Rotary and reciprocating actuator

Abstract

To provide a rotary reciprocating drive actuator capable of increasing a size and amplitude of a movable object such as a mirror and stabilizing a drive performance.SOLUTION: A rotary reciprocating drive actuator includes a movable portion including a rotating shaft, a fixing portion that supports the rotating shaft, and a driving portion that has a coil and a core arranged on the fixing portion and a magnet arranged on the rotating shaft, and rotates the rotating shaft with respect to the fixing portion using electromagnetic interaction. The fixing portion includes a first support and a second support arranged to face each other across the magnet in the axial direction, and a third support arranged to face the second support across a movable object, and the rotating shaft is rotatably supported at three points of the first support, the second support, and the third support.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a rotary reciprocating drive actuator. [Background technology]

[0002] Conventionally, rotary reciprocating actuators (hereinafter referred to as "rotary reciprocating actuators") have been known as actuators used in scanners such as multifunction machines and laser beam printers. Rotary reciprocating actuators include, for example, a rotating shaft that is a movable body, and a drive unit having a coil magnet. By passing electricity through the coil to rotate the rotating shaft back and forth, the reflection angle of the laser light by the mirror attached to the rotating shaft is changed to realize optical scanning of the target object. Such rotary reciprocating actuators include a moving coil type in which a coil is arranged on the rotating shaft, and a moving magnet type in which a magnet is arranged on the rotating shaft (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4727509 Summary of the Invention [Problem to be solved by the invention]

[0004] In a moving coil type rotary reciprocating actuator, the heat generated by the coil during operation (when current is applied) may adversely affect the surface condition of the mirror, the state of attachment of the mirror to the rotating shaft, and the shape of the mirror including warping. In addition, considering the heat generated by the coil during operation, it is difficult to increase the input current to the coil, which makes it difficult to increase the size and amplitude of the mirror, which is the movable object. Furthermore, it is necessary to extend the wiring to the coil arranged on the rotating shaft to the fixed body side, which makes assembly difficult.

[0005] On the other hand, in the case of a moving magnet type rotary reciprocating actuator, the above-mentioned problems related to coil heat generation and coil wiring can be solved. However, in the structure disclosed in Patent Document 1, the magnet is placed in the same area of ​​the rotating shaft as the mirror, and the yoke around which the coil is wound is placed so as to surround the magnet, so that the mirror, which is the movable object, and the yoke are likely to interfere with each other when the rotating shaft rotates. This makes it difficult to increase the size and amplitude of the mirror.

[0006] An object of the present invention is to provide a rotary reciprocating actuator that can accommodate larger and larger amplitude movable objects such as mirrors, while also stabilizing drive performance. [Means for solving the problem]

[0007] The rotary reciprocating actuator according to the present invention comprises: a movable part including a rotation axis on which a movable object is disposed; A fixed portion that supports the rotating shaft; a drive unit having a coil and a core disposed on the fixed portion and a magnet disposed on the rotating shaft, and rotating the rotating shaft about its axis relative to the fixed portion by utilizing electromagnetic interaction; A rotary reciprocating drive actuator comprising: The magnet is a ring-shaped magnet in which S poles and N poles are alternately arranged in the circumferential direction on the outer circumferential surface, the core has a magnetic pole portion that is excited by energization of the coil to generate a polarity, and is disposed such that the magnetic pole portion and the outer circumferential surface of the magnet face each other via an air gap when the rotating shaft is attached to the fixed portion; The number of magnetic poles of the magnet is equal to the number of magnetic pole portions, a rotation angle position holder that is disposed on the fixed portion so as to face the magnet via an air gap and holds the rotation angle position of the rotating shaft at a neutral position by a magnetic attraction force generated between the fixed portion and the magnet, the fixed portion includes a first support and a second support arranged to face each other with the magnet in between in the axial direction, and a third support arranged to face each other with the second support and the movable object in between, The rotation shaft is the first support, The above The second support and the third support are supported rotatably at three points. And, The first support is formed of a shield member made of an electrically conductive material and is disposed on one side in the axial direction of a core unit including the core and the coil. . Effect of the Invention

[0008] According to the present invention, it is possible to increase the size and amplitude of a movable object such as a mirror, and also to stabilize the driving performance. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a perspective view of the appearance of a rotary reciprocating actuator according to an embodiment. [Diagram 2] FIG. 2 is an exploded perspective view of the rotary reciprocating actuator. [Diagram 3] FIG. 3 is a cross-sectional view of a rotary reciprocating actuator. [Figure 4] FIG. 4 is a perspective view showing the configuration of the core unit. [Diagram 5] 5A and 5B are diagrams for explaining the operation of the magnetic circuit of the rotary reciprocating actuator. [Figure 6] FIG. 1 is a block diagram showing a configuration of a main part of an optical scanning device using a rotary reciprocating actuator. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0011] Fig. 1 is an external perspective view of a rotary reciprocating actuator 1 according to an embodiment. Fig. 2 is an exploded perspective view of the rotary reciprocating actuator 1. Fig. 3 is a cross-sectional view of the rotary reciprocating actuator 1.

