Mirror device

Abstract

To provide a mirror device capable of suppressing both of deflection of a mirror section and damage to a movable section.SOLUTION: A mirror device has: a base; a frame-like support section; a movable section in which a mirror surface is formed; a first torsion bar for connecting the movable section to the support section such that the movable section can be rocked with a first axis as a center line; and a second torsion bar for connecting the support section to the base such that the support section can be rocked with a second axis as a center line. In the support section, first beam structure is provided. The first beam structure has: a first part that is formed in a part connected to the first torsion bar in the support section and extends in a direction along the second axis; and a second section that is formed in a part connected to the second torsion bar in the support section and extends in a direction along the first axis. The width of the first part in a direction along the first axis is smaller than the width of the second section in a direction along the second axis.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present disclosure relates to a mirror device configured as, for example, a MEMS (Micro Electro Mechanical Systems) device.

Background Art

[0002] As a MEMS device, there is known a mirror device including a support portion, a movable portion provided with a mirror portion, and a pair of torsion bars that connect the movable portion to the support portion so that the movable portion can swing about a predetermined axis as a center line. In such a mirror device, in order to suppress the mirror portion from flexing when the movable portion is swung at high speed (for example, at the resonance frequency level of the movable portion (several kHz to several tens of kHz)), in the movable portion, the mirror portion may be connected to a frame-shaped frame via a pair of connecting portions arranged on the above axis (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the mirror device as described above, since the pair of torsion bars and the pair of connecting portions are arranged on the same axis, when the movable portion is swung at high speed, the stress generated in the pair of connecting portions due to the torsion of the pair of torsion bars increases, and there is a risk that the movable portion breaks at the connecting portion.

[0005] An object of the present disclosure is to provide a mirror device capable of suppressing both the mirror portion from flexing and the movable portion from breaking.

Means for Solving the Problems

[0006] A mirror device relating to one aspect of the present disclosure comprises a support portion, a movable portion, and a pair of torsion bars positioned on both sides of the movable portion on a first axis, connecting the movable portion to the support portion so that the movable portion can swing with the first axis as its centerline. The movable portion has a frame-shaped frame to which the pair of torsion bars are connected, and a mirror portion positioned inside the frame. The mirror portion is connected to the frame in each of a pair of first connection regions located on both sides of the mirror portion in a direction parallel to a second axis perpendicular to the first axis. The area between the mirror portion and the frame, excluding the pair of first connection regions, is empty space. The outer edge of the mirror portion and the inner edge of the frame are connected such that the curvature is continuous in each of the pair of first connection regions when viewed from a direction perpendicular to the first axis and the second axis.

[0007] In this mirror device, a pair of torsion bars connected to a frame-shaped frame are positioned on the first axis, and a pair of first connection regions, to which the mirror portion and the frame-shaped frame are connected, are located on both sides of the mirror portion in a direction parallel to the second axis perpendicular to the first axis. As a result, even if the movable part is oscillated at high speed, the stress generated in each of the pair of first connection regions due to the twisting of the pair of torsion bars is reduced compared to, for example, when only the pair of connection regions are located on the first axis, or when the mirror portion and the frame-shaped frame are connected to each other in only one connection region. Furthermore, in this mirror device, the outer edge of the mirror portion and the inner edge of the frame are connected such that the curvature is continuous in each of the pair of first connection regions when viewed from a direction perpendicular to the first axis and the second axis. As a result, stress concentration is less likely to occur in each of the pair of first connection regions. Thus, this mirror device can suppress both bending of the mirror portion and damage to the movable part.

[0008] A mirror device relating to one aspect of the present disclosure comprises a support portion, a movable portion, and a pair of torsion bars positioned on both sides of the movable portion on a first axis, connecting the movable portion to the support portion so that the movable portion can swing with the first axis as its centerline. The movable portion comprises a frame-shaped frame to which the pair of torsion bars are connected, and a mirror portion positioned inside the frame. The mirror portion is connected to the frame in each of a pair of first connection regions located on both sides of the mirror portion in a direction parallel to a second axis perpendicular to the first axis, and in each of a pair of second connection regions located on both sides of the mirror portion in a direction parallel to the first axis. The area between the mirror portion and the frame, excluding the pair of first connection regions and the pair of second connection regions, is empty space. The outer edge of the mirror portion and the inner edge of the frame are connected such that the curvature is continuous in each of the pair of first connection regions when viewed from a direction perpendicular to the first axis and the second axis.

[0009] In this mirror device, a pair of torsion bars connected to a frame-shaped frame are positioned on the first axis, and a pair of first connection regions, to which the mirror and the frame-shaped frame are connected, are located on both sides of the mirror in a direction parallel to the second axis perpendicular to the first axis. Furthermore, a pair of second connection regions, to which the mirror and the frame-shaped frame are connected, are located on both sides of the mirror in a direction parallel to the first axis. As a result, even if the movable part is oscillated at high speed, the stress generated in each of the pair of first connection regions and each of the pair of second connection regions due to the twisting of the pair of torsion bars is reduced compared to, for example, when only the pair of connection regions are located on the first axis, or when the mirror and the frame-shaped frame are connected in only one connection region. Furthermore, in this mirror device, the outer edge of the mirror and the inner edge of the frame are connected such that the curvature is continuous in each of the pair of first connection regions when viewed from a direction perpendicular to the first axis and the second axis. As a result, stress concentration is less likely to occur in each of the pair of first connection regions. As described above, this mirror device can suppress both bending of the mirror portion and damage to the movable portion.

[0010] In one aspect of the mirror device of this disclosure, the outer edge of the mirror portion and the inner edge of the frame may be connected such that the curvature is continuous in each of the pair of second connection regions when viewed from a direction perpendicular to the first axis and the second axis. This makes it less likely for stress concentration to occur in each of the pair of second connection regions.

[0011] In one aspect of the mirror device of this disclosure, the pair of second connection regions may be located on both sides of the mirror portion on the first axis. This makes it possible to reduce the moment of inertia of the movable part around the first axis.

[0012] In one aspect of the mirror device of this disclosure, the pair of first connection regions may be located on both sides of the mirror portion on the second axis. This ensures a sufficient distance (a distance at which the torsional effect of the pair of torsion bars does not easily affect each of the pair of first connection regions) between each of the pair of torsion bars. Therefore, it is possible to simplify the configuration of the movable part while suppressing both bending of the mirror portion and damage to the movable part.

[0013] In one aspect of the mirror device of this disclosure, the frame includes a pair of first parts to which the mirror portion is connected and which extend in a direction parallel to a first axis, wherein the width of each of the pair of first parts in a direction parallel to a second axis may decrease as it moves away from each of the pair of first connection regions. This allows the stress generated due to the twisting of the pair of torsion bars to be distributed to the narrower portion of each of the pair of first parts, thereby reducing the stress generated in each of the pair of first connection regions. Furthermore, while ensuring the connection strength in each of the pair of first connection regions, the moment of inertia of the movable part can be reduced by the amount by which the width of each of the pair of first parts is reduced. Reducing the moment of inertia of the movable part is advantageous for swinging the movable part at high speed.

[0014] In one aspect of the mirror device of this disclosure, the frame may further include a pair of second portions to which a pair of torsion bars are connected and which extend in a direction parallel to a second axis. This distributes the stress caused by the twisting of the pair of torsion bars to the portion between the first and second portions that are connected or joined to each other, thereby reducing the stress generated in each of the pair of first connection regions.

[0015] In one aspect of the mirror device of this disclosure, the inner edges of each of the pair of first parts and the inner edges of each of the pair of second parts may be connected to each other such that the curvature is continuous in each of the multiple regions where they are connected when viewed from a direction perpendicular to the first and second axes. This makes it possible to suppress stress concentration in each of the multiple regions where the inner edges of the first parts and the inner edges of the second parts are connected to each other.

