Rotation detector and rotation detection method

Abstract

Provided is a rotation detector that makes it possible to reduce occurrence of false detections. This rotation detector (14) comprises: a magnet (20) that rotates with a rotating shaft; a plurality of power generation elements (22), (24) that generate electric power through changes in a magnetic field resulting from the magnet (20) rotating with the rotating shaft; and a plurality of magnetic sensors (26), (28) provided corresponding to the plurality of power generation elements (22), (24). The rotation detector (14) further comprises: an information processing unit (56) that determines the rotational position of the rotating shaft using the plurality of magnetic sensors (26), (28); and a generated power supply unit (46) that supplies the electric power generated by each of the plurality of power generation elements (22), (24) only to the magnetic sensor corresponding to the power generation element, out of the plurality of magnetic sensors (26), (28).

Description

[Technical Field]

[0001] The present disclosure relates to a rotation detector and a rotation detection method, and more particularly to a rotation detector and a rotation detection method for detecting rotation of a rotation shaft of a rotating body. [Background technology]

[0002] Conventionally, rotation detectors that detect the rotation of a rotating shaft of a motor have been known. For example, Patent Document 1 discloses a rotation detector that includes a disk-shaped magnet attached to a shaft and three power generating units each composed of a magnetic wire and a pickup coil, with the three power generating units being arranged on each of the multiple sides of an imaginary triangle formed on the end face side of the magnet. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6336232 Summary of the Invention

[0004] However, the rotation detector of Patent Document 1 has a problem in that the power generated by the power generating unit cannot be supplied appropriately, resulting in false detection.

[0005] The present disclosure has been made to solve such problems, and has an object to provide a rotation detector and a rotation detection method that can suppress the occurrence of erroneous detection.

[0006] A rotation detector according to one aspect of the present disclosure includes a magnet that rotates together with a rotation shaft, a plurality of power generating elements that generate power by changes in a magnetic field caused by the rotation of the magnet together with the rotation shaft, and a plurality of magnetic sensors provided corresponding to the plurality of power generating elements, an information processing unit that determines a rotational position of the rotation shaft using the plurality of magnetic sensors, and a generated power supply unit that supplies power generated by each of the plurality of power generating elements only to the magnetic sensor of the plurality of magnetic sensors that corresponds to that power generating element.

[0007] A rotation detection method according to one aspect of the present disclosure is a rotation detection method using a rotation detector. The rotation detector includes a magnet that rotates with a rotation shaft, a plurality of power generating elements that generate power due to changes in a magnetic field caused by the rotation of the magnet with the rotation shaft, a plurality of magnetic sensors provided corresponding to the plurality of power generating elements, and a generated power supply unit that supplies the power generated by each of the plurality of power generating elements only to the magnetic sensor of the plurality of magnetic sensors corresponding to that power generating element. The rotation detection method determines in which of a plurality of regions aligned in the rotation direction of the rotation shaft a reference position is located, based on power generation information indicating a power generating element that generated power and detection information indicating a detection result of the magnetic sensor of the plurality of magnetic sensors corresponding to that power generating element, and stores the region of the plurality of regions in which it is determined that the reference position is located.

[0008] According to the present disclosure, it is possible to provide a rotation detector and a rotation detection method that can suppress the occurrence of false detection. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram showing a motor including a rotation detector according to a first embodiment. [Figure 2] FIG. 2 is a diagram showing the substrate and rotating plate of the rotation detector of FIG. [Figure 3] FIG. 3 is a block diagram showing the functional configuration of the rotation detector of FIG. [Figure 4]FIG. 4 is a diagram for explaining an example of the determination operation of the rotation detector of FIG. 1 when the rotation shaft rotates clockwise. [Figure 5] FIG. 5 is a diagram for explaining an example of the determination operation of the rotation detector of FIG. 1 when the rotation shaft rotates counterclockwise. [Figure 6] FIG. 6 is a diagram showing a rotation detector according to the second embodiment. [Figure 7] FIG. 7 is a block diagram showing a part of the functional configuration of the rotation detector of FIG. [Figure 8] FIG. 8 is a block diagram showing another part of the functional configuration of the rotation detector of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present disclosure will be described. Note that each of the embodiments described below represents a specific example of the present disclosure. Therefore, the numerical values, components, the arrangement and connection of the components, steps, and the order of steps shown in the following embodiments are merely examples and are not intended to limit the present disclosure. Therefore, among the components in the following embodiments, components that are not described in the independent claims that represent the superordinate concept of the present disclosure will be described as optional components.

[0011] In addition, each drawing is a schematic diagram and is not necessarily a precise illustration. In all drawings, substantially the same components are denoted by the same reference numerals, and redundant explanations will be omitted or simplified.

[0012] (First embodiment) FIG. 1 is a diagram showing a motor 1 including a rotation detector 14 according to a first embodiment. FIG. 2 is a diagram showing a substrate 18 and a rotating plate 16 of the rotation detector 14 of FIG. 1. (a) of FIG. 2 shows the substrate 18, and (b) of FIG. 2 shows the rotating plate 16. Note that FIG. 1 shows cross sections of a case 12, a magnet 20, and a reflective pattern 44. Also, FIG. 1 does not show the power generating element 22 and the control circuit 32 shown in FIG. 2. Also, FIG. 2 does not show the optical sensor 30 shown in FIG. 1.

[0013] As shown in Fig. 1, motor 1 includes a main body 4, a rotor 6, a stator 8, a rotating shaft 10, a case 12, and a rotation detector 14. The rotation axis direction is the direction in which rotation axis A of rotating shaft 10 extends (see arrow X in Fig. 1).

[0014] The rotor 6 and the stator 8 are housed in the body 4. The rotor 6 rotates relative to the stator 8.

[0015] The rotating shaft 10 extends in the direction of the rotation axis and is rod-shaped, such as a cylindrical shape. The axial center of the rotating shaft 10 coincides with the rotation axis A. The rotating shaft 10 is fixed to the rotor 6 and rotates around the rotation axis A. For example, when power is supplied to the motor 1, the rotating shaft 10 rotates together with the rotor 6 around the rotation axis A based on the power. The rotation direction of the rotating shaft 10 (see arrow Z in FIG. 2 ) coincides with the circumferential direction centered on the rotation axis A. A rotation detector 14 is provided at one end of the rotating shaft 10 in the direction of the rotation axis. A load (not shown) that is rotationally driven by the rotation of the rotating shaft 10 is attached to the other end of the rotating shaft 10 in the direction of the rotation axis. For example, the rotating shaft 10 is formed of a magnetic metal such as iron.

[0016] The case 12 is attached to the main body 4 so as to cover one end of the rotating shaft 10 in the direction of the rotation axis and the rotation detector 14. For example, the case 12 is made of a magnetic metal such as iron.

[0017] The rotation detector 14 detects the rotation of the rotating shaft 10. For example, the rotation detector 14 detects the rotation position, rotation direction, and rotation speed of the rotating shaft 10. For example, the rotation detector 14 is an absolute encoder. As described above, the rotation detector 14 is provided at one end of the rotating shaft 10 in the direction of the rotation axis. As shown in FIGS. 1 and 2 , the rotation detector 14 has a rotating plate 16, a substrate 18, a magnet 20, a plurality of power generating elements 22, 24, a plurality of magnetic sensors 26, 28, an optical sensor 30, and a control circuit 32.

[0018] The rotating plate 16 extends in a direction perpendicular to the rotation axis direction. Specifically, the rotating plate 16 is disk-shaped with a main surface extending in a direction perpendicular to the rotation axis direction, and is circular when viewed from the rotation axis direction. The rotating plate 16 is attached to one end of the rotating shaft 10 in the rotation axis direction. The axis of the rotating plate 16 and the rotation axis A are aligned. The rotating plate 16 rotates together with the rotating shaft 10.

