Tuning fork type drive element and light deflection element

Abstract

A tuning fork type drive element (1) is provided with: a movable part (40) capable of rotating about a rotation axis (R10); a connecting part (32) extending from the movable part (40) along the rotation axis (R10); a pair of arm parts (20) disposed so as to sandwich the connecting part (32) therebetween; a support section (31) that connects the connection section (32) and the pair of arm sections (20) to the fixed section (10); and a drive unit (50) disposed on the arm unit (20). The pair of arm sections (20) have protrusions (21, 22) that overlap a nodal line (S10) or an extension line of the nodal line (S10) generated when vibrated in a high-order vibration mode higher than the first-order vibration mode.

Description

Technical Field

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

[0002] In recent years, a driving element that rotates a movable part has been developed using MEMS (Micro Electro Mechanical System) technology. 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 jitter angle (Japanese: 振れ角). This driving element is, for example, mounted on image display devices such as head-up displays and head-mounted displays. In addition, this driving element can also be used in laser radars that use laser beams to detect objects.

[0003] The following patent document 1 describes a tuning fork type driving element that rotates a movable part by a so-called tuning fork vibrator. In this driving element, the movable part is connected to the tuning fork vibrator by 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 a set surface. By driving the tuning fork vibrator, the movable part rotates around the rotation axis, and the reflecting surface arranged on the movable part rotates accordingly.

[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] The tuning fork type driving element can be driven in a higher order vibration mode than the first order to make the movable part vibrate at a higher frequency. In this case, when the characteristic frequency of the higher order vibration mode is close to an integer multiple of the characteristic frequency of the first order vibration mode, the first order vibration mode affects the higher order vibration mode, causing problems in the operation of the tuning fork type vibrator.

[0009] In this regard, for example, the characteristic frequency of the first-order vibration mode can be changed by changing the length and thickness of the tuning fork vibrator. However, in this method, since the characteristic frequency of the second-order vibration mode is also changed at the same time, it is difficult to design so that the characteristic frequency of the higher-order vibration mode is the target frequency while changing the characteristic frequency of the first-order vibration mode.

[0010] In view of the above problems, an object of the present invention is to provide a tuning fork type driving element and an optical deflection element that can set the characteristic frequency of a high-order vibration mode used during driving to a target frequency, and can easily adjust the characteristic frequency of a low-order vibration mode lower than the high-order vibration mode to a frequency that does not easily affect the high-order vibration mode.

[0011] Solution for Solving the Problem

[0012] The tuning fork type driving element according to the first aspect of the present invention includes: a movable part that can rotate around a rotation axis; a connecting part that extends along the rotation axis from the movable part; a pair of arm parts that are arranged with the connecting part sandwiched therebetween; a support part that connects the connecting part and the pair of arm parts to a fixed part; and a driving part that is arranged on the arm parts. The pair of arm parts have protrusions that overlap on a nodal line generated when vibrating in a high-order vibration mode higher than the first-order vibration mode or on an extension line of the nodal line.

[0013] According to the tuning fork type driving element according to this aspect, the characteristic frequency of the low-order vibration mode can be changed by the protrusions as mass parts, and the characteristic frequency of the low-order vibration mode can be controlled by adjusting the mass of the protrusions such as the length of the protrusions. In addition, since the protrusions as mass parts are formed on the nodal line or the extension line of the nodal line, the influence of the mass of the protrusions on the characteristic frequency of the high-order vibration mode can be suppressed. Therefore, it is possible to easily adjust the characteristic frequency of the low-order vibration mode lower than the vibration mode to a frequency that does not easily affect the high-order vibration mode without causing a large difference between the characteristic frequency in the high-order vibration mode and the target frequency.

[0014] The optical deflection element according to the second aspect of the present invention includes: the tuning fork type driving element according to the first aspect; and a reflecting surface that is arranged on the movable part.

[0015] According to the optical deflection element according to this aspect, since the optical deflection element includes the tuning fork type driving element of the first aspect, the reflecting surface can vibrate smoothly and stably in a high-order vibration mode. Therefore, the light incident on the reflecting surface can be stably deflected as the movable part vibrates.

[0016] The tuning fork type driving element according to the third aspect of the present invention includes: a pair of arm parts that are arranged with a rotation axis sandwiched therebetween; a support part that connects the pair of arm parts to a fixed part; and a driving part that is arranged on the arm parts. The pair of arm parts have protrusions or recesses, the protrusions overlap on a nodal line generated when vibrating in a high-order vibration mode higher than the first-order vibration mode or on an extension line of the nodal line, and the recesses overlap with the nodal line.

[0017] The tuning fork type driving element according to this mode has the same effect as that of the first mode.

[0018] The optical deflection element according to the fourth mode of the present invention includes: the tuning fork type driving element according to the third mode described above; and a reflecting surface disposed on the movable portion.

[0019] The optical deflection element according to this mode has the same effect as that of the second mode.

[0020] Effects of the Invention

[0021] As described above, according to the present invention, it is possible to provide a tuning fork type driving element and an optical deflection element that can set the characteristic frequency of the high-order vibration mode used during driving to a target frequency, and at the same time, easily adjust the characteristic frequency of the low-order vibration mode lower than the high-order vibration mode to a frequency that does not easily affect the high-order vibration mode.

[0022] The effects and significance of the present invention become clearer through the description of the embodiments shown below. However, the embodiments shown below are only examples when implementing the present invention, and the present invention is not limited by any of the contents described in the following embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a top view schematically showing the structures of the tuning fork type driving element and the optical deflection element according to Embodiment 1.

[0024] Figure 2 It is a cross-sectional view when observing the C1-C2 cross-section from the negative X-axis direction according to Embodiment 1.

[0025] Figure 3 (a) thereof is a top view schematically showing the structure of the tuning fork type driving element involved in the verification of the comparative example. Figure 3 (b) of Figure 3 and (c) thereof are the measured results of the waveforms showing the front end positions of the arms involved in the verification of the comparative example.

[0026] Figure 4 (a) to Figure 4 (c) thereof are top views schematically showing the structures of the arms when the length of the protrusion is changed in the simulation according to Embodiment 1.

[0027] Figure 5 (a) to Figure 5 (c) thereof are diagrams showing the simulation results when the length of the protrusion is changed in the simulation according to Embodiment 1.

[0028] Figure 6 (a) to Figure 6(c) is a top view schematically showing the structure of the arm portion in the case where the position of the protrusion is changed in the simulation related to Embodiment 1.

[0029] Figure 7 (a) to Figure 7 (c) are diagrams showing the simulation results when the position of the protrusion is changed in the simulation related to Embodiment 1.

[0030] Figure 8 is a top view schematically showing the structure of the tuning fork type drive element and the optical deflection element related to Embodiment 2.

[0031] Fig. 9 (a) to Fig. 9 (c) are top views schematically showing the structure of the arm portion in the case where the length of the protrusion is changed in the simulation related to Embodiment 2.

[0032] Fig.10 (a) to Fig.10 (c) are diagrams showing the simulation results when the length of the protrusion is changed in the simulation related to Embodiment 2.

[0033] Fig.11 (a) to Fig.11 (c) are top views schematically showing the structure of the arm portion in the case where the mass of the protrusion is made constant and the length and width of the protrusion are changed in the simulation related to Embodiment 2.

[0034] Fig.12 (a) to Fig.12 (c) are diagrams showing the simulation results when the mass of the protrusion is made constant and the length and width of the protrusion are changed in the simulation related to Embodiment 2.

[0035] Fig.13 (a) to Fig.13 (c) are top views schematically showing the structure of the arm portion in the case where the sum of the lengths of the protrusions is made constant and the length of the protrusion is changed in the simulation related to Embodiment 2.

[0036] Fig.14 (a) to Fig.14 (c) are diagrams showing the simulation results representing the displacement amount in the Z-axis direction when the sum of the lengths of the protrusions is made constant and the length of the protrusion is changed in the simulation related to Embodiment 2.

[0037] Fig.15 (a) to Fig.15 (c) are diagrams showing the simulation results when the sum of the lengths of the protrusions is made constant and the length of the protrusion is changed in the simulation related to Embodiment 2.

[0038] Fig.16 (a) to Fig.16 (c) of FIG. are respectively top views schematically showing the structure of the arm portion in the case where the position of the protrusion is shifted in the X-axis direction from the position on the extension line of the nodal line in the simulation of Embodiment 2.

[0039] Fig.17 (a) to Fig.17 (c) of FIG. are respectively diagrams showing the simulation results of the displacement amount in the Z-axis direction in the case where the position of the protrusion is shifted in the X-axis direction from the position on the extension line of the nodal line in the simulation of Embodiment 2.

[0040] Fig.18 (a) to Fig.18 (c) of FIG. are respectively top views schematically showing the structure of the arm portion in the case where the position of the protrusion is shifted in the X-axis direction from the position on the extension line of the nodal line in the simulation of the comparative example.

[0041] Fig.19 (a) to Fig.19 (c) of FIG. are respectively diagrams showing the simulation results of the displacement amount in the Z-axis direction in the case where the position of the protrusion is shifted in the X-axis direction from the position on the extension line of the nodal line in the simulation of the comparative example.

[0042] Fig. 20 (a) to Fig. 20 (c) of FIG. are respectively top views schematically showing the structure of the first driving unit related to the modification example of the protrusion.

[0043] Fig.21 (a) to Fig.21 (c) of FIG. are respectively top views schematically showing the structure of the first driving unit related to the modification example of the protrusion.

[0044] Fig. 22 (a) and Fig. 22 (b) of FIG. are respectively top views schematically showing the structure of the first driving unit related to the modification example of the protrusion.

[0045] Fig.23 (a) of FIG. is a top view (rear view) schematically showing the structure of the first driving unit related to another modification example of the protrusion. Fig.23 (a) of FIG. is a top view (rear view) schematically showing the structure of the first driving unit in the case where a concave portion is provided at the position corresponding to the nodal line of the arm portion and a concave portion is provided at the position of the nodal line in another modification example.

