Drive device

Abstract

To realize an appropriate driving force by a simple configuration.SOLUTION: A drive device (101) comprises: a first base unit (110) connected with a driven unit; a coil (300) arranged on the first base unit; a first magnet (710) arranged so as to enclose a portion of the outer circumference of the coil; a second magnet (720) arranged so as to enclose a portion of the outer circumference of the coil that is not enclosed by the first magnet; a first middle yoke (810) provided on the first magnet; and a second middle yoke (820) provided on the second magnet. The first magnet is smaller than the second magnet, the first middle yoke is arranged so that the distance from the coil to the second middle yoke in a direction in which the driven unit is arranged is greater than the distance from the coil to the first middle yoke in a different direction as seen from the coil.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to the technical field of driving devices, such as MEMS scanners, that drive a driven object, such as a mirror. [Background technology]

[0002] For example, in various technical fields such as displays, printing devices, precision measurement, precision processing, information recording and reproduction, research on MEMS (Micro Electro Mechanical System) devices manufactured by semiconductor process technology is being actively conducted. As such MEMS devices, for example, in the display field where light incident from a light source is scanned over a predetermined screen area to realize an image, or in the scanning field where light is scanned over a predetermined screen area and the reflected light is received to read image information, a microstructured mirror drive device (optical scanner or MEMS scanner) has been attracting attention.

[0003] A typical mirror drive device uses a coil and a magnet to drive the mirror. In this case, a rotational force is applied to the mirror by the interaction between the magnetic field generated by passing a current through the coil and the magnetic field of the magnet, causing the mirror to rotate (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 11-231252 Summary of the Invention [Problem to be solved by the invention]

[0005] In the above-mentioned Patent Document 1, a magnetic field is generated by arranging two magnets on the sides of a coil. However, for example, when arranging the MEMS scanner and the magnet so that they overlap in a plane, the arrangement space of the magnet is limited in order to secure the driving area of ​​the MEMS scanner. On the other hand, it is desirable for the magnet to provide a well-balanced magnetic field to the MEMS scanner. For this reason, it is not easy to lay out the magnets appropriately, and as a result, there is a risk that the device configuration will become complicated and large.

[0006] The above-mentioned problems are given as examples of problems to be solved by the present invention. It is an object of the present invention to provide a drive device capable of realizing an appropriate drive force with a simple configuration. [Means for solving the problem]

[0007] In order to solve the above problem, the driving device comprises a first base part connected to the driven part, a coil arranged on the first base part, a first magnet arranged to surround a portion of the outer periphery of the coil, a second magnet arranged to surround a portion of the outer periphery of the coil that is not surrounded by the first magnet, a first middle yoke provided on the first magnet, and a second middle yoke provided on the second magnet, wherein the first magnet is smaller than the second magnet, and the first middle yoke is arranged so that the distance from the coil to the first middle yoke in a direction different from the direction in which the driven part is arranged is closer than the distance from the coil to the second middle yoke in the direction in which the driven part is arranged. [Brief description of the drawings]

[0008] [Figure 1] 1 is a plan view showing a configuration of a MEMS scanner according to an embodiment when viewed from the front side. [Diagram 2] 2 is a plan view showing the configuration of the MEMS scanner according to the embodiment when viewed from the back side. FIG. [Diagram 3] 1 is a cross-sectional view showing a layered structure of a MEMS scanner according to an embodiment. [Figure 4]4A to 4C are side views conceptually illustrating the manner of operation of the MEMS scanner according to the embodiment. [Diagram 5] 4 is a plan view showing the arrangement of magnets and a middle yoke for a MEMS scanner according to an embodiment. FIG. [Figure 6] 4 is a cross-sectional view showing a configuration of a member that applies a magnetic field to the MEMS scanner according to the embodiment. FIG. [Figure 7] 1 is a conceptual diagram showing the positional relationship of members that apply a magnetic field to a coil. [Figure 8] 4 is a plan view showing the arrangement of magnets and a middle yoke for a MEMS scanner according to a first comparative example. FIG. [Figure 9] 13 is a plan view showing the arrangement of magnets and a middle yoke for a MEMS scanner according to a second comparative example. FIG. [Figure 10] FIG. 11 is a conceptual diagram for explaining whether or not there is interference with the middle yoke when the V axis is driven. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, the embodiments of the drive device will be described in order.

