Magnetic encoder

Abstract

To provide a high-resolution magnetic encoder for detecting an absolute angular position in multi-rotation, which is battery-less and suitable for a hollow shaft.SOLUTION: A magnetic encoder 1A comprising a magnetic power generation element W, generates a pulse-like current on the basis of a change in a magnetic field of a first magnet 11 magnetized with a pair of N pole and S pole, calculates multi-rotation information without external power supply, and stores the multi-rotation information in a first nonvolatile memory 22. A second sensor part 40 calculates, on the basis of output of a magneto-sensitive element MR facing a second magnet 12 magnetized circumferential and alternately with plural pairs of N pole and S pole and output of magnetic detection elements H1, H2, H3 facing a third magnet 13 magnetized with the pair of N pole and S pole, one rotation angle which is an angular position of a rotor 2 in one rotation range. When started up, the encoder reads the multi-rotation information from the first nonvolatile memory 22, and calculates an absolute angular position of multi-rotation by coupling the multi-rotation information to the one rotation angle calculated at start-up.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

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

[0003] [Patent Document 1] Patent No. 6877168 [Patent Document 2] Patent No. 6323558 Summary of the Invention [Problem to be solved by the invention]

[0004] Encoders that detect absolute angular position over multiple rotations need to count the number of rotations, but to correctly count the cumulative number of rotations (multiple rotation information), it is necessary to maintain a state where rotation can always be detected when the rotating body moves, and to continue counting reliably. Conventionally, a configuration has been used in which a power supply is secured by connecting a battery, and a state where rotation can always be detected is maintained, but this requires periodic battery replacement, which imposes a large maintenance burden.

[0005] On the other hand, when an encoder is attached to the rotating shaft of a motor, the rotating shaft may be made hollow due to demands for miniaturization and reduction of wiring space. For this reason, an encoder with a configuration suitable for hollow shafts is required. Conventionally, magnetic encoders generally have a configuration in which a first magnet is arranged on the rotating axis as in Patent Document 1, but such an arrangement blocks the end of the hollow shaft, making it impossible to use the hollow part as wiring space.

[0006] Here, Patent Document 2 describes an encoder device that uses a magnetic encoder unit that has a power generation unit that generates current due to changes in the magnetic field of a Wiegand wire or the like and detects the number of rotations based on the pulse of the generated current, and an optical encoder unit with high resolution. In this configuration, 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 in Patent Document 2 has a magnet or a scale arranged on the axis of rotation, making it possible to accommodate hollow shafts.

[0007] However, the encoder device of Patent Document 2 employs an optical encoder unit to detect the absolute angular position with high resolution, and uses both magnetic and optical systems. The combined use of an optical system requires a clean environment during assembly, which increases costs and makes it difficult to miniaturize and simplify the structure. In addition, optical encoders have the problem of low durability.

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

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

[0010] In order to solve the above problem, a second aspect of the present invention is a magnetic encoder for detecting an absolute angular position of a rotating body relative to a fixed body, the encoder comprising: a first sensor unit for detecting rotation of the rotating body; a second sensor unit for detecting a one rotation angle which is an angular position within a range of one rotation of the rotating body; an annular first magnet having a first track on which a pair of N poles and S poles are magnetized; and an annular second magnet having a second track on which multiple pairs of N poles and S poles are magnetized alternately in a circumferential direction and arranged coaxially with the first magnet, the first sensor unit detecting an absolute angular position of a rotating body relative to a fixed body, the first sensor unit detecting an absolute angular position of a rotating body relative to a fixed body, the second ... second sensor unit detecting an absolute angular position of a rotating body relative to a fixed body The rotating body has a multi-rotation information generating unit that performs calculations based on a current detection signal, and a non-volatile memory that stores multi-rotation information corresponding to the cumulative number of rotations of the rotating body and updates the multi-rotation information based on the output of the multi-rotation information generating unit.The second sensor unit has a magnetic sensing element facing the second magnet, at least three magnetic detection elements facing the first magnet and aligned in the circumferential direction, a position calculation unit that calculates the one-rotation angle based on the outputs of the magnetic sensing element and the magnetic detection elements, and an absolute angle position calculation unit that calculates the absolute angle position based on the multi-rotation information and the one-rotation angle.

[0011] In order to solve the above-mentioned problems, a third aspect of the present invention is a magnetic encoder for detecting an absolute angular position of a rotating body relative to a fixed body, the magnetic encoder comprising: a first sensor unit for detecting rotation of the rotating body; a second sensor unit for detecting a one-rotation angle which is an angular position within a range of one rotation of the rotating body; an annular first magnet having a first track on which a pair of N poles and S poles are magnetized; an annular second magnet having a second track on which multiple pairs of N poles and S poles are magnetized alternately in a circumferential direction and arranged coaxially with the first magnet; and an annular fourth magnet having multiple pairs of N poles and S poles magnetized alternately in a circumferential direction and arranged coaxially with the first magnet and the second magnet, the first sensor unit comprising a magnetic generating element facing the first magnet; and a non-volatile memory that stores multi-rotation information corresponding to a cumulative number of rotations of the rotating body and updates the multi-rotation information based on an output of the multi-rotation information generation unit, wherein the second sensor unit comprises: a magnetic sensing element facing the second magnet; a first magnetic detection element group consisting of three or more magnetic detection elements including first, second and third magnetic detection elements facing the first magnet and aligned in a circumferential direction; a second magnetic detection element group consisting of three or more magnetic detection elements including fourth, fifth and sixth magnetic detection elements facing the fourth magnet and aligned in a circumferential direction; a position calculation unit that calculates the one-rotation angle based on outputs of the magnetic sensing element, the first magnetic detection element group and the second magnetic detection element group; and an absolute angle position calculation unit that calculates the absolute angle position based on the multi-rotation information and the one-rotation angle. do.

