Drive element and light deflection element

Abstract

A drive element (1) is provided with: a movable part (30); a first support part (11) extending along the rotation axis (R0) of the movable part (30), one end of the first support part (11) being connected to the movable part (30); a pair of arms (12) disposed across the rotation axis (R0); a pair of connecting parts (13) that connect the pair of arm parts (12) and the other end of the first support part (11); a second support part (14) which extends along the rotation axis (R0) and supports the pair of connecting parts (13); a fixing part (15) connected to the second support part (14); and a drive unit (16) that drives the arm unit (12). The rigidity of the second support section (14) is higher than the rigidity of the first support section (11), and the pair of connecting sections (13) are disposed so as to be inclined toward the movable section (30) side. The angle formed by each connecting part (13) and the second supporting part (14) is larger than 90 degrees and smaller than 135 degrees.

Description

Technical Field

[0001] The present invention relates to a driving element for rotating a movable part around a rotation axis and a light deflecting element using the driving element. Background Art

[0002] In recent years, a driving element has been developed that uses MEMS (Micro Electro Mechanical System) technology to rotate a movable part. In this driving element, by configuring a reflective surface on the movable part, the light incident on the reflective surface can be scanned at a predetermined swing angle. This driving element is mounted on image display devices such as head-up displays and head-mounted displays. In addition, laser radars that use lasers to detect objects can also use this driving element.

[0003] The following patent document 1 describes a driving element in which a movable part is rotated by using a so-called tuning fork vibrator. In the driving element, the movable part is connected to the tuning fork vibrator by using a first connecting body extending along the rotation axis. In addition, the tuning fork vibrator is vertically connected to a second connecting body extending along the rotation axis. The second connecting body is connected to a base. The base constitutes a fixing part for fixing the driving element to the surface on which it is installed. By driving the tuning fork vibrator, the movable part rotates around the rotation axis, and accordingly, the reflecting surface arranged on the movable part rotates.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2019-082625 Summary of the invention

[0007] Problem that the invention aims to solve

[0008] In the driving element of the above structure, the driving efficiency of the movable part can be improved by making the stiffness of the second connecting body higher than the stiffness of the first connecting body. However, due to the difference in stiffness, when the movable part is driven, stress concentration occurs at the connection position between the second connecting body and the tuning fork vibrator, which may cause the driving element to be damaged starting from the stress concentration position. In addition, due to such a difference in stiffness, the first connecting body and the second connecting body have different eases of rotation. Therefore, in a structure in which the tuning fork vibrator is vertically connected to the second connecting body as in the above-mentioned patent document 1, the torque generated by the tuning fork vibrator is difficult to be smoothly transmitted to the first connecting body. Therefore, the driving efficiency of the movable part is reduced.

[0009] In view of the above problems, an object of the present invention is to provide a driving element and a light deflection element capable of improving the driving efficiency of a movable portion while suppressing stress generated when the movable portion is driven.

[0010] Solutions for solving problems

[0011] The first technical solution of the present invention relates to a driving element. The driving element of this technical solution includes: a movable part; a first supporting part extending along the rotation axis of the movable part, one end of the first supporting part being connected to the movable part; a pair of arm parts arranged across the rotation axis; a pair of connecting parts connecting the pair of arm parts and the other end of the first supporting part; a second supporting part extending along the rotation axis and supporting the pair of connecting parts; a fixed part connected to the second supporting part; and a driving part driving the arm parts. The rigidity of the second supporting part is higher than that of the first supporting part, and the pair of connecting parts are arranged in a manner inclined toward the movable part. The angle formed by each connecting part and the second supporting part is greater than 90° and less than 135°.

[0012] According to the driving element of the technical solution, the pair of connecting parts are arranged in a manner inclined toward the movable part, and the angle formed by each connecting part and the second supporting part is greater than 90° and less than 135°. Therefore, even if the rigidity of the second supporting part is higher than that of the first supporting part, the stress generated at the connection position between the connecting part and the second supporting part when the movable part is driven can be suppressed, and the torque generated by the pair of arm parts can be efficiently transmitted to the first supporting part. Therefore, the driving efficiency of the movable part can be effectively improved while suppressing the stress generated when the movable part is driven.

[0013] A second aspect of the present invention relates to a light deflection element. The light deflection element of this aspect includes: the driving element according to the first aspect; and a reflecting surface disposed on the movable portion.

[0014] According to the light deflection element of this technical aspect, since it includes the driving element of the first technical aspect, it is possible to improve the driving efficiency of the movable part. Therefore, it is possible to efficiently deflect and scan light at a large swing angle by using the reflection surface.

[0015] Effects of the Invention

[0016] As described above, according to the present invention, it is possible to provide a driving element and a light deflection element capable of improving the driving efficiency of the movable portion while suppressing stress generated when the movable portion is driven.

[0017] The effects and significance of the present invention will become more apparent through the description of the following embodiments. However, the following embodiments are merely examples of implementing the present invention, and the present invention is not limited in any way to the contents described in the following embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1It is a perspective view showing the structure of the driving element according to the first embodiment.

[0019] Figure 2 It is a plan view showing the structure of the driving element according to the first embodiment.

