Source: https://patents.google.com/patent/JP4460742B2/en
Timestamp: 2019-12-06 05:43:05
Document Index: 724647848

Matched Legal Cases: ['art 20', 'arts 16', 'art 20', 'art 20', 'art 20', 'art 20', 'art 20', 'art 20', 'art 20', 'art 20', 'art 20', 'art 20', 'art 20', 'art 22', 'art 20', 'art 20', 'art 20', 'art 18', 'art 20', 'arts 16', 'art 20', 'art 20', 'art 20', 'art 22', 'art 20', 'art 20', 'art 20', 'art 16', 'art 22', 'art 16', 'art 16', 'art) 204', 'art 20', 'art 20', 'art 20', 'arts 16', 'art 20', 'art 20', 'art 20', 'art 20', 'art 20', 'art 22', 'art 16', 'art 22', 'art 16', 'art 20', 'art 204', 'art 16']

JP4460742B2 - Piezoelectric / electrostrictive device and manufacturing method thereof - Google Patents
Piezoelectric / electrostrictive device and manufacturing method thereof Download PDF
JP4460742B2
JP4460742B2 JP2000297793A JP2000297793A JP4460742B2 JP 4460742 B2 JP4460742 B2 JP 4460742B2 JP 2000297793 A JP2000297793 A JP 2000297793A JP 2000297793 A JP2000297793 A JP 2000297793A JP 4460742 B2 JP4460742 B2 JP 4460742B2
electrostrictive device
JP2000297793A
JP2002026412A (en
政彦 滑川
1999-10-01 Priority to JP28152299 priority Critical
1999-10-28 Priority to JP30784499 priority
1999-11-16 Priority to JP32619599 priority
1999-12-27 Priority to JP37196799 priority
2000-01-21 Priority to JP2000013576 priority
2000-01-24 Priority to JP2000015123 priority
2000-03-01 Priority to JP2000056434 priority
2000-03-13 Priority to US09/524,042 priority patent/US6498419B1/en
2000-05-01 Priority to JP2000-133012 priority
2000-05-01 Priority to JP2000133012 priority
2000-05-01 Priority to JP09/524042 priority
2000-05-11 Priority to JP11-326195 priority
2000-05-11 Priority to JP11-281522 priority
2000-05-11 Priority to JP2000-56434 priority
2000-05-11 Priority to JP2000-15123 priority
2000-05-11 Priority to JP11-307844 priority
2000-05-11 Priority to JP2000-13576 priority
2000-05-11 Priority to JP11-371967 priority
2000-09-29 Priority to JP2000297793A priority patent/JP4460742B2/en
2000-09-29 Application filed by 日本碍子株式会社 filed Critical 日本碍子株式会社
2002-01-25 Publication of JP2002026412A publication Critical patent/JP2002026412A/en
2010-05-12 Publication of JP4460742B2 publication Critical patent/JP4460742B2/en
The present invention relates to a piezoelectric / electrostrictive device having a movable part that operates based on a displacement operation of a piezoelectric / electrostrictive element, or a piezoelectric / electrostrictive device that can detect displacement of the movable part by a piezoelectric / electrostrictive element and its manufacture. More specifically, the present invention relates to a piezoelectric / electrostrictive device that is excellent in strength, impact resistance, and moisture resistance, and that can efficiently move a movable part to a large extent, and a manufacturing method thereof.
Recently, in the fields of optics, magnetic recording, precision processing, etc., a displacement element capable of adjusting the optical path length and position on the submicron order is required, and voltage is applied to a piezoelectric / electrostrictive material (for example, a ferroelectric material). Development of a displacement element using displacement due to the inverse piezoelectric effect or electrostrictive effect caused by the application of is being advanced.
Conventionally, as such a displacement element, for example, as shown in FIG. 53, by providing a hole 402 in a plate-like body 400 made of a piezoelectric / electrostrictive material, the fixed portion 404 and the movable portion 406 are supported. A piezoelectric actuator is disclosed in which a beam portion 408 is integrally formed and an electrode layer 410 is provided on the beam portion 408 (see, for example, Japanese Patent Laid-Open No. 10-136665).
In the piezoelectric actuator, when a voltage is applied to the electrode layer 410, the beam portion 408 expands and contracts in the direction connecting the fixed portion 404 and the movable portion 406 due to the inverse piezoelectric effect or the electrostrictive effect. An arcuate displacement or a rotational displacement in the plane of the body 400 is possible.
On the other hand, Japanese Patent Application Laid-Open No. 63-64640 discloses an actuator using a bimorph, in which the bimorph electrode is divided and provided, and the divided electrode is selected and driven to achieve high-precision positioning at high speed. This technique (especially FIG. 4) discloses a structure in which two bimorphs are used facing each other, for example.
However, in the piezoelectric actuator, the displacement in the expansion / contraction direction of the piezoelectric / electrostrictive material (that is, the in-plane direction of the plate-like body 400) is directly transmitted to the movable portion 406, so that the operation amount of the movable portion 406 is small. There was a problem.
In addition, since all parts of piezoelectric actuators are made of piezoelectric / electrostrictive materials, which are fragile and relatively heavy materials, they have low mechanical strength and are inferior in handling properties, impact resistance, and moisture resistance. However, the piezoelectric actuator itself is heavy, and has a problem that it is easily affected by vibrations that are harmful to the operation (for example, residual vibrations and noise vibrations during high-speed operation).
In order to solve the above problems, it has been proposed to fill the hole 402 with a flexible filler. However, if the filler is simply used, the amount of displacement due to the inverse piezoelectric effect or the electrostrictive effect is proposed. It is clear that is reduced.
The present invention has been made in consideration of such problems, and can improve the life of the device, the handleability of the device, the mounting property of the component to the movable part, or the fixing property of the device. The movable part can be greatly displaced at a relatively low voltage, and the speed of displacement of the device, particularly the movable part, can be increased (high resonance frequency), and the influence of harmful vibrations can be achieved. To obtain a displacement element that is not easily affected, can respond at high speed, has high mechanical strength, has excellent handling properties, impact resistance, and moisture resistance, and a sensor element that can accurately detect vibrations of moving parts. It is an object of the present invention to provide a piezoelectric / electrostrictive device that can be manufactured and a method for manufacturing the same.
FirstThe present inventionFixed to a fixed portion that is a rectangular body, a pair of opposing rectangular plate-like thin plate portions fixed to a pair of opposing side surfaces of the fixed portion, and a pair of opposed surfaces of the pair of thin plate portions, respectively A pair of opposed movable parts,Of the pair of thin plate portions, at leaston the other handThin platePressureElectro / electrostrictive elementFormationPiezoelectric / electrostrictive device, comprising:Each of the pair of thin plate portions is made of metal, and the piezoelectric / electrostrictive element is formed on a surface of the one thin plate portion opposite to a surface facing the other thin plate portion,AboveA pair ofMovablePart isHave end faces facing each otherDoIt is characterized by that.In this case, the distance between the end surfaces of the pair of movable portions may be equal to or longer than the length of the side extending toward the fixed portion of the end surfaces of the movable portions.
The piezoelectric / electrostrictive device according to the second aspect of the present invention includes a movable portion that is a rectangular body, and a pair of opposing rectangular plate-like thin plate portions that are fixed to a pair of opposite side surfaces of the movable portion, respectively. A pair of opposing fixed portions fixed respectively to a pair of opposing surfaces of the pair of thin plate portions, and a piezoelectric / electrostrictive element is disposed on at least one of the pair of thin plate portions. In the formed piezoelectric / electrostrictive device, each of the pair of thin plate portions is made of metal, and one of the thin plate portions is on the surface opposite to the surface facing the other thin plate portion. / An electrostrictive element is formed, and the pair of fixing portions have end faces facing each other.
In this case, since the thin plate portion is made of metal, it is excellent in strength and toughness and can cope with an abrupt displacement operation. In other words, the present invention can sufficiently cope with fluctuations in the usage environment and severe usage conditions, has excellent impact resistance, can extend the life of the piezoelectric / electrostrictive device, and can improve handling properties. The thin plate part can be displaced greatly with relatively low voltage, and the thin plate part has high rigidity, and the actuator film is thick and the rigidity is high. Frequency) can be achieved.
The piezoelectric / electrostrictive element may be in the form of a film and may be fixed to the thin plate portion with an adhesive. The piezoelectric / electrostrictive element may include a piezoelectric / electrostrictive layer and a pair of electrodes formed on the piezoelectric / electrostrictive layer. In this case, the vibration by the piezoelectric / electrostrictive element can be efficiently transmitted to the movable part or the fixed part through the thin plate part, and the responsiveness can be improved.
In particular, in the piezoelectric / electrostrictive element, it is preferable that a plurality of the piezoelectric / electrostrictive layer and the pair of electrodes are configured in a laminated form. With such a configuration, the generation force of the piezoelectric / electrostrictive element is increased, so that a large displacement is achieved, and the rigidity of the piezoelectric / electrostrictive device itself is increased, so that a high resonance frequency is achieved. There is a feature that speeding up of the displacement operation can be easily achieved.
As the adhesive, an organic resin, glass, brazing material, or solder can be used.
Moreover, a cut part may be provided in either one of the movable part or the fixed part, and a part of the cut part may constitute the end surfaces facing each other. In this case, it is good also as a space | gap between the said opposing end surfaces, Between the said mutually opposing end surfaces, the same member as any one structural member of the said movable part or a fixed part, or different members, for example, glass, Cement, organic resin etc. are mentioned, preferably organic resin such as epoxy, acrylic, polyimide, phenol, silicone, terpene, xylene, styrene, melamine, methacryl, rubber, etc. or these A mixture or copolymer may be interposed. Among these, it is preferable to interpose an epoxy-based, acrylic-based, methacryl-based organic resin, or the like from the viewpoints of bondability, handleability, hardness, and the like. It is also preferable to mix a filler such as an inorganic material for the purpose of further increasing the hardness.
In particular, when a gap is formed between the opposed end surfaces, a member that is lighter than the constituent member of the movable portion or the fixed portion is interposed between the opposed end surfaces, or even between the end surfaces by a small member. By joining, it is possible to effectively reduce the weight of the movable part or the fixed part. Therefore, it is possible to increase the resonance frequency without reducing the amount of displacement of the movable part or the fixed part.
Further, when a gap is formed between the opposing end surfaces, a part of the movable part or the fixed part including one end surface and another part of the movable part or the fixed part including the other end surface are easily bent. Become stronger against deformation. Therefore, the handling property of the piezoelectric / electrostrictive device is excellent.
Furthermore, since the distance between the end faces is equal to or greater than the length of the movable part, when other parts are attached to the movable part, the influence of these dimensional precisions can be easily suppressed even if the dimensional precision of the end faces and parts is low. Therefore, the mounting property of the components can be improved. Here, considering the case where the component is fixed with an adhesive or the like, for example, the article can be held between both sides, so that the component can be securely fixed.
Further, by holding the article sandwiched from both sides, the height of the article and the height of the movable part are not simply added, and the overall height including the article can be kept low. Furthermore, since the length of the movable part can be made smaller than the distance on the end face side, physical properties such as an adhesive that adheres the components act effectively, and the displacement can be increased.