[0019] The base plate 18 extends in a direction perpendicular to the rotation axis direction. Specifically, the base plate 18 is disk-shaped with a main surface extending in a direction perpendicular to the rotation axis direction, and is circular when viewed from the rotation axis direction. The base plate 18 is disposed at a distance from one end of the rotating shaft 10 and the rotating plate 16 in the rotation axis direction, and faces the rotating plate 16. The axis of the base plate 18 coincides with the rotation axis A. The base plate 18 is fixed to the inner surface of the case 12 and does not rotate together with the rotating shaft 10.

[0020] The magnet 20 rotates together with the rotating shaft 10. Specifically, when the rotating shaft 10 rotates, the magnet 20 rotates together with the rotating shaft 10 and the rotating plate 16. The magnet 20 is annular and arranged along the rotation direction of the rotating shaft 10. The magnet 20 is plate-shaped with its thickness direction aligned with the rotation axis direction. The magnet 20 is arranged on the main surface of the rotating plate 16 opposite the substrate 18. The magnet 20 has an N pole and an S pole arranged alongside the N pole in the rotation direction of the rotating shaft 10. One half of the magnet 20 is magnetized to the N pole, and the other half of the magnet 20 is magnetized to the S pole.

[0021] Each of the plurality of power generating elements 22, 24 generates power by the change in magnetic field caused by the rotation of the magnet 20 together with the rotating shaft 10.

[0022] The multiple power generating elements 22, 24 are arranged with a phase difference in the rotation direction of the rotating shaft 10. Specifically, the multiple power generating elements 22, 24 are arranged at an angular interval in the rotation direction of the rotating shaft 10 that is equal to or greater than the angular interval between a first position where one of the multiple power generating elements 22, 24 generates power when the rotating shaft 10 rotates clockwise, and a second position that is closest to the first position among one or more positions where the one power generating element generates power when the rotating shaft 10 rotates counterclockwise. Note that clockwise means clockwise when viewed from the opposite side of the rotation axis line from the rotating plate 16 of the substrate 18, and counterclockwise means counterclockwise when viewed from the opposite side of the rotation axis line from the rotating plate 16 of the substrate 18. The same applies to the following description.

[0023] FIG. 4 is a diagram illustrating an example of the determination operation of the rotation detector 14 when the rotating shaft 10 rotates clockwise. For example, position i shown in FIG. 4 is an example of a first position at which one power generating element 22 of the multiple power generating elements 22, 24 generates power when the rotating shaft 10 rotates clockwise. Position viii shown in FIG. 4 is an example of a second position closest to position i among one or more positions vi, viii at which one power generating element 22 generates power when the rotating shaft 10 rotates counterclockwise. The angular interval between positions i and viii in the rotation direction of the rotating shaft 10 is 30 degrees, and the multiple power generating elements 22, 24 are arranged at angular intervals of 30 degrees or more in the rotation direction of the rotating shaft 10. In this embodiment, the multiple power generating elements 22, 24 are arranged at angular intervals of 120 degrees in the rotation direction of the rotating shaft 10.

[0024] For example, the angular interval between the power generating element 22 and the power generating element 24 in the rotation direction of the rotating shaft 10 is the angle formed by a center line extending radially around the rotation axis A (see arrow Y in Figure 2) and passing through the longitudinal center of the magnetic sensing section 34 of the power generating element 22, and a center line extending radially around the rotation axis A and passing through the longitudinal center of the magnetic sensing section 38 of the power generating element 24.

[0025] The power generating element 22 extends in a tangential direction to the rotation direction of the rotating shaft 10, and is disposed on the main surface of the substrate 18 on the opposite side to the rotating shaft 10 (the opposite side to the rotating plate 16). The power generating element 22 has a magnetic field sensing unit 34 and a coil 36 wound around the magnetic field sensing unit 34. The magnetic field sensing unit 34 is a magnetic material that extends in a tangential direction to the rotation direction of the rotating shaft 10, and is located on the opposite side of the substrate 18 to the rotating plate 16. For example, the magnetic field sensing unit 34 is a magnetic material that exhibits the large Barkhausen effect, and is a Wiegand wire that extends in a tangential direction to the rotation direction of the rotating shaft 10. The Wiegand wire is a magnetic material whose magnetization direction is aligned to one side of the longitudinal direction when a magnetic field of a predetermined value or greater is applied along the longitudinal direction of the Wiegand wire. When the direction of the magnetic flux flowing along the length of the Wiegand wire changes, the magnetization direction of the Wiegand wire suddenly reverses, and a voltage pulse is induced across the coil wound around the Wiegand wire. In this way, the power generating element 22 generates electricity.

[0026] The power generating element 24 extends in a tangential direction to the rotation direction of the rotating shaft 10, and is disposed on the main surface of the substrate 18 opposite to the rotating shaft 10 (opposite to the rotating plate 16). The power generating element 24 has a magnetic field sensing part 38 and a coil 40 wound around the magnetic field sensing part 38. The magnetic field sensing part 38 is a magnetic material extending in a tangential direction to the rotation direction of the rotating shaft 10, and is located on the substrate 18 opposite to the rotating plate 16. For example, the magnetic field sensing part 38 is a magnetic material that exhibits the large Barkhausen effect, and is a Wiegand wire extending in a tangential direction to the rotation direction of the rotating shaft 10. The power generating element 24 generates electricity in the same manner as the power generating element 22.

[0027] The plurality of magnetic sensors 26, 28 are provided corresponding to the plurality of power generating elements 22, 24, respectively. The magnetic sensor 26 is provided corresponding to the power generating element 22 and operates based on the power generated by the power generating element 22. The magnetic sensor 28 is provided corresponding to the power generating element 24 and operates based on the power generated by the power generating element 24. The plurality of magnetic sensors 26, 28 are arranged on the main surface of the substrate 18 on the rotating shaft 10 side (rotating plate 16 side).

[0028] The multiple magnetic sensors 26, 28 are arranged with a phase difference in the rotation direction of the rotating shaft 10. Specifically, each of the multiple magnetic sensors 26, 28 is arranged in the same position as a corresponding one of the multiple power generating elements 22, 24 in the rotation direction of the rotating shaft 10.

[0029] The magnetic sensor 26 is disposed at the same position as the power generating element 22 in the rotation direction of the rotating shaft 10. For example, the magnetic sensor 26 is disposed so that the center of the magnetic sensor 26 is located on a center line that extends in a radial direction about the rotation axis A and passes through the longitudinal center of the magnetic sensing section 34 of the power generating element 22. The magnetic sensor 26 is disposed alongside the power generating element 22 in the radial direction about the rotation axis A, and further outward than the power generating element 22.

[0030] The magnetic sensor 28 is disposed at the same position as the power generating element 24 in the rotation direction of the rotating shaft 10. For example, the magnetic sensor 28 is disposed so that the center of the magnetic sensor 28 is located on a center line that extends in a radial direction about the rotation axis A and passes through the longitudinal center of the magnetic sensing section 38 of the power generating element 24. The magnetic sensor 28 is disposed alongside the power generating element 24 in the radial direction about the rotation axis A, and further outward than the power generating element 24.

[0031] The optical sensor 30 is an optical encoder that has a light emitting / receiving element 42 and a reflection pattern 44 and detects the amount of rotation of the rotary shaft 10 .

[0032] The light emitting / receiving element 42 is disposed on the main surface of the substrate 18 facing the rotating plate 16, and operates based on power from an external power source 150 (see the functional block diagram shown in FIG. 3). The light emitting / receiving element 42 faces the reflection pattern 44 in the direction of the rotation axis, and emits light toward the reflection pattern 44. The light emitting / receiving element 42 also receives light reflected by the reflection pattern 44. The light reflected by the reflection pattern 44 changes depending on the rotation position of the rotating shaft 10. The optical sensor 30 detects the amount of rotation of the rotating shaft 10 based on the light reflected by the reflection pattern 44. In this embodiment, the light emitting / receiving element 42 corresponds to a light emitting element and a light receiving element.

