Vibration type actuator, optical and electronic equipment

Abstract

To provide a vibration type actuator in which electrical contact between a piezoelectric element and an elastic body is sufficiently ensured.SOLUTION: A vibration type actuator includes a through hole in which a plate-shaped piezoelectric material constituting a piezoelectric element penetrates in the thickness direction of the piezoelectric material and a through hole electrode filled in the through hole, the through hole electrode includes a protrusion that protrudes from a first opening of the through hole that opens toward an elastic body, a ground electrode that is electrically connected to the through hole electrode is provided on the surface of the piezoelectric material on the first opening side, and the through hole electrode and the elastic body are electrically connected to each other.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a vibration type actuator including an ultrasonic motor. [Background technology]

[0002] A vibration actuator has a vibrator configured such that vibration is excited in an elastic body joined to a piezoelectric element by applying an alternating voltage to the electromechanical energy conversion element such as a piezoelectric element. The vibration actuator is used as an ultrasonic motor that uses the driving force of the vibration excited in the vibrator to move the vibrator relative to a contact body that is in pressure contact with the vibrator.

[0003] Patent Document 1 discloses a method for manufacturing a vibrator used in a vibration type actuator. In the examples, the document discloses a process in which an elastic body (referred to as a vibration plate in the document) and a power supply member are bonded to a piezoelectric element, and then the elastic body is grounded and a polarization process is performed on the piezoelectric ceramics. However, in vibrators manufactured by the method for manufacturing a vibrator described in Patent Document 1, polarization defects may occur due to insufficient electrical contact between the piezoelectric element and the elastic body, and there has been a demand for further improvement in the yield of vibration type actuators. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2017-184233 Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention provides a vibration actuator in which sufficient electrical contact between a piezoelectric element and an elastic body is ensured. [Means for solving the problem]

[0006] The vibration actuator that solves the above problems is as follows: a vibrating body having a conductive elastic body and a piezoelectric element; a vibration actuator including a contact body in contact with the elastic body, the vibrating body and the contact body moving relatively to each other due to vibration of the vibrating body, The plate-shaped piezoelectric material constituting the piezoelectric element is a through hole penetrating the piezoelectric material in a thickness direction and a through hole electrode filled in the through hole; the through-hole electrode has a protruding portion protruding from a first opening of the through-hole that opens to the elastic body side, a ground electrode that is electrically connected to the through-hole electrode is provided on a surface of the piezoelectric material on the first opening side; The through-hole electrode and the elastic body are electrically connected to each other. Effect of the Invention

[0007] According to the present invention, it is possible to provide a vibration actuator in which electrical contact between the piezoelectric element and the elastic body is sufficiently ensured, thereby making it possible to further improve the yield of the vibration actuator. [Brief description of the drawings]

[0008] [Figure 1] 1A and 1B are diagrams illustrating the schematic structure of a vibration actuator of the present invention using a circular or rectangular piezoelectric material, where (a) and (d) are side views, (b) and (e) are perspective views, and (c) and (f) are rear views. [Diagram 2] 1A and 1B are diagrams illustrating the cross-sectional structure around a through-hole in a piezoelectric material, (a) before lapping, (b) after elastic body bonding (ground electrode thickness<protrusion amount), (c) after elastic body bonding (ground electrode thickness>protrusion amount), and (d) a comparative example. [Diagram 3] 1A and 1B are diagrams illustrating the schematic structure of an annular piezoelectric element, (a) a power supply member bonding surface, and (b) an elastic body bonding surface. [Figure 4] 1A and 1B are diagrams illustrating the schematic structure of a rectangular piezoelectric element, in which (a) and (c) show the power supply member bonding surface, and (b) and (d) show the elastic body bonding surface. [Diagram 5] 1A and 1B are diagrams illustrating two vibration modes generated by a vibrator of the present invention having a rectangular piezoelectric material, where (a) is mode A and (b) is mode B. [Figure 6] 1 is a diagram illustrating a schematic structure of an optical device according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The vibration actuator of the present invention is a vibration actuator comprising a vibrator having a conductive elastic body and a piezoelectric element provided on the elastic body, and a contact body in contact with the elastic body, and the vibrator and the contact body move relatively due to vibration of the vibrator. The plate-shaped piezoelectric material constituting the piezoelectric element has a through hole penetrating the piezoelectric material in the thickness direction and a through hole electrode filled in the through hole. The through hole electrode has a protruding portion protruding from a first opening of the through hole, and a ground electrode that is conductive with the through hole is provided on the surface of the piezoelectric material on the side of the first opening. The through hole electrode and the elastic body are characterized in that they are conductive with each other.

[0010] (Vibration Actuator) FIG. 1 illustrates a schematic structure of a vibration actuator of the present invention.

[0011] In the vibration actuator shown in Fig. 1, a circular ring-shaped piezoelectric material and a rectangular piezoelectric material are used. The vibration actuator 100 of the present invention includes a vibrator 102 in which an electrode 101, a piezoelectric material 102, and an elastic body 103 are arranged in this order, and a contact body 104 in contact with the elastic body 103. The elastic body 103 and the piezoelectric material 102 are bonded via an adhesive part 105.

[0012] The elastic body 103 has a protrusion 106, and the protrusion 106 and the contact body 104 are in pressure contact. The contact body 104 may be any member that can move relative to the vibrator 110, and is not limited to a member that directly contacts the vibrator 110, but may be a member that indirectly contacts the vibrator 110 via another member. In other words, the "contact body" refers to a member that contacts the vibrator and moves relative to the vibrator due to vibration generated in the vibrator. The contact between the contact body and the vibrator is not limited to direct contact where no other member is interposed between the contact body and the vibrator. The contact between the contact body and the vibrator may be indirect contact where another member is interposed between the contact body and the vibrator, as long as the contact body moves relative to the vibrator due to vibration generated in the vibrator. The "other member" is not limited to a member independent of the contact body and the vibrator (for example, a high-friction material made of a sintered body). The "other member" may be a surface treatment portion formed on the contact body or the vibrator by plating, nitriding, or the like.

[0013] (Piezoelectric element) The piezoelectric material 102 constituting the piezoelectric element includes piezoelectric ceramics (sintered body) without crystal orientation, crystal oriented ceramics, and piezoelectric single crystals. The thickness of the piezoelectric material is processed to a design value within the range of approximately 0.3 to 0.5 mm.

[0014] At least one through-hole penetrating the piezoelectric material 102 in the thickness direction and one through-hole electrode filled in the through-hole are provided. To generate symmetric vibrations, the through-holes may be arranged symmetrically in the piezoelectric material, or a configuration may be adopted in which only one through-hole is provided for one ground electrode in order to reduce the manufacturing cost of the element.

[0015] In order to suppress interference with the vibration of the piezoelectric element and at the same time obtain sufficient conductivity, the diameter of the through-hole is preferably in the range of 50 to 200 microns.

