Multi-phase linear motor

Abstract

To provide a multi-phase linear motor that can be miniaturized while ensuring sufficient thrust.SOLUTION: A multi-phase linear motor (1) that generates thrust in a predetermined direction includes: a magnetic circuit (2) formed of a magnet (14) and a yoke (12) and forming an air gap (18) through which a magnetic flux passes between a pair of opposing gap forming surfaces (16a, 16b); a coil assembly (4) formed of a plurality of drive coils (20, 22, 24) through which a drive current flows and disposed between the pair of gap forming surfaces of the magnetic circuit; and a magnetic sensor (6) for detecting the magnetic flux passing through the air gap, wherein the magnetic sensor is attached to at least one surface of the coil assembly facing the pair of air gap forming surfaces, and at least one of the pair of air gap forming surfaces is provided with a recess (28) extending in a thrust generating direction for receiving at least a part of the magnetic sensor.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a polyphase linear motor, and more particularly to a polyphase linear motor that generates a thrust force in a predetermined direction. [Background technology]

[0002] Polyphase linear motors generally have magnetic sensors that detect the magnetic flux passing through the coils and control the current flowing through each coil. In many cases, magnetic sensors are placed inside the coils to detect the magnetic flux. Some polyphase linear motors do not have magnetic sensors, but these require magnetic pole detection at startup, which is disadvantageous in terms of responsiveness.

[0003] Meanwhile, Japanese Patent Laid-Open Publication No. 2009-201264 (Patent Document 1) describes a coil unit for a three-phase linear motor and a three-phase linear motor. In this three-phase linear motor, the coils constituting the coil unit are combined so that the straight sections of the two coils are arranged between the straight sections of one coil. As a result, in the three-phase linear motor described in Patent Document 1, the straight sections of the coils that generate thrust can be arranged at high density, resulting in a linear motor that is small in size and can generate a large thrust. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-201264 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when coils are arranged in a manner similar to the three-phase linear motor described in Patent Document 1 to increase the coil mounting density, it is not possible to arrange a magnetic sensor inside the coil. Furthermore, for example, if a magnetic sensor were arranged outside the coil in the three-phase linear motor described in Patent Document 1, the coil unit would become larger. Alternatively, if a magnetic sensor were arranged on the top or bottom surface of the coil unit, it would be necessary to increase the air gap through which the magnetic flux passes to prevent interference between the magnets and yoke of the linear motor and the magnetic sensor. However, increasing the air gap would reduce the thrust that the linear motor can generate.

[0006] SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a polyphase linear motor that can be made compact while still ensuring sufficient thrust. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems, the present invention provides a polyphase linear motor that generates a thrust in a predetermined direction, comprising: a magnetic circuit composed of a magnet and a yoke, which forms an air gap between a pair of opposing gap-forming surfaces through which magnetic flux passes; a coil assembly composed of a plurality of drive coils through which a drive current flows, which is arranged between the pair of gap-forming surfaces of the magnetic circuit; and a magnetic sensor for detecting the magnetic flux passing through the air gap, wherein the magnetic sensor is attached to at least one surface of the coil assembly that faces the pair of gap-forming surfaces, and at least one of the pair of gap-forming surfaces has a recess extending in the thrust generation direction that receives at least a portion of the magnetic sensor.

[0008] According to the present invention configured as described above, the magnetic sensor is attached to at least one surface of the coil assembly, and at least one of the pair of air gap forming surfaces has a recess extending in the thrust generating direction that receives at least a portion of the magnetic sensor, so that the magnetic sensor can be disposed on the surface of the coil assembly without increasing the air gap, thereby enabling the polyphase linear motor to be miniaturized while still obtaining a large thrust. [Effects of the Invention]