On the other hand, when the fixing portion has end faces facing each other, the piezoelectric / electrostrictive device according to the present invention can be firmly fixed to a predetermined fixing portion, and the reliability can be improved.
Thus, in the present invention, it is possible to reduce the weight of the piezoelectric / electrostrictive device, and in particular, to reduce the weight of the movable part or the fixed part.
By the way, in the manufacture of a piezoelectric / electrostrictive device, when a piezoelectric / electrostrictive element is fixed to a metal thin plate portion with an adhesive, the piezoelectric / electrostrictive element and / or the thin plate, particularly in the solidifying stage of the adhesive. Internal residual stress is generated in the part to be the part.
From this state, when a piezoelectric / electrostrictive device is manufactured and used, even if a predetermined electric field is applied to the piezoelectric / electrostrictive layer constituting the piezoelectric / electrostrictive element, a desired displacement may not be exhibited in the movable portion. This is because the material characteristics of the piezoelectric / electrostrictive layer and the displacement operation of the movable part are hindered by the internal residual stress generated in the piezoelectric / electrostrictive element and / or the thin plate part.
In the present invention, since the end surfaces facing each other are provided on either the movable portion or the fixed portion, the distance between the end surfaces is the internal residual generated in the piezoelectric / electrostrictive element and / or the thin plate portion. For example, it shrinks due to the stress. That is, the internal residual stress generated in the piezoelectric / electrostrictive element and / or the thin plate portion is released by the movement of the end face.
Furthermore, in the present invention, since the distance between the end faces is increased, even if the distance between the end faces is reduced by the internal residual stress, it is possible to provide a margin for attaching other parts between the end faces. .
As described above, in the present invention, the displacement operation of the movable portion is not hindered by the internal residual stress, and the displacement operation of the movable portion almost as designed can be obtained. In addition, the mechanical strength of the piezoelectric / electrostrictive device can be improved by releasing the internal residual stress.
Further, the pair of thin plate portionsOppositeWith the inner wallOpposing to the fixed portions of the plurality of membersOf the inner wall and the fixing partOpposite the inner walls of the plurality of membersWhen a hole is formed by the inner wall, the hole may be filled with a gel material. In this case, normally, the displacement operation of the movable part is limited due to the presence of the filler, but the above-described invention is reduced in weight and displacement of the movable part due to the formation of the end face on the movable part or the fixed part. Since the amount is increased, the restriction of the displacement operation of the movable part by the filler is canceled out, and the effect due to the presence of the filler, that is, higher resonance frequency and securing of rigidity can be realized. .
In the present invention, when the plurality of members described above are interposed between the end surfaces, at least one member of the plurality of members may be an organic resin.
next,ThirdThe present inventionFixed to a fixed portion that is a rectangular body, a pair of opposing rectangular plate-like thin plate portions fixed to a pair of opposing side surfaces of the fixed portion, and a pair of opposed surfaces of the pair of thin plate portions, respectively A pair of opposed movable parts, each of the pair of thin plate parts is made of metal,Of the pair of thin plate portions, at leaston the other handThin platePressureElectro / electrostrictive elementFormationA method for manufacturing a piezoelectric / electrostrictive device, comprising: attaching a metal plate that will later become a thin plate portion to a first substrate;WorkAs a result, at least one excision process on the second substrate has end faces facing each other.DoMovablePartIt has the process of forming, It is characterized by the above-mentioned.
According to a fourth aspect of the present invention, there is provided a method for manufacturing a piezoelectric / electrostrictive device comprising: a movable portion that is a rectangular body; and a pair of opposed rectangular plates that are respectively fixed to a pair of opposing side surfaces of the movable portion. A pair of opposed movable parts fixed to a pair of opposed surfaces of the pair of thin plate portions, the pair of thin plate portions being made of metal, and the pair of thin plate portions A method for manufacturing a piezoelectric / electrostrictive device in which a piezoelectric / electrostrictive element is formed on at least one thin plate portion, wherein a metal plate that will later become a thin plate portion is fixed to a first base, The method includes a step of manufacturing a base and a step of forming the fixing portion having end faces facing each other by at least one excision process on the second base.
As a result, a movable portion or a fixed portion having end faces facing each other is provided, so that the internal residual stress generated in the piezoelectric / electrostrictive element and / or the thin plate portion at the time of manufacture is such that the distance between the end faces is, for example, It is released by shrinking, and the displacement operation of the movable part is not hindered by the internal residual stress. In particular, since a metal is used as the thin plate portion, it is excellent in strength and toughness and can cope with a sudden displacement operation.
Moreover, since the movable part or the fixed part is reduced in weight by providing the movable part or the fixed part having opposite end surfaces, it becomes possible to increase the resonance frequency without reducing the displacement amount of the movable part. A piezoelectric / electrostrictive device can be manufactured efficiently and easily, and mass production of a high-performance piezoelectric / electrostrictive device can be realized.
In addition, since the movable part or the fixed part is easily bent and is resistant to deformation, the handling property of the piezoelectric / electrostrictive device is excellent, and the existence of the end faces facing each other and the distance between the end faces are increased. Therefore, when attaching other components to the movable part, even if the dimensional accuracy of the end face and the components is low, the influence of these dimensional accuracy can be easily suppressed, so that the mounting property of the components can be improved. . Further, the displacement can be improved when the components are bonded to each other.
And in the said manufacturing method, you may make it have the process of adhering the said piezoelectric / electrostrictive element through the adhesive agent to the outer surface of the said metal plate used as a thin-plate part later. Accordingly, in the manufacture of the piezoelectric / electrostrictive device, particularly when the piezoelectric / electrostrictive element is fixed to the metal thin plate portion with the adhesive, particularly in the solidifying stage of the adhesive, the piezoelectric / electrostrictive element and / or Alternatively, since the internal residual stress generated in the thin plate portion can be effectively released, when manufacturing a piezoelectric / electrostrictive device, the weight of the piezoelectric / electrostrictive device, particularly the movable portion or the fixed portion, The handling property of the piezoelectric / electrostrictive device, the attachment property of the component to the movable part, and the fixing property of the piezoelectric / electrostrictive device can be improved, whereby the movable part can be greatly displaced.
Note that the piezoelectric / electrostrictive element may be fixed to the outer surface of the metal plate in advance before the metal plate to be the thin plate portion is fixed to the first base.
And when the first substrate is composed of a ceramic laminate, a ceramic laminate production step of producing a ceramic laminate by laminating and firing at least one ceramic green sheet having at least a window, and You may make it have the hybrid laminated body production process which adheres the metal plate used as the said thin-plate part to a ceramic laminated body later via an adhesive agent, and produces a hybrid laminated body.
In this case, in the ceramic laminate manufacturing step, the ceramic laminate is manufactured by firing a plurality of ceramic green sheets having window portions for forming the movable portion or the fixed portion having at least end surfaces facing each other. You may do it.
In the case where the first substrate is made of metal, the first substrate may include a step of manufacturing the first substrate by laminating at least one metal sheet having a window portion. You may make it comprise a 1st base | substrate with a bulk metal member.
In addition, you may make it include the process of interposing the some member different from the structural member of the said movable part or a fixed part between the said end surfaces which mutually oppose. In this case, an organic resin can be used as at least one member among the plurality of members.
As the adhesive, an adhesive made of an organic resin or an adhesive made of glass, brazing material, or solder can be used.
Therefore, according to the piezoelectric / electrostrictive device and the manufacturing method thereof according to the present invention, various transducers, various actuators, frequency domain functional components (filters), transformers, vibrators and resonators for communication and power, resonators, In addition to active elements such as discriminators, it can be used as sensor elements for various sensors such as ultrasonic sensors, acceleration sensors, angular velocity sensors, impact sensors, and mass sensors. It can be suitably used for various actuators used in mechanisms for displacement, positioning adjustment, and angle adjustment of precision parts.
Embodiments of a piezoelectric / electrostrictive device and a manufacturing method thereof according to the present invention will be described below with reference to FIGS.
Here, the piezoelectric / electrostrictive device is a concept including an element that mutually converts electrical energy and mechanical energy by a piezoelectric / electrostrictive element. Therefore, it is most suitably used as an active element such as various actuators and vibrators, particularly as a displacement element utilizing displacement due to the inverse piezoelectric effect or electrostriction effect, and also suitable as a passive element such as an acceleration sensor element or an impact sensor element. Can be used.
As shown in FIG. 1, the piezoelectric / electrostrictive device 10 </ b> A according to the first embodiment has an elongated rectangular parallelepiped shape as a whole, and is provided with a hole 12 at a substantially central portion in the major axis direction. A substrate 14 is provided.
The base 14 includes a pair of opposed thin plate portions 16a and 16b, a movable portion 20, a pair of thin plate portions 16a and 16b, and a fixed portion 22 that supports the movable portion 20, and at least the thin plate portions 16a and 16b. Piezoelectric / electrostrictive elements 24a and 24b are respectively formed on the respective parts.
In addition, about the said base | substrate 14, it is good also as a hybrid structure which combined what was manufactured with the material of ceramics and a metal besides what was comprised using ceramics or the metal. Further, the base 14 may adopt a structure such as a structure in which each part is bonded with an adhesive such as an organic resin or glass, a metal integrated structure integrated by brazing, soldering, eutectic bonding, welding, or the like. it can.
In the first embodiment, the base 14 has a hybrid structure in which the pair of thin plate portions 16a and 16b are made of metal, and the other movable portion 20 and the fixed portion 22 are made of ceramic. . Specifically, the metal thin plate portions 16 a and 16 b are fixed to the respective side surfaces of the ceramic movable portion 20 and the fixed portion 22 via an adhesive 200. Of course, the thin plate portions 16a and 16b, the movable portion 20 and the fixed portion 22 may all be made of metal.
The piezoelectric / electrostrictive elements 24a and 24b are prepared separately as described later, and the piezoelectric / electrostrictive elements 24a and 24b are prepared separately, and an adhesive such as organic resin or glass, brazing, soldering, In addition to being attached by eutectic bonding or the like, by using a film forming method, it is formed directly on the substrate 14 instead of the attachment. In the first embodiment, the piezoelectric / electrostrictive elements 24 a and 24 b are fixed to the thin plate portions 16 a and 16 b with an adhesive 202, respectively.
Further, in this piezoelectric / electrostrictive device 10A, for example, the rectangular hole 12 is formed by the inner walls of the pair of thin plate portions 16a and 16b, the inner wall 20a of the movable portion 20, and the inner wall 22a of the fixed portion 22. / The movable portion 20 is displaced by driving the electrostrictive elements 24a and / or 24b, or the displacement of the movable portion 20 is detected by the piezoelectric / electrostrictive elements 24a and / or 24b.
The piezoelectric / electrostrictive elements 24 a and 24 b include a piezoelectric / electrostrictive layer 26 and a pair of electrodes 28 and 30 formed on both sides of the piezoelectric / electrostrictive layer 26, and the pair of electrodes 28. And 30, one electrode 28 is formed on at least one pair of thin plate portions 16a and 16b.
