to a fourth embodiment. The detector 400 includes a rotating moving body 410 and a single power generation sensor 420. The moving body 410 has a disk-shaped soft magnetic material part 411 and four magnets 412 that serve as a magnetic field generation source. The four magnets 412 are arranged at equal intervals in the circumferential direction on the outer circumferential surface of the soft magnetic material part 411. The magnets 412 are magnetized in the radial direction of the soft magnetic material part 411 and have a pair of N poles and S poles. The magnets 412 have outer magnetic poles 412a located on the radial outside of the soft magnetic material part 411. The four magnets 412 are arranged such that the outer magnetic poles 412a adjacent to each other in the circumferential direction have opposite poles. The power generation sensor 420 has a magnetic wire 421 that exhibits the large Barkhausen phenomenon, and a coil 422 wound around the magnetic wire 421. The magnetic wire 421 is perpendicular to the rotation axis 413, and an axial direction 421a of the magnetic wire 421 is parallel to the normal direction. Due to the rotational motion of the moving body 410, the four magnets 412 pass near the first axial end of the magnetic wire 421. The direction of motion of the magnets 412 when passing is perpendicular to the axial direction 421a of the magnetic wire 421. The central portion 412b of the magnets 412 passes under the region between the axial central portion 421b and the first axial end 421c of the magnetic wire 421. The soft magnetic material portion 411 does not axially face the first axial end 421c of the magnetic wire 421, but faces the second axial end 421d. With the above structure, when the moving body 410 rotates once, two periods of a uniform alternating magnetic field are applied to the magnetic wire 421. The detector 400 further includes one magnetic sensor 440. The magnetic sensor 440 is disposed at a position where it can determine the magnetic field from the magnetic field generation source when the power generation sensor 420 outputs a pulse signal. When one of the four magnets 412 (called the "first magnet") passes near the magnetic wire 421, a stabilizing magnetic field is applied to the magnetic wire 412. Then, when a second magnet adjacent to the first magnet approaches, an operating magnetic field in the opposite direction to the stabilizing magnetic field is applied to the magnetic wire 412, and the power generation sensor 420 outputs a pulse signal. That is, as shown in Fig. 8B, the magnetic sensor 440 is disposed so as to form a predetermined angle with the first axial end 421c with respect to the rotation shaft 413. This predetermined angle is approximately 45 degrees as shown in Fig. 8B. Alternatively, the predetermined angle may be approximately 135 degrees, approximately 225 degrees, or approximately 315 degrees.

[0028] [How to determine the number of rotations and the direction of rotation] In Fig. 8B, clockwise rotation of the moving body 410 is defined as forward rotation, and counterclockwise rotation is defined as reverse rotation. The magnetic field Ha applied to the power generation sensor 420 during rotation is shown in Fig. 9A. The positive pulse signal generated in the power generation sensor 420 during forward rotation is indicated by symbol P, the stabilizing magnetic field that is the premise for the output of signal P is indicated by symbol Ps, the negative pulse signal is indicated by symbol N, and the stabilizing magnetic field that is the premise for the output of signal N is indicated by symbol Ns. The stabilizing magnetic field is ±H2, and the operating magnetic field is ±H1. The output during reverse rotation is indicated by the same symbols as during forward rotation, but forward rotation is indicated by white and reverse rotation is indicated by black. The magnetic field applied from the permanent magnet 412 to the power generation sensor 420 is an alternating magnetic field with two cycles per rotation. Therefore, the power generation sensor 420 outputs a positive / negative (P, N) signal twice per forward rotation, and also outputs a positive / negative (P, N) signal twice per reverse rotation, just like in the case of forward rotation.

