Drive unit

Abstract

Achieves appropriate driving force with a simple configuration. [Solution] The drive device (101) comprises a first base portion (110) connected to the driven part, a coil (300) placed on the first base portion, a first magnet (710) placed to surround a part of the outer circumference of the coil, a second magnet (720) placed to surround a part of the outer circumference of the coil that is not surrounded 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, and the first middle yoke is positioned such that the distance from the coil to the first middle yoke, which is in a different direction from the coil, is shorter than the distance from the coil to the second middle yoke, which is in the direction in which the driven part is placed.

Description

Technical Field

[0001] The present invention relates to the technical field of driving devices such as MEMS scanners that drive driven objects such as mirrors.

Background Art

[0002] For example, in various technical fields such as displays, printing devices, precision measurements, precision machining, and information recording and reproduction, research on MEMS (Micro Electro Mechanical System) devices manufactured by semiconductor process technology has been actively carried out. 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 embody 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 mirror driving device with a micro-structure (optical scanner or MEMS scanner) has attracted attention.

[0003] In a mirror driving device, a configuration that drives a mirror using a coil and a magnet is common. In this case, a rotational force is applied to the mirror by the interaction between the magnetic field generated by flowing a current through the coil and the magnetic field of the magnet, and as a result, the mirror is rotated (for example, see Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the aforementioned Patent Document 1, a magnetic field is generated by placing two magnets to the side of a coil. However, if, for example, the MEMS scanner and the magnets are to be placed so that they overlap in a planar manner, the space available for placing the magnets is limited in order to secure the driving area of ​​the MEMS scanner. On the other hand, it is desirable that the magnets provide a well-balanced magnetic field to the MEMS scanner. For this reason, it is not easy to properly lay out the magnets, which may result in an increased complexity and size of the device configuration.

[0006] The problems that this invention aims to solve include, for example, those mentioned above. The object of this invention is to provide a drive device that can achieve appropriate driving force with a simple configuration. [Means for solving the problem]

[0007] To solve the above problems, the drive device comprises a first base connected to a driven part, a coil disposed on the first base, a first magnet disposed to surround a part of the outer circumference of the coil, a second magnet disposed to surround a part of the outer circumference 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 such that the distance from the coil to the first middle yoke in a direction different from the direction in which the driven part is located is shorter than the distance from the coil to the second middle yoke in the direction in which the driven part is located. [Brief explanation of the drawing]

[0008] [Figure 1] This is a plan view showing the configuration of the MEMS scanner according to the embodiment, as seen from the front. [Figure 2] This is a plan view showing the configuration of the MEMS scanner according to the embodiment, as seen from the back. [Figure 3] This is a cross-sectional view showing the stacked structure of a MEMS scanner according to an embodiment. [Figure 4]This is a side view conceptually illustrating the operation of the MEMS scanner according to the embodiment. [Figure 5] This is a plan view showing the arrangement of the magnet and middle yoke for the MEMS scanner according to the embodiment. [Figure 6] This is a cross-sectional view showing the configuration of a component that applies a magnetic field to a MEMS scanner according to the embodiment. [Figure 7] This is a conceptual diagram showing the positional relationship of the components that apply a magnetic field to the coil. [Figure 8] This is a plan view showing the arrangement of the magnet and middle yoke for the MEMS scanner related to the first comparative example. [Figure 9] This is a plan view showing the arrangement of the magnet and middle yoke for the MEMS scanner related to the second comparative example. [Figure 10] This is a conceptual diagram illustrating whether or not there is interference with the middle yoke during V-axis drive. [Modes for carrying out the invention]

[0009] The embodiments of the drive device will be described in order below.

[0010] <1> The drive 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 disposed on the first base portion, a first magnet disposed on one side of the coil, a second magnet disposed on the opposite side from the first magnet as seen 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 positioned closer to the coil than the second middle yoke.

[0011] In the drive device of this embodiment, the first base portion and the second base portion are directly or indirectly connected (in other words, linked) by an elastic part (for example, a spring portion described later). Here, due to the elasticity of the elastic part, it is preferable that the rigidity of the elastic part 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 part is relatively more deformable than both or one of the first base portion and the second base portion. To put it another way, it is preferable that the elastic part is relatively easily deformable, while both or one of the first base portion and the second base portion are relatively difficult to deform.