[0016] In one aspect of the mirror device of this disclosure, the outer edges of each of the pair of first parts and the outer edges of each of the pair of second parts may be connected to each other such that the curvature is continuous in each of the multiple regions to which they are connected when viewed from a direction perpendicular to the first and second axes. This makes it possible to suppress stress concentration in each of the multiple regions to which the outer edges of the first parts and the outer edges of the second parts are connected to each other.

[0017] In one aspect of the mirror device of this disclosure, the length of each of the pair of first parts in the direction parallel to the first axis may be longer than the length of each of the pair of second parts in the direction parallel to the second axis. This makes it possible to ensure a sufficient distance (a distance at which the torsional effect of the pair of torsion bars does not easily affect each of the pair of first connection regions) between each of the pair of torsion bars and each of the pair of first connection regions, while suppressing an increase in the moment of inertia of the movable part.

[0018] In the mirror device according to one aspect of the present disclosure, the distance between each of the pair of first connection regions and one of the pair of second portions, and the distance between each of the pair of first connection regions and the other of the pair of second portions may be longer than the distance between the first axis and each of the pair of first portions. Thereby, while suppressing an increase in the moment of inertia of the movable part, a sufficient distance (a distance at which it is difficult for the torsional influence of the pair of torsion bars to reach each of the pair of first connection regions) can be secured between each of the pair of torsion bars and each of the pair of first connection regions.

[0019] In the mirror device according to one aspect of the present disclosure, the shape of the mirror part when viewed from a direction perpendicular to the first axis and the second axis may be an ellipse having a major axis along the first axis. Thereby, while suppressing an increase in the moment of inertia of the movable part, a sufficient area of the mirror surface can be secured.

[0020] In the mirror device according to one aspect of the present disclosure, the width of each of the pair of first connection regions in a direction parallel to the first axis may be 30% or less of the width of the mirror part in a direction parallel to the first axis. Thereby, it is possible to achieve both ensuring sufficient connection strength between the mirror part and the frame and ensuring a sufficient distance between each of the pair of torsion bars and each of the pair of first connection regions.

Advantages of the Invention

[0021] According to the present disclosure, it is possible to provide a mirror device that can suppress both bending of the mirror part and breakage of the movable part.

Brief Description of the Drawings

[0022] [Figure 1] FIG. 1 is a plan view of a mirror device according to an embodiment. [Figure 2] FIG. 2 is a plan view of the movable part of the mirror device shown in FIG. 1. [Figure 3] FIG. 3 is a plan view of the torsion bar of the mirror device shown in FIG. 1. [Figure 4]FIG. 4 is a bottom view of the main part of the mirror device shown in FIG. 1. [Figure 5] (a) of FIG. 5 is a plan view of the movable part of the comparative example. (b) of FIG. 5 is a plan view of the movable part of the embodiment. [Figure 6] (a) of FIG. 6 is a plan view of the movable part of the comparative example. (b) of FIG. 6 is a plan view of the movable part of the embodiment. [Figure 7] (a) of FIG. 7 is a plan view of the movable part of the first modification. (b) of FIG. 7 is a plan view of the movable part of the second modification. [Figure 8] FIG. 8 is a plan view of the movable part of the third modification.

Mode for Carrying Out the Invention

[0023] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In each figure, the same or corresponding parts are denoted by the same reference numerals, and overlapping descriptions are omitted. [Configuration of Mirror Device]

[0024] As shown in FIG. 1, the mirror device 1 includes a base 2, a support portion 3, a movable portion 4, a pair of torsion bars 5 and 6, a pair of torsion bars 7 and 8, and a magnetic field generation portion 10. The base 2, the support portion 3, the movable portion 4, the pair of torsion bars 5 and 6, and the pair of torsion bars and 8 are integrally formed by an SOI (Silicon on Insulator) substrate. That is, the mirror device 1 is configured as a MEMS device. The magnetic field generation portion 10 is configured by, for example, a permanent magnet having a Halbach array. In the mirror device , the movable portion 4 provided with the mirror portion 41 is swung about each of the X-axis (first axis) and the Y-axis (second axis perpendicular to the first axis) that are orthogonal to each other as the center lines. The mirror device 1 is used, for example, in an optical switch for optical communication, an optical scanner, or the like.

[0025] Base 2 has an outer shape, for example, a square shape when viewed from a direction perpendicular to the X and Y axes, and is formed in a frame shape. Base 2 is located on one side of the magnetic field generating unit 10. Support unit 3 has an outer shape, for example, an octagon shape when viewed from a direction perpendicular to the X and Y axes, and is formed in a frame shape. Support unit 3 is located inside Base 2, spaced apart from the magnetic field generating unit 10. Movable unit 4 has an outer shape, for example, a square shape when viewed from a direction perpendicular to the X and Y axes. Movable unit 4 is located inside Support unit 3, spaced apart from the magnetic field generating unit 10.

[0026] A pair of torsion bars 5 and 6 are positioned on both sides of the support section 3 on the Y-axis. The pair of torsion bars 5 and 6 connect the support section 3 to the base 2 so that the support section 3 can swing around the Y-axis as its centerline. Each torsion bar 5 and 6 extends in a meandering manner to improve strength and facilitate adjustment of the torsional spring constant. A pair of torsion bars 7 and 8 are positioned on both sides of the movable section 4 on the X-axis. The pair of torsion bars 7 and 8 connect the movable section 4 to the support section 3 so that the movable section 4 can swing around the X-axis as its centerline. Each torsion bar 7 and 8 extends linearly along the X-axis.

[0027] The mirror device 1 further comprises a coil 9, a coil 11, a plurality of wires 12, 13, 14, 15, and a plurality of electrode pads 16, 17, 18, 19. Coil 9 is provided on the support part 3. Coil 9 extends in a spiral shape, for example, while embedded in the support part 3. Coil 11 is provided on the movable part 4. Coil 9 extends in a spiral shape, for example, while embedded in the movable part 4. Each coil 9 and 11 is made of a metal material such as copper. In the drawing, the areas where each coil 9 and 11 is located are indicated by hatching.

[0028] Multiple electrode pads 16, 17, 18, and 19 are provided on the base 2. Each electrode pad 16, 17, 18, and 19 is exposed to the outside from the insulating layer 21 on the base 2. The insulating layer 21 is integrally formed to cover the surface (the surface opposite to the magnetic field generating part 10) of the base 2, the support part 3, the movable part 4, the pair of torsion bars 5 and 6, and the pair of torsion bars 7 and 8. The insulating layer 21 is made of, for example, a silicon dioxide film, a silicon nitride film, or the like.

[0029] Wiring 12 electrically connects one end of coil 9 to electrode pad 16. Wiring 12 extends from one end of coil 9 to electrode pad 16 via torsion bar 5 while embedded in insulating layer 21. Wiring 13 electrically connects the other end of coil 9 to electrode pad 17. Wiring 13 extends from the other end of coil 9 to electrode pad 17 via torsion bar 6 while embedded in insulating layer 21. Each wire 12, 13 is made of a metal material such as aluminum.

[0030] Wiring 14 electrically connects one end of coil 11 to electrode pad 18. Wiring 14 is embedded in the insulating layer 21 and extends from one end of coil 11 to electrode pad 18 via torsion bar 7, part of support 3, and torsion bar 5. Wiring 15 electrically connects the other end of coil 11 to electrode pad 19. Wiring 15 is embedded in the insulating layer 21 and extends from the other end of coil 11 to electrode pad 19 via torsion bar 8, part of support 3, and torsion bar 6. The portions of each wiring 14 and 15 that pass through each torsion bar 7 and 8 are made of a metal material such as tungsten, while the other portions are made of a metal material such as aluminum. As will be described later, the pair of torsion bars 7 and 8 experience twisting due to the resonance of the movable part 4 at its natural frequency, so a greater load is applied to the portions of each wiring 14 and 15 that pass through each torsion bar 7 and 8 than to the other portions. However, in the mirror device 1, the portion of each wiring 14 and 15 that passes through each torsion bar 7 and 8 is made of a metal material with a higher Vickers hardness than the other portions, thus preventing metal fatigue from occurring in the wiring 14 and 15 on each torsion bar 7 and 8. In the drawing, the portion of each wiring 14 and 15 that passes through each torsion bar 7 and 8 is indicated by hatching.

