Power generation element, power generation module, rotation speed detector, and encoder

Abstract

The voltage generated in the pickup coil could sometimes decrease due to mutual interference between magnetic wires. [Solution] The present invention provides a power generation element comprising a plurality of magnetic wires made of a magnetic material that produces a large Barkhausen effect, and a pickup coil wound around the central part of the plurality of magnetic wires, wherein the distance between the magnetic wires at both ends is greater than the distance between the magnetic wires at the central part, thereby providing a power generation element that can generate high power generation efficiency and a large amount of power.

Description

Technical Field

[0001] The present disclosure relates to a power generation element, a power generation module, a rotational speed detector, and an encoder.

Background Art

[0002] Conventionally, in order to detect the rotational speed of a motor per unit time without using a battery by self-power generation, or to operate an electronic device with electric power generated by minute vibrations of a structure such as a bridge or machinery in a factory, a power generation element having a magnetic wire with the large Barkhausen effect and a pickup coil has been used. The large Barkhausen effect is a phenomenon in which the magnetization direction is abruptly reversed in response to a change in an external magnetic field.

[0003] A power generation element having a magnetic wire in which the large Barkhausen effect occurs and a pickup coil made of a conductive wire has the pickup coil wound around the magnetic wire. Hereinafter, a power generation element having a magnetic wire in which the large Barkhausen effect occurs and a pickup coil will be simply referred to as a power generation element. When the specific trigger magnetic field intensity is exceeded, the magnetization direction of the magnetic wire abruptly reverses due to the influence of an external magnetic field, and a voltage is generated in the pickup coil in the power generation element.

[0004] In the power generation element, the higher the voltage generated in the pickup coil, the higher the detection accuracy of the rotational speed. Also, in the power generation element, the higher the voltage generated in the pickup coil, the more possible it is to operate a high-performance electronic device. For this reason, in the power generation element, it is required to increase the voltage generated in the pickup coil.

[0005] In the power generation element disclosed in Patent Document 1, since the pickup coil is wound around a plurality (at least two) of magnetic wires, the voltage generated in the pickup coil when the trigger magnetic field intensity is exceeded is higher than that of a power generation element having one magnetic wire.

Prior Art Documents

Patent Documents

[0006] [Patent Document 1] Patent No. 7289359 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] The Great Barkhausen effect is believed to begin with magnetization reversal near both ends of a magnetic wire. When multiple magnetic wires are bundled together, if one of the magnetic wires begins to undergo magnetization reversal, it can cause magnetic interference with the other magnetic wires nearby, leading to a problem of reduced power generation efficiency.

[0008] Therefore, in the power generation element disclosed in Patent Document 1, magnetic interference between magnetic wires mutually inhibits magnetization reversal, so when the number of magnetic wires is N, the voltage generated in the pickup coil becomes lower than the N times voltage when there is one magnetic wire. For this reason, there is a need to realize a power generation element that suppresses the decrease in the voltage generated in the pickup coil due to mutual interference of magnetic wires.

[0009] This disclosure was made to solve the above-mentioned problems, and aims to provide a power generation element that suppresses the decrease in voltage generated in the pickup coil due to mutual interference between magnetic wires. [Means for solving the problem]

[0010] The power generation element according to this disclosure comprises a plurality of magnetic wires made of a magnetic material that produces a large Barkhausen effect, and a pickup coil wound around the central portion of the plurality of magnetic wires, wherein the distance between the magnetic wires at both ends is greater than the distance between the magnetic wires at the central portion. [Effects of the Invention]

[0011] The power generation element according to this disclosure has the effect of suppressing the decrease in voltage generated in the pickup coil due to magnetic field interference between magnetic wires. [Brief explanation of the drawing]