[0012] According to each aspect of the present invention, the first sensor unit calculates multi-rotation information corresponding to the cumulative number of rotations of the rotor based on the detection signal of the current generated by the magnetic power generating element, and stores the information in a non-volatile memory. Therefore, the multi-rotation information can be continuously updated even without a battery or external power supply, and when the encoder is started, the correct multi-rotation information can be read from the non-volatile memory to calculate the absolute angular position. Therefore, the correct cumulative number of rotations can be obtained without the burden of replacing the battery, and the correct absolute angular position of the multi-rotation can be output.

[0013] According to each aspect of the present invention, the multiple rotation information is detected using a magnetic generating element, the single rotation angle is detected using a magnetic sensing element and a magnetic detection element, and the absolute angle position of the multiple rotations is calculated from the single rotation angle and the multiple rotation information (accumulated number of rotations). Therefore, since the absolute angle position of the multiple rotations can be detected only by a magnetic mechanism, the configuration can be simplified, and the size and cost can be reduced compared to the case of using an optical encoder. In addition, there is an advantage that the occurrence of defects due to dirt is unlikely and durability is high. Furthermore, since the second sensor unit is equipped with a high-resolution detection mechanism using a multi-pole first magnet and a magnetic sensing element, and further equipped with a low-resolution detection mechanism using three or more magnetic detection elements arranged in the circumferential direction, the angle values ​​obtained from the outputs from the separate detection mechanisms can be compared and corrected. Therefore, a high-resolution encoder can be realized despite being a magnetic type. Furthermore, since no magnet or element is arranged on the rotation axis, it can be installed so as not to block the end of the hollow shaft, and is suitable for a hollow shaft.

[0014] In a first aspect of the present invention, it is preferable that the magnet holder has a ring-shaped magnet holding portion centered on the rotation axis of the rotating body, the second magnet is arranged on the outer periphery of one side of the magnet holding portion, the third magnet is arranged on the inner periphery of the one side, the first magnet is arranged on the other side of the magnet holding portion, the magnetic sensing element and the magnetic detection element are arranged on a first substrate facing the one side, and the magnetic power generation element is arranged on a second substrate facing the other side.

[0015] In a second aspect of the present invention, it is preferable that the rotor has a magnet holder equipped with a ring-shaped magnet holding portion centered on the rotation axis of the rotating body, the second magnet is arranged on one side of the magnet holding portion, the first magnet is arranged on the other side of the magnet holding portion, the magnetic sensing element is arranged on a first substrate facing the one side, and the magnetic power generation element and the magnetic detection element are arranged on a second substrate facing the other side.

[0016] In a third aspect of the present invention, it is preferable that the magnet holder has a ring-shaped magnet holding portion centered on the rotation axis of the rotating body, the second magnet is arranged on the outer periphery of one side of the magnet holding portion, the fourth magnet is arranged on the inner periphery of the one side, the first magnet is arranged on the other side of the magnet holding portion, the magnetic sensing element and the second group of magnetic detection elements are arranged on a first substrate facing the one side, and the magnetic power generation element and the first group of magnetic detection elements are arranged on a second substrate facing the other side.

[0017] In this way, in each aspect of the present invention, magnets are placed on the front and back of the magnet holding part, and the magnetic generating element and the magnetic sensing element face the magnet holding part from opposite sides in the axial direction. Therefore, all detection mechanisms can be made simple and compact. Also, because magnets and elements are not placed on the rotation axis, they can be installed so as not to block the end of the hollow shaft.

[0018] In each aspect of the present invention, the absolute angle position calculation unit calculates the absolute angle position based on the first multi-rotation information, which is the multi-rotation information read from the nonvolatile memory, and the newly detected one-rotation angle at the time of startup, and thereafter calculates second multi-rotation information corresponding to the accumulated number of rotations using an accumulated value of the one-rotation angle until the power is turned off, and It is preferable to calculate the absolute angular position based on the multiple rotation information and the one rotation angle. In this way, even if the rotating body moves while power is not supplied, the number of rotations will not become unknown, and an accurate absolute angular position can be obtained at startup. Also, while power is supplied to the second sensor unit, the multiple rotation absolute angular position can be obtained from the output of the second sensor unit.

[0019] In each aspect of the present invention, the magnetic sensing element is a magnetoresistance effect element having a magnetoresistance pattern of phase A and a magnetoresistance pattern of phase B having a phase difference of 90°, the second tracks are arranged in two rows in the radial direction, the positions of the S pole and the N pole of the adjacent second tracks are shifted by one pole in the circumferential direction, and the magnetic sensing element is preferably opposed to the boundary between the adjacent second tracks. In this way, the magnetoresistance effect element is disposed in a rotating magnetic field whose direction changes in the in-plane direction of each track, thereby improving detection accuracy. Effect of the Invention

[0020] According to the present invention, it is possible to output the correct multi-rotation absolute angular position without the burden of replacing the battery. In addition, it can be installed so as not to block the end of the hollow shaft, and is suitable for hollow shafts. Furthermore, it is possible to realize an encoder with high resolution while being entirely magnetic, which allows for miniaturization and cost reduction, is less prone to malfunction due to dirt, and is highly durable. [Brief description of the drawings]

[0021] [Figure 1] 1 is a configuration diagram and a functional block diagram of a main part of a magnetic encoder according to a first embodiment. [Diagram 2] FIG. 11 is a configuration diagram and a functional block diagram of a main part of a magnetic encoder according to a second embodiment. [Diagram 3] FIG. 11 is a configuration diagram and a functional block diagram of a main part of a magnetic encoder according to a third embodiment. [Figure 4] 1 is a cross-sectional view showing a specific example of a magnetic encoder according to a first embodiment. [Diagram 5] 4 is a sequence diagram showing the flow of processes in the first sensor unit and the second sensor unit at the time of startup, normal operation, and backup operation. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] An embodiment of a magnetic encoder according to the present invention will be described below. The magnetic encoder according to the present invention is a multi-rotation absolute angular position encoder that can know the number of rotations from a predetermined origin position and the current angular position.

