JP7572471B2 - Multi-rotation angle detection device and segment counter therefor - Google Patents

Description

This invention relates to a multi-rotation angle detection device that uses a power generation sensor. More specifically, this invention relates to a device that detects a multi-rotation absolute angle exceeding one rotation by integrating the count value of a segment counter that uses a power generation sensor with an angle detection value obtained from an angle detector that precisely detects the absolute angle in one rotation period. Furthermore, this invention relates to a segment counter for a multi-rotation angle detection device.

Magnetic wire with a large Barkhausen effect (large Barkhausen jump) is known as Wiegand wire or pulse wire. This magnetic wire has a core and a skin surrounding the core. One of the core and skin is a soft (soft magnetic) layer in which the magnetization direction is reversed even in a weak magnetic field, while the other is a hard (hard magnetic) layer in which the magnetization direction does not reverse unless a strong magnetic field is applied. A power generating sensor can be constructed by winding a coil around such a magnetic wire.

When the hard layer and soft layer are magnetized in the same direction along the axial direction of the wire, if the strength of the external magnetic field in the opposite direction to the magnetization direction increases and reaches a certain magnetic field strength, the magnetization direction of the soft layer is reversed. This reversal of the magnetization direction starts at a certain part of the magnetic wire and propagates throughout the entire wire, causing the magnetization direction of the soft layers to reverse simultaneously. At this time, the large Barkhausen effect is manifested, and a pulse signal is induced in the coil wound around the magnetic wire. If the external magnetic field strength increases further and reaches a certain magnetic field strength, the magnetization direction of the hard layer is reversed.

In this specification, the magnetic field strength when the magnetization direction of the soft layer is reversed is called the "operating magnetic field," and the magnetic field strength when the magnetization direction of the hard layer is reversed is called the "stabilizing magnetic field."

The output voltage obtained from the coil is constant regardless of the speed at which the input magnetic field (external magnetic field) changes, and has hysteresis characteristics with respect to the input magnetic field, so there is no chattering. For this reason, the pulse signal generated by the coil is used in position detection devices, etc.

When an alternating magnetic field is applied to the power generating sensor, two pulse signals are generated per cycle: one positive pulse signal and one negative pulse signal. A magnet is used as the source of the magnetic field, and an alternating magnetic field is applied to the power generating sensor due to the relative movement between the magnet and the power generating sensor. The position can be detected by counting the generated pulse signals.

Because the output from the coil is electric, it is possible to create a power-generating sensor (power-generating sensor) that does not require an external power supply. In other words, the output energy from the coil can also be used to operate peripheral circuits without an external power supply.

Angle sensors such as absolute encoders are essentially unable to detect angles that exceed one rotation. When power is supplied, it is possible to detect angles of more than one rotation by integrating the amount of movement, but when the power is cut off, information of more than one rotation is lost.

On the other hand, segment counters that use power generation sensors can continue counting even when the external power supply is cut off because they can use the output energy of the coil, making it possible to detect multiple rotations of more than one. However, segment counters that use power generation sensors can generally only detect rough angles. Therefore, when precise angle detection is required, such as when used for motor control, the count value of the segment counter is combined with the angle detection value of a separately installed precision absolute angle detector, and a precise angle detection value over multiple rotations (multiple rotation absolute angle detection value) is used.

Patent Document 1 and Patent Document 2 disclose a method and device for integrating the count value of a segment counter with the angle detection value of a precision absolute angle detector.

Patent document 1 uses a segment counter in which three power generation sensors are positioned with a phase difference of 60 degrees each.

The output of only one power generating sensor cannot identify the direction of movement if the direction of movement changes. Therefore, by using multiple power generating sensors and using the phase difference between the outputs of each power generating sensor, the direction of movement can be identified.

In order for the power generating sensor to output a pulse voltage, it is necessary for the magnetization direction of only the soft layer to reverse from a state in which the magnetization directions of the hard and soft layers of the magnetic wire are aligned. Even if the magnetization direction of only the soft layer reverses when the magnetization directions of the hard and soft layers are not aligned, no pulse signal will be generated, or if one is generated, it will be very small.

When rotation continues in one direction, after the operating magnetic field is reached and a pulse voltage is output, there is a timing when the stabilizing magnetic field is reached before the operating magnetic field is reached again. Therefore, a pulse voltage is always generated at the angular position where the operating magnetic field is reached.

However, when rotating in both directions, i.e. when the direction of rotation is switched, the pulse voltage is not output even when the operating magnetic field is reached, and so-called pulse missing can occur. Specifically, if the direction of rotation is reversed after the operating magnetic field is reached and the pulse voltage is output before the stabilizing magnetic field is reached, the magnetization directions of the hard layer and soft layer do not match, so the pulse voltage is not output even when the operating magnetic field is reached again.

By arranging multiple power generation sensors at positions with different phase differences and using the phase difference between their output pulses, the direction of rotation can be identified. However, even if two power generation sensors are used, if one of them is missing a pulse, the direction of rotation cannot be identified. Therefore, as disclosed in Patent Document 1, it is necessary to use three power generation sensors. Patent Document 1 also arranges the three power generation sensors at positions with a phase difference of 60 degrees each in order to integrate the count value of the segment counter and the detection value of the precision position detector and to correct the deviation of the origin position.

However, using multiple power generation sensors increases the size and cost of the position detector.

Patent Document 2 discloses a segment counter that determines the direction of rotation by processing the pulse signal of one power generation sensor and the output signal of another sensor element that is not a power generation sensor, and performs counting operations accordingly. Even in this case, if the aforementioned missing pulse occurs, there is an inconvenience when integrating the count value of the segment counter and the detection value of the precision position detector. Therefore, Patent Document 2 monitors the magnetization state of the magnetic wire of the power generation sensor, and corrects the value of the segment counter by the amount of the missing pulse voltage depending on the magnetization state. This synchronizes the count value of the segment counter with the detection value of the precision position detector, and integrates them.

Specifically, the magnetization state monitor disclosed in Patent Document 2 applies a gradually increasing current to the coil of the power generation sensor, and applies the magnetic field generated by the coil to the magnetic wire. The voltage generated at both ends of the coil is then observed to monitor whether the magnetization direction of the magnetic wire is reversed. This makes it possible to check the magnetization state of the magnetic wire.

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

Patent No. 6226811 Patent No. 5730809

One embodiment of the present invention provides a multi-rotation angle detection device that is advantageous in terms of miniaturization and cost reduction.

More specifically, one embodiment of the present invention provides a multi-rotation angle detection device that can generate a multi-rotation absolute angle detection value by integrating the count value of a segment counter configured without using multiple power generation sensors and the angle detection value of a precision absolute angle detector without requiring complex signal processing.

An embodiment of the present invention also provides a segment counter that counts segments using a novel algorithm and a multi-rotation angle detection device equipped with the same.

One embodiment of the present invention provides a rotation angle detection device and a segment counter having the following features:

1. A multiple rotation angle detection device that generates a multiple rotation absolute angle detection value of a rotating body that rotates around a rotation axis, comprising:
a segment counter that generates a count value by counting segments obtained by dividing one rotation period of the rotor in an angle range exceeding one rotation of the rotor in response to rotation of the rotor;
a precision absolute angle detector that is operated by an external power supply and generates an absolute angle detection value within one rotation period of the rotating body with a resolution higher than that of the segment;
a calculation device that operates by an external power supply and that integrates the count value of the segment counter and the absolute angle detection value of the precision absolute angle detector to generate a multiple rotation absolute angle detection value of the rotating body,
the segment counter includes one power generation sensor, a magnetic field generating source that rotates together with the rotor about the rotation axis, a sensor element other than the power generation sensor, and a non-volatile memory that stores the count value;
the power generation sensor has a magnetic wire that exhibits the large Barkhausen effect and a coil wound around the magnetic wire, and generates a pulse voltage in response to a change in a magnetic field caused by rotation of the magnetic field generation source;
the magnetic field generating source applies an alternating magnetic field having two or more periods per rotation of the rotor in the axial direction of the magnetic wire;
The segment counter can operate by the energy of the pulse voltage generated by the power generating sensor without receiving an external power supply, and when the power generating sensor generates a pulse voltage, the segment counter identifies a rotation direction and a rotation position of the rotating body using the polarity of the pulse voltage (hereinafter referred to as the "polarity of the current pulse voltage"), the output state of the sensor element when the pulse voltage was generated (hereinafter referred to as the "current sensor element state"), the polarity of the previous pulse voltage, the output state of the sensor element when the previous pulse voltage was generated (hereinafter referred to as the "previous sensor element state"), and a count value updated by the generation of the previous pulse voltage and stored in the nonvolatile memory (hereinafter referred to as the "previous count value"), and updates the count value and stores it in the nonvolatile memory;
The segment counter is
identifying a rotation direction of the rotor based on a combination of the polarity of the current pulse voltage and the current state of the sensor element, and determining a sign of the count amount;
When the polarity of the current pulse voltage is different from the polarity of the previous pulse voltage, the absolute value of the count amount is set to 1;
when the polarity of the current pulse voltage is the same as the polarity of the previous pulse voltage and the current sensor element state is the same as the previous sensor element state, the absolute value of the count amount is set to 0;
when the polarity of the current pulse voltage is the same as the polarity of the previous pulse voltage and the current sensor element state is different from the previous sensor element state, the absolute value of the count amount is set to 2;
updating the count value by adding the count value obtained by applying the determined sign to the absolute value of the count value to the previous count value;
When the arithmetic device receives an external power supply, it uses the count value stored in the non-volatile memory as is, and integrates the count value of the segment counter and the absolute angle detection value of the precision absolute angle detector to generate a multi-rotation absolute angle detection value of the rotating body.

