JP2009276262A - Position detector and linear drive device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a position detector with high detection accuracy of a position and a linear drive device. <P>SOLUTION: This position detector includes a stator having multiple magnetic pole rows, and a sensor device that moves in parallel relative to faces of the multiple magnetic pole rows of the stator and detects an orientation of a magnetic flux from the stator. The sensor device includes a magnetic sensitive face constituted by a plurality of spin bulb type huge magnetic resistance effect elements (the magnetic resistance effect element includes a fixed layer and a free layer, a magnetizing direction of the fixed layer is fixed, and a magnetizing direction of the free layer is rotated in response to the orientation of a magnetic field). The sensor device is provided at the stator in such a manner that the magnetic flux is made to intersect with the magnetic sensitive face and magnitudes of amplitudes of components of magnetic flux densities orthogonalized in the magnetic sensitive face are the same as each other. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a position detection device that detects the position of a mover relative to a stator, and a linear drive device.

  Patent Document 1 discloses a magnetic position detection device having a magnetic member in which N poles and S poles are alternately arranged, and a plurality of spin-valve giant magnetoresistive elements facing the magnetic pole arrangement surface of the magnetic member. It is disclosed.

JP 2006-023179 A (FIGS. 1 and 7)

  A plurality of spin valve type GMR elements described in FIGS. 1 and 7 of Patent Document 1 constitute one magnetosensitive surface. However, the relationship between the magnetic field formed by the magnetic pole array and the magnetosensitive surface is not described in detail, and a configuration for further improving the position detection accuracy is not disclosed.

  Therefore, an object of the present invention is to provide a position detection device and a linear drive device with high position detection accuracy.

(First position detection device)
A first position detection device according to the present invention includes a stator having a multi-pole array on a surface thereof, a first that detects a direction of magnetic flux from the stator while moving parallel to the multi-pole array surface of the stator. The first sensor device includes a sensor bridge X01 and a sensor bridge Y01 whose fixed layer magnetization directions are orthogonal to each other, and the first sensor device includes the sensor device and the second sensor device. The sensor device 2 includes a sensor bridge X02 and a sensor bridge Y02 whose fixed layer magnetization directions are orthogonal to each other, and each of the sensor bridges X01, Y01, X02 and Y02 is a spin valve type giant magnetoresistive element (fixed). A magnetoresistive element having a layer and a free layer, the fixed layer magnetization direction being fixed, and the free layer magnetization direction rotating according to the direction of the magnetic field. The pinned layer magnetization directions of the spin-valve giant magnetoresistive elements on adjacent sides in the full bridge are antiparallel, and the sensor bridge Y01 and the sensor bridge Y02 have a fixed layer magnetization direction of many of the stators. The direction of the fixed layer magnetization direction of the sensor bridge X01 and the fixed layer magnetization direction of the sensor bridge X02 is λ / 4 or λ / 4 ± nλ / 2 (provided that λ / 4 Is a pitch of magnetic poles of the same polarity of a multi-pole array, and n is an integer.) The magnetic poles are arranged differently, and by applying a voltage to each of the full bridges, the fixed layer magnetization direction and the free layer magnetization A differential output corresponding to an angle made with a direction is obtained, and a position signal is obtained based on the differential output.

  When the mover moves along the arrangement direction of the multi-pole array of the stator (multi-pole arrangement direction), the spin-valve giant magnetoresistive element itself does not rotate mechanically, but the spin-valve giant magnetoresistive element Since the magnetic field acting on the magnetic field relatively corresponds to a rotating magnetic field, the magnetization direction of the free layer of the spin-valve giant magnetoresistive element is magnetically rotated. An output corresponding to the rotation angle of the magnetization direction of the free layer is obtained from a sensor device using a spin valve type giant magnetoresistive element. The position signal is obtained by performing processing including arc tangent operation on the obtained output. The rotation period of the magnetization direction in the free layer is 1 / N times (N is an integer of 2 or more) with respect to the period of the magnetic poles of the stator, and the resolution is increased.

  There are two sensor bridges in the sensor device, and the magnetization directions of the fixed layers of the elements are orthogonal to each other between the sensor bridges. The four spin-valve giant magnetoresistive elements are equivalent to four elements (elements) constituting an electrical full bridge circuit. The differential output is a differential of two outputs obtained at the midpoint of the full bridge using an operational amplifier.

  A first rotation angle signal (cosine signal) is obtained based on angle information detected independently by the sensor bridge X01 and the sensor bridge Y02, and is detected independently by the sensor bridge Y01 and the sensor bridge X02. 90 deg. In electrical angle from the first rotation angle signal. It is preferable to obtain a delayed second rotation angle signal (sine signal). A sine signal means that one wavelength has an electrical angle of 360 deg. Is a waveform corresponding to. In other words, it is a waveform that can be divided into a fundamental wave of an ideal sine wave (sin) and a harmonic that causes a rotation angle error when Fourier series expansion is performed. The cosine signal is a waveform that can be divided into a fundamental wave and a harmonic of an ideal cosine wave (cos) when Fourier series expansion is performed.

  The stator and sensor device satisfy the relationship that the free layer of the spin-valve giant magnetoresistive element, which is an element, rotates when the mover moves in parallel with the stator. Set the distance. In this way, the elements are 90 deg. Since the sensor devices are inclined, the positions of the sensor devices are 90 deg. Even if the phase difference (ie, λ / 4 phase difference) is not reached, the position of the sensor device can be accurately measured.

  The sensor bridge Y01 and the sensor bridge Y02 have the same phase with respect to one direction in which the magnetic poles of the stator are arranged, the output signal detected by the sensor bridge X01, and the sensor A first output signal (cosine signal) is obtained by performing differential amplification on an output signal obtained by inverting the output signal detected by the bridge Y02, and is detected independently by the sensor bridge Y01 and the sensor bridge X02. Differentially amplifying the output signal to be 90 deg. In electrical angle from the first output signal. It has a signal processing part for obtaining a second output signal (sine signal) with a phase lag.

  The first sensor device and the second sensor device are spaced apart from each other by approximately λ / 4 ± nλ / 2 at the position of the multi-pole array of the stator (where λ is the pitch of the same polarity magnetic poles of the multi-pole array) , N is an integer)). It is preferable that the first sensor device and the second sensor device are installed at a position approximately λ / 4 apart from each other at the position of the multi-pole array of the stator.

  The thickness t of the multi-pole array surface of the stator corresponds to the thickness of the stator magnet. The center of the sensor device is the center of the spin valve type giant magnetoresistive effect element or the center point that is substantially equidistant from the spin valve type giant magnetoresistive effect element when there are a plurality of spin valve type giant magnetoresistive effect elements. Since the thickness of the spin-valve giant magnetoresistive element is sufficiently thinner than the magnet of the stator, the center may be on the substrate on which the spin-valve giant magnetoresistive element is formed. That is, it can be said that the center of the sensor device is on the sensor surface.

(Second position detection device)
A second position detection apparatus of the present invention includes a stator having a multi-pole array on the surface, and a sensor device that translates with respect to the multi-pole array surface of the stator and detects the direction of magnetic flux from the stator. A position detecting device comprising:
The sensor device includes a sensor bridge X01 and a sensor bridge Y01 whose fixed layer magnetization directions are orthogonal to each other,
Each of the sensor bridges X01 and Y01 is a spin-valve giant magnetoresistive element (having a fixed layer and a free layer, the fixed layer magnetization direction is fixed, and the free layer magnetization direction rotates according to the direction of the magnetic field. A magnetoresistive element) bridge circuit,
In the sensor bridges X01 and Y01, the pinned layer magnetization directions of the spin valve type giant magnetoresistive effect elements on the electrically adjacent sides are antiparallel,
A plane including the pinned layer magnetization direction of the sensor bridges X01 and Y01 is inclined with respect to a plane passing through the thickness center point of the multi-pole array surface of the stator and perpendicular to the multi-pole array surface,
By applying a voltage to each of the sensor bridges X01 and Y01, an output corresponding to an angle between the fixed layer magnetization direction and the free layer magnetization direction is obtained, and a position signal is obtained based on the output. It is characterized by.

