Optical device

Abstract

An optical device includes a support portion, a first movable portion having an optical surface, a frame-shaped second movable portion surrounding the first movable portion, a first link portion linking the first movable portion and the second movable portion to each other, a second link portion linking the second movable portion and the support portion to each other, and a softening member having a softening characteristic and on which a stress acts when the first movable portion is shaken around a first axis. The softening member is disposed in a portion of the second movable portion extending between a driving element and the first link portion as viewed in a direction perpendicular to the optical surface, and is not electrically connected to the outside.

Description

[0001] This application is a divisional application of the patent application filed on May 10, 2019 , application No. 201980030165.4 , and titled Optical device Figure 1 . TECHNICAL FIELD

[0002] One aspect of the present application relates to, for example, an optical device configured as a MEMS (Micro Electro Mechanical Systems) device. BACKGROUND

[0003] As a MEMS device, there is known an optical device having a support portion, a movable portion, and a linking portion linking the movable portion and the support portion in a manner that the movable portion can swing around a prescribed axis and that the linking portion is deformed in torsion when the movable portion swings. In such an optical device, the linking portion sometimes has a hardening characteristic in which a spring constant increases as a torsion angle increases. When the linking portion has the hardening characteristic, there is a risk that a control characteristic of a swing angle of the movable portion will be degraded. To solve this problem, there is proposed a technique in which the linking portion is configured by two leaf springs that are opposed to each other with a prescribed interval interposed therebetween, thereby suppressing the hardening characteristic of the linking portion (see, for example, Patent Literature 1).

[0004] PRIOR ART DOCUMENTS

[0005] PATENT LITERATURE

[0006] Patent Literature 1: Japanese Patent Application Laid-Open No. 2000-330067 SUMMARY

[0007] PROBLEMS TO BE SOLVED BY THE INVENTION

[0008] In the prior art as described above, since the swing axis is located between the two leaf springs, a stress other than a torsion stress acts locally on the linking portion when the movable portion swings, as a result of which there is a risk that the linking portion will be broken. In particular, in a case where the swing of the movable portion is speeded up or a case where the swing angle is increased, since the stress acting on the linking portion increases, the risk of breakage of the linking portion becomes significant.

[0009] Therefore, an object of one aspect of the present application is to provide an optical device in which the influence of the hardening characteristic of the linking portion can be suppressed and reliability can be ensured even in a case where the swing of the movable portion is speeded up or a case where the swing angle is increased.

[0010] MEANS OF SOLVING THE PROBLEM

[0011] An optical device according to an aspect of the present application includes: a support portion; a first movable portion having an optical surface; a frame-shaped second movable portion surrounding the first movable portion; a first link portion linking the first movable portion and the second movable portion to each other in such a manner that the first movable portion is able to swing around a first axis; a second link portion linking the second movable portion and the support portion to each other; and a softening member having a softening characteristic and being subjected to stress when the first movable portion swings around the first axis, the softening member being disposed in a portion of the second movable portion extending between a driving element and the first link portion when viewed from a direction perpendicular to the optical surface, and not being electrically connected to the outside.

[0012] In the optical device, in order to suppress the influence of the hardening characteristic of the first link portion on the control characteristic of the swing angle of the first movable portion, the softening member having the softening characteristic is provided. In order to suppress the influence of the hardening characteristic of the first link portion, the softening member needs to be disposed at a position where stress acts when the first movable portion swings. On the other hand, in order to suppress the occurrence of an adverse condition in the softening member and ensure reliability, the softening member needs to be disposed at a position where excessive stress does not act when the first movable portion swings. In the optical device, the softening member is disposed in a portion of the second movable portion extending between the driving element and the first link portion when viewed from a direction perpendicular to the optical surface. Thus, it is possible to avoid that excessive stress acts on the softening member, and at least a part of the hardening characteristic of the first link portion is offset by the softening characteristic of the softening member. Therefore, according to the optical device, even in a case where the swing of the first movable portion is speeded up or a case where the swing angle is increased, it is possible to suppress the influence of the hardening characteristic of the first link portion, and it is possible to ensure reliability. Furthermore, since the softening member is not electrically connected to the outside, it is possible to improve the degree of freedom in the design of the softening member.

[0013] An optical device according to an aspect of the present application includes: a support portion; a first movable portion having an optical surface; a frame-shaped second movable portion surrounding the first movable portion; a first link portion linking the first movable portion and the second movable portion to each other in such a manner that the first movable portion is able to swing around a first axis; a second link portion linking the second movable portion and the support portion to each other; a driving element provided to the second movable portion and electrically connected to the outside; and a softening member having a softening characteristic and being subjected to stress when the first movable portion swings around the first axis, the softening member being disposed in a portion of the second movable portion extending between the driving element and the first link portion when viewed from a direction perpendicular to the optical surface, and being disposed in the second movable portion in such a manner that the softening member is located closer to an inner side than the driving element and closer to an outer side than the first link portion, and not being electrically connected to the outside.

[0014] In the optical device, a softening member having a softening property is disposed in a portion of the second movable portion that extends between the driving element and the linear portion as viewed from a direction perpendicular to the optical surface. Thus, excessive stress can be prevented from acting on the softening member, and at least a portion of the hardening property of the first connecting portion is canceled by the softening property of the softening member. Therefore, according to the optical device, even in a case where the swing of the first movable portion is speeded up or a case where the swing angle is increased, the influence of the hardening property of the first connecting portion can be suppressed, and reliability can be ensured. Furthermore, since the softening member is not electrically connected to the outside, the degree of freedom in the design of the softening member can be improved. Furthermore, since the first connecting portion has the linear portion, stress concentration is less likely to occur in the first connecting portion at the time of the swing of the first movable portion, and breakage of the first connecting portion can be suppressed, for example, as compared to a case where the entire first connecting portion has a curved shape.

[0015] The second connecting portion can also interconnect the second movable portion and the support portion in such a manner that the second movable portion is vibrated to enable the first movable portion to swing around the first axis. In this case, the first movable portion can be swung by vibrating the second movable portion.

[0016] The second connecting portion can also interconnect the second movable portion and the support portion in such a manner that the second movable portion is enabled to swing around a second axis that intersects the first axis. In this case, the second movable portion can be swung around the second axis together with the first movable portion.

[0017] An optical device according to an aspect of the present application includes: a support portion; a first movable portion having an optical surface; a first connecting portion that interconnects the first movable portion and the support portion in such a manner that the first movable portion is enabled to swing around a first axis; a driving element that is provided to at least one of the support portion and the first movable portion and is electrically connected to the outside; and a softening member having a softening property and being subjected to stress when the first movable portion swings around the first axis, the softening member being disposed in a portion of the first movable portion that extends between the optical surface and the first connecting portion as viewed from a direction perpendicular to the optical surface and not being electrically connected to the outside.

[0018] In the optical device, a softening member having a softening property is disposed in a portion of the first movable portion that extends between the optical surface and the first connecting portion as viewed from a direction perpendicular to the optical surface. Thus, excessive stress can be prevented from acting on the softening member, and at least a portion of the hardening property of the first connecting portion is canceled by the softening property of the softening member. Therefore, according to the optical device, even in a case where the swing of the first movable portion is speeded up or a case where the swing angle is increased, the influence of the hardening property of the first connecting portion can be suppressed, and reliability can be ensured. Furthermore, since the softening member is not electrically connected to the outside, the degree of freedom in the design of the softening member can be improved.

[0019] The softening member can also be disposed, in a view from a direction perpendicular to the optical surface, in a portion of the first movable portion that extends between the driving element provided to the first movable portion and the first linking portion. In this case, excessive stress can be reliably prevented from acting on the softening member, and at least a part of the hardening characteristic of the first linking portion can be effectively canceled by the softening characteristic of the softening member.

[0020] An optical device according to an aspect of the present application includes: a support portion; a first movable portion having an optical surface; a linear portion extending along a first axis and connected to the first movable portion, a first linking portion interlinking the first movable portion and the support portion in such a manner that the first movable portion is able to swing around the first axis; a driving element provided to at least one of the support portion and the first movable portion and electrically connected to the outside; and a softening member having a softening characteristic, stress acting when the first movable portion swings around the first axis, the softening member being disposed, in a view from a direction perpendicular to the optical surface, in a portion of the first movable portion that extends between the optical surface and the linear portion and not electrically connected to the outside.

