JP2022033852A - Drive device - Google Patents

Abstract

PROBLEM TO BE SOLVED: 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

COPYRIGHT: (C)2022,JPO&INPIT

Description

The present invention relates to the technical field of a driving device such as a MEMS scanner that drives a driven object such as a mirror.

For example, in various technical fields such as displays, printing devices, precision measurement, precision processing, and information recording / reproduction, research on MEMS (Micro Electro Electrical System) devices manufactured by semiconductor process technology is being actively promoted. As such a MEMS device, for example, a display field in which light incident from a light source is scanned against a predetermined screen area to embody an image, or light reflected by scanning light with respect to a predetermined screen area. In the field of scanning in which light is received and image information is read, a mirror drive device (optical scanner or MEMS scanner) having a minute structure is attracting attention.

In a mirror drive device, a configuration in which a mirror is driven by 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 passing an electric current through the coil and the magnetic field of the magnet, and as a result, the mirror is rotated (see, for example, Patent Document 1). ).

Japanese Unexamined Patent Publication No. 11-231252

In Patent Document 1 described above, a magnetic field is generated by arranging two magnets on the side of the coil. However, for example, when the MEMS scanner and the magnet are arranged so as to overlap each other in a plane, the space for arranging the magnet is limited in order to secure the drive area of the MEMS scanner. On the other hand, it is desirable that the magnet applies a well-balanced magnetic field to the MEMS scanner. Therefore, it is not easy to lay out the magnets properly, and as a result, the device configuration may become complicated or large.

The above-mentioned problems are given as an example of the problems to be solved by the present invention. An object of the present invention is to provide a driving device capable of realizing an appropriate driving force with a simple configuration.

In order to solve the above problems, the drive device is arranged so as to surround a first base portion connected to the driven portion, a coil arranged on the first base portion, and a part of the outer periphery of the coil. A first magnet, a second magnet arranged so as to surround a part of the outer periphery of the coil that is not surrounded by the first magnet, and a first magnet provided on the first magnet. A middle yoke and a second middle yoke provided on the second magnet are provided, the first magnet is smaller than the second magnet, and the first middle yoke has the driven portion from the coil. It is arranged so that the distance from the coil to the first middle yoke in a direction different from the direction is closer than the distance to the second middle yoke in the arranged direction.

It is a top view which shows the structure when the MEMS scanner which concerns on an Example is seen from the front side. It is a top view which shows the structure when the MEMS scanner which concerns on an Example is seen from the back side. It is sectional drawing which shows the laminated structure of the MEMS scanner which concerns on Example. It is a side view which conceptually shows the mode of operation of the MEMS scanner which concerns on embodiment. It is a top view which shows the arrangement of the magnet and the middle yoke with respect to the MEMS scanner which concerns on embodiment. It is sectional drawing which shows the structure of the member which applies the magnetic field to the MEMS scanner which concerns on Example. It is a conceptual diagram which shows the positional relationship of the member which applies a magnetic field to a coil. It is a top view which shows the arrangement of the magnet and the middle yoke with respect to the MEMS scanner which concerns on 1st comparative example. It is a top view which shows the arrangement of the magnet and the middle yoke with respect to the MEMS scanner which concerns on 2nd comparative example. It is a conceptual diagram explaining the presence or absence of the interference with the middle yoke at the time of V-axis drive.

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

<1>
The drive device of the present embodiment includes a first base portion, a second base portion, an elastic portion connecting the first base portion and the second base portion, and a coil arranged on the first base portion. The first magnet arranged on one side of the coil, the second magnet arranged on the side opposite to the first magnet when viewed from the coil, and the surface of the first magnet facing the coil. The first middle yoke is provided on the surface of the second magnet facing the coil of the second magnet, and the first magnet is smaller than the second magnet and is smaller than the second magnet. The 1 middle yoke is arranged at a position closer to the coil than the 2nd middle yoke.

According to the drive device of the present embodiment, the first base portion and the second base portion are directly or indirectly connected (in other words, connected) by an elastic portion having elasticity (for example, a spring portion described later). ) Has been. Here, because the elastic portion has elasticity, the rigidity of the elastic portion is preferably 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 other words, it is preferable that the elastic portion is relatively easy to be deformed, while both or one of the first base portion and the second base portion is relatively hard to be deformed.