(Third position detection device)
A third position detection apparatus according to the present invention includes a stator having a multi-pole array on a surface thereof, and a sensor device that translates with respect to the multi-pole array surface of the stator and detects the direction of magnetic flux from the stator. A position detecting device comprising:
The sensor device includes a sensor bridge X01 and a sensor bridge Y01 whose fixed layer magnetization directions are orthogonal to each other,
Each of the sensor bridges X01 and Y01 is a spin-valve giant magnetoresistive element (having a fixed layer and a free layer, the fixed layer magnetization direction is fixed, and the free layer magnetization direction rotates according to the direction of the magnetic field. A magnetoresistive element) bridge circuit,
In the sensor bridges X01 and Y01, the pinned layer magnetization directions of the spin valve type giant magnetoresistive effect elements on the electrically adjacent sides are antiparallel,
The center of the sensor device is away from the plane that passes through the thickness center point of the multi-pole array surface of the stator and is perpendicular to the multi-pole array face, in the thickness direction of the multi-pole array face of the stator,
By applying a voltage to each of the sensor bridges X01 and Y01, an output corresponding to an angle between the fixed layer magnetization direction and the free layer magnetization direction is obtained, and a position signal is obtained based on the output. It is characterized by.

(Fourth position detection device)
According to a fourth position detection apparatus of the present invention, a stator having a multi-pole array on the surface, a first that detects a direction of magnetic flux from the stator while moving parallel to the multi-pole array surface of the stator. The first sensor device includes a sensor bridge X01 and a sensor bridge Y01 whose fixed layer magnetization directions are orthogonal to each other, and the first sensor device includes the sensor device and the second sensor device. The sensor device 2 includes a sensor bridge X02 and a sensor bridge Y02 in which the fixed layer magnetization directions are orthogonal to each other, and each of the sensor bridges X01, Y01, X02, and Y02 is a spin valve type giant magnetoresistive element (fixed). Magnetoresistive element having a layer and a free layer, the fixed layer magnetization direction being fixed, and the free layer magnetization direction rotating according to the direction of the magnetic field) In the sensor bridges X01, Y01, X02 and Y02, the magnetization directions of the pinned layers of the spin-valve giant magnetoresistive elements on the electrically adjacent sides are antiparallel, and the sensor bridges X01, Y01, X02 And a plane including the pinned layer magnetization direction of Y02 is inclined with respect to a plane passing through the center of thickness of the multi-pole array surface of the stator and perpendicular to the multi-pole array surface, and the sensor bridges X01, Y01, X02 And a voltage applied to each of Y02, an output corresponding to an angle between the fixed layer magnetization direction and the free layer magnetization direction is obtained, and a position signal is obtained based on the output. .

  The plane including the fixed layer magnetization direction of the sensor bridges X01 and Y01 and the plane including the fixed layer magnetization direction of the sensor bridges X02 and Y02 are referred to as sensor surfaces (magnetic sensitive surfaces), respectively.

(Fifth position detection device)
According to a fifth position detection apparatus of the present invention, a stator having a multi-pole array on the surface, and a first that detects a direction of magnetic flux from the stator while moving parallel to the multi-pole array surface of the stator. A position detection apparatus comprising the sensor device and the second sensor device,
The first sensor device includes a sensor bridge X01 and a sensor bridge Y01 whose fixed layer magnetization directions are orthogonal to each other,
The second sensor device includes a sensor bridge X02 and a sensor bridge Y02 in which the fixed layer magnetization directions are orthogonal to each other,
Each of the sensor bridges X01, Y01, X02 and Y02 is a spin valve type giant magnetoresistive element (having a fixed layer and a free layer, the fixed layer magnetization direction is fixed, and the free layer magnetization direction is the direction of the magnetic field. A magnetoresistive element that rotates in response to
In the sensor bridges X01, Y01, X02 and Y02, the pinned layer magnetization direction of the spin valve type giant magnetoresistive effect element on the electrically adjacent sides is antiparallel,
The center of the first sensor device and the second sensor device is from a plane that passes through the thickness center point of the multi-pole array surface of the stator and is perpendicular to the multi-pole array surface, and from the plane of the multi-pole array surface of the stator. Apart in the thickness direction,
By applying a voltage to each of the sensor bridges X01, Y01, X02, and Y02, an output corresponding to an angle formed by the fixed layer magnetization direction and the free layer magnetization direction is obtained, and the position is determined based on the output. It is characterized by obtaining a signal.

  Two or four spin-valve giant magnetoresistive elements are used, each corresponding to two or four elements (elements) constituting an electric herb bridge circuit or full bridge circuit.

  In the fourth or fifth position detecting device, a first output signal (cosine signal) is obtained based on phase information detected independently by the sensor bridge X01 and the sensor bridge Y02, and the sensor bridge Y01 Based on an output signal detected independently by the sensor bridge X02, an electrical angle of 90 deg. It is preferable to obtain a delayed second output signal (sine signal).

  In the fourth or fifth position detection apparatus, an analog-digital conversion unit that converts the first output signal (cosine signal) and the second output signal (sine signal) into a digital signal, and the converted digital It is preferable to have a position calculation unit that calculates a signal into a position signal.

  The first sensor device and the second sensor device are separated from each other by approximately λ / 4 ± nλ / 2 in the phase of the multi-pole array of the stator (λ is the pitch of the same polarity magnetic poles of the multi-pole array, n is an integer). Further, it is preferable that the first sensor device and the second sensor device are installed at a position approximately λ / 2 apart from each other at the position of the multi-pole array of the stator.

  The relative positional relationship between the first sensor device and the second sensor device with respect to the north pole pair of the stator is preferably expressed as ± λ / 4 + Nλ / 2. The sensor bridge Y01 and the sensor bridge Y02 are arranged such that the fixed layer magnetization direction is along the direction of the multi-pole array of the stator, and the fixed layer magnetization direction of the sensor bridge X01 and the fixed layer of the sensor bridge X02 are arranged. It is desirable that the position is different from the magnetization direction by λ / 4 or λ / 4 ± nλ / 2 (n is an integer).

(Sixth rotation angle detection device)
A sixth position detection apparatus of the present invention includes a stator having a multi-pole array, and a sensor device that translates with respect to the multi-pole array surface of the stator and detects the direction of magnetic flux from the stator. The sensor device includes a plurality of spin-valve giant magnetoresistive elements (having a fixed layer and a free layer, the fixed layer magnetization direction is fixed, and the free layer magnetization direction is a magnetic field A magnetoresistive element that rotates according to the direction), and the magnitude of the amplitude of magnetic flux density components orthogonal to each other in the magnetosensitive surface is obtained by intersecting the magnetic flux with the magnetosensitive surface. The sensor device is provided with respect to the stator so as to be equal.

  Here, the stator having a multi-pole array may be any one that is magnetized so that at least two N poles and two S poles are aligned in one direction. Examples of the stator include a magnet array in which a plurality of magnets having one magnetic pole are arranged on a straight line, a magnet array in which a plurality of magnets magnetized in multiple poles are arranged on a straight line, and a Halbach magnetic circuit on a straight line. And a plurality of magnet arrays arranged in the above.

(Seventh position detection device)
A seventh position detection apparatus of the present invention includes a stator having a multi-pole array, and a sensor device that translates with respect to the multi-pole array surface of the stator and detects the direction of magnetic flux from the stator. The sensor device includes a plurality of spin-valve giant magnetoresistive elements (having a fixed layer and a free layer, the fixed layer magnetization direction is fixed, and the free layer magnetization direction is a magnetic field A magnetoresistive element that rotates in accordance with the direction), and at the position where the amplitude ratio K ₀ = B _⊥0 / B _{// 0} ≠ 1 of the spatial magnetic flux density, The sensor device is provided with respect to the stator so that the amplitude ratio K _eff = B _{⊥ eff0} / B _{// eff0} is 1.

(Linear drive device)
The linear drive device of the present invention includes any one of the position detection devices and a coil provided on the movable element and facing the multi-pole array surface of the stator.