[0010] <1> The driving device of this embodiment comprises a first base portion, a second base portion, an elastic portion connecting the first base portion and the second base portion, a coil arranged on the first base portion, a first magnet arranged on one side of the coil, a second magnet arranged on the opposite side of the first magnet from the coil, a first middle yoke provided on the surface of the first magnet facing the coil, and a second middle yoke provided on the surface of the second magnet facing the coil, wherein the first magnet is smaller than the second magnet, and the first middle yoke is arranged at a position closer to the coil than the second middle yoke.

[0011] According to the driving device of this embodiment, the first base portion and the second base portion are directly or indirectly linked (in other words, connected) by an elastic portion having elasticity (for example, a spring portion described later). Here, since the elastic portion has elasticity, it is preferable that the rigidity of the elastic portion is lower than the rigidity of both or one of the first base portion and the second base portion. In other words, it is preferable that the elastic portion is relatively more easily deformed than both or one of the first base portion and the second base portion. In further other words, it is preferable that the elastic portion is relatively easily deformed, while both or one of the first base portion and the second base portion are relatively less easily deformed.

[0012] A coil is disposed on the first base. For example, the first base is configured as a frame having an opening, and the coil is wound around the opening. A first magnet is disposed on one side of the coil, and a second magnet is disposed on the opposite side of the coil. That is, the two magnets are disposed so as to sandwich the coil. Therefore, a magnetic field caused by the two magnets is generated around the coil. Therefore, a Lorentz force can be generated on the coil by passing a predetermined control current through the coil.

[0013] The surface of the first magnet facing the coil and the surface of the second magnet facing the coil are typically of different polarities. Specifically, when the surface of the first magnet facing the coil is an N pole, the surface of the second magnet facing the coil is an S pole. Alternatively, when the surface of the first magnet facing the coil is an S pole, the surface of the second magnet facing the coil is an N pole. In this case, when a control current is passed through the coil, Lorentz forces with different directions are generated on the first magnet side and the second magnet side of the coil. Such Lorentz forces act as a driving force for rotating the first base part on which the coil is arranged. In addition, such driving force may be transmittable to the second base part via an elastic part connected to the first base part.

[0014] A first middle yoke is provided on the surface of the first magnet facing the coil. A second middle yoke is provided on the surface of the second magnet facing the coil. The first middle yoke and the second middle yoke are preferably made of a soft magnetic material with high relative permeability, such as pure iron, permalloy, silicon iron, or sendust. Such first middle yoke and second middle yoke can suitably focus the magnetic flux generated by the first magnet and the second magnet to the coil. Therefore, the driving force applied to the coil can be improved.

[0015] Here, in this embodiment, in particular, the first magnet is configured to be smaller than the second magnet. More specifically, for example, the surface area of ​​the first magnet on the coil side is configured to be smaller than the surface area of ​​the second magnet on the coil side. In addition to this, the first middle yoke is disposed closer to the coil than the second middle yoke. That is, the middle yoke provided on the smaller magnet is disposed closer to the coil than the middle yoke provided on the larger magnet.

[0016] According to the above-mentioned configuration, the magnetic field applied to the coil by the first magnet is smaller than that applied to the coil by the second magnet, because the first magnet is smaller than the second magnet. However, the first middle yoke provided on the first magnet is closer to the coil than the second middle yoke provided on the second magnet, so the first middle yoke has a higher magnetic flux concentrating effect on the coil than the second middle yoke. Therefore, the difference in the magnitude of the magnetic field caused by the size of the first magnet and the second magnet is offset by the difference in the magnetic flux concentrating effect caused by the difference in the distance between the first middle yoke and the second middle yoke, and as a result, a balanced magnetic field can be applied to the coil. This makes it possible to bring the Lorentz force generated in the coil closer to a couple force, and more suitable driving of the first base part can be realized.