[0012] The rotary reciprocating actuator 1 is used in, for example, a LIDAR (Laser Imaging Detection and Ranging) device. The rotary reciprocating actuator 1 can also be applied to optical scanning devices such as multifunction peripherals and laser beam printers.

[0013] The rotary reciprocating actuator 1 mainly comprises a movable part 10, a fixed part 20 which rotatably supports the movable part 10, and a drive part 30 which drives the movable part 10 to rotate reciprocally relative to the fixed part 20.

[0014] The movable part 10 has a rotation axis 11 and a mirror part 12 . The mirror section 12 is a movable object in the rotary reciprocating actuator 1, and is attached to the rotary shaft 11. The mirror section 12 is formed, for example, by attaching a mirror 121 to one surface of a mirror holder 122. The rotary shaft 11 is inserted into an insertion hole 122a of the mirror holder 122 and fixed thereto.

[0015] The fixed portion 20 has a base 21, a second bearing 22 and a third bearing 23. The base 21 has a left side wall portion 211 and a right side wall portion 212 arranged opposite to each other. The left side wall portion 211 and the right side wall portion 212 are provided upright on both axial ends of a flat bottom portion 213. In other words, the cross section of the base 21 is formed to be substantially U-shaped.

[0016] The left side wall portion 211 and the right side wall portion 212 are respectively formed with insertion holes 211a and 212a through which the rotating shaft 11 is inserted. In addition, the left side wall portion 211 and the right side wall portion 212 are respectively formed with cutout portions 211b and 212b that communicate the insertion holes 211a and 212a with the outer edges of the left side wall portion 211 and the right side wall portion 212.

[0017] The rotating shaft 11 to which the mirror unit 12 is attached is disposed in the insertion holes 211a, 212a from the outside through the notches 211b, 212b. If the notches 211b, 212b were not provided, a complicated assembly process would be required, for example, to insert the rotating shaft 11 through the insertion hole 211a of the left wall 211, the insertion hole 122a of the mirror holder 122, and the insertion hole 212a of the right wall 212 in that order in a state in which the mirror unit 12 is disposed between the left side wall 211 and the right side wall 212, and then to fix the rotating shaft 11 and the mirror holder 122. In contrast, in this embodiment, the notches 211b, 212b are formed in the left side wall 211 and the right side wall 212, so that the rotating shaft 11 to which the mirror unit 12 is attached in advance can be easily disposed in the insertion holes 211a, 212a through the notches 211b, 212b.

[0018] The second bearing 22 and the third bearing 23 are formed of rolling bearings (for example, ball bearings). Rolling bearings have a low friction coefficient and can smoothly rotate the rotating shaft 11, thereby improving the driving performance of the rotary reciprocating drive actuator 1.

[0019] The second bearing 22 and the third bearing 23 are respectively disposed in bearing attachment portions (reference numerals omitted) connected to the insertion holes 211a, 212a of the left side wall portion 211 and the right side wall portion 212. Specifically, the second bearing 22 and the third bearing 23 are inserted from both axial sides of the rotating shaft 11, and the rotating shaft 11 is disposed in the insertion holes 211a, 212a, and then attached to the bearing attachment portions. In this manner, the rotating shaft 11 is rotatably attached to the base 21 via the second bearing 22 and the third bearing 23.

[0020] The driving unit 30 includes a core unit 31 and a magnet 32 ​​.

[0021] The core unit 31 has first cores 41, 42, a second core (relay core) 43, coils 44, 45, a rotation angle position retaining portion 48, a first shield member 51, a second shield member 52, a first bearing 53, and the like. FIG. 4 is a perspective view showing the configuration of the core unit 31 (excluding the first shield member 51, the second shield member 52, and the first bearing 53). As shown in FIG. 4 and other figures, the core unit 31 is formed in a substantially rectangular parallelepiped shape in this embodiment. The core unit 31 is fixed to the base 21 and forms a part of the fixed portion 20.

[0022] The first cores 41, 42 and the second core 43 are integrated to form a single core body C, which forms a magnetic circuit when current is applied to the coils 44, 45. The first cores 41, 42 and the second core 43 are formed of laminated cores formed by laminating electromagnetic steel plates such as silicon steel plates.

[0023] The first cores 41 and 42 have magnetic pole portions 41a and 42a that generate polarities according to the direction of current flow when excited by current flow through the coils 44 and 45, respectively, and legs 41b and 42b that extend downward from the magnetic pole portions 41a and 42a. The portions of the magnetic pole portions 41a, 42a facing the magnet 32 ​​have a curved shape that follows the outer circumferential surface of the magnet 32. Coils 44, 45 are disposed on the leg portions 41b, 42b, respectively. The first cores 41, 42 are fixed to the second core 43 in an orientation in which the magnetic pole portions 41a, 42a face each other and the leg portions 41b, 42b are parallel to each other.