A coil is arranged on the first base portion. For example, the first base portion is configured as a frame-shaped frame having an opening portion, and a coil is wound around the opening portion. Further, a first magnet is arranged on one side of the coil, and a second magnet is arranged on the side opposite to the first magnet when viewed from the coil. That is, two magnets are arranged 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 for the coil by passing a predetermined control current through the coil.

The surface of the first magnet facing the coil and the surface of the second magnet facing the coil typically have different polarities. Specifically, when the surface of the first magnet facing the coil is the N pole, the surface of the second magnet facing the coil is the S pole. Alternatively, when the surface of the first magnet facing the coil is the S pole, the surface of the second magnet facing the coil is the N pole. In this case, when a control current is passed through the coil, Lorentz forces having different directions are generated on the first magnet side and the second magnet side of the coil. Such a Lorentz force acts as a driving force for rotating the first base portion in which the coil is arranged. It should be noted that such a driving force may be transmitted to the second base portion via the elastic portion connected to the first base portion.

A first middle yoke is provided on the surface of the first magnet facing the coil. Further, 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 composed of a soft magnetic material having a high relative magnetic permeability such as pure iron, permalloy, silicon iron, and sendust. According to such a first middle yoke and a second middle yoke, the magnetic flux generated from the first magnet and the second magnet can be suitably focused on the coil. Therefore, the driving force applied to the coil can be improved.

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

According to the configuration described above, the magnetic field applied to the coil by the first magnet is smaller than the magnetic field applied to the coil by the second magnet because the first magnet is smaller than the second magnet. However, since the first middle yoke provided on the first magnet is closer to the coil than the second middle yoke provided on the second magnet, the first middle yoke focuses the magnetic flux on the coil more than the second middle yoke. The effect is high. Therefore, the difference in the magnitude of the magnetic field due to the size of the first magnet and the second magnet is offset by the difference in the magnetic flux focusing effect due to 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. As a result, the Lorentz force generated in the coil can be brought close to the couple, and a more suitable drive of the first base portion can be realized.

It is considered that a well-balanced magnetic field can be realized by aligning the sizes of the first magnet and the second magnet, but it is difficult to align the sizes of the two magnets depending on the space in which the magnets can be placed. There is also. In particular, in the embodiment in which the second base portion is connected to the first base portion where the coil is provided as in the present embodiment, it is highly likely that each member is required to be arranged asymmetrically with respect to the coil. ..

However, in the present embodiment, as described above, even if there is a difference in size between the first magnet and the second magnet, the distance between the first middle yoke and the second middle yoke and the coil is adjusted. , Appropriate magnetic field can be applied to the coil. Therefore, an appropriate driving force can be applied to the coil to realize an appropriate driving force.

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

According to this aspect, the second magnet, which is the larger magnet, is arranged on the second base portion side when viewed from the coil. In other words, the smaller magnet will be placed on the side opposite to the second base portion when viewed from the coil.

Here, a space for arranging the second base portion is inevitably generated on the side of the second base portion where the second magnet is provided. Therefore, for example, if a space that overlaps with the second base portion in a plane is used, it is easy to arrange a relatively large second magnet.

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 to be driven by the second base portion. However, a member that is desired to be arranged at a position close to the coil (in other words, a position close to the second base portion) such as the middle yoke may hinder the driving of the second base portion.

However, the second middle yoke provided on the second magnet has a larger distance from the coil than the first middle yoke. Therefore, it is easy to arrange the second middle yoke at a distance so as not to interfere with the drive region of the second base portion, for example.

<3>
In the embodiment in which the second magnet is arranged on the second base portion side as described above, the first magnet is provided along the first side of the first base portion on the side not facing the second base portion. It has a first portion and a second portion provided along a second side adjacent to the first side, and the second magnet is the second base of the first base portion. It has a third portion provided along the third side on the side facing the portion and a fourth portion provided along the fourth side adjacent to the third side. 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 is provided on the surface of the third portion of the second middle yoke. It may be arranged at a position closer to the coil than the portion.

In this case, the first portion of the first magnet is provided smaller than the third portion of the second magnet. Specifically, the first portion provided along the first side of the first base portion (that is, the side that does not face the second base portion) is the third side of the first base portion (that is, that is). , The side facing the second base portion) is provided smaller than the third portion provided. Therefore, the second magnet arranged on the second base portion side is made larger than the first magnet. The sizes of the other second and fourth portions are typically about the same, but are not particularly limited.