[0017] Although a balanced magnetic field can be achieved by making the first and second magnets the same size, it may be difficult to make the two magnets the same size depending on the available space for arranging the magnets. In particular, in the embodiment in which the second base is connected to the first base on which the coil is provided, it is highly likely that each member will be required to be arranged asymmetrically with respect to the coil.

[0018] However, in this embodiment, as described above, even if the first magnet and the second magnet are different in size, it is possible to apply an appropriate magnetic field to the coil by adjusting the distance between the first middle yoke and the second middle yoke and the coil, thereby providing an appropriate driving force to the coil and achieving suitable driving.

[0019] <2> In another aspect of the drive device of the present embodiment, the second magnet is disposed on the second base portion side as viewed from the coil.

[0020] According to this embodiment, the second magnet, which is the larger magnet, is disposed on the second base side as viewed from the coil. In other words, the smaller magnet is disposed on the opposite side of the coil from the second base.

[0021] Here, a space for disposing the second base part is necessarily generated on the side of the second base part on which the second magnet is provided. Therefore, for example, by utilizing the space overlapping with the second base part in a plan view, it is easy to dispose a relatively large second magnet.

[0022] On the other hand, considering that the second base part is also driven by the driving force transmitted from the first driving part, it is necessary to secure an area for the second base part to drive. However, a member such as the middle yoke, which is desirably placed in a position close to the coil (in other words, in a position close to the second base part), may interfere with the driving of the second base part.

[0023] However, the second middle yoke provided on the second magnet is spaced farther from the coil than the first middle yoke, and therefore the second middle yoke can be easily disposed at a distance that does not interfere with the driving area of ​​the second base, for example.

[0024] <3> In the aspect in which the second magnet is arranged on the second base portion side as described above, the first magnet has a first portion arranged along a first side of the first base portion on a side that does not face the second base portion, and a second portion arranged along a second side adjacent to the first side, and the second magnet has a third portion arranged along a third side of the first base portion on a side that faces the second base portion, and a fourth portion arranged along a fourth side adjacent to the third side, and the first portion is smaller than the third portion, and the portion of the first middle yoke provided on the surface of the first portion may be arranged closer to the coil than the portion of the second middle yoke provided on the surface of the third portion.

[0025] In this case, the first portion of the first magnet is smaller than the third portion of the second magnet. Specifically, the first portion provided along the first side of the first base portion (i.e., the side not facing the second base portion) is smaller than the third portion provided along the third side of the first base portion (i.e., the side facing the second base portion). Therefore, the second magnet arranged on the second base portion side is larger than the first magnet. The sizes of the other second and fourth portions are typically approximately the same, but are not particularly limited.

[0026] On the other hand, the portion of the first middle yoke provided on the surface of the first portion is disposed closer to the coil than the portion of the second middle yoke provided on the surface of the third portion. Therefore, the difference in the magnitude of the magnetic field caused by the size of the first portion and the third portion is offset by the difference in the magnetic flux focusing effect caused by the difference in the distance of the middle yoke provided in each of the first portion and the third portion. Therefore, a balanced magnetic field can be applied to the coil.

[0027] <4> In another aspect of the drive device of the present embodiment, the first middle yoke and the second middle yoke are arranged so as not to overlap the first base portion and the second base portion in a plan view.

[0028] According to this aspect, it is possible to prevent the first middle yoke and the second middle yoke from interfering with the driving of the first base portion and the second base portion. In other words, the first middle yoke and the second middle yoke are arranged so as not to overlap with the first base portion and the second base portion in plan view, but can be arranged close to the first base portion and the second base portion in terms of height. Therefore, the magnetic flux concentrating function of the first middle yoke and the second middle yoke can be effectively exhibited.