[0012] [Figure 1] This is a perspective view showing the configuration of the power generation element according to Embodiment 1. [Figure 2] This is a schematic diagram illustrating the effect of arranging the magnetic wires of the power generation element according to Embodiment 1 with their ends spaced apart from each other. [Figure 3] This is a perspective view showing a power generation element with a different configuration according to Embodiment 1. [Figure 4] This is a schematic diagram comparing the dimensional relationship of two power generation elements according to Embodiment 1. [Figure 5] This is a schematic diagram comparing the range of magnetic field lines that can be collected by two power generation elements according to Embodiment 1. [Figure 6] This is a perspective view showing the configuration of the power generation element according to Embodiment 2. [Figure 7] This is a perspective view showing the configuration of the power generation element according to Embodiment 3. [Figure 8] This is a perspective view showing an example of the shape of the soft magnetic material of the power generation element according to Embodiment 3. [Figure 9] This is a perspective view showing another soft magnetic material for the power generation element according to Embodiment 3. [Figure 10] This is a perspective view of the power generation element according to Embodiment 3, equipped with another soft magnetic material. [Figure 11] This is a plan view showing the configuration of the holding member for the power generation element according to Embodiment 3. [Figure 12] This is a schematic diagram illustrating the effect of arranging soft magnetic materials at both ends of the magnetic wire of the power generation element according to Embodiment 3. [Figure 13] This is a schematic diagram showing a method for manufacturing a power generation element according to Embodiment 4. [Figure 14] This is a schematic diagram showing another method of manufacturing the power generation element according to Embodiment 4. [Figure 15] This is a perspective view showing the configuration of the power generation element according to Embodiment 5. [Figure 16] This is a perspective view showing the configuration of the rotation speed detector according to Embodiment 6. [Figure 17] It is a plan view showing the arrangement of the power generation element and the magnet of the rotational speed detector according to Embodiment 6. [Figure 18] It is a diagram for explaining an example of a processing circuit of the rotational speed detector according to Embodiment 6. [Figure 19] It is a schematic cross-sectional view of a reflection type optical encoder according to Embodiment 7.

Embodiments for Carrying Out the Invention

[0013] Hereinafter, preferred embodiments of the power generation element according to the present application will be described with reference to the drawings. Note that the same reference numerals are assigned to the same content and corresponding parts, and detailed descriptions thereof are omitted. The same applies to the following embodiments, and duplicate descriptions of the configurations with the same reference numerals are omitted. Note that the embodiments described below are limited to the technologies suitable for implementing the present application, but the technical scope of the present application is not limited to the following embodiments and drawings.

[0014] Embodiment 1. FIG. 1 is a perspective view showing the configuration of the power generation element according to Embodiment 1. The power generation element 10 according to Embodiment 1 includes a plurality of magnetic wires 11 having a large Barkhausen effect, and a pickup coil 12 wound around the bundle of the magnetic wires 11. The magnetic wire 11 can use a Permalloy alloy (FeCoV alloy). In order to generate a large Barkhausen effect, it is necessary to control the internal stress distribution and the composition distribution to have a configuration in which the coercive force is different between the outer peripheral portion and the central portion. Therefore, for example, after drawing a Permalloy alloy having a wire diameter of 0.1 mm to 1 mm into a wire shape, it is twisted to obtain a magnetic wire 11 having a configuration in which the coercive force is different between the outer peripheral portion and the central portion. Note that this is an example and does not limit the wire diameter of the magnetic wire 11.

[0015] The pickup coil 12 is a coil around which a conductive wire is wound, and is positioned to surround the magnetic wire 11, causing the magnetic flux passing through the magnetic wire 11 to link. Due to the Barkhausen effect of the magnetic wire 11, when the magnetic flux inside the magnetic wire 11 changes, the magnetic flux passing through the pickup coil 12 changes. As a result, an electromotive force is generated in the pickup coil 12 by electromagnetic induction, allowing it to function as a power generation element 10.

[0016] The pickup coil 12 using conductive wire can be made of insulated copper wire and is formed by winding the wire onto a bobbin. Alternatively, as described in Embodiment 4, it can be formed by directly winding the wire onto a bundle of magnetic wires 11. In addition to copper wire, gold wire, silver wire, copper alloy wire, aluminum wire, aluminum alloy wire, etc., may also be used. The diameter of the conductive wire is selected based on the diameter of the magnetic wire 11 to be wound around it, the size of the power generation element 10, etc.

[0017] At both ends of the magnetic wire 11, the ends of each of the multiple magnetic wires 11 are spaced apart. The bundle of magnetic wires 11 is twisted so that the diameter is larger at the ends than in the center, and is approximately the same size as the outer diameter of the pickup coil 12. The pickup coil 12 is cylindrical, but it may also be configured to match the shape of the bundle of magnetic wires 11 by winding the wire with a smaller inner diameter in the center and a larger inner diameter at both ends.

[0018] Figure 2 is a schematic diagram illustrating the effect of arranging the ends of multiple magnetic wires 11 at a distance from each other at both ends of the magnetic wire 11 of the power generation element 10 according to Embodiment 1. As an example, it schematically shows the voltage waveform generated in the pickup coil 12 for cases where the ends of three magnetic wires 11 are in contact with each other and when they are spaced apart at both ends. In Figure 2, the vertical axis represents voltage, and the horizontal axis represents the elapsed time from a reference time. The dashed, dotted, and double-dotted waveforms show the voltage waveform when the ends of the three magnetic wires 11 are in contact with each other at both ends, while the solid waveform shows the voltage waveform when the ends of the three magnetic wires 11 are spaced apart at both ends.

