Driving element

Abstract

The present invention provides a drive element that can suppress unwanted vibrations that occur during the resonant operation of the movable part, while also suppressing damage to the torsion part due to torsional stress. [Solution] The drive element 1 comprises a movable part 20 that performs resonant operation around a rotation axis R1 at a target frequency, a torsion part 12 that extends along the rotation axis R1 and has one end connected to the movable part 20, a drive unit 11 having a tuning fork vibrator 111 connected to the other end of the torsion part 12, and a base 30 that supports the drive unit 11. The resonant operation of the movable part 20 at the target frequency is the operation of the movable part 20 in an inverse phase mode in which the movable part 20 repeatedly rotates in the opposite phase to the tuning fork vibrator 111. The natural frequencies of the portion consisting of the movable part 20 and the torsion part 12 and the natural frequency of the drive unit 11 are adjusted so that the position of the node in which the twisting direction of the torsion part 12 switches in the inverse phase mode is near the other end of the torsion part 12.

Description

Technical Field

[0001] The present invention relates to a drive element that rotates a movable part about a rotation axis.

Background Art

[0002] In recent years, drive elements that rotate a movable part using MEMS (Micro Electro Mechanical System) technology have been developed. In this type of drive element, by arranging a reflecting surface on the movable part, the light incident on the reflecting surface can be scanned at a predetermined deflection angle. This type of drive element is mounted, for example, in image display devices such as head-up displays and head-mounted displays. In addition, this type of drive element can also be used in laser radars that detect an object using laser light.

[0003] Patent Document 1 below describes a drive element that rotates a movable part by a so-called tuning fork oscillator. In this drive element, the movable part is connected to the tuning fork oscillator by a rod-shaped member (torsion part) extending along the rotation axis. By vibrating the tuning fork oscillator, torsion occurs in the torsion part. As a result, the movable part rotates about the rotation axis.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the drive element having the above configuration, as the tuning fork oscillator vibrates, the movable part rotates repeatedly at a predetermined resonance frequency. At this time, due to this resonance operation, unnecessary vibrations may occur in the drive element. This vibration propagates to the member that supports the drive element. It is preferable that such unnecessary vibrations be suppressed as much as possible.

[0006] Furthermore, in the drive element with the above configuration, the torsion portion is a rod-shaped member with a small cross-sectional area. Therefore, if a large torsional stress is generated in the torsion portion during the resonant operation of the movable part, there is a risk of damage to the torsion portion. For this reason, in the drive element with the above configuration, it is necessary to appropriately suppress damage to the torsion portion due to torsional stress.

[0007] In view of these challenges, the present invention aims to provide a drive element that can suppress unwanted vibrations that occur during the resonant operation of the movable part, while also suppressing damage to the torsion part due to torsional stress. [Means for solving the problem]

[0008] A first aspect of the present invention relates to a drive element. The drive element according to this aspect comprises a movable part that performs resonant operation around a pivot axis at a target frequency, a torsion part that extends along the pivot axis and has one end connected to the movable part, a drive unit having a tuning fork vibrator connected to the other end of the torsion part, and a base that supports the drive unit. The resonant operation at the target frequency is the operation of the movable part in an inverse phase mode in which the movable part repeatedly rotates in opposite phase to the tuning fork vibrator, and the natural frequencies of the movable part and the portion consisting of the torsion part and the natural frequency of the drive unit are adjusted so that the position of the node in which the twisting direction of the torsion part switches in the inverse phase mode is near the other end of the torsion part.

[0009] According to the drive element of this embodiment, since the resonant operation of the movable part at the target frequency is the operation of the movable part in an inverse phase mode, the vibrations generated in the movable part and the torsion part and the vibrations generated by the tuning fork vibrator cancel each other out during the resonant operation of the movable part. Therefore, unwanted vibrations that occur during the resonant operation of the movable part can be effectively suppressed.

[0010] On the other hand, in the reverse-phase mode, the tuning fork vibrator and the movable part resonate in opposite phases to each other, which can cause a node in the torsion part where the twisting direction switches. That is, no twist angle occurs in the torsion part at the node's position, and the twisting direction of the torsion part is reversed between the range from the node's position towards the movable part and the range from the node's position towards the drive part. Here, the closer the node's position is to the movable part, the shorter the portion of the torsion part from the node to the movable part becomes, and the greater the torsional stress in this portion. In contrast, in the drive element according to this embodiment, as described above, the node is positioned near the other end, i.e., the end of the torsion part connected to the drive part, so that the portion of the torsion part from the node to the movable part can be made longer, and the excessively large torsional stress generated in this portion can be suppressed. This makes it possible to suppress damage to the torsion part due to torsional stress.

[0011] Thus, the drive element according to this embodiment can suppress unwanted vibrations that occur during the resonant operation of the movable part, while also suppressing damage to the torsion part due to torsional stress. [Effects of the Invention]

[0012] As described above, the present invention provides a drive element that can suppress unwanted vibrations that occur during the resonant operation of the movable part, while also suppressing damage to the torsion part due to torsional stress.

[0013] 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]

[0014] [Figure 1] Figure 1 is a top view showing the configuration of the drive element according to Embodiment 1. [Figure 2] Figure 2 is a bottom view showing the configuration of the drive element according to Embodiment 1. [Figure 3]FIG. 3(a) and FIG. 3(b) are diagrams for explaining the comparison between the in-phase mode and the anti-phase mode according to Embodiment 1. [Figure 4] FIG. 4(a) and FIG. 4(b) are diagrams schematically showing the nodes generated in the torsion part in the anti-phase mode according to Embodiment 1. [Figure 5] FIG. 5 is a graph showing the simulation results obtained by simulation of the maximum stress (torsion stress) generated in the torsion part when the position of the node is changed according to Embodiment 1. [Figure 6] FIG. 6 is a bottom view showing the configuration of the drive element according to Embodiment 2. [Figure 7] FIG. 7 is a graph showing the simulation results obtained by simulation of the maximum stress (torsion stress) generated in the torsion part when the position of the node is changed according to Embodiment 2. [Figure 8] FIG. 8 is a bottom view showing the configuration of the drive element according to Embodiment 3. [Figure 9] FIG. 9 is a graph showing the simulation results obtained by simulation of the maximum stress (torsion stress) generated in the torsion part when the position of the node is changed according to Embodiment 3. [Figure 10] FIG. 10 is a plan view showing the configuration of the drive element according to Embodiment 4. [Figure 11] FIG. 11 is a bottom view showing the configuration of the drive element according to the modification example.

MODE FOR CARRYING OUT THE INVENTION

[0015] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0016] In the following embodiments, a reflecting surface is arranged on the movable part of the drive element. For convenience, X, Y, and Z axes orthogonal to each other are added to each figure. The Y-axis direction is parallel to the rotation axis of the drive element, and the Z-axis direction is the thickness direction of the drive element.

[0017] <Embodiment 1> FIG. 1 is a top view showing the configuration of the drive element 1, and FIG. 2 is a bottom view showing the configuration of the drive element 1.

[0018] As shown in FIGS. 1 and 2, the drive element 1 includes two drive units 10, a movable part 20, and a base part 30. The drive element 1 has a shape that is symmetric with respect to the X-axis direction and the Y-axis direction in a plan view.