[0029] <5> In another aspect of the drive device of the present embodiment, the drive device further includes a yoke inserted into the opening of the first base portion.

[0030] According to this aspect, the yoke inserted into the opening of the first base portion can focus the magnetic flux on the coil. This can increase the Lorentz force generated by passing a control current through the coil. In other words, the driving force applied by the coil can be increased. The yoke, like the first middle yoke and the second middle yoke, is preferably made of a soft magnetic material with high relative permeability, such as pure iron, permalloy, silicon iron, or sendust.

[0031] In order to enhance the effect of concentrating the magnetic flux by the yoke, it is preferable that the distance between the yoke and the coil is small. Therefore, it is preferable that the yoke is made large as long as it does not interfere with the driving of the first base part on which the coil is arranged. In addition, it is preferable that the cross section of the yoke has a shape close to the shape of the opening part of the first base part.

[0032] Furthermore, the yoke is inserted from the lower side to the upper side of the first base part, for example, but in order to enhance the effect of concentrating the magnetic flux by the yoke, it is preferable that the yoke is configured to extend upward to some extent. Therefore, it is preferable that the yoke is configured to be long enough so as not to interfere with the driving of the first base part on which the coil is arranged.

[0033] <6> In another aspect of the drive device of the present embodiment, the drive device further includes a driven portion supported by the second base portion.

[0034] According to this aspect, the second base portion supports a driven part configured as, for example, a mirror. In this case, the second base portion supports the driven part so that the driven part is drivable (for example, rotatable or movable). More specifically, for example, the second base portion and the driven part are connected by an elastic part having elasticity, so that the second base portion may support the first driven part in a drivable manner.

[0035] According to a driving device having such a configuration, the driven part can be suitably driven (e.g., rotated or moved). That is, according to a driving device having such a configuration, the driven part can be suitably driven (e.g., rotated or moved). Specifically, for example, when the first base part moves, the second base part connected to the first base part via the elastic part also moves in conjunction with the movement of the first base part. When the second base part moves, the driven part supported by the second base part also moves in conjunction with the movement of the second base part. As a result, the driven part can be suitably driven. EXAMPLES

[0036] Hereinafter, an embodiment of the driving device of the present invention will be described with reference to the drawings. Note that the following describes an example in which the driving device is applied to a MEMS scanner. However, it goes without saying that the driving device of the present invention may be applied to any driving device other than a MEMS scanner.

[0037] (1) Basic configuration First, the configuration of a MEMS scanner 101 according to this embodiment will be described with reference to Fig. 1 to Fig. 3. Fig. 1 is a plan view showing the configuration of the MEMS scanner 101 according to the embodiment when viewed from the front side, and Fig. 2 is a plan view showing the configuration of the MEMS scanner 101 according to the embodiment when viewed from the back side. Also, Fig. 3 is a cross-sectional view showing the layered structure of the MEMS scanner 101 according to the embodiment.

[0038] As shown in Figures 1 and 2, the MEMS scanner 101 of this embodiment is configured to include a first base 110, a second base 120, V torsion bars 150 and 160, a spring portion 210, a wiring spring portion 220, a coil 300, a mirror 400, and an H torsion bar 450.

[0039] The first base 110 has a frame shape with a gap (opening) therein. That is, the first base 110 has two sides extending in the Y-axis direction in the figure and two sides extending in the X-axis direction in the figure (i.e., a direction perpendicular to the Y-axis direction), and has a frame shape with a gap surrounded by the two sides extending in the Y-axis direction and the two sides extending in the X-axis direction. In the example shown in FIG. 1 and FIG. 2, the first base 110 has a square shape, but is not limited thereto, and may have, for example, another shape (for example, a rectangular shape such as a rectangle or a circular shape). In addition, the first base is not limited to a frame shape.

[0040] The coil 300 is disposed on the first base. The coil 300 is, for example, a plurality of windings made of a material having a relatively high electrical conductivity (for example, gold or copper). In this embodiment, the coil 300 has a square shape that conforms to the first base 110. However, the coil 300 may have any shape (for example, a rectangle, a diamond, a parallelogram, a circle, an ellipse, or any other loop shape).