[0046] Fig.24 (a) to Fig.24 (c) respectively show the simulation results of the displacement in the Z-axis direction when the arm is driven in the second-order vibration mode, third-order vibration mode, and fourth-order vibration mode, which relate to the modification examples of the high-order vibration mode.

[0047] Fig.25 (a) to Fig.25 (c) respectively show the simulation results of the displacement in the Z-axis direction when the arm is driven in the second-order vibration mode, third-order vibration mode, and fourth-order vibration mode, which relate to the modification examples of the high-order vibration mode.

[0048] Fig.26 (a) to Fig.26 (c) respectively show the simulation results of the displacement in the Z-axis direction when the arm is driven in the second-order vibration mode, third-order vibration mode, and fourth-order vibration mode, which relate to the modification examples of the high-order vibration mode.

[0049] Fig. 27 (a) and Fig. 27 (b) respectively show the simulation results of the displacement in the Z-axis direction when the arm is driven in the second-order vibration mode and third-order vibration mode, which relate to the modification examples of the high-order vibration mode.

[0050] Fig.28 is a top view schematically showing the structures of the tuning fork type driving element and the light deflecting element according to other modification examples.

[0051] Fig.29 is a top view schematically showing the structure of the tuning fork type driving element according to still another other modification example.

[0052] However, the drawings are for illustrative purposes only and do not limit the scope of the present invention. Detailed Embodiments

[0053] Hereinafter, embodiments of the present invention will be described with reference to the drawings. For convenience, X, Y, and Z axes orthogonal to each other are added to each drawing. The positive direction of the Z axis is the vertically upward direction.

[0054] <Embodiment 1>

[0055] Figure 1 is a top view schematically showing the structures of the tuning fork type driving element 1 and the light deflecting element 2.

[0056] The tuning fork type driving element 1 includes a first driving unit 1a, a second driving unit 1b, a fixed portion 10, and a movable portion 40. The first driving unit 1a and the second driving unit 1b each include a pair of arm portions 20 arranged along the Y-axis direction, a support portion 31, a connecting portion 32, and a pair of driving portions 50. The tuning fork type driving element 1 is configured to be symmetrical about a center C10 in the X-axis direction and the Y-axis direction when viewed from above. The light deflection element 2 is configured by forming a reflection surface 41 on the upper surface of the movable portion 40.

[0057] The first drive unit 1a and the second drive unit 1b rotate the movable part 40 around the rotation axis R10 by supplying a drive voltage from a drive circuit (not shown) to each drive part 50. The reflective surface 41 reflects light incident from above the movable part 40 in a direction corresponding to the rotation angle (Japanese: vibration angle) of the movable part 40. Thus, the light (for example, a laser beam) incident on the reflective surface 41 is deflected as the movable part 40 rotates to perform scanning.

[0058] The fixed part 10 is configured in a frame shape. The four arm parts 20 and the pair of connecting parts 32 are located in the opening 11 penetrating the fixed part 10 in the Z-axis direction at the center of the fixed part 10 in a plan view, and are arranged between the fixed part 10 and the movable part 40. The first drive unit 1a and the second drive unit 1b are respectively arranged on the positive side of the X axis and the negative side of the X axis of the movable part 40. The pair of arm parts 20 provided in each of the first drive unit 1a and the second drive unit 1b are in the shape of a tuning fork in a plan view.

[0059] The arm portion 20 has a substantially L-shape when viewed from above. A pair of arm portions 20 arranged along the Y-axis direction is arranged so as to sandwich the connecting portion 32. The arm portion 20 has a first portion 20a extending in a direction away from the rotation axis R10 and a second portion 20b extending from the end of the first portion 20a in a direction close to the movable portion 40 (X-axis direction). The first portion 20a is connected to the support portion 31 on the side opposite to the second portion 20b. The drive portion 50 is mainly arranged on the upper surface of the second portion 20b. Here, the first portion 20a extends in a direction close to the movable portion 40 at a predetermined angle relative to a direction perpendicular to the rotation axis R10. The first portion 20a may also extend in a direction perpendicular to the rotation axis R10.

[0060] On the inner side surface of the second part 20b on the side closer to the rotation axis R10, a protrusion 21 extending in the direction approaching the rotation axis R10 is formed. On the outer side surface of the second part 20b on the side opposite to the rotation axis R10, a protrusion 21 extending in the direction away from the rotation axis R10 is formed. Specifically, the protrusion 21 extends in the direction perpendicular to the second part 20b (Y-axis direction) on the inner side surface of the second part 20b, and the protrusion 22 extends in the direction perpendicular to the second part 20b (Y-axis direction) on the outer side surface of the second part 20b. In addition, the protrusions 21 and 22 are formed so as to overlap on the extension line of the nodal line S10 described later in a plan view. In Figure 1 , the nodal line S10 is represented by a thick solid line, and the extension line of the nodal line S10 is represented by a dotted line.

[0061] The support portion 31 connects the connecting portion 32 and a pair of arm portions 20 arranged in the Y-axis direction to the fixed portion 10. The outer edge on the outer side in the X-axis direction of the support portion 31 is connected to the fixed portion 10. The connecting portion 32 extends in the X-axis direction along the rotation axis R10 starting from the movable portion 40. The outer end portion in the X-axis direction of the connecting portion 32 is connected to the support portion 31. The end portions on the positive X-axis side and the negative X-axis side of the movable portion 40 are connected to the inner end portions in the Y-axis direction of a pair of connecting portions 32.

[0062] The movable portion 40 has a circular shape in a plan view. The movable portion 40 is supported by the fixed portion 10 via a pair of support portions 31 and a pair of connecting portions 32 so as to be rotatable about the rotation axis R10. The center of the movable portion 40 coincides with the position of the center C10 of the tuning fork type driving element 1.

[0063] An optical reflection film is formed on the upper surface of the movable portion 40. The optical reflection film is made of a material with a high reflectivity (for example, metals such as gold, silver, copper, and aluminum, metal compounds, or silicon dioxide, titanium dioxide, etc.). The optical reflection film may also be composed of a dielectric multilayer film. By forming the optical reflection film on the upper surface of the movable portion 40, the upper surface of the optical reflection film constitutes a reflection surface 41 that reflects light. The reflection surface 41 may also be constituted by the upper surface of the movable portion 40.

[0064] The driving portion 50 is formed on the upper surface of the arm portion 20. The driving portion 50 is connected to the electrode on the fixed portion 10 via the wiring on the arm portion 20, the support portion 31, and the fixed portion 10. A cable (external wiring) connected to an external device is connected to the electrode on the fixed portion 10 by wire bonding.

[0065] When a driving voltage is applied to the driving portion 50, the piezoelectric layer 112 in the driving portion 50 (refer to Figure 2)Due to the inverse piezoelectric effect, the arm portion 20 provided with the drive portion 50 undergoes flexural vibration. At this time, drive voltages with opposite phases are applied to the two drive portions 50 arranged in the Y-axis direction, and drive voltages with the same phase are applied to the two drive portions 50 arranged in the X-axis direction. As a result, a pair of arm portions 20 on the positive Y-axis side of the rotation axis R10 and a pair of arm portions 20 on the negative Y-axis side of the rotation axis R10 flex in opposite directions. In this way, the movable portion 40 rotates about the rotation axis R10 due to the deformation of the four arm portions 20.

[0066] Figure 2 when viewed from the negative X-axis direction Figure 1 is a cross-sectional view of the C1 - C2 cross-section.

[0067] The arm portion 20 is composed of a base layer 101. The drive portion 50 is formed on the upper surface of the arm portion 20 and has a layer structure composed of a lower electrode layer 111, a piezoelectric layer 112, and an upper electrode layer 113. The base layer 101 is made of, for example, silicon (Si). The lower electrode layer 111 is made of, for example, platinum (Pt). The piezoelectric layer 112 is a piezoelectric thin film, and the piezoelectric thin film is made of, for example, PZT (lead zirconate titanate: Pb(Zr,Ti)O3). The upper electrode layer 113 is made of, for example, gold (Au).

[0068] The protrusion 22 is formed by the base layer 101 of the arm portion 20 protruding in the negative Y-axis direction and is formed integrally with the arm portion 20. In addition, the protrusion 21 is also formed in the same manner as the protrusion 22. That is, the protrusion 21 is formed by the base layer 101 of the arm portion 20 protruding in the positive Y-axis direction and is formed integrally with the arm portion 20.

[0069] Here, in Embodiment 1, the arm portion 20 is driven in the second-order vibration mode so that the movable portion 40 vibrates at a higher frequency. When the arm portion 20 is driven in the second-order vibration mode in this way, according to the research findings of the inventors, when the characteristic frequency of the second-order vibration mode approaches an integer multiple of the characteristic frequency of the first-order vibration mode, the first-order vibration mode affects the second-order vibration mode, resulting in problems in the operation of the tuning fork type drive element 1. The following will refer to Figure 3 in (a) to Figure 3 illustrate such problems through the verification of the comparative examples shown in (c).

[0070] Figure 3 (a) of is a top view schematically showing the structure of the tuning fork type drive element 1 involved in the verification of the comparative example. Figure 3 in (b) and Figure 3 in (c) are the measured results of the waveforms showing the positions of the front ends of the arm portions 20 in the Z-axis direction involved in the verification of the comparative example.

[0071] As shown in Figure 3As shown in (a) of , the tuning fork type drive element 1 of the comparative example includes a first drive unit 1a and a fixing portion 10 around the support portion 31. In this case, the connecting portion 32 is omitted from the first drive unit 1a. In the comparative example, different from the first embodiment, the protrusions 21 and 22 are not formed on the arm portion 20.

[0072] In the verification of the comparative example, the shape of the arm portion 20 and the like were adjusted so that the characteristic frequency of the arm portion 20 in the second-order vibration mode was 62984.3 Hz as shown in the waveform of (b) of . If the arm portion 20 vibrates only in the second-order vibration mode, the vibration of the arm portion 20 at this time is an ideal vibration. Figure 3 As shown in the waveform of (b) of , the characteristic frequency of the arm portion 20 in the second-order vibration mode was 62984.3 Hz. If the arm portion 20 vibrates only in the second-order vibration mode, the vibration of the arm portion 20 at this time is an ideal vibration.