According to this configuration, the magnetic field generating source rotates around the axis of rotation together with the rotor, and the magnetic field generating source applies an alternating magnetic field of two or more periods per rotation to the magnetic wire in the axial direction. As a result, the power generating sensor generates four or more pulse voltages per rotation. As a result, the segment counter can generate a count value by counting the segments into which one rotation period is divided, for example, into four or more. Even if a pulse is dropped due to a reversal of the direction of rotation and a count error occurs accordingly, the error is not so large that the count value is the same over an angle range of one rotation or more. In this way, an alternating magnetic field of two or more periods per rotation is applied to the magnetic wire, and the magnetic wire generates four or more pulse voltages per rotation, so that a precise multi-rotation absolute angle value can be uniquely determined from the combination of the count value of the segment counter and the absolute angle detection value of the precision absolute angle detector at any multi-rotation absolute angle. In other words, even if the count value of the segment counter contains an error, the count value can be integrated with the angle detection value of the precision absolute angle detector without performing any correction process on the count value (i.e., the count value can be used as is).

In this way, a precise multi-rotation absolute angle detection value can be generated by combining the count value of the segment counter and the angle detection value of the precision absolute angle detector using only one power generation sensor, without the need to perform magnetization direction determination processing of the magnetic wire or correction/synchronization processing based on that.

In this embodiment, the segment counter performs counting operations in response to all pulse voltages generated by the power generation sensor, and operates according to a novel algorithm that compensates for missing pulses. In other words, the segment counter identifies the direction of rotation of the rotor based on a combination of the polarity of the current pulse voltage and the current state of the sensor element, and determines the sign of the count amount.

When the rotor rotates in one direction, the polarity of the pulse voltage alternates, so if the polarity of the pulse voltage is reversed, it means that an angular displacement across a segment has occurred. Therefore, the segment counter sets the absolute value of the count to 1 when the polarity of the current pulse voltage is different from the polarity of the previous pulse voltage.

When the direction of rotation is reversed, a missing pulse may occur, resulting in a series of pulse voltages of the same polarity and the same sensor element state. In this case, it is appropriate to leave the count unchanged since it can be considered that the same angular position has been returned to. Therefore, the segment counter sets the absolute value of the count to 0 when the polarity of the current pulse voltage is the same as the previous pulse voltage and the current sensor element state is the same as the previous sensor element state.

In addition, a missing pulse may occur due to a reversal of the direction of rotation, resulting in a series of pulse voltages of the same polarity, while the sensor element state may change. In this case, it can be considered that the segment boundary has been crossed twice. Therefore, the segment counter sets the absolute value of the count to 2 when the polarity of the current pulse voltage is the same as the polarity of the previous pulse voltage, and the current sensor element state is different from the previous sensor element state.

The segment counter calculates the count amount by adding the determined sign to the absolute value of the count amount thus calculated, and updates the count value by adding the count amount to the previous count value.

In this way, counting operations are performed according to all pulse voltages generated by the power generation sensor, and missing pulses can be compensated for. Because missing pulses are compensated for by generating pulse voltages, the count value of the segment counter may contain an error. Even in such cases, as mentioned above, the count value of the segment counter can be used as is and integrated with the absolute angle detection value.

2. The multi-rotation angle detection device described in paragraph 1, in which, when the power generation sensor generates a pulse voltage, the segment counter stores in the non-volatile memory the polarity of the pulse voltage and the output state of the sensor element when the pulse voltage is generated.

This allows the segment counter to obtain information on the polarity of the previous pulse voltage and the state of the sensor element from the non-volatile memory and perform the counting operation described above.

3. The multi-rotation angle detection device described in paragraph 1 or 2, in which the segment counter counts segments obtained by dividing one rotation period of the rotating body into four or more segments.

With this configuration, the segment counter can count four or more segments per revolution. Typically, the number of segments is 2k when the magnetic field source applies an alternating magnetic field to the magnetic wire with k periods (k ≥ 2) per revolution of the rotor.

4. The multi-rotation angle detection device according to any one of claims 1 to 3, wherein the magnetic field source includes two or more magnetic pole pairs in which north and south poles are arranged alternately on a circumference having a center on the rotation axis.

For example, consider an initial state in which the soft and hard layers of the magnetic wire are magnetized in a set state (set state for generating a negative pulse) in a direction from the first end to the second end of the magnetic wire, one S pole faces the center of the power generation sensor, and the magnetic flux from a pair of N poles on both sides of the S pole is balanced. When the magnetic field generating source rotates a little from this initial state together with the rotor, the magnetic flux from the first end to the second end of the magnetic wire increases, reaching the operating magnetic field, the magnetization direction of the soft layer of the magnetic wire is reversed, and a negative pulse is generated. When the magnetic field generating source rotates further together with the rotor, the magnetic flux from the first end to the second end of the magnetic wire increases further and reaches the stabilizing magnetic field, the magnetization direction of the hard layer is also reversed, and the magnetic wire is in a set state for generating a positive pulse. When the magnetic field generating source rotates further, the magnetic flux from the second end to the first end of the magnetic wire increases, reaching the operating magnetic field, the magnetization direction of the soft layer of the magnetic wire is reversed, and a positive pulse is generated. As the magnetic field source continues to rotate, the magnetic flux from the second end of the magnetic wire to the first end increases further and reaches a stabilizing magnetic field, the magnetization direction of the hard layer also reverses, and the magnetic wire enters a set state for generating a negative pulse. Thus, two pulses are generated when one magnetic pole pair passes through the detection area of the power generation sensor.

If the magnetic field source includes k (k ≧ 2) magnetic pole pairs with alternating north and south poles arranged on a circumference centered on the axis of rotation, k periods of alternating magnetic field are applied to the magnetic wire per rotation of the rotor, and accordingly, 2k pulses are generated.

5. The multi-rotation angle detection device described in item 4, in which the magnetic wire of the power generation sensor is on a tangent to a circumference having a center on the rotation axis, and the center of the magnetic wire is on the tangent point of the tangent.

This configuration allows the magnetic field source and the magnetic wire to be appropriately magnetically coupled, and allows an alternating magnetic field to be appropriately applied to the magnetic wire as the rotor rotates.

6. The multi-rotation angle detection device described in paragraph 5, in which the power generation sensor has a first magnetic flux conducting piece and a second magnetic flux conducting piece that are magnetically coupled to both ends of the magnetic wire.

In this configuration, a first magnetic flux conducting piece is magnetically coupled to a first end of the magnetic wire, and a second magnetic flux conducting piece is magnetically coupled to a second end of the magnetic wire. This strengthens the magnetic coupling between the magnetic field generating source and the magnetic wire, and allows a strong magnetic field to be applied in the axial direction of the magnetic wire to generate a good pulse voltage.

7. The multi-rotation angle detection device according to any one of claims 4 to 6, wherein the sensor element detects the polarity of the magnetic pole facing the center of the power generation sensor.

In this case, the boundary of the segment may be an angular position where one of the north pole and the south pole of the magnetic pole pair faces the center of the power generation sensor. The boundary of the segment is a boundary where the count value of the segment counter changes.

8. A segment counter that generates a count value by counting segments obtained by dividing one rotation period of a rotor that rotates about a rotation axis of the rotor in an angle range exceeding one rotation of the rotor,
a power generation sensor, a magnetic field generating source rotating about the rotation axis together with the rotor, a sensor element other than the power generation sensor, a non-volatile memory that stores the count value, and a counter circuit that updates the count value,
the power generation sensor has a magnetic wire that exhibits the large Barkhausen effect and a coil wound around the magnetic wire, and generates a pulse voltage in response to a change in a magnetic field caused by rotation of the magnetic field generation source;
the magnetic field generating source applies an alternating magnetic field having two or more periods per rotation of the rotor in the axial direction of the magnetic wire;
When the power generation sensor generates a pulse voltage, the counter circuit uses the polarity of the pulse voltage (hereinafter referred to as the "polarity of the current pulse voltage"), the output state of the sensor element when the pulse voltage was generated (hereinafter referred to as the "current sensor element state"), the polarity of the previous pulse voltage, the output state of the sensor element when the previous pulse voltage was generated (hereinafter referred to as the "previous sensor element state"), and a count value updated by the generation of the previous pulse voltage and stored in the nonvolatile memory (hereinafter referred to as the "previous count value") to identify the rotation direction and rotation position of the rotating body, update the count value, and store it in the nonvolatile memory;
The counter circuit includes:
identifying a rotation direction of the rotor based on a combination of the polarity of the current pulse voltage and the current state of the sensor element, and determining a sign of the count amount;
When the polarity of the current pulse voltage is different from the polarity of the previous pulse voltage, the absolute value of the count amount is set to 1;
when the polarity of the current pulse voltage is the same as the polarity of the previous pulse voltage and the current sensor element state is the same as the previous sensor element state, the absolute value of the count amount is set to 0;
when the polarity of the current pulse voltage is the same as the polarity of the previous pulse voltage and the current sensor element state is different from the previous sensor element state, the absolute value of the count amount is set to 2;
updating the count value by adding the count value obtained by applying the determined sign to the absolute value of the count value to the previous count value;
Segment counter.

