Multi-axis actuator

Abstract

A multi-axis actuator (100) is provided with: a multi-axis actuator coil (1); and a shaft (10) that is disposed on the inner periphery of the multi-axis actuator coil (1). The multi-axis actuator coil (1) is provided with: a linear coil group (2) that generates a magnetic field that causes the shaft (10) to move in an axial direction; and a rotary coil group (3) that is disposed on the inner periphery or the outer periphery of the linear coil group (2) and generates a magnetic field that causes the shaft (10) to move in a circumferential direction. The linear coil group (2) comprises a plurality of linear coils (2a) arranged side-by-side in the axial direction. Each of the linear coils (2a) extends in the circumferential direction. Each of the linear coils (2a) comprises two coil ends (2b, 2c) that are positioned at one end and the other end in the circumferential direction. A first angle in the circumferential direction formed by the two coil ends (2b, 2c) of each linear coil (2a) either is equal to the electrical angle period of the rotary coil group (3) or is an integral multiple of the electrical angle period of the rotary coil group (3).

Description

Multi-axis Actuator

[0001] The present disclosure relates to a multi-axis actuator including a multi-axis actuator coil.

[0002] Conventionally, multi-axis actuators that move a mover in multiple directions have been used in semiconductor manufacturing equipment, small robots, etc. The multi-axis actuators are equipped with multi-axis actuator coils that generate magnetic fields for moving the mover in multiple directions. For example, Patent Document 1 discloses a multi-axis actuator coil that includes a linear coil group having Z-axis coils arranged in the axial direction and a rotary coil group having θ-axis coils arranged in a row on the outer periphery of the linear coil group.

[0003] JP 2011-142725 A

[0004] However, as disclosed in Patent Document 1, when two different coil groups are arranged side by side in the radial direction, mutual interference occurs, in which magnetic flux generated when one of the two coil groups is energized interferes with the other coil group. This causes the problem of unintended induced currents and malfunction of the multi-axis actuator. This problem becomes particularly pronounced when magnetic flux generated from the rotary coil group interferes with the linear coil group.

[0005] The present disclosure has been made in view of the above, and has an object to provide a multi-axis actuator that can suppress interference of magnetic flux generated from a rotary coil group with a linear motion coil group.

[0006] In order to solve the above-mentioned problems and achieve the object, the multi-axis actuator according to the present disclosure includes a cylindrical multi-axis actuator coil and a shaft arranged on the inner periphery of the multi-axis actuator coil. The multi-axis actuator coil includes a group of direct-acting coils that generate a magnetic field that moves the shaft in the axial direction, and a group of rotating coils that are arranged on the inner or outer periphery of the group of direct-acting coils and generate a magnetic field that moves the shaft in the circumferential direction. The group of direct-acting coils includes a plurality of direct-acting coils arranged side by side in the axial direction. Each direct-acting coil extends in the circumferential direction. Each direct-acting coil has two coil ends located at one end and the other end in the circumferential direction. A first angle in the circumferential direction formed by the two coil ends of each direct-acting coil is equal to the electrical angle period of the group of rotating coils or is an integer multiple of the electrical angle period of the group of rotating coils.

[0007] The multi-axis actuator according to the present disclosure has the advantage of being able to suppress the magnetic flux generated from the rotary coil group from interfering with the linear motion coil group.

[0008] 1A perspective view of the multi-axis actuator according to the first embodiment; A cross-sectional view taken along line II-II of FIG. 1; A cross-sectional view taken along line III-III of FIG. 1; A perspective view of the multi-axis actuator according to the first embodiment, with a part broken away; A perspective view of the direct-acting coil according to the first embodiment; A view of the direct-acting coil according to the first embodiment, as viewed in the axial direction; A front view of the rotary coil according to the first embodiment; A perspective view of the magnet according to the first embodiment, with a part broken away; A view of the magnet according to the first embodiment, as viewed in the axial direction; A side view schematically showing the multi-axis actuator according to the second embodiment; A side view schematically showing the multi-axis actuator according to the third embodiment; A perspective view of a coil for the multi-axis actuator according to the fourth embodiment; A view of the coil for the multi-axis actuator according to the fourth embodiment, as viewed in the axial direction; A side view showing the first printed circuit board before winding the first printed circuit board; A view showing the surface of the first printed circuit board; A side view showing the first printed circuit board before winding the first printed circuit board; A view showing the back surface of the first printed circuit board seen through from the surface; 1 is a side view showing a state of a multi-axis actuator coil according to a fourth embodiment before being wound around a second printed circuit board, showing the surface of the second printed circuit board; 2 is a side view showing a state of a multi-axis actuator coil according to a fourth embodiment before being wound around a second printed circuit board, showing the back surface of the second printed circuit board seen through from the front surface; 3 is a perspective view showing a multi-axis actuator coil according to a modified example of the fourth embodiment; 4 is a view showing a multi-axis actuator coil according to a modified example of the fourth embodiment as seen along the axial direction; 5 is a side view showing a multi-axis actuator coil according to a fifth embodiment before being wound around a first printed circuit board, showing the surface of the first printed circuit board;FIG. 1 is a perspective view showing the back surface of the second printed circuit board as seen through from the front surface; FIG. 2 is a perspective view showing the coil for a multi-axis actuator according to a fifth embodiment; FIG. 3 is a side view showing the state before winding the first printed circuit board of the coil for a multi-axis actuator according to a sixth embodiment, showing the front surface of the first printed circuit board; FIG. 4 is a side view showing the state before winding the first printed circuit board of the coil for a multi-axis actuator according to a sixth embodiment, showing the back surface of the first printed circuit board as seen through from the front surface; a side view showing the state before the substrate is wound, the view showing the rear surface of the second printed circuit board seen through from the front surface; a side view showing the state before the second printed circuit board of the coil for the multi-axis actuator according to the seventh embodiment is wound around the second printed circuit board, the view showing the front surface of the second printed circuit board; a side view showing the state before the first printed circuit board of the coil for the multi-axis actuator according to the seventh embodiment is wound around the first printed circuit board, the view showing the front surface of the first printed circuit board; a perspective view showing the coil for the multi-axis actuator according to the seventh embodiment as seen along the axial direction; a cross-sectional view taken along the line XXXIII-XXXIII shown in FIG. 32; a cross-sectional view taken along the line XXXIV-XXXIV shown in FIG.

[0009] A multi-axis actuator according to an embodiment will be described in detail below with reference to the drawings.

[0010] First Embodiment First, a multi-axis actuator 100 will be described with reference to Figures 1 to 3. Figure 1 is a perspective view showing the multi-axis actuator 100 according to the first embodiment. Figure 2 is a cross-sectional view taken along line II-II in Figure 1. Figure 3 is a cross-sectional view taken along line III-III in Figure 1. As shown in Figures 1 and 2, the multi-axis actuator 100 includes a housing 6, a rotor core 7, a magnet 8, a multi-axis actuator coil 1, a stator core 9, and a shaft 10.

[0011] The rotor core 7 and the stator core 9 are both formed in a cylindrical shape having a central axis C. Hereinafter, when describing the directions of each component of the multi-axis actuator 100, the direction parallel to the central axis C will be referred to as the axial direction, the direction perpendicular to the central axis C as the radial direction, and the direction of rotation about the central axis C as the circumferential direction. The multi-axis actuator 100 is an inner rotor type multi-axis actuator in which the rotor core 7 is disposed on the inner circumferential side of the stator core 9.

[0012] The housing 6 accommodates the rotor core 7, magnets 8, multi-axis actuator coil 1, stator core 9, and shaft 10. The housing 6 is cylindrical with a rounded square outer surface and a circular inner surface. As shown in FIG. 3 , the housing 6 includes a cylindrical frame 6a with open axial ends and two brackets 6b disposed in the openings at both axial ends of the frame 6a. An insertion hole 6c is formed in each of the two brackets 6b, into which the shaft 10 is inserted. A bearing 11 is disposed on the inner circumferential surface of the insertion hole 6c in each bracket 6b. The bearings 11 are components that support the shaft 10 for rotation and linear motion. The shaft 10 is supported for rotation and linear motion by the two bearings 11. The bracket 6b on the right side of FIG. 3 has a through-hole 6d formed therein, allowing the shaft 10 to protrude outside the housing 6.

[0013] As shown in Fig. 2, the stator core 9 is disposed on the inner periphery of the frame 6a. The stator core 9 is fitted into the inner periphery of the frame 6a. Magnetic paths are formed in multiple directions in the stator core 9. For this reason, it is preferable to use, for example, a powder magnetic core or a bulk material as the material for the stator core 9.

