JP2012247523A - Vibration device and optical scanner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vibration device which prevents a lead wire breakage due to a load applied to a joint part between the lead wire and an electrode resulting from the expansion and contraction of a piezoelectric element under voltage application, and an optical scanner.SOLUTION: A vibration device having a piezoelectric element which expands or contracts under voltage application, a first electrode disposed at the piezoelectric element, a second electrode disposed at a body separated from the piezoelectric element, to which voltage is applied from a power source, and a lead wire which electrically connects the first electrode and the second electrode comprises a neck part which is disposed at least at one of a first connection part for connecting the lead wire and the first electrode and a second connection part for connecting the lead wire and the second electrode, with the lead wire having thickness increasing toward the connection part, and a reinforcing member disposed at the boundary of the neck part which displaces in response to the expansion or contraction of the piezoelectric element.

Description

  The present invention relates to a vibration device in which a piezoelectric element expands and contracts when electric power is applied via a wire bonded to an electrode.

  Conventionally, there is a wire bonding method as a method of electrically connecting a plurality of electronic components arranged on a substrate. The wire bonding method is a method in which both ends of a wire of a conducting wire are melted, joined to an electrode and a conductor formed on a substrate, and they are electrically connected. For example, Patent Literature 1 describes a wire bonding method in which an electrode of a semiconductor chip formed on a ceramic substrate and a wiring electrode are electrically connected by a wire. Specifically, the wire is bonded to the electrode of the semiconductor chip in the primary bonding process, and the wire is bonded to the wiring electrode in the secondary bonding process. As a result, the semiconductor chip and the wiring electrode are electrically connected. When electrical connection is made by the wire bonding method, a ball reservoir is formed by melting at the tip of the wire. Then, a ball reservoir of molten wire is joined to each electrode. The ball reservoir of the wire is bonded so that the diameter of the ball pool is larger than that of the other portion of the wire.

  Such a wire bonding method is used when an electrode to be bonded is small and accuracy is required for bonding. For example, when an electrical connection is made to a small vibration device, the wire is bonded to an electrode provided on a piezoelectric element of the vibration device and an electrode connected to a power source by a wire bonding method. The piezoelectric element expands and contracts when a voltage is applied via a wire bonded to an electrode connected to a power source.

JP 2004-147193 A

  Electric power is supplied to the electrodes provided in the piezoelectric element of the vibration device via a wire bonded by a wire bonding method. The wire bonded to the electrode of the piezoelectric element is bonded so as to be thick at the bonded portion. When a voltage is applied to the electrode provided on the piezoelectric element, the piezoelectric element expands and contracts. Since the electrode vibrates due to expansion and contraction of the piezoelectric element, the wire bonded to the electrode may be subjected to a large load on the bonded portion where the thickness changes, and may be disconnected. The vibration device in which the wire is disconnected becomes a defective product and cannot be used. Moreover, when reusing the vibration device in which the wire is disconnected, electrical connection is required again.

  The present invention has been made to solve the above-described problems. The present invention relates to a vibration device and an optical device in which a voltage is applied and a piezoelectric element expands and contracts, whereby a load is applied to a joint portion between a lead wire that supplies power to the piezoelectric element and an electrode, and the lead wire is not cut. An object is to provide a scanner.

  In order to achieve this object, the vibration device according to claim 1 is provided with a piezoelectric element that expands and contracts when a voltage is applied thereto, a first electrode provided on the piezoelectric element, and a piezoelectric element that is provided separately from the piezoelectric element. A vibration device comprising: a second electrode to which a voltage is applied; and a conductive wire that electrically connects the first electrode and the second electrode, wherein the connection portion between the conductive wire and the first electrode A neck portion that is provided on at least one of the first connection portion and the second connection portion that is a connection portion between the conductive wire and the second electrode, and the thickness of the conductive wire increases toward the connection portion. And a reinforcing material provided at a boundary of the neck portion that is displaced along with expansion and contraction by the piezoelectric element.

  An optical scanner comprising the vibration device according to claim 2 includes a mirror that reflects incident light, and a support part on which the piezoelectric element is placed and a support that is adjacent to and supported by the placement part. And the substrate, the substrate vibrates about a line connecting the support portion and the mounting portion as a central axis when the piezoelectric element expands and contracts, and scans the mirror. The reinforcing material is provided on a line connecting the first joint portion and the second joint portion of the neck portion in the conductive wire.