[0016] Fig. 2 shows a schematic cross-sectional structure of a through-hole provided in a piezoelectric material suitable for the vibration actuator of the present invention. A lapping process is applied to the surface of the piezoelectric material provided with the through-hole electrode in order to flatten the surface of the piezoelectric element and adjust the thickness (protrusion amount or height) of the protruding portion of the through-hole electrode. After the lapping process, a protruding portion of the through-hole electrode is formed at the first opening that opens on the elastic body side of the through-hole.

[0017] The amount of protrusion of the protrusion, i.e., the height from the surface of the piezoelectric material to the tip of the through-hole electrode, varies depending on the size of the media (e.g., silicon carbide) used in the lapping process, and can be adjusted by the size of the media. For example, the larger the size of the media, the smaller the amount of protrusion. FIG. 2(a) shows a state in which a through-hole electrode 203 filled in a through-hole provided in a piezoelectric material 202 protrudes from a first opening that opens on the elastic body side of the piezoelectric element, and is lapped so that it protrudes by the thickness sandwiched between the dashed lines. FIG. 2(a) shows the state before the lapping process is performed, and the height direction is exaggerated to explain the protrusion of the through-hole electrode. The through-hole electrode 203 above the upper dashed line of the two dashed lines is removed by the lapping process.

[0018] The protrusion amount of the protruding portion 201 of the through-hole electrode 203 sandwiched between the dashed lines is preferably 0.5 microns or more and less than 10 microns. If the protrusion amount is 10 microns or less, the thickness of the adhesive layer can be made 10 microns or less, and the vibration efficiency of the vibration actuator can be kept sufficiently good. On the other hand, if the protrusion amount is 10 microns or more, the thickness of the adhesive layer is greater than 10 microns, and the vibration efficiency of the vibration actuator may be significantly reduced. Furthermore, the inclination of the elastic body relative to the surface of the piezoelectric material becomes large, and there is a risk that the moving speed of the contact body will differ depending on the direction of travel.

[0019] It is more preferable that the protrusion amount is 5 microns or less, because if the protrusion amount is 5 microns or less, the thickness of the adhesive layer becomes thinner than 5 microns, and the vibration efficiency of the vibration type actuator can be maintained at a better level.

[0020] In addition to inexpensive silver, silver-palladium, platinum, etc. can be used for the through-hole electrodes. When the piezoelectric material and the through-hole electrodes are co-fired, the through-hole electrode material must not melt during the firing process of the piezoelectric material. Therefore, the through-hole electrode material is selected according to the firing temperature of the piezoelectric material, and when the firing temperature exceeds 1300°C, an electrode material whose main component is platinum is used. Main component refers to a weight percent concentration of 90% or more. The through-hole electrode can also be formed in the through-hole after the piezoelectric material is fired.

[0021] FIG. 2(b) is an enlarged cross-sectional view showing the state after a through-hole provided in the piezoelectric material is filled with a through-hole electrode 203, a lapping process is performed, a ground electrode 204 is formed, and an elastic body 206 and a piezoelectric element are bonded via an adhesive layer 205.

[0022] The ground electrode 204 and the through-hole electrode 203 provided on the surface of the piezoelectric material on the first opening side after lapping contact each other and are electrically connected to each other. FIG. 2(b) shows a case where the thickness of the ground electrode 204 is smaller than the protrusion of the through-hole electrode 203, and the through-hole electrode 203 contacts the elastic body 206 and is electrically connected to each other. By pressing the elastic body 206 and the piezoelectric material 202 through the adhesive layer 205 applied to the surface of the ground electrode 204 provided on the piezoelectric material 202, the material constituting the adhesive layer seeps out and is removed from between the ground electrode 204 and the elastic body 206. Therefore, the protrusion of the through-hole electrode and the elastic body directly contact each other and are electrically connected to each other.

[0023] When the thickness of the ground electrode is sufficiently larger than the protrusion amount, the through-hole electrode 203 is covered with the ground electrode, and the ground electrode forms a convex portion on the protrusion. In this embodiment, the convex portion of the ground electrode may be in contact with the elastic body as shown in FIG. 2(c), and the ground electrode may be configured to be conductive with the elastic body. The protrusion amount of the through-hole electrode may be replaced by the height of the convex portion of the ground electrode. It is possible to confirm that the through-hole electrode is covered with the ground electrode by detecting the constituent elements of the ground electrode between the top of the protrusion portion of the through-hole electrode and the elastic body 206.

[0024] The elastic body 103 and the piezoelectric material 102 are bonded via an adhesive layer 205. The type of adhesive is not particularly limited, but an epoxy resin is preferable because it has excellent strength, a short curing time, and is stable even in a high temperature and high humidity atmosphere. General epoxy resins are insulating.

[0025] If the piezoelectric element does not have the protrusion, increasing the pressure applied when bonding the ground electrode and the elastic body in order to conduct the ground electrode and the elastic body will significantly reduce the thickness of the adhesive layer, resulting in partial loss of the adhesive layer. As a result, the adhesive strength between the elastic body and the piezoelectric element will decrease, causing peeling during operation of the vibration actuator, resulting in malfunction. On the other hand, unlike this embodiment, if an adhesive layer is provided between the elastic body and the ground electrode without providing a protrusion of the through-hole electrode, the elastic body and the ground electrode will not be electrically conductive (Figure 2(d)). As a result, polarization failure may cause the vibration actuator to malfunction and reduce the yield.

[0026] Around the protruding portion of the above-mentioned through-hole electrode 203, a gap is provided between the ground electrode and the elastic body according to the amount of protrusion. The gap serves as a space for holding an adhesive material containing an insulating material, and by forming an adhesive layer, the adhesive strength between the piezoelectric element and the elastic body is increased. By having the protruding portion of the through-hole electrode, electrical continuity between the ground electrode and the elastic body can be obtained without sacrificing the adhesive strength between the piezoelectric element and the elastic body.

[0027] The outline of a circular piezoelectric element using a circular piezoelectric material will be specifically described below with reference to Fig. 3. When a circular piezoelectric material is used, the piezoelectric material is composed of a driving phase electrode 101e and a non-driving phase electrode 101f that are divided in the circumferential direction (Fig. 3(a)). The circumferential length of the driving phase electrode is 1 / 2 the wavelength λ of the driving frequency. The circumferential length of the non-driving phase electrode is 1 / 4 the wavelength λ of the driving frequency. The number of driving phase electrodes and non-driving phase electrodes varies according to the number of traveling waves excited in the circular piezoelectric material. The piezoelectric material corresponding to each driving phase electrode is polarized with a voltage of a different polarity from that of adjacent regions.

[0028] A circular ground electrode 101g is provided on the surface facing the electrodes 101e and 101f (FIG. 3(b)). At least one of the non-driving phase electrodes provided on the same surface as the driving phase electrode 101e is electrically connected to the ground electrode 101g via a through-hole electrode 101t.

