Vibration wave motor and drive device

Abstract

A vibration wave motor includes a first elastic body 111 and a second elastic body 112, a piezoelectric element (electromechanical energy conversion element) 113 sandwiched between the first elastic body 111 and the second elastic body 112, and a contact body configured to be in pressure contact with the first elastic body 111, an outer shape of a cross section (XY plane) in the piezoelectric element (113) perpendicular to a pressure direction (Z direction) in pressure contact between the first elastic body (111) and the contact body is a rectangle, and vertexes (1131-1134) of the rectangle of the piezoelectric element (113) are not in contact with the first elastic body (111).

Description

Technical Field

[0001] The present invention relates to a vibration wave motor and a drive device including the vibration wave motor. Background Art

[0002] Various configurations of vibration wave motors using electromechanical energy conversion elements such as piezoelectric elements are known. For example, a vibration wave motor that performs driving by bringing a rotor into pressure contact with a Langevin vibrator configured by clamping a piezoelectric element with an elastomer made of stainless steel or the like is known. The driving principle is to generate two bending vibrations orthogonal to each other on the vibrator by applying a predetermined alternating voltage (also referred to as a "driving voltage") to the piezoelectric element, thereby generating an elliptical motion or a circular motion on the surface of the elastomer, and the rotor is rotationally moved by frictional force.

[0003] For example, the piezoelectric element includes a stacked body in order to obtain a greater driving force and has an annular columnar configuration. The piezoelectric element including the stacked body is manufactured through various steps. In particular, it is necessary to perform outer diameter processing after sintering, and the outer diameter processing requires special equipment, which increases the manufacturing cost.

[0004] Patent Document 1 discusses a vibrator including a piezoelectric element as an electromechanical energy conversion element having a polygonal cross-section orthogonal to the axis direction, and a pair of metal elastomers each having a circular cross-section orthogonal to the axis direction. More specifically, Patent Document 1 discusses a rod-shaped vibrator in which the piezoelectric element is disposed between a pair of metal elastomers, and the metal elastomers are fastened by fastening members to clamp the piezoelectric element and fix it between the metal elastomers. In addition, in Patent Document 1, the piezoelectric element is formed in a rectangular shape (more specifically, a square shape). Therefore, the piezoelectric element cut out from the sheet can be used as it is (the work of outer shape processing can be eliminated). This makes it possible to reduce the manufacturing cost.

[0005] In Patent Document 2, four divided portions of the inner layer electrode of a piezoelectric element formed in a rectangular shape (more specifically, a square shape) are disposed at positions corresponding to respective vertices of the rectangle including the piezoelectric element. This makes it possible to generate a greater force compared to the case where the four divided portions of the inner layer electrode are disposed at positions not including the vertices.

[0006] Citation List

[0007] Patent Documents

[0008] Patent Document 1: Japanese Patent Laid-Open No. 2003-47266

[0009] Patent Document 2: Japanese Patent Laid-Open No. 2006-179578 Summary of the Invention

[0010] Technical problem

[0011] However, there is the following problem: when the shape of a piezoelectric element, which is an electromechanical energy conversion element, is changed from circular to rectangular (e.g., square) as in the prior art, the power increases. This is because, for example, when the piezoelectric element is formed into a square as in the piezoelectric element discussed in Patent Document 2, the distance from the axial center in the radial direction is √2 times as large as that in the case where the piezoelectric element is formed into a circle, the pressure increases toward the outer diameter side, and the vibrator cannot be vibrated efficiently.

[0012] The present invention has been made in consideration of such a problem, and is directed to a vibration wave motor that can efficiently perform vibration while reducing the manufacturing cost.

[0013] Solution to the problem

[0014] The vibration wave motor according to the present invention includes a first elastic body and a second elastic body; an electromechanical energy conversion element sandwiched between the first elastic body and the second elastic body; and a contact body configured to be in pressure contact with the first elastic body. In the electromechanical energy conversion element, the outer shape of a cross section perpendicular to the pressure direction in the pressure contact is rectangular. The vertices of the rectangle of the electromechanical energy conversion element do not contact the first elastic body. In addition, the present invention includes a drive device including the above-described vibration wave motor.

[0015] Advantageous effects of the present invention

[0016] According to the present invention, it is possible to provide a vibration wave motor that can efficiently perform vibration while reducing the manufacturing cost. Description of the drawings

[0017] Figure 1 is an exploded view of a vibration wave motor according to a first exemplary embodiment of the present invention.

[0018] Figure 2 is a cross-sectional view of a vibration wave motor according to a first exemplary embodiment of the present invention.

[0019] Figure 3A is a diagram illustrating a vibration mode in a vibrator of a vibration wave motor according to a first exemplary embodiment of the present invention.

[0020] Figure 3B is a diagram illustrating a vibration mode in a vibrator of a vibration wave motor according to a first exemplary embodiment of the present invention.

[0021] Figure 3CFIG. is a diagram showing vibration modes in a vibrator of a vibration wave motor according to a first exemplary embodiment of the present invention.

[0022] Figure 4 is Figure 2 an enlarged view of a predetermined region in a cross section of the vibration wave motor shown in

[0023] Figure 5 Part A of

[0024] Figure 5 is a diagram showing the outer shape of a contact surface between a first elastic body and a piezoelectric element and the outer shape of a contact surface between a second elastic body and a flexible printed board according to a first exemplary embodiment of the present invention when viewed from the axial direction (Z direction) of the vibrator.

[0025] Figure 6 is a cross-sectional view of a piezoelectric element perpendicular to the axial direction (Z direction) of the vibrator (XY plane) according to a first exemplary embodiment of the present invention.

[0026] Figure 7 is a diagram showing Figure 4 in the case where the gap shown in Figure 4 is provided and in the case where the gap shown in

[0027] Figure 8A is a diagram showing the outer shape of a contact surface between a first elastic body and a piezoelectric element according to a second exemplary embodiment of the present invention when viewed from the axial direction (Z direction) of the vibrator.