[0021] In the optical device, the softening member having the softening characteristic is disposed, in a view from a direction perpendicular to the optical surface, in a portion of the first movable portion that extends between the optical surface and the linear portion. Thus, excessive stress can be prevented from acting on the softening member, and at least a part of the hardening characteristic of the first linking portion can be canceled by the softening characteristic of the softening member. Therefore, according to the optical device, even in a case where the swing of the first movable portion is speeded up or a case where the swing angle is increased, the influence of the hardening characteristic of the first linking portion can be suppressed, and reliability can be ensured. Furthermore, since the softening member is not electrically connected to the outside, the degree of freedom in the design of the softening member can be improved. Furthermore, since the first linking portion has the linear portion, stress concentration is less likely to occur in the first linking portion at the time of the swing of the first movable portion, for example, compared to a case where the entire first linking portion has a curved shape, and breakage of the first linking portion can be suppressed.

[0022] The softening member can also be disposed, in a view from a direction perpendicular to the optical surface, in a portion of the first movable portion that extends between the driving element provided to the first movable portion and the linear portion. In this case, excessive stress can be reliably prevented from acting on the softening member, and at least a part of the hardening characteristic of the first linking portion can be effectively canceled by the softening characteristic of the softening member.

[0023] The optical device according to an aspect of the present application can further include a fixed portion, and the support portion can be linked to the fixed portion in such a manner that the first movable portion is able to swing around the first axis by vibrating the support portion. In this case, the first movable portion can be swung by vibrating the support portion.

[0024] The optical device according to one aspect of the present application can further include a fixed portion, and the support portion can be coupled to the fixed portion in a manner that allows the support portion to swing around a second axis that intersects the first axis. In this case, the second movable portion can be caused to swing around the second axis together with the first movable portion.

[0025] The softening member can be disposed at a position at which a maximum stress acting on the softening member when the first movable portion swings around the first axis is 20 times or more the maximum stress acting on the first coupling portion when the first movable portion swings around the first axis. In this case, the influence of the hardening characteristics of the first coupling portion can be effectively suppressed by the softening member.

[0026] The softening member can be disposed at a position at which a maximum stress acting on the softening member when the first movable portion swings around the first axis is less than a 0.2% proof stress or a yield stress of the softening member. In this case, the softening member can be effectively prevented from being in an undesirable state, and the reliability can be further improved.

[0027] The optical device according to one aspect of the present application can include a pair of softening members that are symmetrically disposed with respect to a straight line that passes through the center of the first movable portion and is perpendicular to the first axis, as viewed from a direction perpendicular to the optical surface. In this case, the influence of the hardening characteristics of the first coupling portion can be further effectively suppressed by the pair of softening members. In addition, the weight balance can be homogenized.

[0028] The softening member can be composed of a metal. In this case, the influence of the hardening characteristics of the first coupling portion can be further effectively suppressed by the softening member.

[0029] The softening member can be embedded in the groove. In this case, the optical device can be miniaturized, for example, as compared with a case in which the softening member is disposed on the surface.

[0030] The driving element can be a coil. In such an optical device, the influence of the hardening characteristics of the first coupling portion can be suppressed, and the reliability can be ensured.

[0031] The driving element can be a piezoelectric element. In such an optical device, the influence of the hardening characteristics of the first coupling portion can be suppressed, and the reliability can be ensured.

[0032] At least a portion of the first coupling portion can be located on the first axis. In this case, unlike the related art described above, a stress other than a torsional stress with respect to the first coupling portion can be locally applied when the first coupling portion swings, and an undesirable state can be suppressed from occurring in the first coupling portion.

[0033] Effects of the Invention

[0034] According to one aspect of the present invention, an optical device can be provided that can suppress the influence of the hardening characteristics of the connecting part even when the swing of the movable part is accelerated or the swing angle is increased, and can ensure reliability. Attached Figure Description

[0035] Figure 2 This is a top view of the optical device involved in the embodiment.

[0036] Figure 1 It is shown in magnification Figure 3 A top view of a portion of it.

[0037] Figure 1 It is along Figure 4 The cross-sectional view of line III-III shown.

[0038] Figure 5 It is a diagram used to illustrate hardening properties and softening components.

[0039] Figure 6 It is a chart used to illustrate the effects of hardening characteristics and softening components on the control characteristics of the swing angle.

[0040] Figure 6 (a) is a top view of the optical device involved in the first variation. Figure 7 (b) is a top view of the optical device involved in the second variation.

[0041] Figure 7 (a) is a top view of the optical device involved in the third variation. Figure 8 (b) is a top view of the optical device involved in the fourth variation.

[0042] Figure 8 (a) is a top view of the optical device involved in the fifth variation. Figure 9 (b) is a top view of the optical device involved in the sixth variation.

[0043] Figure 9 (a) is a top view of the optical device involved in the seventh variation. Figure 1 (b) is a top view of the optical device involved in the reference example. Detailed Implementation

[0044] Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. Furthermore, in the following description, the same or equivalent elements will be referred to by the same reference numerals, and repeated descriptions will be omitted.

[0045] like Figure 1As shown, the optical device 1 includes a support portion (fixed portion) 2, a first movable portion 3, a second movable portion (support portion) 4, a pair of first torsion bars (first connecting portions) 5, 6, a pair of second torsion bars (second connecting portions) 7, 8, and a magnetic field generating portion 9. The support portion 2, the first movable portion 3, the second movable portion 4, the pair of first torsion bars 5, 6, and the pair of second torsion bars 7, 8 are integrally formed of an SOI (Silicon on Insulator) substrate, for example. That is, the optical device 1 is configured as a MEMS device. The SOI substrate has a pair of silicon layers and an insulating layer disposed between the pair of silicon layers. The support portion 2 is configured of the pair of silicon layers and the insulating layer, and the first movable portion 3, the second movable portion 4, the pair of first torsion bars 5, 6, and the pair of second torsion bars 7, 8 are configured of one of the silicon layers. In the optical device 1, the first movable portion 3 having a mirror surface (optical surface) 10 is caused to oscillate around each of the X-axis (first axis) and the Y-axis (second axis perpendicular to the first axis) which are orthogonal to each other. The optical device 1 is used in an optical switch for optical communication, an optical scanner, or the like, for example. The optical device 1 is manufactured using a MEMS technique (patterning, etching, or the like).

[0046] The magnetic field generating portion 9 is configured of a permanent magnet or the like of a Halbach array, for example. The magnetic field generating portion 9 generates a magnetic field in a direction D inclined at 45 degrees with respect to each of the X-axis and the Y-axis in plan view, for example, and acts on a coil 14 described later. Further, "in plan view" means "when viewed from a direction perpendicular to the mirror surface 10", in other words, "when viewed from a direction perpendicular to the X-axis and the Y-axis". The direction D of the magnetic field generated by the magnetic field generating portion 9 can also be inclined at an angle other than 45 degrees with respect to each of the X-axis and the Y-axis in plan view.

[0047] The support portion 2 has a quadrangular outer shape in plan view, for example, and is formed in a frame shape. The support portion 2 is disposed on one side in a direction perpendicular to the X-axis and the Y-axis with respect to the magnetic field generating portion 9. The support portion 2 supports the first movable portion 3, the second movable portion 4, and the like. The first movable portion 3 is disposed inside the support portion 2 in a state separated from the magnetic field generating portion 9. The first movable portion 3 has a shape symmetrical with respect to each of the X-axis and the Y-axis in plan view. The first movable portion 3 has a main body portion 3a, a ring-shaped portion 3b, and a pair of connecting portions 3c.

[0048] The main body portion 3a has a circular shape in plan view, but can have an arbitrary shape such as an elliptical shape, a quadrangular shape, a rhombic shape, or the like. The center P of the main body portion 3a coincides with the intersection of the X-axis and the Y-axis in plan view. A mirror surface 10 having a circular shape is provided on the surface of the main body portion 3a on the side opposite to the magnetic field generating portion 9, for example, by a metal film made of aluminum. The mirror surface 10 is provided on substantially the entire surface of the surface, but can be provided on a part of the surface. The annular portion 3b is formed in a ring shape so as to surround the main body portion 3a in plan view. The annular portion 3b has an octagonal shape in plan view, but can have an arbitrary shape such as a circular shape, an elliptical shape, a quadrangular shape, a rhombic shape, or the like. A pair of link portions 3c are provided on both sides of the main body portion 3a on the Y-axis, and link the main body portion 3a and the annular portion 3b to each other.

[0049] The second movable portion 4 is formed in a frame shape, and is disposed inside the support portion 2 so as to surround the first movable portion 3 in a state separated from the magnetic field generating portion 9. The second movable portion 4 has a pair of first connecting portions 41A, 41B; a pair of second connecting portions 42A, 42B; a pair of first linear portions 43A, 43B; a pair of second linear portions 44A, 44B; a pair of third linear portions 45A, 45B; and a pair of fourth linear portions 46A, 46B. The second movable portion 4 has a shape symmetrical with respect to each of the X-axis and the Y-axis in plan view. In the following description, the symmetry with respect to the X-axis or the Y-axis means the symmetry in plan view.