  An optical scanner comprising the vibration device according to claim 3, wherein the piezoelectric element is in a direction parallel to a surface of the substrate on which the mirror is driven by extending and contracting, and in a direction intersecting the central axis direction. The reinforcing material is further provided on a line parallel to the central axis of the neck portion in the conductive wire.

  The optical scanner including the vibration device according to claim 4 is characterized in that the reinforcing material is provided so as to cover the boundary of the neck portion of the conducting wire and the first electrode.

  An optical scanner including the vibration device according to claim 5 is characterized in that a resin material having an elastic modulus in a range of 1 GPa to 10 GPa is used as the reinforcing member.

  In the vibration device according to claim 1, a reinforcing member is provided in a neck portion whose thickness increases toward a connection portion in a conductive wire that electrically connects two electrodes. The vibration device has a shape in which, when the first electrode and the second electrode are electrically connected, the conductive wire becomes thicker toward the first connection portion or the second connection portion. In such a vibration device, by providing the reinforcing member at the neck portion where the thickness of the conducting wire changes, the load applied to the conducting wire is dispersed by the expansion and contraction of the piezoelectric element, and the neck portion can be prevented from being cut.

  In the optical scanner including the vibration device according to claim 2, the reinforcing material is provided on a line connecting the first connection portion and the second connection portion of the neck portion in the conductive wire. In an optical scanner, when a piezoelectric element to which a voltage is applied expands and contracts and the substrate vibrates, a load caused by the vibration of the substrate is applied to the conducting wire. The lead wire of the optical scanner is wired with a predetermined length in which the first connection portion and the second connection portion are fixed. Therefore, when the substrate vibrates, a large load is applied in the wiring direction. Therefore, a reinforcing material is provided in a direction along the wiring direction of the neck portion where the thickness of the conducting wire is increased, and the wiring direction of the neck portion to which a large load is applied is reinforced. With this configuration, even when a load is applied to the conducting wire due to the vibration of the substrate, the neck portion can be prevented from being cut by the load applied in the wiring direction.

  The optical scanner including the vibration device according to claim 3 is further provided with a reinforcing material on a line parallel to the central axis of the substrate in the neck portion of the conducting wire. As the piezoelectric element expands and contracts, the substrate vibrates around the central axis, and scans the mirror. At this time, a load is applied to the conducting wire due to the vibration of the substrate. With the configuration in which the reinforcing member is provided in the neck portion, it is possible to prevent the neck portion from being cut by a load applied to the conductive wire due to the vibration of the substrate.

  The optical scanner including the vibration device according to claim 4 is provided with a reinforcing material so as to cover the boundary of the neck portion and the first electrode. When the piezoelectric element expands and contracts, a load is also applied to the connection portion between the conducting wire and the first electrode provided on the piezoelectric element. By providing the reinforcing material so as to cover the boundary of the neck portion and the first electrode, it is possible to prevent the conductive wire from being separated from the connected first electrode.

  In the optical scanner including the vibration device according to claim 5, a resin material having an elastic modulus in the range of 1 GPa to 10 GPa is used as the reinforcing material. By using a reinforcing material having an elastic modulus within a predetermined range, the neck portion can be reliably reinforced, and the load applied to the conducting wire can be suppressed by the expansion and contraction of the piezoelectric element, thereby preventing the neck portion from being damaged.

1 is an overall perspective view of an optical scanner 1 in the present embodiment. It is explanatory drawing which shows each process of the bonding method of the optical scanner. 3 is an enlarged cross-sectional view of a bonding portion between a bonding wire 50 of the optical scanner 1 and an electrode pad 22a of the piezoelectric element 22. FIG. 3 is an enlarged view showing a stress distribution in a neck portion 50a of a bonding wire 50 of the optical scanner 1. FIG. FIG. 4 is an enlarged cross-sectional view of a joint portion between a wire 50 provided with a reinforcing member 60 of the optical scanner 1, an electrode 35, and an electrode pad 22a. 4 is an enlarged view showing a stress distribution in a neck portion 50a of a wire 50 provided with a reinforcing member 60 of the optical scanner 1. FIG. FIG. 6 is a diagram showing a correlation between stress applied to the neck portion 50a of the wire 50 of the optical scanner 1 and the properties of the reinforcing material 60.