[0023] In this specification, the configuration of the magnetic encoder according to the present invention will be described, focusing on the specific configuration of its main parts, namely the magnet and magnet holder, various elements that detect changes in the magnetic field, and the substrate on which these are arranged, but descriptions of other parts (such as the outer case) will be omitted.

[0024] 1, 2, and 3 are respectively a configuration diagram (arrangement of magnets and elements) and a functional block diagram of the main parts of a magnetic encoder according to the present invention. FIG. 1 is a configuration diagram and a functional block diagram of the main parts of a magnetic encoder 1A of embodiment 1. FIG. 2 is a configuration diagram and a functional block diagram of the main parts of a magnetic encoder 1B of embodiment 2. FIG. 3 is a configuration diagram and a functional block diagram of the main parts of a magnetic encoder 1C of embodiment 3. FIG. 4 is a cross-sectional view showing the main parts of a specific example of the magnetic encoder 1A of embodiment 1.

[0025] (Embodiment 1) The magnetic encoder 1A of the first embodiment has a rotating body 2, such as the rotating shaft of a motor, as a measurement target. As shown in Fig. 1, 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 arranged coaxially with the rotation axis L of the rotating body 2 as the center. The magnet holder 3 includes a cylindrical shaft portion 31 and an annular magnet holding portion 32 that expands outward from the shaft portion 31. The shaft portion 31 is fixed to the rotating shaft It extends in the axial direction of line L. Magnet holder 32 is disposed at an end of one side L1 in the axial direction of shaft 31 (see FIG. 4). Shaft 31 is fixed to the rotating shaft of the motor (rotating body 2) by, for example, a set screw.

[0026] The first magnet 11, the second magnet 12, and the third magnet 13 are 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 one surface 33 faces one side L1 in the axial direction, and the other surface 34 faces the other side L2 in the axial direction (see FIG. 4). As shown in FIGS. 1 and 4, on the one surface 33, the second magnet 12 is arranged on the outer periphery of the magnet holder 32, and the third magnet 13 is arranged on the inner periphery of the magnet holder 32.

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

[0028] The second magnet 12 is disposed on the outer periphery of one surface 33 of the magnet holder 32. The second magnet 12 has an annular second track T2 in which multiple pairs of N poles and S poles are magnetized alternately in the circumferential direction, and its center coincides with the rotation axis L. The second tracks T2 are arranged in two rows in the radial direction. The positions of the N poles and S poles of the radially adjacent second tracks T2 are shifted by one pole in the circumferential direction. The second magnet 12 has, for example, 128 pairs of N poles and S poles magnetized alternately in the circumferential direction. Note that the number of N poles and S poles may be a number other than 128 pairs.

[0029] The third magnet 13 is disposed on the inner periphery of one surface 33 of the magnet holder 32. The third magnet 13 is magnetized with one north pole and one south pole, and its center coincides with the axis L of rotation.

[0030] The magnetic encoder 1A includes a first sensor unit 20 that detects the rotation of the rotating body 2 by detecting the magnetic field of the first magnet 11. The first sensor unit 20 includes a magnetic generating element W that faces the first magnet 11 from the other side L2 in the axial direction, a first microcontroller unit 21 that is connected to the magnetic generating element W, and a first non-volatile memory 22. Note that the first sensor unit 20 may include configurations other than those described above. The magnetic generating element W is mounted on a second substrate 36 that faces the other surface 34 of the magnet holding unit 32.

[0031] In the first sensor unit 20, the magnetic generating element W is a magnetosensitive wire such as a Wiegand wire. The Wiegand wire exhibits the large Barkhausen effect (Wiegand effect) when a magnetic field changes. The Wiegand wire is an element in which a coil is wound around a ferromagnetic wire, and as the first magnet 11 rotates, a pulse-like current is generated in the coil when the coil passes the position where the N pole and S pole of the first magnet 11 switch. At this time, the direction of the current changes depending on the direction before and after the magnetic field reversal. Therefore, the direction of the current changes depending on the rotation direction of the rotating body 2.

[0032] The first microcontroller unit 21 includes a multi-rotation information generating section 23 that performs calculations such as counting the number of rotations based on the output of the magnetic generating element W. For example, the multi-rotation information generating section 23 performs a process of incrementing or decrementing a counter value based on a pulsed current and a signal corresponding to its direction, and generates multi-rotation information (e.g., a counter value) corresponding to the accumulated number of rotations of the rotating body 2. The first microcontroller unit 21 performs a process of storing the multi-rotation information in the first non-volatile memory 22 using the current from the magnetic generating element W. Therefore, even if the power supply from the outside or a battery is stopped, the first sensor section 20 detects the rotation of the rotating body 2 and stores the multi-rotation information in the first non-volatile memory 22 (hereinafter referred to as the first multi-rotation information). (hereinafter referred to as "information") is updated.