[0012] A coil is positioned on the first base. For example, the first base is configured as a frame-shaped structure with an opening, and the coil is wound around the opening. A first magnet is positioned on one side of the coil, and a second magnet is positioned on the opposite side of the coil from the first magnet. In other words, the two magnets are positioned so as to sandwich the coil. As a result, a magnetic field is generated around the coil due to the two magnets. Therefore, by passing a predetermined control current through the coil, a Lorentz force can be generated on the coil.

[0013] The side of the first magnet facing the coil and the side of the second magnet facing the coil typically have different polarities. Specifically, if the side of the first magnet facing the coil is the north pole, the side of the second magnet facing the coil is the south pole. Alternatively, if the side of the first magnet facing the coil is the south pole, the side of the second magnet facing the coil is the north 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 to rotate the first base section on which the coil is located. This driving force may also be transmitted to the second base section via an elastic part connected to the first base section.

[0014] A first middle yoke is provided on the surface facing the coil of the first magnet. Also, a second middle yoke is provided on the surface facing the coil of the second magnet. The first middle yoke and the second middle yoke are preferably composed of a soft magnetic material having a high relative permeability, such as pure iron, permalloy, silicon iron, sendust, etc. According to such first and second middle yokes, the magnetic fluxes generated by the first and second magnets can be suitably focused on the coil. Therefore, the driving force applied to the coil can be improved.

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

[0016] According to the above-described configuration, due to the first magnet being smaller than the second magnet, the magnetic field applied by the first magnet to the coil is smaller than the magnetic field applied by the second magnet to the coil. However, since the first middle yoke provided for the first magnet is closer to the coil than the second middle yoke provided for the second magnet, the first middle yoke has a higher magnetic flux focusing effect on the coil than the second middle yoke. Therefore, the difference in the magnitude of the magnetic field caused by the difference in the sizes of the first and second magnets is offset by the difference in the magnetic flux focusing effect caused by the difference in the distances of the first and second middle yokes, and as a result, a balanced magnetic field can be applied to the coil. Thereby, the Lorentz force generated in the coil can be made closer to a couple force, and more suitable driving of the first base portion can be realized.

[0017] A balanced magnetic field is considered to be achievable even by making the sizes of the first magnet and the second magnet uniform. However, depending on the available space for magnet placement, it may be difficult to make the sizes of the two magnets uniform. In particular, in the configuration where the second base portion is connected to the first base portion where the coil is provided, as in the present embodiment, there is a high possibility that the members need to be arranged asymmetrically with respect to the coil.

[0018] However, in the present embodiment, as described above, even when there is a difference in size between the first magnet and the second magnet, an appropriate magnetic field can be applied to the coil by adjusting the distances between the first middle yoke and the second middle yoke and the coil. Therefore, an appropriate driving force can be applied to the coil, and suitable driving can be realized.

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

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

[0021] Here, a space for arranging the second base portion inevitably occurs on the second base portion side where the second magnet is provided. Therefore, for example, by using a space that is planarly overlapped with the second base portion, it is easy to arrange the relatively large second magnet.

[0022] On the other hand, considering that the second base portion is also driven by the driving force transmitted from the first driving portion, it is required to secure a region where the second base portion drives. However, a member that is desired to be arranged at a position close to the coil (in other words, also close to the second base portion), such as a middle yoke, may interfere with the driving of the second base portion.

[0023] However, the second middle yoke provided on the second magnet is located at a greater distance from the coil than the first middle yoke. Therefore, the second middle yoke can be positioned at a distance such that it does not obstruct the drive area of ​​the second base.

[0024] <3> In the configuration in which the second magnet is arranged on the second base portion side as described above, the first magnet has a first portion provided along the first edge of the first base portion that does not face the second base portion, and a second portion provided along the second edge adjacent to the first edge, and the second magnet has a third portion provided along the third edge of the first base portion that faces the second base portion, and a fourth portion provided along the fourth edge adjacent to the third edge, the first portion being smaller than the third portion, and the portion of the first middle yoke provided on the surface of the first portion may be positioned 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 (i.e., the side not facing the second base) is smaller than the third portion provided along the third side of the first base (i.e., the side facing the second base). Therefore, the second magnet located on the second base side is larger than the first magnet. The sizes of the other second and fourth portions are typically about the same, but are not particularly limited.

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

[0027] <4> In another embodiment of the drive unit of this embodiment, 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 when viewed in plan.

