Multi-rotation angle detection device

Abstract

The present invention provides a multi-rotation angle detection device that generates a multi-rotation absolute angle detection value of a rotating body that rotates around a rotation axis. The multi-rotation angle detection device includes a segment counter that counts segments divided after a one-rotation period of the rotating body in an angle region exceeding one rotation; a fine absolute angle detector that generates an absolute angle detection value within the one-rotation period of the rotating body; and an arithmetic device that integrates outputs thereof to generate the multi-rotation absolute angle detection value. The segment counter includes a power generation sensor, a magnetic field generation source, a sensor element, and a nonvolatile memory that stores a count value. The magnetic field generation source applies an alternating magnetic field of k periods (k is an integer of 3 or more) to an axial direction of a magnetic wire every one rotation of the rotating body. The arithmetic device directly uses the count value stored in the nonvolatile memory to integrate the absolute angle detection value of the fine absolute angle detector when a power supply from the outside is accepted.

Description

[0001] Related applications

[0002] This application claims priority based on Japanese Patent Application No. 2022-170648, filed on October 25, 2022, and all contents of that application are incorporated herein by reference. Technical Field

[0003] This invention relates to a multi-rotation angle detection device using a power generation sensor. More specifically, this invention relates to a device that integrates the count value of a segmented counter using a power generation sensor with an angle detection value obtained from an angle detector that can precisely detect the absolute angle of one rotation cycle, to detect multiple rotation absolute angles exceeding one rotation. Background Technology

[0004] Magnetic wires exhibiting the Big Backhausen effect (Big Backhausen jump) are called Wiegand wires or pulse wires. These magnetic wires consist of a core and a skin portion surrounding the core. One of the core and the skin portion is a soft magnetic layer whose magnetization reverses even under a weak magnetic field, while the other is a hard magnetic layer whose magnetization does not reverse unless a strong magnetic field is applied. By winding a coil around such a magnetic wire, a power generation sensor can be constructed.

[0005] When the hard magnetic layer and the soft magnetic layer are magnetized in the same direction along the axis of the conductor, if the strength of an external magnetic field in the opposite direction to their magnetization direction increases and reaches a certain strength, the magnetization direction of the soft magnetic layer reverses. This reversal of magnetization direction propagates from a portion of the magnetic conductor to the entire conductor, and the magnetization direction of the soft magnetic layer also reverses. At this time, the Big Barkhausen effect occurs, inducing a pulse signal in the coil wound on the magnetic conductor. When the strength of the external magnetic field increases further and reaches a certain strength, the magnetization direction of the hard magnetic layer reverses.

[0006] In this specification, the magnetic field strength when the magnetization direction of the soft magnetic layer is reversed is referred to as the "operating magnetic field," and the magnetic field strength when the magnetization direction of the hard magnetic layer is reversed is referred to as the "stable magnetic field."

[0007] It has the following characteristics: the output voltage obtained from the coil is constant, independent of the rate of change of the input magnetic field (external magnetic field), and has a hysteresis characteristic relative to the input magnetic field, thus preventing jitter. Therefore, the pulse signal generated from the coil can be used in position detection devices, etc.

[0008] When an alternating magnetic field is applied to the power generation sensor, a total of two pulse signals are generated in one cycle: one positive pulse signal and one negative pulse signal. A magnet can be used as the source of the magnetic field. The alternating magnetic field is applied to the power generation sensor by the relative motion between the magnet and the sensor, and the position is detected by counting the generated pulse signals.

[0009] Since the output from the coil has power, it can be used to construct a power-generating sensor (power-generating sensor) that does not require an external power supply. In other words, without providing external power, the peripheral circuits can be activated by the energy output from the coil.

[0010] Absolute encoders and other angle sensors are inherently unable to detect angles exceeding one rotation. While powered on, they can detect angles exceeding one rotation by accumulating the movement, but this information is lost if the power is cut off.

[0011] On the other hand, segmented counters utilizing generator sensors can continue counting even when the external power supply is cut off, thanks to the output energy of the coil, allowing them to detect multiple rotations beyond one. However, segmented counters using generator sensors typically only detect coarse angles. Therefore, in applications requiring precise angle detection, such as motor control, the count value of the segmented counter is integrated with the angle detection value from a separately installed precision absolute angle detector, thereby utilizing precise angle detection values ​​across multiple rotations (multi-rotation absolute angle detection values).

[0012] Patent Documents 1 and 2 disclose a method and apparatus for integrating the count value of a segment counter and the angle detection value of a precision absolute angle detector.

[0013] Patent document 1 uses a segmented counter that positions three power generation sensors at 60-degree phase differences.

[0014] Using only the output of a single power sensor, the direction of motion cannot be identified when it changes. Therefore, by using multiple power sensors and utilizing the phase difference between their outputs, the direction of motion can be identified.

[0015] To generate a pulse voltage from the power sensor, the magnetization directions of the hard and soft magnetic layers of the magnetic conductor need to be aligned, while the magnetization direction of only the soft magnetic layer needs to be reversed. If the magnetization directions of the hard and soft magnetic layers are not aligned, even if only the magnetization direction of the soft magnetic layer is reversed, no pulse signal will be generated, or if a pulse signal is generated, it will be very small.

[0016] When rotating continuously in one direction, there is a timing interval between reaching the stable magnetic field and reaching the operating magnetic field, after reaching the operating magnetic field and outputting a pulse voltage, and before reaching the operating magnetic field again. However, the pulse voltage must be generated at the angular position when reaching the operating magnetic field.

[0017] However, in the case of bidirectional rotation, i.e., when the rotation direction is switched, no pulse voltage is output even when the operating magnetic field is reached, sometimes resulting in so-called pulse loss. Specifically, if the rotation direction is reversed after reaching the operating magnetic field and outputting a pulse voltage, and before reaching the stable magnetic field, the magnetization directions of the hard magnetic layer and the soft magnetic layer will be inconsistent even when the operating magnetic field is reached again, so no pulse voltage is output.

[0018] By arranging multiple power generation sensors at positions with different phase differences and using the phase difference of their output pulses, the direction of rotation can be identified. However, even with two power generation sensors, if one of them fails to generate a pulse, the direction of rotation cannot be identified. Therefore, as disclosed in Patent Document 1, three power generation sensors are required. Furthermore, in Patent Document 1, in order to integrate the count value of the segment counter and the detection value of the precision position detector, and to correct for the offset of the origin position, three power generation sensors are arranged at positions with a phase difference of 60 degrees.

[0019] However, using multiple power generation sensors would increase the size and cost of the position detector.

[0020] Patent Document 2 discloses a segmented counter that determines the rotation direction by processing the pulse signal from a power generation sensor and the output signals from other sensor elements besides the power generation sensor, and performs a counting operation accordingly. In this case, if the aforementioned pulse is missing, problems arise when integrating the count value of the segmented counter and the detection value of the precision position detector. Therefore, in Patent Document 2, the magnetization state of the magnetic wire of the power generation sensor is monitored, and the value of the segmented counter is corrected according to the amount of the missing pulse voltage based on its magnetization state. This achieves synchronization between the count value of the segmented counter and the detection value of the precision position detector, and allows for their integration.

[0021] Specifically, in the magnetization state monitor disclosed in Patent Document 2, a gradually increasing current flows through the coil of a power generation sensor, and the magnetic field generated by the coil is applied to a magnetic wire. Therefore, the magnetization direction of the magnetic wire is monitored by observing the voltage generated across the coil. This allows for the inspection of the magnetization state of the magnetic wire.

[0022] However, in order to determine the magnetization direction of the magnetic wire as in Patent Document 2 and to correct the count value based thereon, complex signal processing is required, which makes it difficult to miniaturize the device and reduce costs.

[0023] Existing technical documents

[0024] Patent documents

[0025] Patent Document 1: Japanese Patent No. 6226811

[0026] Patent Document 2: Japanese Patent No. 5730809 Summary of the Invention

[0027] The technical problem that the invention aims to solve

[0028] One embodiment of the present invention provides a multi-rotation angle detection device, which is beneficial for miniaturization and cost reduction of the device.

[0029] More specifically, one embodiment of the present invention provides a multi-rotation angle detection device that can integrate the count value of a segmented counter consisting of multiple power generation sensors and the angle detection value of a precision absolute angle detector to generate a multi-rotation absolute angle detection value without requiring complex signal processing.