[0020] Figure 3 It is a perspective view showing the structure of a driving element of a comparative example.

[0021] Figure 4 This is a top view of the driving element for explaining the simulation conditions of the first embodiment.

[0022] Figure 5 This is a diagram schematically showing the resonance mode used in the simulation of the first embodiment.

[0023] Figure 6 This is a graph showing simulation results of the maximum stress and the swing angle in the first embodiment.

[0024] Figure 7 It is a plan view showing the structure of the driving element in the case where the angle formed by the connecting portion and the second supporting portion according to the first embodiment is 150 degrees.

[0025] Figure 8 It is a top view showing the structure of the driving element according to the second embodiment.

[0026] Fig. 9 This is a graph showing simulation results of the swing angle according to the second embodiment.

[0027] Fig.10 It is a perspective view showing the structure of a driving element according to the third embodiment.

[0028] Fig.11 (a) is a plan view showing the structure of the first driving unit of the driving element according to Modification Example 1. Fig.11 (b) is a plan view showing the structure of the first driving unit of the driving element according to Modification Example 2.

[0029] Fig.12 (a) is a plan view showing the structure of the first driving unit of the driving element according to Modification Example 3. Fig.12 (b) is a plan view showing the structure of the first driving unit of the driving element according to Modification Example 4.

[0030] However, the drawings are provided for illustration purposes only and are not intended to limit the scope of the present invention. DETAILED DESCRIPTION

[0031] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0032] In the following embodiments, a light deflection element is formed by configuring a reflective surface on the movable part of the driving element. For convenience, mutually orthogonal X-axis, Y-axis, and Z-axis are indicated in each figure. The Y-axis direction is parallel to the rotation axis of the driving element, and the Z-axis direction is perpendicular to the reflective surface configured on the movable part.

[0033] <Implementation method 1>

[0034] Figure 1 is a perspective view showing the structure of the driving element 1. Figure 2 FIG. 1 is a top view showing the structure of the driving element 1. Figure 2 ] A top view of the driving element 1 as viewed from the lower surface side (Z-axis negative side) is shown in FIG.

[0035] like Figure 1 and Figure 2 As shown, the driving element 1 includes a first driving unit 10, a second driving unit 20, and a movable portion 30. The light deflection element 2 is formed by arranging a reflection surface 40 on the upper surface of the movable portion 30. The driving element 1 has a symmetrical shape in the X-axis direction and the Y-axis direction in a plan view.

[0036] The first drive unit 10 and the second drive unit 20 rotate the movable part 30 around the rotation axis R0 according to a drive signal supplied from a drive circuit not shown. The reflective surface 40 reflects light incident from above the movable part 30 in a direction corresponding to the swing angle of the movable part 30. Thus, the light (such as laser light) incident on the reflective surface 40 is deflected and scanned as the movable part 30 rotates. The movable part 30 and the reflective surface 40 can be formed by the same member.

[0037] The first driving unit 10 includes a first supporting portion 11 , a pair of arm portions 12 , a pair of connecting portions 13 , a second supporting portion 14 , a fixing portion 15 , and a driving portion 16 .

[0038] The first support portion 11 extends along the rotation axis R0 of the movable portion 30, and one end thereof (the end on the negative side of the Y axis) is connected to the movable portion 30. The first support portion 11 is in the shape of a rod. The width of the first support portion 11 in the X-axis direction is constant except for the two ends. The width of the two ends of the first support portion 11 gradually widens. The cross section when the center of the first support portion 11 is cut by the X-Z plane is approximately square. The cross-sectional shape of the first support portion 11 may also be other shapes such as a circle.

[0039] The pair of arm portions 12 are symmetrically arranged with the rotation axis R0 interposed therebetween. The pair of arm portions 12 extend parallel to the rotation axis R0. Each arm portion 12 is a substantially rectangular shape with rounded corners on the negative side of the Y axis in a plan view.

[0040] A pair of connecting parts 13 connects the pair of arm parts 12 and the other end of the first support part 11 (the end on the positive side of the Y axis). The pair of connecting parts 13 extend in a manner separated from the rotation axis R0 in the positive and negative directions of the X axis. In more detail, the direction in which the pair of connecting parts 13 extend is not perpendicular to the rotation axis R0, but is inclined in a direction close to the movable part 30 (negative direction of the Y axis) relative to the direction perpendicular to the rotation axis R0. That is, the pair of connecting parts 13 are arranged in a manner inclined toward the movable part 30 side. The pair of connecting parts 13 are arranged in a manner that the top end is farther from the rotation axis R0 than the root. The width of the connecting part 13 in the horizontal direction perpendicular to the direction in which the connecting part 13 extends is constant except for the two ends.

[0041] The second support portion 14 extends along the rotation axis R0 and supports the pair of connecting portions 13. The width of the second support portion 14 in the X-axis direction is constant except for the end portion on the fixing portion 15 side. The width of the end portion of the first support portion 11 on the fixing portion 15 side gradually increases. The second support portion 14 is connected to the fixing portion 15.