[0019] When the ends of the three magnetic wires 11 are in contact with each other, the magnetization reversal due to the Barkhausen effect of each magnetic wire 11 interferes with each other in the magnetic field, and the timing at which the magnetic field strength required for magnetization reversal is reached differs for each magnetic wire 11, resulting in variations in the power generation timing of each magnetic wire 11. If we distinguish the timing at which the magnetic field strength required for magnetization reversal is reached for the three magnetic wires 11 as A, B, and C, then normally, if the three magnetic wires 11 are simply bundled together, each magnetic wire 11 will generate a voltage in the pickup coil 12 at a different timing.

[0020] In the example shown in Figure 2, the time P at which the voltage generated on the pickup coil 12 by the magnetic wire 11 at timing A (indicated by the dashed line) is maximum, and the time Q at which the voltage generated on the pickup coil 12 by the magnetic wire 11 at timing C (indicated by the dashed line) is maximum, are 10 [μs] apart. Therefore, the voltage obtained by superimposing the voltages generated on the pickup coil 12 by each of the three magnetic wires 11 is not three times the voltage generated on the pickup coil 12 by each of the three magnetic wires 11.

[0021] On the other hand, when the magnetic wires 11 with timing A, timing B, and timing C (shown by the dashed line) are arranged with their respective ends spaced apart at both ends, the magnetic field interference between each magnetic wire 11 can be reduced. As a result, the power generation timings of the magnetic wires 11 with timing A, timing B, and timing C are synchronized, as shown by the solid line waveform in Figure 2, and a higher voltage is generated in the pickup coil 12 compared to when the three magnetic wires 11 are in contact.

[0022] Figure 3 is a perspective view showing the configuration of a power generation element 10a in a different form from that shown in Figure 1. Similar to the power generation element 10 in the form shown in Figure 1, the power generation element 10a comprises a plurality of magnetic wires 11 having a large Barkhausen effect and a pickup coil 12 wound around a bundle of magnetic wires 11. However, unlike in Figure 1, the magnetic wires 11 of the power generation element 10a are arranged in parallel so that there is a gap between each of the magnetic wires 11. Even with this configuration, magnetic field interference between each of the magnetic wires 11 is reduced, and a high voltage as shown by the solid line in Figure 3 can be generated. However, when comparing power generation element 10 and power generation element 10a, power generation element 10 has higher power generation efficiency and can generate a larger amount of power for the following reasons.

[0023] Figure 4 is a schematic diagram comparing the dimensional relationship between the power generation element 10 shown in Figure 1 and the power generation element 10a shown in Figure 3. In the dimensions of the power generation element 10a shown in Figure 4(b), the inner diameter B of the pickup coil 12 is always smaller than the outer diameter A of the pickup coil 12, and the outer diameter C of the bundle of magnetic wires 11 is smaller than the inner diameter B of the pickup coil.

[0024] The dimensions of the power generation element 10 shown in Figure 4(a) allow the outer diameter D of both ends of the magnetic wire bundle to be larger than the outer diameter A of the pickup coil 12, and also allow the outer diameter D of both ends of the magnetic wire bundle to be smaller than or equal to the outer diameter A of the pickup coil 12. Since the overall outer diameter of the power generation element 10 is determined by the outer diameter D of both ends of the magnetic wire bundle, increasing the number of turns of the pickup coil 12 after determining the outer diameter D will result in higher power generation efficiency.

[0025] Figure 5 is a schematic diagram comparing the range of magnetic field lines 101 that can be collected by power generation element 10 and power generation element 10a. Of the magnetic field lines 101, those that can be collected are shown as solid lines, and those that cannot be collected are shown as dashed lines. The range of magnetic field lines that can be collected by power generation element 10 in Figure 5(a) is wider than the range of magnetic field lines that can be collected by power generation element 10a in Figure 5(b). This is because the outer diameter D of the bundle of magnetic wires 11 in power generation element 10 is larger than the outer diameter C of the bundle of magnetic wires 11 in power generation element 10a, resulting in a greater amount of magnetic force that can be collected. In other words, power generation element 10 can generate more electricity than power generation element 10a.

[0026] As described above, in the power generation elements 10 and 10a according to Embodiment 1, the ends of the multiple magnetic wires 11 are spaced apart at both ends of the multiple magnetic wires 11, so that the voltage generated in the pickup coil 12 does not decrease due to magnetic field interference between the magnetic wires 11. Furthermore, because the ends of the magnetic wires 11 are spaced apart at both ends of the power generation element 10, the power generation efficiency of the power generation element 10 is higher than that of the power generation element 10a, and the amount of power generated can also be increased.