[0019] The two drive units 10 each include a drive part 11 and a torsion part 12. The two drive units 10 are arranged in opposite directions with the movable part 20 interposed therebetween, and the torsion part 12 of each drive unit 10 is connected to the movable part 20. Each drive part 11 is supported by the base part 30. The base part 30 is a frame-shaped member having a rectangular outline in a plan view. The drive unit 10 rotates the movable part 20 about the rotation axis R1 by a drive signal supplied from a drive circuit not shown.

[0020] Each drive part 11 includes a tuning fork oscillator 111 and a piezoelectric body 112. The tuning fork oscillator 111 is configured such that a pair of arm parts 111a are connected to a connecting part 111b. In a plan view, each of the pair of arm parts 111a has an inclined part inclined with respect to the rotation axis R1 and a straight part parallel to the rotation axis R1. The piezoelectric body 112 serving as a drive source is arranged on the upper surfaces (surfaces on the positive Z-axis side) of the pair of straight parts. The shape of the pair of arm parts 111a is not limited to the shape shown in FIGS. 1 and 2. For example, the pair of arm parts 111a may have a shape in which they extend in a direction perpendicular to the rotation axis R1 from the connecting part 111b and then bend in a direction parallel to the rotation axis R1.

[0021] The piezoelectric body 112 has a laminated structure in which electrode layers are arranged above and below a piezoelectric thin film having a predetermined thickness. The piezoelectric thin film is made of a piezoelectric material having a high piezoelectric constant, such as lead zirconate titanate (PZT). The electrodes are made of a material having a low electrical resistance and high heat resistance, such as platinum (Pt) or gold (Au). The piezoelectric body 112 is arranged by forming a layer structure including the piezoelectric thin film and the upper and lower electrodes on the upper surface of the arm part 111a by a sputtering method or the like.

[0022] The torsion section 12 extends along the pivot axis R1, with one end connected to the movable section 20. The other end of the torsion section 12 is connected to the tuning fork vibrator 111. The torsion section 12 is a thin, rod-shaped member. The cross-sectional area of ​​the torsion section 12 perpendicular to the pivot axis R1 is substantially constant. The cross-section of the torsion section 12 is approximately square. The cross-section of the torsion section 12 may be of other shapes, such as circular.

[0023] The movable part 20 comprises a driven part 21 and a frame part 22. The driven part 21 is a circular plate-shaped member in plan view. The shape of the driven part 21 may be other than circular, such as an ellipse or a square. In plan view, the frame part 22 surrounds the driven part 21 and is connected to the driven part 21 near the position of the driven part 21 furthest from the pivot axis R1. The torsion part 12 of each drive unit 10 is connected to the frame part 22.

[0024] A reflective surface 23 is positioned on the upper surface of the driven part 21. The reflective surface 23 is formed by creating a highly reflective metal film or dielectric multilayer film on the upper surface of the driven part 21. However, it is not limited to this; if the upper surface of the driven part 21 itself has high reflectivity, this upper surface may be used as the reflective surface 23, or the upper surface of the driven part 21 may be given a mirror finish.

[0025] The substrate of the driving element 1 has the same contour as the driving element 1 in a plan view and has a constant thickness. The piezoelectric body 112 and the reflective surface 23 are arranged in corresponding areas on the upper surface of the substrate. A wiring pattern (not shown) for supplying driving signals to each piezoelectric body 112 is arranged on the upper surface (positive Z-axis side) of the substrate connecting the tuning fork vibrator 111 to the base 30, and terminals (not shown) connected to these wiring patterns are arranged on the upper surface of the substrate of the base 30. The wiring and terminals may have the same layer structure as the piezoelectric body 112. The lower electrode of the wiring may be extended to the area of ​​the ground terminal to become a ground terminal.

[0026] Furthermore, in Figure 2, a layer made of a predetermined material is laminated over the area on the underside of the substrate where hatching is applied, that is, over most of the area on the underside of the base portion 30, thereby increasing the thickness of the base portion 30. The thickness of the laminated layer is constant. The material of the laminated layer may be different from that of the substrate, or it may be the same material as the substrate.

[0027] The base material is integrally formed from, for example, silicon. However, the material constituting the base material is not limited to silicon; other materials may also be used. Preferably, the material constituting the base material is a material with high mechanical strength and Young's modulus, such as metal, crystal, glass, or resin. In addition to silicon, titanium, stainless steel, elimperium, brass alloy, etc., can be used as such materials. The material of the layer laminated on the base 30 can also be similarly selected.

[0028] The length, thickness, and stiffness of each part of the drive element 1 are adjusted so that the movable part 20 (driven part 21) rotates repeatedly at a target frequency. In other words, the drive element 1 is configured so that the resonant frequency of the movable part 20 is near the target frequency. For example, during this resonant operation, a pair of drive units 11 (piezoelectric bodies 112) are controlled so that the movable part 20 (driven part 21) rotates repeatedly with a deflection angle of ±10° or more with respect to the neutral position.

[0029] As described above, a reflective surface 23 is positioned on the movable part 20 (driven part 21). The reflective surface 23 reflects light incident on the movable part 20 from above in a direction corresponding to the swing angle of the movable part 20. As a result, the light incident on the reflective surface 23 (for example, laser light) is deflected and scanned as the movable part 20 rotates. By positioning the reflective surface 23 on the movable part 20 (driven part 21), the driving element 1 is configured as an optical deflection element.

[0030] Incidentally, in the drive element 1 with the above configuration, the movable part 20 is repeatedly rotated at a predetermined resonant frequency in accordance with the vibration of the tuning fork vibrator 111. At this time, unwanted vibrations may be generated in the drive element 1 due to this resonant operation. These vibrations are propagated to the member supporting the drive element 1. It is preferable to suppress such unwanted vibrations as much as possible.

[0031] Furthermore, in the drive element 1 with the above configuration, the torsion portion 12 is a rod-shaped member with a small cross-sectional area. Therefore, if a large torsional stress is generated in the torsion portion 12 during the resonant operation of the movable portion 20, there is a risk that the torsion portion 12 may be damaged. For this reason, in the drive element 1 with the above configuration, it is necessary to appropriately suppress damage to the torsion portion 12 due to torsional stress.

[0032] Therefore, in this embodiment, a configuration is used to suppress unwanted vibrations that occur during the resonant operation of the movable part 20, while also suppressing damage to the torsion part 12 due to torsional stress. This configuration will be described below.

[0033] First, the drive element 1 is configured such that the resonant operation of the movable part 20 at the target frequency is achieved in a so-called inverse-phase mode, by adjusting parameters that contribute to the resonant operation, such as the thickness, length, and stiffness of each part. Here, the inverse-phase mode is an operating mode in which the movable part 20 repeatedly rotates in the opposite phase to the tuning fork vibrator 111.

[0034] Figures 3(a) and 3(b) illustrate the comparison between in-phase mode and out-of-phase mode.

[0035] Figure 3(a) shows the state of the tuning fork vibrator 111 and the movable part 20 when the movable part 20 rotates at the maximum amplitude in the in-phase mode, and Figure 3(b) shows the state of the tuning fork vibrator 111 and the movable part 20 when the movable part 20 rotates at the maximum amplitude in the out-of-phase mode.