[0042] The fixing part 15 is used to fix the driving element 1 to the installation surface. The thickness of the ends on the positive and negative sides of the X axis and the end on the positive side of the Y axis of the fixing part 15 is thicker than the thickness of other parts. The thicker parts are provided on the installation surface.

[0043] The two driving parts 16 drive the pair of arm parts 12 , respectively. The two driving parts 16 are piezoelectric driving bodies. The two driving parts 16 are formed on the upper surfaces of the pair of arm parts 12 , respectively.

[0044] The second drive unit 20 includes a first support portion 21, a pair of arm portions 22, a pair of connecting portions 23, a second support portion 24, a fixing portion 25, and a drive portion 26. The structure of the second drive unit 20 is the same as that of the first drive unit 10. The first drive unit 10 and the second drive unit 20 are arranged in opposite directions to each other with the movable portion 30 interposed therebetween. The first support portion 11 of the first drive unit 10 and the first support portion 21 of the second drive unit 20 are respectively connected to the movable portion 30.

[0045] A tuning fork vibrator is formed by a pair of arm portions 12 and a connecting portion 13. In addition, a tuning fork vibrator is formed by a pair of arm portions 22 and a connecting portion 23. In the first drive unit 10, the pair of arm portions 12 are driven by two drive portions 16, so that the first support portion 11 rotates around the rotation axis R0. In addition, in the second drive unit 20, the pair of arm portions 22 are driven by two drive portions 26, so that the first support portion 21 rotates around the rotation axis R0. By controlling the rotation directions of the first support portions 11 and 21 to be the same direction, the movable portion 30 rotates.

[0046] The driving parts 16 and 26 are composed of piezoelectric driving bodies. The driving parts 16 and 26 (piezoelectric driving bodies) have a laminated structure in which electrode layers are arranged above and below piezoelectric thin films 16a and 26a of a predetermined thickness.

[0047] The piezoelectric thin films 16a and 26a are formed of a piezoelectric material having a relatively high piezoelectric constant, such as lead zirconate titanate (PZT). The electrodes are formed of a material having a relatively low electrical resistance and a relatively high heat resistance, such as platinum (Pt). A layer structure including the piezoelectric thin films 16a and 26a and upper and lower electrodes is formed on the upper surfaces of the arms 12 and 22 by a sputtering method or the like, thereby configuring a piezoelectric driver on the upper surfaces of the respective parts.

[0048] The substrate of the driving element 1 has the same contour as the driving element 1 when viewed from above and has a constant thickness. The reflecting surface 40 and the driving parts 16 and 26 (piezoelectric driving bodies) are arranged in corresponding areas on the upper surface of the substrate. In addition, layers 15a and 25a formed of a predetermined material are formed on the lower surface of the substrate in an area corresponding to the periphery of the fixing parts 15 and 25, and the thickness of the fixing parts 15 and 25 is increased. Therefore, the thickness of the driving element 1 is constant in areas other than the areas where the layers 15a and 25a are formed. The material of the layers 15a and 25a may be a material different from that of the substrate, or may be the same material as that of the substrate.

[0049] The substrate is formed integrally of silicon or the like, for example. However, the material constituting the substrate is not limited to silicon, and may be other materials. The material constituting the substrate is preferably a material having high mechanical strength and Young's modulus, such as metal, crystal, glass, resin, etc. As such a material, titanium, stainless steel, elinvar, brass alloy, etc. may be used in addition to silicon. The material of the layers 15a, 25a of the fixing portions 15, 25 is also the same.

[0050] In addition, Figure 1 , Figure 2 In the driving element 1 shown, the width of the second supporting parts 14 and 24 in the X-axis direction is made wider than the width of the first supporting parts 11 and 21 in the X-axis direction, so that the rigidity of the second supporting parts 14 and 24 around the rotation axis R0 is higher than that of the first supporting parts 11 and 21. By making the rigidity of the second supporting parts 14 and 24 higher than that of the first supporting parts 11 and 21, the driving efficiency of the movable part 30 can be improved. However, on the other hand, if the rigidity of the second supporting parts 14 and 24 is made higher than that of the first supporting parts 11 and 21, stress is generated at the connection position between the second supporting parts 14 and 24 and the connecting parts 13 and 23 when the movable part 30 is driven.

[0051] Figure 3 It is a perspective view showing the structure of a driving element 1 according to a comparative example.

[0052] In the comparative example, the direction in which the pair of connecting parts 13 extend is Figure 1 The other structures of the comparative example are the same as those of the first embodiment.

[0053] In the comparative example, a pair of connecting parts 13 extend in a manner separated from the rotation axis R0 in the positive and negative directions of the X axis, and the extending direction is perpendicular to the rotation axis R0. Similarly, a pair of connecting parts 23 extend in a manner separated from the rotation axis R0 in the positive and negative directions of the X axis, and the extending direction is perpendicular to the rotation axis R0. That is, a pair of connecting parts 13 and a pair of connecting parts 23 are respectively connected to the second supporting parts 14 and 24 perpendicularly. Therefore, the angle θ10 formed by each connecting part 13 and the second supporting part 14 is 90°, and the angle θ10 formed by each connecting part 23 and the second supporting part 24 is also 90°.