[0033] The reflective pattern 44 is disposed on the main surface of the rotating plate 16 facing the substrate 18. The reflective pattern 44 is disposed along the rotation direction of the rotating shaft 10 and is annular. For example, the reflective pattern 44 has reflective areas that easily reflect light and non-reflective areas that do not easily reflect light. For example, the reflective areas and non-reflective areas are disposed alternately in the rotation direction of the rotating shaft 10.

[0034] The control circuit 32 is disposed on the main surface of the substrate 18 on the rotating shaft 10 side (rotating plate 16 side), and is electrically connected to the power generating element 22 and the like.

[0035] FIG. 3 is a block diagram showing the functional configuration of the rotation detector 14 of FIG.

[0036] As shown in FIG. 3, the rotation detector 14 further includes a generated power supply unit 46, a polarity determination unit 47, a magnetic pole determination unit 51, a signal processing unit 55, an information processing unit 56, a memory unit 58, and a communication unit 60.

[0037] The generated power supply unit 46 supplies the power generated by each of the multiple power generating elements 22, 24 only to the magnetic sensor corresponding to that power generating element among the multiple magnetic sensors 26, 28. For example, the generated power supply unit 46 supplies the power generated by the power generating element 22 only to the magnetic sensor 26 among the multiple magnetic sensors 26, 28, and supplies the power generated by the power generating element 24 only to the magnetic sensor 28 among the multiple magnetic sensors 26, 28.

[0038] The generated power supply unit 46 has a plurality of full-wave rectification units 62, 64, a sensor power storage unit 66, a power storage unit 67, a plurality of switches 72, 74, 76, a plurality of internal power supplies 78, 80, a plurality of power supply monitoring units 82, 84, 86, 88, 89, a plurality of voltage adjustment units 90, 92, a plurality of discharge units 94, 96, 98, and a plurality of switches 100, 102.

[0039] The full-wave rectifier 62 is connected to the power generating element 22 and rectifies the voltage pulse generated by the power generating element 22. The full-wave rectifier 64 is connected to the power generating element 24 and rectifies the voltage pulse generated by the power generating element 24.

[0040] The sensor power storage unit 66 stores the power generated by each of the plurality of power generating elements 22, 24 and supplied to the magnetic sensor corresponding to that power generating element among the plurality of magnetic sensors 26, 28. When the power generating element 22 generates power, the sensor power storage unit 66 stores the power generated by the power generating element 22 and supplied to the magnetic sensor 26. When the power generating element 24 generates power, the sensor power storage unit 66 stores the power generated by the power generating element 24 and supplied to the magnetic sensor 28.

[0041] The power storage unit 67 stores the power generated by each of the plurality of power generating elements 22, 24 and supplied to parts other than the plurality of magnetic sensors 26, 28. The power storage unit 67 has a first storage unit 68 that stores the power generated by the power generating element 22 and supplied to parts other than the magnetic sensor 26, and a second storage unit 70 that stores the power generated by the power generating element 24 and supplied to parts other than the magnetic sensor 28.

[0042] The switch 72 is an example of a disconnecting unit that can electrically disconnect the sensor power storage unit 66 and the power storage unit 67. The switch 72 is in an OFF state that cuts off power when neither the power generating element 22 nor the power generating element 24 is generating power, and electrically disconnects the sensor power storage unit 66 and the power storage unit 67. The switch 72 is in an ON state that allows power transmission during a period when one of the power generating element 22 or the power generating element 24 is generating power. The switch 74 is in an OFF state that cuts off power when the power generating element 22 is not generating power, and is in an ON state that allows power transmission during a period when the power generating element 22 is generating power. The switch 76 is in an OFF state that cuts off power when the power generating element 24 is not generating power, and is in an ON state that allows power transmission during a period when the power generating element 24 is generating power.

[0043] The internal power supply 78 is a power supply that receives power stored in the sensor power storage unit 66 and supplies the power to the magnetic sensor 26 or the magnetic sensor 28. The internal power supply 80 is a power supply that receives power stored in the power storage unit 67 and supplies the power to components other than the plurality of magnetic sensors 26, 28, such as the information processing unit 56.

[0044] The power supply monitoring unit 82 monitors the power between the sensor power storage unit 66 and the voltage adjustment unit 90. The power supply monitoring unit 84 monitors the power between the voltage adjustment unit 90 and the internal power supply 78. The power supply monitoring unit 86 monitors the power between the full-wave rectification unit 62 and the first storage unit 68. The power supply monitoring unit 88 monitors the power between the full-wave rectification unit 64 and the second storage unit 70. The power supply monitoring unit 89 monitors the power between the voltage adjustment unit 92 and the internal power supply 80.

[0045] The voltage adjustment unit 90 uses the ground potential as a reference potential and the voltage across the terminals of the capacitor of the sensor power storage unit 66 as an input voltage, and outputs a constant voltage. The output voltage of the voltage adjustment unit 90 is supplied to the internal power supply 78. The voltage adjustment unit 92 uses the ground potential as a reference potential and the voltage across the terminals of the capacitor of the first storage unit 68 or the second storage unit 70 as an input voltage, and outputs a constant voltage. The output voltage of the voltage adjustment unit 92 is supplied to the internal power supply 80. For example, each of the multiple voltage adjustment units 90, 92 is an LDO (Low Drop Out) regulator.

[0046] The discharge unit 94 discharges the power stored in the sensor power storage unit 66 when the power generating element 22 and the power generating element 24 are not generating power. The discharge unit 96 discharges the power stored in the first storage unit 68 when the power generating element 22 is not generating power. The discharge unit 98 discharges the power stored in the second storage unit 70 when the power generating element 24 is not generating power.

[0047] The switch 100 is in an OFF state to block power from the internal power supply 78 from being supplied to the magnetic sensor 26 when the power generating element 22 is not generating power, and is in an ON state to allow power from the internal power supply 78 to be transmitted to the magnetic sensor 26 while the power generating element 22 is generating power. The switch 102 is in an OFF state to block power from the internal power supply 78 from being supplied to the magnetic sensor 28 when the power generating element 24 is not generating power, and is in an ON state to allow power from the internal power supply 78 to be transmitted to the magnetic sensor 28 while the power generating element 24 is generating power.

[0048] The polarity determination unit 47 determines the polarity of the power generated by each of the power generating elements 22, 24. The polarity determination unit 47 has a first determination unit 48 that determines the polarity of the power generated by the power generating element 22 and a second determination unit 50 that determines the polarity of the power generated by the power generating element 24.

[0049] The magnetic pole determination unit 51 determines the magnetic pole detected by each of the multiple magnetic sensors 26, 28. The magnetic pole determination unit 51 has a first determination unit 52 that determines the magnetic pole detected by the magnetic sensor 26 and a second determination unit 54 that determines the magnetic pole detected by the magnetic sensor 28.

[0050] The signal processing unit 55 is driven by power from an external power supply 150 and transmits the detection results of the optical sensor 30 to the information processing unit 56 .

[0051] The information processing unit 56 uses the plurality of magnetic sensors 26, 28 to determine the rotational position of the rotating shaft 10. The determination of the rotational position of the rotating shaft 10 by the information processing unit 56 will be described later.

[0052] The storage unit 58 stores the rotation position, rotation direction, etc. of the rotating shaft 10. For example, the storage unit 58 is configured by a nonvolatile memory such as FRAM (registered trademark).