[0028] According to this embodiment, the first and second middle yokes can avoid interfering with the driving of the first and second base portions. In other words, although the first and second middle yokes are arranged so as not to overlap with the first and second base portions in plan view, they can be arranged in close proximity to the first and second base portions in terms of height. Therefore, the magnetic flux focusing function of the first and second middle yokes can be effectively utilized.

[0029] <5> In another embodiment of the drive device of this embodiment, a yoke is further provided, which is inserted through the opening in the first base portion.

[0030] According to this embodiment, the magnetic flux can be focused on the coil by the yoke inserted through the opening in the first base. Therefore, the Lorentz force generated by passing a control current through the coil can be increased. That is, 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] Furthermore, in order to enhance the magnetic flux focusing effect of the yoke, it is preferable that the distance between the yoke and the coil be small. For this reason, it is preferable that the yoke be made as large as possible without interfering with the driving of the first base portion where the coil is located. In addition, it is preferable that the cross-section of the yoke be similar in shape to the opening of the first base portion.

[0032] Furthermore, the yoke is inserted, for example, from the lower side to the upper side of the first base portion. However, in order to enhance the magnetic flux focusing effect of the yoke, it is preferable to configure the yoke to extend upward to a certain extent. For this reason, it is preferable to configure the yoke to be as long as possible without interfering with the driving of the first base portion on which the coil is located.

[0033] <6> In another embodiment of the drive device of this embodiment, a driven part further comprises a driven part supported by the second base part.

[0034] In this embodiment, the second base portion supports the driven portion, which is configured as, for example, a mirror. In this case, the second base portion supports the driven portion in such a way that the driven portion is drivable (for example, rotatable or movable). More specifically, for example, the second base portion and the driven portion may be connected by an elastic portion, so that the second base portion supports the first driven portion in a drivable manner.

[0035] With a drive device having such a configuration, the driven part can be suitably driven (for example, rotated or moved). In other words, with a drive device having such a configuration, the driven part can be suitably driven (for example, rotated or moved). Specifically, for example, when the first base part moves, the second base part, which is connected to the first base part via an elastic part, also moves in accordance with the movement of the first base part. When the second base part moves, the driven part, which is supported by the second base part, also moves in accordance with the movement of the second base part. As a result, the driven part can be suitably driven. [Examples]

[0036] The following describes embodiments of the drive device of the present invention with reference to the drawings. The following description will focus on an example in which the drive device is applied to a MEMS scanner. However, it goes without saying that the drive device of the present invention may be applied to any drive device other than a MEMS scanner.

[0037] (1) Basic configuration First, the configuration of the MEMS scanner 101 according to this embodiment will be described with reference to Figures 1 to 3. Here, Figure 1 is a plan view showing the configuration of the MEMS scanner 101 according to this embodiment as seen from the front, and Figure 2 is a plan view showing the configuration of the MEMS scanner 101 according to this embodiment as seen from the back. Figure 3 is a cross-sectional view showing the stacked structure of the MEMS scanner 101 according to this embodiment.

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

[0039] The first base 110 has a frame shape with an internal void (opening). In other words, 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 (i.e., a direction perpendicular to the Y-axis direction) in the figure, and has a frame shape with a void surrounded by the two sides extending in the Y-axis direction and the two sides extending in the X-axis direction. In the examples shown in Figures 1 and 2, the first base 110 has a square shape, but is not limited to this, and may have other shapes (for example, a rectangular shape or a circular shape). Furthermore, the first base is not limited to a frame shape.

[0040] A coil 300 is positioned on the first base. The coil 300 consists of multiple windings made of a relatively conductive material (e.g., gold or copper). In this embodiment, the coil 300 has a square shape along the first base 110. However, the coil 300 may have any shape (e.g., a rectangle, rhombus, parallelogram, circle, ellipse, or any other loop shape).

[0041] A control current is supplied to the coil 300 from a power supply via power terminals (not shown). The power supply may be one provided by the MEMS scanner 101 itself, or it may be a power supply provided externally to the MEMS scanner 101. A magnet (not shown) is placed around the coil 300, and a rotational force is applied due to the interaction between the magnetic field generated by the control current flowing through the coil 300 and the magnetic field of the magnet. As a result, the first base 110 on which the coil 300 is mounted is rotated in a direction corresponding to the direction of the magnetic field and the control current.

[0042] The second base portion 120, like the first base portion 110, has a frame shape with an internal void. A mirror 400 is positioned within the void of the second base portion 120. The mirror 400 is positioned to be suspended or supported by an H-torsion bar 450.