[0030] Technical means for solving technical problems

[0031] One embodiment of the present invention provides a multi-rotation angle detection device for generating multi-rotation absolute angle detection values ​​of a rotating body rotating about a rotation axis. The multi-rotation angle detection device includes: a segment counter that counts segments (typically, equally divided) of one rotation cycle of the rotating body within an angular region exceeding one rotation of the rotating body, based on the rotation of the rotating body, and generates count values; a precision absolute angle detector that operates via an external power supply and generates absolute angle detection values ​​within one rotation cycle of the rotating body at a higher resolution than the segments; and a computing unit that operates via an external power supply and integrates the count values ​​of the segment counter and the absolute angle detection values ​​of the precision absolute angle detector to generate the multi-rotation absolute angle detection values ​​of the rotating body. The segment counter includes one (only one) power generation sensor, a magnetic field generator that rotates with the rotating body about the rotation axis, a sensor element different from the power generation sensor (typically, a sensor element other than the power generation sensor), and a non-volatile memory storing the count values. The power generation sensor has a magnetic wire exhibiting the large Backhausen effect and a coil wound around the magnetic wire. It generates pulse voltages by varying the magnetic field that accompanies the rotation of the magnetic field generator. The magnetic field generator applies an alternating magnetic field of k cycles (k being an integer greater than or equal to 3) to the axial direction of the magnetic wire each time the rotating body rotates. The segment counter operates independently of external power supply, powered by the energy from the pulse voltages generated by the power generation sensor. It uses the pulse voltages generated by the power generation sensor and the output signal of the sensor element to identify the rotation direction and position of the rotating body, update the count value, and store it in the non-volatile memory. When the computing device receives external power supply, it directly uses the count value stored in the non-volatile memory (i.e., without performing correction processing on the count value of the segment counter) to integrate the count value of the segment counter and the absolute angle detection value of the precision absolute angle detector, generating a multi-rotation absolute angle detection value for the rotating body.

[0032] According to this structure, an alternating magnetic field of k cycles is applied to the axial direction of the magnetic wire during each rotation by a magnetic field generator, thereby generating 2k pulse voltages per rotation by the power sensor. Since k ≥ 3, an alternating magnetic field of more than 3 cycles is applied to the magnetic wire during each rotation, and the magnetic wire generates more than 6 pulse voltages per rotation. A segment counter can, for example, generate count values ​​by counting segments that divide one rotation cycle into more than k (e.g., k or 2k), i.e., more than 3 segments. Even if pulse loss occurs due to a reversal of the rotation direction, resulting in counting errors, errors of the magnitude of identical count values ​​across angles spanning more than one rotation will not occur. Therefore, with an alternating magnetic field of more than 3 cycles applied to the magnetic wire during each rotation, and the magnetic wire generating more than 6 pulse voltages per rotation, a precise multi-rotation absolute angle value can be uniquely determined by combining the count value of the segment counter and the absolute angle detection value of the precision absolute angle detector in any multi-rotation absolute angle. That is, even if the count value of the segment counter contains errors, it can be integrated with the angle detection value of the precision absolute angle detector without correcting the count value (i.e., using the count value directly).

[0033] Therefore, by using only a single power generation sensor, and without the need for magnetization direction determination processing of magnetic wires and corresponding correction / synchronization processing, the count value of the segment counter and the angle detection value of the precision absolute angle detector can be integrated to generate a precise multi-rotation absolute angle detection value.

[0034] In one embodiment of the invention, the magnetic field generating source comprises k magnets arranged on a circumference centered on the rotation axis, with magnetic poles of the same polarity facing the power generation sensor. The magnetic conductor of the power generation sensor is arranged parallel to the tangent of the circumference. The power generation sensor has a first magnetic flux conducting plate and a second magnetic flux conducting plate, respectively magnetically coupled to both ends of the magnetic conductor. As the magnetic field generating source rotates, the magnetic poles sequentially approach the first and second magnetic flux conducting plates. The power generation sensor generates a negative voltage pulse in a first state where the magnetic flux from the magnetic poles of the magnetic field generating source is conducted from the first magnetic flux conducting plate, and generates a positive voltage pulse in a second state where the magnetic flux from the magnetic field generating source is conducted from the second magnetic flux conducting plate.

[0035] In this embodiment, typically, no other magnetic poles are arranged on the circular track around the axis of rotation through which the magnetic poles of the same polarity of the k magnets pass. Therefore, as the rotating body rotates in one direction, the magnetic poles of the same polarity face the power generation sensor in sequence, and the first state and the second state are repeated alternately.

[0036] According to this structure, the k magnets constituting the magnetic field source are arranged with their magnetic poles of the same polarity facing the power generation sensor. For example, consider the following situation: In a configuration where the soft and hard magnetic layers of the magnetic conductor are magnetized in the direction from the second flux-conducting plate towards the first flux-conducting plate (a configuration for generating negative pulses), the magnetic field source rotates together with the rotating body, and the magnetic pole approaches the first flux-conducting plate. Magnetic flux from this pole is conducted through the first flux-conducting plate, thus reversing the magnetization direction of the soft magnetic layer of the magnetic conductor, generating a negative pulse. As the magnetic pole approaches the first flux-conducting plate further, the magnetization direction of the hard magnetic layer also reverses, and the magnetic conductor becomes configured to generate a positive pulse. When the magnetic field source rotates further, and the magnetic pole approaches the second flux-conducting plate, magnetic flux from this pole is conducted through the second flux-conducting plate. Thus, the magnetization direction of the soft magnetic layer of the magnetic conductor reverses, generating a positive pulse. As the magnetic pole approaches the second flux-conducting plate further, the magnetization direction of the hard magnetic layer also reverses, and the magnetic conductor becomes configured to generate a negative pulse. Thus, when a magnetic pole passes through the detection area of ​​the power generation sensor, two pulses are generated.

[0037] In one embodiment of the present invention, the sensor element detects whether the magnetic pole of the magnetic field generating source is located at a position opposite to the central part of the power generation sensor, and the boundary of the segment is the angular position of the magnetic pole relative to the central part of the power generation sensor.

[0038] The segment boundary refers to the boundary where the count value of the segment counter changes.

[0039] By using a sensor element to detect whether the magnetic poles of the magnetic field generator are opposite to the central part of the power generation sensor, the rotational position and direction can be identified based on the output of the sensor element and the power generation sensor.

[0040] In one embodiment of the present invention, the magnetic field source comprises k magnetic pole pairs arranged alternately with N and S poles on a circumference centered on the axis of rotation.

[0041] For example, consider the following initial state: In a configuration where the soft and hard magnetic layers of the magnetic conductor are magnetized from the second flux-conducting plate towards the first flux-conducting plate (for generating negative pulses), one S pole faces the center of the power generation sensor, and the magnetic flux from a pair of N poles on either side of this S pole reaches equilibrium. From this initial state, when the magnetic field generator rotates slightly with the rotating body, the magnetic flux from the first flux-conducting plate side of the magnetic conductor towards the second flux-conducting plate side increases, thereby achieving an operating magnetic field. The magnetization direction of the soft magnetic layer of the magnetic conductor reverses, generating a negative pulse. When the magnetic field generator rotates further with the rotating body, the magnetic flux from the first flux-conducting plate side of the magnetic conductor towards the second flux-conducting plate side further increases, achieving a stable magnetic field. The magnetization direction of the hard magnetic layer also reverses, and the magnetic conductor becomes configured to generate positive pulses. As the magnetic field source rotates further, the magnetic flux from the second flux-conducting plate side of the magnetic conductor towards the first flux-conducting plate side increases, reaching the operating magnetic field. The magnetization direction of the soft magnetic layer of the magnetic conductor reverses, generating a positive pulse. As the magnetic field source rotates further, the magnetic flux from the second flux-conducting plate side of the magnetic conductor towards the first flux-conducting plate side further increases, reaching a stable magnetic field. The magnetization direction of the hard magnetic layer also reverses, and the magnetic conductor is set to generate a negative pulse. Thus, one magnetic pole pair passes through the detection area of ​​the power generation sensor, generating two pulses.

[0042] In one embodiment of the present invention, the magnetic wire of the power generation sensor is located on a tangent to a circle centered on the axis of rotation, and the center of the magnetic wire is located at the point of tangency of the tangent.

[0043] In one embodiment of the present invention, the sensor element detects the polarity of a magnetic pole opposite to the central portion of the power generation sensor, and the boundary of the segment is the angular position of either the N pole or the S pole of the magnetic pole pair opposite to the central portion of the power generation sensor.

[0044] By using a sensor element to detect the polarity of the magnetic pole opposite the central part of the power generation sensor, the rotational position and direction can be identified based on the output of the sensor element and the power generation sensor.

[0045] The above and other objects, features and effects of the present invention will become more apparent from the description of the embodiments with reference to the accompanying drawings and as described below. Attached Figure Description

[0046] Figure 1 This is a block diagram illustrating a structural example of a multi-rotation angle detection device according to an embodiment of the present invention.

[0047] Figure 2A This is a three-dimensional diagram illustrating the construction example of a segmented counter. Figure 2B This is its top view. And, Figure 2C It is along Figure 2B The main view observed in the direction of arrow IIC.

[0048] Figure 3A , Figure 3B and Figure 3C This is a diagram used to illustrate the function of a power generation sensor.

[0049] Figure 3D , Figure 3E and Figure 3F This is a diagram used to illustrate the function of a power generation sensor.

[0050] Figure 4 This is a diagram used to illustrate the counting action of a segment counter.

[0051] Figure 5 This is a table that provides examples of more detailed counting operations for segmented counters.

[0052] Figure 6 This is a graph used to illustrate the effect of pulse loss on the count value.

[0053] Figure 7 This shows the relationship between the count value of the segment counter and the angle detection value of the precision absolute angle detector.

[0054] Figure 8 This shows the precision multi-rotation absolute angle detection value, which integrates the count value of the segment counter and the angle detection value of the precision absolute angle detector.

[0055] Figure 9A This is a perspective view illustrating an example of the structure of a segmented counter according to other embodiments of the present invention. Figure 9B This is its top view.