On the other hand, the portion of the first middle yoke provided on the surface of the first portion is arranged 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 due to the size of the first portion and the third portion is the difference in the magnetic flux focusing effect due to the difference in the distance of the middle yokes provided in each of the first portion and the third portion. More offset. Therefore, a balanced magnetic field can be applied to the coil.

<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 with the first base portion and the second base portion in a plane view. ..

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 the first base portion and the second base portion in a plane, but the first base portion and the second middle yoke are arranged in terms of height. 2 Can be placed close to the base. Therefore, the magnetic flux focusing function of the first middle yoke and the second middle yoke can be effectively exerted.

<5>
In another aspect of the drive device of the present embodiment, a yoke inserted through the opening of the first base portion is further provided.

According to this aspect, the magnetic flux can be focused on the coil by the yoke inserted through the opening portion of the first base portion. 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. Like the first middle yoke and the second middle yoke, the yoke is preferably composed of a soft magnetic material having a high relative magnetic permeability such as pure iron, permalloy, silicon iron, and sendust.

In order to enhance the effect of focusing 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 enlarged within a range that does not interfere with the driving of the first base portion in which the coil is arranged. Further, it is preferable that the cross section of the yoke has a shape close to the shape of the opening portion of the first base portion.

Further, the yoke is inserted from the lower side to the upper side of the first base portion, for example, but in order to enhance the effect of focusing the magnetic flux by the yoke, it is preferable to configure the yoke so as to extend upward to some extent. Therefore, it is preferable that the yoke is long as long as it does not interfere with the driving of the first base portion in which the coil is arranged.

<6>
In another aspect of the driving device of the present embodiment, a driven portion supported by the second base portion is further provided.

According to this aspect, the second base portion supports a driven portion configured as, for example, a mirror or the like. At this time, the second base portion supports the driven portion so that the driven portion can be driven (for example, rotatable or movable). More specifically, for example, the second base portion and the driven portion are connected by an elastic portion having elasticity, so that the second base portion supports the first driven portion in a driveable manner. May be good.

According to the drive device having such a configuration, the driven portion can be suitably driven (for example, rotated or moved). That is, according to the drive device having such a configuration, the driven unit can be suitably driven (for example, rotated or moved). Specifically, for example, when the first base portion moves, the second base portion connected to the first base portion via the elastic portion also moves with the movement of the first base portion. .. When the second base portion moves, the driven portion supported by the second base portion also moves with the movement of the second base portion. As a result, the driven portion can be suitably driven.

Hereinafter, examples of the drive device of the present invention will be described with reference to the drawings. In the following, an example in which the drive device is applied to the MEMS scanner will be described. However, it goes without saying that the drive device of the present invention may be applied to any drive device other than the MEMS scanner.

(1) Basic Configuration First , the configuration of the MEMS scanner 101 according to the present embodiment will be described with reference to FIGS. 1 to 3. Here, FIG. 1 is a plan view showing a configuration when the MEMS scanner 101 according to the embodiment is viewed from the front side, and FIG. 2 shows a configuration when the MEMS scanner 101 according to the embodiment is viewed from the back side. It is a plan view. Further, FIG. 3 is a cross-sectional view showing a laminated structure of the MEMS scanner 101 according to the embodiment.

As shown in FIGS. 1 and 2, the MEMS scanner 101 according to the present embodiment includes a first base 110, a second base 120, V torsion bars 150 and 160, a spring portion 210, and a wiring spring portion 220. , Coil 300, mirror 400, and H torsion bar 450 are provided.

The first base 110 has a frame shape having a gap (opening portion) inside. That is, the first base 110 has two sides extending in the Y-axis direction in the drawing and two sides extending in the X-axis direction (that is, a direction orthogonal to the Y-axis direction) in the drawing, and Y. It has a frame shape having a gap surrounded by two sides extending in the axial direction and two sides extending in the X-axis direction. In the examples shown in FIGS. 1 and 2, the first base 110 has a square shape, but is not limited to this, and is not limited to this, for example, other shapes (for example, a rectangular shape such as a rectangle). Or a circular shape, etc.). Further, the first base is not limited to the frame shape.

