Magnetic encoder

Abstract

The present invention realizes battery-free and hollow shaft response of a high-resolution magnetic encoder for detecting an absolute angular position in multi-turn rotation. A magnetic encoder is provided with a magnetic power generation element (W) that generates a pulsed current on the basis of changes in the magnetic field of a first magnet magnetized with a pair of N-poles and S-poles, calculates multi-turn rotation information without being supplied with power from the outside, and stores the multi-turn rotation information in a first non-volatile memory (22). The second sensor unit (40) calculates the one-turn rotation angle, which is the angular position within the range of one-turn rotation of the rotating body (2), on the basis of the output of a magnetosensitive element (MR) facing a second magnet in which a plurality of pairs of N-poles and S-poles are alternately magnetized in the circumferential direction, and the output of magnetic detection elements (H1, H2, H3) facing a third magnet in which a pair of N-poles and S-poles are magnetized. At the time of startup, the multi-turn rotation information is read from the first non-volatile memory, and the absolute angular position of the multi-turn rotation is calculated by combining the multi-turn rotation information with the one-turn rotation angle calculated at the time of startup.

Description

Technical Field

[0001] The present invention relates to a magnetic encoder for detecting rotation. Background Art

[0002] An encoder that detects the absolute angular position during multiple rotations, including not only the angular position but also the number of rotations, is installed in various devices such as motors. In the rotary encoder described in Patent Document 1, a first magnet with two poles, one of which is magnetized to the N pole and the other to the S pole, is arranged on the rotation axis of the rotating body, and a second magnet with multiple poles, in which the N poles and the S poles are alternately magnetized in the circumferential direction, is arranged to surround the first magnet. The absolute angular position during multiple rotations is detected based on the outputs of the magnetoresistive element and two Hall elements (first magnetic sensing unit) facing the first magnet with two poles and the output of the magnetoresistive element (second magnetic sensing unit) facing the second magnet with multiple poles. Prior art literature Patent Literature

[0003] Patent Document 1: Japanese Patent No. 6877168 Patent Document 2: Japanese Patent No. 6323558 Summary of the invention

[0004] Problems to be solved by the invention An encoder that detects the absolute angular position during multiple rotations needs to count the number of rotations. However, in order to accurately count the cumulative number of rotations (multi-rotation information), it is necessary to always maintain a state in which the rotation can be detected when the rotating body is moving and to reliably continue counting. In the past, a structure was adopted that ensured power supply by connecting a battery so as to always maintain a state in which the rotation could be detected, but the battery had to be replaced regularly, which was a heavy maintenance burden.

[0005] On the other hand, when an encoder is mounted on a rotating shaft of a motor, the rotating shaft is sometimes made hollow in order to reduce the size or wiring space. Therefore, an encoder having a structure suitable for a hollow shaft is required. In the past, in magnetic encoders, a first magnet is generally arranged on the rotating axis as in Patent Document 1, but in such an arrangement, the end of the hollow shaft is blocked, and the hollow portion cannot be used as a wiring space.

[0006] Here, Patent Document 2 describes an encoder device that uses a magnetic encoder unit and an optical encoder unit. The magnetic encoder unit has a power generation unit that generates current through changes in a magnetic field, such as a Wiegand wire, and detects the number of rotations based on the pulses of the generated current. The optical encoder unit has a high resolution. In this structure, the number of rotations can be continuously detected even without power supply from a battery. In addition, neither the magnetic encoder unit nor the optical encoder unit of Patent Document 2 has a magnet or scale configured on the axis of rotation, and can cope with a hollow shaft.

[0007] However, the encoder device of Patent Document 2 uses an optical encoder part in order to detect the absolute angle position with high resolution, and uses both magnetic and optical encoders. If the optical encoder is used together, a clean environment is required during assembly, which is costly and difficult to achieve miniaturization and structural simplification. In addition, the optical encoder has the problem of low durability and poor durability.

[0008] In view of the above problems, the present invention provides a magnetic encoder that detects the absolute angular position in multiple rotations, can eliminate the burden of battery replacement, is suitable for a hollow shaft structure, and is small, low-cost, durable, and has high resolution. Technical solutions to solve problems

[0009] In order to solve the above-mentioned problems, the first mode of the present invention is a magnetic encoder that detects the absolute angular position of a rotating body relative to a fixed body, and comprises: a first sensor unit that detects the rotation of the rotating body; a second sensor unit that detects the angular position within the range of one rotation of the rotating body, that is, the angle of one rotation; an annular first magnet that has a first track magnetized with a pair of N poles and S poles; an annular second magnet that has a second track magnetized with multiple pairs of N poles and S poles alternately in the circumferential direction and is coaxially arranged with the first magnet; and an annular third magnet that has a pair of N poles and S poles and is coaxially arranged with the first magnet and the second magnet, wherein the first sensor unit comprises: a magnetoelectric element that is coaxially arranged with the The first magnet is opposite; a multi-turn rotation information generating unit, which performs calculations based on the detection signal of the current generated by the magnetic generating element; and a non-volatile memory, which stores multi-turn rotation information corresponding to the accumulated number of rotations of the rotating body, and updates the multi-turn rotation information based on the output of the multi-turn rotation information generating unit. The second sensor unit includes: a magnetic sensitive element, which is opposite to the second magnet; at least three magnetic detection elements, which are opposite to the third magnet and arranged in the circumferential direction; a position calculation unit, which calculates the one-turn rotation angle based on the outputs of the magnetic sensitive element and the magnetic detection element; and an absolute angular position calculation unit, which calculates the absolute angular position based on the multi-turn rotation information and the one-turn rotation angle.

[0010] In order to solve the above-mentioned problems, a second embodiment of the present invention is a magnetic encoder that detects the absolute angular position of a rotating body relative to a fixed body, and comprises: a first sensor unit that detects the rotation of the rotating body; a second sensor unit that detects the angular position within the range of one rotation of the rotating body, that is, the angle of one rotation; an annular first magnet that has a first track magnetized with a pair of N poles and S poles; and an annular second magnet that has a second track magnetized with multiple pairs of N poles and S poles alternately in the circumferential direction and is coaxially arranged with the first magnet, wherein the first sensor unit comprises: a magnetoelectric element that is opposite to the first magnet; and a multi-turn rotation information generating unit that generates information based on the first magnet. The detection signal of the current generated by the magnetic generating element is calculated; and a non-volatile memory, which stores multi-turn rotation information corresponding to the accumulated number of rotations of the rotating body, and updates the multi-turn rotation information according to the output of the multi-turn rotation information generating unit, the second sensor unit comprises: a magnetic sensitive element, which is opposite to the second magnet; at least three magnetic detection elements, which are opposite to the first magnet and arranged in the circumferential direction; a position calculation unit, which calculates the one-turn rotation angle according to the output of the magnetic sensitive element and the magnetic detection element; and an absolute angular position calculation unit, which calculates the absolute angular position according to the multi-turn rotation information and the one-turn rotation angle.