[0029] When the first electrode, the second electrode, and the non-driving phase electrode that is electrically connected to the ground electrode via the through-hole electrode are formed on the same surface of the piezoelectric material, the shape of the power supply member can be made into a simple, planar structure.

[0030] The driving phase electrodes are separated by an odd number of non-driving phase electrodes. An elastic body is bonded to the piezoelectric element, and then a high voltage is applied between the driving phase electrode 101e and the elastic body to polarize the annular piezoelectric material. Then, a first electrode 101a and a second electrode 101b are provided so as to short-circuit the two driving phase electrode groups separated by the non-driving phase electrodes. The first electrode 101a and the second electrode 101b are formed at a temperature lower than the depolarization temperature of the piezoelectric material. The first electrode 101a and the second electrode 101b are used to drive a vibration type actuator using the annular piezoelectric material.

[0031] The outline of a rectangular piezoelectric element using a rectangular piezoelectric material will be specifically described below with reference to Fig. 4. In Fig. 4(a) and (b), one through-hole electrode is provided. The through-hole electrode is indicated by a black dot in the figure, and the black dot in Fig. 4(a) and the black dot in Fig. 4(b) indicate the top of the through-hole electrode 203 as seen from one opening of the same through-hole and the other opening facing each other.

[0032] The arrangement of the through-hole electrodes is not symmetrical about the center line of a rectangular piezoelectric element when a center line is drawn horizontally on the page of the piezoelectric material 102 in the figure, but it has lower manufacturing costs than a piezoelectric element having multiple through-hole electrodes.

[0033] On the other hand, as shown in Figures 4(c) and (d), in order to improve the vibration quality of the vibration waves generated by the vibrating body, it is also possible to arrange the through-hole electrodes so that they are substantially symmetrical with respect to the center line. Figures 4(c) and (d) show a rectangular piezoelectric element provided with two through-hole electrodes. By providing two through-hole electrodes, the arrangement of the electrodes becomes symmetrical with respect to the line, and the symmetry of the vibration generated by the piezoelectric element is improved.

[0034] The rectangular piezoelectric material is provided with a first electrode 101a, a second electrode 101b, and a non-driving phase electrode 101f (FIGS. 4(a) and 4(c)). The first electrode 101a and the second electrode 101b are polarized with a voltage of the same polarity and are used to drive a vibration type actuator using the rectangular piezoelectric material.

[0035] A rectangular ground electrode 101g is provided on the surface facing the first electrode 101a and the second electrode 101b. At least one of the non-driving phase electrodes 101f provided on the same surface as the driving phase electrodes 101a and 101b is electrically connected to the ground electrode 101g via a through-hole electrode 101t (FIGS. 4(b) and 4(d)).

[0036] The surface electrodes formed on the surface of the piezoelectric material, i.e., the driving phase electrodes, non-driving phase electrodes, ground electrodes, first electrodes, and second electrodes excluding the through-hole electrodes, are made of a metal film having a thickness of 0.3 to 10 μm. The material is not particularly limited, but silver, silver-palladium, or gold is generally used. Electrodes mainly composed of inexpensive silver are most preferable. If the thickness of the surface electrodes is less than 5 microns, it is preferable because it suppresses interference with the vibration efficiency of the piezoelectric element.

[0037] (Elastic body) The elastic body of the present invention is conductive and is electrically connected to the ground electrode. Therefore, when performing polarization processing on the piezoelectric material, the elastic body can be used as an electrode. When performing polarization processing on the annular piezoelectric material of FIG. 3, a voltage is applied to the driving phase electrode 101e and the non-driving phase electrode 101f that are not electrically connected to the ground electrode 101g, and the elastic body is grounded. When performing polarization processing on the rectangular piezoelectric material of FIG. 4, a voltage is applied to the first electrode 101a and the second electrode 101b, and the elastic body is grounded.

[0038] Considering the properties and workability as an elastic body, the elastic body 103 is preferably made of a metal. Examples of metals that can be used for the elastic body 103 include aluminum, brass, and stainless steel. Among stainless steels, martensitic stainless steel is preferable, and SUS420J2 is most preferable (resistivity at room temperature is 55 μΩcm). The elastic body has a protrusion 106 that contacts the contact body. When the elastic body is quenched to improve the wear resistance of the protrusion, the quenching is performed in a vacuum to prevent the formation of an oxide film that increases electrical resistance. SUS420J2 that has been quenched in a vacuum has high hardness and is suitable for the vibration type actuator of the present invention that drives the contact body by friction with the elastic body.

[0039] It is preferable that the thickness of the elastic body to be bonded to the rectangular piezoelectric material is in the range of 0.2 to 0.35 mm, since this provides both rigidity and springiness and is easy to mold.

[0040] From the viewpoint of rigidity, the contact body 104 is preferably made of stainless steel. Among stainless steels, martensitic stainless steel is preferable, and SUS420J2 is most preferable. The contact body 104 must have excellent wear resistance because it is in frictional contact with the elastic body 103, and its surface is subjected to a nitriding treatment. A frictional force due to pressurized contact acts between the protrusion 106 and the contact body 104. The vibration generated by the piezoelectric material 102 causes the tip of the protrusion 106 to vibrate elliptically, generating a driving force (thrust) that drives the contact body 104. The contact body is generally called a slider or rotor.

[0041] (Driving a vibration actuator using a circular piezoelectric material) In the annular piezoelectric element, the piezoelectric material in contact with the adjacent driving phase electrodes is polarized with different polarities, so when an electric field of the same polarity is applied to the driving phase electrode 101e, the expansion and contraction polarity in the corresponding region of the piezoelectric material alternates at a pitch of λ / 2. When an alternating voltage is applied to the first electrode 101a, a first standing wave with a wavelength of λ is generated over the entire circumference of the vibrator. When an alternating voltage is applied to the second electrode 101b, a second standing wave is generated in the same manner, but the position of the wave is rotated by λ / 4 in the circumferential direction relative to the first standing wave. On the other hand, two types of alternating voltages with the same frequency and a temporal phase difference of π / 2 are applied to the first and second electrodes. As a result of the synthesis of the first and second standing waves, a traveling wave (wave number n along the annulus, wavelength λ) of bending vibration (vibration with amplitude perpendicular to the surface of the vibrator) that progresses in the circumferential direction over the entire circumference is generated in the vibrator.

[0042] When a traveling wave of bending vibration (hereinafter sometimes simply referred to as "bending vibration wave") is generated, each point on the surface of the diaphragm that constitutes the vibrator moves elliptically, so that a moving body in contact with this surface receives a circumferential frictional force (driving force) from the diaphragm and rotates. The direction of rotation can be reversed by switching the positive and negative phase difference of the alternating voltage applied to the first and second electrodes. The rotation speed can also be controlled by the frequency and amplitude of the alternating voltage applied to the first and second electrodes.