[0054] In the case where each connecting portion 13, 23 is vertically connected to the second supporting portion 14, 24, if the rigidity of the second supporting portion 14, 24 is higher than the rigidity of the first supporting portion 11, 21 as described above, then at the connection position of the second supporting portion 14, 24 and the connecting portion 13, 23, that is, Figure 3 A high stress concentration occurs at the position P1. Therefore, the driving element 1 may be damaged starting from the stress concentration portion (position P1).

[0055] In addition, in the structure where the rigidity of the second supporting parts 14 and 24 is higher than that of the first supporting parts 11 and 21 as described above, the first supporting parts 11 and 21 are different from the second supporting parts 14 and 24 in terms of ease of rotation. Therefore, in the structure where the pair of connecting parts 13 and the pair of connecting parts 23 are respectively connected to the second supporting parts 14 and 24 perpendicularly as in the comparative example, the torque generated by the pair of arm parts 12 and the pair of arm parts 22 is difficult to be smoothly transmitted to the first supporting parts 11 and 21, resulting in a decrease in the driving efficiency of the movable part 30.

[0056] Therefore, in the first embodiment, in order to solve these problems, Figure 1 , Figure 2 As shown, the pair of connecting parts 13 and the pair of connecting parts 23 are arranged in a manner inclined toward the movable part 30, and the angle formed by each connecting part 13, 23 and the second supporting part 14, 24 is set to be larger than 90 degrees. As a result, compared with the case where each connecting part 13, 23 is vertically connected to the second supporting part 14, 24 as in the above-mentioned comparative example, the stress generated at the connection position of the second supporting part 14, 24 and the connecting part 13, 23 can be suppressed, and the driving efficiency of the movable part 30 can be improved.

[0057] Hereinafter, verification (simulation) performed by the inventors to confirm such effects will be described.

[0058] Figure 4 It is a figure explaining the simulation conditions.

[0059] exist Figure 4 , a top view of a driving element 1 having the same structure as that of the above-mentioned embodiment 1 is shown. In the simulation, the interval D0 between each arm portion 12, 22 and the first support portion 11, 21 is fixed to a predetermined value. In addition, the resonance frequency of the tuning fork portion U1 composed of a pair of arm portions 12, a pair of connecting portions 13, a second support portion 14 and two driving portions 16 and the resonance frequency of the tuning fork portion U1 composed of a pair of arm portions 22, a pair of connecting portions 23, a second support portion 24 and two driving portions 26 are fixed to predetermined values. The reason is that by making the resonance frequency of the portion composed of these tuning fork portions U1 consistent with the resonance frequency of the portion composed of the first support portions 11, 21 and the movable portion 30, the driving efficiency of the movable portion 30 can be improved.

[0060] Under this condition, the slope of the pair of connecting parts 13 and the slope of the pair of connecting parts 23 are changed, so that the angle θ formed by each connecting part 13, 23 and the second supporting part 14, 24 is changed within a range of 90° or more. Figure 4 , the angle θ is θ11 (120°). As described above, since the resonance frequency of the tuning fork portion U1 is fixed to a predetermined value, the lengths of the arms 12 and 22 also change in accordance with the change in the angle θ. Figure 4 Length L11 of the arm portions 12 and 22 when the angle θ formed is θ11 (120°) is shown in FIG.

[0061] Then, for each angle θ, the maximum stress and the swing angle of the movable part 30 when each tuning fork part U1 is made to resonate are obtained by simulation. Figure 5 As shown, the tuning fork portion U1 resonates in each of the arm portions 12 and 22 in a mode in which the tip and the base move in opposite directions. Figure 5 The arrows in the Z-axis direction indicate the moving directions of the respective parts, and the curved arrows indicate the rotational directions (twisting directions) of the first supporting parts 11 and 21 .

[0062] As for the maximum stress, when each tuning fork portion U1 is resonated in such a manner that the swing angle of the movable portion 30 (the optical full angle of the reflecting surface 40) is 65°, the maximum stress generated at the connection position between the pair of connecting portions 13 and the second supporting portion 14 and the connection position between the pair of connecting portions 23 and the second supporting portion 24 is obtained. In addition, as for the swing angle, the swing angle (optical full angle) when a voltage of 10 Vpp is applied to the driving portions 16 and 26 (piezoelectric driving body) is obtained.

[0063] Figure 6 It is a graph showing the simulation results of the maximum stress and the swing angle.

[0064] Figure 6 The horizontal axis of the graph is the angle between each connecting portion 13, 23 and the second supporting portion 14, 24, that is, the angle θ formed by the above-mentioned. In addition, the vertical axis on the left is the above-mentioned maximum stress, and the vertical axis on the right is the above-mentioned swing angle (optical full angle). The quadrilateral mark represents the maximum stress, and the circular mark represents the swing angle.