[0009] According to the polyphase linear motor of the present invention, it is possible to reduce the size while ensuring a sufficient thrust. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a perspective view showing a polyphase linear motor according to a first embodiment of the present invention. [Figure 2] 1 is a front cross-sectional view of a polyphase linear motor according to a first embodiment of the present invention. [Figure 3] 1 is a side cross-sectional view of a polyphase linear motor according to a first embodiment of the present invention. [Figure 4] 1 is an exploded perspective view showing a polyphase linear motor according to a first embodiment of the present invention. [Figure 5] FIG. 10 is a front cross-sectional view of a polyphase linear motor according to a second embodiment of the present invention. [Figure 6] FIG. 10 is a front cross-sectional view of a polyphase linear motor according to a third embodiment of the present invention. [Figure 7] FIG. 10 is a perspective view showing an example in which the polyphase linear motor according to the fourth embodiment of the present invention is used as a force feedback motor. DETAILED DESCRIPTION OF THE INVENTION

[0011] Next, a polyphase linear motor according to an embodiment of the present invention will be described with reference to the accompanying drawings. In the following description, a case where a polyphase linear motor according to an embodiment of the present invention is used as an actuator for driving a lens frame in the optical axis direction will be exemplified. Fig. 1 is a perspective view showing a polyphase linear motor according to a first embodiment of the present invention. Fig. 2 is a front sectional view of the polyphase linear motor according to the first embodiment of the present invention. Fig. 3 is a side sectional view of the polyphase linear motor according to the first embodiment of the present invention. Fig. 4 is an exploded perspective view showing the polyphase linear motor according to the first embodiment of the present invention.

[0012] 1, the polyphase linear motor 1 of this embodiment has a magnetic circuit 2, a coil assembly 4 placed in the air gap of this magnetic circuit 2, and a Hall sensor 6, which is a magnetic sensor, attached to the upper surface of the coil assembly 4. In this embodiment, this polyphase linear motor 1 is used as an actuator for driving a lens frame 8 in the direction of the optical axis A.

[0013] 2, two guide poles 10 extending in the direction of optical axis A are attached inside lens barrel B, and lens frame 8 is attached to guide poles 10 so as to be slidable in the direction of optical axis A. Furthermore, coil assembly 4 constituting polyphase linear motor 1 is fixed to lens frame 8, and magnetic circuit 2 is fixed to lens barrel B. By passing a drive current through the coils of coil assembly 4, a thrust force in a predetermined direction is generated in coil assembly 4, and lens frame 8 attached to coil assembly 4 is driven in the direction of optical axis A.

[0014] Next, as shown in FIGS. 3 and 4, the magnetic circuit 2 is composed of a yoke 12 and a magnet 14. In this embodiment, the yoke 12 is formed by combining two plates 12a and 12b made of a ferromagnetic material and bent into an L shape. That is, the plates 12a and 12b are steel plates bent into an L shape, and by joining the two identical plates 12a and 12b facing each other, the yoke 12 is formed into a ring shape with opposing parallel surfaces.

[0015] In this embodiment, the magnet 14 is composed of four identical rectangular, flat-plate-shaped permanent magnets 14a to 14d. Furthermore, in this embodiment, the permanent magnets 14a to 14d are rare-earth magnets. These permanent magnets 14a to 14d are fixed in pairs, arranged side by side, inside the parallel surfaces of the annular yoke 12 so as to extend in the direction of the optical axis A (the direction in which thrust is generated). That is, of the opposing parallel surfaces formed by the yoke 12, the permanent magnets 14a and 14b are attached side by side to the upper surface, and the permanent magnets 14c and 14d are attached side by side to the lower surface.

[0016] As a result, the bottom surface of permanent magnet 14a faces the top surface of permanent magnet 14c, and the bottom surface of permanent magnet 14b faces the top surface of permanent magnet 14d, respectively, and magnetic flux passes between these facing surfaces. Therefore, the bottom surfaces of permanent magnets 14a and 14b form air gap forming surface 16a, and the top surfaces of permanent magnets 14c and 14d form air gap forming surface 16b. Furthermore, this pair of air gap forming surfaces 16a and 16b face each other, and an air gap 18 through which magnetic flux passes is formed between these air gap forming surfaces (FIG. 3).