[0014] The multi-axis actuator coil 1 is disposed on the inner periphery of the stator core 9. The multi-axis actuator coil 1 is formed in a cylindrical shape. The multi-axis actuator coil 1 is disposed coaxially with the central axis C of the rotor core 7 and the stator core 9. The multi-axis actuator coil 1 includes a direct-acting coil group 2 and a rotating coil group 3 disposed on the inner periphery of the direct-acting coil group 2. The direct-acting coil group 2 generates a magnetic field for moving the shaft 10 in the axial direction. A magnetic field is generated by passing a current through the direct-acting coil group 2, and this magnetic field generates a thrust that moves the shaft 10 axially, thereby moving the shaft 10 axially. The rotating coil group 3 generates a magnetic field for rotating the shaft 10 in the circumferential direction. A magnetic field is generated by passing a current through the rotating coil group 3, and this magnetic field generates a torque that rotates the shaft 10 in the circumferential direction, thereby rotating the shaft 10 in the circumferential direction. Details of the multi-axis actuator coil 1 will be described later.

[0015] The magnet 8 is provided on the inner periphery of the multi-axis actuator coil 1. The magnet 8 is arranged with a gap between it and the multi-axis actuator coil 1. The magnet 8 faces the multi-axis actuator coil 1 in the radial direction.

[0016] The rotor core 7 is disposed on the inner periphery of the magnets 8. In other words, the magnets 8 are attached to the outer periphery of the rotor core 7.

[0017] The shaft 10 is disposed on the inner periphery of the rotor core 7. As shown in FIG. 3 , the shaft 10 extends along the central axis C. The shaft 10 is disposed coaxially with the central axis C. One axial end of the shaft 10 protrudes outside the housing 6 through the insertion hole 6c and the through-hole 6d of one bracket 6b on the right side of FIG. 3 . The other axial end of the shaft 10 protrudes outside the housing 6 through the insertion hole 6c of the other bracket 6b on the left side of FIG. 3 . The shaft 10 is movable in multiple directions. In this embodiment, the shaft 10 can move in the circumferential direction and the axial direction. In this embodiment, the multi-axis actuator 100 is a moving magnet type multi-axis actuator. The rotor core 7, the magnets 8, and the shaft 10 form a mover, and the multi-axis actuator coil 1, the stator core 9, and the frame 6a form a stator. The rotor core 7 and the magnets 8 move in the circumferential direction and the axial direction together with the shaft 10.

[0018] A first position detector 12 and a second position detector 13 are disposed inside one of the brackets 6b on the right side of the page in FIG. 3 . The first position detector 12 is a device for detecting the circumferential angle of the shaft 10. The first position detector 12 has a first scale 12a having a plurality of magnetic poles or rulings and a first sensor 12b that detects the rotation angle of the shaft 10 from the first scale 12a. The first scale 12a is attached to the shaft 10. The first sensor 12b is attached to one of the brackets 6b. The second position detector 13 is a device for detecting the axial position of the shaft 10. The second position detector 13 has a second scale 13a having a plurality of magnetic poles or rulings and a second sensor 13b that detects the axial position of the shaft 10 from the second scale 13a. The second scale 13a is attached to the shaft 10. The second sensor 13b is attached to one of the brackets 6b.

[0019] Next, the magnet 8, the shaft 10, and the multi-axis actuator coil 1 will be described in detail with reference to FIGS. 4 to 9 . FIG. 4 is a partially cutaway perspective view of the multi-axis actuator 100 according to the first embodiment. FIG. 5 is a perspective view showing a direct-acting coil 2a according to the first embodiment. FIG. 6 is a view of the direct-acting coil 2a according to the first embodiment as viewed along the axial direction. FIG. 7 is a front view of the rotary coil 3a according to the first embodiment. FIG. 8 is a partially cutaway perspective view of the magnet 8 according to the first embodiment. FIG. 9 is a view of the magnet 8 according to the first embodiment as viewed along the axial direction. Note that FIG. 4 illustrates only the multi-axis actuator coil 1, the magnet 8, and the shaft 10 of the multi-axis actuator 100. FIG. 5 illustrates only one direct-acting coil 2a.

[0020] 4, the multi-axis actuator coil 1 includes a direct-acting coil group 2 that generates a magnetic field that moves a mover in the axial direction, and a rotary coil group 3 that is disposed inside the direct-acting coil group 2 and generates a magnetic field that moves the mover in the circumferential direction. In the following, an example will be described in which the direct-acting coil group 2 and the rotary coil group 3 are three-phase coils.

[0021] The direct-acting coil group 2 has a plurality of direct-acting coils 2a arranged side by side in the axial direction. While two direct-acting coils 2a are illustrated in FIG. 4 , three or more direct-acting coils 2a are actually arranged side by side in the axial direction. Each direct-acting coil 2a extends in the circumferential direction. Each direct-acting coil 2a is a single spirally wound magnet wire that extends in the circumferential direction while moving in the axial direction. In this embodiment, each direct-acting coil 2a has a single-layer cylindrical shape with no overlap in the radial direction, but may have a cylindrical shape with two or more layers overlapping in the radial direction.

[0022] Each direct-acting coil 2a has two coil ends 2b, 2c located at one end and the other end in the circumferential direction. As shown in FIG. 5 , the coil ends 2b, 2c of the direct-acting coil 2a are located at one end and the other end in the longitudinal direction of the magnet wire. The two coil ends 2b, 2c protrude radially outward. One of the two coil ends 2b, 2c is the winding start end. The other of the two coil ends 2b, 2c is the winding end end. One of the two coil ends 2b, 2c serves as a terminal to which a power supply line of a power supply unit (not shown) is connected. The other of the two coil ends 2b, 2c serves as a connection part electrically connected to the direct-acting coil 2a of each phase. The connection part may be, for example, a neutral point or a delta connection.

[0023] As shown in FIG. 6 , the first circumferential angle θ1 formed by the two coil ends 2b, 2c of each direct-acting coil 2a is equal to the electrical angle period of the rotating coil group 3 shown in FIG. 4 or an integer multiple of the electrical angle period of the rotating coil group 3. The first angle θ1 is the circumferential angle formed by the two coil ends 2b, 2c with the axial center 2d of the direct-acting coil 2a as the base point. The first angle θ1 may be 0 degrees, but preferably exceeds 0 degrees. This embodiment illustrates a case where the first angle θ1 exceeds 0 degrees. When the first angle θ1 exceeds 0 degrees, the circumferential positions of the two coil ends 2b, 2c of the same direct-acting coil 2a are misaligned. On the other hand, when the first angle θ1 is 0 degrees, the circumferential positions of the two coil ends 2b, 2c of the same direct-acting coil 2a are the same.

[0024] As shown in Figure 4, the circumferential positions of the coil ends 2b of different direct-acting coils 2a may be the same or may be shifted. The circumferential positions of the coil ends 2c of different direct-acting coils 2a may be the same or may be shifted. The circumferential positions of the coil end 2b of one axially adjacent direct-acting coil 2a and the coil end 2c of the other adjacent direct-acting coil 2a may be shifted or may be the same. When the winding angle A of the direct-acting coil 2a is A, the number of turns of the direct-acting coil 2a is T, and the first angle is θ1, and the winding angle A is expressed by the following equation (1), it is preferable that the winding angle A of each direct-acting coil 2a is the same angle. A = 360 degrees × T + θ1 (1)

[0025] The rotating coil group 3 is a single magnet wire wound in a spiral shape that moves circumferentially while extending alternately in the axial and radial directions. The rotating coil group 3 includes a plurality of rotating coils 3a, which are hexagonal loops as shown in FIG. 7. The plurality of rotating coils 3a are formed continuously in the circumferential direction. Each rotating coil 3a includes a long side portion 3b that extends linearly in the axial direction and a short side portion 3c that extends radially. The long side portions 3b and the short side portions 3c are arranged alternately. The long side portion 3b is a portion that contributes to generating torque that rotates the mover. The short side portion 3c is a portion that does not contribute much to generating torque that rotates the mover. The short side portion 3c serves to connect two adjacent long side portions 3b. The shape of the short side portion 3c is pointed and convex toward the outer periphery of the loop.

[0026] As shown in FIG. 4 , the magnets 8 and the shaft 10 are disposed on the inner periphery of the rotating coil 3 a. The magnets 8 are disposed along the outer periphery of the shaft 10. As shown in FIG. 8 , the shape of the magnets 8 when viewed radially is a rhombus in this embodiment, but may be a square or other shape. The magnets 8 are tightly arranged with one diagonal of the rhombus aligned with the axial direction and the other diagonal of the rhombus aligned with the circumferential direction. The magnets 8 include a first magnet 8 a with a north pole and a second magnet 8 b with a south pole. In FIG. 8 , only the first magnet 8 a is hatched to distinguish the first magnet 8 a from the second magnet 8 b. The first magnet 8 a and the second magnet 8 b are disposed with their edges in contact with each other. Axial rows of the first magnets 8 a and axial rows of the second magnets 8 b are alternately arranged in the circumferential direction. The first magnets 8a are arranged in rows circumferentially, and the second magnets 8b are arranged in rows circumferentially, alternating in the axial direction. The first magnets 8a are oriented from the inside to the outside in the radial direction. The second magnets 8b are oriented from the outside to the inside in the radial direction.