[0043] The H-torsion bar 450 is an elastic component, such as a spring, made from materials such as silicon, copper alloy, iron-based alloy, other metals, or resin. The H-torsion bar 450 is positioned to extend in the Y-axis direction in Figure 1. In other words, the H-torsion bar 450 has a shape with a longitudinal side extending in the Y-axis direction and a transverse 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. As a result, the mirror 400 can rotate around an axis along the Y-axis direction as its axis of rotation 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 section 210. The spring section 210 is a specific example of an "elastic section" and has the function of transmitting the driving force obtained from the coil 300 in the first base 110 to the second base 120. In addition, a wiring spring section 220 is provided between the first base 110 and the second base 120. The wiring spring section 220 is provided to realize the electrical connection between the first base 110 and the second base 120. Specifically, the wiring spring section 220 has connecting wiring 225 for connecting the coil 300 of the first base 110 and the wiring 500 of the second base 120.

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

[0046] As shown in Figure 3, the MEMS scanner 101 according to this embodiment is composed of a laminated structure of a support layer 10, an active layer 20, a box layer 30, and a metal layer 40. However, it may also be a laminated structure that includes other layers.

[0047] Each of the support layer 10 and the active layer 20 is composed of, for example, silicon. The BOX layer 30 is composed of, for example, an oxide film such as SiO2 and is placed between the support layer 10 and the active layer 20. The BOX layer 30 insulates the support layer 10 and the active layer 20. The metal layer 40 is composed of, for example, a metal with high conductivity and is placed 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 connecting wiring 225 in the wiring spring section 220, etc.

[0048] The support layer 10 is formed to extend from the first base 110 to the spring portion 210 and the second base 120 (see Figure 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 not on the spring portion 210. In other words, the spring portion 210 is composed solely of the support layer 20. Furthermore, 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. Although the active layer 20 is not formed on the spring portion 210, the active layer 20 is formed on the wiring spring portion 220 (see Figure 1). This enables electrical connection between the first base 110 and the second base 120.

[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 Figure 4. Here, Figure 4 is a conceptual side view showing the operation of the MEMS scanner according to this embodiment. In Figures 4 and beyond, for the sake of explanation, detailed components constituting the MEMS scanner 101 described in Figures 1 to 3, etc., are omitted as appropriate and shown in a simplified manner.

[0050] As shown in Figure 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 direction to the lower right direction in the figure. The external magnetic field is applied by a magnet, which will be described later. However, the direction of the magnetic field shown here is just one example, and the magnetic field may be applied in other directions.

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

[0052] When a Lorentz force is generated, the first base, to which the coil 300 is installed, is driven. The driving force of the first base 110 is transmitted to the second base 120 via the spring section 210. Therefore, the second base 120 is 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 driven in conjunction with the driving of the second base 120. In this way, the generation of a Lorentz force in the coil 300 drives the first base 110, the second base 120, and the mirror 400, respectively.

[0053] Here, when the frequency of the control current supplied to coil 300 is DC to several hundred 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 its axis of rotation. As a result, the mirror 400 also rotates around the X-axis as its axis of rotation, and so-called vertical scanning is performed.

[0054] As shown in Figure 4(c), when the control current supplied to the coil 300 is set to the frequency corresponding to the natural resonant 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. As a result, the mirror 400 also rotates around the Y-axis, performing a so-called lateral scan.

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

[0056] In order to bring the Lorentz force generated in coil 300 closer to a couple, it is preferable that the magnetic field applied to coil 300 is horizontal and that the intensity is approximately the same on both sides of coil 300 (i.e., the two regions where the Lorentz force is generated).

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

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

[0059] Furthermore, a second magnet 720 is positioned on the other side of the coil 300 (lower left in the figure). The second magnet 720 is shaped like a "V" so as to follow two sides of the first base 110 on which the coil 300 is provided (specifically, two sides different from the two sides along which the first magnet 710 follows). A second middle yoke 820 is provided on the side of the second magnet 720 facing the coil 300. The second magnet 720 is positioned using a relatively wide space from below the second base 120 to below the V-torsion bar 160. In other words, the second magnet 720 is configured as a larger magnet than the first magnet 710. Moreover, the second middle yoke 820 does not completely cover the surface of the second magnet 720, but is positioned so as not to overlap with the second base in a planar manner.