[0017] Next, in this embodiment, the coil assembly 4 is composed of three drive coils 20, 22, and 24, and a flexible substrate 26 is attached to the upper surface of each of them. These three drive coils 20, 22, and 24 are all flat coils wound in the shape of a long, narrow rectangle with rounded corners, and the straight portions (long sides) of these drive coils are arranged in the air gap 18 formed by the magnetic circuit 2.

[0018] 4, both ends of drive coil 20 are curved upward, while both ends of drive coil 24 are curved downward. Drive coil 22 has both ends that are not curved but are flat. Drive coil 20 is assembled from above flat drive coil 22, and drive coil 24 is assembled from below.

[0019] 3, the straight portion 20b of the drive coil 20 and the straight portion 24a of the drive coil 24 can be arranged between the straight portions 22a and 22b of the drive coil 22 without the drive coils interfering with each other. In this manner, in this embodiment, the straight portions of one drive coil constituting the coil assembly 4 are arranged with substantially no gaps between the straight portions of the other drive coils. As a result, the straight portions of the coils can be arranged adjacent to each other, and the drive coils can be arranged at high density.

[0020] Each straight portion of the drive coils 20, 22, 24 configured in this manner is disposed between a pair of gap-forming surfaces 16a and 16b formed by the magnetic circuit 2. As a result, the upper surface of the coil assembly 4 made up of the drive coils 20, 22, 24 faces the gap-forming surface 16a, and the lower surface of the coil assembly 4 faces the gap-forming surface 16b. A magnetic flux is formed between the pair of opposing gap-forming surfaces 16a and 16b, and by passing a predetermined drive current through each of the drive coils 20, 22, 24, a thrust is generated in the coil assembly 4 in the direction of the optical axis A (left-right direction in FIG. 3).

[0021] Next, the flexible substrate 26 is a thin, flexible circuit board, and a portion of it is attached to the upper surface of each of the flatly wound drive coils. Furthermore, three Hall sensors 6, which are magnetic sensors, are attached to the upper surface of the flexible substrate 26, arranged in a row in the thrust generation direction. Thus, in this embodiment, each Hall sensor 6 is attached to the surface of the coil assembly 4 that faces the gap forming surface 16a. A detection signal from each Hall sensor 6 is transmitted via a circuit pattern (not shown) formed on the flexible substrate 26, and the current flowing through each drive coil is controlled based on this signal.

[0022] Next, the magnetization state of each permanent magnet will be described. As shown in FIG. 3, the plate-shaped permanent magnets 14a, 14c are magnetized so that the north and south poles are reversed in the thickness direction. Furthermore, the magnetic poles appearing on the gap-forming surfaces 16a, 16b of each permanent magnet are magnetized so that they alternate at a predetermined pitch in the longitudinal direction. Therefore, each gap-forming surface 16a, 16b is magnetized with north and south poles repeatedly alternated at a predetermined interval. Furthermore, the gap-forming surface 16b is magnetized with an south pole facing the north pole of the gap-forming surface 16a, and the gap-forming surface 16b is magnetized with an north pole facing the south pole of the gap-forming surface 16a. In other words, the permanent magnets 14a, 14c are magnetized so that the magnetic poles are reversed at the portions where the gap-forming surfaces 16a and 16b face each other.

[0023] Furthermore, as shown in FIG. 3, the longitudinal pitch at which the magnetization is reversed is three times the width of each straight portion of the drive coils 20, 22, and 24. That is, in the state shown in FIG. 3, an S pole is formed on the gap-forming surface 16a and an N pole is formed on the gap-forming surface 16b so as to face the three straight portions 20a, 22a, and 24a of each adjacent drive coil. On the other hand, an N pole is formed on the gap-forming surface 16a and an S pole is formed on the gap-forming surface 16b so as to face the three straight portions 20b, 22b, and 24b. Note that while only permanent magnets 14a and 14c are shown in FIG. 3, permanent magnet 14b arranged adjacent to permanent magnet 14a is magnetized similarly to permanent magnet 14a, and permanent magnet 14d arranged adjacent to permanent magnet 14c is magnetized similarly to permanent magnet 14c.