[0024] The second core 43 connects the legs 41b, 42b of the first cores 41, 42 and forms an intermediate portion of a magnetic circuit connecting the magnetic pole portions 41a, 42a. That is, the first cores 41, 42 are integrally connected via the second core 43. In this embodiment, the second core 43 is formed in a U-shape, and the ends of the legs 41b, 42b of the first cores 41, 42 are connected to the inside of the open ends of the legs 43a, 43b. That is, the first cores 41, 42 are surrounded by the second core 43 from three sides (left side, right side, and upper side) perpendicular to the rotation axis 11. Note that the bent portion of the second core 43 (the connecting portion between the legs 43a, 43b and the bridge portion 43c) may have a rounded R shape or a linearly bent shape.

[0025] When the rotary reciprocating drive actuator 1 is assembled, the rotary shaft 11 is inserted into the space surrounded by the magnetic pole portions 41a and 42a. The magnet 32 ​​attached to the rotary shaft 11 is located in this space and faces the magnetic pole portions 41a and 42a via an air gap.

[0026] In the core unit 31, a spacer 49 is disposed between the magnetic pole portions 41a, 42a of the first cores 41, 42 and the legs 43a, 43b of the second core 43. The spacer 49 is fixed to the first cores 41, 42 and the second core 43 by, for example, adhesion or welding. The spacer 49 is formed of a non-magnetic material such as brass or aluminum.

[0027] By interposing the spacer 49 between the magnetic pole parts 41a, 42a, which are the free ends, and the second core 43, the rigidity of the core unit 31 can be increased, and deformation or damage of the first cores 41, 42 due to magnetic forces or impacts generated between the magnet 32 ​​and the core unit 31 can be suppressed. In addition, by forming the spacer 49 from a non-magnetic material, the magnetic flux path in the core unit 31 can be regulated.

[0028] The coils 44, 45 are wound around cylindrical bobbins 46, 47. A coil unit consisting of the coils 44, 45 and the bobbins 46, 47 is extrapolated onto the legs 41b, 42b of the first cores 41, 42, so that the coils 44, 45 are arranged to wind around the legs 41b, 42b of the first cores 41, 42. The winding direction of the coils 44, 45 is set so that magnetic flux is suitably generated from one of the magnetic pole portions 41a, 42a of the first cores 41, 42 to the other when current is applied.

[0029] The rotation angle position holder 48 is incorporated into the core unit 31 so as to face the magnet 32 ​​across an air gap when the rotary reciprocating drive actuator 1 is assembled. The rotation angle position holder 48 is attached, for example, to the bridge portion 43c of the second core 43 (the portion above the first cores 41, 42) in a position where its magnetic pole faces the magnet 32.

[0030] The rotation angle position holder 48 is formed of, for example, a magnet, and generates a magnetic attraction force between itself and the magnet 32. That is, the rotation angle position holder 48, together with the first cores 41, 42, forms a magnetic spring between itself and the magnet 32. Due to this magnetic spring, in a normal state (when no current is applied) when the coils 44, 45 are not energized, the rotation angle position of the magnet 32, i.e., the rotation angle position of the rotating shaft 11, is held in a neutral position.

[0031] The neutral position is the reference position for the reciprocating rotational motion of the magnet 32, i.e., the center of oscillation. When the magnet 32 ​​is held in the neutral position, the magnetic pole switching portions 32c and 32d of the magnet 32 ​​directly face the magnetic pole portions 41a and 42a of the first cores 41 and 42. In addition, the mounting posture of the mirror portion 12 is adjusted based on the state in which the magnet 32 ​​is in the neutral position.

[0032] A first shield member 51 and a second shield member 52 made of an electrically conductive material are disposed on both axial sides of the core unit 31. The first shield member 51 and the second shield member 52 can suppress the entrance of noise from the outside to the core unit 31 and the emission of noise from the core unit 31 to the outside.

[0033] The first shield member 51 and the second shield member 52 are preferably made of an aluminum alloy. Aluminum alloys offer a high degree of design freedom and can easily impart the desired rigidity. Therefore, they are suitable for use when the first shield member 51 functions as a support for supporting the rotating shaft 11.

[0034] The rotating shaft 11 is rotatably attached to the first shield member 51 via a first bearing 53. The first bearing 53 is disposed in a bearing attachment portion 51a formed in the first shield member 51. The first bearing 53 has a cylindrical body portion 53b through which the rotating shaft 11 is inserted, and a flange portion 53a disposed at one end of the body portion 53b. The body portion 53b of the first bearing 53 is fitted into the bearing attachment portion 51a of the first shield member 51, and the flange portion 53a is engaged with the outer surface of the first shield member 51. After the rotating shaft 11 is inserted into the bearing attachment portion 51a of the first shield member 51, the first bearing 53 is inserted from the end of the rotating shaft 11 protruding from the first shield member 51, and is fitted into the bearing attachment portion 51a. In this way, the end of the rotating shaft 11 on the side where the magnet 32 ​​is disposed can be easily attached to the first shield member 51.

[0035] The first bearing 53 is, for example, a sliding bearing. Specifically, the first bearing 53 is preferably a resin molded product such as a fluororesin. By configuring the first bearing 53 as a sliding bearing, it is possible to make it function as a damping part and suppress the driving noise (resonance noise of the movable part 10). Furthermore, by making the first bearing 53 a resin molded product, it is possible to have a high degree of freedom in shape and to manufacture it at low cost. In particular, when it is made into a fluororesin molded product, it is possible to suppress expansion and contraction due to the environmental temperature, so it is suitable for the case where the rotary reciprocating drive actuator 1 is used in a high-temperature environment. Furthermore, since a fluororesin molded product has high processing accuracy and can realize appropriate sliding characteristics, it is possible to stably support the rotary shaft 11 without interfering with the rotary reciprocating motion of the rotary shaft 11, and is suitable as a bearing.