  Since the position detection device of the present invention has high position detection accuracy, it is suitable for a linear drive device.

(Embodiment 1)
FIG. 1 shows a position detection device that detects the position of the sensor device 12 a with respect to the stator 11. FIG.1 (b) is AA sectional drawing of Fig.1 (a). The stators 11 are connected in one row so that the blocks of sintered magnets are adjacent to each other, and are arranged at λ / 2 so that the N poles and the S poles are alternated to constitute a multi-pole row. A side surface (surface on the side where magnetic flux enters and exits) perpendicular to the direction of magnetization represented by a thick arrow is a multi-pole array surface. In this configuration, the sensor device 12a corresponds to a mover, and is arranged so as to be able to translate along the arrangement direction of the magnetic poles of the stator 11. When the sensor device is translated, the sensor device receives a rotating magnetic field from the multi-pole array, so that the free layer rotates and an output corresponding to the position can be taken out from the sensor device. Details of the electronic circuit connected to the sensor device will be described later. The distance between the plane passing through the center of the thickness of the stator and orthogonal to the multi-pole array surface and the magnetosensitive surface of the sensor device 12a is h ′ ≠ 0. Distance between the center (center of the sensitive surface) of the plane parallel to the thickness center as and multi-pole column surface of the stator and the sensor device 12a is r _1. Within the magnetic sensing surface of the sensor device, the magnitude of the magnetic flux density component along the magnetic pole arrangement direction (multi-pole array direction) and the magnitude of the magnetic flux density component orthogonal to the magnetic pole arrangement direction are substantially equal. Further, the sensor device 12a is arranged with a distance h ′ shifted in the Z-axis direction. When this position detection device is applied to a linear drive device, the position of the mover of the linear drive device can be detected with high accuracy.

(Comparative form 1)
FIG. 2 shows a position detection device in which the sensor device 12a is arranged directly beside the multi-pole array (χ = 0, h ′ = 0). FIG.2 (b) is AA sectional drawing of Fig.2 (a). Configurations other than h ′ = 0 are the same as those in FIG. However, in this arrangement, the magnitude of the magnetic flux density component along the magnetic pole arrangement direction (multi-pole array direction) and the magnitude of the magnetic flux density component orthogonal to the magnetic pole arrangement direction within the magnetic sensing surface of the sensor device. Therefore, even if the sensor device is translated and its position is obtained, the error of the linear displacement amount is large.

(Embodiment 2)
FIG. 3 shows a position detection apparatus in which the sensor device 12a is arranged beside the multi-pole array (χ ≠ 0, h ′ = 0). FIG.3 (b) is AA sectional drawing of Fig.3 (a). The configuration is the same as that of FIG. 1 except that the magnetosensitive surface of the sensor device 12a is tilted by χ with respect to a plane that passes through the thickness center point of the stator and is orthogonal to the multi-pole array surface. However, in the magnetic sensing surface of the sensor device, the magnitude of the magnetic flux density component along the magnetic pole arrangement direction (multi-pole array direction) is almost equal to the magnitude of the magnetic flux density component orthogonal to the magnetic pole arrangement direction. Therefore, the error of the linear displacement amount can be suppressed to the same extent as in the first embodiment.

(Embodiment 3)
FIG. 4 shows a position detection apparatus in which a sensor device 12b is added to the configuration of FIG. When the second sensor device 12b is arranged so that the centers of the magnetic sensitive surfaces are spaced apart from each other by λ / 4 with respect to the first sensor device 12a, the two sensor devices are the same as in FIG. . Since the error component is canceled when the outputs of the two sensor devices are combined, the error of the linear displacement amount can be made smaller than that in the comparative form.

(Embodiment 4)
FIG. 5 shows another position detection apparatus that detects the position of the sensor device 12a with respect to the stator 11. 4 except that the second sensor device 12b is arranged so that the centers of the magnetic sensitive surfaces are separated from each other by 3λ / 4 with respect to the first sensor device 12a. In the case of detecting the amount of displacement related to linear movement, the positional relationship between the two sensor devices (the positional relationship between the centers of the magnetic sensitive surfaces) is defined by λ / 4 ± nλ / 2. Therefore, the same effect can be obtained even if the second sensor device is arranged at a position separated by 3λ / 4 as shown in FIG.

(Embodiment 5)
With respect to the configuration of FIG. 5, when the sensor devices 12a and 12b are both translated by h ′ in the z-axis direction, a displacement detection device that further suppresses the error of the linear displacement amount of FIG. 1 is obtained.

(Embodiment 6)
With respect to the configuration of FIG. 5, when the sensor devices 12a and 12b are both tilted by χ as shown in FIG. 3, a displacement detection device that suppresses the error of the linear displacement amount to the same level as in FIG. 5 is obtained.

(Positional relationship between stator and mover)
FIG. 6 shows an example of the positional relationship between the multi-pole array of the stator and the sensor device of the mover. FIG. 6A is a top view of the position detection device as in FIGS. 1A to 5A, and FIG. 6B corresponds to a cross-sectional view taken along line AA in FIG. In (a), a thick arrow represents the magnetization direction for each block, and a thin curved arrow represents a magnetic field line. FIG. 6B shows the arrangement of two types of sensor devices 12a ″ and sensor devices 12a ″. In the sensor device 12a ′, the center of the magnetic sensitive surface of the sensor device is arranged on the XY plane with h ′ = 0, and the magnetic sensitive surface is inclined by the sensor inclination angle χ with respect to the XY plane. The sensor device 12a ″ is at the position of the sensor arrangement angle φ ′ and is inclined χ ′ with respect to the XY plane. The center of the sensor device 12a ″ is h ′ away in the Z-axis direction from a plane passing through the thickness center point of the stator 11 and perpendicular to the multi-pole array direction (a plane parallel to the XY plane). At the position of the sensor device 12a ″, the direction of the magnetic flux is inclined ε ′ from the X axis. The thickness t of the stator magnet is a dimension in the Z-axis direction. The thickness center point of the stator 11 is a point where the center of the XY cross section of the stator intersects the center of the Z axis cross section, and corresponds to the origin of the XYZ axis. The relative positional relationship between the magnet and the sensor device in FIG. 6 is basically the same as the configuration in which the sensor device is shifted in the Z-axis direction in FIG. 9, but the rotation center of the magnet does not exist. The reference of the sensor arrangement angle φ is regarded as the center of the X axis of the magnet and the center of the Z direction.

(Embodiment 7)
FIG. 7A is a cross-sectional view (XY cross-sectional view) of a linear drive device that translates the mover 49 along the multi-pole array direction of the stator 40. In the stator 40, ring magnets 41 made of NdFeB-based sintered permanent magnets are stacked in multiple stages, and a nonmagnetic shaft 42 is mounted in the through hole of the ring. Adjacent ring magnets constitute a multi-pole array so that the magnetization direction (thick arrow) is reversed in the Y direction. The magnetization direction of each ring magnet corresponds to the axial direction of the ring magnet. The mover 49 includes a drive cylinder that generates a magnetic field and a detection cylinder having a sensor device. The drive cylinder portion is provided with a coil 44 for exciting winding on a soft magnetic yoke 43. The movable element 49 is driven or stopped by controlling the exciting current flowing through the coil and the magnetic field generated thereby.

  The detection cylindrical portion includes a cylindrical nonmagnetic portion 45a that supports the sensor devices 12a and 12c, a cylindrical nonmagnetic portion 45b that supports the sensor devices 12b and 12d, and a rectangular shape provided on the outer periphery of the nonmagnetic portion 45b. Nonmagnetic part 46 and sensor device 12e. A driving cylindrical portion is fixed between the nonmagnetic portions 45a and 45b, and the three members form an integral cylindrical shape. In the sensor device, the amplitude of the magnetic flux density component along the magnetic pole arrangement direction (multi-pole array direction) and the amplitude of the magnetic flux density component orthogonal to the magnetic pole arrangement direction within the magnetic sensing surface of the sensor device Are fixed to the non-magnetic part 45a or 45b so that they are substantially equal.