[0027] The first magnet 8a has a first center 8c. The first center 8c is the center of the first magnet 8a when viewed radially. If the shape of the first magnet 8a is rhombic, the first center 8c is the point where two diagonal lines intersect. The second magnet 8b has a second center 8d. The second center 8d is the center of the second magnet 8b when viewed radially. If the shape of the second magnet 8b is rhombic, the second center 8d is the point where two diagonal lines intersect. The first center 8c and the second center 8d are offset in the axial and circumferential directions.

[0028] Here, the distance along the axial direction between the first center 8c of the first magnet 8a and the second center 8d of the second magnet 8b is defined as the inter-pole distance P5. Also, as shown in FIG. 9 , the circumferential angle formed by the first center 8c and the second center 8d of the adjacent first magnet 8a and second magnet 8b is defined as the second angle θ2. The second angle θ2 is the circumferential angle formed by the first center 8c of the first magnet 8a and the second center 8d of the adjacent second magnet 8b, with the axial center 8e of the magnets 8 arranged in a cylindrical shape as the base point. The first angle θ1 shown in FIG. 6 is the same as 2n times the second angle θ2 shown in FIG. 9 , where n is 0 or a natural number. In this specification, the term "same angle" refers not only to completely identical angles, but also to angles that are not strictly identical but are offset by two to three times the wire diameter of the magnet wire, taking into account the bending performance of the magnet wire. The illustrated arrangement of the magnets 8 is an example, and may be changed as appropriate as long as the arrangement of the magnets 8 has the inter-pole distance P5 and the second angle θ2.

[0029] Next, the effects of the multi-axis actuator 100 according to this embodiment will be described.

[0030] In this embodiment, as shown in FIG. 4 , the multi-axis actuator coil 1 includes a linear motion coil group 2 that generates a magnetic field that moves the mover in the axial direction, and a rotary coil group 3 that is disposed inside the linear motion coil group 2 and generates a magnetic field that moves the mover in the circumferential direction. Also, in this embodiment, as shown in FIG. 6 , the first circumferential angle θ1 formed by the two coil ends 2 b, 2 c of each linear motion coil 2 a is equal to the electrical angle period of the rotary coil group 3 or an integer multiple of the electrical angle period of the rotary coil group 3. With this configuration, when the rotary coil group 3 shown in FIG. 4 is energized, the magnetic flux that links with the linear motion coil group 2, i.e., the linear motion interference magnetic flux, is balanced in each phase of the rotary coil group 3. Therefore, the sum of the linear motion interference magnetic flux generated from each phase of the rotary coil group 3 is theoretically zero, and the linear motion interference magnetic flux generated from the rotary coil group 3 can be prevented from interfering with the linear motion coil group 2. This suppresses the generation of unintended induced current and prevents malfunction of the multi-axis actuator 100.

[0031] In this embodiment, as shown in Fig. 6, the first angle θ1 exceeds 0 degrees. With this configuration, the two coil ends 2b, 2c of the same direct-acting coil 2a are circumferentially offset from each other. This facilitates the connection of a power supply line to one of the two coil ends 2b, 2c and the connection of the other of the two coil ends 2b, 2c to form a neutral or delta connection.

[0032] 4 and 6, the winding angle of the direct-acting coil 2a is A, the number of turns of the direct-acting coil 2a is T, and the first angle is θ1. When the winding angle A is expressed by the above-mentioned formula (1), it is preferable that the winding angle A of each direct-acting coil 2a is the same. In this way, the number of turns T of each direct-acting coil 2a closely matches, and the length of the direct-acting coil 2a of each phase becomes the same. As a result, the magnetomotive forces of the windings of each phase match, which can be expected to suppress pulsation, i.e., vibration, during operation of the multi-axis actuator 100. Also, since the resistance values ​​of the windings of each phase match, circulating currents can be suppressed when a delta connection is used.

[0033] In this embodiment, as shown in Fig. 4, the coil end 2b of one adjacent direct-acting coil 2a and the coil end 2c of the other adjacent direct-acting coil 2a are circumferentially offset from each other. This configuration prevents the coil end 2b of one adjacent direct-acting coil 2a and the coil end 2c of the other adjacent direct-acting coil 2a from interfering with each other. This allows the direct-acting coils 2a to be stacked in the axial direction while minimizing gaps between the adjacent direct-acting coils 2a, and also facilitates the work of connecting the coil ends 2b and 2c.

[0034] Next, a modification of the first embodiment will be described.

[0035] In the present embodiment, the direct-acting coil group 2 and the rotating coil group 3 are illustrated as three-phase coils, but are not limited thereto. The direct-acting coil group 2 and the rotating coil group 3 may be multi-phase coils having four or more phases.

[0036] 4, the multi-axis actuator 100 includes the magnet 8, but it may not include the magnet 8. For example, the multi-axis actuator 100 may have a configuration equivalent to a Synchronous Reluctance Motor (SynRM) that rotates only by the reluctance torque of an iron core.

[0037] 2 and 3, the multi-axis actuator 100 includes the stator core 9, but it may not include the stator core 9. For example, the multi-axis actuator 100 may have a configuration equivalent to a coreless structure that does not have an iron core near the coils.

[0038] 2 and 3, the multi-axis actuator 100 includes the frame 6a, but the frame 6a may not be included. For example, the multi-axis actuator 100 may have a frameless structure in which the stator core 9 also serves as the frame.

[0039] In this embodiment, the first magnet 8a shown in Figure 8 is the north pole and the second magnet 8b is the south pole, but the first magnet 8a may be the south pole and the second magnet 8b may be the north pole.

[0040] Second Embodiment Next, a multi-axis actuator 100A according to the second embodiment will be described with reference to FIG. 10 . FIG. 10 is a side view schematically illustrating the multi-axis actuator 100A according to the second embodiment. This embodiment differs from the first embodiment in that the number of direct-acting coils 2 a radially facing the rotary coil group 3 is the same for each phase, the number of direct-acting coils 2 a for each phase is an even number, and the axial length P1 of the direct-acting coil group 2 in the multi-axis actuator coil 1A is shorter than the axial length P2 of the long side portion 3 b of the rotary coil group 3. Note that in the second embodiment, parts that overlap with those in the first embodiment are designated by the same reference numerals and will not be described again.

[0041] The axial length P1 of the direct-acting coil group 2 is shorter than the axial length P2 of the long side portion 3b of the rotating coil group 3. The axial length P1 of the direct-acting coil group 2 is the length along the axial direction from one axial end to the other of the direct-acting coil group 2. The axial length P2 of the long side portion 3b of the rotating coil group 3 is the length along the axial direction from one axial end to the other of the long side portion 3b of the rotating coil group 3. The number of direct-acting coils 2a facing the rotating coil group 3 in the radial direction is the same for each phase, and the number of direct-acting coils 2a for each phase is an even number. Figure 12 shows, as an example, a case where the direct-acting coil group 2 is a three-phase coil and the number of direct-acting coils 2a for each phase is two.

[0042] Next, the effects of the multi-axis actuator 100A according to this embodiment will be described.

[0043] This embodiment can achieve the same effects as the first embodiment. In this embodiment, the number of direct-acting coils 2 a radially facing the rotating coil group 3 is the same for each phase, and the number of direct-acting coils 2 a for each phase is even. Furthermore, in this embodiment, the axial length P1 of the direct-acting coil group 2 is shorter than the axial length P2 of the long side portion 3 b of the rotating coil group 3. These configurations allow the magnetic flux interlinking with the rotating coil group 3 when current is applied to the direct-acting coil group 2, i.e., the rotation-side interference magnetic flux, to be balanced for each phase of the direct-acting coil group 2. Therefore, the sum of the rotation-side interference magnetic flux generated from each phase of the direct-acting coil group 2 is theoretically zero, thereby preventing the rotation-side interference magnetic flux generated from the direct-acting coil group 2 from interfering with the rotating coil group 3. In other words, this embodiment can prevent both the magnetic flux generated from the rotating coil group 3 from interfering with the direct-acting coil group 2 and the magnetic flux generated from the direct-acting coil group 2 from interfering with the rotating coil group 3. This makes it possible to further suppress the occurrence of unintended induced currents and to further suppress malfunction of the multi-axis actuator 100A.

[0044] Third Embodiment Next, a multi-axis actuator 100B according to the third embodiment will be described with reference to FIG. 11 . FIG. 11 is a side view schematically illustrating the multi-axis actuator 100B according to the third embodiment. This embodiment differs from the first embodiment in that the axial length P2 of the long side portion 3 b of the rotating coil group 3 is the same as 2 m times the inter-pole distance P5, and that the axial length P1 of the linear motion coil group 2 in the multi-axis actuator coil 1B is longer than the axial length P2 of the long side portion 3 b of the rotating coil group 3. Note that in the third embodiment, parts that overlap with the first and second embodiments are designated by the same reference numerals and will not be described again.