[0056] Figure 10A , Figure 10B and Figure 10C This is a diagram used to illustrate the function of a power generation sensor.

[0057] Figure 10D , Figure 10E and Figure 10F This is a diagram used to illustrate the function of a power generation sensor.

[0058] Figure 11 This is a diagram used to illustrate the counting action of a segment counter. Detailed Implementation

[0059] Figure 1This is a block diagram illustrating a structural example of a multi-rotation angle detection device according to one embodiment of the present invention. The multi-rotation angle detection device 100 is a device that detects multiple absolute rotation angles of a rotation axis 30 (an example of a rotating body) rotating about a rotation axis 33, and generates its detection value, i.e., the multi-rotation absolute angle detection value. Multiple absolute rotation angles refer to absolute angles spanning more than one rotation, i.e., angles across multiple rotation regions. The multi-rotation angle detection device 100 includes a precision absolute angle detector 1, a segmented counter 2, and a calculation unit 4.

[0060] The precision absolute angle detector 1 is an angle sensor that generates precise absolute angle detection values ​​for the rotating shaft 30 within one rotation cycle, i.e., from 0 degrees to 360 degrees, with a higher resolution than the segmented counter 2 described below. The precision absolute angle detector 1 is, for example, constructed from an optical absolute encoder. For example, the precision absolute angle detector 1 is configured to generate absolute angle detection values ​​for the angle region (0 degrees to 360 degrees) within one rotation cycle with a resolution of 16 bits (65536 steps).

[0061] Typically, the precision absolute angle detector 1 operates by receiving power from an external power source. Specifically, the multi-rotation angle detection device 100 includes a power supply circuit 3 that can be connected to an external power source. When the power supply circuit 3 is connected to an external power source, it supplies power to the precision absolute angle detector 1, which then operates. The precision absolute angle detector 1, for example, inputs a 16-bit absolute angle detection value to the arithmetic unit 4 via serial communication.

[0062] The segment counter 2 counts the segments obtained by dividing (equally dividing) one rotation cycle of the rotation axis 30 according to the rotation of the rotation axis 30, and generates a count value representing the angle value of the segment unit in the angle region spanning multiple rotations (more than one rotation) across the rotation axis 30.

[0063] The segment counter 2 includes one (only one) power generation sensor 20, a magnetic field source 50 that rotates with the rotation axis 30 about the rotation axis 33, a sensor element MS (non-power generation sensor) different from the power generation sensor 20, a counter circuit 8, and a non-volatile memory 9 for storing the count value. The non-volatile memory 9 can be constructed of FeRAM (ferroelectric random access memory). In this embodiment, the counter circuit 8 and the non-volatile memory 9 are assembled into a counter memory IC (integrated circuit) 10. The segment counter 2 also includes a signal evaluation circuit 5, a rectification / power supply circuit 6, and a signal processing circuit 7.

[0064] The power generation sensor 20 generates a pulse voltage based on the change in the magnetic field accompanying the rotation of the magnetic field generator 50. In this embodiment, the sensor element MS is a magnetic sensor that detects the magnetic field of the magnetic field generator 50 based on its rotation. An example of a magnetic sensor is a Hall IC. The signal evaluation circuit 5 determines the polarity of the pulse voltage generated by the power generation sensor 20 and provides a signal (pulse polarity PP) representing the result of this polarity determination to the signal processing circuit 7. The signal processing circuit 7 converts the signal representing the result of the polarity determination obtained from the signal evaluation circuit 5 into digital data (serial signal) and provides it as polarity determination data (pulse polarity PP) to the counter circuit 8. Furthermore, the signal processing circuit 7 converts the output signal of the sensor element MS into digital data (serial signal) and provides it as magnetic detection data to the counter circuit 8.

[0065] The rectifier / power supply circuit 6 rectifies the pulse voltage generated by the power generation sensor 20, converting it into an appropriate voltage, and supplies it to the sensor element MS, signal evaluation circuit 5, signal processing circuit 7, and counter memory IC 10 (counter circuit 8 and non-volatile memory 9). Therefore, the sensor element MS, signal evaluation circuit 5, signal processing circuit 7, and counter memory IC 10 (counter circuit 8 and non-volatile memory 9) can operate without receiving power from an external power source. In other words, the segment counter 2 can operate using power generated by its own generator even without an external power supply. The counter memory IC 10 can receive power from the power supply circuit 3 and operate when the power supply circuit 3 is connected to an external power source.

[0066] The counter circuit 8, built into the counter memory IC 10, performs a counting operation according to a predetermined counting logic based on the polarity discrimination data (pulse polarity PP) and magnetic detection data (MS) provided by the signal processing circuit 7. This counting operation is performed regardless of whether an external power supply from the power supply circuit 3 is available. The count value obtained through this counting operation is stored in the non-volatile memory 9. This count value is retained even without a power supply (non-volatile storage). When an external power supply is provided, the counter memory 10 can provide the count value stored in the non-volatile memory 9 to the arithmetic device 4 via serial communication.

[0067] When the power supply circuit 3 is connected to an external power source, the arithmetic unit 4 receives power from the power supply circuit 3 and operates. When the external power source is on, the arithmetic unit 4 requests a precise absolute angle detection value from the precision absolute angle detector 1 and a count value from the non-volatile memory 9. The precision absolute angle detector 1 provides the precise absolute angle detection value to the arithmetic unit 4 via serial communication. The non-volatile memory 9 provides the count value to the arithmetic unit 4 via serial communication. The arithmetic unit 4 integrates the precise absolute angle detection value and the count value to generate and output a multi-rotation absolute angle detection value. The multi-rotation absolute angle detection value output by the arithmetic unit 4 is provided, for example, to a higher-level controller (not shown) and used for motor rotation control, etc.

[0068] The arithmetic unit 4 directly uses the count value provided from the non-volatile memory 9 and integrates it with the precision absolute angle detection value. That is, the count value used during integration is the value that is directly counted in the segmented timer 2 during the power-off process. The arithmetic unit 4 does not perform correction processing related to the error of the count value. Specifically, it does not perform synchronization processing to correct the error of the count value and obtain synchronization with the precision absolute angle detection value.

[0069] Figure 2A This is a perspective diagram illustrating the construction example of segment counter 2. Figure 2B This is its top view. Furthermore, Figure 2C It is along Figure 2B The front view is observed in the direction of arrow IIC. The segmented counter 2 includes a power generation sensor 20, a magnetic field source 50, and a sensor element MS (e.g., a magnetic sensor).

[0070] The power generation sensor 20 is disposed on and supported by the first support 31. In this embodiment, the first support 31 also carries a sensor element MS.

[0071] The magnetic field source 50 is fixed to the second support 32. The second support 32 is movable relative to the first support 31. Specifically, the second support 32 is coupled (fixed) to the rotation shaft 30 and rotates together with the rotation shaft 30 about the rotation axis 33. Therefore, the second support 32 can be part of a rotating body. In contrast, the first support 31 is fixed and remains in a non-rotating state. Thus, the magnetic field source 50 rotates together with the second support 32 about the rotation axis 33 and moves relative to the first support 31.

[0072] Typically, the rotating shaft 30 is rotated by a driving force from a drive shaft of an electric motor (not shown). When the motor is driven bidirectionally, the rotating shaft 30 rotates accordingly in both the counter-clockwise (CCW) and clockwise (CW) directions. The first support 31 may be a printed wiring substrate arranged along a plane orthogonal to the rotation axis 33.

[0073] The magnetic field source 50 includes k magnets M1, M2, ..., Mk (k is an integer greater than or equal to 3; in this embodiment, k = 3) positioned away from the rotation axis 33. Magnets M1, M2, ..., Mk are fixed to the second support 32 and sequentially enter the detection area SR of the power generation sensor 20 via the rotational movement of the second support 32 about the rotation axis 33. Magnets M1, M2, ..., Mk are magnetized in the detection area SR such that their magnetic poles n1, n2, ..., nk (N poles in this example) of the same polarity are opposite to the power generation sensor 20. Magnetic poles n1, n2, ..., nk move along a circular track 51 around the rotation axis 33. The configuration of the power generation sensor 20 and the magnetic field source 50 is determined such that the circular track 51 passes through the detection area SR. Magnetic poles n1, n2, ..., nk are arranged at equal intervals on the circular track 51.

[0074] The power generation sensor 20 is mounted on one main surface of the first support 31 (printed wiring substrate). The power generation sensor 20 includes a magnetic wire FE, and a first magnetic flux conducting sheet FL1 and a second magnetic flux conducting sheet FL2 magnetically coupled to both ends of the magnetic wire FE, respectively. A coil SP (induction coil) is wound around the magnetic wire FE between the first magnetic flux conducting sheet FL1 and the second magnetic flux conducting sheet FL2. The first magnetic flux conducting sheet FL1 and the second magnetic flux conducting sheet FL2 are composed of soft magnetic body components of substantially the same shape and size. More specifically, the first magnetic flux conducting sheet FL1 and the second magnetic flux conducting sheet FL2 are symmetrically configured with respect to a plane of symmetry 27 (a virtual plane used to illustrate the geometric configuration) orthogonal to the x-axis at the axial center position 25 of the magnetic wire FE (hereinafter referred to as "axial center position 25").