[0024] For this reason, in the state shown in Fig. 3, when a current is passed through linear portions 22a and 24a of the three linear portions from the back side to the front side of the page in Fig. 3, a thrust force is generated in these linear portions from the right side to the left side in Fig. 3. At this time, a current also flows through other linear portions 22b and 24b from the front side to the back side of the page in Fig. 3, and a thrust force is also generated in these linear portions from the right side to the left side in Fig. 3. Furthermore, in the state shown in Fig. 3, when a current is passed in the opposite direction through drive coils 20 and 22 of the three drive coils, a thrust force is generated in each drive coil from the left side to the right side in Fig. 3.

[0025] When the coil assembly 4 (each drive coil) is moved by a thrust acting on it, the magnetic field detected by each Hall sensor 6 attached to the coil assembly 4 changes. Based on the detection signal detected by each Hall sensor 6, the drive coil through which current flows is sequentially switched among the three drive coils, thereby making it possible to obtain a thrust in the desired direction.

[0026] Next, as shown in FIG. 4, the three Hall sensors 6 are arranged side by side in the direction of the optical axis A on the flexible substrate 26. These Hall sensors 6 are attached to the surface of the coil assembly 4 that faces the gap-forming surface 16a (the upper surface of the coil assembly 4). Therefore, in this embodiment, each Hall sensor 6 protrudes upward from the coil assembly 4 toward the gap-forming surface 16a. As shown in FIG. 2, the gap-forming surface 16a is formed by the lower surfaces of two permanent magnets 14a and 14b that are arranged side by side. A gap of a certain width is provided between these two permanent magnets 14a and 14b, and the upper part of each Hall sensor 6 is received in this gap.

[0027] That is, a recess 28 of a constant width extending in the direction of the optical axis A (thrust generation direction) is formed in the gap forming surface 16a of the magnetic circuit 2 by providing a gap between the two permanent magnets 14a, 14b, and a portion of each Hall sensor 6 is received in this recess 28. In this way, in the polyphase linear motor 1 of this embodiment, the recess 28 extending in the thrust generation direction is provided in the gap forming surface 16a of the magnetic circuit 2, and the Hall sensor 6 is attached to the upper surface of the coil assembly 4 opposing the gap forming surface 16a so as to protrude toward the gap forming surface 16a.

[0028] In this way, a portion of the Hall sensor 6 is received in the recess 28 of the gap forming surface 16a, so that the upper surface of the coil assembly 4 can be disposed close to the gap forming surface 16a while avoiding interference between the gap forming surface 16a and the Hall sensor 6. This allows the polyphase linear motor 1 to be made smaller and the thrust force generated by the polyphase linear motor 1 to be increased.

[0029] The Hall sensor 6 used in the polyphase linear motor 1 of this embodiment has a built-in semiconductor chip that generates a galvanomagnetic effect as the magnetic detection portion 6a (FIG. 2). The Hall sensor 6 is configured to detect a magnetic field acting on the magnetic detection portion 6a. The magnetic detection portion 6a is built into the Hall sensor 6 at a position close to the flexible substrate 26. Therefore, as shown in FIG. 2, although a portion of the Hall sensor 6 is received in the recess 28, the built-in magnetic detection portion 6a is located outside the recess 28. That is, magnetic flux is easily disturbed inside the recess 28 provided in the gap forming surface 16a, but the magnetic flux is less disturbed outside the recess 28. Therefore, by arranging the Hall sensor 6 so that its magnetic detection portion 6a is located outside the recess 28, magnetic flux with less disturbance can be detected, improving position detection accuracy.