In the example of FIG. 1, the pair of electrodes 28 and 30 constituting the piezoelectric / electrostrictive elements 24a and 24b and the respective tip surfaces of the piezoelectric / electrostrictive layer 26 are substantially aligned, and the piezoelectric / electrostrictive elements 24a and 24b A substantial driving portion 18 (a portion where the pair of electrodes 28 and 30 overlap with the piezoelectric / electrostrictive layer 26 sandwiched therebetween) extends from a part of the outer surface of the fixing portion 22 to a part of the outer surface of the thin plate portions 16a and 16b. It is formed continuously. In particular, in this example, the front end surfaces of the pair of electrodes 28 and 30 are positioned slightly closer to the rear end than the inner wall 20a of the movable portion 20. Of course, the piezoelectric / electrostrictive elements 24a and 24b may be formed so that the substantial driving portion 18 is located from a part of the movable part 20 to a part of the thin plate parts 16a and 16b.
In the piezoelectric / electrostrictive device 10A according to the first embodiment described above, as shown in FIG. 1, end surfaces 36a and 36b facing each other are formed on the movable portion 20. The end faces 36a and 36b are side surfaces of the movable portion 20, that is, surfaces substantially parallel to the element formation surface, and are separated from each other from the upper surface of the movable portion 20 to the hole portion 12. At this time, for example, as shown in FIG. 12, it is preferable that distances Da and Db from the central axis n of the movable portion 20 to the end faces 36a and 36b are substantially equal.
Further, a gap (air) 38 may be interposed between the end faces 36a and 36b, for example, as shown in FIG. 1, or the piezoelectric / electrostrictive according to the seventh modification shown in FIG. As shown in FIG. 12, the device 10 </ b> Ag or a member 40 made of a resin or the like different from the constituent members of the movable portion 20 may be interposed between the end surfaces 36 a and 36 b.
By the way, in the piezoelectric / electrostrictive device 10A according to the first exemplary embodiment, voltage application to the pair of electrodes 28 and 30 is performed on both side surfaces (element formation surfaces) of the fixed portion 22 of the electrodes 28 and 30, respectively. ) Through the terminals (pads) 32 and 34 formed thereon. The positions of the terminals 32 and 34 are such that the terminal 32 corresponding to one electrode 28 is formed near the rear end of the fixing portion 22, and the terminal 34 corresponding to the other electrode 30 on the external space side is the inner wall 22 a of the fixing portion 22. It is formed close.
In this case, the piezoelectric / electrostrictive device 10A can be fixed separately using a surface different from the surface on which the terminals 32 and 34 are arranged. As a result, the piezoelectric / electrostrictive device 10A is fixed. And high reliability in both the circuit and the electrical connection between the terminals 32 and 34. In this configuration, the terminals 32 and 34 and the circuit are electrically connected by a flexible printed circuit (also referred to as FPC), a flexible flat cable (also referred to as FFC), wire bonding, or the like.
As the configuration of the piezoelectric / electrostrictive elements 24a and 24b, in addition to the configuration shown in FIG. 1, the piezoelectric / electrostrictive elements 24a and 24b are similar to the piezoelectric / electrostrictive device 10Aa according to the first modification shown in FIG. The tip portions of the pair of electrodes 28 and 30 constituting the same may be aligned so that only the tip portion of the piezoelectric / electrostrictive layer 26 protrudes to the movable portion 20 side, or the second modification shown in FIG. As in the piezoelectric / electrostrictive device 10Ab according to the example, the tip portions of one electrode 28 and the piezoelectric / electrostrictive layer 26 are aligned, and only the tip portion of the other electrode 30 is positioned closer to the fixed portion 22. Also good. In the piezoelectric / electrostrictive device 10Ab shown in FIG. 3, an example in which end faces 36a and 36b facing each other are provided on the fixed portion 22 instead of the movable portion 20 is shown.
In addition, as in the piezoelectric / electrostrictive device 10Ac according to the third modification shown in FIG. 4, each electrode 28 and each tip of the piezoelectric / electrostrictive layer 26 are extended to the side surface of the movable portion 20, and the other The distal end portion of the electrode 30 may be positioned substantially at the center in the length direction (Z-axis direction) of the thin plate portions 16a and 16b.
In the above-described example, the piezoelectric / electrostrictive elements 24a and 24b are configured by the single-layered piezoelectric / electrostrictive layer 26 and the pair of electrodes 28 and 30, but in addition, the piezoelectric / electrostrictive elements 24a and 24b. It is also preferable that the piezoelectric / electrostrictive layer 26 and a plurality of the pair of electrodes 28 and 30 are formed in a laminated form.
For example, like the piezoelectric / electrostrictive device 10Ad according to the fourth modification shown in FIG. 5, the piezoelectric / electrostrictive layer 26 and the pair of electrodes 28 and 30 each have a multilayer structure, and one electrode 28 and the other electrode 30. Of the piezoelectric / electrostrictive element in which the one electrode 28 and the other electrode 30 overlap each other with the piezoelectric / electrostrictive layer 26 interposed therebetween (substantially driving portion 18). It is good also as 24a and 24b. In FIG. 5, the piezoelectric / electrostrictive layer 26 has a three-layer structure, and one electrode 28 is formed separately on the lower surface of the first layer (side surfaces of the thin plate portions 16a and 16b) and the upper surface of the second layer, The other electrode 30 is formed separately on the upper surface of the first layer and the upper surface of the third layer, and terminals 32 a and 32 b are provided at each end of one electrode 28, respectively. The example which provided the terminal 34a and 34b in the part, respectively is shown.
Further, like the piezoelectric / electrostrictive device 10Ae according to the fifth modification shown in FIG. 6, the piezoelectric / electrostrictive layer 26 and the pair of electrodes 28 and 30 have a multilayer structure, respectively, and one electrode 28 and the other electrode. 30 are alternately stacked so as to have a substantially comb-shaped cross section, and the portion where the one electrode 28 and the other electrode 30 overlap with the piezoelectric / electrostrictive layer 26 interposed therebetween (substantially driving portion 18) is multistage. The piezoelectric / electrostrictive elements 24a and 24b may be configured. In FIG. 6, the piezoelectric / electrostrictive layer 26 has a three-layer structure, and one electrode 28 is in a comb-like shape so as to be positioned on the lower surface of the first layer (side surfaces of the thin plate portions 16a and 16b) and the upper surface of the second layer. In this example, the other electrode 30 is formed in a comb shape so as to be positioned on the upper surface of the first layer and the upper surface of the third layer. In the case of this configuration, the number of terminals 32 and 34 can be reduced as compared with the configuration of FIG. 5 by connecting one electrode 28 and the other electrode 30 in common, so that the piezoelectric / electrostrictive element can be reduced. The increase in size due to the multi-layering of 24a and 24b can be suppressed.
Further, as shown in FIG. 7, in another example of the piezoelectric / electrostrictive device 10Ae according to the fifth modification, the piezoelectric / electrostrictive elements 24a and 24b are arranged so that the tips thereof are on the thin plate portions 16a and 16b. You may make it form so that it may stay. In the example of FIG. 7, an example in which the tip portions of the piezoelectric / electrostrictive elements 24 a and 24 b are positioned at the substantially central portion in the length direction of the thin plate portion is shown. In this case, there is an advantage that the movable part 20 can be largely displaced.
Further, like the piezoelectric / electrostrictive device 10Af according to the sixth modification shown in FIG. 8, two multi-stage piezoelectric / electrostrictive elements 24a1 and 24b1 are respectively straddled between the fixed portion 22 and the thin plate portions 16a and 16b. The other two multi-stage piezoelectric / electrostrictive elements 24a2 and 24b2 may be formed so as to straddle the movable portion 20 and the thin plate portions 16a and 16b, respectively. In this case, the movable part 20 can be displaced greatly due to the effect of the piezoelectric / electrostrictive elements 24a and 24b having a multi-stage structure and the effect of increasing the action point for displacing the movable part 20, and the high speed It is excellent in responsiveness and is preferable.
Further, as in the piezoelectric / electrostrictive device 10Ag according to the seventh modification shown in FIG. 9, the piezoelectric / electrostrictive layer 26 has a two-layer structure, and one electrode 28 has a lower surface (thin plate portion 16a and 16b) and a multi-stage piezoelectric / electrostrictive element 24a and 24b formed in a comb shape so as to be positioned on the upper surface of the second layer and the other electrode 30 positioned on the upper surface of the first layer. It is good. In this example, a member different from the movable portion 20 is filled between the end faces 36 a and 36 b of the movable portion 20.
By forming the piezoelectric / electrostrictive elements 24a and 24b in a multi-stage structure, the generated force of the piezoelectric / electrostrictive elements 24a and 24b is increased, so that a large displacement is achieved and the piezoelectric / electrostrictive device 10A itself By increasing the rigidity, the resonance frequency can be increased and the speed of the displacement operation can be easily increased.
If the number of stages is increased, the driving force can be increased, but the power consumption increases accordingly. Therefore, in actual implementation, the number of stages may be appropriately determined according to the application and use state. Further, in the piezoelectric / electrostrictive device 10A according to the first embodiment, even if the piezoelectric / electrostrictive elements 24a and 24b have a multi-stage structure and the driving force is increased, the widths of the thin plate portions 16a and 16b ( Since the distance in the Y-axis direction is unchanged, it is a very preferable device for application to actuators such as positioning and ringing control of a magnetic head for a hard disk used in a very narrow gap. In addition, even when used as a sensor (for example, an acceleration sensor), the multi-stage structure increases the capacitance and increases the generated charge, so that the level of the electric signal generated by the sensor increases, There is an advantage that the processing in the signal processing circuit connected to the subsequent stage becomes easy.
In the above-described piezoelectric / electrostrictive elements 24a and 24b, a case of a so-called sandwich structure in which a piezoelectric / electrostrictive layer 26 is interposed between a pair of electrodes 28 and 30 has been shown. In addition, as shown in FIG. In addition, a pair of comb-shaped electrodes 28 and 30 may be formed on one main surface of the piezoelectric / electrostrictive layer 26 formed on at least the side surfaces of the thin plate portions 16a and 16b, as shown in FIG. Alternatively, a pair of comb-shaped electrodes 28 and 30 may be embedded in the piezoelectric / electrostrictive layer 26 formed at least on the side surfaces of the thin plate portions 16a and 16b.
The structure shown in FIG. 10 has the advantage that power consumption can be kept low, and the structure shown in FIG. 11 is a structure that can effectively use the reverse piezoelectric effect in the electric field direction with large distortion and generated force. Therefore, it is advantageous for occurrence of a large displacement.
Specifically, the piezoelectric / electrostrictive elements 24 a and 24 b shown in FIG. 10 are formed by forming a pair of comb-shaped electrodes 28 and 30 on one main surface of the piezoelectric / electrostrictive layer 26, and one electrode 28. The other electrodes 30 are alternately opposed to each other with a gap 29 having a constant width. FIG. 10 shows an example in which the pair of electrodes 28 and 30 are formed on one main surface of the piezoelectric / electrostrictive layer 26. In addition, a pair of electrodes 28 and 30 are disposed between the thin plate portions 16a and 16b and the piezoelectric / electrostrictive layer 26. The electrodes 28 and 30 may be formed, or a pair of comb-shaped electrodes 28 and 30 between one principal surface of the piezoelectric / electrostrictive layer 26 and the thin plate portions 16a and 16b and the piezoelectric / electrostrictive layer 26, respectively. 30 may be formed.