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

  The structure of the optical scanner 1 according to the embodiment of the present invention will be described with reference to FIG. FIG. 1 is a perspective view showing the entire optical scanner 1. The optical scanner 1 includes a scanning unit 20 and a fixed base 30. The fixed base 30 fixes the scanning unit 20. In the optical scanner 1 of the present embodiment, the vertical direction, the horizontal direction, and the front-rear direction are set as shown in FIG.

  The scanning unit 20 shown in FIG. 1 has a thin plate-like drive substrate 21 whose outer shape is a quadrangular shape. The drive substrate 21 is formed using a conductive material having elasticity, specifically, a metal material such as stainless steel such as SUS304 or SUS430, titanium, or iron. The drive substrate 21 includes a fixed portion 21a fixed to the fixed base 30 on the rear side and a substantially square-shaped scanning portion 21b on the front side. The fixed part 21a and the scanning part 21b are joined at the center of the opposite sides via the elastic part 21c.

  The piezoelectric element 22 is placed on the upper surface of the scanning unit 21b. The piezoelectric element 22 has a configuration in which a piezoelectric body is sandwiched between two electrodes. An electrode pad 22 a is disposed on the upper surface of the piezoelectric element 22 placed on the scanning unit 21 b of the drive substrate 21. A rod-like beam 23 extending in the left-right direction is provided in front of the scanning unit 21b, and a round mirror 24 is provided in the center of the beam 23 in the left-right direction. The elastic portion 21c, the beam 23, and the mirror 24 of the drive substrate 21 are formed by etching or pressing a rectangular metal plate.

  Next, the structure of the fixed base 30 will be described with reference to FIG. The fixed base 30 shown in FIG. 1 has a rectangular shape that is slightly larger than the drive substrate 21 and includes a flat bottom plate portion 31 formed using a material similar to that of the drive substrate 21. Further, the fixed base 30 includes a raised portion 32 whose one side is raised upward from the flat plate of the bottom plate portion 31. The fixed portion 21 a of the drive substrate 21 is fixed to the raised portion 32.

  The scanning unit 20 is fixed by attaching the lower surface side of the fixed portion 21 a of the drive substrate 21 to the upper surface side of the raised portion 32 of the fixed base 30. The drive substrate 21 and the raised portion 32 are attached by, for example, a laser welding method. When the fixed portion 21 a is attached to the raised portion 32, the scanning portion 21 b of the driving substrate 21 is arranged in a state where a space is provided between the bottom portion 31.

  In addition, an electrode substrate 34 is disposed on the fixed base 30 in a region adjacent to the raised portion 32. Further, an electrode 35 is disposed on the upper surface of the electrode substrate 34. In the present embodiment, as shown in FIG. 1, the electrode 35 is disposed on the right side of the piezoelectric element 22 in parallel with the position where the piezoelectric element 22 of the driving substrate 21 is disposed. The electrode 35 is connected to an AC power supply (not shown) via a wiring (not shown) formed on the electrode substrate 34.

  The piezoelectric element 22 and the electrode 35 are joined by a wire 50 and electrically connected as shown in FIG. Specifically, the wire 50 extends to the electrode 35 provided on the right side of the drive substrate 21 so as to extend rightward from the electrode pad 22a of the piezoelectric element 22 placed on the drive substrate 21 shown in FIG. Be joined. The optical scanner 1 can be driven when the wire 50 is bonded. In the optical scanner 1, electric power is supplied to the electrode 35 from an AC power supply (not shown) via a wiring (not shown) of the electrode substrate 34 of the fixed base 30. The electric power supplied to the electrode 35 is supplied to the electrode pad 22a through the wire 50 and causes the piezoelectric element 22 to expand and contract.