[0033] The magnetic encoder 1A includes a second sensor unit 40 that detects the angular position within one rotation range of the rotor 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 sensing 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 section 40, the magnetic sensing element MR and the magnetic detection elements H1, H2, and H3 are mounted on a first substrate 35 facing one surface 33 of the magnet holding section 32. For example, in the specific example shown in FIG. 4, a substrate holder 37 is fixed to the first substrate 35 from the side of the magnet holder 3 to form a substrate unit 38. The magnetic sensing element MR is disposed in a penetration portion of the substrate holder 37 and is connected to a 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 disposed so as to surround the magnet holder 3, thereby forming a predetermined gap between the magnetic sensing element MR and the second magnet 12, and between the magnetic detection elements H1, H2, and H3 and the third magnet 13. It is also possible to eliminate the substrate holder 37 and directly fix the first substrate 35 to which the magnetic sensing element MR and the magnetic detection elements H1, H2, and H3 are fixed to the encoder holder 39.

[0035] The magnetic sensing element MR is a magnetoresistance effect element. The magnetic sensing element MR has an A-phase magnetic resistance pattern and a B-phase magnetic resistance pattern that are shifted from each other by 90° in electrical angle in the phase of rotation about the rotation axis L. The A-phase magnetic resistance pattern has a +a-phase magnetic resistance pattern and a -a-phase magnetic resistance pattern that are shifted from each other by 180 in electrical angle. The B-phase magnetic resistance pattern has a +b-phase magnetic resistance pattern and a -b-phase magnetic resistance pattern that are shifted from each other by 180 in electrical angle. The magnetic sensing element MR outputs two periods of sine and cosine signals every time the rotating body 2 rotates through an angle equivalent to one pair of magnetic pole pairs of the second magnet 12.

[0036] The magnetic detection elements H1, H2, and H3 are Hall elements. The magnetic detection elements H1, H2, and H3 are disposed at positions shifted from each other by 120° mechanical angle in the phase of rotation about 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 one period of sinusoidal waveform signals shifted from each other by 120° phase while the rotor 2 rotates once (i.e., while passing through one pair of magnetic pole pairs).

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

[0038] The position calculation unit 43 calculates an angular position (one rotation angle) within one rotation range of the rotor 2 from the output of the magneto-sensing element MR and the outputs of the magnetic detection elements H1, H2, and H3. For example, the position calculation unit 43 performs an arctangent calculation based on the output (sine signal and cosine signal) of the magneto-sensing element MR. As a result, when the number of magnetic pole pairs of the second magnet 12 is P, an angle calculation value of P periods is obtained for one rotation of the rotor 2. As a result, an angle calculation value with high resolution is obtained.

[0039] The position calculation unit 43 performs processing to estimate the angular position of the rotating body 2 using the outputs of the magnetic detection elements H1, H2, and H3. The position calculation unit 43 estimates the angular position using a correspondence table between the angular position of the rotating body 2 and values ​​calculated from the outputs of the magnetic detection elements H1, H2, and H3. For this reason, when the magnetic encoder 1A is initially set up, the operation of one rotation of the rotating body 2 is previously calculated. A learning process is performed to create a correspondence table from 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 (sine-wave signals with mutually out-of-phase relationships) can be converted into a predetermined number of codes corresponding to the angular positions. For example, by combining the results of determining whether each signal is positive or negative and the results of determining the magnitude relationship between the signals, the signals can be converted into codes from 0 to 11. A correspondence table is created by associating angular positions with each code as the rotor 2 rotates once. The position calculation unit 43 calculates the above codes from the outputs of the magnetic detection elements H1, H2, and H3, and reads out the angular positions corresponding to the calculated values ​​from the correspondence table. This provides a low-resolution angle estimate.

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

[0042] As described below, the position calculation unit 43 also performs a process of calculating the number of rotations of the rotating body 2 from the accumulated value of the change in the angle of one rotation. For example, the position calculation unit 43 performs a process of converting the output (sine signal and cosine signal) of the magnetic sensing element MR into a binary signal by determining whether it is positive or negative, and performs a process of adding or subtracting a counter value based on the binary signal. A value indicating the number of rotations is obtained by dividing the counter value by the number of counts during one rotation of the rotating body 2.

[0043] At the time of startup of the magnetic encoder 1A, the absolute angular position calculation unit 44 calculates the absolute angular position of multiple rotations of the rotating body 2 based on the output of the position calculation unit 43 and the first multiple rotation information read from the first nonvolatile memory 22 of the first sensor unit 20. In other words, the absolute angular position of multiple rotations of the rotating body 2 is calculated by combining the first multiple rotation information at startup with the one-rotation angle calculated at startup.

[0044] As will be described later, after calculating the absolute angular position of multiple rotations of the rotor 2 using the first multiple rotation information read from the first nonvolatile memory 22 at startup, the absolute angular position calculation unit 44 calculates the number of rotations from a count value based on changes in the calculation value corresponding to one rotation angle in the position calculation unit 43 and combines this with the first multiple rotation information at startup to calculate multiple rotation information (hereinafter referred to as second multiple rotation information) in the second sensor unit 40 separately from the first multiple rotation information that is continually updated in the first sensor unit 20. Then, the absolute angular position of multiple rotations of the rotor 2 is calculated by combining the second multiple rotation information with the one rotation angle.

[0045] (Calculation of absolute angle position in magnetic encoder) 5 is a sequence diagram showing the flow of processing in the first sensor section 20 and the second sensor section 40 at startup, normal operation, and backup. First, the processing at startup (immediately after power is turned on) will be described. When power is turned on to the magnetic encoder 1A, in the second sensor section 40, the second microcontroller unit 41 reads setting values ​​and parameters from the second nonvolatile memory 42 and performs startup processing such as initialization of the encoder function (ST1). In addition, the second microcontroller unit 41 notifies the first sensor section 20 of setting values ​​and parameters required for startup processing, and requests notification of the first multiple-rotation information stored in the first nonvolatile memory 22 (ST2).

