Cantilever and drive element

Abstract

The present invention provides a cantilever and a drive element that can maintain high drive efficiency while suppressing element failure during operation. [Solution] The cantilever 21 comprises a plate portion 21a extending in one direction with a predetermined width and deformable in the thickness direction, a support portion 21c formed by laminating an active layer 201 common to the plate portion 21a, a BOX layer 202 and a base layer 203, and a piezoelectric element 21b arranged in at least the longitudinal direction of the plate portion 21a. Two inclined portions C1 are formed side by side in the width direction of the plate portion 21a at the boundary B1 of the support portion 21c on the plate portion 21a side, approaching each other as they move toward the plate portion 21a, and the two edges of the plate portion 21a in the width direction are connected to the two inclined portions C1 respectively, and furthermore, in a plan view, a recess R1 is formed in the center between the two inclined portions C1 at the boundary B1, recessed inward from the support portion 21c, and two protrusions P1 projecting toward the plate portion 21a side by side in the width direction are formed.

Description

TECHNICAL FIELD

[0001] The present invention relates to a cantilever and a driving element including the same.

BACKGROUND ART

[0002] Conventionally, driving elements that rotate a movable portion about a rotation axis are known. For example, the following Patent Document 1 describes a driving element in which a reflective portion (movable portion) is swingably supported by plate-shaped beams. The plate-shaped beam includes a plurality of linearly extending deformable portions, at least one connecting portion that connects these deformable portions in a meandering shape, and a rib protruding at the connecting portion to reinforce the connecting portion. A piezoelectric body serving as a driving source is disposed on at least the linear portion of the beam. The rib is provided at a position extending the deformable portion in its longitudinal direction. Both end portions of the rib are located outside the outer edge of the connecting portion, which is the portion connected to the deformable portion, in the orthogonal direction perpendicular to the longitudinal direction of the deformable portion. The rib is arranged at a position farther from the deformable portion than the connecting portion. Patent Document 1 describes that by arranging the ribs in this manner, the stress applied to the ribs is dispersed, making the ribs less likely to break.

PRIOR ART DOCUMENTS

PATENT DOCUMENTS

[0003]

PATENT DOCUMENT 1

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

[0004] However, even in the configuration of Patent Document 1 described above, the stress applied to the ribs increases near both ends of the connecting portion. Therefore, if the deformable portion is deformed more greatly to increase the rotation angle of the movable portion, there is a risk that the ribs may break.

[0005] In view of these challenges, the present invention aims to provide a cantilever and a drive element that can suppress element failure during operation while maintaining high drive efficiency. [Means for solving the problem]

[0006] A first aspect of the present invention relates to a cantilever. The cantilever according to this aspect comprises a plate portion extending in one direction with a predetermined width and deformable in the thickness direction, a support portion formed by laminating a layer common to the plate portion and other layers, and a piezoelectric element arranged in a range at least in the longitudinal direction of the plate portion. Two inclined portions are formed side by side in the width direction of the plate portion at the boundary of the support portion on the plate portion side, approaching each other as they move toward the plate portion, and the two edges of the plate portion in the width direction are connected to the two inclined portions, respectively, and further, in plan view, a recess is formed in the center between the two inclined portions at the boundary, recessed inward from the support portion, and two protrusions are formed side by side in the width direction, projecting toward the plate portion.

[0007] When the plate portion is driven, the stress generated at the connection between the plate portion and the support portion is greatest at both ends of this connection portion. In contrast, with the cantilever according to this embodiment, since the two edges of the plate portion in the width direction are connected to two inclined portions respectively, the stress generated at both ends of the connection portion when the plate portion is driven is distributed along the inclined portions, thereby suppressing the stress generated at both ends of the connection portion. Therefore, it is possible to suppress the failure of the support portion when the plate portion is driven. Furthermore, at the boundary, in a plan view, a recess is formed in the center between the two inclined portions, recessed inward from the support portion, so the effective area of ​​the piezoelectric element can be extended into the recess. Therefore, the driving efficiency of the cantilever can be maintained at a high level. Accordingly, with the cantilever according to this embodiment, it is possible to suppress element failure during driving while maintaining high driving efficiency.

[0008] A second aspect of the present invention relates to a drive element. The drive element according to this aspect comprises a movable part, a drive unit for rotating the movable part about a pivot axis, and a base for supporting the drive unit. The drive unit is configured by connecting a plurality of cantilevers in a meander shape, at least one of the plurality of cantilevers is a cantilever according to the first aspect, and the support portion of the cantilever furthest from the movable part is connected to the base.

[0009] According to the drive element of this embodiment, since the cantilever according to the first embodiment is used in at least one cantilever that is intended to suppress the maximum stress, it is possible to suppress element failure of the cantilever while maintaining high driving efficiency in the cantilever. Therefore, the plate portion of the cantilever can be deformed significantly, and the rotation angle of the movable part can be increased. [Effects of the Invention]

[0010] As described above, the present invention provides a cantilever and a drive element that can suppress element failure during operation while maintaining high drive efficiency.

[0011] The effects and significance of the present invention will become even clearer from the description of the embodiments shown below. However, the embodiments shown below are merely examples of how to implement the present invention, and the present invention is not limited in any way to those described in the embodiments below. [Brief explanation of the drawing]

[0012] [Figure 1] Figure 1 is a schematic top view showing the configuration of the drive element according to Embodiment 1. [Figure 2] Figure 2 is a schematic bottom view showing the configuration of the drive element according to Embodiment 1. [Figure 3] Figure 3 is an end view of the drive element according to Embodiment 1, when the drive element is cut by a plane parallel to the YZ plane at the center position in the width direction (X-axis direction) of the cantilever closest to the positive X-axis. [Figure 4] Figure 4 is an enlarged perspective view showing the configuration near the support portion of the cantilever on the positive X-axis side according to Embodiment 1. [Figure 5] Figures 5(a) to 5(c) show the simulation results obtained by simulation for comparative examples and reference examples, which determine the stress generated in the BOX layer at the boundary of the support part due to the driving of the plate part. [Figure 6] Figures 6(a) to 6(c) show the simulation results obtained by simulation for the comparative example and Embodiment 1, which determine the stress generated in the BOX layer at the boundary of the support part due to the driving of the plate part. [Figure 7] Figures 7(a) to 7(c) show the simulation results obtained by simulation for Embodiment 1, which determine the stress generated in the BOX layer at the boundary of the support part due to the driving of the plate part. [Figure 8] Figures 8(a) to 8(c) show the simulation results obtained by simulation for Embodiment 1, which determine the stress generated in the BOX layer at the boundary of the support part due to the driving of the plate part. [Figure 9] Figure 9 is a graph showing the relationship between angle and maximum stress in the BOX layer for the simulations of the comparative example and Embodiment 1. [Figure 10] Figures 10(a) and (b) show the simulation results of the stress distribution for the reference example and Embodiment 1 used for comparison. [Figure 11] Figures 11(a) to (d) are schematic bottom views showing the shape of the boundary on the plate side of the support part for each modified example. [Figure 12] Figures 12(a) to (d) are schematic bottom views showing the shape of the boundary on the plate side of the support part for each modified example. [Figure 13] Figure 13 is a perspective view showing the configuration of the cantilever according to Embodiment 2. [Figure 14] Figure 14 is a schematic bottom view showing the configuration of the drive element in the modified example. [Modes for carrying out the invention]

[0013] Hereinafter, embodiments of the present invention will be described with reference to the drawings. For convenience, mutually orthogonal X, Y, and Z axes are appended to each drawing. The X-axis direction and the Y-axis direction are the width direction and the length direction of the cantilever, respectively, and the positive Z-axis direction is the upward direction of the driving element.