[0045] The axial length P1 of the direct-acting coil group 2 is longer than the axial length P2 of the long side portion 3b of the rotating coil group 3. The axial length P2 of the long side portion 3b is the same as 2m times the inter-pole distance P5 shown in FIG. 8, where m is a natural number. In this specification, the term "same length" refers not only to completely identical lengths, but also to lengths that are not strictly identical but are between two and three times the wire diameter of the magnet wire, taking into account the bending performance of the magnet wire.

[0046] Next, the effects of the multi-axis actuator 100B according to this embodiment will be described.

[0047] This embodiment can achieve the same effects as the first embodiment. In this embodiment, the axial length P2 of the long side portion 3b is equal to 2m times the inter-pole distance P5. Furthermore, in this embodiment, the axial length P1 of the direct-acting coil group 2 is longer than the axial length P2 of the long side portion 3b. These configurations allow the magnetic flux that interlinks with the rotating coil group 3 when current is applied to the direct-acting coil group 2, i.e., the rotation-side interference magnetic flux, to be balanced in each phase of the direct-acting coil group 2. Therefore, the sum of the rotation-side interference magnetic flux generated from each phase of the direct-acting coil group 2 is theoretically zero, thereby preventing the rotation-side interference magnetic flux generated from the direct-acting coil group 2 from interfering with the rotating coil group 3. In other words, this embodiment can prevent both the magnetic flux generated from the rotating coil group 3 from interfering with the direct-acting coil group 2 and the magnetic flux generated from the direct-acting coil group 2 from interfering with the rotating coil group 3. This further reduces the occurrence of unintended induced currents and further prevents malfunction of the multi-axis actuator 100B.

[0048] Fourth Embodiment Next, a multi-axis actuator 100C according to a fourth embodiment will be described with reference to FIGS. 12 to 17. FIG. 12 is a perspective view showing a multi-axis actuator coil 1C according to the fourth embodiment. FIG. 13 is a view of the multi-axis actuator coil 1C according to the fourth embodiment as viewed along the axial direction. FIG. 14 is a side view showing the multi-axis actuator coil 1C according to the fourth embodiment before winding the first printed circuit board 4A, illustrating the surface 41 of the first printed circuit board 4A. FIG. 15 is a side view showing the multi-axis actuator coil 1C according to the fourth embodiment before winding the first printed circuit board 4A, illustrating the rear surface 42 of the first printed circuit board 4A seen through the surface 41. FIG. 16 is a side view showing the multi-axis actuator coil 1C according to the fourth embodiment before winding the second printed circuit board 4B, illustrating the surface 41 of the second printed circuit board 4B. 17 is a side view showing the state of the multi-axis actuator coil 1C according to the fourth embodiment before it is wound around the second printed circuit board 4B, and is a view of the back surface 42 of the second printed circuit board 4B seen through from the front surface 41. This embodiment differs from the first embodiment in that the multi-axis actuator coil 1C is a coil board. In the fourth embodiment, parts that overlap with those in the first embodiment are given the same reference numerals and descriptions thereof will be omitted.

[0049] As shown in FIG. 12 , the multi-axis actuator coil 1C includes a flexible printed circuit board 4 wound in the circumferential direction, and a linear coil group 5A and a rotary coil group 5B printed on the printed circuit board 4. While the rotary coil group 5B is not clearly shown in FIG. 12 , it is disposed on the inner periphery of the linear coil group 5A. Also, FIG. 12 does not show the magnet 8 and shaft 10 disposed on the inner periphery of the multi-axis actuator coil 1C. The printed circuit board 4 is wound around a single axis 57 shown in FIG. 13 . The axis 57 is a virtual axis extending parallel to the central axis C shown in FIG. 2 . The winding direction of the printed circuit board 4 coincides with the circumferential direction, which is the direction of rotation about the central axis C.

[0050] As shown in FIG. 12 , the printed circuit board 4 is a flexible board that can be freely deformed. In this embodiment, the printed circuit board 4 is divided in the circumferential direction. As shown in FIGS. 14 to 17 , the printed circuit board 4 is divided into two pieces. In the following description, when distinguishing between the two printed circuit boards 4, one printed circuit board 4 shown in FIGS. 14 and 15 will be referred to as the first printed circuit board 4A, and the other printed circuit board 4 shown in FIGS. 16 and 17 will be referred to as the second printed circuit board 4B. In FIGS. 14 and 15 , the first printed circuit board 4A is illustrated as a gray area. In FIGS. 16 and 17 , the second printed circuit board 4B is illustrated with diagonal hatching. When the first printed circuit board 4A and the second printed circuit board 4B are illustrated in FIG. 18 and subsequent figures, they will be distinguished from each other in the same manner as in FIGS. 14 to 17 . As shown in FIG. 12 , the printed circuit board 4 has a front surface 41 and a back surface 42 facing opposite to the front surface 41. It is preferable that the printed circuit board 4 is formed in two or more layers in the radial direction. As shown in Figures 14 to 17, the printed circuit board 4 has one end 43 and the other end 44 in the circumferential direction. Although the back surface 42 is not visible in Figures 15 and 17, the reference numerals for the front surface 41 and the back surface 42 are both shown for the sake of convenience.

[0051] The dot-hatched areas in Figures 14 and 15 are the direct-acting coil group 5A. The grid-hatched areas in Figures 16 and 17 are the rotating coil group 5B. In the following description, the direct-acting coil group 5A and the rotating coil group 5B may be referred to as the coil group 5 without distinction. When the direct-acting coil group 5A and the rotating coil group 5B are shown in Figures 18 and onwards, they are also distinguished from each other in the same way as in Figures 14 to 17.

[0052] As shown in FIGS. 14 to 17 , each coil group 5 has multiple coil patterns 51. Each coil pattern 51 includes multiple linearly extending long sides 51 a and multiple short sides 51 b connecting two adjacent long sides 51 a. The coil patterns 51 are conductors formed by etching the copper foil layer of the printed circuit board 4. In the following description, when distinguishing between the coil patterns 51 of the direct-acting coil group 5A and the rotating coil group 5B, the coil pattern 51 of the direct-acting coil group 5A will be referred to as a first coil pattern 52, and the coil pattern 51 of the rotating coil group 5B will be referred to as a second coil pattern 53. FIGS. 14 to 17 illustrate a case where each coil group 5 is a three-phase coil. In FIGS. 14 to 17 , the coil patterns 51 of each phase are distinguished by changing the hatching density.

[0053] As shown in FIGS. 14 and 15 , the number of first coil patterns 52 is six in this embodiment. In this embodiment, there are three first coil patterns 52 on each of the front surface 41 and the back surface 42 of the first printed circuit board 4A. The three first coil patterns 52 on the front surface 41 are arranged in the axial direction. The three first coil patterns 52 on the back surface 42 are arranged in the axial direction. The multiple first coil patterns 52 are multiple direct-acting coils arranged in the axial direction. Here, the number of coils in the direct-acting coil is defined as the number of axial areas in which the first coil patterns 52 of the same phase exist, counted without distinction between the front surface 41 and the back surface 42 of the first printed circuit board 4A. Furthermore, the axial areas in which the first coil patterns 52 of the same phase exist are divided based on a first long side 52 a (described later), and areas other than the first long side 52 a are not taken into consideration. Therefore, when viewed in a direction from the front surface 41 to the back surface 42 of the first printed circuit board 4A, if the axial position of the axial area where the first long side 52 a of the first coil pattern 52 of the same phase on the front surface 41 exists is the same as the axial position of the axial area where the first long side 52 a of the first coil pattern 52 of the same phase on the back surface 42 exists, they are counted as one direct-acting coil. On the other hand, when viewed in a direction from the front surface 41 to the back surface 42 of the first printed circuit board 4A, if the axial position of the axial area where the first long side 52 a of the first coil pattern 52 of the same phase on the front surface 41 exists is different from the axial position of the axial area where the first long side 52 a of the first coil pattern 52 of the same phase on the back surface 42 exists, they are counted as different direct-acting coils. 14 and 15 , for example, there are three axial areas on the front surface 41 where the first long side portions 52 a of the first coil patterns 52 of the same phase are present, and three axial areas on the back surface 42 where the first long side portions 52 a of the first coil patterns 52 of the same phase are present, and the axial positions of the six axial areas are different from each other. Therefore, the number of coils in the direct-acting coil is counted as six. Each of the first coil patterns 52 has roughly the same shape. Each of the first coil patterns 52 is printed on the first printed circuit board 4A in a distributed winding manner, in which loops of the same shape are wound with their centers shifted at regular intervals in the axial direction.Two ends A1 . . . A5, B1 . . . B5, C1 . . . C5 at the same positions on the front surface 41 and the back surface 42 of the first printed circuit board 4A are electrically connected via through holes 54.