  The sensor device 12e provided in the non-magnetic portion 46 is fixed in the same manner as the stator, detects the reference magnetic pole 47 provided only at one location on the non-magnetic reference rail 48, and controls the mover by using it as a position reference. Used for. The reference rail 48 does not move like the stator. The sensor device 12e can determine the number λ detected by the sensor devices 12a to 12d. When the position information obtained from these sensor devices is used to control the drive cylindrical portion, the mover can be accurately driven or stopped, and a highly accurate linear drive device is obtained.

  In FIG. 7, sensor devices 12a to 12d and 12e are the same as the sensor devices 12a and 12b shown in FIGS. In FIG. 7, the sensor devices 12a and 12b are fixed so as to have a positional relationship of 2λ + 3λ / 4 in the multi-pole array direction of the stator. Although not shown, the electronic circuit connected to the sensor device constitutes the circuit of FIG. In the detection cylindrical portion, the inner surface of the through hole that passes through the ring is processed so as to slide smoothly with the shaft, but no member that holds the position is provided except for passing through the ring.

  Further, in the configuration of FIG. 7A, the stator 40 can be replaced with a column magnet 41b stacked in multiple stages as shown in FIG. 7B. The cylindrical magnet 41b is preferably stacked and fixed in a nonmagnetic cylinder. Further, the yoke 43 may be replaced with a nonmagnetic material (that is, a bobbin) having the same shape. The combination of the ring magnet 41 and the non-magnetic shaft is, for example, a non-magnetic shaft passed through a radially magnetized ring magnet or a soft magnetic shaft passed through a ring magnet magnetized on the outer peripheral surface. Can be replaced by something. Further, some or all of the yoke or the like may be replaced with a non-magnetic material. These changes can be made as appropriate based on the relationship between the number of turns of the coil, the current passed through it, the weight of the mover, the required driving force, and the like.

(Embodiment 8)
FIG. 8 is a cross-sectional view (XZ cross-sectional view) of another linear drive device that translates the mover 59 along the multi-pole array direction (Y direction) of the stator 50. The stator 50 includes U-shaped yokes composed of soft magnetic side plate yokes 52a and 52b and a substrate yoke 52c, magnet rows 51a and 52b fixed to the inside of the side plate yoke, and the side plate yoke and the substrate. Reinforcing members 58a and 58b are provided to increase the strength for fixing the yoke, and a magnetic circuit is formed by the yoke and the magnet. The mover 59 includes an exciting coil 54, a frame 53 and a table 56 that support the coil 54, guide portions 57a and 57b that support the table 56 movably in the Y direction with respect to the stator 50, and a sensor device. 12a and 12b. The sensor device 12 a is directly fixed to the surface of the frame 53, and the sensor device 12 b is supported on the table 56 through a support substrate 55.

In FIG. 8, the sensor device is disposed at a position where the magnetic field from the magnet applied to the sensor device becomes a rotating magnetic field when the mover moves in parallel with respect to the magnetic circuit described above.
Separate aspects are illustrated on the left and right sides of the line BB. The configuration on the left side detects the magnetic field in the region from the magnetic pole, and is arranged so that the lines of magnetic force are inclined with respect to the magnetosensitive surface of the sensor device. The configuration on the right side detects the magnetic field in the region in the middle of the magnetic pole, and is arranged so that the magnetic sensitive surface of the sensor device is inclined with respect to the magnetic field lines. For both configurations, the magnitude of the amplitude of the magnetic flux density component along the magnetic pole arrangement direction (multi-pole array direction) and the magnitude of the magnetic flux density component orthogonal to the magnetic pole arrangement direction in the magnetic sensing surface of the sensor device The sensor devices are arranged so as to be equal.

  In FIG. 8, the sensor devices 12c, 12d, and 12e are displayed by dotted lines as another example of the location where the sensor device is installed. These sensor devices are fixed to the end face of the frame 53 in the Y-axis direction. In the case of the sensor device 12c, since it receives a parallel magnetic field (magnetic field whose direction changes alternately) formed between the magnet arrays 51a and 51b, the magnetosensitive surface is inclined with respect to the XY plane of coordinates. In the case of the sensor devices 12d and 12e, the magnetic field lines are bent near the end of the magnet array, and therefore the magnitude of the amplitude of the magnetic flux density component along the magnetic pole array direction (multi-pole array direction) and the magnetic pole Of the positions where the amplitudes of the magnetic flux density components orthogonal to the arrangement direction are substantially equal, a position where the sensor device can be substantially parallel to the XY plane is selected and arranged.

  It is not easy to describe the phase relationship between the mover and the sensor device that translates in a straight line and the stator having a multi-pole array in detail with mathematical expressions. Therefore, an angle detection principle of a rotation angle detection apparatus including a rotating magnet rotor and a fixed sensor device will be described as a convertible model. First, consider the case where the outer diameter of the ring magnet is extremely large and the number of poles is very large. In this case, when viewed from the sensor device side, the rotation of the ring magnet can be considered to be equivalent to a state in which a large number of magnetic poles arranged in a line are moving linearly, and the amount of linear displacement can be detected. Therefore, the description of the linear displacement amount can be mutually replaced with the description of the rotation angle detection.

(1) Rotation angle detection principle The angle detection principle of the rotation angle detection device of the present invention will be described for a magnet rotor having 2N poles (N is a natural number) in the rotation direction. In other words, this magnet rotor has N pole pairs of magnets, and has N-fold axial symmetry. Mechanical angle theta _m of a reference angle is represented by the formula (1) by an electrical angle theta _el. In particular, in the case of two poles (N = 1), it is expressed by Expression (2), and the electrical angle and the mechanical angle are equal.

For simplicity, an infinitely long magnet rotor is assumed (ie, the magnetic field is uniformly distributed in the axial direction). When the magnetic field generated from the magnet rotor at this time is represented by a space vector as a function of the measurement position (r, θ), the radial magnetic field component H _r and the rotational magnetic field component H _θ are expressed by the following equations (3-1). ) And equation (3-2).

Further, Table in formula (3-1) and (3-2), the fundamental wave component is not zero (i.e. _{A 1} is not zero), r is large to some extent third or higher order harmonics by _{A 1} When it is smaller than the fundamental wave to be made, it can be simplified as shown in equations (4-1) and (4-2).

This means that the direction of the magnetic field changes by θ _{el when the} magnet rotor moves by an angle θ _{m with} respect to the measurement point. That is, it means that the rotation angle of the magnet rotor can be measured by detecting the direction of the magnetic field regardless of the magnitude of the magnetic field.

(2) Spin-valve giant magnetoresistive effect element As an element (element) for realizing the magnetic sensor based on the above principle, there is a spin-valve giant magnetoresistive effect element. The magnetoresistive effect element is an element that changes its resistance value by sensing a magnetic field, and is usually used to detect a magnetic field component in the anisotropic direction of the element (element) one-dimensionally. We focus on the resistance change when the element is placed in a rotating magnetic field. An element (element) that changes the resistance of cos α (α is the angle between the magnetization of the fixed layer and the magnetization of the free layer) with respect to the rotating magnetic field, and an element (element) that changes the resistance of the opposite sign (−COS α) Or a combination of elements. By applying an element that outputs a voltage proportional to COSα when a DC voltage is applied, R _res is output as shown in Equation (5). In Expression (5), δ is a resistance change rate.

When a spin valve type giant magnetoresistive element is used, the magnetization direction of the fixed layer is determined by the manufacturing process and does not change with the movement of the external magnetic field. On the other hand, since the magnetization of the free layer is the same as the direction of the external magnetic field, the resistance change depends only on the direction of the external magnetic field, and an operation that does not depend on the magnitude of the absolute value of the magnetic field is possible. As described above, in the spin valve type giant magnetoresistive effect element, an output corresponding to the angle between the magnetic field and the magnetosensitive direction can be obtained, so that a waveform output for one period can be obtained with respect to one period of the electrical angle. The absolute angle can be obtained by tangent calculation. The magnetization of the free layer rotates smoothly according to the magnetic flux applied from the magnet rotor. For this reason, it is suitable as an element (element) used in the present invention. The arc tangent calculation means that tan θ _m = y from the first sinusoidal output signal x (for example, a signal obtained from the sensor bridge X01) and the second sinusoidal output signal y (for example, a signal obtained from the sensor bridge Y01). This is to obtain θ _m that is a relationship of / x.