According to this invention, the count value of a segment counter configured without using multiple power generation sensors and the angle detection value of a precision absolute angle detector can be integrated to generate a multi-rotation absolute angle detection value without requiring complex signal processing. This makes it possible to provide a multi-rotation angle detection device that is advantageous in terms of size and cost reduction.

The present invention also provides a segment counter that counts segments using a new algorithm and a multi-rotation angle detection device equipped with the same.

FIG. 1 is a block diagram for explaining an example of the configuration of a multiple rotation angle detection device according to an embodiment of the present invention. Fig. 2A is a perspective view for explaining a structural example of a segment counter, Fig. 2B is a plan view thereof, and Fig. 2C is a front view seen in the direction of the arrow IIC in Fig. 2B. 3A, 3B and 3C are operation explanatory diagrams for explaining the function of the power generation sensor. 3D, 3E and 3F are operation explanatory diagrams for explaining the function of the power generation sensor. FIG. 4 is a diagram for explaining the counting operation of the segment counter. FIG. 5 is a table for explaining an example of a more detailed counting operation of the segment counter. FIG. 6 is a diagram for explaining the effect of a missing pulse on the count value. FIG. 7 shows the relationship between the count value of the segment counter and the angle detection value of the precision absolute angle detector. FIG. 8 shows the relationship between the count value of the segment counter and the angle detection value of the precision absolute angle detector. FIG. 9 shows a precision multi-rotation absolute angle detection value obtained by integrating the count value of the segment counter and the angle detection value of the precision absolute angle detector. FIG. 10 is a diagram for explaining an example of calculation of the number of rotations based on the count value of the segment counter.

The following describes in detail an embodiment of the present invention with reference to the attached drawings.

Figure 1 is a block diagram for explaining an example of the configuration 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 the multi-rotation absolute angle of a rotating shaft 30 (an example of a rotating body) rotating around a rotation axis 33, and generates a multi-rotation absolute angle detection value that is the detected value. The multi-rotation absolute angle is an absolute angle within an angle range that exceeds one rotation, i.e., spans multiple rotations. The multi-rotation angle detection device 100 includes a precision absolute angle detector 1, a segment counter 2, and a calculation device 4.

The precision absolute angle detector 1 is an angle sensor that generates a precise absolute angle detection value within one rotation period of the rotating shaft 30, i.e., from 0 degrees to 360 degrees, with a higher resolution than the segment counter 2, which will be described next. The precision absolute angle detector 1 is, for example, composed of an optical absolute encoder. The precision absolute angle detector 1 is configured to generate an absolute angle detection value in the angle range within one rotation period (0 degrees to 360 degrees) with a resolution of 16 bits (65,536 steps).

The precision absolute angle detector 1 typically 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 connected to an external power source, the power supply circuit 3 supplies power to the precision absolute angle detector 1, and the precision absolute angle detector 1 operates by receiving that power. The precision absolute angle detector 1 inputs a 16-bit absolute angle detection value to the calculation device 4, for example, by serial communication.

The segment counter 2 counts the segments into which one rotation period of the rotating shaft 30 is divided (divided into equal parts) according to the rotation of the rotating shaft 30, and generates a count value that represents the angle value of each segment in an angle range that spans multiple rotations of the rotating shaft 30 (more than one rotation).

The segment counter 2 includes one (only one) power generation sensor 20, a magnetic field generating source 50 that rotates around the rotation axis 33 together with the rotating shaft 30, a sensor element MS (not a power generation sensor) separate from the power generation sensor 20, a counter circuit 8, and a non-volatile memory 9 that stores the count value. The non-volatile memory 9 may be composed of FeRAM (ferroelectric random access memory). In this embodiment, the counter circuit 8 and the non-volatile memory 9 are incorporated into one counter memory IC (integrated circuit) 10. The segment counter 2 further includes a signal evaluation circuit 5, a rectification/power supply circuit 6, and a signal processing circuit 7.

The power generation sensor 20 generates a pulse voltage in response to changes in the magnetic field caused by the rotation of the magnetic field generating source 50. In this embodiment, the sensor element MS is a magnetic sensor that detects the magnetic field of the magnetic field generating source 50 in response to the rotation of the magnetic field generating source 50. 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 supplies a signal (pulse polarity PP) representing the result of the polarity determination to the signal processing circuit 7. The signal processing circuit 7 converts the signal representing the result of the polarity determination received from the signal evaluation circuit 5 into digital data (serial signal) and supplies it to the counter circuit 8 as polarity determination data (pulse polarity PP). The signal processing circuit 7 also converts the output signal of the sensor element MS into digital data (serial signal) and supplies it to the counter circuit 8 as magnetic detection data.

The rectifier/power supply circuit 6 rectifies the pulse voltage generated by the power generation sensor 20, converts it into an appropriate voltage, and supplies it to the sensor element MS, the signal evaluation circuit 5, the signal processing circuit 7, and the counter memory IC 10 (counter circuit 8 and non-volatile memory 9). Therefore, the sensor element MS, the signal evaluation circuit 5, the signal processing circuit 7, and the 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 operates with power generated by self-generation even when there is no external power supply. The counter memory IC 10 can operate with power supplied from the power supply circuit 3 when the power supply circuit 3 is connected to an external power source.

The counter circuit 8 built into the counter memory IC 10 executes a counting operation according to a predetermined counting logic based on the polarity discrimination data (pulse polarity PP) and magnetic detection data (MS) supplied from the signal processing circuit 7. This counting operation is executed regardless of whether or not external power is being supplied from the power supply circuit 3. The count value obtained by this counting operation is stored in the non-volatile memory 9. This count value is saved even when there is no power supply (non-volatile storage). When an external power supply is being supplied, the counter memory IC 10 can supply the count value stored in the non-volatile memory 9 to the calculation device 4 via serial communication.

When the power supply circuit 3 is connected to an external power supply, the arithmetic device 4 receives power from the power supply circuit 3 to operate. When the external power supply is turned on, the arithmetic device 4 requests a precision absolute angle detection value from the precision absolute angle detector 1 and also requests a count value from the non-volatile memory 9. The precision absolute angle detector 1 supplies the precision absolute angle detection value to the arithmetic device 4 by serial communication. The non-volatile memory 9 supplies the count value to the arithmetic device 4 by serial communication. The arithmetic device 4 integrates the precision 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 device 4 is supplied to, for example, a higher-level controller (not shown) and used for controlling the rotation of an electric motor, etc.

The calculation device 4 uses the count value supplied from the non-volatile memory 9 as is and integrates it with the precision absolute angle detection value. In other words, the count value used during integration is the value that was counted in the segment counter 2 while the power was cut off, and the calculation device 4 does not perform any correction process for the error in the count value, specifically, any synchronization process for correcting the error in the count value and synchronizing it with the precision absolute angle detection value.

Figure 2A is a perspective view for explaining an example of the structure of the segment counter 2, and Figure 2B is a plan view thereof. Also, Figure 2C is a front view seen in the direction of the arrow IIC in Figure 2B. The segment counter 2 includes a power generation sensor 20, a magnetic field generation source 50, and a sensor element MS (e.g., a magnetic sensor).

The power generation sensor 20 is disposed on the first support 31 and is supported by the first support 31. In this embodiment, the sensor element MS is also mounted on the first support 31.

The magnetic field generating source 50 is fixed to the second support 32. The second support 32 moves relative to the first support 31. Specifically, the second support 32 is coupled (fixed) to the rotating shaft 30 and rotates together with the rotating shaft 30 around the rotation axis 33. Therefore, the second support 32 can be a part of a rotating body. In contrast, the first support 31 is fixedly disposed and held in a non-rotating state. As a result, the magnetic field generating source 50 rotates together with the second support 32 around the rotation axis 33 and moves relative to the first support 31.

The rotating shaft 30 is typically rotated by a driving force from a drive shaft of an electric motor (not shown). When the electric motor is driven in both directions, the rotating shaft 30 rotates in both counterclockwise and clockwise directions accordingly. The first support 31 may be a printed circuit board arranged along a plane perpendicular to the rotation axis 33.

The magnetic field generating source 50 is composed of a ring-shaped four-pole 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 four-pole magnetized magnet M has a configuration in which k (k is an integer of 2 or more. In the illustrated example, k=2) magnetic pole pairs (pairs of N and S poles) are arranged in alternating order on a circumference centered on the rotation axis 33, and has 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 (90 degrees in this embodiment) around the rotation axis 33. Therefore, the second support 32 rotates together with the rotating shaft 30, and the magnetic field source 50 rotates accordingly around the rotation axis 33, so that an alternating magnetic field of k periods (two periods in the illustrated example) is applied to the power generation sensor 20.

The power generation sensor 20 is mounted on one main surface of the first support 31 (printed wiring board). The power generation sensor 20 includes a magnetic wire FE and a first magnetic flux conducting piece FL1 and a second magnetic flux conducting piece FL2 that are magnetically coupled to both ends of the magnetic wire FE. A coil SP (induction coil) is wound around the magnetic wire FE between the first magnetic flux conducting piece FL1 and the second magnetic flux conducting piece FL2. The first magnetic flux conducting piece FL1 and the second magnetic flux conducting piece FL2 are made of soft magnetic material parts of substantially the same shape and size. More specifically, the first magnetic flux conducting piece FL1 and the second magnetic flux conducting piece FL2 are configured symmetrically with respect to a symmetry plane 27 (a virtual plane for explaining the geometric arrangement) perpendicular to the axial direction x at the axial center position 25 (hereinafter referred to as the "axial center position 25") of the magnetic wire FE.