  The wire 50 is bonded by a wire bonding method using a conductive wire such as gold. In the present embodiment, a conductive wire having a diameter of 37 [μm] is used for the wire 50. At this time, the wire 50 is bonded by using heat, weight, and ultrasonic waves to the electrode pad 22a of the piezoelectric element 22 by a bonding apparatus (not shown) and using pressure, friction, and heat. A wire bonding method for bonding the wire 50 to the electrode pad 22a and the electrode 35 of the optical scanner 1 will be described in detail with reference to FIG. FIG. 2 is a state transition diagram illustrating a wire bonding method performed on the optical scanner 1 in the present embodiment. FIG. 2 is a view of the wire 50 as viewed from the side. In the present embodiment, first, in the optical scanner 1, a primary bonding process is performed in which the wire 50 is bonded to the electrode pad 22 a of the piezoelectric element 22. The wire 50 that has been subjected to the primary bonding process on the electrode pad 22 a is stretched and a secondary bonding process is performed in which the wire 50 is bonded to the electrode 35 of the fixed base 30.

  First, in the primary bonding process, when the wire 50 is bonded to the electrode pad 22a of the piezoelectric element 22, heat is applied to the tip of the wire 50. The tip of the wire 50 is heated to form a molten ball reservoir (FIG. 2A). The ball reservoir has a spherical shape whose diameter is larger than the thickness of other positions of the wire 50.

  The ball reservoir of the wire 50 is pressure-bonded to the upper surface of the electrode pad 22a of the piezoelectric element 22 by heat, weight, and ultrasonic waves. Then, the ball reservoir at the tip of the wire 50 is joined to the electrode pad 22a (FIG. 2B). Thereby, the primary bonding process which joins the wire 50 with the electrode pad 22a of the piezoelectric element 22 of the scanning unit 20 is completed. In the primary bonding step, a ball reservoir having a diameter larger than the thickness of the wire 50 is bonded to the electrode pad 22a. As a result, a stepped neck portion 50a is formed at the joint portion of the wire 50 with the electrode pad 22a. The diameter of the neck 50a of the wire 50 is larger than the diameter of the other position where the ball reservoir of the wire 50 is not formed.

  After the tip of the wire 50 is bonded to the electrode pad 22a by the primary bonding process, the secondary bonding process is performed on the electrode 35 of the fixed base 30. When the secondary bonding process is performed, the wire 50 bonded to the electrode pad 22a is extended from the electrode pad 22a to the electrode 35 of the fixed base 30. Then, the stretched wire 50 is joined to the electrode 35 (FIG. 2C). In the secondary bonding step, when the wire 50 is bonded to the electrode 35, heat is applied to the portion of the wire 50 to be bonded to the electrode 35 in the same manner as in the primary bonding step. The wire 50 melted by application of heat is joined to the electrode 35 by heat, load, and ultrasonic waves. At this time, the joint portion of the wire 50 with the electrode 35 has a stepped shape having a larger diameter than other portions where the heat of the wire 50 is not applied, similarly to the joint portion with the electrode pad 22a in the primary bonding step. Thereby, the secondary bonding process which joins the wire 50 to the electrode 35 is completed (FIG.2 (d)).

  The wire 50 is bonded to the electrode pad 22a and the electrode 35 of the piezoelectric element 22 through the steps of primary bonding and secondary bonding, so that the piezoelectric element 22 of the optical scanner 1 is connected to an AC power supply (not shown) and an electric power. Connected.

  When each step of the wire bonding method described above is performed, the electrode pad 22a of the piezoelectric element 22 and the electrode 35 are connected so that the wire 50 extends in the left-right direction. The piezoelectric element 22 expands and contracts when electric power is supplied from the AC power source through the electrode 35 and the wire 50. When the piezoelectric element 22 expands and contracts, the drive substrate 21 on which the piezoelectric element 22 is placed vibrates in the vertical direction about the central axis X extending in the front-rear direction of FIG. As shown in FIG. 1, the fixed portion 21 a of the drive substrate 21 is provided on the raised portion 32 of the fixed base 30 so that the central axis X is the center in the left-right direction of the drive substrate 21.

  When a voltage is applied to the piezoelectric element 22 and the piezoelectric element 22 expands and contracts, vibration is transmitted to the drive substrate 21 and the entire drive substrate 21 vibrates. When the drive substrate 21 vibrates, the vibration is transmitted to the beam 23. The beam 23 converts the vibration into torsional driving, and drives the mirror 24 torsionally. The mirror 24 reflects and scans laser light incident on the surface of the mirror 24 from a laser light source (not shown) according to the twist direction, thereby forming a desired image.