[0065] according to Figure 6 From the simulation results, it can be seen that the larger the angle θ is from 90°, the smaller the maximum stress is. On the other hand, in the range where the angle θ is greater than 90 degrees and is below about 115°, the swing angle increases as the angle θ increases, but if the angle exceeds about 115°, the swing angle decreases as the angle θ increases. Moreover, if the angle θ is greater than 135°, the swing angle is smaller than the case of the comparative example where the angle θ is 90°. The reason is that, Figure 7 As shown, the resonance frequency of the tuning fork portion U1 is fixed to a predetermined value, so the lengths of the arms 12 and 22 become shorter as the angle θ increases, and the torque generated by the tuning fork portion U1 decreases. Figure 7 1 shows the length L12 of the arms 12 and 22 when the angle θ is θ12 (150°). Figure 4 The length L11 is much shorter.

[0066] Therefore, according to the above simulation results, it can be said that by setting the angle θ to be greater than 90° and less than about 135°, Figure 3 Compared with the comparative example shown, the maximum stress can be suppressed and the driving efficiency can be improved. Thus, the driving efficiency of the movable part 30 can be effectively improved while suppressing the stress generated when the movable part 30 is driven.

[0067] <Effects of Embodiment 1>

[0068] According to the first embodiment, the following effects can be achieved.

[0069] The pair of connecting parts 13, 23 are arranged in a manner inclined toward the movable part 30, and the angle formed by each connecting part 13, 23 and the second supporting part 14, 24 is set to be greater than 90° and less than 135°. Figure 6 As shown in the simulation results, even when the rigidity of the second supporting parts 14 and 24 is higher than that of the first supporting parts 11 and 21, the stress generated at the connection position between the connecting parts 13 and 23 and the second supporting parts 14 and 24 when the movable part 30 is driven can be suppressed, and the torque generated by the pair of arm parts 12 and 22 can be efficiently transmitted to the first supporting parts 11 and 21. Therefore, the driving efficiency of the movable part 30 can be effectively improved while suppressing the stress generated when the movable part 30 is driven.

[0070] Here, if Figure 6 As shown in the simulation results, the angle formed by each connecting portion 13, 23 and the second supporting portion 14, 24 is preferably set to a range of 110° or more and 120° or less, and more preferably set to a range of 115° or less. Thus, the driving efficiency of the movable portion 30 can be maximized.

[0071] like Figure 1 and Figure 2 As shown in FIG. 1 , the pair of arm portions 12 and the pair of arm portions 22 extend parallel to the rotation axis R0. Thus, the driving element 1 can be made compact in plan view while maintaining a compact appearance. Figure 6 As shown in the simulation results, stress suppression and improvement of the driving efficiency of the movable part 30 are achieved.

[0072] like Figure 1 and Figure 2 As shown, the first drive unit 10 including the first support portion 11, a pair of arm portions 12, a pair of connecting portions 13, the second support portion 14, the fixing portion 15 and the driving portion 16 and the second drive unit 20 including the first support portion 21, a pair of arm portions 22, a pair of connecting portions 23, the second support portion 24, the fixing portion 25 and the driving portion 26 are arranged in opposite directions with the movable portion 30 interposed therebetween, and the first support portions 11 and 21 of each drive unit are connected to the movable portion 30. By supporting and driving the movable portion 30 by each drive unit in this way, the movable portion 30 can be stably driven with a larger torque.

[0073] like Figure 1 As shown in FIG. 1 , the driving parts 16 and 26 include piezoelectric thin films 16 a and 26 a as driving sources, thereby making it possible to smoothly drive the arm parts 12 and 22 .

[0074] like Figure 1 As shown, the light deflection element 2 is composed of the driving element 1 and the reflection surface 40 disposed on the movable part 30. As described above, the driving efficiency of the movable part 30 can be improved, so that the light can be efficiently deflected and scanned by the reflection surface 40 at a large swing angle.

[0075] <Implementation method 2>

[0076] Figure 8 It is a plan view showing the structure of the driving element 1 according to the second embodiment.

[0077] In Embodiment 2, the configuration of the pair of arm portions 12 and the configuration of the pair of arm portions 22 are different from those in Embodiment 1. The other structures of Embodiment 2 are the same as those in Embodiment 1. In Embodiment 2, the driving element 1 also has a shape symmetrical in the X-axis direction and the Y-axis direction when viewed from above. In addition, in Embodiment 2, the light deflection element 2 is also formed by forming the reflection surface 40 on the upper surface of the movable portion 30.

[0078] like Figure 8 As shown, the pair of arm portions 12 and the pair of arm portions 22 are respectively arranged in a manner that the top ends are opened. That is, the pair of arm portions 12 are arranged in a manner that the distance between them is increased toward the top ends. Similarly, the pair of arm portions 22 are arranged in a manner that the distance between them is increased toward the top ends. The pair of arm portions 12, 22 are arranged obliquely with respect to the rotation axis R0 in a manner that the top ends are farther from the rotation axis R0 than the base ends.

[0079] By arranging the pair of arms 12, 22 in this way, the angle (in Figure 8 θ21) is greater than the angle (in Figure 8 In the Figure 8 ] shows a structure in which θ11 is 120° and θ12 is 150°.

[0080] exist Figure 8 In the structure, the distance between the top ends of the pair of arms 12 and 22 and the rotation axis R0 is increased compared to the above embodiment, so a larger change in the moment of inertia can be generated when driving the arms 12 and 22. Thus, the driving efficiency can be further improved compared to the above embodiment 1.