[0027] Embodiment 2. Figure 6 is a perspective view showing the configuration of the power generation element according to Embodiment 2. The power generation element 10b according to Embodiment 2, like the power generation element 10 according to Embodiment 1, has a plurality of magnetic wires 11 having a large Barkhausen effect and a pickup coil 12 wound around a bundle of magnetic wires 11, with the ends of the plurality of magnetic wires 11 spaced apart at both ends of the magnetic wires 11. The bundle of magnetic wires 11 is twisted such that the outer diameter of the ends is larger than that of the center, and the diameter of both ends of the bundle of magnetic wires 11 is approximately the same as the outer diameter of the pickup coil 12.

[0028] A magnetic field source 70 is placed around the magnetic wire 11. Two magnetic poles, a north pole and a south pole, are used as the magnetic field source 70 to generate a magnetic field that emits magnetic field lines 101. The magnetic field is applied to the magnetic wire 11. For this reason, it is desirable that the magnetic field source 70 be placed below or above the magnetic wire 11 so that the generated magnetic field links with the magnetic wire 11. In this embodiment, the magnetic field source 70 is a magnet. Hereafter, it will be described as a magnet 70. The magnet 70 and the power generation element 10b form a power generation module.

[0029] Of the multiple magnetic wires 11, the length of the magnetic wires 11 further from the magnet 70 is made longer than the magnetic wires 11 closer to the magnet 70. As you move away from the magnet 70, the magnetic force decreases with the square of the distance. Therefore, by changing the number of magnetic field lines 101 used on the side closer to the magnet 70 and the side farther away from the magnet 70, more magnetic force can be applied to the magnetic wires 11 further from the magnet 70, allowing the magnetic force of the magnet 70 to be used to its fullest extent, and a power generation element 10b with high power generation can be obtained. Note that the arrangement of the magnet 70 and power generation element 10b shown in Figure 6 is just one example and is not limited to this.

[0030] Embodiment 3. Figure 7 is a perspective view showing the configuration of the power generation element according to Embodiment 3. The power generation element 10c according to Embodiment 3, like the power generation element 10 according to Embodiment 1, has a plurality of magnetic wires 11 having a large Barkhausen effect and a pickup coil 12 wound around a bundle of magnetic wires 11, and at both ends of the magnetic wires 11, the ends of each of the plurality of magnetic wires 11 are spaced apart from each other. The bundle of magnetic wires 11 is twisted so that the outer diameter of the ends is larger than that of the center, and the diameter of both ends of the bundle of magnetic wires 11 is approximately the same as the outer diameter of the pickup coil 12.

[0031] The magnetic wire 11 is equipped with soft magnetic material 13 at both ends. The soft magnetic material 13 readily undergoes magnetic pole reversal and exhibits high permeability and saturation magnetic flux density. It is sufficient if the permeability is higher than that of air, but it is desirable that it be higher than that of the magnetic wire 11. The soft magnetic material 13 may be made of steel such as SS400 or S45C, magnetic stainless steel such as SUS430 or SUS440, soft ferrite, or high-permeability materials such as permalloy or permendur. Silicon steel, amorphous magnetic alloys, nanocrystal magnetic alloys, and Sendust can also be used. Furthermore, molded products in which ferrite powder is integrated with resin can be considered. The soft magnetic material 13 is disc-shaped, with a groove 202 on its outer circumference for positioning the magnetic wire 11, and an insertion hole 201 in the center for inserting the magnetic wire 11.

[0032] Figure 8 shows another disc-shaped soft magnetic material 13a. An insertion hole 201a for passing a magnetic wire 11 is provided in the center, and a groove 202a for fitting the magnetic wire 11 is provided on the outer circumference. The member forming the groove 202a has a return 203, and when the magnetic wire 11 is fitted into the groove 202a, it is fixed in place by the return 203. In this embodiment, the soft magnetic material 13a has been described as disc-shaped, but it is not limited to this.

[0033] As shown in Figure 9, instead of the soft magnetic materials 13 and 13a having grooves 202 and 202a, a soft magnetic material 13b with an insertion hole 201b for twisting the magnetic wire 11 protruding from the pickup coil 12 may be arranged on both sides of the pickup coil 12. As shown in Figure 9(b), the insertion hole 201b provided in the soft magnetic material 13b is formed so that multiple magnetic wires 11 can be arranged in a twisted shape by inserting the magnetic wire 11 into the insertion hole 201b provided in the soft magnetic material 13b. In this case, the manufacturing method involves passing the magnetic wire 11 through an air-core coil or a pickup coil 12 with a coil wound on a bobbin, then placing soft magnetic materials 13b on both ends of the pickup coil 12, and passing the magnetic wire 11 through the hole in the soft magnetic material 13b from the side furthest from the pickup coil 12. Alternatively, the coil may be wound directly around the wire passed through the soft magnetic material 13b without using a bobbin.