[0014] <Embodiment 1> FIG. 1 is a top view schematically illustrating the configuration of a driving element 1 according to Embodiment 1. FIG. 2 is a bottom view schematically illustrating the configuration of the driving element 1 according to Embodiment 1. For convenience, in FIG. 1, illustration of wiring patterns for supplying drive signals to each piezoelectric body 21b and the terminal portions of the wiring patterns is omitted.

[0015] With reference to FIG. 1 and FIG. 2, the driving element 1 includes a base 10, a pair of driving portions 20, a pair of connecting beams 30, and a movable portion 40. The driving element 1 has a point-symmetric shape with respect to the center C10 in plan view. Hereinafter, the side close to the center C10 is referred to as "inner side", and the side far from the center C10 is referred to as "outer side". The driving element 1 is formed by processing an SOI wafer.

[0016] Each part of the driving element 1 is integrally connected by an active layer 201. In addition, in the hatched portion of the driving element 1 in FIG. 2, the thickness is increased by laminating a BOX layer 202 and a base layer 203 on the lower surface of the active layer 201. The layer structure of the driving element 1 will be described later with reference to FIG. 3.

[0017] The base 10 has a rectangular frame shape in plan view. The pair of driving portions 20 and the pair of connecting beams 30 are arranged in the opening 11 of the base 10 in plan view. One end of each of the pair of driving portions 20 is supported by the base 10, and the other end thereof is connected to the movable portion 40 via the connecting beam 30. The pair of driving portions 20 are arranged on opposite sides of the movable portion 40 in parallel with the rotation axis R10, and apply a driving force to the movable portion 40 from both sides.

[0018] The movable part 40 has a circular contour in plan view. The movable part 40 is supported on the base 10 so as to be rotatable about the pivot axis R10 via a pair of drive units 20 and a pair of connecting beams 30. In plan view, the center of the movable part 40 coincides with the position of the center C10 of the drive element 1. A rib 41 is formed on the outer circumference of the lower surface of the movable part 40.

[0019] A reflective surface 40a that reflects light is arranged on the upper surface of the movable part 40. Normally, the upper surface of the active layer 201 has sufficient reflectivity due to the formation of the SOI wafer, so the upper surface of the active layer 201 can be used as the reflective surface 40a. The reflectivity of the reflective surface 40a may be increased by polishing the upper surface of the active layer 201 of the movable part 40. Alternatively, an optical reflective film that constitutes the reflective surface 40a may be formed separately on the upper surface of the active layer 201 of the movable part 40.

[0020] Each drive unit 20 has multiple cantilevers 21. Here, four cantilevers 21 are included in each drive unit 20. The four cantilevers 21 are connected in a meandering shape to form one drive unit 20. In adjacent cantilevers 21, the adjacent support portion 21c and drive end 21d are connected. The support portion 21c is one end of the cantilever 21 to be supported, and the drive end 21d is the other end of the cantilever 21 to be driven. In adjacent cantilevers 21, the support portion 21c of the inner cantilever 21 is connected to the drive end 21d of the outer cantilever 21, and the inner cantilever 21 is supported by the outer cantilever 21.

[0021] In each drive unit 20, the three inner cantilevers 21 each have a shape in which, in a plan view, the two long sides of a rectangle that is long in the Y-axis direction are recessed inward in a rectangular shape. The shape and size of these three cantilevers 21 are the same as each other. In each drive unit 20, the outermost cantilever 21 has a shape in which, in a plan view, the two long sides of a rectangle that is long in the Y-axis direction are recessed inward in a trapezoidal shape. In each drive unit 20, the Y-axis length of the three inner cantilevers 21 is the same as the Y-axis length of the outermost cantilever 21. The eight cantilevers 21 are arranged so that their short sides are aligned in a straight line along the X-axis.

[0022] Each cantilever 21 comprises a plate portion 21a, a piezoelectric element 21b, and a support portion 21c. The plate portion 21a extends in one direction (Y-axis direction) with a predetermined width and is deformable in the thickness direction (Z-axis direction). In this case, the plate portion 21a consists only of the active layer 201. However, the plate portion 21a may be composed of multiple layers.

[0023] The support portion 21c is constructed by laminating a layer common to the plate portion 21a (active layer 201) and other layers (the BOX layer 202 and base layer 203 shown in Figure 3). Therefore, the thickness of the support portion 21c is greater than the thickness of the plate portion 21a. As a result, ribs 31 and 32 that protrude downward are formed on the lower surface of the support portion 21c.

[0024] The rib 31 formed on the first support section 21c from the outside extends in the X-axis direction to the base 10 and connects to the base 10. The ribs 32 formed on the second, third, and fourth support sections 21c from the outside extend to the first, second, and third drive ends 21d from the outside, respectively. A rib 33 is also formed on the drive end 21d of the innermost cantilever 21. The rib 33 extends inward from this drive end 21d and connects to the connecting beam 30.

[0025] The support portion 21c and the drive end 21d each have corresponding ribs over their entire length in a plan view. Ribs 32 and 33 are rectangular in a plan view. In contrast, rib 31 has two protrusions projecting toward the plate portion 21a in a plan view. The shape of rib 31 will be described later with reference to Figure 4.

[0026] As shown in Figure 1, the width (length in the X-axis direction) of the support portion 21c and the drive end 21d is slightly larger than the width (length in the X-axis direction) of the plate portion 21a. Therefore, in a plan view, the support portion 21c and the drive end 21d of each cantilever 21 protrude in the X-axis direction relative to the plate portion 21a of the cantilever 21.

