Vibration module and light deflector

Abstract

This vibration module comprises a drive element and a support substrate that supports the drive element. The drive element includes: a movable portion; a drive unit that rotates the movable portion about a rotary shaft; a fixed portion that supports the movable portion and the drive unit and is fixed to the support substrate; and an electrode pad that is installed on the upper surface of the fixed portion and is connected to the drive unit. An electrode pad is disposed on the lower surface of the support substrate at a position facing an electrode pad. These electrode pads are connected to each other in a portion corresponding to a node of vibration generated in the fixed portion when the movable portion vibrates.

Description

Vibration module and optical deflector

[0001] The present invention relates to a vibration module that rotates a movable part about a rotation axis, and an optical deflector that includes the vibration module.

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

[0003] The following Patent Document 1 describes a driving element that rotates a movable part using a so-called tuning fork vibrator. In this driving element, a piezoelectric element is disposed on each of a pair of arms extending along a rotation axis. When an AC voltage is applied to these piezoelectric elements, the pair of arms expands and contracts. This causes the movable part to rotate about the rotation axis, and accordingly, a reflecting surface disposed on the movable part rotates. The tuning fork vibrator is connected to a frame-shaped fixed part via a connecting part that extends along the rotation axis.

[0004] Patent No. 5045470

[0005] In the drive element having the above configuration, for example, the lower surface of the frame-shaped fixing part is fixed to the substrate, and the drive element is installed on the substrate. Then, the connection terminals of the drive element are connected to the circuit on the substrate by wire bonding. However, in this case, the arrangement of the wire bonding increases the size of the entire configuration.

[0006] A first aspect of the present invention relates to a vibration module. The vibration module according to this aspect includes a drive element and a support substrate that supports the drive element. The drive element includes a movable part, a drive unit that rotates the movable part about a rotation axis, a fixed part that supports the movable part and the drive unit and is fixed to the support substrate, and a first electrode pad that is installed on an upper surface of the fixed part and connected to the drive unit by a wiring pattern. A second electrode pad is arranged on the lower surface of the support substrate at a position facing the first electrode pad, and the first electrode pad and the second electrode pad are connected to each other at a portion that corresponds to a vibration node that occurs on the fixed part when the movable part vibrates.

[0007] According to the vibration module of this aspect, the first electrode pad and the second electrode pad are connected to each other at the vibration node, thereby reducing the vibration displacement at the positions where the first electrode pad and the second electrode pad are arranged. This reduces the influence of vibration on the connection between the first electrode pad and the second electrode pad, thereby maintaining the reliability of the electrical connection between the first electrode pad and the second electrode pad. Furthermore, because the first electrode pad and the second electrode pad are connected to each other, the support substrate and the fixing portion can be electrically connected without using a separate wiring means such as wire bonding. This allows the overall configuration of the vibration module to be miniaturized.

[0008] A second aspect of the present invention relates to an optical deflector, which includes the vibration module according to the first aspect and a reflecting surface disposed on the movable part.

[0009] Since the optical deflector of this aspect includes the vibration module of the first aspect, the optical deflector of this aspect can stably deflect and scan light incident on the reflective surface at a predetermined deflection angle while increasing the reliability of the electrical connection between the first electrode pad and the second electrode pad.

[0010] As described above, according to the present invention, it is possible to provide a vibration module and an optical deflector that can achieve a reduction in the size of the entire configuration while maintaining the reliability of the electrical connection between the drive element and the substrate.

[0011] The effects and significance of the present invention will become more apparent from the following description of the embodiments, however, the embodiments shown below are merely examples of how the present invention can be implemented, and the present invention is not limited to the embodiments described below.

[0012] FIG. 1 is a perspective view showing the configuration of a drive element according to the first embodiment. FIG. 2 is a perspective view of the drive element according to the first embodiment, as viewed from the bottom side. FIG. 3 is a perspective view showing the configuration of a support substrate according to the first embodiment. FIG. 4 is a perspective view showing the assembly of a vibration module according to the first embodiment. FIG. 5 is a plan view showing an example of mounting a vibration module (optical deflector) according to the first embodiment. FIG. 6 is a cross-sectional view of a cross section of a vibration module (optical deflector) installed in a housing according to the first embodiment, as viewed in the negative direction of the X-axis. FIG. 7 is a plan view showing nodes and antinodes of vibration generated in a fixed part when a movable part is resonantly driven according to the first embodiment. FIG. 8 is a plan view showing the configuration of a vibration module (optical deflector) according to the first embodiment. FIG. 9 is a cross-sectional view of the C1-C2 cross section shown in FIG. 8 according to the first embodiment, as viewed in the positive direction of the Y-axis. FIG. 10A is a cross-sectional view of the C1-C2 cross section shown in FIG. 8 according to a first modification of fixing of the first embodiment, as viewed in the positive direction of the Y-axis. FIG. 10B is a cross-sectional view of the C1-C2 cross section shown in FIG. 8 as viewed in the positive direction of the Y-axis, according to a second modification of the fastening of the first embodiment. FIG. 11 is a perspective view showing the configuration of a drive element according to a first modification of the first embodiment. FIG. 12 is a perspective view showing the configuration of a support substrate according to a first modification of the first embodiment. FIG. 13 is a plan view showing the configuration of a vibration module (optical deflector) according to a first modification of the first embodiment. FIG. 14 is a plan view showing the configuration of a vibration module (optical deflector) according to a second modification of the first embodiment. FIG. 15 is a perspective view showing the configuration of a drive element according to the second embodiment. FIG. 16A is a diagram showing the configuration of a drive element used in a simulation of resonantly driving a movable part according to the second embodiment. FIG. 16B is a diagram showing the simulation results according to the second embodiment. FIG. 17 is a plan view showing the configuration of a vibration module (optical deflector) according to the second embodiment. FIG. 18A is a diagram showing the simulation results of vibration in the Z-axis direction generated in the drive element when the movable part is resonantly driven in the in-phase mode according to the third embodiment. 18B is a diagram showing a simulation result of vibration in the Z-axis direction generated in the drive element when the movable part is resonantly driven in the opposite phase mode according to embodiment 3. Fig. 19 is a block diagram showing the configuration of a vibration device according to embodiment 3.FIG. 20 is a plan view showing the configuration of a vibration module (optical deflector) according to the fourth embodiment.

[0013] Hereinafter, embodiments of the present invention will be described with reference to the drawings. For convenience, each drawing is labeled with X, Y, and Z axes that are orthogonal to each other. The Y axis direction is parallel to the rotation axis of the drive element, and the Z axis direction is the thickness direction of the drive element.

[0014] First Embodiment FIG. 1 is a perspective view showing the configuration of a driving element 1, and FIG. 2 is a perspective view of the driving element 1 as viewed from the bottom side (Z-axis negative side).

[0015] The driving element 1 includes a movable portion 11, two driving portions 12, two torsion portions 13, two connecting portions 14, and a fixed portion 15. The driving element 1 has a rectangular outline in a plan view. The driving element 1 has a shape that is symmetrical in the Y-axis direction and in the X-axis direction about the center of the movable portion 11.

[0016] The movable portion 11 is supported by the fixed portion 15 via two torsion portions 13 and two connecting portions 14 so as to be rotatable about a rotation axis R0. The rotation axis R0 extends parallel to the length direction (Y axis direction) of the drive element 1 at the midpoint in the width direction (X axis direction) of the drive element 1. A reflective surface 11a is formed on the upper surface (the surface on the positive side of the Z axis) of the movable portion 11. The reflective surface 11a is formed by laminating a highly reflective material (e.g., metals or metal compounds such as gold, silver, copper, or aluminum, or silicon dioxide or titanium dioxide) on the upper surface of the movable portion 11. The reflective surface 11a may be formed of a dielectric multilayer film. Alternatively, the reflective surface 11a may be formed by the upper surface of the movable portion 11. In this case, the reflective surface may be formed by mirror-finishing the upper surface of the movable portion 11.

[0017] The two torsion sections 13 have a beam-like shape extending along the rotation axis R0 and are arranged to sandwich the movable section 11 in the Y-axis direction. One end of the torsion section 13 on the Y-axis positive side is connected to the side surface of the movable section 11 on the Y-axis positive side, and the other end is connected to the connecting section 14 on the Y-axis positive side. One end of the torsion section 13 on the Y-axis negative side is connected to the side surface of the movable section 11 on the Y-axis negative side, and the other end is connected to the connecting section 14 on the Y-axis negative side.