[0075] The magnetic conductor FE is configured to exhibit the large Backhausen effect. Specifically, the magnetic conductor FE includes a core and a skin covering the core. One of the core and the skin is a soft magnetic layer (soft magnetic layer) whose magnetization direction reverses even under a weak magnetic field, and the other of the core and the skin is a hard magnetic layer (hard magnetic layer) whose magnetization direction does not reverse unless a strong magnetic field is applied.

[0076] Each flux-conducting plate FL1, FL2 has flux-conducting ends 21, 22 opposite to the detection area SR. The magnetic conductor FE sets the axial direction x as a tangent at a point (tangent point) on the circular track 51 between the pair of flux-conducting ends 21, 22, and sets and arranges the center position 25 of the axial direction x (hereinafter referred to as "axial center position 25") on a vertical line perpendicular to the tangent at that tangent point. The coil SP generates a negative voltage pulse in a first state where the magnetic flux from the magnetic poles n1, n2, ..., Mk of magnets M1, M2, ..., Mk is conducted from the first flux-conducting plate FL1, and generates a positive voltage pulse in a second state where the magnetic flux from the magnetic poles n1, n2, ..., Mk of magnets M1, M2, ..., Mk is conducted from the second flux-conducting plate FL2.

[0077] In this embodiment, the first magnetic flux conducting sheet FL1 and the second magnetic flux conducting sheet FL2 include: axially orthogonal portions 41 extending parallel to each other in a direction orthogonal to the axial x-axis from both ends of the magnetic wire FE; and axially parallel portions 42 extending from the front end of the axially orthogonal portions 41 in a direction approaching each other along the axial x-axis. Both ends of the magnetic wire FE are respectively fixed to the base end of the axially orthogonal portions 41 of the first magnetic flux conducting sheet FL1 and the second magnetic flux conducting sheet FL2. More specifically, a wire arrangement portion 23 is provided at the base end of the axially orthogonal portion 41, which forms a hole or groove extending along the axial x-axis. Both ends of the magnetic wire FE pass through the axially orthogonal portions 41 of the first magnetic flux conducting sheet FL1 and the second magnetic flux conducting sheet FL2 in the wire arrangement portion 23 and are fixed to the axially orthogonal portions 41. For example, the magnetic wire FE is bonded and fixed to the first magnetic flux conducting sheet FL1 and the second magnetic flux conducting sheet FL2 by resin (not shown) disposed in the holes or grooves constituting the wire arrangement part 23. Thus, the two ends of the magnetic wire FE are magnetically coupled to the first magnetic flux conducting sheet FL1 and the second magnetic flux conducting sheet FL2, respectively.

[0078] The power generation sensor 20 is configured such that the side opposite to the magnetic wire FE relative to the axial parallel portion 42 is set as the detection area SR for detecting the magnetic field.

[0079] Each flux-conducting sheet FL1 and FL2, composed of soft magnetic material components, has an axially orthogonal portion 41 of approximately cuboid shape and an axially parallel portion 42 of approximately cuboid shape connected to the end portion (front end) of the detection area SR side of the axially orthogonal portion 41. Each flux-conducting sheet FL1 and FL2 has an L-shape that bends at a right angle at the junction of the axially orthogonal portion 41 and the axially parallel portion 42. The axially parallel portion 42 extends along the axial x-axis to cover the magnetic wire 110, i.e., to shield between the magnetic wire FE and the detection area SR. The first flux-conducting sheet FL1 and the second flux-conducting sheet FL2, having mutually symmetrical shapes, extend toward the axial center side of the magnetic wire FE, and their approach ends 42a are spaced apart and face each other near the axial center position 25 of the magnetic wire FE. The approach ends 42a form a plane orthogonal to the axial x-axis, and the two planes forming the two approach ends 42a are parallel to each other and face each other along the axial x-axis.

[0080] The axially parallel portions 42 of the first flux-conducting sheet FL1 and the second flux-conducting sheet FL2 form flux-conducting ends 21 and 22, which form detection area facing surfaces opposite to the detection area SR. The flux-conducting ends 21 and 22 (detection area facing surfaces) are flat surfaces parallel to the axial direction x. When a magnetic pole is positioned in the detection area SR, the flux-conducting ends 21 and 22 (detection area facing surfaces) guide the magnetic flux from that magnetic pole into the interior of the first flux-conducting sheet FL1 and the second flux-conducting sheet FL2.

[0081] The axially parallel portions 42 of the first flux-conducting sheet FL1 and the second flux-conducting sheet FL2 are joined to a wiring pattern (not shown) formed on a main surface of the first support 31 (printed wiring board), thereby surface-mounting the power generation sensor 20 onto the first support 31 (printed wiring board). The power generation sensor 20 is configured such that the axial x of the magnetic wire FE is along a tangent at a point (tangent point) on the circumference centered on the rotation axis 33, and the axial center position 25 of the magnetic wire FE coincides with this tangent point. The detection area SR of the power generation sensor 20 is located on the side opposite to the magnetic wire FE relative to the axially parallel portion 42, which in this example is the area on the other main surface side of the first support 31 (printed wiring board).

[0082] The k magnets M1, M2, ..., Mk constituting the magnetic pole generating source 50 are arranged such that magnetic poles n1, n2, ..., nk (N pole in the illustrated example) with the same polarity are opposite to the first support 31 (printed wiring board). In this example, the second support 32 is configured as an annulus surrounding the rotation axis 33. More specifically, the second support 32 is composed of an annular plate-like body, arranged along a plane orthogonal to the rotation axis 33, and parallel to the first support 31 (printed wiring board). In the second support 32, magnets M1, M2, ..., Mk are fixed to the surface of the first support 31 (printed wiring board) opposite to the other main surface mentioned above. Magnets M1, M2, ..., Mk are arranged at equal intervals around the rotation axis 33. In the specific example illustrated, three magnets M1, M2, M3 are arranged at 120-degree angular intervals around the rotation axis 33. The magnetization directions of each magnet M1, M2, ..., Mk are parallel to the rotation axis 33. Then, the magnets M1, M2, ..., Mk are fixed to the second support 32 such that the magnetic poles n1, n2, ..., nk (the N pole in the illustrated example) with the same polarity are opposite to the first support 31 (printed wiring board). The distance from the rotation axis 33 to the magnets M1, M2, ..., Mk (more specifically, the centers of the magnetic poles n1, n2, ..., nk opposite to the first support 31) is equal to the distance from the rotation axis 33 to the axial center position 25 of the magnetic conductor FE. That is, in the top view along the rotation axis 33, the magnetic conductor FE and the magnets M1, M2, ..., Mk are located on a circle with equal radius around the rotation axis 33, thus achieving a relative positional relationship in a direction parallel to the rotation axis 33. The second support 32 is preferably a yoke made of a soft magnetic material.

[0083] The magnetic poles n1, n2, ..., nk rotate together with the rotation axis 30 around the rotation axis 33, thereby moving on the circular track 51 passing through the detection area SR with the rotation axis 33 as the center. The axial direction x of the magnetic conductor FE is parallel to the tangent line passing through a point (tangent point) on the circular track 51, and the axial center position 25 is located on the perpendicular line (in this example, the perpendicular line parallel to the rotation axis 33) at that tangent point. In other words, the axial center position 25 of the magnetic conductor FE is located at a point (tangent point) on the circumference of the circle centered on the rotation axis 33 and with a radius equal to that of the circular track 51, and the magnetic conductor FE moves along the tangent line at that tangent point.

[0084] The distance between the first support 31 and the second support 32 along the rotation axis 33 is determined to be an appropriate value by which the magnetic poles n1, n2, ..., nk of the magnets M1, M2, ..., Mk can enter the detection area SR of the power generation sensor 20 through the rotation of the second support 32.

[0085] In the printed wiring board constituting the first support 31, a sensor element MS, for example a magnetic sensor, is also mounted on the main surface on which the power generation sensor 20 is mounted. In this example, the sensor element MS is positioned approximately opposite to the center position of the axial x-axis of the magnetic conductor FE. Thus, when the magnetic poles n1, n2, ..., nk are opposite the power generation sensor 20 on the circumferential track 51 between the first magnetic flux conducting plate FL1 and the second magnetic flux conducting plate FL2, the sensor element MS detects the magnetic field from the magnetic poles n1, n2, ..., nk and outputs an identification signal. Thus, the sensor element MS detects whether the magnetic poles n1, n2, ..., nk are in phase with the central portion of the power generation sensor 20 and outputs an identification signal indicating the detection result. The configuration of the sensor element MS is not limited to this. Specifically, when any one of the magnetic poles n1, n2, ..., nk is opposite the central portion of the power generation sensor 20, the sensor element MS can be positioned to detect the magnetic field from any one of the magnetic poles n1, n2, ..., nk. More specifically, ... Figure 2B Based on the configuration, the sensor element MS can be positioned at any of a plurality of positions at angular intervals of 360 degrees / k (120 degrees when k=3) around the rotation axis 33.