[0036] Figures 3(a) and 3(b) show the displacement amounts of each part obtained by simulation, indicated by the colors on the color scales attached to each figure. In addition, in Figures 3(a) and 3(b), parts that include the rotation axis R1 and are displaced upward (positive Z-axis direction) with respect to a reference plane parallel to the XY plane are indicated by upward arrows, and parts that are displaced downward (negative Z-axis direction) are indicated by downward arrows.

[0037] In the in-phase mode shown in Figure 3(a), the inclination around the rotation axis R1 is in the same direction for the movable part 20 and the tuning fork vibrator 111. That is, in the range on the positive X-axis side with respect to the rotation axis R1, the movable part 20 and the tuning fork vibrator 111 are displaced downward (negative Z-axis direction) with respect to the reference plane, and in the range on the negative X-axis side with respect to the rotation axis R1, the movable part 20 and the tuning fork vibrator 111 are displaced upward (positive Z-axis direction) with respect to the reference plane. Thus, in the in-phase mode, the movable part 20 repeatedly rotates in phase with respect to the tuning fork vibrator 111.

[0038] In contrast, in the reverse-phase mode shown in Figure 3(b), the inclination around the rotation axis R1 is in opposite directions for the movable part 20 and the tuning fork vibrator 111. That is, in the range on the positive side of the X axis with respect to the rotation axis R1, the movable part 20 is displaced downward (negative Z-axis direction) with respect to the reference plane, while the tuning fork vibrator 111 is displaced upward (positive Z-axis direction) with respect to the reference plane. Also, in the range on the negative side of the X axis with respect to the rotation axis R1, the movable part 20 is displaced upward (positive Z-axis direction) with respect to the reference plane, while the tuning fork vibrator 111 is displaced downward (negative Z-axis direction) with respect to the reference plane. Thus, in the reverse-phase mode, the movable part 20 repeatedly rotates in opposite phase to the tuning fork vibrator 111.

[0039] In the reverse-phase mode, as described above, the movable part 20 and the tuning fork vibrator 111 operate in opposite phases. Therefore, the vibrations generated in the movable part 20 and the torsion part 12 during the resonant operation of the movable part 20 and the vibrations generated by the tuning fork vibrator 111 cancel each other out. For this reason, in the reverse-phase mode, unwanted vibrations generated during the resonant operation of the movable part 20 can be effectively suppressed compared to the in-phase mode.

[0040] Specifically, in the in-phase mode, as shown in Figure 3(a), the uneven coloring indicates that different displacement amounts occur in the base 30. This indicates that unwanted vibrations are occurring in the base 30 in the in-phase mode. In contrast, in the out-of-phase mode, as shown in Figure 3(b), there is almost no uneven coloring in the base 30. From this, it can be understood that unwanted vibrations are effectively suppressed in the out-of-phase mode.

[0041] Thus, in Embodiment 1, parameters contributing to the resonant operation of the movable part 20 at the target frequency, such as the thickness, length, and stiffness of each part of the drive element 1, are adjusted so that the resonant operation of the movable part 20 at the target frequency is realized in a so-called inverse-phase mode. As a result, unwanted vibrations that occur during the resonant operation of the movable part 20 at the target frequency are effectively suppressed.

[0042] However, in the opposite-phase mode, the tuning fork vibrator 111 and the movable part 20 resonate in opposite phases to each other, which can cause a node in the torsion part 12 where the twisting direction switches. That is, no twist angle is generated in the torsion part 12 at the node, and the twisting direction of the torsion part 12 is reversed in the range from the node towards the movable part 20 and in the range from the node towards the drive part 11.

[0043] Figures 4(a) and 4(b) schematically show the knot S1 that occurs in the torsion section 12 in reverse-phase mode, respectively. For convenience, only the peripheral configuration of one of the drive units 10 is shown in Figures 4(a) and 4(b).

[0044] As shown by the arrows in Figure 4(a), the direction of twist around the rotation axis R1 in the torsion section 12 is reversed in the range from the position of node S1 towards the movable section 20 (positive Y-axis side) and in the range from the position of node S1 towards the drive section 11 (negative Y-axis side). No twist angle occurs at the position of node S1.

[0045] Here, the closer the position of node S1 is to the movable part 20, the smaller the length L1 of the torsion portion 12 from node S1 to the movable part 20 becomes. In other words, as the position of node S1 approaches the movable part 20, the effective length L1 of the twisted portion of the torsion portion 12 on the movable part 20 side becomes smaller. For this reason, the closer the position of node S1 is to the movable part 20, the greater the torsional stress in this portion becomes, and the more likely this portion is to break.

[0046] Therefore, in Embodiment 1, as shown in Figure 4(b), parameters such as the length, thickness, and stiffness of each part of the drive element 1 are adjusted so that the position of the node S1 is near the end of the torsion part 12 on the drive part 11 side (negative Y-axis side). More specifically, the balance between the natural frequency of the part consisting of the movable part 20 and the torsion part 12 and the natural frequency of the drive part 11 is adjusted so that the position of the node S1 is set near the end of the torsion part 12 on the negative Y-axis side.

[0047] The position of node S1 moves in the Y-axis direction according to the balance between the natural frequencies of the movable part 20 and the torsion part 12 and the natural frequency of the drive unit 11. That is, as described above, during resonance, the vibration of the structure consisting of the movable part 20 and the torsion part 12 and the vibration of the drive unit 11 are in opposite phase. By adjusting the balance between the natural frequencies of this structure and the drive unit 11, node S1 can be generated near the boundary between this structure and the drive unit 11. On the other hand, if the natural frequency of this structure is lower than the balance described above with respect to the natural frequency of the drive unit 11, node S1 will be generated at a position displaced from this boundary towards the movable part 20. Thus, the position of node S1 shifts from this boundary towards the side with the lower natural frequency of the structure (movable part 20, torsion part 12) and the drive unit 11. Therefore, by adjusting the balance between the natural frequencies of these two, the position of node S1 can be set near the negative Y-axis end of the torsion part 12.

[0048] Here, the natural frequency can be changed by adjusting the mass and stiffness of the structure or the drive unit 11. That is, the natural frequency decreases as the mass of the object increases, and increases as the stiffness (rigidity) increases. For example, if the length of the tuning fork vibrator 111 is reduced and the mass of the tuning fork vibrator 111 is reduced, the natural frequency of the drive unit 11 increases. Also, if the cross-sectional area of ​​the torsion part 12 is increased and the torsion part 12 is made stiffer, the natural frequency of the structure increases. In this way, by adjusting the balance between these natural frequencies, the position of the node S1 can be set near the negative end of the Y-axis of the torsion part 12.

[0049] As shown in Figure 4(b), when the node S1 is set near the end of the torsion section 12 on the drive section 11 side, the length L1 of the portion of the torsion section 12 between the node S1 and the movable section 20 can be increased. This suppresses the torsional stress generated in this portion when the movable section 20 rotates, and prevents damage to the torsion section 12 due to torsional stress.

[0050] Figure 5 is a graph showing the simulation results obtained by simulation when the position of node S1 is changed, which determines the maximum stress (maximum torsional stress) generated in the torsion section 12.

[0051] In this simulation, the position of node S1 was changed by adjusting the length of the tuning fork oscillator 111 to alter the balance of the natural frequencies described above. Furthermore, the oscillation angle of the movable part 20 around the rotation axis R1 was set to ±10°, and it was assumed that the resonant operation of the movable part 20 occurred at a predetermined target frequency.