[0073] However, in reality, in addition to the vibration generated by the second-order vibration mode, the vibration generated by the first-order vibration mode is also applied. In the verification of the comparative example, the characteristic frequency of the arm portion 20 in the first-order vibration mode at this time was 12240 Hz. In this case, the characteristic frequency of the second-order vibration mode was 5.15 times the characteristic frequency of the first-order vibration mode.

[0074] In this way, when the characteristic frequency of the second-order vibration mode is approximately an integer multiple of the characteristic frequency of the first-order vibration mode, the second-order vibration mode and the first-order vibration mode occur simultaneously. As a result, the vibration of the first-order vibration mode is superimposed on the vibration of the second-order vibration mode, and an undesired vibration is generated as shown in the waveform of (c) of . This undesired vibration may cause damage to the arm portion 20. Figure 3 As shown in the waveform of (c) of , an undesired vibration is generated. This undesired vibration may cause damage to the arm portion 20.

[0075] In response to this, it is possible to adjust the shape of the arm portion 20 and the like to change the characteristic frequency of the first-order vibration mode so that the characteristic frequency of the second-order vibration mode is not approximately an integer multiple of the characteristic frequency of the first-order vibration mode. However, in this method, the characteristic frequency of the second-order vibration mode also changes simultaneously, so it is difficult to design such that the characteristic frequency of the second-order vibration mode is the target frequency while changing the characteristic frequency of the first-order vibration mode.

[0076] Therefore, in the first embodiment, first, the characteristic frequency of the second-order vibration mode is set as the target frequency. Through the second-order vibration mode, a nodal line S10 as shown in is formed on the arm portion 20. The vibration in the Z-axis direction of the arm portion 20 generated by the second-order vibration mode is substantially zero at the position of the nodal line S10. That is, the nodal line S10 is a line along the nodal portion where the amplitude in the vibration direction where almost no vibration is generated when the arm portion 20 vibrates at the target characteristic frequency (second-order vibration mode). Figure 1 As shown in , a nodal line S10 is formed. The vibration in the Z-axis direction of the arm portion 20 generated by the second-order vibration mode is substantially zero at the position of the nodal line S10. That is, the nodal line S10 is a line along the nodal portion where the amplitude in the vibration direction where almost no vibration is generated when the arm portion 20 vibrates at the target characteristic frequency (second-order vibration mode).

[0077] After that, by adjusting to overlap with the extension line of the nodal line S10 ( Figure 1The position, length, width, etc. of the protrusions 21 and 22 arranged in a manner on the dashed line) are adjusted to adjust the characteristic frequency of the first-order vibration mode. At this time, since the protrusions 21 and 22 as the mass portions are formed on the extension line of the nodal line S10, the influence of the mass of the protrusions 21 and 22 on the characteristic frequency of the second-order vibration mode can be suppressed. Therefore, the characteristic frequency in the first-order vibration mode can be easily adjusted to a frequency that does not easily affect the second-order vibration mode without causing a large difference between the characteristic frequency in the second-order vibration mode and the target frequency.

[0078] Next, refer to Figure 4 (a) to Figure 7 (c) of Embodiment 1 to describe an example of adjusting the structure of the protrusions 21 and 22 to suppress the influence of the first-order vibration mode. The inventors obtained the ratio FR of the characteristic frequency of the second-order vibration mode to the characteristic frequency of the first-order vibration mode by changing the length and position of the protrusions 21 and 22 through simulation.

[0079] The tuning fork type driving element 1 in the simulation of Embodiment 1 shown below, for example Figure 4 has a first driving unit 1a and a fixing portion 10 around the support portion 31 as shown in (b). In this case, the connecting portion 32 is omitted from the first driving unit 1a.

[0080] Figure 4 (a) to Figure 4 (c) are top views schematically showing the structure of the arm portion 20 when the length L1 of the protrusions 21 and 22 is changed in the simulation of Embodiment 1. In Figure 4 (a), for comparison, the same structure as the comparative example shown in Figure 3 (a) is shown.

[0081] Figure 4 (a) to Figure 4 (c) respectively show the states where the length L1 of the protrusions 21 and 22 is 0 μm, 200 μm, and 500 μm. The length L1 is the length in the Y-axis direction of the protrusions 21 and 22 protruding from the arm portion 20 in the Y-axis direction. In this simulation, the length of the protrusion 21 and the length of the protrusion 22 are both L1. The protrusions 21 and 22 are arranged to overlap on the extension line of the nodal line S10.

[0082] Figure 5 (a) to Figure 5 (c) are diagrams showing the simulation results when the length L1 of the protrusions 21 and 22 is changed in the range of 0 μm to 500 μm in the structure of Figure 4 (a) to Figure 4 (c).

[0083] Figure 5(a) is a graph showing the characteristic frequencies of the first-order vibration mode and the second-order vibration mode when the lengths L1 of the protrusions 21 and 22 are varied within the range of 0 μm to 500 μm. Figure 5 (b) is a graph showing the amounts of change in the characteristic frequencies of the first-order vibration mode and the second-order vibration mode when the lengths L1 of the protrusions 21 and 22 are varied within the range of 0 μm to 500 μm.

[0084] As Figure 5 shown in (a) and Figure 5 shown in (b), the amount of change in the characteristic frequency of the first-order vibration mode varies significantly according to the change in the lengths L1 of the protrusions 21 and 22. On the other hand, even when the lengths L1 of the protrusions 21 and 22 change, the amount of change in the characteristic frequency of the second-order vibration mode (the amount of change relative to the target frequency) hardly changes. This is because the protrusions 21 and 22 are arranged to overlap on the extension line of the nodal line S10. However, when the length L1 becomes large, unnecessary vibrations due to the protrusions 21 and 22 are generated, so the amount of change in the characteristic frequency of the second-order vibration mode slightly increases.

[0085] Figure 5 (c) is a graph showing the ratio FR of the characteristic frequencies when the lengths L1 of the protrusions 21 and 22 are varied within the range of 0 μm to 500 μm.

[0086] As Figure 5 shown in (c), when the lengths L1 of the protrusions 21 and 22 change, the ratio FR of the characteristic frequencies also changes. As described above, when the characteristic frequency of the second-order vibration mode approaches an integer multiple of the characteristic frequency of the first-order vibration mode, that is, when the ratio FR of the characteristic frequencies approaches an integer, the first-order vibration mode affects the second-order vibration mode, resulting in problems in the operation of the tuning fork type drive element 1.

[0087] Therefore, in the case where the ratio FR changes as Figure 5 shown in (c), it is preferable to keep the ratio FR away from integers such as 4 and 5, and it is preferable to make the ratio FR a value within the vibration suppression range between 4.2 and 4.8. In this case, it is most preferable to make the ratio FR the intermediate value between adjacent integers (about 4.5 in the case of Figure 5 (c)). By making the ratio FR a value within the vibration suppression range, the influence caused by the first-order vibration mode can be suppressed, so that the tuning fork type drive element 1 operates normally.

[0088] When the ratio FR is to be set to a preferred value as described above, first, the length, width, thickness, etc. of the arm portion 20 are adjusted so that the characteristic frequency of the tuning fork type drive element 1 in the second-order vibration mode becomes the target frequency. Then, the lengths L1 of the protrusions 21 and 22 provided on the extension line of the nodal line S10 in the second-order vibration mode are adjusted so that the ratio FR of the tuning fork type drive element 1 becomes a value away from an integer value. At this time, since the protrusions 21 and 22 are arranged to overlap on the extension line of the nodal line S10, even if the lengths L1 of the protrusions 21 and 22 are changed, the characteristic frequency in the second-order vibration mode does not deviate significantly from the target frequency. Therefore, the characteristic frequency in the first-order vibration mode can be adjusted to easily design the tuning fork type drive element 1 so that the ratio FR becomes a value away from an integer value.

[0089] Figure 6 of (a) to Figure 6 (c) are top views schematically showing the structure of the arm portion 20 in the case where the positions x of the protrusions 21 and 22 are changed in the simulation according to Embodiment 1.

[0090] Figure 6 of (a) to Figure 6 (c) respectively show the states where the positions x of the protrusions 21 and 22 are -100 μm, 0 μm, and +220 μm. The position x is the coordinate of the center position of the protrusions 21 and 22 in the x-axis direction when the position where the nodal line S10 intersects the side of the arm portion 20 extending in the X-axis direction is the origin. For convenience, in Figure 6 of (a) to Figure 6 the positions x related to the protrusion 21 on the negative Y-axis side are shown in (c). When the position where the nodal line S10 passes through the center of the arm portion 20 in the Y-axis direction is set as the center C11, in this simulation, the protrusions 21 and 22 provided on one arm portion 20 are configured to be point-symmetrical to each other with respect to the center C11.

[0091] Figure 7 of (a) to Figure 7 (c) are diagrams showing the simulation results when the positions x of the protrusions 21 and 22 are changed in the range of -100 μm to +280 μm in the structure of (a) to Figure 6 of (a) to Figure 6 (c).

[0092] As Figure 7 in (a) and Figure 7As shown in FIG. (b), the variation amount of the characteristic frequency of the first-order vibration mode hardly changes with the change of the position x of the protrusions 21 and 22. On the other hand, the variation amount of the characteristic frequency of the second-order vibration mode (the variation amount relative to the target frequency) becomes larger in the range where the position x of the protrusions 21 and 22 is small. This is because when the position x is small, the area where the protrusions 21 and 22 overlap with the extension line of the nodal line S10 becomes smaller. Therefore, when adjusting the characteristic frequency of the first-order vibration mode so that the characteristic frequency of the second-order vibration mode does not deviate significantly from the target frequency, it is preferable that the protrusions 21 and 22 overlap more with the extension line of the nodal line S10. Specifically, in Figure 7 FIG. (a) and Figure 7 FIG. (b), it is preferable to set the position x to about 220 μm.