[0027] The piezoelectric element 21b is positioned at least within the range of the plate portion 21a in the longitudinal direction (Y-axis direction). Here, the piezoelectric element 21b is positioned in a range that exceeds the range of the plate portion 21a in the Y-axis direction. That is, the piezoelectric element 21b extends over the upper surface of the plate portion 21a and the support portion 21c. Each piezoelectric element 21b is a rectangle that is elongated in the Y-axis direction when viewed from above.

[0028] The piezoelectric element 21b is a so-called piezoelectric transducer. A piezoelectric transducer is sometimes called a piezoelectric actuator. The piezoelectric element 21b has a layered structure consisting of a lower electrode layer 211, a piezoelectric layer 212, and an upper electrode layer 213, which will be described later. When a driving voltage is applied to the piezoelectric element 21b, the piezoelectric layer 212 within the piezoelectric element 21b deforms due to the inverse piezoelectric effect, and the plate portion 21a on which the piezoelectric element 21b is formed bends.

[0029] Of the four piezoelectric elements 21b arranged in one drive unit 20, a first drive voltage with the same phase is applied to the first and third piezoelectric elements 21b from the outside, and a second drive voltage with the same phase is applied to the second and fourth piezoelectric elements 21b from the outside. At this time, the first drive voltage and the second drive voltage are in opposite phases to each other. As a result, a driving force around the pivot axis R10 is applied to the movable part 40 from the four cantilevers 21 connected in a meander shape. As a result, the movable part 40 rotates around the pivot axis R10.

[0030] Figure 3 is an end view of the drive element 1 when the drive element 1 is cut by a plane parallel to the YZ plane at the center position in the width direction (X-axis direction) of the cantilever 21 on the positive X-axis side.

[0031] The driving element 1 is formed by processing a single SOI wafer in which an active layer 201, a BOX layer 202, and a base layer 203 are stacked in the negative Z-axis direction. The active layer 201 and the base layer 203 are made of, for example, silicon (Si), and the BOX layer 202 is made of, for example, silicon dioxide (SiO2).

[0032] First, the lower electrode layer 211, piezoelectric layer 212, and upper electrode layer 213 are stacked on the upper surface of the SOI wafer in the positive Z-axis direction. Then, the lower electrode layer 211, piezoelectric layer 212, and upper electrode layer 213 are etched so that piezoelectric material 21b is formed on the upper surface of the corresponding regions of the plate portion 21a, support portion 21c, and drive end 21d. Subsequently, the active layer 201 is processed, and the BOX layer 202 and base layer 203 are processed in order. The active layer 201 is processed by etching from the top side (positive Z-axis side), and the BOX layer 202 and base layer 203 are processed by etching from the bottom side (negative Z-axis side). The thickness of the ribs (sum of the thicknesses of the BOX layer 202 and base layer 203) is greater than the thickness of the active layer 201.

[0033] The plate portion 21a is composed of an active layer 201. The base 10, support portion 21c, and drive end 21d are constructed by laminating the active layer 201, BOX layer 202, and base layer 203. In the support portion 21c and drive end 21d, the ribs 31 and 32 are formed by the laminated structure of the BOX layer 202 and the base layer 203. The other ribs 31, 32, and 41 in Figure 2 are similarly constructed by the laminated structure of the BOX layer 202 and the base layer 203. The connecting beam 30 in Figure 2 is constructed by laminating the active layer 201, BOX layer 202, and base layer 203, similar to the base 10.

[0034] Incidentally, when a driving voltage is applied to the piezoelectric element 21b of the cantilever 21, the piezoelectric element 21b expands and contracts not only in the longitudinal direction but also in the transverse direction. As a result, strain occurs in the plate portion 21a not only in the longitudinal direction but also in the transverse direction. Due to the strain of the plate portion 21a in the transverse direction, large stresses are generated at both ends in the X-axis direction of the connection between the plate portion 21a and the support portion 21c.

[0035] On the other hand, the BOX layer 202 has a lower fracture stress compared to the other active layers 201 and base layer 203. Also, because the BOX layer 202 is formed by bonding with the active layers 201 and base layer 203, its adhesion to the active layers 201 and base layer 203 is low. Therefore, if the large stress generated at both ends of the aforementioned connection part is applied to the BOX layer 202, fracture will occur in the BOX layer 202 of the support part 21c, and this fracture will trigger fracture of the drive element 1.

[0036] Therefore, in Embodiment 1, a configuration is applied to the support portion 21c of at least one of the four cantilevers 21 that constitute each drive unit 20, in order to reduce the stress generated when the cantilever 21 is driven.

[0037] In the following, a configuration to reduce stress is applied to the support portion 21c of the outermost cantilever 21 among the four cantilevers 21 that constitute each drive unit 20. This is because when the drive element 1 is subjected to an impact in the thickness direction due to the drive element 1 falling, the maximum stress (stress generated at both ends of the connection portion) of the support portion 21c of the outermost cantilever 21 among the four cantilevers 21 of each drive unit 20 becomes larger than that of the other cantilevers 21. In other words, in the following, a configuration to reduce stress is applied to the support portion 21c of the outermost cantilever 21 among the four cantilevers 21 that constitute each drive unit 20, taking into consideration not only the maximum stress generated in the BOX layer 202 by the driving of the movable part 40, but also the maximum stress generated in the BOX layer 202 by the impact on the drive element 1.

[0038] However, the stress generated at both ends of the connection portion due to the driving of the movable portion 40 is predominantly due to the strain in the short direction of the plate portion 21a. Therefore, the support portion 21c and drive end 21d of the eight cantilevers 21 shown in Figure 2 may experience nearly the same maximum stress due to the driving of the movable portion 40. For this reason, from the viewpoint of suppressing the maximum stress on the BOX layer 202 generated by the driving of the movable portion 40 without considering the impact on the drive element 1, it is preferable to apply the same configuration as below not only to the support portion 21c but also to the drive end 21d of each of the eight cantilevers 21.

[0039] Figure 4 is an enlarged perspective view showing the configuration near the support portion 21c of the cantilever 21 on the positive X-axis side.

[0040] Figure 4 shows a perspective view from below of the area near the support portion 21c of the cantilever 21, which is located furthest towards the positive X-axis in Figure 2. In Figure 4, the portion of the support portion 21c hidden by the plate portion 21a is shown with a dashed line.

[0041] At the boundary B1 of the support portion 21c on the plate portion 21a side, two inclined portions C1 are formed side by side in the width direction (X-axis direction) of the plate portion 21a, approaching each other as they move toward the plate portion 21a. In Figure 4, for convenience, the boundary B1 is shown as a dashed line, and the inclined portions C1 are shown as dots enclosed by dotted lines. In addition, the two edges of the plate portion 21a in the width direction (X-axis direction) are connected to the two inclined portions C1, respectively. Furthermore, in a plan view, a recess R1 is formed in the center between the two inclined portions C1 at the boundary B1, recessed inward (positive Y-axis direction) of the support portion 21c, and two convex portions P1 protruding toward the plate portion 21a are formed side by side in the width direction (X-axis direction).