[0041] A control current is supplied to the coil 300 from a power source via a power source terminal (not shown) or the like. The power source may be a power source provided in the MEMS scanner 101 itself, or may be a power source provided outside the MEMS scanner 101. A magnet (not shown) is disposed around the coil 300, and a rotational force is applied by the interaction between a magnetic field generated by passing a control current through the coil 300 and the magnetic field of the magnet, and as a result, the first base 110 on which the coil 300 is provided is rotated in a direction according to the directions of the magnetic field and the control current.

[0042] The second base portion 120 has a frame shape with a gap therein, similar to the first base portion 110. A mirror 400 is disposed in the gap of the second base 120. The mirror 400 is disposed so as to be suspended or supported by an H torsion bar 450.

[0043] The H torsion bar 450 is an elastic member such as a spring made of, for example, silicon, copper alloy, iron alloy, other metals, resin, etc. The H torsion bar 450 is disposed so as to extend in the Y-axis direction in FIG. 1. In other words, the H torsion bar 450 has a shape having a long side extending in the Y-axis direction and a short side extending in the X-axis direction. One end of the H torsion bar 450 is connected to the second base 110. The other end of the H torsion bar 450 is connected to the mirror 400. Therefore, the mirror 400 can rotate around an axis along the Y-axis direction as a rotation axis due to the elasticity of the H torsion bar 450. The mirror 400 is a specific example of a "driven part."

[0044] The first base 110 and the second base 120 are connected to each other by a spring portion 210. The spring portion 210 is a specific example of an "elastic portion" and has a function of transmitting a driving force obtained from the coil 300 in the first base 110 to the second base 120. In addition, a wiring spring portion 220 is provided between the first base 110 and the second base 120. The wiring spring portion 220 is provided to realize an electrical connection between the first base 110 and the second base 120. Specifically, a connection wiring 225 for connecting the coil 300 of the first base 110 and the wiring 500 of the second base 120 is arranged in the wiring spring portion 220.

[0045] The first base 110 and the second base 120 are fixed to a substrate or a support member (not shown) via V torsion bars 150 and 160 (in other words, they are fixed inside the system called the MEMS scanner 101). Alternatively, the first base 110 may be suspended by a suspension (not shown).

[0046] 3, the MEMS scanner 101 according to this embodiment is configured with a laminated structure including a support layer 10, an active layer 20, a BOX layer 30, and a metal layer 40. However, the laminated structure may include other layers.

[0047] Each of the support layer 10 and the active layer 20 is made of, for example, silicon or the like. The BOX layer 30 is made of, for example, an oxide film such as SiO2 or the like, and is disposed between the support layer 10 and the active layer 20. The BOX layer 30 insulates the support layer 10 from the active layer 20. The metal layer 40 is made of, for example, a metal with high conductivity, and is disposed on the active layer 20. The metal layer 40 constitutes the coil 300 in the first base 110, the wiring 500 in the second base 120, the connection wiring 225 in the wiring spring portion 220, and the like.

[0048] The support layer 10 is formed so as to extend from the first base 110 to the spring portion 210 and the second base 120 (see FIG. 2 for details). On the other hand, the active layer 20, the BOX layer 30, and the metal layer 40 are formed on the first base 110 and the second base 120, respectively, but are not formed on the spring portion 210. In other words, the spring portion 210 is formed only by the support layer 20. Also, the spring portion 210 is integrally formed with the support layer 10 of the first base 110 and the support layer of the second base 120. Note that the active layer 20 is not formed on the spring portion 210, but the active layer 20 is formed on the wiring spring portion 220 (see FIG. 1). Therefore, the electrical connection between the first base 110 and the second base 120 can be realized.