[0053] The communication unit 60 connects the information processing unit 56 and the signal processing unit 55 so as to enable wired or wireless communication between them.

[0054] Fig. 4 is a diagram for explaining an example of the determination operation of the rotation detector 14 of Fig. 1 when the rotating shaft 10 rotates clockwise. Fig. 4(a) shows a state in which the reference position B is located at position i, Fig. 4(b) shows a state in which the reference position B is located at position ii, Fig. 4(c) shows a state in which the reference position B is located at position iii, and Fig. 4(d) shows a state in which the reference position B is located at position iv.

[0055] Fig. 5 is a diagram for explaining an example of the determination operation of the rotation detector 14 of Fig. 1 when the rotating shaft 10 rotates counterclockwise. Fig. 5(a) shows a state in which the reference position B is located at position v, Fig. 5(b) shows a state in which the reference position B is located at position vi, Fig. 5(c) shows a state in which the reference position B is located at position vii, and Fig. 5(d) shows a state in which the reference position B is located at position viii.

[0056] Reference position B is a reference position in the rotation direction of the rotating shaft 10, and in this embodiment, the center of the N pole in the rotation direction of the rotating shaft 10 is set as the reference position.

[0057] First, a case where the rotating shaft 10 rotates clockwise will be described with reference to Fig. 4. In this case, when the reference position B is located at position i, position ii, position iii, or position iv, one of the power generating element 22 and the power generating element 24 generates power.

[0058] For example, when the rotation shaft 10 rotates clockwise and the reference position B is located at position i as shown in Fig. 4(a), the magnetic field generated by the magnet 20 reverses the direction of the magnetic field in the longitudinal direction of the power generating element 22, causing the power generating element 22 to generate power. On the other hand, when the reference position B is located at position i, the magnetic field generated by the magnet 20 does not reverse the direction of the magnetic field in the longitudinal direction of the power generating element 24, causing the power generating element 24 to not generate power.

[0059] When the power generating element 22 generates power, the magnetic sensor 26 operates based on the power from the power generating element 22. When the reference position B is located at position i, the magnetic sensor 26 faces the south pole. Therefore, when the reference position B is located at position i, the magnetic sensor 26 outputs a signal indicating that it faces the south pole.

[0060] 4(b), when the rotation shaft 10 further rotates clockwise and the reference position B is located at position ii, the magnetic field generated by the magnet 20 reverses the direction of the magnetic field in the longitudinal direction of the power generating element 24, causing the power generating element 24 to generate power. On the other hand, when the reference position B is located at position ii, the magnetic field generated by the magnet 20 does not reverse the direction of the magnetic field in the longitudinal direction of the power generating element 22, causing the power generating element 22 to not generate power.

[0061] When the power generating element 24 generates power, the magnetic sensor 28 operates based on the power from the power generating element 24. When the reference position B is located at position ii, the magnetic sensor 28 faces the south pole. Therefore, when the reference position B is located at position ii, the magnetic sensor 28 outputs a signal indicating that it faces the south pole.

[0062] 4(c), when the rotation shaft 10 further rotates clockwise and the reference position B is located at position iii, the magnetic field generated by the magnet 20 reverses the direction of the magnetic field in the longitudinal direction of the power generating element 22, causing the power generating element 22 to generate power. On the other hand, when the reference position B is located at position iii, the magnetic field generated by the magnet 20 does not reverse the direction of the magnetic field in the longitudinal direction of the power generating element 24, causing the power generating element 24 to not generate power.

[0063] When the power generating element 22 generates power, the magnetic sensor 26 operates based on the power from the power generating element 22. When the reference position B is located at position iii, the magnetic sensor 26 faces the N pole. Therefore, when the reference position B is located at position iii, the magnetic sensor 26 outputs a signal indicating that it faces the N pole.

[0064] 4(d), when the rotation shaft 10 further rotates counterclockwise and the reference position B is located at position iv, the magnetic field generated by the magnet 20 reverses the direction of the magnetic field in the longitudinal direction of the power generating element 24, causing the power generating element 24 to generate power. On the other hand, when the reference position B is located at position iv, the magnetic field generated by the magnet 20 does not reverse the direction of the magnetic field in the longitudinal direction of the power generating element 22, causing the power generating element 22 to not generate power.

[0065] When the power generating element 24 generates power, the magnetic sensor 28 operates based on the power from the power generating element 24. When the reference position B is at position iv, the magnetic sensor 28 faces the N pole. Therefore, when the reference position B is at position iv, the magnetic sensor 28 outputs a signal indicating that it faces the N pole.

[0066] Next, a case where the rotating shaft 10 rotates counterclockwise will be described with reference to Fig. 5. In this case, when the reference position B is located at position v, position vi, position vii, or position viii, one of the power generating element 22 and the power generating element 24 generates power.

[0067] For example, when the rotation shaft 10 rotates counterclockwise and the reference position B is located at position v as shown in Fig. 5(a), the magnetic field generated by the magnet 20 reverses the direction of the magnetic field in the longitudinal direction of the power generating element 24, causing the power generating element 24 to generate power. On the other hand, when the reference position B is located at position v, the magnetic field generated by the magnet 20 does not reverse the direction of the magnetic field in the longitudinal direction of the power generating element 22, causing the power generating element 22 to not generate power.

[0068] When the power generating element 24 generates power, the magnetic sensor 28 operates based on the power from the power generating element 24. When the reference position B is located at position v, the magnetic sensor 28 faces the N pole. Therefore, when the reference position B is located at position v, the magnetic sensor 28 outputs a signal indicating that it faces the N pole.

[0069] 5(b), when the rotation shaft 10 further rotates counterclockwise and the reference position B is located at position vi, the magnetic field generated by the magnet 20 reverses the direction of the magnetic field in the longitudinal direction of the power generating element 22, causing the power generating element 22 to generate power. On the other hand, when the reference position B is located at position vi, the magnetic field generated by the magnet 20 does not reverse the direction of the magnetic field in the longitudinal direction of the power generating element 24, causing the power generating element 24 to not generate power.

[0070] When the power generating element 22 generates power, the magnetic sensor 26 operates based on the power from the power generating element 22. When the reference position B is located at position vi, the magnetic sensor 26 faces the N pole. Therefore, when the reference position B is located at position vi, the magnetic sensor 26 outputs a signal indicating that it faces the N pole.

[0071] 5(c), when the rotation shaft 10 further rotates counterclockwise and the reference position B is located at position vii, the magnetic field generated by the magnet 20 reverses the direction of the magnetic field in the longitudinal direction of the power generating element 24, causing the power generating element 24 to generate power. On the other hand, when the reference position B is located at position vii, the magnetic field generated by the magnet 20 does not reverse the direction of the magnetic field in the longitudinal direction of the power generating element 22, causing the power generating element 22 to not generate power.

[0072] When the power generating element 24 generates power, the magnetic sensor 28 operates based on the power from the power generating element 24. When the reference position B is located at position vii, the magnetic sensor 28 faces the S pole. Therefore, when the reference position B is located at position vii, the magnetic sensor 28 outputs a signal indicating that it faces the S pole.

[0073] 5(d), when the rotation shaft 10 further rotates counterclockwise and the reference position B is located at position viii, the magnetic field generated by the magnet 20 reverses the direction of the magnetic field in the longitudinal direction of the power generating element 22, causing the power generating element 22 to generate power. On the other hand, when the reference position B is located at position viii, the magnetic field generated by the magnet 20 does not reverse the direction of the magnetic field in the longitudinal direction of the power generating element 24, causing the power generating element 24 to not generate power.

[0074] When the power generating element 22 generates power, the magnetic sensor 26 operates based on the power from the power generating element 22. When the reference position B is located at position viii, the magnetic sensor 26 faces the S pole. Therefore, when the reference position B is located at position viii, the magnetic sensor 26 outputs a signal indicating that it faces the S pole.