[0028] Figure 8B is a diagram showing the outer shape of a contact surface between a first elastic body and a piezoelectric element according to a second exemplary embodiment of the present invention when viewed from the axial direction (Z direction) of the vibrator.

[0029] Figure 9A is a cross-sectional view of a piezoelectric element perpendicular to the axial direction (Z direction) of the vibrator (XY plane) according to a third exemplary embodiment of the present invention.

[0030] Figure 9B is a cross-sectional view of a piezoelectric element perpendicular to the axial direction (Z direction) of the vibrator (XY plane) according to a third exemplary embodiment of the present invention.

[0031] Figure 9CIt is a cross-sectional view of a piezoelectric element perpendicular to the axis direction (Z direction) of a vibrator (XY plane) according to a third exemplary embodiment.

[0032] Figure 10A It is a diagram illustrating an example of a schematic configuration of an imaging device applied as a driving device according to a fourth exemplary embodiment of the present invention.

[0033] Figure 10B It is a diagram illustrating an example of a schematic configuration of an imaging device applied as a driving device according to a fourth exemplary embodiment of the present invention. Detailed Description

[0034] Some embodiments (exemplary embodiments) for implementing the present invention will be described below with reference to the accompanying drawings.

[0035] (First Exemplary Embodiment)

[0036] First, the first exemplary embodiment of the present invention will be described.

[0037] Figure 1 It is an exploded view of a vibration wave motor 100 according to the first exemplary embodiment of the present invention.

[0038] As Figure 1 shown, the vibration wave motor 100 includes a rod-shaped vibrator 110, a contact body 120, a rotor main ring 130, rubber 140, a pressure spring 150, a gear 160, a flange cap 170, a flange 180, and a nut 190.

[0039] As Figure 1 shown, the rod-shaped vibrator 110 includes a first elastic body 111, a second elastic body 112, a piezoelectric element (electromechanical energy conversion element) 113, a flexible printed circuit board 114, a shaft 115, and a nut 116. The rod-shaped vibrator 110 is configured such that the shaft 115 and the nut 116 fasten the first elastic body 111, the second elastic body 112, the piezoelectric element 113, and the flexible printed circuit board 114 to apply a predetermined holding force.

[0040] Figure 2 It is a cross-sectional view of the vibration wave motor 100 according to the first exemplary embodiment of the present invention. In Figure 2 this, components similar to those shown in Figure 1 are denoted by the same reference numerals. Figure 2 An XYZ coordinate system is illustrated to facilitate understanding of the positions of the respective components of the vibration wave motor 100. Hereinafter, with reference to Figure 1 and Figure 2 the schematic configuration and basic principle of the vibration wave motor 100 according to the first exemplary embodiment will be described.

[0041] The piezoelectric element 113 includes electrode groups (A-phase and B-phase), and each electrode group includes two electrodes. An AC voltage (AC electric field) with different phases is applied to the electrode groups from a power source (not shown) through the flexible printed board 114. As a result, two bending vibrations orthogonal to each other are excited on the vibrator 110.

[0042] Figures 3A to 3C FIG. is a diagram illustrating a vibration mode in the vibrator 110 of the vibration wave motor 100 according to the first exemplary embodiment of the present invention. In Figures 3A to 3C , components similar to those shown in Figure 1 are denoted by the same reference numerals. Additionally, Figures 3A to 3C FIG. illustrates an XYZ coordinate system corresponding to the XYZ coordinate system shown in Figure 2 . More specifically, Figure 3A FIG. illustrates a state where no voltage is applied to the vibrator 110. Figure 3B FIG. illustrates a vibration mode in which bending occurs in the X direction (left - right direction on the paper surface) in the vibrator 110. Figure 3C FIG. illustrates a vibration mode in which bending occurs in the Y direction (vertical direction on the paper surface) in the vibrator 110.

[0043] Furthermore, by adjusting the phases of the AC voltages (AC electric fields) applied to the piezoelectric element 113, a 90 - degree time phase difference can be given to two vibration modes that are offset by 90 degrees in the spatial phase around the axis direction of the vibrator 110. As a result, the bending vibration of the vibrator 110 rotates around the axis, and elliptical motion occurs on the first elastic body 111. When the contact body 120 is brought into pressure contact with the first elastic body 111, the contact body 120, the rotor main ring 130 to which the contact body 120 is fixed, and the gear 160 rotate integrally around the axis by frictional force. In the present exemplary embodiment, the pressure direction in the pressure contact between the first elastic body 111 and the contact body 120 is the Z direction.

[0044] In the present exemplary embodiment, the piezoelectric element 113 is assumed to be a stacked piezoelectric element formed by alternately stacking a plurality of piezoelectric layers and electrode layers and sintering these layers simultaneously; however, the piezoelectric element 113 may have a configuration in which a plurality of single-plate piezoelectric elements are stacked and clamped by an elastomer. In the present exemplary embodiment, a sensor phase for monitoring the vibration state of the vibrator 110 is provided on a part of the A phase of the piezoelectric element 113. The vibration state of the vibrator 110 is monitored by detecting the charge generated due to the distortion of the bending vibration passing through the vibrator 110 (i.e., the charge generated by the direct piezoelectric effect). At this time, the relationship between the phase difference between the voltage applied to the A-phase piezoelectric element and the output signal of the sensor phase with respect to frequency is 90 degrees at the resonance frequency and gradually shifts as the frequency increases from the resonance frequency. Therefore, when detecting the value of the phase difference while exciting the vibration, the relationship between the input frequency and the resonance frequency of the vibrator 110 can be monitored, and stable driving can be performed.