[0081] Fig. 9 It is a graph showing the simulation results of the swing angle.

[0082] Fig. 9 The horizontal axis of the graph is the angle (with Figure 8 In addition, the vertical axis and Figure 6 The vertical axis on the right side of φ is also the swing angle (optical full angle) of the movable part 30 .

[0083] In this simulation, the angle between the connecting parts 13, 23 and the second supporting parts 14, 24 is fixed to Figure 8 The angle formed between the inner side of each arm 12, 22 and the connecting part 13, 23 is changed. Then, the angles formed by each tuning fork U1 at θ11, i.e., 120°, are calculated by simulation. Figure 5 The swing angle of the movable part 30 in the case of mode resonance. As for the swing angle, the swing angle (optical full angle) when a voltage of 10 Vpp is applied to the driving parts 16 and 26 (piezoelectric driving body) is obtained. The other simulation conditions are the same as Figure 6 The same situation.

[0084] exist Fig. 9 In the example, the swing angle when the horizontal axis is 120° is Figure 6 That is, when the horizontal axis is 120°, the pair of arm portions 12, 22 are in a state parallel to the rotation axis R0, and the angle formed by the inner side of the arm portions 12, 22 and the connecting portions 13, 23 is equal to the angle formed by the connecting portions 13, 23 and the second supporting portions 14, 24.

[0085] The range R11 corresponds to a range in which the angle formed by the inner side of the arm portions 12, 22 and the connecting portions 13, 23 is larger than the angle formed by the connecting portions 13, 23 and the second supporting portions 14, 24, that is, 120°. That is, within the range R12, the top ends of the pair of arm portions 12, 22 are farther from the rotation axis R0 than the base. In addition, the range R12 corresponds to a range in which the angle formed by the inner side of the arm portions 12, 22 and the connecting portions 13, 23 is smaller than the angle formed by the connecting portions 13, 23 and the second supporting portions 14, 24, that is, 120°. That is, within the range R12, the top ends of the pair of arm portions 12, 22 are closer to the rotation axis R0 than the base.

[0086] according to Fig. 9 According to the simulation results, the larger the angle formed by the inner side of the arm 12, 22 and the connecting part 13, 23 is than the angle (120°) formed by the connecting part 13, 23 and the second supporting part 14, 24, the larger the swing angle is when the same voltage (10Vpp) is applied, and the higher the driving efficiency of the movable part 30. On the other hand, if the angle formed by the inner side of the arm 12, 22 and the connecting part 13, 23 is smaller than the angle (120°) formed by the connecting part 13, 23 and the second supporting part 14, 24, the swing angle is smaller than the case where these angles are the same, and the driving efficiency of the movable part 30 is reduced.

[0087] Therefore, based on the simulation results, it can be said that by configuring the arm portions 12, 22 in a manner such that the top end is farther away from the rotation axis R0 than the root end, the angle formed by the inner side of the arm portions 12, 22 and the connecting portions 13, 23 is larger than the angle formed by the connecting portions 13, 23 and the second supporting portions 14, 24, thereby further improving the driving efficiency of the movable portion 30 compared to the structure of the above-mentioned embodiment 1.

[0088] In addition, Figure 8 In the structure shown, since the distance between the top ends of the pair of arm portions 12 and 22 in the X-axis direction is larger than that in the above-mentioned embodiment 1, the outer shape of the driving element 1 in a plan view is larger in the X-axis direction than that in the structure of the above-mentioned embodiment 1. Therefore, it can be said that it is preferable to increase the angle formed by the inner side of the arm portions 12 and 22 and the connecting portions 13 and 23 under the condition that the outer shape of the driving element 1 in a plan view can be within a predetermined restricted range.

[0089] <Effects of Embodiment 2>

[0090] like Figure 8 As shown in FIG. 1 , the angle θ21 formed between the rotation axis R0 side of the arm portions 12 and 22 and the connecting portions 13 and 23 is larger than the angle θ11 formed between the connecting portions 13 and 23 and the second supporting portions 14 and 24. Fig. 9 As shown, the swing angle (optical full angle) of the movable portion 30 at the same voltage (10 Vpp) can be further increased compared to the first embodiment, and the driving efficiency of the movable portion 30 can be further improved.

[0091] Furthermore, even when there is no condition that the angle formed by the connection portions 13 , 23 and the second support portions 14 , 24 is larger than 90° and approximately equal to or smaller than 135°, the structure of the second embodiment can be applied.

[0092] <Implementation method 3>

[0093] Fig.10 It is a perspective view showing the structure of the driving element 1 according to the third embodiment.

[0094] In the third embodiment, the second drive unit 20 shown in the first embodiment is omitted, and the first drive unit 10 is arranged only on the positive side of the Y axis of the movable portion 30. In this structure, as in the first embodiment, the light deflection element 2 is formed by arranging the reflection surface 40 on the upper surface of the movable portion 30.

[0095] According to the third embodiment, similarly to the first embodiment, stress concentration generated at the joining positions between the pair of coupling portions 13 and the second supporting portion 14 can be suppressed, and the driving efficiency of the movable portion 30 can be improved.