[0011] In order to solve the above-mentioned problems, a third embodiment of the present invention is a magnetic encoder, which detects the absolute angular position of a rotating body relative to a fixed body, and comprises: a first sensor unit, which detects the rotation of the rotating body; a second sensor unit, which detects the angular position within the range of one rotation of the rotating body, that is, the angle of one rotation; an annular first magnet, which has a first track magnetized with a pair of N poles and S poles; an annular second magnet, which has a second track magnetized with multiple pairs of N poles and S poles alternately in the circumferential direction and is coaxially arranged with the first magnet; and an annular fourth magnet, which has multiple pairs of N poles and S poles alternately magnetized in the circumferential direction and is coaxially arranged with the first magnet and the second magnet, wherein the first sensor unit comprises: a magnetic generating element, which is opposite to the first magnet; a multi-turn rotation information generating unit, which performs calculations based on the detection signal of the current generated by the magnetic generating element; and a nonvolatile A memory, which stores multi-turn rotation information corresponding to the accumulated number of rotations of the rotating body, and updates the multi-turn rotation information according to the output of the multi-turn rotation information generating unit, wherein the second sensor unit comprises: a magnetic sensitive element, which is opposite to the second magnet; a first magnetic detection element group, which is composed of three or more magnetic detection elements including a first, a second, and a third magnetic detection element opposite to the first magnet and arranged in a circumferential direction; a second magnetic detection element group, which is composed of three or more magnetic detection elements including a fourth, a fifth, and a sixth magnetic detection element opposite to the fourth magnet and arranged in a circumferential direction; a position calculation unit, which calculates the one-turn rotation angle according to the outputs of the magnetic sensitive element, the first magnetic detection element group, and the second magnetic detection element group; and an absolute angular position calculation unit, which calculates the absolute angular position according to the multi-turn rotation information and the one-turn rotation angle.

[0012] According to each embodiment of the present invention, the first sensor unit calculates the multi-turn rotation information corresponding to the cumulative number of rotations of the rotating body based on the detection signal of the current generated by the magnetoelectric element, and stores it in the non-volatile memory. Therefore, even if there is no power supply from the battery or the outside, the multi-turn rotation information can be continuously updated, and when the encoder is started, the correct multi-turn rotation information can be read from the non-volatile memory to calculate the absolute angle position. Therefore, even without the burden of replacing the battery, the correct cumulative number of rotations can be obtained, and the correct absolute angle position of the multi-turn rotation can be output.

[0013] In addition, according to each mode of the present invention, the multi-turn rotation information is detected using a magnetic generating element, the one-turn rotation angle is detected using a magnetic sensitive element and a magnetic detection element, and the absolute angle position of the multi-turn rotation is calculated based on the one-turn rotation angle and the multi-turn rotation information (accumulated number of rotations). Therefore, since the absolute angle position of the multi-turn rotation can be detected only by a magnetic mechanism, the structure can be simplified, and miniaturization and cost reduction can be achieved compared with the case of using an optical encoder. In addition, it also has the advantages of being less prone to adverse conditions caused by contamination and high durability. In addition, the second sensor unit has a high-resolution detection mechanism based on a multi-pole first magnet and a magnetic sensitive element, and a low-resolution detection mechanism using more than three magnetic detection elements arranged in the circumferential direction, so that the angle values ​​obtained based on the output from each detection mechanism can be compared for correction. Therefore, a magnetic and high-resolution encoder can be realized. In addition, since no magnet or element is configured on the rotation axis, it can be set in a manner that does not block the end of the hollow shaft, which is suitable for a hollow shaft.

[0014] In the first embodiment of the present invention, it is preferred to have a magnet holder, which has an annular magnet holding portion centered on the rotation axis of the rotating body, the second magnet is arranged on the outer peripheral portion of one surface of the magnet holding portion, the third magnet is arranged on the inner peripheral portion of the one surface, the first magnet is arranged on the other surface of the magnet holding portion, the magnetic sensitive element and the magnetic detection element are arranged on a first substrate opposite to the one surface, and the magnetic power generation element is arranged on a second substrate opposite to the other surface.

[0015] In the second embodiment of the present invention, it is preferred to have a magnet holder having an annular magnet holder centered on the rotation axis of the rotating body, the second magnet being arranged on one surface of the magnet holder, the first magnet being arranged on the other surface of the magnet holder, the magnetic sensitive element being arranged on a first substrate opposite to the one surface, and the magnetic generating element and the magnetic detecting element being arranged on a second substrate opposite to the other surface.

[0016] In the third embodiment of the present invention, it is preferred to have a magnet holder having an annular magnet holder portion centered on the rotation axis of the rotating body, the second magnet being arranged on the outer peripheral portion of one surface of the magnet holder portion, the fourth magnet being arranged on the inner peripheral portion of the one surface, the first magnet being arranged on the other surface of the magnet holder portion, the magnetic sensitive element and the second magnetic detection element group being arranged on a first substrate opposite to the one surface, and the magnetic power generation element and the first magnetic detection element group being arranged on a second substrate opposite to the other surface.

[0017] In this way, each method of the present invention configures magnets on the front and back of the magnet holding part, and the magneto-electric element and the magnetic sensitive element are opposite to the magnet holding part from opposite sides in the axial direction. Therefore, all detection mechanisms can be made into simple and compact structures. In addition, since no magnets or elements are arranged on the rotation axis, it can be set in a manner that does not block the end of the hollow shaft.

[0018] In each embodiment of the present invention, it is preferred that the absolute angle position calculation unit calculates the absolute angle position based on the multi-turn rotation information, i.e., the first multi-turn rotation information, read from the nonvolatile memory and the newly detected one-turn rotation angle at startup, and then, during the period until power is cut off, the second multi-turn rotation information corresponding to the accumulated number of rotations is calculated using the cumulative value of the change in the one-turn rotation angle, and the absolute angle position is calculated based on the second multi-turn rotation information and the one-turn rotation angle. In this way, even if the rotating body moves during the period when no power is supplied, the number of rotations will not be unclear, and the correct absolute angle position can be obtained at startup. In addition, during the period when power is supplied to the second sensor unit, the absolute angle position of the multi-turn rotation can be obtained based on the output of the second sensor unit.

[0019] In each embodiment of the present invention, the magneto-sensitive element is preferably a magneto-resistance effect element having a magneto-resistance pattern of phase A and a magneto-resistance pattern of phase B having a phase difference of 90°, the second track is arranged in two rows in the radial direction, the positions of the S pole and the N pole of the adjacent second track are offset by one pole in the circumferential direction, and the magneto-sensitive element is opposite to the boundary of the adjacent second track. In this way, since the magneto-resistance effect element is arranged in the rotating magnetic field that changes in the in-plane direction of each track, the detection accuracy can be improved. Effects of the Invention

[0020] According to the present invention, the absolute angle position of multiple turns of rotation can be output accurately without the burden of replacing batteries. In addition, it can be set in a manner that does not block the end of the hollow shaft, which is suitable for the hollow shaft. In addition, it is possible to realize an encoder that is entirely magnetic and has a high resolution, which can achieve miniaturization and cost reduction, and is not prone to adverse conditions caused by contamination, and has high durability. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a configuration diagram and a functional block diagram of the main part of the magnetic encoder according to the first embodiment. Figure 2 This is a configuration diagram and a functional block diagram of the main parts of the magnetic encoder according to the second embodiment. Figure 3 This is a configuration diagram and a functional block diagram of the main parts of the magnetic encoder according to the third embodiment. Figure 4It is a cross-sectional view showing a specific example of the magnetic encoder according to the first embodiment. Figure 5 This is a timing chart showing the flow of processing in the first sensor unit and the second sensor unit during startup, normal operation, and backup. DETAILED DESCRIPTION

[0022] Embodiments of the magnetic encoder of the present invention are described below. The magnetic encoder of the present invention is a multi-turn absolute angular position encoder capable of knowing the number of rotations from a predetermined origin position and the current angular position.