[0043] (Driving a vibration actuator using rectangular piezoelectric material) Fig. 5 explains two vibration modes generated by the vibrator of the present invention having a rectangular piezoelectric material. The regions where the first electrode and the second electrode are provided are the first region and the second region, respectively. The structure of the vibration type actuator is as shown in Fig. 1 (d), (e), and (f), respectively.

[0044] Mode A When the first region and the second region both expand or contract, a first bending vibration mode (mode A) occurs. Mode A occurs when an alternating voltage V A , V Bis excited most strongly when the phase difference between them is 0° and the frequency is near the resonant frequency of mode A. Mode A is a primary out-of-plane vibration mode in which two nodes (where the amplitude is minimum) appear approximately parallel to the long sides of vibrator 110. Elastic protrusion 106 is disposed near the position that becomes the antinode (where the amplitude is maximum) of mode A. Therefore, the tip surface of protrusion 106 reciprocates in the Z direction due to vibration mode A.

[0045] Mode B When the first region expands and contracts, the second region contracts and expands, respectively, and a second bending vibration mode (mode B) is generated. Mode B is generated when an alternating voltage V A , V B is excited most strongly when the phase difference between them is 180° and the frequency is near the resonant frequency of mode B. Mode B is a secondary out-of-plane vibration mode in which three nodes appear approximately parallel to the short sides of vibrator 110. Protrusion 106 of the elastic body is disposed near the node position of mode B. Therefore, the tip surface of protrusion 106 reciprocates in the X direction due to mode B.

[0046] In the vibration actuator 100 equipped with a rectangular piezoelectric element, the alternating voltage V A , V B When the phase difference is between 0 and ±180°, mode A and mode B are excited simultaneously, and elliptical vibration is excited in protrusion 106 of the elastic body.

[0047] The vibrator is supported by a fitting hole provided in a support portion 107 that protrudes from an end of a rectangular portion 108. In order to miniaturize the vibrator, the support portion 107 can be omitted and the rectangular portion 108 of an elastic body can be held.

[0048] (Composition of piezoelectric material) It is preferred that the piezoelectric material contain less than 1000 ppm of lead.

[0049] In particular, from the viewpoint of a high piezoelectric constant and relatively easy manufacturing, it is preferable that the main component of the piezoelectric material is a barium titanate-based material. Here, examples of barium titanate-based materials include barium titanate (BaTiO3), barium calcium titanate ((Ba,Ca)TiO3), barium zirconate titanate (Ba(Ti,Zr)O3), and barium calcium zirconate titanate ((Ba,Ca)(Ti,Zr)O3). In addition, sodium niobate-barium titanate (NaNbO3-BaTiO3), sodium bismuth titanate-barium titanate ((Bi 0.5 Na 0.5 )TiO3-BaTiO3), bismuth potassium titanate-barium titanate ((Bi 0.5 K 0.5 )TiO3-BaTiO3) and other compositions are examples. It refers to materials that have these compositions as their main components. Among them, the following materials are preferred from the viewpoint of achieving both the piezoelectric constant and mechanical quality factor of the piezoelectric material. That is, it is preferred to have barium calcium zirconate titanate ((Ba,Ca)(Ti,Zr)O3) and sodium niobate-barium titanate ((1-x)NaNbO3-xBaTiO3, x = 0.1 to 015) as the main components. It is preferred to include manganese and bismuth as elements other than the main components. The term "main component" refers to a material whose weight fraction is greater than 90%.

[0050] Moreover, it is more preferable that the lead content of the piezoelectric material is 1000 ppm or less, since this reduces the environmental load. In general, lead zirconate titanate (Pb(Zr,Ti)O3) containing lead is widely used in piezoelectric devices. For this reason, it has been pointed out that, for example, when a piezoelectric element is discarded and exposed to acid rain or left in a harsh environment, the lead component in the conventional piezoelectric material may dissolve into the soil and cause harm to the ecosystem. Therefore, it is preferable that the piezoelectric material of the present invention is a barium titanate-based piezoelectric material with a lead content of less than 1000 ppm. The lead content can be measured, for example, by ICP atomic emission spectrometry.

[0051] It is preferable that the main component of the piezoelectric material is barium calcium zirconate titanate (hereinafter referred to as BCTZ). When BCTZ is the main component, the piezoelectricity of BCTZ can be adjusted according to the application by adjusting the amount of Ca and Zr. In addition, the amount of expensive niobium used can be reduced.

[0052] The piezoelectric material is a piezoelectric material containing an oxide having a perovskite structure containing Ba, Ca, Ti, and Zr, and Mn, a molar ratio x of the Ca to the sum of the Ba and the Ca is 0.02≦x≦0.30, a molar ratio y of the Zr to the sum of the Ti and the Zr is 0.020≦y≦0.095 and y≦x; It is preferable that α, which is the ratio of the molar amounts of Ba and Ca to the molar amounts of Ti and Zr, is 0.9955≦α≦1.01, and the content of Mn relative to 100 parts by weight of the oxide is 0.02 part by weight or more and 1.0 part by weight or less in terms of metal.

[0053] Such a piezoelectric material can be expressed by the following general formula (1). (Ba 1-x Ca x ) α (Ti 1-y Zr y )O3(1) however, 0.986≦α≦1.100, 0.02≦x≦0.30, 0.02≦y≦0.095 and the content of metal components other than the main component contained in the piezoelectric material is preferably 1 part by weight or less in terms of metal per 100 parts by weight of the metal oxide.

[0054] In particular, it is preferable that the metal oxide contains Mn, and the content of the Mn is 0.02 parts by weight or more and 0.40 parts by weight or less in terms of metal relative to 100 parts by weight of the metal oxide. When the Mn content is within the above range, the insulating property and the mechanical quality factor Qm are improved. Here, the mechanical quality factor Qm is a coefficient that represents the elastic loss due to vibration when the piezoelectric material is evaluated as a vibrator, and the magnitude of the mechanical quality factor is observed as the sharpness of the resonance curve in impedance measurement. In other words, it is a constant that represents the sharpness of the resonance of the vibrator. When the mechanical quality factor Qm is large, the amount of distortion of the piezoelectric material becomes larger near the resonance frequency, and the piezoelectric material can be vibrated effectively.

[0055] The metal oxide represented by the general formula (1) means that the metal elements located at the A site of the perovskite structure are Ba and Ca, and the metal elements located at the B site are Ti and Zr. However, some of the Ba and Ca may be located at the B site. Similarly, some of the Ti and Zr may be located at the A site.

[0056] In general formula (1), the molar ratio of the B site element to the O element is 1:3. However, even if the molar ratio is slightly different, it is within the scope of the present invention as long as the metal oxide has a perovskite structure as the main phase.

[0057] Whether a metal oxide has a perovskite structure can be determined, for example, by structural analysis using X-ray diffraction or electron beam diffraction.