A coil 300 is arranged on the first base. The coil 300 is, for example, a plurality of windings made of a material having a relatively high conductivity (for example, gold, copper, etc.). In this embodiment, the coil 300 has a square shape along the first base 110. However, the coil 300 may have an arbitrary shape (for example, a rectangle, a rhombus, a parallelogram, a circle, an ellipse, or any other loop shape).

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

Like the first base portion 110, the second base portion 120 has a frame shape having a gap inside. A mirror 400 is arranged in the gap of the second base 120. The mirror 400 is arranged to be suspended or supported by the H torsion bar 450.

The H torsion bar 450 is a member having elasticity such as a spring made of, for example, silicon, a copper alloy, an iron-based alloy, another metal, a resin, or the like. The H torsion bar 450 is arranged so as to extend in the Y-axis direction in FIG. In other words, the H torsion bar 450 has a shape having a length extending in the Y-axis direction and a short hand extending in the X-axis direction. One end of the H torsion bar 450 is connected to the second base 110. Also, the other end of the H torsion bar 450 is connected to the mirror 400. Therefore, the mirror 400 can rotate with the axis along the Y-axis direction as the rotation axis due to the elasticity of the H torsion bar 450. The mirror 400 is a specific example of the "driven unit".

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 the “elastic portion” and has a function of transmitting the driving force obtained from the coil 300 in the first base 110 to the second base 120. Further, 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, the wiring spring portion 220 is provided with a connection wiring 225 for connecting the coil 300 of the first base 110 and the wiring 500 of the second base 120.

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

As shown in FIG. 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, a laminated structure including other layers may be used.

Each of the support layer 10 and the active layer 20 is configured to contain, for example, silicon. The BOX layer 30 is composed of, for example, an oxide film such as SiO ₂ , and is arranged 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 configured to contain, for example, a metal having high conductivity, and is arranged on the active layer 20. The metal layer 40 constitutes a coil 300 in the first base 110, a wiring 500 in the second base 120, a connection wiring 225 in the wiring spring portion 220, and the like.

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 (specifically, see FIG. 2). 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 composed of only the support layer 20. Further, the spring portion 210 is integrally configured 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 FIG. 1). Therefore, the electrical connection between the first base 110 and the second base 120 can be realized.

(2) Operation of the MEMS Scanner Next, the operation of the MEMS scanner 101 according to the present embodiment will be described with reference to FIG. Here, FIG. 4 is a side view conceptually showing an operation mode of the MEMS scanner according to the embodiment. In the drawings after FIG. 4, for convenience of explanation, the detailed members constituting the MEMS scanner 101 described in FIGS. 1 to 3 and the like are simply shown by omitting them as appropriate.

As shown in FIG. 4A, in the MEMS scanner 101 according to the present 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 described later. However, the direction of the magnetic field here is an example, and the magnetic field may be applied in another direction.

In FIGS. 4A and 4B, a control current is supplied to the coil 300 during operation of the MEMS scanner 101 according to the present embodiment. Then, a Lorentz force is generated due to the electromagnetic interaction between the magnetic field generated by supplying the control current to the coil 300 and the external magnetic field. Specifically, Lorentz force in the opposite direction is generated at one end and the other end of the coil 300.

When the Lorentz force is generated, the first base provided with the coil 300 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 drive 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 drive of the second base 120. As described above, the Lorentz force generated in the coil 300 drives each of the first base 110, the second base 120, and the mirror 400.

Here, when the frequency of the control current supplied to the coil 300 is DC to several 100 Hz, the MEMS scanner 101 rotates about the X axis. Specifically, the MEMS scanner 101 rotates around the V torsion bars 150 and 160 as a rotation axis. As a result, the mirror 400 also rotates around the X axis as a rotation axis, and so-called vertical scanning is executed.

As shown in FIG. 4C, when the control current supplied to the coil 300 has a frequency corresponding to the natural resonance mode, the MEMS scanner 101 rotates about the Y axis. Specifically, each of the first base 110 and the second base 120 of the MEMS scanner 101 rotates around different axes along the Y axis. As a result, the mirror 400 also rotates around the Y axis as a rotation axis, and so-called lateral scanning is executed.

At the time of driving described above, the Lorentz force generated in the coil 300 is preferably a couple. In particular, in the drive with the Y axis as the rotation axis, the rotation center of the coil 300 is only determined by the dimensions, hardness, and weight of each part of the structure, and is easily affected when an external force is applied. If the Lorentz force generated in the coil 300 deviates from the couple, another motion (for example, the translational motion of the coil 300) is mixed with the resonance motion, which hinders the smooth resonance motion.