[0023] In this specification, regarding the structure of the magnetic encoder of the present invention, the specific structure of the magnet and magnet holder as its main parts, various elements for detecting magnetic field changes and the substrate on which they are configured are described, but the description of other parts (external casing, etc.) is omitted.

[0024] Figure 1 , Figure 2 , Figure 3 They are respectively a structural diagram (disposition diagram of magnets and elements) and a functional block diagram of the main parts of the magnetic encoder of the present invention. Figure 1 It is a configuration diagram and a functional block diagram of the main part of the magnetic encoder 1A according to the first embodiment. Figure 2 It is a configuration diagram and a functional block diagram of the main part of the magnetic encoder 1B according to the second embodiment. Figure 3 It is a configuration diagram and a functional block diagram of the main part of a magnetic encoder 1C according to the third embodiment. Figure 4 It is a cross-sectional view showing a main part of a specific example of the magnetic encoder 1A according to the first embodiment.

[0025] (Implementation Method 1) The magnetic encoder 1A of the first embodiment uses a rotating body 2 such as a rotating shaft of a motor as a measurement object. Figure 1 As shown, the magnetic encoder 1A includes a magnet holder 3 fixed to the rotating body 2, and a first magnet 11, a second magnet 12, and a third magnet 13 fixed to the magnet holder 3. The first magnet 11, the second magnet 12, and the third magnet 13 are all annular permanent magnets, and are coaxially arranged around the rotation axis L of the rotating body 2. The magnet holder 3 includes a cylindrical shaft portion 31 and an annular magnet holder 32 extending from the shaft portion 31 toward the outer peripheral side. The shaft portion 31 extends in the axial direction of the rotation axis L. The magnet holder 32 is arranged at an end portion of one side L1 of the shaft portion 31 in the axial direction (refer to Figure 4 ). The shaft portion 31 is fixed to the rotating shaft (rotating body 2) of the motor by, for example, a set screw.

[0026] Of the first magnet 11, the second magnet 12, and the third magnet 13, the second magnet 12 and the third magnet 13 are disposed on one surface 33 of the magnet holding portion 32, and the first magnet 11 is disposed on the other surface 34 of the magnet holding portion 32. The one surface 33 is a surface facing one side L1 in the axial direction, and the other surface 34 is a surface facing the other side L2 in the axial direction (see Figure 4 ).like Figure 1 , Figure 4 As shown, on one surface 33 , the second magnet 12 is arranged on the outer peripheral portion of the magnet holding portion 32 , and the third magnet 13 is arranged on the inner peripheral portion of the magnet holding portion 32 .

[0027] like Figure 1 , Figure 4 As shown, the first magnet 11 is arranged on the outer periphery of the other surface 34 of the magnet holding portion 32. The first magnet 11 has an annular first track T1 in which the N pole and the S pole are magnetized one pole each in the circumferential direction, and the center thereof coincides with the rotation axis L. The first track T1 is arranged in two rows in the radial direction. The positions of the N pole and the S pole of the first track T1 adjacent in the radial direction are offset by one pole in the circumferential direction.

[0028] The second magnet 12 is arranged on the outer periphery of one surface 33 of the magnet holding portion 32. The second magnet 12 has a second annular track T2 in which a plurality of pairs of N poles and S poles are alternately magnetized in the circumferential direction, and the center thereof coincides with the rotation axis L. The second track T2 is arranged in two rows in the radial direction. The positions of the N poles and S poles of the second tracks T2 adjacent in the radial direction are offset by one pole in the circumferential direction. For example, the second magnet 12 has 128 pairs of N poles and S poles alternately magnetized in the circumferential direction. In addition, the number of N poles and S poles may be a number different from 128 pairs.

[0029] The third magnet 13 is disposed on the inner circumference of one surface 33 of the magnet holding portion 32. The third magnet 13 has an N pole and an S pole that are magnetized in one pole each, and the center thereof coincides with the rotation axis L.

[0030] The magnetic encoder 1A includes a first sensor unit 20 for detecting the rotation of the rotating body 2 by detecting the magnetic field of the first magnet 11. The first sensor unit 20 includes: a magnetoelectric element W facing the first magnet 11 from the other side L2 in the axial direction; a first microcontroller unit 21 connected to the magnetoelectric element W; and a first non-volatile memory 22. In addition, the first sensor unit 20 may also include a structure other than the above. The magnetoelectric element W is mounted on a second substrate 36 facing the other surface 34 of the magnet holding portion 32.

[0031] In the first sensor unit 20, the magnetoelectric element W is a magnetic sensitive wire such as a Wiegand wire. The Wiegand wire exerts a large Barkhausen effect (Wiegand effect) by changing the magnetic field. The Wiegand wire is an element in which a coil is wound on a ferromagnetic wire. As the first magnet 11 rotates, a pulsed current is generated in the coil when the N pole and the S pole of the first magnet 11 are switched. At this time, the direction of the current changes according to the direction before and after the magnetic field is reversed. Therefore, the direction of the current changes according to the rotation direction of the rotating body 2.

[0032] The first microcontroller unit 21 is provided with a multi-turn rotation information generating unit 23, which performs calculations such as counting the number of rotations based on the output of the magnetic power generation element W. For example, the multi-turn rotation information generating unit 23 performs a process of increasing or decreasing the count value based on the pulsed current and the signal corresponding to its direction, and generates multi-turn rotation information (such as the count value) corresponding to the cumulative number of rotations of the rotating body 2. The first microcontroller unit 21 performs a process of storing the multi-turn rotation information in the first non-volatile memory 22 using the current from the magnetic power generation element W. Therefore, in the first sensor unit 20, even if the power supply from the outside or the battery is stopped, the rotation of the rotating body 2 is detected, and the multi-turn rotation information (hereinafter referred to as the first multi-turn rotation information) stored in the first non-volatile memory 22 is updated.

[0033] The magnetic encoder 1A includes a second sensor unit 40, which detects the angular position within the range of one rotation of the rotating body 2 (hereinafter referred to as one rotation angle) by detecting the magnetic fields of the second magnet 12 and the third magnet 13. The second sensor unit 40 includes: a magnetic sensitive element MR facing the second magnet 12 from one side L1 in the axial direction; and three magnetic detection elements H1, H2, H3 facing the third magnet 13 from one side L1 in the axial direction.