[0058] In the general formula (1), x, which indicates the molar ratio of Ca in the A site, is in the range of 0.02≦x≦0.30. When a part of Ba in perovskite-type barium titanate is replaced with Ca within the above range, the phase transition temperature between the orthorhombic and tetragonal crystals shifts to the lower temperature side, so that stable piezoelectric vibration can be obtained in the driving temperature range of the vibration actuator. However, if x is larger than 0.30, the piezoelectric constant of the piezoelectric material becomes insufficient, and the performance of the vibration actuator may be insufficient. On the other hand, if x is smaller than 0.02, the dielectric loss (tan δ) may increase. If the dielectric loss increases, the heat generated when applying a voltage to the piezoelectric material to drive the vibration actuator may increase, the motor driving efficiency may decrease, and the power consumption may increase.

[0059] In the general formula (1), y, which indicates the molar ratio of Zr in the B site, is in the range of 0.02≦y≦0.1. If y is greater than 0.1, Td becomes low, less than 80° C., and the temperature range in which the vibration actuator can be used becomes less than 80° C., which is undesirable.

[0060] In this specification, Td refers to the lowest temperature at which the piezoelectric constant after heating a piezoelectric material from room temperature to Td one week after polarization treatment and then cooling it back to room temperature decreases by more than 10% compared to the piezoelectric constant before heating.

[0061] In general formula (1), α, which indicates the ratio of the molar amount of Ba and Ca at the A site to the molar amount of Ti and Zr at the B site, is preferably in the range of 0.9955≦α≦1.010. If α is smaller than 0.9955, abnormal grain growth is likely to occur in the crystal grains constituting the piezoelectric material, and the mechanical strength of the piezoelectric material is reduced. On the other hand, if α is larger than 1.010, the piezoelectric material does not become highly densified and the insulation becomes extremely brittle.

[0062] The method for measuring the composition of the piezoelectric material is not particularly limited. Examples of the method include X-ray fluorescence analysis, ICP emission spectrometry, and atomic absorption spectrometry. Regardless of the measurement method used, the weight ratio and composition ratio of each element contained in the piezoelectric material can be calculated.

[0063] The metal equivalent showing the Mn content is calculated by calculating the content of each metal, Ba, Ca, Ti, Zr, and Mn, measured from the piezoelectric material by X-ray fluorescence analysis (XRF), ICP atomic emission spectrometry, atomic absorption spectrometry, etc. From the content, the elements constituting the metal oxide represented by general formula (1) are converted into oxides, and the value is calculated as the ratio of the weight of Mn to the total weight of 100.

[0064] If the Mn content is less than 0.02 parts by weight, the effect of the polarization process required for driving the vibration actuator may be insufficient. On the other hand, if the Mn content is more than 0.40 parts by weight, the piezoelectric properties of the piezoelectric material may be insufficient, or crystals with a hexagonal structure that do not have piezoelectric properties may appear. Mn is not limited to metallic Mn, and it is sufficient that it is contained in the piezoelectric material as a Mn component, and the form of its inclusion does not matter. For example, it may be solid-dissolved in the B site or contained in the grain boundary. A more preferable form of inclusion is solid-dissolved in the B site from the viewpoint of insulation and sintering ease.

[0065] The piezoelectric material preferably contains 0.042 parts by weight or more and 0.850 parts by weight or less of Bi calculated as metal.

[0066] The piezoelectric material may contain 0.85 parts by weight or less of Bi in terms of metal, based on 100 parts by weight of the metal oxide represented by the general formula (1). The content of Bi relative to the metal oxide can be measured, for example, by ICP emission spectroscopy. Bi may be present at the grain boundaries of the ceramic piezoelectric material, or may be dissolved in the perovskite structure of (Ba,Ca)(Ti,Zr)O3. When Bi is present at the grain boundaries, friction between particles is reduced and the mechanical quality factor is increased. On the other hand, when Bi is incorporated into a solid solution that forms a perovskite structure, the phase transition temperature is lowered, so that the temperature dependence of the piezoelectric constant is reduced and the mechanical quality factor is further improved. When Bi is incorporated into the solid solution, it is preferable that the position of Bi is the A site, since the charge balance with the Mn is improved.

[0067] The piezoelectric material may contain components (hereinafter, "auxiliary components") other than the elements contained in the general formula (1) and Mn and Bi, to the extent that the characteristics do not change. The total amount of the auxiliary components is preferably less than 1.2 parts by weight per 100 parts by weight of the metal oxide expressed by the general formula (1). If the auxiliary components exceed 1.2 parts by weight, the piezoelectric characteristics and insulating characteristics of the piezoelectric material may be degraded. The Curie temperature of (Ba,Ca)(Ti,Zr)O3 is in the range of 85°C to 126°C.

[0068] The vibration actuator of the present invention has a power supply member joined to a piezoelectric element including the piezoelectric material and the electrodes.

[0069] It is preferable to use a flexible printed circuit board (hereinafter, FPC) as the power supply member because it has high dimensional accuracy and is easy to position. The material for the power supply member is preferably polyimide. There is no particular limitation on the method for joining the FPC and the piezoelectric element, but it is preferable to use anisotropic conductive paste (ACP) or anisotropic conductive film (ACF), which have high adhesive tact and electrical connection reliability. Supplying power through the FPC makes it possible to supply power without inhibiting the vibration of the piezoelectric element. The FPC is connected to at least the first electrode and the second electrode, and may also be connected to the non-driving phase electrode.

[0070] (Manufacturing method of piezoelectric element) The manufacturing method for piezoelectric elements is explained below. First, the raw powder of piezoelectric material is molded using a sheet molding method to create a green sheet with a thickness of 30 to 200 microns. Next, the positions for forming the through holes are determined taking into consideration factors such as shrinkage during firing and cutting margins during dicing, and the green sheet is punched with a punch with a diameter of, for example, 150 microns to form the through holes.

[0071] Print the through-hole electrode paste into the through-hole. As mentioned above, select a heat-resistant material for the through-hole electrode that will not melt during the firing process. For example, the aforementioned (Ba,Ca)(Ti,Zr)O3 requires a firing temperature of at least 1300°C, so a material with platinum as the main component is used for the through-hole electrode. For the aforementioned NaNbO3-BaTiO3, the firing temperature is 1200 to 1260°C, so Ag-Pd (e.g. 0.5Ag-0.5Pd) is used for the through-hole electrode.

[0072] After printing and drying the electrodes in the through-holes, the required number of green sheets are stacked and compressed, taking into consideration shrinkage during firing and the margin for scraping during the lapping process. When stacking the green sheets, the through-holes are aligned in the stacking direction so that the through-hole electrodes do not break.

[0073] The laminated and compressed molded body is sintered, and then a lapping process is performed to adjust the thickness of the piezoelectric material. The amount of protrusion of the through-hole electrode changes depending on the lapping conditions at this time. The amount of protrusion varies depending on the lapping conditions such as the grit (grain size) of the abrasive, the work load, and the rotation speed of the platen, but is most dependent on the grit. The lower the grit, the greater the amount of protrusion.