In the above has been described as the amplitude of the H _r and H _theta is equal, when the axial dimension of the magnet rotor (i.e. magnet rotor thickness) is finite, the amplitude is not equal. Hereinafter, an angle calculation method when the amplitudes are not equal will be described. When the sensor device is installed near the outer periphery of the permanent magnet with the axis of rotation as the origin of coordinates, the optimum arrangement is obtained as follows. In a coordinate system (X, Y, Z) with the center of the magnet rotor as the origin, a spin-valve giant magnet having a pinned layer magnetization direction parallel and antiparallel to the interior (described later) at position (X, Y, Z). A sensor device 12a to which a resistance effect element is bridge-connected is disposed. The fixed layer magnetization direction of the sensor bridge X01 is arranged parallel to the X axis, and the fixed layer magnetization direction of the sensor bridge Y01 is arranged parallel to the Y axis (tangential direction of magnet rotation). Assuming that an angle formed by an XY plane and a line connecting the origin of the magnet and the center of the sensor device is a sensor arrangement angle φ, X, Y, and Z when the magnet rotor is rotated by θ _{m in the} circumferential direction The magnetic flux components B _X , B _Y and B _{Z in the} direction are expressed by Expression (6-1), Expression (6-2) and Expression (6-3), respectively. However, the magnet rotor was considered to approximate one magnetic moment m.

At this time, when _{BY is represented} by B _// and the remaining component orthogonal to the Y axis is represented by B _⊥ , Equations (7-1) and (7-2) are obtained.

B _{// 0} is the amplitude of B _// and B _⊥0 is the amplitude of B _⊥ . A spatial magnetic flux density amplitude ratio K ₀ that is an amplitude ratio of these is expressed by Expression (8).

In the case of Z _s = 0, since B _z = 0, both B _// and B _存在 exist in the XY plane. When Z _s ≠ 0, that is, when a sensor device is installed at a certain sensor arrangement angle φ (excluding φ = 90 deg.), A plane inclined ε from the XY plane at the center of the sensor device (hereinafter referred to as ε plane) A rotating magnetic field having a spatial magnetic flux density amplitude ratio K ₀ is obtained.

On the other hand, φ = 0 deg. , The spatial magnetic flux density amplitude ratio K ₀ = B _⊥0 / B _{// 0} = 2 and 90 _deg . Since the magnetic fluxes having different phases are received, the sensor output does not become a sine wave, the output of the sensor bridge X01 is almost a trapezoidal wave, and the output of the sensor bridge B01 is almost a triangular wave. As a result, ± 20 deg. A very large error will occur. At this time, when the magnetization direction of the fixed layer of the sensor bridge Y01 is tilted by χ, the Y direction component B _{// eff of} the magnetic flux density effectively received by the spin valve type giant magnetoresistive element in the sensor device is orthogonal to it. The component B _⊥eff and the effective magnetic flux density amplitude ratio K _eff in the direction to be expressed are expressed by Expression (9-1), Expression (9-2), and Expression (9-3), respectively. B _{// EFF0} is the amplitude of the _{B // eff,} B ⊥eff0 is the amplitude of _B ⊥eff.

It is preferable that the amplitude ratio K _eff = B _⊥eff0 / B _// orthogonal effective magnetic flux density is in a state where _eff0 is 1, that is, the amplitude is equal. A preferred range of K _eff is K _eff = 0.93~1.08, more preferably K _eff = 0.96~1.04, ideally K _eff = 1.0.

χ is the optimum sensor tilt angle χ _best [in equation (9-3), χ is χ _best when K _eff = 1.0. ], No angular error occurs even if the pinned layer magnetization direction of the sensor device is rotated in the magnetosensitive plane. This is because the pinned layer magnetization direction of the spin valve type giant magnetoresistive effect element is orthogonalized, and if the pair of sensor bridges are in a biaxial orthogonal relationship, the pinned layer magnetization direction is rotated within the magnetosensitive surface. also only the phase of the output of the sensor bridge is advanced or delayed with respect to theta _m, the output of the amplitude and the output accuracy is because no effect. As described above, the spin valve giant magnetoresistive element detects the direction of magnetic flux having three-axis components of Bx, By, and Bz.

The above-described equations (9-1) to (9-3) indicate that an arbitrary effective magnetic flux density amplitude ratio smaller than K ₀ can be obtained by tilting the sensor device by χ. For example, χ = 60 deg. As a result, the effective magnetic flux density amplitude ratio K _eff between B _⊥eff and B _{// eff} is 1.0. At this time, the outputs of the sensor bridges X01 and Y01 in the sensor device are sinusoidal, and no angle error occurs even if the arctangent calculation is performed.

Here, the magnet rotor is approximated to the magnetic moment m. However, since a disk-shaped magnet having a thin flat shape in the direction of the rotation axis is actually used, the demagnetizing factor of the magnet rotor and the mounting position of the sensor device Depends on the spatial magnetic flux density amplitude ratio K ₀ . However, when the mounting position of the sensor device is separated so that the gap distance from the magnet rotor surface is several mm, it can be approximated by the magnetic moment m.

As described above, in the case of a magnet with two poles, the optimum sensor arrangement angle φ _best and the optimum sensor inclination angle χ _best that the effective magnetic flux density amplitude ratio K _eff is 1 are obtained by an analysis that can approximate the magnetic moment m. Can be sought. However, when the magnetizing pattern is complicated, such as a ring magnet magnetized with multiple poles, analysis with the magnetic moment m becomes difficult. In such a case, the spatial magnetic flux density amplitude ratio K ₀ is obtained from the magnetic flux density component at an arbitrary point by magnetic field analysis such as a finite element method, and the sensor device is _adjusted so that the effective magnetic flux density amplitude ratio K _eff becomes 1. By tilting χ from the XY plane, it is possible to configure a rotation angle detection device with little angle error. Similarly, even if the sensor device is moved in the Z direction from the XY plane so that the effective magnetic flux density amplitude ratio K _eff becomes 1, it is possible to configure a rotation angle detection device with little angle error.

(Importance of 2 devices and 4 bridges)
In order to obtain an angle signal representing the rotation angle by the inverse tangent calculation, two signals of a sine signal and a cosine signal are required. As for the outputs of the sensor bridge X01 and the sensor bridge Y01, the respective signals correspond to the cosine signal and the sine signal, and it is possible to obtain the rotation angle output only with these two sensor bridges. However, as shown in the above equation (3), the magnetic flux density from the magnet rotor does not necessarily include only the fundamental wave component but also includes harmonics. Further, as shown in equations (9-1) to (9-2), when the sensor device is not provided with the tilt angle χ or the axis shift amount h, the magnetic flux in the radial direction and the rotational direction at the installation position of the sensor device. Since the density is different, the output signal further includes harmonics. That is, when measuring the output of the sensor device in the vicinity of the magnet rotor, when the rotation angle of the magnet rotor is on the horizontal axis and the output of the sensor device is on the vertical axis, the fixed layer magnetization direction is in the radial direction. The output of the sensor bridge has a trapezoidal waveform (a waveform in which the sin curve is trapezoidally distorted), and the output of the sensor bridge in which the fixed layer magnetization direction is in the rotational direction is a triangular waveform (a waveform in which the sin curve is distorted in a triangle) become. For this reason, the electrical angle is 90 deg. By adding the outputs X02 and Y02 from the second sensor device installed at a distant position, it becomes possible to increase the fundamental wave component and cancel and reduce the harmonic component. By such signal processing, the error of the angle signal can be further reduced. The first sensor device and the second sensor device do not necessarily have an electrical angle of 90 deg. It is not necessary to install in the adjacent part. For example, from the first sensor device 12a, the second sensor device 12b has an electrical angle of 90 deg. +180 deg. When installed at a distant position, the fundamental wave of each sensor bridge output is expressed by equations (16-1) to (16-4) with reference to the output of the sensor bridge X01.