[0036] The second shield member 52 has an insertion hole 52a that is larger than the outer shape of the magnet 32. The rotating shaft 11 on which the magnet 32 ​​is attached is inserted into the core unit 31 through the insertion hole 52a of the second shield member 52.

[0037] A core body C consisting of the first cores 41, 42 and the second core 43 is sandwiched by the first shielding member 51 and the second shielding member 52, and fixed by a fastening material 61 to be integrated as a core unit 31. The core unit 31 is also fixed to the left side wall portion 211 of the base 21 by a fastening material 62 to be integrated with the base 21.

[0038] The magnet 32 ​​is a ring-shaped magnet in which S poles 32a and N poles 32b are alternately arranged in the circumferential direction. The magnet 32 ​​is attached to the circumferential surface of the rotating shaft 11 so as to be located in a space surrounded by the magnetic pole portions 41a, 42a of the core unit 31 when the rotary reciprocating drive actuator 1 is assembled. When the coils 44, 45 are energized, the first cores 41, 42 and the second core 43 are excited, and a polarity corresponding to the energizing direction is generated in the magnetic pole portions 41a, 42a, and a magnetic force (attraction force and repulsion force) is generated between the magnetic pole portions 41a, 42a and the magnet 32.

[0039] In this embodiment, the magnet 32 ​​is magnetized with different polarities with a plane along the axial direction of the rotating shaft 11 as the boundary. That is, the magnet 32 ​​is a two-pole magnet magnetized so as to be equally divided into an S pole 32a and an N pole 32b. The number of magnetic poles of the magnet 32 ​​(two in this embodiment) is equal to the number of magnetic pole portions 41a, 42a of the core unit 31. The magnet 32 ​​may be magnetized with two or more poles depending on the amplitude during movement. In this case, the magnetic pole portions of the core unit 31 are provided corresponding to the magnetic poles of the magnet 32.

[0040] The polarity of the magnet 32 ​​is switched at boundary portions 32c and 32d (hereinafter referred to as "magnetic pole switching portions") between the S pole 32a and the N pole 32b. When the magnet 32 ​​is held in the neutral position, the magnetic pole switching portions 32c and 32d directly face the magnetic pole portions 41a and 42a, respectively.

[0041] In the neutral position, the magnetic pole switching parts 32c, 32d of the magnet 32 ​​face the magnetic pole parts 41a, 42a, so that the driving part 30 can generate maximum torque and stably drive the movable part 10. Furthermore, by configuring the magnet 32 ​​as a two-pole magnet, it becomes easier to drive the movable object with high amplitude in cooperation with the core unit 31, and the driving performance can be improved. Note that, although the embodiment has been described with respect to a case where the magnet 32 ​​has a pair of magnetic pole switching parts 32c, 32d, the magnet 32 ​​may have two or more pairs of magnetic pole switching parts.

[0042] The rotating shaft 11 on which the mirror section 12 and the magnet 32 ​​are mounted is fixed to the base 21 via the second bearing 22 and the third bearing 23. The mirror section 12 is located in the space between the left side wall section 211 and the right side wall section 212 of the base 21, and the magnet 32 ​​is located outside (to the left) of the left side wall section 211 of the base 21.

[0043] The core unit 31 is inserted axially into the portion of the rotating shaft 11 exposed from the left side wall 211 (the portion where the magnet 32 ​​is arranged) and is fixed to the first shield member 51 via the first bearing 53. The magnet 32 ​​is located inside the core unit 31, that is, in the space sandwiched between the first shield member 51 and the left side wall 211 of the base 21.

[0044] When the rotary reciprocating drive actuator 1 is assembled, the portion of the rotating shaft 11 where the mirror section 12 is located is supported at two points by the left side wall section 211 and the right side wall section 212. This provides a higher support strength than when it is supported as a cantilever by only the left side wall section 211, and the straightness of the rotating shaft 11 can be ensured even if the mirror section 12 becomes larger and its weight increases.

[0045] Furthermore, the portion of the rotating shaft 11 where the magnet 32 ​​is arranged is supported at two points by the first shield member 51 and the left side wall 211, so that the linearity of the rotating shaft 11 can be ensured even if the magnetic attractive force between the magnet 32 ​​and the rotation angle position holder 48 becomes large. In other words, if the portion of the rotating shaft 11 where the magnet 32 ​​is arranged is supported in a cantilevered manner only by the left side wall 211, there is a risk that the rotating shaft 11 will bend toward the rotation angle position holder 48 and the linearity will decrease when the magnetic attractive force between the magnet 32 ​​and the rotation angle position holder 48 becomes large, but this problem does not occur.

[0046] Next, the operation of the rotary reciprocating actuator 1 will be described with reference to Figures 5A and 5B. Figures 5A and 5B are diagrams for explaining the operation of the magnetic circuit of the rotary reciprocating actuator 1.