[0074] After lapping the piezoelectric material, the surface electrodes are printed and baked. The piezoelectric material with the surface electrodes is diced to separate into individual element pieces. For example, the rectangular piezoelectric element of the present invention has dimensions of 9 mm x 6 mm and a thickness of 0.3 to 0.45 mm.

[0075] (Vibrator manufacturing method) The vibrator constituting the vibration type actuator of the present invention is manufactured by the following steps. First, a step of bonding a piezoelectric element and an elastic body with an adhesive at temperature T1, and a step of bonding the piezoelectric element and a power supply member at temperature T2 are carried out. Then, a step of applying a voltage between the electrode and the elastic body and performing a polarization process at temperature T3 are carried out in order to manufacture the vibrator. The T1, T2, and T3 satisfy the relationships T1>T3 and T2>T3.

[0076] By using a piezoelectric element with a protruding through-hole electrode, it is possible to continuously interpose an adhesive between the piezoelectric element and the elastic body to increase the adhesive strength, while applying a voltage for polarization to the piezoelectric material via the elastic body. With this method, even if the piezoelectric material has a depolarization temperature lower than the adhesive temperature, it is possible to manufacture a vibration type actuator with a good yield.

[0077] (electronic equipment) The electronic device of the present invention is characterized by comprising the above vibration actuator, a member connected to the contact body of the vibration actuator, and a member position detection means (e.g., an encoder). The electronic device detects the position of the member and operates the vibration actuator until the member reaches a target position, thereby enabling precise control of the position of the member.

[0078] (optical equipment) The optical apparatus of the present invention includes the vibration actuator described above in a drive section, and further includes at least one of an optical element and an imaging element.

[0079] FIG. 5 is a schematic diagram showing an embodiment of the optical device (focus lens unit of the lens barrel device) of the present invention. In FIG. 5, the vibrator 110 having a rectangular piezoelectric material is in pressure contact with the contact body (slider) 104 in the same manner as in FIG. 1(d). The power supply member 507 is connected to the surface side having the first and second regions. When a desired voltage is applied to the vibrator 110 via the power supply member 507 by a voltage input means (not shown), an elliptical motion is generated in the protrusion of the elastic body (not shown). The holding member 501 is joined to the vibrator 110 and is configured not to generate unnecessary vibration. The moving housing 502 is fixed to the holding member 501 with a screw 503 and is integrated with the vibrator 110. These members form the electronic device of the present invention. By attaching the moving housing 502 to the guide member 504, the electronic device of the present invention can move linearly in both directions (forward and reverse directions) along the guide member 504.

[0080] Next, a lens 506 (optical member) that plays the role of a focus lens of the lens barrel device will be described. The lens 506 is fixed to a lens holding member 505, and has an optical axis (not shown) parallel to the moving direction of the vibration actuator. The lens holding member 505, like the vibration actuator, moves linearly on two guide members 504 described later to perform focal position adjustment (focusing operation). The two guide members 504 are members that engage the movable housing 502 and the lens holding member 505, enabling the movable housing 502 and the lens holding member 505 to move linearly. With this configuration, the movable housing 502 and the lens holding member 505 can move linearly on the guide members 504.

[0081] Furthermore, the connecting member 510 is a member that transmits the driving force generated by the vibration actuator to the lens holding member 505, and is fitted and attached to the lens holding member 505. This allows the lens holding member 505 to move smoothly in both directions along the two guide members 504 together with the movable housing 502.

[0082] Further, sensor 508 is provided to detect the position of lens holding member 505 on guide member 504 by reading position information from scale 509 affixed to the side surface of lens holding member 505. As described above, the focus lens unit of the lens barrel device is configured by incorporating the above-mentioned respective members.

[0083] In the above, a lens barrel device for a single-lens reflex camera has been described as an example of an optical device, but the present invention can be applied to a variety of optical devices equipped with a vibration actuator regardless of the type of camera, such as a compact camera in which the lens and camera body are integrated, or an electronic still camera.

[0084] As another configuration of the vibration type actuator, a plurality of vibrators may be in contact with one common contact body, and the contact body may be arranged so that the vibration of the plurality of vibrators causes relative movement of the plurality of vibrators.

[0085] Furthermore, the vibration actuator of the present invention can be applied to medical or engineering fields. Specifically, a wire-driven actuator can be configured that includes a thin member, a wire that is inserted through the thin member and fixed to a part of the thin member, and the vibration actuator that drives the wire, and that bends the thin member by driving the wire. EXAMPLES

[0086] Next, the vibration actuator of the present invention will be described with reference to examples, but the present invention is not limited to the following examples.

[0087] First, a piezoelectric element with a protruding through-hole electrode was fabricated according to the manufacturing method of the piezoelectric element described above. The relationship between the size of the media used in lapping the piezoelectric material and the protruding amount of the through-hole electrode is shown in Table 1.

[0088] [Table 1]

[0089] Example 1 A circular ring-shaped compact of (Ba,Ca)(Ti,Zr)O3 with through-hole electrodes was sintered at 1340°C. The resulting sintered body was adjusted to a thickness of 0.5 mm using #4000 silicon carbide powder. At this time, the protrusion of the through-hole electrodes was 1 to 3 microns. The inner and outer diameters were also ground to process it into a ring shape with an outer diameter of 62 mm and an inner diameter of 54 mm.

[0090] The driving phase electrode 101e and the non-driving phase electrode 101f shown in FIG. 3(a) were formed on one side of the shaped piezoelectric material 102. In the example of FIG. 3(a) where three non-driving phase electrodes are formed continuously, the driving phase electrode 101e and the non-driving phase electrode 101f are printed so that the middle non-driving phase electrode and the through-hole are joined. As a result, the ground electrode 101g in FIG. 3(b) is electrically connected to one of the non-driving phase electrodes 101f via the through-hole electrode 101t. The surface electrodes formed by the screen printing method are dried and then baked at 600 to 850°C. The thickness of the silver surface electrodes after baking was 6 microns.

[0091] Next, adhesive was applied to elastic body 103 made of SUS420J2, and it was pressed against piezoelectric material 102 with electrodes formed on it. The annular piezoelectric material and annular elastic body were positioned using a positioning jig so that the centers of their respective circles were aligned. Next, heat treatment was performed to harden the conductive adhesive. The piezoelectric material with the elastic body pressed against it was heated to a temperature T1 = 160°C and held for 180 seconds, then cooled to room temperature, and the elastic body and piezoelectric element were bonded together. At least one of the non-driven phases of the annular piezoelectric element was conductive to the elastic body.