On the other hand, in the piezoelectric / electrostrictive elements 24a and 24b shown in FIG. 11, a pair of comb-shaped electrodes 28 and 30 are formed so as to be embedded in the piezoelectric / electrostrictive layer 26, and one electrode 28 and the other electrode are formed. 30 have a structure in which the gaps 29 are alternately opposed to each other with a gap 29 having a constant width.
Such piezoelectric / electrostrictive elements 24a and 24b as shown in FIGS. 10 and 11 can also be suitably used for the piezoelectric / electrostrictive device 10A according to the first embodiment. When using a pair of comb-shaped electrodes 28 and 30 like the piezoelectric / electrostrictive elements 24a and 24b shown in FIGS. 10 and 11, by reducing the pitch D of the comb teeth of each electrode 28 and 30, It is possible to increase the displacement of the piezoelectric / electrostrictive elements 24a and 24b.
Here, the operation of the piezoelectric / electrostrictive device 10A according to the first embodiment will be described. First, for example, when the two piezoelectric / electrostrictive elements 24a and 24b are in a natural state, that is, when the piezoelectric / electrostrictive elements 24a and 24b are not performing a displacement operation, as shown in FIG. The long axis 10A (long axis of the fixed portion) m and the central axis n of the movable portion 20 substantially coincide with each other.
From this state, for example, as shown in the waveform diagram of FIG. 13A, a sine wave Wa having a predetermined bias potential Vb is applied to a pair of electrodes 28 and 30 in one piezoelectric / electrostrictive element 24a, and as shown in FIG. 13B. Then, a sine wave Wb having a phase substantially different from that of the sine wave Wa is applied to the pair of electrodes 28 and 30 in the other piezoelectric / electrostrictive element 24b.
At a stage where, for example, a maximum voltage is applied to the pair of electrodes 28 and 30 in one piezoelectric / electrostrictive element 24a, the piezoelectric / electrostrictive layer 26 in one piezoelectric / electrostrictive element 24a Shrinks and displaces in the main surface direction. As a result, for example, as shown in FIG. 14, a stress is generated in the direction of bending the thin plate portion 16a in the right direction, for example, as indicated by an arrow A, as shown in FIG. The portion 16a bends in the right direction. At this time, since no voltage is applied to the pair of electrodes 28 and 30 in the other piezoelectric / electrostrictive element 24b, the other thin plate portion 16b is one thin plate portion. Following the bending of 16a, it bends to the right. As a result, the movable portion 20 is displaced, for example, in the right direction with respect to the long axis m of the piezoelectric / electrostrictive device 10A. The amount of displacement changes in accordance with the maximum value of the voltage applied to each piezoelectric / electrostrictive element 24a and 24b. For example, the amount of displacement increases as the maximum value increases.
In particular, when a piezoelectric / electrostrictive material having a high coercive electric field is applied as the constituent material of the piezoelectric / electrostrictive layer 26, as shown in the two-dot chain line waveforms of FIGS. 13A and 13B, the minimum level is obtained. The bias potential may be adjusted so that becomes a slightly negative level. In this case, by driving the piezoelectric / electrostrictive element (for example, the other piezoelectric / electrostrictive element 24b) to which the negative level is applied, for example, the same direction as the bending direction of the one thin plate portion 16a on the other thin plate portion 16b. Thus, the amount of displacement of the movable portion 20 can be increased. That is, by using a waveform as shown by a two-dot chain line in FIGS. 13A and 13B, the piezoelectric / electrostrictive element 24b or 24a to which a negative level is applied is the main component of the displacement operation. A function of supporting the electrostrictive element 24a or 24b can be provided.
In the example of the piezoelectric / electrostrictive device 10Af shown in FIG. 8, the voltage (see sine wave Wa) shown in FIG. 13A is applied to, for example, the piezoelectric / electrostrictive element 24a1 and the piezoelectric / electrostrictive element 24b2 arranged on the diagonal line. The voltage shown in FIG. 13B (see sine wave Wb) is applied to the other piezoelectric / electrostrictive element 24a2 and the piezoelectric / electrostrictive element 24b1.
As described above, in the piezoelectric / electrostrictive device 10A according to the first embodiment, a minute displacement of the piezoelectric / electrostrictive elements 24a and 24b is amplified to a large displacement operation using the bending of the thin plate portions 16a and 16b. Thus, since it is transmitted to the movable part 20, the movable part 20 can be largely displaced with respect to the major axis m of the piezoelectric / electrostrictive device 10A.
In particular, in the first embodiment, the movable portion 20 is provided with end faces 36a and 36b facing each other. In this case, a gap 38 is formed between the end faces 36a and 36b facing each other, or a member 40 that is lighter than the constituent members of the movable section 20 is interposed between the end faces 36a and 36b facing each other. It is possible to effectively reduce the weight, and it is possible to increase the resonance frequency without reducing the amount of displacement of the movable portion 20.
Here, the frequency indicates the frequency of the voltage waveform when the voltage applied to the pair of electrodes 28 and 30 is alternately switched and the movable part 20 is displaced left and right, and the resonance frequency is a predetermined sine. The frequency at which the displacement amplitude of the movable part 20 becomes maximum when the wave voltage is applied is shown.
In the piezoelectric / electrostrictive device 10A according to the first embodiment, the pair of thin plate portions 16a and 16b is made of metal, and the other movable portion 20 and the fixed portion 22 are made of ceramic. Because all parts need not be made of a fragile and relatively heavy piezoelectric / electrostrictive material, it has high mechanical strength, excellent handling, impact resistance, and moisture resistance. This has the advantage that it is less susceptible to harmful vibrations (for example, residual vibrations and noise vibrations during high-speed operation).
Further, in the first embodiment, when the gap 38 is formed between the opposing end faces 36a and 36b, a part 20A of the movable portion 20 including one end face 36a and a movable including the other end face 36b. Another part 20B of the part 20 is easily bent and is strong against deformation. Therefore, the handling property of the piezoelectric / electrostrictive device 10A is excellent.
Moreover, the surface area of the movable part 20 or the fixed part 22 is increased due to the presence of the end faces 36a and 36b facing each other. Therefore, as shown in FIG. 1, in the case of the movable part 20 having the end faces 36a and 36b facing each other, when other parts are attached to the movable part 20, the attachment area can be increased. Attachment property can be improved. Here, considering the case where the component is fixed by, for example, an adhesive or the like, the adhesive spreads to the end surfaces 36a and 36b in addition to one main surface (component mounting surface) of the movable portion 20, so that the adhesive is applied. It is possible to solve the shortage and the like, and it is possible to securely fix the components.
As an example of this, FIG. 15 shows another piezoelectric / electrostrictive device according to the present embodiment (the other piezoelectric / electrostrictive device 10A1) on the movable portion 20 of the piezoelectric / electrostrictive device according to the present embodiment. The case where the piezoelectric / electrostrictive device 10A2) is fixed is shown.
One piezoelectric / electrostrictive device 10 </ b> A <b> 1 has a fixing portion 22 fixed to the surface of the substrate 122 with an adhesive 120. The fixed portion 22 of the other piezoelectric / electrostrictive device 10A2 is fixed to the movable portion 20 of the one piezoelectric / electrostrictive device 10A1 via an adhesive 124. That is, the two piezoelectric / electrostrictive devices 10A1 and 10A2 are arranged in series. Note that a lightweight member 126 different from the movable portion 20 is interposed between the end faces 36a and 36b of the movable portion 20 facing each other in the other piezoelectric / electrostrictive device 10A2.
In this case, the adhesive 124 for fixing the other piezoelectric / electrostrictive device 10A2 is spread between the end faces 36a and 36b of the movable portion 20 in the one piezoelectric / electrostrictive device 10A1. The piezoelectric / electrostrictive device 10A2 is firmly fixed to the one piezoelectric / electrostrictive device 10A1. Further, if the piezoelectric / electrostrictive device 10A2 is bonded in this way, a lightweight member (in this example, an adhesive 124) different from the movable portion 20 can be interposed between the end faces 36a and 36b simultaneously with the bonding, There is an advantage that the manufacturing process can be simplified.
On the other hand, as shown in FIG. 3, in the case of the fixed portion 22 having the end surfaces 36a and 36b facing each other, in addition to the effect obtained when the movable portion 20 has the end surfaces 36a and 36b facing each other, the second portion. The piezoelectric / electrostrictive device 10Ab according to the modified example can be firmly fixed to a predetermined fixing portion, and the reliability can be improved.
Further, in the first embodiment, a portion (substantially driving portion 18) where the pair of electrodes 28 and 30 overlap with the piezoelectric / electrostrictive layer 26 interposed therebetween is changed from a part of the fixing portion 22 to the thin plate portion 16 a. And 16b are continuously formed. When the substantial driving portion 18 is formed over a part of the movable portion 20, the displacement operation of the movable portion 20 is limited by the substantial driving portion 18 and a large displacement may not be obtained. In one embodiment, since the substantial drive portion 18 is formed so as not to be applied to the movable portion 20, the disadvantage that the displacement operation of the movable portion 20 is limited is avoided, and the displacement amount of the movable portion 20 is reduced. Can be bigger.
On the contrary, when the piezoelectric / electrostrictive elements 24a and 24b are formed on a part of the movable part 20, the substantial driving part 18 is positioned from a part of the movable part 20 to a part of the thin plate parts 16a and 16b. It is preferable to form. This is because, when the substantial driving portion 18 is formed over a part of the fixed portion 22, the displacement operation of the movable portion 20 is limited as described above.
Next, a preferred configuration example of the piezoelectric / electrostrictive device 10A according to the first embodiment will be described.
First, in order to ensure the displacement operation of the movable portion 20, the distance g applied to the fixed portion 22 or the movable portion 20 by the substantial drive portion 18 of the piezoelectric / electrostrictive elements 24a and 24b is set to be equal to that of the thin plate portions 16a and 16b. It is preferable to set it to 1/2 or more of thickness d.
The ratio a / b between the distance between the inner walls of the thin plate portions 16a and 16b (distance in the X-axis direction) a and the width (distance in the Y-axis direction) b of the thin plate portions 16a and 16b is 0.5 to 20. Configure as follows. The ratio a / b is preferably 1 to 15, and more preferably 1 to 10. The specified value of the ratio a / b is a specification based on the discovery that the displacement amount of the movable part 20 is increased and the displacement in the XZ plane can be obtained predominantly.
On the other hand, the ratio e / a of the length (distance in the Z-axis direction) e of the thin plate portions 16a and 16b and the distance a between the inner walls of the thin plate portions 16a and 16b is preferably 0.5 to 10, and Preferably it is 0.5-5.
Furthermore, it is preferable to fill the hole 12 with a gel material, for example, silicon gel. Normally, the displacement operation of the movable portion 20 is limited by the presence of the filler, but in the first embodiment, the weight reduction and the movement due to the formation of the end surfaces 36a and 36b on the movable portion 20 are limited. Since the displacement amount of the portion 20 is increased, the restriction of the displacement operation of the movable portion 20 by the filler is canceled out, and the effect due to the presence of the filler, that is, high resonance frequency and securing of rigidity are ensured. Can be realized.