[0031] In the mirror device 1 configured as described above, when a drive signal for linear operation is input to the coil 9 via the electrode pads 16, 17 and wiring 12, 13, a Lorentz force acts on the coil 9 due to its interaction with the magnetic field generated by the magnetic field generator 10. By utilizing the balance between this Lorentz force and the elastic force of the pair of torsion bars 5, 6, the mirror section 41 can be made to move linearly together with the support section 3 with the Y-axis as the centerline. On the other hand, when a drive signal for resonant operation is input to the coil 11 via the electrode pads 18, 19 and wiring 14, 15, a Lorentz force acts on the coil 11 due to its interaction with the magnetic field generated by the magnetic field generator 10. In addition to this Lorentz force, by utilizing the resonance of the movable section 4 at its natural frequency, the mirror section 41 can be made to move resonantly with the X-axis as the centerline. The natural frequency is determined by the moment of inertia of the movable section 4, the torsional spring constants of the pair of torsion bars 7, 8, etc. [Structure of each part]

[0032] As shown in Figure 2, the movable part 4 has a frame-shaped frame 42 in addition to the mirror part 41. A pair of torsion bars 7 and 8 are connected to the frame 42. The mirror part 41 is located inside the frame 42. The mirror part 41 is connected to the frame 42 in each of a pair of connection regions (first connection regions) 40a and 40b located on both sides of the mirror part 41 in a direction parallel to the Y-axis (hereinafter referred to as the "Y-axis direction"). More specifically, the mirror part 41 is connected to the frame 42 in each of a pair of connection regions 40a and 40b located on both sides of the mirror part 41 on the Y-axis. The area between the mirror part 41 and the frame 42 other than the pair of connection regions 40a and 40b is empty space. In other words, the mirror part 41 and the frame 42 are connected to each other only in the pair of connection regions 40a and 40b. The width (minimum width) W2 of each connection region 40a, 40b in the direction parallel to the X-axis (hereinafter referred to as the "X-axis direction") is 30% or less of the width (maximum width) W1 of the mirror portion 41 in the X-axis direction.

[0033] When viewed from a direction perpendicular to the X and Y axes, the shape of the mirror portion 41 is an ellipse centered at the intersection O of the X and Y axes, with a major axis along the X axis and a minor axis along the Y axis. A mirror surface 41a is formed on the surface of the mirror portion 41 (the surface opposite to the magnetic field generating portion 10) by a metal film made of, for example, aluminum.

[0034] The frame 42 has an outer shape, for example, a rectangular shape when viewed from a direction perpendicular to the X and Y axes, and is formed in a frame shape. More specifically, the frame 42 is formed in a frame shape by a pair of first parts 43, 44 extending in the X-axis direction and a pair of second parts 45, 46 extending in the Y-axis direction. The length of each first part 43, 44 in the X-axis direction is longer than the length of each second part 45, 46 in the Y-axis direction. Note that the length of each first part 43, 44 in the X-axis direction can be considered as the length of the outer or inner edge of each first part 43, 44 when viewed from a direction perpendicular to the X and Y axes. The length of each second part 45, 46 in the Y-axis direction can be considered as the length of the outer or inner edge of each second part 45, 46 when viewed from a direction perpendicular to the X and Y axes.

[0035] The distances between connection region 40a and second part 45, connection region 40a and second part 46, connection region 40b and second part 45, and connection region 40b and second part 46 are all longer than the distance between the X-axis and first part 43, and the distance between the X-axis and first part 44. The distance between connection region 40a and second part 45 can be considered as the distance (maximum distance) from the outer edge of connection region 40a on the second part 45 side to the inner edge of second part 45 along the X-axis. The distance between connection region 40a and second part 46 can be considered as the distance (maximum distance) from the outer edge of connection region 40a on the second part 46 side to the inner edge of second part 46 along the X-axis. The distance between connection region 40b and second part 45 can be considered as the distance (maximum distance) from the outer edge of connection region 40b on the second part 45 side to the inner edge of second part 45 along the X-axis. The distance between the connection region 40b and the second part 46 can be considered as the distance (maximum distance) from the outer edge of the connection region 40b on the side of the second part 46 to the inner edge of the second part 46, along the X-axis. The distance between the X-axis and the first part 43 can be considered as the distance (maximum distance) from the X-axis to the inner edge of the first part 43, along the Y-axis. The distance between the X-axis and the first part 44 can be considered as the distance (maximum distance) from the X-axis to the inner edge of the first part 44, along the Y-axis.

[0036] The mirror portion 41 is connected to the inner (mirror portion 41 side) side 43a of the first portion 43 and the inner (mirror portion 41 side) side 44a of the first portion 44. The torsion bar 7 is connected to the outer (opposite side of the mirror portion 41) side 45b of the second portion 45. The torsion bar 8 is connected to the outer (opposite side of the mirror portion 41) side 46b of the second portion 46.

[0037] The side surface 41b of the mirror section 41 and the inner side surface 43a of the first section 43 are connected such that the curvature is continuous in the connection region 40a. The side surface 41b of the mirror section 41 and the inner side surface 44a of the first section 44 are connected such that the curvature is continuous in the connection region 40b. In other words, the outer edge of the mirror section 41 and the inner edge of the frame 42 are connected such that the curvature is continuous in each connection region 40a and 40b when viewed from a direction perpendicular to the X and Y axes. Note that "connected so that the curvature is continuous" means that there are no points where the curvature is discontinuous (for example, the vertices of sharp corners (including acute, right, and obtuse angles)). Therefore, if there are no points where the curvature is discontinuous, the outer edge of the mirror section 41 and the inner edge of the frame 42 may include straight sections in each connection region 40a and 40b (the curvature value of the straight sections can be considered as 0).

[0038] The width of the first portion 43 in the Y-axis direction decreases as it approaches the torsion bar 7 along the X-axis direction from the connection region 40a, and also as it approaches the torsion bar 8 along the X-axis direction from the connection region 40a. In other words, the width of the first portion 43 in the Y-axis direction decreases as it moves away from the connection region 40a. Here, the outer side surface 43b of the first portion 43 (opposite the mirror portion 41) is a flat surface parallel to the X-axis, and the inner side surface 43a of the first portion 43 is a curved surface that curves concavely on the opposite side of the mirror portion 41, so that it approaches the side surface 43b as it moves away from the connection region 40a. The width of the first portion 44 in the Y-axis direction decreases as it approaches the torsion bar 7 along the X-axis direction from the connection region 40b, and also as it approaches the torsion bar 8 along the X-axis direction from the connection region 40b. In other words, the width of the first portion 44 in the Y-axis direction decreases as it moves away from the connection region 40b. Here, the outer side surface 44b of the first part 44 (opposite to the mirror part 41) is a flat surface parallel to the X-axis, while the inner side surface 44a of the first part 44 is a curved surface that curves concavely on the opposite side to the mirror part 41, as it moves away from the connection region 40b and approaches the side surface 44b.