[0092] Next, the FPC coated with ACP was thermocompression bonded to the electrodes provided on the piezoelectric material. The thermocompression bonding conditions were a temperature T2 = 140°C and a holding time of 20 seconds. After that, the elastic body SUS420J2 was grounded, and voltages of different polarities were applied alternately to the adjacent driving phase electrodes 101e to perform polarization processing. In the polarization processing, multiple external electrodes connected to a power source were brought into contact with the driving phase electrodes 101e and the electrodes used as sensors among the driven phase electrodes 101f that were not conductive with the installation electrode 101t. After that, the FPC was heated to T3 = 100°C, and an electric field equivalent to 2 kV / mm was applied for 30 minutes, and then the FPC was cooled to 40°C for 40 minutes while the electric field was applied, and the voltage application was terminated. After that, the first electrode 101a and the second electrode 101b were printed and dried to obtain a vibrator. In the drying process, the temperature of the piezoelectric material was kept below 80°C to prevent depolarization of the piezoelectric material. The obtained vibrator was brought into pressure contact with a contact body (rotor) made of SUS420J2 to produce a vibration type actuator.

[0093] Example 2 A plate-shaped molded body of (Ba,Ca)(Ti,Zr)O3 provided with a through-hole electrode was sintered at 1340°C. The composition of the through-hole electrode was platinum. The obtained sintered body was adjusted to a thickness of 0.4 mm using 4000-number silicon carbide powder. At this time, the protrusion amount of the through-hole electrode was 1 to 3 microns. On one side of the plate-shaped piezoelectric material 102 with the adjusted thickness, the first electrode 101a, the second electrode 101b, and the non-driving phase electrode 101f shown in FIG. 4(a) were printed and dried. Next, the installation electrode 101g was printed on the opposite side of the piezoelectric material and dried. The surface electrode was baked at 600 to 850°C. The thickness of the silver surface electrode after baking was 3 microns. The ground electrode 101g was conductive with the non-driving phase electrode 101t via the through-hole electrode 101t. Thereafter, the piezoelectric material having the surface electrodes formed thereon was cut into individual pieces of 8.9 mm×5.7 mm using a dicing device, to obtain the rectangular piezoelectric elements shown in FIG. 4(a).

[0094] Next, an epoxy-based thermosetting adhesive was applied to the elastic body 103 shown in FIG. 1(e) made of SUS420J2, and it was pressed onto the piezoelectric material 102 on which the electrodes were formed. Next, a heat treatment was performed to harden the adhesive. The piezoelectric material with the elastic body pressed onto it was heated to a temperature T1 = 160°C and held for 180 seconds, and then cooled to room temperature, bonding the elastic body and the piezoelectric element. After bonding, the non-driven phase of the rectangular piezoelectric element and the elastic body were conductive.

[0095] Next, the FPC coated with ACP was thermocompressed to the non-driving phase electrode provided on the piezoelectric material to produce a vibrator. The thermocompression conditions were temperature T2 = 140°C and holding time 20 seconds. After that, the elastic body SUS420J2 was grounded, and a voltage of the same polarity was applied to the first electrode 101a and the second electrode 101b to perform polarization processing. In the polarization processing, two external electrodes connected to a power source were brought into contact with the first electrode 101a and the second electrode 101b. After that, it was heated to T3 = 100°C, and an electric field equivalent to 2 kV / mm was applied for 30 minutes, and then it was cooled to 40°C over 40 minutes while the electric field was applied, and the voltage application was terminated. The obtained vibrator was pressed into contact with a contact body (rotor) made of SUS420J2 to produce a vibration type actuator.

[0096] Example 3 Except for using #2000 silicon carbide powder for wrapping the sintered body, a vibration type actuator was produced in the same manner as in Example 2. The protrusion amount of the through-hole electrode was 3 to 5 microns.

[0097] Example 4 Except for using #1000 silicon carbide powder for wrapping the sintered body, a vibration actuator was produced in the same manner as in Example 2. The protrusion amount of the through-hole electrode was 5 to 10 microns.

[0098] Example 5 A plate-shaped molded body of 0.88NaNbO3-0.12BaTiO3 with a through-hole electrode was sintered at 1260°C. The composition of the through-hole electrode was 5Ag-5Pd, a mixture of silver and palladium in a molar ratio of 1:1. The thickness of the piezoelectric material of the obtained sintered body was adjusted to 0.35 mm using silicon carbide powder of No. 4000. At this time, the protrusion amount of the through-hole electrode was 1 to 3 microns. On one side of the plate-shaped piezoelectric material 102 with the adjusted thickness, the first electrode 101a, the second electrode 101b, and the non-driving phase electrode 101f shown in FIG. 4(c) were printed and dried. Next, the installation electrode 101g was printed on the opposite side of the piezoelectric material and dried. The surface electrodes were baked at 600 to 850°C. The ground electrode 101g was conductive to the non-driving phase electrode 101t via the through-hole electrode 101t. Thereafter, the piezoelectric material having the surface electrodes formed thereon was cut into individual pieces of 8.5 mm×5.7 mm using a dicing device, to obtain the rectangular piezoelectric elements shown in FIG. 4(c).

[0099] Next, an epoxy-based thermosetting adhesive was applied to the elastic body 103 shown in FIG. 1(e) made of SUS420J2, and the elastic body was pressed against the piezoelectric material 102 made of 0.88NaNbO3-0.12BaTiO3 with electrodes. Next, a heat treatment was performed to harden the adhesive. The piezoelectric material with the elastic body pressed against it was heated to a temperature T1=160°C and held for 180 seconds, and then cooled to room temperature, bonding the elastic body and the piezoelectric element. After bonding, the non-driven phase 101f of the rectangular piezoelectric element and the elastic body were conductive.

[0100] Next, the FPC coated with ACP was thermocompressed to the non-driving phase electrode provided on the piezoelectric material to produce a vibrator. The thermocompression conditions were temperature T2 = 140°C and holding time 20 seconds. After that, the elastic body SUS420J2 was grounded, and a voltage of the same polarity was applied to the first electrode 101a and the second electrode 101b to perform polarization treatment. In the polarization treatment, two external electrodes connected to a power source were brought into contact with the first electrode 101a and the second electrode 101b. After that, it was heated to T3 = 150°C, and an electric field equivalent to 2 kV / mm was applied for 30 minutes, and then it was cooled to 40°C for 40 minutes while the electric field was applied, and the voltage application was terminated. The obtained vibrator was pressed into contact with a contact body (rotor) made of SUS420J2 to produce a vibration type actuator.

[0101] (Evaluation and manufacturing method of vibration actuators) Five vibration actuators were fabricated for each of Examples 2 to 4, and a drive test was performed by applying an alternating voltage with an amplitude of 120 Vpp to the first and second electrodes, where the phase difference between the voltages at the first and second electrodes was set to -90° and 90°.

[0102] When the frequency of the AC voltage is swept from a frequency higher than the resonant frequency of vibration mode A and vibration mode B toward the resonant frequency, the contact body is driven in a direction according to the phase difference of the AC voltage and stops after reaching maximum speed. For convenience, the directions of travel when the phase difference is -90° and 90° are called the reverse direction and forward direction, respectively. The maximum speed of the vibrator and the frequency at which the maximum speed was reached were measured with a sensor. The power (rated power) at a rated speed lower than the maximum speed was calculated from the current flowing through the drive circuit.