In order to bring the Lorentz force generated in the coil 300 close to the couple, the magnetic field applied to the coil 300 is horizontal, and the strengths on the left and right sides of the coil 300 (that is, the two regions where the Lorentz force is generated) are about the same. Is preferable.

(3) Arrangement of Magnets and Yorks Next, the configurations of the magnets and yokes that generate a magnetic field for the MEMS scanner 101 according to the present embodiment will be described with reference to FIGS. 5 to 7. Here, FIG. 5 is a plan view showing the arrangement of the magnet and the middle yoke with respect to the MEMS scanner according to the embodiment. Further, FIG. 6 is a cross-sectional view showing the configuration of a member that applies a magnetic field to the MEMS scanner according to the embodiment. FIG. 7 is a conceptual diagram showing the positional relationship of the members that apply a magnetic field to the coil.

In FIG. 5, according to the MEMS scanner 101 according to the present embodiment, the first magnet 710 is arranged on one side of the coil 300 (upper right in the figure). The first magnet 710 has a dogleg shape so as to be along the two sides of the first base 110 on which the coil 300 is provided. A first middle yoke 810 is provided on the surface of the first magnet 710 on the side facing the coil 300.

Further, a second magnet 720 is arranged on the other side of the coil 300 (lower left in the drawing). The second magnet 720 has a dogleg shape so as to be along 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 is aligned). There is. A second middle yoke 820 is provided on the surface of the second magnet 720 on the side facing the coil 300. The second magnet 720 is arranged using a relatively wide space from the lower part of the second base 120 to the lower part of the V torsion bar 160. That is, the second magnet 720 is configured as a magnet larger than the first magnet 710. Further, the second middle yoke 820 is provided at a position that does not cover the entire surface of the second magnet 720 but does not overlap with the second base in a plane.

In FIG. 6, the coil 300 is inserted with a yoke 600 extending upward from the lower yoke 650. Further, a third magnet 730 and a fourth magnet 740 are arranged on the upper side of the MEMS scanner 101. A third middle yoke 830 is provided on the surface of the third magnet 730 on the side facing the coil 300. A fourth middle yoke 840 is provided on the surface of the fourth magnet 740 facing the coil 300.

Here, the yokes of the above-mentioned yoke 600, lower yoke 650, first middle yoke 810, second middle yoke 820, third middle yoke 830, and fourth middle yoke 840 are, for example, pure iron, permalloy, silicon iron, and sendust. It is composed of a soft magnetic material having a high relative magnetic permeability such as. According to 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 focused and parallel to the coil 300. .. As a result, the driving force applied to the coil 300 can be improved.

In FIG. 7, in the MEMS scanner 101 according to the present embodiment, in particular, the distance L1 between the portion of the first middle yoke 810 along the right side of the coil 300 and the yoke 600 is the second middle yoke 820. The coil 300 is configured to be smaller than the distance L2 between the portion along the left side in the drawing 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. Therefore, the difference in the strength of the magnetic field due to the difference in the size of the first magnet 710 and the second magnet 720 is offset by the difference in the magnetic flux focusing function due to the difference in the distance between the first middle yoke 810 and the second middle yoke 820. The magnet. In other words, L1 and L2, which are the distances between the first middle yoke 810 and the second middle yoke 820 and the yoke 600, are values that can offset the difference in magnetic field strength between the first magnet 710 and the second magnet 720. It may be adjusted.

As a result, a well-balanced magnetic field is applied to the coil 300. Therefore, the Lorentz force generated in the coil 300 at the time of driving can be brought close to the couple, and more suitable driving can be realized.

(4) Comparison with Comparative Example Next, by comparing 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 FIGS. 8 to 10, the present embodiment will be obtained. The advantages of the MEMS scanner 101 will be specifically described. Here, FIG. 8 is a plan view showing the arrangement of the magnet and the middle yoke with respect to the MEMS scanner according to the first comparative example. Further, FIG. 9 is a plan view showing the arrangement of the magnet and the middle yoke with respect to the MEMS scanner according to the second comparative example. FIG. 10 is a conceptual diagram illustrating the presence or absence of interference with the middle yoke when the V-axis is driven.