[0086] With this structure, whenever the magnetic poles n1, n2, ..., Mk of a magnet M1, M2, ..., Mk pass through the detection area SR along the circular track 51 by rotating counterclockwise (CCW) around the rotation axis 33, a negative pulse and a positive pulse are generated sequentially. Furthermore, whenever the magnetic poles n1, n2, ..., Mk of a magnet M1, M2, ..., Mk pass through the detection area SR along the circular track 51 by rotating clockwise (CW) around the rotation axis 33, a positive pulse and a negative pulse are generated sequentially. Then, the rotational position and direction can be identified by these pulses, as well as by the sensor element MS that outputs an identification signal when the magnets M1, M2, ..., Mk are located on the circular track 51 between the first flux-conducting plate FL1 and the second flux-conducting plate FL2.

[0087] Figures 3A to 3F This diagram illustrates the function of the power generation sensor 20 in detail. Figure 3A (Initial State) This shows the first setting state as a preparation state for outputting a negative voltage pulse. That is, the magnetization directions of both the soft and hard magnetic layers of the magnetic conductor FE are aligned with the second axis x2. In this first setting state, as... Figure 3B(TriggerNegative) As shown, if the magnetic pole n1 of magnet M1 (the N pole in the illustrated example) approaches the flux conduction end 21 of the first flux conduction plate FL1 (the opposite surface of the detection area of ​​the axial parallel portion 42), then the magnetic flux from the magnetic pole n1 is conducted out from the first flux conduction plate FL1 in the first state, thereby applying a first axial x1 operating magnetic field to the magnetic conductor FE. This results in the Big Barkhausen effect, where the magnetization direction of the soft magnetic layer reverses to the first axial x1. Subsequently, a negative voltage pulse is generated from the coil SP.

[0088] like Figure 3C As shown in (Set: Setting (Positive: Positive)), starting from the first state, if the magnetic pole n1 approaches the flux conduction end 21 of the first flux conduction plate FL1 further, the magnetic flux applied to the magnetic conductor FE along the first axis x1 is enhanced, thereby applying a stable magnetic field, and the magnetization direction of the hard magnetic layer is also reversed to the first axis x1. Thus, a second setting state is reached where the magnetization directions of both the soft and hard magnetic layers are aligned with the first axis x1. The second setting state is a preparation state for generating a positive voltage pulse.

[0089] like Figure 3E (Trigger Positive) As shown, starting from the second setting state, if the magnet M1 moves further and the magnetic pole n1 approaches the flux conduction end 22 of the second flux conduction plate FL2 (the opposite surface of the detection area of ​​the axial parallel portion 42), then the magnetic flux from the magnetic pole n1 is conducted out from the second flux conduction plate FL2 in the second state. Therefore, a second axial x2 operating magnetic field is applied to the magnetic conductor FE. This results in the Big Barkhausen effect, and the magnetization direction of the soft magnetic layer reverses to the second axial x2. Subsequently, a positive voltage pulse is generated from the coil SP.

[0090] like Figure 3F As shown in (Set: Setting (Negative: Negative)), starting from the second state, if the magnet M1 moves further and the magnetic pole n1 gets closer to the flux conduction end 22 of the second flux conduction plate FL2, the magnetic flux applied to the magnetic conductor FE along the second axis x2 is enhanced, thereby applying a stable magnetic field, and the magnetization direction of the hard magnetic layer is also reversed to the second axis x2. Thus, it returns to the first setting state (preparation state for outputting negative voltage pulses) where the magnetization directions of both the soft and hard magnetic layers are aligned with the second axis x2.

[0091] When the magnetic pole n1 moves and passes near the power generation sensor 20, the axially parallel portions 42 of the flux-conducting plates FL1 and FL2 are located between the magnetic pole n1 and the magnetic wire FE, and these axially parallel portions 42 magnetically shield the magnetic wire FE. Therefore, the magnetic flux from the magnetic pole n1 is attracted to the flux-conducting ends 21 and 22, which are opposite to the detection area of ​​the axially parallel portions 42, and enters the flux-conducting plates FL1 and FL2 from there, being guided to the end of the magnetic wire FE. Thus, an axial x-field can be applied over almost the entire axial length of the magnetic wire FE. In other words, the flux-conducting plates FL1 and FL2 are configured to have a magnetic field correction function that corrects the magnetic field formed by the magnetic pole n1 at the flux-conducting ends 21 and 22 to an axial x-field and applies this magnetic field to the magnetic wire FE.

[0092] To achieve this magnetic field correction function, such as Figure 3D As shown in (Balanced), even when magnetic pole n1 is located in the middle of a pair of flux-conducting plates FL1 and FL2, there is almost no magnetic flux directly guided from magnetic pole n1 to the axial midpoint of the magnetic wire FE. At this time, the magnetic forces conducted between the flux-conducting plates FL1 and FL2 and applied from both ends of the magnetic wire FE are balanced, so the magnetic field is not applied to the magnetic wire FE, and the magnetization direction of the magnetic wire FE does not change. Then, when reaching... Figure 3E When the soft magnetic layer is in a certain state, it simultaneously reverses and generates a pulse voltage.

[0093] Figure 4 This is a diagram illustrating the operation of the segment counter 2. In this embodiment, the segment counter 2 counts the segments obtained by dividing (typically, equally) the angular region around the rotation axis 33 into Um segments (Um being an integer of 3 or more), and generates a count value representing the counting result. Figure 4 The example shown is Um=3. Three segments are defined by three boundaries a, b, and c set at 120-degree intervals around the rotation axis 33. Boundaries a, b, and c are the boundaries through which the count value of the segment counter 2 switches in response to the voltage pulses generated by the power generation sensor 20. Specifically, boundary a corresponds to the position of magnetic pole n1 opposite to the center of the power generation sensor 20, boundary b corresponds to the position of magnetic pole n2 opposite to the center of the power generation sensor 20, and boundary c corresponds to the position of magnetic pole n3 opposite to the center of the power generation sensor 20. The count increases when each magnetic pole n1, n2, n3 crosses its position opposite to the center of the power generation sensor 20 and moves counterclockwise (CCW), and decreases when it moves clockwise (CW).

[0094] Magnetic poles n1, n2, and n3 are set at equal intervals on the circumference. Therefore, the interval between boundaries a, b, and c is 120° in terms of rotation angle. If boundary a is set as the reference angle of 0°, then boundary b is at an angle of 120° and boundary c is at an angle of 240°.

[0095] In this embodiment, the segment counter 2 is designed to count upwards when the rotation angle moves across boundaries a, b, c in the counterclockwise direction CCW, and to count downwards when the rotation angle moves across boundaries a, b, c in the clockwise direction CW. Accordingly, in the following description, the angle value about the rotation axis 33 is based on boundary a and increases in the counterclockwise direction CCW.

[0096] The magnetic field source 50 is configured to generate an alternating magnetic field with k periods (k=3 in the illustrated example) during the period when the rotation axis 30 rotates once around the rotation axis 33. More specifically, in this embodiment, k magnetic poles n1, n2, ..., nk are arranged at equal angular intervals around the rotation axis 33.

[0097] The symbols in the diagram have the following meanings: "H" represents the state where the sensor element MS detects any one of the magnetic poles n1, n2, ..., nk, i.e., any one of the magnetic poles n1, n2, ..., nk faces the center of the power generation sensor 20. "L" represents the state where the sensor element MS does not detect any one of the magnetic poles n1, n2, ..., nk, i.e., none of the magnetic poles n1, n2, ..., nk faces the center of the power generation sensor 20. These state values ​​are equivalent to the magnetic detection data generated by the signal processing circuit 7 based on the output of the sensor element MS. "P" represents the pulse polarity value of the positive pulse generated by the power generation sensor 20. "N" represents the pulse polarity value of the negative pulse generated by the power generation sensor 20. These pulse polarity values ​​are equivalent to the polarity discrimination data generated by the signal processing circuit 7 based on the output of the signal evaluation circuit 5.

[0098] The state values ​​provided from the signal processing circuit 7 to the counter circuit 8 are represented by combinations of these values, updated each time the power generation sensor 20 generates a pulse, and stored in the non-volatile memory 9. "HP" represents a state value indicating a positive pulse is generated when any one of the magnetic poles n1, n2, ..., nk faces the center of the power generation sensor 20. "LN" represents a state value indicating a negative pulse is generated when neither magnetic pole faces the center of the power generation sensor 20. "HN" represents a state value indicating a negative pulse is generated when either magnetic pole faces the center of the power generation sensor 20. "LP" represents a state value indicating a positive pulse is generated when neither magnetic pole faces the center of the power generation sensor 20.

[0099] “SET_P” indicates the angle range for the preparation state (setup state) used to generate a positive pulse. “SET_N” indicates the angle range for the preparation state (setup state) used to generate a negative pulse.

[0100] The basic operation of segment counter 2 is as follows.

[0101] When the rotation axis 30 rotates counterclockwise in the direction CCW, near the boundaries a, b, and c, which correspond to rotation angles of 0°, 120°, and 240° respectively, through Figures 3A to 3F The generator sensor 20, as shown, generates a negative pulse and a positive pulse sequentially. At this time, the state changes in the following order: state value LN (negative pulse generation) → setting state SET_P → state value HP (positive pulse generation) → setting state SET_N. The segment counter 2 increments by 1 at state value HP. That is, it increments by 1 each time the rotation angle increases through 0° (boundary a), 120° (boundary b), and 240° (boundary c).