[0030] According to the polyphase linear motor 1 of the first embodiment of the present invention, the Hall sensor 6, which is a magnetic sensor, is attached to one surface (top surface) of the coil assembly 4, and the gap forming surface 16a, of the pair of gap forming surfaces 16a, 16b, is provided with a recess 28 extending in the thrust generating direction (the direction of the optical axis A) to receive a portion of the Hall sensor 6. As a result, the Hall sensor 6 can be disposed on the surface of the coil assembly 4 without increasing the air gap 18. This allows the polyphase linear motor 1 to be miniaturized while still obtaining a large thrust.

[0031] Furthermore, according to the multi-phase linear motor 1 of this embodiment, the coil assembly 4 has the straight portion 20b of one drive coil 20 and the straight portion 24a of the other drive coil 24 arranged between the straight portions 22a, 22b of one drive coil 22 that make up the coil assembly 4, so that the straight portions of the drive coils that generate thrust can be arranged at high density, and the thrust can be increased while the multi-phase linear motor 1 is made smaller.

[0032] Furthermore, according to the polyphase linear motor 1 of this embodiment, the gap-forming surface 16a of the magnetic circuit 2 is configured by arranging the permanent magnets 14a, 14b extending in the thrust generation direction side by side, and the recess 28 is formed by the gap between the permanent magnets 14a, 14b arranged side by side, so that the recess can be easily formed in the magnetic circuit.

[0033] Furthermore, according to the multi-phase linear motor 1 of this embodiment, the Hall sensor 6, which is a magnetic sensor, is provided with a magnetic detection portion 6a, and this magnetic detection portion 6a is located outside the recess 28 provided in the gap forming surface 16a of the magnetic circuit 2, so that the magnetic sensor can detect magnetic flux with little disturbance extending between the opposing gap forming surfaces 16a, 16b, thereby improving the accuracy of position detection by the magnetic sensor.

[0034] Next, a polyphase linear motor according to a second embodiment of the present invention will be described with reference to FIG. The multi-phase linear motor of this embodiment differs from the first embodiment in the configuration of the magnets. Therefore, only the differences between the second embodiment of the present invention and the first embodiment will be described below, and a description of the same configurations, actions, and effects will be omitted. Figure 5 is a front cross-sectional view of the multi-phase linear motor according to the second embodiment of the present invention.

[0035] As shown in FIG. 5, a polyphase linear motor 100 according to a second embodiment of the present invention includes a magnetic circuit 102, a coil assembly 104 disposed in the air gap of the magnetic circuit 102, and Hall sensors 106a and 106b, which are magnetic sensors attached to the upper and lower surfaces of the coil assembly 104, respectively.

[0036] The magnetic circuit 102 is made up of a yoke and a magnet. In this embodiment, the yoke is made up of two plates 12a and 12b bent into an L shape, similar to the first embodiment.

[0037] In the first embodiment described above, the magnets were composed of four rectangular, flat-plate permanent magnets. However, in this embodiment, the magnets are composed of two permanent magnets 114a and 114b attached to the inside of an annular yoke. That is, the permanent magnets 114a and 114b are each configured as a rectangular, flat plate and fixed so as to face each other on the inner side of the parallel surfaces of the annular yoke. This positions the bottom surface of the permanent magnet 114a and the top surface of the permanent magnet 114b so as to face each other. The bottom surface of the permanent magnet 114a forms the gap-forming surface 116a, and the top surface of the permanent magnet 114b forms the gap-forming surface 116b, forming an air gap between them through which magnetic flux passes.

[0038] In this embodiment, the permanent magnets 114a, 114b are also magnetized so that the north and south poles are reversed in the thickness direction. Furthermore, the magnetic poles appearing on the gap forming surfaces 116a, 116b of each permanent magnet are magnetized so that they alternately reverse at a predetermined pitch in the longitudinal direction. Furthermore, the permanent magnets 114a, 114b are magnetized so that the magnetic poles are reversed at the portions where the gap forming surfaces 116a and 116b face each other.