[0039] The inner side surface 43a of the first part 43 and the inner side surface 45a (mirror section 41 side) of the second part 45 are connected such that, when viewed from a direction perpendicular to the X and Y axes, the curvature is continuous in the regions where they are connected. The inner side surface 43a of the first part 43 and the inner side surface 46a (mirror section 41 side) of the second part 46 are connected such that, when viewed from a direction perpendicular to the X and Y axes, the curvature is continuous in the regions where they are connected. The inner side surface 44a of the first part 44 and the inner side surface 45a of the second part 45 are connected such that, when viewed from a direction perpendicular to the X and Y axes, the curvature is continuous in the regions where they are connected. The inner side surface 44a of the first part 44 and the inner side surface 46a of the second part 46 are connected such that, when viewed from a direction perpendicular to the X and Y axes, the curvature is continuous in the regions where they are connected. In other words, the inner edges of each first section 43, 44 and the inner edges of each second section 45, 46 are connected to each other such that the curvature is continuous in each connected region when viewed from a direction perpendicular to the X and Y axes.

[0040] The outer side surface 43b of the first part 43 and the outer side surface 45b of the second part 45 are connected such that the curvature is continuous in the regions where they are connected when viewed from a direction perpendicular to the X and Y axes. The outer side surface 43b of the first part 43 and the outer side surface 46b of the second part 46 are connected such that the curvature is continuous in the regions where they are connected when viewed from a direction perpendicular to the X and Y axes. The outer side surface 44b of the first part 44 and the outer side surface 45b of the second part 45 are connected such that the curvature is continuous in the regions where they are connected when viewed from a direction perpendicular to the X and Y axes. The outer side surface 44b of the first part 44 and the outer side surface 46b of the second part 46 are connected such that the curvature is continuous in the regions where they are connected when viewed from a direction perpendicular to the X and Y axes. In other words, the outer edges of each first section 43, 44 and the outer edges of each second section 45, 46 are connected to each other such that the curvature is continuous in each connected region when viewed from a direction perpendicular to the X and Y axes.

[0041] The second portion 45 has a slit 45c that extends in the Y-axis direction. The slit 45c is located between the torsion bar 7 and the mirror portion 41 when viewed from a direction perpendicular to the X and Y axes. The second portion 46 has a slit 46c that extends in the Y-axis direction. The slit 46c is located between the torsion bar 8 and the mirror portion 41 when viewed from a direction perpendicular to the X and Y axes.

[0042] The coil 11 extends along the outer sides 43b and 44b in each of the first parts 43 and 44. In the first part 43, the center position of the region where the coil 11 extends (the center position of the width in the Y-axis direction) is located outside (on the opposite side from the connection region 40a) of the center position of the first part 43 (the center position of the width in the Y-axis direction). In the first part 44, the center position of the region where the coil 11 extends (the center position of the width in the Y-axis direction) is located outside (on the opposite side from the connection region 40b) of the center position of the first part 44 (the center position of the width in the Y-axis direction).

[0043] The coil 11 extends along the inner sides 45a and 46a in each of the second sections 45 and 46. In the second section 45, the center of the region where the coil 11 extends (the center of the width in the X-axis direction) is located inside the center of the second section 45 (the center of the width in the X-axis direction) (on the opposite side from the torsion bar 7) (here, it is located inside the slit 45c). In the second section 46, the center of the region where the coil 11 extends (the center of the width in the X-axis direction) is located inside the center of the second section 46 (the center of the width in the X-axis direction) (on the opposite side from the torsion bar 8) (here, it is located inside the slit 46c).

[0044] As shown in Figure 3, both sides 7a of the torsion bar 7 and the outer side 45b of the second part 45 are connected to each other such that the curvature is continuous in each region when viewed from a direction perpendicular to the X and Y axes. In other words, the outer edge of the torsion bar 7 and the outer edge of the second part 45 are connected to each other such that the curvature is continuous in each region when viewed from a direction perpendicular to the X and Y axes. Both sides 7a of the torsion bar 7 and the inner (mirror part 41 side) side 3a of the support part 3 are connected to each other such that the curvature is continuous in each region when viewed from a direction perpendicular to the X and Y axes. In other words, the outer edge of the torsion bar 7 and the inner edge of the support part 3 are connected to each other such that the curvature is continuous in each region when viewed from a direction perpendicular to the X and Y axes. The curvature of the outer edge of the torsion bar 7 in the region connected to the outer edge of the second part 45 is smaller than the curvature of the outer edge of the torsion bar 7 in the region connected to the inner edge of the support part 3.

[0045] Similarly, both sides of the torsion bar 8 and the outer side 46b of the second part 46 are connected to each other such that the curvature is continuous in each region they connect to when viewed from a direction perpendicular to the X and Y axes (see Figures 1 and 2). In other words, the outer edge of the torsion bar 8 and the outer edge of the second part 46 are connected to each other such that the curvature is continuous in each region they connect to when viewed from a direction perpendicular to the X and Y axes. Both sides of the torsion bar 8 and the inner side 3a of the support part 3 are connected to each other such that the curvature is continuous in each region they connect to when viewed from a direction perpendicular to the X and Y axes (see Figures 1 and 2). In other words, the outer edge of the torsion bar 8 and the inner edge of the support part 3 are connected to each other such that the curvature is continuous in each region they connect to when viewed from a direction perpendicular to the X and Y axes. The curvature of the outer edge of the torsion bar 8 in the region connected to the outer edge of the second part 46 is smaller than the curvature of the outer edge of the torsion bar 8 in the region connected to the inner edge of the support part 3 (see Figures 1 and 2).

[0046] As shown in Figure 3, the coil 9 extends along the outer side surface 3b of the support portion 3 (opposite to the mirror portion 41). In the portion of the support portion 3 to which the torsion bar 7 is connected, the center position of the region where the coil 9 extends (center position of width in the X-axis direction) is located outside (opposite to the torsion bar 7) of the center position of that portion (center position of width in the X-axis direction). In the portion of the support portion 3 to which the torsion bar 8 is connected, the center position of the region where the coil 9 extends (center position of width in the X-axis direction) is located outside (opposite to the torsion bar 8) of the center position of that portion (center position of width in the X-axis direction) (see Figures 1 and 2).

[0047] As shown in Figure 4, a beam structure 31 is provided on the back surface of the support portion 3 (the surface facing the magnetic field generating portion 10). When viewed from directions perpendicular to the X and Y axes, the beam structure 31 extends in an annular shape along the frame-shaped support portion 3. The width of the portion of the beam structure 31 extending in the Y-axis direction (width in the X-axis direction) is smaller than the width of the portion of the beam structure 31 extending in the X-axis direction (width in the Y-axis direction). In the portion of the beam structure 31 extending in the X-axis direction, multiple weight-reducing cutouts 31a are formed, except for the intermediate portion that crosses the Y-axis. The size of each weight-reducing cutout 31a increases as it moves away from the Y-axis.

[0048] On the torsion bar 7 side of the beam structure 31, the center position of the portion extending in the Y-axis direction (the center position of the width in the X-axis direction) is located outside (on the opposite side from the torsion bar 7) of the center position of the portion of the support 3 that extends in the Y-axis direction and to which the torsion bar 7 is connected (the center position of the width in the X-axis direction). On the torsion bar 8 side of the beam structure 31, the center position of the portion extending in the Y-axis direction (the center position of the width in the X-axis direction) is located outside (on the opposite side from the torsion bar 8) of the center position of the portion of the support 3 that extends in the Y-axis direction and to which the torsion bar 8 is connected (the center position of the width in the X-axis direction).