[0047] The two magnetic pole portions 41a, 42a of the core body C are disposed to sandwich the magnet 32 ​​with an air gap G therebetween. When the coils 44, 45 are not energized, the magnet 32 ​​is held in a neutral position by the magnetic attraction force between the magnet 32 ​​and the rotation angle position holding portion 48, as shown in FIG.

[0048] In this neutral position, one of the S pole 32a and the N pole 32b of the magnet 32 ​​(the S pole 32a in FIG. 5A) is attracted to the rotation angle position holder 48. At this time, the magnetic pole switching portions 32c and 32d face the centers of the magnetic pole portions 41a and 42a of the core body C.

[0049] When the coils 44 and 45 are energized, the core body C is excited, and the magnetic pole parts 41a and 42a have a polarity according to the energizing direction. As shown in FIG. 5B, when the coils 44 and 45 are energized, a magnetic flux is generated inside the core body C, and the magnetic pole part 41a becomes an S pole and the magnetic pole part 42a becomes an N pole. As a result, the magnetic pole part 41a magnetized to an S pole attracts the N pole 32b of the magnet 32, and the magnetic pole part 42a magnetized to an N pole attracts the S pole 32a of the magnet 32, and a torque in the F direction is generated in the magnet 32 ​​around the axis of the rotating shaft 11, and the magnet 32 ​​rotates in the F direction. Accordingly, the rotating shaft 11 also rotates in the F direction, and the mirror part 12 fixed to the rotating shaft 11 also rotates in the F direction.

[0050] On the other hand, although not shown, when a current is applied to the coils 44, 45 in the opposite direction to that in Fig. 5B, a magnetic flux is generated inside the core body C, and the magnetic pole portion 41a becomes an N pole and the magnetic pole portion 42a becomes an S pole. As a result, the magnetic pole portion 41a magnetized to an N pole attracts the S pole 32a of the magnet 32, and the magnetic pole portion 42a magnetized to an S pole attracts the N pole 32b of the magnet 32, and a torque in the opposite direction to the F direction is generated in the magnet 32 ​​around the axis of the rotating shaft 11, and the magnet 32 ​​rotates in the -F direction. Accordingly, the rotating shaft 11 also rotates, and the mirror portion 12 fixed to the rotating shaft 11 also rotates. The rotary reciprocating actuator 1 rotates and reciprocates the mirror portion 12 by repeating the above operations.

[0051] In practice, the rotary reciprocating actuator 1 is driven by AC waves input to the coils 44, 45 from a power supply unit (equivalent to, for example, the drive signal supply unit 103 in FIG. 6). That is, the current flow direction of the coils 44, 45 is switched periodically. When the current flow direction is switched, the magnet 32 ​​is urged to return to the neutral position by the magnetic attraction force between the rotation angle position holder 48 and the magnet 32, i.e., the restoring force of the magnetic spring, so that a torque in the F direction and a torque in the opposite direction to the F direction (-F direction) act alternately on the movable part 10 around the axis. This causes the movable part 10 to be rotary and reciprocatingly driven.

[0052] The following is a brief explanation of the driving principle of the rotary reciprocating actuator 1. In the rotary reciprocating actuator 1 of this embodiment, the moment of inertia of the movable body (movable part 10) is J [kg m 2 ], the spring constant in the torsional direction of the magnetic spring (magnetic pole portions 41a, 42a, rotation angle position holder 48, and magnet 32) is K sp In this case, the movable body has a resonant frequency F r It vibrates (reciprocating rotation) at [Hz].

[0053]

number

[0054] Since the movable body constitutes a mass part in the vibration model of the spring-mass system, the resonance frequency F r When an AC wave having a frequency equal to the resonant frequency F of the movable body is input to the coils 44 and 45 from the power supply unit, the movable body is in a resonant state. r By inputting an AC wave having a frequency substantially equal to that of the movable body, the movable body can be vibrated efficiently.

[0055] Below are equations of motion and circuit equations showing the driving principle of the rotary reciprocating actuator 1. The rotary reciprocating actuator 1 is driven based on the equation of motion shown in equation (2) and the circuit equation shown in equation (3).

[0056]

number

[0057]

number

[0058] That is, the moment of inertia of the movable body in the rotary reciprocating actuator 1, J [kg m 2 ], rotation angle θ(t) [rad], torque constant K t [N·m / A], current i(t) [A], spring constant K sp [N m / rad], damping coefficient D [N m / (rad / s)], load torque T Loss [N m], etc. can be changed as appropriate within the range that satisfies formula (2). In addition, the voltage e(t) [V], resistance R [Ω], inductance L [H], and back electromotive force constant K e [V / (rad / s)] can be changed as appropriate within the range that satisfies formula (3).

[0059] In this way, the rotary reciprocating actuator 1 has a moment of inertia J of the movable body and a spring constant K of the magnetic spring. sp The resonant frequency F is determined by r When the coil is energized with an AC wave corresponding to the above, it is possible to obtain a large vibration output efficiently.