[0093] In Figure 7 FIG. (c), it is also preferable to make the ratio FR far from an integer such as 4 or 5, and it is preferable to make the ratio FR a value within the vibration suppression range between 4.2 and 4.8. In this case, it is most preferable to make the ratio FR the intermediate value of adjacent integers (about 4.5 in the case of Figure 7 FIG. (c)). By making the ratio FR a value within the vibration suppression range, the influence caused by the first-order vibration mode can be suppressed, so that the tuning fork type drive element 1 operates normally.

[0094] Also in this case, when the position x of the protrusions 21 and 22 is set to 200 μm or more and the protrusions 21 and 22 are arranged to overlap with the extension line of the nodal line S10, even if the position x of the protrusions 21 and 22 is changed, the characteristic frequency of the second-order vibration mode does not deviate significantly from the target frequency. Therefore, it is possible to easily design the tuning fork type drive element 1 so that the ratio FR becomes a value far from an integer value by adjusting the characteristic frequency in the first-order vibration mode.

[0095] In addition, in the case of only changing the position x as in Figure 6 FIG. (a) to Figure 7 FIG. (c), as shown in Figure 7 FIG. (a) and Figure 7 FIG. (b), the characteristic frequency of the first-order vibration mode does not change significantly, so it is difficult to adjust the characteristic frequency of the first-order vibration mode. Therefore, for example, Figure 4 FIG. (a) to Figure 5 FIG. (c), adjusting the length L1 of the protrusions 21 and 22 can more effectively adjust the characteristic frequency of the first-order vibration mode.

[0096] <Effect of Embodiment 1>

[0097] According to Embodiment 1, the following effects are achieved.

[0098] A pair of arms 20 arranged in the Y-axis direction have protrusions 21 and 22 that overlap on the extension line of the nodal line S10 generated when vibrating in the second-order vibration mode.

[0099] According to this structure, the characteristic frequency of the first-order vibration mode can be changed by the protrusions 21 and 22 as mass portions, and the mass of the protrusions 21 and 22 can be adjusted by the length, etc. of the protrusions 21 and 22 to control the characteristic frequency of the first-order vibration mode. In addition, since the protrusions 21 and 22 as mass portions are formed on the extension line of the nodal line S10, the influence of the mass of the protrusions 21 and 22 on the characteristic frequency of the second-order vibration mode can be suppressed. Therefore, the characteristic frequency in the first-order vibration mode can be easily adjusted to a frequency that does not easily affect the second-order vibration mode without making the characteristic frequency in the second-order vibration mode deviate greatly from the target frequency.

[0100] The protrusions 21 and 22 are formed integrally with the arms 20.

[0101] According to this structure, the protrusions 21 and 22 and the arms 20 can be formed simultaneously through the same manufacturing process, and the protrusions 21 and 22 can be easily formed on the arms 20.

[0102] The protrusions 21 and 22 are respectively provided on both the inner side surface of the arm 20 on the side closer to the connecting portion 32 and the outer side surface of the arm 20 on the side opposite to the inner side surface on the side closer to the connecting portion 32.

[0103] According to this structure, the characteristic frequency of the first-order vibration mode can be appropriately adjusted while adjusting the length and width of each of the protrusions 21 and 22 according to the respective constraints on the inner and outer sides of the arm 20.

[0104] The drive unit 50 has a piezoelectric film as a drive source.

[0105] According to this structure, the arm 20 can be driven smoothly.

[0106] The first drive unit 1a and the second drive unit 1b each having a connecting portion 32, a pair of arms 20, a support portion 31, and a drive unit 50 are arranged facing each other in opposite directions with the movable portion 40 sandwiched therebetween, and the connecting portions 32 of the first drive unit 1a and the second drive unit 1b are connected to the movable portion 40.

[0107] According to this structure, by supporting and driving the movable portion 40 by each drive unit, the movable portion 40 can be stably driven with a larger torque.

[0108] As Figure 1 shown, the optical deflection element 2 includes a tuning fork type drive element 1 and a reflecting surface 41 disposed on the movable portion 40.

[0109] According to this structure, since the tuning fork type driving element 1 with the above structure is provided in the light deflection element 2, the reflecting surface 41 can vibrate smoothly and stably in the second-order vibration mode. Therefore, the light incident on the reflecting surface 41 can be stably deflected as the movable part 40 vibrates.

[0110] As Figure 1 shown, the protrusions 21 facing each other with the rotation axis R10 in between are symmetrically formed with respect to the rotation axis R10, and the protrusions 22 facing each other with the rotation axis R10 in between are symmetrically formed with respect to the rotation axis R10. Thus, in the first driving unit 1a and the second driving unit 1b, the weight balance of the structure on the positive Y-axis side and the structure on the negative Y-axis side can be made equal. Therefore, it is possible to avoid the non-intended influence of the protrusions 21 and 22 on the rotation of the tuning fork type driving element 1.

[0111] <Embodiment 2>

[0112] In Embodiment 1, the protrusions 21 and 22 extending perpendicularly (in the Y-axis direction) to the arm portion 20 are arranged to overlap on the extension line of the nodal line S10. However, in Embodiment 2, the protrusions 21 and 22 are arranged along the extension line of the nodal line S10.

[0113] Figure 8 is a top view schematically showing the structures of the tuning fork type driving element 1 and the light deflection element 2 according to Embodiment 2.

[0114] The tuning fork type driving element 1 and the light deflection element 2 of Embodiment 2 differ only in the formation direction of the protrusions 21 and 22 from Figure 1 that shown in Embodiment 1. In Embodiment 2, the protrusions 21 and 22 are formed along the extension line in the direction of the nodal line S10.

[0115] Next, with reference to Fig. 9 from (a) to Fig.15 from (c), an example of adjusting the structures of the protrusions 21 and 22 to suppress the influence of the first-order vibration mode in Embodiment 2 will be described. The inventors obtained the ratio FR of the characteristic frequency of the second-order vibration mode to the characteristic frequency of the first-order vibration mode by simulating and changing the lengths and widths of the protrusions 21 and 22.

[0116] The simulated tuning fork type driving element 1 of Embodiment 2 shown below, for example, Fig. 9 as shown in (b) of

[0117] Fig. 9 from (a) to Fig. 9(c) is a top view schematically showing the structure of the arm portion 20 when the lengths L1 of the protrusions 21 and 22 are changed in the simulation of Embodiment 2. In Fig. 9 (a), for comparison, the same structure as the comparative example shown in Figure 3 (a) is shown.

[0118] Fig. 9 (a) to Fig. 9 (c) respectively show the states where the lengths L1 of the protrusions 21 and 22 are 0 μm, 500 μm, and 700 μm. The length L1 is the length of the protrusions 21 and 22 protruding along the extension line of the nodal line S10 from the arm portion 20. In this simulation, the length of the protrusion 21 and the length of the protrusion 22 are both L1.

[0119] Fig.10 (a) to Fig.10 (c) are diagrams showing the simulation results when the lengths L1 of the protrusions 21 and 22 are changed in the range of 0 μm to 700 μm under the structure of Fig. 9 (a) to Fig. 9 (c).

[0120] As Fig.10 (a) and Fig.10 (b) show, the amount of change in the characteristic frequency of the first-order vibration mode changes significantly according to the change in the lengths L1 of the protrusions 21 and 22. On the other hand, even if the lengths L1 of the protrusions 21 and 22 change, the amount of change in the characteristic frequency of the second-order vibration mode (the amount of change relative to the target frequency) hardly changes. The amount of change in the characteristic frequency of the second-order vibration mode in this case is smaller than that in Figure 5 (b). This is because the protrusions 21 and 22 are arranged along the extension line of the nodal line S10.

[0121] As Fig.10 (c) shows, when the lengths L1 of the protrusions 21 and 22 change, the ratio FR of the characteristic frequencies also changes. In Fig.10 (c), it is also preferable to make the ratio FR away from integers such as 4 and 5, and it is preferable to make the ratio FR a value within the vibration suppression range between 4.2 and 4.8. In this case, it is most preferable to make the ratio FR the intermediate value of adjacent integers (about 4.5 in the case of Fig.10 (c)). By making the ratio FR a value within the vibration suppression range, the influence caused by the first-order vibration mode can be suppressed, so that the tuning fork type drive element 1 can operate normally.

[0122] Also in this case, even if the lengths L1 of the protrusions 21 and 22 are changed, the characteristic frequency of the second-order vibration mode does not deviate significantly from the target frequency. Therefore, it is possible to easily design the tuning fork type drive element 1 so that the ratio FR becomes a value far from an integer value by adjusting the characteristic frequency in the first-order vibration mode. In addition, compared with the case of (b) of Figure 5 the amount of change in the characteristic frequency of the second-order vibration mode is smaller, so it is possible to further suppress the deviation of the characteristic frequency of the second-order vibration mode from the target frequency when the characteristic frequency of the first-order vibration mode is adjusted.

[0123] Fig.11 (a) to Fig.11 (c) of is a top view schematically showing the structure of the arm portion 20 in the case where the masses of the protrusions 21 and 22 are kept constant and the lengths L1 and widths D1 of the protrusions 21 and 22 are changed in the simulation related to Embodiment 2.

[0124] Fig.11 (a) to Fig.11 (c) of respectively show the states where the sets of the length L1 and width D1 of the protrusions 21 and 22 are 667 μm and 150 μm, 500 μm and 200 μm, and 286 μm and 350 μm. The width D1 is the width of the protrusions 21 and 22 in the direction perpendicular to the direction of the length L1. In this simulation, the areas of the protrusions 21 and 22 are substantially the same as each other.

[0125] Fig.12 (a) to Fig.12 (c) of is a graph showing the simulation results when the width D1 of the protrusions 21 and 22 is changed in the range of 150 μm to 350 μm in the structure of (a) to Fig.11 (a) to Fig.11 (c) of.

[0126] As shown in Fig.12 (a) of and Fig.12 (b) of, even if the width D1 of the protrusions 21 and 22 changes, the amounts of change in the characteristic frequency of the first-order vibration mode and the second-order characteristic frequency do not change significantly. However, when the width D1 becomes larger, the ends in the width direction of the protrusions 21 and 22 deviate from the extension line of the nodal line S10, so the characteristic frequency of the second-order vibration mode changes slightly. Therefore, it is more preferable that the width D1 of the protrusions 21 and 22 is small.