[0018] The two connecting portions 14 have a plate-like shape extending along the rotation axis R0. The connecting portions 14 connect the drive portion 12 and the torsion portion 13 to the fixed portion 15.

[0019] The two drive units 12 each include a piezoelectric element 12b as a drive source and rotate the movable unit 11 about a rotation axis R0. Each of the two drive units 12 is formed by a tuning-fork vibrator. That is, the two tuning-fork vibrators are arranged in opposite directions along the rotation axis R0 to form the two drive units 12. One of the two drive units 12 (tuning-fork vibrators) and the other drive unit 12 (tuning-fork vibrator) are arranged in opposite directions to each other along the rotation axis R0.

[0020] Each drive unit 12 includes a pair of arm units 12a extending in an L-shape from the connecting unit 14. A piezoelectric element 12b for driving the movable unit 11 is disposed on the upper surface of the portion of each arm unit 12a extending in the Y-axis direction. In addition, a piezoelectric element 12c for detecting the vibration state of the arm unit 12a is disposed near the base of each arm unit 12a.

[0021] The piezoelectric bodies 12b and 12c have a laminated structure in which an upper electrode layer and a lower electrode layer are respectively arranged above and below a piezoelectric thin film of a predetermined thickness. The piezoelectric thin film is made of a piezoelectric material with a high piezoelectric constant, such as lead zirconate titanate (PZT). The material of the piezoelectric thin film is not limited to PZT, and piezoelectric materials with other compositions may also be used. The upper electrode layer and the lower electrode layer are made of a material with low electrical resistance and high heat resistance, such as platinum (Pt) or gold (Au). The piezoelectric bodies 12b and 12c are formed on the upper surface of the arm portion 12a by a method such as sputtering.

[0022] The fixed portion 15 has a rectangular frame shape in a plan view. The outer periphery of the fixed portion 15 forms the outer periphery of the drive element 1. The fixed portion 15 supports the movable portion 11, the drive portion 12, and the torsion portion 13 via two connecting portions 14. The fixed portion 15 is fixed to the support substrate 2 (see FIG. 3 ), as described below.

[0023] Two terminals 16 are arranged on the upper surface of the fixed portion 15. Each terminal 16 is connected to the corresponding piezoelectric body 12b, 12c via four wirings 16b. Similar to the piezoelectric bodies 12b, 12c, the wirings 16b have a layered structure in which upper and lower electrode layers are arranged above and below the piezoelectric thin film. On the upper surface of the terminal 16, four electrode pads 16a are arranged, which are connected to the upper electrode layers of the corresponding piezoelectric bodies 12b, 12c, and two electrode pads 16a are arranged, which are connected to the lower electrode layers of the corresponding piezoelectric bodies 12b, 12c and connect these lower electrode layers to ground.

[0024] The electrode pads 16a connected to the upper electrode layer are integrally formed with the corresponding piezoelectric bodies 12b, 12c and the upper electrode layers of the wiring 16b, and are made of, for example, platinum (Pt) or gold (Au). The electrode pads 16a connected to the lower electrode layer are integrally formed with the corresponding piezoelectric bodies 12b, 12c and the lower electrode layers of the wiring 16b, and are made of, for example, platinum (Pt) or gold (Au). Each electrode pad 16a is exposed upward. An insulating protective film is disposed on the upper surface of the area of ​​the terminal portion 16 other than the electrode pads 16a, the upper surface of the wiring 16b, and the upper surfaces of the piezoelectric bodies 12b, 12c.

[0025] The driving element 1 is formed by removing the material layer 1b by etching or the like from an integral structure consisting of a substrate 1a of a predetermined thickness and a material layer 1b so as to leave a region corresponding to the fixed portion 15. This increases the mechanical strength of the fixed portion 15.

[0026] The material of the material layer 1b may be different from that of the base material 1a, or may be the same as that of the base material 1a. The driving element 1 may also be configured by laminating the material layer 1b on the lower surface of a base material 1a having a predetermined thickness. In this case, the material layer 1b is laminated only in the region corresponding to the fixed portion 15.

[0027] The substrate 1a has the same contour as the drive element 1 in a plan view and a constant thickness. A reflecting surface 11a, piezoelectric elements 12b and 12c, terminal portion 16, electrode pads 16a, and wiring 16b are arranged in corresponding regions on the top surface of the substrate 1a. The substrate 1a is also removed by etching or the like so as to leave the movable portion 11, drive portion 12, torsion portion 13, and connecting portion 14, thereby forming the movable portion 11, drive portion 12, torsion portion 13, and connecting portion 14 on the substrate 1a. The area of ​​the substrate 1a other than the movable portion 11, drive portion 12, torsion portion 13, and connecting portion 14 forms an opening 15a that penetrates vertically.

[0028] The substrate 1a is integrally formed from, for example, silicon (Si). However, the material constituting the substrate 1a is not limited to silicon (Si) and may be other materials. The material constituting the substrate 1a is preferably a material with high mechanical strength and Young's modulus. The same applies to the material of the material layer 1b.

[0029] When the drive element 1 is driven, an AC voltage is applied to the four piezoelectric bodies 12b to resonantly drive the movable part 11 at the natural frequency (resonance frequency) of the drive element 1. As a result, each of the four piezoelectric bodies 12b deforms due to the inverse piezoelectric effect. At this time, the AC voltage applied to two piezoelectric bodies 12b aligned in the Y-axis direction is set to the same phase, and the AC voltage applied to two piezoelectric bodies 12b aligned in the X-axis direction is set to the opposite phase. As a result, the deformation direction (amplitude direction) of the two piezoelectric bodies 12b on the positive side of the X-axis is opposite to the deformation direction (amplitude direction) of the piezoelectric body 12b on the negative side of the X-axis. In this way, the deformation of the four piezoelectric bodies 12b deforms the arm portion 12a, and the movable part 11 is resonantly driven around the rotation axis R0 at a predetermined resonant frequency via the two torsion portions 13.

[0030] The four piezoelectric elements 12c for vibration detection generate currents due to the piezoelectric effect in response to the deformation of the corresponding arms 12a. Therefore, the vibration state of the arms 12a can be monitored from these currents. An external circuit connected to the support substrate 2 (described later) uses these currents to control the AC voltages applied to the piezoelectric elements 12b so that the amplitude, frequency, and phase of each arm 12a converge to their respective target values. This causes the movable element 11 and the reflecting surface 11a to rotate at the target resonant frequency and deflection angle.

[0031] Fig. 3 is a perspective view showing the configuration of the support substrate 2. Fig. 3 is a perspective view of the support substrate 2 as viewed from the bottom surface side (negative side of the Z axis). The support substrate 2 is located above the drive element 1 and has a bottom surface facing the drive element 1.

[0032] The support substrate 2 has a frame shape with a rectangular outline in a plan view. An opening 2a is formed in the support substrate 2, penetrating the support substrate 2 in the Z-axis direction. The opening 2a has a rectangular shape in a plan view. Four screw holes 2b are formed in the corners of the support substrate 2, penetrating the support substrate 2 in the Z-axis direction. The support substrate 2 is made of a material with a high elastic modulus, such as a glass epoxy substrate, a paper phenol substrate, a ceramic substrate, or a glass substrate.

[0033] Two terminals 21 are arranged on the lower surface (the surface on the negative side of the Z axis) of the support substrate 2. Six electrode pads 21a are arranged on each terminal 21, exposed downward (in the negative direction of the Z axis). The electrode pads 21a are made of a metal with high electrical conductivity, such as copper (Cu), platinum (Pt), or gold (Au). Each electrode pad 21a in the two terminals 21 is connected to a connection terminal 22 installed on the side of the support substrate 2 via a wiring pattern (not shown) arranged on the surface of the support substrate 2. In this case, the wiring pattern is also made of a metal with high electrical conductivity, such as copper (Cu), platinum (Pt), or gold (Au). An insulating protective film is arranged on the lower surface (the surface on the negative side of the Z axis) of the region of the terminal 21 other than the electrode pads 21a and on the lower surface (the surface on the negative side of the Z axis) of the wiring pattern connecting each electrode pad 21a to the connection terminal 22. For convenience, FIG. 3 shows a state in which a flexible printed circuit board FPC is connected to the connection terminal 22.