The length (distance in the Z-axis direction) f of the movable part 20 is preferably short. This is because shortening can reduce the weight and increase the resonance frequency. However, in order to ensure the rigidity of the movable portion 20 in the X-axis direction and ensure the displacement, the ratio f / d with the thickness d of the thin plate portions 16a and 16b is 2 or more, preferably 5 or more. It is desirable to do.
Note that the actual dimensions of each part are the bonding area for mounting the component to the movable part 20, the bonding area for mounting the fixed part 22 to another member, the bonding area for mounting the electrode terminal, etc. It is determined in consideration of the strength, durability, required displacement amount, resonance frequency, drive voltage, and the like of the entire electrostrictive device 10A.
Specifically, for example, the distance a between the inner walls of the thin plate portions 16a and 16b is preferably 100 μm to 2000 μm, and more preferably 200 μm to 1600 μm. The width b of the thin plate portions 16a and 16b is preferably 50 μm to 2000 μm, more preferably 100 μm to 500 μm. The thickness d of the thin plate portions 16a and 16b is set to b> d in relation to the width b of the thin plate portions 16a and 16b so as to effectively suppress the turning displacement that is a displacement component in the Y-axis direction, and 2 micrometers-100 micrometers are preferable, More preferably, they are 10 micrometers-80 micrometers.
The length e of the thin plate portions 16a and 16b is preferably 200 μm to 3000 μm, more preferably 300 μm to 2000 μm. The length f of the movable part 20 is preferably 50 μm to 2000 μm, more preferably 100 μm to 1000 μm.
By adopting such a configuration, the displacement in the Y-axis direction does not exceed 10% with respect to the displacement in the X-axis direction. It is possible and exhibits a very excellent effect that the displacement component in the Y-axis direction can be suppressed to 5% or less. That is, the movable portion 20 is displaced substantially in one axial direction, that is, the X-axis direction, and is excellent in high-speed response and can obtain a large displacement at a relatively low voltage.
Further, in this piezoelectric / electrostrictive device 10A, the shape of the device is not a conventional plate shape (a shape having a small thickness in the direction orthogonal to the displacement direction), and the movable portion 20 and the fixed portion 22 are substantially rectangular parallelepiped shapes. Since the pair of thin plate portions 16a and 16b are provided so that the side surfaces of the movable portion 20 and the fixed portion 22 are continuous, the rigidity in the Y-axis direction of the piezoelectric / electrostrictive device 10A is selectively increased. can do.
That is, in this piezoelectric / electrostrictive device 10A, only the operation of the movable part 20 in the plane (in the XZ plane) can be selectively generated, and the operation in the YZ plane of the movable part 20 (the operation in the so-called turning direction). ) Can be suppressed.
Next, each component of the piezoelectric / electrostrictive device 10A according to the first embodiment will be described.
As described above, the movable portion 20 is a portion that operates based on the driving amount of the thin plate portions 16a and 16b, and various members are attached according to the purpose of use of the piezoelectric / electrostrictive device 10A. For example, if the piezoelectric / electrostrictive device 10A is used as a displacement element, an optical shutter shielding plate or the like is attached. In particular, if it is used for a magnetic head positioning or ringing suppression mechanism of a hard disk drive, the magnetic Members that require positioning, such as a head, a slider having a magnetic head, and a suspension having a slider, are attached.
As described above, the fixed portion 22 is a portion that supports the thin plate portions 16a and 16b and the movable portion 20, and is attached to a VCM (voice coil motor) when used for positioning the magnetic head of the hard disk drive, for example. The entire piezoelectric / electrostrictive device 10A is fixed by supporting and fixing the fixing portion 22 to a carriage arm, a fixing plate or a suspension attached to the carriage arm, and the like. In addition, as shown in FIG. 1, there are cases where terminals 32 and 34 and other members for driving the piezoelectric / electrostrictive elements 24 a and 24 b are disposed on the fixing portion 22.
The material constituting the movable portion 20 and the fixed portion 22 is not particularly limited as long as it has rigidity, but ceramics to which a ceramic green sheet laminating method described later can be applied can be suitably used. Specifically, in addition to zirconia such as stabilized zirconia and partially stabilized zirconia, materials mainly composed of alumina, magnesia, silicon nitride, aluminum nitride, titanium oxide, etc., and materials mainly composed of a mixture thereof. In view of high mechanical strength and toughness, zirconia, in particular, a material mainly composed of stabilized zirconia and a material mainly composed of partially stabilized zirconia are preferable. In addition, the metal material is not limited as long as it has rigidity, but examples include stainless steel, nickel, brass, white bronze, bronze and the like.
In the stabilized zirconia and the partially stabilized zirconia, those stabilized and partially stabilized as follows are preferable. That is, as a compound that stabilizes and partially stabilizes zirconia, there are yttrium oxide, ytterbium oxide, cerium oxide, calcium oxide, and magnesium oxide. By adding and containing at least one of these compounds, zirconia is partially However, the stabilization of the target zirconia is possible not only by adding one kind of compound but also by adding these compounds in combination.
The amount of each compound added is 1 to 30 mol%, preferably 1.5 to 10 mol% in the case of yttrium oxide or ytterbium oxide, and 6 to 6 in the case of cerium oxide. 50 mol%, preferably 8 to 20 mol%, and in the case of calcium oxide or magnesium oxide, it is desirable that the content be 5 to 40 mol%, preferably 5 to 20 mol%. It is preferable to use it as a stabilizer, and in that case, it is desirable that the content be 1.5 to 10 mol%, more preferably 2 to 4 mol%. Further, it is possible to add alumina, silica, transition metal oxide or the like as an additive such as a sintering aid in the range of 0.05 to 20 wt%, but a method for forming the piezoelectric / electrostrictive elements 24a and 24b. In the case of adopting the integration by firing by the film forming method, it is also preferable to add alumina, magnesia, transition metal oxide or the like as an additive.
In order to obtain a mechanical strength and a stable crystal phase, the average crystal particle diameter of zirconia is desirably 0.05 to 3 μm, preferably 0.05 to 1 μm. Further, as described above, for the thin plate portions 16a and 16b, ceramics similar to the movable portion 20 and the fixed portion 22 can be used, but preferably, the thin plate portions 16a and 16b are configured using substantially the same material. This is advantageous in reducing the reliability of the bonded portion, the strength of the piezoelectric / electrostrictive device 10A, and the complexity of manufacturing.
As described above, the thin plate portions 16a and 16b are portions that are driven by the displacement of the piezoelectric / electrostrictive elements 24a and 24b. The thin plate portions 16 a and 16 b are flexible thin plate-like members, and amplify the expansion / contraction displacement of the piezoelectric / electrostrictive elements 24 a and 24 b disposed on the surface as bending displacements and transmit them to the movable portion 20. It has the function to do. Therefore, the shape and material of the thin plate portions 16a and 16b need only be flexible and have a mechanical strength that is not damaged by bending deformation, and the responsiveness and operability of the movable portion 20 are considered. Can be selected as appropriate.
The thickness d of the thin plate portions 16a and 16b is preferably about 2 μm to 100 μm, and the combined thickness of the thin plate portions 16a and 16b and the piezoelectric / electrostrictive elements 24a and 24b is preferably 7 μm to 500 μm. The thickness of the electrodes 28 and 30 is preferably 0.1 to 50 μm, and the thickness of the piezoelectric / electrostrictive layer 26 is preferably 3 to 300 μm. The width b of the thin plate portions 16a and 16b is preferably 50 μm to 2000 μm.
On the other hand, as long as the shape and material of the thin plate portions 16a and 16b are flexible and have a mechanical strength that is not damaged by bending deformation, a metal is preferably employed. In this case, as described above, a metal material having flexibility and capable of bending deformation, specifically, a metal material having a Young's modulus of 100 GPa or more may be used.
Preferably, as the iron-based material, austenitic stainless steel such as SUS301, SUS304, AISI653, SUH660, ferritic stainless steel such as SUS430, 434, martensitic stainless steel such as SUS410, SUS630, semi-material such as SUS631, AISI632, and the like. It is desirable to use austenitic stainless steel, maraging stainless steel, and various spring steel materials. Non-ferrous materials may be composed of superelastic titanium alloys including titanium-nickel alloys, brass, white copper, aluminum, tungsten, molybdenum, beryllium copper, phosphor bronze, nickel, nickel iron alloys, titanium, and the like. desirable.
As the thin plate portions 16a and 16b, like the movable portion 20 and the fixed portion 22, zirconia is suitable when using ceramics. Among them, the material mainly composed of stabilized zirconia and the material mainly composed of partially stabilized zirconia have high mechanical strength and high toughness even if they are thin, and the piezoelectric / electrostrictive layer 26 and the electrode material Is most preferably used because of its low reactivity.
The piezoelectric / electrostrictive elements 24a and 24b have at least a piezoelectric / electrostrictive layer 26 and a pair of electrodes 28 and 30 for applying an electric field to the piezoelectric / electrostrictive layer 26, such as a unimorph type and a bimorph type. However, since the unimorph type combined with the thin plate portions 16a and 16b is more stable in the amount of generated displacement and is more advantageous for weight reduction, such a piezoelectric / electrostrictive element can be used. Suitable for the electrostrictive device 10A.
For example, as shown in FIG. 1, a piezoelectric / electrostrictive element or the like in which one electrode 28, piezoelectric / electrostrictive layer 26 and the other electrode 30 are laminated in layers can be suitably used. As shown in FIG. In this case, the positional deviation of the films (electrode films) constituting the electrodes 28 and 30, that is, the positional deviation in the plane direction on the vertical projection plane of the electrodes 28 every other layer is 50 μm or less. The same applies to the electrode 30.
The piezoelectric / electrostrictive elements 24a and 24b are preferably formed on the outer surface side of the piezoelectric / electrostrictive device 10A as shown in FIG. 1 in that the thin plate portions 16a and 16b can be driven more greatly. Depending on the form of use, it may be formed on the inner surface side of the piezoelectric / electrostrictive device 10A, that is, on the inner wall surface of the hole 12, or on both the outer surface side and inner surface side of the piezoelectric / electrostrictive device 10A. Also good.
Piezoelectric ceramics are preferably used for the piezoelectric / electrostrictive layer 26, but electrostrictive ceramics, ferroelectric ceramics, or antiferroelectric ceramics can also be used. However, when this piezoelectric / electrostrictive device 10A is used for positioning of a magnetic head of a hard disk drive or the like, since the linearity between the displacement of the movable portion 20 and the drive voltage or output voltage is important, a material having a small strain history. It is preferable to use a material having a coercive electric field of 10 kV / mm or less.
Specific materials include lead zirconate, lead titanate, lead magnesium niobate, lead nickel niobate, lead zinc niobate, lead manganese niobate, lead antimony stannate, lead manganese tungstate, lead cobalt niobate, Examples thereof include ceramics containing barium titanate, sodium bismuth titanate, potassium sodium niobate, strontium bismuth tantalate, etc. alone or as a mixture.
In particular, when the thin plate portions 16a and 16b are made of ceramics and the piezoelectric / electrostrictive layer 26 is integrally fired, the reactivity with the thin plate portions 16a and 16b (ceramics) is high. A material mainly composed of lead zirconate, lead titanate and lead magnesium niobate or a material mainly composed of sodium bismuth titanate is preferably used in that a small and stable composition can be obtained.