[0029] In FIG. 9B, the magnetic field Hb applied to the magnetic sensor 440 is indicated by a dashed line. As described above, the magnetic sensor 440 is disposed so as to form approximately 45 degrees with respect to the first axial end 421c with respect to the rotating shaft 413. Therefore, the alternating magnetic field Hb is shifted in phase by 45 degrees from the alternating magnetic field Ha shown in FIG. 9A. As the magnetic sensor 440, for example, a magnetic sensor capable of distinguishing between NS poles (positive and negative in the figure) such as a Hall element or a magnetoresistance effect element (SV-GMR, TMR) can be used. In this case, when the power generation sensor 420 outputs two positive P signals and two inverted N signals, the magnetic sensor 440 outputs a signal that detects a negative magnetic field. This is indicated by white and black triangles in the figure. Also, when the power generation sensor 420 outputs two positive N signals and two inverted P signals, the magnetic sensor 440 outputs a signal that detects a positive magnetic field. This is indicated by white and black rectangles in the figure. FIG. 9C(A) shows a combination of the output signal of the power generation sensor 420 and the detection signal of the magnetic sensor 440.

[0030] FIG. 9C(B) shows the rotation coordinates. After the positive pulse signal P is output, the moving body 410 rotates right as indicated by the symbol R, and the rotation angle until the next signal N' is detected is +90 degrees. On the other hand, if the moving body 410 rotates left as indicated by the symbol L immediately after the positive pulse signal P is output, the next signal is expected to be the signal N. However, since the stabilizing magnetic field Ns has not been passed, the signal N is not output, or even if it is output, it is very small and difficult to evaluate. Therefore, the rotation angle until the next left rotation signal P' that can be evaluated is output is about -(90 degrees + α). Even if a rotational motion occurs in which the stabilizing magnetic field is not applied in both the forward and reverse directions, no overlapping range of the same signal occurs. In addition, the range of positions that can be determined is less than 360 degrees, and the number of rotations of the moving body 410 can be accurately detected.

[0031] For ease of understanding, the method for determining the rotation direction of the moving body 410 will be described using two consecutive signals as an example. The determination is performed by a signal processing circuit (not shown) including a memory. This signal processing circuit has an identification function, a reference function, and a calculation function. First, the signal processing circuit uses the identification function to identify the signal from the power generation sensor 420 as one of the four types P, P', N, and N'. Next, the signal processing circuit uses the reference function to write the previous (previous state) history signal stored in the initial state when counting the number of rotations and the direction of rotation begins, and the signal (new state) associated with the subsequent rotation, in sequence, to the memory. The signal processing circuit searches the two consecutive signals, past and present, stored in the memory in four types of pre-set coded tables, and returns the matching count value. An example of this table is shown in FIG. 9D. The signal processing circuit searches every time a signal is input, and sequentially adds or subtracts the resulting count value using the calculation function. The added or subtracted value represents the number of rotations and the direction of rotation at that time. By setting a reference position between the signal N and the signal P and using a table such as that shown in FIG. 9D, the rotation direction and the number of rotations of the moving body 410 can be counted accurately.

[0032] [How to synchronize the position within one rotation and the number of rotations] When the detector is used for multiple rotations of a motor, the number of rotations is detected by the method described above with reference to FIG. 9D during a power outage in the motor drive system. When the motor drive system is started, the signals P, P', N, and N' each exist at two locations per rotation, so a choice between two areas is required and the number of rotations cannot be determined. Therefore, it is necessary to determine the displacement angle from the reference position of the rotation counter. Therefore, by attaching an external one-rotation absolute type position sensor, it is possible to determine which area the motor is located in and determine the number of rotations.

[0033] [Modification of the fourth embodiment] As shown in Fig. 10, as a modification of the fourth embodiment, a hollow type can also provide a multi-rotation function. The detector 400-1 includes a moving body 410-1, a power generation sensor 420-1, and a magnetic sensor 440-1. The moving body 410-1 includes a ring-shaped soft magnetic material part 411-1 and four magnets 412-1 fixed to the upper surface of the soft magnetic material part. The four magnets 412-1 are formed by magnetizing ring-shaped hard magnetic materials. The power generation sensor 420-1 includes a magnetic wire 421-1 and a coil 422-1. The magnetic wire 421-1 is arranged parallel to the rotation axis 413-1 of the moving body 410-1.