[0075] For example, the information processing unit 56 determines the rotational position of the rotating shaft 10 by determining in which of the multiple regions I to IV aligned in the rotation direction of the rotating shaft 10 the reference position B in the rotation direction of the rotating shaft 10 is located, based on power generation information indicating which of the multiple power generating elements 22, 24 has generated power and detection information indicating the detection result of the magnetic sensor corresponding to that power generating element out of the multiple magnetic sensors 26, 28. The storage unit 58 stores the region of the multiple regions I to IV in which the information processing unit 56 has determined that the reference position B is located.

[0076] For example, the power generation information is two-bit information that indicates 1 when power generation element 22 generates power and 0 when power generation element 24 generates power. Furthermore, for example, the detection information is two-bit information that indicates 1 when magnetic sensor 26 detects a south pole and when magnetic sensor 28 detects a south pole, and indicates 0 when magnetic sensor 26 detects a north pole and when magnetic sensor 28 detects a north pole.

[0077] Furthermore, for example, each of the multiple regions I to IV is a region sandwiched between two adjacent straight lines among multiple straight lines that extend radially around the rotation axis A and are arranged at equal intervals in the rotation direction of the rotating shaft 10. In this embodiment, the region including positions i and viii is referred to as region I, the region including positions ii and vii is referred to as region II, the region including positions iii and vi is referred to as region III, and the region including positions iv and v is referred to as region IV.

[0078] As described above, when reference position B is located at position i, power generating element 22 generates power and magnetic sensor 26 detects the south pole. When reference position B is located at position viii, power generating element 22 generates power and magnetic sensor 26 detects the south pole. That is, in these cases, (detection information, power generation information) = (1, 1). Therefore, when (detection information, power generation information) = (1, 1), information processing unit 56 determines that reference position B is located near position i or position viii and that reference position B is located in region I.

[0079] Furthermore, when reference position B is located at position ii, power generating element 24 generates power and magnetic sensor 28 detects the S pole. Furthermore, when reference position B is located at position vii, power generating element 24 generates power and magnetic sensor 28 detects the S pole. That is, in these cases, (detection information, power generation information) = (1, 0). Therefore, when (detection information, power generation information) = (1, 0), information processing unit 56 determines that reference position B is located near position ii or position vii and that reference position B is located in region II.

[0080] Furthermore, when reference position B is located at position iii, the power generating element 22 generates power and the magnetic sensor 26 detects the north pole. Furthermore, when reference position B is located at position vi, the power generating element 22 generates power and the magnetic sensor 26 detects the north pole. That is, in these cases, (detection information, power generation information) = (0, 1). Therefore, when (detection information, power generation information) = (0, 1), the information processing unit 56 determines that reference position B is located near position iii or position vi and that reference position B is located in region III.

[0081] Furthermore, when reference position B is located at position iv, power generating element 24 generates power and magnetic sensor 28 detects the north pole. When reference position B is located at position v, power generating element 24 generates power and magnetic sensor 28 detects the north pole. That is, in these cases, (detection information, power generation information) = (0, 0). Therefore, when (detection information, power generation information) = (0, 0), information processing unit 56 determines that reference position B is located near position iv or position v, and that reference position B is located in region IV.

[0082] Furthermore, if the area among the multiple areas I to IV where it is determined that the reference position B is located this time is not an area adjacent to the area where it was determined that the reference position B was located last time, the information processing unit 56 stores in the memory unit 58 that an error has occurred.

[0083] For example, the information processing unit 56 determines the rotational position of the rotating shaft 10 each time either the power generating element 22 or the power generating element 24 generates power, and stores the determined rotational position in the memory unit 58. If the area in which the reference position B is currently determined to be located is area I and the area in which the reference position B was previously determined to be located is area III, the information processing unit 56 stores in the memory unit 58 that an error has occurred.

[0084] Furthermore, if the area among the multiple areas I to IV where it is determined that the reference position B is currently located is not an area adjacent to the area where it was determined that the reference position B was previously located, the information processing unit 56 stores in the memory unit 58 that a transition has occurred from the area where it was determined that the reference position B was previously located to the area where it is determined that the reference position B is currently located.

[0085] For example, if the area in which the information processing unit 56 determines that the reference position B is located this time is area I and the area in which the information processing unit 56 determined that the reference position B was located last time is area III, the information processing unit 56 stores in the memory unit 58 that a transition from area III to area I has occurred.

[0086] Furthermore, the information processing unit 56 determines the rotation direction of the rotating shaft 10 based on the power generation information, the detection information, and the polarity information indicating the polarity determined by the polarity determining unit 47 .

[0087] For example, the polarity information is two-bit information that indicates 1 when the polarity of the power generated by the power generating element 22 is negative, and indicates 0 when the polarity of the power generated by the power generating element 22 is positive. In other words, for example, the polarity information is two-bit information that indicates 0 when the polarity of the power generated by the power generating element 24 is negative, and indicates 1 when the polarity of the power generated by the power generating element 24 is positive.

[0088] For example, the polarity of the power generated by the power generating element 22 when the reference position B is located at position i is reversed to the polarity of the power generated by the power generating element 22 when the reference position B is located at position viii. For example, if the polarity of the power generated by the power generating element 22 when the reference position B is located at position i is set to positive, and the polarity of the power generated by the power generating element 22 when the reference position B is located at position viii is set to negative, the information processing unit 56 can determine that the rotation shaft 10 is rotating clockwise when the polarity information is 0, and can determine that the rotation shaft 10 is rotating counterclockwise when the polarity information is 1.

[0089] Furthermore, when the area among the multiple areas I to IV in which it is determined that the current reference position B is located is adjacent to the area in which it was determined last time that the reference position B was located, and the transition from the polarity determined last time by the polarity determination unit 47 to the polarity determined this time by the polarity determination unit 47 is not normal, the information processing unit 56 stores in the memory unit 58 that an error has occurred.

[0090] Table 1 shows the relationship between the power generation positions of the multiple power generation elements 22, 24 of the rotation detector 14 in Fig. 1 and the rotation direction of the rotating shaft 10. As shown in Table 1, for example, the polarity information indicates 0 when the reference position B is located at position i, 0 when the reference position B is located at position ii, 1 when the reference position B is located at position iii, and 1 when the reference position B is located at position iv. Furthermore, for example, the polarity information indicates 0 when the reference position B is located at position v, 0 when the reference position B is located at position vi, 1 when the reference position B is located at position vii, and 1 when the reference position B is located at position viii.

[0091] [Table 1]

[0092] For example, when the information processing unit 56 determines that the region in which reference position B is currently located is region I and the region in which reference position B was previously located is region II, if the polarity information transitions from 1 to 1, it can be determined that the rotating shaft 10 has rotated counterclockwise and that reference position B has moved from region II to region I, and it can be determined that detection of the rotational position of the rotating shaft 10 is normal. On the other hand, when the information processing unit 56 determines that the region in which reference position B is currently located is region I and the region in which reference position B was previously located is region II, if the polarity information transitions from 0 to 0, it can be determined that the rotating shaft 10 has rotated clockwise and that reference position B has moved from region II to region I, and it cannot be determined that reference position B was located in region III or region IV, and it can be determined that detection of the rotational position of the rotating shaft 10 is abnormal. Therefore, when the area in which the current reference position B is determined to be located is area I and the area in which the previous reference position B was determined to be located is area II, if the polarity information has transitioned from 0 to 0, the information processing unit 56 determines that the transition from the polarity determined by the previous polarity determination unit 47 to the polarity determined by the current polarity determination unit 47 is not normal, and stores in the memory unit 58 that an error has occurred.