[0039] Furthermore, the coil assembly 104 is made up of three drive coils 20, 22, and 24, and its structure is the same as that of the first embodiment described above. Furthermore, in this embodiment, flexible substrates are attached to the upper and lower surfaces of the coil assembly 104, and Hall sensors 106a and 106b, which are magnetic sensors, are attached to these flexible substrates, respectively.

[0040] Furthermore, recesses 128a, 128b extending in the thrust direction of the polyphase linear motor 100 are provided at positions facing the Hall sensors 106a, 106b attached to the upper and lower surfaces of the coil assembly 104, respectively. A portion of each Hall sensor 106a, 106b is received in each recess 128a, 128b. That is, in this embodiment, the recess 128a is formed by forming a groove extending in the thrust direction (a direction perpendicular to the plane of FIG. 5 ) in the gap-forming surface 116a on the lower surface of the permanent magnet 114a. Similarly, the recess 128b is formed by forming a groove extending in the thrust direction in the gap-forming surface 116b on the upper surface of the permanent magnet 114b. Furthermore, in this embodiment, one Hall sensor is disposed so as to be received in each recess. However, as in the first embodiment, multiple Hall sensors may be provided so as to be received in one recess.

[0041] According to the polyphase linear motor 100 of the second embodiment of the present invention, the Hall sensors 106a and 106b, which are magnetic sensors, are attached to the upper and lower surfaces of the coil assembly 104, respectively, so that the magnetic sensors can be placed closer to the direction in which the thrust of the linear motor is generated. This allows the pitch of the magnetic poles to be finer, making it possible to make the motor more compact.

[0042] Furthermore, according to the polyphase linear motor 100 of this embodiment, the recesses 128a, 128b provided in the gap forming surfaces 116a, 116b are provided by forming grooves in a single plate-shaped permanent magnet, which reduces the number of parts and enables precise alignment of the magnetization positions on both sides of each recess.

[0043] Next, a polyphase linear motor according to a third embodiment of the present invention will be described with reference to FIG. The polyphase linear motor of this embodiment differs from the first embodiment in the configuration of the magnetic circuit. Therefore, only the differences between the third embodiment of the present invention and the first embodiment will be described below, and a description of the same configuration, action, and effects will be omitted. Figure 6 is a front cross-sectional view of the polyphase linear motor according to the third embodiment of the present invention.

[0044] As shown in FIG. 6, a polyphase linear motor 200 according to a third embodiment of the present invention includes a magnetic circuit 202, a coil assembly 204 disposed in the air gap of the magnetic circuit 202, and Hall sensors 206a and 206b, which are magnetic sensors attached to the underside of the coil assembly 204.

[0045] The magnetic circuit 202 is made up of a yoke and a magnet. In this embodiment, the yoke is made up of two plates 212a and 212b bent into an L-shape, which are combined to form a ring-shaped yoke.

[0046] In the first and second embodiments described above, the magnets were attached to the inside of the annular yoke so as to face each other, but in this embodiment, the permanent magnets 214 are attached to only one of the parallel inner surfaces of the yoke. That is, in this embodiment, the rectangular, flat-plate-shaped permanent magnets 214 are attached only to the upper of the opposing parallel surfaces of the yoke, and no permanent magnets are attached to the lower surface of the yoke. Therefore, in this embodiment, the lower surface of the permanent magnet 214 forms the gap-forming surface 216a, and the upper surface of the lower plate 212b that forms the yoke forms the gap-forming surface 216b, forming an air gap between them through which magnetic flux passes.

[0047] In this embodiment, the permanent magnet 214 is also magnetized so that the N pole and S pole are reversed in the thickness direction. Furthermore, the magnetic poles appearing on the gap forming surface 216a side of the permanent magnet 214 are magnetized so that they are alternately reversed at a predetermined pitch in the longitudinal direction.