[0034] [Fifth embodiment] In the fourth embodiment described above, one magnetic sensor 440 located at a position approximately 45° away from the magnetic wire 421 in the circumferential direction can cover a total of eight signals, four each for normal and reverse rotations, of the power generation sensor 420. This is because the magnetic field generation sources arranged at equal intervals in the circumferential direction are relatively close to each other, and a magnetic field sufficient to be detected by the magnetic sensor 440 alone is applied to the magnetic sensor 440 in both normal and reverse rotations. However, in a hollow type such as the first modified example of the fourth embodiment, there are cases where the magnetic field generation sources are not close to each other. Such a case will be described below. As shown in Fig. 11A, the detector 500 includes a moving body 510, a power generation sensor 520, a first magnetic sensor 540, and a second magnetic sensor 541. The moving body 510 includes a ring-shaped soft magnetic material part 511, and four magnets 512 arranged at equal intervals in the circumferential direction on the outer circumferential surface of the soft magnetic material part 511. Unlike the fourth embodiment (Fig. 8A), the magnets 512 are not close to each other. The power generation sensor 520 includes a magnetic wire 521 and a coil 522. The power generation sensor 520 is arranged parallel to the radial direction of the moving body 510 and offset from the rotation axis 513 of the moving body 510. The power generating sensor 520 outputs a pulse signal when one of the four magnets 512 passes near the magnetic wire 521, and then the next magnet approaches, gradually strengthening the reversal magnetic field and applying the operating magnetic field. There are eight rotational positions of the moving body 510 when a pulse signal is output: rotational positions where the power generating sensor 520 outputs a positive pulse signal P and a negative pulse signal N during forward rotation, and positions where the power generating sensor 520 outputs a positive pulse signal P and a negative pulse signal N during reverse rotation. A first magnetic sensor 540 and a second magnetic sensor 541 are arranged corresponding to these eight locations so that they can detect the magnetic field of the magnetic field generating source. The magnetic sensors are arranged with a phase shift of -20 degrees and +20 degrees so that the first magnetic sensor 540 can detect the magnetic field during normal rotation and the second magnetic sensor 541 can detect the magnetic field during reverse rotation. As shown in FIG. 11B, the first magnetic sensor 540 is arranged at a position slightly away from one magnet 512 (referred to as the first magnet) in the clockwise direction when the first magnet is directly below the magnetic wire 521, and the second magnetic sensor 541 is arranged at a position slightly away from another magnet adjacent to the first magnet in the clockwise direction in the counterclockwise direction. The arrangement of the first magnetic sensor and the second magnetic sensor may be appropriately determined according to the material, size, etc. of the magnet. In Fig. 11B, clockwise rotation of the moving body 510 is defined as forward rotation, and counterclockwise rotation is defined as reverse rotation. The first magnetic sensor 540 is responsible for identifying the signal of the power generation sensor 520 during forward rotation, and the second magnetic sensor 541 is responsible for identifying the signal of the power generation sensor 520 during reverse rotation. If the 3 o'clock direction in Fig. 11B is defined as 0 degrees, the power generation sensor 520 is at 0 degrees, the first magnetic sensor 540 is at +70 degrees, and the second magnetic sensor 541 is at +20 degrees. The magnetic wire is at the 0 degree position, and both magnetic sensors are arranged in the region from 0 degrees to 90 degrees, but they may be arranged in any of the other three regions (the region from 90 degrees to 180 degrees, the region from 180 degrees to 270 degrees, and the region from 270 degrees to 360 degrees).

[0035] In FIG. 12A, the magnetic field Ha applied to the power generation sensor 520 when the moving body 510 rotates is shown by a dotted line. In the figure, the positive pulse signal generated in the power generation sensor 520 during forward rotation is shown by symbol P, the stabilizing magnetic field that is the premise for the output of the signal P is shown by symbol Ps, the negative pulse signal is shown by symbol N, and the stabilizing magnetic field that is the premise for the output of the signal N is shown by symbol Ns. The stabilizing magnetic field is ±H2, the operating magnetic field is ±H1, and the output during reverse rotation is shown by the same symbols as during forward rotation, but forward rotation is shown by white and reverse rotation is shown by black. The magnetic field applied from the magnet 512 to the power generation sensor 520 is an alternating magnetic field with two periods per rotation. Therefore, the power generation sensor 520 outputs positive and negative (P, N) signals twice per forward rotation, and also outputs positive and negative (P, N) signals twice per reverse rotation, just like during forward rotation.