[0054] The first coil patterns 52 are alternately arranged on the front surface 41 and the back surface 42 of the first printed circuit board 4A. The first coil pattern 52 on the front surface 41 of the first printed circuit board 4A extends halfway around the front surface 41, then crosses over to the back surface 42 of the first printed circuit board 4A via a through hole 54, and the first coil pattern 52 on the back surface 42 extends halfway around the back surface 42. The number of turns of each of the six first coil patterns 52 is the product of the number of turns of each first coil pattern 52 before winding around the first printed circuit board 4A and the number of layers of the first printed circuit board 4A stacked in the radial direction. The number of turns of each of the six first coil patterns 52 may be determined arbitrarily. A connection portion 55 is provided on the front surface 41 of the first printed circuit board 4A to electrically connect the other ends of the first coil patterns 52 of each phase. The connection portion 55 extends in the axial direction.

[0055] The first coil pattern 52 includes a plurality of first long side portions 52a and a plurality of first short side portions 52b extending in the circumferential direction. The first long side portions 52a and the first short side portions 52b are arranged alternately. The first long side portions 52a are portions that contribute to generating thrust that moves the mover in the axial direction. The first short side portions 52b are portions that do not contribute much to generating thrust that moves the mover in the axial direction. The first short side portions 52b serve to connect the two first long side portions 52a on the front and back sides. The first short side portions 52b shown in FIG. 14 extend while inclining so as to be positioned on one side in the axial direction as they move away from the first long side portions 52a. The first short side portions 52b shown in FIG. 15 extend while inclining so as to be positioned on the other side in the axial direction as they move away from the first long side portions 52a. A terminal 52c is provided at one end of the first coil pattern 52 on the back surface 42 to which a power line from a power supply unit (not shown) is connected. Power is supplied to each first coil pattern 52 from a power supply unit (not shown) via the terminal 52c. The terminal 52c protrudes axially outward from one axial end face of the first printed circuit board 4A. "Outward in the axial direction" means the direction from the axial center toward the axial end face of the first printed circuit board 4A.

[0056] As shown in FIG. 14 , each first coil pattern 52 has two coil ends 51 c, 51 d located at one end and the other end in the circumferential direction. The coil ends 51 c, 51 d of the first coil pattern 52 are located at one end and the other end in the longitudinal direction of the first long side portion 52 a of the first coil pattern 52. As shown in FIG. 13 , the first circumferential angle θ1 formed by the two coil ends 51 c, 51 d is equal to the electrical angle period of the rotating coil group 5B or an integer multiple of the electrical angle period of the rotating coil group 5B. The first angle θ1 is the circumferential angle formed by the two coil ends 51 c, 51 d with respect to the axis 57, which is the center of winding around the printed circuit board 4, as the base point. The first angle θ1 is preferably greater than 0 degrees. In this embodiment, a case where the first angle θ1 exceeds 0 degrees is illustrated. When the first angle θ1 exceeds 0 degrees, the two coil ends 51c, 51d are misaligned in the circumferential direction in the same first coil pattern 52. The first angle θ1 is equal to 2n times the second angle θ2 shown in FIG.

[0057] As shown in FIG. 14 , the circumferential positions of the coil ends 51 c of different first coil patterns 52 may be the same as shown, or may be offset. The circumferential positions of the coil ends 51 d of different first coil patterns 52 may be the same as shown, or may be offset. As shown in FIG. 12 , the circumferential positions of the coil ends 51 c of one axially adjacent first coil pattern 52 and the coil ends 51 d of the other adjacent first coil pattern 52 may be offset as shown, or may be the same. When the winding angle A of the first coil pattern 52 is represented by A, the number of turns of the first coil pattern 52 is represented by T, and the first angle is represented by θ1, and the winding angle A is expressed by the following equation (2), it is preferable that the winding angles A of the first coil patterns 52 are the same. A = 360 degrees × T + θ1 (2)

[0058] As shown in FIGS. 16 and 17 , the number of second coil patterns 53 is 18 in this embodiment. In this embodiment, there are nine second coil patterns 53 on each of the front surface 41 and the back surface 42 of the second printed circuit board 4B. The nine second coil patterns 53 on the front surface 41 are arranged in the circumferential direction. The nine second coil patterns 53 on the back surface 42 are arranged in the circumferential direction. The multiple second coil patterns 53 are multiple rotating coils arranged in the circumferential direction. Here, the number of coils in the rotating coil is defined as the number of circumferential areas in which the same-phase second coil patterns 53 exist, counted without distinction between the front surface 41 and the back surface 42 of the second printed circuit board 4B. The division of the circumferential areas in which the same-phase second coil patterns 53 exist is based on the second long side 53 a (described later), and portions other than the second long side 53 a are not taken into consideration. Therefore, when viewed in a direction from the front surface 41 to the back surface 42 of the second printed circuit board 4B, if the circumferential area in which the second long side 53 a of the second coil pattern 53 of the same phase exists on the front surface 41 is located and the circumferential area in which the second long side 53 a of the second coil pattern 53 of the same phase exists on the back surface 42 are located at the same circumferential position, they are counted as one rotating coil. On the other hand, when viewed in a direction from the front surface 41 to the back surface 42 of the second printed circuit board 4B, if the circumferential area in which the second long side 53 a of the second coil pattern 53 of the same phase exists on the front surface 41 is located and the circumferential area in which the second long side 53 a of the second coil pattern 53 of the same phase exists on the back surface 42 are located at different circumferential positions, they are counted as different rotating coils. 16 and 17 , for example, there are nine circumferential areas on the front surface 41 where the second long side portions 53 a of the second coil patterns 53 of the same phase are present, and nine circumferential areas on the back surface 42 where the second long side portions 53 a of the second coil patterns 53 of the same phase are present, and six of these circumferential areas are located at different circumferential positions and six of these circumferential areas are located at the same circumferential position. Therefore, the number of coils in the rotating coil is counted as 12. Each second coil pattern 53 has approximately the same shape.Each second coil pattern 53 is printed on the second printed circuit board 4B in a distributed winding manner, in which loops of the same shape are wound with their centers shifted at regular intervals in the circumferential direction. Two ends D1...D5, E1...E5, F1...F5 located at the same position on the front surface 41 and back surface 42 of the second printed circuit board 4B are electrically connected via through holes 54. Two ends G1...G5, H1...H5, I1...I5 located at the same position on the front surface 41 and back surface 42 of the second printed circuit board 4B are electrically connected via through holes 54. Two ends J1...J5, K1...K5, L1...L5 located at the same position on the front surface 41 and back surface 42 of the second printed circuit board 4B are electrically connected via through holes 54.

[0059] The second coil patterns 53 are alternately arranged on the front surface 41 and the back surface 42 of the second printed circuit board 4B. The second coil pattern 53 on the front surface 41 of the second printed circuit board 4B extends halfway around the front surface 41, then crosses over to the back surface 42 of the second printed circuit board 4B via a through hole 54, and the second coil pattern 53 on the back surface 42 extends halfway around the back surface 42. The number of turns of each of the 18 second coil patterns 53 is the product of the number of turns of each second coil pattern 53 before winding around the second printed circuit board 4B and the number of layers of the second printed circuit board 4B stacked in the radial direction. The number of turns of each of the 18 second coil patterns 53 may be determined arbitrarily. The front surface 41 of the second printed circuit board 4B has a connection portion 56 that electrically connects the other ends of the second coil patterns 53 of each phase. The connection portion 56 extends in the circumferential direction. The connection parts 55 and 56 may be, for example, neutral points or delta connections.

[0060] The second coil pattern 53 includes a plurality of second long side portions 53a and a plurality of second short side portions 53b extending in the axial direction. The second long side portions 53a and the second short side portions 53b are arranged alternately. The second long side portions 53a are portions that contribute to generating torque to rotate the mover. The second short side portions 53b are portions that do not contribute much to generating torque to rotate the mover. The second short side portions 53b serve to connect the two second long side portions 53a on the front and rear sides. The second short side portions 53b shown in FIG. 16 extend while inclining so as to be positioned on one side of the circumferential direction as they move away from the second long side portions 53a. The second short side portions 53b shown in FIG. 17 extend while inclining so as to be positioned on the other side of the circumferential direction as they move away from the second long side portions 53a. A terminal 53c to which a power supply line from a power supply unit (not shown) is connected is provided at one end of the second coil pattern 53 on the back surface 42. Power is supplied from the power supply unit (not shown) via the terminal 53c to each second coil pattern 53. The terminal 53c protrudes outward in the axial direction beyond the other axial end face of the second printed circuit board 4B.