The magnetic wire FE is configured to exhibit the large Barkhausen effect. Specifically, the magnetic wire FE has a core and a skin covering it. One of the core and skin is a soft layer (soft magnetic layer) in which the magnetization direction is reversed even in a weak magnetic field, and the other of the core and skin is a hard layer (hard magnetic layer) in which the magnetization direction does not reverse unless a strong magnetic field is applied.

Each of the magnetic flux conducting pieces FL1, FL2 has a magnetic flux conducting end 21, 22 facing the detection region SR. The magnetic wire FE of the power generation sensor 20 is on a tangent to a circumference having a center on the rotation axis 33, and the axial center position 25 of the magnetic wire FE is on the tangent point of the tangent. The power generation sensor 20 is arranged so that the magnetic fields conducted from the two magnetic flux conducting pieces FL1, FL2 are balanced when the center of one magnetic pole n1, n2, ..., nk; s1, s2, ..., sk over an angular region of 360 degrees/2k (90 degrees in this embodiment) around the rotation axis 33 is aligned with the axial center position 25 of the magnetic wire FE. Coil SP generates a negative voltage pulse in the first state when magnetic flux from N poles n1, n2, ..., nk is conducted from first magnetic flux conducting piece FL1, and generates a positive voltage pulse in the second state when magnetic flux from N poles n1, n2, ..., nk is conducted from second magnetic flux conducting piece FL2.

In this embodiment, the first magnetic flux conducting piece FL1 and the second magnetic flux conducting piece FL2 have an axis-orthogonal portion 41 extending parallel to each other in a direction perpendicular to the axial direction x from both ends of the magnetic wire FE, and an axis-parallel portion 42 extending from the tip of the axis-orthogonal portion 41 in a direction approaching each other along the axial direction x. Both ends of the magnetic wire FE are fixed to the base ends of the axis-orthogonal portions 41 of the first magnetic flux conducting piece FL1 and the second magnetic flux conducting piece FL2. More specifically, the base end of the axis-orthogonal portion 41 is provided with a wire arrangement portion 23 having a hole or groove formed therein that penetrates in the axial direction x. Both ends of the magnetic wire FE are fixed to the axis-orthogonal portions 41 in the wire arrangement portion 23, penetrating the axis-orthogonal portions 41 of the first magnetic flux conducting piece FL1 and the second magnetic flux conducting piece FL2, respectively. For example, the magnetic wire FE and the first and second magnetic flux conducting pieces FL1 and FL2 are connected and fixed to each other by resin (not shown) placed in the holes or grooves that make up the wire placement section 23. As a result, both ends of the magnetic wire FE are magnetically connected to the first and second magnetic flux conducting pieces FL1 and FL2, respectively.

The power generation sensor 20 is configured so that the side opposite the magnetic wire FE with respect to the axially parallel portion 42 is a detection region SR for detecting a magnetic field.

Each of the magnetic flux conducting pieces FL1 and FL2, which are made of a soft magnetic material, has an axis-orthogonal portion 41 having a substantially rectangular parallelepiped shape and an axis-parallel portion 42 having a substantially rectangular parallelepiped shape connected to the tip portion, which is the end portion of the axis-orthogonal portion 41 on the detection region SR side, and has an L-shape bent at a right angle at the joint between the axis-orthogonal portion 41 and the axis-parallel portion 42. The axis-parallel portion 42 extends along the axial direction x so as to cover the magnetic wire FE, i.e., to shield the area between the magnetic wire FE and the detection region SR. The first magnetic flux conducting piece FL1 and the second magnetic flux conducting piece FL2, which have mutually symmetrical shapes, extend toward the axial center side of the magnetic wire FE, and their proximal ends 42a face each other with a gap in between near the axial center position 25 of the magnetic wire FE. The proximal end 42a forms a plane perpendicular to the axial direction x, and the two planes forming each of the two proximal ends 42a are parallel to each other and face each other in the axial direction x.

The axially parallel portion 42 of the first magnetic flux conduction piece FL1 and the second magnetic flux conduction piece FL2 form magnetic flux conduction ends 21, 22 that form a detection area facing surface that faces the detection area SR. The magnetic flux conduction ends 21, 22 (detection area facing surfaces) are flat surfaces parallel to the axial direction x. When a magnetic pole is placed in the detection area SR, these magnetic flux conduction ends 21, 22 (detection area facing surfaces) guide the magnetic flux from the magnetic pole into the inside of the first magnetic flux conduction piece FL1 and the second magnetic flux conduction piece FL2.

The axially parallel portions 42 of the first magnetic flux conducting piece FL1 and the second magnetic flux conducting piece FL2 are joined to a wiring pattern (not shown) formed on one main surface of the first support 31 (printed wiring board), thereby surface-mounting the power generation sensor 20 on the first support 31 (printed wiring board). The power generation sensor 20 is arranged so that the axial direction x of the magnetic wire FE is aligned with a tangent at a point (contact point) on a circumference whose central axis is the rotation axis 33, and the axial center position 25 of the magnetic wire FE coincides with the contact point. The detection region SR of the power generation sensor 20 is on the opposite side of the axially parallel portions 42 to the magnetic wire FE, and in this example, is an area on the other main surface side of the first support 31 (printed wiring board).

In this example, the second support 32 is configured in a circular ring shape surrounding the rotation axis 33. More specifically, the second support 32 is configured as a circular plate-shaped body, arranged along a plane perpendicular to the rotation axis 33, and parallel to the first support 31 (printed wiring board). In the second support 32, a magnet M is fixed to a surface facing the other main surface of the first support 31 (printed wiring board). In this embodiment, the magnetic poles n1, s1, n2, s2, ..., nk, sk of the magnet M are arranged at equal intervals in the circumferential direction around the rotation axis 33. In the illustrated specific example, four magnetic poles n1, s1, n2, s2 are arranged at 90 degree angular intervals around the rotation axis 33, and the magnet M is fixed to the second support 32 so that they face the first support 31 (printed wiring board). The distance from the rotation axis 33 to the center of the magnetic poles n1, s1, n2, s2, ..., nk, sk may be equal to the distance from the rotation axis 33 to the axial center position 25 of the magnetic wire FE. That is, in a plan view along the rotation axis 33, the magnetic wire FE and the magnetic poles n1, s1, n2, s2, ..., nk, sk may be located on a circumference of equal radius with the rotation axis 33 as the center axis, and thus may be in a positional relationship that allows them to face each other in a direction parallel to the rotation axis 33. The second support 32 is preferably a yoke made of a soft magnetic material.

When the second support 32 rotates around the rotation axis 33 together with the rotation shaft 30, the magnetic poles n1, s1, n2, s2, ..., nk, sk move on a circumferential orbit 55 centered on the rotation axis 33 and passing through the detection region SR. The axial direction x of the magnetic wire FE is parallel to a tangent passing through a certain point (contact point) on the circumferential orbit 55, and the axial center position 25 is on a perpendicular line (in this example, a perpendicular line parallel to the rotation axis 33) erected to the tangent line at the contact point. In other words, the axial center position 25 of the magnetic wire FE has its center on the rotation axis 33 and is located at a certain point (contact point) on a circumference of a radius equal to that of the circumferential orbit 55, and the magnetic wire FE is along the tangent line at the contact point.

The distance between the first support 31 and the second support 32 in the direction along the rotation axis 33 is set to an appropriate value that allows the magnetic poles n1, s1, n2, s2, ..., nk, sk to enter the detection region SR of the power generation sensor 20 by the rotation of the second support 32.

In the printed wiring board constituting the first support 31, a sensor element MS, for example a magnetic sensor, is further mounted on the main surface on which the power generation sensor 20 is mounted. The sensor element MS is arranged so as to detect the polarity of the magnetic pole facing the center of the power generation sensor 20. The sensor element MS is, for example, a magnetic sensor such as a Hall IC, and outputs an H signal when it detects an N pole (when the N pole faces the center of the power generation sensor 20), and outputs an L signal when it detects an S pole (when the S pole faces the center of the power generation sensor 20). As a result, the sensor element MS determines the polarity of the magnetic pole passing nearby, and as a result, outputs an identification signal that identifies the polarity of the magnetic pole facing the center of the power generation sensor 20. In this embodiment, the sensor element MS is arranged so as to detect the magnetic pole at a position with a phase difference of 180 degrees around the rotation axis 33, that is, at a position symmetrical with respect to the rotation axis 33, with respect to the power generation sensor 20. If k is an even number (for example, 2), the sensor element MS detects a magnetic pole of the same polarity as the magnetic pole facing the center of the power generation sensor 20. When k is an odd number (e.g., 3), the sensor element MS detects a magnetic pole of opposite polarity to the magnetic pole facing the center of the power generation sensor 20. In either case, the sensor element MS can detect the polarity of the magnetic pole facing the center of the power generation sensor 20.

With this configuration, when one magnetic pole pair n1, s1; n2, s2; ...; nk, sk passes through the detection area SR along the circumferential orbit 55 by rotating in the counterclockwise direction CCW around the rotation axis 33, one negative pulse and one positive pulse are generated in sequence. When one magnetic pole pair n1, s1; n2, s2; ...; nk, sk passes through the detection area SR along the circumferential orbit 55 by rotating in the clockwise direction CW around the rotation axis 33, one positive pulse and one negative pulse are generated in sequence. Then, the rotational position and rotational direction can be identified by these pulses and the sensor element MS that outputs an identification signal indicating the polarity of the magnetic pole on the circumferential orbit 55 between the first magnetic flux conducting piece FL1 and the second magnetic flux conducting piece FL2.