[0036] 12B, the magnetic field Hb applied to the first magnetic sensor 540 is indicated by a two-dot chain line, and the magnetic field Hc applied to the second magnetic sensor 541 is indicated by a one-dot chain line. As described above, the first magnetic sensor 540 and the second magnetic sensor 541 are disposed at a distance in the circumferential direction from the power generation sensor 520. Therefore, the alternating magnetic fields Hb and Hc are out of phase with the alternating magnetic field Ha shown in FIG. 12A. As the magnetic sensors 540 and 541, for example, a magnetic sensor capable of distinguishing between NS poles (plus and minus in the figure), such as a Hall element or a magnetoresistance effect element (SV-GMR, TMR), can be used. When the power generation sensor 520 outputs two positive P signals, the first magnetic sensor 540 outputs a negative magnetic field detection signal (white triangle in the figure). When the power generation sensor 520 outputs two positive N signals, the first magnetic sensor 540 outputs a positive magnetic field detection signal (white square in the figure). When the power generation sensor 520 outputs two inverted P signals, the second magnetic sensor 541 outputs a detection signal of a positive magnetic field (black square in the figure). When the power generation sensor 520 outputs two inverted N signals, the second magnetic sensor 541 outputs a detection signal of a negative magnetic field (black triangle in the figure). By combining the detection signals of the first magnetic sensor 540 and the second magnetic sensor 541 with the output signal of the power generation sensor 520, four types of signals, P, P', N, and N', are identified as shown in Fig. 12C. By operating these four types of signals according to the above-mentioned [method of determining the number of rotations and the direction of rotation] and [method of synchronizing the position within one rotation and the number of rotations], this detector 500 can be used for multiple rotations of a motor.

[0037] [Other circuit examples] The detectors of each embodiment use a power generating sensor equipped with a magnetic wire. Therefore, the output signal due to the large Barkhausen effect is an electromotive force as is already known, and can be used as a power source. That is, by adding a function to process the output of the power generating sensor with a rectifier and a capacitor, the detector of the first embodiment can be used, for example, as a switch (door opening / closing, shutter position), and the detectors of the second and third embodiments can be used, for example, as a meter (flow rate, water, air volume, gas). In such applications where synchronization of the rotation angle within one rotation is not required, it is not necessary to use a power source or a battery. Furthermore, it is possible to transmit data wirelessly using the power generated by the power generating sensor. In the detectors of the fourth and fifth embodiments, the power generating sensor supplies power to the circuit and the magnetic sensor, making it possible to apply the detectors to a battery-less multi-rotation position detector of a motor.

[0038] [Action and Effects] The functions and effects of the embodiments described above will now be described again. When a magnetic field source approaches the power generating sensor, a magnetic field is applied to the first axial end of the magnetic wire in the power generating sensor, but the second axial end is not applied because it does not face the magnetic field source. This causes simultaneous reversal of the magnetic domains from the first axial end to the second axial end, so no magnetic induction yoke is required, and a single magnetic domain is formed throughout the magnetic wire in the same way as in the case of applying a magnetic field to both ends of the magnetic wire. This allows a high-output pulse signal to be obtained from the power generating sensor.

[0039] By applying a magnetic field to one axial end of the magnetic wire, the axial dimension of the portion of the magnetic wire facing the magnetic field source can be made less than half the length of the magnetic wire. This eliminates the need for a relatively large magnet, which is required in methods that apply a magnetic field to the entire length of the magnetic wire. Also, by appropriately selecting the material of the magnet, the magnet can be made small enough to apply a stabilizing magnetic field. Furthermore, since the magnetic field is detected on the side of the magnetic wire's magnetic field source, there is a wide range of adjustment for the gap (the distance between the N-S boundary of the magnetic field source and the first end of the magnetic wire). Its durability provides stable output.