[0034] Furthermore, as shown in Figure 10, the power generation element 10d, the soft magnetic material 13c may be in a simple shape such as a cylinder, and a holding member 15 made of a non-magnetic material such as resin or metal may be provided. The outer circumference of the holding member 15 may have a groove 302 for positioning the magnetic wire 11, and an insertion hole 301 for inserting the magnetic wire 11 may be provided in the center. That is, the holding member 15 has an insertion hole in the center for inserting the magnetic wire 11 placed in the center of the bundle of magnetic wires 11, and grooves around the periphery for engaging with magnetic wires that are not inserted, and the soft magnetic material 13c is provided in contact with the side of the holding member 15 opposite to the side facing the pickup coil 12, and the soft magnetic material 13c has an insertion hole for inserting the magnetic wire 11 inserted into the insertion hole, and the magnetic wire 11 that engages with the groove 302 is in contact with the periphery of the soft magnetic material 13c. Also, as shown in Figure 11, the structure may be such that when the magnetic wire 11 is fitted into the groove 302, it is fixed by a return 303. The soft magnetic materials 13a, 13b, and 13c are molded from the same material as the soft magnetic material 13 described above. The holding member 15 may also be formed from a soft magnetic material, or it may be molded integrally with the resin using ferrite powder or the like.

[0035] Figure 12 is a schematic diagram showing the effect of arranging soft magnetic material 13 at both ends of the magnetic wire 11 of the power generation element 10c according to Embodiment 3. The waveforms of the voltage measured at the pickup coil 12 are schematically shown for the case where soft magnetic material 13 is arranged at both ends of the magnetic wire 11 and the case where it is not. The vertical axis represents voltage, and the horizontal axis represents the elapsed time from a reference time. The dashed line waveform shows the voltage waveform when soft magnetic material 13 is not arranged at both ends of the magnetic wire 11, and the solid line waveform shows the voltage waveform when soft magnetic material 13 is arranged at both ends of the magnetic wire 11. As shown in Figure 7, when soft magnetic material 13 is provided at both ends of the magnetic wire 11, the voltage generated at the pickup coil 12 is higher compared to the case where soft magnetic material 13 is not provided at both ends of the magnetic wire 11. The reason why the voltage generated in the pickup coil 12 can be increased by providing soft magnetic materials 13 at both ends of the magnetic wire 11 is presumed to be that all of the multiple magnetic wires 11 are in contact with the soft magnetic materials 13, which makes the magnetic flux density of the entire magnetic wire 11 between the soft magnetic materials arranged at both ends uniform, thereby widening the region of high magnetic flux density and reducing the magnitude of the demagnetizing field. Soft magnetic materials 13a, 13b, and 13c also produce a similar effect.

[0036] Embodiment 4. Figure 13 is a schematic diagram showing a manufacturing method for the power generation element 10 according to Embodiment 4. In the power generation element 10 according to Embodiment 4, the magnetic wire 11 is fitted and fixed into the groove 202 of the holding member 15 (step S1, omitted in Figure 13). Then, the holding members 15 at both ends are twisted in opposite directions (step S2) to twist the bundle of magnetic wires 11 (step S3). The pickup coil 12 is formed by directly winding wire onto the twisted bundle of magnetic wires 11 (step S4). By arranging multiple bundles of magnetic wires 11 in a twisted shape, the ends of each magnetic wire 11 can be spaced apart. This manufacturing method eliminates the need for a bobbin during winding. Direct winding onto the bundle of magnetic wires 11 may result in uneven winding, but since conductive wires less than 0.1 mm in thickness are wound, priority is given to winding a predetermined number of turns rather than uneven winding. Alternatively, as shown in Figure 14, the magnetic wire 11 may be passed through the pickup coil 12, which is an air-core coil or a pickup coil 12 with conductive wire wound around a bobbin (step S5), and then twisted (step S6).

[0037] Embodiment 5. Figure 15 is a perspective view showing the configuration of a power generation element according to Embodiment 5. In the power generation element 10e, the pickup coil 12 is wound on a bobbin 14, and a member is disposed inside the bobbin 14 that has an insertion hole 401 with an oblique cross-sectional shape so that the inserted magnetic wires 11 can be arranged in a twisted manner. As a result, by simply inserting the magnetic wires 11 into the insertion hole 401 from one end of the bobbin 14, a bundle of multiple magnetic wires 11 can be arranged in a twisted manner, and the ends of each magnetic wire 11 can be separated from each other as the magnetic wires 11 protrude outwards from the bobbin 14.