Figures 3A to 3F show an example of operation. Consider the case where the rotating shaft 30 rotates counterclockwise CCW (counterclockwise direction) around the rotation axis 33. Figure 3A is an explanatory diagram of operation when the state of Figure 2B is viewed along the arrow IIC. Figures 3B to 3F are also explanatory diagrams from a similar perspective. However, for the sake of explanation, in Figures 3A to 3F, the magnetic poles are shown expanded on a straight line.

When the state of FIG. 3A (FIG. 2B) is reached, the hard layer and soft layer of the magnetic wire FE are magnetized in the direction from the second magnetic flux conducting piece FL2 to the first magnetic flux conducting piece FL1, i.e., in the set state (SET_N) for generating a negative pulse. At this time, the area of the first magnetic flux conducting piece FL1 facing the north and south poles is balanced with the area of the second magnetic flux conducting piece FL2 facing the north and south poles. In other words, the magnetic field generating source 50, the power generation sensor 20 and their relative positions are designed to achieve this state.

When the magnetic field generating source 50 rotates slightly counterclockwise CCW together with the rotating shaft 30 from this state, as shown in FIG. 3B, the proportion of the area of the first magnetic flux conducting piece FL1 facing the N pole increases, and the proportion of the area of the second magnetic flux conducting piece FL2 facing the N pole decreases. As a result, a magnetic field is applied to the magnetic wire FE in a direction from the first magnetic flux conducting piece FL1 to the second magnetic flux conducting piece FL2. When the strength of this magnetic field reaches the operating magnetic field, the magnetization direction of the soft layer is reversed, and a negative voltage pulse is generated. At this time, the sensor element MS detects the S pole (the S pole faces the center of the power generation sensor 20), so it generates an L signal.

Furthermore, when the rotating shaft 30 rotates in the counterclockwise direction CCW, the magnetic field in the direction from the first magnetic flux conducting piece FL1 to the second magnetic flux conducting piece FL2 becomes even stronger and reaches a stabilizing magnetic field, and as shown in FIG. 3C, the magnetization direction of the hard layer of the magnetic wire FE is also reversed, resulting in a set state (SET_P) for generating a positive pulse.

When the rotating shaft 30 rotates further and reaches the state of FIG. 3D, rotated 90 degrees counterclockwise CCW from the state of FIG. 3C, the polarity is reversed, but the operation is the same as in the above case. That is, the hard layer and soft layer of the magnetic wire FE are magnetized in the direction from the first magnetic flux conducting piece FL1 to the second magnetic flux conducting piece FL2, that is, in the set state (SET_P) for generating a positive pulse. At this time, the area of the first magnetic flux conducting piece FL1 facing the north and south poles is balanced with the area of the second magnetic flux conducting piece FL2 facing the north and south poles.

When the magnetic field generating source 50 rotates slightly counterclockwise CCW together with the rotating shaft 30 from this state, the proportion of the area of the first magnetic flux conducting piece FL1 facing the N pole decreases and the proportion of the area of the second magnetic flux conducting piece FL2 facing the N pole increases, as shown in Figure 3E. As a result, a magnetic field is applied to the magnetic wire FE in a direction from the second magnetic flux conducting piece FL2 toward the first magnetic flux conducting piece FL1. When the strength of this magnetic field reaches the operating magnetic field, the magnetization direction of the soft layer is reversed and a positive voltage pulse is generated. At this time, the sensor element MS detects the N pole (the N pole faces the center of the power generation sensor 20) and generates an H signal.

When the rotating shaft 30 rotates further in the counterclockwise direction CCW, the magnetic field in the direction from the second magnetic flux conducting piece FL2 to the first magnetic flux conducting piece FL1 becomes even stronger and reaches a stabilizing magnetic field, and as shown in Figure 3F, the magnetization direction of the hard layer of the magnetic wire FE is also reversed, resulting in a set state (SET_N) for generating a negative pulse. When the rotating shaft 30 rotates further in the counterclockwise direction CCW from this state, the state becomes equivalent to that of Figure 3A.

Thus, two pulses are generated when one magnetic pole pair passes through the detection area of the power generation sensor 20. Since the magnetic field generating source 50 has k magnetic pole pairs (two in this example), 2k pulses (four in this example) are generated per rotation.

FIG. 4 is a diagram for explaining the operation of the segment counter 2. In this embodiment, the segment counter 2 counts the number of segments obtained by dividing the angular region around the rotation axis 33 into _Um segments ( _Um is an integer equal to or greater than 4), and generates a count value representing the counting result. The division of the segments corresponds to the arrangement of the magnetic poles n1, s1, n2, s2, ..., nk, and sk. Typically, a plurality of magnetic poles n1, s1, n2, s2, ..., nk, and sk are formed (magnetized) in regions divided at equal angles around the rotation axis 33, and accordingly, the segments are regions obtained by equally dividing the angular region around the rotation axis 33. FIG. 4 shows an example where _Um = 4. The four segments are defined by four boundaries a, b, c, and d set at 90-degree intervals around the rotation axis 33. The boundaries a, b, c, and d are boundaries at which the count value of the segment counter 2 switches in response to a voltage pulse generated by the power generation sensor 20. Specifically, the boundaries a, b, c, and d correspond to angular positions where any of the magnetic poles faces the center of the power generation sensor 20. As an example, a case will be described here where the magnetic poles cross the position facing the center of the power generation sensor 20 and count up when they move in the counterclockwise direction CCW and count down when they move in the clockwise direction CW.

When the magnetic poles n1, s1, n2, and s2 are arranged at equal intervals on a circumference, the intervals between the boundaries a, b, c, and d are 90 degrees in rotation angle, and if the boundary a is set as the reference angle of 0 degrees, the boundary b is 90 degrees, the boundary c is 180 degrees, and the boundary d is 270 degrees. In this embodiment, the segment counter 2 is designed to count up when the rotation angle moves in the counterclockwise direction CCW across the boundaries a, b, c, and d, and to count down when the rotation angle moves in the clockwise direction CW across the boundaries a, b, c, and d. Accordingly, in the following description, the angle value around the rotation axis 33 is assumed to increase in the counterclockwise direction CCW with the boundary a as the reference.

The magnetic field generating source 50 is configured to generate an alternating magnetic field with k periods (k=2 in the illustrated example) during one rotation of the rotating shaft 30 around the rotating axis 33. More specifically, in this embodiment, 2k magnetic poles n1, s2, n2, s2, ..., nk, sk are arranged at equal angular intervals around the rotating axis 33.

The symbols in the figure have the following meanings. "H" is a state value representing a state in which the sensor element MS detects any of the N poles n1, n2, ..., nk, i.e., any of the N poles n1, n2, ..., nk faces the center of the power generation sensor 20. "L" is a state value representing a state in which the sensor element MS detects any of the S poles s1, s2, ..., sk, i.e., any of the S poles s1, s2, ..., sk faces the center of the power generation sensor 20. These state values correspond to the magnetic detection data generated by the signal processing circuit 7 based on the output of the sensor element MS. "P" is a pulse polarity value representing the generation of a positive pulse of the power generation sensor 20. "N" is a pulse polarity value representing the generation of a negative pulse of the power generation sensor 20. These pulse polarity values correspond to the polarity discrimination data generated by the signal processing circuit 7 based on the output of the signal evaluation circuit 5.

The state value supplied from the signal processing circuit 7 to the counter circuit 8 is represented by a combination of these values, is updated each time the power generation sensor 20 generates a pulse, and is stored in the non-volatile memory 9. "HP" is a state value representing a state in which a positive pulse is generated when any of the N poles n1, n2, ..., nk faces the center of the power generation sensor 20. "LN" is a state value representing a state in which a negative pulse is generated when any of the S poles s1, s2, ..., sk faces the center of the power generation sensor 20. "HN" is a state value representing a state in which a negative pulse is generated when any of the N poles faces the center of the power generation sensor 20. "LP" is a state value representing a state in which a positive pulse is generated when any of the S poles faces the center of the power generation sensor 20.

"SET_P" represents the angle range in which the device is ready (set) to generate a positive pulse. "SET_N" represents the angle range in which the device is ready (set) to generate a negative pulse.

The basic operation of segment counter 2 is as follows:

When the rotating shaft 30 rotates counterclockwise CCW, one positive pulse or one negative pulse is generated by the operation of the power generation sensor 20 shown in Figures 3A to 3F near the boundaries a, b, c, and d corresponding to rotation angles of 0 degrees, 90 degrees, 180 degrees, and 270 degrees, respectively. At this time, the state changes cyclically as follows: set state SET_P → state value HP (generating positive pulse) → set state SET_N → state value LN (generating negative pulse) → set state SET_P → ... The segment counter 2 counts up by +1 at each of the state values HP and LN. That is, it counts up by +1 when the rotation angle increases by passing through 0 degrees (boundary a), 90 degrees (boundary b), 180 degrees (boundary c), and 270 degrees (boundary d).