[0060] The rotary reciprocating actuator 1 may include an angle sensor 60 (see FIG. 6) that detects the rotation angle of the rotary shaft 11. The angle sensor 60 is fixed to the right side wall portion 212 of the base 21, for example.

[0061] The angle sensor 60 has, for example, an optical sensor and an encoder disk. The encoder disk is attached to the rotating shaft 11 and rotates together with the magnet 32 ​​and the mirror section 12. In other words, the rotational position of the encoder disk is the same as the rotational position of the rotating shaft 11. The optical sensor emits light to the encoder disk and detects the rotational position (angle) of the encoder disk based on the reflected light. This makes it possible to detect the rotational positions of the magnet 32 ​​and the mirror section 12. By providing the angle sensor 60, it becomes possible to detect the rotation angle of the movable part 10 including the magnet 32 ​​and the rotation shaft 11, and it is possible to control the rotation angle position and rotation speed of the movable body during operation, specifically, the mirror part 12 which is the movable object.

[0062] FIG. 6 is a block diagram showing the configuration of a main part of an optical scanning device using the rotary reciprocating actuator 1. As shown in FIG.

[0063] The optical scanning device A includes a laser emission unit 101, a laser control unit 102, a drive signal supply unit 103, and a position control signal calculation unit 104 in addition to the rotary reciprocating actuator 1.

[0064] The laser emission unit 101 has, for example, an LD (laser diode) serving as a light source, a lens system for converging the laser light output from the light source, etc. The laser control unit 102 controls the laser emission unit 101. The laser light emitted from the laser emission unit 101 is incident on a mirror 121 of the rotary reciprocating actuator 1.

[0065] The position control signal calculation unit 104 generates and outputs a drive signal for controlling the rotating shaft 11 (mirror 121) to be at the target angular position, with reference to the angular position of the rotating shaft 11 (mirror 121) acquired by the angle sensor 60 and the target angular position. For example, the position control signal calculation unit 104 generates a position control signal based on the acquired angular position of the rotating shaft 11 (mirror 121) and a signal indicating the target angular position converted using sawtooth waveform data or the like stored in a waveform memory (not shown), and outputs this position control signal to the drive signal supply unit 103.

[0066] Based on the position control signal, the drive signal supply unit 103 supplies a drive signal to the coils 44, 45 of the rotary reciprocating actuator 1 so that the angular position of the rotary shaft 11 (mirror 121) becomes a desired angular position. This enables the optical scanning device A to emit scanning light from the rotary reciprocating actuator 1 to a predetermined scanning area.

[0067] The rotary reciprocating actuator 1 according to the present embodiment has the following features. That is, the rotary reciprocating drive actuator 1 comprises a movable part 10 including a rotating shaft 11 on which a mirror part 12 (movable object) is arranged, a fixed part 20 supporting the rotating shaft 11, and a drive part 30 having coils 44, 45 and cores 41 to 43 arranged on the fixed part 20, as well as a magnet 32 ​​arranged on the rotating shaft 11, and rotating the rotating shaft 11 around its axis relative to the fixed part 20 by utilizing electromagnetic interaction. In addition, the magnet 32 ​​is a ring-shaped magnet in which S poles 32a and N poles 32b are arranged alternately in the circumferential direction on its outer peripheral surface, and the cores 41 to 43 have magnetic pole portions 41a, 42a that are excited by passing current through the coils 44, 45 to generate polarity, and are arranged so that the magnetic pole portions 41a, 42a and the outer peripheral surface of the magnet 32 ​​face each other across the air gap G when the rotating shaft 11 is attached to the fixed portion 20. The number of magnetic poles of the magnet 32 ​​is equal to the number of magnetic pole portions 41a, 42a, and the magnet 32 ​​is arranged on the fixed portion 20 so as to face the magnet 32 ​​across the air gap G, and the magnet 32 ​​further includes a rotational angle position holding portion 48 that holds the rotational angle position of the rotating shaft 11 in a neutral position by the magnetic attraction force generated between the magnet 32 ​​and the number of magnetic poles. As a result, each time the current flow direction to the coils 44, 45 is switched, the magnet 32 ​​is magnetically attracted by the rotation angle position holder 48 and is urged to return to the neutral position (operation reference position), thereby achieving high-amplitude rotary reciprocating drive with good energy efficiency and responsiveness. Also, compared to a moving coil type rotary reciprocating drive actuator, heat generated in the coil is less likely to be transmitted to the movable object, so if the movable object is a mirror, it is possible to avoid adverse effects of heat on the mirror (deterioration of joints, warping, etc.).