[0046] In the first sensor section 20, the first microcontroller unit 21 performs start-up processing such as initialization of the power generation function using the set values ​​and parameters notified from the second sensor section 40, and reads the current first multiple rotation information from the first non-volatile memory 22 (ST3). Then, it notifies the second sensor section 40 (ST4).

[0047] In the second sensor unit 40, the position calculation unit 43 calculates the current one rotation angle. Absolute angle position The calculation unit 44 calculates the absolute angle position of multiple rotations by combining the current single rotation angle with the first multiple rotation information acquired from the first non-volatile memory 22 (ST5).

[0048] The magnetic encoder 1A is powered on and a startup procedure is performed when there is no power supply from an external source or a battery. Considering the possibility that the rotating body 2 may move while there is no power supply, an accurate cumulative number of rotations from the origin position cannot be obtained only from the output of the position calculation unit 43. Therefore, at startup, the absolute angle position calculation unit 44 calculates the absolute angle position of multiple rotations by combining the first multiple rotation information in the first non-volatile memory 22, in which the multiple rotation information is updated even without power supply, with the one-rotation angle calculated by the position calculation unit 43 at startup.

[0049] Next, the normal processing (from the start-up processing until the power is turned off) will be described. In the first sensor unit 20, the multiple-rotation information generating unit 23 counts the number of rotations based on the current generated in the magnetic generating element W, and continues to update the first multiple-rotation information in the first non-volatile memory 22 (ST6).

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

[0051] The second sensor unit 40 performs various processes at low frequency to monitor the entire magnetic encoder 1A for abnormalities (ST8 to ST10). For example, the first sensor unit 20 is requested to provide first multi-rotation information at a predetermined timing (ST8), and when the first multi-rotation information is notified (ST9), the presence or absence of an abnormality is confirmed by comparing it with the second multi-rotation information. The second sensor unit 40 also checks for abnormalities in the output of the magnetic sensing element MR, and if there is an abnormality, performs a correction process and updates the correction information stored in the second non-volatile memory 42. Furthermore, the second sensor unit 40 monitors for abnormalities in other encoder functions (ST10).

[0052] Next, the process during backup (when there is no power supply from the outside or a battery) will be described. In the first sensor unit 20, the multiple rotation information generating unit 23 counts the number of rotations based on the current generated by the magnetic generating element W, and continues to update the first multiple rotation information in the first non-volatile memory 22 (ST11). Meanwhile, in this state, the power supply to the second sensor unit 40 is stopped, so the calculation of the single rotation angle is stopped, and the calculation of the absolute angle position of multiple rotations is also stopped (ST12).

[0053] (Effects of the First Embodiment) 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 includes a first sensor unit 20 that detects the rotation of the rotating body 2, a second sensor unit 40 that detects the one rotation angle, which is the angular position within the range of one rotation of the rotating body 2, an annular first magnet 11 having a first track T1 on which a pair of N poles and S poles are magnetized, an annular second magnet 12 having a second track T2 on which multiple pairs of N poles and S poles are magnetized alternately in the circumferential direction and arranged coaxially with the first magnet 11, and an annular third magnet 13 on which a pair of N poles and S poles are magnetized and arranged coaxially with the first magnet 11 and the second magnet 12. The first sensor unit 20 includes a magnetic generating element W facing the first magnet 11, a multi-rotation information generating unit 23 that performs calculations based on a detection signal of a current generated by the magnetic generating element W, and a first non-volatile memory 22 that stores multi-rotation information corresponding to the cumulative number of rotations of the rotor 2 and updates the multi-rotation information based on the output of the multi-rotation information generating unit 23. The second sensor unit 40 includes a magnetic sensing element MR facing the second magnet 12, magnetic detection elements H1, H2, and H3 facing the third magnet 13 and aligned in the circumferential direction, and a position sensor that calculates a one-rotation angle based on the outputs of the magnetic sensing element MR and the magnetic detection element H1. The apparatus includes a calculation unit 43 and an absolute angle position calculation unit 44 that calculates an absolute angle position based on the multiple rotation information and the one-rotation angle.

[0054] In the first embodiment, the first sensor unit 20 calculates multiple 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 generating element W, and stores the information in the first nonvolatile memory 22. Therefore, the multiple rotation information can be continuously updated even without a battery or external power supply, and when the magnetic encoder 1A is started, the correct multiple rotation information can be read from the first nonvolatile memory 22 to calculate the absolute angle position. As a result, even if the rotating body 2 moves while power is not being supplied, the number of rotations will not become unknown, and an accurate absolute angle position can be obtained at the time of start-up. Therefore, the correct cumulative number of rotations can be obtained without the burden of replacing the battery, and the correct absolute angle position of multiple rotations can be output.

[0055] In addition, in the first embodiment, the multiple rotation information is detected using the magnetic generating element W, the single rotation angle is detected using the magnetic sensing element MR and the magnetic detection element H1, and the absolute angle position of the multiple rotations is calculated from the single rotation angle and the multiple rotation information. Therefore, since the absolute angle position of the multiple rotations can be detected only by the magnetic mechanism, the configuration can be simplified, and the size and cost can be reduced compared to the case of using an optical encoder. In addition, there is an advantage that the malfunction due to dirt is unlikely to occur and the durability is high. Furthermore, the second sensor unit 40 is equipped with a high-resolution detection mechanism using the multi-pole first magnet 11 and the magnetic sensing element MR, and a low-resolution detection mechanism using the magnetic detection elements H1, H2, and H3, and the angle values ​​obtained from the outputs from the separate detection mechanisms can be compared and corrected. Therefore, a high-resolution encoder can be realized even though it is a magnetic type. In addition, since no magnets or elements are arranged on the rotation axis L, when the rotor 2 is a hollow shaft, it can be installed so as not to block the hollow part.