[0127] As shown in Fig.12 (c) of, in this example, the ratio FR of the characteristic frequencies is constant at about 4.5 regardless of the width D1, and the ratio FR becomes a value within the vibration suppression range. Therefore, no matter which value in the range of 150 μm to 350 μm the width D1 is set to, the influence caused by the first-order vibration mode can be suppressed.

[0128] According to this simulation, as described above, even when the width D1 is changed under the condition of constant area, the ratio FR hardly changes. Therefore, it can be said that the shapes of the protrusions 21 and 22 can be changed as needed. Thus, for example, when designing the arm portion 20, as shown in (a) to (c) of Fig. 9 , after adjusting the lengths of the protrusions 21 and 22 to set the characteristic frequency of the first-order vibration mode that is not easily affected by the second-order vibration mode, the areas of the protrusions 21 and 22 are made constant, so that the length L1 and the width D1 can be freely changed. Fig.10 (a) to (c) of

[0129] Fig.13 are top views schematically showing the structure of the arm portion 20 when the sum of the lengths of the protrusions 21 and 22 provided on one arm portion 20 is constant and the lengths of the protrusions 21 and 22 are changed in the simulation related to Embodiment 2. Fig.13 (a) to (c) of

[0130] Fig.13 respectively show the states where the set of the length L11 of the protrusion 21 and the length L12 of the protrusion 22 are 0 μm and 1000 μm, 500 μm and 500 μm, and 1000 μm and 0 μm. In this simulation, the sum of the length L11 of the protrusion 21 and the length L12 of the protrusion 22 provided on one arm portion 20 is the same. Fig.13

[0131] As shown in (a) of , when only the outer protrusion 22 is formed, compared with the case where only the inner protrusion 21 is formed, the mass of the protrusion 22 is located closer to the antinode of the first-order vibration mode (near the front end of the arm portion 20). Thus, the characteristic frequency of the first-order vibration mode can be smoothly changed by the outer protrusion 22 that is smaller than the inner protrusion 21. In addition, as shown in (c) of Fig.13 , when only the inner protrusion 21 is formed, the protrusion does not protrude outside the pair of arm portions 20. Thus, the width of the opening 11 (refer to Fig.13 Figure 8 ) of the fixing portion 10 in the Y-axis direction can be reduced, and thus the outer width of the fixing portion 10 can be reduced. Therefore, the outer width of the tuning fork type driving element 1 can be reduced. Figure 8

[0132] Fig.14 (a) to (c) of Fig.14 are respectively diagrams showing the simulation results of the displacement amount in the Z-axis direction when the structure of (a) to (c) of Fig.13 vibrates in the second-order vibration mode. The black portions of the arm portion 20 indicate that the displacement amount in the Z-axis direction with respect to the neutral position is small. Fig.13

[0133] Regardless Fig.14 In any of the cases (a) to Fig.14 (c) of [[ID=]], the extending directions of the protrusions 21 and 22 are substantially the same as the extending direction of the portion with a small displacement amount (nodal line S10), and it can be known that the protrusions 21 and 22 do not easily affect the second-order vibration mode.

[0134] Fig.15 In (a) to Fig.15 (c) of [[ID=]] shows the simulation results when the ratio of the length L11 of the protrusion 21 to the sum of the lengths of the protrusions 21 and 22 (L11 + L12) varies within the range of 0% to 100% under the structure of (a) to Fig.13 In (a) to Fig.13 (c) of [[ID=]].

[0135] As shown in Fig.15 (a) and Fig.15 (b) of [[ID=]], the variation amount of the characteristic frequency of the first-order vibration mode changes significantly according to the ratio of the length L11 of the protrusion 21. On the other hand, even if the ratio of the length L11 of the protrusion 21 changes, the variation amount of the characteristic frequency of the second-order vibration mode (the variation amount relative to the target frequency) hardly changes. This is because the protrusions 21 and 22 are arranged along the extension line of the nodal line S10.

[0136] In Fig.15 (c) of [[ID=]], it is also preferable to make the ratio FR away from integers such as 4 and 5, and it is preferable to make the ratio FR a value within the vibration suppression range between 4.2 and 4.8. In this case, it is most preferable to make the ratio FR the intermediate value between adjacent integers (about 4.5 in the case of Fig.15 (c) of [[ID=]]). By making the ratio FR a value within the vibration suppression range, the influence caused by the first-order vibration mode can be suppressed, so that the tuning fork type drive element 1 operates normally.

[0137] In addition, when the protrusions 21 and 22 are too long, sometimes the vibration mode of the protrusions 21 and 22 themselves is generated, and thus the characteristic frequency of the second-order vibration mode changes. In this case, it is preferable to suppress the change in the characteristic frequency of the second-order vibration mode in the protrusions 21 and 22 by adjusting the length, width, and thickness of the protrusions 21 and 22, etc.

[0138] Next, with reference to Fig.16 (a) to Fig.19 (c) of [[ID=]], the case where it is more preferable not to fix the front ends of the protrusions 21 and 22 will be described. The inventors obtained the displacement amount in the Z-axis direction of the arm portion 20 by changing the positions of the protrusions 21 and 22 in the X-axis direction through the simulation of the second embodiment and the comparative example.

[0139] Fig.16in (a) to Fig.16 In (c), it is a top view showing the structure of the arm portion 20 in the case where the positions of the protrusions 21 and 22 are shifted in the X-axis direction from the positions on the extension line of the nodal line S10, which is involved in the simulation of Embodiment 2.

[0140] In Fig.16 in (b), the protrusions 21 and 22 extend along the extension line of the nodal line S10. In Fig.16 in (a) and Fig.16 in (c), the protrusions 21 and 22 are respectively moved 10 μm in the negative X-axis direction and the positive X-axis direction with respect to the state of Fig.16 in (b). In the simulation of Embodiment 2, the tips of the protrusions 21 and 22 are not fixed.

[0141] Fig.17 in (a) to Fig.17 in (c) are respectively diagrams showing the simulation results of the displacement amount in the Z-axis direction when the structures of Fig.16 in (a) to Fig.16 in (c) vibrate in the second-order vibration mode. The black portions of the arm portion 20 indicate that the displacement amount in the Z-axis direction from the neutral position is small.

[0142] In Fig.17 in (a) to Fig.17 in (c), the characteristic frequencies of the second-order vibration mode are 67340.8 Hz, 67339.7 Hz, and 67335.1 Hz respectively. That is, in Fig.17 in (a) and Fig.17 in (c), compared with Fig.17 in (b), the deviations of the characteristic frequencies of the second-order vibration mode are respectively maintained at about +1 Hz and -5 Hz. From this, it can be known that even if the protrusions 21 and 22 are unintentionally deviated by about 10 μm in the X-axis direction from the extension line of the nodal line S10, the characteristic frequency of the second-order vibration mode hardly changes. Therefore, according to the structure of Embodiment 2 of Fig.16 in (a) to Fig.16 in (c), for the position deviation of the protrusions 21 and 22, the characteristic frequency of the second-order vibration mode does not change significantly, so the manufacturing deviation of the tuning fork type driving element 1 can be suppressed.

[0143] In addition, when the arm portion 20 vibrates in the second-order vibration mode without forming the protrusions 21 and 22, the characteristic frequency of the second-order vibration mode becomes 67366.2 Hz. From this, it can be known that Fig.17 in (a) to Fig.17 the characteristic frequency of the second-order vibration mode in (c) hardly changes with respect to the characteristic frequency of the second-order vibration mode in the case where there are no protrusions 21 and 22, so the protrusions 21 and 22 hardly affect the second-order vibration mode.

[0144] In addition, regardless of Fig.17 in (a) to Fig.17 in (c) of, the extending directions of the protrusions 21 and 22 are substantially the same as the extending direction of the portion with a small displacement amount (nodal line S10). From this, it can also be known that the protrusions 21 and 22 do not easily affect the second-order vibration mode.

[0145] Fig.18 in (a) to Fig.18 (a) to (c) of show a top view of the structure of the arm portion 20 in the case where the positions of the protrusions 21 and 22 are offset in the X-axis direction from the positions on the extension line of the nodal line S10 in the simulation of the comparative example schematically.

[0146] In Fig.18 in (a) to Fig.18 in (c), the positions of the protrusions 21 and 22 are the same as those in Fig.16 in (a) to Fig.16 in (c) respectively. However, in the simulation of the comparative example, the front end of the protrusion 22 is fixed to a part 10a of the fixing portion 10.

[0147] Fig.19 in (a) to Fig.19 in (c) respectively show diagrams of the simulation results of the displacement amount in the Z-axis direction when the structure in Fig.18 in (a) to Fig.18 in (c) vibrates in the second-order vibration mode. The black portion of the arm portion 20 indicates that the displacement amount in the Z-axis direction from the neutral position is small.

[0148] In Fig.19 in (a) to Fig.19 in (c), the characteristic frequencies of the second-order vibration mode are 82815.1 Hz, 83119.3 Hz, and 83500.1 Hz respectively. That is, in Fig.19 in (a) and Fig.19 in (c), compared with Fig.19 in (b), the deviations of the characteristic frequencies of the second-order vibration mode become larger by about +384 Hz and -300 Hz respectively. From this, it can be known that in the comparative example, when the protrusions 21 and 22 are unintentionally deviated by about 10 μm in the X-axis direction from the extension line of the nodal line S10, the characteristic frequency of the second-order vibration mode changes significantly. Therefore, in the case where the front end of the protrusion 22 is fixed as in Fig.18 in (a) to Fig.18 in (c), for the position offset of the protrusions 21 and 22, the characteristic frequency of the second-order vibration mode changes significantly, resulting in a larger manufacturing deviation of the tuning fork type driving element 1.

[0149] In addition, regardless of Fig.19 In any of (a) to Fig.19 in (c), the extending directions of the protrusions 21 and 22 are not consistent with the extending direction of the portion with a small displacement amount (nodal line S10), and it can be seen that the protrusions 21 and 22 affect the second-order vibration mode.