[0034] In the second sensor unit 40, the magnetic sensor element MR and the magnetic detection elements H1, H2, H3 are mounted on a first substrate 35 facing one surface 33 of the magnet holding portion 32. Figure 4In the specific example shown, a substrate holder 37 is fixed on the first substrate 35 from the magnet holder 3 side to form a substrate unit 38. The magnetic sensor MR is arranged on the through portion of the substrate holder 37, and is connected to the sensor circuit provided on the first substrate 35 via a flexible wiring substrate (not shown). The substrate unit 38 is fixed to an encoder holder 39 arranged in a manner surrounding the magnet holder 3, thereby forming a predetermined gap between the magnetic sensor MR and the second magnet 12 and between the magnetic detection elements H1, H2, H3 and the third magnet 13. In addition, the substrate holder 37 may not be provided, and the first substrate 35 to which the magnetic sensor MR and the magnetic detection elements H1, H2, H3 are fixed may be directly fixed to the encoder holder 39.

[0035] The magnetic sensor MR is a magnetoresistive effect element. The magnetic sensor MR has a magnetoresistive pattern of phase A and a magnetoresistive pattern of phase B that are mutually offset by 90° electrical angle in the phase of rotation centered on the rotation axis L. The magnetoresistive pattern of phase A has a magnetoresistive pattern of phase +a and a magnetoresistive pattern of phase -a that are offset by 180 electrical angle. The magnetoresistive pattern of phase B has a magnetoresistive pattern of phase +b and a magnetoresistive pattern of phase -b that are offset by 180 electrical angle. Whenever the rotating body 2 rotates by an angle corresponding to a pair of magnetic pole pairs of the second magnet 12, the magnetic sensor MR outputs two cycles of sin signals and cos signals.

[0036] The magnetic detection elements H1, H2, and H3 are Hall elements. The magnetic detection elements H1, H2, and H3 are arranged at positions that are mutually offset by a mechanical angle of 120° in the phase of rotation centered on the rotation axis L. As described above, the third magnet has a pair of magnetic pole pairs. Therefore, the magnetic detection elements H1, H2, and H3 output a sinusoidal waveform signal of one cycle with a phase offset of 120° from each other during one rotation of the rotating body 2 (i.e., during the period when the pair of magnetic pole pairs passes).

[0037] The second sensor unit 40 includes a second microcontroller unit 41 connected to the magnetic sensor MR and the magnetic detection elements H1, H2, H3, and a second nonvolatile memory 42. The second nonvolatile memory 42 stores information required for startup, such as set values ​​and parameters. The second microcontroller unit 41 includes a position calculation unit 43 and an absolute angle position calculation unit 44.

[0038] The position calculation unit 43 calculates the angular position (one rotation angle) within the range of one rotation of the rotating body 2 based on the output of the magnetic sensor MR and the output of the magnetic detection elements H1, H2, and H3. For example, the position calculation unit 43 performs an inverse tangent calculation based on the output (sin signal and cos signal) of the magnetic sensor MR. Thus, when the number of magnetic pole pairs of the second magnet 12 is set to P, an angle calculation value of P cycles is obtained relative to one rotation of the rotating body 2. Thus, a high-resolution angle calculation value is obtained.

[0039] The position calculation unit 43 uses the outputs of the magnetic detection elements H1, H2, and H3 to perform processing for estimating the angular position of the rotating body 2. In the estimation of the angular position by the position calculation unit 43, a correspondence table between the angular position of the rotating body 2 and the calculated values ​​calculated based on the outputs of the magnetic detection elements H1, H2, and H3 is used. Therefore, when the magnetic encoder 1A is initially set, the rotating body 2 is rotated one circle in advance, and a learning process for creating a correspondence table is performed based on the outputs of the magnetic detection elements H1, H2, and H3 during this period, and the created correspondence table is stored.

[0040] The outputs of the magnetic detection elements H1, H2, and H3 (sinusoidal waveform signals with mutually offset phases) can be converted into a sign of a specified number corresponding to the angular position. For example, by combining the positive and negative judgment results of each signal and the judgment results of the relative magnitude of each signal, it can be converted into a sign of 0 to 11. By performing a rotation of the rotating body 2, the angular position is made to correspond to each sign, thereby making a correspondence table. The position calculation unit 43 calculates the above-mentioned sign based on the outputs of the magnetic detection elements H1, H2, and H3, and reads the angular position corresponding to the calculated value from the correspondence table. Thus, a low-resolution angle estimation value is obtained.

[0041] The position calculation unit 43 calculates the angle of one rotation by combining the high-resolution angle calculation value obtained from the output of the magnetic sensor MR and the low-resolution angle estimation value obtained from the outputs of the magnetic detection elements H1 , H2 , and H3 .

[0042] As described later, the position calculation unit 43 calculates the number of rotations of the rotating body 2 based on the accumulated value of the change in the one-rotation angle. For example, the output (sin signal and cos signal) of the magnetic sensor MR is judged to be positive or negative, etc., and converted into a binary signal, and the count value is increased or decreased based on the binary signal. The value indicating the number of rotations is obtained based on the value obtained by dividing the count value by the number of counts during one rotation of the rotating body 2.

[0043] When the magnetic encoder 1A is started, the absolute angle position calculation unit 44 calculates the absolute angle position of the rotating body 2 for multiple turns based on the output of the position calculation unit 43 and the first multiple-turn rotation information read from the first nonvolatile memory 22 of the first sensor unit 20. That is, the absolute angle position of the rotating body 2 for multiple turns is calculated by combining the first multiple-turn rotation information at the start-up with the one-turn rotation angle calculated at the start-up.

[0044] In addition, as described later, after the absolute angle position calculation unit 44 calculates the absolute angle position of the multi-turn rotation of the rotating body 2 using the first multi-turn rotation information read from the first non-volatile memory 22 at startup, the number of rotations is calculated in the position calculation unit 43 based on the count value based on the change of the calculation value corresponding to the one-turn rotation angle, and combined with the first multi-turn rotation information at startup, thereby, unlike the first multi-turn rotation information continuously updated in the first sensor unit 20, the multi-turn rotation information (hereinafter referred to as the second multi-turn rotation information) is also calculated in the second sensor unit 40. Then, by combining the second multi-turn rotation information and the one-turn rotation angle, the absolute angle position of the multi-turn rotation of the rotating body 2 is calculated.

[0045] (Calculation Processing of Absolute Angle Position in Magnetic Encoder) Figure 5 This is a timing diagram showing the processing flow in the first sensor unit 20 and the second sensor unit 40 at startup, normal time, and backup time. First, the processing at startup (just after the power is turned on) is described. When the magnetic encoder 1A is powered on, in the second sensor unit 40, the second microcontroller unit 41 reads the set values ​​and parameters from the second non-volatile memory 42, and performs startup processing such as initialization of the encoder function (ST1). In addition, the set values ​​and parameters required for the startup processing are notified to the first sensor unit 20, and notification of the first multi-turn rotation information stored in the first non-volatile memory 22 is requested (ST2).

[0046] In the first sensor unit 20, the first microcontroller unit 21 performs a startup process such as initialization of the power generation function using the set values ​​and parameters notified from the second sensor unit 40, and reads the current first multi-turn rotation information from the first nonvolatile memory 22 (ST3). Then, the second sensor unit 40 is notified (ST4).

