JP2017135936A - Piezoelectric actuator, piezoelectric motor, robot, hand, feeding pump, and adjustment method of piezoelectric actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric actuator which achieves improvement of work efficiency for adjusting a resonance frequency and achieves improvement of costs.SOLUTION: A piezoelectric actuator (10) includes: a housing (30, 70, 80) having an opening (71); and a vibrator (102) having protruding parts (20) and housed in the housing (30, 70, 80). Mass adjustment parts (24) for adjusting a mass of the vibrator (102) are disposed in the vibrator (102).SELECTED DRAWING: Figure 1

Description

  The present invention relates to a piezoelectric actuator, a piezoelectric motor, a robot, a hand, a liquid feed pump, and a method for adjusting a piezoelectric actuator.

  In Patent Document 1, the resonance frequency of a vibrating body used in an ultrasonic motor (piezoelectric motor) as a piezoelectric device is adjusted, and an additional mass portion or a mass removing portion is provided on the plane (main surface) of the vibrating body to vibrate. It describes that it is performed by adjusting the weight (mass) of the body. Further, the resonance frequency of the vibrating body before adjustment can be measured in a state in which the structural member is incorporated into a unit of an ultrasonic motor and the moving body is pressed against the moving body via the friction member. Have been described.

JP 2006-296042 A

  However, in order to adjust the resonance frequency after measuring the resonance frequency before adjustment, it is necessary to disassemble the ultrasonic motor and take out the vibrating body, which has a problem that work efficiency is low and cost is high. .

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms.

(1) According to one aspect of the present invention, a piezoelectric actuator is provided. The piezoelectric actuator includes a housing having an opening and a vibrating body having a convex portion and housed in the housing. A mass adjusting unit for adjusting the mass of the vibrating body is disposed on the vibrating body.
According to this aspect, since the housing that accommodates the vibrating body has the opening, the state of the vibrating body through the opening of the housing can be maintained even in the state of the piezoelectric actuator in which the vibrating body is incorporated. The mass is adjusted, and the resonance frequency of the vibrating body can be adjusted. Therefore, it is possible to provide a piezoelectric actuator with improved work efficiency and improved cost.

(2) In the piezoelectric actuator of the above aspect, the vibrating body may be stacked. According to this aspect, since the vibrating body is laminated, the vibration force can be increased.

(3) The piezoelectric actuator of the above aspect may include a biasing portion that biases the vibrating body in a direction in which the convex portion protrudes. According to this aspect, since the vibrating body is biased by the biasing portion, the resonance frequency can be adjusted by arranging the mass adjusting portion in a state where the piezoelectric actuator is brought close to the actual use state.

(4) In the piezoelectric actuator of the above aspect, the mass adjusting unit may be disposed on a surface of the vibrating body that intersects a direction in which the convex portion protrudes. According to this aspect, since the mass adjusting unit is disposed on the surface of the vibrating body having the convex portion, the mass of the vibrating body can be adjusted efficiently, the resonance frequency can be adjusted, and the vibration of the vibrating body can be adjusted. It is possible to reduce the occurrence of unnecessary vibration in the direction intersecting with the direction.

(5) In the piezoelectric actuator according to the above aspect, at least a part of the mass adjusting unit may be disposed in the opening in a plan view from a direction in which the convex portion protrudes. According to this aspect, since at least a part of the mass adjusting unit is disposed in the opening in a plan view from the direction in which the convex part protrudes, even in a state of the piezoelectric actuator in which the vibrating body is incorporated, The mass of the vibrating body is adjusted through the opening of the housing, and the resonance frequency of the vibrating body can be adjusted. Therefore, it is possible to provide a piezoelectric actuator with improved work efficiency and improved cost.

(6) The piezoelectric actuator of the above aspect may include a wiring board for transmitting a driving signal for the vibrating body.

(7) According to another aspect of the present invention, there is provided a piezoelectric motor including any one of the above piezoelectric actuators.

(8) According to another aspect of the present invention, a robot including any one of the above piezoelectric actuators is provided.

(9) According to another aspect of the present invention, a hand including any one of the above piezoelectric actuators is provided.

(10) According to another aspect of the present invention, a liquid feed pump including any one of the above piezoelectric actuators is provided.

(11) According to another aspect of the present invention, a method for adjusting a resonance frequency of a piezoelectric actuator is provided. In this method of adjusting the resonance frequency of the piezoelectric actuator, (a) a vibrating body having a protruding convex portion and a biasing portion that biases the vibrating body in a direction in which the convex portion protrudes In the step of preparing the accommodated piezoelectric actuator, (b) the step of measuring the resonance frequency of the vibrating body, and (c) the resonance frequency measured in the step (b) is out of the allowable range, Adjusting the mass of the vibrating body.
According to this aspect, the resonance frequency of the vibrating body can be adjusted by efficiently adjusting the mass of the vibrating body.

(12) In the method for adjusting the resonance frequency of the piezoelectric actuator, the step (c) may include a step of measuring the resonance frequency of the vibrating body after adjustment. According to this aspect, it can be confirmed that the resonance frequency after mass adjustment is within the allowable range.

(13) In the method for adjusting the resonance frequency of the piezoelectric actuator, the step (b) and the step (c) may be repeated. According to this aspect, the resonance frequency can be adjusted by adjusting the mass while measuring the resonance frequency.

(14) In the resonance frequency adjusting method of the piezoelectric actuator, the step (c) may be performed by adding a weight to adjust the mass.

(15) In the method for adjusting the resonance frequency of the piezoelectric actuator, the step (c) may adjust the mass by removing a part of the vibrating body or a previously added weight.

  The present invention can be realized in various forms. For example, in addition to a piezoelectric actuator, a resonance frequency adjusting method for a piezoelectric actuator, a piezoelectric motor equipped with a piezoelectric actuator, a robot equipped with a piezoelectric actuator, and a piezoelectric actuator. It can be realized in various forms such as a hand to be used, a liquid feed pump equipped with a piezoelectric actuator, an electronic component conveying device equipped with a piezoelectric actuator, a medication pump equipped with a piezoelectric actuator.

It is a perspective view of a piezoelectric actuator. It is a disassembled perspective view of a piezoelectric actuator. It is a top view which shows schematic structure of a piezoelectric vibrating body. It is 3B-3B sectional drawing of the piezoelectric vibrating body of FIG. 3A. It is explanatory drawing which shows the example of the pattern of the wiring by a wiring layer. It is explanatory drawing which shows the equivalent circuit of a piezoelectric vibration part. It is explanatory drawing which shows the example of the longitudinal vibration of a piezoelectric vibrating body. It is explanatory drawing which shows the example of the bending vibration of a piezoelectric vibrating body. It is explanatory drawing which shows the adjustment procedure of the resonant frequency of a piezoelectric actuator. It is explanatory drawing shown about an example of the measurement circuit of the resonant frequency of a piezoelectric actuator. It is explanatory drawing which shows an example of the impedance characteristic of a piezoelectric vibration part. It is a perspective view which expands and shows the example of the arrangement position of a mass adjustment part. It is a perspective view which expands and shows the example of the arrangement position of a mass adjustment part. It is a perspective view which expands and shows the example of the arrangement position of a mass adjustment part. It is a graph which shows the resonant frequency change with respect to the mass change of the mass adjustment part in a 1st symmetrical position. It is a graph which shows the resonant frequency change with respect to the mass change of the mass adjustment part in a 2nd symmetrical position. It is a graph which shows the resonant frequency change with respect to the mass change of the mass adjustment part in the 3rd symmetrical position. It is a graph which shows the difference change of the resonant frequency of a bending vibration and a longitudinal vibration with respect to the mass change of the mass adjustment part in each position. It is a perspective view which shows the modification of arrangement | positioning of a mass adjustment part. It is a perspective view which shows the modification of arrangement | positioning of a mass adjustment part. It is a perspective view which shows the other modification of arrangement | positioning of a mass adjustment part. It is sectional drawing which shows schematic structure of the piezoelectric vibrating body of a modification. It is a top view which shows schematic structure of the piezoelectric vibrating body unit of a modification. It is a top view which shows schematic structure of the piezoelectric vibrating body unit of a modification. It is a top view which shows schematic structure of the piezoelectric vibrating body unit of a modification. It is explanatory drawing which shows the example of a piezoelectric motor. It is explanatory drawing which shows an example of a robot. It is explanatory drawing of the wrist part of a robot. It is explanatory drawing which shows a finger assistance apparatus. It is explanatory drawing which shows an example of a liquid feeding pump.

A. Piezoelectric actuator configuration:
FIG. 1 is a perspective view of the piezoelectric actuator 10. FIG. 2 is an exploded perspective view of the piezoelectric actuator 10. The piezoelectric actuator 10 includes a plurality of piezoelectric vibration units 100, a mass adjustment unit 24, an outer frame 30, an inner frame 40, a leaf spring 50, an intermediate member 60, a fixed frame 70, a lid 80, and a flexible substrate. 90. The outer frame 30, the fixed frame 70, and the lid 80 constitute a casing. In FIG. 2, the mass adjustment unit 24 is omitted for convenience of illustration.

  Each member is arranged as follows. The piezoelectric vibration unit 100 is composed of a plurality of piezoelectric vibration bodies 101 stacked in the z direction by being bonded to each other with an adhesive. There are two intermediate members 60, and as shown in FIG. 2, the piezoelectric vibrating portion 100 is sandwiched from the vertical direction (z direction). Note that the intermediate member 60 sandwiches only a part of the surface of the piezoelectric vibrating portion 100. This point will be described later. The fixed frame 70 surrounds the piezoelectric vibrating portion 100 and the intermediate member 60 from the x direction and the y direction. The two leaf springs 50 sandwich the intermediate member 60, the piezoelectric vibrating portion 100, and the fixed frame 70 from the vertical direction (z direction) at the central portion 52. The inner frame 40 has three side portions 42, 43, 44, and these side portions 42, 43, 44 pass through the leaf spring 50 and are inserted between the piezoelectric vibrating portion 100 and the fixed frame 70. ing. The outer frame 30 surrounds the fixed frame 70. The lid 80 is disposed above (in the z direction) the upper leaf spring 50. The flexible substrate 90 passes through the lid 80 and the leaf spring 50 and is connected to the piezoelectric vibration unit 100. Among the piezoelectric vibrating portions 100, the side surface of each piezoelectric vibrating body 101 on which the convex portion 20 is provided is exposed to the outside through the opening 71 of the fixed frame 70 in the x direction.

  The mass adjusting unit 24 is disposed on the side surface of the piezoelectric vibrating unit 100 exposed to the outside through the opening 71 and adjusts the resonance frequency of the piezoelectric vibrating unit 100. The arrangement position of the mass adjusting unit 24 will be described later.

FIG. 3A is a plan view illustrating a schematic configuration of the piezoelectric vibrating body 101 of the piezoelectric vibrating unit 100. The piezoelectric vibrating body 101 includes piezoelectric elements 110a, 110b, 110c, 110d, and 110e, a substrate 200, and a convex portion 20. The substrate 200 includes a vibration part 210 and a support part 220. The vibration part 210 has a substantially rectangular shape, and the piezoelectric elements 110a to 110e are arranged. The piezoelectric element 110e is configured in a substantially rectangular shape, and in the center in the short direction (also referred to as “short side direction” or “width direction”) of the vibration unit 210, the longitudinal direction of the vibration unit 210 (on the central axis CX). (Direction along). The piezoelectric elements 110 a to 110 d are arranged at the four corner positions of the vibration unit 210. The support part 220 is disposed so as to surround approximately half of the vibration part 210, and the end part of the support part 220 is connected to the vibration part 210 at the center of the long side of the vibration part 210. Of the support part 220, the end part connected to the vibration part 210 is referred to as a “first connection part 222” and a “second connection part 223”, and parts other than the first connection part 222 and the second connection part 223 are referred to. This is referred to as “fixed portion 221”. A gap 205 is disposed between the vibration part 210 and the support part 220. When a voltage is applied to the piezoelectric elements 110a to 110e, the piezoelectric elements 110a to 110e expand and contract, and the vibration unit 210 vibrates. However, the gap 205 does not contact the fixing unit 221 of the support unit 220 due to this vibration. Is configured. The convex portion 20 is disposed in the concave portion 216 at the center position (position on the central axis CX in plan view) of the side surface 214 including the short side of the vibrating portion 210 that is not surrounded by the support portion 220. The convex portion 20 is preferably made of a durable material such as ceramics (for example, Al ₂ O ₃ ).

  3B is a 3B-3B cross-sectional view of the piezoelectric vibrating body 101 of FIG. 3A. In FIG. 3B, the vertical dimension is exaggerated for convenience of illustration. The piezoelectric vibrator 101 includes two piezoelectric vibrator units 102. The two piezoelectric vibrator units 102 each include a substrate 200 and five piezoelectric elements 110 a to 110 e disposed on the substrate 200. In FIG. 3B, two piezoelectric elements 110c and 110d are illustrated, and the other three piezoelectric elements 110a, 110b, and 110e are not illustrated. Piezoelectric elements 110a to 110e are planar surfaces (regions of the vibration unit 210) where the two substrates 200 overlap each other in a plan view (FIG. 3A) (the region of the vibration unit 210). On the plane, that is, the plane along the main surface). Further, two piezoelectric elements having the same reference numerals, for example, two piezoelectric elements 110a, are in positions where they can be seen to overlap each other in plan view of the two substrates 200. The same applies to the other piezoelectric elements 110b to 110e.

  The two piezoelectric vibrating body units 102 are disposed so that the substrate 200 faces outside and the piezoelectric elements 110 a to 110 e are sandwiched between the two substrates 200. That is, in the piezoelectric vibrating body 101, two piezoelectric vibrating body units 102 are arranged (laminated) along the direction in which the piezoelectric elements 110 a to 110 e are arranged on the substrate 200. The piezoelectric elements 110a to 110e are covered with a protective layer 260. Here, “protective layer 260” is also referred to as “covering portion 260”. The piezoelectric vibrators 101 are configured by bonding the covering portions 260 of the two piezoelectric vibrator units 102 with the adhesive layer 270. As shown in FIGS. 3A and 3B, the convex portion 20 has a substantially rectangular parallelepiped shape, and is attached across the two substrates 200. However, the convex portion 20 may have a substantially cylindrical shape, a sphere shape, or an ellipsoid shape, or may be provided on each substrate 200. The piezoelectric vibrating body unit 102 corresponds to one “vibrating body”, and the piezoelectric vibrating portion 100 corresponds to a structure in which a plurality of “vibrating bodies” are stacked.

  As illustrated in FIG. 3B, the piezoelectric vibrating body 101 includes a piezoelectric element structure 111 on the support portion 220. Here, when the piezoelectric vibrating body 101 does not include the piezoelectric element structure 111 on the support portion 220 of the substrate 200, the two support portions 220 are arranged with a gap therebetween. On the other hand, in the vibration unit 210, the piezoelectric elements 110 a to 110 e are disposed between the two substrates 200. Therefore, when the piezoelectric element structure 111 is not provided on the support part 220, the vibration part 210 and the support part 220 have different thicknesses. Therefore, in the support part 220, the piezoelectric vibrator units 102 do not contact each other, and the structure is May become unstable. When the piezoelectric element structure 111 is provided on the support portion 220, the thicknesses of the vibrating portion 210 and the support portion 220 are substantially the same, and the piezoelectric vibrating body units 102 are also in contact with each other in the support portion 220. Easy to stabilize. Note that, if a voltage is applied to the piezoelectric element structure 111 and the support part 220 may vibrate when it expands or contracts, the piezoelectric element structure 111 is not applied with a voltage or applied with a voltage. However, it is preferable that it is configured not to stretch or contract. For example, the two electrodes sandwiching the piezoelectric body of the piezoelectric element structure 111 may be grounded or short-circuited.

  The piezoelectric vibrator unit 102 includes each member in the order of an insulating layer 201, a first electrode 130, a piezoelectric body 140, a second electrode 150, an insulating layer 240, a wiring layer 250, and a protective layer 260 (covering portion 260) on the substrate 200. Is arranged. The insulating layer 201 insulates the substrate 200 from other electrodes (the first electrode 130, the second electrode 150, and the wiring layer 250). The first electrode 130, the piezoelectric body 140, and the second electrode 150 constitute the piezoelectric elements 110a to 110e. The insulating layer 240 covers and insulates the piezoelectric elements 110a to 110e. However, the insulating layer 240 includes a contact hole for bringing the first electrode 130 and the second electrode 150 of the piezoelectric elements 110 a to 110 e into contact with the wiring layer 250. In the wiring layer 250, wiring for energizing the first electrode 130 and the second electrode 150 is disposed. As described above, the protective layer 260 protects the piezoelectric elements 110a to 110e.

  The piezoelectric vibrator unit 102 can be manufactured using, for example, a film forming process. The outline is as follows. On a Si wafer as the substrate 200, an insulating layer 201, a first electrode 130, a piezoelectric body 140, a second electrode 150, an insulating layer 240, a wiring layer 250, and a protective layer (covering portion) 260 are sequentially formed. Then, the shape of each substrate 200 is formed by etching, and at the same time, a gap 205 between the vibrating portion 210 and the support portion 220 is formed, and a concave portion 216 (FIG. 3A) for attaching the convex portion 20 is formed. . Thereby, a plurality of piezoelectric vibrator units 102 can be formed on one Si wafer. The two piezoelectric vibrator units 102 are arranged so that the substrate 200 faces the outside, the piezoelectric elements 110a to 110e face the inside, and the members having the same reference numerals are plane-symmetric. The covering portions 260 of the vibrator unit 102 are bonded to each other, and the convex portion 20 is bonded to the concave portions 216 of the two substrates 200 with an adhesive. Thereby, the piezoelectric vibrating body 101 can be manufactured.

As the insulating layers 201 and 240, for example, an SiO ₂ layer formed by thermally oxidizing the surface of the substrate 200 can be used. Alternatively, the insulating layer 201 can be formed using an organic material such as alumina (Al ₂ O ₃ ), acrylic, or polyimide. When the substrate 200 is an insulator, the step of forming the insulating layer 201 can be omitted.

  Moreover, as materials for the electrodes 130 and 150, any material having high conductivity such as Al (aluminum), Ni (nickel), Au (gold), Pt (platinum), Ir (iridium), Cu (copper), or the like. Is available. The electrodes 130 and 150 can be formed by sputtering, for example, and the patterning can be performed by etching, for example.

In addition, as a material of the piezoelectric body 140, any material exhibiting a piezoelectric effect such as ceramics having an ABO ₃ type perovskite structure can be used. Examples of ceramics having an ABO ₃ type perovskite structure include lead zirconate titanate (PZT), barium titanate, lead titanate, potassium niobate, lithium niobate, lithium tantalate, sodium tungstate, zinc oxide, titanium Barium strontium oxide (BST), strontium bismuth tantalate (SBT), lead metaniobate, lead zinc niobate, lead scandium niobate, and the like can be used. It is also possible to use a material exhibiting a piezoelectric effect other than ceramic, such as polyvinylidene fluoride and quartz.

  The formation of the piezoelectric body 140 can be performed using, for example, a sol-gel method. That is, a sol-gel solution of a piezoelectric material is dropped on the substrate 200 (first electrode 130), and the substrate 200 is rotated at a high speed to form a thin film of the sol-gel solution on the first electrode 130. Thereafter, the first layer of the piezoelectric material is formed on the first electrode 130 by calcining at a temperature of 200 ° C. to 300 ° C. Thereafter, the piezoelectric layer is formed on the first electrode 130 to a desired thickness by repeating the sol-gel solution dripping, high-speed rotation, and calcination cycles a plurality of times. Note that the thickness of one layer of the piezoelectric body formed in one cycle is approximately 50 nm to 150 nm, although it depends on the viscosity of the sol-gel solution and the rotation speed of the substrate 200. After the piezoelectric layer is formed to a desired thickness, the piezoelectric body 140 is formed by sintering at a temperature of 600 ° C. to 1000 ° C. If the thickness of the sintered piezoelectric body 140 is set to 50 nm (0.05 μm) or more and 20 μm or less, a small piezoelectric actuator 10 can be realized. If the thickness of the piezoelectric body 140 is 0.05 μm or more, a sufficiently large force can be generated according to the expansion and contraction of the piezoelectric body 140. If the thickness of the piezoelectric body 140 is 20 μm or less, a sufficiently large force can be generated even if the voltage applied to the piezoelectric body 140 is 600 V or less. As a result, a drive circuit (not shown) for driving the piezoelectric actuator 10 can be configured with an inexpensive element. The thickness of the piezoelectric body may be 400 nm or more. In this case, the force generated by the piezoelectric element can be increased. The temperature and time for calcining and sintering are examples, and are appropriately selected depending on the piezoelectric material.

  In the case of sintering after forming a thin film of piezoelectric material using the sol-gel method, (a) it is easier to form a thin film as compared with a conventional sintering method in which raw material powders are mixed and sintered. (B) It is easy to crystallize by aligning the lattice direction, and (c) it is possible to improve the breakdown voltage of the piezoelectric body.

  The patterning of the piezoelectric body 140 can be performed by ion milling using an argon ion beam. Note that instead of patterning using ion milling, any other patterning method (for example, using chlorine-based gas) Patterning may be performed by dry etching.

  The wiring layer 250 can be formed using copper or brass. The wiring layer 250 can be formed by sputtering, for example, and wiring can be formed in the wiring layer 250 by patterning. The patterning of the wiring can be performed by etching, for example.

  FIG. 4 is an explanatory diagram showing an example of a wiring pattern by the wiring layer 250. The wiring layer 250 has four wirings 251, 252, 253, and 254. These wirings 251 to 254 are formed so as to cross over the connection parts 222 and 223 from the top of the fixed part 221 to the vibration part 210. The first wiring 251 is connected to the second electrode 150 of the piezoelectric elements 110 a and 110 d (FIGS. 1A and 1B) on the vibration unit 210. Similarly, the second wiring 252 is connected to the second electrode 150 of the piezoelectric elements 110b and 110c on the vibration unit 210, and the third wiring 253 is connected to the second electrode 150 of the piezoelectric element 110e on the vibration unit 210. The fourth wiring 254 is connected to the first electrode 130 of the piezoelectric elements 110 a to 110 e on the vibration unit 210. In addition, these wirings 251 to 254 are connected to the wiring board on the support portion 220. Note that the wirings 251 to 254 are not connected to the piezoelectric element structure 111 on the fixed portion 221.

  The protective layer 260 (FIG. 1B) is made of, for example, a silicone resin such as JCR (junction coating resin). Note that a resin material such as epoxy or polyimide may be used instead of JCR.

  The piezoelectric vibration unit 100 of the piezoelectric actuator 10 is connected to the connection terminals (not shown) formed at the ends of the wirings 251 to 254 of the wiring layer 250 in the support unit 220 (FIG. 4) of the substrate 200. , 2) are connected and electrically connected to an external drive circuit (not shown) via the flexible substrate 90.

  FIG. 5 is an explanatory diagram showing an equivalent circuit of the piezoelectric vibration unit 100. Note that the piezoelectric vibrating unit 100 includes a plurality of piezoelectric vibrating bodies 101, and each of the plurality of piezoelectric vibrating bodies 101 includes two piezoelectric vibrating body units 102. However, in FIG. Only the vibrating body unit 102 is illustrated. As can be seen from FIG. 5, the first electrodes 130 of the five piezoelectric elements 110 a to 110 e are connected to the fourth wiring 254 and connected to the drive circuit 400. The second electrodes 150 of the piezoelectric elements 110 a and 110 d are connected to the first wiring 251 and connected to the drive circuit 400. The second electrodes 150 of the piezoelectric elements 110 b and 110 c are connected to the second wiring 252 and connected to the drive circuit 400. The second electrode 150 of the piezoelectric element 110 e is connected to the third wiring 253 and connected to the drive circuit 400. That is, the piezoelectric elements 110 are divided into three groups. The first group has two piezoelectric elements 110a and 110d. The second group has two piezoelectric elements 110b and 110c. The third group has only one piezoelectric element 110e. The first group of piezoelectric elements 110 a and 110 d are connected in parallel to each other and connected to the drive circuit 400. The second group of piezoelectric elements 110 b and 110 c are connected in parallel to each other and connected to the drive circuit 400. When connected in parallel, the voltage applied to each of the piezoelectric elements 110a to 110d can be increased. The third group of piezoelectric elements 110e are independently connected to the drive circuit 400. The first group of piezoelectric elements 110a and 110d may be connected in series. In this case, the polarization directions of the piezoelectric elements 110a and 110d when a voltage is applied are preferably the same. Similarly, the second group of piezoelectric elements 110b and 110c may be connected in series. When connected in series, the capacity can be reduced.

  From the drive circuit 400, a predetermined piezoelectric element among the five piezoelectric elements 110a to 110e, for example, periodically changes between the first electrode 130 and the second electrode 150 of the first group of piezoelectric elements 110a and 110d. By applying an AC voltage or a pulsating voltage as a drive signal, the piezoelectric vibrating portion 100 can be operated by ultrasonic vibration such as longitudinal vibration or bending vibration. Here, the “pulsating voltage” means a voltage obtained by adding a DC offset to an AC voltage, and the direction of the voltage (electric field) of the pulsating voltage is one direction from one electrode to the other electrode. The direction of the current is preferably from the second electrode 150 to the first electrode 130 rather than from the first electrode 130 to the second electrode 150.

  FIG. 6A is an explanatory diagram illustrating an example of longitudinal vibration of the piezoelectric vibrating body 101. The support portion 220 is omitted for convenience of illustration. In the example shown in FIG. 6A, an AC voltage or a pulsating voltage is applied to one piezoelectric element 110e of the third group, and the piezoelectric element 110e vibrates so as to expand and contract in the direction of arrow x in FIG. 6A (longitudinal vibration). To do. This vibration is transmitted to the vibration part 210 of the substrate 200, and the vibration part 210 also vibrates (longitudinal vibration) so as to expand and contract in the direction of the arrow x in FIG. 6A. The convex portion 20 reciprocates in the x direction in the plane of the piezoelectric vibrating body 101, and the piezoelectric vibrating body 101 reciprocates by longitudinally vibrating in the longitudinal direction of the vibrating portion 210.

  FIG. 6B is an explanatory diagram illustrating an example of bending vibration of the piezoelectric vibrating body 101. The support part 220 is omitted as in FIG. 6A. In the example shown in FIG. 6B, an AC voltage or a pulsating voltage is applied to the two piezoelectric elements 110a and 110d in the first group, and the two piezoelectric elements 110a and 110d in the first group are in the direction of the arrow x in FIG. 6B. Extends and contracts. This vibration is transmitted to the vibration part 210 of the substrate 200, and the vibration part 210 vibrates (bends and vibrates) so as to bend in the plane of the vibration part 210 and deform into a meandering shape (S-shape). And the convex part 20 reciprocates in the direction of the arrow y (width direction of the vibration part 210) in the plane of the piezoelectric vibrating body 101, or makes an elliptical movement. In addition, when the drive circuit 400 applies an AC voltage or a pulsating current voltage to the two piezoelectric elements 110b and 110c (FIG. 5) of the second group, the position of the vibrating part 210 that expands and contracts is different. Generates ultrasonic vibration of bending vibration.

  In addition, the first electrode 130 and the second electrode 150 of the two piezoelectric elements 110a and 110d of the first group and the two piezoelectric elements 110b and 110c of the second group correspond to “flexural vibration electrodes”, and The first electrode 130 and the second electrode 150 of one piezoelectric element 110e correspond to “longitudinal vibration electrodes”. The direction along the longitudinal direction or the width direction of the vibration unit 210 corresponds to the “direction along the first surface (in-plane direction)” of the piezoelectric vibrating body 101 or the piezoelectric element 110. In addition, either the longitudinal vibration or the bending vibration corresponds to the “first vibration mode” and the other corresponds to the “second vibration mode”. In this example, the longitudinal vibration is the “first vibration mode” and the bending vibration is the “second vibration mode”.

  The piezoelectric vibrating body 101 transmits a stretching force due to longitudinal vibration and a vibration force (driving force) generated by a reciprocating motion or elliptical motion due to bending vibration to the driven body via the convex portion 20. Can be driven. The piezoelectric vibrating unit 100 includes a plurality of piezoelectric vibrating bodies 101. A large longitudinal vibration force can be obtained by simultaneously vibrating the plurality of piezoelectric vibrating bodies 101, and a plurality of piezoelectric vibrating bodies 101 can be obtained. By simultaneously bending and vibrating the vibrating body 101, a vibration force of a large bending vibration can be obtained, and the driven body can be driven with a large driving force.

  Note that the period of the voltage applied to the piezoelectric element 110 (110a to 110e) is set in advance in the piezoelectric vibration unit 100 in order to efficiently use the vibration of the piezoelectric vibrating body 101 and enhance output characteristics as the piezoelectric actuator 10. It is preferable to set the resonance frequency, that is, the resonance frequency obtained by synthesizing the resonance frequencies of the plurality of piezoelectric vibrating bodies 101, or the period of the frequency in the vicinity thereof.

  In the description of the structure of the piezoelectric actuator 10 described above (FIGS. 1 and 2), it has been described that the intermediate member 60 sandwiches only a part of the surface of the piezoelectric vibration unit 100. This is because the vibration of the vibrating portion 210 (FIG. 3A) of each piezoelectric vibrating body 101 is not suppressed, and part of the surface of the piezoelectric vibrating portion 100 sandwiched between the intermediate members 60 is the upper and lower ends of the piezoelectric vibrating body 101. It corresponds to the support part 220 of the substrate 200.

  The fixed frame 70 (FIG. 2) is a member having a substantially frame shape, and an opening 71 is provided at the center of one side of the frame shape. As described above, the inner frame 40, the piezoelectric vibrating portion 100, and the intermediate member 60 are accommodated (accommodated) inside the fixed frame 70. As described above, a part of the piezoelectric vibrating portion 100 on the side surface where the convex portion 20 is provided on each piezoelectric vibrating body 101 is exposed to the outside from the opening 71 of the fixed frame 70. The opening 71 corresponds to the “opening of the housing”.

  When the piezoelectric actuator 10 is configured, the leaf springs 50 are disposed above and below the fixed frame 70 as shown in FIG. The spring portions 53 and 54 of the two leaf springs 50 are elongated portions that connect the central portion 52 and the outer frame portion 51, and have a bent structure. When the piezoelectric vibrating portion 100 is driven, the vibrating portion 210 (FIG. 3A) of each piezoelectric vibrating body 101 expands and contracts. When the vibration part 210 extends, the support part 220 moves in the direction opposite to the concave part 216, so that the intermediate member 60 and the central part 52 of the leaf spring 50 also move in the same direction. As a result, the relative position between the central portion 52 and the outer frame portion 51 changes, and the spring portions 53 and 54 are distorted. The distorted spring portions 53 and 54 function as springs (elastic bodies) and bias the piezoelectric vibrating portion 100 in the direction in which the convex portion 20 protrudes so that the piezoelectric vibrating portion 100 presses a driven body (not shown). It functions as a “biasing part” (which can also be referred to as a “pressurizing part” for applying pressure).

  By the way, the resonance frequency (resonance frequency of longitudinal vibration and resonance frequency of bending vibration) of the piezoelectric vibration unit 100 varies due to dimensional variations during the manufacture of the piezoelectric vibration unit 102 and the piezoelectric vibration body 101. Moreover, it fluctuates also by incorporating as the piezoelectric actuator 10. For this reason, it is preferable to adjust the resonance frequency to a desired value by adding or removing mass to the piezoelectric vibration unit 100 in a state incorporated in the piezoelectric actuator 10.

  In the piezoelectric actuator 10, as shown in FIG. 1A, the mass adjusting unit 24 is disposed on the side surface of the piezoelectric vibration unit 100 exposed to the outside from the opening 71 (the side surface intersecting the direction in which the convex portion 20 protrudes). Has been. For this reason, the resonance frequency of the piezoelectric vibrating part 100 can be adjusted in a state where the piezoelectric vibrating part 100 is incorporated as the piezoelectric actuator 10. In addition, the piezoelectric vibration unit 100 in the assembled state is urged in the direction in which the convex portion 20 protrudes (x direction) by the spring portions 53 and 54 functioning as the urging portion. The resonance frequency can be adjusted by bringing the driven body (not shown) close to a pressing state. Therefore, it is possible to provide a piezoelectric actuator with improved work efficiency and improved cost. The resonance frequency adjustment by the mass adjusting unit 24 is performed by the arrangement position of the mass adjusting unit 24 and the addition or removal of mass by the mass adjusting unit 24 as described below.

B. Resonance frequency adjustment:
FIG. 7 is an explanatory diagram showing a procedure for adjusting the resonance frequency of the piezoelectric actuator. First, in step S110, the piezoelectric actuator 10 (FIGS. 1A and 1B) before adjustment is prepared. In step S120, the resonance frequency of the prepared piezoelectric actuator 10 before adjustment is measured.

  FIG. 8 is an explanatory diagram illustrating an example of a measurement circuit for the resonance frequency of the piezoelectric actuator 10. In FIG. 8, for convenience of illustration, only one piezoelectric vibrating body unit 102 included in the piezoelectric vibrating unit 100 of the piezoelectric actuator 10 is illustrated.

  The resonance frequency of the piezoelectric actuator 10, that is, the piezoelectric vibrating unit 100 can be obtained based on the impedance characteristics of the piezoelectric vibrating unit 100 in which the impedance characteristics of the plurality of piezoelectric vibrating body units 102 are combined. The impedance characteristic of the piezoelectric vibration unit 100 can be measured using the impedance measurement circuit 500. As the impedance measurement circuit 500, an impedance analyzer, an impedance meter, or the like is used. Then, the resonance frequency of the piezoelectric vibration unit 100 is determined based on the five piezoelectric elements 110a, 110b, 110c, 110d included in each of the plurality of piezoelectric vibration unit units 102 of the piezoelectric vibration unit 100 to be measured with respect to the impedance measurement circuit 500. 110e can be obtained by connecting all of 110e in parallel to measure impedance characteristics and analyzing the measurement results.

  FIG. 9 is an explanatory diagram illustrating an example of the impedance characteristic of the piezoelectric vibration unit 100. FIG. 9 shows impedance characteristics when the resonance frequency fv of longitudinal vibration and the resonance frequency fb of bending vibration are shifted. As these resonance frequencies, for example, frequencies at which the impedance is minimized are used.

  In step S130 of FIG. 7, it is confirmed whether or not the measured resonance frequency before adjustment is within an allowable range. When the resonance frequency before adjustment is within the allowable range, it is not necessary to adjust the resonance frequency, and the adjustment of the resonance frequency is finished as it is. On the other hand, if the resonance frequency before adjustment is not within the allowable range, in step S140, the mass is adjusted by the arrangement of the mass adjusting unit 24 so that the resonance frequency is adjusted to be within the allowable range. The allowable range is set according to the desired accuracy.

  10A, 10B, and 10C are perspective views showing enlarged examples of arrangement positions of the mass adjusting unit 24. FIG. FIG. 10A shows a state in which the mass adjusting unit 24 is arranged at the first symmetric position PA on the side surface of the piezoelectric vibrating unit 100 configured by the side surface of the piezoelectric vibrating body 101 provided with the convex portion 20. Yes. The first symmetrical position PA is an end position on both sides in the y direction farthest from the convex portion 20 at the center position (on the central axis CX) in the z direction and the y direction. FIG. 10B shows a state in which the mass adjusting unit 24 is arranged at the third symmetrical position PC closest to the center position. FIG. 10C shows a state in which the mass adjusting unit 24 is arranged at the second symmetric position PB intermediate the first symmetric position PA and the third symmetric position PC.

  FIG. 11A is a graph showing the resonance frequency change with respect to the mass change of the mass adjusting unit 24 at the first symmetric position PA, and FIG. 11B shows the resonance frequency change with respect to the mass change of the mass adjusting unit 24 at the second symmetric position PB. FIG. 11C is a graph showing a change in resonance frequency with respect to a change in mass of the mass adjusting unit 24 at the third symmetrical position PC. FIG. 11D is a graph showing a change in the difference between the resonance frequencies of the bending vibration and the longitudinal vibration with respect to the mass change of the mass adjusting unit 24 at each of the symmetrical positions PA, PB, and PC. Note that the vertical axis of each graph indicates the frequency from the degenerate frequency when the resonance frequency fv of the longitudinal vibration and the resonance frequency fb of the bending vibration match (degenerate) as a state where the “degenerate frequency is zero”. ing. In addition, the horizontal axis of each graph indicates the mass of the mass adjustment unit 24. 11A to 11C, the mass W3 at the time of degeneration, the masses W1 and W2 (> W1) lighter (smaller) than the mass W3, and the masses W4 and W5 heavier (larger) than the mass W3 are shown. The resonance frequency fv of longitudinal vibration and the resonance frequency fb of bending vibration in five masses (> W4) are shown. In the graph of FIG. 11D, the difference Δf [PA] (= fb−) between the resonance frequency fb of the bending vibration and the resonance frequency fv of the longitudinal vibration at the five masses W1 to W5 for each of the symmetrical positions PA, PB, and PC. fv), Δf [PB] (= fb−fv), Δf [PC] (= fb−fv).

  As shown in FIGS. 11A to 11C, the resonance frequencies fv and fb are higher than the degeneracy frequency and lower as the mass (larger) is higher as the mass of the mass adjusting unit 24 is lighter (smaller) than the mass W3 during degeneration. However, the resonance frequency fv of the longitudinal vibration has the same frequency change according to the mass change regardless of the arrangement position of the mass adjusting unit 24. On the other hand, the resonance frequency fb of the bending vibration is such that the frequency change with respect to the mass change decreases as the arrangement position of the mass adjusting unit 24 is closer to the center position, and increases as the position is farther from the center position. For this reason, as shown in FIG. 11D, the change in the difference Δf between the resonance frequency fb of the bending vibration and the resonance frequency fv of the longitudinal vibration according to the mass change is very high at the first symmetrical position PA farthest from the center position. It becomes large (Δf [PA]), very small at the third symmetrical position PC closest to the central position (Δf [PC]), and has an intermediate size at the second intermediate symmetrical position PB (Δf [PA]). PB]). That is, the change in the difference Δf between the resonance frequency fb of the bending vibration and the resonance frequency fv of the longitudinal vibration according to the change in the mass of the mass adjustment unit 24 is smaller as the arrangement position of the mass adjustment unit 24 is closer to the center position. The farther from the position, the larger it will be. That is, the closer the arrangement position of the mass adjusting unit 24 is to the center position, the lower the sensitivity of the frequency change to the mass change, and the farther from the center position, the higher the sensitivity of the frequency change to the mass change.

  Therefore, the arrangement position of the mass adjustment unit 24 is determined according to the deviation from the target resonance frequency and the difference between the resonance frequencies of the longitudinal vibration and the bending vibration, and the mass (weight) of the mass adjustment unit 24 arranged at the arrangement position is determined. The resonance frequency of the piezoelectric actuator 10 can be adjusted. For example, as shown in FIG. 11A, the resonance frequencies fv and fb before adjustment of the sample Sp of the piezoelectric actuator 10 provided with the mass adjustment unit 24 of a certain reference mass indicate frequencies fvp and fbp that are higher than the degenerate frequency. If it is, the mass (W3−Wp) corresponding to the frequency adjustment range is added to the reference mass, so that the resonance frequencies fv and fb can be lowered so as to approach the degenerate frequency. On the other hand, when the resonance frequencies fvp and fbp before adjustment are lower than the degenerate frequency, the resonance frequency fv and fb are raised by removing the mass corresponding to the frequency adjustment range from the reference mass, thereby reducing the degenerate frequency. Can be adjusted to approach. In addition, provision of the mass of the mass adjustment part 24 is performed by dipping a resin material, for example. Moreover, the removal of mass is performed by removing the resin material provided as reference | standard mass with a laser, for example. Moreover, you may make it perform by removing the board | substrate 200 of the piezoelectric vibration part 100 with a laser. In addition, since the frequency change per unit mass is larger at the outer arrangement position farther from the center position, coarse adjustment is possible, and the frequency change per unit mass is smaller at the inner arrangement position closer to the center position, so fine adjustment is possible. is there.

  As described above, after adjusting the mass in step S140 (FIG. 7), the adjusted resonance frequency is measured in step S150, and in step S130, the resonance frequency of the piezoelectric actuator 10 falls within the allowable range. Confirming that the resonance frequency is adjusted, the resonance frequency adjustment processing is terminated.

  Here, the adjusted resonance frequency is confirmed, but if it is not within the allowable range, the processing of step S130 to step S150 may be repeatedly executed until the resonance frequency falls within the allowable range. Further, in the above adjustment process, as described with reference to FIG. 11A, after performing mass adjustment by applying or removing mass estimated in advance from a graph indicating the resonance frequency change with respect to the mass change of the mass adjustment unit 24, The procedure for confirming that the resonance frequency is within the allowable range has been described as an example. On the other hand, while gradually adding or removing mass, the change in the resonance frequency is measured by measuring the change in impedance characteristics caused by the change in mass until the resonance frequency falls within the allowable range. The mass adjustment may be repeated.

  As described above, the piezoelectric actuator 10 has a mass on the side surface where the convex portion 20 of the portion of the piezoelectric vibrating portion 100 exposed from the opening 71 is disposed, that is, on the portion of the vibrating body corresponding to the opening of the housing. It is possible to adjust the resonance frequency by arranging the adjusting unit 24. Therefore, it is possible to adjust the resonance frequency of the vibrating body by adjusting the mass of the vibrating body while maintaining the state of the piezoelectric actuator in which the vibrating body is incorporated, thereby improving the working efficiency and improving the cost. Can be provided.

C. Modification of the mass adjustment unit:
12A and 12B are perspective views showing a modification example of the arrangement of the mass adjusting unit 24 and corresponding to FIG. 10A. FIG. 10A described above shows an example in which the mass adjusting unit 24 is arranged at the symmetrical positions of the end portions on both sides in the y direction from the convex portion 20 at the center position (on the central axis CX) in the z direction and the y direction. FIG. 12A shows an example in which the mass adjusting unit 24 is arranged over the entire piezoelectric vibrating unit 100 along the z direction at symmetrical positions on both ends in the y direction. However, in this arrangement example, the change in the resonance frequency with respect to the mass change becomes larger than in the case of FIG. 10A, and the adjustment resolution becomes lower. FIG. 12B shows an example in which the mass adjusting unit 24 is arranged at the symmetrical positions of the four end portions on the diagonal line with the central axis CX as the center. In this case, similarly to FIG. 10A, the adjustment resolution can be increased by arranging the mass adjusting units 24 at the four inner symmetrical positions on the diagonal line.

  12A and 12B, the adjustment sensitivity can be changed by shifting the arrangement position in the same manner as in FIGS. 10B and 10C. Moreover, although FIG. 12A and FIG. 12B showed as an example the mass adjustment part 24 to which mass (weight) is provided, the mass adjustment part from which mass is removed may be sufficient. In this case, as described above, the mass adjusting unit is arranged by removing the substrate 200 of the piezoelectric vibrating unit 100 with a laser. Moreover, it is also possible to be constituted by removing a preliminarily provided weight portion with a laser.

  FIG. 12C is a perspective view showing another modification of the arrangement of the mass adjusting unit 24. 12C shows the mass adjustment unit 24 on the upper surface (surface parallel to the xy plane) exposed from the opening 71, not on the side surface where the convex portion 20 of the piezoelectric vibration unit 100 is disposed. Shows an example in which is arranged. Also in this case, it is possible to adjust the resonance frequency by adjusting the mass of the vibrating body. Even in this arrangement, it is possible to use a mass adjusting unit having a configuration in which mass is removed instead of the mass adjusting unit 24 to which mass is applied. However, in the case where the mass adjusting unit 24 is disposed on the upper surface of the piezoelectric vibration unit 100, the longitudinal vibration and bending vibration (hereinafter also referred to as “in-plane vibration”) of the piezoelectric vibration unit 100 (hereinafter referred to as “in-plane direction”). It is easy to generate unnecessary vibrations in the out-of-plane direction intersecting with each other. On the other hand, as shown in FIGS. 10A to 10C, FIGS. 12A, and 12B, when the mass adjusting unit 24 is arranged on the side surface of the piezoelectric vibrating unit 100 where the convex portion 20 is arranged, the direction is out of plane. This is advantageous in that the resonance frequency can be adjusted while reducing the occurrence of unnecessary vibration. The effect is higher when the thickness of the piezoelectric body 140 is a thin film of 0.05 μm to 20 μm.

  The mass adjusting unit 24 is formed on the side surface of the piezoelectric vibrating unit 100 exposed from the opening 71 (FIGS. 10A to 10C, FIGS. 12A and 12B) or on the upper surface of the piezoelectric vibrating unit 100 exposed from the opening 71 (FIG. 12C If the mass of the piezoelectric vibration part 100 is adjustable in any part of the piezoelectric vibration part 100 corresponding to the opening of the housing, the position and shape of the piezoelectric vibration part 100 are not particularly limited. That is, it is only necessary that at least a part of the mass adjusting unit 24 is disposed in the piezoelectric vibrating unit 100 exposed from the opening 71. However, as shown in FIGS. 10A to 10C and FIGS. 12A to 12C, the resonance frequency can be adjusted by adjusting the mass in a balanced manner when arranged at symmetrical positions. In addition, instead of the opening 71 where the side surface of the piezoelectric vibration unit 100 having the convex portion 20 is exposed, another opening is provided in the housing, and the mass adjustment unit 24 is provided in the portion of the piezoelectric vibration unit 100 corresponding to the opening. May be arranged.

D. Modified examples of the piezoelectric vibrating part and the piezoelectric vibrating body:
FIG. 13 is a cross-sectional view illustrating a schematic configuration of a piezoelectric vibrating body 101B according to a modification. The piezoelectric vibrating body 101 (FIG. 3B) constituting the piezoelectric vibrating portion 100 (FIGS. 1 and 2) of the piezoelectric actuator 10 is formed by laminating two piezoelectric vibrating body units 102 together. On the other hand, the piezoelectric vibrating body 101B of the modification includes only one piezoelectric vibrating body unit 102, and includes a substrate 200 on which no piezoelectric element is arranged instead of the second piezoelectric vibrating body unit 102. Yes. That is, the piezoelectric elements 110a to 110e of the first piezoelectric vibrating body unit 102 are sandwiched between the substrate 200 of the first piezoelectric vibrating body unit 102 and the substrate 200 on which no piezoelectric element is disposed. The substrate 200 on which the piezoelectric element is not disposed is bonded to the piezoelectric vibrator unit 102 by an adhesive layer (not shown). A piezoelectric actuator may be configured by using a piezoelectric vibrating portion in which a plurality of piezoelectric vibrating bodies 101B of this modification are stacked. In addition, you may abbreviate | omit about the board | substrate 200 in which the piezoelectric element is not arrange | positioned. Alternatively, a plurality of piezoelectric vibrator units 102 may be stacked and a substrate 200 may be provided in which no piezoelectric element is disposed only on the uppermost piezoelectric vibrator unit 102.

  Further, in the above-described embodiment, the case where the piezoelectric actuator is configured by using the piezoelectric vibrating section in which a plurality of piezoelectric vibrating bodies is stacked has been described as an example. However, the piezoelectric actuator is configured by using one piezoelectric vibrating body. May be.

E. Other embodiments of the piezoelectric vibrator unit:
14A, 14B, and 14C are plan views showing a schematic configuration of piezoelectric vibrator units 102J, 102K, and 102L as modifications of the piezoelectric vibrator unit constituting the piezoelectric vibrator. 14A to 14C, for convenience of illustration, the fixing part 221 and the connection parts 222 and 223 of the substrate 200 are not shown.

  The piezoelectric vibrating body unit 102J in FIG. 14A shows an example in which the pair of piezoelectric elements 110b and 110c in the second group in FIG. 3A is omitted. In the piezoelectric vibrating body unit 102K in FIG. 14B, the third group of piezoelectric elements 110e in FIG. 3A is omitted, and the four other piezoelectric elements 110a, 110b, 110c, and 110d are arranged in a larger area than in FIG. 3A. An example is shown. In the piezoelectric vibrating body unit 102L of FIG. 14C, the four piezoelectric elements 110a, 110b, 110c, and 110d of the first and second groups of FIG. 3A are omitted, and one piezoelectric element 110e of the third group is large. An example in which areas are arranged is shown.

  You may make it comprise a piezoelectric actuator using the piezoelectric vibrating body comprised by these piezoelectric vibrating body units 102J, 102K, and 102L.

F. Piezoelectric motor using a piezoelectric actuator:
FIG. 15 is an explanatory diagram showing an example of a piezoelectric motor using the piezoelectric actuator 10. The support portion 220 is omitted for convenience of illustration. The convex portion 20 of the piezoelectric actuator 10 is in contact with the outer periphery of a rotor 95 as a driven member (driven body). In the example illustrated in FIG. 15, as described with reference to FIG. 6B, the vibration unit 210 is in the plane of the vibration unit 210 according to the expansion and contraction of the two piezoelectric elements 110 a and 110 d in the first group in the direction of the arrow x. In response to this, the tip of the convex portion 20 reciprocates in the direction of the arrow y or moves elliptically. As a result, the rotor 95 rotates around the center 96 in a predetermined direction z (clockwise direction in FIG. 15). When an AC voltage or a pulsating voltage is applied to the two piezoelectric elements 110b and 110c (FIG. 3A) of the second group, the rotor 95 rotates in the reverse direction. As described with reference to FIG. 6A, the piezoelectric actuator 10 expands and contracts in the longitudinal direction in accordance with the expansion and contraction of the third group of piezoelectric elements 110e in the center, so that the force applied from the convex portion 20 to the rotor 95 is increased. Is possible. As described above, the piezoelectric actuator 10 can be used as a piezoelectric motor that is one of piezoelectric devices. Such an operation of the piezoelectric actuator 10 is described in Japanese Patent Application Laid-Open No. 2004-320979 (or corresponding US Pat. No. 7,224,102), the disclosure of which is incorporated by reference.

G. Embodiments of a device equipped with a piezoelectric actuator:
The piezoelectric actuator described above can apply a large force to the driven member by utilizing resonance, and can be applied to various devices. The piezoelectric actuator 10 is, for example, a robot (including an electronic component transport device (IC handler)), a hand (including a finger assist device), a medication pump, a clock calendar feeding device, and a printing device (for example, a paper feeding mechanism. The piezoelectric actuator used in the head is not applicable to the head because it does not resonate the diaphragm, and can be used as a driving device in various devices. Hereinafter, representative embodiments will be described.

  FIG. 16 is an explanatory diagram showing an example of a robot 2050 that uses the above-described piezoelectric actuator 10 as a piezoelectric motor. The robot 2050 includes a plurality of link portions 2012 (also referred to as “link members”) and an arm 2010 (“a” that includes a plurality of joint portions 2020 that connect the link portions 2012 in a rotatable or bendable state. It is also called “arm”. Each joint part 2020 incorporates the piezoelectric actuator 10 described above, and the joint part 2020 can be rotated or bent by an arbitrary angle using the piezoelectric actuator 10. A hand 2000 is connected to the tip of the arm 2010. The hand 2000 includes a pair of grip portions 2003. The hand 2000 also incorporates the piezoelectric actuator 10, and the piezoelectric actuator 10 can be used to open and close the gripping part 2003 to grip an object. The piezoelectric actuator 10 is also provided between the hand 2000 and the arm 2010, and the hand 2000 can be rotated with respect to the arm 2010 by using the piezoelectric actuator 10.

  FIG. 17 is an explanatory diagram of a wrist portion of the robot 2050 shown in FIG. The wrist joint portion 2020 sandwiches the wrist rotating portion 2022, and the wrist link portion 2012 is attached to the wrist rotating portion 2022 so as to be rotatable around the central axis O of the wrist rotating portion 2022. . The wrist rotation unit 2022 includes the piezoelectric actuator 10, and the piezoelectric actuator 10 rotates the wrist link unit 2012 and the hand 2000 around the central axis O. The hand 2000 is provided with a plurality of grips 2003. The proximal end portion of the grip portion 2003 is movable in the hand 2000, and the piezoelectric actuator 10 is mounted on the base portion of the grip portion 2003. For this reason, by operating the piezoelectric actuator 10, it is possible to move the gripping part 2003 and grip the object.

  Note that the robot is not limited to a single-arm robot, and the piezoelectric actuator 10 can be applied to a multi-arm robot having two or more arms. Here, the wrist joint 2020 and the hand 2000 include, in addition to the piezoelectric actuator 10, a power line for supplying power to various devices such as a force sensor and a gyro sensor, a signal line for transmitting a signal, and the like. Therefore, a great deal of wiring is required. Therefore, it is very difficult to arrange wiring inside the joint portion 2020 and the hand 2000. However, since the piezoelectric actuator 10 of the above-described embodiment can reduce the drive current as compared with a normal electric motor or a conventional piezoelectric drive device, the joint portion 2020 (particularly, the joint portion at the tip of the arm 2010) or the hand 2000 is used. Wiring can be arranged even in such a small space.

  In the above description, the robot 2050 including the hand 2000 has been described as an example. However, the hand 2000 may be configured not only as a part of the robot 2050 but also as a single product.

  FIG. 18 is an explanatory diagram showing a finger assist device 1000 that uses the piezoelectric actuator 10 described above. The finger assist device 1000 includes a first finger assist unit 1001, a second finger assist unit 1002, and a base member 1003, and is attached to the finger 700. The first finger assist unit 1001 includes the piezoelectric actuator 10, a speed reducer 501, and a finger support unit 701. The second finger assist unit 1002 includes the piezoelectric actuator 10, a speed reducer 502, a finger support unit 702, and a band 703. Except for the band 703, the first finger assist unit 1001 and the second finger assist unit 1002 have substantially the same configuration. The band 703 fixes the second finger assist unit 1002 from the ventral side of the finger 700. Note that the band 703 is also provided in the first finger assist unit 1001, but is omitted in FIG. 18. The finger assist device 1000 assists bending and stretching of the finger 700 by the piezoelectric actuator 10. In the present embodiment, the finger assist device 1000 has been described as assisting the bending and stretching of the finger 700, but a robot hand may be used instead of the finger 700, and the hand and the finger assist device 1000 may be integrated. . In this case, the hand is driven by the piezoelectric actuator 10 to bend and stretch.

  FIG. 19 is an explanatory diagram showing an example of a liquid feed pump 2200 that uses the piezoelectric actuator 10 described above. A liquid feed pump 2200 includes a reservoir 2211, a tube 2212, a piezoelectric actuator 10, a rotor (driven body) 2222, a deceleration transmission mechanism 2223, a cam 2202, a plurality of fingers 2213 and 2214, and a case 2230. 2215, 2216, 2217, 2218, and 2219 are provided. The reservoir 2211 is a storage unit for storing a liquid to be transported. The tube 2212 is a tube for transporting the liquid sent out from the reservoir 2211. The convex portion 20 of the piezoelectric actuator 10 is provided so as to be pressed against the side surface of the rotor 2222, and the piezoelectric actuator 10 rotationally drives the rotor 2222. The rotational force of the rotor 2222 is transmitted to the cam 2202 via the deceleration transmission mechanism 2223. Fingers 2213 to 2219 are members for closing the tube 2212. When the cam 2202 rotates, the fingers 2213 to 2219 are sequentially pushed outward in the radial direction by the protrusion 2202A of the cam 2202. The fingers 2213 to 2219 close the tube 2212 in order from the upstream side in the transport direction (reservoir 2211 side). Thereby, the liquid in the tube 2212 is transported to the downstream side in order. In this way, it is possible to realize a small liquid feed pump 2200 that can deliver an extremely small amount with high accuracy and that is small. In addition, arrangement | positioning of each member is not restricted to what was illustrated. Further, a member such as a finger may not be provided, and a ball or the like provided on the rotor 2222 may close the tube 2212. The liquid feed pump 2200 as described above can be used for a medication device that administers a drug solution such as insulin to the human body. Here, by using the piezoelectric actuator 10 of the above-described embodiment, the driving current is smaller than that of the conventional piezoelectric driving device, so that the power consumption of the dispensing device can be suppressed. Therefore, it is particularly effective when the medication apparatus is battery-driven.

  The present invention is not limited to the above-described embodiments, examples, and modifications, and can be realized with various configurations without departing from the spirit thereof. For example, the technical features in the embodiments, examples, and modifications corresponding to the technical features in each embodiment described in the summary section of the invention are to solve some or all of the above-described problems, or In order to achieve part or all of the above-described effects, replacement or combination can be performed as appropriate. Further, if the technical feature is not described as essential in the present specification, it can be deleted as appropriate.

  DESCRIPTION OF SYMBOLS 10 ... Piezoelectric actuator, 20 ... Convex part, 24 ... Mass adjustment part, 30 ... Outer frame, 40 ... Inner frame, 42, 43, 44 ... Side part, 50 ... Leaf spring, 51 ... Outer frame part, 52 ... Center part 53, 54 ... Spring part, 60 ... Intermediate member, 70 ... Fixed frame, 71 ... Opening part, 80 ... Cover, 90 ... Flexible substrate, 95 ... Rotor (driven body) 96 ... Center, 100 ... Piezoelectric vibration part, DESCRIPTION OF SYMBOLS 101,101B ... Piezoelectric vibrator, 102, 102J-102L ... Piezoelectric vibrator unit (vibrator), 110, 110a-110e ... Piezoelectric element, 111 ... Piezoelectric element structure, 130 ... First electrode, 140 ... Piezoelectric body, 150 ... Second electrode, 200 ... Substrate, 201 ... Insulating layer, 205 ... Gap, 210 ... Vibrating part, 214 ... Side, 216 ... Recess, 220 ... Supporting part, 221 ... Fixing part, 222 ... Connecting part (first connecting part) 223 ... Connection part (second connection part), 240 ... insulating layer, 250 ... wiring layer, 251 ... first wiring, 252 ... second wiring, 253 ... third wiring, 254 ... fourth wiring, 260 ... covering part (protective layer) 270 ... Adhesive layer 400 ... Drive circuit 500 ... Impedance measurement circuit 501,502 ... Speed reducer 700 ... Finger 701,702 ... Finger support part 703 ... Band 1000 ... Finger assist device 1001,1002 ... finger assist part, 1003 ... base member, 2000 ... hand, 2003 ... grip part, 2010 ... arm, 2012 ... link part, 2020 ... joint part, 2022 ... wrist rotation part, 2050 ... robot, 2200 ... liquid feed pump, 2202 ... Cam, 2202A ... Projection, 2211 ... Reservoir, 2212 ... Tube, 2213-2219 ... Finger, 2222 ... Rotor, 2 23 ... the reduction-transmission mechanism, 2230 ... case

Claims (15)

A housing having an opening;
A vibrating body having a convex portion and housed in the housing;
With
A piezoelectric actuator, wherein a mass adjusting unit that adjusts the mass of the vibrating body is arranged on the vibrating body.   The piezoelectric actuator according to claim 1, wherein the vibrating body is laminated.   The piezoelectric actuator according to claim 1, further comprising an urging portion that urges the vibrating body in a direction in which the convex portion protrudes.   The piezoelectric actuator according to any one of claims 1 to 3, wherein the mass adjusting unit is disposed on a surface of the vibrating body that intersects a direction in which the convex portion protrudes.   5. The piezoelectric actuator according to claim 1, wherein at least a part of the mass adjusting portion is disposed in the opening in a plan view from a direction in which the convex portion protrudes.   The piezoelectric actuator according to any one of claims 1 to 5, further comprising a wiring board for transmitting a driving signal of the vibrating body.   A piezoelectric motor provided with the piezoelectric actuator as described in any one of Claims 1 thru | or 6.   A robot comprising the piezoelectric actuator according to any one of claims 1 to 6.   A hand comprising the piezoelectric actuator according to any one of claims 1 to 6.   A liquid feed pump comprising the piezoelectric actuator according to any one of claims 1 to 6. (A) A step of preparing a piezoelectric actuator in which a vibrating body having a protruding convex portion and a biasing portion that biases the vibrating body in a direction in which the convex portion protrudes are accommodated in a housing. When,
(B) measuring a resonance frequency of the vibrating body;
(C) adjusting the mass of the vibrating body when the resonance frequency measured in the step (b) is out of an allowable range;
A method for adjusting the resonance frequency of a piezoelectric actuator including:   The method of adjusting a resonance frequency of a piezoelectric actuator according to claim 11, wherein the step (c) includes a step of measuring a resonance frequency of the vibrating body after adjustment.   The method for adjusting a resonance frequency of a piezoelectric actuator according to claim 11, wherein the step (b) and the step (c) are repeated.   The method for adjusting a resonance frequency of a piezoelectric actuator according to claim 11, wherein the step (c) adjusts the mass by adding a weight.   The method for adjusting a resonance frequency of a piezoelectric actuator according to any one of claims 11 to 13, wherein the step (c) adjusts the mass by removing a part of the vibrating body or a weight added in advance.

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