[0048] Furthermore, the coil assembly 204 is made up of three drive coils 20, 22, and 24, and its structure is the same as that of the first embodiment described above. Furthermore, in this embodiment, a flexible substrate is attached to the underside of the coil assembly 204, and Hall sensors 206a and 206b, which are magnetic sensors, are attached to this flexible substrate. In the above-mentioned embodiment, the Hall sensors are arranged in a row in the direction in which the linear motor generates thrust. In contrast, in this embodiment, the Hall sensors 206a and 206b are not overlapped in the direction in which thrust is generated, but are attached at offset positions.

[0049] Furthermore, recesses 228a and 228b extending in the thrust direction of the polyphase linear motor 200 are provided at positions facing the Hall sensors 206a and 206b attached to the lower surface of the coil assembly 204. A portion of each of the Hall sensors 206a and 206b is received in the recesses 228a and 228b. Thus, in this embodiment, two recesses 228a and 228b are formed in the gap-forming surface 216b on the upper surface of the lower plate 212b. That is, two parallel grooves extending in the thrust direction (perpendicular to the plane of FIG. 6 ) are formed in the gap-forming surface 216b, which form the recesses 228a and 228b. Furthermore, in this embodiment, one Hall sensor is disposed so as to be received in each recess. However, as in the first embodiment, multiple Hall sensors may be provided so as to be received in one recess.

[0050] According to the polyphase linear motor 200 of the third embodiment of the present invention, the permanent magnets 214 are attached to only one side of the air gap, so that the polyphase linear motor 200 can be made thin.

[0051] Furthermore, according to the polyphase linear motor 200 of this embodiment, the recesses 228a, 228b for receiving the Hall sensors 206a, 206b, which are magnetic sensors, are provided in the plate 212b of the yoke, so that the recesses 228a, 228b can be easily formed.

[0052] Furthermore, according to the polyphase linear motor 200 of this embodiment, multiple recesses 228a, 228b are provided to receive the Hall sensors 206a, 206b, which are magnetic sensors, so that many magnetic sensors can be concentrated and arranged in the thrust generation direction. This allows the pitch of the magnetic poles to be finer, making it possible to make the motor more compact.

[0053] Next, a polyphase linear motor according to a fourth embodiment of the present invention will be described with reference to FIG. In the first embodiment described above, the polyphase linear motor is used as an actuator for driving the lens frame. In contrast, the polyphase linear motor according to the fourth embodiment of the present invention is used as a force feedback motor. Fig. 7 is a perspective view showing an example in which the polyphase linear motor according to the fourth embodiment of the present invention is used as a force feedback motor.

[0054] 7, a polyphase linear motor 300 according to the fourth embodiment of the present invention is provided in a glove-type wearable control device. The wearable control device 301 includes a glove 308 to be worn on a user's hand, a polyphase linear motor 300 attached to the glove 308, and a band member 310 extending from the polyphase linear motor 300. The wearable control device 301 can be used for VR (Virtual Reality), AR (Virtual Reality), or MR (Mixed Reality), or for a remote-controlled robot.

[0055] Glove 308 is a glove that can be worn on the user's hand and is configured to be deformable in accordance with the movement of the user's hand. The polyphase linear motor 300 is attached to the back of the glove 308, and is configured to generate a predetermined thrust in response to a control signal from a controller (not shown). Note that any of the linear motors of the first to third embodiments described above can be used as the polyphase linear motor 300 in this embodiment.

[0056] Band member 310 is a flexible, strip-shaped member extending from polyphase linear motor 300 toward the index finger portion of glove 308. The tip end of band member 310 is fixed to the tip of the index finger by fastener 310a, and is fixed to the base of the index finger by fastener 310b. The base end of band member 310 is connected to the movable portion of polyphase linear motor 300.

[0057] As a result, for example, when a user moves a finger in a virtual reality space, force feedback given to the user's finger from the virtual space can be provided by the thrust generated by the polyphase linear motor 300. The polyphase linear motor 300 of this embodiment generates a thrust proportional to the current flowing through the coils of the coil assembly, so the generated thrust can be easily controlled, making it suitable for wearable control devices that require subtle force feedback.