[0049] (2) Operation of the MEMS scanner Next, the operation of the MEMS scanner 101 according to this embodiment will be described with reference to Fig. 4. Fig. 4 is a side view conceptually showing the operation of the MEMS scanner according to this embodiment. For ease of explanation, in Fig. 4 and subsequent figures, detailed members constituting the MEMS scanner 101 shown in Figs. 1 to 3 and the like are omitted as appropriate and shown simply.

[0050] 4(a), in the MEMS scanner 101 according to this embodiment, an external magnetic field is applied to the coil 300 from the upper right to the lower right in the figure. The external magnetic field is applied by a magnet, which will be described later. However, the direction of the magnetic field here is just an example, and the magnetic field may be applied in another direction.

[0051] 4(a) and (b), when the MEMS scanner 101 according to this embodiment is in operation, a control current is supplied to the coil 300. Then, a Lorentz force is generated due to electromagnetic interaction between a magnetic field generated by supplying the control current to the coil 300 and an external magnetic field. Specifically, Lorentz forces in opposite directions are generated at one end and the other end of the coil 300.

[0052] When the Lorentz force is generated, the first base on which the coil 300 is provided is driven. The driving force of the first base 110 is transmitted to the second base 120 via the spring portion 210. Therefore, the second base 120 is also driven in conjunction with the driving of the first base 110. The driving force of the second base is also transmitted to the mirror 400 via the H torsion bar. Therefore, the mirror 400 is also driven in conjunction with the driving of the second base 120. In this way, when the Lorentz force is generated in the coil 300, each of the first base 110, the second base 120, and the mirror 400 is driven.

[0053] Here, when the frequency of the control current supplied to the coil 300 is DC to several hundreds of Hz, the MEMS scanner 101 rotates around the X-axis. Specifically, the MEMS scanner 101 rotates around the V torsion bars 150 and 160 as the rotation axis. This causes the mirror 400 to also rotate around the X-axis as the rotation axis, thereby performing so-called vertical scanning.

[0054] 4(c), when the control current supplied to the coil 300 is set to a frequency corresponding to the natural resonance mode, the MEMS scanner 101 rotates around the Y-axis. Specifically, the first base 110 and the second base 120 of the MEMS scanner 101 each rotate around different axes along the Y-axis. This causes the mirror 400 to also rotate around the Y-axis, thereby performing so-called horizontal scanning.

[0055] During the above-described driving, it is preferable that the Lorentz force generated in the coil 300 is a couple force. In particular, in driving with the Y-axis as the rotation axis, the center of rotation of the coil 300 is determined only by the dimensions, hardness, and weight of each structural part, and is easily affected when an external force is applied. If the Lorentz force generated in the coil 300 deviates from the couple force, other motions (for example, translational motion of the coil 300) will be mixed into the resonant motion, hindering smooth resonant motion.

[0056] In order to make the Lorentz force generated in coil 300 closer to a couple force, it is preferable that the magnetic field applied to coil 300 is horizontal and has approximately the same strength on the left and right sides of coil 300 (i.e., the two areas where the Lorentz force is generated).

[0057] (3) Magnet and yoke arrangement Next, the configuration of the magnets and yokes that generate a magnetic field for the MEMS scanner 101 according to this embodiment will be described with reference to Fig. 5 to Fig. 7. Fig. 5 is a plan view showing the arrangement of the magnets and middle yoke for the MEMS scanner according to this embodiment. Fig. 6 is a cross-sectional view showing the configuration of members that apply a magnetic field to the MEMS scanner according to this embodiment. Fig. 7 is a conceptual diagram showing the positional relationship of members that apply a magnetic field to a coil.

[0058] 5, in the MEMS scanner 101 according to this embodiment, a first magnet 710 is disposed on one side (upper right in the figure) of the coil 300. The first magnet 710 is V-shaped so as to fit along two sides of the first base 110 on which the coil 300 is provided. A first middle yoke 810 is provided on a surface of the first magnet 710 facing the coil 300.