[0052] The horizontal axis of Figure 5 represents the position of node S1, defined by the ratio (%) of the length L2 from the end of the torsion section 12 on the drive unit 11 side to node S1, relative to the total length L0 of the torsion section 12 shown in Figure 4(b). A value of 0 on the horizontal axis corresponds to the position of the end of the torsion section 12 on the drive unit 11 side (the boundary position between the drive unit 11 and the torsion section 12). The vertical axis of Figure 5 represents the maximum stress (MPa) generated in the torsion section 12.

[0053] As shown in Figure 5, the maximum stress generated in the torsion section 12 decreases as the position of node S1 approaches the boundary position (position where the horizontal axis is 0). Here, if the position of node S1 is within 10% of the total length L0 of the torsion section 12 from the boundary position, the maximum stress generated in the torsion section 12 converges to a substantially constant magnitude. That is, if node S1 is included within 10% of the total length L0 of the torsion section 12 from this boundary position, the maximum stress generated in the torsion section 12 is substantially equal to the maximum stress when there is no node S1 in the torsion section 12 (when the value on the horizontal axis is 0 or less).

[0054] Therefore, it is preferable that the node S1 is set on the drive unit 11 side of a position that is 10% of the total length L0 of the torsion portion 12 from the end (boundary position) of the torsion portion 12 on the drive unit 11 side. This reliably prevents damage to the torsion portion 12 caused by torsional stress generated in the torsion portion 12 when the movable part 20 rotates.

[0055] Furthermore, in the range on the drive unit 11 side of the torsion section 12, from the end (boundary position) of the torsion section 12 on the drive unit 11 side to a position 10% of the total length L0 of the torsion section 12, even if the position of the node S1 fluctuates, the maximum stress generated in the torsion section 12 does not substantially change. Therefore, by setting the position of the node S1 within this range, even if the position of the node S1 deviates slightly from the intended position due to manufacturing errors, the maximum stress generated in the torsion section 12 can be substantially minimized, and damage to the torsion section 12 due to torsional stress can be reliably suppressed.

[0056] Furthermore, referring to the simulation results in Figure 5, even if the node S1 is set at a position approximately 12% of the total length L0 of the torsion portion 12 from the end (boundary position) of the torsion portion 12 on the drive unit 11 side, the maximum stress (torsional stress) generated in the torsion portion 12 is suppressed to at most about 1.5 times the maximum stress when there is no node S1 in the torsion portion 12 (when the value on the horizontal axis is 0 or less). Therefore, by setting the position of node S1 on the drive unit 11 side of the position 12% of the total length L0 of the torsion portion 12 from the end (boundary position) of the torsion portion 12 on the drive unit 11 side, the torsional stress generated in the torsion portion 12 during the rotational movement of the movable part 20 can be effectively suppressed, and damage to the torsion portion 12 caused by this torsional stress can be appropriately suppressed.

[0057] However, in order to more reliably suppress damage to the torsion portion 12 due to torsional stress, it is even more preferable that the position of the node S1 be set in a range closer to the drive unit 11 than a position 10% of the total length L0 of the torsion portion 12 from the end (boundary position) of the torsion portion 12 on the drive unit 11 side.

[0058] <Effects of Embodiment 1> According to Embodiment 1, the following effects can be achieved.

[0059] As shown in Figures 1 and 2, the drive element 1 comprises a movable part 20 that performs resonant operation around a rotation axis R1 at a target frequency, a torsion part 12 that extends along the rotation axis R1 and has one end connected to the movable part 20, a drive unit 11 having a tuning fork vibrator 111 connected to the other end of the torsion part 12, and a base 30 that supports the drive unit 11. As shown in Figure 3(b), the resonant operation of the movable part 20 at the target frequency is the operation of the movable part 20 in an inverse phase mode in which the movable part 20 repeatedly rotates in the opposite phase to the tuning fork vibrator 111. As explained with reference to Figures 4(a), (b) and 5, the natural frequencies of the portion consisting of the movable part 20 and the torsion part 12 and the natural frequency of the drive unit 11 are adjusted so that the position of the node S1 where the twisting direction of the torsion part 12 switches in the inverse phase mode is near the end (other end) of the torsion part 12 on the drive unit 11 side.

[0060] With this configuration, since the resonant operation of the movable part 20 at the target frequency is in an out-of-phase mode, the vibrations generated in the movable part 20 and the torsion part 12 and the vibrations generated by the tuning fork vibrator 111 cancel each other out during the resonant operation of the movable part 20. Therefore, unwanted vibrations generated during the resonant operation of the movable part 20 can be effectively suppressed. On the other hand, in the out-of-phase mode, the tuning fork vibrator 111 and the movable part 20 resonate in out-of-phase with each other, so a node S1 where the twisting direction switches can occur in the torsion part 12. In contrast, in the drive element 1 according to Embodiment 1, as described above, the node S1 is located near the other end, i.e., the end of the torsion part 12 connected to the drive part 11, so that the portion of the torsion part 12 from the node S1 to the movable part 20 is made longer, and the torsional stress generated in this portion can be prevented from becoming excessively large. As a result, damage to the torsion part 12 due to torsional stress can be prevented.

[0061] From the simulation results in Figure 5, it is preferable that the node S1 is set on the drive unit 11 side of the torsion portion 12, at a position that is 12% of the total length L0 of the torsion portion 12 from the end (other end) of the torsion portion 12 on the drive unit 11 side.

[0062] With this configuration, as described above, the maximum torsional stress generated in the torsion section 12 can be suppressed to about 1.5 times or less the maximum torsional stress generated in the torsion section 12 when there is no node S1 in the torsion section 12. Therefore, damage to the torsion section 12 due to torsional stress can be appropriately suppressed.

[0063] As shown in Figures 1 and 2, two drive units 10, each equipped with a torsion section 12 and a drive section 11, are arranged in opposite directions with the movable section 20 in between, and the torsion section 12 of each drive unit 10 is connected to the movable section 20.

[0064] With this configuration, since the movable part 20 is supported and driven by each drive unit 10, the movable part 20 can be driven stably with greater torque.

[0065] As shown in Figures 1 and 2, the movable part 20 consists of a driven part 21 and a frame part 22 that, in a plan view, surrounds the driven part 21 and is connected to the driven part 21 near the position of the driven part 21 furthest from the rotation axis R1. The torsion part 12 of each drive unit 10 is connected to the frame part 22.

[0066] In this configuration, the area of ​​the driven part 21 furthest from the pivot axis R1, that is, the area of ​​the driven part 21 most prone to distortion during rotation, is supported by the frame 22, and the driving force from the torsion part 12 is applied to this end. Therefore, distortion of the driven part 21 that occurs during rotation can be effectively suppressed.

[0067] From the simulation results in Figure 5, it is preferable that the node S1 is set on the drive unit 11 side of the torsion portion 12, at a position that is 10% of the total length L0 of the torsion portion 12 from the end (other end) of the torsion portion 12 on the drive unit 11 side.