[0050] The first connecting portions 41A, 41B are located on both sides of the first movable portion 3 in the X-axis direction parallel to the X-axis. That is, each of the first connecting portions 41A, 41B has a portion opposite to the first movable portion 3 in the X-axis direction in plan view. Each of the first connecting portions 41A, 41B extends in the Y-axis direction.

[0051] The second connecting portions 42A, 42B are located on both sides of the first movable portion 3 in the Y-axis direction parallel to the Y-axis. That is, each of the second connecting portions 42A, 42B has a portion opposite to the first movable portion 3 in the Y-axis direction in plan view. Each of the second connecting portions 42A, 42B extends in the X-axis direction. The inner edge of each of the second connecting portions 42A, 42B has a recessed portion 51 recessed toward the Y-axis direction in plan view, and the outer edge of each of the second connecting portions 42A, 42B has a protruded portion 52 protruded toward the Y-axis direction in plan view. The recessed portion 51 and the protruded portion 52 are located on the Y-axis in plan view.

[0052] The first linear portions 43A, 43B are located on both sides of the second connecting portion 42A in the X-axis direction and are connected to the second connecting portion 42A. Each of the first linear portions 43A, 43B extends in the X-axis direction. The first linear portions 43A, 43B are symmetrically arranged with respect to the Y-axis. The second linear portions 44A, 44B are located on both sides of the second connecting portion 42B in the X-axis direction and are connected to the second connecting portion 42B. The second linear portions 44A, 44B extend in the X-axis direction. The second linear portions 44A, 44B are symmetrically arranged with respect to the Y-axis.

[0053] The third linear portions 45A, 45B are located on the opposite side of the second connecting portion 42A with respect to each of the first linear portions 43A, 43B and are connected to the first linear portions 43A, 43B and the first connecting portions 41A, 41B. The third linear portion 45A extends in a direction inclined by 45 degrees with respect to each of the X-axis and the Y-axis when viewed from above. The third linear portion 45B extends symmetrically with respect to the third linear portion 45A with respect to the Y-axis.

[0054] The fourth linear portions 46A, 46B are located on the opposite side of the second connecting portion 42B with respect to each of the second linear portions 44A, 44B and are connected to the second linear portions 44A, 44B and the first connecting portions 41A, 41B. The fourth linear portion 46A extends symmetrically with respect to the third linear portion 45A with respect to the X-axis. The fourth linear portion 46B extends symmetrically with respect to the fourth linear portion 46A with respect to the Y-axis and symmetrically with respect to the third linear portion 45B with respect to the X-axis.

[0055] The first torsion bars 5, 6 are arranged on both sides of the first movable portion 3 in the X-axis direction. The first torsion bars 5, 6 link the first movable portion 3 (the annular portion 3b) and the second movable portion 4 to each other in the X-axis direction in such a manner that the first movable portion 3 can rock around the X-axis (with the X-axis as a center line). The first torsion bars 5, 6 are connected to the support portion 2 via the second movable portion 4 and the second torsion bars 7, 8 as described later. That is, the first torsion bars 5, 6 can be regarded as linking the first movable portion 3 and the support portion 2 to each other in such a manner that the first movable portion 3 can rock around the X-axis. The first torsion bars 5, 6 are connected to the second movable portion 4 at the first connecting portions 41A, 41B. Each of the first torsion bars 5, 6 is deformed by being twisted when the first movable portion 3 rocks around the X-axis. Each of the first torsion bars 5, 6 has a plate shape extending in a plane parallel to the mirror surface 10. The entire first torsion bars 5, 6 are located in the X-axis direction.

[0056] The first torsion bar 5 has a linear portion 5a extending along the X-axis and having a certain width, and a pair of widened portions 5b connected to both ends of the linear portion 5a. The first torsion bar 5 is connected to the first movable portion 3 at one of the widened portions 5b, and is connected to the second movable portion 4 at the other widened portion 5b. When viewed from above, the width of the one widened portion 5b is wider closer to the first movable portion 3, and the width of the other widened portion 5b is wider closer to the second movable portion 4. A pair of edges of each widened portion 5b is curved so as to protrude toward each other. Each widened portion 5b is provided for the purpose of relaxing stress acting on the connection between the first torsion bar 5 and the first movable portion 3 or the second movable portion 4 when the first movable portion 3 is rocked about the X-axis. At least one of the pair of widened portions 5b can not be provided. The width of a certain portion of the first torsion bar 5 refers to the length in the direction perpendicular to the direction of extension of the first torsion bar 5 (the length in the Y-axis direction in the present embodiment). This point is the same for the first torsion bar 6 as well.

[0057] The first torsion bar 6 is arranged symmetrically with respect to the first torsion bar about the Y-axis. That is, the first torsion bar 6 has a linear portion 6a extending along the X-axis and having a certain width, and a pair of widened portions 6b connected to both ends of the linear portion 6a. The first torsion bar 6 is connected to the first movable portion 3 at one of the widened portions 6b, and is connected to the second movable portion 4 at the other widened portion 6b. When viewed from above, the width of the one widened portion 6b is wider closer to the first movable portion 3, and the width of the other widened portion 6b is wider closer to the second movable portion 4. A pair of edges of each widened portion 6b is curved so as to protrude toward each other. Each widened portion 6b is provided for the purpose of relaxing stress acting on the connection between the first torsion bar 6 and the first movable portion 3 or the second movable portion 4 when the first movable portion 3 is rocked about the X-axis. At least one of the pair of widened portions 5b can not be provided.

[0058] In the present embodiment, the first torsion bar 5 refers to a portion up to when the stress acting when the first movable portion 3 is rocked about the X-axis is 90% or more of the maximum stress acting on the first torsion bar 5 when the first movable portion 3 is rocked about the X-axis. In other words, the stress acting on the first movable portion 3 or the second movable portion 4 when the first movable portion 3 is rocked about the X-axis is smaller than 90% of the maximum stress acting on the first torsion bar 5 when the first movable portion 3 is rocked about the X-axis. Similarly, the first torsion bar 6 refers to a portion up to when the stress acting when the first movable portion 3 is rocked about the X-axis is 90% or more of the maximum stress acting on the first torsion bar 6 when the first movable portion 3 is rocked about the X-axis. In Figure 1 In the present embodiment, an example of the boundary between each first torsion bar 5, 6 and the first movable portion 3 and the second movable portion 4 is indicated by a dotted line B.

[0059] Second torsion bars 7, 8 are arranged on both sides of the second movable part 4 in the Y-axis direction. The second torsion bars 7, 8 link the second movable part 4 and the support part 2 to each other in the Y-axis direction in such a manner that the second movable part 4 can swing around the Y-axis (with the Y-axis as a center line). The second torsion bars 7, 8 are connected to the second movable part 4 at the second connection parts 42A, 42B. When the second movable part 4 swings around the Y-axis, each of the second torsion bars 7, 8 is twisted and deformed. Each of the second torsion bars 7, 8 extends in a meandering manner in plan view. Each of the second torsion bars 7, 8 has a plurality of linear portions 11 and a plurality of return portions 12. The plurality of linear portions 11 respectively extend in the Y-axis direction and are arranged in the X-axis direction. The plurality of return portions 12 alternately link both ends of adjacent linear portions 11.

[0060] As shown in Figure 2 and Figure 1 , the optical device 1 further includes a pair of coils 14, 15, a pair of softening members 16, 17, a first wiring 21, a second wiring 22, a third wiring 23, a fourth wiring 24, a first external terminal 25, a second external terminal 26, a third external terminal 27, a fourth external terminal 28, and four pairs of wires 29. Each of the coils 14, 15 is disposed on the second movable part 4 in such a manner as to surround the first movable part 3 and has a spiral shape in plan view. Each of the coils 14, 15 is arranged in a plane including the X-axis and the Y-axis. Each of the coils 14, 15 is wound around the first movable part 3 a plurality of times. The pair of coils 14, 15 is arranged in such a manner as to be arranged in the width direction of the second movable part 4 in plan view so as to be offset from each other.

[0061] In Figure 3 , a configuration region R1 in which the coils 14, 15 are arranged is shown by hatching. Each of the coils 14, 15 extends in the extension direction of the first connection parts 41A, 41B and the linear portions 43A to 46B in the first connection parts 41A, 41B and the linear portions 43A to 46B. In the first connection parts 41A, 41B and the linear portions 43A to 46B, the outer edge of the configuration region R1 follows the outer edge of the first connection parts 41A, 41B and the linear portions 43A to 46B, and the inner edge of the configuration region R1 follows the inner edge of the first connection parts 41A, 41B and the linear portions 43A to 46B.