[0038] Embodiment 6. Figure 16 is a perspective view showing the configuration of the rotation speed detector 40 according to Embodiment 6. The rotation speed detector 40 according to Embodiment 6 is a magnetic rotation speed detector that detects the rotation speed of a rotating body per unit time based on the induced voltage generated in accordance with a change in the magnetic field. The rotation speed detector 40 comprises a power generation element 10 and a processing unit 60. The power generation module 20 consists of a power generation element 10 according to Embodiments 1 to 5 and a magnet 70 which is a magnetic field source arranged opposite the power generation element 10.

[0039] In the example shown in Figure 16, the magnet 70 is a circular, flat magnet that can rotate in direction A. Half of the circular surface facing the power generation element 10 is the north pole, and the other half is the south pole. It is desirable that the magnetization direction of the magnet 70 intersects with the surface of the magnet 70 facing the power generation element 10. For example, it is desirable that the magnetization is such that magnetic flux exits from the surface constituting the north pole of the magnet 70 towards the power generation element 10 and enters from the power generation element 10 side into the surface constituting the south pole. It is also desirable that the magnetization direction be perpendicular or nearly perpendicular to the surface facing the power generation element 10. However, this is merely an example and does not limit the magnetization direction.

[0040] It is preferable to use a permanent magnet for magnet 70. However, any magnet capable of stably generating a magnetic field is acceptable, and an electromagnet may also be used. As permanent magnets, ferrite magnets, neodymium magnets, alnico magnets, samarium-cobalt magnets, and other rare-earth magnets can be used. Alternatively, magnetic material particles can be incorporated into a plastic material and molded by injection molding or the like to create a magnet.

[0041] The magnet 70 is attached to the shaft 21 and rotates together with the shaft 21. As the magnet 70 rotates, the magnetic poles applied to the power generation element 10 switch. The power generation element 10 generates a pulsed induced voltage in the pickup coil 12 in accordance with the change in the magnetic field caused by the rotation of the magnet 70. The signal generated by the voltage in the pickup coil 12 is input to the processing unit 60.

[0042] The processing unit 60 counts the number of pulses generated based on the signal from the power generation element 10. By counting the number of pulses, the processing unit 60 detects the rotational speed of the shaft 21 per unit time. Since the processing unit 60 can operate using the induced voltage generated in the power generation element 10, it can detect the rotational speed of the shaft 21 without a power supply.

[0043] The power generation element 10 is positioned opposite the magnet 70 in a direction parallel to the rotation axis 22 of the shaft 21. In Figure 16, the power generation element 10 is positioned opposite the surface of the magnet 70 that is not fixed to the shaft 21, but the power generation element 10 may also be positioned opposite the surface of the magnet 70 that is fixed to the shaft 21.

[0044] Figure 17 is a plan view showing the arrangement of the rotation speed detector 40 and the magnet 70. This view is taken from a direction parallel to the rotation axis 22 shown in Figure 16, and from the side opposite to the shaft 21, showing the magnet 70 and the power generation element 10, with the processing unit 60 omitted. The power generation element 10 is positioned opposite the disc-shaped magnet 70 at a distance from the center 71 of the magnet 70. Such a rotation speed detector 40 is used as a reflective optical encoder together with an angle detector.

[0045] Figure 18 shows the hardware of a microcontroller as an example of the processing unit 60. It consists of a processor 300 and a storage device 400. Although not shown, the storage device 400 includes a volatile storage device such as random access memory and a non-volatile auxiliary storage device such as flash memory. Alternatively, a hard disk may be provided as an auxiliary storage device instead of flash memory. The processor 300 may detect the rotational speed by executing a program input from the storage device 400 and may, for example, communicate with other devices. In this case, the program is input from the auxiliary storage device to the processor 300 via the volatile storage device. The processor 300 may also output data such as calculation results to the volatile storage device of the storage device 400, or it may save the data to the auxiliary storage device via the volatile storage device. Note that the processing unit 60 may be configured not with a microcontroller, but with simpler logic circuits, analog circuits, etc., or a combination of these may be used.

[0046] The rotation speed detector 40 according to Embodiment 6 can suppress the decrease in the voltage generated in the pickup coil 12 due to magnetic field interference between the magnetic wires 11, thereby increasing the voltage generated in the pickup coil 12 by the rotation of the shaft 21.