[0034] The twelve electrode pads 21a provided on the support substrate 2 are positioned so as to overlap with the twelve electrode pads 16a (see Figure 1) provided on the drive element 1 when the support substrate 2 and the drive element 1 are fixed together.

[0035] The electrode pads 21a and 16a arranged at positions where they overlap each other are equal in size, and the centers of the electrode pads 21a and 16a arranged at positions where they overlap each other are aligned. However, the electrode pads 21a and 16a arranged at positions where they overlap each other may be different in size, and the centers of the electrode pads 21a and 16a arranged at positions where they overlap each other may not be aligned.

[0036] FIG. 4 is a perspective view showing the assembly of the vibration module 3. As shown in FIG.

[0037] With the opposing electrode pads 21a, 16a electrically connected by a conductive adhesive 31, the upper surface (the surface on the positive side of the Z axis) of the fixing portion 15 of the driving element 1 is fixed to the lower surface (the surface on the negative side of the Z axis) of the support substrate 2 by an adhesive 32, which will be described later. At this time, the fixing portion 15 is fixed to the lower surface of the support substrate 2 so that the center of the driving element 1 coincides with the center of the support substrate 2 in a plan view. The connection of the electrode pads 21a, 16a and the fixing of the support substrate 2 and the fixing portion 15 will be described later with reference to FIG. 9 . The support substrate 2 supports the driving element 1, thereby completing a vibration module 3 consisting of the driving element 1 and the support substrate 2. In this way, the electrode pad 16a of the driving element 1 is connected to a connection terminal 22 (see FIG. 3) via the electrode pad 21a of the support substrate 2, and is connected to an external circuit via a flexible printed circuit board FPC (see FIG. 3) connected to the connection terminal 22.

[0038] In this embodiment, a reflective surface 11a is formed on the upper surface of the movable part 11. Therefore, the vibration module 3 constitutes an optical deflector 3a that deflects light incident on the reflective surface 11a in response to the driving of the movable part 11.

[0039] FIG. 5 is a perspective view showing an example of mounting the vibration module 3 (optical deflector 3a).

[0040] The vibration module 3 (optical deflector 3a) is mounted on the target device by being fixed to a housing 4 as shown in Fig. 5. Assembly in this case will be described below.

[0041] The housing 4 is a plate-like member with a rectangular outline in a plan view. Four holes 41 are formed in the housing 4, which respectively face the four screw holes 2b of the support substrate 2 when the support substrate 2 and the housing 4 are stacked together. The upper ends of four bolts 42 are fixed to the four screw holes 2b of the fixing portion 15, and the lower ends of the four bolts 42 are fixed to the four holes 41 of the housing 4 by nuts 43. In this way, the vibration module 3 (optical deflector 3a) is installed in the housing 4 with a predetermined gap between it and the top surface of the housing 4.

[0042] FIG. 6 is a cross-sectional view of the vibration module 3 (optical deflector 3a) installed in the housing 4, taken along the YZ plane passing through the rotation axis R0, as viewed in the negative direction of the X axis.

[0043] Incident light L1 incident on the vibration module 3 (optical deflector 3a) from above (positive side of the Z axis) is irradiated onto the reflective surface 11a of the movable part 11 through the opening 2a of the support substrate 2. The incident light L1 is reflected by the reflective surface 11a in a direction according to the rotation angle of the movable part 11. The incident light L1 reflected by the reflective surface 11a is irradiated as reflected light L2 onto a scanning region located above the vibration module 3 (optical deflector 3a) through the opening 2a.

[0044] In the driving element 1 having the above configuration, the four piezoelectric bodies 12b are driven so that the movable part 11 rotates repeatedly at the natural resonance frequency, as described above. At this time, the vibration in the Z-axis direction generated in the fixed part 15 differs depending on the position, being larger at the antinodes and smaller at the nodes.

[0045] FIG. 7 is a plan view showing the nodes and antinodes of vibrations that occur in the fixed part 15 when the movable part 11 is resonantly driven.

[0046] In the driving element 1 of embodiment 1, portions P11, P12, P13, P14, P15, and P16 surrounded by dashed lines correspond to nodes where vibration in the Z-axis direction decreases when the movable part 11 is resonantly driven. On the other hand, portions P21, P22, P23, P31, P32, and P33 surrounded by dashed lines correspond to antinodes where vibration in the Z-axis direction increases when the movable part 11 is resonantly driven. In other words, portions P11, P12, P13, P14, P15, and P16 of the driving element 1 (fixed part 15) are nodes where vibration in the Z-axis direction decreases when the movable part 11 is resonantly driven. Portions P21, P22, P23, P31, P32, and P33 of the driving element 1 (fixed part 15) are antinodes where vibration in the Z-axis direction increases when the movable part 11 is resonantly driven.

[0047] The node portions P11 and P12 are located symmetrically to each other on the rotation axis R0 with respect to the movable portion 11. The antinode portions P21, P22, P31, and P32 are located near the four corners of the fixed portion 15. The antinode portion P23 is located near the midpoint between the antinode portions P21 and P22, and the antinode portion P33 is located near the midpoint between the antinode portions P31 and P32. The node portion P13 is located near the midpoint between the antinode portions P21 and P23, the node portion P14 is located near the midpoint between the antinode portions P22 and P23, the node portion P15 is located near the midpoint between the antinode portions P31 and P33, and the node portion P16 is located near the midpoint between the antinode portions P32 and P33.

[0048] 8 is a plan view showing the configuration of the vibration module 3 (optical deflector 3a). In Fig. 8, for convenience, the support substrate 2 is shown in a transparent state, and the outer periphery of the support substrate 2 and the outline of the opening 2a are shown by thick dotted lines.

[0049] In a plan view, the electrode pads 21 a, 16 a are arranged at node portions P11, P12 where the vibration in the Z-axis direction of the fixed portion 15 is reduced. This makes it possible to improve the reliability of the electrical connection between the electrode pads 16 a, 21 a in the vibration module 3 in which the support substrate 2 and the fixed portion 15 are fixed.

[0050] FIG. 9 is a cross-sectional view taken along the line C1-C2 in FIG. 8 as viewed in the positive direction of the Y axis.

[0051] The electrode pads 21 a, 16 a are connected with a conductive adhesive 31, and the support substrate 2 and the fixing portion 15 are fixed with an insulating adhesive 32. When assembling the vibration module 3, the conductive adhesive 31 is applied to the electrode pad 21 a or the electrode pad 16 a, and the support substrate 2 and the fixing portion 15 are overlapped. The area where the conductive adhesive 31 is disposed is an area that includes the overlapping portion of the electrode pads 21 a, 16 a and the vicinity thereof in a plan view. Then, adhesive 32 is injected from the gap between the lower surface of the support substrate 2 and the upper surface of the fixing portion 15. The area where the adhesive 32 is disposed is the entire area of ​​the upper surface (the surface on the positive side of the Z axis) of the fixing portion 15 excluding the area where the conductive adhesive 31 is disposed.

[0052] The conductive adhesive 31 is configured to have conductivity and a lower modulus of elasticity than that of a general metal alone. Specifically, the conductive adhesive 31 includes an adhesive material and a conductive filler dispersed in the adhesive material.

[0053] The adhesive material of the conductive adhesive 31 is, for example, an epoxy resin, a silicone resin, a urethane resin, or an acrylic resin. When the adhesive material of the conductive adhesive 31 is a resin such as those described above, the elastic modulus of the conductive adhesive 31 can be set to, for example, 10,000 MPa or less, preferably 1,000 MPa or less, and more preferably 100 MPa. A lower elastic modulus of the conductive adhesive 31 is preferable.