[0062] Figure 2 is a cross-sectional view along the line II-II shown in Figure 3 . As shown in Figure 1As shown, the second movable portion 4 is provided with grooves 31 having shapes corresponding to the respective coils 14, 15. An insulating layer 32 is provided on the inner surface of the grooves 31, and an insulating layer 33 is provided on the insulating layer 32. The respective coils 14, 15 are disposed in the grooves 31 via the insulating layers 32, 33. The respective coils 14, 15 are inlaid wiring of the second movable portion 4. The respective coils 14, 15 are composed of, for example, a metal material such as copper (Cu) or gold (Au).

[0063] An insulating layer 34 is provided so as to cover the coils 14, 15 and the insulating layer 33. An insulating layer 35 is provided on the insulating layer 34. The respective insulating layers 32 to 35 are composed of, for example, silicon oxide, silicon nitride, silicon oxynitride, or the like. The respective insulating layers 32 to 35 are integrally formed so as to cover the surfaces (surfaces on the side opposite to the magnetic field generating portion 9) of the support portion 2, the first movable portion 3, the second movable portion 4, the first torsion bars 5, 6, and the second torsion bars 7, 8.

[0064] The softening member 16 is provided to the first connecting portion 41A of the second movable portion 4 so as to be located between the first torsion bar 5 and the coils 14, 15 in plan view. The softening member 17 is provided to the first connecting portion 41B of the second movable portion 4 so as to be located between the first torsion bar 6 and the coils 14, 15 in plan view. In Figure 2 In the second embodiment, a configuration region R2 in which the softening members 16, 17 are disposed is shown by hatching. Details of the softening members 16, 17 are described later.

[0065] The respective external terminals 25 to 28 are, for example, electrode pads provided to the support portion 2 and exposed to the outside from the insulating layer 35. To the respective external terminals 25 to 28, a pair of wires 29 is electrically connected, respectively. The respective wires 29 are drawn to the outside from the optical device 1. The external terminals 25 to 28 are electrically connected to a driving source or the like disposed outside the optical device 1 via the wires 29, respectively.

[0066] The first wiring 21 is electrically connected to the inner side end portion of the coil 14 and the first external terminal 25. The first wiring 21 extends from the inner side end portion of the coil 14 to the first external terminal 25 via the second torsion bar 7. The second wiring 22 is electrically connected to the outer side end portion of the coil 14 and the second external terminal 26. The second wiring 22 is connected to the outer side end portion of the coil 14 on the Y axis, for example. The second wiring 22 extends from the outer side end portion of the coil 14 to the second external terminal 26 via the second torsion bar 8. In this way, the coil 14 is electrically connected to the outside of the optical device 1.

[0067] The third wiring 23 is electrically connected to the inner end of the coil 15 and the third external terminal 27. The third wiring 23 extends from the inner end of the coil 15 to the third external terminal 27 via the second torsion bar 7. The fourth wiring 24 is electrically connected to the outer end of the coil 15 and the fourth external terminal 28. The fourth wiring 24 is connected to the outer end of the coil 15, for example, on the Y-axis. The fourth wiring 24 extends from the outer end of the coil 15 to the fourth external terminal 28 via the second torsion bar 8. Thus, the coil 15 is electrically connected to the external optical device 1.

[0068] In the optical device 1 configured as described above, when a drive signal for linear operation is input to the coil 14 via each external terminal 25, 26 and each wiring 21, 22, a Lorentz force acts on the coil 14 through interaction with the magnetic field generated by the magnetic field generating unit 9. By utilizing the balance between this Lorentz force and the elastic force of the second torsion bars 7, 8, the mirror 10 (first movable part 3) and the second movable part 4 can move linearly together around the Y-axis.

[0069] On the other hand, when a drive signal for resonant operation is input to coil 15 via external terminals 27, 28 and wiring 23, 24, a Lorentz force acts on coil 15 through interaction with the magnetic field generated by magnetic field generating unit 9. In addition to this Lorentz force, the mirror 10 (first movable part 3) can also resonate around the X-axis by utilizing the resonance of the first movable part 3 at its resonant frequency. Specifically, when a drive signal with a frequency equal to the resonant frequency of the first movable part 3 around the X-axis is input to coil 15, the second movable part 4 vibrates slightly around the X-axis at that frequency. This vibration is transmitted to the first movable part 3 via the first torsion bars 5, 6, causing the first movable part 3 to rock around the X-axis at that frequency. Furthermore, when the first movable part 3 is stationary, the entire first torsion bars 5, 6 are located on the X-axis; however, when the first movable part 3 rocks, only a portion of each first torsion bar 5, 6 may be located on the X-axis. For example, when the center of gravity of the first movable part 3 is located lower than the X-axis (towards the magnetic field generating part 9) due to the ribs or the like provided on the first movable part 3, the first movable part 3 will rock closer to the lower side than its stationary position. In this case, when the first movable part 3 rocks, only the connection portion of each of the first torsion bars 5 and 6 to the support part 2 is located on the X-axis. Alternatively, when the first movable part 3 rocks, the entire first torsion bars 5 and 6 may be located on the X-axis, and when the first movable part 3 is stationary, only a portion of each of the first torsion bars 5 and 6 may be located on the X-axis.

[0070] Next, the details of softening components 16 and 17 will be explained. For example... Figure 2As shown, the softening member 16 has a plurality of (four in this embodiment) dummy wiring portions 16a. The plurality of dummy wiring portions 16a each extend in the Y-axis direction and are arranged in the X-axis direction. Of the four dummy wiring portions 16a, the closer to the first torsion bar 5, the longer the length. In other words, of the dummy wiring portions 16a adjacent in the X-axis direction, the dummy wiring portion 16a on the first torsion bar 5 side is longer than the dummy wiring portions 16a on the coil 14, 15 side. Thus, the softening member 16 can be arranged in a manner following the curved shape of the coil 14, 15, and the arrangement area of the softening member 16 can be ensured. Further, the dummy wiring portion 16a can be arranged up to a position where the longer the length of the dummy wiring portion 16a in a direction perpendicular to the extending direction of the first torsion bar 5, the smaller the stress acting on the first movable portion 3 when the first movable portion 3 is rocked around the X-axis, and the adjustment of the magnitude of the softening characteristic described later can be facilitated. The widths of the respective dummy wiring portions 16a are equal to each other. The respective dummy wiring portions 16a are, for example, composed of the same metal material as the coil 14, 15. The respective dummy wiring portions 16a can also be composed of a metal material different from the metal material composing the coil 14, 15, and can be composed of, for example, copper, gold, tungsten (W), or aluminum (Al), or the like. Further, in the present embodiment, the softening member 16 is composed of a plurality of dummy wiring portions 16a, but the softening member 16 can also be composed of a single continuous dummy wiring portion 16a. Figure 2 In the present embodiment, hatching is attached to the coil 14, 15 and the softening members 16, 17 for ease of explanation, but Figure 3 the figures do not show cross sections.

[0071] The softening member 16 is arranged in the second movable portion 4 in a portion 4a extending between the coil 14, 15 and the first torsion bar 5, 6 when viewed from above. In the present embodiment, the portion 4a is a portion in the second movable portion 4 closer to the inner side than the coil 14, 15, extending annularly between the coil 14, 15 and the first torsion bar 5, 6. In other words, the softening member 16 is provided to the second movable portion 4 in a manner located closer to the inner side than the coil 14, 15 and closer to the outer side than the first torsion bar 5, 6 when viewed from above. Here, the "inner side" and the "outer side" are defined with reference to the center P (the center of the first movable portion 3, the center of the mirror surface 10) of the main body portion 3a when viewed from above. "The softening member 16 is located closer to the inner side than the coil 14, 15" means that the distance from the center P of the main body portion 3a to the softening member 16 is smaller than the distance from the center P to the coil 14, 15 (the distance along a straight line passing through the center P and the softening member 16), and "the softening member 16 is located closer to the outer side than the first torsion bar 5, 6" means that the distance from the center P to the softening member 16 is larger than the distance from the center P to the first torsion bar 5, 6.

[0072] The softening member 16 is different from the coils 14, 15 and is not electrically connected to the outside. That is, the softening member 16 is electrically independent from the outside. On the other hand, each dummy wiring portion 16a of the softening member 16 has the same structure (shape, material, etc.) as the coils 14, 15. That is, the dummy wiring portion 16a is a dummy wiring having the same structure as the coils 14, 15 but is not electrically connected to the outside. The dummy wiring portion 16a can be formed at the same time (in parallel) as the coils 14, 15. Thereby, it is possible to simplify the manufacturing process of the optical device 1.

