JP7645136B2 - Movement detector - Google Patents

Description

The present invention relates to a detector that detects the movement of a moving body using a power generation sensor.

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 even if it is generated, it is very small.

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 there is no chattering. For this reason, this magnetic wire is also used in position detectors and the like when combined 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.

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, when a single power generation sensor is used, it is not possible to identify the direction of motion of a moving object when the direction of motion is changed. As shown in FIG. 1 of Patent Document 1, the direction of motion can be identified by using multiple power generation sensors, but this leads to an increase in the size and cost of the detector.
Patent Document 2 describes the use of a single power generating sensor and another sensor element that is not a power generating 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 of Patent Document 3 is an example of a structure for detection using a single magnet (FIG. 2 of 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 of Patent Document 4 is an example of a structure for increasing the resolution (FIG. 3 of Patent Document 2). The main use of this type of motion detector is to detect the number of rotations per revolution. A motion detector using a power generation sensor has the problem that a pulse signal that should be output is sometimes not output, and a single magnet (two poles) structure that outputs only two pulses per revolution usually lacks precision and cannot 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.

Patent No. 5511748 Patent No. 4712390 U.S. Pat. No. 9,528,856 U.S. Pat. No. 8,283,914 Patent No. 5730809

When detecting motion, using multiple power generating sensors tends to increase the size of the detector itself. On the other hand, even if a single power generating sensor is used, determining the magnetization direction of the magnetic wire inside the power generating sensor can be a complicated process.

Therefore, the present invention aims to provide a detector that is compact by efficiently applying a high-frequency alternating magnetic field to a magnetic wire using a single power generation sensor and multiple magnetic field generating sources.

The detector according to the present invention detects the motion of a moving body using a power generation sensor. The power generation 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 sources attached to the soft magnetic part, each of which has a pair of N and S poles, a magnetization direction parallel to the attachment direction to the soft magnetic part, and the magnetic poles on the outer side of the attachment direction of two adjacent magnetic field sources are opposite poles. The power generation sensor is disposed near the trajectory drawn by the plurality of magnetic field sources due to the motion of the moving body. The motion direction of the magnetic field source when the magnetic field source approaches the power generation sensor is perpendicular to the axial direction of the magnetic wire, and the magnetization direction of the magnetic field source when the magnetic field source approaches the power generation sensor is parallel to the axial direction of the magnetic wire. When the magnetic field source approaches the power generation 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 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.

According to the present invention, it is possible to provide a detector that is miniaturized by efficiently applying a high-frequency alternating magnetic field to a magnetic wire using multiple magnetic field generating sources.

FIG. 1 is a perspective view of a linear type detector according to a first embodiment. FIG. 2 is a top view of a linear-type detector according to the first embodiment. FIG. 2 is an explanatory diagram showing a magnetic wire and a moving body. This is a magnetic simulation diagram. FIG. 11 is another magnetic simulation diagram. 13A to 13D are explanatory diagrams showing the positional relationship between the magnetic wire and the moving body. FIG. 13 is a perspective view of a rotary type detector based on a second embodiment. FIG. 11 is a side view of a rotary type detector according to a second embodiment. FIG. 13 is a perspective view of a rotary type detector based on a first modified example of the second embodiment. FIG. 13 is a perspective view of a rotary type detector based on a second modified example of the second embodiment. FIG. 13 is a perspective view of a multi-pole magnetized magnet according to a modified example of the second embodiment. FIG. 13 is a perspective view of a rotary type detector based on a third embodiment. FIG. 13 is a perspective view of a rotary type detector based on a first modified example of the third embodiment. FIG. 13 is a perspective view of a multi-pole magnetized magnet according to a modified example of the third embodiment. FIG. 13 is a perspective view of a rotary type detector based on a second modified example of the third embodiment. FIG. 13 is a top view of a rotary type detector based on a second modified example of the third embodiment. FIG. 13 is a perspective view of a rotary type detector based on a fourth embodiment. FIG. 13 is a top view of a rotary type detector based on a fourth embodiment. 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. 13A and 13B are explanatory diagrams showing a magnetic field applied to a magnetic sensor according to a fourth embodiment and an output signal. 13A is a diagram illustrating a combination of the detection results of the power generation sensor and the magnetic sensor according to the fourth embodiment, and FIG. 13B is a diagram illustrating the synchronization of the power generation sensor and the magnetic sensor and the rotation coordinate of the output signal based on the fourth embodiment. FIG. 13 is an explanatory diagram showing the count number of an output signal based on the fourth embodiment. FIG. 13 is a perspective view of a rotary type detector based on a modified example of the fourth embodiment. FIG. 13 is a perspective view of a rotary type detector based on a fifth embodiment. FIG. 13 is a top view of a rotary type detector based on a fifth embodiment. 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. 13 is an explanatory diagram showing a magnetic field applied to a magnetic sensor based on a fifth embodiment and an output signal. FIG. 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.