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

[0061] Here, each of the yokes described above—the yoke 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—is made of a soft magnetic material with high relative permeability, such as pure iron, permalloy, silicon iron, or Sendust. These yokes allow the magnetic flux generated by the first magnet 710, the second magnet 720, the third magnet 730, and the fourth magnet 740 to be suitably focused and made parallel to the coil 300. As a result, the driving force applied to the coil 300 can be improved.

[0062] In Figure 7, in the MEMS scanner 101 according to this embodiment, 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 configured to be 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 focusing function of the first middle yoke 810 with respect to the coil 300 is higher than that of the second middle yoke 820. As a result, the difference in magnetic field strength due to the difference in size between the first magnet 710 and the second magnet 720 is canceled out by the difference in magnetic flux focusing function due to the difference in 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 should be adjusted to values ​​that can cancel out 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 operation can be brought closer to a couple, enabling more optimal operation.

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

[0065] In Figure 8, the first magnet 710b and the first middle yoke 810b in the first comparative example are provided in the same manner as the first magnet 710 and the first middle yoke 810 of the MEMS scanner 101 in this embodiment (see Figure 5). On the other hand, the second magnet 720b and the second middle yoke 820b in the first comparative example are provided to be smaller than the second magnet 720 and the second middle yoke 820 of the MEMS scanner 101 in this embodiment (see Figure 5). Specifically, the first magnet 710b and the second magnet 720b in the first comparative example are of roughly the same size and are configured to apply equivalent magnetic fields to the coil 300.

[0066] However, in the first comparative example, the size of the second magnet 720 is smaller compared to this embodiment, resulting in a decrease in driving efficiency. Specifically, because the empty space on the left side of the second base 120 is not effectively utilized, the magnetic field applied to the coil 300 is weaker, and the Lorentz generated in the coil 300 is also reduced.

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

[0068] However, in the second comparative example, the first magnet 710 is larger than in this embodiment, causing it to protrude outside the chip. This increases the overall device size, including the magnetic circuit, leading to a larger device.

[0069] In Figure 10(a), in the first and second comparative examples, the second middle yoke 820 is positioned so as to overlap the second base 120 in a planar manner. Therefore, for example, when the MEMS scanner 101b or 101c is driven with the V-axis (X-axis) as the axis of rotation, the second base 120 and the second middle yoke 820 interfere with each other. As a way to avoid such interference, for example, one could consider positioning the second middle yoke 820 at a distance from the second base 120, but this would reduce the magnetic flux focusing function of the second middle yoke 820.

[0070] On the other hand, in Figure 10(b), according to this embodiment, the second middle yoke 820 is not positioned to overlap the second base 120 in a planar manner. Therefore, even if the MEMS scanner 101 is driven with the V-axis (X-axis) as the axis of rotation, interference between the second base 120 and the second middle yoke 820 can be avoided.

[0071] As described above, in the MEMS scanner 101 according to this embodiment, multiple magnets and yokes are arranged in a manner that avoids interference with the MEMS scanner 101 during operation, and a well-balanced magnetic field is applied to the coil 300. Therefore, suitable operation of the MEMS scanner 101 is achieved.

[0072] Furthermore, the MEMS scanner 101 according to each of the embodiments described above can be applied to various electronic devices such as head-up displays, head-mounted displays, laser scanners, laser printers, and scanning drive devices. Therefore, these electronic devices are also included within the scope of the present invention.

[0073] Furthermore, the present invention can be modified as appropriate, provided that it does not contradict the gist or idea of ​​the invention as can be inferred from the claims and the specification as a whole, and a drive device with 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 1st Base 120 2nd base 150, 160 V Torsion Bar 210 Spring section 220 Wiring spring section 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 Fourth Magnet 810 1st Middle York 820 Second Middle York 830 Third Middle York 840 4th Middle York

Claims

[Claim 1] A first base portion connected to the driven portion, A coil placed on the first base portion, A first magnet is arranged so as to surround a part of the outer circumference of the coil, A second magnet is positioned to surround a portion of the outer circumference of the coil that is not surrounded by the first magnet, The first middle yoke provided on the first magnet, The second middle yoke provided on the second magnet and Equipped with, The first magnet is smaller than the second magnet. The first middle yoke is positioned such that the distance from the coil to the first middle yoke, which is in a direction different from the direction in which the driven part is located, is shorter than the distance from the coil to the second middle yoke, which is in the direction in which the driven part is located. A drive device characterized by the following features.

Images