In FIG. 8, the first magnet 710b and the first middle yoke 810b according to the first comparative example are the same as the first magnet 710 and the first middle yoke 810 (see FIG. 5) of the MEMS scanner 101 according to the present embodiment. It is provided as. On the other hand, the second magnet 720b and the second middle yoke 820b according to the first comparative example are provided to be smaller than the second magnet 720 and the second middle yoke 820 (see FIG. 5) of the MEMS scanner 101 according to the present embodiment. Has been done. Specifically, the first magnet 710b and the second magnet 720b according to the first comparative example have the same size as each other, and are configured to apply the same magnetic field to the coil 300.

However, in the first comparative example, the size of the second magnet 720 is smaller than that in the present embodiment, so that 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 by that amount, and the Lorentz generated in the coil 300 is also reduced.

In FIG. 9, the first magnet 710c and the first middle yoke 810c according to the second comparative example are larger than the first magnet 710 and the first middle yoke 810 (see FIG. 5) of the MEMS scanner 101 according to the present embodiment. It is provided as a thing. On the other hand, the second magnet 720b according to the first comparative example is provided as the same as the second magnet 720 of the MEMS scanner 101 according to the present embodiment. However, the second middle yoke 820 according to the second embodiment is not partially provided like the second middle yoke 820 according to the present embodiment, but covers the entire surface of the second magnet 720 on the coil 300 side. It is provided as follows. Therefore, also in the second comparative example, the first magnet 710c and the second magnet 720c have the same size as each other and apply the same magnetic field to the coil 300, as in the first comparative example described above. It is configured as.

However, in the second comparative example, the size of the first magnet 710 is larger than that in the present embodiment, so that the magnet 710 protrudes to the outside of the chip. For this reason, the size of the device including the magnetic circuit becomes large, which leads to an increase in the size of the device.

In FIG. 10A, in the first comparative example and the second comparative example, the second middle yoke 820 is further arranged at a position where the second middle yoke 820 is planarly overlapped with the second base 120. 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 of avoiding such interference, for example, a method of arranging the second middle yoke 820 at a position away from the second base 120 can be considered, but the magnetic flux focusing function of the second middle yoke 820 is deteriorated by that amount. ..

On the other hand, in FIG. 10B, according to the present embodiment, the second middle yoke 820 is not arranged at a position where the second middle yoke 820 is planarly overlapped with the second base 120. Therefore, for example, even when the MEMS scanner 101 is driven with the V axis (X axis) as the rotation axis, it is possible to prevent the second base 120 and the second middle yoke 820 from interfering with each other.

As described above, according to the MEMS scanner 101 according to the present embodiment, a plurality of magnets and yokes are arranged in such a manner as to avoid interference with the MEMS scanner 101 during driving, and the coil 300 is provided with a plurality of magnets and yokes. A well-balanced magnetic field is applied. Therefore, suitable driving of the MEMS scanner 101 is realized.

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

Further, the present invention can be appropriately modified within the scope of the claims and within the range not contrary to the gist or idea of the invention which can be read from the entire specification, and the driving device accompanied by such modification is also included in the technical idea of the present invention. Will be.

10 Support layer 20 Active layer 30 BOX layer 40 Metal layer 101 MEMS scanner 110 1st base 120 2nd base 150,160 V torsion bar 210 Spring part 220 Wiring Spring part 225 Connection wiring 300 Coil 400 Mirror 450 H Torsion bar 500 Wiring 600 York 650 Lower yoke 710 1st magnet 720 2nd magnet 730 3rd magnet 740 4th magnet 810 1st middle yoke 820 2nd middle yoke 830 3rd middle yoke 840 4th middle yoke

Claims (1)

The first base part connected to the driven part and
The coil arranged on the first base portion and
A first magnet arranged so as to surround a part of the outer circumference of the coil,
A second magnet that is a part of the outer circumference of the coil and is arranged so as to surround a portion that is not surrounded by the first magnet.
The first middle yoke provided on the first magnet and
A second middle yoke provided on the second magnet is provided.
The first magnet is smaller than the second magnet,
The first middle yoke is a distance from the coil to the first middle yoke in a direction different from the direction from the distance from the coil to the second middle yoke in the direction in which the driven portion is arranged. A drive unit characterized by being arranged so that they are close to each other.

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