[0047] Embodiment 7. Figure 19 shows a schematic cross-sectional view of the reflective optical encoder 200. The reflective optical encoder 200 is attached to the motor 41. A shaft 21 is connected to the motor rotation shaft 42 of the motor 41, and a magnet 70 is fixed to the shaft 21. The magnet 70 and the scale plate 51, which has an optical slit fixed to the upper surface of the magnet 70, are covered by a substrate 63, a housing 61 arranged around it, and a housing 62 through which the shaft 21 passes. A rotation speed detector 40 is located on the outer surface of the substrate 63, and a light-emitting part 53 and a light-receiving part 55 of the angle detector are located on the inner surface.

[0048] The angle detector comprises a scale plate 51, a light-emitting unit 53 that generates illumination light 52, and a light-receiving unit 55 that detects reflected light 54 emitted from the light-emitting unit 53 and passing through the optical slit of the scale plate 51. For example, the scale plate 51 is fixed on the upper side of the magnet 70. The light-emitting unit 53 and the light-receiving unit 55 are provided in positions facing the scale plate 51.

[0049] In the reflective optical encoder 200, when the shaft 21 rotates, the light 52 emitted from the light-emitting unit 53 is reflected by optical slits formed on the scale plate 51, which are composed of high-reflectivity and low-reflectivity areas. The light-receiving unit 55 detects the change in the amount of reflected light 54, thereby detecting the rotation angle and rotation speed. Furthermore, the rotation speed detector 40 detects the rotation speed from the reference position by the power generation element 10 generating electricity due to the change in the direction of the magnetic force emitted from the magnet 70, and the processing unit 60 calculates the rotation speed per unit time. Since the shaft 21 rotates together with the motor rotation axis 42 of the motor 41, the reflective optical encoder 200 can detect the rotation angle and rotation speed of the motor 41 by detecting the rotation angle and rotation speed of the shaft 21. Note that the processing unit 60 may be common to both the angle detector and the rotation speed detector 40.

[0050] While this disclosure describes various exemplary embodiments and examples, the various features, aspects, and functions described in one or more embodiments are not limited to the application of a particular embodiment, but can be applied individually or in various combinations to the embodiments. Accordingly, countless variations not illustrated are conceivable within the scope of the technology disclosed in the specification. These include, for example, modifying, adding or omitting at least one component, or even extracting at least one component and combining it with components of other embodiments.

[0051] The various aspects of this disclosure are summarized below as an appendix.

[0052] [Note 1] A power generation element comprising a plurality of magnetic wires made of a magnetic material that produces a large Barkhausen effect, and a pickup coil wound around the central part of the plurality of magnetic wires, wherein the distance between the magnetic wires at both ends is greater than the distance between the magnetic wires at the central part. [Note 2] A power generation element comprising a bundle of multiple magnetic wires made of a magnetic material that produces a large Barkhausen effect, and a pickup coil wound around the central part of the bundle of magnetic wires, wherein the outer diameter of the bundle of magnetic wires at the ends is larger than the outer diameter of the bundle of magnetic wires at the central part. [Note 3] The power generation element according to Appendix 1 or 2, having a soft magnetic material that contacts both ends of the plurality of magnetic wires. [Note 4] The power generation element according to Appendix 3, characterized in that an insertion hole is provided in the center of the soft magnetic material for inserting the magnetic wire positioned in the center of the plurality of magnetic wires, and grooves are provided around it for engaging with magnetic wires that are not inserted. [Note 5] The power generation element according to Appendix 4, characterized in that a return for fixing a magnetic wire engaged in the groove is formed on the member forming the groove. [Note 6] The power generation element according to Appendix 1 or 2, comprising a central insertion hole for inserting the centrally positioned magnetic wire among the plurality of magnetic wires, grooves for engaging with the uninserted magnetic wires provided around the periphery, and a holding member made of resin. [Note 7] The power generation element according to Appendix 2, comprising: a holding member having an insertion hole in the center of a bundle of magnetic wires into which a magnetic wire positioned in the center is inserted, and a groove around the periphery that engages with magnetic wires that are not inserted; and a soft magnetic material provided in contact with the side of the holding member opposite to the side facing the pickup coil, wherein the soft magnetic material has an insertion hole into which the magnetic wire inserted into the insertion hole is inserted, and the magnetic wire that engages with the groove is in contact with the periphery of the soft magnetic material. [Note 8] The power generation element according to appendix 6 or 7, characterized in that a return for fixing a magnetic wire engaged in the groove is formed on the member forming the groove. [Note 9] The power generation element according to Appendix 1 or 2, characterized in that the pickup coil is wound around a bobbin, the bobbin has two or more insertion holes for inserting the magnetic wire, and the cross-sectional shape of the insertion holes is inclined so that the magnetic wire inserted from the inside to the outside of the bobbin spreads outwards. [Note 10] A power generation module comprising a power generation element described in any one of the appendices 1 to 9, and a magnetic field source for applying a magnetic field to the magnetic material. [Note 11] The power generation module according to Appendix 10, characterized in that the magnetic field source is placed above or below the power generation element, and the portion of the plurality of magnetic wires protruding from the pickup coil is longer on the side farther from the magnetic field source than on the side closer to the magnetic field source. [Note 12] The power generation module described in Appendix 10 or 11 has a rotating magnet as the magnetic field source, and a rotation speed detector equipped with a processing unit that counts voltage pulses generated in the pickup coil as the magnetic poles applied to the plurality of magnetic wires switch as the magnet rotates. [Note 13] An encoder comprising a rotation speed detector as described in Appendix 12, and a detector comprising a light-emitting unit, a light-receiving unit, and an optical slit for detecting rotation angle and rotation speed. [Explanation of Symbols]