[0049] Multiple beam structures 47, 48, and 49 are provided on the back surface of the mirror section 41 (the surface facing the magnetic field generating section 10). When viewed from a direction perpendicular to the X and Y axes, beam structure 47 extends in a V-shape from intersection O toward both edges of the connection region 40a in the X-axis direction. When viewed from a direction perpendicular to the X and Y axes, beam structure 48 extends in a V-shape from intersection O toward both edges of the connection region 40b in the X-axis direction. When viewed from a direction perpendicular to the X and Y axes, beam structure 49 extends in an X-shape on both sides in the X-axis direction from intersection O. [Mechanism of Action and Effects]

[0050] In the mirror device 1, a pair of torsion bars 7 and 8 connected to a frame-shaped frame 42 are positioned on the X-axis, and a pair of connection regions 40a and 40b, to which the mirror portion 41 and the frame-shaped frame 42 are connected, are located on both sides of the mirror portion 41 in the Y-axis direction. As a result, even if the movable portion 4 is oscillated at high speed with the X-axis as its centerline, the stress generated in each connection region 40a and 40b due to the twisting of the pair of torsion bars 7 and 8 is reduced compared to cases where, for example, only the pair of connection regions 40a and 40b are located on the X-axis, or where the mirror portion 41 and the frame-shaped frame 42 are connected to each other in only one connection region 40a (or 40b). Furthermore, in the mirror device 1, the outer edge of the mirror portion 41 and the inner edge of the frame 42 are connected such that the curvature is continuous in each connection region 40a and 40b when viewed from a direction perpendicular to the X-axis and Y-axis. As a result, stress concentration is less likely to occur in each connection region 40a and 40b. As described above, the mirror device 1 can suppress both bending of the mirror portion 41 and damage to the movable portion 4.

[0051] In the mirror device 1, a pair of connection regions 40a and 40b are located on both sides of the mirror portion 41 on the Y axis. This ensures a sufficient distance (a distance at which the twisting effect of the pair of torsion bars 7 and 8 does not easily affect the connection regions 40a and 40b) between each torsion bar 7 and 8. Therefore, while simplifying the configuration of the movable portion 4, it is possible to suppress both bending of the mirror portion 41 and damage to the movable portion 4.

[0052] In the mirror device 1, the frame 42 includes a pair of first parts 43 and 44 to which the mirror part 41 is connected and which extend in the X-axis direction, and the width of each first part 43 and 44 in the Y-axis direction decreases as it moves away from each connection region 40a and 40b. This distributes the stress generated due to the twisting of the pair of torsion bars 7 and 8 to the parts of each first part 43 and 44 where the width is reduced, thereby reducing the stress generated in each connection region 40a and 40b. Furthermore, while ensuring the connection strength in each connection region 40a and 40b, the moment of inertia of the movable part 4 when the X-axis is the axis of rotation can be reduced by the amount by which the width of each first part 43 and 44 is reduced. Reducing the moment of inertia of the movable part 4 when the X-axis is the axis of rotation is advantageous when the movable part 4 is oscillated at high speed with the X-axis as the centerline. In particular, the inner side surface 43a of the first part 43 is a curved surface that curves concavely toward the opposite side of the mirror portion 41 so that it moves closer to the outer side surface 43b of the first part 43 as it moves away from the connection region 40a, and the inner side surface 44a of the first part 44 is a curved surface that curves concavely toward the opposite side of the mirror portion 41 so that it moves closer to the outer side surface 44b of the first part 44 as it moves away from the connection region 40b. As a result, the stress generated due to the twisting of the pair of torsion bars 7 and 8 can be distributed more reliably, and stress concentration in each of the first parts 43 and 44 can be suppressed.

[0053] Figure 5(a) is a plan view of the movable part 4 of the comparative example, and Figure 5(b) is a plan view of the movable part 4 of the embodiment (the movable part 4 described above). Figure 6(a) is a plan view of the movable part 4 of the comparative example, and Figure 6(b) is a plan view of the movable part 4 of the embodiment. In the movable part 4 of the comparative example shown in Figure 5(a), the width of each first part 43, 44 in the Y-axis direction is constant, and the width of the movable part 4 in the Y-axis direction is equal to the width of the movable part 4 of the embodiment shown in Figure 5(b). In the movable part 4 of the comparative example shown in Figure 6(a), the width of each first part 43, 44 in the Y-axis direction is constant, and the width of the movable part 4 in the Y-axis direction is smaller than the width of the movable part 4 of the embodiment shown in Figure 6(b).

[0054] Comparing the movable part 4 of the comparative example shown in Figure 5(a) with the movable part 4 of the comparative example shown in Figure 6(a), the moment of inertia of the movable part 4 of the comparative example shown in Figure 5(a) is large when the X-axis is the axis of rotation, and the stress generated due to the twisting of the pair of torsion bars 7 and 8 cannot be fully relieved in the movable part 4 of the comparative example shown in Figure 6(a). In contrast, the movable part 4 of the embodiment shown in Figure 5(b) and Figure 6(b) can reduce the moment of inertia of the movable part 4 when the X-axis is the axis of rotation compared to the movable part 4 of the comparative example shown in Figure 5(a). Furthermore, the movable part 4 of the embodiment shown in Figure 5(b) and Figure 6(b) can relieve the stress generated due to the twisting of the pair of torsion bars 7 and 8 compared to the movable part 4 of the comparative example shown in Figure 6(a).

[0055] In the mirror device 1, the frame 42 includes a pair of first parts 43, 44, as well as a pair of second parts 45, 46 to which a pair of torsion bars 7, 8 are connected and which extend in the Y-axis direction. This allows the stress generated due to the twisting of the pair of torsion bars 7, 8 to be distributed to the parts between the connected first parts 43, 44 and the connected second parts 45, 46, thereby reducing the stress generated in each connection region 40a, 40b.

[0056] In the mirror device 1, the inner edges of each first portion 43, 44 and the inner edges of each second portion 45, 46 are connected to each other such that the curvature is continuous in each region where they are connected, when viewed from a direction perpendicular to the X and Y axes. This makes it possible to suppress stress concentration in each region where the inner edges of each first portion 43, 44 and the inner edges of each second portion 45, 46 are connected to each other.

[0057] In the mirror device 1, the outer edges of each first part 43, 44 and the outer edges of each second part 45, 46 are connected to each other such that the curvature is continuous in each region where they are connected, when viewed from a direction perpendicular to the X and Y axes. This makes it possible to suppress stress concentration in each region where the outer edges of each first part 43, 44 and the outer edges of each second part 45, 46 are connected to each other.

[0058] In the mirror device 1, the lengths of the first parts 43 and 44 in the X-axis direction are longer than the lengths of the second parts 45 and 46 in the Y-axis direction. This allows for sufficient distance (a distance at which the twisting effect of the pair of torsion bars 7 and 8 does not easily affect the connection regions 40a and 40b) between each torsion bar 7 and 8 and each connection region 40a and 40b, while suppressing the increase in the moment of inertia of the movable part 4 when the X-axis is the axis of rotation.

[0059] In the mirror device 1, the distance between the connection region 40a and the second part 45, the distance between the connection region 40a and the second part 46, the distance between the connection region 40b and the second part 45, and the distance between the connection region 40b and the second part 46 are all longer than the distance between the X-axis and the first part 43, and the distance between the X-axis and the first part 44. This makes it possible to ensure a sufficient distance (a distance at which the torsional effect of the pair of torsion bars 7 and 8 does not easily affect the connection regions 40a and 40b) between each torsion bar 7 and 8 and each connection region 40a and 40b, while suppressing the increase in the moment of inertia of the movable part 4 when the X-axis is the axis of rotation.

[0060] In the mirror device 1, the shape of the mirror portion 41 when viewed from a direction perpendicular to the X and Y axes is an ellipse with a major axis along the X axis. This makes it possible to secure a sufficient area of ​​the mirror surface 41a while suppressing the increase in the moment of inertia of the movable portion 4 when the X axis is the axis of rotation.

[0061] In the mirror device 1, the width of each connection region 40a, 40b in the X-axis direction is 30% or less of the width of the mirror section 41 in the X-axis direction. This ensures both sufficient connection strength between the mirror section 41 and the frame 42, and sufficient distance between each torsion bar 7, 8 and each connection region 40a, 40b.