  Here, it is necessary to invert X02 and differentially process the Y01 output and the X02 inverted output. The X01 output and the Y02 output can be input to the input terminal of the differential amplifier without inversion processing. It is also possible to detect the rotation angle with the same accuracy by changing the arrangement and connection without changing the phase relationship. Therefore, regarding the installation positions of the first sensor device and the second sensor device, the electrical angle is 90 deg. And an electrical angle of 90 ± 360 deg. The relative position is not limited to 90 ± 180 ndeg. Any angle (n is an integer) can be taken. However, if the distance between the sensor devices is increased in this way, the position detection accuracy may be limited due to the influence of the assembly accuracy when the position detection device is attached to the linear drive device. Therefore, it is more preferable to reduce the interval between the sensor devices.

As described above, it has been described that the rotation angle of the ring magnet can be measured with high accuracy by tilting the sensor device, translating in the axial direction, and arranging a plurality of sensor devices. Consider a case where the outer diameter of the ring magnet is extremely large and the number of poles is very large. In this case, when viewed from the sensor device side, the rotation of the ring magnet can be considered equivalent to the linear movement of the multi-pole array, and the amount of linear displacement can be detected. FIG. 6 shows the positional relationship between the magnets of the multi-pole array and the sensor device. When detecting the amount of linear displacement, it is necessary to obtain λ in FIG. Since the above explanation is a method for detecting the angle θ _el or θ _m , it is necessary to convert the angle into a distance when obtaining λ. If the radius of the ring magnet is r ₀ and the number of poles is 2N poles (where N is an integer equal to or greater than 2), the distance λ per cycle of the electrical angle can be obtained as 2r ₀ π / N. For example, in the case of a magnet of 100 mm in diameter and 8 poles, the distance per cycle of electrical angle is λ = 39.27 mm.

(Reference form 1, 2)
9A and 9B show a rotation angle detection device configured using a multipolar magnet rotor 21 and one sensor device 12a as a reference mode 1. FIG. FIG.9 (b) is AA sectional drawing of Fig.9 (a). Although it fixes through the shaft to the inner peripheral surface side of the magnet rotor 21, illustration is abbreviate | omitted. The sensor device is arranged with a sensor tilt angle χ = 0 and h = 0. As a reference mode 2, FIG. 10 is configured in the same manner as the rotation angle detection apparatus shown in FIG. 9 except that the sensor device is arranged with the sensor tilt angle χ tilted.

The positional relationship between the magnetic flux of the magnet rotor (four or more poles) and the sensor device is shown in FIGS. In FIG. 11A, the magnetization direction in each magnetic pole of the ring-shaped permanent magnet 31 of the magnet rotor is represented by a straight thick arrow, and the magnetic flux generated from the magnetic pole surface is represented by a curved thick arrow. The sensor device 32f receives a magnetic flux in the X-axis direction. λ corresponds to one wavelength of a sine signal when measuring the surface magnetic flux density distribution (360 deg. in electrical angle), and in the ring-shaped permanent magnet 31, corresponds to the circumferential length of a pair of magnetic pole surfaces, as shown in FIG. In the stator, this corresponds to the distance between magnetic poles of the same polarity. r ₁ is the distance between the center of the magnetic sensitive surface of the sensor device 32 f and the surface of the ring-shaped permanent magnet 31 when viewed along the radial direction of the ring-shaped permanent magnet 31. At this time, the sensor device 32f receives the magnetic flux in the X-axis direction. The ring-shaped permanent magnet 31 is 90 deg. The sensor device 32f receives the magnetic flux in the Y-axis direction when it is rotated only by the amount of rotation. The Z axis is an axis that passes through the center o of the hole of the ring-shaped permanent magnet 31 and is orthogonal to the rotation plane of the magnet, and corresponds to the rotation axis of the magnet rotor. θ _m is a mechanical angle representing the mechanical rotation of the magnet rotor.

  FIG. 11B shows the arrangement of two types of sensor devices 32f and sensor devices 32f '. In the sensor device 32f, the center of the magnetic sensitive surface of the sensor device is arranged on the XY plane with Z = 0, and the magnetic sensitive surface is inclined by the sensor inclination angle χ with respect to the XY plane. The sensor device 32f 'is at the position of the sensor arrangement angle φ' and is inclined by χ 'with respect to the XY plane. The center of the sensor device 32f 'is h' away from the plane passing through the center point of the thickness of the ring magnet 31 and perpendicular to the rotation axis in the Z-axis direction. At the position of the sensor device 32 f ′, the direction of the magnetic flux is inclined ε ′ from the X axis. The thickness t of the ring magnet is a dimension in the Z-axis direction. The center point of the thickness of the ring magnet 31 is the point where the center of the XY cross section of the ring magnet intersects the center of the Z axis cross section, and corresponds to the origin of the XYZ axis. A shaft serving as a rotating shaft can be fixed to the hole of the ring magnet.

  As shown in FIGS. 12A to 12F, the position detection apparatus of the present invention includes two spin valve type giant magnetoresistive effect elements as sensor devices 12a and 12b shown in FIGS. Two full bridge circuits are formed, ten terminals 23 are formed using a nonmagnetic lead frame, and sensor devices 12a and 12b molded with a resin material are used.

  As shown in FIG. 12A, in one sensor device 12a, a spin valve type giant magnetoresistive effect element having any one of the X, Y, -X, and -Y directions as the fixed layer magnetization direction is provided as an element. 8 built-in. The thick arrow in the figure represents the fixed layer magnetization direction in one element. Four substrates in which two elements having the same fixed layer magnetization direction are formed are used. Among these eight elements, the elements having the X and −X directions as the fixed layer magnetization directions are connected as shown in the circuit diagram of FIG. 12B to constitute the sensor bridge X01. Similarly, elements having the Y and −Y directions as the fixed layer magnetization directions are connected as shown in the circuit diagram of FIG. 12C to form a sensor bridge Y01. The X and −X directions are antiparallel, the Y and −Y directions are antiparallel, and the X and −X directions are formed to be orthogonal to the Y and −Y directions.

  Similarly, as shown in FIG. 12D, in another sensor device 12b, a spin-valve type giant magnetoresistive effect element in which any one of the X, Y, -X, and -Y directions is a fixed layer magnetization direction. Are built-in. Elements whose X and −X directions are fixed layer magnetization directions are connected as shown in the circuit diagram of FIG. 12E, and constitute a sensor bridge X02. Similarly, the elements having the Y and −Y directions as the fixed layer magnetization directions are connected as shown in the circuit diagram of FIG. 12F to form a sensor bridge Y02. The sensor bridge X01 has a fixed layer magnetization direction in a direction perpendicular to the arrangement direction of the multi-pole array, the sensor bridge Y01 has a fixed layer magnetization direction in the arrangement direction of the multi-pole array, and the sensor bridge X02 has a multi-pole array direction. The sensor device is provided in the position detection device so that the fixed layer magnetization direction is in a direction orthogonal to the arrangement direction, and the sensor bridge Y02 has the fixed layer magnetization direction in the arrangement direction of the multi-pole array.

  In FIG. 12A, two spin-valve giant magnetoresistive elements 22, 22b, 22c and 22d are connected as shown in FIGS. 12B and 12C, and 10 terminals 23 formed by a lead frame are connected to The sensor device 12a is formed by connecting and molding integrally with resin. The thick arrows of the spin-valve giant magnetoresistive elements 22a and 22d are arranged so as to be orthogonal to the arrangement direction of the multi-pole array (that is, the movement direction of the sensor device) in FIG. In the bridge circuit of FIG. 12B, a constant DC voltage Vccx is applied and Vx1 and Vx2 are output from the midpoint of the bridge connection. Gndx1, Gndx2, Gnddy1, and Gndy2 are ground (ground potential). In FIG. 12 (a), four elements in which two elements having the same fixed layer magnetization direction are formed on one substrate are used, but eight elements are formed on one substrate or one element. You may use eight board | substrates in which it was formed. It is also possible to cut out elements one by one from a wafer in which all the fixed layer magnetization directions are formed in the same direction, arrange them as shown in FIG. 12A, and wire them so as to form a bridge. Although not shown, each spin-valve giant magnetoresistive element shown in FIG. 12A is formed on a nonmagnetic substrate with a base layer (Cr) / fixed layer (Co / Ru / Co). / Cu layer / free layer (Co / NiFe) / cap layer (Ta) in this order and patterned, an electrode film for energization is provided, and an insulating coating is applied. Alternatively, the pinned layer magnetization direction of the element can be determined using a self-pinned spin-valve giant magnetoresistive element.