  When electric power is supplied to the electrode pad 22a through the wire 50, the piezoelectric element 22 expands and contracts in the left-right direction. When the expansion / contraction of the piezoelectric element 22 in the left-right direction is transmitted to the drive substrate 21, the drive substrate 21 vibrates in the vertical direction. On the other hand, in the optical scanner 1, the wire 50 is arranged to extend in the left-right direction. That is, the drive substrate 21 vibrates in the up and down direction intersecting the left and right direction in which the wires 50 are arranged. When the drive substrate 21 vibrates, the electrode pad 22a at the position where the wire 50 is bonded also moves, so that the state in which the wire 50 bonded to the piezoelectric element 22 and the electrode 35 is arranged changes. As a result, a load is generated at the joint between the electrode pad 22a of the wire 50 and the electrode 35. In particular, the neck portion 50a at the joining portion of the wire 50 has a stepped shape having a diameter and a diameter different from each other, so that the wire 50 is easily cut when a load is applied.

  In this regard, an optical scanner 1 in which the scanning unit 20 and the fixed base 30 are electrically connected by a wire 50 will be described with reference to FIGS. 3A and 3B. 3A is a cross-sectional view of the optical scanner 1 shown in FIG. 1 taken along line AA and viewed from the direction of the arrows. FIG. 3B is a diagram illustrating a load stress generated in the wire 50 of the optical scanner 1 occupying FIG. 3A. 3A and 3B are views showing the optical scanner 1 in a state in which the reinforcing member 60 is not provided at the connection portion of the wire 50 of the scanning unit 20 and the fixed base 30, unlike FIGS. 4A and 4B described later. It is.

  First, the optical scanner 1 in a state where the reinforcing material 60 is not provided on the wire 50 will be described with reference to FIGS. 3A and 3B. FIG. 3A is a cross-sectional view taken along the line AA of the optical scanner 1 in a state where the reinforcing member 60 is not provided at the connection portion of the wire 50 to the scanning unit 20 and the fixed base 30. FIG. 3B is an enlarged view showing a distribution of load stress generated in the neck portion 50a of the wire 50 shown in FIG. 3A when the optical scanner 1 shown in FIG. 3A is driven. The wire 50 shown in FIG. 3B is not provided with the reinforcing member 60 as shown in FIG. 4A described later. The wire 50 of the optical scanner 1 is configured such that a large load is applied when electric power is supplied to the piezoelectric element 22 and the drive substrate 21 vibrates.

  In the optical scanner 1 of this embodiment, when electric power is supplied from the wire 50, the piezoelectric element 22 expands and contracts. At this time, the piezoelectric element 22 greatly expands and contracts in the left-right direction. Thereby, the scanning part 21b of the drive substrate 21 is twisted in the left-right direction and moved up and down. One end of the wire 50 is bonded to the electrode pad 22a of the piezoelectric element 22 placed on the upper surface of the scanning unit 21b of the drive substrate 21, and the other end is bonded to the electrode 35 of the fixed base 30 and fixed. In the state, it is wired in the left-right direction. When the piezoelectric element 22 expands and contracts, the drive substrate 21 vibrates, so that the position of the joint point between the wire 50 and the piezoelectric element 22 changes. On the other hand, the position of the junction point of the wire 50 with the electrode 35 does not change. Thus, when the piezoelectric element 22 expands and contracts, only the drive substrate 21 vibrates, so that the arrangement state between the electrode 35 of the wire 50 and the piezoelectric element 22 changes. In the wire 50, a force for releasing the load is generated when the drive substrate 21 vibrates in the left-right direction which is the wiring direction.

  In particular, as shown in FIG. 3A, the wire 50 has a stepped shape at the bonding portion between the piezoelectric element 22 and the electrode pad 22 a and the bonding portion with the electrode 35. Therefore, when the drive substrate 21 vibrates, a load is applied to the neck portion 50a of the joint portion of the wire 50. When the drive substrate 21 vibrates, a large load is applied to the neck portion 50a at the joint portion of the wire 50 with the electrode pad 22a of the piezoelectric element 22 particularly in the left-right direction as shown in FIG. 3B. In FIG. 3B, the stress intensity is used as an index indicating the strength of the load stress generated in the neck portion 50a of the wire 50 when the drive substrate 21 vibrates with the central axis X shown in FIG. Are displayed in three stages. Specifically, in the cross section of the neck portion 50a of the wire 50, a region where the load stress is small is indicated by a vertical line, a region where the load stress is medium is indicated by a horizontal line, and a region where the load stress is high is indicated by a vertical and horizontal line. In FIG. 3B, a region where the load stress is small is distributed in a region 30% from the center centering on the front-rear direction of the wire 50 parallel to the central axis X. Moreover, the area | region where load stress is medium is distributed from the area | region where the load stress of the wire 50 is small to 40% outside. Furthermore, a region where the load stress is large is distributed in 30% of the outermost periphery outside the region where the load stress is medium.