[0042] In the example shown in Figure 4, the two protrusions P1 each have a trapezoidal shape with rounded corners when viewed from above. The two protrusions P1 are identical in shape and size. Furthermore, the two protrusions P1 are symmetrical in the X-axis direction.

[0043] Thus, when the two edges of the plate portion 21a in the width direction are connected to the two inclined portions C1 respectively, the stress generated at both ends E1 of the connection portion when the plate portion 21a is driven is distributed along the inclined portions C1, thereby suppressing the stress generated at both ends E1 of the connection portion. Therefore, it is possible to suppress the occurrence of fracture in the BOX layer 202 of the support portion 21c when the plate portion 21a is driven. In addition, in a plan view, a recess R1 is formed in the center between the two inclined portions C1 at the boundary B1, recessed inward from the support portion 21c. Therefore, the effective area of ​​the piezoelectric element 21b that contributes to the driving of the plate portion 21a can be extended into the recess R1. Therefore, the driving efficiency of the cantilever 21 can be maintained at a high level.

[0044] Below, we will sequentially verify the effects of the configuration shown in Figure 4 through simulation, dividing them into stress reduction due to the inclined section C1 and improvement of driving efficiency due to the recessed section R1.

[0045] <Confirmation of stress reduction due to inclined section C1 1> First, the stress generated in the BOX layer 202 of the support portion 21c at boundary B1 was determined by simulation for a comparative example where no inclined portion C1 is formed at boundary B1 of the support portion 21c, and for a reference example where two inclined portions C1 are formed at boundary B1. In the reference example, there is no recess R1 at boundary B1, and only one convex portion P2 protruding towards the plate portion 21a is formed at boundary B1.

[0046] Figures 5(a) to (c) show the simulation results obtained by simulation for comparative examples and reference examples, showing the stress generated in the BOX layer 202 at the boundary B1 of the support portion 21c due to the driving of the plate portion 21a.

[0047] In the comparative example in Figure 5(a), width W0 is the width range of the support portion 21c in Figure 4, and width W1 is the width range of the plate portion 21a in Figure 4. Widths W0 and W1 are the same in the comparative example and the reference example. Widths W0 and W1 are 340 μm and 300 μm, respectively. In the comparative example, the boundary B1 of the support portion 21c is a plane parallel to the XZ plane. In the reference example, the angle θ1 of the two inclined portions C1 of the convex portion P2 with respect to the XZ plane (corresponding to the angle θ1 in Figure 4) is fixed at 26.6°, and the height H1 of the convex portion P2 is changed. In Figure 5(b), the height H1 is 30 μm, and in Figure 5(c), the height H1 is 60 μm.

[0048] In Figures 5(a) to (c), the maximum and minimum values ​​of the scale bar represent the maximum and minimum stresses generated in the BOX layer 202, respectively. In Figures 5(a) to (c), the scale bar and simulation results are actually shown in color. Specifically, the minimum, maximum, and intermediate values ​​of the scale bar are set to blue, red, and green, respectively, and the color of the scale bar is set to transition between these colors as the stress increases. However, for convenience, the color simulation results are shown in grayscale here. Also for convenience, the area around where the maximum stress occurs is indicated by a white dashed line.

[0049] Referring to the simulation results in Figure 5(a), in the comparative example, localized maximum stress occurred near both ends of the width of the plate portion 21a. In contrast, in the reference example, as shown in Figure 5(b), the stress generated in the BOX layer 202 was distributed along the inclined portion C1, and the maximum stress was reduced compared to the comparative example. Furthermore, in the reference example, as shown in Figure 5(c), when the height H1 of the convex portion P2 was increased compared to Figure 5(b) to extend the length of the inclined portion C1, the stress distribution progressed further, and the maximum stress was reduced even more. Therefore, from these simulation results, it was confirmed that by connecting the two edges of the plate portion 21a in the width direction to the two inclined portions C1, the maximum stress generated in the BOX layer 202 when the plate portion 21a is driven can be effectively reduced.

[0050] <Confirmation of stress reduction due to inclined section C1 2> Next, the stress generated in the BOX layer 202 of the support portion 21c at boundary B1 was determined by simulation for the comparative example described above and the configuration of Embodiment 1 described above. Compared to the reference example described above, in Embodiment 1, a recess R1 is formed at boundary B1, and two protrusions P1 that project toward the plate portion 21a are formed side by side in the width direction of the plate portion 21a.

[0051] Figures 6(a) to 8(c) show the simulation results obtained by simulation for the comparative example and Embodiment 1, showing the stress generated in the BOX layer 202 at the boundary B1 of the support portion 21c due to the driving of the plate portion 21a. These simulation results are also shown in grayscale for convenience, similar to Figures 5(a) to (c).

[0052] In the comparative example and the simulation of Embodiment 1, the widths W0 and W1 are 440 μm and 400 μm, respectively. In the simulation of Embodiment 1, the width W2 shown in Figure 6(b) is 420 μm, and the widths W3 to W6 are all 60 μm. Width W2 is the width of the area where the two inclined portions C1 and the recess R1 are located. Width W3 is the width of the bottom surface of the recess R1, and widths W4 and W6 are the widths of the two inclined portions C1 of the convex portion P1. Width W5 is the width of the upper bottom portion of the convex portion P1. In Figure 6(b), the widths W4 to W6 are indicated only for one of the convex portions P1, but the widths W4 to W6 of the other convex portion P1 are also 60 μm.

[0053] In the simulation according to Embodiment 1, with the widths W2 to W6 fixed, the heights of the two protrusions P1 were changed, and the angle θ1 (corresponding to angle θ1 in Figure 4) between the inclined portion C1 of each protrusion P1 and the XZ plane was changed.

[0054] In the simulation shown in Figure 6(b), the angle θ1 is 9.5°. Referring to the results of this simulation, the stress generated in the BOX layer 202 is distributed along the inclined section C1, and the maximum stress in the BOX layer 202 is reduced compared to the comparative example. Therefore, similar to the above reference example, it was confirmed that the maximum stress generated in the BOX layer 202 when the plate section 21a is driven can be effectively reduced by connecting the two edges of the plate section 21a in the width direction to the two inclined sections C1, respectively.

[0055] In the simulations shown in Figures 7(a) to 7(c), the angles θ1 are 14.0°, 18.4°, and 26.6°, respectively. Referring to these simulation results, compared to the simulation result in Figure 6(b), the stress generated in the BOX layer 202 is further distributed along the inclined section C1, and the maximum stress in the BOX layer 202 is further reduced. Therefore, it was confirmed that by adjusting the angle of the inclined section C1, the maximum stress generated in the BOX layer 202 when the plate section 21a is driven can be reduced more effectively.