[0058] Although the embodiments of the present invention have been described above, various modifications can be made to the above-described embodiments. In particular, in the above-described embodiments, the polyphase linear motor is used for driving a lens frame and for a wearable control device, but the polyphase linear motor of the present invention can be used for generating thrust in any other equipment. Furthermore, in applications of optical systems, the polyphase linear motor of the present invention can be used for driving optical elements in cameras and interchangeable lenses, as well as as an actuator in an optical system for free-space optical communications mounted on artificial satellites.

[0059] In the above-described embodiment, the polyphase linear motor is configured as a three-phase linear motor having three coils, but the present invention can also be configured as a two-phase or four-or-more-phase linear motor. Also, in the above-described embodiment, the magnetic circuit constitutes the fixed part of the linear motor and the coil assembly constitutes the movable part of the linear motor, but the magnetic circuit can also constitute the movable part and the coil assembly can also constitute the fixed part.

[0060] Furthermore, in the above-described embodiment, an air layer is formed between the opposing gap forming surfaces, but the air gap between the pair of opposing gap forming surfaces may be filled with a fluid other than air. Also, in the above-described embodiment, a Hall sensor is used as the magnetic sensor, but any sensor that can detect magnetic flux may be used as the magnetic sensor. [Explanation of symbols]

[0061] 1. Polyphase linear motor 2 Magnetic circuit 4 Coil Assembly 6 Hall sensors (magnetic sensors) 6a Magnetic detection unit 8 Lens frame 10 Guide Pole 12 York 12a, 12b plates 14 Magnet 14a Permanent magnet 14b Permanent magnet 14c permanent magnet 14d permanent magnet 16a, 16b void forming surface 18 Air Gap 20 Drive coil 20a, 20b Straight section 22 Drive coil 22a, 22b Straight section 24 drive coil 24a, 24b Straight section 26 Flexible PCB 28 Recess 100 Polyphase linear motor 102 Magnetic Circuit 104 Coil Assembly 106a, 106b Hall sensors (magnetic sensors) 114a, 114b permanent magnet 116a Void forming surface 116b Void forming surface 200 Polyphase Linear Motor 202 Magnetic Circuit 204 Coil Assembly 206a, 206b Hall sensors (magnetic sensors) 212a, 212b plates 214 Permanent Magnets 216a Void forming surface 216b Void forming surface 228a, 228b recesses

Claims

1. A polyphase linear motor that generates a thrust in a predetermined direction, a magnetic circuit including a magnet and a yoke, which forms an air gap between a pair of opposing gap-forming surfaces through which magnetic flux passes; a coil assembly including a plurality of drive coils through which a drive current flows and disposed between the pair of gap-forming surfaces of the magnetic circuit; a magnetic sensor for detecting magnetic flux passing through the air gap; and the magnetic sensor is attached to at least one surface of the coil assembly that faces the pair of gap-forming surfaces; a recess extending in the thrust generating direction that receives at least a portion of the magnetic sensor is provided in at least one of the pair of gap forming surfaces;

2. 2. The polyphase linear motor according to claim 1, wherein the coil assembly is configured such that the straight portions of one drive coil constituting the coil assembly are arranged between the straight portions of the other drive coil.

3. 2. The polyphase linear motor according to claim 1, wherein at least one of the gap-forming surfaces of the magnetic circuit is configured by arranging a plurality of magnets extending in the thrust generating direction, and the recess is formed by a gap between the plurality of magnets arranged in a row.

4. 2. The polyphase linear motor according to claim 1, wherein a plurality of magnetic sensors are attached to the coil assembly, and the gap-forming surface of the magnetic circuit is provided with a plurality of recesses extending in the thrust generating direction so as to receive the plurality of magnetic sensors.

5. 5. The polyphase linear motor according to claim 1, wherein the magnetic sensor includes a magnetic detection portion, the magnetic detection portion being located outside the recess provided in the gap forming surface of the magnetic circuit.

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