[0068] Furthermore, the fixed portion 20 has a first shield member 51 (first support) and a left side wall portion 211 (second support) of the base 21, which are arranged opposite each other in the axial direction with the magnet 32 ​​in between, and the rotating shaft 11 is rotatably attached to the first shield member 51 and the left side wall portion 211 via a first bearing 53 and a second bearing 22, one of the first bearing 53 and the second bearing 22 being a rolling bearing and the other being a sliding bearing. In this embodiment, the first bearing 53 is a sliding bearing, and the second bearing 22 is a rolling bearing. The portion of the rotating shaft 11 where the magnet 32 ​​is arranged is supported by the first shield member 51 and the left side wall portion 211, so that the linearity of the rotating shaft 11 can be ensured even if the magnetic attractive force between the magnet 32 ​​and the rotation angle position holder 48 becomes large. In other words, if the portion of the rotating shaft 11 where the magnet 32 ​​is arranged is supported in a cantilevered manner only by the left side wall portion 211, there is a risk that the rotating shaft 11 will bend toward the rotation angle position holder 48 and the linearity will decrease when the magnetic attractive force between the magnet 32 ​​and the rotation angle position holder 48 becomes large, but this problem does not occur. Therefore, by increasing the size of magnet 32, the driving torque can be increased to accommodate larger movable objects, and the amplitude of the movable object can be increased by increasing the diameter of magnet 32. In addition, the linearity of rotating shaft 11 can be ensured, so that the driving performance can be stabilized. Furthermore, since the first bearing 53 is a sliding bearing, it functions as a damping section and can suppress the driving noise (resonance noise of the movable section 10). Note that the first bearing 53 may be a rolling bearing and the second bearing 22 may be a sliding bearing, and the second bearing 22 may function as a damping section.

[0069] The first bearing 53 has a cylindrical body 53b through which the rotating shaft 11 is inserted and a flange 53a disposed at an end of the body 53b, with the body 53b being fitted into a bearing attachment portion 51a formed in the first shield member 51 (first support), and the flange 53a being engaged with the outer surface of the first shield member 51. This allows the end of the rotating shaft 11 on the side where the magnet 32 ​​is disposed to be easily attached to the first shield member 51.

[0070] Moreover, the first bearing 53 is a resin molded product, which allows a high degree of freedom in the shape of the first bearing 53 and allows it to be manufactured at low cost. In addition, the first bearing 53 is made of fluororesin. This makes it possible to suppress expansion and contraction of the first bearing 53 due to the environmental temperature, and also allows for high processing precision and appropriate sliding characteristics. Therefore, the rotary reciprocating drive actuator 1 can be used in high-temperature environments, and the rotary shaft 11 can be stably supported without interfering with the rotary reciprocating motion, improving reliability.

[0071] Furthermore, the magnet 32 ​​is a two-pole magnet, and the two magnetic pole switching portions 32c and 32d of the magnet 32 ​​face the magnetic pole portions 41a and 42a when the magnet 32 ​​is held in the neutral position. This causes the magnet 32, i.e., the movable body including the rotating shaft 11, to rotate back and forth in one direction and the other direction around the axis within the same angle range from the neutral position, maximizing the driving torque and stabilizing the direction of the driving torque.

[0072] In addition, a first shield member 51 and a second shield member 52 made of an electrically conductive material are arranged on both axial sides of the core unit 31 including the cores 41 to 43 and the coils 44, 45. This suppresses noise from entering the core unit 31 from the outside and noise from the core unit 31 to the outside, improving the reliability of the rotary reciprocating drive actuator 1. It is sufficient that either the first shielding member 51 or the second shielding member 52 is provided, and for example, the second shielding member 52 does not have to be provided.

[0073] The first support is formed of a first shield member 51. That is, the first shield member 51 functions as a shield that suppresses the ingress and egress of noise in the core unit 31, and also functions as a support that supports the rotating shaft 11. This allows the number of parts to be reduced, and space to be saved. Note that a support that supports the rotating shaft 11 may be provided separately from the first shield member 51.

[0074] Moreover, the first shield member 51 is formed of an aluminum alloy. This allows for a high degree of freedom in design and provides sufficient rigidity, allowing the first shield member 51 to function as a support for the movable portion 10.

[0075] The movable object is a mirror 121 that reflects the scanning light. This allows the rotary reciprocating actuator 1 to be used as a scanner that performs optical scanning.

[0076] The rotary reciprocating actuator 1 according to the embodiment also has the following features. That is, in the rotary reciprocating drive actuator 1, the fixed portion 20 has a first shield member 51 (first support) and a left side wall portion 211 (second support) of the base 21 arranged opposite each other in the axial direction with the magnet 32 ​​in between, and a right side wall portion 212 (third support) arranged opposite the left side wall portion 211 with the mirror portion 12 (movable object) in between, and the rotating shaft 11 is supported for free rotation at three points, the first shield member 51, the left side wall portion 211 and the right side wall portion 212. The portion of the rotating shaft 11 where the magnet 32 ​​is arranged is supported at two points by the first shield member 51 and the left side wall portion 211, so that the linearity of the rotating shaft 11 can be ensured even if the magnetic attraction force between the magnet 32 ​​and the rotation angle position holder 48 increases. Also, the portion of the rotating shaft 11 where the mirror portion 12 is arranged is supported at two points by the left side wall portion 211 and the right side wall portion 212, so that the linearity of the rotating shaft 11 can be ensured even if the mirror portion 12 becomes larger and its weight increases. Therefore, by increasing the size of magnet 32, the driving torque can be increased to accommodate larger movable objects, and the amplitude of the movable object can be increased by increasing the diameter of magnet 32. In addition, the linearity of rotating shaft 11 can be ensured, so that the driving performance can be stabilized.