[0056] In the simulations shown in Figures 8(a) to (c), the angles θ1 were 33.7°, 39.8°, and 45.0°, respectively. In these simulation results as well, the maximum stress in the BOX layer 202 was reduced compared to the comparative example. However, in these simulation results, although the stress near the edge of the plate portion 21a decreased due to dispersion, a maximum stress occurred near the corner between the upper base of the convex portion P1 and the inclined portion C1, and this maximum stress increased compared to the cases in Figures 7(b) and (c). Therefore, it was confirmed that there is a range in the angle of the inclined portion C1 that is preferable for reducing the maximum stress, based on the bending shape near the upper base of the convex portion P1.

[0057] Figure 9 is a graph showing the relationship between the angle θ1 and the maximum stress in the BOX layer 202 in this simulation.

[0058] The horizontal axis of the graph represents the angle θ1, and the vertical axis represents the ratio of the maximum stress obtained at each value of angle θ1 to the maximum stress in the comparative example in Figure 6(a). In the comparative example, there is no convex P1, so the angle θ1 is 0°.

[0059] This graph also shows that, in order to suppress the maximum stress in the BOX layer 202, there is a preferred range for the angle θ1 of the convex portion P1, and there is a minimum point of angle θ1 that can best suppress the maximum stress in the BOX layer 202. Therefore, in order to suppress the maximum stress in the BOX layer 202, it is preferable to set the angle of the convex portion P1 near this minimum point.

[0060] <Checking drive efficiency> Next, the difference in the driving efficiency of the cantilever 21 between the above reference example and the configuration of Embodiment 1 was confirmed by simulation.

[0061] Figures 10(a) and (b) show the simulation results of the stress distribution for the reference example and Embodiment 1 used for comparison.

[0062] In the simulations shown in Figures 10(a) and (b), the widths W0, W1, and W2 are 340 μm, 300 μm, and 320 μm, respectively, and the widths W4, W5, and W6 are 60 μm, 40 μm, and 60 μm, respectively. The height H1 of the protrusions P1 and P2 is 30 μm, and the angle θ1 is 26.6°. Under these conditions, the displacement of the drive end 21d (without ribs) in the Z-axis direction was determined by simulation when the same drive voltage was applied to the piezoelectric body 21b of the cantilever 21, which has the same configuration as the reference example except for the protrusions P1 and P2, for both the reference example and Embodiment 1. As a result, when the displacement in Embodiment 1 was set to 100, the displacement in the reference example was 99.62.

[0063] From these simulation results, it was confirmed that by providing a recess R1 as in Embodiment 1 and extending the effective area of ​​the piezoelectric element 21b into the interior of the recess R1, the driving efficiency of the cantilever 21 can be maintained at a high level.

[0064] In the configuration shown in Figure 10(b), the recess R1 is omitted compared to Figures 6(b) to 8(c). From this, it can be assumed that the driving efficiency of the cantilever 21 can be further improved by widening the width of the recess R1 by providing a width W3 as shown in Figures 6(b) to 8(c).

[0065] <Effects of Embodiment 1> According to Embodiment 1, the following effects are achieved.

[0066] As shown in Figures 1-4, the cantilever 21 comprises a plate portion 21a extending in one direction with a predetermined width and deformable in the thickness direction, a support portion 21c formed by laminating an active layer 201 common to the plate portion 21a, a BOX layer 202 and a base layer 203 (other layers), and a piezoelectric element 21b arranged in at least the longitudinal direction of the plate portion 21a. Two inclined portions C1 are formed side by side in the width direction of the plate portion 21a at the boundary B1 of the support portion 21c on the plate portion 21a side, approaching each other as they move toward the plate portion 21a, and the two edges of the plate portion 21a in the width direction are connected to the two inclined portions C1 respectively. Furthermore, in a plan view, a recess R1 is formed in the center between the two inclined portions C1 at the boundary B1, recessed inward from the support portion 21c, and two protrusions P1 projecting toward the plate portion 21a are formed side by side in the width direction.

[0067] When the plate portion 21a is driven, the stress generated at the connection between the plate portion 21a and the support portion 21c is greatest at both ends E1 of this connection portion. In contrast, with the above configuration, since the two edges of the plate portion 21a in the width direction are connected to the two inclined portions C1 respectively, the stress generated at both ends E1 of the connection portion when the plate portion 21a is driven is distributed along the inclined portions C1, thereby suppressing the stress generated at both ends E1 of the connection portion. Therefore, it is possible to suppress the failure of the support portion 21c when the plate portion 21a is driven. In addition, in a plan view, a recess R1 is formed in the center between the two inclined portions C1 at the boundary B1, recessed inward from the support portion 21c, so the effective area of ​​the piezoelectric element 21b can be extended into the recess R1. Therefore, the driving efficiency of the cantilever 21 can be maintained at a high level. Thus, with the above configuration, it is possible to maintain a high driving efficiency while suppressing element failure during driving.

[0068] As shown in Figures 2 and 4, the two inclined sections C1 each have a linear shape in a plan view.

[0069] With this configuration, the stress generated at both ends E1 of the connection between the plate portion 21a and the support portion 21c when the plate portion 21a is driven can be distributed along the linear inclined portion C1.

[0070] As shown in Figure 4, the two protrusions P1 each have a trapezoidal shape with rounded corners when viewed from above.

[0071] With this configuration, the end of the protrusion P1 (the part corresponding to the upper base of the trapezoid) has width, which suppresses stress concentration at this end when the plate portion 21a is driven. Also, by rounding the corners of the trapezoid, stress concentration at these corners can be suppressed. Therefore, it is possible to suppress element failure in the cantilever 21 due to stress concentration when the plate portion 21a is driven.

[0072] As shown in Figure 4, the two protrusions P1 are spaced apart from each other with a gap between them.

[0073] This configuration allows the effective area of ​​the piezoelectric element 21b to be extended to the gap between the two protrusions P1. Therefore, the driving efficiency of the cantilever 21 can be increased.

[0074] As shown in Figure 1, the drive element 1 comprises a movable part 40, a drive unit 20 that rotates the movable part 40 about a pivot axis R10, and a base 10 that supports the drive unit 20. The drive unit 20 is composed of a plurality of cantilevers 21 connected in a meander shape. In at least one of the plurality of cantilevers 21, two inclined parts C1 are formed side by side in the width direction of the plate part 21a at the boundary B1 on the plate part 21a side of the support part 21c, and the two edges of the plate part 21a in the width direction are connected to the two inclined parts C1, respectively. Furthermore, in plan view, a recess R1 is formed in the center between the two inclined parts C1 at the boundary B1, recessed inward from the support part 21c, and two protrusions P1 projecting toward the plate part 21a are formed side by side in the width direction. The support part 21c of the cantilever 21 furthest from the movable part 40 is connected to the base 10.