When the rotating shaft 30 rotates in the clockwise direction CW, the power generation sensor 20 operates in a manner that reverses the direction of magnetic pole movement from that shown in Figures 3A to 3F near boundaries a, b, c, and d, which correspond to rotation angles of 0 degrees, 90 degrees, 180 degrees, and 270 degrees, respectively. This generates one positive pulse or one negative pulse. At this time, the state changes cyclically as follows: set state SET_N → state value HN (negative pulse generation) → set state SET_P → state value LP (positive pulse generation) → set state SET_N → ... The segment counter 2 counts down by -1 at the state values HN and LP. That is, it counts down by -1 when the rotation angle decreases by passing through 0 degrees (boundary a), 90 degrees (boundary b), 180 degrees (boundary c), and 270 degrees (boundary d).

Figure 5 is a table for explaining an example of the counting operation of the segment counter 2 in more detail. The counter circuit 8 built into the counter memory IC 10 executes the counting operation according to logic that follows this table. When the power generation 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 (Counter operation) is determined by the combination of the updated state value (NEW: current value) and the immediately preceding state value (OLD: previous value). The counter circuit 8 reads the immediately preceding state value (OLD) from the non-volatile memory 9 and executes the counting operation using it.

When the updated state value is HP, if the previous state value is either LN or HN (i.e., if the polarity of the pulse is different), a +1 count-up operation is performed. When the updated state value is HN, if the previous state value is either LP or HP (i.e., if the polarity of the pulse is different), a -1 count-down operation is performed.

When the updated state value is LP, if the previous state value is either HN or LN (i.e., if the polarity of the pulse is different), a -1 count-down operation is performed. When the updated state value is LN, if the previous state value is either HP or LP (i.e., if the polarity of the pulse is different), a +1 count-up operation is performed.

The above is the basic counting operation, and in addition to this, an exceptional counting operation is performed to compensate for the effect of missing pulses, which will be described later. Specifically, when the updated state value is equal to the previous state value, the count value is kept unchanged (the count value changes to "0"). Furthermore, when the updated state value is HP, if the previous state value is LP (i.e., if the polarity of the pulse voltage is the same and the polarity of the magnetic pole detected by the sensor element MS is different), a +2 count operation is performed. When the updated state value is HN, if the previous state value is LN (i.e., if the polarity of the pulse voltage is the same and the polarity of the magnetic pole detected by the sensor element MS is different), a -2 count operation is performed. When the updated state value is LP, if the previous state value is HP (i.e., if the polarity of the pulse voltage is the same and the polarity of the magnetic pole detected by the sensor element MS is different), a -2 count operation is performed. When the updated state value is LN, if the previous state value is HN (i.e., if the polarity of the pulse voltage is the same and the polarity of the magnetic pole detected by the sensor element MS is different), a +2 count operation is performed.

In this way, the counter circuit 8 operates according to the state value, i.e., using the output signal of the sensor element MS and the pulse voltage generated by the power generation sensor 20, to identify the rotation direction and rotation position of the rotating shaft 30, update the count value, and write the count value to the non-volatile memory 9.

The operation of the counter circuit 8 can be summarized as follows:

Step 1 (identification of rotation direction): The direction of rotation is identified by a combination of the polarity of the current pulse voltage and the current sensor element state (here, the polarity of the magnetic pole detected by the sensor element MS), and the sign of the count amount is determined. For example, the state value H of the sensor element MS is represented as "+1", and the state value L of the sensor element MS is represented as "-1". Also, the pulse polarity value P is represented as "+1", and the pulse polarity value N is represented as "-1". Then, the product of the pulse polarity value and the sensor element state value is +1 or -1, which is the rotation direction value that represents the rotation direction. That is, the rotation direction value for the state values HP and LN is "+1", which represents the counterclockwise direction CCW rotation direction (see Figure 4). Also, the rotation direction value for the state values HN and LP is "-1", which represents the clockwise direction CW rotation direction. The signs of these rotation direction values are the signs of the count amount. It is obvious that the way symbols are assigned is not limited to the above. If different symbols are assigned to the two sensor element state values and different symbols are assigned to the two pulse polarity values, the sign of the product of the sensor element state value and the pulse polarity value will indicate the direction of rotation.

Step 2 (absolute value of the count amount): When the polarity of the current pulse voltage is different from the polarity of the previous pulse voltage, the absolute value of the count amount is set to 1. When the polarity of the current pulse voltage is the same as the polarity of the previous pulse voltage and the current sensor element state is the same as the previous sensor element state, the absolute value of the count amount is set to 0. When the polarity of the current pulse voltage is the same as the polarity of the previous pulse voltage and the current sensor element state is different from the previous sensor element state, the absolute value of the count amount is set to 2.

Step 3 (count amount): The determined sign (step 1) is applied to the absolute value of the count amount (step 2) to obtain the count amount.

Step 4 (update count value): Update the count value by adding the calculated count amount (step 3) to the previous count value.

The order of steps 1 and 2 may be reversed, or they may be performed simultaneously. Also, the table shown in FIG. 5 may be prepared in advance, and the count amount may be calculated using this table. In this case, steps 1, 2, and 3 are performed substantially simultaneously.

Figure 6 is a diagram to explain the effect of missing pulses on the count value.

Consider the case where the rotation angle moves along the trajectory T1. When the rotation angle moves in the counterclockwise direction CCW across the boundary a, and a positive pulse is generated at position 51, the state value becomes HP (see FIG. 3E). If the rotation direction is reversed before the rotation angle reaches the position (see FIG. 3F) where the stabilizing magnetic field is applied to the magnetic wire FE of the power generation sensor 20, the rotation angle crosses the boundary a in the clockwise direction CW and reaches position 52 where the state value should be HN without the magnetic wire FE being in a negative pulse generation preparation state (SET_N). At this time, the negative pulse that should be generated at position 52 is not generated (pulse missing), so the state value is not updated. After that, the magnetic wire FE becomes in a positive pulse generation preparation state (SET_P) due to further rotation in the clockwise direction CW. After that, before the rotation angle reaches the boundary d, the rotation direction is reversed to the counterclockwise direction CCW at position 53, and when the boundary a is crossed again, a positive pulse is generated again at position 51. Therefore, the change in state value is from HP to HP, so the count value remains unchanged (see Figure 5). The behavior is similar when the rotation direction is reversed. During this behavior, the count value may include an error of ±1.

Next, consider the case where the rotation angle moves along the trajectory T2. That is, the rotation angle moves in the clockwise direction CW across the boundary d, which generates a positive pulse at position 61, resulting in a state value LP. If the rotation direction is reversed before the rotation angle reaches a position (see FIG. 3F) where a stabilizing magnetic field is applied to the magnetic wire FE of the power generation sensor 20, the rotation angle crosses the boundary d in the counterclockwise direction CCW and reaches position 62 where the state value should be LN, without the magnetic wire FE being in a negative pulse generation preparation state (SET_N). At this time, since a negative pulse that should be generated at position 62 is not generated (pulse missing), the state value is not updated. After that, the magnetic wire FE is further rotated in the counterclockwise direction CCW, resulting in a positive pulse generation preparation state (SET_P). Then, the rotation angle moves in the counterclockwise direction CCW across the boundary a, and a positive pulse is generated at position 63, resulting in a state value HP. Therefore, if the state value changes from LP to LN and then from LN to HP, the count value should change by +1+1=+2, but because of the missing pulse at position 62, the count value changes from LP to HP without passing through the state value LN. Therefore, at this time, the count value is incremented by +2 (see FIG. 5) to compensate for the effect of the missing pulse. The behavior when the rotation direction is reversed is similar. During such behavior, the count value may include an error of ±1.

Assume that the correct count value in the angle range of one rotation (360 degrees) is "0" in the section S0 (0 degrees to 90 degrees) between the boundaries a and b, "1" in the section S1 (90 degrees to 180 degrees) between the boundaries b and c, "2" in the section S2 (180 degrees to 270 degrees) between the boundaries c and d , and "3" in the section S3 (270 degrees to 360 degrees) between the boundaries d and a . In this case, taking into account the count error as described above, the angle ranges A0, A1, A2, and A3 in which the count value may be "0", "1", "2", and "3", respectively, are as shown in FIG. 6. These angle ranges A0, A1, A2, and A3 are wider than the angle ranges (90 degrees) of the sections S0, S1, S2, and S3, but as shown in FIG. 6, all of them are less than one rotation (360 degrees). Therefore, since there are no overlapping areas over a plurality of revolutions, it is possible to determine the number of revolutions in units of one revolution using the count value and the detected angle value.

7 shows the relationship between the count value of the segment counter 2 and the angle detection value of the precision absolute angle detector 1. The horizontal axis is the rotation angle (degrees) of the rotating shaft 30, and the vertical axis is the multiple rotation absolute angle value, with one rotation (360 degrees) represented with a resolution of 16 bits (65,536 steps). However, it is assumed that the number of segments U _m =2k=4.

As the rotating shaft 30 rotates, the angle detection value of the precision absolute angle detector 1 changes in a sawtooth wave shape between 0 and 65536, as shown by reference numeral 70.

On the other hand, the count value of the segment counter 2 ideally changes in a step-like manner as indicated by reference symbol 71 as the rotation shaft 30 rotates. For example, ideally, the count value in each angle section of a 90 degree (=360 degree/4) range with a median value at intervals of 90 degrees (=360 degree/4) from 0 degree should be -3, -2, -1, 0, 1, 2, 3... The segment counter 2 counts 4 times per rotation, so the step height per count is 65536/4.