[0102] When the rotating shaft 30 rotates clockwise in the direction CW, near the boundaries a, b, and c, which correspond to rotation angles of 0°, 120°, and 240° respectively, the direction of motion of the generated magnetic poles is... Figures 3A to 3F The generator sensor 20 operates after reversal. This generates a positive pulse and a negative pulse sequentially. At this time, it changes according to the following sequence: state value LP (positive pulse generation) → setting state SET_N → state value HN (negative pulse generation) → setting state SET_P. The segment counter 2 counts down by 1 under state value HN. That is, it counts down by 1 each time the rotation angle decreases through 0° (boundary a), 120° (boundary b), and 240° (boundary c).

[0103] Figure 5 This table illustrates a more detailed example of the counting operation of the segment counter 2. The counter circuit 8, built into the counter memory IC 10, performs the counting operation by following the logic in this table. When the generator sensor 20 generates a pulse, the state value input from the signal processing circuit 7 to the counter circuit 8 is updated. The counting operation (Count) is determined based on the combination of the updated state value (NEW) and the previous state value (OLD). The counter circuit 8 reads the previous state value (OLD) from the non-volatile memory 9 and uses it to perform the counting operation.

[0104] When the updated state value is HP, if the previous state value was any of HN, LP, or LN (i.e., if it was anything other than HP), then it is a +1 up counting action. When the updated state value is HN, if the previous state value was any of HP, LP, or LN (i.e., if it was anything other than HN), then it is a -1 down counting action.

[0105] When the updated state value is LP, it becomes a -1 downward counting action only when the previous state value was HP. When the updated state value is LN, it becomes a +1 upward counting action only when the previous state value was HN. These are exception counting actions when the output of the sensor element MS changes from a magnetic pole detection state to a magnetic pole non-detection state without a change in pulse polarity. These counting actions are performed to compensate for the effects of pulse loss described later.

[0106] For changes in state values ​​other than those mentioned above (others), the count value remains unchanged (the change in the count value is "0"). That is, when the current state value is equal to the previous state value, when the current state value is LP and the previous state value is HN or LN, and when the current state value is LN and the previous state value is HP or LP, the count value remains unchanged.

[0107] Therefore, the counter circuit 8 identifies the rotation direction and position of the rotating shaft 30 and updates the count value based on the state value, that is, the output signal of the sensor element MS and the pulse voltage generated by the power generation sensor 20, and performs an action to write the count value into the non-volatile memory 9.

[0108] Figure 6 This is a graph used to illustrate the effect of pulse loss on the count value.

[0109] Consider the case where the rotation angle moves along trajectory T1. When the rotation angle moves counterclockwise (CCW) across boundary a, thus generating a positive pulse at position 51, it becomes the state value HP (refer to...). Figure 3E If the rotation angle reaches the position where the magnetic wire FE of the power generation sensor 20 provides a stable magnetic field (refer to...). Figure 3F If the rotation direction reverses, the magnetic conductor FE will not enter the negative pulse generation preparation state (SET_N). The rotation angle crosses boundary a in the clockwise direction CW, reaching position 52 where it should become state value HN. At this time, the negative pulse that should have been generated at position 52 is not generated (pulse missing), so the state value is not updated. Afterwards, by further rotating in the clockwise direction CW, the magnetic conductor FE enters the positive pulse generation preparation state (SET_P). When the rotation angle reaches position 53, a negative pulse is generated and becomes state value LP. Therefore, if the state value changes according to HP→HN, it should become a basic -1 down counting operation, but in reality, the state value changes according to HP→LP. Therefore, an exceptional -1 down counting operation is performed (see [reference]). Figure 5 This compensates for the effects of missing pulses. The behavior is the same when the rotation direction is reversed; the state value changes from HN to LN, performing an exceptional +1 count up operation (see [reference]). Figure 5Before these exceptional counting actions are performed, the count value may contain an error of ±1.

[0110] Next, consider the case where the rotation angle moves along trajectory T2. That is, the rotation angle moves counterclockwise CCW across boundary b, thereby generating a positive pulse at position 61, which becomes the state value HP. If the rotation angle reaches the position that provides a stable magnetic field to the magnetic wire FE of the power generation sensor 20 (refer to...), Figure 3F If the rotation direction reverses, the magnetic wire FE will not enter the negative pulse generation preparation state (SET_N). The rotation angle crosses the boundary b in the clockwise direction CW, reaching position 62, which should be the state value HN. At this time, the negative pulse that should have been generated at position 62 is not generated (pulse missing), so the state value is not updated. Then, by further rotating in the clockwise direction CW, the magnetic wire FE enters the positive pulse generation preparation state (SET_P). Then, when the rotation direction reverses again, the rotation angle crosses the boundary b and moves in the counterclockwise direction CCW, generating a positive pulse again at position 61, becoming the state value HP. Therefore, if the state value changes according to HP→HN, it should become a basic -1 downward counting action, but in reality, the state value changes according to HP→HP, therefore, the count value remains unchanged. Figure 5 (The "others"). That is, although the state value changes according to HP→HP, it is not counted because it is at the same position. Therefore, in the scenario of trajectory T2, the count value of segment counter 2 may contain an error of ±1 during the period from the generation of the second state value HP until the count is ignored. The behavior is the same when the rotation direction is reversed, the state value changes according to HN→HN, and the count value remains unchanged (refer to...). Figure 5 In this case, the count value may contain an error of -1. Therefore, the count value may contain an error of ±1 before the exceptional counting action is performed.

[0111] The correct count for the angle range of one rotation (360 degrees) is "0" in the interval S0 (0 degrees to 120 degrees) between boundaries a and b, "1" in the interval S1 (120 degrees to 240 degrees) between boundaries b and c, and "2" in the interval S2 (240 degrees to 360 degrees) between boundaries b and c. In this case, when considering the counting error described above, the angle ranges A0, A1, and A2 with count values ​​of "0", "1", and "2" respectively are as follows: Figure 6 As shown. These angular ranges A0, A1, A2 are wider than the angular ranges (120 degrees) of each interval S0, S1, S2, but as... Figure 6As shown, all rotations are less than one rotation (360 degrees). Therefore, there are no regions that repeat across multiple rotations. Thus, the number of rotations per rotation unit can be determined using both the count value and the angle detection value. Specifically, the angle ranges A0, A1, and A2, where the count values ​​may be "0", "1", and "2", do not exceed the intervals S2, S1; S0, S2; and S1, S0, respectively, which are adjacent to the corresponding intervals S0, S1, and S2.

[0112] Additionally, this embodiment shows an example using a counter circuit 8, which is configured to provide a k-cycle alternating magnetic field to the magnetic conductor FE with each rotation, thereby performing k counts when 2k pulses are generated. In this case, the number of segments Um per rotation is k. However, this is just an example; for instance, a counter circuit with the following specifications can also be used: performing 2k counts during the period when 2k pulses are generated per rotation (i.e., performing +1 or -1 counts based on pulse generation). In this case, the number of segments Um per rotation is 2k. The count value is maintained when the same state value is continuous, and a count correction of +2 or -2 is performed for pulse missing. It is also possible to design a number of segments Um other than k or 2k.

[0113] Figure 7 The relationship between the count value of the segment counter 2 and the angle detection value of the precision absolute angle detector 1 is shown. The horizontal axis is the rotation angle (degrees) of the rotation axis 30, and the vertical axis is the multi-rotation absolute angle value, representing one rotation (360 degrees) with a resolution of 16 bits (65536 steps). It is assumed that the number of segments Um = k = 3. As mentioned above, Um is not necessarily equal to k; the number of segments Um can be any divisor of 2 or more of the number of pulses (2k) generated by the power generation sensor 20 per rotation, preferably a divisor of 3 or more.

[0114] As the rotating shaft 30 rotates, the angle detection value of the precision absolute angle detector 1 changes in a sawtooth wave pattern between 0 and 65536, as shown by reference numeral 61.

[0115] On the other hand, ideally, the count value of the segment counter 2 changes in a stepped manner as the rotation axis 30 rotates, as shown by reference numeral 62. For example, ideally, with 0 degrees as the reference, within each 120-degree (=360 / 3) angular interval with a central value at intervals of 120 degrees (=360 / 3), the count value becomes... -3, -2, -1, 0, 1, 2, 3... The segment counter 2 counts 3 times for every rotation, therefore, the step height for each count is 65536 / 3.

[0116] In reality, the count value of the segment counter 2, which includes the aforementioned error, may also be the same in the error regions e1 and e2 on both sides of each count value. In Patent Document 2, in order to eliminate this error range, magnetic discrimination is performed when the external power is turned on, the count value of the segment counter is corrected, and synchronized with the angle detection value of the precision absolute angle detector. In this embodiment, this correction and synchronization processing are not performed. Instead, the count value of the segment counter 2, which includes the error, is used directly, and the count value of the segment counter 2 and the angle detection value of the precision absolute angle detector 1 are integrated.

[0117] When providing specific details, such as Figure 7 As shown, when the angle detection value of the precision absolute angle detector 1 is a certain value, for example, "38299" which is equivalent to 210 degrees within the angle range of one rotation (0 degrees to 360 degrees), the count value of the segment counter 2 is checked. Across multiple rotation angle ranges, the angle detection value of the precision absolute angle detector 1, "38299" (210 degrees), represents multiple rotation angles at 360-degree intervals based on 210 degrees. That is, ... -870 degrees, -510 degrees, -150 degrees, 210 degrees, 570 degrees, 930 degrees, ... Considering counting errors, the possible count values ​​for the segment counter 2 under these multiple rotation angles are shown in the table below.