[0075] With this configuration, at least one cantilever 21 that attempts to suppress the maximum stress is configured as described above, so that the drive efficiency of the cantilever 21 can be maintained at a high level while suppressing element failure of the cantilever 21. Therefore, the plate portion 21a of the cantilever 21 can be deformed significantly, and the rotation angle of the movable portion 40 can be increased.

[0076] In this case, at least one cantilever 21 may be the cantilever 21 furthest from the movable part 40.

[0077] With this configuration, when the drive element 1 is subjected to an impact in the thickness direction due to a fall or the like, the greatest stress is generated at the cantilever 21, which is furthest from the movable part 40. Therefore, by applying the above configuration to at least the support part 21c of the cantilever 21, it is possible to maintain high driving efficiency in the cantilever 21 while suppressing element failure of the cantilever 21 when an impact is applied.

[0078] As shown in Figure 1, a reflective surface 40a that reflects incident light is located on the movable part 40.

[0079] With this configuration, the drive element 1 can be used as a deflector. Furthermore, as described above, the rotation angle of the movable part 40 can be increased, thus increasing the scanning angle of the deflector.

[0080] As shown in Figure 1, a pair of drive units 20 are arranged parallel to the pivot axis R10, flanking the movable part 40, and each drive unit 20 is connected to the movable part 40 to provide driving force to the movable part 40.

[0081] With this configuration, the movable part 40 can be stably driven by a pair of drive units 20.

[0082] <Example of changes> In Embodiment 1, the boundary B1 on the plate portion 21a side of the support portion 21c had a shape consisting of two convex portions P1 with rounded corners of a trapezoid and a recess R1 provided between the two convex portions P1, but the shape of the boundary B1 is not limited to this.

[0083] For example, as shown in Figure 11(a), the shape of the two protrusions P1 may be a trapezoid with unrounded corners. In this case as well, since the two edges in the width direction of the plate portion 21a are connected to the inclined portions C1 of the two protrusions P1, stress in the BOX layer 202 near these two edges can be suppressed. However, if the shape of the two protrusions P1 has corners, there is a concern that the stress dispersed from the two edges in the width direction of the plate portion 21a will concentrate near the corners, causing large stress in the BOX layer 202 near the corners. Therefore, in order to more thoroughly suppress the generation of large stress in the BOX layer 202 at the support portion 21c of the outermost cantilever 21, it is preferable that the shape of the two protrusions P1 has rounded corners.

[0084] Furthermore, in the above embodiment 1, the shapes of the two protrusions P1 were symmetrical with respect to each other in the width direction of the plate portion 21a, and the shapes of each protrusion P1 were symmetrical. However, as shown in Figure 11(b), for example, the shapes of each protrusion P1 may be asymmetrical in the width direction of the plate portion 21a. In this configuration as well, the stress generated in the BOX layer 202 near the two edges in the width direction of the plate portion 21a is distributed on the sides of the protrusions P1, thereby suppressing the generation of large stresses in the BOX layer 202.

[0085] Furthermore, as shown in Figures 11(c) and (d), the depth D1 of the recess R1 may be set to be greater than the height H1 of each protrusion P1. In Figure 11(c), the angles of the two inclined portions with respect to the XZ plane are the same for each protrusion P1, while in Figure 11(d), the angles of the two inclined portions with respect to the XZ plane are different for each protrusion P1. With this configuration, the effective area of ​​the piezoelectric element 21b can be further widened compared to the configuration of Embodiment 1. Therefore, the driving efficiency of the cantilever 21 can be further increased.

[0086] Furthermore, in the configurations shown in Figures 11(b) to (d), it is preferable that the corners of each protrusion P1 be rounded. This helps to suppress the generation of large stresses in the BOX layer 202 near the corners.

[0087] Furthermore, the shape of the protrusion P1 is not limited to a trapezoid or a trapezoid with rounded corners; it may be any other shape.

[0088] For example, the shapes of the two protrusions P1 may each be circular arcs as shown in Figure 12(a) in a plan view, or ellipses as shown in Figure 12(b), or shapes other than elliptical arcs with gradually changing curvature as shown in Figure 12(c). The shapes of the protrusions P1 in Figures 12(b) and (c) are bow-shaped, and the shapes of each protrusion P1 in Figure 12(c) are asymmetrical in the width direction of the plate portion 21a.

[0089] In Figures 12(a) to (c), the two inclined sections C1 each have a curved shape that is convex outward from the support section 21c in a plan view.

[0090] With this configuration, the stress generated at both ends E1 of the connection between the plate portion 21a and the support portion 21c when the plate portion 21a is driven can be distributed along the curved inclined portion C1. Furthermore, when the angle between the two edges of the plate portion 21a and the two inclined portions C1 in the width direction is set to an angle suitable for stress suppression, the height H1 of the convex portion P1 can be made smaller compared to when the inclined portion C1 is straight. As a result, the effective area of ​​the piezoelectric element 21b can be expanded compared to when the inclined portion C1 is straight, and the driving efficiency of the cantilever 21 can be increased.

[0091] In Figures 12(a) to (c), the two protrusions P1 each have an arc or bow shape in a plan view.

[0092] With this configuration, since the protrusion P1 has no corners, stress concentration is less likely to occur at the boundary B1 between the plate portion 21a and the support portion 21c when the plate portion 21a is driven. Therefore, it is possible to suppress element failure in the cantilever 21 due to stress concentration when the plate portion 21a is driven.

[0093] Furthermore, as shown in Figure 12(d), the shapes of the two protrusions P1 may include an arc shape and a straight line shape, respectively, in a plan view.

[0094] In addition, in the configurations shown in Figures 12(a) to (d), the depth D1 of the recess R1 may be set to be greater than the height H1 of each protrusion P1, similar to the configurations shown in Figures 11(c) and (d).

[0095] <Embodiment 2> In Embodiment 1, the drive element 1 included multiple cantilevers 21, but the drive element may be composed of a single cantilever. Such a cantilever will be described below.

[0096] Figure 13 is a perspective view showing the configuration of the cantilever 2 according to Embodiment 2.