[0056] In the first embodiment, the magnet holder 3 includes an annular magnet holding portion 32 centered on the rotation axis L of the rotor 2. The second magnet 12 is disposed on the outer periphery of one surface 33 of the magnet holding portion 32, and the third magnet 13 is disposed on the inner periphery of the one surface 33. The first magnet 11 is disposed on the other surface 34 of the magnet holding portion 32. The magnetic sensing element MR and the magnetic detection element H1 are disposed on a first substrate 35 facing the one surface 33, and the magnetic power generation element W is disposed on a second substrate 36 facing the other surface 34.

[0057] In this way, by arranging magnets on the front and back of the magnet holding portion 32 and having the magnetic generating element W and the magnetic sensing element MR face the magnet holding portion 32 from opposite sides in the axial direction, it is possible to make the entire detection mechanism simple and compact. Also, since no elements or magnets are arranged on the rotation axis L, they can be installed so as not to 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 an absolute angle position based on the first multi-rotation information, which is the multi-rotation information read from the first non-volatile memory 22, and a newly detected one-rotation angle at startup, and thereafter calculates second multi-rotation information corresponding to the accumulated number of rotations using the accumulated value of the change in the one-rotation angle until the power is turned off, and calculates an absolute angle position based on the second multi-rotation information and the one-rotation angle. In this way, while power is being supplied to the second sensor unit 40, the absolute angle position of multiple rotations can be obtained from the output of the second sensor unit 40.

[0059] In the first embodiment, the magnetic sensing element MR is a magnetoresistance effect element having a magnetic resistance pattern of phase A and a magnetic resistance pattern of phase B having a phase difference of 90° from each other, the second tracks T2 are arranged in two rows in the radial direction, the positions of the S pole and the N pole of the adjacent second tracks T2 are shifted by one pole in the circumferential direction, and the magnetic sensing element MR faces the boundary between the adjacent second tracks T2. Therefore, the magnetoresistance effect element is arranged in a rotating magnetic field whose direction changes in the in-plane direction of each track. Therefore, the detection accuracy can be improved, and the angle of one rotation can be detected with high accuracy.

[0060] In the second sensor unit 40 of the first embodiment, three magnetic detection elements H1, H2, and H3 facing the third magnet 13 are provided, but in order to perform the process of estimating one rotation angle, the number of magnetic detection elements facing the third magnet 13 and aligned in the circumferential direction may be three or more, and the arrangement is not limited to an interval of 120° mechanical angle. That is, the second sensor unit 40 may include a magnetic sensing element MR facing the second magnet 12, and at least three magnetic detection elements facing the third magnet 13 and aligned at equal angular intervals in the circumferential direction.

[0061] Furthermore, in the first sensor section 20 and the second sensor section 40 of the first embodiment, a microcontroller unit is used as an electronic element for performing arithmetic processing, but other electronic elements may also be used.

[0062] (Embodiment 2) The magnetic encoder 1B of the second embodiment differs from the first embodiment in the configuration of the magnet for detecting one rotation angle and the arrangement of the elements, but the other configurations are the same as those of the first embodiment. Hereinafter, the same configurations as those of the first embodiment are given the same reference numerals and the description will be omitted. As shown in FIG. 2, the magnetic encoder 1B does not include a third magnet 13. The magnetic detection elements H1, H2, and H3 of the second sensor unit 40B face the first magnet 11 and are arranged on the first substrate 35.

[0063] The magnetic encoder 1B has a magnet holder 3 equipped with an annular magnet holding portion 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 holding portion 32, and the first magnet 11 is arranged on the other surface 34 of the magnet holding portion 32. The magnetic sensing element MR is arranged on a first substrate 35 facing the one surface 33, and the magnetic generating element W and the magnetic detecting elements H1, H2, H3 are arranged on a second substrate 36 facing the other surface 34.

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

[0065] The magnetic encoder 1B of the second embodiment performs the process of the sequence diagram of FIG. 5, as in the first embodiment. Therefore, the same effects as those of the first embodiment can be obtained. That is, the correct absolute angular position of multiple rotations can be output without the burden of replacing the battery. In addition, a high-resolution encoder can be realized despite being magnetic. Furthermore, no magnet or element is arranged on the rotation axis L, and the encoder can be installed so as not to block the hollow portion. Furthermore, compared to the case where an optical encoder is used, the configuration can be simplified, and miniaturization and cost reduction can be achieved. In particular, since the first magnet 11 is used for both detecting the number of rotations and detecting the angle of one rotation, the number of parts can be reduced, and costs can be reduced.

[0066] (Embodiment 3) The magnetic encoder 1C of the third embodiment differs from the first and second embodiments in the configuration of the magnet that detects one rotation angle and the number and arrangement of the elements, but the other configurations are the same as those of the first and second embodiments. As shown in FIG. 3, the magnetic encoder 1C includes a fourth magnet 14 disposed on the inner periphery of one surface 33 of the magnet holder 32. The fourth magnet 14 is magnetized with multiple pairs of N poles and S poles alternately arranged in the circumferential direction. The second sensor unit 40C includes first, second, and third magnetic detection elements H1, H2, and H3 (first magnetic detection element group) facing the fourth magnet 14, and fourth, fifth, sixth, and seventh magnetic detection elements H4, H5, H6, and H7 (second magnetic detection element group) facing the first magnet 11.