[0047] In the second sensor unit 40, the position calculation unit 43 calculates the current one-turn angle. The absolute angle position calculation unit 44 calculates the absolute angle position of multiple turns by combining the current one-turn angle with the first multiple-turn information obtained from the first nonvolatile memory 22 (ST5).

[0048] The magnetic encoder 1A is powered on and performs startup processing from a state where there is no power supply from the outside or the battery. Considering the possibility that the rotating body 2 moves during the period when there is no power supply, the accurate cumulative number of rotations from the origin position cannot be obtained only based on the output of the position calculation unit 43. Therefore, at startup, the absolute angle position calculation unit 44 combines the first multi-turn rotation information of the first non-volatile memory 22, which updates the multi-turn rotation information even when there is no power supply, with the one-turn rotation angle calculated by the position calculation unit 43 at startup, thereby calculating the absolute angle position of the multi-turn rotation.

[0049] Next, the processing during normal operation (from the start-up process to the power supply being turned off) is described. In the first sensor unit 20, the multi-turn rotation information generating unit 23 counts the number of turns based on the current generated by the magnetoelectric element W, and continuously updates the first multi-turn rotation information of the first nonvolatile memory 22 (ST6).

[0050] On the other hand, in the second sensor unit 40, the position calculation unit 43 calculates the one-turn angle, and calculates the count value corresponding to the number of rotations based on the change in the calculation value corresponding to the one-turn angle as described above. Then, by combining with the first multi-turn information at the time of startup, in addition to the first multi-turn information continuously updated in the first sensor unit 20, multi-turn information (hereinafter referred to as second multi-turn information) is also calculated in the second sensor unit 40. Then, by combining the one-turn angle and the second multi-turn information, the absolute angular position of the multi-turn is calculated (ST7).

[0051] In addition, in the second sensor unit 40, various processes for abnormality monitoring of the entire magnetic encoder 1A are performed at a low frequency (ST8 to ST10). For example, the first sensor unit 20 is requested to obtain the first multi-turn rotation information at a predetermined timing (ST8), and when the first multi-turn rotation information is notified (ST9), it is checked whether there is an abnormality by comparing it with the second multi-turn rotation information. In addition, it is checked whether there is an abnormality in the output of the magnetic sensor MR, and if there is an abnormality, correction processing is performed, and the correction information stored in the second non-volatile memory 42 is updated. In addition, abnormality monitoring of other encoder functions is performed (ST10).

[0052] Next, the processing during the backup period (a period when there is no power supply from the outside or the battery) is described. In the first sensor unit 20, the multi-turn rotation information generating unit 23 counts the number of rotations based on the current generated by the magnetic generating element W, and continuously updates the first multi-turn rotation information of the first non-volatile memory 22 (ST11). On the other hand, in this state, in the second sensor unit 40, since the power supply is stopped, the calculation of the one-turn rotation angle is stopped, and the calculation of the absolute angular position of the multi-turn rotation is also stopped (ST12).

[0053] (Effects of Embodiment 1) As described above, embodiment 1 is a magnetic encoder 1A that detects the absolute angular position of a rotating body 2 relative to a fixed body, and comprises: a first sensor unit 20 that detects the rotation of the rotating body 2; a second sensor unit 40 that detects the angular position within the range of one rotation of the rotating body 2, that is, the angle of one rotation; an annular first magnet 11 that has a first track T1 magnetized with a pair of N poles and S poles; an annular second magnet 12 that has a second track T2 that has a plurality of pairs of N poles and S poles magnetized alternately in the circumferential direction and is coaxially arranged with the first magnet 11; and an annular third magnet 13 that has a pair of N poles and S poles magnetized and is coaxially arranged with the first magnet 11 and the second magnet 12. The first sensor unit 20 includes: a magnetoelectric element W facing the first magnet 11; a multi-turn rotation information generating unit 23 that performs calculation based on the detection signal of the current generated by the magnetoelectric element W; and a first non-volatile memory 22 that stores multi-turn rotation information corresponding to the cumulative number of rotations of the rotating body 2 and updates the multi-turn rotation information based on the output of the multi-turn rotation information generating unit 23. The second sensor unit 40 includes: a magnetic sensor MR facing the second magnet 12; magnetic detection elements H1, H2, H3 facing the third magnet 13 and arranged in the circumferential direction; a position calculation unit 43 that calculates a one-turn rotation angle based on the outputs of the magnetoelectric element MR and the magnetic detection element H1; and an absolute angle position calculation unit 44 that calculates an absolute angle position based on the multi-turn rotation information and the one-turn rotation angle.

[0054] In the first embodiment, the first sensor unit 20 calculates the multi-turn rotation information corresponding to the cumulative number of rotations of the rotating body 2 based on the detection signal of the current generated by the magnetic power generation element W, and stores it in the first non-volatile memory 22. Therefore, even if there is no power supply from the battery or the outside, the multi-turn rotation information can be continuously updated, and when the magnetic encoder 1A is started, the correct multi-turn rotation information can be read from the first non-volatile memory 22 to calculate the absolute angle position. As a result, even if the rotating body 2 moves during the period when the power supply is not supplied, the number of rotations will not be unclear, and the accurate absolute angle position can be obtained at the time of startup. Therefore, even without the burden of replacing the battery, the correct cumulative number of rotations can be obtained, and the correct absolute angle position of the multi-turn rotation can be output.

[0055] In addition, in the first embodiment, the magnetoelectric element W is used to detect the multi-turn rotation information, the magnetic sensor MR and the magnetic detection element H1 are used to detect the one-turn rotation angle, and the absolute angle position of the multi-turn rotation is calculated based on the one-turn rotation angle and the multi-turn rotation information. Therefore, since the absolute angle position of the multi-turn can be detected only by the magnetic mechanism, the structure can be simplified, and miniaturization and cost reduction can be achieved compared with the case of using an optical encoder. In addition, it has the advantages of being less prone to adverse conditions caused by contamination and high durability. In addition, the second sensor unit 40 has: a high-resolution detection mechanism based on the multi-pole first magnet 11 and the magnetic sensor MR; and a low-resolution detection mechanism using the magnetic detection elements H1, H2, and H3, which can compare and correct the angle values ​​obtained based on the outputs from each detection mechanism. Therefore, a magnetic and high-resolution encoder can be realized. In addition, since no magnet or element is configured on the rotation axis L, it can be set in a manner that does not block the hollow portion when the rotating body 2 is a hollow shaft.

[0056] In the first embodiment, there is a magnet holder 3 having an annular magnet holder 32 centered on the rotation axis L of the rotating body 2. The second magnet 12 is arranged on the outer periphery of one surface 33 of the magnet holder 32, and the third magnet 13 is arranged on the inner periphery of the one surface 33. The first magnet 11 is arranged on the other surface 34 of the magnet holder 32. The magnetic sensitive element MR and the magnetic detection element H1 are arranged on a first substrate 35 opposite to the one surface 33, and the magnetic power generation element W is arranged on a second substrate 36 opposite to the other surface 34.