[0118] Table 1

[0119] Multiple rotation angles Count value …… …… -870 degrees -8, -7 or -6 -510 degrees -5, -4 or -3 -150 degrees -2, -1 or 0 210 degrees 1, 2 or 3 570 degrees 4, 5 or 6 930 degrees 7, 8 or 9 …… ……

[0120] Even considering errors, the range of possible count values ​​for each segment counter 2 is less than 360 degrees. Therefore, the same count value will not repeat under different multi-rotation angles. Thus, the combination of the count value from segment counter 2 and the angle detection value detected by precision absolute angle detector 1 can uniquely determine the multi-rotation absolute angle detection value. Therefore, there is no need to correct for the counting error of segment counter 2 or perform processing to synchronize the count value with the angle detection value detected by precision absolute angle detector 1; simply integrating them allows for... Figure 8 Generate multi-rotation absolute angle detection values ​​as shown.

[0121] The arithmetic unit 4 uses the count value m of the segment counter 2 and the angle detection value θ of the precision absolute angle detector 1 to perform calculations, for example, as described below, and integrates them to calculate the multi-rotation absolute angle detection value θmt. (The above...) Figure 8The calculation results are shown below. In the following formula, N represents the rotational speed (rotation amount) from the reference point (origin of rotation position) of the rotation axis 30. Uθ represents the angle detection amount per rotation (e.g., Uθ = 65536 (16 bits)), which is equivalent to the resolution of the precision absolute angle detector 1. Um (e.g., Um = k = 3) is the number of segments per rotation, which is equivalent to the number of counts per rotation of the segment counter 2.

[0122] [Mathematical Expression 1]

[0123] θmt=N×U θ +θ

[0124] N = INT(m / U) m -θ / U θ +1 / 2)

[0125] As shown in the formula above, the rotational speed N is obtained by dividing the count value m by the number of segments Um and converting it to rotational speed, then subtracting the rotation amount (θ / Uθ) equivalent to the angle detection value θ, and finally rounding it off. In the example above, rounding is performed by adding 1 / 2 and using the integerization function INT (a function that discards the decimal part to convert to an integer).

[0126] By multiplying the rotational speed N obtained in this way by the angle detection amount Uθ per rotation, the multi-rotation angle detection value relative to the count value m of the segment counter 2 can be obtained. By adding the precision angle detection value θ within one rotation, the multi-rotation absolute angle detection value θmt, representing the precision multi-rotation absolute angle, can be obtained.

[0127] In order to perform some or all of the above operations in the arithmetic unit 4, a pre-prepared table may be used as needed.

[0128] In addition, in the actual calculation of the rotational speed N, it is more convenient to use the following formula, which is equivalent to the above formula, in order to avoid the processing of values ​​after the decimal point.

[0129] [Mathematical Expression 2]

[0130]

[0131] As described above, in this embodiment, the segment counter 2 has only one power generation sensor 20 and a sensor element MS, and has a structure that applies an alternating magnetic field of more than three cycles to the magnetic wire of the power generation sensor 20 with each rotation. The count value of this segment counter 2, including errors, can be directly processed and appropriately integrated with the angle detection value generated by the precision absolute angle detector 1, thereby obtaining precise multi-rotation absolute angle detection values. Therefore, it is not necessary to use multiple power generation sensors 20, nor is it necessary to determine the magnetization direction of the magnetic wire FE of the power generation sensor 20, or to perform complex correction or synchronization processing based on this. Therefore, the structure is simplified, thereby providing a small, low-cost, and high-resolution multi-rotation precision absolute angle detection device.

[0132] Figure 9A This is a perspective view illustrating a construction example of the segmented counter 2 applied to the multi-rotation angle detection device according to other embodiments of the present invention. Figure 9B This is its top view. In these figures, for... Figure 2A , Figure 2B and Figure 2C The corresponding parts shown are labeled with the same reference number.

[0133] In this embodiment, Figure 1 In the multi-rotation angle detection device 100 with a structure, a device with a function is used. Figure 9A and Figure 9B The segmented counter 2 shown has the following structure. The main difference compared to the embodiment described above is the structure of the magnetic field generator 50. Furthermore, the configuration of the sensor element MS is also different. The first support 31 supporting the power generation sensor 20 is changed to support the sensor element MS in a way that matches the configuration of the sensor element MS. Additionally, Figure 9B The arrangement of the magnetic field source 50 is shown through a perspective view of the first support 31. The other structures of the segment counter 2 are the same as those in the above embodiment.

[0134] In this embodiment, the magnetic field source 50 is composed of a ring-shaped hexagonal magnetized magnet M surrounding the rotation axis 33. The magnetization direction is parallel to the rotation axis 33. When viewed from one direction of the rotation axis 33, the hexagonal magnetized magnet M has the following structure: on a circumference centered on the rotation axis 33, there are k pairs of magnetic poles (k is an integer greater than or equal to 3, k = 3 in the illustrated example) alternating N and S poles, and k N poles n1, n2, ..., nk and k S poles s1, s2, ..., sk. Each magnetic pole n1, n2, ..., nk; s1, s2, ..., sk spans an angular region of 360 degrees / 2k (60 degrees in this embodiment) around the rotation axis 33. Therefore, the second support 32 rotates together with the rotation axis 30, and the magnetic field source 50 rotates accordingly around the rotation axis 33, thereby applying an alternating magnetic field of k cycles (3 cycles in the illustrated example) to the power generation sensor 20.

[0135] The magnetic conductor FE of the power generation sensor 20 is located on the tangent of the circumference centered on the rotation axis 33, and the axial center position 25 of the magnetic conductor FE is located at the point of tangency of this tangent. The power generation sensor 20 is configured such that when the center of a magnetic pole n1, n2, ..., nk; s1, s2, ..., sk in an angular region spanning 360 degrees / 2k (60 degrees in this embodiment) across the rotation axis 33 matches the axial center position 25 of the magnetic conductor FE, the magnetic force conducted from the two magnetic flux conduction plates FL1, FL2 reaches equilibrium.

[0136] The sensor element MS is configured to detect the polarity of the magnetic pole opposite to the central portion of the power generation sensor 20. The sensor element MS is, for example, a magnetic sensor such as a Hall IC. When it detects the S pole (when the N pole is opposite to the central portion of the power generation sensor 20), it outputs an H signal; when it detects the N pole (when the S pole is opposite to the central portion of the power generation sensor 20), it outputs an L signal. Thus, the sensor element MS determines the polarity of the magnetic poles passing near it, and consequently, determines the polarity of the magnetic pole opposite to the central portion of the power generation sensor 20. In this embodiment, the sensor element MS is configured to detect the magnetic pole at a position 180 degrees phase-different from the power generation sensor 20 about the rotation axis 33, i.e., a position symmetrical about the rotation axis 33. When k is an odd number (e.g., 3), the sensor element MS detects a magnetic pole with the opposite polarity to the magnetic pole facing the central portion of the power generation sensor 20. When k is an even number (e.g., 4), the sensor element MS detects a magnetic pole with the same polarity as the magnetic pole facing the central portion of the power generation sensor 20. In either case, the sensor element MS can detect the polarity of the magnetic pole opposite to the central part of the power generation sensor 20.

[0137] Figures 10A to 10FAn example of operation is shown. Consider the case where the rotation axis 30 rotates counterclockwise (CCW) about the rotation axis 33. Figure 10A Observe along arrow X Figure 9B The main view is obtained from the state of the view. Figures 10B to 10F It is also the main view observed from the same perspective.

[0138] When reached Figure 10A ( Figure 9B In the state of SET_N, the hard magnetic layer and soft magnetic layer of the magnetic conductor FE are magnetized in the direction from the second flux-conducting plate FL2 towards the first flux-conducting plate 1, i.e., the setting state for generating negative pulses. At this time, the area of ​​the first flux-conducting plate FL1 facing the N and S poles is balanced with the area of ​​the second flux-conducting plate FL2 facing the N and S poles. In other words, the magnetic field generator 50, the power generation sensor 20, and their relative configuration are designed to achieve this state.

[0139] When the magnetic field source 50 and the rotating shaft 30 rotate slightly in the counterclockwise direction CCW from this state, as Figure 10B As shown, the proportion of the area of ​​the first magnetic flux conducting sheet FL1 facing the N pole increases, while the proportion of the area of ​​the second magnetic flux conducting sheet FL2 facing the N pole decreases. Consequently, a magnetic field is applied to the magnetic conductor FE from the first magnetic flux conducting sheet FL1 towards the second magnetic flux conducting sheet FL2. When the strength of this magnetic field reaches the operating magnetic field, the magnetization direction of the soft magnetic layer reverses, generating a negative voltage pulse. At this time, the sensor element MS detects the N pole (the S pole is opposite the center of the power generation sensor 20), thus generating an L signal. Therefore, the state value LN is obtained.

[0140] Furthermore, when the rotating shaft 30 rotates counterclockwise in the CCW direction, the magnetic field from the first magnetic flux conducting plate FL1 towards the second magnetic flux conducting plate FL2 further strengthens and reaches a stable magnetic field, such as... Figure 10C As shown, the magnetization direction of the hard magnetic layer of the magnetic conductor FE is also reversed, becoming a set state (SET_P) for generating positive pulses.