The present invention will be described below based on the illustrated embodiment. However, the present invention is not limited to the embodiment described below.

[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 thin rectangular parallelepiped soft magnetic material part 111 and a plurality of 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 the first widthwise end surface 111b of the soft magnetic material portion 111. The attachment direction is parallel to the widthwise direction of the soft magnetic material portion 111. Examples of attachment methods include embedding, fitting, and adhesion. The magnets 112 are magnetized in the widthwise direction of the soft magnetic material portion 111 and have a pair of N and S poles. The magnets 112 have outer magnetic poles 112a located on the outer side in the widthwise direction of the soft magnetic material portion 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 described by the multiple magnets 112 when the moving body 110 moves linearly along the longitudinal direction 111a of the soft magnetic material section 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 the region between the axial central portion 121b and the axial first 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 axial second end portion 121d of the magnetic wire 121 and the magnet 112 (at a position that fills the magnetic path between the axial second end portion 121d and the magnet 112).
The first axial end 121c is an 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 an 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.

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 locally applied 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 in place 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 portion 111 may be increased in the direction opposite to the magnet 112 (negative y-axis direction) so that the second end face 111c in the width direction of the soft magnetic material portion 111 and the second end face 121d in the axial direction are located at substantially the same position on the y-axis. In this case, the magnetic resistance of the magnetic circuit becomes smaller, the applied magnetic field propagates more easily along the entire shaft, and the output of the pulse signal is further increased.

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), a magnetic circuit similar to that 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 axial first 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 at least a portion of the magnetic wire 121 to the axial second 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 material 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 installation tolerance range 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.

The magnets 112, which are the magnetic field generating sources of the multiple N-S pole pairs, are arranged at the rear and front of the page in Figures 2B and 2C. The influence of magnetic interference between adjacent magnets on the magnetic wire 121 is also reduced by the magnetic 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 smaller.

By applying a magnetic field to one axial end of the magnetic wire 121, there is no need to apply a magnetic field of equal strength to both axial ends of the magnetic wire or to the entire magnetic wire, allowing for greater freedom in placement. The shape of the soft magnetic material portion can be changed to a ring or disk shape to create a hollow type, shaft type radial gap type, axial gap type rotary type, or other detector. These various forms are described below.

[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 of the paper surface of FIG. 3B) and have a pair of N and S poles. The magnets 212 have outer magnetic poles 212a on the axial upper side of the soft magnetic material part 211. The plurality of magnets 212 are arranged so that adjacent outer magnetic poles 212a have different poles. 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 outward of 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 in 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 less than the length of the magnetic wire 221. In addition, since the power generation sensor 220 is located radially outward of the moving body 210, the hollow portion of the hollow detector 200 can be made large.

[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.

[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 of a shaft type. The material of the shaft 213a may be either a non-magnetic material or a magnetic material.

The multiple magnetic field generating sources can also 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 equivalent 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 way can 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, this can also be applied to the first embodiment.

[Third embodiment]
Fig. 5A shows a detector 300 according to the third embodiment. Unlike the second embodiment (Fig. 3A), a plurality of magnets 312 are fixed at equal intervals in the circumferential direction to the outer peripheral surface of a ring-shaped soft magnetic material part 311. The power generation sensor 320 is disposed so as to be 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 lengthwise 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.