[0073] As shown in FIG. 6, each dummy wiring portion 16a is buried in a groove 36 provided in the second movable portion 4. The groove 36 has a shape corresponding to each dummy wiring portion 16a. The groove 36 has the same cross-sectional shape as the groove 31. That is, each dummy wiring portion 16a has the same cross-sectional shape as each coil 14, 15. Each dummy wiring portion 16a is disposed in the groove 36 via the insulating layers 32, 33 and is covered by the insulating layers 34, 35. Figure 4

[0074] The softening member 17 is disposed symmetrically to the softening member 16 with respect to the Y axis and has the same structure as the softening member 16. That is, the softening member 17 is provided with a plurality of (four in the present embodiment) dummy wiring portions having the same structure as the dummy wiring portions 16a of the softening member 16. The dummy wiring portions of the softening member 17 are buried in grooves provided in the second movable portion 4. The softening member 17 is disposed in the second movable portion 4 in a portion 4a extending between the coils 14, 15 and the first torsion bars 5, 6 when viewed from above. The softening member 17 is not electrically connected to the outside.

[0075] Figure 5 is a graph for explaining the hardening characteristics and the softening member. Figure 5 is a graph for explaining the influence of the control characteristics of the hardening characteristics and the softening member on the tilt angle. Generally, a member elastically deformed, as shown by a symbol L1, has characteristics in which the spring constant is constant with respect to the twist angle. On the other hand, the first torsion bars 5, 6 having a rectangular cross-sectional shape as in the present embodiment, as shown by a symbol L2, have hardening characteristics in which the spring constant increases with an increase in the twist angle.

[0076] When each first torsion bar 5, 6 has the hardening characteristics, the control characteristics of the tilt angle of the first movable portion 3, that is, the tilt angle of the mirror surface 10, sometimes decrease as described below. The rocking of the first movable portion 3 can be expressed by a motion equation of the following formula (1). In formula (1), θ is the tilt angle of the mirror surface 10, j is the moment of inertia of the first movable portion 3, c(θ) is the viscous force of the system, k(θ) is the spring constant of the first torsion bars 5, 6, and T(θ, t) is the torque acting on the first movable portion 3.

[0077] [Num 1] ​

[0078]

[0079] In this case, the spring constant k(θ) can be approximated as shown in equation (2). In equation (2), k0 is a parameter representing the magnitude of the spring constant, and β is a parameter representing the magnitude of the nonlinearity. When parameter β is positive, it means that the first torsion bars 5 and 6 have hardening characteristics. When parameter β is negative, it means that the first torsion bars 5 and 6 have softening characteristics, where the spring constant decreases as the torsion angle increases.

[0080] [Number 2]

[0081] k(θ)=k0(1+βθ 2 (2)

[0082] like Figure 6 As shown, the frequency response of the swing angle θ varies depending on the sign of the parameter β. When β is positive (symbol L2), the frequency response tilts towards the positive frequency range compared to when β is zero (symbol L1). When β is negative (symbol L3), the frequency response tilts towards the negative frequency range compared to when β is zero (symbol L1). The degree of these tilts increases with the absolute value of β.

[0083] Because the first torsion bars 5 and 6 have hardening characteristics and their frequency characteristics are tilted, the swing angle θ changes significantly due to a small change in the driving frequency (resonance frequency), thus risking a reduction in the control characteristics of the swing angle θ. To increase the swing speed of the mirror 10, the parameter k0 needs to be increased. When the parameter k0 is increased, the hardening characteristics of the first torsion bars 5 and 6 have a significant impact on the control characteristics of the swing angle θ.

[0084] Therefore, in the optical device 1, softening members 16 and 17 are provided to suppress the hardening characteristics of the first torsion bars 5 and 6. Since the softening members 16 and 17 are made of a plastically deformable material, they have a softening characteristic where the spring constant decreases with increasing torsion angle. When the first movable part 3 oscillates around the X-axis, stress is applied to the softening members 16 and 17. The softening characteristics of the softening members 16 and 17 can counteract at least a portion of the hardening characteristics of the first torsion bars 5 and 6.

[0085] Here, in order to suppress the influence of the hardening characteristics of the first torsion bars 5, 6, the softening members 16, 17 need to be disposed at positions where stress acts when the first movable section 3 is rocked. Therefore, the softening members 16, 17 are disposed at the portion 4a of the second movable section 4, i.e., closer to the inner side than the coils 14, 15, in plan view. This is because the coils 14, 15 are disposed at positions where stress acts less when the first movable section 3 is rocked around the X axis, but the region closer to the inner side than the coils 14, 15 in the second movable section 4 acts stress of a prescribed amount or more when the first movable section 3 is rocked around the X axis.

[0086] More specifically, the softening members 16, 17 are disposed at positions where the maximum stress acting on the softening members 16, 17 when the first movable section 3 is rocked around the X axis is 1 / 20 or more of the maximum stress acting on the first torsion bars 5, 6 when the first movable section 3 is rocked around the X axis. Thus, the influence of the hardening characteristics of the first torsion bars 5, 6 can be effectively suppressed by the softening members 16, 17.

[0087] On the other hand, in order to suppress the occurrence of an adverse condition in the softening members 16, 17 and ensure reliability, the softening members 16, 17 need to be disposed at positions where excessive stress does not act when the first movable section 3 is rocked. Therefore, the softening members 16, 17 are disposed at the portion 4a of the second movable section 4, i.e., closer to the outer side than the first torsion bars 5, 6, in plan view. This is because greater stress acts on the first torsion bars 5, 6 when the first movable section 3 is rocked around the X axis.

[0088] More specifically, the softening members 16, 17 are disposed at positions where the maximum stress acting on the softening members 16, 17 when the first movable section 3 is rocked around the X axis is less than the yield stress (yield point) of the softening members 16, 17. Furthermore, the softening members 16, 17 are disposed at positions where the maximum stress acting on the softening members 16, 17 when the first movable section 3 is rocked around the X axis is 1 / 2 or less of the maximum stress acting on the first torsion bars 5, 6 when the first movable section 3 is rocked around the X axis. Thus, the occurrence of an adverse condition in the softening members 16, 17 can be suppressed.

[0089] As explained above, in the optical device 1, the softening members 16, 17 having the softening property are disposed in the second movable portion 4 at portions 4a extending between the coils 14, 15 and the first torsion bars 5, 6 in plan view. Thereby, it is possible to avoid excessive stress from acting on the softening members 16, 17, and to cancel at least a part of the hardening property of the first torsion bars 5, 6 by the softening property of the softening members 16, 17. Therefore, according to the optical device 1, it is possible to suppress the influence of the hardening property of the first torsion bars 5, 6 even in a case where the oscillation of the first movable portion 3 is speeded up or a case where the swing angle is increased, and it is possible to ensure reliability. Further, since the softening members 16, 17 are not electrically connected to the outside, it is possible to improve the degree of freedom in designing the softening members 16, 17.

[0090] Further, in the optical device 1, the second torsion bars 7, 8 link the second movable portion 4 and the support portion 2 to each other in a manner that the second movable portion 4 is able to oscillate around the Y axis. Thereby, it is possible to make the second movable portion 4 oscillate around the Y axis together with the first movable portion 3.

[0091] Further, in the optical device 1, the softening members 16, 17 are disposed at positions where the maximum stress acting on the softening members 16, 17 when the first movable portion 3 oscillates around the X axis is 1 / 20 or more of the maximum stress acting on the first torsion bars 5, 6 when the first movable portion 3 oscillates around the X axis. Thereby, it is possible to effectively suppress the influence of the hardening property of the first torsion bars 5, 6 by the softening members 16, 17.

[0092] Further, in the optical device 1, the softening members 16, 17 are disposed at positions where the maximum stress acting on the softening members 16, 17 when the first movable portion 3 oscillates around the X axis is smaller than the yield stress of the softening members 16, 17. Thereby, it is possible to effectively suppress occurrence of an undesirable condition in the softening members 16, 17, and it is possible to further improve reliability.

[0093] Further, in the optical device 1, the pair of softening members 16, 17 are disposed symmetrically with respect to the Y axis (a straight line passing through the center of the first movable portion 3 and perpendicular to the X axis) in plan view. Thereby, it is possible to more effectively suppress the influence of the hardening property of the first torsion bars 5, 6 by the pair of softening members 16, 17. Further, it is possible to make the weight balance uniform.