[0062] In the mirror device 1, the coil 11 extends along the outer sides 43b and 44b in each first section 43 and 44, and along the inner sides 45a and 46a in each second section 45 and 46. As a result, the coil 11 is separated from each connection region 40a and 40b and each torsion bar 7 and 8, thereby reducing the stress generated in the coil 11 due to the twisting of the pair of torsion bars 7 and 8. Therefore, metal fatigue in the coil 11 can be suppressed. As described above, in each connection region 40a and 40b, the stress is reduced to an extent that does not lead to deflection of the mirror section 41 and damage to the movable part 4, but there is a risk that stress sufficient to lead to metal fatigue in the coil 11 may remain. For this reason, extending the coil 11 along the outer sides 43b and 44b in each first section 43 and 44, and separating the coil 11 from each connection region 40a and 40b, is effective from a safety standpoint.

[0063] In the mirror device 1, a slit 45c is formed in the first part 43, located between the torsion bar 7 and the mirror part 41, and a slit 46c is formed in the first part 44, located between the torsion bar 8 and the mirror part 41. This makes it difficult for the torsional influence of the pair of torsion bars 7 and 8 to affect the coil 11. Therefore, metal fatigue in the coil 11 can be suppressed. Furthermore, the torsional influence of the pair of torsion bars 7 and 8 is also less likely to affect the respective connection regions 40a and 40b. Therefore, both bending of the mirror part 41 and damage to the movable part 4 can be more reliably suppressed.

[0064] In the Miller device 1, the coil 9 extends along the outer side surface 3b of the support portion 3. This separates the coil 9 from each torsion bar 7, 8, thereby reducing the stress generated in the coil 9 due to the twisting of the pair of torsion bars 7, 8. Consequently, metal fatigue in the coil 9 can be suppressed.

[0065] In the mirror device 1, the curvature of the outer edge of the torsion bar 7 in the region connected to the outer edge of the second part 45 is smaller than the curvature of the outer edge of the torsion bar 7 in the region connected to the inner edge of the support part 3. Similarly, the curvature of the outer edge of the torsion bar 8 in the region connected to the outer edge of the second part 46 is smaller than the curvature of the outer edge of the torsion bar 8 in the region connected to the inner edge of the support part 3. By reducing the curvature of the outer edges of each torsion bar 7, 8 in the region connected to the frame 42, the stress generated in the frame 42 due to the twisting of the pair of torsion bars 7, 8 can be reduced. On the other hand, by increasing the curvature of the outer edges of each torsion bar 7, 8 in the region connected to the support part 3, the length of each torsion bar 7, 8 can be secured, and the stress generated due to the twisting of the pair of torsion bars 7, 8 can be reduced. It should be noted that reducing the stress generated due to the twisting of the pair of torsion bars 7, 8 on the movable part 4 side, which is linearly operated, is more effective than reducing it on the support part 3 side.

[0066] In the mirror device 1, a beam structure 31 extending in an annular manner along the frame-shaped support part 3 is provided on the back surface of the support part 3. This suppresses deformation of the support part 3. Moreover, because the beam structure 31 is formed continuously, stress concentration can be suppressed compared to when the beam structure 31 is formed intermittently. Furthermore, in the mirror device 1, the width of the part of the beam structure 31 extending in the Y-axis direction (width in the X-axis direction) is smaller than the width of the part of the beam structure 31 extending in the X-axis direction (width in the Y-axis direction). This reduces the moment of inertia of the support part 3 when the Y-axis is the axis of rotation. Furthermore, in the mirror device 1, the size of each weight-reducing cutout 31a formed in the part of the beam structure 31 extending in the X-axis direction increases as it moves away from the Y-axis. This reduces the moment of inertia of the support part 3 when the Y-axis is the axis of rotation. Furthermore, in the mirror device 1, no weight-reducing cutouts 31a are formed in the intermediate part of the beam structure 31 that crosses the Y-axis. This increases the moment of inertia of the support part 3 when the X-axis is the axis of rotation, and suppresses the oscillation of the support part 3 with the X-axis as the center line. Furthermore, in the mirror device 1, the center position of the part of the beam structure 31 that extends in the Y-axis direction is located outside the center position of the part of the support part 3 that extends in the Y-axis direction. As a result, the part of the beam structure 31 that extends in the Y-axis direction on the torsion bar 7 side moves away from the torsion bar 7, and the part of the beam structure 31 that extends in the Y-axis direction on the torsion bar 8 side moves away from the torsion bar 8, thereby reducing the stress generated in the beam structure 31 due to the twisting of the pair of torsion bars 7 and 8.

[0067] In the mirror device 1, a beam structure 47 extending in a V-shape from the intersection O toward both edges of the connection region 40a in the X-axis direction, and a beam structure 48 extending in a V-shape from the intersection O toward both edges of the connection region 40b in the X-axis direction, are provided on the back surface of the mirror portion 41. This makes it possible to reduce the stress generated in each connection region 40a and 40b due to the twisting of the pair of torsion bars 7 and 8. [Differentiation]

[0068] This disclosure is not limited to the embodiments described above. For example, the materials and shapes of each part are not limited to those described above, and various materials and shapes can be used. For example, the frame 42 may have an external shape other than a rectangle, such as a polygon, when viewed from a direction perpendicular to the X and Y axes, as long as it is formed in a frame shape. Also, the mirror surface 41a only needs to be formed on at least a part of the mirror part 41. Furthermore, the shape of the mirror part 41 when viewed from a direction perpendicular to the X and Y axes may be circular, etc. Also, the driving method of the mirror device 1 is not limited to an electromagnetic drive, but may be an electrostatic drive, piezoelectric drive, thermal drive, etc. Also, the base 2 and the pair of torsion bars 5,6 may not be provided on the mirror device 1, and the support part 3 may function as the base.

[0069] Furthermore, if a pair of torsion bars 7 and 8 are arranged on both sides of the movable part 4 on the first axis, the pair of connection regions 40a and 40b only need to be located on both sides of the mirror portion 41 in a direction parallel to the second axis perpendicular to the first axis. For example, if a pair of parts (parts constituting opposite sides) of a polygonal frame 42 intersect the second axis, the pair of connection regions 40a and 40b only need to be arranged within that pair of parts. In the embodiment described above, the pair of connection regions 40a and 40b only need to be arranged within a pair of first parts 43 and 44. Alternatively, regardless of the shape of the frame 42, the pair of connection regions 40a and 40b only need to be arranged in a region that is 45 degrees or more and 135 degrees or less in one direction from the first axis, with the intersection of the first axis and the second axis as the center point, and in a region that is 45 degrees or more and 135 degrees or less in the other direction from the first axis. Each connection area 40a, 40b may be composed of multiple physically separated areas.

[0070] Furthermore, if the width of the first portion 43 in the Y-axis direction decreases as it moves away from the connection region 40a, it may be a flat surface inclined such that the inner side surface 43a of the first portion 43 approaches the outer side surface 43b of the first portion 43 as it moves away from the connection region 40a, as shown in Figure 7(a). Similarly, if the width of the first portion 44 in the Y-axis direction decreases as it moves away from the connection region 40b, it may be a flat surface inclined such that the inner side surface 44a of the first portion 44 approaches the outer side surface 44b of the first portion 44 as it moves away from the connection region 40b, as shown in Figure 7(a).

[0071] Furthermore, if the width of the first portion 43 in the Y-axis direction decreases as it moves away from the connection region 40a, it may be a stepped curved surface, as shown in Figure 7(b), where the inner side surface 43a of the first portion 43 approaches the outer side surface 43b of the first portion 43 as it moves away from the connection region 40a. Similarly, if the width of the first portion 44 in the Y-axis direction decreases as it moves away from the connection region 40b, it may be a stepped curved surface, as shown in Figure 7(b), where the inner side surface 44a of the first portion 44 approaches the outer side surface 44b of the first portion 44 as it moves away from the connection region 40b.