[0061] The first long sides 52a of each first coil pattern 52 shown in Figures 14 and 15 extend parallel to each other. The second long sides 53a of each second coil pattern 53 shown in Figures 16 and 17 extend parallel to each other. The first long sides 52a of each first coil pattern 52 shown in Figures 14 and 15 and the second long sides 53a of each second coil pattern 53 shown in Figures 16 and 17 extend in directions that intersect with each other. In this embodiment, the first long sides 52a and the second long sides 53a extend in directions that are perpendicular to each other.

[0062] As shown in FIG. 12 , each printed circuit board 4 is wound clockwise so that the front surface 41 on which the coil group 5 is formed is located on the outer periphery and the back surface 42 is located on the inner periphery. Each printed circuit board 4 may also be wound so that the front surface 41 on which the coil group 5 is formed is located on the inner periphery and the back surface 42 is located on the outer periphery. Each printed circuit board 4 is wound along the cylindrical surface of a jig (not shown). The first printed circuit board 4A and the second printed circuit board 4B are wound continuously so that the other circumferential end 44 of the first printed circuit board 4A shown in FIGS. 14 and 15 is continuous with one circumferential end 43 of the second printed circuit board 4B shown in FIGS. 16 and 17 . This results in the cylindrical multi-axis actuator coil 1C shown in FIG. 12 . The outer circumferential surface of the multi-axis actuator coil 1C becomes the front surface 41 of the first printed circuit board 4A.

[0063] The first printed circuit board 4A and the second printed circuit board 4B shown in Figures 14 to 17 may or may not be connected by a fixing means such as adhesive or tape. In the latter case, after winding the second printed circuit board 4B located on the inner periphery, the first printed circuit board 4A may be wound so as to be continuous with one circumferential end 43 of the second printed circuit board 4B. Since the second printed circuit board 4B located on the inner periphery can be used as a guide to wind the second first printed circuit board 4A, the multi-axis actuator coil 1C can be easily formed.

[0064] The direct-acting coil group 5A is disposed on the outer periphery of the rotating coil group 5B. That is, the direct-acting coil group 5A and the rotating coil group 5B are disposed at the same position in the circumferential direction. In other words, the direct-acting coil group 5A and the rotating coil group 5B are disposed side by side in the radial direction. Between the direct-acting coil group 5A and the rotating coil group 5B disposed side by side in the radial direction, for example, an insulating layer (not shown) is sandwiched around the entire circumference. This prevents short circuits between the direct-acting coil group 5A and the rotating coil group 5B.

[0065] Next, the effects of the multi-axis actuator 100C according to this embodiment will be described.

[0066] In this embodiment, as in the first embodiment described above, the sum of the direct-acting side interference magnetic flux generated from each phase of the rotating coil group 5B is theoretically zero, and the direct-acting side interference magnetic flux generated from the rotating coil group 5B can be prevented from interfering with the direct-acting coil group 5A.

[0067] In this embodiment, as shown in FIGS. 12 and 13 , the multi-axis actuator coil 1C includes a flexible printed circuit board 4 wound around a single axis 57 and a plurality of linear coil groups 5A and rotary coil groups 5B printed on the printed circuit board 4. This configuration allows the printed circuit board 4 to be easily deformed, thereby easily deforming the printed circuit board 4 along with the printed linear coil groups 5A and rotary coil groups 5B. That is, in this embodiment, the linear coil groups 5A and rotary coil groups 5B can be easily and accurately aligned in the radial direction. As a result, this embodiment is less susceptible to winding collapse and winding intertwining, suppressing the enlargement of the multi-axis actuator coil 1C and the coil space. Therefore, the multi-axis actuator coil 1C can be formed with high space efficiency. Furthermore, suppressing the enlargement of the coil space can suppress the enlargement of the multi-axis actuator 100C and the reduction in the output density of the multi-axis actuator 100C.

[0068] Next, a modification of the fourth embodiment will be described.

[0069] In this embodiment, as shown in FIG. 13, the printed circuit board 4 is wound in a cylindrical shape, but the printed circuit board 4 may also be wound so that the cross-sectional shape perpendicular to the axis 57 of the printed circuit board 4 is a polygonal cylindrical shape.

[0070] The amount of winding of the first printed circuit board 4A and the second printed circuit board 4B shown in Figures 14 to 17 may be changed as appropriate. For example, each printed circuit board 4 may be wound more than one turn. This makes it possible to accommodate the multi-axis actuator 100C, which requires a larger number of turns of the coil pattern 51.

[0071] The number of coil patterns 51 in each of the direct-acting coil group 5A and the rotating coil group 5B is not limited to the illustrated example and may be changed as appropriate. Also, although FIGS. 14 to 17 illustrate a case where each of the direct-acting coil group 5A and the rotating coil group 5B is a three-phase coil, this is not limiting. Each of the direct-acting coil group 5A and the rotating coil group 5B may be a four- or more-phase coil. Also, in this embodiment, lap winding is illustrated as an example of distributed winding of each coil pattern 51, but this is not limiting. The distributed winding of each coil pattern 51 may be, for example, wave winding.

[0072] Fig. 18 is a perspective view showing a coil 1C for a multi-axis actuator according to a modification of the fourth embodiment. Fig. 19 is a view of the coil 1C for a multi-axis actuator according to a modification of the fourth embodiment as viewed along the axial direction. As shown in Figs. 18 and 19, in the same first coil pattern 52, the circumferential positions of two coil ends 51c, 51d may be the same. With this configuration, the first angle θ1 becomes 0 degrees.

[0073] Fifth Embodiment Next, a multi-axis actuator 100D according to a fifth embodiment will be described with reference to FIGS. 20 to 24 . FIG. 20 is a side view showing a state of a multi-axis actuator coil 1D according to the fifth embodiment before winding around a first printed circuit board 4A, illustrating the surface 41 of the first printed circuit board 4A. FIG. 21 is a side view showing a state of a multi-axis actuator coil 1D according to the fifth embodiment before winding around a first printed circuit board 4A, illustrating the back surface 42 of the first printed circuit board 4A seen through the surface 41. FIG. 22 is a side view showing a state of a multi-axis actuator coil 1D according to the fifth embodiment before winding around a second printed circuit board 4B, illustrating the surface 41 of the second printed circuit board 4B. FIG. 23 is a side view showing a state of a multi-axis actuator coil 1D according to the fifth embodiment before winding around a second printed circuit board 4B, illustrating the back surface 42 of the second printed circuit board 4B seen through the surface 41. FIG. 24 is a perspective view showing a multi-axis actuator coil 1D according to the fifth embodiment. This embodiment differs from the fourth embodiment in that the number of direct-acting coils facing the rotary coil group 5B in the radial direction is the same for each phase, the number of direct-acting coils for each phase is even, and the axial length P3 of the direct-acting coil group 5A in the multi-axis actuator coil 1D is shorter than the axial length P4 of the second long side portion 53a of the rotary coil group 5B. Note that in the fifth embodiment, parts that overlap with those in the fourth embodiment are denoted by the same reference numerals and will not be described again. While the back surface 42 is not visible in FIGS. 21 and 23, the reference numerals for the front surface 41 and the back surface 42 are shown together for ease of explanation.

[0074] As shown in FIGS. 20 and 21 , the axial length P3 of the direct-acting coil group 5A is the length from one axial end P31 to the other axial end P32 of the direct-acting coil group 5A. Specifically, the axial length P3 of the direct-acting coil group 5A is the length from the first long side portion 52a located at one axial end to the first long side portion 52a located at the other axial end. As shown in FIGS. 22 and 23 , the axial length P4 of the second long side portion 53a is the length from one axial end to the other axial end of the second long side portion 53a of the rotating coil group 5B. In FIGS. 20 and 21 , there are three axial areas where the first long side portions 52a of the first coil pattern 52 on the front surface 41 are present, and there are three axial areas where the first long side portions 52a of the first coil pattern 52 on the back surface 42 are present, and the axial positions of the six axial areas are different from each other. Therefore, the number of coils in the direct-acting coil is six. The number of direct-acting coils facing the rotary coil group 5B in the radial direction is the same for each phase, and the number of direct-acting coils for each phase is an even number. Fig. 24 shows, as an example, a case where the direct-acting coil group 5A is a three-phase coil and the number of direct-acting coils for each phase is two.

[0075] Next, the effects of the multi-axis actuator 100D according to this embodiment will be described.