[0057] In this way, by arranging magnets on the front and back of the magnet holding part 32, the magnetoelectric element W and the magnetic sensitive element MR are opposite to the magnet holding part 32 from opposite sides in the axial direction, so that all the detection mechanisms can be made into a simple and compact structure. In addition, since no element or magnet is arranged on the rotation axis L, it can be set in a manner that does not block the end of the hollow shaft.

[0058] In the first embodiment, in the second sensor unit 40, the absolute angle position calculation unit 44 calculates the absolute angle position based on the first multi-turn rotation information and the newly detected one-turn rotation angle, which are multi-turn rotation information read from the first non-volatile memory 22 at the time of startup, and then calculates the second multi-turn rotation information corresponding to the cumulative number of rotations using the cumulative value of the change in the one-turn rotation angle until the power is turned off, and calculates the absolute angle position based on the second multi-turn rotation information and the one-turn rotation angle. In this way, the absolute angle position of the multi-turn rotation can be obtained based on the output of the second sensor unit 40 while power is supplied to the second sensor unit 40.

[0059] In the first embodiment, the magnetic sensor MR is a magnetoresistive effect element having a magnetoresistive pattern of the A phase and a magnetoresistive pattern of the B phase with a phase difference of 90°, the second track T2 is arranged in two rows in the radial direction, the positions of the S pole and the N pole of the adjacent second track T2 are offset by one pole in the circumferential direction, and the magnetic sensor MR is opposite to the boundary of the adjacent second track T2. Therefore, since the magnetoresistive effect element is arranged in the rotating magnetic field whose direction changes in the in-plane direction of each track, the detection accuracy can be improved. Therefore, the rotation angle of one circle can be detected with high accuracy.

[0060] In addition, in the second sensor unit 40 of the first embodiment, three magnetic detection elements H1, H2, and H3 are provided opposite to the third magnet 13. However, in order to perform the process of estimating the rotation angle of one circle, the number of magnetic detection elements opposite to the third magnet 13 and arranged in the circumferential direction may be three or more, and the configuration is not limited to the mechanical angle interval of 120°. That is, the second sensor unit 40 only needs to include the magnetic sensitive element MR opposite to the second magnet 12 and at least three magnetic detection elements opposite to the third magnet 13 and arranged in the circumferential direction at equal angles.

[0061] In addition, in the first sensor unit 20 and the second sensor unit 40 of the first embodiment, a microcontroller unit is used as an electronic component that performs calculation processing, but other electronic components may be used.

[0062] (Implementation Method 2) The structure of the magnet for detecting the rotation angle of one rotation and the arrangement of the elements of the magnetic encoder 1B of the second embodiment are different from those of the first embodiment, and the other structures are the same as those of the first embodiment. Hereinafter, the same symbols are given to the same structures as those of the first embodiment, and the description thereof is omitted. Figure 2 As shown, the magnetic encoder 1B does not include the third magnet 13 . The magnetic detection elements H1 , H2 , and H3 of the second sensor unit 40B are arranged on the first substrate 35 so as to face the first magnet 11 .

[0063] The magnetic encoder 1B includes a magnet holder 3 having an annular magnet holder 32 centered on the rotation axis L of the rotating body 2. The second magnet 12 is arranged on one surface 33 of the magnet holder 32, and the first magnet 11 is arranged on the other surface 34 of the magnet holder 32. The magnetic sensitive element MR is arranged on a first substrate 35 facing the one surface 33, and the magnetoelectric element W and the magnetic detection elements H1, H2, and H3 are arranged on a second substrate 36 facing the other surface 34.

[0064] (Effects of Embodiment 2) As described above, the magnetic encoder 1B of the second embodiment includes: the first sensor unit 20 that detects the rotation of the rotating body 2; the second sensor unit 40B that detects the angular position within the range of one rotation of the rotating body 2, that is, the one-turn rotation angle; the annular first magnet 11 that includes the first track T1 magnetized with a pair of N poles and S poles; and the annular second magnet 12 that includes the second track T2 that alternately magnetizes a plurality of pairs of N poles and S poles in the circumferential direction and is coaxially arranged with the first magnet 11. The first sensor unit 20B includes: the magnetoelectric element W that faces the first magnet 11; the multi-turn rotation information generating unit 23 that performs calculations based on the detection signal of the current generated by the magnetoelectric element W; and the first nonvolatile memory 22 that stores the multi-turn rotation information corresponding to the cumulative number of rotations of the rotating body 2 and updates the multi-turn rotation information based on the output of the multi-turn rotation information generating unit 23. The second sensor unit 40B includes: a magnetic sensitive element MR, which is opposite to the second magnet 12; magnetic detection elements H1, H2, H3, which are opposite to the first magnet 11 and arranged in the circumferential direction; a position calculation unit 43, which calculates the angle of one rotation based on the outputs of the magnetic sensitive element MR and the magnetic detection elements H1, H2, H3; and an absolute angle position calculation unit 44, which calculates the absolute angle position based on multi-turn rotation information and the angle of one rotation.

[0065] The magnetic encoder 1B of the second embodiment performs the same operation as the first embodiment. Figure 5 's timing diagram. Therefore, the same effect as that of embodiment 1 can be obtained. That is, the correct absolute angle position of multiple rotations can be output without the burden of replacing batteries. In addition, a magnetic and high-resolution encoder can be realized. Moreover, no magnet or element is arranged on the rotation axis L, and it can be set in a manner that does not block the hollow portion. Moreover, compared with the case of using an optical encoder, the structure can be simplified, and miniaturization and cost reduction can be achieved. In particular, since the first magnet 11 is used for both the detection of the number of rotations and the detection of the angle of one rotation, the number of components can be further reduced, and cost reduction can be achieved.

[0066] (Implementation 3) The structure of the magnet for detecting the rotation angle of one revolution and the number and arrangement of the elements of the magnetic encoder 1C of the third embodiment are different from those of the first and second embodiments, and the other structures are the same as those of the first and second embodiments. Figure 3As shown, the magnetic encoder 1C includes a fourth magnet 14 disposed on the inner circumference of one surface 33 of the magnet holding portion 32. The fourth magnet 14 is magnetized with a plurality of pairs of N poles and S poles alternately in the circumferential direction. The second sensor portion 40C includes: first, second, and third magnetic detection elements H1, H2, and H3 (a first magnetic detection element group) facing the fourth magnet 14; and fourth, fifth, sixth, and seventh magnetic detection elements H4, H5, H6, and H7 (a second magnetic detection element group) facing the first magnet 11.

[0067] The magnetic encoder 1C has a magnet holder 3, which has an annular magnet holder 32 centered on the rotation axis L of the rotating body 2. The second magnet 12 is arranged on the outer periphery of one surface 33 of the magnet holder 32, and the fourth magnet 14 is arranged on the inner periphery of the one surface 33. The first magnet 11 is arranged on the other surface 34 of the magnet holder 32. The magnetic sensitive element MR and the first, second and third magnetic detection elements H1, H2 and H3 are arranged on a first substrate 35 opposite to the one surface 33. The magnetic power generation element W and the fourth, fifth, sixth and seventh magnetic detection elements H4, H5, H6 and H7 are arranged on a second substrate 36 opposite to the other surface 34.