[0054] The conductive filler of the conductive adhesive 31 is, for example, conductive particles made of a conductive material such as silver (Ag), copper (Cu), gold (Au), nickel (Ni), and carbon (C). When the conductive filler of the conductive adhesive 31 is made of such a material, the resistivity of the conductive adhesive 31 is set to, for example, 1×10 －３ Ω cm or less, preferably 1×10 －４ Ω cm or less, more preferably 1×10 －５ The resistivity of the conductive adhesive 31 can be set to Ω cm or less. The lower the resistivity, the better. The particle diameter of the conductive filler in the conductive adhesive 31 is, for example, several μm to several tens of μm. This allows the electrical connection by the conductive adhesive 31 to be maintained even if the adhesive material of the conductive adhesive 31 has a low modulus of elasticity.

[0055] As described above, when the elastic modulus of the conductive adhesive 31 is set low, even if vibrations generated in the fixing portion 15 are transmitted to the conductive adhesive 31, stress is less likely to concentrate on the conductive adhesive 31. This makes it possible to maintain the reliability of the electrical connection between the electrode pads 21 a and 16 a. Furthermore, when the resistivity of the conductive adhesive 31 is set low as described above, it is possible to suppress the generation of Joule heat in the conductive adhesive 31, allowing the drive voltage from an external circuit to be applied efficiently to the piezoelectric body 12 b and the current generated in the piezoelectric body 12 c to be output efficiently to the external circuit.

[0056] The adhesive 32 is an underfill material having a higher elastic modulus than the conductive adhesive 31. The material of the adhesive 32 is selected from, for example, epoxy resin, acrylic resin, polyimide resin, etc., so that the material has a higher elastic modulus than the conductive adhesive 31. The higher the elastic modulus of the adhesive 32, the better.

[0057] As described above, by setting the elastic modulus of the adhesive 32 higher than that of the conductive adhesive 31, the periphery of the conductive adhesive 31 is fixed with the adhesive 32 having a higher elastic modulus, thereby suppressing vibration displacement around the conductive adhesive 31. This prevents fatigue caused by vibration in the conductive adhesive 31 connecting the electrode pad 21a and the electrode pad 16a. This maintains the reliability of the electrical connection between the electrode pads 21a and 16a.

[0058] The connection of the electrode pads 21 a, 16 a and the fixing of the support substrate 2 and the fixing portion 15 are not limited to being performed using the conductive adhesive 31 and the adhesive 32. For example, the above-mentioned connection and fixing may be performed as shown in Figures 10A and 10B.

[0059] FIG. 10A is a cross-sectional view showing the configuration of Modification 1 in which the electrode pads 21 a and 16 a are connected by a conductive member 33 and the support substrate 2 and the fixing portion 15 are fixed by an adhesive 32 .

[0060] The conductive member 33 is, for example, solder. In this case as well, when assembling the vibration module 3, the conductive member 33 is placed on the electrode pad 21 a or the electrode pad 16 a, and the support substrate 2 and the fixing portion 15 are overlapped. Thereafter, the adhesive 32 is injected from the gap between the lower surface of the support substrate 2 and the upper surface of the fixing portion 15 onto the entire area of ​​the upper surface of the fixing portion 15. This allows the support substrate 2 and the fixing portion 15 to be fixed together while maintaining the reliability of the electrical connection between the electrode pads 21 a, 16 a, as in the case of FIG. 9 .

[0061] FIG. 10B is a cross-sectional view showing the configuration of Modification 2 in which the connection between electrode pads 21 a and 16 a and the fixing of support substrate 2 and fixing portion 15 are performed with conductive adhesive 34 .

[0062] The conductive adhesive 34 includes an insulating adhesive material 34A and a conductive filler 34B dispersed in the adhesive material 34A. The adhesive material 34A of the conductive adhesive 34 can be the same material as the adhesive material of the adhesive 32, and the conductive filler 34B of the conductive adhesive 34 can be the same material as the conductive filler of the conductive adhesive 31. The particle diameter of the conductive filler 34B of the conductive adhesive 34 is, for example, approximately 3 μm to 10 μm. The conductive adhesive 34 is, for example, an anisotropic conductive paste (ACP) or an anisotropic conductive film (ACF). In this case, during assembly of the vibration module 3, the conductive adhesive 34 is disposed on the lower surface of the support substrate 2 or the upper surface of the fixing portion 15 in an area corresponding to the entire area of ​​the upper surface of the fixing portion 15. The support substrate 2 and the fixing portion 15 are then superimposed and fixed. The conductive adhesive 34 includes a plurality of conductive fillers 34B that are separated and insulated from each other. One electrode pad 21a is electrically connected to one electrode pad 16a via a conductive filler 34B. Another electrode pad 21a is electrically connected to another electrode pad 16a via another conductive filler 34B that is separated from and insulated from the conductive filler 34B that electrically connects the one electrode pad 21a to the one electrode pad 16a.

[0063] 10B , in order to reliably bond the support substrate 2 and the fixing portion 15 and to compress and fix the conductive filler 34B of the conductive adhesive 34 at the positions of the electrode pads 21 a, 16 a, an adhesive material with a high elastic modulus is used as the adhesive material for the conductive adhesive 34, similar to the adhesive 32 in FIG. 9 . In this case, although vibration displacement around the electrode pads 21 a, 16 a can be suppressed, stress tends to concentrate on the conductive adhesive 34 at the positions of the electrode pads 21 a, 16 a. Therefore, in order to suppress stress concentration at the connection portions of the electrode pads 21 a, 16 a, it is more preferable to use different materials for connecting the electrode pads 21 a, 16 a and for fixing the support substrate 2 and the fixing portion 15, as in the configuration in FIG. 9 .

[0064] <Effects of First Embodiment> According to the first embodiment, the following effects are achieved.

[0065] As shown in FIG. 4 , the vibration module 3 includes a driving element 1 and a support substrate 2 that supports the driving element 1. As shown in FIG. 1 , the driving element 1 includes a movable portion 11, a driving portion 12 that rotates the movable portion 11 about a rotation axis R0, a fixed portion 15 that supports the movable portion 11 and the driving portion 12 and is fixed to the support substrate 2, and an electrode pad 16a (first electrode pad) that is installed on the upper surface of the fixed portion 15 and connected to the piezoelectric elements 12b and 12c of the driving portion 12 by a wiring 16b (wiring pattern). As shown in FIG. 4 , an electrode pad 21a (second electrode pad) is disposed on the lower surface of the support substrate 2 in a position opposite the electrode pad 16a (first electrode pad). As shown in FIG. 8 , the electrode pad 16a (first electrode pad) and the electrode pad 21a (second electrode pad) are connected to each other at portions P11 and P12 that correspond to vibration nodes generated in the fixed portion 15 when the movable portion 11 vibrates.

[0066] According to this configuration, the electrode pads 16a and 21a are connected to each other at the vibration node portions P11 and P12, thereby reducing the amount of vibration displacement at the positions where the electrode pads 16a and 21a are arranged. This reduces the effect of vibration on the connection between the electrode pads 16a and 21a, thereby maintaining the reliability of the electrical connection between the electrode pads 16a and 21a. Furthermore, because the electrode pads 16a and 21a are connected to each other, the support substrate 2 and the fixing portion 15 can be electrically connected without using a separate wiring means such as wire bonding. This allows the overall configuration of the vibration module 3 to be miniaturized.

[0067] As shown in FIG. 9, the electrode pad 16a (first electrode pad) and the electrode pad 21a (second electrode pad) are electrically connected to each other by a conductive adhesive 31 in which a conductive filler is mixed into a resin material.

[0068] With this configuration, the elastic modulus of the conductive adhesive 31 can be set lower than that of common conductive metals (such as silver or copper). As a result, even if vibrations generated in the fixing portion 15 are transmitted to the conductive adhesive 31, stress is less likely to concentrate on the conductive adhesive 31 because the elastic modulus of the conductive adhesive 31 is low. This makes it possible to maintain the reliability of the electrical connection between the electrode pads 16 a and 21 a.

[0069] As shown in Figure 9, the area where the conductive adhesive 31 is placed is the area near where the electrode pad 16a (first electrode pad) and the electrode pad 21a (second electrode pad) overlap in a planar view, and at least around the area where the conductive adhesive 31 is placed, the fixing portion 15 and the support substrate 2 are fixed together by an adhesive 32 having a higher elastic modulus than the conductive adhesive 31.