[0094] Further, in the optical device 1, the softening members 16, 17 are composed of metal. Thereby, it is possible to further effectively suppress the influence of the hardening property of the first torsion bars 5, 6 by the pair of softening members 16, 17.

[0095] Furthermore, in the optical device 1, the softening members 16 and 17 are embedded in the groove 36. Thus, compared to the case where the softening members 16 and 17 are disposed on the surface of the second movable part 4, the softening members 16 and 17, which have a large volume, can be disposed in a small space, and the optical device 1 can be miniaturized.

[0096] Furthermore, the optical device 1 includes coils 14 and 15 as driving elements. Even in such an optical device 1, the effects of the hardening characteristics of the first torsion bars 5 and 6 can be suppressed, and reliability can be ensured.

[0097] Furthermore, unlike the prior art described above, in the optical device 1, at least a portion of the first torsion bars 5 and 6 are located on the X-axis. Therefore, the localized stress other than the torsional stress of the first torsion bars 5 and 6 can be suppressed when the first movable part 3 is rocked, and the adverse conditions of the first torsion bars 5 and 6 can be suppressed.

[0098] The above description illustrates one embodiment of the present invention, but the present invention is not limited to the above embodiment. It can be described as follows: Figure 6 The optical device 1 is constructed as shown in the first variation (a). In the first variation, the main body 3a and the mirror 10 are elliptical in shape. The annular part 3b has a rectangular shape when viewed from above. The second movable part 4 has a rectangular shape when viewed from above. The first torsion bar 5 has a straight part 5a and a widened part 5b connecting the straight part 5a and the first movable part 3. The end of the straight part 5a opposite to the widened part 5b is directly connected to the second movable part 4. The first torsion bar 6 has a straight part 6a and a widened part 6b connecting the straight part 6a and the first movable part 3. The end of the straight part 6a opposite to the widened part 6b is directly connected to the second movable part 4. Each of the second torsion bars 7 and 8 extends linearly along the Y-axis direction.

[0099] Similar to the embodiment described above, the softening members 16 and 17, when viewed from above, are located in the portion 4a of the second movable part 4 extending between the coils 14 and 15 and the first torsion bars 5 and 6. Even in this first variation, as in the embodiment described above, the influence of the hardening characteristics of the first torsion bars 5 and 6 can be suppressed, and reliability can be ensured. Furthermore, in Figure 6 In (a), the structure of the optical device 1 is shown in a simplified manner, for example, omitting wiring 21-24, external terminals 25-28 and wire 29.

[0100] It can also be like Figure 7The optical device 1 is configured as shown in the second modification (b). In the second modification, coil 15 is disposed in the annular portion 3b of the first movable portion 3. The second modification is otherwise the same as the first modification. In the second modification, the mirror 10 can also be rocked around the X and Y axes by utilizing the Lorentz force acting on coils 14 and 15. Even in this second modification, as in the embodiment described above, the influence of the hardening characteristics of the first torsion bars 5 and 6 can be suppressed, and reliability can be ensured.

[0101] It can also be like Figure 7 The optical device 1 is configured as shown in the third variation of (a). In the above embodiment, the first movable part 3 is rocked around each of the X-axis and Y-axis, but in the third variation, the first movable part 3 is rocked only around the X-axis. In the third variation, the second connecting part does not need to be a connecting part that can be twisted and deformed like the second torsion bars 7 and 8, as long as the connecting part of the second movable part 4 and the support part 2 are connected to each other in such a way that the first movable part 3 can be rocked around the X-axis by vibrating the second movable part 4 (so that the second movable part 4 can vibrate at least around the X-axis).

[0102] This design allows for a high degree of freedom in the design of the second connection. For example, the second connection could be designed as follows: Figure 7 As shown in (a), the second connecting part can also be a pair of members 7A and 8A connected to the second movable part 4 and the support part 2 on the Y-axis, located on both sides of the second movable part 4. Alternatively, the second connecting part can be multiple pairs of members connected to the second movable part 4 and the support part 2 at a location on the Y-axis and / or other than the Y-axis. Alternatively, the second connecting part can also be a pair of members connected to the second movable part 4 and the support part 2 on the X-axis, located on both sides of the second movable part 4. In the third variation, the coil 15 is not provided. By inputting a drive signal to the coil 14, the first movable part 3 can be rocked around the X-axis. The third variation is the same as the first variation in other respects. Even in this third variation, the influence of the hardening characteristics of the first torsion bars 5 and 6 can be suppressed, just like in the above embodiment, and reliability can be ensured. Furthermore, the first movable part 3 can be rocked by vibrating the second movable part 4.

[0103] It can also be like Figure 8The optical device 1 is configured as shown in the fourth variation (b). In the fourth variation, the softening members 16 and 17, when viewed from above, are disposed in the portion 3d of the first movable part 3 extending between the mirror 10 and the first torsion bars 5 and 6. In this example, portion 3d corresponds to the portion of the main body 3a that is closer to the outer side than the mirror 10, the annular portion 3b, and a pair of connecting portions 3c. In other words, the softening members 16 and 17 are disposed in the first movable part 3 such that, when viewed from above, they are located closer to the outer side than the mirror 10 and closer to the inner side than the first torsion bars 5 and 6. Specifically, the softening members 16 and 17 are disposed in the portion of the annular portion 3b located on both sides of the main body 3a in the X-axis direction. When viewed from above, the softening members 16 and 17 are located between the mirror 10 and the first torsion bars 5 and 6. The fourth variation is the same as the first variation in other respects.

[0104] In the fourth variation, softening members 16 and 17, having softening properties, are disposed in the portion 3d of the first movable part 3 extending between the mirror surface 10 and the first torsion bars 5 and 6 when viewed from above. This prevents excessive stress from acting on the softening members 16 and 17, and the softening properties of the softening members 16 and 17 offset at least a portion of the hardening properties of the first torsion bars 5 and 6. Therefore, even with the fourth variation, the influence of the hardening properties of the first torsion bars 5 and 6 can be suppressed, just as in the above-described embodiment, and reliability can be ensured.

[0105] It can also be like Figure 8 The optical device 1 is configured as shown in the fourth variation (a). In the fifth variation, the coil 15 is disposed in the annular portion 3b of the first movable portion 3. The softening members 16 and 17, when viewed from above, are disposed in the portion 3d of the first movable portion 3 extending between the mirror 10 and the first torsion bars 5 and 6. Specifically, the softening members 16 and 17, when viewed from above, are disposed in the portion 3e of the first movable portion 3 extending between the coil 15 and the first torsion bars 5 and 6. In this example, portion 3e is the portion of the first movable portion 3 that is closer to the outer side than the coil 15, extending annularly between the coil 15 and the first torsion bars 5 and 6. In other words, the softening members 16 and 17, when viewed from above, are located closer to the outer side than the coil 15 and closer to the inner side than the first torsion bars 5 and 6. The softening members 16 and 17, when viewed from above, are located between the coil 15 and the first torsion bars 5 and 6. The fifth variation is otherwise the same as the fourth variation. In the fifth variation, the mirror 10 can also be shaken around the X and Y axes by using the Lorentz force acting on the coils 14 and 15.

[0106] Even in such a fifth modification, since the softening members 16, 17 are arranged in the first movable portion 3 between the mirror surface 10 and the first torsion bars 5, 6 in plan view, excessive stress can be prevented from acting on the softening members 16, 17, and at least a part of the hardening characteristics of the first torsion bars 5, 6 is canceled by the softening characteristics of the softening members 16, 17. As a result, as in the above-described embodiment, the influence of the hardening characteristics of the first torsion bars 5, 6 can be suppressed, and reliability can be ensured. Further, in the fifth modification, since the softening members 16, 17 are arranged in the first movable portion 3 between the coil 15 and the first torsion bars 5, 6 in plan view, excessive stress can be reliably prevented from acting on the softening members 16, 17, and at least a part of the hardening characteristics of the first torsion bars 5, 6 is effectively canceled by the softening characteristics of the softening members 16, 17.