[0045] As Figure 2 shown, the lower end surface of the contact body 120 is in contact with the first elastomer 111 (pressure). The contact body 120 is fixed to the rotor main ring 130, and the contact body 120 and the rotor main ring 130 rotate integrally. The contact body 120 has a small contact area with the first elastomer 111 and has appropriate spring properties. As the material of the contact body 120, stainless steel having wear resistance, strength, and corrosion resistance is preferable, and SUS420J2 is more preferable. The contact body 120 made of such a material can be processed by turning, a three-dimensional (3D) printer, etc.; however, from the viewpoints of processing accuracy and cost, stamping is preferable. The contact body 120 is fixed to the rotor main ring 130 by adhesion using a resin adhesive, metal brazing using solder, etc., welding such as laser welding or resistance welding, or mechanical joining such as press fitting or crimping.

[0046] The rotor main ring 130 is pressurized by the pressure spring 150 through the rubber 140. When the rotor main ring 130 is pressurized in such a manner, a frictional force is generated between the contact body 120 and the first elastomer 111, and the contact body 120 can be rotated by the above-described elliptical motion. The rubber 140 has a function of reducing unnecessary vibration of the pressure spring 150 while equalizing the pressing force.

[0047] As Figure 2 shown, a gear 160 for transmitting the output to the outside is provided on the upper surface of the rotor main ring 130. In addition, as Figure 1As shown, the concave portion that meshes with the convex portion provided on the gear 160 is provided on the upper surface of the rotor main ring 130. When the convex portion of the gear 160 meshes with the concave portion provided on the upper surface of the rotor main ring 130, the gear 160 rotates together with the rotor main ring 130, and transmits the output of the vibration wave motor 100 to the outside. The gear 160 slides while receiving pressure. Therefore, the gear 160 is preferably made of a material that satisfies strength and wear resistance. In addition, considering cost and quiet performance, the gear 160 is most preferably made of a resin containing reinforcing fibers.

[0048] The vibrator 110 is fixed to the flange 180 as a fixing member through the shaft 115 and the nut 190. A flange cap 170 as a pressure receiving member is provided between the gear 160 and the flange 180. The flange cap 170 can be fixed to the flange 180 using an adhesive or the like. As the material of the flange cap 170, a material having wear resistance is preferable. The flange cap 170 is more preferably formed by stamping of stainless steel because high dimensional accuracy and high productivity can be achieved. The flange 180 is preferably formed by resin molding, zinc die casting, aluminum die casting, or metal sintering because the flange 180 has a complex shape. In the present exemplary embodiment, the flange 180 is more preferably formed by zinc die casting that is excellent in the balance between dimensional accuracy and cost. In the present exemplary embodiment, the gear 160 and the flange cap 170 slide in the axial direction (the arrangement direction of the shaft 115: Z direction) of the vibrator 110, and the gear 160 and the flange 180 slide in the radial direction to be used as a sliding bearing.

[0049] Figure 4 is Figure 2 An enlarged view of a predetermined region 101 in a cross section of the vibration wave motor 100 shown in. In Figure 4 In, components similar to the components shown in Figure 2 are denoted by the same reference numerals.

[0050] As Figure 4 shown, a gap S1 extending from the axial center toward the outer diameter side is provided between the first elastic body 111 and the piezoelectric element 113. More specifically, Figure 4 the first elastic body 111 shown in includes a first surface 1111 in a region adjacent to the outer shape of the piezoelectric element 113 on the piezoelectric element 113 side of the first elastic body 111, and the first surface 1111 includes the gap S1 between the first elastic body 111 and the piezoelectric element 113.

[0051] As Figure 4 shown, a gap S2 is provided between the flexible printed board 114 and the second elastic body 112. More specifically, Figure 4The second elastomer 112 shown in [the figure] includes a second surface 1121 in an outer shape adjacent region of the outer shape of the piezoelectric element 113 on the flexible printed board 114 side, and the second surface 1121 includes a gap S2 between the second elastomer 112 and the flexible printed board 114.

[0052] The following describes Figure 4 the suitable sizes of the gap S1 and the gap S2 shown in [the figure].

[0053] When the sizes of the gap S1 and the gap S2 are too small, the gap S1 and the gap S2 are filled due to variations during manufacturing, deformation when the piezoelectric element 113 is clamped by the elastomers 111 and 112, and displacement during driving, and the above-described functions cannot be performed. Therefore, the size of each of the gap S1 and the gap S2 is desirably 20 μm or more. When the sizes of the gap S1 and the gap S2 are too large, the vibration mode changes from the desired mode and the driving efficiency decreases. Therefore, the size of each of the gap S1 and the gap S2 is desirably 200 μm or less. Thus, Figure 4 the size of each of the gap S1 and the gap S2 shown in [the figure] is preferably 20 μm or more and 200 μm or less.

[0054] In Figure 4 the example shown in [the figure], the gap S1 is ensured by forming a first surface 1111 including a step on the surface of the first elastomer 111; however, the present invention is not limited to this form. For example, a form in which a thin plate (first plate) having a thickness of 20 μm or more and 200 μm or less corresponding to the gap S1 is provided between the first elastomer 111 and the piezoelectric element 113 also achieves an effect similar to that in the above-described case where the gap S1 is provided, and can be applied to the present invention.

[0055] In Figure 4 the example shown in [the figure], the gap S2 is ensured by forming a second surface 1121 including a step on the surface of the second elastomer 112; however, the present invention is not limited to this form. For example, a form in which a thin plate (second plate) having a thickness of 20 μm or more and 200 μm or less corresponding to the gap S2 is provided between the flexible printed board 114 and the second elastomer 112 also achieves an effect similar to that in the above-described case where the gap S2 is provided, and can be applied to the present invention.

[0056] Figure 5 Part A of Figure 5 and Part B of Figure 5 are diagrams respectively illustrating the outer shape of the contact surface between the first elastomer 111 and the piezoelectric element 113 and the outer shape of the contact surface between the second elastomer 112 and the flexible printed board 114 according to the first exemplary embodiment of the present invention when viewed from the axial direction (Z direction) of the vibrator 110. In Figure 5In part B of, Figure 2 and Figure 4 Components similar to those shown in are denoted by the same reference numerals. Additionally, Figure 5 Part A of Figure 5 and part B of Figure 2 illustrate an XYZ coordinate system corresponding to the XYZ coordinate system shown in.

[0057] More specifically, Figure 5 Part A of is a diagram showing the outline 1112 (shown by a dotted line) of the contact surface between the first elastic body 111 and the piezoelectric element 113 shown in Figure 2 and Figure 4 when viewed from the Z direction, and the piezoelectric element 113 (shown by a solid line). When viewed from the Z direction, the outline of the piezoelectric element 113 is a rectangle (more specifically, a square) having four vertices 1131 to 1134. In the present exemplary embodiment, when viewed from the Z direction, the outline 1112 of the contact surface between the first elastic body 111 and the piezoelectric element 113 is a circle inscribed in the piezoelectric element 113. Additionally, in the present exemplary embodiment, as shown in Figure 5 part A of, the outline 1112 of the contact surface between the first elastic body 111 and the piezoelectric element 113 is inside the vertices 1131 to 1134 of the rectangle of the piezoelectric element 113. This indicates that, in the present exemplary embodiment, the first elastic body 111 does not contact the vertices 1131 to 1134 of the rectangle of the piezoelectric element 113. Thus, even when the piezoelectric element 113 is formed into a rectangle from the perspective of reducing the above-mentioned manufacturing cost, the radial distance from the axial center on the contact surface between the piezoelectric element 113 and the first elastic body 111 can be reduced, and the vibrator 110 can be vibrated efficiently.

[0058] In the case where the above-mentioned first thin plate is provided in the form between the first elastic body 111 and the piezoelectric element 113, a form is adopted in which the first thin plate does not contact the vertices 1131 to 1134 of the rectangle of the piezoelectric element 113.

[0059] Figure 5 Part B of is a diagram showing the outline 1122 (shown by a dotted line) of the contact surface between the second elastic body 112 and the flexible printed board 114 shown in Figure 2 and Figure 4 when viewed from the Z direction, and the piezoelectric element 113 (shown by a solid line). Similar to Figure 5As in part A, when viewed from the Z direction, the outer shape of the piezoelectric element 113 is a rectangle (more specifically, a square) having four vertices 1131 to 1134. In the present exemplary embodiment, when viewed from the Z direction, the outer shape 1122 of the contact surface of the second elastic body 112 with the flexible printed board 114 is a circle inscribed in the piezoelectric element 113. Further, in the present exemplary embodiment, as Figure 5 shown in part B, the outer shape 1122 of the contact surface of the second elastic body 112 with the flexible printed board 114 is inside the vertices 1131 to 1134 of the rectangle of the piezoelectric element 113. As Figure 2 , Figure 4 and Figure 5 shown in part B, the second elastic body 112 does not contact the vertices 1131 to 1134 of the rectangle of the piezoelectric element 113.

[0060] Figure 6 is a cross-sectional view (XY plane) of a cross-section of the piezoelectric element 113 perpendicular to the axis direction (Z direction) of the vibrator 110 according to the first exemplary embodiment of the present invention. In Figure 6 , components similar to the components shown in part A of Figure 2 , Figure 5 and part B of Figure 5 are denoted by the same reference numerals. Figure 6 illustrates an XYZ coordinate system corresponding to the XYZ coordinate system shown in part A of Figure 2 , Figure 5 and part B of Figure 5 .

[0061] As Figure 6 shown, the piezoelectric element 113 includes an inner layer electrode 1135 (illustrated by hatched lines) and a non-electrode portion 1136 that does not include the inner layer electrode 1135. In the present exemplary embodiment, the inner layer electrode 1135 is deployed while being divided into four parts by the diagonal lines connecting the vertices 1131 to 1134 of the rectangle of the piezoelectric element 113. In the piezoelectric element 113, the portion provided with the inner layer electrode 1135 is polarized. Thus, this portion serves as an active portion that generates displacement by the application of voltage. On the other hand, in the piezoelectric element 113, the non-electrode portion 1136 that does not include the inner layer electrode 1135 is not polarized. Thus, the non-electrode portion 1136 serves as an inactive portion that does not generate displacement even when voltage is applied to the piezoelectric element 113. In other words, in the present exemplary embodiment, the vicinity of the vertices 1131 to 1134 of the rectangle including the piezoelectric element 113 is not polarized. Substantially, via-hole electrodes are deployed to conduct the inner layer electrode 1135; however, in Figure 6The illustration of the through-hole electrode is omitted. In the case where the piezoelectric element 113 is a stacked piezoelectric element, the inner electrode 1135 and the piezoelectric body are generally sintered integrally. Therefore, as the material of the inner electrode 1135, it is necessary to use expensive noble metals with high heat-resistant temperatures, such as platinum and palladium-silver alloys. Regarding this problem, in the present exemplary embodiment, as Figure 6 shown, the inner electrode 1135 is not provided over the entire rectangle of the piezoelectric element 113 to minimize the electrode material cost.

[0062] However, in this state, the non-electrode portion 1136, which is an inactive portion that does not contribute to vibration, contacts the first elastic body 111 and the second elastic body 112, and thus, the vibration efficiency deteriorates. Therefore, in the present exemplary embodiment, Figure 6 the size of the outer diameter of the inner electrode 1135 of the piezoelectric element 113 shown in Figure 5 the A portion of Figure 5 and the size of the outer diameter of the outer shapes 1112 and 1122 shown in the B portion of Figure 6 are defined as follows. More specifically, in the present exemplary embodiment, the size of the outer diameter of the inner electrode 1135 (at least a part of the inner electrode 1135) shown in Figure 5 is made to be the same as the size of the outer diameter of the outer shape 1112 of the contact surface of the first elastic body 111 and the piezoelectric element shown in the A portion of Figure 6 . Further, in the present exemplary embodiment, the size of the outer diameter of the inner electrode 1135 (at least a part of the inner electrode 1135) shown in Figure 5 is made to be the same as the size of the outer diameter of the outer shape 1122 of the contact surface of the second elastic body 112 and the flexible printed board 114 shown in the B portion of

[0063] Figure 7 is a characteristic diagram showing the actually measured relationship between the speed (rotational speed) and the electric power of the vibration wave motor in the case where the gaps S1 and S2 shown in Figure 4 are provided and in the case where the gaps S1 and S2 shown in Figure 4 are not provided.

[0064] Figure 7Characteristic 710 indicated by the dotted line in the figure shows the relationship between the speed (rotation speed) and the electric power of a vibration wave motor using a cylindrical piezoelectric element according to a comparative example. In a vibration wave motor using a cylindrical piezoelectric element according to a comparative example, excellent electric power is achieved, but the manufacturing cost increases because rounding processing is necessary as the external shape processing of the cylindrical piezoelectric element.

[0065] Figure 7 Characteristic 720 indicated by the line with cross marks at both ends in the figure shows the relationship between the speed (rotation speed) and the electric power of a vibration wave motor that does not have Figure 4 the gap S1 and the gap S2 shown therein according to a comparative example. As understood from characteristic 720, in a vibration wave motor that does not have the gap S1 and the gap S2 according to a comparative example, the electric power becomes the highest.

[0066] Figure 7 Characteristic 730 indicated by the line with triangular marks at both ends in the figure shows the relationship between the speed (rotation speed) and the electric power of a vibration wave motor having Figure 4 the gap S1 shown therein and not having the gap S2 according to an exemplary embodiment of the present invention. In characteristic 730, the electric power is improved compared with characteristic 720.

[0067] Figure 7 Characteristic 740 indicated by the line with circular marks at both ends in the figure shows the relationship between the speed (rotation speed) and the electric power of a vibration wave motor having Figure 4 the gap S1 and the gap S2 shown therein according to an exemplary embodiment of the present invention. Characteristic 740 achieves an electric power equal to or less than the electric power in characteristic 710 of a vibration wave motor using a cylindrical piezoelectric element according to a comparative example.

[0068] The vibration wave motor 100 according to the first exemplary embodiment described above includes a first elastic body 111 and a second elastic body 112, a piezoelectric element 113 sandwiched between the first elastic body 111 and the second elastic body 112, and a contact body 120 in pressure contact with the first elastic body 111. The piezoelectric element 113 is an electromechanical energy conversion element. In the vibration wave motor 100 according to the first exemplary embodiment, in the piezoelectric element 113, the outer shape of the cross-section (XY plane) perpendicular to the pressure direction (Z direction or the axial direction of the vibrator 110) in the pressure contact between the first elastic body 111 and the contact body 120 is rectangular. Further, in the vibration wave motor 100 according to the first exemplary embodiment, the vertices 1131 to 1134 of the rectangle of the piezoelectric element 113 do not contact the first elastic body 111.

[0069] With such a configuration, it is possible to provide a vibration wave motor that can efficiently perform vibration (with high driving efficiency) while reducing the manufacturing cost.

[0070] Further, in the vibration wave motor 100 according to the first exemplary embodiment, the vertices 1131 to 1134 of the rectangle of the piezoelectric element 113 do not contact the second elastic body 112.

[0071] With such a configuration, it is possible to provide a vibration wave motor that can perform vibration more efficiently (with higher driving efficiency) while reducing manufacturing costs.

[0072] (Second Exemplary Embodiment)

[0073] The second exemplary embodiment is described. In the description of the second exemplary embodiment described below, the description of matters common to the above-described first exemplary embodiment is omitted, and matters different from the above-described first exemplary embodiment are mainly described.

[0074] In the above-described first exemplary embodiment, Figure 5 the outer shape 1112 of the contact surface of the first elastic body 111 with the piezoelectric element 113 shown in part A of

[0075] Figure 8A and Figure 8B are diagrams showing the outer shape of the contact surface of the first elastic body 111 with the piezoelectric element 113 according to the second exemplary embodiment of the present invention when viewed from the axial direction (Z direction) of the vibrator 110. In Figure 8A and Figure 8B components similar to those shown in part A of Figure 5 are denoted by the same reference numerals. Further, Figure 8A and Figure 8B show the XYZ coordinate system corresponding to the XYZ coordinate system shown in part A of Figure 5 . More specifically, Figure 8A and Figure 8B are diagrams of the outer shape 1112 (shown by a dotted line) of the contact surface of the first elastic body 111 with the piezoelectric element 113 and the piezoelectric element 113 (shown by a solid line) shown in Figure 2 and Figure 4 when viewed from the Z direction.

[0076] First, in the first example of the second exemplary embodiment shown in Figure 8A the outer shape 1112 of the contact surface of the first elastic body 111 with the piezoelectric element 113 is a circle, and the outer diameter of the circle is longer than the length of one side of the rectangle (more specifically, a square) that is the outer shape of the piezoelectric element 113. Further, as shown in Figure 8AAs shown in [the figure], the circle of the outer shape 1112 of the contact surface of the first elastomer 111 and the piezoelectric element 113 is inside the vertices 1131 to 1134 of the rectangle that is the outer shape of the piezoelectric element 113. In the case of the first example of the second exemplary embodiment, it is necessary to increase the outer diameter of the inner layer electrode 1135 so that Figure 6 the non-electrode portion 1136, which is the inactive portion of the piezoelectric element 113 as shown in [the figure], does not contact the first elastomer 111. In addition, in the first example of the second exemplary embodiment, the relationship between the outer shape of the contact surface of the second elastomer 112 and the flexible printed board 114 and the piezoelectric element 113 is also similar to Figure 8A the relationship between the outer shape 1112 and the piezoelectric element 113 as shown in [the figure].

[0077] In Figure 8B the second example of the second exemplary embodiment shown in [the figure], the outer shape 1112 of the contact surface of the first elastomer 111 and the piezoelectric element 113 is a circle, and the outer diameter of the circle is shorter than the length of one side of the rectangle (more specifically, a square) that is the outer shape of the piezoelectric element 113. In addition, in the second example of the second exemplary embodiment, the relationship between the outer shape of the contact surface of the second elastomer 112 and the flexible printed board 114 and the piezoelectric element 113 is also similar to Figure 8B the relationship between the outer shape 1112 and the piezoelectric element 113 as shown in [the figure].

[0078] The second exemplary embodiment can also achieve an effect similar to that of the above-described first exemplary embodiment.

[0079] (Third Exemplary Embodiment)

[0080] Describe the third exemplary embodiment. In the description of the third exemplary embodiment described below, the description of matters common to the above-described first and second exemplary embodiments is omitted, and matters different from the above-described first and second exemplary embodiments are mainly described.

[0081] In the above-described first exemplary embodiment, the arrangement example of the inner layer electrode 1135 in the piezoelectric element 113 shown in Figure 6 [the figure] was described. In the second exemplary embodiment, an arrangement example of the inner layer electrode 1135 different from the arrangement example according to the first exemplary embodiment is described.

[0082] Figures 9A to 9C is a cross-sectional view (XY plane) of the piezoelectric element 113 perpendicular to the axis direction (Z direction) of the vibrator 110 according to the third exemplary embodiment of the present invention. In Figures 9A to 9C [the figure], components similar to the components shown in Figure 6 [the figure] are denoted by the same reference numerals. In addition, Figures 9A to 9C it is illustrated that Figure 6The XYZ coordinate system corresponding to the XYZ coordinate system shown in

[0083] In Figure 9A In the first example of the third exemplary embodiment shown in , the inner electrode 1135 is divided into four parts by lines connecting the approximate midpoints of the mutually facing sides of a rectangle (more specifically, a square) that forms the outer shape of the piezoelectric element 113. The first example of the third exemplary embodiment can also achieve an effect similar to that of the first exemplary embodiment described above.

[0084] In Figure 9B In the second example of the third exemplary embodiment shown in , the inner electrode 1135 extends over the entire surface of a rectangle (more specifically, a square) that forms the outer shape of the piezoelectric element 113. In the second example of the third exemplary embodiment, similar to Figure 6 the first exemplary embodiment shown in , the inner electrode 1135 is deployed while being divided into four parts by the diagonal line connecting the vertices 1131 to 1134 of the rectangle that forms the outer shape of the piezoelectric element 113. In Figure 9B the second example of the third exemplary embodiment shown in , the amount of electrode material increases because the inner electrode 1135 extends over the entire surface of the rectangle that forms the outer shape of the piezoelectric element 113, but a greater force can be generated compared to the forces in the first examples of the first to third exemplary embodiments described above.

[0085] In Figure 9C In the third example of the third exemplary embodiment shown in , similar to Figure 9B the second example of the third exemplary embodiment shown in , the inner electrode 1135 extends over the entire surface of a rectangle (more specifically, a square) that forms the outer shape of the piezoelectric element 113. In the third example of the third exemplary embodiment, similar to Figure 9A the first example of the third exemplary embodiment shown in , the inner electrode 1135 is divided into four parts by lines connecting the approximate midpoints of the mutually facing sides of a rectangle (more specifically, a square) that forms the outer shape of the piezoelectric element 113. The third example of the third exemplary embodiment can also achieve an effect similar to that of Figure 9B the second example of the third exemplary embodiment shown in . In other words, the amount of electrode material increases because the inner electrode 1135 extends over the entire surface of the rectangle that forms the outer shape of the piezoelectric element 113, but a greater force can be generated compared to the first examples of the first to third exemplary embodiments described above.

[0086] (Fourth Exemplary Embodiment)

[0087] Describe a fourth exemplary embodiment. In the description of the fourth exemplary embodiment described below, descriptions of matters common to the above-described first to third exemplary embodiments are omitted, and matters different from the above-described first to third exemplary embodiments are mainly described.

[0088] In the fourth exemplary embodiment, a drive device including the vibration wave motor 100 according to any one of the above-described first to third exemplary embodiments and driven by the vibration wave motor 100 is described.

[0089] Figure 10A and Figure 10B is a diagram illustrating an example of a schematic configuration of an imaging device 200 to which the drive device according to the fourth exemplary embodiment of the present invention is applied. The vibration wave motor 100 according to any one of the above-described first to third exemplary embodiments can be used, for example, to drive a lens of an imaging device (an optical device or an electronic device) 200. In the fourth exemplary embodiment, an imaging device 200 including the vibration wave motor 100 that drives a lens unit as an optical member deployed in a lens barrel 220 is described.

[0090] Figure 10A is a top view illustrating an example of a schematic configuration of an imaging device 200 to which the drive device according to the fourth exemplary embodiment is applied. As Figure 10A shown, the imaging device 200 includes a camera body 210 and a lens barrel 220. The camera body 210 includes an imaging element 211, a power button 212, etc. The lens barrel 220 includes a first lens unit ( Figure 10A not shown in the figure), a second lens unit 222, a third lens unit ( Figure 10A not shown in the figure), a fourth lens unit 224, a vibration wave motor 100-2, a vibration wave motor 100-4, etc. Each of the vibration wave motors 100-2 and 100-4 corresponds to the vibration wave motor 100 according to any one of the above-described first to third exemplary embodiments, but may further include other components such as a drive circuit in addition to the components of the vibration wave motor 100 according to any one of the above-described first to third exemplary embodiments. In the imaging device 200, the vibration wave motor 100-2 drives the second lens unit 222, and the vibration wave motor 100-4 drives the fourth lens unit 224. In the imaging device 200, the lens barrel 220 can be replaced as an interchangeable lens, and a lens barrel 220 suitable for an imaging object can be attached to the camera body 210.

[0091] In the vibration wave motor 100-2, a rotor including a contact body 120 and a rotor main ring 130 is deployed inside the lens barrel 220 such that the radial direction is along the optical axis ( Figure 10Bis substantially orthogonal (illustrated by long and short dashed lines). In the vibration wave motor 100-2, a rotor including a contact body 120 and a rotor main ring 130 rotates around the optical axis, and the rotational output of the contact body 120 is converted into linear motion in the optical axis direction through a gear 160 or the like, thereby moving the second lens unit 222 in the optical axis direction. In the vibration wave motor 100-4, the fourth lens unit 224 is also moved in the optical axis direction through a configuration and operation similar to those of the vibration wave motor 100-2.

[0092] Figure 10B is a block diagram showing an example of a schematic configuration of an imaging device 200 applied as a driving device according to the fourth exemplary embodiment. In Figure 10B , components similar to those shown in Figure 10A are denoted by the same reference numerals.

[0093] Figure 10B The first lens unit 221, the second lens unit 222, the third lens unit 223, the fourth lens unit 224, and the light quantity adjustment unit 225 shown in Figure 10A are disposed at corresponding predetermined positions on the optical axis inside the lens barrel 220 shown in Figure 10B . In

[0094] The CPU 233 is a control circuit that controls the overall operation of the imaging device 200 and generates control signals for exposure determination and focusing from the acquired image signal. The CPU 233 controls the driving of the vibration wave motors 100-2, 100-4, and the meter 236 to obtain a determined exposure and an appropriate focusing state. Through the driving control of the vibration wave motors 100-2, 100-4, and the meter 236 by the CPU 233, the corresponding positions of the second lens unit 222, the fourth lens unit 224, and the light quantity adjustment unit 225 in the optical axis direction are adjusted. More specifically, the vibration wave motor 100-2 moves the second lens unit 222 in the optical axis direction under the control of the CPU 233. The vibration wave motor 100-4 moves the fourth lens unit 224 in the optical axis direction under the control of the CPU 233. The meter 236 moves the light quantity adjustment unit 225 in the optical axis direction under the control of the CPU 233.

[0095] The position of the second lens unit 222 driven by the vibration wave motor 100-2 in the optical axis direction is detected by the first linear encoder 237, and the detection result is transmitted to the CPU 233 and fed back to the driving of the vibration wave motor 100-2. Similarly, the position of the fourth lens unit 224 driven by the vibration wave motor 100-4 in the optical axis direction is detected by the second linear encoder 238, and the detection result is transmitted to the CPU 233 and fed back to the driving of the vibration wave motor 100-4. The position of the light quantity adjustment unit 225 driven by the meter 236 in the optical axis direction is detected by the aperture encoder 239, and the detection result is transmitted to the CPU 233 and fed back to the driving of the meter 236.

[0096] The above exemplary embodiments of the present invention are merely specific examples for implementing the present invention, and the technical scope of the present invention is not limitedly interpreted thereby. In other words, the present invention can be implemented in various forms without departing from the technical idea or main features of the present invention.

[0097] The disclosure of the exemplary embodiments of the present invention includes the following configurations.

[0098] [Configuration 1]

[0099] A vibration wave motor, comprising:

[0100] A first elastic body and a second elastic body;

[0101] An electromechanical energy conversion element sandwiched between the first elastic body and the second elastic body; and

[0102] A contact body configured to be in pressure contact with the first elastic body,

[0103] Among them, in the electromechanical energy conversion element, the outer shape of the cross-section perpendicular to the pressure direction in the pressure contact is rectangular, and

[0104] the vertices of the rectangle of the electromechanical energy conversion element do not contact the first elastic body.

[0105] [Configuration 2]

[0106] The vibration wave motor according to Configuration 1, wherein the vertices of the rectangle of the electromechanical energy conversion element do not contact the second elastic body.

[0107] [Configuration 3]

[0108] The vibration wave motor according to Configuration 1 or 2, further comprising a flexible printed circuit board provided between the electromechanical energy conversion element and the second elastic body,

[0109] wherein when viewed from the pressure direction, the contact surface of the second elastic body and the flexible printed circuit board is inside the vertices of the rectangle of the electromechanical energy conversion element.

[0110] [Configuration 4]

[0111] The vibration wave motor according to Configuration 3, wherein the outer shape of the contact surface of the second elastic body and the flexible printed circuit board is circular.

[0112] [Configuration 5]

[0113] The vibration wave motor according to Configuration 3 or 4,

[0114] wherein in the outer shape adjacent region of the outer shape of the electromechanical energy conversion element on the electromechanical energy conversion element side, the first elastic body includes a first surface, and the first surface includes a gap S1 between the first elastic body and the electromechanical energy conversion element,

[0115] wherein in the outer shape adjacent region of the outer shape of the electromechanical energy conversion element on the flexible printed circuit board side, the second elastic body includes a second surface, and the second surface includes a gap S2 between the second elastic body and the flexible printed circuit board, and

[0116] wherein the size of each of the gap S1 and the gap S2 is 20 μm or more and 200 μm or less.

[0117] [Configuration 6]

[0118] The vibration wave motor according to any one of Configurations 1 to 5, wherein the outer shape of the contact surface of the first elastic body and the electromechanical energy conversion element is circular.

[0119] [Configuration 7]

[0120] The vibration wave motor according to any one of Configurations 1 to 6, wherein the vicinity of the vertex of the rectangle including the electromechanical energy conversion element is not polarized.

[0121] [Configuration 8]

[0122] The vibration wave motor according to any one of Configurations 1 to 7, wherein the outer diameter of at least a part of the inner layer electrode of the electromechanical energy conversion element is the same as the outer diameter of the contact surface between the first elastic body and the electromechanical energy conversion element.

[0123] [Configuration 9]

[0124] The vibration wave motor according to any one of Configurations 1 to 8, wherein the outer diameter of at least a part of the inner layer electrode of the electromechanical energy conversion element is the same as the outer diameter of the contact surface between the second elastic body and the electromechanical energy conversion element.

[0125] [Configuration 10]

[0126] The vibration wave motor according to any one of Configurations 1 to 9, wherein the rectangle of the electromechanical energy conversion element is a square.

[0127] [Configuration 11]

[0128] The vibration wave motor according to any one of Configurations 1 to 10, further comprising a thin plate provided between the first elastic body and the electromechanical energy conversion element and having a thickness of 20 μm or more and 200 μm or less, and the thin plate does not contact the vertex of the rectangle of the electromechanical energy conversion element.

[0129] [Configuration 12]

[0130] A drive device, comprising:

[0131] The vibration wave motor according to any one of Configurations 1 to 11; and

[0132] A member configured to be driven by the vibration wave motor.

[0133] [Configuration 13]

[0134] The drive device according to Configuration 12, wherein the member is a lens.

[0135] The present invention is not limited to the above-described exemplary embodiments, and various changes and modifications can be made without departing from the spirit and scope of the present invention. Therefore, in order to inform the public of the scope of the present invention, the appended claims are presented.

[0136] This application is based on and claims the priority benefit of the prior Japanese Patent Application No. 2022-139298 filed on September 1, 2022, the entire content of which is incorporated herein by reference.

[0137] List of Reference Signs

[0138] 100 Vibration Wave Motor

[0139] 110 Vibrator

[0140] 111 First Elastic Body

[0141] 112 Second Elastic Body

[0142] 113 Piezoelectric Element (Electromechanical Energy Conversion Element)

[0143] 114 Flexible Printed Circuit Board

[0144] 115 Shaft

[0145] 116 Nut

[0146] 120 Contact Body

[0147] 130 Rotor Main Ring

[0148] 140 Rubber

[0149] 150 Pressure Spring

[0150] 160 Gear

[0151] 170 Flange Cap

[0152] 180 Flange

[0153] 190 Nut

[0154] 1111 First Surface of the First Elastic Body 111

[0155] 1112 Outer Shape of the Contact Surface between the First Elastic Body 111 and the Piezoelectric Element 113

[0156] 1121 Second Surface of the Second Elastic Body 112

[0157] 1122 Outer Shape of the Contact Surface between the Second Elastic Body 112 and the Flexible Printed Circuit Board 114

[0158] 1131 to 1134 Vertices of the Rectangle as the Outer Shape of the Piezoelectric Element 113

[0159] 1135 Inner Layer Electrode of the Piezoelectric Element 113

[0160] 1136 Non-Electrode Portion of the Piezoelectric Element 113

[0161] S1 gap

[0162] S2 gap.

Claims

1. A vibration wave motor, comprising: a first elastic body and a second elastic body; an electromechanical energy conversion element sandwiched between the first elastic body and the second elastic body; and a contact body configured to be in pressure contact with the first elastic body, wherein, in the electromechanical energy conversion element, the outer shape of a cross-section perpendicular to the pressure direction is rectangular, wherein a gap is provided at a position where the electromechanical energy conversion element and the first elastic body face each other in the pressure direction, and wherein the vertices of the rectangle of the electromechanical energy conversion element do not contact the first elastic body at the gap.

2. The vibration wave motor according to claim 1, wherein the vertices of the rectangle of the electromechanical energy conversion element do not contact the second elastic body.

3. The vibration wave motor according to claim 1, further comprising a flexible printed board provided between the electromechanical energy conversion element and the second elastic body, wherein, when viewed from the pressure direction, the contact surface of the second elastic body and the flexible printed board is inside the vertices of the rectangle of the electromechanical energy conversion element.

4. The vibration wave motor according to claim 3, wherein the outer shape of the contact surface of the second elastic body and the flexible printed board is circular.

5. The vibration wave motor according to claim 3, wherein in a region adjacent to the outer shape of the electromechanical energy conversion element on the side of the electromechanical energy conversion element, the first elastic body includes a first surface, and the first surface includes a gap S1 serving as a gap between the first elastic body and the electromechanical energy conversion element, wherein in a region adjacent to the outer shape of the electromechanical energy conversion element on the side of the flexible printed board, the second elastic body includes a second surface, and the second surface includes a gap S2 between the second elastic body and the flexible printed board, and wherein the size of each of the gap S1 and the gap S2 is 20 μm or more and 200 μm or less.

6. The vibration wave motor according to claim 1, wherein the outer shape of the contact surface of the first elastic body and the electromechanical energy conversion element is circular.

7. The vibration wave motor according to claim 1, wherein a region adjacent to the vertices of the rectangle including the electromechanical energy conversion element is not polarized.

8. The vibration wave motor according to claim 1, wherein the size of the outer diameter of at least a part of the inner layer electrode of the electromechanical energy conversion element is the same as the size of the outer diameter of the contact surface of the first elastic body and the electromechanical energy conversion element.

9. The vibration wave motor according to claim 1, wherein the size of the outer diameter of at least a part of the inner layer electrode of the electromechanical energy conversion element is the same as the size of the outer diameter of the contact surface of the second elastic body and the electromechanical energy conversion element.

10. The vibration wave motor according to claim 1, wherein the rectangle of the electromechanical energy conversion element is a square.

11. The vibration wave motor according to claim 1 further includes a thin plate provided between the first elastic body and the electromechanical energy conversion element and having a thickness of 20 μm or more and 200 μm or less, and the thin plate does not contact the vertices of the rectangle of the electromechanical energy conversion element.

12. A driving device, comprising: the vibration wave motor according to any one of claims 1 to 11; and a member configured to be driven by the vibration wave motor.

13. The driving device according to claim 12, wherein the member is a lens.

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