  As described above, each sensor device includes two sensor bridges whose fixed layer magnetization directions are orthogonal to each other. The fixed layer magnetization direction of each sensor bridge is determined by a lithography technique or a machine having ultra-precision positioning accuracy. By forming elements by component arrangement, positioning is performed with higher accuracy than when sensor devices are mounted on a printed circuit board or the like. By making the fixed layer magnetization directions orthogonal, position detection can be performed with high accuracy. Further, by using the first sensor device and the second sensor device having the same specifications, it is possible to avoid an error in mounting that occurs when sensor devices having different specifications are used. The thing of the same specification is the sensor device produced on the same conditions. For example, when an element is manufactured by a wafer process, a range in which manufacturing conditions are the same even if formed on wafers of different lots is referred to as the same specification.

As shown in FIGS. 12A to 12F, each sensor device has two bridge circuits, and a DC voltage is applied between Vcc and Gnd so that it is within the magnetic field of the magnet rotor. By placing the sensor device, differential outputs can be obtained between Vx1 and Vx2 and between Vy1 and Vy2. The differential outputs output from the four sensor bridges X01, Y01, X02 and Y02 are amplified and amplified by differential amplifiers (operational amplifiers 26a, 26b, 26c, 26d, 26e and 26f) as shown in FIG. The first output signal output from the X01 and Y02 and the second output signal output from the amplified Y01 and X02 are digitally converted by the AD converter 27 and calculated by the position calculator 28. Finally, a signal (position signal) corresponding to the electrical angle is output. In this case, the phase difference between the first output signal and the second output signal is 90 deg. When the first output signal is regarded as a cosine signal, the second output signal can be regarded as a sine signal, and an arctangent operation (tan ⁻¹ ) is performed from these signals. , Position signals corresponding to 0 to λ are obtained.

  In this specification, the sensor bridge corresponds to a combination of four elements (spin valve type giant magnetoresistive effect element) in an electric circuit bridge. Further, a device equipped with two sensor bridges is called a sensor device. A configuration in which the stator and the sensor device are opposed to each other is referred to as a position detection device (unit). A unit obtained by combining a plurality of sensor devices so as to be attached to the position detection device is referred to as a module.

  The present invention will be described in more detail with reference to the following examples using the drawings, but the present invention is not limited thereto.

Example 1
FIG. 14 shows the relationship between the displacement amount and the displacement amount error when the sensor device 12a is translated in the configuration of the first embodiment with λ = 45 mm, r ₁ = 6 mm, and h ′ = 6 mm. The error of the linear displacement amount of the sensor device could be reduced to about 1/7 as compared with a comparative example described later.

(Comparative example)
FIG. 15 shows the relationship between the displacement amount and the displacement amount error when the sensor device 12a is translated as the same conditions as in Example 1 except that h ′ = 0 mm in the configuration of the comparative form. The error of the linear displacement amount exceeds ± 1.5 mm, and it is difficult to measure the displacement amount with high accuracy.

(Example 2)
In FIG. 16, in the configuration of the third embodiment, λ = 45 mm (that is, the distance λ / 4 between the centers of the magnetic sensitive surfaces is 11.25 mm), r ₁ = 6 mm, h ′ = 0 mm, χ = The relationship between the displacement amount and the displacement amount error when the sensor devices 12a and 12b are translated together as 0 mm is shown. The error of the linear displacement amount of the sensor device was able to be reduced to ± 0.3 mm or less in Example 2 compared to ± 1.7 mm in the comparative example. It can be seen that the accuracy can be improved by using two sensor devices.

(Example 3)
The relative positional relationship between the two sensor devices of the third embodiment was not changed, and a similar experiment was performed with both h ′ = 6 mm. As a result, further improvement in accuracy was confirmed.

(Reference Examples 1 and 2)
In Reference Embodiment 1, the distance from the outer circumference of the magnet rotor to the center of the sensor device is about 3 mm. In Reference Embodiment 2, the sensor inclination angle χ = 55 deg. It was. Since the magnet rotor 21 is 12-pole magnetized, the mechanical angle is 360 deg. When rotated, an output of 6 cycles was obtained. In this case, the mechanical angle is 60 deg. Thus, one cycle of the electrical angle is obtained. The obtained data are shown in FIG. 17 as (a) a graph of mechanical angle and sensor output, (b) a graph of detected angle and electrical angle error with respect to the mechanical angle, and (c) a graph in which (b) is partially enlarged. Show. Although there is a difference in the degree of distortion, the sensor bridge X01 is a trapezoidal wave and the sensor bridge Y01 is a triangular wave, and the angle error per electrical angle cycle is ± 10 deg. That was a very big value. On the other hand, the data obtained by implementing Reference Form 2 are shown in graphs (a) to (c) of FIG. The output from each sensor bridge is a sine wave and a cosine wave, and the angle error of the electrical angle is ± 3 deg. As a result, a large improvement in angular error was observed. This rotation angle detection device can be applied to a motor to detect the rotation angle with high accuracy.

The schematic of the position detection apparatus of this invention is shown. The schematic of the position detection apparatus of a comparison form is shown. The schematic of the other position detection apparatus of this invention is shown. The schematic of the other position detection apparatus of this invention is shown. The schematic of the other position detection apparatus of this invention is shown. It is the schematic explaining the coordinate etc. of a position detection apparatus. The schematic of the linear drive device of this invention is shown. The schematic of the other linear drive device of this invention is shown. The schematic of the rotation angle detection apparatus of a reference form is shown. The schematic of the rotation angle detection apparatus of another reference form is shown. It is the schematic explaining the coordinate etc. of the rotation angle detection apparatus of a reference form. It is a schematic diagram which shows arrangement | positioning and the bridge circuit of the element (element) in a sensor device. It is a figure which shows an example of the circuit used for this invention. It is a graph which shows the displacement amount and displacement amount error of an Example. It is a graph which shows the displacement amount and displacement amount error of a comparative example. It is a graph which shows the displacement amount and displacement amount error of another Example. It is a graph which shows the relationship between the mechanical angle and sensor output of a reference example, and the relationship between the detection angle with respect to a mechanical angle, and an electrical angle error. It is a graph which shows the relationship between the mechanical angle of another reference example, and a sensor output, and the relationship between the detection angle with respect to a mechanical angle, and an electrical angle error.