[0070] With this configuration, the periphery of the conductive adhesive 31 is fixed with the adhesive 32 having a high elastic modulus, thereby suppressing vibration displacement around the conductive adhesive 31. This prevents fatigue caused by vibration in the conductive adhesive 31 connecting the electrode pads 16 a and 21 a. This maintains the reliability of the electrical connection between the electrode pads 16 a and 21 a.

[0071] As shown in FIG. 10B , in an area including at least the areas of the electrode pad 16 a (first electrode pad) and the electrode pad 21 a (second electrode pad), the electrode pads 16 a and 21 a may be electrically connected by adhering the fixing portion 15 and the support substrate 2 with a paste-like or film-like conductive adhesive 34 in which conductive filler 34B is mixed into a resin material (adhesive material 34A).

[0072] 9 and 10A, the electrical connection between the electrode pads 16a, 21a and the adhesion between the fixing portion 15 and the support substrate 2 can be achieved by the conductive adhesive 34. Furthermore, since the conductive adhesive 34 can be used both for the electrical connection between the electrode pads 16a, 21a and for fixing the fixing portion 15 and the support substrate 2, the manufacturing process can be simplified.

[0073] 9 and 10A , when connecting the electrode pads 16 a, 21 a using the conductive adhesive 31 or the conductive member 33, it is necessary to place the conductive adhesive 31 or the conductive member 33, overlap the lower surface of the support substrate 2 with the upper surface of the fixing portion 15, and then inject the adhesive 32 through the gap between the support substrate 2 and the fixing portion 15. In contrast, when using the conductive adhesive 34, the fixing process can be completed simply by placing the conductive adhesive 34 at a predetermined position on the lower surface of the support substrate 2 or the upper surface of the fixing portion 15, and then overlapping the support substrate 2 with the fixing portion 15. Therefore, the use of the conductive adhesive 34 makes it easy to place the conductive adhesive 34 at the desired position and simplifies the fixing process.

[0074] As shown in FIG. 1, two drive units 12 are arranged in opposite directions along the rotation axis R0.

[0075] According to this configuration, the movable part 11 can be driven stably with a larger torque.

[0076] As shown in FIG. 1, the driving unit 12 is a tuning fork type vibrator.

[0077] According to this configuration, the movable part 11 can be smoothly and repeatedly rotated (resonantly driven) about the rotation axis R0.

[0078] As shown in FIG. 4, the optical deflector 3 a includes a vibration module 3 and a reflecting surface 11 a disposed on a movable part 11 .

[0079] Since the optical deflector 3a includes the vibration module 3, this configuration enables the light incident on the reflecting surface 11a to be stably deflected and scanned at a predetermined deflection angle while increasing the reliability of the electrical connection between the electrode pads 16a and 21a.

[0080] <First Modification of First Embodiment> In the first embodiment, electrode pads are arranged only at the node portions P11 and P12, but in the second embodiment, electrode pads are also arranged at portions other than the node portions P11 and P12.

[0081] FIG. 11 is a perspective view showing the configuration of a driving element 1 according to a first modification of the first embodiment.

[0082] In this modified example, compared to the first embodiment shown in Fig. 1, terminal portions 17 are arranged at vibration antinode portions P21, P22, P31, and P32 (see Fig. 7) on the upper surface of fixed portion 15. Four electrode pads 17a are arranged on the upper surface of terminal portion 17. However, electrode pads 17a are so-called dummy electrodes and are not connected to other portions.

[0083] Of the four electrode pads 17a of the terminal portion 17, a laminated structure consisting of an upper electrode layer, a piezoelectric thin film, and a lower electrode layer is arranged at the position of the two inner electrode pads 17a (closer to the movable portion 11), similar to the four electrode pads 16a on the inside of the terminal portion 16. A lower electrode layer is arranged at the position of the two outer electrode pads 17a of the terminal portion 17 (opposite the movable portion 11), similar to the two outer electrode pads 16a of the terminal portion 16. As a result, the positions of the two inner electrode pads 17a of the terminal portion 17 in the Z-axis direction are the same as the positions of the four inner electrode pads 16a of the terminal portion 16, and the positions of the two outer electrode pads 17a of the terminal portion 17 in the Z-axis direction are the same as the positions of the two outer electrode pads 16a of the terminal portion 16.

[0084] FIG. 12 is a perspective view showing the configuration of a support substrate 2 according to a first modification of the first embodiment.

[0085] In this modified example, compared to the first embodiment shown in FIG. 3, four terminal portions 23 are arranged on the lower surface (surface on the negative side of the Z axis) of the support substrate 2. Four electrode pads 23a exposed downward are arranged on the terminal portions 23. The electrode pads 23a are configured similarly to the electrode pads 21a. However, the electrode pads 23a are so-called dummy electrodes and are not connected to other portions. The 16 electrode pads 23a provided on the support substrate 2 are arranged at positions that overlap with the 16 electrode pads 17a (see FIG. 11) provided on the drive element 1 when the support substrate 2 and the drive element 1 are fixed together.

[0086] FIG. 13 is a plan view showing the configuration of the vibration module 3 (optical deflector 3a) according to the first modification of the first embodiment.

[0087] In a plan view, the electrode pads 23a and 17a are arranged at antinode portions P21, P22, P31, and P32 where the vibration in the Z-axis direction of the fixed portion 15 becomes large. When assembling the vibration module 3, the conductive adhesive 31 and the adhesive 32 are used, as in the case of FIG. 9 .

[0088] That is, the electrode pads 21 a and 16 a are electrically connected by the conductive adhesive 31, and the electrode pads 23 a and 17 a are electrically connected by the conductive adhesive 31. In this case, too, the area where the conductive adhesive 31 is disposed is the area near where the electrode pads 21 a and 16 a overlap each other, and the area near where the electrode pads 23 a and 17 a overlap each other in a plan view. Thereafter, adhesive 32 is injected from the gap between the lower surface of the support substrate 2 and the upper surface of the fixing portion 15. The area where the adhesive 32 is disposed is the entire area of ​​the upper surface (the surface on the positive side of the Z axis) of the fixing portion 15, excluding the area where the conductive adhesive 31 is disposed.

[0089] According to this modification, the following effects are achieved.

[0090] 13 , electrode pads 17a (third electrode pads) and 23a (fourth electrode pads) are arranged opposite each other on the upper surface of the fixing portion 15 and the lower surface of the support substrate 2 at positions other than the positions where electrode pads 16a (first electrode pads) and electrode pads 21a (second electrode pads) are arranged. Electrode pads 17a (third electrode pads) and electrode pads 23a (fourth electrode pads) are connected to each other by a conductive adhesive 31.

[0091] According to this configuration, the conductive adhesive 31 is placed not only at the positions where the electrode pads 16 a and 21 a are disposed, but also at the positions where the electrode pads 17 a and 23 a are disposed. This allows the supporting substrate 2 and the driving element 1 to be overlapped with high precision after the conductive adhesive 31 is placed during assembly. Furthermore, the connection of the electrode pads 17 a and 23 a and the connection of the electrode pads 16 a and 21 a can be performed by the same process of placing the conductive adhesive 31 between the opposing electrode pads.

[0092] 13, the electrode pad 16a (first electrode pad) and the electrode pad 21a (second electrode pad) are arranged at node portions P11 and P21 near the rotation axis R0 in a plan view. The pair of electrode pads 17a (third electrode pad) and 23a (fourth electrode pad) are arranged at two positions symmetrical with respect to the rotation axis R0 in a plan view.

[0093] According to this configuration, when the conductive adhesive 31 is disposed to bond the lower surface of the support substrate 2 to the upper surface of the fixing portion 15, the conductive adhesive 31 interposed between the two sets of electrode pads 17 a, 23 a maintains a gap between the support substrate 2 and the fixing portion 15. This makes it possible to easily bond the support substrate 2 and the fixing portion 15 so that they are parallel to each other.

[0094] In this modification, the pair of electrode pads 23a, 17a are respectively arranged at the vibration antinode portions P21, P22, P31, and P32 of the fixed portion 15, but they may be arranged at other positions. However, by arranging the pair of electrode pads 23a, 17a at positions far from the rotation axis R0 as described above, it becomes easier to bond the support substrate 2 and the drive element 1 in parallel during assembly. Furthermore, by arranging the pair of electrode pads 23a, 17a near the four corners of the fixed portion 15 as described above, it becomes easier to bond the support substrate 2 and the fixed portion 15 in parallel during assembly.