[0068] By setting the position of node S1 in this manner, the maximum torsional stress generated in the torsion section 12 can be made substantially equal to the maximum torsional stress that would occur if node S1 were not present in the torsion section 12. Therefore, damage to the torsion section 12 due to torsional stress can be reliably suppressed. Furthermore, in the range on the drive section 11 side of a position 10% of the total length L0 of the torsion section 12 from the other end, even if the position of node S1 fluctuates, the maximum torsional stress generated in the torsion section 12 does not substantially change. Therefore, by setting the position of node S1 within this range, even if the position of node S1 deviates slightly from the intended position due to manufacturing errors, etc., the maximum torsional stress generated in the torsion section 12 can be substantially minimized, and damage to the torsion section 12 due to torsional stress can be reliably suppressed.

[0069] As shown in Figure 1, the drive unit 11 has a piezoelectric element 112 as a drive source.

[0070] This configuration allows the tuning fork oscillator 111 to be driven smoothly.

[0071] As shown in Figure 1, the movable part 20 has a reflective surface 23 that reflects incident light.

[0072] With this configuration, the light incident on the reflective surface 23 can be scanned by the rotational movement of the movable part 20, and the driving element 1 can be configured as an optical deflection element.

[0073] <Embodiment 2> Figure 6 is a bottom view showing the configuration of the drive element 1 according to Embodiment 2.

[0074] In Embodiment 2, the configuration of the movable part 20 differs from that of Embodiment 1. Specifically, in Embodiment 2, the frame part 22 is omitted, and the movable part 20 is composed of the driven part 21 and the reflective surface 23. Therefore, in a plan view, the movable part 20 extends continuously without gaps from the center to the outer circumference. For convenience, in Figure 6, the reflective surface 23 located on the upper surface (the positive Z-axis side) of the driven part 21 is shown by a dashed line. The other configurations in Embodiment 2 are the same as those in Embodiment 1.

[0075] In Embodiment 2, the drive element 1 is configured such that the rotational operation of the movable part 20 at the target frequency is achieved by an inverse phase mode. This suppresses unwanted vibrations that occur during the rotational operation of the movable part 20. Also in Embodiment 2, the natural frequencies of the structure consisting of the movable part 20 and the torsion part 12 and the natural frequency of the drive unit 11 are adjusted so that the position of the node S1 generated by the inverse phase mode is set near the end of the torsion part 12 on the drive unit 11 side.

[0076] Figure 7 is a graph showing the simulation results obtained by simulation when the position of node S1 is changed in the configuration of Embodiment 2, and the maximum stress (torsional stress) generated in the torsion portion 12 is determined by simulation.

[0077] The simulation conditions in Figure 7 are the same as those in Figure 5. Also, the vertical and horizontal axes of the graph in Figure 7 are the same as those in Figure 5.

[0078] The trend in the simulation results in Figure 7 is almost the same as that in the simulation results in Figure 5. However, in the simulation results in Figure 7, the upper limit of the horizontal axis for the range in which the maximum stress of the torsion section 12 converges to the minimum value is 5%, which differs from the corresponding upper limit of 10% in the simulation results in Figure 5.

[0079] Therefore, in the configuration of Embodiment 2, in order to minimize the maximum stress (torsional stress) of the torsion portion 12 that occurs during the resonant operation of the movable portion 20 and to reliably suppress damage to the torsion portion 12 due to torsional stress, it is preferable to set the position of the node S1 closer to the drive unit 11 than a position that is 5% of the total length L0 of the torsion portion 12 from the end of the torsion portion 12 on the drive unit 11 side.

[0080] Furthermore, referring to the simulation results in Figure 7, even if the node S1 is set at a position approximately 12% of the total length L0 of the torsion portion 12 from the end (boundary position) of the torsion portion 12 on the drive unit 11 side, the maximum stress (torsional stress) generated in the torsion portion 12 is suppressed to at most about 1.5 times the maximum stress when there is no node S1 in the torsion portion 12 (when the value on the horizontal axis is 0 or less). Therefore, in the configuration of Embodiment 2, as in the configuration of Embodiment 1, by setting the position of node S1 on the drive unit 11 side from a position 12% of the total length L0 of the torsion portion 12 from the end (boundary position) of the torsion portion 12 on the drive unit 11 side, the torsional stress generated in the torsion portion 12 during the rotational operation of the movable part 20 can be effectively suppressed, and damage to the torsion portion 12 due to this torsional stress can be appropriately suppressed.

[0081] <Effects of Embodiment 2> With the configuration of Embodiment 2, as with Embodiment 1, by driving the movable part 20 in reverse phase mode and setting the position of the node S1 near the end (other end) of the torsion part 12 on the drive unit 11 side, it is possible to suppress unwanted vibrations that occur during the resonant operation of the movable part 20 while suppressing damage to the torsion part 12 due to torsional stress.

[0082] As shown in Figure 6, the movable part 20 extends continuously from the center to the outer periphery without any gaps in a plan view.

[0083] With this configuration, since the movable part 20 does not have a frame part 22, the structure of the movable part 20 can be simplified and the movable part 20 can be made lighter.

[0084] From the simulation results in Figure 7, it is preferable that in the configuration of Embodiment 2, the node S1 is set on the drive unit 11 side of a position that is 5% of the total length L0 of the torsion portion 12 from the end (other end) of the torsion portion 12 on the drive unit 11 side. A driving element characterized by the following features.

[0085] By setting the position of node S1 in this manner, the maximum torsional stress generated in the torsion section 12 can be made substantially equal to the maximum torsional stress that would occur if there were no node in the torsion section 12. Therefore, damage to the torsion section 12 due to torsional stress can be reliably suppressed. Furthermore, in the range on the drive section 11 side of a position 5% of the total length L0 of the torsion section 12 from the other end, even if the position of node S1 fluctuates, the maximum torsional stress generated in the torsion section 12 does not substantially change. Therefore, even if the position of node S1 deviates slightly from the intended position due to manufacturing errors, etc., the maximum torsional stress generated in the torsion section 12 can be substantially minimized, and damage to the torsion section 12 due to torsional stress can be reliably suppressed.

[0086] <Embodiment 3> Figure 8 is a bottom view showing the configuration of the drive element 1 according to Embodiment 3.

[0087] In Embodiment 3, the drive unit 10 on the positive side of the Y-axis is omitted from the configuration of Embodiment 2. Therefore, the drive element 1 comprises only one drive unit 10. The other configurations in Embodiment 3 are the same as in Embodiment 2.

[0088] In Embodiment 3, the drive element 1 is configured such that the rotational movement of the movable part 20 at the target frequency is achieved by the reverse-phase mode. This suppresses unwanted vibrations that occur during the rotational movement of the movable part 20. In Embodiment 2, the natural frequencies of the structure consisting of the movable part 20 and the torsion part 12 are adjusted to the natural frequency of the drive unit 11 so that the position of the node S1 generated by the reverse-phase mode is set near the end of the torsion part 12 on the drive unit 11 side.

[0089] Figure 9 is a graph showing the simulation results obtained by simulation of the maximum stress (torsional stress) generated in the torsion section 12 when the position of node S1 is changed in the configuration of Embodiment 3.

[0090] The simulation conditions in Figure 9 are the same as those in Figures 5 and 7. Also, the vertical and horizontal axes of the graph in Figure 9 are the same as those in Figures 5 and 7.

[0091] The trend in the simulation results in Figure 9 is almost the same as that in the simulation results in Figures 5 and 7. However, in the simulation results in Figure 9, the upper limit of the horizontal axis for the range in which the maximum stress of the torsion section 12 converges to the minimum value is 7%, which differs from the corresponding upper limits of 10% and 5% in the simulation results in Figures 5 and 7, respectively.