[0107] The optical device 1 can also be configured as shown in a sixth modification of (b) of the above-described embodiment. In the sixth modification, as in the third modification, only the first movable portion 3 is swung around the X axis. In the sixth modification, the second connecting portion can not be a connecting portion capable of torsional deformation as in the second torsion bars 7, 8, but can be a connecting portion that connects the second movable portion 4 and the support portion 2 to each other in a manner in which the first movable portion 3 is swingable around the X axis by vibrating the second movable portion 4 (in a manner in which the second movable portion 4 is vibratable at least around the X axis). The sixth modification is the same as the fourth modification in other respects. Even with such a fifth modification, as in the above-described embodiment, the influence of the hardening characteristics of the first torsion bars 5, 6 can be suppressed, and reliability can be ensured. Figure 9 The optical device 1 can also be configured as shown in a seventh modification of (a) of the above-described embodiment. The optical device 1 of the seventh modification does not have the second movable portion 4 and the second torsion bars 7, 8. In the seventh modification, the first torsion bars 5, 6 directly connect the first movable portion 3 and the support portion 2 to each other. The coil 14 is not provided, and only the coil 15 is provided to the annular portion 3b of the first movable portion 3. The softening members 16, 17 are arranged in the first movable portion 3 between the coil 15 and the first torsion bars 5, 6 in plan view. The first movable portion 3 is swung only around the X axis by the Lorentz force of the coil 15. The seventh modification is the same as the fourth modification in other respects. Even with such a fifth modification, as in the above-described embodiment, the influence of the hardening characteristics of the first torsion bars 5, 6 can be suppressed, and reliability can be ensured.

[0108] Figure 9

[0109] ​ ​​(b) is a plan view of the optical device 1A involved in the reference example. The optical device 1A of the reference example does not have the second movable portion 4 and the second torsion bars 7, 8. In the reference example, the first torsion bars 5, 6 directly link the first movable portion 3 and the support portion 2 to each other. The coil 14 is not provided, and only the coil 15 is provided to the annular portion 3b of the first movable portion 3. The softening member 16 is disposed in the portion 2a of the support portion 2 extending between the external terminal 27 and the first torsion bar 5, and the softening member 17 is disposed in the portion 2b extending between the external terminal 28 and the first torsion bar 6. In other words, the softening members 16, 17 are disposed to the second movable portion in a manner of being located closer to the inner side than the external terminals 27, 28 provided to the support portion 2 and closer to the outer side than the first torsion bars 5, 6. This is because the external terminals 27, 28 are disposed to positions where stress acting when the first movable portion 3 is rocked around the X axis is smaller, but stress acting on the region closer to the inner side than the external terminals 27, 28 in the support portion 2 when the first movable portion 3 is rocked around the X axis is a prescribed amount or more.

[0110] The softening members 16, 17 are disposed to positions where the maximum stress acting on the softening members 16, 17 when the first movable portion 3 is rocked around the X axis is 1 / 20 or more of the maximum stress acting on the first torsion bars 5, 6 when the first movable portion 3 is rocked around the X axis. The softening members 16, 17 are disposed to positions where the maximum stress acting on the softening members 16, 17 when the first movable portion 3 is rocked around the X axis is smaller than the yield stress of the softening members 16, 17. Further, the softening members 16, 17 are disposed to positions where the maximum stress acting on the softening members 16, 17 when the first movable portion 3 is rocked around the X axis is 1 / 2 or less of the maximum stress acting on the first torsion bars 5, 6 when the first movable portion 3 is rocked around the X axis. The first movable portion 3 is rocked around the X axis only by the Lorentz force of the coil 15. The optical device 1A is the same as the optical device 1 involved in the first modification example in other respects. Even through such a reference example, it is possible to suppress the influence of the hardening characteristics of the first torsion bars 5, 6 and to ensure reliability, as with the above-described embodiment.

[0111] As another modification example, in the above-described embodiment, the first movable portion 3 and the second movable portion 4 are made to linearly act around the Y axis, but the first movable portion 3 and the second movable portion 4 can be made to resonantly act around the Y axis. In the above-described embodiment, a pair of coils 14, 15 is provided to the second movable portion 4, but only one coil can be provided to the second movable portion 4. Even in this case, by inputting a drive signal to the coil, it is possible to make the mirror surface 10 rock around each of the X axis and the Y axis. In the above-described embodiment, the electromotive force monitoring coil for measuring electromotive force can be provided to the second movable portion 4, and the temperature sensor coil for measuring temperature can be provided to the support portion 2.

[0112] In the above-described embodiments, the driving of the mirror surface 10 is performed by electromagnetic force, but the driving of the mirror surface 10 can also be performed by a piezoelectric element. In this case, for example, a piezoelectric film is provided in place of the coils 14, 15 as a driving element. Alternatively, the driving of the mirror surface 10 can also be performed by electrostatic force. In this case, for example, an electrostatic comb is provided in place of the coils 14, 15 as a driving element. Even with these modifications, as with the above-described embodiments, it is possible to suppress the influence of the hardening characteristics of the first torsion bars 5, 6, and it is possible to ensure reliability. For example, the piezoelectric element can also be disposed in the second connecting portions 42A, 42B, the first linear portions 43A, 43B, and the second linear portions 44A, 44B in the second movable portion 4. In this case, the portions of the second movable portion 4 that extend between the piezoelectric element and the first torsion bars 5, 6 are the first connecting portions 41A, 41B, the third linear portions 45A, 45B, and the fourth linear portions 46A, 46B.

[0113] Alternatively, the driving element can also be a magnet. In this case, the mirror surface 10 can be driven by moving the magnet. In this case, the driving element can also not be electrically connected to the outside. In the moving magnet method, for example, a magnetic field generated by a coil provided in the optical device 1 acts on the magnet, thereby causing the movable portion (the first movable portion and / or the second movable portion) provided with the magnet to act, as a result of which the mirror surface 10 is driven. That is, the optical device can be provided with: a support portion; a first movable portion having an optical surface; a frame-shaped second movable portion surrounding the first movable portion; a first linking portion linking the first movable portion and the second movable portion to each other in such a manner that the first movable portion can swing around a first axis; a second linking portion linking the second movable portion and the support portion to each other; a magnet as a driving element provided in the second movable portion; and a softening member having a softening property with respect to stress acting when the first movable portion swings around the first axis, the softening member being disposed in a portion of the second movable portion extending between the driving element and the first linking portion as viewed from a direction perpendicular to the optical surface, and not being electrically connected to the outside. Alternatively, the optical device can be provided with: a support portion; a first movable portion having an optical surface; a frame-shaped second movable portion surrounding the first movable portion; a linear portion extending along the first axis and connected to the first movable portion, a first linking portion linking the first movable portion and the second movable portion to each other in such a manner that the first movable portion can swing around the first axis; a second linking portion linking the second movable portion and the support portion to each other; a magnet as a driving element provided in the second movable portion; and a softening member having a softening property with respect to stress acting when the first movable portion swings around the first axis, the softening member being disposed in a portion of the second movable portion extending between the driving element and the linear portion as viewed from a direction perpendicular to the optical surface, and not being electrically connected to the outside. Alternatively, the optical device can be provided with: a support portion; a first movable portion having an optical surface; a first linking portion linking the first movable portion and the support portion to each other in such a manner that the first movable portion can swing around a first axis; a magnet as a driving element provided in at least one of the support portion and the first movable portion; and a softening member having a softening property with respect to stress acting when the first movable portion swings around the first axis, the softening member being disposed in a portion of the first movable portion extending between the optical surface and the first linking portion as viewed from a direction perpendicular to the optical surface, and not being electrically connected to the outside.Alternatively, the optical device can include a support portion, a first movable portion having an optical surface, a first connecting portion that connects the first movable portion and the support portion to each other in such a manner that the first movable portion can swing around a first axis, a magnet as a driving element provided to at least one of the support portion and the first movable portion, and a softening member having a softening property on which stress acts when the first movable portion swings around the first axis, the softening member being disposed in a portion of the first movable portion that extends between the optical surface and a linear portion connected to the first movable portion, and not being electrically connected to the outside. Alternatively, the optical device can include a support portion, a first movable portion having an optical surface, a first connecting portion that connects the first movable portion and the support portion to each other in such a manner that the first movable portion can swing around a first axis, a magnet as a driving element provided to at least one of the support portion and the first movable portion, and a softening member having a softening property on which stress acts when the first movable portion swings around the first axis, the softening member being disposed in the first movable portion, and not being electrically connected to the outside.