In reality, the count value of the segment counter 2, which includes the error described above, may be the same value in the error intervals e1 and e2 on both sides of each count value. In Patent Document 2, to eliminate this error interval, magnetic discrimination is performed when the external power supply is turned on, the count value of the segment counter is corrected, and synchronization is achieved with the angle detection value of the precision absolute angle detector. In this embodiment, such correction and synchronization processing is not performed, and the count value of the segment counter 2, which includes the error, is used as is to integrate the count value of the segment counter 2 and the angle detection value of the precision absolute angle detector 1.

To be more specific, as shown in FIG. 7, the count value of the segment counter 2 is checked when the angle detection value of the precision absolute angle detector 1 is a certain value, for example, "38229" which corresponds to 210 degrees in an angle range within one rotation (0 degrees to 360 degrees). In an angle range spanning multiple rotations, the angle detection value of the precision absolute angle detection value becomes "38229" (210 degrees) at multiple rotation angles in 360 degree intervals, with 210 degrees as the base. That is, -870 degrees, -510 degrees, -150 degrees, 210 degrees, 570 degrees, 930 degrees, .... Considering the count error, the possible values that the count value of the segment counter 2 can take at these multiple rotation angles are as shown in Table 1 below.

図８には、正の回転角範囲におけるセグメントカウンタ２のカウント値の変化を示す。ただし、ここでは、セグメントカウンタ２のカウント値は、セグメント数（ここでは４）で除した値（回転数Ｎに換算した値）を示す。線７０は、図７と同様に、精密アブソリュート角度検出器１の角度検出値を表す。階段状の線７１は、図７の線７１に相当する。線７１－１は、－１の誤差（セグメント数「４」で除した場合の誤差は－０．２５）を含むカウント値の変化を示し、線７１＋１は、＋１の誤差（セグメント数「４」で除した場合の誤差は＋０．２５）を含むカウント値の変化を示す。この図８からも、表１のとおりの結論が得られる。

FIG. 8 shows the change in the count value of the segment counter 2 in the positive rotation angle range. However, here, the count value of the segment counter 2 indicates the value (converted into the number of rotations N) divided by the number of segments (here, 4). Line 70, like FIG. 7, indicates the angle detection value of the precision absolute angle detector 1. Step-like line 71 corresponds to line 71 in FIG. 7. Line 71-1 indicates the change in the count value including an error of -1 (the error when divided by the number of segments "4" is -0.25), and line 71+1 indicates the change in the count value including an error of +1 (the error when divided by the number of segments "4" is +0.25). The conclusions shown in Table 1 can be obtained from FIG. 8 as well.

In this way, even when the error is taken into account, the range that each count value of the segment counter 2 can take is less than 360 degrees, so the same count value does not overlap at different multi-rotation angles. Therefore, the multi-rotation absolute angle detection value can be uniquely determined by combining the count value of the segment counter 2 and the angle detection value detected by the precision absolute angle detector 1. Therefore, without performing processing to correct the count error of the segment counter 2 and synchronize the count value with the angle detection value detected by the precision absolute angle detector 1, they can be integrated to generate the multi-rotation absolute angle detection value as shown in Figure 9.

The calculation device 4 uses the count value m of the segment counter 2 and the angle detection value θ of the precision absolute angle detector 1, and performs, for example, the following calculation to integrate them and calculate the multi-rotation absolute angle detection value θmt. The above-mentioned FIG. 9 shows the calculation result. In the following formula, N represents the number of rotations (amount of rotation) from the reference point (origin of rotation position) of the rotating shaft 30. U _θ represents the amount of angle detection per rotation (for example, U _θ = 65536 (16 bits)) and corresponds to the resolution of the precision absolute angle detector 1. U _m (for example, U _m = 2k = 4) is the number of segments per rotation and corresponds to the number of counts per rotation of the segment counter 2.

上式のとおり、回転数Ｎは、カウント値ｍをセグメント数Ｕ_ｍで除して回転数に換算し、そこから角度検出値θに相当する回転量（θ／Ｕ_θ）を減じたうえで、四捨五入して求めることができる。上式の例では、１／２を加えて整数化関数INT（小数部を切り捨てて整数化する関数）で処理することで四捨五入演算が行われている。

As shown in the above formula, the number of rotations N can be calculated by dividing the count value m by the number of segments _Um to convert it to the number of rotations, subtracting the amount of rotation (θ/ _Uθ ) corresponding to the detected angle value θ from the number of rotations, and then rounding off the result. In the above formula, the rounding operation is performed by adding 1/2 and processing with the integer conversion function INT (a function that rounds down the decimal part to an integer).

The number of rotations N thus obtained is multiplied by the amount of angle detection _Uθ per rotation to obtain a multiple-rotation angle detection value for the count value m of the segment counter 2. By adding a precise angle detection value θ within one rotation to this, a multiple-rotation absolute angle detection value θmt that represents a precise multiple-rotation absolute angle can be obtained.

Prepared tables may be used, as necessary, to perform some or all of the above-mentioned calculations in the calculation device 4.

When actually calculating the rotation speed N, it is convenient to use the following formula, which is equivalent to the above formula, to avoid dealing with decimal values.

すなわち、カウント値ｍに１回転あたりの角度検出量Ｕ_θを乗じ、これをセグメント数Ｕ_ｍで除した換算値ｍＵ_θ/Ｕ_ｍを用いる。この換算値ｍＵ_θ/Ｕ_ｍは、カウント値ｍを精密角度検出値の値に換算した数値である。換算値ｍＵ_θ/Ｕ_ｍは、回転角に応じて、図８の線７１，７１－１，７１＋１のように階段状に変化する。図８に示す換算値ｍＵ_θ/Ｕ_ｍ（線７１，７１－１，７１＋１）から精密角度検出値θ（図８の線７０）を減じてｍＵ_θ/Ｕ_ｍ－θを求め、さらにＵ_θ／２を加算すると、図１０に示すように、各段において鋸歯状の変化を示す階段状の線が得られる。線８０，８０－１，８０＋１は、図８の線７１，７１－１，７１＋１にそれぞれ対応しており、ｍＵ_θ/Ｕ_ｍ－θ＋Ｕ_θ／２に相当する。これをＵ_θで除して、整数化関数INTで整数化することにより、図１０に線８５で示すように、上記式の回転数Ｎを得ることができる。

That is, a converted value mU _θ /U _m is used, which is obtained by multiplying the count value m by the amount of angle detection U _θ per rotation and dividing the result by the number of segments U _m . This converted value mU _θ /U _m is a numerical value obtained by converting the count value m into a precise angle detection value. The converted value mU _θ /U _m changes in a stepped manner according to the rotation angle, as shown by lines 71, 71-1, and 71+1 in FIG. 8. By subtracting the precise angle detection value θ (line 70 in FIG. 8) from the converted value mU _θ /U _m (lines 71, 71-1, and 71+1) shown in FIG. 8 to obtain mU _θ /U _m -θ, and then adding U _θ /2, a stepped line showing a sawtooth change at each step is obtained, as shown in FIG. 10. Lines 80, 80-1, and 80+1 correspond to lines 71, 71-1, and 71+1 in Fig. 8, respectively, and are equivalent to mU _θ /U _m -θ + U _θ /2. By dividing this by U _θ and converting it to an integer using the integer conversion function INT, the rotation speed N of the above formula can be obtained, as shown by line 85 in Fig. 10.

As described above, in this embodiment, the segment counter 2 has only one power generation sensor 20 and sensor element MS, and is configured so that two or more periods of an alternating magnetic field are applied to the magnetic wire of the power generation sensor 20 per rotation. The count value of the segment counter 2 configured in this way can be handled while still including errors and appropriately integrated with the angle detection value generated by the precision absolute angle detector 1, thereby obtaining a precise multi-rotation absolute angle detection value. Therefore, there is no need to use multiple power generation sensors 20, and there is no need 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 that. This simplifies the configuration, and therefore a compact, low-cost, yet high-resolution multi-rotation precision absolute angle detection device can be provided.

The second embodiment of the invention will now be described.

The magnetic field generating source may be configured to include k magnets (k≧2) arranged on a circumference centered on the axis of rotation with magnetic poles of the same polarity facing the power generating sensor. In this case, too, an alternating magnetic field of k periods per rotation can be applied to the magnetic wire. In this case, too, it is preferable that the magnetic wire of the power generating sensor is arranged parallel to the tangent of the circumference. In addition, it is preferable that the power generating sensor has a first magnetic flux conducting piece and a second magnetic flux conducting piece magnetically coupled to the first end and the second end of the magnetic wire, respectively. As the magnetic field generating source rotates, the magnetic pole approaches the first magnetic flux conducting piece and the second magnetic flux conducting piece in order. The power generating sensor generates a negative pulse voltage in a first state in which the magnetic flux from the magnetic pole of the magnetic field generating source is conducted from the first magnetic flux conducting piece, and generates a positive pulse voltage in a second state in which the magnetic flux from the magnetic field generating source is conducted from the second magnetic flux conducting piece. By counting these pulse voltages with the aforementioned segment counter, 2k segments can be counted per rotation. In this case, typically, no magnetic poles of the same polarity are arranged on the circular orbit through which the magnetic poles of the k magnets of the same polarity pass. Therefore, as the rotor rotates in one direction, the magnetic poles of the same polarity face the power generation sensor in sequence.