[0067] The magnetic encoder 1C has a magnet holder 3 with an annular magnet holding portion 32 centered on the rotation axis L of the rotor 2. The second magnet 12 is disposed on the outer periphery of one surface 33 of the magnet holding portion 32, and the fourth magnet 14 is disposed on the inner periphery of the one surface 33. The first magnet 11 is disposed on the other surface 34 of the magnet holding portion 32. The magnetic sensing element MR and the first, second and third magnetic detection elements H1, H2 and H3 are disposed on a first substrate 35 facing the one surface 33. The magnetic generating element W and the fourth, fifth, sixth and seventh magnetic detection elements H4, H5, H6 and H7 are disposed on a second substrate 36 facing the other surface 34.

[0068] In the second sensor unit 40C, in a position calculation unit 43C that calculates one rotation angle, one period of sinusoidal waveform signals mutually shifted in phase by a fixed angle are input from the magnetic detection elements H1, H2, and H3 while the rotor 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, one period of sinusoidal waveform signals mutually shifted in phase by a fixed angle are input from the magnetic detection elements H4, H5, H6, and H7 while the rotor 2 rotates once.

[0069] The position calculation unit 43C performs a process of estimating the angular position of the rotating body 2 using the outputs of the magnetic detection elements H1, H2, and H3 (first magnetic detection element group) and the outputs of the magnetic detection elements H4, H5, H6, and H7 (second magnetic detection element group). The position calculation unit 43C estimates the angular position using a correspondence table between the angular position of the rotating body 2 and values ​​calculated from the outputs of the magnetic detection elements H1 to H7. During the initial setting of the magnetic encoder 1C, a learning process is performed in advance to create a correspondence table from the outputs of the magnetic detection elements H1 to H7 by performing one rotation of the rotating body 2, and the created correspondence table is stored.

[0070] The correspondence table is created and the learning process is performed, for example, as follows. The outputs of the magnetic detection elements H1, H2, and H3 (sine-wave signals with mutually out-of-phase relationships) can be converted into a predetermined number of codes corresponding to the angular positions. For example, they are converted into codes from 0 to 11 corresponding to the number of combinations of the results of the positive / negative judgment of each signal and the judgment results of the magnitude relationship between them. This results in a calculated value that changes from 0 to 11 every time the rotor 2 rotates an angle obtained by dividing one rotation (360°) by the number of magnetic pole pairs (P) of the fourth magnet 14.

[0071] Meanwhile, 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 rotor 2 can be divided into sections represented by 4-bit digital value signals. A correspondence table is created by associating a code indicating an angular position with each of the sections into which one rotation (360°) is divided according to the total number of combinations of the 4-bit digital values ​​and codes from 0 to 11.

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

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

[0074] The magnetic encoder 1C of the third embodiment performs the process of the sequence diagram of FIG. 5 in the same manner as in the first and second embodiments. Therefore, the same effects as those of the first and second embodiments can be obtained. That is, the correct absolute angular position of multiple rotations can be output without the burden of replacing the battery. In addition, a high-resolution encoder can be realized despite being magnetic. In particular, the third embodiment estimates the angular position of the rotating body using the output of the magnetic detection elements H1 to H7, so that when calculating the angle of one rotation, the angular position can be estimated with higher accuracy than the first and second embodiments. In addition, no magnet or element is arranged on the rotation axis L, and the hollow part can be installed so as not to block it. Furthermore, compared to the case of using an optical encoder, the configuration can be simplified, and the size and cost can be reduced.

[0075] In the second sensor unit 40C of the third embodiment, the first magnetic detection element group is composed of three elements, but the number of elements included in the first magnetic detection element group may be three or more. That is, the first magnetic detection element group may include three or more magnetic detection elements including the first, second, and third magnetic detection elements H1, H2, and H3 that face the first magnet 11 and are arranged at equal angular intervals in the circumferential direction. Similarly, the second magnetic detection element group that faces the fourth magnet 14 is composed of four elements, but the number of elements in the second magnetic detection element group may be three or more. That is, the second magnetic detection element group may include three or more magnetic detection elements including the fourth, fifth, and sixth magnetic detection elements H4, H5, and H6 that face the fourth magnet 14 and are arranged at equal angular intervals in the circumferential direction.

[0076] (Other embodiments) In the third embodiment, the magnetic detection elements H1, H2, and H3 are provided with the fourth magnet 14 as a magnet facing them, but a configuration may be adopted in which the magnetic detection elements H1, H2, and H3 face the second magnet 12. In this case, the fourth magnet 14 is not necessary. [Explanation of symbols]

[0077] Reference Signs List 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 section, 21...first microcontroller unit, 22...first non-volatile memory, 23...multi-rotation information generating section, 31...shaft section, 32...magnet holding section, 33...one side, 34...other side, 35...first board, 36...second board, 37...board holder, 38...board unit, 39...encoder holder, 40, 40B, 40C...second sensor section, 41...second microcontroller unit, 42...second non-volatile memory, 43, 43C...first position calculation section, 44...absolute angle position calculation section, H1, H2, H3, H4, H5, H6, H7...magnetic detection element, L...rotation axis, L1...axial direction one side of the track, L2...the other side in the axial direction, MR...magnetic sensing element, T1...first track, T2...second track, W...magnetic generating element

Claims

1. A magnetic encoder for detecting an absolute angular position of a rotating body relative to a fixed body, A first sensor unit that detects rotation of the rotating body; a second sensor unit for detecting a one-rotation angle which is an angular position within a range of one rotation of the rotating body; a first magnet having an annular shape and a first track having a pair of north and south poles magnetized thereon; a second magnet having a ring-shaped second track in which a plurality of pairs of N poles and S poles are alternately magnetized in a circumferential direction and arranged coaxially with the first magnet; a third magnet having a ring shape and a pair of N and S poles magnetized and arranged coaxially with the first magnet and the second magnet; the first sensor unit includes a magnetic power generating element facing the first magnet, a multi-rotation information generating unit that performs a calculation based on a detection signal of a current generated by the magnetic power generating element, and a non-volatile memory that stores multi-rotation information corresponding to a cumulative number of rotations of the rotor and updates the multi-rotation information based on an output of the multi-rotation information generating unit; the second sensor unit comprises a magnetic sensing element facing the second magnet, at least three magnetic detection elements facing the third magnet and arranged in a circumferential direction, a position calculation unit that calculates the one-rotation angle based on outputs of the magnetic sensing element and the magnetic detection elements, and an absolute angular position calculation unit that calculates the absolute angular position based on the multi-rotation information and the one-rotation angle.