[0068] In the position calculation unit 43C of the second sensor unit 40C that calculates the one-rotation angle, a signal of a sinusoidal waveform of one cycle with phases shifted by a certain angle is input from the magnetic detection elements H1, H2, and H3 while the rotating body 2 rotates by an angle obtained by dividing 360° by the number of magnetic pole pairs of the fourth magnet 14. On the other hand, a signal of a sinusoidal waveform of one cycle with phases shifted by a certain angle is input from the magnetic detection elements H4, H5, H6, and H7 while the rotating body 2 rotates by one rotation.

[0069] The position calculation unit 43C uses the outputs of the magnetic detection elements H1, H2, H3 (the first magnetic detection element group) and the outputs of the magnetic detection elements H4, H5, H6, H7 (the second magnetic detection element group) to perform processing for estimating the angular position of the rotating body 2. In the estimation of the angular position by the position calculation unit 43C, a correspondence table between the angular position of the rotating body 2 and the calculated values ​​calculated based on the outputs of the magnetic detection elements H1 to H7 is used. When the magnetic encoder 1C is initially set, the rotating body 2 is rotated one circle in advance, and a learning process for creating a correspondence table is performed based on the outputs of the magnetic detection elements H1 to H7 during this period, and the created correspondence table is stored.

[0070] The preparation of the correspondence table and the learning process are performed, for example, as follows. The outputs of the magnetic detection elements H1, H2, and H3 (sinusoidal waveform signals with mutually offset phases) can be converted into a specified number of symbols corresponding to the angular position. For example, the symbols are converted into 0 to 11 corresponding to the number of combinations of the positive and negative judgment results of each signal and the judgment results of the relative magnitude of each other. Thus, each time the rotating body 2 rotates by an angle obtained by dividing one revolution (360°) by the number of magnetic pole pairs (P) of the fourth magnet 14, a calculated value varying from 0 to 11 is obtained.

[0071] On the other hand, by converting the outputs of the magnetic detection elements H4, H5, H6, and H7 into 1-bit digital values, the angle during one rotation of the rotating body 2 can be divided into intervals represented by 4-bit digital value signals. A correspondence table is prepared by matching the symbols representing the angular position with the respective intervals obtained by dividing one rotation (360°) by the total number of combinations of 4-bit digital values ​​and symbols from 0 to 11.

[0072] When calculating the one-rotation angle, position calculation unit 43C calculates the above-mentioned signs and digital values ​​based on the outputs of magnetic detection elements H1 to H7, reads the angular position corresponding to the calculated value from the correspondence table, and performs processing to estimate the one-rotation angle.

[0073] (Effects of Embodiment 3) As described above, the magnetic encoder 1C includes: a first sensor unit 20 that detects the rotation of the rotating body 2; a second sensor unit 40C that detects the angular position within the range of one rotation of the rotating body 2, that is, the one-turn rotation angle; an annular first magnet 11 that includes a first track T1 magnetized with a pair of N poles and S poles; an annular second magnet 12 that includes a second track T2 magnetized with a plurality of pairs of N poles and S poles alternately in the circumferential direction and arranged coaxially with the first magnet 11; and an annular fourth magnet 14 that magnetized with a plurality of pairs of N poles and S poles alternately in the circumferential direction and arranged coaxially with the first magnet 11 and the second magnet 12. The first sensor unit 20 includes: a magnetoelectric element W that faces the first magnet 11; a multi-turn rotation information generating unit 23 that performs calculations based on a detection signal of a current generated by the magnetoelectric element W; and a first nonvolatile memory 22 that stores multi-turn rotation information corresponding to the cumulative number of rotations of the rotating body 2 and updates the multi-turn rotation information based on the output of the multi-turn rotation information generating unit 23. The second sensor unit 40C includes: a magnetic sensitive element MR, which is opposite to the second magnet 12; magnetic detection elements H1, H2, H3 (first magnetic detection element group), which are opposite to the first magnet 11 and arranged in the circumferential direction; magnetic detection elements H4, H5, H6, H7 (second magnetic detection element group), which are opposite to the fourth magnet 14 and arranged in the circumferential direction; a position calculation unit 43C, which calculates the angle of one rotation based on the outputs of the magnetic sensitive element MR, the first magnetic detection element group and the second magnetic detection element group; and an absolute angle position calculation unit 44, which calculates the absolute angle position based on multi-turn rotation information and the angle of one rotation.

[0074] The magnetic encoder 1C of the third embodiment performs the same operation as the first and second embodiments. Figure 5 's timing diagram. Therefore, the same effects as those of embodiments 1 and 2 can be obtained. That is, the correct absolute angle position of multiple rotations can be output without the burden of replacing batteries. In addition, a magnetic and high-resolution encoder can be realized. In particular, embodiment 3 uses the outputs of magnetic detection elements H1 to H7 to estimate the angular position of the rotating body. Therefore, when calculating the angle of one rotation, the angle position can be estimated with better accuracy than embodiments 1 and 2. In addition, no magnets or elements are arranged on the rotation axis L, and it can be set in a manner that does not block the hollow portion. Moreover, compared with the case of using an optical encoder, the structure can be simplified, and miniaturization and cost reduction can be achieved.

[0075] In addition, in the second sensor unit 40C of embodiment 3, the first magnetic detection element group is composed of three elements, but the number of elements included in the first magnetic detection element group can be more than three. That is, the first magnetic detection element group only needs to have three or more magnetic detection elements including the first, second, and third magnetic detection elements H1, H2, and H3 that are opposite to the first magnet 11 and arranged at equal angles in the circumferential direction. Similarly, the second magnetic detection element group that is opposite to the fourth magnet 14 is composed of four elements, but the number of elements in the second magnetic detection element group can be more than three. That is, the second magnetic detection element group only needs to have three or more magnetic detection elements including the fourth, fifth, and sixth magnetic detection elements H4, H5, and H6 that are opposite to the fourth magnet 14 and arranged at equal angles in the circumferential direction.

[0076] (Other Embodiments) In the third embodiment, the fourth magnet 14 is provided as a magnet facing the magnetic detection elements H1, H2, and H3, but the magnetic detection elements H1, H2, and H3 may be configured to face the second magnet 12. In this case, the fourth magnet 14 is not required. [Explanation of Symbols]

[0077] 1A, 1B, 1C…magnetic encoder, 2…rotating body, 3…magnet holder, 11…first magnet, 12…second magnet, 13…third magnet, 14…fourth magnet, 20, 20B…first sensor unit, 21…first microcontroller unit, 22…first nonvolatile memory, 23…multi-turn rotation information generating unit, 31…shaft, 32…magnet holder, 33…one surface, 34…other surface, 35…first substrate, 36…second substrate, 37…substrate holder, 38…substrate Unit, 39…encoder holder, 40, 40B, 40C…second sensor unit, 41…second microcontroller unit, 42…second non-volatile memory, 43, 43C…first position calculation unit, 44…absolute angle position calculation unit, H1, H2, H3, H4, H5, H6, H7…magnetic detection element, L…rotation axis, L1…one side of the axis direction, L2…the other side of the axis direction, MR…magnetic sensitive element, T1…first track, T2…second track, W…magnetic generating element.