[0053] 10, 10a, 10b, 10c, 10d, 10e: Power generation element, 11: Magnetic wire, 12: Pickup coil, 13, 13a, 13b, 13c: Soft magnetic material, 14: Bobbin, 15: Holding member, 20: Power generation module, 21: Shaft, 22: Rotating axis, 40: Rotation speed detector, 41: Motor, 42: Motor rotating axis, 51: Scale plate, 52: Irradiated light, 53: Light-emitting part, 54: Reflected light, 55: Light-receiving part, 60: Processing unit, 61, 62: Housing, 63: Substrate, 70: Magnet, 71: Center, 101: Magnetic field lines, 200: Reflective optical encoder, 201, 201a, 201b, 301, 401: Insertion hole, 202, 202a, 302: Groove, 203, 303: Return.

Claims

1. A power generation element comprising a plurality of magnetic wires made of a magnetic material that produces a large Barkhausen effect, and a pickup coil wound around the central part of the plurality of magnetic wires, wherein the distance between the magnetic wires at both ends is greater than the distance between the magnetic wires at the central part.

2. A power generation element comprising a bundle of multiple magnetic wires made of a magnetic material that produces a large Barkhausen effect, and a pickup coil wound around the central part of the bundle of magnetic wires, wherein the outer diameter of the bundle of magnetic wires at the ends is larger than the outer diameter of the bundle of magnetic wires at the central part.

3. The power generation element according to claim 1 or 2, having a soft magnetic material that contacts both ends of the plurality of magnetic wires.

4. The power generation element according to claim 3, characterized in that an insertion hole is provided in the center of the soft magnetic material for inserting the magnetic wire positioned in the center of the plurality of magnetic wires, and grooves are provided around it for engaging with magnetic wires that are not inserted.

5. The power generation element according to claim 4, characterized in that a return for fixing a magnetic wire engaged with the groove is formed on the member forming the groove.

6. The power generation element according to claim 1 or 2, wherein an insertion hole is provided in the center for inserting the centrally positioned magnetic wire among the plurality of magnetic wires, grooves are provided around the periphery for engaging with magnetic wires that are not inserted, and the element comprises a holding member made of resin.

7. The power generation element according to claim 2, comprising: a holding member having an insertion hole in the center of a bundle of magnetic wires into which a magnetic wire positioned in the center is inserted, and grooves around the periphery that engage with magnetic wires that are not inserted; and a soft magnetic material provided in contact with the side of the holding member opposite to the side facing the pickup coil, wherein the soft magnetic material has an insertion hole into which the magnetic wire inserted into the insertion hole is inserted, and the magnetic wire that engages with the grooves is in contact with the periphery of the soft magnetic material.

8. The power generation element according to claim 7, characterized in that a return for fixing a magnetic wire engaged with the groove is formed on the member forming the groove.

9. The power generation element according to claim 1 or 2, characterized in that the pickup coil is wound around a bobbin, the bobbin has two or more insertion holes for inserting the magnetic wire, and the cross-sectional shape of the insertion holes is inclined so that the magnetic wire inserted from the inside to the outside of the bobbin spreads outwards.

10. A power generation module comprising a power generation element according to claim 1 or 2, and a magnetic field source for applying a magnetic field to the magnetic wire.

11. The power generation module according to claim 10, wherein the magnetic field source is placed above or below the power generation element, and the portion of the plurality of magnetic wires protruding from the pickup coil is longer on the side farther from the magnetic field source than on the side closer to the magnetic field source.

12. The power generation module according to claim 10 is a rotating magnet as the magnetic field source, and the rotation speed detector is equipped with a processing unit that counts voltage pulses generated in the pickup coil as the magnetic poles applied to the plurality of magnetic wires switch as the magnet rotates.

13. An encoder comprising a rotation speed detector according to claim 12, and a detector comprising a light-emitting unit, a light-receiving unit, and an optical slit for detecting rotation angle and rotation speed.

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