For example, consider the case where the soft layer and hard layer of the magnetic wire are in a set state (set state for generating a negative pulse) magnetized in a direction from the second magnetic flux conducting piece to the first magnetic flux conducting piece, and the magnetic pole approaches the first magnetic flux conducting piece as the magnetic field generating source rotates together with the rotor. The magnetic flux from that magnetic pole is conducted from the first magnetic flux conducting piece, reversing the magnetization direction of the soft layer of the magnetic wire and generating a negative pulse. When that magnetic pole approaches the first magnetic flux conducting piece even closer, the magnetization direction of the hard layer is also reversed, and the magnetic wire is in a set state for generating a positive pulse. When the magnetic field generating source rotates further and the magnetic pole approaches the second magnetic flux conducting piece, the magnetic flux from that magnetic pole is conducted from the second magnetic flux conducting piece. This reverses the magnetization direction of the soft layer of the magnetic wire and generates a positive pulse. When that magnetic pole approaches the second magnetic flux conducting piece even closer, the magnetization direction of the hard layer is also reversed, and the magnetic wire is in a set state for generating a negative pulse. Thus, when one magnetic pole passes through the detection area of the power generation sensor, two pulses are generated.

When this configuration is adopted, it is preferable that the sensor element detects whether or not the magnetic pole of the magnetic field source is located in a position facing the center of the power generation sensor. The boundary of the segment is the angular position where the magnetic pole faces the center of the power generation sensor. By using the sensor element to detect whether the magnetic pole of the magnetic field source faces the center of the power generation sensor, it becomes possible to identify the rotational position and rotational direction based on the output of the sensor element and the power generation sensor, as in the case of the above-mentioned embodiment.

Two embodiments of the present invention have been described above, but the present invention can be embodied in other forms as shown below.

In the above embodiment, an example was shown in which a power generation sensor 20 having L-shaped magnetic flux conducting pieces FL1 and FL2 was used, but the magnetic flux conducting pieces may have other shapes. For example, an I-shaped magnetic flux conducting piece extending linearly from the magnetic wire FE toward the detection area may be used. In addition, a configuration may be used in which cylindrical magnetic flux conducting pieces about the size of a coil are provided at both ends of the magnetic wire.

In the above embodiment, the magnetic field generating source 50 has mainly been described as having two magnetic pole pairs (see FIG. 2A) or two homopolar magnets (second embodiment), but it may also be configured to have three or more magnetic pole pairs or three or more homopolar magnets, and may be provided with a segment counter having six or more segments.

In addition, the precision absolute angle detector 1 does not necessarily mean a single detector, but may be any detector that has the function of obtaining the absolute angle within one rotation. For example, the precision absolute angle detector 1 may be configured with multiple detectors with a detection range of one rotation or less. As an example, the angle per one cycle/revolution may be calculated from the detection signal of a detector with 32 cycles/revolution and the detection signal of a detector with 31 cycles/revolution. The calculation in this case may also be performed by the calculation device 4.

In addition, various design changes may be made within the scope of the claims.

1: Precision absolute angle detector 2: Segment counter 3: Power supply circuit 4: Arithmetic unit 5: Signal evaluation circuit 6: Rectification/power supply circuit 7: Signal processing circuit 8: Counter circuit 9: Non-volatile memory 10: Counter memory IC
20: power generation sensor 33: rotation axis 50: magnetic field generator 100: multi-rotation angle detection device FE: magnetic wire FL1: first magnetic flux conducting piece FL2: second magnetic flux conducting piece M: magnet MS: sensor element SP: coil SR: detection areas a, b, c, d: boundaries n1, n2: north poles s1, s2: south poles

Claims (8)

A multiple rotation angle detection device that generates a multiple rotation absolute angle detection value of a rotating body that rotates around a rotation axis, comprising:
a segment counter that generates a count value by counting segments obtained by dividing one rotation period of the rotor in an angle range exceeding one rotation of the rotor in response to rotation of the rotor;
a precision absolute angle detector that is operated by an external power supply and generates an absolute angle detection value within one rotation period of the rotating body with a resolution higher than that of the segment;
a calculation device that operates by an external power supply and that integrates the count value of the segment counter and the absolute angle detection value of the precision absolute angle detector to generate a multiple rotation absolute angle detection value of the rotating body,
the segment counter includes one power generation sensor, a magnetic field generation source that rotates around the rotation axis together with the rotor, a sensor element other than the power generation sensor, and a non-volatile memory that stores the count value;
the power generation sensor has a magnetic wire that exhibits the large Barkhausen effect and a coil wound around the magnetic wire, and generates a pulse voltage in response to a change in a magnetic field caused by rotation of the magnetic field generation source;
the magnetic field generating source applies an alternating magnetic field having two or more periods per rotation of the rotor in the axial direction of the magnetic wire;
The segment counter can operate by the energy of the pulse voltage generated by the power generating sensor without receiving an external power supply, and when the power generating sensor generates a pulse voltage, the segment counter identifies a rotation direction and a rotation position of the rotating body using the polarity of the pulse voltage (hereinafter referred to as the "polarity of the current pulse voltage"), the output state of the sensor element when the pulse voltage was generated (hereinafter referred to as the "current sensor element state"), the polarity of the previous pulse voltage, the output state of the sensor element when the previous pulse voltage was generated (hereinafter referred to as the "previous sensor element state"), and a count value updated by the generation of the previous pulse voltage and stored in the nonvolatile memory (hereinafter referred to as the "previous count value"), and updates the count value and stores it in the nonvolatile memory;
The segment counter is
identifying a rotation direction of the rotor based on a combination of the polarity of the current pulse voltage and the current state of the sensor element, and determining a sign of the count amount;
When the polarity of the current pulse voltage is different from the polarity of the previous pulse voltage, the absolute value of the count amount is set to 1;
when the polarity of the current pulse voltage is the same as the polarity of the previous pulse voltage and the current sensor element state is the same as the previous sensor element state, the absolute value of the count amount is set to 0;
when the polarity of the current pulse voltage is the same as the polarity of the previous pulse voltage and the current sensor element state is different from the previous sensor element state, the absolute value of the count amount is set to 2;
updating the count value by adding the count value obtained by applying the determined sign to the absolute value of the count value to the previous count value;
When the arithmetic device receives an external power supply, it uses the count value stored in the non-volatile memory as is, and integrates the count value of the segment counter and the absolute angle detection value of the precision absolute angle detector to generate a multi-rotation absolute angle detection value of the rotating body. The multi-rotation angle detection device according to claim 1, wherein when the power generation sensor generates a pulse voltage, the segment counter stores in the non-volatile memory the polarity of the pulse voltage and the output state of the sensor element when the pulse voltage is generated. The multi-rotation angle detection device according to claim 1, wherein the segment counter counts segments obtained by dividing one rotation period of the rotating body into four or more segments. The multi-rotation angle detection device according to any one of claims 1 to 3, wherein the magnetic field generating source includes two or more magnetic pole pairs in which N poles and S poles are arranged alternately on a circumference having a center on the rotation axis. The multi-rotation angle detection device according to claim 4, wherein the magnetic wire of the power generation sensor is on a tangent to a circumference having a center on the rotation axis, and the center of the magnetic wire is on the tangent point of the tangent. The multi-rotation angle detection device according to claim 5, wherein the power generation sensor has a first magnetic flux conducting piece and a second magnetic flux conducting piece magnetically coupled to both ends of the magnetic wire. The multi-rotation angle detection device according to claim 4, wherein the sensor element detects the polarity of the magnetic pole facing the center of the power generation sensor. A segment counter that generates a count value by counting segments obtained by dividing one rotation period of a rotor that rotates about a rotation axis of the rotor in an angle range exceeding one rotation of the rotor, the segment counter comprising:
a power generation sensor, a magnetic field generating source rotating about the rotation axis together with the rotor, a sensor element other than the power generation sensor, a non-volatile memory that stores the count value, and a counter circuit that updates the count value,
the power generation sensor has a magnetic wire that exhibits the large Barkhausen effect and a coil wound around the magnetic wire, and generates a pulse voltage in response to a change in a magnetic field caused by rotation of the magnetic field generation source;
the magnetic field generating source applies an alternating magnetic field having two or more periods per rotation of the rotor in the axial direction of the magnetic wire;
When the power generation sensor generates a pulse voltage, the counter circuit uses the polarity of the pulse voltage (hereinafter referred to as the "polarity of the current pulse voltage"), the output state of the sensor element when the pulse voltage was generated (hereinafter referred to as the "current sensor element state"), the polarity of the previous pulse voltage, the output state of the sensor element when the previous pulse voltage was generated (hereinafter referred to as the "previous sensor element state"), and a count value updated by the generation of the previous pulse voltage and stored in the nonvolatile memory (hereinafter referred to as the "previous count value") to identify the rotation direction and rotation position of the rotating body, update the count value, and store it in the nonvolatile memory;
The counter circuit includes:
identifying a rotation direction of the rotor based on a combination of the polarity of the current pulse voltage and the current state of the sensor element, and determining a sign of the count amount;
When the polarity of the current pulse voltage is different from the polarity of the previous pulse voltage, the absolute value of the count amount is set to 1;
when the polarity of the current pulse voltage is the same as the polarity of the previous pulse voltage and the current sensor element state is the same as the previous sensor element state, the absolute value of the count amount is set to 0;
when the polarity of the current pulse voltage is the same as the polarity of the previous pulse voltage and the current sensor element state is different from the previous sensor element state, the absolute value of the count amount is set to 2;
updating the count value by adding the count value obtained by applying the determined sign to the absolute value of the count value to the previous count value;
Segment counter.

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