[0072] Furthermore, in the movable part 4 of the third modified example, as shown in Figure 8, the mirror part 41 is connected to the frame 42 in each of the pair of connection regions (first connection regions) 40a, 40b located on both sides of the mirror part 41 in the Y-axis direction, and in each of the pair of connection regions (second connection regions) 40c, 40d located on both sides of the mirror part 41 in the X-axis direction. The area between the mirror part 41 and the frame 42 other than the pair of connection regions 40a, 40b and the pair of connection regions 40c, 40d is empty space. In other words, the mirror part 41 and the frame 42 are connected to each other only in the pair of connection regions 40a, 40b and the pair of connection regions 40c, 40d.

[0073] The side surface 41b of the mirror section 41 and the inner side surface 43a of the first section 43 are connected such that the curvature is continuous in the connection region 40a. The side surface 41b of the mirror section 41 and the inner side surface 44a of the first section 44 are connected such that the curvature is continuous in the connection region 40b. In other words, the outer edge of the mirror section 41 and the inner edge of the frame 42 are connected such that the curvature is continuous in the respective connection regions 40a and 40b when viewed from directions perpendicular to the X and Y axes.

[0074] The side surface 41b of the mirror section 41 and the inner side surface 45a of the second section 45 are connected such that the curvature is continuous in the connection region 40d. The side surface 41b of the mirror section 41 and the inner side surface 46a of the second section 46 are connected such that the curvature is continuous in the connection region 40c. In other words, the outer edge of the mirror section 41 and the inner edge of the frame 42 are connected such that the curvature is continuous in the respective connection regions 40c and 40d when viewed from directions perpendicular to the X and Y axes.

[0075] The width of the first portion 43 in the Y-axis direction decreases as it moves away from the connection region 40a. Here, the outer side surface 43b of the first portion 43 is a flat surface parallel to the X-axis, and the inner side surface 43a of the first portion 43 becomes a surface that approaches side surface 43b as it moves away from the connection region 40a. The width of the first portion 44 in the Y-axis direction decreases as it moves away from the connection region 40b. Here, the outer side surface 44b of the first portion 44 is a flat surface parallel to the X-axis, and the inner side surface 44a of the first portion 44 becomes a surface that approaches side surface 44b as it moves away from the connection region 40b.

[0076] Furthermore, the inner side surface 43a of the first portion 43 may be a flat surface that is inclined so that it approaches the outer side surface 43b of the first portion 43 as it moves away from the connection region 40a. Similarly, the inner side surface 44a of the first portion 44 may be a flat surface that is inclined so that it approaches the outer side surface 44b of the first portion 44 as it moves away from the connection region 40b. In addition, the inner side surface 43a of the first portion 43 may be a curved surface that is bent in a step shape so that it approaches the outer side surface 43b of the first portion 43 as it moves away from the connection region 40a. Similarly, the inner side surface 44a of the first portion 44 may be a curved surface that is bent in a step shape so that it approaches the outer side surface 44b of the first portion 44 as it moves away from the connection region 40b.

[0077] The width of the second portion 45 in the X-axis direction decreases as it moves away from the connection region 40d. Here, the outer side surface 45b of the second portion 45 is a flat surface parallel to the Y-axis, and the inner side surface 45a of the second portion 45 becomes a surface that approaches side surface 45b as it moves away from the connection region 40d. The width of the second portion 46 in the X-axis direction decreases as it moves away from the connection region 40c. Here, the outer side surface 46b of the second portion 46 is a flat surface parallel to the Y-axis, and the inner side surface 46a of the second portion 46 becomes a surface that approaches side surface 46b as it moves away from the connection region 40c.

[0078] Furthermore, the inner side surface 45a of the second part 45 may be a flat surface that slopes so that it approaches the outer side surface 45b of the second part 45 as it moves away from the connection region 40d. Similarly, the inner side surface 46a of the second part 46 may be a flat surface that slopes so that it approaches the outer side surface 46b of the second part 46 as it moves away from the connection region 40c. In addition, the inner side surface 45a of the second part 45 may be a curved surface that is bent in a step shape so that it approaches the outer side surface 45b of the second part 45 as it moves away from the connection region 40d. Similarly, the inner side surface 46a of the second part 46 may be a curved surface that is bent in a step shape so that it approaches the outer side surface 46b of the second part 46 as it moves away from the connection region 40c.

[0079] In the mirror device 1 equipped with the movable part 4 of the third modified example, a pair of torsion bars 7 and 8 connected to a frame-shaped frame 42 are arranged on the X-axis, and a pair of connection regions 40a and 40b, to which the mirror part 41 and the frame-shaped frame 42 are connected, are located on both sides of the mirror part 41 in the Y-axis direction. Furthermore, a pair of connection regions 40c and 40d, to which the mirror part 41 and the frame-shaped frame 42 are connected, are located on both sides of the mirror part 41 in the X-axis direction. As a result, even if the movable part 4 is oscillated at high speed with the X-axis as its centerline, the stress generated in each connection region 40a, 40b, 40c, and 40d due to the twisting of the pair of torsion bars 7 and 8 is reduced compared to, for example, when only the pair of connection regions 40a and 40b are located on the X-axis, or when the mirror part 41 and the frame-shaped frame 42 are connected to each other in only one connection region 40a (or 40b). Furthermore, in the mirror device 1 equipped with the movable part 4 of the third modified example, the outer edge of the mirror part 41 and the inner edge of the frame 42 are connected such that the curvature is continuous in each connection region 40a and 40b when viewed from a direction perpendicular to the X and Y axes. This makes it less likely for stress concentration to occur in each connection region 40a and 40b. As a result, the mirror device 1 equipped with the movable part 4 of the third modified example can suppress both bending of the mirror part 41 and damage to the movable part 4.

[0080] In the mirror device 1 equipped with the movable part 4 of the third modified example, the outer edge of the mirror part 41 and the inner edge of the frame 42 are connected such that the curvature is continuous in each connection region 40c, 40d when viewed from a direction perpendicular to the X and Y axes. This makes it less likely for stress concentration to occur in each connection region 40c, 40d.

[0081] In the mirror device 1 equipped with the movable part 4 of the third modified example, a pair of connection regions 40c and 40d are located on both sides of the mirror part 41 on the X axis. This makes it possible to reduce the moment of inertia of the movable part around the X axis.

[0082] If a pair of torsion bars 7 and 8 are arranged on both sides of the movable part 4 on the first axis, the pair of connection regions 40c and 40d only need to be located on both sides of the mirror part 41 in a direction parallel to the first axis. For example, if a pair of parts (parts constituting opposite sides) of a polygonal frame 42 intersect the first axis, the pair of connection regions 40c and 40d only need to be arranged within that pair of parts. In the case of the movable part 4 of the third modified example, the pair of connection regions 40c and 40d only need to be arranged within a pair of second parts 45 and 46. Alternatively, regardless of the shape of the frame 42, the pair of connection regions 40c and 40d only need to be arranged in a region that is 45 degrees or more and 135 degrees or less in one direction from the second axis, with the intersection of the first axis and the second axis as the center point, and in a region that is 45 degrees or more and 135 degrees or less in the other direction from the second axis. Each connection area 40c, 40d may be composed of multiple physically separated areas.

[0083] In the mirror device 1 equipped with the movable part 4 of the third modified example, the width of each first part 43, 44 in the Y-axis direction decreases as it moves away from each connection region 40a, 40b, and the width of each second part 45, 46 in the X-axis direction decreases as it moves away from each connection region 40c, 40d. As a result, the stress generated due to the twisting of the pair of torsion bars 7, 8 is distributed to the parts of each first part 43, 44 and each second part 45, 46 where the width is reduced, thereby reducing the stress generated in each connection region 40a, 40b, 40c, 40d. Furthermore, while ensuring the connection strength in each connection region 40a, 40b, 40c, 40d, the moment of inertia of the movable part 4 when the X-axis is the axis of rotation can be reduced by the amount by which the width of each first part 43, 44 and each second part 45, 46 is reduced. However, the width of each second portion 45, 46 in the X-axis direction does not necessarily have to decrease as it moves away from each connection region 40c, 40d.