[0093] In addition, when the optical sensor 30 changes from an unpowered state in which it is not receiving power from the power source 150 to a powered state in which it is receiving power from the power source 150, the information processing unit 56 determines the rotational position of the rotating shaft 10 based on the rotational position of the rotating shaft 10 determined using the multiple magnetic sensors 26, 28 in the unpowered state and the amount of rotation of the rotating shaft 10 detected by the optical sensor 30 after it changes to the powered state.

[0094] For example, the information processing unit 56 determines the rotational position of the rotating shaft 10 by adding the amount of rotation of the rotating shaft 10 detected by the optical sensor 30 after the optical sensor 30 becomes powered to the rotational position of the rotating shaft 10 determined using the multiple magnetic sensors 26, 28 immediately before the optical sensor 30 becomes powered from an unpowered state.

[0095] In addition, the information processing unit 56 updates the count value for calculating the number of rotations of the rotating shaft 10 based on the area among the multiple areas I to IV in which it is determined that the current reference position B is located, the polarity determined by the current polarity determination unit 47, and the area among the multiple areas I to IV in which it is determined that the previous reference position B is located, and the polarity determined by the previous polarity determination unit 47.

[0096] Table 2 is a table for explaining an example of the update operation of the count value of the rotation detector 14 of FIG.

[0097] [Table 2]

[0098] As shown in Table 2, for example, if the previous polarity information indicates 1, the previous detection information indicates 0, the previous power generation information indicates 0, the current polarity information indicates 0, the current detection information indicates 1, and the current power generation information indicates 1, it is determined that the rotating shaft 10 has rotated clockwise and the reference position B has moved from region IV to region I, and the information processing unit 56 decrements the count value by 1.

[0099] Furthermore, for example, if the previous polarity information indicates 0, the previous detection information indicates 0, the previous power generation information indicates 0, the current polarity information indicates 0, the current detection information indicates 1, and the current power generation information indicates 1, it is determined that the rotating shaft 10 has rotated clockwise and the reference position B has moved from region IV to region I, and the information processing unit 56 decrements the count value by 1.

[0100] Furthermore, for example, if the previous polarity information indicates 1, the previous detection information indicates 1, the previous power generation information indicates 1, the current polarity information indicates 0, the current detection information indicates 0, and the current power generation information indicates 0, it is determined that the rotating shaft 10 has rotated counterclockwise and the reference position B has moved from region I to region IV, and the information processing unit 56 increments the count value by +1.

[0101] Furthermore, for example, if the previous polarity information indicates 0, the previous detection information indicates 1, the previous power generation information indicates 1, the current polarity information indicates 0, the current detection information indicates 0, and the current power generation information indicates 0, it is determined that the rotating shaft 10 has rotated counterclockwise and the reference position B has moved from region I to region IV, and the information processing unit 56 sets the count value to +1.

[0102] As described above, the information processing unit 56 updates the count value, thereby calculating the number of rotations of the rotating shaft 10.

[0103] The rotation detector 14 according to the first embodiment has been described above.

[0104] The rotation detector 14 according to this embodiment includes a magnet 20 that rotates together with the rotating shaft 10, a plurality of power generating elements 22, 24 that generate power due to changes in the magnetic field caused by the rotation of the magnet 20 together with the rotating shaft 10, and a plurality of magnetic sensors 26, 28 provided corresponding to the plurality of power generating elements 22, 24. The rotation detector 14 according to this embodiment further includes an information processing unit 56 that determines the rotational position of the rotating shaft 10 using the plurality of magnetic sensors 26, 28, and a generated power supply unit 46 that supplies power generated by each of the plurality of power generating elements 22, 24 only to the magnetic sensor of the plurality of magnetic sensors 26, 28 that corresponds to that power generating element.

[0105] This allows the power generated by the multiple power generating elements 22, 24 to be supplied only to the magnetic sensors 26, 28 corresponding to those power generating elements, thereby reducing consumption of the power generated by each of the multiple power generating elements 22, 24 and enabling the magnetic sensors corresponding to those power generating elements to be driven more reliably using that power. This reduces the occurrence of erroneous detection due to the magnetic sensors corresponding to those power generating elements not being driven.

[0106] Furthermore, in rotation detector 14 according to this embodiment, information processing unit 56 determines the rotational position of rotating shaft 10, and further includes storage unit 58 that stores the region determined by information processing unit 56 to be where reference position B is located among the plurality of regions I to IV. The determination of rotating shaft 10 is performed by determining in which region of the plurality of regions I to IV aligned in the rotation direction of rotating shaft 10 reference position B is located, based on power generation information indicating which of the plurality of power generating elements 22, 24 has generated power, and detection information indicating the detection result of the magnetic sensor corresponding to that power generating element among the plurality of magnetic sensors 26, 28.

[0107] This allows the rotational position of the rotating shaft 10 to be determined using the power generation information and the detection information without using the polarity of the power generated by each of the multiple power generating elements 22, 24. Therefore, even if the power generated by each of the multiple power generating elements 22, 24 is small and the polarity of the power cannot be determined, the rotational position of the rotating shaft 10 can be determined, and the occurrence of erroneous detection can be reduced.

[0108] Furthermore, in the rotation detector 14 according to this embodiment, if the area among the multiple areas I to IV in which it is determined that the reference position B is currently located is not an area adjacent to the area in which it was determined that the reference position B was located last time, the information processing unit 56 stores in the memory unit 58 that an error has occurred.

[0109] According to this, if an erroneous detection occurs because the area in which the reference position B is currently determined to be located is not an area adjacent to the area in which the reference position B was previously determined to be located, due to reasons such as the multiple magnetic sensors 26, 28 not being driven, the occurrence of the erroneous detection can be memorized, making it easy to recognize the occurrence of the erroneous detection.

[0110] Furthermore, in the rotation detector 14 according to this embodiment, if the area among the multiple areas I to IV in which it is determined that the current reference position B is located is not an area adjacent to the area in which it was determined that the previous reference position B was located, the information processing unit 56 stores in the memory unit 58 the fact that a transition has occurred from the area in which it was determined that the previous reference position B was located to the area in which it is determined that the current reference position B is located.

[0111] This makes it easy to recognize from which area to which area the reference position B transitioned that caused the erroneous detection, and therefore makes it easy to identify the cause of the erroneous detection.

[0112] Moreover, the rotation detector 14 according to this embodiment further includes a polarity determination unit 47 that determines the polarity of the power generated by each of the plurality of power generating elements 22, 24, and the information processing unit 56 determines the rotation direction of the rotating shaft 10 based on the power generation information, the detection information, and the polarity information indicating the polarity determined by the polarity determination unit 47.

[0113] According to this, by determining the rotation direction of the rotating shaft 10 in addition to the rotation position of the rotating shaft 10, it is possible to easily recognize the occurrence of an erroneous detection.

[0114] Furthermore, in the rotation detector 14 according to this embodiment, when the area among the plurality of areas I to IV in which it has been determined that the current reference position B is located is adjacent to the area in which it has been determined that the previous reference position B is located, and the transition from the polarity determined by the previous polarity determination unit 47 to the polarity determined by the current polarity determination unit 47 is not normal, the information processing unit 56 stores in the memory unit 58 that an error has occurred.

[0115] According to this, if an erroneous detection occurs due to the multiple magnetic sensors 26, 28 not being driven, for example, error information indicating that an erroneous detection has occurred can be stored, making it easy to recognize that an erroneous detection has occurred.

[0116] Furthermore, in the rotation detector 14 according to this embodiment, the information processing unit 56 updates the count value for calculating the number of rotations of the rotating shaft 10 based on the area among the plurality of areas I to IV in which it is determined that the current reference position B is located, the polarity determined by the current polarity determination unit 47, and the area among the plurality of areas I to IV in which it is determined that the previous reference position B is located, and the polarity determined by the previous polarity determination unit 47.