[0092] Therefore, in the configuration of Embodiment 3, in order to minimize the maximum stress (torsional stress) of the torsion portion 12 that occurs during the resonant operation of the movable portion 20 and to reliably suppress damage to the torsion portion 12 due to torsional stress, it is preferable to set the position of the node S1 closer to the drive unit 11 than a position that is 7% of the total length L0 of the torsion portion 12 from the end of the torsion portion 12 on the drive unit 11 side.

[0093] Furthermore, referring to the simulation results in Figure 9, even if the node S1 is set at a position approximately 12% of the total length L0 of the torsion portion 12 from the end (boundary position) of the torsion portion 12 on the drive unit 11 side, the maximum stress (torsional stress) generated in the torsion portion 12 is suppressed to at most about 1.5 times the maximum stress when there is no node S1 in the torsion portion 12 (when the value on the horizontal axis is 0 or less). Therefore, in the configuration of Embodiment 3, similar to the configurations of Embodiments 1 and 2, by setting the position of node S1 on the drive unit 11 side from a position 12% of the total length L0 of the torsion portion 12 from the end (boundary position) of the torsion portion 12 on the drive unit 11 side, the torsional stress generated in the torsion portion 12 during the rotational operation of the movable part 20 can be effectively suppressed, and damage to the torsion portion 12 due to this torsional stress can be appropriately suppressed.

[0094] Furthermore, although the movable part 20 does not include the frame part 22 in the configuration shown in Figure 8, the movable part 20 may include the frame part 22.

[0095] In this case, from the simulation results in Figures 5 and 7, it can be assumed that if the frame portion 22 is included in the configuration of Figure 8, the upper limit of the range in which the maximum stress of the torsion portion 12 is substantially minimized will be several percent larger than the 7% shown in Figure 9. Therefore, even in this configuration, by setting a node S1 at a position approximately 12% of the total length L0 of the torsion portion 12 from the end (boundary position) of the torsion portion 12 on the drive portion 11 side, it can be assumed that the maximum stress (torsional stress) generated in the torsion portion 12 will be suppressed to at most about 1.5 times the maximum stress when there is no node S1 in the torsion portion 12 (when the value on the horizontal axis is 0 or less).

[0096] Furthermore, in this configuration as well, by setting the position of node S1 closer to the drive unit 11 than a point 7% of the total length L0 of the torsion portion 12 from the end of the torsion portion 12 on the drive unit 11 side, it is assumed that the maximum stress (torsional stress) of the torsion portion 12 generated during the resonant operation of the movable part 20 can be minimized, thereby reliably suppressing damage to the torsion portion 12 due to torsional stress.

[0097] From the simulation results in Figures 5 and 7, it can be assumed that, in the configuration of Figure 8, when the movable part 20 includes the frame part 22, the upper limit of the range in which the maximum stress is substantially minimized will be several percent larger than the 7% shown in Figure 9, as described above. Therefore, when the movable part 20 includes the frame part 22 in this way, even if the position of the node S1 is set on the drive unit 11 side of a position that is about 10 percent greater than 7% of the total length L0 of the torsion part 12 from the end of the torsion part 12 on the drive unit 11 side, it can be assumed that the maximum stress (torsional stress) of the torsion part 12 generated during the resonant operation of the movable part 20 can be minimized, and damage to the torsion part 12 due to torsional stress can be reliably suppressed.

[0098] <Effects of Embodiment 3> With the configuration of Embodiment 2, as with Embodiment 1, by driving the movable part 20 in reverse phase mode and setting the position of the node S1 near the end (other end) of the torsion part 12 on the drive unit 11 side, it is possible to suppress unwanted vibrations that occur during the resonant operation of the movable part 20 while suppressing damage to the torsion part 12 due to torsional stress.

[0099] As shown in Figure 8, the drive element 1 comprises only one drive unit 10, which includes a torsion section 12 and a drive section 11.

[0100] This configuration allows the drive element 1 to be made simple and compact.

[0101] From the simulation results in Figure 9, it is preferable that in the configuration of Embodiment 3, the node S1 is set on the drive unit 11 side of a position that is 7% of the total length L0 of the torsion portion 12 from the end (other end) of the torsion portion 12 on the drive unit 11 side.

[0102] By setting the position of node S1 in this manner, the maximum torsional stress generated in the torsion section 12 can be made substantially equal to the maximum torsional stress that would occur if node S1 were not present in the torsion section 12. Therefore, damage to the torsion section 12 due to torsional stress can be reliably suppressed. Furthermore, in the range on the drive section 11 side of a position 7% of the total length L0 of the torsion section 12 from the other end, even if the position of node S1 fluctuates, the maximum torsional stress generated in the torsion section 12 does not substantially change. Therefore, even if the position of node S1 deviates slightly from the intended position due to manufacturing errors, etc., the maximum torsional stress generated in the torsion section 12 can be substantially minimized, and damage to the torsion section 12 due to torsional stress can be reliably suppressed.

[0103] <Embodiment 4> Figure 10 is a plan view showing the configuration of the drive element 2 according to Embodiment 4.

[0104] In Embodiment 4, a drive element 1 having the same configuration as in Embodiment 1 is included in the drive element 2 as an element unit that rotates the movable part 20. The drive element 2 further comprises another drive unit 40 and another base unit 50.

[0105] The other drive units 40 are connected to the base 30 and rotate the base 30 about another pivot axis R2 that intersects the pivot axis R1 in a plan view. Here, pivot axis R2 intersects pivot axis R1 perpendicularly. The angle between pivot axes R1 and R2 in a plan view may be slightly off from 90°. A pair of other drive units 40 are arranged on either side of the base 30 in a direction parallel to pivot axis R2. The other base 50 is a frame-shaped member that supports the pair of other drive units 40. The drive element 2 has a symmetrical shape with respect to the center of the movable part 20.

[0106] The base 30 is rotated about the pivot axis R2 by a pair of other drive units 40, thereby causing the movable part 20 to rotate about the pivot axis R2. The movable part 20 is rotated about two pivot axes R1 and R2 by the drive unit 11 of the drive element 1 and the other drive units 40 that support the drive element 1, causing the light incident on the reflective surface 23 to be scanned in two dimensions.

[0107] Each of the other drive units 40 is a meander type drive unit. Each of the other drive units 40 has four plate portions 41 connected in a meander manner. In plan view, each plate portion 41 is a rectangle elongated in the Y-axis direction. A piezoelectric element 42 is arranged on the upper surface of each plate portion 41. The layer structure of the piezoelectric element 42 is the same as that of the piezoelectric element 112 in Embodiment 1 above. The two innermost plate portions 41 are in contact with one end of two connecting portions 43 at the ends furthest from the pivot axis R2. The other ends of the two connecting portions 43 are connected to the base portion 30 at the position of the pivot axis R2 in plan view.

[0108] The pair of other drive units 40 and the other base unit 50 share a common substrate with the drive element 1. Similar to the underside of the substrate of the base unit 30, another layer is laminated to the underside of the substrate of the base unit 50, increasing the thickness of the base unit 50. In addition, other layers are laminated to the parts that connect the four plate units 41 to the base unit 50 in a meander manner, and to the connecting units 43, increasing their thickness as well.