  Therefore, in the present embodiment, the reinforcing member 60 is provided at the joint portion of the wire 50 of the optical scanner 1. In the optical scanner 1, the reinforcing member 60 is provided at the joint portion of the wire 50 in order to suppress the load applied to the wire 50 as shown in FIG. 3B when the drive substrate 21 vibrates. Providing the reinforcing member 60 reduces the load applied to the joint portion of the wire 50 due to the vibration of the drive substrate 21 of the scanning unit 20 of the optical scanner 1 and prevents the wire 50 from being cut.

  Thus, the structure which provided the reinforcing material 60 in the junction part of the wire 50 in the optical scanner 1 is demonstrated using FIG. 4A and FIG. 4B. FIG. 4A is a cross-sectional view showing the optical scanner 1 of the present embodiment in which a reinforcing material 60 is provided at a joint portion between the scanning unit 20 and the fixed base 30 of the wire 50. 4B is an enlarged view showing a distribution of load stress applied to the neck portion 50a of the wire 50 when the optical scanner 1 shown in FIG. 4A is driven. 4A and 4B are different from FIGS. 3A and 3B in that a reinforcing member 60 is provided at a joint portion of the wire 50 in the scanning unit 20 and the fixed base 30 of the optical scanner 1.

  In the present embodiment, as shown in FIG. 4A, the wire 50 of the optical scanner 1 is formed in a stepped shape at the junction with the electrode pad 22a and the junction with the electrode 35. Therefore, as shown in FIG. 4A, the reinforcing member 60 is provided so as to cover the periphery of the neck portion 50a of the wire 50 and the periphery of the joint portion between the electrode pad 22a and the electrode 35.

  In the optical scanner 1 of the present embodiment, a reinforcing member 60 is provided at the joint portion of the wire 50 as shown in FIG. 4A. In FIG. 4B, the intensity of the load stress generated in the neck portion 50a of the wire 50 when the drive substrate 21 vibrates is displayed in three stages with the central axis X shown in FIG. To do. Specifically, a region where the stress is low is indicated by a vertical line, a region where the stress is moderate is indicated by a horizontal line, and a region where the stress is high is indicated by a vertical and horizontal line. In FIG. 4B, centering on the front-rear direction of the wire 50 parallel to the central axis X, 70% from the center is an area where the stress is low, 20% outside the area where the stress is low is an area where the stress is medium, and the outermost 1 The distribution of the area where the stress is relatively large. As shown in FIG. 4B, by providing the reinforcing member 60, it is possible to reduce the load in the left-right direction at the neck portion 50a of the wire 50 due to the expansion and contraction of the piezoelectric element 22.

  Comparing the load distribution diagrams of FIG. 3B and FIG. 4B, the neck portion 50a provided with the reinforcing member 60 shown in FIG. 4B has a smaller load stress than the neck portion 50a without the reinforcing member 60 shown in FIG. 3B. The area is large and the area where the load stress is large is small. As a result, when the reinforcing material 60 is provided around the neck portion 50a, the load is reduced and the wire 50 is less likely to be cut than the neck portion 50a where the reinforcing material 60 is not provided.

  In particular, by providing the reinforcing member 60 in the left-right direction of the neck portion 50 a of the wire 50, it is possible to prevent the neck portion 50 a from being cut due to the load of the wire 50 due to the expansion and contraction of the piezoelectric element 22. Further, by providing the reinforcing member 60 not only in the left-right direction of the neck portion 50a of the wire 50 but also in the periphery, the step-shaped neck portion 50a that is easily cut by being loaded by the vibration of the drive substrate 21 is reinforced. The possibility that the neck portion 50a is cut can be prevented.