[0096] The structure of Embodiment 2 can also be applied to the structure of Embodiment 3. In this case, the pair of arm portions 12 are arranged so that the top ends are farther from the rotation axis R0 than the base ends. Thus, as in Embodiment 2, the driving efficiency of the movable portion 30 can be further improved.

[0097] <Change Example>

[0098] The embodiment of the present invention is not limited to the above-mentioned Embodiments 1 to 3.

[0099] For example, you can also Fig.11 As in the modification example 1 shown in (a), the corner portion (the portion of the circle of the dotted line) where the side surface of the pair of connecting parts 13 on the fixing part 15 side joins the side surface of the second supporting part 14 is chamfered to form a curved surface. In this case, the angle formed by the side surface of the pair of connecting parts 13 on the fixing part 15 side and the side surface of the second supporting part 14 is greater than 90° and less than or equal to approximately 135°.

[0100] In addition, you can also Fig.11 As in the modification example 2 shown in (b) of FIG. 1 , there is another side surface between the outer side surface of the connecting portion 13 and the outer side surface of the second supporting portion 14. In this case, as shown in FIG. Fig.11 As shown in (b), the range to the other side surface is set as the second support portion 14, and the other side surface is included in the connecting portion 13. Therefore, in this case, the angle θb formed by the other side surface and the second support portion 14 is set to be greater than 90° and less than or equal to approximately 135°.

[0101] In addition, the width of the second support portion 14 in the X-axis direction may not be constant, for example, Fig.12 As in the modification 3 shown in (a), the width of the second support portion 14 varies within the range of W11 to W12. In this case, the angle θc formed by the pair of connecting portions 13 and the second support portion 14 may be greater than 90° and not more than approximately 135°.

[0102] In addition, the width of the connecting portion 13 may not be constant, for example, Fig.12 As in the modification 4 shown in (b), the width of the connection part 13 varies within the range of W21 to W22. In this case, the angle θd formed by the pair of connection parts 13 and the second support part 14 may be greater than 90° and not more than approximately 135°.

[0103] In addition, Fig.11 (a)~ Fig.12 (b) shows the structure of the first drive unit 10 side. However, when the drive element 1 includes the second drive unit 20 as in the first and second embodiments, the structure of the second drive unit 20 side may be changed in the same manner.

[0104] In the above-mentioned first and second embodiments, the second supporting parts 14 and 24 are made wider in the X-axis direction than the first supporting parts 11 and 21, thereby making the second supporting parts 14 and 24 have higher rigidity than the first supporting parts 11 and 21. However, the method of increasing the rigidity of the second supporting parts 14 and 24 is not limited thereto. For example, the second supporting parts 14 and 24 may be made thicker than the first supporting parts 11 and 21 or made of a material having higher rigidity than the first supporting parts 11 and 21, thereby making the second supporting parts 14 and 24 have higher rigidity than the first supporting parts 11 and 21.

[0105] In the above-mentioned first and second embodiments, the movable portion 30 is circular in shape, but the movable portion 30 may be square or other shapes. The planar shape of the driving element 1 and the dimensions of each part of the driving element 1 may also be changed as appropriate.

[0106] Furthermore, the driving element 1 may be used as an element other than the light deflection element 2. When the driving element 1 is used as an element other than the light deflection element, the movable portion 30 may be provided with a member other than the reflection surface 40 instead of the reflection surface 40.

[0107] In addition, the embodiments of the present invention can be variously modified as appropriate within the scope of the technical concept shown in the claims.

[0108] (Note)

[0109] According to the description of the above embodiments, the following technology is disclosed.

[0110] (Technology 1)

[0111] A driving element, characterized in that

[0112] The drive element includes:

[0113] movable part;

[0114] a first support portion extending along the rotation axis of the movable portion, one end of the first support portion being connected to the movable portion;

[0115] a pair of arms disposed across the rotation axis;

[0116] a pair of connecting parts connecting the pair of arm parts and the other end of the first supporting part;

[0117] a second supporting portion extending along the rotation axis and supporting the pair of connecting portions;

[0118] a fixing portion connected to the second supporting portion; and

[0119] a driving portion that drives the arm portion,

[0120] The second support portion has a higher rigidity than the first support portion.

[0121] The pair of connecting parts are arranged in a manner inclined toward the movable part.

[0122] An angle formed by each of the connecting portions and the second supporting portion is larger than 90° and smaller than or equal to 135°.

[0123] According to this technology, a pair of connecting parts are arranged in a manner inclined toward the movable part, and the angle formed by each connecting part and the second supporting part is greater than 90° and less than 135°. Therefore, even when the rigidity of the second supporting part is higher than that of the first supporting part, the stress generated at the connection position of the connecting part and the second supporting part when the movable part is driven can be suppressed, and the torque generated by the pair of arm parts can be efficiently transmitted to the first supporting part. Therefore, the driving efficiency of the movable part can be effectively improved while suppressing the stress generated when the movable part is driven.