[0077] Furthermore, the rotating shaft 11 is rotatably attached to the first shield member 51 (first support), the left side wall portion 211 (second support) and the right side wall portion 212 (third support) of the base 21 via the first bearing 53, the second bearing 22 and the third bearing 23, and the first bearing 53 is a sliding bearing, while the second bearing 22 and the third bearing 23 are rolling bearings. Since the second bearing 22 and the third bearing 23 are rolling bearings, the rotating shaft 11 on which a movable object is mounted can be stably held by the rolling bearings at two locations, and the reliability of the rotary reciprocating drive actuator 1 can be improved in terms of durability. Furthermore, the first bearing 53 is Slippery By using the bearings as rolling bearings, they function as damping sections and can suppress the driving noise (resonance noise of the movable section 10). From the viewpoint of the stability of the driving performance, the first bearing 53, the second bearing 22, and the third bearing 23 may all be rolling bearings.

[0078] The invention made by the inventor has been specifically described above based on an embodiment, but the present invention is not limited to the above embodiment and can be modified within the scope of the gist of the invention.

[0079] For example, in the embodiment, the movable object is the mirror unit 12, but the movable object is not limited to this. The movable object may be, for example, an imaging device such as a camera.

[0080] Further, for example, in the embodiment, the case where the rotary reciprocating actuator 1 is resonantly driven has been described, but the present invention can also be applied to the case where it is non-resonantly driven.

[0081] The configuration of the driving unit 30 is not limited to that described in the embodiment. For example, the core may have a magnetic pole part that is excited by energizing the coil to generate a polarity, and when the rotating shaft is attached to the fixed part, the magnetic pole part and the outer circumferential surface of the magnet may face each other via an air gap. Also, for example, the coil may have a configuration that generates a magnetic flux suitably from one side of the magnetic pole part of the core to the other side when energized.

[0082] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0083] 1 Rotation Reciprocating Actuator 10 Moving parts 11 Rotation axis 12 Mirror part (movable object) 20 Fixed part 21 Base 211 Left side wall (second support) 212 Right side wall (third support) 22 No. 2 bearing 23 Third bearing 30 Drive unit 31 Core Unit 32 Magnet 41, 42 1st core (core) 43 Second Core (Core) 44, 45 Coil 48 Rotation angle position holding unit 51 First shield member (first support) 52 Second shield member 53 No. 1 bearing A Optical Scanning Device

Claims

1. a movable part including a rotation axis on which a movable object is disposed; A fixed portion that supports the rotating shaft; a drive unit having a coil and a core disposed on the fixed portion and a magnet disposed on the rotating shaft, and rotating the rotating shaft about its axis relative to the fixed portion by utilizing electromagnetic interaction; A rotary reciprocating drive actuator comprising: The magnet is a ring-shaped magnet in which S poles and N poles are alternately arranged in the circumferential direction on the outer circumferential surface, the core has a magnetic pole portion that is excited by energization of the coil to generate a polarity, and is disposed such that the magnetic pole portion and the outer circumferential surface of the magnet face each other via an air gap when the rotating shaft is attached to the fixed portion; The number of magnetic poles of the magnet is equal to the number of magnetic pole portions, a rotation angle position holder that is disposed on the fixed portion so as to face the magnet via an air gap and holds the rotation angle position of the rotating shaft at a neutral position by a magnetic attraction force generated between the fixed portion and the magnet, the fixed portion includes a first support and a second support disposed opposite to each other with the magnet interposed therebetween in the axial direction, and a third support disposed opposite to the second support and the movable object interposed therebetween, the rotation shaft is rotatably supported at three locations, i.e., the first support, the second support, and the third support; The first support is configured by a shield member made of an electrically conductive material and is disposed on one side in the axial direction of a core unit including the core and the coil. Rotary reciprocating drive actuator.

2. The shield member is a flat plate-shaped member, and is joined to the core so that the plate thickness direction coincides with the axial direction, and is integrated as the core unit.

2. The rotary reciprocating drive actuator of claim 1.

3. the rotating shaft is rotatably attached to the first support, the second support, and the third support via a first bearing, a second bearing, and a third bearing, The first bearing is a sliding bearing, The second bearing and the third bearing are rolling bearings.

3. The rotary reciprocating actuator according to claim 1 or 2.

4. the rotating shaft is rotatably attached to the first support, the second support, and the third support via a first bearing, a second bearing, and a third bearing, The first bearing, the second bearing, and the third bearing are rolling bearings.

3. The rotary reciprocating actuator according to claim 1 or 2.

5. The magnet is a two-pole magnet, The two magnetic pole switching portions of the magnet directly face the magnetic pole portion when the magnet is held in the neutral position. A rotary reciprocating drive actuator according to any one of claims 1 to 4.

6. A shield member made of an electrically conductive material is arranged on the other side of the core unit in the axial direction. A rotary reciprocating drive actuator according to any one of claims 1 to 5.

7. The shield member is made of an aluminum alloy. A rotary reciprocating drive actuator according to any one of claims 1 to 6.

8. The movable object is a mirror that reflects the scanning light. A rotary reciprocating drive actuator according to any one of claims 1 to 7.

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