[0084] In the mirror device 1 equipped with the movable part 4 of the third modified example, a slit 45c located between the torsion bar 7 and the mirror part 41 is formed in the first part 43, and a slit 46c located between the torsion bar 8 and the mirror part 41 is formed in the first part 44. Furthermore, the curvature of the outer edge of the torsion bar 7 in the region connected to the outer edge of the second part 45 is smaller than the curvature of the outer edge of the torsion bar 7 in the region connected to the inner edge of the support part 3. Similarly, the curvature of the outer edge of the torsion bar 8 in the region connected to the outer edge of the second part 46 is smaller than the curvature of the outer edge of the torsion bar 8 in the region connected to the inner edge of the support part 3. As a result, in the mirror device 1 equipped with the movable part 4 of the third modified example, stable support of the mirror part 41 is achieved by the four connection regions 40a, 40b, 40c, and 40d, while the torsional influence of the pair of torsion bars 7 and 8 is less likely to affect the pair of connection regions 40c and 40d.

[0085] Each configuration in the above-described embodiment is also applied to the mirror device 1 equipped with a movable part 4 of the third modified example. For example, the inner edges of each first part 43, 44 and the inner edges of each second part 45, 46 are connected to each other such that the curvature is continuous in each region connected to each other when viewed from a direction perpendicular to the X and Y axes. Also, the outer edges of each first part 43, 44 and the outer edges of each second part 45, 46 are connected to each other such that the curvature is continuous in each region connected to each other when viewed from a direction perpendicular to the X and Y axes. Furthermore, the length of each first part 43, 44 in the X-axis direction is longer than the length of each second part 45, 46 in the Y-axis direction. Furthermore, the distance between the connection region 40a and the second portion 45, the distance between the connection region 40a and the second portion 46, the distance between the connection region 40b and the second portion 45, and the distance between the connection region 40b and the second portion 46 are all longer than the distance between the X-axis and the first portion 43, and the distance between the X-axis and the first portion 44. Also, the shape of the mirror portion 41 when viewed from a direction perpendicular to the X-axis and Y-axis is an ellipse with a major axis along the X-axis. In addition, the width of each connection region 40a, 40b in the X-axis direction is 30% or less of the width of the mirror portion 41 in the X-axis direction. Furthermore, the coil 11 extends along the outer sides 43b, 44b in each first portion 43, 44, and extends along the inner sides 45a, 46a in each second portion 45, 46. Furthermore, the coil 9 extends along the outer side 3b of the support portion 3. Furthermore, a beam structure 31 is provided on the back surface of the support portion 3, extending in an annular shape along the frame-shaped support portion 3. Additionally, a beam structure 47 is provided on the back surface of the mirror portion 41, extending in a V-shape from the intersection O toward both edges of the connection region 40a in the X-axis direction, and a beam structure 48 is provided, extending in a V-shape from the intersection O toward both edges of the connection region 40b in the X-axis direction.

[0086] In the mirror device 1 equipped with the movable part 4 of the third modification, the materials and shapes of each part are not limited to those described above, but can be made from a variety of materials and shapes. For example, the frame 42 may have an external shape other than a rectangle, such as a polygon, when viewed from a direction perpendicular to the X and Y axes, as long as it is formed in a frame shape. Also, the mirror surface 41a only needs to be formed on at least a part of the mirror part 41. Furthermore, the shape of the mirror part 41 when viewed from a direction perpendicular to the X and Y axes may be circular, etc.

[0087] In the embodiments and modifications described above, a coil 11 for swinging the movable part 4 is provided on the movable part 4, and a coil 9 for swinging the support part 3 is provided on the support part 3. However, the coil for swinging the movable part 4 and the coil for swinging the support part 3 may each be provided on the support part 3, or a single coil for swinging both the movable part 4 and the support part 3 may be provided on the support part 3.

[0088] Each configuration in the above-described embodiment or modification can be optionally applied to each configuration in other embodiments or modifications. [Explanation of Symbols]

[0089] 1...Mirror device, 3...Support part, 4...Movable part, 7,8...Torsion bar, 40a,40b...Connection area (first connection area), 40c,40d...Connection area (second connection area), 41...Mirror part, 42...Frame, 43,44...First part, 45,46...Second part.

Claims

1. Bass and, A frame-shaped support section, A movable part with a mirror surface, A first torsion bar connects the movable part to the support part so that the movable part can swing with respect to the first axis as its centerline, The support portion is connected to the base by a second torsion bar, such that the support portion can swing with respect to the second axis as its centerline. The support section is provided with a first beam structure. The first beam structure has a first portion formed in the support portion connected to the first torsion bar and extending in a direction along the second axis, and a second portion formed in the support portion connected to the second torsion bar and extending in a direction along the first axis, A mirror device in which the width of the first portion in the direction along the first axis is smaller than the width of the second portion in the direction along the second axis.

2. The mirror device according to claim 1, wherein the first beam structure extends in an annular manner along the frame-shaped support portion.

3. The mirror device according to claim 2, wherein the curvature of the inner edge of the annularly extending first beam structure is continuous when viewed from a direction perpendicular to both the first axis and the second axis.

4. The mirror device according to claim 2 or 3, wherein the shape of the outer edge of the annularly extending first beam structure is octagonal when viewed from a direction perpendicular to both the first axis and the second axis.

5. The mirror surface is formed on one side of the movable part, The mirror device according to any one of claims 1 to 4, wherein the first beam structure is provided on the back surface of the support portion opposite to the one side.

6. The center position of the first portion is located outward from the center position of the portion connected to the first torsion bar in the support portion. The center position of the first portion is the center position of the width in the direction along the first axis, The mirror device according to any one of claims 1 to 5, wherein the center position of the portion connected to the first torsion bar in the support portion is the center position of the width in the direction along the first axis.

7. The mirror device according to any one of claims 1 to 6, wherein the movable part is provided with a second beam structure.

8. The movable part comprises a frame-shaped frame to which the first torsion bar is connected, and a mirror part positioned inside the frame. The mirror device according to claim 7, wherein the mirror surface is formed on one side of the mirror portion, and the second beam structure is provided on the back surface opposite to the one side of the mirror portion.

9. The mirror device according to any one of claims 1 to 8, wherein the width of the end of the first torsion bar on the support side increases as it approaches the support when viewed from a direction perpendicular to both the first axis and the second axis.

10. The mirror device according to any one of claims 1 to 9, wherein the width of the end of the first torsion bar on the movable part side increases as it approaches the movable part when viewed from a direction perpendicular to both the first axis and the second axis.

11. The mirror device according to any one of claims 1 to 10, wherein the second torsion bar extends in a meandering manner.

12. The mirror device according to any one of claims 1 to 11, wherein the base, the support portion, the movable portion, the first torsion bar, and the second torsion bar are integrally formed from a semiconductor substrate.

13. The first torsion bar is each of a pair of first torsion bars arranged on both sides of the movable part on the first axis, The mirror device according to any one of claims 1 to 12, wherein the second torsion bar is each of a pair of second torsion bars arranged on both sides of the support portion on the second axis.

14. The first portion is each of a pair of first portions formed in the support portion connected to the pair of first torsion bars, The second portion is each of a pair of second portions formed in the support portion connected to the pair of second torsion bars, The mirror device according to claim 13, wherein the width of each of the pair of first portions in the direction along the first axis is smaller than the width of each of the pair of second portions in the direction along the second axis.

15. The first beam structure further comprises a third portion connected to the end of the first portion, The mirror device according to any one of claims 1 to 14, wherein the third portion extends from the end of the first portion toward the second axis in a direction that intersects both the direction along the first axis and the direction along the second axis when viewed from a direction perpendicular to both the first axis and the second axis.

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