In addition, the materials include oxidation of lanthanum, calcium, strontium, molybdenum, tungsten, barium, niobium, zinc, nickel, manganese, cerium, cadmium, chromium, cobalt, antimony, iron, yttrium, tantalum, lithium, bismuth, tin, etc. Or a ceramic containing at least one component that finally becomes an oxide or a mixture thereof may be used.
For example, by incorporating lanthanum or strontium into the main components of lead zirconate, lead titanate, and lead magnesium niobate, there are cases where advantages such as adjustment of coercive electric field and piezoelectric characteristics can be obtained.
Note that it is desirable to avoid the addition of a material that is easily vitrified, such as silica. This is because a material such as silica easily reacts with the piezoelectric / electrostrictive material during the heat treatment of the piezoelectric / electrostrictive layer, changes its composition, and deteriorates the piezoelectric characteristics.
On the other hand, the pair of electrodes 28 and 30 of the piezoelectric / electrostrictive elements 24a and 24b is preferably made of a metal that is solid at room temperature and has excellent conductivity. For example, aluminum, titanium, chromium, iron, cobalt , Nickel, copper, zinc, niobium, molybdenum, ruthenium, palladium, rhodium, silver, tin, tantalum, tungsten, iridium, platinum, gold, lead, etc. A cermet material in which ceramics of the same material as the electrostrictive layer 26 or a different material is dispersed may be used.
The material selection of the electrodes 28 and 30 in the piezoelectric / electrostrictive elements 24 a and 24 b is determined depending on the method of forming the piezoelectric / electrostrictive layer 26. For example, when one electrode 28 is formed on the thin plate portions 16 a and 16 b and then the piezoelectric / electrostrictive layer 26 is formed on the one electrode 28 by firing, the one electrode 28 has a piezoelectric / electrostrictive layer. Although it is necessary to use a refractory metal such as platinum, palladium, platinum-palladium alloy, silver-palladium alloy, etc. that does not change even at the firing temperature of 26, the piezoelectric / electrostrictive layer 26 is formed after the piezoelectric / electrostrictive layer 26 is formed. Since the other electrode 30 formed on the outermost layer formed on the layer 26 can form an electrode at a low temperature, a low-melting-point metal such as aluminum, gold, or silver can be used.
When the laminated piezoelectric / electrostrictive element 24 is bonded to the thin plate portions 16a and 16b with the adhesive 202, the piezoelectric / electrostrictive layer 26 and the electrodes 28 and 30 (electrode film) are laminated in multiple layers. Preferably, the electrodes 28 and 30 are made of a high melting point metal such as platinum, palladium, or an alloy thereof. The electrodes 28 and 30 are preferably cermets that are a mixture of a refractory metal and a piezoelectric / electrostrictive material or other ceramics.
Further, since the thickness of the electrodes 28 and 30 is a factor that lowers the displacement of the piezoelectric / electrostrictive elements 24a and 24b, the electrode formed after the piezoelectric / electrostrictive layer 26 is fired is particularly dense after firing. It is preferable to use a material such as an organic metal paste that can provide a thinner film, such as a gold resinate paste, a platinum resinate paste, or a silver resinate paste.
Next, several manufacturing methods of the piezoelectric / electrostrictive device 10A according to the first embodiment will be described with reference to FIGS.
In the piezoelectric / electrostrictive device 10A according to the first embodiment, the thin plate portions 16a and 16b are made of metal, and the constituent materials of the movable portion 20 and the fixed portion 22 are ceramics. Therefore, as the components of the piezoelectric / electrostrictive device 10A, the fixed portion 22 and the movable portion 20 except for the thin plate portions 16a and 16b and the piezoelectric / electrostrictive elements 24a and 24b are manufactured using a ceramic green sheet lamination method. On the other hand, it is preferable to manufacture each terminal 32 and 34 including the piezoelectric / electrostrictive elements 24a and 24b by using a film forming method such as a thin film or a thick film.
The thin plate portions 16a and 16b are preferably fixed to the side surfaces of the movable portion 20 and the fixed portion 22 by the adhesive 200, and the piezoelectric / electrostrictive elements 24a and 24b are fixed to the thin plate portions 16a and 16b. Adhesion by is preferred.
According to the ceramic green sheet laminating method capable of integrally forming the movable portion 20 and the fixed portion 22 of the piezoelectric / electrostrictive device 10A, since the state change of the joint portion of each member over time hardly occurs. This is a method that is highly reliable at the joining site and is advantageous for securing rigidity.
In the piezoelectric / electrostrictive device 10A according to the first embodiment, the boundary portions between the thin plate portions 16a and 16b and the fixed portion 22 and the boundary portions between the thin plate portions 16a and 16b and the movable portion 20 are fulcrums for the expression of displacement. Therefore, the reliability of these boundary portions is an important point that affects the characteristics of the piezoelectric / electrostrictive device 10A.
Moreover, since the manufacturing method shown below is excellent in productivity and moldability, a piezoelectric / electrostrictive device having a predetermined shape can be obtained in a short time and with good reproducibility.
Hereinafter, the first manufacturing method of the piezoelectric / electrostrictive device 10A according to the first embodiment will be specifically described. Here, definition is made. The laminate obtained by laminating the ceramic green sheets is defined as a ceramic green laminate 158 (see, for example, FIG. 16B), and the ceramic green laminate 158 is fired and integrated to form a ceramic laminate 160 (see, for example, FIG. 16). 17A), a laminate of the ceramic laminate 160 and the metal plate is defined as a hybrid laminate 162 (see FIG. 18), and unnecessary portions are cut out from the hybrid laminate 162 to move the movable portion 20, A substrate in which the thin plate portions 16a and 16b and the fixing portion 22 are integrated is defined as a base body 14D (see FIG. 19).
Further, in this first manufacturing method, the hybrid laminate 162 is finally cut into chips, and a large number of piezoelectric / electrostrictive devices 10A are taken. For simplicity of explanation, A description will be given mainly of a single piece of the piezoelectric / electrostrictive device 10A.
First, a binder, a solvent, a dispersant, a plasticizer, etc. are added to and mixed with a ceramic powder such as zirconia to prepare a slurry, and after defoaming, a predetermined method is used by a reverse roll coater method, a doctor blade method, or the like. A ceramic green sheet having a thickness is prepared.
Next, the ceramic green sheet is processed into various shapes as shown in FIG. 16A by a method such as punching using a die or laser processing, specifically, a plurality of ceramic green sheets for forming a substrate, specifically, A plurality of (for example, four) ceramic green sheets 50A to 50D in which a window 54 for forming the hole 12 later is formed, and end faces 36a and 36b facing the window 54 for forming the hole 12 later. A ceramic green sheet 102 in which a window portion 100 for forming the movable portion 20 having the above is continuously formed is prepared.
Thereafter, as shown in FIG. 16B, ceramic green sheets 50 </ b> A to 50 </ b> D and 102 are laminated and pressure-bonded to obtain a ceramic green laminate 158. In this lamination, the ceramic green sheets 102 are laminated in the center. Thereafter, the ceramic green laminate 158 is fired to obtain a ceramic laminate 160 as shown in FIG. 17A. At this time, the ceramic laminate 160 is formed with a hole 130 formed by the windows 54 and 100.
Next, as shown in FIG. 17B, the piezoelectric / electrostrictive elements 24a and 24b configured separately are bonded to the surfaces of the metal plates 152A and 152B, which are thin plate portions, with an epoxy adhesive 202, respectively.
Next, the metal plates 152A and 152B are bonded to the ceramic laminate 160 with the epoxy adhesive 200 so that the ceramic laminate 160 is sandwiched between the metal plates 152A and 152B and the hole 130 is closed. The hybrid laminate 162 (see FIG. 18).
Next, as shown in FIG. 18, the hybrid laminate 162 in which the piezoelectric / electrostrictive elements 24 a and 24 b are formed is cut along the cutting lines C 1, C 2, and C 5, so that the hybrid laminate 162 side is cut. Cut out the tip and tip. By this cutting, as shown in FIG. 19, the piezoelectric / electrostrictive elements 24a and 24b are formed in the thin plate portions 16a and 16b made of a metal plate in the base 14D, and the end faces 36a and 36b facing each other are formed. The piezoelectric / electrostrictive device 10 </ b> A according to the first embodiment in which the movable portion 20 is formed is obtained.
On the other hand, in the second manufacturing method, first, as shown in FIG. 20A, a plurality of (for example, four) ceramic green sheets 50A to 50D in which window portions 54 for forming holes 12 are formed at least later, A ceramic green sheet 102 in which a window portion 54 for forming the hole portion 12 and a window portion 100 for forming the movable portion 20 having end faces 36a and 36b facing each other is continuously formed is prepared.
Thereafter, as shown in FIG. 20B, ceramic green sheets 50 </ b> A to 50 </ b> D and 102 are laminated and pressure-bonded to obtain a ceramic green laminate 158. Thereafter, the ceramic green laminate 158 is fired to obtain a ceramic laminate 160 as shown in FIG. 21A. At this time, the ceramic laminate 160 is formed with a hole 130 formed by the windows 54 and 100.
Next, as shown in FIG. 21B, the ceramic laminate 160 is sandwiched between the metal plates 152A and 152B, and the holes 130 are closed so that the metal plates 152A and 152B are bonded to the ceramic laminate 160 with an epoxy system. The hybrid laminate 162 is obtained by bonding with the adhesive 200. At this time, as shown in FIG. 21A, a hole is formed as necessary so that a sufficient bonding pressure is applied when the piezoelectric / electrostrictive elements 24a and 24b are bonded to the surfaces of the bonded metal plates 152A and 152B. The portion 130 is filled with the filler 164.
Since the filler 164 needs to be finally removed, the filler 164 is preferably dissolved in a solvent or the like and is preferably a hard material, and examples thereof include organic resins, waxes, and waxes. In addition, a material obtained by mixing ceramic powder as a filler with an organic resin such as acrylic may be employed.
Next, as shown in FIG. 21B, piezoelectric / electrostrictive elements 24 a and 24 b formed separately are bonded to the surfaces of the metal plates 152 A and 152 B in the hybrid laminate 162 with an epoxy-based adhesive 202. Separate piezoelectric / electrostrictive elements 24a and 24b can be formed by, for example, a ceramic green sheet lamination method or a printing multilayer method.
Next, as shown in FIG. 22, the hybrid laminate 162 in which the piezoelectric / electrostrictive elements 24 a and 24 b are formed is cut along the cutting lines C <b> 1, C <b> 2, C <b> 5, thereby Cut out the tip and tip. By this cutting, as shown in FIG. 23, the piezoelectric / electrostrictive elements 24a and 24b are formed on the thin plate portions 16a and 16b made of a metal plate in the base 14D, and the end faces 36a and 36b facing each other are formed. The piezoelectric / electrostrictive device 10 </ b> A according to the first embodiment in which the movable portion 20 is formed is obtained.
Further, when the base portion is made entirely of metal, for example, a portion corresponding to the ceramic laminate 160 in FIG. 17A is formed by casting, and the bulk-like member is ground, wire electric discharge machining, die punching, chemical etching The above method may be used, or a thin plate metal may be laminated and formed by a cladding method.