[0114] In the above embodiment, the first torsion bars 5, 6 are defined as "portions up to when a stress acting when the first movable portion 3 is rocked around the X axis is 90% or more of the maximum stress acting on the first torsion bar 5 when the first movable portion 3 is rocked around the X axis". However, in the above embodiment, the first torsion bar 5 is constituted only by the linear portion 5a, and each of the widened portions 5b can be regarded as being included in the first movable portion 3 or the second movable portion 4. Similarly, the first torsion bar 6 is constituted only by the linear portion 6a, and each of the widened portions 6b can be regarded as being included in the first movable portion 3 or the second movable portion 4. In this case, each of the linear portions 5a, 6a is directly connected to the first movable portion 3 and the second movable portion 4. The softening members 16, 17 are arranged in the second movable portion 4 in portions 4a extending between the coils 14, 15 and the linear portions 5a, 6a when viewed from above. In other words, the softening members 16, 17 are provided in the second movable portion 4 in a manner to be located more inward than the coils 14, 15 and more outward than the linear portions 5a, 6a when viewed from above. Even in the first to third modified examples and the reference example, the softening members 16, 17 are arranged in the second movable portion 4 in portions 4a extending between the coils 14, 15 and the linear portions 5a, 6a when viewed from above. In other words, the softening members 16, 17 are located more inward than the coils 14, 15 and more outward than the linear portions 5a, 6a when viewed from above. Further, in the fourth modified example, each of the first torsion bars 5, 6 can have a linear portion directly connected to the first movable portion 3 and a widened portion connected between the linear portion and the second movable portion 4. In this structure, the softening members 16, 17 can also be arranged in the first movable portion 3 in portions extending between the mirror surface 10 and the linear portion when viewed from above. Even in this case, as in the above embodiment, it is possible to suppress the influence of the hardening characteristics of the first torsion bars 5, 6 and to ensure reliability.

[0115] The materials and shapes of the respective structures are not limited to those described above, and various materials and shapes can be employed. For example, the softening member 16 can also be constituted by a resin material. However, since it exhibits significant plastic characteristics and has a high yield stress, the softening member 16 is preferably constituted by copper. The softening member 16 can also have only one dummy wiring portion 16a. The dummy wiring portion 16a can also not have the same configuration as the coils 14, 15, and for example, can be arranged on the surface of the second movable portion 4 and can have a different cross-sectional shape from the coils 14, 15. That is, the softening member 16 is only required to be a member having softening characteristics in which a stress acts when the first movable portion 3 is rocked around the X axis. These points are also the same for the softening member 17.

[0116] The softening members 16, 17 can also be provided on the surface of the second movable portion 4 opposite the surface on which the coils 14, 15 are provided (the surface on the side of the magnetic field generating portion 9). Only one of the pair of softening members 16, 17 can also be provided. A plurality of pairs of softening members can also be provided. For example, in the above embodiment, not only are the softening members 16, 17 provided on the second movable portion 4, but the first movable portion 3 can also be provided with softening members, as in the fourth modification.

[0117] The second movable portion 4 can also have a substantially circular shape, a substantially elliptical shape, a substantially quadrangular shape, or a substantially diamond shape, or the like, in plan view. The annular portion 3b can also not be provided, and the first torsion bars 5, 6 can be directly connected to the main portion 3a. In the above embodiment, the first connecting portion is composed of the plate-like first torsion bars 5, 6, but the shape of the first connecting portion is not limited, and can be any shape, such as a rod shape. The first torsion bars 5, 6 can also have a meandering portion that meanders in plan view. Either or both of the pair of widened portions 5b can also not be provided, and either or both of the pair of widened portions 6b can also not be provided. The second torsion bars 7, 8 can also connect the second movable portion 4 and the support portion 2 to each other at a position other than the Y axis, in such a manner that the second movable portion 4 can be rocked about the Y axis. The first movable portion 3 can also have an optical surface other than the mirror surface 10, and can have, for example, a diffraction lattice surface. In the above embodiment, the pair of coils 14, 15 are arranged so as to be offset from each other, but the coils 14, 15 can also be arranged so that one is inside the other in plan view. Three or more wires 29 can also be connected to each of the external terminals 25 to 28.

[0118] In the above embodiment and modifications, in the case where the softening members 16, 17 do not have a yield stress, the 0.2% proof stress can also be used instead of the yield stress. That is, the softening members 16, 17 can also be arranged at a position at which the maximum stress acting on the softening members 16, 17 when the first movable portion 3 is rocked about the X axis is smaller than the 0.2% proof stress of the softening members 16, 17. In the case where the maximum stress acting on the softening members 16, 17 when the first movable portion 3 is rocked about the X axis is smaller than the 0.2% proof stress or the yield stress of the softening members 16, 17, for example, when the first movable portion 3 is rocked ten thousand times at a normal swing angle (±1 degree or more and ±20 degrees or less) or a resonance frequency, the increase rate of the cross-sectional area of the softening members 16, 17 (the ratio of the cross-sectional area after rocking to the cross-sectional area before rocking) is 10% or less. Alternatively, when the first movable portion 3 is rocked for 1000 hours, the increase rate of the cross-sectional area of the softening members 16, 17 is 10% or less. Furthermore, the yield stress and the 0.2% proof stress can also be measured, for example, according to the method according to JIS Z 2241.

[0119] Explanation of Symbols

[0120] 1 optical device, 2 support portion (fixed portion), 3 first movable portion, 3d portion, 3e portion, 4 second movable portion (support portion), 4a portion, 5, 6 first torsion bar (first link portion), 5a, 6a straight portion, 7, 8 second torsion bar (second link portion), 10 mirror surface (optical surface), 14, 15 coil (driving element), 16, 17 softening member, P center of first movable portion.

Claims

1. An optical device, comprising: a support portion; a first movable portion having an optical surface; a frame-shaped second movable portion surrounding the first movable portion; a first connecting portion connecting the first movable portion and the second movable portion to each other in such a manner that the first movable portion is able to swing around a first axis, and having a hardening characteristic in which a spring constant increases as a twist angle increases; a second connecting portion connecting the second movable portion and the support portion to each other; and a softening member having a softening characteristic for suppressing the hardening characteristic of the first connecting portion, a stress acting when the first movable portion swings around the first axis, the softening member being disposed on the second movable portion in such a manner that a maximum stress acting on the softening member when the first movable portion swings around the first axis is more than 1 / 20 of a maximum stress acting on the first connecting portion when the first movable portion swings around the first axis, and not being electrically connected to the outside.

2. The optical device according to claim 1, further comprising a driving element disposed on the second movable portion and electrically connected to the outside, the softening member being disposed in a portion of the second movable portion extending between the driving element and the first connecting portion when viewed in a direction perpendicular to the optical surface.

3. The optical device according to claim 2, wherein the first connecting portion has a linear portion extending along the first axis and connected to the first movable portion, the softening member being disposed in a portion of the second movable portion extending between the driving element and the linear portion when viewed in a direction perpendicular to the optical surface.

4. The optical device according to any one of claims 1 to 3, wherein the softening member is a member different from the second movable portion.

5. The optical device according to any one of claims 1 to 4, wherein the softening member is disposed on a surface of the second movable portion or in a groove formed in the second movable portion.

6. The optical device according to any one of claims 1 to 5, wherein the softening member extends in a direction intersecting the first axis.

7. An optical device, comprising: a support portion; a first movable portion having an optical surface; a first connecting portion connecting the first movable portion and the support portion to each other in such a manner that the first movable portion is able to swing around a first axis, and having a hardening characteristic in which a spring constant increases as a twist angle increases; and a softening member having a softening characteristic for suppressing the hardening characteristic of the first connecting portion, a stress acting when the first movable portion swings around the first axis, the softening member being disposed on the first movable portion in such a manner that a maximum stress acting on the softening member when the first movable portion swings around the first axis is more than 1 / 20 of a maximum stress acting on the first connecting portion when the first movable portion swings around the first axis, and not being electrically connected to the outside.

8. The optical device according to claim 7, ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The softening member is disposed in a portion of the first movable section that extends between the optical surface and the first connecting section, as viewed from a direction perpendicular to the optical surface.

9. The optical device according to claim 8, wherein The first connecting section has a linear portion extending along a first axis and connected to the first movable section, The softening member is disposed in a portion of the first movable section that extends between the optical surface and the linear portion, as viewed from a direction perpendicular to the optical surface.

10. The optical device according to any one of claims 7 to 9, wherein The softening member is a member different from the first movable section.

11. The optical device according to any one of claims 7 to 10, wherein The softening member is disposed on a surface of the first movable section or in a groove formed in the first movable section.

12. The optical device according to any one of claims 7 to 11, wherein The first movable section has a main body portion in which the optical surface is formed, a ring-shaped portion surrounding the main body portion as viewed from a direction perpendicular to the optical surface and connected to the first connecting section, and a connecting portion interconnecting the main body portion and the ring-shaped portion, The softening member is disposed in the ring-shaped portion.

13. The optical device according to any one of claims 7 to 12, wherein Further comprising a fixed section, The support section is connected to the fixed section in a manner that allows the support section to swing around a second axis that intersects the first axis.

14. The optical device according to any one of claims 1 to 13, wherein The softening member is disposed at a position at which a maximum stress acting on the softening member when the first movable section swings around the first axis is smaller than a 0.2% proof stress or a yield stress of the softening member.

15. The optical device according to any one of claims 1 to 14, wherein The softening member is composed of a metal or a resin material.

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