[0141] As the rotating shaft 30 rotates further, and from Figure 10C The state reaches the point where the CCW rotates 60 degrees counterclockwise. Figure 10D In this state, the polarity is reversed, but the operation is the same as described above. That is, the hard magnetic layer and soft magnetic layer of the magnetic conductor FE are in a state where they are magnetized in the direction from the first magnetic flux conducting sheet FL1 to the second magnetic flux conducting sheet FL2, i.e., the setting state (SET_P) for generating positive pulses. At this time, the area of ​​the first magnetic flux conducting sheet FL1 facing the N and S poles is balanced with the area of ​​the second magnetic flux conducting sheet FL2 facing the N and S poles.

[0142] When the magnetic field source 50 and the rotating shaft 30 rotate slightly in the counterclockwise direction CCW from this state, as Figure 10E As shown, the proportion of the area of ​​the first magnetic flux conducting sheet FL1 facing the N pole decreases, while the proportion of the second magnetic flux conducting sheet FL2 facing the N pole increases. Consequently, a magnetic field from the second magnetic flux conducting sheet FL2 towards the first magnetic flux conducting sheet FL1 is applied to the magnetic conductor FE. When the strength of this magnetic field reaches the operating magnetic field, the magnetization direction of the soft magnetic layer reverses, generating a positive voltage pulse. At this time, the sensor element MS detects the S pole (the N pole is opposite to the center of the power generation sensor 20), thus generating an H signal. From this, the state value HP is obtained.

[0143] Furthermore, when the rotating shaft 30 rotates counterclockwise in the CCW direction, the magnetic field from the second magnetic flux conducting plate FL2 towards the first magnetic flux conducting plate FL1 further strengthens and reaches a stable magnetic field, such as... Figure 10F As shown, the magnetization direction of the hard magnetic layer of the magnetic conductor FE is also reversed, becoming a setting state (SET_N) for generating negative pulses. When the rotating shaft 30 is further rotated 60 degrees counterclockwise in the CCW direction from this state, it becomes... Figure 10A Equal state.

[0144] Thus, one magnetic pole pair passes through the detection area of ​​the power generation sensor 20, thereby generating two pulses. The magnetic field generator 50 has k (3 in this example) magnetic pole pairs, therefore, it generates 2k (6 in this example) pulses per rotation.

[0145] By examining the clockwise rotation of CW in the same way, it can be seen that the operation of segment counter 2 becomes... Figure 11 That way. With Figure 4 In comparison, the angular positions of state values ​​LN and LP are different, but they can be directly applied. Figure 5 The counting method shown is used, and the same counting operation as in the above embodiment is performed. Therefore, by performing the same signal processing as in the above embodiment, the count value of the segment counter 2 and the angle detection value of the precision absolute angle detector 1 can be integrated to generate a precision multi-rotation absolute angle detection value. The segment boundaries a, b, and c, i.e., the boundaries of the count value switching, correspond to the angular positions of either the N pole or S pole of the magnetic pole pair relative to the center of the power generation sensor 20.

[0146] The embodiments of the present invention have been described above, but as illustrated below, the present invention may also be implemented in other ways.

[0147] The above embodiments illustrate an example of a power generation sensor 20 using L-shaped magnetic flux conduction plates FL1 and FL2, but the magnetic flux conduction plates can also be of other types. For example, an I-shaped magnetic flux conduction plate extending linearly from the magnetic wire FE toward the detection area can be used. Alternatively, a cylindrical magnetic flux conduction plate structure with coil-sized portions at both ends of the magnetic wire can also be employed.

[0148] The above embodiments mainly describe that the magnetic field generating source 50 has 3 magnets (refer to...). Figure 2A ) or 3 magnetic pole pairs (refer to) Figure 9A However, it can also be configured to have four or more magnets or four or more magnetic pole pairs, and to have a segment counter with four or more segments.

[0149] Furthermore, the precision absolute angle detector 1 does not necessarily mean a single detector; it only needs to have the function of obtaining the absolute angle within one rotation. For example, the precision absolute angle detector 1 can be constructed by multiple detectors having a detection range of less than one rotation. As an example, the angle per cycle / rotation can also be calculated by calculation based on the detection signals of the detector with 32 cycles / rotation and the detector with 31 cycles / rotation. In this case, the calculation is also performed by the calculation device 4.

[0150] Although the embodiments of the present invention have been described in detail, these are merely specific examples used to illustrate the technical content of the present invention. The present invention should not be construed as being limited to these specific examples, and the scope of the present invention is limited only by the appended claims.

[0151] Label Explanation

[0152] 1. Precision absolute angle detector

[0153] 2. Segment Counter

[0154] 3 Power supply circuit

[0155] 4. Computing device

[0156] 5. Signal Evaluation Circuit

[0157] 6. Rectifier / Power Supply Circuit

[0158] 7. Signal Processing Circuit

[0159] 8. Counter Circuit

[0160] 9. Non-volatile memory

[0161] 10-counter memory IC

[0162] 20 Power Generation Sensor

[0163] 30 Rotation axis

[0164] 31 First Support

[0165] 32 Second Support

[0166] 33. Axis of rotation

[0167] 50 Magnetic field generators

[0168] 100+ rotation angle detection device

[0169] FE magnetic wire

[0170] FL1 first flux conduction plate

[0171] FL1 second flux conduction plate

[0172] M 6-pole magnetized magnet

[0173] Magnets M1, M2, and M3

[0174] MS sensor element

[0175] SP coil

[0176] SR detection area

[0177] n1, n2, n3 N poles

[0178] s1, s2, s3 S pole.

Claims

1. A multi-rotation angle detecting device, A multi-rotation absolute angle detection value of a rotating body rotating around a rotation axis is generated, characterized in that comprising: a segment counter that counts segments divided after a one-rotation period of a rotating body in an angle region exceeding one rotation of the rotating body according to rotation of the rotating body, and generates a count value; a fine absolute angle detector that operates by supply of power from outside, and generates an absolute angle detection value within the one-rotation period of the rotating body at a higher resolution than the segments; and an arithmetic device that operates by supply of power from outside, integrates the count value of the segment counter and the absolute angle detection value of the fine absolute angle detector, and generates a multi-rotation absolute angle detection value of the rotating body, the segment counter including a power generation sensor, a magnetic field generating source that rotates together with the rotating body around the rotation axis, a sensor element different from the power generation sensor, and a nonvolatile memory that stores the count value, the power generation sensor having a magnetic conductor that exhibits a large Barkhausen effect and a coil wound around the magnetic conductor, and generating a pulse voltage by a change in magnetic field accompanying rotation of the magnetic field generating source, the magnetic field generating source applying an alternating magnetic field of k periods to the axial direction of the magnetic conductor at each one rotation of the rotating body, where k is an integer of 3 or more, the segment counter being able to operate by energy of the pulse voltage generated by the power generation sensor without accepting supply of power from outside, and using the pulse voltage generated by the power generation sensor and an output signal of the sensor element to recognize a rotation direction and a rotation position of the rotating body, update the count value, and store in the nonvolatile memory, the arithmetic device directly using the count value stored in the nonvolatile memory when accepting supply of power from outside, integrating the count value of the segment counter and the absolute angle detection value of the fine absolute angle detector, and generating the multi-rotation absolute angle detection value of the rotating body.

2. The multi-rotation angle detecting device according to claim 1, wherein the magnetic field generating source includes k magnets arranged with the same polarity facing the power generation sensor on a circumference centered on the rotation axis, the magnetic conductor of the power generation sensor is disposed in parallel with a tangent line of the circumference, the power generation sensor has a first magnetic flux conducting sheet and a second magnetic flux conducting sheet that are respectively magnetically coupled to both end portions of the magnetic conductor, the poles sequentially approach the first magnetic flux conducting sheet and the second magnetic flux conducting sheet with rotation of the magnetic field generating source, the power generation sensor generates a negative voltage pulse in a first state in which magnetic flux from the poles of the magnetic field generating source is conducted from the first magnetic flux conducting sheet, and generates a positive voltage pulse in a second state in which magnetic flux from the magnetic field generating source is conducted from the second magnetic flux conducting sheet.

3. The multi-rotation angle detecting device according to claim 1 or 2, wherein The sensor element detects whether a magnetic pole of the magnetic field generating source exists at a position opposite to the central portion of the power generation sensor, and the boundary of the segments is an angular position at which the magnetic pole opposes the central portion of the power generation sensor.

4. The multi-rotation angle detection device according to claim 1, wherein The magnetic field generating source includes k pairs of magnetic poles obtained by alternately arranging N poles and S poles on a circumference centered on the rotation axis.

5. The multi-rotation angle detection device according to claim 4, wherein The magnetic wire of the power generation sensor is located on a tangent line of the circumference centered on the rotation axis, and a center of the magnetic wire is located on a tangent point of the tangent line.

6. The multi-rotation angle detection device according to claim 4 or 5, wherein The sensor element detects a polarity of a magnetic pole opposing the central portion of the power generation sensor, and the boundary of the segments is an angular position at which either of an N pole and an S pole of the magnetic pole pair opposes the central portion of the power generation sensor.

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