[0150] <Effects of Embodiment 2>

[0151] According to Embodiment 2, the following effects are achieved.

[0152] As Figure 8 shown, the protrusions 21 and 22 are configured to vibrate together with the arm portion 20 without being restricted by other elements (for example, the fixing portion 10) other than the arm portion 20. According to this structure, the protrusions 21 and 22 can move freely together with the arm portion 20. Therefore, as described with reference to Fig.16 in (a) to Fig.19 in (c), the protrusions 21 and 22 are less likely to affect the characteristic frequency of the second-order vibration mode. Therefore, the characteristic frequency of the second-order vibration mode can be appropriately set to the target frequency.

[0153] The protrusions 21 and 22 extend along the extension line of the nodal line S10.

[0154] According to this structure, compared with the case where the protrusions 21 and 22 do not extend parallel to the nodal line S10, the change in the second-order characteristic frequency caused by the protrusions 21 and 22 can be suppressed. Therefore, the characteristic frequency of the second-order vibration mode can be set more appropriately to the target frequency.

[0155] As Fig.13 shown in (c), the protrusion 21 may be provided only on the inner side surface of the arm portion 20 on the side closer to the connecting portion 32.

[0156] According to this structure, since no protrusion is formed on the outside of the arm portion 20, the outer shape width of the tuning fork type driving element 1 can be reduced.

[0157] <Modification Examples of Protrusions>

[0158] The protrusions 21 and 22 may be arranged so as to overlap on the extension line of the nodal line S10 in a top view, and are not limited to the shapes shown in Embodiments 1 and 2. The protrusions 21 and 22 may be configured, for example, as shown in Fig. 20 in (a) to Fig. 22 in (b). In addition, also in the following modification examples, the protrusions formed on the pair of arm portions 20 arranged in the Y-axis direction are configured to be line-symmetrical with respect to the rotation axis R10.

[0159] As Fig. 20 shown in (a), only the inner protrusion 21 may be formed on the arm portion 20. Additionally, Fig. 20The protrusion 21 in (a) can also be formed along the extension line of the nodal line S10 in the same manner as the protrusion 21 in Embodiment 2.

[0160] As Fig. 20 shown in (b), only the outer protrusion 22 can be formed on the arm portion 20. Additionally, Fig. 20 the protrusion 22 in (b) can also be formed along the extension line of the nodal line S10 in the same manner as the protrusion 22 in Embodiment 2.

[0161] As Fig. 20 shown in (c), the inner protrusion 21 can also be formed to have a wider width as it is farther from the connected arm portion 20. Additionally, the outer protrusion 22 can also be formed to have a wider width as it is farther from the connected arm portion 20. In this way, when the protrusions 21 and 22 are configured to have different widths at the root and the tip, when forming the protrusions 21 and 22 with the mass required to adjust the characteristic frequency of the first-order vibration mode, by making the widths of the roots and the tips of the protrusions 21 and 22 different, it is possible to more easily adjust the lengths of the protrusions 21 and 22 to the target lengths, or to form the protrusions 21 and 22 into shapes that can suppress the influence on the characteristic frequency of the second-order vibration mode, etc., and the shapes of the protrusions 21 and 22 can be adjusted to meet various requirements.

[0162] As Fig.21 shown in (a), the protrusions 21 and 22 can also be formed to have a narrower width as they are farther from the connected arm portion 20. In this case, since the tips of the protrusions 21 and 22 are tapered, the characteristic frequencies of the protrusions 21 and 22 become higher, and unnecessary vibrations based on the protrusions 21 and 22 can be suppressed. Additionally, in this case as well, the protrusions 21 and 22 are configured to have different widths at the root and the tip, so the same effects as those described in reference to Fig. 20 (c) are achieved. Furthermore, in Fig.21 (a), either one of the protrusions 21 and 22 can be omitted.

[0163] As Fig.21 shown in (b), the lengths of the protrusions 21 and 22 formed on one arm portion 20 can also be different from each other. The length of the protrusion 21 can be either longer or shorter than the length of the protrusion 22.

[0164] As Fig.21 shown in (c), the protrusion 21 can also be made of a material different from that of the arm portion 20. Additionally, the protrusion 22 can also be made of a material different from that of the arm portion 20. When the protrusions 21 and 22 are made of materials different from that of the arm portion 20, the protrusions 21 and 22 are made of resin, for example.

[0165] It can also be as Fig. 22As shown in (a) thereof, the roots of the protrusions 21 and 22 extend in a direction (Y-axis direction) perpendicular to the arm portion 20, and the front ends of the protrusions 21 and 22 extend along the extension line of the nodal line S10.

[0166] It is also possible to, as Fig. 22 shown in (b) thereof, the roots of the protrusions 21 and 22 extend along the extension line of the nodal line S10, and the front ends of the protrusions 21 and 22 extend in the X-axis direction. Additionally, in Fig. 22 the (b) thereof, the front ends of the protrusions 21 and 22 may also extend in the Y-axis direction.

[0167] In Fig. 20 the modification examples from (a) to Fig. 22 the (b) thereof, in all cases, the protrusions 21 and 22 overlap on the extension line of the nodal line S10. Thus, similar to Embodiments 1 and 2, the shape of the protrusions 21 and 22 can be adjusted, and thus it is easy to adjust the characteristic frequency of the first-order vibration mode to a frequency that does not easily affect the second-order vibration mode.

[0168] In addition to this, it is also possible to, as Fig.23 shown in (a) thereof, arrange the protrusion 23 to overlap with the nodal line S10 in a top view. In this case, for example, the protrusion 23 is formed at a position corresponding to the position of the nodal line S10 on the lower surface of the arm portion 20. The protrusion 23 may also be integrally formed with the arm portion 20 from the same material (silicon) as the arm portion 20, or may be formed from a material different from the arm portion 20 (for example, a resin material).

[0169] In Fig.23 the example of (a) thereof, the protrusion 23 is arranged to protrude downward from the lower surface of the arm portion 20, but it is also possible to form the protrusion 23 at a position overlapping with the nodal line S10 on the upper surface of the arm portion 20, that is, on the upper surface of the drive portion 50, so as to protrude upward. In this case, the protrusion 23 is formed, for example, by stacking a resin material or the like on the upper surface of the drive portion 50.

[0170] Furthermore, when configuring the structure for adjusting the mass at a position overlapping with the nodal line S10 in this way, it is also possible to, as Fig.23 shown in (b) thereof, arrange a recess 24 at a position overlapping with the nodal line S10 on the lower surface of the arm portion 20 instead of the protrusion 23. The recess 24 may have a shape with two walls parallel to the Z-axis and a certain depth, or may have a shape with the position of the nodal line S10 as the bottommost part and gradually becoming shallower as it moves away from the nodal line S1. In Fig.23 the example of (a) thereof, in a top view, the width of the recess S10 in the X-axis direction is constant, and the nodal line S10 is located in the middle of this width.

[0171] The concave portion 24 may also be provided at a position overlapping the nodal line S10 on the upper surface of the arm portion 20. However, since the drive portion 50 is disposed on the upper surface of the arm portion 20, in order to provide the concave portion 24, a part of the drive portion 50 needs to be removed. Therefore, in order to maintain the drive efficiency of the drive portion 50, it is preferable to provide the concave portion at a position corresponding to the nodal line S10 on the lower surface of the arm portion 20.

[0172] In addition, regarding the protrusion 23 and the concave portion 24, it is not necessary to dispose the protrusion 23 and the concave portion 24 over the entire length of the nodal line S10, and the protrusion 23 and the concave portion 24 may be disposed within a partial range of the nodal line S10. Further, the protrusion 23 or the concave portion 24 may be disposed together with the above-described protrusions 21 and 22.

[0173] <Modification Example of Higher-Order Vibration Mode>

[0174] In Embodiments 1 and 2, the arm portion 20 is driven in the second-order vibration mode, but the arm portion 20 may be driven in a higher-order vibration mode higher than the second order.

[0175] The inventors simulated to form four first drive units 1a as shown in (a) of Fig.24 (a) of Fig.25 (a) of Fig.26 (a) of Fig. 27 and obtained the displacement amounts in the Z-axis direction when the arm portion 20 was driven in a higher-order vibration mode higher than the first-order vibration mode under each structure.

[0176] Fig.24 (a) to Fig.24 (c) of Fig.24 show the simulation results of the displacement amounts in the Z-axis direction when the arm portion 20 was driven in the second-order vibration mode, the third-order vibration mode, and the fourth-order vibration mode, respectively, in the first drive unit 1a having the dimensions shown in (a) of

[0177] In the first drive unit 1a in this case, the length and width of the second portion 20b of the arm portion 20 were set to 4000 μm and 500 μm, respectively, and the thickness of the arm portion 20 in the Z-axis direction was set to 150 μm. The first portion 20a of the arm portion 20 was formed to extend in the Y-axis direction. In this case, the connecting portion 32 was omitted from the first drive unit 1a. In Fig.24 (a) to Fig.24 (c), the black portions of the arm portion 20 indicate that the displacement amounts in the Z-axis direction from the neutral position are small.

[0178] As shown in (a) of Fig.24 , when the arm portion 20 was driven in the second-order vibration mode, as in Figure 1 and Figure 8As also shown, a nodal line S10 is formed in a direction inclined with respect to a second part 20b. In this case, as shown in Embodiments 1 and 2 and the modification example, the protrusions 21 and 22 are arranged to overlap on the extension line of the nodal line S10 indicated by a dashed line in a plan view. By adjusting the length, width, thickness, etc. of the protrusions 21 and 22, it is possible to easily adjust the characteristic frequency in the first-order vibration mode to a frequency that does not easily affect the second-order vibration mode without causing a large difference between the characteristic frequency in the second-order vibration mode and the target frequency.