[0109] A wiring pattern for applying a drive signal to the four piezoelectric elements 112 of the drive element 1 extends from the upper surface of the substrate of the drive element 1, the upper surface of the substrate of the connecting portion 43, and the upper surface of the substrates of the other drive units 40 where the piezoelectric elements 42 are not located, to the upper surface of the substrate of the base unit 50. Similarly, a wiring pattern for applying a drive signal to the four piezoelectric elements 42 of each of the other drive units 40 extends from the upper surface of the substrate of the other drive units 40 where the piezoelectric elements 42 are not located, to the upper surface of the substrate of the base unit 50. Terminals connected to these wiring patterns are located on the upper surface of the substrate of the base unit 50. As in the first embodiment described above, these wiring patterns and terminals may have the same layer structure as the piezoelectric elements 112. Furthermore, the lower electrodes of these wirings are extended to the area of ​​the ground terminal, which serves as the ground terminal.

[0110] Of the four piezoelectric elements 42 on the positive X-axis side, the first and third piezoelectric elements 42 from the positive X-axis side are subjected to a drive signal of the same polarity, and of the four piezoelectric elements 42 on the negative X-axis side, the second and fourth piezoelectric elements 42 from the negative X-axis side are subjected to a drive signal of the opposite polarity to this drive signal, and the remaining four piezoelectric elements 42 are subjected to a drive signal of the opposite polarity. As a result, each piezoelectric element 42 is compressed or expanded in the Y-axis direction according to the polarity of the drive signal, and a driving force around the rotation axis R2 is applied to the drive element 1. In this way, the drive element 1 rotates around the rotation axis R2, and consequently, the movable part 20 rotates around the rotation axis R2.

[0111] In the configuration shown in Figure 10, the drive element 1 of Embodiment 1 is included in the drive element 2 as an element unit that rotates the movable part 20. However, the drive element 1 of Embodiment 2 or 3 may also be included in the drive element 2 as an element unit that rotates the movable part 20. Furthermore, the other drive unit 40 is not limited to a meander type drive unit; it may be a drive unit with another configuration, and the drive element 2 may be configured to include only one other drive unit 40.

[0112] <Effects of Embodiment 4> As shown in Figure 10, the drive element 2 includes another drive unit 40 connected to the base 30 that rotates the base 30 about another rotation axis R2 intersecting the rotation axis R1 in a plan view, and another base 50 that supports the other drive unit 40.

[0113] With this configuration, the movable part 20 can be rotated around two intersecting pivot axes R1 and R2.

[0114] Furthermore, as described above, the drive element 1 drives the movable part 20 in reverse phase mode, and by setting the position of the node S1 near the end (other end) of the torsion part 12 on the drive unit 11 side, unwanted vibrations that occur during the resonant operation of the movable part 20 are suppressed. Therefore, it is possible to suppress such unwanted vibrations from propagating from the connecting part 43 to the other drive unit 40 and interfering with the operation of the other drive unit 40. Thus, the movable part 20 can be rotated stably around the two intersecting rotation axes R1 and R2, and light can be scanned stably.

[0115] <Example of changes> The embodiments of the present invention are not limited to the above embodiments 1 to 4.

[0116] For example, the shapes of the drive elements 1 and 2 in a plan view, and the dimensional balance of each part of the drive elements 1 and 2, are not limited to the shapes and dimensional balances shown in the above embodiments 1 to 4, and can be modified as appropriate insofar as the objective of the present invention can be achieved.

[0117] For example, as shown in Figure 11, the pair of arm portions 111a may extend from the connecting portion 111b in an arc and deform in a direction parallel to the rotation axis R1. When operating in opposite phases as described above, the arm portions 111a and the torsion portion 12 twist in opposite directions, so the stress on the arm portions 111a tends to be high. For this reason, by making the arm portions 111a in an arc shape, as shown in Figure 11, it is possible to reduce the stress on the arm portions 111a that are close to the rotation axis R1. The same simulation results as in Figure 5 can be obtained with this configuration as well.

[0118] Furthermore, the driving element 1 may be used as an element other than an optical deflection element. When the driving element 1 is used as an element other than an optical deflection element, the reflective surface 23 does not need to be placed on the movable part 20, and other members other than the reflective surface 23 may be placed there.

[0119] 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.

[0120] (Note) The above description of embodiments discloses the following technologies.

[0121] (Technology 1) A movable part that performs resonant motion around the pivot axis at the target frequency, A torsion portion extending along the pivot axis and having one end connected to the movable part, A drive unit having a tuning fork vibrator connected to the other end of the torsion part, It comprises a base that supports the drive unit, The resonance operation at the target frequency is the operation of the movable part in an out-of-phase mode in which the movable part repeatedly rotates in the opposite phase to the tuning fork vibrator, The natural frequencies of the movable part and the torsion part and the natural frequency of the drive part are adjusted so that the position of the node where the twisting direction of the torsion part switches in the reverse-phase mode is near the other end of the torsion part. A driving element characterized by the following features.

[0122] According to this technology, the resonant operation of the movable part at the target frequency is in an out-of-phase mode. Therefore, during the resonant operation of the movable part, the vibrations generated in the movable part and the torsion part cancel each other out with the vibrations generated by the tuning fork vibrator. As a result, unwanted vibrations generated during the resonant operation of the movable part can be effectively suppressed. On the other hand, in the out-of-phase mode, the tuning fork vibrator and the movable part resonate in out-of-phase with each other, so a node can be generated in the torsion part where the twisting direction switches. That is, no twisting occurs in the torsion part at the node's position, and the twisting direction of the torsion part is reversed in the range from the node's position towards the movable part and in the range from the node's position towards the drive part. Here, the closer the node is to the movable part, the shorter the portion of the torsion part from the node to the movable part becomes, and the greater the torsional stress in this portion. In contrast, in the drive element according to this embodiment, as described above, the node is positioned near the other end, i.e., the end of the torsion part connected to the drive part. Therefore, the portion of the torsion part from the node to the movable part can be made longer, and the excessively large torsional stress generated in this portion can be suppressed. This helps to prevent damage to the torsion joint caused by torsional stress.

[0123] Thus, the drive element according to this embodiment can suppress unwanted vibrations that occur during the resonant operation of the movable part, while also suppressing damage to the torsion part due to torsional stress.

[0124] (Technology 2) In the driving element described in Technology 1, The aforementioned section is set on the drive unit side of a position that is 12% of the total length of the torsion section from the other end. A driving element characterized by the following features.

[0125] This technology allows the maximum torsional stress generated in the torsion joint to be suppressed to approximately 1.5 times or less the maximum torsional stress generated in the torsion joint when there are no joints in the torsion joint. Therefore, damage to the torsion joint caused by torsional stress can be effectively suppressed.

[0126] (Technology 3) In the driving element described in Technology 1 or 2, Two drive units, each comprising the torsion section and the drive section, are arranged in opposite directions with the movable section in between. The torsion portion of each of the drive units is connected to the movable portion. A driving element characterized by the following features.

[0127] According to this technology, since the movable parts are supported and driven by each drive unit, the movable parts can be driven stably with greater torque.