[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.

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 of the magnetic poles 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.

[Explanation of multi-rotation function]
Next, we will explain detectors with multi-revolution detection capabilities. The power generation sensor is 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, an absolute angle detector within one revolution is used. The power generation sensor outputs 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 only these pulses. Therefore, the method shown below has traditionally been used.
1) A method of increasing the number of power generation sensors to obtain a phase difference signal 2) A method of adding another detection means The former requires multiple power generation sensors, while the latter can be achieved with one power generation sensor and an additional sensor element, as described in Patent Document 2.

When using a single power generation sensor, the stabilizing magnetic field and operating magnetic field must be applied to the magnetic wire in a specific order to obtain a pulse signal of sufficient level. If the rotating body rotates in the forward direction and the operating magnetic field is applied to the magnetic wire and a pulse signal is output, and then the rotating body reverses immediately after, the above order is not followed and one pulse signal required for rotation detection is missed. In that case, the error will exceed ±180° and the correct amount of rotation cannot be detected.

Until now, 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 can be obtained that is compact, low cost, and has a stable pulse signal output. The configuration is described in detail below.

[Fourth embodiment]
8A and 8B show a detector 400 having 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 magnetic field generating sources. 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 pairs of N 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 a 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.

[Method for determining rotation speed and direction]
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 outputs a positive/negative (P, N) signal twice per reverse rotation, just like in the case of forward rotation.

In FIG. 9B, the magnetic field Hb applied to the magnetic sensor 440 is shown by a dashed line. As described above, the magnetic sensor 440 is disposed so as to form approximately 45 degrees with 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 N and S 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 shown 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 shown 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.

The rotation coordinates are shown in FIG. 9C (B). After the positive pulse signal P is output, the moving body 410 rotates right as shown 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 shown by the symbol L immediately after the positive pulse signal P is output, the next signal is expected to be 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). In this way, even if a rotational motion occurs in which a stabilizing magnetic field is not applied in both the forward and reverse directions, no overlapping ranges of the same signal are generated. 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.

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, into 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 signals N and P and using a table such as that shown in FIG. 9D, the rotation direction and number of rotations of the moving body 410 can be counted accurately.

[Method for synchronizing 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 of the motor drive system. When the motor drive system is started, the signals P, P', N, and N' are present at two locations each in one rotation, so that a choice between two regions 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 region the motor is located in and to determine the number of rotations.

[Modification of the fourth embodiment]
As shown in Fig. 10, as a modification of the fourth embodiment, the hollow type can also provide a multiple 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.

[Fifth embodiment]
In the fourth embodiment described above, one magnetic sensor 440 located 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 generating 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 generating 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 generation 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 generation sensor 520 outputs a positive pulse signal P and a negative pulse signal N during forward rotation, and positions where the power generation sensor 520 outputs a positive pulse signal P and a negative pulse signal N during reverse rotation.
The first magnetic sensor 540 and the second magnetic sensor 541 are arranged so as to detect the magnetic field of the magnetic field generating source in correspondence with these eight locations. The first magnetic sensor 540 detects the magnetic field during normal rotation, and the second magnetic sensor 541 detects the magnetic field during reverse rotation, so that the magnetic sensors are arranged with a phase shift of -20 degrees and +20 degrees. 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, the right rotation of the moving body 510 is defined as forward rotation, and the left 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 the 0 degree position, the first magnetic sensor 540 is at the +70 degree position, and the second magnetic sensor 541 is at the +20 degree position. 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).

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 indicated by the symbol P, the stabilizing magnetic field that is the premise for the output of the signal P is indicated by the symbol Ps, the negative pulse signal is indicated by the symbol N, and the stabilizing magnetic field that is the premise for the output of the signal N is indicated by the symbol Ns. The stabilizing magnetic field is ±H2, the operating magnetic field is ±H1, and the output during reversal is indicated by the same symbol as during forward rotation, but forward rotation is indicated by white and reverse rotation is indicated 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 signal of the power generation sensor 520 outputs positive and negative (P, N) signals twice each in one forward rotation, and even in one reverse rotation, positive and negative (P, N) signals are output twice each in the same way as during forward rotation.