[0103] The rated power of the vibration actuators of Examples 2 and 3 was approximately 10% lower than, and generally equivalent to, the rated power of the vibration actuator of Example 4. The drive characteristics of the vibration actuators of Examples 2 to 4 were evaluated for durability by performing continuous reciprocating motion, and no significant deterioration in the drive characteristics was observed even after the test.

[0104] Comparative Example 1 A green sheet of (Ba,Ca)(Ti,Zr)O3 with a thickness of about 130 microns was prepared. After forming through holes in the green sheet with a punch, the green sheets were laminated, pressed, and sintered at 1340°C without printing through-hole electrodes. The obtained sintered body was adjusted to a thickness of 0.4 mm using 4000-number silicon carbide powder. On one side of the plate-shaped piezoelectric material 102 with the adjusted thickness, the first electrode 101a, the second electrode 101b, and the non-driving phase electrode 101f shown in FIG. 4(a) were printed and dried. Next, the installation electrode 101g was printed and dried on the opposite side of the piezoelectric material. The electrodes were filled in the through-holes through the printing process of these surface electrodes. The surface electrode and the through-hole electrodes were baked at 600 to 850°C. The protrusion amount of the through-hole electrodes was 0 microns or less. The ground electrode 101g was electrically connected to the non-driving phase electrode 101t via the through-hole electrode 101t. Thereafter, the piezoelectric material having the surface electrodes formed thereon was cut into individual pieces of 8.9 mm×5.7 mm using a dicing device, to obtain the rectangular piezoelectric elements shown in FIG. 4(a).

[0105] Next, an epoxy-based thermosetting adhesive was applied to the elastic body 103 shown in FIG. 1(e) made of SUS420J2, and it was pressed onto the piezoelectric material 102 on which the electrodes were formed. Next, a heat treatment was performed to harden the adhesive. The piezoelectric material with the elastic body pressed onto it was heated to a temperature T1 = 160°C and held for 180 seconds, and then cooled to room temperature to bond the elastic body and the piezoelectric element. After bonding, there were some vibrators in which the non-driven phase of the rectangular piezoelectric element and the elastic body were not conducting.

[0106] Example 6 The vibration actuator produced in Example 2 was mechanically connected to an optical member to produce the optical device shown in Figure 6. By controlling the alternating voltage applied to the piezoelectric material based on the position information given to the encoder consisting of a sensor and a scale, it was possible to precisely drive the vibration actuator and the optical member connected to the vibration actuator to the target position. In this optical device, an optical lens was connected to the vibration actuator, and it was confirmed that it had an autofocus function.

[0107] In the vibration actuator of the present invention, which uses a piezoelectric element with a through-hole electrode having a protruding portion, the elastic body and the ground electrode are electrically connected to each other, so that polarization defects do not occur in the process of grounding the elastic body and performing polarization treatment on the piezoelectric material, and vibration actuators can be manufactured with a good yield. [Industrial Applicability]

[0108] The vibration actuator of the present invention can be used for various purposes such as driving lenses and image pickup elements in imaging devices (optical instruments), driving the rotation of photosensitive drums in copiers, driving stages, etc. Although one vibration actuator has been described in this specification, multiple vibration actuators can also be arranged in a circular ring to drive the rotation of a ring-shaped contact body. [Explanation of symbols]

[0109] 100 Vibration Actuator 101 Electrode 101a 1st electrode 101b 2nd electrode 101e Driving phase electrode 101f Non-driven phase electrode 101g ground electrode 101t Through-hole electrode 102 Piezoelectric Materials 103 Elastic Body 104 Contact body 105 Conductive adhesive 106 Protrusion 107 Support part 108 Rectangular part 110 Transducer 201 Protrusion 202 Piezoelectric Materials 203 Through-hole electrode 204 Ground electrode 205 Adhesive layer 206 Elastic Body

Claims

1. a vibrating body having a conductive elastic body and a piezoelectric element; a vibration type actuator including a contact body in contact with the elastic body, wherein the vibrating body and the contact body move relatively to each other due to vibration of the vibrating body, The plate-shaped piezoelectric material constituting the piezoelectric element is a through-hole penetrating the piezoelectric material in a thickness direction and a through-hole electrode filled in the through-hole; the through-hole electrode has a protruding portion protruding from a first opening of the through-hole that opens to the elastic body side, a ground electrode electrically connected to the through-hole electrode is provided on a surface of the piezoelectric material on the side of the first opening, The vibration type actuator is characterized in that the through-hole electrode and the elastic body are electrically connected to each other.

2. 2. The vibration actuator according to claim 1, wherein the through-hole electrode protrudes from the first opening of the through-hole by 10 microns or less.

3. 3. The vibration actuator according to claim 2, wherein the ground electrode is provided between the elastic body and the through-hole electrode.

4. 4. The vibration actuator according to claim 3, wherein a non-driving phase electrode is provided on the surface of the piezoelectric material on the side of a second opening opposed to the first opening of the through-hole.

5. 5. The vibration actuator according to claim 4, wherein the piezoelectric material is rectangular.

6. 5. The vibration actuator according to claim 4, wherein the elastic body is rectangular.

7. 5. The vibration actuator according to claim 4, wherein the elastic body is annular.

8. 5. The vibration actuator according to claim 4, wherein the piezoelectric element is provided with first and second surface electrodes adjacent to the non-driven phase electrode, and the vibrator forms a first bending vibration mode in which the first region and the second region both expand or contract when the first region expands or contracts, when the regions in the piezoelectric material where the first electrode and the second electrode are provided, respectively, are defined as a first region and a second region.

9. 5. The vibration actuator according to claim 4, wherein the elastic body is bonded to the surface on which the ground electrode is provided with an adhesive material, and at least one of the non-driving phase electrodes is electrically connected to the elastic body via the through-hole electrode and the ground electrode.

10. 5. The vibration actuator according to claim 4, wherein the elastic body is made of martensitic stainless steel.

11. 10. The vibration type actuator according to claim 9, wherein the through-hole electrode is mainly made of platinum, and the first electrode, the second electrode, the ground electrode, and the non-driving phase electrode are mainly made of silver.

12. 10. The vibration actuator according to claim 9, wherein the adhesive material is an insulating material.

13. 3. The vibration actuator according to claim 2, wherein the piezoelectric material contains less than 1000 ppm of lead.

14. 14. The vibration actuator according to claim 13, wherein the piezoelectric material includes a barium titanate-based material.

15. 15. The vibration actuator according to claim 14, wherein the piezoelectric material includes barium calcium zirconate titanate.

16. 5. The vibration type actuator according to claim 4, wherein the piezoelectric element has one through-hole electrode.

17. An electronic device comprising: a member; and the vibration actuator according to claim 1 provided on the member.

18. An optical device comprising the vibration actuator according to claim 1 in a drive section, and further comprising at least one of an optical element and an imaging element.

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