[0179] As Fig.24 As shown in (b) of Fig.24 , when the arm part 20 is driven in the third-order vibration mode, two nodal lines S10 are formed in a second part 20b. Also in this case, the protrusions 21 and 22 are arranged to overlap on the extension line of the nodal line S10 indicated by a dashed line in a plan view. By adjusting the length, width, thickness, etc. of the protrusions 21 and 22, it is possible to easily adjust the characteristic frequency in the lower-order vibration mode to a frequency that does not easily affect the third-order vibration mode without causing a large difference between the characteristic frequency in the third-order vibration mode and the target frequency.

[0180] Specifically, the ratio FR1 of the characteristic frequency of the third-order vibration mode to the characteristic frequency of the first-order vibration mode and the ratio FR2 of the characteristic frequency of the third-order vibration mode to the characteristic frequency of the second-order vibration mode are each set to a value far from an integer. In this case, it is particularly preferable to first set the ratio FR1 to a value far from an integer.

[0181] As Fig.24 As shown in (c) of Fig.24 , when the arm part 20 is driven in the fourth-order vibration mode, three nodal lines S10 are formed in a second part 20b. Also in this case, the protrusions 21 and 22 are arranged to overlap on the extension line of the nodal line S10 indicated by a dashed line in a plan view. By adjusting the length, width, thickness, etc. of the protrusions 21 and 22, it is possible to easily adjust the characteristic frequency in the lower-order vibration mode to a frequency that does not easily affect the fourth-order vibration mode without causing a large difference between the characteristic frequency in the fourth-order vibration mode and the target frequency.

[0182] Specifically, the ratio FR1 of the characteristic frequency of the fourth-order vibration mode to the characteristic frequency of the first-order vibration mode, the ratio FR2 of the characteristic frequency of the fourth-order vibration mode to the characteristic frequency of the second-order vibration mode, and the ratio FR3 of the characteristic frequency of the fourth-order vibration mode to the characteristic frequency of the third-order vibration mode are each set to a value far from an integer. Also in this case, it is particularly preferable to first set the ratio FR1 to a value far from an integer.

[0183] Fig.25 (a) to Fig.25 (c) of Fig.25 show Fig.25 1 and 2 are simulation results of the displacement in the Z-axis direction when the arm 20 is driven in the second-order vibration mode, the third-order vibration mode, and the fourth-order vibration mode in the first driving unit 1 a having the size shown in (a).

[0184] In the first driving unit 1a, the length and width of the second portion 20b of the arm 20 are 4000 μm and 500 μm respectively, and the thickness of the arm 20 in the Z-axis direction is 300 μm. The first portion 20a of the arm 20 is formed to extend in the Y-axis direction.

[0185] exist Fig.25 (a)~ Fig.25 In (c), although Fig.24 (a)~ Fig.24 The direction and position of the nodal line S10 are slightly different from those of (c), but Fig.24 (a)~ Fig.24 In this case as well, the protrusions 21 and 22 can easily adjust the characteristic frequency in the low-order vibration mode to a frequency that is less likely to affect the high-order vibration mode without greatly differing the characteristic frequency in the high-order vibration mode from the target frequency.

[0186] Fig.26 (a)~ Fig.26 (c) is shown in Fig.26 1 and 2 are simulation results of the displacement in the Z-axis direction when the arm 20 is driven in the second-order vibration mode, the third-order vibration mode, and the fourth-order vibration mode in the first driving unit 1 a having the size shown in (a).

[0187] In this case, the dimensions of the first drive unit 1a are set to Fig.24 The same is true for (a). In addition, the first portion 20a of the arm portion 20 is formed to extend obliquely with respect to the Y-axis direction.

[0188] exist Fig.26 (a)~ Fig.26 In (c), although Fig.24 (a)~ Fig.25 (c) is slightly different from the direction and position of the nodal line S10, but Fig.24 (a)~ Fig.25 In this case as well, the protrusions 21 and 22 can easily adjust the characteristic frequency in the low-order vibration mode to a frequency that is less likely to affect the high-order vibration mode without greatly differing the characteristic frequency in the high-order vibration mode from the target frequency.

[0189] Fig. 27of (a) and Fig. 27 of (b) shows the Fig. 27 simulation results of the displacement amounts in the Z-axis direction when the arm portion 20 is driven in the second-order vibration mode and the third-order vibration mode, respectively, in the first driving unit 1a having the dimensions shown in (a).

[0190] In the first driving unit 1a in this case, the length and width of the second portion 20b of the arm portion 20 are 4000 μm and 1000 μm, respectively, and the thickness of the arm portion 20 in the Z-axis direction is set to 150 μm. The first portion 20a of the arm portion 20 is formed to extend in the Y-axis direction.

[0191] In Fig. 27 of (a) as well, although the direction and position of the nodal line S10 are slightly different from those in Fig.24 of (a), Fig.25 of (a), Fig.26 of (a), the nodal line S10 is formed in the same manner. Also in this case, by the protrusions 21 and 22, it is possible to easily adjust the characteristic frequency in the first-order vibration mode to a frequency that does not greatly affect the second-order vibration mode without making the characteristic frequency in the second-order vibration mode differ greatly from the target frequency.

[0192] In Fig. 27 of (b), a substantially U-shaped nodal line S10 is formed along a pair of arm portions 20 and support portions 31 arranged in the Y-axis direction. In this case, the protrusions are arranged so as to overlap on the extension line of the nodal line S10 represented by a dotted line when viewed from above, from the end portion on the positive X-axis side of the arm portion 20. By adjusting the length, width, thickness, etc. of the protrusions, it is possible to easily adjust the characteristic frequency in the lower-order vibration mode to a frequency that does not greatly affect the third-order vibration mode without making the characteristic frequency in the third-order vibration mode differ greatly from the target frequency.

[0193] As Fig.24 of (b) and Fig.24 of (c), Fig.25 of (b) and Fig.25 of (c), Fig.26 of (b) and Fig.26 of (c), and Fig. 27 as shown in of (b), even when the arm portion 20 is driven in a higher-order vibration mode higher than the second-order, it is preferable to arrange the protrusions arranged on the arm portion 20 to overlap on the nodal line S10 or the extension line of the nodal line S10. More specifically, it is preferable to extend along the extension line of the nodal line S10. In addition, the shape of the protrusions arranged on the arm portion 20 is preferably configured to vibrate together with the arm portion 20 without being restricted by other elements (for example, the fixing portion 10) other than the arm portion 20.

[0194] <Other modification examples>

[0195] In the above-described embodiments and modification examples, as Figure 1 and Figure 8 shown, the first drive unit 1a and the second drive unit 1b are arranged so as to sandwich the movable part 40 therebetween, but either one of the two drive units may be omitted. For example, as Fig.28 shown, compared with the embodiment 1 shown in Figure 1 , the second drive unit 1b may be omitted, and the movable part 40 may be supported by the connecting part 32 of the first drive unit 1a. Further, in the tuning fork type drive element 1 of Figure 8 , the second drive unit 1b may also be omitted.

[0196] In addition, as Fig.29 shown, the movable part 40 and the connecting part 32 may be omitted from the tuning fork type drive element 1. In this case, in the structure shown in Fig.29 , projections 21 and 22 are provided on a pair of arm parts 20, and the projections 21 and 22 are located on the extension line of the nodal line S10 generated on the arm parts 20 when the pair of arm parts 20 vibrate in a higher-order vibration mode higher than the first-order vibration mode. The projections 21 and 22 can be configured in the same manner as in the above-described embodiments and modification examples.

[0197] In the structure of Fig.29 , instead of the projections 21 and 22, or together with the projections 21 and 22, a projection 23 overlapping the nodal line S1 as shown in Fig.23 of (a) may be provided, or a recess 24 overlapping the nodal line S1 as shown in Fig.23 of (b) may be provided. The projection 23 and the recess 24 can be formed by the same method as in Fig.23 of (a) and Fig.23 of (b). In addition, the projection 23 and the recess 24 may be formed on the upper surface side of the arm part 20 in the same manner as in Fig.23 of (a) and Fig.23 of (b).

[0198] Such a tuning fork type drive element 1 can be used as an angular velocity sensor, for example. Based on the signal output from the drive unit 50, the angular velocity of the arm part 20 rotating about the rotation axis R10 is detected.

[0199] In addition, the embodiments of the present invention can be appropriately modified within the scope of the technical idea shown in the claims.

[0200] (Supplementary note)

[0201] Based on the description of the above embodiments, the following technology is disclosed.

[0202] (Technology 1)

[0203] A tuning fork type driving element, characterized by comprising:

[0204] A movable part that can rotate around a rotation axis;

[0205] A connecting part that extends along the rotation axis from the movable part;

[0206] A pair of arm parts arranged so as to sandwich the connecting part therebetween;

[0207] A support part that connects the connecting part and the pair of arm parts to a fixed part; and

[0208] A driving part that is arranged on the arm part,

[0209] wherein the pair of arm parts have protrusions that overlap on a nodal line or an extension of the nodal line generated when vibrating in a higher-order vibration mode higher than the first-order vibration mode.

[0210] According to this technique, by means of the protrusions as mass parts, the characteristic frequency of the lower-order vibration mode can be changed, and the characteristic frequency of the lower-order vibration mode can be controlled by adjusting the mass of the protrusions such as the length of the protrusions. In addition, since the protrusions as mass parts are formed on the nodal line or an extension of the nodal line, the influence of the mass of the protrusions on the characteristic frequency of the higher-order vibration mode can be suppressed. Therefore, it is possible to easily adjust the characteristic frequency of the lower-order vibration mode lower than this vibration mode to a frequency that does not easily affect the higher-order vibration mode without making the characteristic frequency in the higher-order vibration mode deviate greatly from the target frequency.

[0211] (Technique 2)

[0212] The tuning fork type driving element according to Technique 1, characterized in that

[0213] the protrusions are configured to vibrate together with the arm parts without being restricted by other elements except the arm parts.

[0214] According to this technique, the protrusions can move freely together with the arm parts, so the protrusions are not likely to affect the characteristic frequency of the higher-order vibration mode. Therefore, the characteristic frequency of the higher-order vibration mode can be appropriately set to the target frequency.