[0059] Also, a second magnet 720 is disposed on the other side of the coil 300 (lower left in the figure). The second magnet 720 is formed in a dogleg shape so as to be aligned with two sides (specifically, two sides different from the two sides along which the first magnet 710 is aligned) of the first base 110 on which the coil 300 is disposed. A second middle yoke 820 is disposed on the surface of the second magnet 720 facing the coil 300. The second magnet 720 is disposed in a relatively wide space from below the second base 120 to below the V torsion bar 160. That is, the second magnet 720 is configured as a magnet larger than the first magnet 710. Furthermore, the second middle yoke 820 does not cover the entire surface of the second magnet 720, but is disposed at a position that does not overlap with the second base in plan view.

[0060] 6, the coil 300 is inserted through a yoke 600 extending upward from a lower yoke 650. A third magnet 730 and a fourth magnet 740 are disposed on the upper side of the MEMS scanner 101. A third middle yoke 830 is provided on a surface of the third magnet 730 facing the coil 300. A fourth middle yoke 840 is provided on a surface of the fourth magnet 740 facing the coil 300.

[0061] Here, each of the yokes 600, the lower yoke 650, the first middle yoke 810, the second middle yoke 820, the third middle yoke 830, and the fourth middle yoke 840 described above is configured to include a soft magnetic material having a high relative magnetic permeability, such as pure iron, permalloy, silicon iron, and sendust. With each of these yokes, the magnetic flux generated by the first magnet 710, the second magnet 720, the third magnet 730, and the fourth magnet 740 can be suitably concentrated and made parallel to the coil 300. As a result, the driving force applied to the coil 300 can be improved.

[0062] In FIG. 7, the MEMS scanner 101 according to this embodiment is configured so that the distance L1 between the portion of the first middle yoke 810 along the right side of the coil 300 in the figure and the yoke 600 is smaller than the distance L2 between the portion of the second middle yoke 820 along the left side of the coil 300 in the figure and the yoke 600. Therefore, the magnetic flux concentrating function of the first middle yoke 810 for the coil 300 is higher than that of the second middle yoke 820. Therefore, the difference in magnetic field strength due to the difference in size between the first magnet 710 and the second magnet 720 is offset by the difference in magnetic flux concentrating function due to the difference in the distance between the first middle yoke 810 and the second middle yoke 820. In other words, the distances L1 and L2 between the first middle yoke 810 and the second middle yoke 820 and the yoke 600 may be adjusted to values ​​that can offset the difference in magnetic field strength between the first magnet 710 and the second magnet 720.

[0063] As a result, a well-balanced magnetic field is applied to the coil 300. Therefore, the Lorentz force generated in the coil 300 during driving can be made to approach a couple force, and more suitable driving can be realized.

[0064] (4) Comparison with comparative examples Next, the advantages of the MEMS scanner 101 according to this embodiment will be specifically described by comparing it with a MEMS scanner 101b according to a first comparative example and a MEMS scanner 101c according to a second comparative example, which will be described with reference to Figs. 8 to 10. Fig. 8 is a plan view showing the arrangement of the magnets and middle yoke for the MEMS scanner according to the first comparative example. Fig. 9 is a plan view showing the arrangement of the magnets and middle yoke for the MEMS scanner according to the second comparative example. Fig. 10 is a conceptual diagram for explaining the presence or absence of interference with the middle yoke during V-axis driving.

[0065] 8, the first magnet 710b and the first middle yoke 810b according to the first comparative example are provided similarly to the first magnet 710 and the first middle yoke 810 (see FIG. 5) of the MEMS scanner 101 according to this embodiment. On the other hand, the second magnet 720b and the second middle yoke 820b according to the first comparative example are provided smaller than the second magnet 720 and the second middle yoke 820 (see FIG. 5) of the MEMS scanner 101 according to this embodiment. Specifically, the first magnet 710b and the second magnet 720b according to the first comparative example are approximately the same size as each other and are configured to apply the same magnetic field to the coil 300.