[0124] (Technique 2)

[0125] The driving element according to technology 1 is characterized in that

[0126] The formed angle is set at approximately 115°.

[0127] According to this technology, the driving efficiency of the movable part can be maximized.

[0128] (Technique 3)

[0129] The driving element according to technology 1 or 2 is characterized in that:

[0130] An angle formed between the rotation axis side of the arm portion and the connection portion is larger than an angle formed between the connection portion and the second support portion.

[0131] According to this technology, the driving efficiency of the movable part can be further improved.

[0132] (Technique 4)

[0133] The driving element according to technology 1 or 2 is characterized in that:

[0134] The pair of arm portions extend parallel to the rotation axis.

[0135] According to this technique, it is possible to suppress stress and improve the driving efficiency of the movable portion 30 while making the outer shape of the driving element 1 compact in a plan view.

[0136] (Technique 5)

[0137] The driving element according to any one of techniques 1 to 4 is characterized in that:

[0138] Two driving units each including the first supporting portion, the pair of arm portions, the pair of connecting portions, the second supporting portion, the fixing portion, and the driving portion are arranged in opposite directions across the movable portion.

[0139] The first supporting portion of each of the driving units is connected to the movable portion.

[0140] According to this technology, the movable part is supported and driven by each driving unit, so that the movable part can be stably driven with a larger torque.

[0141] (Technique 6)

[0142] The driving element according to any one of techniques 1 to 5 is characterized in that:

[0143] The driving unit includes a piezoelectric thin film as a driving source.

[0144] According to this technology, the arm can be driven smoothly.

[0145] (Technique 7)

[0146] A light deflection element, characterized in that:

[0147] The light deflection element comprises:

[0148] The driving element of any one of technologies 1 to 6; and

[0149] The reflecting surface is arranged on the movable part.

[0150] According to this technique, since the driving efficiency of the movable portion can be improved by using the driving element of any one of Techniques 1 to 6, light can be efficiently deflected and scanned at a large swing angle by using the reflection surface.

[0151] Furthermore, according to the description of Embodiment 2, the following technology is disclosed.

[0152] (Technology 8)

[0153] A driving element, characterized in that

[0154] The drive element includes:

[0155] movable part;

[0156] a first support portion extending along the rotation axis of the movable portion, one end of the first support portion being connected to the movable portion;

[0157] a pair of arms disposed across the rotation axis;

[0158] a pair of connecting parts connecting the pair of arm parts and the other end of the first supporting part;

[0159] a second supporting portion extending along the rotation axis and supporting the pair of connecting portions;

[0160] a fixing portion connected to the second supporting portion; and

[0161] a driving portion that drives the arm portion,

[0162] The pair of arm portions are arranged such that the top ends thereof are farther from the rotation axis than the base ends thereof.

[0163] (Technique 9)

[0164] According to technology 8, it is characterized in that

[0165] An angle formed between the rotation axis side of the arm portion and the connection portion is larger than an angle formed between the connection portion and the second support portion.

[0166] According to the techniques 8 and 9, the driving efficiency of the movable part can be improved.

[0167] Description of Reference Numerals

[0168] 1. Driving element; 2. Light deflection element; 10. First driving unit; 11. First supporting portion; 12. Arm portion; 13. Connecting portion; 14. Second supporting portion; 15. Fixing portion; 16. Driving portion; 16a. Piezoelectric film; 20. Second driving unit; 21. First supporting portion; 22. Arm portion; 23. Connecting portion; 24. Second supporting portion; 25. Fixing portion; 26. Driving portion; 26a. Piezoelectric film; 30. Movable portion; 40. Reflecting surface.

Claims

1. A driving element, characterized in that: The drive element includes: movable part; a first support portion extending along the rotation axis of the movable portion, one end of the first support portion being connected to the movable portion; a pair of arms disposed across the rotation axis; a pair of connecting parts connecting the pair of arm parts and the other end of the first supporting part; a second supporting portion extending along the rotation axis and supporting the pair of connecting portions; a fixing portion connected to the second supporting portion; and a driving portion that drives the arm portion, The second support portion has a higher rigidity than the first support portion. The pair of connecting parts are arranged in a manner inclined toward the movable part. An angle formed by each of the connecting portions and the second supporting portion is larger than 90° and smaller than or equal to 135°.

2. The driving element according to claim 1, characterized in that The formed angle is set at approximately 115°.

3. The driving element according to claim 1, characterized in that An angle formed between the rotation axis side of the arm portion and the connection portion is larger than an angle formed between the connection portion and the second support portion.

4. The driving element according to claim 1, characterized in that The pair of arm portions extend parallel to the rotation axis.

5. The driving element according to claim 1, characterized in that Two driving units each including the first supporting portion, the pair of arm portions, the pair of connecting portions, the second supporting portion, the fixing portion, and the driving portion are arranged in opposite directions across the movable portion. The first supporting portion of each of the driving units is connected to the movable portion.

6. The driving element according to claim 1, characterized in that The driving unit includes a piezoelectric thin film as a driving source.

7. A light deflection element, characterized in that: The light deflection element comprises: The driving element according to any one of claims 1 to 6; and The reflecting surface is arranged on the movable part.

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