Explanation of symbols

11: Stator, 12a, 12b, 12c, 12d, 12e: Sensor device,
12a ′: sensor device, 12a ″: sensor device,
22a, 22b, 22c, 22d: spin valve type giant magnetoresistive effect element,
23: terminal, 26a, 26b, 26c, 26d, 26e, 26f: operational amplifier,
27: AD conversion unit, 28: position calculation unit,
40: Stator, 41: Ring magnet, 41b: Cylindrical magnet, 42: Shaft,
43: York, 44: Coil, 45a, 45b: Non-magnetic part,
46: nonmagnetic part, 47: reference magnetic pole, 48: reference rail 49: mover,
50: Stator, 51: Magnet array,
52a, 52b: side plate yoke, 52c: substrate yoke, 53: frame, 54: coil,
55: Support substrate, 56: Table, 57a, 57b: Guide part,
58a, 58b: reinforcement member, 59: mover

Claims (8)

A stator having a multi-pole array on the surface, and a first sensor device and a second sensor device that detect a direction of a magnetic flux from the stator while moving in parallel with the magnetic pole array surface of the stator. A position detecting device,
The first sensor device includes a sensor bridge X01 and a sensor bridge Y01 whose fixed layer magnetization directions are orthogonal to each other,
The second sensor device includes a sensor bridge X02 and a sensor bridge Y02 in which the fixed layer magnetization directions are orthogonal to each other,
Each of the sensor bridges X01, Y01, X02 and Y02 is a spin valve type giant magnetoresistive element (having a fixed layer and a free layer, the fixed layer magnetization direction is fixed, and the free layer magnetization direction is the direction of the magnetic field. A magnetoresistive element that rotates according to the
The magnetization direction of the fixed layer of the spin valve type giant magnetoresistive effect element on the adjacent side in the full bridge is antiparallel,
The sensor bridge Y01 and the sensor bridge Y02 are arranged such that the fixed layer magnetization direction is along the direction of the multi-pole array of the stator, and the fixed layer magnetization direction of the sensor bridge X01 and the fixed layer magnetization direction of the sensor bridge X02. And λ / 4 or λ / 4 ± nλ / 2 (where λ is the pitch of magnetic poles of the same polarity in a multi-pole array, and n is an integer),
By applying a voltage to each of the full bridges, a differential output corresponding to an angle formed by the fixed layer magnetization direction and the free layer magnetization direction is obtained, and a position signal is obtained based on the differential output. A position detecting device characterized by that. A position detection device comprising a stator having a multi-pole array on the surface, and a sensor device that detects the direction of magnetic flux from the stator while moving parallel to the multi-pole array surface of the stator,
The sensor device includes a sensor bridge X01 and a sensor bridge Y01 whose fixed layer magnetization directions are orthogonal to each other,
Each of the sensor bridges X01 and Y01 is a spin-valve giant magnetoresistive element (having a fixed layer and a free layer, the fixed layer magnetization direction is fixed, and the free layer magnetization direction rotates according to the direction of the magnetic field. A magnetoresistive element) bridge circuit,
In the sensor bridges X01 and Y01, the pinned layer magnetization directions of the spin valve type giant magnetoresistive effect elements on the electrically adjacent sides are antiparallel,
A plane including the pinned layer magnetization direction of the sensor bridges X01 and Y01 is inclined with respect to a plane passing through the thickness center point of the multi-pole array surface of the stator and perpendicular to the multi-pole array surface,
By applying a voltage to each of the sensor bridges X01 and Y01, an output corresponding to an angle between the fixed layer magnetization direction and the free layer magnetization direction is obtained, and a position signal is obtained based on the output. A position detection device characterized by the above. A position detection device comprising a stator having a multi-pole array on the surface, and a sensor device that detects the direction of magnetic flux from the stator while moving parallel to the multi-pole array surface of the stator,
The sensor device includes a sensor bridge X01 and a sensor bridge Y01 whose fixed layer magnetization directions are orthogonal to each other,
Each of the sensor bridges X01 and Y01 is a spin-valve giant magnetoresistive element (having a fixed layer and a free layer, the fixed layer magnetization direction is fixed, and the free layer magnetization direction rotates according to the direction of the magnetic field. A magnetoresistive element) bridge circuit,
In the sensor bridges X01 and Y01, the pinned layer magnetization directions of the spin valve type giant magnetoresistive effect elements on the electrically adjacent sides are antiparallel,
The center of the sensor device is away from the plane that passes through the thickness center point of the multi-pole array surface of the stator and is perpendicular to the multi-pole array face, in the thickness direction of the multi-pole array face of the stator,
By applying a voltage to each of the sensor bridges X01 and Y01, an output corresponding to an angle between the fixed layer magnetization direction and the free layer magnetization direction is obtained, and a position signal is obtained based on the output. A position detection device characterized by the above. A stator having a multi-pole array on the surface, and a first sensor device and a second sensor device that detect a direction of magnetic flux from the stator while moving parallel to the multi-pole array surface of the stator. A position detecting device comprising:
The first sensor device includes a sensor bridge X01 and a sensor bridge Y01 whose fixed layer magnetization directions are orthogonal to each other,
The second sensor device includes a sensor bridge X02 and a sensor bridge Y02 in which the fixed layer magnetization directions are orthogonal to each other,
Each of the sensor bridges X01, Y01, X02 and Y02 is a spin valve type giant magnetoresistive element (having a fixed layer and a free layer, the fixed layer magnetization direction is fixed, and the free layer magnetization direction is the direction of the magnetic field. A magnetoresistive element that rotates in response to
In the sensor bridges X01, Y01, X02 and Y02, the pinned layer magnetization direction of the spin valve type giant magnetoresistive effect element on the electrically adjacent sides is antiparallel,
The plane including the pinned layer magnetization direction of the sensor bridges X01, Y01, X02 and Y02 is inclined with respect to a plane passing through the center of thickness of the multi-pole array surface of the stator and perpendicular to the multi-pole array surface,
By applying a voltage to each of the sensor bridges X01, Y01, X02, and Y02, an output corresponding to an angle formed by the fixed layer magnetization direction and the free layer magnetization direction is obtained, and the position is determined based on the output. A rotation angle detection device characterized by obtaining a signal. A stator having a multi-pole array on the surface, and a first sensor device and a second sensor device that detect a direction of magnetic flux from the stator while moving parallel to the multi-pole array surface of the stator. A position detecting device comprising:
The first sensor device includes a sensor bridge X01 and a sensor bridge Y01 whose fixed layer magnetization directions are orthogonal to each other,
The second sensor device includes a sensor bridge X02 and a sensor bridge Y02 in which the fixed layer magnetization directions are orthogonal to each other,
Each of the sensor bridges X01, Y01, X02 and Y02 is a spin valve type giant magnetoresistive element (having a fixed layer and a free layer, the fixed layer magnetization direction is fixed, and the free layer magnetization direction is the direction of the magnetic field. A magnetoresistive element that rotates in response to
In the sensor bridges X01, Y01, X02 and Y02, the pinned layer magnetization direction of the spin valve type giant magnetoresistive effect element on the electrically adjacent sides is antiparallel,
The center of the first sensor device and the second sensor device is from a plane that passes through the thickness center point of the multi-pole array surface of the stator and is perpendicular to the multi-pole array surface, and from the plane of the multi-pole array surface of the stator. Apart in the thickness direction,
By applying a voltage to each of the sensor bridges X01, Y01, X02, and Y02, an output corresponding to an angle formed by the fixed layer magnetization direction and the free layer magnetization direction is obtained, and the position is determined based on the output. A position detection device characterized by obtaining a signal. A position detection apparatus comprising: a stator having a multi-pole array; and a sensor device that translates with respect to the multi-pole array surface of the stator and detects the direction of magnetic flux from the stator,
The sensor device includes a plurality of spin-valve giant magnetoresistive elements (a magnetoresistive element having a fixed layer and a free layer, the fixed layer magnetization direction being fixed, and the free layer magnetization direction rotating according to the direction of the magnetic field. Element) having a magnetosensitive surface,
The sensor device is provided with respect to the stator so that the amplitude of magnetic flux density components orthogonal to each other in the magnetosensitive surface is equal by crossing the magnetic flux with the magnetosensitive surface. A position detection device. A position detection apparatus comprising: a stator having a multi-pole array; and a sensor device that translates with respect to the multi-pole array surface of the stator and detects the direction of magnetic flux from the stator,
The sensor device includes a plurality of spin-valve giant magnetoresistive elements (a magnetoresistive element having a fixed layer and a free layer, the fixed layer magnetization direction being fixed, and the free layer magnetization direction rotating according to the direction of the magnetic field. Element) having a magnetosensitive surface,
The amplitude ratio K _eff = B _⊥eff0 / B _{// eff0 of} the effective magnetic flux density orthogonal in the _{magnetosensitive surface} at the position where the amplitude ratio K ₀ = B _⊥0 / B _{// 0} ≠ 1 1. The position detection apparatus according to claim 1, wherein the sensor device is provided for the stator. A linear drive device comprising: the position detection device according to any one of claims 1 to 8; and a coil provided on the mover and facing the multi-pole array surface of the stator.

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