[0095] Also in this modified example, the conductive member 33 shown in Fig. 10A may be used instead of the conductive adhesive 31. Moreover, the conductive adhesive 31 and the adhesive 32 may be used instead of the conductive adhesive 34 shown in Fig. 10B.

[0096] <Modification 2 of Embodiment 1> In Modification 1 of Embodiment 1, two tuning-fork vibrators (drive units 12) are arranged in opposite directions along the rotation axis R0 in plan view, but as shown in FIG. 14 , only one may be arranged along the rotation axis R0.

[0097] FIG. 14 is a plan view showing the configuration of the vibration module 3 (optical deflector 3a) according to the second modification of the first embodiment.

[0098] 13 , in this modification, the pair of drive unit 12 and connecting unit 14 is disposed on only one side of movable unit 11 along rotation axis R0, and electrode pads 23a and 17a are disposed on ends P41 and P42 on the negative Y-axis side of the side of fixed unit 15 extending in the Y-axis direction. In this case as well, the pair of electrode pads 21a and 16a are connected by conductive adhesive 31, and the pair of electrode pads 23a and 17a are connected by conductive adhesive 31. Then, adhesive 32 is disposed over the entire area of ​​the upper surface of fixed unit 15.

[0099] According to this modified example, compared to modified example 1 of embodiment 1, the configuration on the negative side of the Y axis of the movable part 11 is omitted, so that the support substrate 2 and the vibration module 3 (optical deflector 3a) can be made smaller in the Y axis direction.

[0100] In this modified example, the conductive member 33 shown in FIG. 10A may be used instead of the conductive adhesive 31, and the conductive adhesive 31 and the adhesive 32 may be used instead of the conductive adhesive 34 shown in FIG. 10B.

[0101] Second Embodiment In the first embodiment, the fixing portion 15 is configured in a frame shape, but in the second embodiment, the fixing portion 15 is configured by two first portions 18a and one second portion 18b.

[0102] FIG. 15 is a perspective view showing the configuration of a driving element 1 according to the second embodiment.

[0103] In the second embodiment, compared to the first embodiment shown in FIG. 1 , the fixing portion 15 includes a first portion 18a that supports the connecting portion 14 on the positive side of the Y axis from the outside, a first portion 18a that supports the connecting portion 14 on the negative side of the Y axis from the outside, and a second portion 18b (lower cover) that connects the lower surfaces of the two first portions 18a (lower surfaces of the material layer 1b). The second portion 18b may be made of, for example, silicon (Si). The second portion 18b may be processed and molded together with the driving element 1 from a single SOI wafer, or the second portion 18b molded separately from the driving element 1 may be bonded to the lower surfaces of the two first portions 18a.

[0104] FIG. 16A is a diagram showing the configuration of the driving element 1 used in a simulation for resonantly driving the movable part 11, and FIG. 16B is a diagram showing the simulation results.

[0105] For convenience, Fig. 16A illustrates the driving element 1 without the second portion 18b of the fixed portion 15, while Fig. 16B illustrates the two first portions 18a of the fixed portion 15 and the second portion 18b of the fixed portion 15 indicated by dashed lines. In Fig. 16B, the closer to black the color, the greater the vibration, and the closer to white the color, the smaller the vibration. In Fig. 16B, vibration is small at portions P11 and P12 surrounded by dashed lines, and vibration is large at portions P21, P22, P31, and P32 surrounded by dashed lines. That is, portions P11 and P12 correspond to vibration nodes, and portions P21, P22, P31, and P32 correspond to vibration antinodes.

[0106] FIG. 17 is a plan view showing the configuration of the vibration module 3 (optical deflector 3a) according to the second embodiment.

[0107] In the second embodiment, similarly to the first embodiment, the electrode pads 21a and 16a are arranged at the node portions P11 and P12, and the pair of electrode pads 21a and 16a are electrically connected by the conductive adhesive 31, and the adhesive 32 is arranged in the portions other than the conductive adhesive 31. This can improve the reliability of the electrical connection between the electrode pads 16a and 21a.

[0108] In addition, in embodiment 2, the conductive member 33 shown in FIG. 10A may be used instead of the conductive adhesive 31, and the conductive adhesive 34 shown in FIG. 10B may be used instead of the conductive adhesive 31 and the adhesive 32.

[0109] <Embodiment 3> When the movable part 11 is resonantly driven at a target frequency, the driving method of the driving element 1 includes an in-phase mode in which the movable part 11 and the connecting part 14 rotate in the same direction, and an out-of-phase mode in which the movable part 11 and the connecting part 14 rotate in opposite directions.

[0110] 18A and 18B are diagrams showing simulation results of vibrations in the Z-axis direction that occur in the drive element 1 when the movable part 11 is resonantly driven in the in-phase mode and the out-of-phase mode, respectively.

[0111] In this simulation, the shape of the arm portion 12a of the drive portion 12 and the shape of the movable portion 11 are slightly different from those shown in FIG. 1, but the amount of vibration in the Z-axis direction in each portion is considered to be approximately the same as the configuration shown in FIG. 1.

[0112] For convenience, only the substrate 1a of the driving element 1 is shown in Figures 18A and 18B. In Figures 18A and 18B, parts where vibrations of the same magnitude occur are colored the same, with the blacker the color, the stronger the vibration and the whiter the color, the weaker the vibration. In Figures 18A and 18B, parts P11, P12, P13, P14, P15, and P16 surrounded by dashed circles correspond to vibration nodes, and parts P21, P22, P23, P31, P32, and P33 surrounded by dashed circles correspond to vibration antinodes.

[0113] In the antiphase mode of Fig. 18B, the vibration generated in fixed portion 15 is smaller than in the inphase mode of Fig. 18A, and therefore the color of fixed portion 15 is approximately the same. However, even in the antiphase mode, nodes and antinodes occur at positions similar to those in the inphase mode, as shown by the dashed and dashed line boxes in Fig. 18B.

[0114] When the movable part 11 is resonantly driven at the target frequency, whether the driving element 1 drives in in-phase mode or out-of-phase mode can be set by adjusting, for example, the thicknesses of the movable part 11, arm part 12a, torsion part 13 and connecting part 14, the width and length of the torsion part 13, the width and length of the arm part 12a, etc.

[0115] In other words, when the antiphase mode is used to drive the movable part 11, the parameters of each part of the drive element 1 related to the resonance frequency may be adjusted so that resonance occurs in the antiphase mode at the target frequency, thereby configuring the vibration module 3. Similarly, when the inphase mode is used to drive the movable part 11, the parameters of each part of the drive element 1 related to the resonance frequency may be adjusted so that resonance occurs in the inphase mode at the target frequency, thereby configuring the vibration module 3.

[0116] FIG. 19 is a block diagram showing the configuration of the vibration device 5.

[0117] The vibration device 5 includes a vibration module 3 (optical deflector 3a) similar to those in the first and second embodiments and the first and second modifications of the first embodiment, a control circuit 5a, and a drive circuit 5b. The four piezoelectric bodies 12c are connected to the control circuit 5a via electrode pads 16a and 21a and connection terminals 22. The drive circuit 5b is connected to the four piezoelectric bodies 12b via connection terminals 22 and electrode pads 21a and 16a.

[0118] The control circuit 5a controls the drive circuit 5b based on the detection signal from the piezoelectric bodies 12c so that the movable part 11 is driven at the target resonance frequency. The drive circuit 5b applies drive signals to the four piezoelectric bodies 12b in accordance with the control from the control circuit 5a. At this time, if the drive element 1 (vibration module 3) is configured so that the movable part 11 resonates at the target frequency when driven in in-phase mode, the drive element 1 is driven in in-phase mode. On the other hand, if the drive element 1 (vibration module 3) is configured so that the movable part 11 resonates at the target frequency when driven in anti-phase mode, the drive element 1 is driven in anti-phase mode.