[0128] (Technology 4) In the driving element described in Technology 3, The aforementioned movable part is The driven part and, In a plan view, it consists of a frame that surrounds the driven part and is connected to the driven part near the position of the driven part furthest from the pivot axis, Each of the aforementioned drive units has a torsion section connected to the frame section. A driving element characterized by the following features.

[0129] According to this technology, the area of ​​the driven part furthest from the pivot axis, i.e., the area of ​​the driven part most susceptible to distortion during rotation, is supported by the frame, and the driving force from the torsion section is applied to this end. Therefore, distortion of the driven part that occurs during rotation can be effectively suppressed.

[0130] (Technology 5) In the driving element described in Technology 4, The aforementioned section is set on the drive unit side of a position that is 10% of the total length of the torsion section from the other end. A driving element characterized by the following features.

[0131] By setting the position of the nodes in this way, the maximum torsional stress generated in the torsion section can be made substantially equal to the maximum torsional stress that would occur if there were no nodes in the torsion section. Therefore, damage to the torsion section due to torsional stress can be reliably suppressed. Furthermore, in the range on the drive section side of a position 10% of the total length of the torsion section from the other end, the maximum torsional stress generated in the torsion section does not substantially change even if the position of the nodes fluctuates. Therefore, by setting the position of the nodes within this range, even if the position of the nodes deviates slightly from the intended position due to manufacturing errors, etc., the maximum torsional stress generated in the torsion section can be substantially minimized, and damage to the torsion section due to torsional stress can be reliably suppressed.

[0132] (Technology 6) In the driving element described in Technology 3, In a plan view, the aforementioned movable part extends continuously without gaps from the center to the outer circumference. A driving element characterized by the following features.

[0133] This technology eliminates the need for a frame in the movable parts, thus simplifying the structure of the movable parts and reducing their weight.

[0134] (Technology 7) In the driving element described in Technical 6, The aforementioned section is set on the drive unit side of a position that is 5% of the total length of the torsion section from the other end. A driving element characterized by the following features.

[0135] By setting the position of the nodes in this way, the maximum torsional stress generated in the torsion section can be made substantially equal to the maximum torsional stress that would occur if there were no nodes in the torsion section. Therefore, damage to the torsion section due to torsional stress can be reliably suppressed. Furthermore, in the range on the drive section side of a position 5% of the total length of the torsion section from the other end, even if the position of the nodes fluctuates, the maximum torsional stress generated in the torsion section does not substantially change. Therefore, even if the position of the nodes deviates slightly from the intended position due to manufacturing errors, etc., the maximum torsional stress generated in the torsion section can be substantially minimized, and damage to the torsion section due to torsional stress can be reliably suppressed.

[0136] (Technology 8) In the driving element described in Technology 1 or 2, The drive unit comprises only one unit including the torsion section and the drive section. A driving element characterized by the following features.

[0137] This technology allows for simpler and smaller drive elements.

[0138] (Technology 9) In the driving element described in Technical 8, The aforementioned section is set on the drive unit side of a position that is 7% of the total length of the torsion section from the other end. A driving element characterized by the following features.

[0139] By setting the position of the nodes in this way, the maximum torsional stress generated in the torsion section can be made substantially equal to the maximum torsional stress that would occur if there were no nodes in the torsion section. Therefore, damage to the torsion section due to torsional stress can be reliably suppressed. Furthermore, in the range on the drive section side of a position 7% of the total length of the torsion section from the other end, even if the position of the nodes changes, the maximum torsional stress generated in the torsion section does not substantially change. Therefore, even if the position of the nodes deviates slightly from the intended position due to manufacturing errors, etc., the maximum torsional stress generated in the torsion section can be substantially minimized, and damage to the torsion section due to torsional stress can be reliably suppressed.

[0140] (Technology 10) In the driving element described in any of Technology 1 to 9, A drive unit connected to the base and which rotates the base about another pivot axis that intersects the pivot axis in a plan view, The system comprises another base that supports the other drive unit, A driving element characterized by the following features.

[0141] This technology allows the movable part to rotate around two intersecting pivot axes.

[0142] (Technology 11) In the driving element described in any of Technology 1 to 10, The drive unit has a piezoelectric element as a drive source. A driving element characterized by the following features.

[0143] This technology allows for the smooth operation of a tuning fork oscillator.

[0144] (Technology 12) In the driving element described in any of Technology 1 to 11, The movable part has a reflective surface that reflects incident light. A driving element characterized by the following features.

[0145] This technology allows light incident on a reflective surface to be scanned by the rotational movement of a movable part, and the driving element can be configured as an optical deflection element. [Explanation of Symbols]

[0146] 1, 2 Driving elements 10 Drive Unit 11 Drive unit 20 Moving parts 21 Driven part 22 Frame section 23 Reflective surface 30, 50 base 40 Other drive units 111 Tuning Fork Oscillator 112 Piezoelectric material R1, R2 pivot axes

Claims

1. A movable part that performs resonant motion around the pivot axis at the target frequency, A torsion portion extending along the pivot axis and having one end connected to the movable part, A drive unit having a tuning fork vibrator connected to the other end of the torsion part, It comprises a base that supports the drive unit, The resonance operation at the target frequency is the operation of the movable part in an out-of-phase mode in which the movable part repeatedly rotates in the opposite phase to the tuning fork vibrator, The natural frequencies of the movable part and the torsion part and the natural frequency of the drive part are adjusted so that the position of the node where the twisting direction of the torsion part switches in the reverse-phase mode is near the other end of the torsion part. A driving element characterized by the following features.

2. In the drive element according to claim 1, The aforementioned section is set on the drive unit side of a position that is 12% of the total length of the torsion section from the other end. A driving element characterized by the following features.

3. In the drive element according to claim 1, Two drive units, each comprising the torsion section and the drive section, are arranged in opposite directions with the movable section in between. The torsion portion of each of the drive units is connected to the movable portion. A driving element characterized by the following features.

4. In the drive element according to claim 3, The aforementioned movable part is The driven part and, In a plan view, it consists of a frame that surrounds the driven part and is connected to the driven part near the position of the driven part furthest from the pivot axis, Each of the aforementioned drive units has a torsion section connected to the frame section. A driving element characterized by the following features.

5. In the drive element according to claim 4, The aforementioned section is set on the drive unit side of a position that is 10% of the total length of the torsion section from the other end. A driving element characterized by the following features.

6. In the drive element according to claim 3, In a plan view, the aforementioned movable part extends continuously without gaps from the center to the outer circumference. A driving element characterized by the following features.

7. In the drive element according to claim 6, The aforementioned section is set on the drive unit side of a position that is 5% of the total length of the torsion section from the other end. A driving element characterized by the following features.

8. In the drive element according to claim 1, The system comprises only one drive unit, which includes the torsion section and the drive section. A driving element characterized by the following features.

9. In the driving element according to claim 8, The aforementioned section is set on the drive unit side of a position that is 7% of the total length of the torsion section from the other end. A driving element characterized by the following features.

10. In the drive element according to claim 1, A drive unit connected to the base and which rotates the base about another pivot axis that intersects the pivot axis in a plan view, The system comprises another base that supports the other drive unit, A driving element characterized by the following features.

11. In the drive element according to claim 1, The drive unit has a piezoelectric element as a drive source. A driving element characterized by the following features.

12. In the driving element according to any one of claims 1 to 11, The movable part has a reflective surface that reflects incident light. A driving element characterized by the following features.

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