2. a magnet holder including an annular magnet holding portion centered on a rotation axis of the rotor; The second magnet is disposed on an outer periphery of one surface of the magnet holder, The third magnet is disposed on an inner periphery of the one surface, The first magnet is disposed on the other surface of the magnet holder, the magnetic sensing element and the magnetic detection element are disposed on a first substrate facing the one surface, 2. The magnetic encoder according to claim 1, wherein the magnetic power generating element is disposed on a second substrate facing the other surface.

3. A magnetic encoder for detecting an absolute angular position of a rotating body relative to a fixed body, A first sensor unit that detects rotation of the rotating body; a second sensor unit for detecting a one-rotation angle which is an angular position within a range of one rotation of the rotating body; a first magnet having an annular shape and a first track having a pair of north and south poles magnetized thereon; a second magnet having a ring-shaped second track in which a plurality of pairs of N poles and S poles are alternately magnetized in a circumferential direction and arranged coaxially with the first magnet; the first sensor unit includes a magnetic power generating element facing the first magnet, a multi-rotation information generating unit that performs a calculation based on a detection signal of a current generated by the magnetic power generating element, and a non-volatile memory that stores multi-rotation information corresponding to a cumulative number of rotations of the rotor and updates the multi-rotation information based on an output of the multi-rotation information generating unit; a position calculation unit that calculates the one-rotation angle based on outputs of the magnetic sensing element and the magnetic detection elements; and an absolute angular position calculation unit that calculates the absolute angular position based on the multi-rotation information and the one-rotation angle.

4. a magnet holder including an annular magnet holding portion centered on a rotation axis of the rotor; The second magnet is disposed on one surface of the magnet holder, The first magnet is disposed on the other surface of the magnet holder, The magnetic sensing element is disposed on a first substrate facing the one surface, 4. The magnetic encoder according to claim 3, wherein the magnetic generating element and the magnetic detecting element are disposed on a second substrate facing the other surface.

5. A magnetic encoder for detecting an absolute angular position of a rotating body relative to a fixed body, A first sensor unit that detects rotation of the rotating body; a second sensor unit for detecting a one-rotation angle which is an angular position within a range of one rotation of the rotating body; a first magnet having an annular shape and a first track having a pair of north and south poles magnetized thereon; a second magnet having a ring-shaped second track in which a plurality of pairs of N poles and S poles are alternately magnetized in a circumferential direction and arranged coaxially with the first magnet; a fourth magnet having a ring shape in which a plurality of pairs of N poles and S poles are alternately magnetized in a circumferential direction and which is arranged coaxially with the first magnet and the second magnet; the first sensor unit includes a magnetic power generating element facing the first magnet, a multi-rotation information generating unit that performs a calculation based on a detection signal of a current generated by the magnetic power generating element, and a non-volatile memory that stores multi-rotation information corresponding to a cumulative number of rotations of the rotor and updates the multi-rotation information based on an output of the multi-rotation information generating unit; the second sensor unit comprises a magnetic sensing element facing the second magnet, a first magnetic detection element group consisting of three or more magnetic detection elements including first, second and third magnetic detection elements facing the first magnet and aligned in the circumferential direction, a second magnetic detection element group consisting of three or more magnetic detection elements including fourth, fifth and sixth magnetic detection elements facing the fourth magnet and aligned in the circumferential direction, a position calculation unit that calculates the one rotation angle based on outputs of the magnetic sensing element, the first magnetic detection element group, and the second magnetic detection element group, and an absolute angle position calculation unit that calculates the absolute angular position based on the multi-rotation information and the one rotation angle.

6. a magnet holder including an annular magnet holding portion centered on a rotation axis of the rotor; The second magnet is disposed on an outer periphery of one surface of the magnet holder, The fourth magnet is disposed on an inner periphery of the one surface, The first magnet is disposed on the other surface of the magnet holder, the magnetic sensing element and the second magnetic detection element group are disposed on a first substrate facing the one surface, 6. The magnetic encoder according to claim 5, wherein the magnetic generating element and the first group of magnetic detection elements are arranged on a second substrate facing the other surface.

7. The absolute angle position calculation unit At the time of startup, the absolute angle position is calculated based on the first multiple-rotation information, which is the multiple-rotation information read from the non-volatile memory, and the newly detected one-rotation angle; 7. A magnetic encoder according to claim 1, wherein, during the period until the power is turned off, a cumulative value of the change in the one-rotation angle is used to calculate second multiple-rotation information corresponding to the cumulative number of rotations, and the absolute angular position is calculated based on the second multiple-rotation information and the one-rotation angle.

8. the magnetic sensing element is a magnetoresistance effect element having an A-phase magnetoresistance pattern and a B-phase magnetoresistance pattern having a phase difference of 90° from each other, The magnetic encoder according to any one of claims 1 to 6, characterized in that the second tracks are arranged in two rows in the radial direction, the positions of the S pole and N pole of adjacent second tracks are shifted by one pole in the circumferential direction, and the magnetic sensing element faces the boundary between adjacent second tracks.

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