[0119] In the in-phase mode, the rotation directions of the movable portion 11 and the connecting portion 14 are the same, so the rotational moment transmitted to the fixed portion 15 by the movable portion 11 and the connecting portion 14 is large, resulting in a large displacement of the fixed portion 15, as shown in FIG. 18A . In contrast, in the out-of-phase mode, the rotational moment generated in the movable portion 11 and the rotational moment generated in the connecting portion 14 cancel each other out, so the rotational moment transmitted to the fixed portion 15 by the movable portion 11 and the connecting portion 14 is suppressed. As a result, as shown in FIG. 18B , the displacement of the entire fixed portion 15 is smaller in the out-of-phase mode than in the in-phase mode, thereby improving the reliability of the electrical connection between the paired electrode pads 16 a and 21 a. Therefore, the out-of-phase mode is preferable from the viewpoint of improving the reliability of the electrical connection between the electrode pads 16 a and 21 a.

[0120] Fourth Embodiment In the first to third embodiments, the driving unit 12 is a tuning fork type vibrator, but the driving unit 12 may be a vibrator of another type. In a fourth embodiment, the driving unit 12 is a meander type vibrator.

[0121] FIG. 20 is a plan view showing the configuration of the vibration module 3 (optical deflector 3a) according to the fourth embodiment.

[0122] In this embodiment, compared to the first embodiment shown in Fig. 8, the pair of torsion units 13 is omitted, and the pair of drive units 12 are meandering vibrators. The drive unit 12 includes four rectangular arm units 12a connected to each other, and two piezoelectric bodies 12b and two piezoelectric bodies 12c installed on the four arm units 12a. The inner end of the drive unit 12 is connected to the movable unit 11, and the outer end of the drive unit 12 is connected to the fixed unit 15 via a connecting unit 14. In the fourth embodiment, too, each terminal unit 16 is connected to the corresponding piezoelectric body 12b, 12c via a wiring pattern (not shown).

[0123] 7, in this embodiment, vibration nodes occur at portions P11 to P16, and vibration antinodes occur at portions P21 to P23 and P31 to P33. Terminal portions 21 and 16 and electrode pads 21a and 16a are disposed at node portions P11 and P12. In the fourth embodiment, connection and fixation are performed using conductive adhesive 31 and adhesive 32, as in FIG.

[0124] In this embodiment, too, the electrode pads 21a, 16a are connected to each other at the vibration node portions P11, P12, so the amount of vibration displacement at the positions where the electrode pads 16a, 21a are arranged is small. This reduces the effect of vibration on the connection between the electrode pads 16a, 21a, so the reliability of the electrical connection between the electrode pads 16a, 21a can be maintained. Furthermore, because the electrode pads 16a, 21a are connected to each other, the support substrate 2 and the fixing portion 15 can be electrically connected without using a separate wiring means such as wire bonding. This allows the overall configuration of the vibration module 3 to be miniaturized.

[0125] In this embodiment, the conductive member 33 shown in FIG. 10A may be used instead of the conductive adhesive 31, and the conductive adhesive 34 shown in FIG. 10B may be used instead of the conductive adhesive 31 and the adhesive 32.

[0126] <Other Modifications> The configuration examples of the present invention are not limited to the above-described embodiment and modifications, and various modifications are possible.

[0127] In the above embodiment and modified example, the electrode pads 21 a, 16 a are arranged only at the node portions P11 and P12, but this is not limiting, and the electrode pads 21 a, 16 a may be arranged at the node portions P13 to P16. In this case as well, since the amount of vibration displacement is small at the node portions P13 to P16, the reliability of the electrical connection of the electrode pads 21 a, 16 a arranged at the node portions P13 to P16 can be maintained.

[0128] In the first modification of the first embodiment, the electrode pads 23a, 17a are arranged on both sides of the movable part 11 in the Y-axis direction, but they may be arranged on only one side of the movable part 11 in the Y-axis direction. For example, the terminal parts 23, 17 and the electrode pads 23a, 17a arranged at the vibration antinode parts P22, P32 may be omitted from the configuration shown in Fig. 13. In this case as well, by arranging the conductive adhesive 31 or conductive member 33 at the node parts P11, P12 and the antinode parts P21, P31, it becomes easy to attach the support substrate 2 and the fixed part 15 parallel to each other.

[0129] 9 and 10A is disposed over the entire upper surface of the fixing portion 15 excluding the area where the conductive adhesive 31 or the conductive member 33 is disposed, but this is not limiting and the adhesive 32 may be disposed over only a portion of the upper surface of the fixing portion 15. However, by disposing the adhesive 32 at least around the conductive adhesive 31 or the conductive member 33, fatigue of the conductive adhesive 31 or the conductive member 33 due to vibration can be suppressed.

[0130] The conductive adhesive 34 shown in Figure 10B is arranged over the entire area of ​​the upper surface of the fixing portion 15, but this is not limited to this, and it may be arranged over only a portion of the upper surface of the fixing portion 15 as long as it is arranged at least at the positions of the electrode pads 16a and 21a.

[0131] In the above embodiment and modified examples, the shapes of the terminals 16 and 21 are not limited to those of the above embodiment and modified examples, as long as adjacent terminals 16 and 21 do not overlap each other. Furthermore, the arrangement of the electrode pads in the terminals 16 and 21 and the arrangement of the electrode pads in the terminals 17 and 23 are not limited to those described above. Furthermore, the positions of the three types of electrode pads 16a in the terminal 16 connected to the upper electrode layer of the piezoelectric body 12b, the upper electrode layer of the piezoelectric body 12c, and the lower electrode layers of the piezoelectric bodies 12b and 12c, respectively, may be interchanged. Furthermore, the arrangement of the wiring 16b connecting the terminal 16 and the piezoelectric bodies 12b and 12c is not limited to those of the above embodiment and modified examples. However, it is preferable that the wiring 16b be arranged so as to connect the mutually connected terminals 16 and the piezoelectric bodies 12b and 12c via the shortest route.

[0132] In the above embodiment and modified examples, the shape of the movable part 11 is circular, but the shape of the movable part 11 may be other shapes such as square. The shape of the driving element 1 in a plan view and the dimensions of each part of the driving element 1 can also be changed as appropriate.

[0133] Furthermore, the driving element 1 may be used as an element other than an optical deflector. When the driving element 1 is used as an element other than an optical deflector, the movable part 11 does not need to be provided with the reflective surface 11a, and a member other than the reflective surface 11a may be provided.

[0134] In addition, the embodiments of the present invention can be modified in various ways as appropriate within the scope of the technical ideas set forth in the claims.

[0135] In the above embodiment, terms indicating directions such as "bottom surface," "top surface," and "above" indicate relative directions determined only by the relative positional relationship of components of the optical deflector such as the drive element and the support substrate, and do not indicate absolute directions such as the vertical direction.

[0136] (Additional Notes) The above description of the embodiments discloses the following techniques.

[0137] (Technology 1) A vibration module comprising: a drive element; and a support substrate that supports the drive element, wherein the drive element comprises: a movable part; a drive part that rotates the movable part about a rotation axis; a fixed part that supports the movable part and the drive part and is fixed to the support substrate; and a first electrode pad that is installed on an upper surface of the fixed part and connected to the drive part by a wiring pattern, wherein a second electrode pad is arranged on a lower surface of the support substrate at a position opposite to the first electrode pad, and the first electrode pad and the second electrode pad are connected to each other at a portion that corresponds to a node of vibration that occurs in the fixed part when the movable part vibrates.

[0138] According to this technology, the first electrode pad and the second electrode pad are connected to each other at the vibration node, thereby reducing the vibration displacement at the positions where the first electrode pad and the second electrode pad are arranged. This reduces the influence of vibration on the connection between the first electrode pad and the second electrode pad, thereby maintaining the reliability of the electrical connection between the first electrode pad and the second electrode pad. Furthermore, because the first electrode pad and the second electrode pad are connected to each other, the support substrate and the fixing portion can be electrically connected without using a separate wiring means such as wire bonding. This allows the overall configuration of the vibration module to be miniaturized.

[0139] (Technology 2) In the vibration module described in Technology 1, the first electrode pad and the second electrode pad are electrically connected to each other by a conductive adhesive in which a conductive filler is mixed into a resin material.