[0040] The magnetic field is applied to one side of the axial end of the magnetic wire, and the soft magnetic material portion collects magnetic force at the axial end where the magnetic field is not applied, which reduces the effect on the magnetic wire of magnetic interference between adjacent magnetic field sources of different poles. This allows multiple magnetic field sources to be placed close together. It is possible to increase the pole density (number of poles per perimeter of the moving body) of the magnetic field source. If the moving body is a rotating body, the circumference of the rotating body can be shortened. In other words, the overall structure of the detector becomes smaller.

[0041] Since it is not necessary to apply a magnetic field of equal strength to both ends or the entire magnetic wire, there is a high degree of freedom in placement. If the magnetic wire is placed on a straight line parallel to the rotation axis of the rotating body, the shape of the soft magnetic material part can be either ring-shaped or disk-shaped. Either the hollow type or the shaft type can be used as a radial gap rotary type detector. In this structure, the dimension in the rotation axis direction of the rotating body is less than or equal to the length of the magnetic wire, resulting in a thin detector. In the hollow type, if the inner diameter of the detector is to be large, the power generation sensor can be placed on the outer periphery, and if the outer diameter is to be small, the power generation sensor can be placed on the inner periphery. In other words, there is a high degree of freedom in design.

[0042] In terms of freedom of placement, if the magnetic wire is placed on a straight line perpendicular to the rotation axis, the shape of the soft magnetic material part can be made ring-shaped or disk-shaped. In other words, it can be used as a hollow or shaft-type axial gap rotary type detector. If the rotation axis is vertical, electronic components that make up the circuit, such as a power generation sensor, can be stably mounted on a horizontally placed board.

[0043] The magnetic wire can be arranged so that it is perpendicular to the axis of rotation of the rotating body. In this case, it becomes a shaft-type, axial gap rotary type detector. An alternating magnetic field of two or more periods is applied. Further miniaturization (especially of the radial dimension) can be achieved. In addition, the stability of the signal induced in the coil wound around the magnetic wire can be improved.

[0044] In a shaft-type axial gap rotary detector, when the number of magnetic field generating sources is four or eight, if the center of the magnetic wire is placed at the center of the rotation axis, a magnetic field of the same polarity is applied to both ends of the wire, and the Great Barkhausen phenomenon cannot be exhibited. However, by shifting the magnetic wire from the center of the rotation axis (offsetting it), an alternating magnetic field with many periods can be applied to the magnetic wire. In particular, by setting the number of magnetic field generating sources to four, an alternating magnetic field with two periods, which is the minimum period, can be applied, resulting in a rotating body with the smallest radius.

[0045] A magnetic sensor may be provided in addition to the power generation sensor. Since two periods of an alternating magnetic field are applied, there is no need to provide multiple power generation sensors.

[0046] Regarding the embodiments described above, the following supplementary notes are disclosed. [Appendix 1] A detector for detecting the motion of a moving object using a power generation sensor, The power generation sensor includes a magnetic wire that exhibits a large Barkhausen effect and a coil wound around the magnetic wire, the moving body includes a soft magnetic material portion and a plurality of magnetic field generating sources attached to the soft magnetic material portion, each of the plurality of magnetic field generating sources has a pair of N and S poles, a magnetization direction is parallel to a mounting direction for the soft magnetic material portion, and the magnetic poles on the outer side in the mounting direction of two adjacent magnetic field generating sources are opposite poles; the power generation sensor is disposed in the vicinity of a trajectory traced by the plurality of magnetic field generating sources due to the motion of the moving body; a direction of motion of the magnetic field source when the magnetic field source approaches the power generation sensor is perpendicular to an axial direction of the magnetic wire; a magnetization direction of the magnetic field generation source when the magnetic field generation source is close to the power generation sensor is parallel to an axial direction of the magnetic wire, When the magnetic field generating source approaches the power generating sensor, at least a portion of the magnetic wire from the axial center to the first axial end faces the center of the magnetic field generating source, and at least a portion of the magnetic wire from the at least a portion of the magnetic wire to the second axial end faces the soft magnetic material portion. Detector. [Appendix 2] The detector of claim 1, wherein when the magnetic field generating source is close to the power generating sensor, the soft magnetic material portion faces the second axial end of the magnetic wire. [Appendix 3] The moving body rotates, 3. The detector of claim 1 or 2, wherein the magnetic wire is arranged parallel to a rotation axis of the rotational motion. [Appendix 4] The moving body rotates, 3. The detector of claim 1 or 2, wherein the magnetic wire is on a straight line perpendicular to the axis of rotation of the rotary motion, and the axial center of the magnetic wire is offset with respect to the axis of rotation. [Appendix 5] 5. The detector of claim 4, wherein the magnetic wire is arranged to intersect with an axis of rotation of the rotational motion. [Appendix 6] 6. The detector according to any one of claims 1 to 5, wherein the number of magnetic field generating sources is four. [Appendix 7] a magnetic sensor that detects a magnetic field from the magnetic field generation source when the power generation sensor outputs a signal; a circuit for determining the number of rotations and the direction of rotation of the moving body based on the signals outputted by the power generation sensor and the magnetic sensor in response to the rotational motion of the moving body; The detector according to any one of claims 1 to 6, further comprising:

[0047] Although the embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and various modifications and changes can be made based on the technical concept of the present invention. [Explanation of symbols]

[0048] 100, 200, 300, 400, 500 Motion Detector 110, 210, 310, 410, 510 moving body 111, 211, 311, 411, 511 Soft magnetic material part 112, 212, 312, 412, 512 Magnets 120, 220, 320, 420, 520 Power generation sensor 121, 221, 321, 421, 521 Magnetic Wire 122, 222, 322, 422, 522 coils 440, 540, 541 Magnetic Sensors

Claims

1. A detector for detecting the motion of a moving object using a power generation sensor, The power generation sensor includes a magnetic wire that exhibits a large Barkhausen effect and a coil wound around the magnetic wire, The moving body includes a soft magnetic material portion and a plurality of magnetic field generating sources attached to the soft magnetic material portion, each of the plurality of magnetic field generating sources has a pair of N and S poles, a magnetization direction is parallel to a mounting direction for the soft magnetic material portion, and the magnetic poles on the outer side in the mounting direction of two adjacent magnetic field generating sources are opposite poles, the power generation sensor is disposed in the vicinity of a trajectory traced by the plurality of magnetic field generating sources due to the motion of the moving body; a direction of motion of the magnetic field source when the magnetic field source approaches the power generation sensor is perpendicular to an axial direction of the magnetic wire; a magnetization direction of the magnetic field generation source when the magnetic field generation source is close to the power generation sensor is parallel to an axial direction of the magnetic wire, when the magnetic field generating source approaches the power generating sensor, at least a portion of the magnetic wire from the axial center to the axial first end faces the center of the magnetic field generating source, and at least a portion of the magnetic wire from the at least a portion of the magnetic wire to the axial second end faces the soft magnetic material portion. Detector.

2. The detector according to claim 1 , wherein the soft magnetic material portion faces the second axial end of the magnetic wire when the magnetic field generating source approaches the power generating sensor.

3. The moving body rotates, The detector of claim 1 , wherein the magnetic wire is arranged parallel to an axis of rotation of the rotary motion.

4. The moving body rotates, The detector according to claim 1 or 2, wherein the magnetic wire is on a straight line perpendicular to a rotation axis of the rotary motion, and the axial center portion of the magnetic wire is offset with respect to the rotation axis.

5. The detector of claim 4 , wherein the magnetic wire is disposed so as to intersect an axis of rotation of the rotary motion.

6. A detector according to any one of claims 1 to 5, wherein the number of magnetic field sources is four.

7. a magnetic sensor that detects a magnetic field from the magnetic field generation source when the power generation sensor outputs a signal; a circuit for determining the number of rotations and the direction of rotation of the moving body based on the signals outputted by the power generation sensor and the magnetic sensor in response to the rotational motion of the moving body; The detector of any one of claims 1 to 6, further comprising:

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