[0117] This allows the count value for calculating the number of rotations of the rotating shaft 10 to be updated more accurately, thereby reducing the occurrence of erroneous detection.

[0118] Furthermore, rotation detector 14 according to this embodiment further includes optical sensor 30, which has light receiving and emitting elements 42 that operate based on power from power supply 150 and detects the amount of rotation of rotating shaft 10. When optical sensor 30 changes from an unpowered state in which it is not receiving power from power supply 150 to a powered state in which it is receiving power from power supply 150, information processing unit 56 determines the rotational position of rotating shaft 10 based on the rotational position of rotating shaft 10 determined using multiple magnetic sensors 26, 28 in the unpowered state and the amount of rotation of rotating shaft 10 detected by optical sensor 30 after it entered the powered state.

[0119] According to this, when the state is unpowered, the rotational position of the rotating shaft 10 can be determined using the multiple magnetic sensors 26, 28. Furthermore, when the state is switched from unpowered to powered, the rotational position of the rotating shaft 10 can be determined by adding the amount of rotation of the rotating shaft 10 detected by the optical sensor 30 after the state is switched to powered to the rotational position of the rotating shaft 10 determined using the multiple magnetic sensors 26, 28 when the state is unpowered, thereby further reducing the occurrence of erroneous detection.

[0120] Furthermore, in the rotation detector 14 according to this embodiment, the generated power supply unit 46 has a sensor power storage unit 66, a power storage unit 67, and a switch 72. The sensor power storage unit 66 stores the power generated by each of the plurality of power generating elements 22, 24 and supplied to the magnetic sensor of the plurality of magnetic sensors 26, 28 corresponding to that power generating element. The power storage unit 67 stores the power generated by each of the plurality of power generating elements 22, 24 and supplied to devices other than the plurality of magnetic sensors 26, 28. The switch 72 allows the sensor power storage unit 66 and the power storage unit 67 to be electrically disconnected.

[0121] This allows the power generated by each of the multiple power generating elements 22, 24 to be reliably supplied to the corresponding one of the multiple magnetic sensors 26, 28, thereby further reducing the occurrence of erroneous detection due to the magnetic sensor not being driven.

[0122] Furthermore, in the rotation detector 14 according to this embodiment, the multiple power generating elements 22, 24 are arranged at angular intervals in the rotation direction of the rotating shaft 10 that are equal to or greater than the angular interval between a first position where one of the multiple power generating elements 22, 24 generates power when the rotating shaft 10 rotates clockwise, and a second position that is closest to the first position among the one or more positions where the one power generating element generates power when the rotating shaft 10 rotates counterclockwise. Each of the multiple magnetic sensors 26, 28 is arranged at the same position as a corresponding one of the multiple power generating elements 22, 24 in the rotation direction of the rotating shaft 10.

[0123] This makes it easy to differentiate between the magnetic pole detected by the magnetic sensor 26 when the power generating element 22 generates power at one position and the magnetic pole detected by the magnetic sensor 26 when the power generating element 22 generates power at another position, thereby making it easy to determine the rotational position of the rotating shaft 10 and reducing the occurrence of erroneous detection.

[0124] (Second embodiment) FIG. 6 is a diagram showing a rotation detector 14a according to the second embodiment.

[0125] As shown in FIG. 6, the rotation detector 14a differs from the rotation detector 14 mainly in that the rotation detector 14a further includes a power generating element 104 and a magnetic sensor 106.

[0126] The power generating element 104 has the same configuration as the power generating element 22 and the power generating element 24, and therefore a detailed description of the power generating element 104 will be omitted. The multiple power generating elements 22, 24, and 104 are arranged at equal intervals in the rotation direction of the rotating shaft 10.

[0127] The magnetic sensor 106 has the same configuration as the magnetic sensors 26 and 28, and therefore a detailed description of the magnetic sensor 106 will be omitted. The magnetic sensor 106 is disposed at the same position as the power generating element 104 in the rotation direction of the rotating shaft 10, and is disposed alongside and further outward than the power generating element 104 in the radial direction of the rotating shaft 10.

[0128] In this way, by further providing a power generating element 104 and a magnetic sensor 106 corresponding to the power generating element 104, it is possible to cause any of the multiple power generating elements 22, 24, 104 to generate power at positions i to vi when the rotating shaft 10 rotates clockwise, and to cause any of the multiple power generating elements 22, 24, 104 to generate power at positions vii to xii when the rotating shaft 10 rotates counterclockwise. This makes it possible to determine which of the six regions, I to VI, the reference position B is located in, and to detect the position of the rotating shaft 10 more precisely than the rotation detector 14.

[0129] Fig. 7 is a block diagram showing a part of the functional configuration of the rotation detector 14a of Fig. 6. Fig. 8 is a block diagram showing another part of the functional configuration of the rotation detector 14a of Fig. 6.

[0130] As shown in Figures 7 and 8, rotation detector 14a differs from rotation detector 14 mainly in that it includes a generated power supply unit 46a that is different from generated power supply unit 46, a polarity determination unit 47a that is different from polarity determination unit 47, and a magnetic pole determination unit 51a that is different from magnetic pole determination unit 51.

[0131] The generated power supply unit 46a differs from the generated power supply unit 46 mainly in that it has a full-wave rectifier unit 112, a third storage unit 114, a switch 116, a power supply monitoring unit 118, a discharge unit 120, and a switch 122.

[0132] The generated power supply unit 46a can supply the power generated by the power generating element 104 only to the magnetic sensor 106 corresponding to the power generating element 104 among the plurality of magnetic sensors 26, 28, and 106.

[0133] The polarity determination unit 47a differs from the polarity determination unit 47 mainly in that it further includes a third determination unit 108 that determines the polarity of the power generated by the power generating element 104. The third determination unit 108 can determine the polarity of the power generated by the power generating element 104.

[0134] The magnetic pole determination unit 51a differs from the magnetic pole determination unit 51 mainly in that it further includes a third determination unit 110 that determines the magnetic pole detected by the magnetic sensor 106. The third determination unit 110 enables the magnetic pole detected by the magnetic sensor 106 to be determined.

[0135] (Other embodiments, etc.) As described above, the embodiments have been described as examples of the technology disclosed in this application. However, the technology according to the present disclosure is not limited to these, and can be applied to embodiments or modified examples in which changes, substitutions, additions, omissions, etc. are made as appropriate without departing from the spirit of the present disclosure.

[0136] In the above-described embodiment, the magnet 20 is described as being annular, but this is not limiting. For example, the magnet does not have to be annular, and may be disk-shaped, rod-shaped, or the like.

[0137] In the above-described embodiment, the optical sensor 30 has the reflective pattern 44, but the present invention is not limited to this. For example, the optical sensor may have a transmissive pattern that transmits light, and detect the rotational position of the rotation shaft by receiving light that has passed through the transmissive pattern.

[0138] In the above-described embodiment, the case has been described in which each of the multiple magnetic sensors 26, 28 is disposed at the same position as the corresponding one of the multiple power generating elements 22, 24 in the rotation direction of the rotating shaft 10. However, this is not limiting. For example, each of the multiple magnetic sensors may be disposed at a position shifted by 180 degrees from the corresponding one of the multiple power generating elements in the rotation direction of the rotating shaft.