[0076] This embodiment can achieve the same effects as the fourth embodiment. In this embodiment, as shown in FIGS. 20, 21, and 24, the number of direct-acting coils facing the rotating coil group 5B in the radial direction is the same for each phase, and the number of direct-acting coils for each phase is even. Also, in this embodiment, as shown in FIG. 24, the axial length P3 of the direct-acting coil group 5A is shorter than the axial length P4 of the second long side portion 53a of the rotating coil group 5B. With these configurations, when the direct-acting coil group 5A is energized, the magnetic flux linking the rotating coil group 5B, i.e., the rotation-side interference magnetic flux, is balanced for each phase of the direct-acting coil group 5A. Therefore, the sum of the rotation-side interference magnetic flux generated from each phase of the direct-acting coil group 5A is theoretically zero, thereby preventing the rotation-side interference magnetic flux generated from the direct-acting coil group 5A from interfering with the rotating coil group 5B. That is, in this embodiment, it is possible to prevent both the magnetic flux generated from the rotary coil group 5B from interfering with the linear motion coil group 5A and the magnetic flux generated from the linear motion coil group 5A from interfering with the rotary coil group 5B. This further suppresses the occurrence of unintended induced currents, thereby further suppressing malfunction of the multi-axis actuator 100D.

[0077] Sixth Embodiment Next, a multi-axis actuator 100E according to a sixth embodiment will be described with reference to FIGS. 25 to 28 . FIG. 25 is a side view showing a state of a multi-axis actuator coil 1E according to the sixth embodiment before winding around a first printed circuit board 4A, illustrating the surface 41 of the first printed circuit board 4A. FIG. 26 is a side view showing a state of a multi-axis actuator coil 1E according to the sixth embodiment before winding around a first printed circuit board 4A, illustrating the back surface 42 of the first printed circuit board 4A seen through the surface 41. FIG. 27 is a side view showing a state of a multi-axis actuator coil 1E according to the sixth embodiment before winding around a second printed circuit board 4B, illustrating the surface 41 of the second printed circuit board 4B. FIG. 28 is a side view showing a state of a multi-axis actuator coil 1E according to the sixth embodiment before winding around a second printed circuit board 4B, illustrating the back surface 42 of the second printed circuit board 4B seen through the surface 41. This embodiment differs from the fourth embodiment in that the axial length P4 of the second long side portion 53a of the rotating coil group 5B is the same as 2m times the inter-pole distance P5, and that the axial length P3 of the linear motion coil group 5A in the multi-axis actuator coil 1E is longer than the axial length P4 of the second long side portion 53a of the rotating coil group 5B. Note that in the sixth embodiment, parts that overlap with the fourth and fifth embodiments are denoted by the same reference numerals and will not be described again. While the back surface 42 is not visible in Figures 26 and 28, the reference numerals for the front surface 41 and the back surface 42 are shown together for ease of explanation.

[0078] The axial length P3 of the direct-acting coil group 5A shown in Figures 25 and 26 is longer than the axial length P4 of the second long side portion 53a of the rotating coil group 5B shown in Figures 27 and 28. The axial length P4 of the second long side portion 53a is the same as 2m times the inter-pole distance P5 shown in Figure 8, where m is a natural number.

[0079] Next, the effects of the multi-axis actuator 100E according to this embodiment will be described.

[0080] This embodiment can achieve the same effects as the fourth embodiment. In this embodiment, the axial length P4 of the second long side portion 53 a of the rotating coil group 5B shown in FIGS. 27 and 28 is 2 m times the inter-pole distance P5 shown in FIG. 8 . Also, in this embodiment, as shown in FIGS. 25 to 28 , the axial length P3 of the direct-acting coil group 5A is longer than the axial length P4 of the second long side portion 53 a of the rotating coil group 5B. This configuration ensures that when the direct-acting coil group 5A is energized, the magnetic flux linking the rotating coil group 5B, i.e., the rotation-side interference magnetic flux, is balanced for each phase of the direct-acting coil group 5A. Therefore, the sum of the rotation-side interference magnetic flux generated from each phase of the direct-acting coil group 5A is theoretically zero, thereby preventing the rotation-side interference magnetic flux generated from the direct-acting coil group 5A from interfering with the rotating coil group 5B. That is, in this embodiment, it is possible to prevent both the magnetic flux generated from the rotary coil group 5B from interfering with the linear motion coil group 5A and the magnetic flux generated from the linear motion coil group 5A from interfering with the rotary coil group 5B. This makes it possible to further suppress the occurrence of unintended induced currents and further suppress malfunction of the multi-axis actuator 100E.

[0081] Seventh Embodiment Next, a multi-axis actuator 100F according to the seventh embodiment will be described with reference to FIGS. 29 to 31 . FIG. 29 is a side view showing a state of a multi-axis actuator coil 1F according to the seventh embodiment before winding around a second printed circuit board 4B, illustrating the surface 41 of the second printed circuit board 4B. FIG. 30 is a side view showing a state of a multi-axis actuator coil 1F according to the seventh embodiment before winding around a first printed circuit board 4A, illustrating the surface 41 of the first printed circuit board 4A. FIG. 31 is a view of a multi-axis actuator coil 1F according to the seventh embodiment as viewed along the axial direction. This embodiment differs from the fourth embodiment in that the coil pattern 51 is wound in a concentrated winding manner. Note that in the seventh embodiment, parts that overlap with those in the fourth embodiment are designated by the same reference numerals, and descriptions thereof will be omitted.

[0082] As shown in Figure 30, the number of first coil patterns 52 in this embodiment is three. The three first coil patterns 52 are arranged side by side in the axial direction. Each first coil pattern 52 is printed on the first printed circuit board 4A in a concentrated winding manner, with loops of the same shape but different sizes wound around the same center. The shape of the first coil pattern 52 is a snake-like pattern in which the size of the rectangular loops decreases from the outer periphery toward the inner periphery.

[0083] The first coil pattern 52 includes a plurality of first long side portions 52a extending in the circumferential direction and a plurality of first short side portions 52b extending in the axial direction. The first long side portions 52a and the first short side portions 52b are alternately arranged. The first short side portions 52b serve to connect two adjacent first long side portions 52a. A terminal 52d is provided on the other end of each first coil pattern 52, on the inner side of the loop opposite the terminal 52c. The terminals 52d of each first coil pattern 52 are connected to each other by a wire or jumper wire (not shown).

[0084] As shown in Figure 29, the number of second coil patterns 53 in this embodiment is six. The six second coil patterns 53 are arranged in a line in the circumferential direction. Each second coil pattern 53 has the same shape. Each second coil pattern 53 is printed on the second printed circuit board 4B in a concentrated winding manner, in which loops of the same shape but different sizes are wound around the same center. The shape of the second coil pattern 53 is a zigzag pattern that decreases in size from the outer periphery toward the inner periphery.

[0085] The second coil pattern 53 includes a plurality of second long side portions 53a extending in the axial direction and a plurality of second short side portions 53b extending in the circumferential direction. The second long side portions 53a and the second short side portions 53b are alternately arranged. The second short side portions 53b serve to connect two adjacent second long side portions 53a. A terminal 53d is provided on the other end of each second coil pattern 53, on the inner side of the loop opposite the terminal 53c. The terminals 53d of each second coil pattern 53 are connected to each other by a wire or jumper wire (not shown).

[0086] As shown in FIG. 31 , each printed circuit board 4 is wound clockwise so that the front surface 41 on which the coil group 5 is formed is located on the inner periphery and the back surface 42 is located on the outer periphery. Each printed circuit board 4 may also be wound so that the front surface 41 on which the coil group 5 is formed is located on the outer periphery and the back surface 42 is located on the inner periphery. Each printed circuit board 4 is wound along the cylindrical surface of a jig (not shown). The first printed circuit board 4A and the second printed circuit board 4B are wound continuously so that one circumferential end 43 of the first printed circuit board 4A is continuous with the other circumferential end 44 of the second printed circuit board 4B. This results in a cylindrical multi-axis actuator coil 1F. The outer circumferential surfaces of the multi-axis actuator coil 1F become the back surface 42 of the first printed circuit board 4A and the back surface 42 of the second printed circuit board 4B.

[0087] The direct-acting coil group 5A is disposed on the outer periphery of a portion of the rotating coil group 5B. That is, the direct-acting coil group 5A and a portion of the rotating coil group 5B are disposed at the same position in the circumferential direction. In other words, the direct-acting coil group 5A and a portion of the rotating coil group 5B are disposed side by side in the radial direction. The second printed circuit board 4B is disposed around the entire circumference and sandwiched between the direct-acting coil group 5A and a portion of the rotating coil group 5B, which are disposed side by side in the radial direction. This prevents short circuits between the direct-acting coil group 5A and the rotating coil group 5B.

[0088] Next, the effects of the multi-axis actuator 100F according to this embodiment will be described.

[0089] 31 is wound around a cylinder multiple times, the circumferential length per revolution of the printed circuit board 4 becomes longer as it approaches the outer periphery of the printed circuit board 4. Therefore, if the arrangement direction of the coil patterns 51 coincides with the circumferential direction and the circumferential width of each coil pattern 51 is equal, as in the rotating coil group 5B shown in FIG. 29, the more times the printed circuit board 4 is wound around the cylinder, the more phase shift occurs in which the coil patterns 51 of the same phase are shifted in the circumferential direction. Furthermore, the occurrence of phase shift changes the electrical phase for each revolution, which can lead to a problem of the electromagnetic characteristics of the multi-axis actuator being easily degraded.