[0097] In Embodiment 2, components similar to those in Embodiment 1 are given the same numbering as in Embodiment 1 for convenience. The cantilever 2 comprises a plate portion 21a, a piezoelectric element 21b, and a support portion 21c. Compared to the cantilever 21 on the X-axis positive side in Embodiment 1, the drive end 21d of the cantilever 2 in Embodiment 2 is omitted. In Embodiment 2 as well, when a drive voltage is applied to the piezoelectric element 21b, the piezoelectric layer 212 within the piezoelectric element 21b deforms due to the inverse piezoelectric effect, causing the plate portion 21a to bend. As a result, the Y-axis negative end of the plate portion 21a vibrates in the Z-axis direction.

[0098] In Embodiment 2, since the two edges of the plate portion 21a in the width direction are connected to the two inclined portions C1 respectively, the stress generated at both ends E1 of the connection portion when the plate portion 21a is driven is distributed along the inclined portions C1, thereby suppressing the stress generated at both ends E1 of the connection portion. Therefore, it is possible to suppress the failure of the support portion 21c when the plate portion 21a is driven. In addition, at the boundary of the support portion 21c on the plate portion 21a side, a recess R1 is formed in the center between the two inclined portions C1 in a plan view, so that the effective area of ​​the piezoelectric element 21b can be extended into the recess R1. Therefore, the driving efficiency of the cantilever 2 can be maintained at a high level. Thus, with the above configuration, it is possible to maintain a high driving efficiency while suppressing element failure during driving.

[0099] <Other examples of changes> In the above embodiments 1 and 2 and their modifications, the ribs 31 were formed over the entire area of ​​the support portion 21c in a plan view. However, the invention is not limited to this, and the ribs 31 may not be formed over a portion of the support portion 21c on the opposite side of the boundary B1 in a plan view.

[0100] In the embodiments 1 and 2 and the modified examples described above, the piezoelectric element 21b was positioned not only on the plate portion 21a but also on the upper surface of the support portion 21c. However, it is not necessary for the piezoelectric element to be positioned on the upper surface of the support portion 21c. For example, the end of the piezoelectric element 21b on the support portion 21c side may be shaped to follow the boundary B1 in a plan view.

[0101] In the above embodiment 1 and its modifications, as described above, the boundary on the plate portion 21a side of the support portion 21c of the other cantilevers, except for the cantilever 21 furthest from the movable portion 40 (the outer cantilever), does not have a convex portion P1 or a concave portion R1, and the boundary is planar in shape. However, as described above, in order to suppress the maximum stress generated in the BOX layer 202 due to the rotation of the movable portion 40, the boundary B1 on the plate portion 21a side of the support portion 21c and drive end 21d of the other cantilevers 21 may be shaped as shown in Figure 4, with the widthwise edge of the plate portion 21a connected to the two inclined portions C1 of this boundary B1, as shown in Figure 14. The configuration in Figure 4 is not limited to the outermost cantilever 21, but can be applied to any cantilever 21 that seeks to suppress the maximum stress from various viewpoints.

[0102] In the above embodiment 1 and its modifications, the plate portion 21a extends in a direction perpendicular to the rotation axis R10, but it is not limited to this; it may extend in a direction substantially perpendicular to the rotation axis R10. For example, the plate portion 21a may extend in a direction slightly inclined from the direction perpendicular to the rotation axis R10. Also, the support portion 21c and the drive end 21d extend in a direction parallel to the rotation axis R10, but it is not limited to this; they may extend in a direction substantially parallel to the rotation axis R10. For example, the support portion 21c and the drive end 21d may extend in a direction slightly inclined from the direction parallel to the rotation axis R10.

[0103] In addition, the embodiments of the present invention can be modified in various ways as appropriate within the scope of the technical idea set forth in the claims.

[0104] (Note) The above description of embodiments discloses the following technologies.

[0105] (Technology 1) A plate portion that extends in one direction with a predetermined width and is deformable in the thickness direction, A support portion is formed by laminating a common layer with the aforementioned plate portion and other layers, The device comprises a piezoelectric element arranged in a range at least in the longitudinal direction of the plate portion, Two inclined portions are formed at the boundary of the support portion on the plate portion side, which approach each other as they move toward the plate portion, and these portions are arranged in the width direction of the plate portion. The two edges of the plate portion in the width direction are connected to the two inclined portions, respectively. Furthermore, in a plan view, the boundary has a recess formed in the center between the two inclined portions, which is recessed inward from the support portion, and two protrusions are formed side by side in the width direction, projecting toward the plate portion. A cantilever characterized by the following features.

[0106] When the plate is driven, the stress generated at the connection between the plate and the support is greatest at both ends of this connection. In contrast, with the cantilever of the above technology, the two edges of the plate in the width direction are connected to two inclined sections, respectively. Therefore, the stress generated at both ends of the connection when the plate is driven is distributed along the inclined sections, thereby suppressing the stress at both ends of the connection. Thus, it is possible to suppress the failure of the support when the plate is driven. Furthermore, in a plan view, a recess is formed in the center between the two inclined sections at the boundary, recessed inward from the support. This allows the effective area of ​​the piezoelectric element to be extended into the recess. Thus, the driving efficiency of the cantilever can be maintained at a high level. Consequently, with the cantilever of the above technology, it is possible to maintain high driving efficiency while suppressing element failure during driving.

[0107] (Technology 2) In the cantilever described in Technical 1, The two inclined portions each have a linear shape in a plan view. A cantilever characterized by the following features.

[0108] This technology allows the stress generated at both ends of the connection between the plate and the support when the plate is driven to be distributed along the linearly shaped inclined section.

[0109] (Technology 3) In the cantilever described in Technology 1 or 2, Each of the two inclined portions has a curved shape that is convex outward from the support portion in a plan view. A cantilever characterized by the following features.

[0110] This technology allows the stress generated at both ends of the connection between the plate and the support during plate movement to be distributed along the curved inclined section. Furthermore, when the angle between the two edges of the plate and the two inclined sections in the width direction is set to an angle suitable for stress suppression, the height of the protrusion can be reduced compared to when the inclined section is straight. As a result, the effective area of ​​the piezoelectric element can be expanded compared to when the inclined section is straight, and the driving efficiency of the cantilever can be improved.

[0111] (Technology 4) In the cantilever described in any one of the techniques 1 to 3, The two convex portions each have a trapezoidal or trapezoidal shape with rounded corners when viewed from above. A cantilever characterized by the following features.

[0112] This technology allows the ends of the convex portion (corresponding to the upper base of the trapezoid) to have width, thereby suppressing stress concentration at these ends when the plate portion is driven. Furthermore, rounding the corners of the trapezoid also suppresses stress concentration at these corners. Therefore, it is possible to suppress element failure in the cantilever due to stress concentration when the plate portion is driven.

[0113] (Technology 5) In a cantilever described in any one of the techniques 1 through 4, The two convex portions each have an arc or bow shape in a plan view. A cantilever characterized by the following features.