[0215] (Technique 3)

[0216] The tuning fork type driving element according to Technique 1 or 2, characterized in that

[0217] the protrusions extend along the extension of the nodal line.

[0218] According to this technique, compared with the case where the protrusion does not extend parallel to the nodal line, the change in the characteristic frequency of higher orders caused by the protrusion can be suppressed. Therefore, the characteristic frequency of the higher-order vibration mode can be set more appropriately to the target frequency.

[0219] (Technique 4)

[0220] The tuning fork type driving element according to any one of Techniques 1 to 3, characterized in that

[0221] The width of the root of the protrusion is different from the width of the front end.

[0222] According to this technique, when forming a protrusion for adjusting the mass required for the characteristic frequency of a lower order, by making the width of the root of the protrusion different from the width of the front end, it is possible to more easily adjust the length of the protrusion to the target length, or to form the protrusion into a shape that can suppress the influence on the characteristic frequency of the higher-order vibration mode, etc., and the shape of the protrusion can be adjusted to a shape that meets each requirement.

[0223] (Technique 5)

[0224] The tuning fork type driving element according to any one of Techniques 1 to 4, characterized in that

[0225] The protrusion is formed integrally with the arm portion.

[0226] According to this technique, the protrusion and the arm portion can be formed simultaneously by the same manufacturing process, and the protrusion can be easily formed on the arm portion.

[0227] (Technique 6)

[0228] The tuning fork type driving element according to any one of Techniques 1 to 5, characterized in that

[0229] The protrusion is provided only on the inner surface of the arm portion on the side closer to the connecting portion.

[0230] According to this technique, since no protrusion is formed on the outside of the arm portion, the outer width of the tuning fork type driving element can be reduced.

[0231] (Technique 7)

[0232] The tuning fork type driving element according to any one of Techniques 1 to 5, characterized in that

[0233] The protrusion is provided on both the inner surface of the arm portion on the side closer to the connecting portion and the outer surface on the side opposite to the inner surface.

[0234] According to this technique, it is possible to appropriately adjust the characteristic frequency of the lower-order vibration mode while adjusting the length and width of each protrusion according to the respective constraints on the inner and outer sides of the arm portion.

[0235] (Technology 8)

[0236] The tuning fork type driving element according to any one of Technologies 1 to 7, wherein:

[0237] The driving portion has a piezoelectric thin film as a driving source.

[0238] According to this technology, the arm portion can be smoothly driven.

[0239] (Technology 9)

[0240] The tuning fork type driving element according to any one of Technologies 1 to 8, wherein:

[0241] Two driving units each having the connecting portion, the pair of arm portions, the supporting portion, and the driving portion are arranged facing each other in opposite directions with the movable portion sandwiched therebetween.

[0242] The connecting portion of each driving unit is connected to the movable portion.

[0243] According to this technology, by supporting and driving the movable portion by each driving unit, the movable portion can be stably driven with a larger torque.

[0244] (Technology 10)

[0245] An optical deflection element, comprising:

[0246] The tuning fork type driving element according to any one of Technologies 1 to 9; and

[0247] A reflecting surface disposed on the movable portion.

[0248] According to this technology, since the optical deflection element includes the tuning fork type driving element having the above structure, the reflecting surface can vibrate smoothly and stably in a high-order vibration mode. Therefore, the light incident on the reflecting surface can be stably deflected as the movable portion vibrates.

[0249] (Technology 11)

[0250] A tuning fork type driving element, comprising:

[0251] A pair of arm portions arranged with a rotation axis sandwiched therebetween;

[0252] A supporting portion connecting the pair of arm portions to a fixed portion; and

[0253] A driving portion disposed on the arm portion,

[0254] Among them, the pair of arms have protrusions or recesses, the protrusions overlapping on the nodal line generated when vibrating in a higher-order vibration mode higher than the first-order vibration mode or on the extension line of the nodal line, and the recess overlapping with the nodal line.

[0255] (Technology 12)

[0256] The tuning fork type driving element according to Technology 11, characterized in that

[0257] The protrusion is configured to vibrate with the arm without being restricted by other elements other than the arm.

[0258] (Technology 13)

[0259] The tuning fork type driving element according to Technology 11, characterized in that

[0260] The protrusion extends along the extension line of the nodal line.

[0261] (Technology 14)

[0262] The tuning fork type driving element according to Technology 11, characterized in that

[0263] The width of the root of the protrusion is different from the width of the front end.

[0264] (Technology 15)

[0265] The tuning fork type driving element according to claim 11, characterized in that

[0266] The protrusion is integrally formed with the arm.

[0267] (Technology 16)

[0268] The tuning fork type driving element according to Technology 16, characterized in that

[0269] The protrusion is provided only on the inner side surface of the arm on the side close to the rotation axis.

[0270] (Technology 17)

[0271] The tuning fork type driving element according to Technology 11, characterized in that

[0272] The protrusion is provided on both the inner side surface of the arm on the side close to the rotation axis and the outer side surface on the side opposite to the inner side surface.

[0273] (Technology 18)

[0274] The tuning fork type driving element according to Technology 11, characterized in that

[0275] The driving part has a piezoelectric film as a driving source.

[0276] According to Technologies 11 to 18, the same effects as those of Technologies 11 to 8 are achieved.

[0277] (Technology 19)

[0278] The tuning fork type driving element according to any one of Technologies 11 to 18 is characterized by further comprising:

[0279] A movable part that can rotate around the rotation axis; and

[0280] A connecting part that extends from the movable part along the rotation axis and is connected to the fixed part.

[0281] (Technology 20)

[0282] The tuning fork type driving element according to Technology 19 is characterized in that

[0283] Two driving units each having the connecting part, the pair of arm parts, the supporting part, and the driving part are arranged facing each other in opposite directions with the movable part sandwiched therebetween,

[0284] The connecting part of each driving unit is connected to the movable part.

[0285] According to this technology, the same effect as that of Technology 9 is achieved.

[0286] (Technology 21)

[0287] An optical deflection element is characterized by comprising:

[0288] The tuning fork type driving element according to Technology 19 or 20; and

[0289] A reflecting surface that is arranged on the movable part.

[0290] According to this technology, the same effect as that of Technology 10 is achieved.

[0291] Explanation of reference numerals

[0292] 1: Tuning fork type driving element; 1a: First driving unit (driving unit); 1b: Second driving unit (driving unit); 2: Optical deflection element; 10: Fixed part; 10a: Part (other element); 20: Arm part; 31: Supporting part; 32: Connecting part; 40: Movable part; 41: Reflecting surface; 50: Driving part; 112: Piezoelectric layer (piezoelectric film); R10: Rotation axis; S10: Node line.

Claims

1. A tuning fork type driving element, characterized in that, Comprising: A movable part that can rotate around a rotation axis; A connecting part that extends along the rotation axis from the movable part; A pair of arm parts arranged so as to sandwich the connecting part therebetween; A support part that connects the connecting part and the pair of arm parts to a fixed part; And A drive part arranged on the arm part, wherein the pair of arm parts have protrusions that overlap on a nodal line or an extension line of the nodal line generated when vibrating in a higher-order vibration mode higher than the first-order vibration mode.

2. The tuning fork type drive element according to claim 1, wherein: The protrusion is configured to vibrate together with the arm part without being restricted by other elements except the arm part.

3. The tuning fork type drive element according to claim 1, wherein: The protrusion extends along the extension line of the nodal line.

4. The tuning fork type drive element according to claim 1, wherein: The width of the root of the protrusion is different from the width of the front end.

5. The tuning fork type drive element according to claim 1, wherein: The protrusion is integrally formed with the arm part.

6. The tuning fork type drive element according to claim 1, wherein: The protrusion is provided only on the inner side surface of the arm part on the side closer to the connecting part.

7. The tuning fork type drive element according to claim 1, wherein: The protrusion is provided on both the inner side surface of the arm part on the side closer to the connecting part and the outer side surface opposite to the inner side surface.

8. The tuning fork type drive element according to claim 1, wherein: The drive part has a piezoelectric thin film as a drive source.

9. The tuning fork type drive element according to claim 1, wherein: Two drive units each having the connecting part, the pair of arm parts, the support part, and the drive part are arranged in opposite directions sandwiching the movable part therebetween, and the connecting part of each drive unit is connected to the movable part.

10. An optical deflection element, characterized in that, Comprising: The tuning fork type drive element according to any one of claims 1 to 9; and A reflecting surface arranged on the movable part.

11. A tuning fork type driving element, characterized in that, Comprising: A pair of arm parts arranged so as to sandwich a rotation axis therebetween; A support part that connects the pair of arm parts to a fixed part; and A drive part arranged on the arm part, wherein the pair of arm parts have protrusions or recesses, the protrusions overlap on a nodal line or an extension line of the nodal line generated when vibrating in a higher-order vibration mode higher than the first-order vibration mode, and the recesses overlap with the nodal line.

12. The tuning fork type drive element according to claim 11, wherein: The protrusion is configured to vibrate together with the arm part without being restricted by other elements except the arm part.

13. The tuning fork type drive element according to claim 11, wherein: The protrusion extends along the extension line of the nodal line.

14. The tuning fork type drive element according to claim 11, wherein: The width of the root of the protrusion is different from the width of the front end.

15. The tuning fork type driving element according to claim 11, wherein: the protrusion is integrally formed with the arm portion.

16. The tuning fork type driving element according to claim 11, wherein: the protrusion is provided only on the inner surface of the arm portion on the side closer to the rotation axis.

17. The tuning fork type driving element according to claim 11, wherein: the protrusion is provided on both the inner surface of the arm portion on the side closer to the rotation axis and the outer surface on the side opposite to the inner surface.

18. The tuning fork type driving element according to claim 11, wherein: the driving portion has a piezoelectric film as a driving source.

19. The tuning fork type driving element according to any one of claims 11 to 18, characterized in that, Further provided with: a movable portion that can rotate around the rotation axis; and a connecting portion that extends along the rotation axis from the movable portion and is connected to the fixed portion.

20. An optical deflection element, characterized in that, Provided with: the tuning fork type driving element according to claim 19; and a reflecting surface that is disposed on the movable portion.

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