Next, a piezoelectric / electrostrictive device 10B according to a second embodiment will be described with reference to FIGS.
As shown in FIG. 24, the piezoelectric / electrostrictive device 10B according to the second embodiment includes a pair of opposed thin plate portions 16a and 16b and a fixing portion 22 that supports the thin plate portions 16a and 16b. The laminated piezoelectric / electrostrictive element 24 is arranged on one thin plate portion 16a of the pair of thin plate portions 16a and 16b. Since the multilayer piezoelectric / electrostrictive element 24 has a complicated structure, it is shown in a simplified manner in FIGS. 24 and 25, and a detailed enlarged view thereof is shown in FIGS.
Between each rear end part of a pair of thin plate part 16a and 16b, the fixing | fixed part 22 is fixed by the adhesive agent 200, for example, and each front-end | tip part of a pair of thin plate part 16a and 16b is an open end.
For example, as shown in FIG. 25, the above-mentioned movable portion 20 or various members and parts are fixed between the tip portions of the pair of thin plate portions 16 a and 16 b through an adhesive 200, for example. In the example of FIG. 25, an example is shown in which the movable portion 20 made of the same member as the fixed portion 22 is fixed via an adhesive 200 between the tip portions of the pair of thin plate portions 16 a and 16 b.
The pair of thin plate portions 16a and 16b is made of metal, and the fixed portion 22 and the movable portion 20 are made of ceramic or metal. In particular, in the example of FIGS. 24 and 25, the thickness of one thin plate portion 16a in which the laminated piezoelectric / electrostrictive element 24 is formed out of the pair of thin plate portions 16a and 16b is larger than the thickness of the other thin plate portion 16b. It is considered large.
The laminated piezoelectric / electrostrictive element 24 is attached to the thin plate portion 16a with an adhesive 202 such as organic resin, glass, brazing, soldering, eutectic bonding or the like. That is, the laminated piezoelectric / electrostrictive element 24 is fixed to the metal thin plate portion 16a via the adhesive 202, whereby the actuator portion 204 that is the driving source of the piezoelectric / electrostrictive device 10B is configured. become.
In the piezoelectric / electrostrictive device 10B, the distal end portion (the portion to which the movable portion 20 is attached) of the thin plate portion 16a (16a and 16b in the example of FIG. 25) is displaced by driving the actuator portion 204. Or the displacement of the front-end | tip part in the thin-plate part 16a is electrically detected through the actuator part (When using as a sensor, it is a drained-ducer part) 204. FIG. In this case, it will be used as a sensor.
For example, as shown in FIG. 26, the multilayer piezoelectric / electrostrictive element 24 has a piezoelectric / electrostrictive layer 26 and a pair of electrodes 28 and 30 each having a multilayer structure, and one electrode 28 and the other electrode 30 are alternately arranged. A portion where the one electrode 28 and the other electrode 30 are stacked and overlapped with the piezoelectric / electrostrictive layer 26 therebetween is formed in a multi-stage structure.
In FIG. 26, the piezoelectric / electrostrictive layer 26 and the pair of electrodes 28 and 30 each have a multilayer structure, and one electrode 28 and the other electrode 30 are alternately stacked so as to have a substantially comb-like cross section. The portion where the electrode 28 and the other electrode 30 overlap with the piezoelectric / electrostrictive layer 26 in between has a multi-stage configuration.
Specifically, the laminated piezoelectric / electrostrictive element 24 has a substantially rectangular parallelepiped shape, and includes a plurality of piezoelectric / electrostrictive layers 26 and electrode films 28 and 30. Then, the electrode films 28 and 30 in contact with the upper and lower surfaces of each piezoelectric / electrostrictive layer 26 are led out alternately to the opposite end faces 208 and 209, respectively, and each electrode film 28 led out to the opposite opposite end faces 208 and 209 is obtained. And 30c are electrically connected to terminal portions 28b and 30b provided on the surface of the outermost piezoelectric / electrostrictive layer 26 and spaced apart by a predetermined distance Dk. It is connected.
The predetermined distance Dk between the terminal portions 28b and 30b is preferably 20 μm or more. Further, the material of the electrode films 28 and 30 in contact with the upper and lower surfaces of the piezoelectric / electrostrictive layer may be different from the material of the end face electrodes 28c and 30c. Further, at least one terminal portion (terminal portion 28b in the example of FIG. 26) and the end face electrode 28c corresponding to the terminal portion 28b are made of a thin film electrode film (outer surface electrode) that is thinner than the terminal portion 28b and the end face electrode 28c. ) Electrical connection may be made at 28d.
The surface electrode film 28d, the end face electrodes 28c and 30c, and the terminal portions 28b and 30b formed after the piezoelectric / electrostrictive layer 26 are fired are formed before or simultaneously fired with the piezoelectric / electrostrictive layer 26. It may be thinner than the electrode layers 28 and 30 to be formed and may have low heat resistance.
In FIG. 26, the piezoelectric / electrostrictive layer 26 has a five-layer structure, and one electrode 28 is formed in a comb shape so as to be positioned on the upper surface of the first layer, the upper surface of the third layer, and the upper surface of the fifth layer. In the example, the other electrode 30 is formed in a comb shape so as to be positioned on the upper surface of the second layer and the upper surface of the fourth layer.
Also, in FIG. 28, the piezoelectric / electrostrictive layer 26 has the same five-layer structure, and one electrode 28 has a comb-tooth shape so as to be positioned on the upper surface of the first layer, the upper surface of the third layer, and the upper surface of the fifth layer. In this example, the other electrode 30 is formed in a comb shape so as to be positioned on the lower surface of the first layer, the upper surface of the second layer, and the upper surface of the fourth layer.
In the case of these configurations, since the increase in the number of terminals can be suppressed by connecting one electrode 28 and the other electrode 30 to each other in common, the stacked piezoelectric / electrostrictive element 24 is used. The increase in size due to this can be suppressed.
By using the multilayer piezoelectric / electrostrictive element 24 in this way, the driving force of the actuator unit 204 is increased, thereby achieving a large displacement and increasing the rigidity of the piezoelectric / electrostrictive device 10B itself, thereby increasing the resonance. The frequency can be increased, and the speed of the displacement operation can be easily achieved.
If the number of stages is increased, the driving force of the actuator unit 204 can be increased, but the power consumption increases accordingly. Therefore, in the case of implementation, the number of stages may be appropriately determined according to the application and use state. Further, in the piezoelectric / electrostrictive device 10B according to the second embodiment, even if the driving force of the actuator unit 204 is increased by using the laminated piezoelectric / electrostrictive element 24, basically the thin plate portion 16a and Since the width of 16b (distance in the Y-axis direction) is not changed, it is a very preferable device for application to actuators for positioning, ringing control, etc. of a magnetic head for a hard disk used in a very narrow gap.
Here, with respect to the formation position of the multilayer piezoelectric / electrostrictive element 24 with respect to the thin plate portion 16a, the tip 208 of the multilayer body constituting the multilayer piezoelectric / electrostrictive element 24 does not include at least the fixing portion 22 in plan view. At the position (in the example of FIG. 25, the position included in the hole formed between the movable portion 20 and the fixed portion 22), the rear end 209 of the multilayer body constituting the multilayer piezoelectric / electrostrictive element 24 is The end portion 28a of the electrode 28 is a position including at least the fixing portion 22 in a plane, and the end portion 30a of the electrode 30 includes the fixing portion 22 in a plane. It is preferably formed at a position that is not present (in the example of FIG. 25, a position that is also included in a hole formed between the movable portion 20 and the fixed portion 22).
The voltage is applied to the pair of electrodes 28 and 30 through end portions of the electrodes 28 and 30 (hereinafter referred to as terminal portions 28b and 30b) formed on the fifth piezoelectric / electrostrictive layer 26. To be done. The terminal portions 28b and 30b are formed so as to be electrically insulated from each other.
The predetermined distance Dk between the terminal portions 28a and 30b is preferably 20 μm or more. Further, when the thickness of the terminal portions 28b and 30b is 1 μm to 30 μm, 50 μm or more is preferable. The terminal portions 28b and 30b may be made of the same material as the internal electrodes 28 and 30 or different materials. For example, in the case of simultaneous firing with the piezoelectric / electrostrictive layer 26, the same material may be used, and in different firing, different materials may be used.
The end face electrodes 28c and 30c are preferably electrically connected to each other by grinding or polishing the end faces after firing the internal electrodes 28 and 30 and the piezoelectric / electrostrictive layer 26. The material of the end face electrodes 28c and 30c may be the same as or different from the internal electrodes 28 and 30. For example, it is preferable to use platinum paste for the internal electrodes 28 and 30, gold resinate for the outer surface electrode 28 d, and gold paste for the end face electrodes 28 c and 30 c and the terminal portions 28 b and 30 b, but the first embodiment described above. The piezoelectric / electrostrictive device according to the present invention can have almost the same configuration.
In this case, the piezoelectric / electrostrictive device 10B can be fixed separately using a surface different from the surface on which the terminal portions 28b and 30b are arranged, and as a result, the piezoelectric / electrostrictive device 10B can be fixed. High reliability can be obtained for both fixing and electrical connection between the circuit and the terminal portions 28b and 30b. In this configuration, the terminal portions 28b and 30b are electrically connected to the circuit by a flexible printed circuit, a flexible flat cable, wire bonding, or the like.
Thus, in the piezoelectric / electrostrictive device 10B according to the second embodiment, the actuator unit 204 is fixed to the laminated piezoelectric / electrostrictive element 24 on the metal thin plate portion 16a via the adhesive 202. Therefore, the thin plate portion 16a (and 16b) can be greatly displaced without increasing the planar area of the multilayer piezoelectric / electrostrictive element 24, and the thin plate portion 16a (and Since 16b) is made of metal, it is excellent in strength and toughness and can cope with a sudden displacement operation.
In other words, in the second embodiment, it is possible to sufficiently cope with fluctuations in the use environment and severe use conditions, excellent impact resistance, extending the life of the piezoelectric / electrostrictive device 10B, and improving handling properties. In addition, the thin plate portions 16a and 16b can be largely displaced at a relatively low voltage, and the rigidity of the thin plate portions 16a (and 16b) is high, and the thickness of the actuator portion 204 is thick, so that the rigidity is high. Since it is high, the displacement operation of the thin plate portion 16a (and 16b) can be speeded up (high resonance frequency).
In general, for the actuator unit 204 that combines the thin plate portion 16a and the piezoelectric / electrostrictive element 24 that deforms and deforms, it is necessary to increase the rigidity of the actuator unit 204 in order to drive the actuator unit 204 at high speed, and a large displacement is obtained. Therefore, it is necessary to reduce the rigidity of the actuator unit 204.
However, in the piezoelectric / electrostrictive device 10B according to the second embodiment, the thin plate portions 16a and 16b constituting the actuator portion 204 are opposed to each other to form a pair of thin plate portions 16a and 16b, and the pair of thin plate portions 16a. And 16b are fixed with an adhesive 200 between the respective rear end portions, and the piezoelectric / electrostrictive element 24 has a multi-stage structure. The position of the piezoelectric / electrostrictive element 24 and the material and size of the constituent members are determined. Since the piezoelectric / electrostrictive device 10B is appropriately selected and configured, it is possible to achieve both of the above conflicting characteristics, and a fixed portion between the open ends of the pair of thin plate portions 16a and 16b. The minimum resonance frequency of the structure when an object having substantially the same size as that of 22 is present is 20 kHz or more, and the relative displacement between the object and the fixed portion 22 is the resonance frequency. It is possible to 0.5μm or more substantive application voltage 30V at less than 1/4 the frequency.