  Further, it is conceivable that a large load is generated on the bonding surface of the wire 50 with the electrode pad 22a due to the expansion and contraction of the piezoelectric element 22 in the left-right direction. As a result, the wire 50 may be peeled off from the electrode pad 22a. Therefore, by providing the reinforcing material 60 around the joint portion with the drive substrate 21, the peeling of the wire 50 can be prevented. In the present embodiment, by providing the reinforcing member 60 in the left-right direction of the wire 50 joined to the electrode pad 22a, damage due to the load applied to the wire 50 due to expansion / contraction of the piezoelectric element 22 can be prevented. Moreover, the durability of the optical scanner 1 is improved by providing the reinforcing member 60.

  Further, in the optical scanner 1, the drive substrate 21 vibrates in the vertical direction according to the expansion and contraction of the piezoelectric element 22 to drive the mirror 24. When the drive substrate 21 vibrates, a load in the vertical direction is generated between the wire 50 and the electrode pad 22a. Therefore, the wire 50 may be peeled off from the electrode pad 22a or may be cut. Therefore, the reinforcing member 60 is provided not only in the left-right direction of the wire 50 joined to the electrode pad 22a but also around the wire 50. With this configuration, it is possible to prevent the wire 50 from being cut by a load applied to the wire 50 due to the vibration of the drive substrate 21. Further, by providing the reinforcing material 60 at the joint portion of the wire 50 with the electrode pad 22a, the wire 50 is peeled off from the electrode pad 22a or the wire 50 is cut due to expansion / contraction of the piezoelectric element 22 and vibration of the drive substrate 21. Can be prevented.

  As the reinforcing material 60, for example, a resin adhesive such as an epoxy resin or an acrylic resin is used. In the present embodiment, it is desirable that the reinforcing material 60 is made of a material having a predetermined elastic modulus. FIG. 5 is a simulation result in which the stress applied to the wire 50 is quantified according to the material of the reinforcing member 60 provided on the wire 50 in the optical scanner 1 of the present embodiment. FIG. 5 shows a simulation result in which the optical scanner 1 is driven at a frequency of 33 [kHz] so that the mirror 24 swings at a swing angle of ± 6.25 degrees. In the graph shown in FIG. 5, the elastic modulus of the reinforcing material 60 is shown as a characteristic of the material of the reinforcing material 60. In FIG. 5, the stress applied to the neck 50 a of the wire 50 in the optical scanner 1 in a state where the reinforcing material 60 is not provided is indicated by a line α. A stress of 45 [MPa] indicated by a line α in FIG. 5 is applied to the neck portion 50a of the wire 50 where the reinforcing material 60 is not provided. Further, in the optical scanner 1 in a state where the reinforcing material 60 is provided, the stress applied to the neck portion 50a of the wire 50 is indicated by a line β. According to FIG. 5, when the reinforcing member 60 is provided on the wire 50, the stress applied to the neck portion 50a can be reduced as compared with the case where the reinforcing member 60 is not provided. Further, the stress applied to the neck portion 50 a of the wire 50 varies depending on the elastic modulus of the reinforcing material 60. For example, when the reinforcing member 60 having an elastic modulus of 1 [Gpa] is provided on the neck portion 50a, a stress of about 27.5 [MPa] is applied. Further, when the reinforcing member 60 having an elastic modulus of 10 [Gpa] is provided, a stress of about 11 [MPa] is applied.

  As shown in FIG. 5, the stress applied to the neck portion 50 a of the wire 50 can be reduced as the reinforcing material 60 having a higher elastic modulus is provided. In particular, the reinforcing member 60 desirably has an elastic modulus of 1 [GPa] or more. However, when the reinforcing material 60 is a resin material, it is considered that the reinforcing material 60 tends to flow if the elastic modulus is too high. Even if the reinforcing material 60 having a large elastic modulus is applied to the neck portion 50a of the wire 50 to be reinforced, the reinforcing material 60 may flow before solidifying, and the neck portion 50a may not be reinforced. Therefore, it is desirable that the reinforcing material 60 has an elastic modulus of 10 [GPa] or less. For example, when a metal material having an elastic modulus larger than 10 [GPa] is used, the load stress applied to the neck portion 50a of the wire 50 can be reduced, but the boundary between the wire 50 and the metal reinforcing material A heavy load is applied. As a result, the boundary between the wire 50 and the metal reinforcing material may be broken.