[0090] 29 and 31 , in the present embodiment, the rotating coil group 5B arranged on the inner periphery of the wound printed circuit board 4 has the arrangement direction of the coil patterns 51 aligned with the circumferential direction, and the long sides 51 a extend in a direction perpendicular to the circumferential direction. In other words, the rotating coil group 5B, in which degradation of the electromagnetic characteristics of the multi-axis actuator 100F due to phase shift is likely to become noticeable, is arranged on the inner periphery of the printed circuit board 4, where the occurrence of phase shift is suppressed. With this configuration, degradation of the electromagnetic characteristics of the multi-axis actuator 100F can be suppressed compared to when the rotating coil group 5B is arranged on the outer periphery of the wound printed circuit board 4.

[0091] In addition, one of the coil patterns 51 of the direct-acting coil group 5A and the rotating coil group 5B may be printed on the printed circuit board 4 using concentrated winding, and the other of the direct-acting coil group 5A and the rotating coil group 5B may be printed on the printed circuit board 4 using distributed winding.

[0092] Eighth Embodiment Next, a multi-axis actuator 100G according to the eighth embodiment will be described with reference to FIGS. 32 to 34. FIG. 32 is a perspective view showing the multi-axis actuator 100G according to the eighth embodiment. FIG. 33 is a cross-sectional view taken along line XXXIII-XXXIII shown in FIG. 32. FIG. 34 is a cross-sectional view taken along line XXXIV-XXXIV shown in FIG. 32. This embodiment differs from the first embodiment in that it is a moving coil type multi-axis actuator 100G in which a multi-axis actuator coil 1G is disposed on the outer periphery of the rotor core 7. Note that in the eighth embodiment, parts that overlap with those in the first embodiment are designated by the same reference numerals and description thereof will be omitted.

[0093] As shown in FIGS. 32 to 34, the configurations of the housing 6, shaft 10, bearing 11, first position detector 12 and second position detector 13 are the same as those in the first embodiment.

[0094] 33, the stator core 9 is disposed on the inner periphery of the frame 6a. The magnet 8 is provided on the inner periphery of the stator core 9. The magnet 8 faces the multi-axis actuator coil 1G in the radial direction.

[0095] The multi-axis actuator coil 1G is disposed on the inner periphery of the magnet 8. The multi-axis actuator coil 1G is disposed with a gap between it and the magnet 8. The multi-axis actuator coil 1G includes a linear motion coil group 2 and a rotary coil group 3 disposed on the outer periphery of the linear motion coil group 2.

[0096] The rotor core 7 is disposed on the inner periphery of the multi-axis actuator coil 1G. In other words, the multi-axis actuator coil 1G is disposed on the outer periphery of the rotor core 7.

[0097] The shaft 10 is disposed on the inner periphery of the rotor core 7. The rotor core 7, the multi-axis actuator coil 1G, and the shaft 10 form a mover. The magnet 8, the stator core 9, and the frame 6a form a stator. The rotor core 7 and the multi-axis actuator coil 1G move together with the shaft 10 in the circumferential and axial directions.

[0098] Next, the effects of the multi-axis actuator 100G according to this embodiment will be described.

[0099] In this embodiment, the mover can be moved in multiple directions while achieving the same effects as in the first embodiment. Furthermore, if the multi-axis actuator coil 1G is a multi-axis actuator coil with a small number of turns, the mover can be made lighter, improving the responsiveness of the multi-axis actuator 100G. Furthermore, when the multi-axis actuator coil 1G is directly cylindrically molded, it becomes possible to mold the printed circuit board 4 while winding it directly around the rotor core 7, eliminating the need to prepare a separate cylindrical molding jig.

[0100] The configurations shown in the above embodiments are merely examples, and may be combined with other known technologies, or different embodiments may be combined with each other. It is also possible to omit or modify parts of the configurations as long as they do not deviate from the gist of the invention.

[0101] 1, 1A, 1B, 1C, 1D, 1E, 1F, 1G Coil for multi-axis actuator, 2, 5A Direct-acting coil group, 2a Direct-acting coil, 2b, 2c, 51c, 51d Coil end, 2d, 8e Shaft center, 3, 5B Rotating coil group, 3a Rotating coil, 3b, 51a Long side portion, 3c, 51b Short side portion, 4 Printed circuit board, 4A First printed circuit board, 4B Second printed circuit board, 5 Coil group, 6 Housing, 6a Frame, 6b Bracket, 6c Insertion hole, 6d Through hole, 7 Rotor core, 8 Magnet, 8a First magnet, 8b Second magnet, 8c First center, 8d Second center, 9 Stator core, 10 Shaft, 11 Bearing, 12 First position detector, 12a First scale, 12b First sensor, 13 Second position detector, 13a Second scale, 13b Second sensor, 41 Front surface, 42 Back surface, 43 One end, 44 Other end, 51 Coil pattern, 52 First coil pattern, 52a First long side portion, 52b First short side portion, 52c, 52d, 53c, 53d Terminal, 53 Second coil pattern, 53a Second long side portion, 53b Second short side portion, 54 Through hole, 55, 56 Connection portion, 57 Axis, 100, 100A, 100B, 100C, 100D, 100E, 100F, 100G Multi-axis actuator.

Claims

1. A multi-axis actuator comprising: a cylindrical multi-axis actuator coil; and a shaft arranged on the inner circumference of the multi-axis actuator coil, wherein the multi-axis actuator coil comprises: a group of linear motion coils generating a magnetic field that moves the shaft in the axial direction; and a group of rotary coils arranged on the inner or outer circumference of the group of linear motion coils and generating a magnetic field that moves the shaft in a circumferential direction, wherein the group of linear motion coils has a plurality of linear motion coils arranged side by side in the axial direction, each of the linear motion coils extending in the circumferential direction, each of the linear motion coils having two coil ends located at one end and the other end in the circumferential direction, and wherein a first angle in the circumferential direction formed by the two coil ends of each of the linear motion coils is equal to the electrical angle period of the group of rotary coils or is an integer multiple of the electrical angle period of the group of rotary coils.

2. The multi-axis actuator according to claim 1, characterized in that the winding angle A of the linear actuator coil is the same angle, where A is the winding angle of the linear actuator coil, T is the number of turns of the linear actuator coil, and θ1 is the first angle, and the winding angle A is expressed by the following formula: A = 360 degrees × T + θ1.

3. The multi-axis actuator according to claim 1 or 2, characterized in that the linear coil group and the rotating coil group are multi-phase coils, the number of linear coils radially facing the rotating coil group is the same for each phase and the number of linear coils for each phase is an even number, the rotating coil group includes a long side portion extending linearly in the axial direction, and the axial length of the linear coil group is shorter than the axial length of the long side portion.

4. A multi-axis actuator as claimed in claim 1 or 2, further comprising magnets arranged on the inner or outer circumference of the multi-axis actuator coil so as to face the multi-axis actuator coil in the radial direction, and also arranged on the outer circumference of the shaft, wherein the magnets include a plurality of first magnets having a first center, and a plurality of second magnets arranged adjacent to the first magnets and having a second center displaced from the first center in the axial and circumferential directions, the group of rotating coils includes a long side portion extending linearly in the axial direction, when the distance along the axial direction between the first center of adjacent first magnets and the second center of adjacent second magnets is defined as the inter-pole distance, the axial length of the long side portion is the same as 2m times the inter-pole distance, m is a natural number, and the axial length of the group of linear motion coils is longer than the axial length of the long side portion.

5. A multi-axis actuator as described in any one of claims 1 to 4, characterized in that the linear coil is a spirally wound magnet wire that extends in the circumferential direction while moving in the axial direction, the group of rotating coils is a spirally wound magnet wire that extends alternately in the axial and radial directions while moving in the circumferential direction, and the two coil ends of the linear coil are located at one end and the other end of the length of the magnet wire.

6. The multi-axis actuator according to claim 5, wherein the first angle is greater than 0 degrees.

7. The coil for the multi-axis actuator comprises: a printed circuit board which is flexible and wound in the circumferential direction; and the linear coil group and the rotary coil group printed on the printed circuit board, wherein the linear coil group has a plurality of first coil patterns which are each a plurality of the linear coils, and the rotary coil group has a plurality of second coil patterns, the first coil pattern includes a first long side portion which extends linearly in the circumferential direction, and the second coil pattern includes a second long side portion which extends linearly in the axial direction, the first long sides of the first coil patterns extend parallel to each other, the second long sides of the second coil patterns extend parallel to each other, and the first long sides of the first coil patterns and the second long sides of the second coil patterns extend in directions which intersect with each other, 5. The multi-axis actuator according to claim 1, wherein the two coil ends of the linear motion coil are located at one end and the other end in a longitudinal direction of the first long side portion of the first coil pattern.

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