As a result, the pair of thin plate portions 16a and 16b can be greatly displaced, and the displacement operation of the piezoelectric / electrostrictive device 10B, particularly the pair of thin plate portions 16a and 16b, can be speeded up (high resonance frequency). be able to.
Further, in the piezoelectric / electrostrictive device 10B according to the second embodiment, a minute displacement of the piezoelectric / electrostrictive element 24 is amplified to a large displacement operation using the bending of the thin plate portions 16a and 16b. Since it is transmitted to the movable part 20, the movable part 20 can be largely displaced with respect to the major axis m (see FIG. 14) of the piezoelectric / electrostrictive device 10B.
In addition, in the piezoelectric / electrostrictive device 10B according to the second embodiment, it is not necessary to make all parts of the piezoelectric / electrostrictive material which is a fragile and relatively heavy material, so that the mechanical strength is high. It has the advantages that it has excellent handling properties, impact resistance and moisture resistance, and is hardly affected by harmful vibrations (for example, residual vibration and noise vibration during high-speed operation).
Further, as shown in FIG. 24, since the tip ends of the pair of thin plate portions 16a and 16b are open ends, when attaching various members and parts to the piezoelectric / electrostrictive device 10B, the pair of thin plate portions 16a. 16b can be used, and a member or a part can be sandwiched between these tips and attached. In this case, the mounting area of the member or component can be increased, and the mounting property of the component can be improved. Moreover, since the members and components to be attached are included in the pair of thin plate portions 16a and 16b, the size of the piezoelectric / electrostrictive device in the Y direction after the members and components are attached can be reduced. This is advantageous in downsizing.
Of course, as shown in FIG. 25, when the movable part 20 is fixed between the respective tip parts of the pair of thin plate parts 16a and 16b, various members and components are attached to one main surface of the movable part 20 with, for example, an adhesive. It will be fixed via.
In the second embodiment, the multilayer body constituting the multilayer piezoelectric / electrostrictive element 24 has a rear end 209 at a position where the front end 208 of the multilayer body does not include at least the fixing portion 22 in plan view. However, the end portion 28a of the electrode 28 is a position including at least the fixing portion 22 in a plane, and the end portion 30a of the electrode 30 is planarly including the fixing portion 22 in a plane. It is made to form in the position which does not contain.
For example, when the end portions of the pair of electrodes 28 and 30 are formed at positions included in the movable portion 20, the displacement operation of the pair of thin plate portions 16 a and 16 b is limited by the laminated piezoelectric / electrostrictive element 24, resulting in a large displacement. However, in the second embodiment, since the positional relationship is as described above, the disadvantage that the displacement operation of the movable portion 20 is restricted is avoided, and the pair of thin plate portions 16a and 16 The amount of displacement of 16b can be increased.
Next, a preferred configuration example of the piezoelectric / electrostrictive device 10B according to the second embodiment will be described. Since a preferred configuration example is almost the same as the piezoelectric / electrostrictive device 10A according to the first embodiment described above, a preferred configuration example specific to the piezoelectric / electrostrictive device 10B according to the second embodiment. Only explained.
First, in the piezoelectric / electrostrictive device 10B according to the second embodiment, when the shape of the piezoelectric / electrostrictive device 10B is not a plate shape as in the prior art, and the movable part 20 is provided, the movable part 20 The fixed portion 22 has a rectangular parallelepiped shape, and a pair of thin plate portions 16a and 16b are provided so that the side surfaces of the movable portion 20 and the fixed portion 22 are continuous. / The rigidity of the electrostrictive device 10B in the Y-axis direction can be selectively increased.
That is, in this piezoelectric / electrostrictive device 10B, only the operation of the movable portion 20 in the plane (in the XZ plane) can be selectively generated, and the operations in the YZ plane of the pair of thin plate portions 16a and 16b (so-called so-called) (Operation in the turning direction) can be suppressed.
The thin plate portions 16a and 16b are desirably made of metal, and the fixed portion 22 and the movable portion 20 may be made of different materials, but are more preferably made of metal. The thin plate portions 16 a and 16 b and the fixed portion 22, and the thin plate portions 16 a and 16 b and the movable portion 20 may be bonded with organic resin, brazing material, solder, or the like, but an integrated structure in which diffusion bonding or welding is performed between metals. More preferred. Furthermore, the use of cold-rolled metal is more desirable because of its high strength because there are many dislocations.
In the second embodiment, since the laminated piezoelectric / electrostrictive element 24 is formed only on one thin plate portion 16a, as shown in FIG. 30, a pair of thin plate portions 16a and 16b are respectively provided. It can be manufactured at a lower cost compared to the multilayer piezoelectric / electrostrictive elements 24a and 24b (modified example). Further, in the second embodiment, when the movable portion 20 is fixed, the thin plate portion 16a on which the multilayer piezoelectric / electrostrictive element 24 is formed is directly displaced and interlocked therewith. Therefore, since the thin thin plate portion 16b where the multilayer piezoelectric / electrostrictive element 24 is not formed is displaced, it can be displaced more greatly.
The formation of the multilayer piezoelectric / electrostrictive element 24 on the thin plate portion 16a can be realized by bonding the multilayer piezoelectric / electrostrictive element 24 to the thin plate portion 16a with an organic resin, a brazing material, solder or the like. However, in the case of bonding at a low temperature, an organic resin is desirable, and in the case of bonding at a high temperature, a brazing material, solder, glass or the like is preferable. However, since the thin plate portion 16a, the laminated piezoelectric / electrostrictive element 24, and the adhesive 202 generally have different thermal expansion coefficients, the laminated piezoelectric / electrostrictive element 24 does not generate stress due to the difference in thermal expansion coefficient. In order to do so, it is desirable that the bonding temperature be low. An organic resin is preferably used because it can be bonded at a temperature of approximately 180 ° C. or lower. More preferably, a room temperature curable adhesive is used. When the thin plate portions 16a and 16b and the piezoelectric / electrostrictive element 24 are fixed after the fixed portion 22 and the movable portion 20 are fixed to the thin plate portions 16a and 16b or simultaneously, the fixed portion 22 or the movable portion 20 is fixed. If it is an open type structure, the distortion which generate | occur | produces between dissimilar materials can be reduced effectively.
In order to prevent thermal stress from being applied to the laminated piezoelectric / electrostrictive element 24, the laminated piezoelectric / electrostrictive element 24 and the thin plate portion 16a are bonded with an organic resin, and the thin plate portions 16a and 16b are fixed to the fixing portion. It is preferable that fixing of 22 and the movable part 20 is made into another process.
Further, as shown in FIG. 31, when a part of the piezoelectric / electrostrictive element 24 is located on the fixed portion 22, the boundary portion between the movable portion 20 and the fixed portion 22 in the pair of thin plate portions 16 a and 16 b. La is the shortest distance between the portions, and the distance from the boundary portion between the movable portion 20 and the thin plate portion 16a to any one of the ends 28a or 30a of the pair of electrodes 28 and 30 of the laminated piezoelectric / electrostrictive element 24. Among these, when Lb is the shortest distance, (1-Lb / La) is preferably 0.4 or more, and more preferably 0.5 to 0.8. If it is 0.4 or less, the displacement cannot be increased. In the case of 0.5 to 0.8, it is easy to achieve both the displacement and the resonance frequency. In this case, a structure in which the laminated piezoelectric / electrostrictive element 24 is formed only on one thin plate portion 16a is more preferable. Is suitable. The same applies to the case where a part of the piezoelectric / electrostrictive element 24 is located on the movable portion 20.
The total thickness of the multilayer piezoelectric / electrostrictive element 24 is preferably 40 μm or more. If the thickness is less than 40 μm, it is difficult to bond the laminated piezoelectric / electrostrictive element 24 to the thin plate portion 16a. The total thickness is preferably 180 μm or less. If it exceeds 180 μm, it is difficult to reduce the size of the piezoelectric / electrostrictive device 10B.
Of the laminated piezoelectric / electrostrictive element 24, when a metal such as a brazing material or a solder layer is used as the adhesive 202, the portion in contact with the thin plate portion 16 a has a wettability relationship as shown in FIGS. 28 and 29. It is preferable that an electrode film exists in the lowest layer. 28 and 29 show a state in which an electrode film constituting the other electrode 30 is arranged.
When the laminated piezoelectric / electrostrictive element 24 shown in FIGS. 26 and 28 is bonded to the thin plate portion 16a via a metal layer such as a brazing material or a solder layer, the laminated piezoelectric / electrostrictive element 24 is laminated as shown in FIGS. Of the lower surface of the piezoelectric / electrostrictive element 24, it is preferable to chamfer the corner where at least one electrode 28 exists. This is to prevent the pair of electrodes 28 and 30 from being short-circuited through the metal layer and the thin plate portion 16a. FIG. 27 shows an example in which two corners where a pair of electrodes 28 and 30 exist are chamfered, and FIG. 29 shows an example in which a corner where one electrode 28 exists is chamfered.
Examples of the adhesive 202 for bonding the laminated piezoelectric / electrostrictive element 24 to the thin plate portion 16a and the adhesive 200 for bonding the thin plate portions 16a and 16b to the fixing portion 22 and the like include epoxy, isocyanate type 2 and the like. Liquid-type reactive adhesives, instant adhesives such as cyanoacrylates, hot-melt adhesives such as ethylene-vinyl acetate copolymers may be used. In particular, the laminated piezoelectric / electrostrictive element 24 is provided on the thin plate portion 16a. As the adhesive 202 for bonding, an adhesive having a hardness of Shore D of 80 or more is preferable.
The adhesive 202 for bonding the thin plate portions 16a and 16b and the piezoelectric / electrostrictive element 24 (24a and 24b) is preferably an organic adhesive containing a filler such as metal or ceramic. In this case, the thickness of the adhesive 202 is desirably 100 μm or less. This is because by containing the filler, the substantial thickness of the resin can be reduced and the hardness of the adhesive can be kept high.
The adhesives 200 and 202 may be inorganic adhesives in addition to the organic adhesives described above, and examples of the inorganic adhesives include glass, cement, solder, and brazing material.
Next, several manufacturing methods for manufacturing the piezoelectric / electrostrictive device 10B according to the second embodiment will be described with reference to FIGS.
In the third manufacturing method, first, as shown in FIG. 32, a rectangular hole 252 having a length of 1 mm and a width of 8 mm is formed in the center of a stainless steel plate 250 having a length of 1.6 mm, a width of 10 mm, and a thickness of 0.9 mm. Then, a base body 258 having a rectangular annular structure in which support portions 254 and 256 are arranged on both sides of the hole 252 is manufactured.
Then, as shown in FIG. 33, a first stainless steel plate 260 having a length of 1.6 mm × width of 10 mm × thickness of 0.05 mm and a second stainless steel plate 262 having a length of 1.6 mm × width of 10 mm × thickness of 0.02 mm ( