JP2019033627A - Vibrator, ultrasonic motor, and method of manufacturing vibrator - Google Patents

Abstract

To provide a vibrator capable of preventing peeling of a piezoelectric element from an elastic body.SOLUTION: A vibrator 30 includes: an elastic body 10; and a piezoelectric element 20 joined to the elastic body 10. The elastic body 10 has two partially formed projections 11. The piezoelectric element 20 and the elastic body 10 are joined to form a closed gap 18 inside each projection 11. The piezoelectric element 20 has two through-holes 21 for communicating the respective gaps 18 with the outside.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a vibrator having an electromechanical energy conversion element, an ultrasonic motor, and a method for manufacturing the vibrator.

  A vibrator in which a piezoelectric element as an electro-mechanical energy conversion element and an elastic body mainly made of metal are joined is known. In this vibrator, a piezoelectric element is excited by application of a high-frequency voltage to generate a plurality of vibration modes, and these vibration modes are combined to generate an elliptical motion at the tip of the protrusion formed on the elastic body. Such a vibrator is provided in an ultrasonic motor or a vibration wave motor, and these motors are used as actuators that relatively drive a driven body that contacts the vibrator. As such an actuator, a vibrator 123 (FIG. 14) formed by joining the piezoelectric element 120 to an elastic body 122 having two projecting portions 121, and a driven member that is in pressure contact with the vibrator 123. An ultrasonic motor provided is known. In this ultrasonic motor, since the two protrusions 121 are formed on the plate-like elastic body 122 by pressing, the manufacturing accuracy of the vibrator 123 can be reduced by improving the processing accuracy, and the performance can be stabilized. (For example, refer to Patent Document 1). In the vibrator 123, when the piezoelectric element 120 is joined to the elastic body 122, a sealed gap portion 124 is formed inside each protrusion 121.

JP2015-106927A

  By the way, there are various environments in which a device to which the ultrasonic motor of Patent Document 1 is applied is used. For example, the device may be used in an environment where the temperature is higher than room temperature. At this time, the air sealed in the gap portion 124 expands, the internal pressure of the gap portion 124 increases, and a peeling force for peeling the piezoelectric element 120 and the elastic body 122 is generated as indicated by the arrow in FIG. For example, as shown in FIG. 16, the internal pressure of the gap 124 is based on the internal pressure when the temperature is 20 ° C. When the temperature reaches 80 ° C., the relative pressure becomes 1.2 times, and when the temperature reaches 160 ° C. The relative pressure is 1.5 times.

  In addition, a relatively high-strength adhesive is used for joining the piezoelectric element 120 and the elastic body 122. However, the adhesive strength of such an adhesive decreases in an environment where the temperature is high. For example, as shown in FIG. 17, the adhesive strength of a certain adhesive is about 20 when the temperature reaches 80 ° C. when the temperature is normal temperature (20 ° C. to 30 ° C.). %descend.

  That is, in the high-temperature environment, the ultrasonic motor including the vibrator 123 is subjected to double peeling factors such as an increase in the internal pressure of the gap portion 124 and a decrease in the adhesive strength of the adhesive, and the piezoelectric element 120 is peeled from the elastic body 122. Problem arises.

  An object of the present invention is to provide a vibrator, an ultrasonic motor, and a vibrator manufacturing method capable of preventing a piezoelectric element from peeling from an elastic body.

  In order to achieve the above object, the vibrator of the present invention includes an elastic body having a protrusion and an electro-mechanical energy conversion element in contact with one surface of the elastic body, A gap is formed between the energy conversion element and the protrusion, and the electro-mechanical energy conversion element has a through-hole penetrating the electro-mechanical energy conversion element.

  In order to achieve the above object, the vibrator according to the present invention includes an elastic body having a protrusion and an electromechanical energy conversion element in contact with one surface of the elastic body. A gap is formed between the mechanical energy conversion element and the protrusion, and the elastic body and the electro-mechanical energy conversion element are not in contact with each other, extending from the gap to the end of the vibrator. It has the area | region which has.

  According to the present invention, it is possible to prevent the piezoelectric element from peeling from the elastic body.

It is a perspective view which shows the elastic body with which the vibrator | oscillator which concerns on embodiment of this invention is provided. It is a figure which shows the piezoelectric element with which the vibrator | oscillator which concerns on embodiment of this invention is provided. FIG. 4 is a cross-sectional view schematically showing a configuration of a vibrator according to an embodiment of the present invention. FIG. 5 is a bottom view showing a state in which a flexible printed board is bonded to a piezoelectric element in the vibrator according to the embodiment of the present invention. It is a figure for demonstrating the manufacturing method of the piezoelectric element of FIG. FIG. 3 is an enlarged cross-sectional view showing a configuration in the vicinity of a through hole in the piezoelectric element of FIG. 2. It is a disassembled perspective view which shows the structure of the ultrasonic motor which concerns on embodiment of this invention. It is a perspective view which shows the structure of the vibrator holder in FIG. It is an enlarged view of the part looked along the arrow A in FIG. FIG. 8 is a partial cross-sectional view of a lens barrel to which the ultrasonic motor of FIG. 7 is applied. It is an expanded sectional view which shows the structure of the vicinity of the through-hole in the modification of a piezoelectric element. It is sectional drawing which shows schematically the structure of the 1st modification of a vibrator | oscillator. It is a perspective view showing roughly the composition of the 2nd modification of a vibrator. It is sectional drawing which shows the structure of the conventional vibrator | oscillator schematically. It is an expanded partial sectional view which shows roughly the structure of the projection part vicinity of the elastic body in the conventional vibrator | oscillator. It is a graph which shows the relationship between the pressure and temperature of the space | gap part inside the protrusion part of an elastic body. It is a graph which shows the relationship between the adhesive strength of the adhesive agent used for joining of an elastic body, and a piezoelectric element, and temperature.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the configurations described in the following embodiments are merely examples, and the scope of the present invention is not limited by the configurations described in the embodiments. First, the vibrator according to the present embodiment will be described.

  FIG. 1 is a perspective view showing an elastic body provided in the vibrator according to the present embodiment. 2A and 2B are diagrams showing a piezoelectric element included in the vibrator according to the present embodiment, FIG. 2A is a plan view, and FIG. 2B is a line II in FIG. 2A. It is sectional drawing which follows, and FIG.2 (C) is a bottom view. FIG. 3 is a cross-sectional view schematically showing the configuration of the vibrator according to the present embodiment. FIG. 4 is a bottom view showing a state in which the flexible printed circuit board is bonded to the piezoelectric element in the vibrator according to the present embodiment.

  The elastic body 10 is made of a metal plate, for example, a thin plate of SUS420J2 (for example, a thickness of 0.3 mm). The elastic body 10 includes a substantially rectangular central portion 13, two protruding portions 11 (dents) partially protruding from the central portion 13 in the plate thickness direction, and girders extending in the longitudinal direction from both ends of the central portion 13. Two support portions 14 in the form of a ring. A joint portion 15 having a substantially cross shape in plan view is formed at the tip of each support portion 14, and a round hole 16 or a long hole 17 penetrating the joint portion 15 is formed in each of the two joint portions 15. The two protrusions 11 are arranged along the longitudinal direction of the central portion 13 and have a contact portion 12 at the tip. The two protrusions 11 protrude on the opposite side of the central portion 13 from the side in contact with a piezoelectric element 20 described later. In the elastic body 10, the protrusions 11, the central portion 13, the support portions 14, and the coupling portions 15 (round holes 16 and long holes 17) are integrally formed through press working on a metal plate. The piezoelectric element 20 is composed of a piezoelectric element that is an electro-mechanical energy conversion element, and has a substantially rectangular shape that is substantially the same shape as the central portion 13. The piezoelectric element 20 includes a piezoelectric body portion 22 serving as a base, a first electrode 23, a second electrode 24, and a connecting electrode 25. The first electrode 23 is a thin film electrode that substantially covers the upper surface of the piezoelectric body portion 22. The second electrode 24 is a thin film electrode that substantially covers the lower surface of the piezoelectric body portion 22, and is divided into two electrodes along the center line in the short direction of the piezoelectric element 20. The connecting electrode 25 is formed so as to be sandwiched between two divided second electrodes 24 on the lower surface of the piezoelectric body portion 22. The piezoelectric element 20 is polarized in the thickness direction by forming a high-voltage electric field between the first electrode 23 and the second electrode 24, and has a polarity in the thickness direction. The piezoelectric element 20 has two through holes 21 that penetrate the piezoelectric body portion 22 in the thickness direction.

  In the present embodiment, the piezoelectric element 20 and the elastic body 10 are bonded to each other by an adhesive or the like to constitute the vibrator 30. At this time, the inside of each protrusion 11 of the elastic body 10 is sealed from the outside to form the gap 18, but in the elastic body 10, the piezoelectric element 20 so that each through hole 21 faces each gap 18. Are joined to the elastic body 10 (second step). Accordingly, each gap 18 communicates with the outside through each through hole 21. In the vibrator 30, a flexible printed circuit board (hereinafter referred to as “FPC”) 40 (power supply body) is bonded to the piezoelectric element 20 so as to be in contact with the second electrode 24 of the piezoelectric element 20. The FPC 40 is formed with two openings 41 penetrating the FPC 40 in the thickness direction, and the FPC 40 is joined to the piezoelectric element 20 so that each opening 41 faces each through hole 21 (third). Process). As a result, the FPC 40 does not block each through hole 21 and communication through each through hole 21 is maintained.

  In the vibrator 30, a high frequency voltage is applied to the piezoelectric element 20 from the power source (not shown) via the FPC 40. Specifically, an alternating voltage having a frequency close to each resonance frequency of the out-of-plane bending vibration mode (mode 1) and the out-of-plane bending vibration mode (mode 2) of the elastic body 10 is divided into two piezoelectric elements 20. Applied to each of the two electrodes 24. As a result, the vibration in the out-of-plane bending vibration mode (mode 1) and the vibration in the out-of-plane bending vibration mode (mode 2) are simultaneously excited in the vibrator 30. Here, the out-of-plane bending vibration mode (mode 1) is a vibration that deforms along the short direction of the piezoelectric element 20, and the protrusion 30 is sandwiched between the vibrator 30 and substantially parallel to the longitudinal direction of the piezoelectric element 20. This is a vibration mode in which two nodal lines appear. The out-of-plane bending vibration mode (mode 2) is vibration that is deformed along the longitudinal direction of the piezoelectric element 20, and is a vibration mode in which three nodal lines are generated in the vibrator 30 substantially parallel to the short direction of the piezoelectric element 20. It is. In the vibrator 30, the two protrusions 11 are arranged at a position where the antinode vibration mode (mode 1) becomes an antinode and at a position where the vibration node of the out-of-plane bending vibration mode (mode 2) becomes a vibration node. The The protrusion 11 performs an elliptical motion by combining the vibration in the out-of-plane bending vibration mode (mode 1) and the vibration in the out-of-plane bending vibration mode (mode 2). Since the principle of making it known is well known, a more detailed description is omitted. In the vibrator 30, the driven body is brought into pressure contact with each protrusion 11 that performs the elliptical motion, and the driven body is driven relative to the vibrator 30. At this time, in order to prevent the contact portion 12 of each projection portion 11 from being worn, the elastic body 10 is formed by pressing each projection portion 11 and then subjected to a quenching process, whereby the hardness of each contact portion 12 is determined. To improve.

  The piezoelectric element 20 expands and contracts in the thickness direction and the direction orthogonal to the thickness direction (longitudinal direction, short direction) when a voltage is applied, but when bonded to the elastic body 10, the piezoelectric element 20 mainly extends in the longitudinal direction. Due to the expansion and contraction in the short direction, it deforms so that it can be bent entirely by the bimetal principle. In other words, when an alternating voltage is applied to the piezoelectric element 20, the vibrator 30 is vibrated in an out-of-plane bending vibration mode (mode 1) or an out-of-plane bending vibration mode (mode 2) due to bending deformation. As described above, since the bending vibration is excited in the vibrator 30 by the deformation of the piezoelectric element 20, in order to increase the output (thrust and speed) of the motor using the vibrator 30, the longitudinal direction of the piezoelectric element 20 is used. In addition, it is necessary to increase the deformation force in the short direction. As a method for increasing these deformation forces, it is conceivable to increase the alternating voltage applied to the piezoelectric element 20 or to increase the cross-sectional area of each direction of the piezoelectric element 20. Furthermore, it is conceivable to increase the Young's modulus of the piezoelectric element 20 or to increase the piezoelectric constant of the piezoelectric element 20. Among these methods, the simplest method is to increase the cross-sectional area of each direction of the piezoelectric element 20. Therefore, in the present embodiment, the thickness of the piezoelectric element 20 is increased. The thickness of 20 is set to 0.47 mm.

  As described above, in the vibrator 30, the thickness of the piezoelectric element 20 is set to a relatively large value of 0.47 mm in consideration of increasing the elliptical motion of each protrusion 11. On the other hand, if the piezoelectric element 20 is thick, it may be difficult to drill the through hole 21. Moreover, in order to reduce the influence on the vibration by the through hole 21 and the influence of the stress concentration due to the deformation, the through hole 21 is preferably small. However, for example, when the through-hole 21 is drilled into the thin piezoelectric element 20 having a thickness of about 0.47 mm, the piezoelectric element 20 itself is also a material that is difficult to cut. It is necessary to make the diameter of the hole 21 larger than a predetermined size. Specifically, stable machining may not be possible unless the diameter is 0.3 mm or more. In the present embodiment, correspondingly, each through hole 21 is formed without cutting the piezoelectric body portion 22 with a drill.

  FIG. 5 is a diagram for explaining a method of manufacturing the piezoelectric element of FIG. 6 is an enlarged cross-sectional view showing a configuration in the vicinity of the through hole in the piezoelectric element of FIG. As described above, the piezoelectric element 20 is composed of a piezoelectric element having a thickness of 0.47 mm, but has a laminated structure of thin film piezoelectric sheets. In the manufacturing process of the piezoelectric element 20, first, a green sheet made of a piezoelectric body having a thickness of about 0.06 mm is manufactured, and the green sheet is cut to obtain n piezoelectric sheets 22a (piezoelectric thin films). The size of each piezoelectric sheet 22 a is aligned with the size of the piezoelectric portion 22. Next, two holes 21a that penetrate the piezoelectric sheet 22a in the thickness direction are formed in each piezoelectric sheet 22a. Each hole 21 a is formed so as to correspond to the position of each through hole 21 in the piezoelectric element 20. For example, a Φ0.1 mm drill or punch is used to make each hole 21a. Thereafter, the n piezoelectric sheets 22a in which the holes 21a are formed are stacked and fired so that the holes 21a face each other (first step). Here, a positioning hole (not shown) is provided in each piezoelectric sheet 22a so that the holes 21a are opposed to each other, and a needle-like jig is loosely fitted in the positioning hole of each piezoelectric sheet 22a. By doing so, the piezoelectric sheets 22a may be overlapped. At this time, the laminated piezoelectric sheets 22 a are integrally fired (sintered) to obtain the piezoelectric portion 22, and at the same time, the through holes 21 are formed in the piezoelectric portion 22. Next, the first electrode 23, the second electrode 24, and the connecting electrode 25 are formed on the upper and lower surfaces of the piezoelectric body portion 22 by applying an electrode material (for example, silver) by screen printing and then baking. At this time, the first electrode 23 and the second electrode 24 partially wrap around each through hole 21, but the first electrode 23 and the second electrode 24 do not come into contact with each through hole 21. (FIG. 6) The application amount of the electrode material is adjusted. Thereafter, a high-voltage electric field is formed between the first electrode 23 and the second electrode 24 to perform polarization treatment, and the piezoelectric element 20 is obtained.

  According to the vibrator 30, the piezoelectric element 20 has the through hole 21 that allows the gap 18 to communicate with the outside. Therefore, even if the air sealed in the gap 18 expands, the air in the gap 18 escapes to the outside. It is possible to prevent the internal pressure of the gap 18 from increasing. Thereby, it is possible to prevent the peeling of the piezoelectric element 20 from the elastic body 10 by preventing generation of a peeling force for peeling the piezoelectric element 20 and the elastic body 10. Further, since the FPC 40 joined to the piezoelectric element 20 has an opening 41 and the opening 41 faces the through hole 21, even if the FPC 40 is joined to the piezoelectric element 20, the through hole 21 may be blocked. And the internal pressure of the gap 18 does not increase.

  Further, in the vibrator 30, in order to obtain the piezoelectric part 22 by superimposing a plurality of piezoelectric sheets 22a having two holes 21a penetrating in the thickness direction, the through holes 21 are formed by superimposing the holes 21a. be able to. That is, it is not necessary to process the piezoelectric body portion 22 with a drill to form the through hole 21, and the yield can be prevented from being deteriorated due to breakage of the drill. Further, since it is not necessary to form the through hole 21 by drilling, it is not necessary to make the through hole 21 larger than necessary, and the diameter of the through hole 21 is set to a small value (about 0.1 mm). Can do. Thereby, it is possible to reduce the decrease in rigidity of the piezoelectric element 20, minimize the influence on the vibration mode, and prevent the elliptical motion of each protrusion 11 from being reduced.

  Next, the ultrasonic motor according to the present embodiment will be described. FIG. 7 is an exploded perspective view showing the configuration of the ultrasonic motor according to the present embodiment. FIG. 8 is a perspective view showing the configuration of the vibrator holder in FIG. FIG. 9 is an enlarged view of a portion viewed along an arrow A in FIG. The ultrasonic motor 70 includes a vibrator holding body 72 having a vibrator holding ring 71 and a vibrator 30, a rotor 73 (driven body), a leaf spring 74, a pressure ring 75, and a vibration isolating rubber 76. All of the vibrator holder 72, the rotor 73, the leaf spring 74, the pressure ring 75, and the vibration isolating rubber 76 have an annular shape, and the pressure ring 75, the leaf spring 74, The vibrator holder 72, the rotor 73, and the vibration isolating rubber 76 are stacked in this order. The upper surface of the vibrator holding ring 71 of the vibrator holding body 72 is provided with three recesses 71a at intervals of about 120 °, and the three vibrators 30 are disposed so as to be accommodated in the respective recesses 71a. Pin-like protrusions 71 b and 71 c are formed integrally with the vibrator holding ring 71 on both sides in the circumferential direction of each recess 71 a. When the vibrator 30 is accommodated in the recess 71 a, the pin-like protrusion 71 b engages with the round hole 16 in the elastic body 10 of the vibrator 30, and the pin-like protrusion 71 c contacts the elongated hole 17 in the elastic body 10 of the vibrator 30. Engage. As a result, the position of the vibrator 30 with respect to the concave portion 71a, that is, the vibrator holding ring 71 is defined, and the relative movement of the vibrator 30 with respect to the vibrator holding ring 71 is restricted. A vibration insulating member 90 made of felted breathable is disposed at the bottom of the recess 71a. The vibration insulating member 90 contacts so as not to inhibit the vibration of the vibrator 30 and suppresses the vibration from being transmitted to the vibrator holding ring 71. In the vibrator holder 72, the vibrator 30 is accommodated in the recess 71a so that the FPC 40 of the vibrator 30 contacts the vibration insulation member 90, but the vibration insulation member 90 has air permeability. Therefore, each opening 41 of the FPC 40, and hence each through hole 21 of the piezoelectric element 20 can be ventilated to the outside through the vibration insulating member 90, so that communication with the outside of the gap 18 is maintained. Further, when the vibrator 30 is housed in the recess 71a, the height of the pin-like protrusions 71b and 71c is such that each contact portion 12 of the elastic body 10 of the vibrator 30 is positioned above the pin-like protrusions 71b and 71c. Is set.

  On the lower surface of the rotor 73, for example, a frictional contact portion 73a is formed by performing an anti-wearing process such as a nitriding process. The rotor 73 is disposed so that the friction contact portion 73 a faces the vibrator holder 72. As described above, in the vibrator holding body 72, each contact portion 12 of the elastic body 10 of the vibrator 30 is positioned above the pin-like protrusions 71b and 71c, and thus each contact portion 12 contacts the friction contact portion 73a. . Anti-vibration rubber 76 is in close contact with the upper surface of the rotor 73. The anti-vibration rubber 76 is made of, for example, butyl rubber or neoprene rubber. The anti-vibration rubber 76 is in contact with an output transmission member 104 described later.

  FIG. 10 is a cross-sectional view of a part of a lens barrel to which the ultrasonic motor of FIG. 7 is applied. The lens barrel 100 includes a cylindrical barrel unit main body 101. The lens barrel unit main body 101 has a flange 102 that is perpendicular to the central axis (optical axis) L and protrudes outward at one end. On the flange 102, a manual ring 103 that is manually operated during manual focusing is disposed around the optical axis L. In the lens barrel 100, the ultrasonic motor 70 is disposed around the optical axis L so as to enclose the barrel unit body 101. Furthermore, the annular output transmission member 104 is disposed so as to face the rotor 73 of the ultrasonic motor 70 with the vibration isolating rubber 76 interposed therebetween with the optical axis L as the center. A roller ring 105 is disposed between the output transmission member 104 and the manual ring 103. The roller ring 105 is configured to be rotatable by transmission of driving force from the output transmission member 104 or the manual ring 103. The roller ring 105 has an output key 106 protruding from the end of the lens barrel unit body 101 along the optical axis L. For example, the output key 106 engages with a cam ring (not shown) of the lens barrel 100 and transmits the rotation of the roller ring 105 to the cam ring. The roller ring 105 includes a plurality of roller shafts 107 protruding in the radial direction and wheel-shaped rollers 108 supported by the roller shafts 107.

  The pressure ring 75 of the ultrasonic motor 70 is engaged with the lens barrel unit main body 101 by a screw or bayonet structure on the inner peripheral side. The pressure ring 75 is rotated around the lens barrel unit main body 101 to move along the optical axis L, and the leaf spring 74 is compressed. The compressed leaf spring 74 presses the vibrator holder 72 toward the rotor 73. Thereby, a pressing force acts on the vibrator 30 of the ultrasonic motor 70, and each contact portion 12 of the elastic body 10 in the vibrator 30 comes into pressure contact with the friction contact portion 73a. Here, when an alternating voltage is applied to the FPC 40 of the vibrator 30 and each protrusion 11 performs an elliptical motion, the rotor 73 is driven in the circumferential direction by friction drive, but the output transmission member 104 and the vibration proof are driven to the rotor 73. The roller ring 105 in contact with the rubber 76 also moves in the circumferential direction. At this time, the output key 106 of the roller ring 105 rotates the cam ring to be engaged, thereby realizing an autofocus operation of the lens barrel. Note that the ultrasonic motor 70 may be used not only for the autofocus operation of the lens barrel but also for the zoom operation of the lens barrel, and further, the lens or imaging when driving the image sensor of the camera or correcting camera shake. It may be used to realize driving of the element.

  According to the ultrasonic motor 70, even if the vibrator 30 is accommodated in the recess 71 a of the vibrator holding ring 71 in the vibrator holding body 72, each through hole 21 of the piezoelectric element 20 is externally connected via the vibration insulating member 90. Therefore, communication with the outside of the gap 18 is maintained. Therefore, even if the lens barrel 100 to which the ultrasonic motor 70 is applied is left in a mid-summer car or used in a scorching desert area, the void expanded by heat. The air in the portion 18 can be released to the outside. As a result, it is possible to prevent an increase in the internal pressure of the gap portion 18, and it is possible to prevent the piezoelectric element 20 from peeling from the elastic body 10 in the vibrator 30. Can be prevented.

  As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to embodiment mentioned above, A various deformation | transformation and change are possible within the range of the summary. For example, the through hole 21 has a constant diameter in the thickness direction of the piezoelectric body portion 22, but the diameter of the through hole 21 in the thickness direction of the piezoelectric body portion 22 may not be constant. Specifically, when the piezoelectric body portion 22 is formed by stacking a plurality of piezoelectric sheets 22a, the diameter of the hole 21a formed in each piezoelectric sheet 22a may be changed. In this case, the piezoelectric sheet 22a having the hole 21a having a large diameter is disposed near the surface of the piezoelectric body portion 22, and the diameter is increased as the through hole 21 approaches the surface (upper surface, lower surface) of the piezoelectric body portion 22. As shown, each piezoelectric sheet 22a may be laminated (FIG. 11A). As a result, the diameter of the through hole 21 is reduced toward the center of the thickness of the piezoelectric body portion 22, so that the electrode material applied to form the first electrode 23 and the second electrode 24 is deep into the through hole 21. Inflow can be prevented (FIG. 11B). As a result, the first electrode 23 and the second electrode 24 can be prevented from contacting and short-circuiting. Further, since the diameter of the through hole 21 increases as it approaches the surface of the piezoelectric body portion 22, the through hole 21 may be blocked by the first electrode 23, the second electrode 24, and the FPC 40. Can be reduced. As a result, communication with the outside of each gap 18 can be reliably maintained. In addition, the cross-sectional shape of the through hole 21 shown in FIG. 11A is an example, and the cross-sectional shape of the through hole 21 is not limited to this. Further, the shape of the through hole 21 in the plane perpendicular to the thickness direction of the piezoelectric body portion 22 is not limited to a circle but may be a polygon such as a quadrangle.

  Further, in the vibrator 30, in order to realize communication with the outside of the gap portion 18, the through hole 21 is provided in the piezoelectric element 20, but the through hole 19 that penetrates each projection portion 11 in the thickness direction is provided as an elastic body. 10 may be additionally provided (FIG. 12). Thereby, for example, even if the vibration insulating member 90 is clogged and loses air permeability, and the through hole 21 of the piezoelectric element 20 cannot maintain communication with the outside of the gap portion 18, the through hole 19 of the elastic body 10 can be maintained. Thus, communication with the outside of the gap 18 can be maintained.

  When the vibrator 30 is relatively small, in order to ensure a bonding area between the elastic body 10 and the piezoelectric element 20, a portion corresponding to each protrusion 11 is removed from the surface of the piezoelectric element 20 facing the elastic body 10. It is preferable that an adhesive is applied over the entire surface and bonded to the elastic body 10. However, when the vibrator 30 is relatively large, there is a margin in the bonding area between the elastic body 10 and the piezoelectric element 20, and thus a region where the adhesive is not intentionally applied to the opposing surface of the piezoelectric element 20 may be provided. Thereby, a portion where the elastic body 10 and the piezoelectric element 20 are not joined (unjoined portion) is generated, and when vibration is excited in the vibrator 30, the piezoelectric element 20 is temporarily separated from the elastic body 10 in the unjoined portion. be able to. That is, it is possible to partially generate a mouth opening between the piezoelectric element 20 and the elastic body 10 and to communicate the gap portion 18 with the outside through the mouth opening. Therefore, even if the through hole 21 is not provided in the piezoelectric element 20, the air in the gap portion 18 can be released to the outside, and the internal pressure of the gap portion 18 can be prevented from increasing. In the vibrator 30, the unjoined portion and the through hole 21 may be used in combination.

  Further, in the elastic body 10, the grooves 31 that connect the protrusions 11 and both side edges of the central portion 13 may be formed integrally with the protrusions 11 through press working. The grooves 31 are preferably formed symmetrically with respect to the protrusions 11. Thereafter, when the piezoelectric element 20 is joined to the elastic body 10, as shown in FIG. 13, since the inside of the groove 31 is not joined to the piezoelectric element 20, a region where the elastic body 10 and the piezoelectric element 20 do not contact is formed. This region extends from the gap portion 18 to both side edges of the central portion 13 and functions as a communication path 32 that allows the gap portion 18 to communicate with the outside. Thereby, even if it does not provide the through-hole 21 in the piezoelectric element 20, the air of the space | gap part 18 can be escaped outside, and it can prevent that the internal pressure of the space | gap part 18 rises. In the vibrator 30, the groove 31 (communication path 32) and the through hole 21 may be used in combination. Moreover, in the elastic body 10, although the two support parts 14 are extended in the longitudinal direction from the both ends of the center part 13, the form of the support part 14 is not restricted to this, For example, even if it extends in a transversal direction Good.

DESCRIPTION OF SYMBOLS 10 Elastic body 11 Protrusion part 12 Contact part 18 Cavity part 20 Piezoelectric element 21 Through hole 21a Hole 22a Piezoelectric sheet 30 Vibrator 40 FPC
41 opening 70 ultrasonic motor

Claims (12)

An elastic body having a protrusion;
An electro-mechanical energy conversion element in contact with one surface of the elastic body,
A gap is formed between the electromechanical energy conversion element and the protrusion,
The electro-mechanical energy conversion element has a through-hole penetrating the electro-mechanical energy conversion element.   The vibrator according to claim 1, wherein a power feeder is joined to the electro-mechanical energy conversion element, and the power feeder is provided with an opening at a position overlapping the through hole.   The vibrator according to claim 1, wherein the through hole communicates the gap with the outside.   4. The vibrator according to claim 1, wherein the through hole penetrates the electro-mechanical energy conversion element in a direction perpendicular to the one surface. 5. A vibrator,
An elastic body having a protrusion;
An electro-mechanical energy conversion element in contact with one surface of the elastic body,
A gap is formed between the electromechanical energy conversion element and the protrusion,
A vibrator having a region where the elastic body and the electro-mechanical energy conversion element do not contact with each other and extending from the gap to an end of the vibrator.   The vibrator according to claim 5, wherein the region communicates the gap with the outside. The elastic body has a groove;
The vibrator according to claim 5, wherein the region is formed between the groove and the electro-mechanical energy conversion element.   The vibrator according to claim 1, wherein the protrusion protrudes on a side opposite to a side of the elastic body that contacts the electro-mechanical energy conversion element.   An ultrasonic motor comprising: the vibrator according to claim 1; and a driven body that is in pressure contact with the elastic body of the vibrator. A method of manufacturing a vibrator comprising an electro-mechanical energy conversion element and an elastic body having a partially formed depression,
A first step of laminating a plurality of piezoelectric thin films to form the electromechanical energy conversion element;
A second step of joining the formed electro-mechanical energy conversion element and the elastic body,
In the first step, the piezoelectric thin films are laminated so that the holes formed in the piezoelectric thin films overlap to form through holes in the electromechanical energy conversion element,
In the second step, the through hole is made to face the air gap sealed inside the hollow that is formed when the electromechanical energy conversion element and the elastic body are joined, and the air gap is made outside. A method of manufacturing a vibrator, wherein the vibrator is communicated.   11. The vibration according to claim 10, wherein in the first step, the piezoelectric thin films are stacked such that the diameter of the through hole becomes larger as the surface of the electro-mechanical energy conversion element is closer. Child manufacturing method. The method for manufacturing a vibrator according to claim 10, further comprising a third step of joining a power feeder to the electro-mechanical energy conversion element so as to maintain communication of the through hole.

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