Claims

1. A magnetic encoder for detecting the absolute angular position of a rotating body relative to a fixed body, characterized in that: have: a first sensor portion that detects rotation of the rotating body; a second sensor unit configured to detect an angular position within a range of one rotation of the rotating body, that is, a one-rotation angle; A first annular magnet having a first track magnetized with a pair of N poles and S poles; an annular second magnet having a second track having a plurality of pairs of N poles and S poles alternately magnetized in a circumferential direction and arranged coaxially with the first magnet; and a third annular magnet, the third magnet being magnetized with a pair of N poles and S poles and being coaxially arranged with the first magnet and the second magnet, The first sensor unit includes: a magnetic power generation element, the magnetic power generation element is opposite to the first magnet; a multi-turn rotation information generation unit, the multi-turn rotation information generation unit performs calculation based on the detection signal of the current generated by the magnetic power generation element; and a nonvolatile memory storing multi-turn rotation information corresponding to the cumulative number of turns of the rotating body and updating the multi-turn rotation information according to the output of the multi-turn rotation information generating unit, The second sensor unit includes: a magnetic sensitive element, which is opposite to the second magnet; at least three magnetic detection elements, which are opposite to the third magnet and arranged in a circumferential direction; a position calculation unit, which calculates the one-circle rotation angle based on the outputs of the magnetic sensitive element and the magnetic detection element; and an absolute angle position calculation unit, which calculates the absolute angle position based on the multi-circle rotation information and the one-circle rotation angle.

2. The magnetic encoder according to claim 1, characterized in that A magnet holder is provided, the magnet holder having an annular magnet holding portion centered on the rotation axis of the rotating body, The second magnet is arranged on the outer periphery of one surface of the magnet holding portion. The third magnet is arranged on the inner periphery of the one surface, The first magnet is arranged on the other surface of the magnet holding portion. The magnetic sensing element and the magnetic detecting element are arranged on a first substrate opposite to the one surface, The magnetoelectric element is disposed on a second substrate facing the other surface.

3. A magnetic encoder for detecting the absolute angular position of a rotating body relative to a fixed body, characterized in that: have: a first sensor portion that detects rotation of the rotating body; a second sensor unit configured to detect an angular position within a range of one rotation of the rotating body, that is, a one-rotation angle; a first annular magnet having a first track magnetized with a pair of N poles and S poles; and an annular second magnet having a second track with a plurality of pairs of N poles and S poles alternately magnetized in the circumferential direction and arranged coaxially with the first magnet, The first sensor unit includes: a magnetic power generation element, the magnetic power generation element is opposite to the first magnet; a multi-turn rotation information generation unit, the multi-turn rotation information generation unit performs calculation based on the detection signal of the current generated by the magnetic power generation element; and a nonvolatile memory storing multi-turn rotation information corresponding to the cumulative number of turns of the rotating body and updating the multi-turn rotation information according to the output of the multi-turn rotation information generating unit, The second sensor unit includes: a magnetic sensitive element, which is opposite to the second magnet; at least three magnetic detection elements, which are opposite to the first magnet and arranged in a circumferential direction; a position calculation unit, which calculates the one-circle rotation angle based on the outputs of the magnetic sensitive element and the magnetic detection element; and an absolute angle position calculation unit, which calculates the absolute angle position based on the multi-circle rotation information and the one-circle rotation angle.

4. The magnetic encoder according to claim 3, characterized in that: A magnet holder is provided, the magnet holder having an annular magnet holding portion centered on the rotation axis of the rotating body, The second magnet is arranged on one surface of the magnet holding portion. The first magnet is arranged on the other surface of the magnet holding portion. The magnetic sensor is arranged on a first substrate opposite to the one surface. The magnetic power generation element and the magnetic detection element are arranged on a second substrate facing the other surface.

5. A magnetic encoder for detecting the absolute angular position of a rotating body relative to a fixed body, characterized in that: have: a first sensor portion that detects rotation of the rotating body; a second sensor unit configured to detect an angular position within a range of one rotation of the rotating body, that is, a one-rotation angle; A first annular magnet having a first track magnetized with a pair of N poles and S poles; an annular second magnet having a second track with a plurality of pairs of N poles and S poles alternately magnetized in a circumferential direction and arranged coaxially with the first magnet; as well as an annular fourth magnet having a plurality of pairs of N poles and S poles alternately magnetized in the circumferential direction and arranged coaxially with the first magnet and the second magnet, The first sensor unit includes: a magnetic power generation element, the magnetic power generation element is opposite to the first magnet; a multi-turn rotation information generation unit, the multi-turn rotation information generation unit performs calculation based on the detection signal of the current generated by the magnetic power generation element; and a nonvolatile memory storing multi-turn rotation information corresponding to the cumulative number of turns of the rotating body and updating the multi-turn rotation information according to the output of the multi-turn rotation information generating unit, The second sensor unit includes: a magnetic sensitive element, which is opposite to the second magnet; a first magnetic detection element group, which is composed of more than three magnetic detection elements including a first magnetic detection element, a second magnetic detection element, and a third magnetic detection element, which are opposite to the first magnet and arranged in a circumferential direction; a second magnetic detection element group, which is composed of more than three magnetic detection elements including a fourth magnetic detection element, a fifth magnetic detection element, and a sixth magnetic detection element, which are opposite to the fourth magnet and arranged in a circumferential direction; a position calculation unit, which calculates the one-circle rotation angle based on the outputs of the magnetic sensitive element, the first magnetic detection element group, and the second magnetic detection element group; and an absolute angular position calculation unit, which calculates the absolute angular position based on the multi-circle rotation information and the one-circle rotation angle.

6. The magnetic encoder according to claim 5, characterized in that: A magnet holder is provided, the magnet holder having an annular magnet holding portion centered on the rotation axis of the rotating body, The second magnet is arranged on the outer periphery of one surface of the magnet holding portion. The fourth magnet is arranged on the inner periphery of the one surface, The first magnet is arranged on the other surface of the magnet holding portion. The magnetic sensing element and the second magnetic detection element group are arranged on a first substrate opposite to the one surface, The magnetic power generation element and the first magnetic detection element group are arranged on a second substrate facing the other surface.

7. The magnetic encoder according to any one of claims 1 to 6, characterized in that: The absolute angle position calculation unit At startup, the absolute angle position is calculated based on the multi-turn rotation information, i.e., the first multi-turn rotation information, read from the nonvolatile memory and the newly detected one-turn rotation angle. Then, until power is turned off, second multi-rotation information corresponding to the accumulated number of rotations is calculated using the accumulated value of the change in the one-rotation angle, and the absolute angular position is calculated based on the second multi-rotation information and the one-rotation angle.

8. The magnetic encoder according to any one of claims 1 to 6, characterized in that: The magneto-sensitive element is a magnetoresistive effect element including a magnetoresistive pattern of an A phase and a magnetoresistive pattern of a B phase having a phase difference of 90° with each other. The second tracks are arranged in two rows in the radial direction, the positions of the S poles and the N poles of adjacent second tracks are offset by one pole in the circumferential direction, and the magnetic sensitive elements are opposite to the boundaries of the adjacent second tracks.

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