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.
The magnetic sensors 540 and 541 may be magnetic sensors capable of distinguishing between north and south poles (plus and minus in the figure), such as Hall elements and magnetoresistance effect elements (SV-GMR, TMR).
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 positive magnetic field detection signal (black square in the figure). When the power generation sensor 520 outputs two inverted N signals, the second magnetic sensor 541 outputs a negative magnetic field detection signal (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.

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, power can be supplied from the power generating sensor to the circuit and the magnetic sensor, making it possible to apply the detectors to a battery-less motor multi-rotation position detector.

[Action and Effect]
The functions and effects of the embodiments described above will now be explained again.
When the 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 with a magnetic field 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.

By applying a magnetic field to one axial end of the magnetic wire, the axial dimension of the part 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 the relatively large magnets 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 on the side of the magnetic wire's magnetic field source is detected, 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 creates stability in the output.

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. This reduces the effect of magnetic interference between adjacent magnetic field sources of different poles on the magnetic wire. 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.

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. Both hollow and shaft types can be used as radial gap rotary type detectors. With 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. With hollow types, if you want a large inner diameter for the detector, you can place the power generation sensor on the outer periphery, and if you want a small outer diameter, you can place the power generation sensor on the inner periphery. In other words, there is a high degree of freedom in design.

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

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. Two or more periods of alternating magnetic field are applied. Further miniaturization (especially of radial dimensions) can be achieved. In addition, the stability of the signal induced in the coil wound around the magnetic wire can be improved.

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 occur. However, by shifting the magnetic wire from the center of the rotation axis (offsetting it), an even, multi-period alternating magnetic field is applied to the magnetic wire. In particular, by setting the number of magnetic field generating sources to four, an alternating magnetic field of two periods, which is the minimum period, can be applied, resulting in a rotating body with the smallest radius.

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.

Regarding the embodiments described above, the following supplementary notes are disclosed.
[Appendix 1]
A detector for detecting the motion of a moving body 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.
[Appendix 2]
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 an axis of rotation of the rotational motion.
[Appendix 4]
The moving body rotates,
3. The detector of claim 1, 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 of claim 1, 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 a rotation speed and a rotation direction of the moving body based on signals output by the power generation sensor and the magnetic sensor in response to the rotational motion of the moving body.

Although the embodiment of the present invention has been described above, the present invention is not limited to the embodiment described above, and various modifications and changes are possible based on the technical concept of the present invention.

100, 200, 300, 400, 500 Motion Detector

110, 210, 310, 410, 510 Moving body 111, 211, 311, 411, 511 Soft magnetic body part 112, 212, 312, 412, 512 Magnet

120, 220, 320, 420, 520 Power generation sensor 121, 221, 321, 421, 521 Magnetic wire 122, 222, 322, 422, 522 Coil 440, 540, 541 Magnetic sensor

Claims (7)

A detector for detecting the motion of a moving body 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. The detector according to claim 1, wherein when the magnetic field source approaches the power generation sensor, the soft magnetic material portion faces the second axial end of the magnetic wire. 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. The moving body rotates,
The detector according to claim 1 or 2, wherein the magnetic wire is on a straight line perpendicular to an axis of rotation of the rotary motion, and the axial center of the magnetic wire is offset with respect to the axis of rotation. The detector of claim 4, wherein the magnetic wire is arranged to intersect with the axis of rotation of the rotational motion. The detector according to any one of claims 1 to 5, wherein the number of magnetic field generating sources is four. a magnetic sensor that detects a magnetic field from the magnetic field generation source when the power generation sensor outputs a signal;
The detector according to any one of claims 1 to 6, further comprising: a circuit for determining a rotation speed and a rotation direction of the moving body based on signals output by the power generation sensor and the magnetic sensor in response to rotational motion of the moving body.