(Relationship with the configuration of the present invention)
The electrode pad 22a of this embodiment is an example of the first electrode of the present invention. The electrode 35 of the present embodiment is an example of the second electrode of the present invention. The portion where the wire 50 in this embodiment is connected to the electrode pad 22a is an example of the first connection portion of the present invention. The portion where the wire 50 in this embodiment is connected to the electrode 35 is an example of the second connection portion of the present invention.

  Moreover, the scanning part 21b of the drive substrate 21 in this embodiment is an example of the board | substrate mounting part of this invention. The fixed portion 21a of the drive substrate 21 in the present embodiment is an example of the substrate support portion of the present invention. In the present embodiment, the piezoelectric element 22 is configured to greatly expand and contract in the left-right direction. The left-right direction in which the piezoelectric element 22 of the present embodiment greatly expands and contracts corresponds to the direction in which the piezoelectric element of the present invention expands and contracts. Further, in the present embodiment, the fixed portion 21a is fixed to the drive substrate 21 and vibrates around the central axis X that is the center in the left-right direction. In the present embodiment, the center in the left-right direction in which the central axis X in FIG. 1 extends corresponds to the central axis of the present invention.

(Modification)
In the present embodiment, the reinforcing member 60 is provided at the neck portion of the connection portion between the wire 50 and the electrode pad 22 a and the neck portion 50 a of the connection portion between the wire 50 and the electrode 35. However, the reinforcing member 60 provided on the wire 50 may be one of a connection portion between the wire 50 and the electrode pad 22 a or a connection portion between the wire 50 and the electrode 35. Moreover, the reinforcing material 60 should just be provided in the neck part 50a of the connection part of the wire 50 and the electrode pad 22a at least. Thereby, when the piezoelectric element 22 expands and contracts, it is possible to prevent the neck portion 50a at the connection portion with the electrode pad 22a that is heavily loaded from being cut.

  The reinforcing material 60 may be partially applied according to the position of the force applied to the wire 50 from the expanding and contracting piezoelectric element 22. Further, the reinforcing material 60 provided in the neck portion 50a may partially increase or decrease the coating amount according to the magnitude of the force applied from the piezoelectric element 22 to the wire 50.

DESCRIPTION OF SYMBOLS 1 Optical scanner 20 Scanning unit 21 Drive board 22 Piezoelectric element 22a Electrode pad 24 Mirror 30 Fixed base 34 Electrode board 35 Electrode 50 Wire 50a Neck part 60 Reinforcement material

Claims (5)

A piezoelectric element that expands and contracts when a voltage is applied;
A first electrode provided on the piezoelectric element;
A second electrode provided separately from the piezoelectric element, to which a voltage from a power source is applied;
A conducting wire electrically connecting the first electrode and the second electrode;
A vibration device comprising:
Provided in at least one of a first connection portion that is a connection portion between the conductive wire and the first electrode and a second connection portion that is a connection portion between the conductive wire and the second electrode, and the thickness of the conductive wire is , A neck portion that thickens toward the connection portion;
And a reinforcing member provided at a boundary of the neck portion that is displaced along with expansion and contraction by the piezoelectric element. A substrate that includes a mirror that reflects incident light, the mounting unit on which the piezoelectric element is mounted, and a support unit that is adjacent to and supported by the mounting unit;
The substrate vibrates about a line connecting the support portion and the mounting portion as a central axis when the piezoelectric element expands and contracts, and scans the mirror.
2. The optical scanner including the vibration device according to claim 1, wherein the reinforcing material is provided on a line connecting the first joint portion and the second joint portion of the neck portion in the conductive wire. The piezoelectric element is a direction parallel to the surface of the substrate on which the mirror is driven by expanding and contracting, and at least expands and contracts in a direction intersecting the central axis direction,
The optical scanner having the vibration device according to claim 2, wherein the reinforcing material is further provided on a line parallel to the central axis of the neck portion in the conducting wire.   The optical scanner provided with the vibration device according to claim 1, wherein the reinforcing material is provided so as to cover the boundary of the neck portion of the conducting wire and the first electrode.   The optical scanner including the vibration device according to claim 1, wherein the reinforcing material is a resin material having an elastic modulus in a range of 1 GPa to 10 GPa.