[0066] However, in the first comparative example, the size of the second magnet 720 is smaller than that of this embodiment, and therefore the driving efficiency is deteriorated. Specifically, since the empty space on the left side of the second base 120 cannot be effectively utilized, the magnetic field applied to the coil 300 is weakened accordingly, and the Lorentz generated in the coil 300 is also smaller.

[0067] In FIG. 9, the first magnet 710c and the first middle yoke 810c according to the second comparative example are provided larger than the first magnet 710 and the first middle yoke 810 (see FIG. 5) of the MEMS scanner 101 according to this embodiment. On the other hand, the second magnet 720b according to the first comparative example is provided similarly to the second magnet 720 of the MEMS scanner 101 according to this embodiment. However, the second middle yoke 820 according to the second embodiment is not provided partially like the second middle yoke 820 according to this embodiment, but is provided so as to cover the entire surface of the second magnet 720 on the coil 300 side. Therefore, in the second comparative example, as in the above-mentioned first comparative example, the first magnet 710c and the second magnet 720c are of approximately the same size and are configured to apply the same magnetic field to the coil 300.

[0068] However, in the second comparative example, the first magnet 710 is larger than in this embodiment and protrudes outside the chip, which increases the device dimensions including the magnetic circuit, resulting in an increase in the size of the device.

[0069] 10(a), in the first and second comparative examples, the second middle yoke 820 is further disposed at a position overlapping the second base 120 in a plan view. Therefore, for example, when the MEMS scanner 101b or 101c is driven with the V-axis (X-axis) as the rotation axis, the second base 120 and the second middle yoke 820 interfere with each other. As a method for avoiding such interference, for example, a method of disposing the second middle yoke 820 at a position away from the second base 120 is conceivable, but the magnetic flux focusing function of the second middle yoke 820 is accordingly reduced.

[0070] 10(b), according to this embodiment, the second middle yoke 820 is not disposed at a position that overlaps with the second base 120 in a plan view. Therefore, even when the MEMS scanner 101 is driven about the V-axis (X-axis) as the rotation axis, for example, interference between the second base 120 and the second middle yoke 820 can be avoided.

[0071] As described above, according to the MEMS scanner 101 of this embodiment, the magnets and yokes are arranged in a manner that makes it possible to avoid interference with the MEMS scanner 101 during operation, and a well-balanced magnetic field is applied to the coil 300. Therefore, the MEMS scanner 101 can be preferably operated.

[0072] The MEMS scanner 101 according to each of the above-mentioned embodiments can be applied to various electronic devices, such as a head-up display, a head-mounted display, a laser scanner, a laser printer, a scanning drive device, etc. Therefore, these electronic devices are also included in the scope of the present invention.

[0073] Furthermore, the present invention can be modified as appropriate within the scope of the claims and the entire specification without going against the gist or concept of the invention, and a drive device involving such modifications is also included in the technical concept of the present invention. [Explanation of symbols]

[0074] 10 Support layer 20 Active layer 30 BOX layers 40 metal layer 101 MEMS Scanner 110 First Base 120 2nd Base 150,160 V torsion bar 210 Spring part 220 Wiring spring part 225 Connection Wiring 300 coils 400 Mirror 450 H torsion bar 500 Wiring 600 York 650 Lower Yoke 710 First Magnet 720 Second Magnet 730 Third Magnet 740 4th Magnet 810 1st Middle York 820 Second Middle York 830 3rd Middle York 840 4th Middle York

Claims

[Claim 1] a first base portion coupled to the driven portion; A coil disposed on the first base portion; A first magnet is disposed so as to surround a part of the outer periphery of the coil; a second magnet disposed to surround a portion of the outer periphery of the coil that is not surrounded by the first magnet; a first middle yoke provided on the first magnet; a second middle yoke provided on the second magnet; Equipped with The first magnet is smaller than the second magnet; The first middle yoke is disposed so that the distance from the coil to the first middle yoke in a direction different from the direction in which the driven part is disposed is shorter than the distance from the coil to the second middle yoke in the direction in which the driven part is disposed. A drive device characterized by:

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