[0140] This technology allows the elastic modulus of the conductive adhesive to be set lower than that of common conductive metals (such as silver or copper). As a result, even if vibrations generated in the fixing part are transmitted to the conductive adhesive, the low elastic modulus of the conductive adhesive makes it difficult for stress to concentrate on the conductive adhesive. This maintains the reliability of the electrical connection between the first electrode pad and the second electrode pad.

[0141] (Technology 3) A vibration module according to Technology 2, characterized in that the area in which the conductive adhesive is disposed is an area including, in a planar view, an area where the first electrode pad and the second electrode pad overlap and the vicinity thereof, and at least around the periphery of the area in which the conductive adhesive is disposed, the fixing portion and the support substrate are fixed together by an adhesive having a higher elastic modulus than the conductive adhesive.

[0142] According to this technology, the periphery of the conductive adhesive is fixed with an adhesive having a high elastic modulus, thereby suppressing vibration displacement around the conductive adhesive. This prevents fatigue of the conductive adhesive connecting the first electrode pad and the second electrode pad due to vibration, thereby maintaining the reliability of the electrical connection between the first electrode pad and the second electrode pad.

[0143] (Technology 4) A vibration module according to Technology 2 or 3, characterized in that a third electrode pad and a fourth electrode pad facing each other are respectively arranged on the upper surface of the fixing part and the lower surface of the support substrate at positions other than the positions of the first electrode pad and the second electrode pad, and the third electrode pad and the fourth electrode pad are connected to each other by the conductive adhesive.

[0144] According to this technology, conductive adhesive is applied not only to the positions of the first and second electrode pads but also to the positions of the third and fourth electrode pads. This allows the support substrate and the drive element to be accurately superimposed after the conductive adhesive is applied during assembly. Furthermore, the connection of the third and fourth electrode pads and the connection of the first and second electrode pads can be performed by the same process of applying conductive adhesive between the opposing electrode pads.

[0145] (Technology 5) A vibration module according to Technology 4, characterized in that the first electrode pad and the second electrode pad are arranged at the node portion near the rotation axis in a planar view, and the third electrode pad and the fourth electrode pad that form a pair are arranged at two positions symmetrical with respect to the rotation axis in a planar view.

[0146] According to this technique, when the lower surface of the support substrate and the upper surface of the fixing portion are bonded together using the conductive adhesive, the gap between the support substrate and the fixing portion is maintained by the conductive adhesive present in each of the two sets of third and fourth electrode pads, making it possible to easily bond the support substrate and the fixing portion so that they are parallel to each other.

[0147] (Technology 6) A vibration module described in any one of technologies 1 to 5, characterized in that in an area including at least the areas of the first electrode pad and the second electrode pad, the first electrode pad and the second electrode pad are electrically connected by adhering the fixing portion and the support substrate with a paste-like or film-like conductive adhesive having a conductive filler mixed into a resin material.

[0148] According to this technology, the electrical connection between the first electrode pad and the second electrode pad and the fixing of the fixing portion and the support substrate can be achieved by the conductive adhesive without using separate members. In addition, since the conductive adhesive can be used for both the electrical connection between the first electrode pad and the second electrode pad and the fixing of the fixing portion and the support substrate, the manufacturing process can be simplified.

[0149] (Technology 7) A vibration module described in any one of technologies 1 to 6, characterized in that the drive element further includes another drive unit that rotates the movable part about the rotation axis, and the drive unit and the other vibration unit are arranged in opposite directions to each other along the rotation axis.

[0150] This technology allows the moving part to be driven stably with a larger torque.

[0151] (Technology 8) The vibration module according to any one of technologies 1 to 7, wherein the driving unit is a tuning fork vibrator.

[0152] According to this technique, the movable part can be smoothly and repeatedly rotated (resonantly driven) about the rotation axis.

[0153] (Technology 9) In the vibration module described in Technology 8, the vibration module is characterized in that the vibration module is configured so that the movable part resonates at a target frequency when driven in an antiphase mode in which the movable part and the connecting part rotate in opposite directions to each other.

[0154] In the in-phase mode, in which the movable part and the connecting part rotate in the same direction, the rotation directions of the movable part and the connecting part are the same, so the rotation moment transmitted to the fixed part by the movable part and the connecting part is large, resulting in a large displacement of the fixed part. In contrast, in the anti-phase mode, in which the movable part and the connecting part rotate in opposite directions as described above, the rotation moment generated in the movable part and the rotation moment generated in the connecting part cancel each other out, so the rotation moment transmitted to the fixed part by the movable part and the connecting part is suppressed. As a result, the displacement of the entire fixed part is smaller in the anti-phase mode than in the in-phase mode, resulting in increased reliability of the electrical connection between the paired first and second electrode pads.

[0155] (Technology 10) An optical deflector comprising: the vibration module according to any one of technologies 1 to 9; and a reflecting surface disposed on the movable part.

[0156] Since this technology includes the vibration module, it is possible to stably deflect and scan light incident on the reflective surface at a predetermined deflection angle while increasing the reliability of the electrical connection between the first electrode pad and the second electrode pad.

[0157] REFERENCE SIGNS LIST 1 Drive element 2 Support substrate 3 Vibration module 3a Optical deflector 11 Movable portion 11a Reflection surface 12 Drive portion (tuning fork vibrator) 15 Fixed portion 16a Electrode pad (first electrode pad) 16b Wiring (wiring pattern) 17a Electrode pad (third electrode pad) 21a Electrode pad (second electrode pad) 23a Electrode pad (fourth electrode pad) 31 Conductive adhesive 32 Adhesive 34 Conductive adhesive P11 to P16 Parts (parts corresponding to vibration nodes) R0 Rotation axis

Claims

1. A vibration module comprising a driving element and a support substrate for supporting the driving element, wherein the driving element includes a movable part, a driving part for rotating the movable part about a rotation axis, a fixing part for supporting the movable part and the driving part and being fixed to the support substrate, and a first electrode pad disposed on an upper surface of the fixing part and connected to the driving part by a wiring pattern; a second electrode pad is disposed on a lower surface of the support substrate at a position facing the first electrode pad; and the first electrode pad and the second electrode pad are connected to each other at a node portion of vibrations generated in the fixing part among the fixing parts during vibration of the movable part.

2. The vibration module according to claim 1, wherein the first electrode pad and the second electrode pad are electrically connected to each other by a conductive adhesive in which a conductive filler is mixed into a resin material.

3. The vibration module according to claim 2, wherein a region where the conductive adhesive is disposed is a region including a portion where the first electrode pad and the second electrode pad overlap and an area in the vicinity thereof in a plan view, and at least around the region where the conductive adhesive is disposed, the fixing part and the support substrate are fixed by an adhesive having a higher elastic modulus than that of the conductive adhesive.

4. The vibration module according to claim 2, wherein a third electrode pad and a fourth electrode pad facing each other are respectively disposed at positions on the upper surface of the fixing part and the lower surface of the support substrate other than the arrangement positions of the first electrode pad and the second electrode pad, and the third electrode pad and the fourth electrode pad are connected to each other by the conductive adhesive.

5. The vibration module according to claim 4, wherein the first electrode pad and the second electrode pad are disposed at the node portion near the rotation axis in a plan view, and the third electrode pad and the fourth electrode pad that form a pair are respectively disposed at two positions symmetric with respect to the rotation axis in a plan view.

6. In the vibration module according to claim 1, in a region including at least the regions of the first electrode pad and the second electrode pad, the fixing portion and the support substrate are adhered by a paste-like or film-like conductive adhesive in which a conductive filler is mixed into a resin material, whereby the first electrode pad and the second electrode pad are electrically connected. A vibration module characterized by this.

7. In the vibration module according to claim 1, the driving element further includes another driving unit that rotates the movable unit about the rotation axis, and the driving unit and the another driving unit are arranged in opposite directions along the rotation axis. A vibration module characterized by this.

8. In the vibration module according to claim 1, the driving unit is a tuning fork type vibrator. A vibration module characterized by this.

9. In the vibration module according to claim 8, the vibration module is configured such that the movable unit resonates at a target frequency by driving in an anti-phase mode in which the movable unit and the connecting unit rotate in opposite directions. A vibration module characterized by this.

10. An optical deflector comprising the vibration module according to any one of claims 1 to 9 and a reflecting surface disposed on the movable unit. A optical deflector characterized by this.

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