[0139] In the above-described embodiment, the magnetic sensors 26, 28 are aligned with the power generating elements 22, 24 in the radial direction centered on the rotation axis A and are disposed outward of the power generating elements 22, 24. However, the magnetic sensors 26, 28 do not necessarily need to be disposed outside the power generating elements 22, 24; they may be disposed inside the power generating elements 22, 24. Here, the magnetic sensors 26, 28 are required to accurately read the magnetic pole of the magnet 20. Therefore, the magnetic sensors 26, 28 are preferably disposed in positions with a high S / N ratio to detect the magnetic flux of the magnet 20. Therefore, when the magnetic sensors 26, 28 are viewed along the rotation axis A, the magnetic sensors 26, 28 are disposed in positions that do not overlap with the power generating elements 22, 24. This has the advantage that the magnetic sensors 26, 28 are less susceptible to changes in magnetic flux due to power generation by the power generating elements 22, 24. When the magnetic sensors 26, 28 are disposed outside the power generating elements 22, 24, the magnetic sensors 26, 28 can be disposed even on a substrate with a hole in the center, so the center of the rotation detector 14 can be easily made hollow.

[0140] In the above-described embodiment, the case where the multiple power generating elements 22, 24 are arranged on the main surface of the substrate 18 opposite to the rotating plate 16 has been described, but the present invention is not limited to this. For example, the multiple power generating elements may be arranged on the main surface of the substrate facing the rotating plate.

[0141] In the above-described embodiment, the multiple magnetic sensors 26, 28 are arranged on the main surface of the substrate 18 facing the rotating plate 16, but this is not limiting. For example, the multiple magnetic sensors may be arranged on the main surface of the substrate opposite the rotating plate.

[0142] In the above-described embodiment, the magnet 20 is disposed on the main surface of the rotating plate 16 opposite the substrate 18, but the present invention is not limited to this. For example, the magnet may be disposed on the main surface of the rotating plate facing the substrate. [Industrial Applicability]

[0143] The rotation detector according to the present disclosure can be used to detect the rotation of the rotating shaft of a motor that rotates a load. [Explanation of symbols]

[0144] 14,14a Rotation detector 16 Rotating Plate 18 PCB 20 Magnet 22, 24, 104 Power generating element 26,28,106 Magnetic Sensors 30 Optical Sensor 32 Control circuit 34,38 Magnetically sensitive part 36,40 coil 42 Light-emitting / receiving element 44 Reflective Pattern 46, 46a Power Generation and Supply Section 47,47a Polarity judgment section 48,52 1st judgment section 50,54 Second judgment part 51,51a Magnetic pole determination section 55 Signal Processing Unit 56 Information Processing Department 58 Memory section 60 Communications Department 62,64,112 Full wave rectifier 66 Sensor power storage unit 67 Power Storage Unit 68 First Storage Unit 70 Second Storage Unit 72,74,76,100,102,116,122 switches 78,80 Internal power supply 82,84,86,88,89,118 Power supply monitoring section 90,92 Voltage adjustment unit 94,96,98,120 Discharge part 108,110 Third judgment section 114 Third Storage Unit

Claims

1. a magnet that rotates together with the rotating shaft; a plurality of power generating elements that generate power by a change in a magnetic field caused by the magnet rotating together with the rotation shaft; a plurality of magnetic sensors provided corresponding to the plurality of power generating elements; an information processing unit that determines a rotational position of the rotary shaft using the plurality of magnetic sensors; a generated power supply unit that supplies the power generated by each of the plurality of power generating elements to only the magnetic sensor corresponding to that power generating element among the plurality of magnetic sensors, Rotation detector.

2. the information processing unit determines in which of a plurality of regions aligned in the rotation direction of the rotation shaft a reference position in the rotation direction of the rotation shaft is located, based on power generation information indicating a power generation element among the plurality of power generation elements that has generated power and detection information indicating a detection result of a magnetic sensor among the plurality of magnetic sensors that corresponds to the power generation element, thereby determining the rotation position of the rotation shaft; a storage unit configured to store an area among the plurality of areas that is determined by the information processing unit to be where the reference position is located, The rotation detector according to claim 1 .

3. the information processing unit stores in the storage unit a fact that an error has occurred when the area in which it has been determined that the reference position is currently located among the plurality of areas is not an area adjacent to the area in which it has been determined that the reference position was located previously. The rotation detector according to claim 2 .

4. when the area in which it is currently determined that the reference position is located among the plurality of areas is not an area adjacent to the area in which it was previously determined that the reference position was located, the information processing unit stores in the storage unit information that a transition has occurred from the area in which it was previously determined that the reference position was located to the area in which it is currently determined that the reference position is located.

4. The rotation detector according to claim 2 or 3.

5. a polarity determination unit that determines the polarity of the power generated by each of the plurality of power generating elements; the information processing unit determines the rotation direction of the rotating shaft based on the power generation information, the detection information, and polarity information indicating the polarity determined by the polarity determination unit. The rotation detector according to any one of claims 2 and 3.

6. the information processing unit, when the area in which it is currently determined that the reference position is located among the plurality of areas is adjacent to the area in which it was previously determined that the reference position was located, and when a transition from the polarity previously determined by the polarity determination unit to the polarity currently determined by the polarity determination unit is not normal, causes the storage unit to store information indicating that an error has occurred.

6. The rotation detector according to claim 5.

7. the information processing unit updates a count value for calculating the number of rotations of the rotating shaft based on the region among the plurality of regions in which it is determined that the reference position is currently located, the polarity determined by the polarity determination unit this time, the region among the plurality of regions in which it was previously determined that the reference position was located last time, and the polarity determined by the polarity determination unit last time.

6. The rotation detector according to claim 5.

8. an optical sensor having a light emitting element and a light receiving element that operate based on power from a power source, and that detects the amount of rotation of the rotary shaft; When the optical sensor changes from an unpowered state in which it is not receiving power from the power source to a powered state in which it is receiving power from the power source, the information processing unit determines the rotational position of the rotating shaft based on the rotational position of the rotating shaft determined using the plurality of magnetic sensors in the unpowered state and the amount of rotation of the rotating shaft detected by the optical sensor after the optical sensor changes to the powered state. The rotation detector according to any one of claims 1 to 3.

9. the generated power supply unit includes a sensor power storage unit that stores power generated from each of the plurality of power generating elements and supplied to a magnetic sensor among the plurality of magnetic sensors corresponding to that power generating element; a power storage unit that stores power generated from each of the plurality of power generating elements and supplied to devices other than the plurality of magnetic sensors; and a disconnection unit that can electrically disconnect the sensor power storage unit from the power storage unit. The rotation detector according to any one of claims 1 to 3.

10. the plurality of power generating elements are arranged at angular intervals in the rotation direction of the rotation shaft that are equal to or greater than an angular interval between a first position at which one power generating element of the plurality of power generating elements generates power when the rotation shaft rotates clockwise, and a second position, which is closest to the first position among one or more positions at which the one power generating element generates power when the rotation shaft rotates counterclockwise, each of the plurality of magnetic sensors is disposed at the same position as a corresponding one of the plurality of power generating elements in the rotation direction of the rotation shaft, or at a position shifted by 180 degrees from the corresponding power generating element; The rotation detector according to any one of claims 1 to 3.

11. A rotation detection method using a rotation detector, comprising: the rotation detector includes a magnet that rotates together with a rotation shaft, a plurality of power generating elements that generate power by a change in a magnetic field caused by the rotation of the magnet together with the rotation shaft, a plurality of magnetic sensors provided corresponding to the plurality of power generating elements, and a generated power supply unit that supplies the power generated by each of the plurality of power generating elements only to the magnetic sensor among the plurality of magnetic sensors that corresponds to the power generating element; determining in which of a plurality of regions aligned in the rotation direction of the rotation shaft a reference position in the rotation direction of the rotation shaft is located, based on power generation information indicating a power generation element among the plurality of power generation elements that has generated power and detection information indicating a detection result of a magnetic sensor among the plurality of magnetic sensors that corresponds to the power generation element; storing the area among the plurality of areas in which it is determined that the reference position is located; Rotation detection method.

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