[0114] According to this technology, because there are no corners on the protruding part, stress concentration is less likely to occur at the boundary between the plate part and the support part when the plate part is driven. Therefore, it is possible to suppress element failure in the cantilever due to stress concentration when the plate part is driven.

[0115] (Technology 6) In a cantilever described in any one of the techniques 1 through 5, The two protrusions are spaced apart from each other with a gap between them. A cantilever characterized by the following features.

[0116] This technology allows the effective area of ​​the piezoelectric material to be extended to the gap between the two protrusions. Therefore, the driving efficiency of the cantilever can be increased.

[0117] (Technology 7) Movable parts and A drive unit that rotates the movable part on the pivot axis, The drive unit comprises a base that supports the drive unit, The aforementioned drive unit is configured by connecting multiple cantilevers in a meander shape, At least one of the aforementioned multiple cantilevers is a cantilever described in any one of the technical specifications 1 to 6. The support portion of the cantilever furthest from the movable portion is connected to the base. A driving element characterized by the following features.

[0118] According to the drive element of this technology, since the cantilever of the above technology is used in at least one cantilever that attempts to suppress the maximum stress, it is possible to suppress element failure of the cantilever while maintaining high driving efficiency in the cantilever. Therefore, the plate portion of the cantilever can be deformed significantly, and the rotation angle of the movable part can be increased.

[0119] (Technology 8) In the driving element described in Technology 7, The at least one cantilever is the cantilever furthest from the movable part. A driving element characterized by the following features.

[0120] According to this technology, when an impact is applied to the drive element in the thickness direction due to a fall or the like, the greatest stress is generated in the cantilever furthest from the movable part. Therefore, by applying the configuration described in any of the above technologies 1 to 6 to at least the support part of this cantilever, it is possible to maintain high driving efficiency in the cantilever while suppressing element failure of the cantilever when an impact is applied.

[0121] (Technology 9) In the driving element described in Technical 7 or 8, A reflective surface that reflects incident light is positioned in the movable part. A driving element characterized by the following features.

[0122] This technology allows the drive element to be used as a deflector. Furthermore, as described above, the rotation angle of the movable part can be increased, thus increasing the scanning angle of the deflector.

[0123] (Technology 10) In the driving element described in any one of the technical items 7 to 9, A pair of the aforementioned drive units are arranged parallel to the pivot axis, sandwiching the movable unit. Each of the aforementioned drive units is connected to the movable unit and provides driving force to the movable unit. A driving element characterized by the following features.

[0124] This technology allows a pair of drive units to stably drive the movable parts.

[0125] (Technology 11) A plate portion that extends in one direction with a predetermined width and is deformable in the thickness direction, A support portion is formed by laminating a common layer with the aforementioned plate portion and other layers, The device comprises a piezoelectric element arranged in a range at least in the longitudinal direction of the plate portion, Two inclined portions are formed at the boundary of the support portion on the plate portion side, which approach each other as they move toward the plate portion, and these portions are arranged in the width direction of the plate portion. The two edges of the plate portion in the width direction are connected to the two inclined portions, respectively. A cantilever characterized by the following features.

[0126] When the plate is driven, the stress generated at the connection between the plate and the support is greatest at both ends of this connection. In contrast, with the cantilever of the above technology, the two edges of the plate in the width direction are connected to two inclined sections, respectively. Therefore, the stress generated at both ends of the connection when the plate is driven is distributed along the inclined sections, thereby suppressing the stress generated at both ends of the connection. Thus, it is possible to suppress the failure of the support when the plate is driven, and to suppress the failure of the element when it is driven.

[0127] (Technology 12) In the cantilever described in Technical 11, In a plan view, the boundary has a recess formed in the center between the two inclined portions, which is recessed inward from the support portion, and two protrusions that project toward the plate portion are formed side by side in the width direction. A cantilever characterized by the following features.

[0128] According to this technology, a recess is formed at the boundary, in a plan view, between the two inclined sections, with the support section recessed inward. This allows the effective area of ​​the piezoelectric element to extend into the recess. Therefore, the driving efficiency of the cantilever can be maintained at a high level. [Explanation of Symbols]

[0129] 1. Driving element 2. Cantilever 10 base 20 Drive unit 21 Cantilever 21a Plate part 21b Piezoelectric material 21c Support part 40 Moving parts 40a reflective surface 201 Active layer (common layer) 202 BOX layer (other layers) 203 Base layer (other layers) B1 boundary C1 Slope P1 protrusion R1 recess R10 pivot axis

Claims

1. A plate portion that extends in one direction with a predetermined width and is deformable in the thickness direction, A support portion is formed by laminating a common layer with the aforementioned plate portion and other layers, The device comprises a piezoelectric element arranged in a range at least in the longitudinal direction of the plate portion, Two inclined portions are formed at the boundary of the support portion on the plate portion side, which approach each other as they move toward the plate portion, and these portions are arranged in the width direction of the plate portion. The two edges of the plate portion in the width direction are connected to the two inclined portions, respectively. Furthermore, in a plan view, the boundary has a recess formed in the center between the two inclined portions, which is recessed inward from the support portion, and two protrusions that project toward the plate portion are formed side by side in the width direction. A cantilever characterized by the following features.

2. In the cantilever according to claim 1, The two inclined portions each have a linear shape in a plan view. A cantilever characterized by the following features.

3. In the cantilever according to claim 1, Each of the two inclined portions has a curved shape that is convex outward from the support portion when viewed from above. A cantilever characterized by the following features.

4. In the cantilever according to claim 1, The two convex portions each have a trapezoidal or trapezoidal shape with rounded corners when viewed from above. A cantilever characterized by the following features.

5. In the cantilever according to claim 1, The two convex portions each have an arc or bow shape in a plan view. A cantilever characterized by the following features.

6. In the cantilever according to claim 1, The two protrusions are spaced apart from each other with a gap between them. A cantilever characterized by the following features.

7. Movable parts and A drive unit that rotates the movable part on the pivot axis, The drive unit comprises a base that supports the drive unit, The aforementioned drive unit is configured by connecting multiple cantilevers in a meander shape, At least one of the plurality of cantilevers is a cantilever according to any one of claims 1 to 6. The support portion of the cantilever furthest from the movable portion is connected to the base. A driving element characterized by the following features.

8. In the drive element according to claim 7, The at least one cantilever is the cantilever furthest from the movable part. A driving element characterized by the following features.

9. In the drive element according to claim 7, A reflective surface that reflects incident light is positioned in the movable part. A driving element characterized by the following features.

10. In the drive element according to claim 7, A pair of the aforementioned drive units are arranged parallel to the pivot axis, sandwiching the movable unit. Each of the aforementioned drive units is connected to the movable unit and provides driving force to the movable unit. A driving element characterized by the following features.

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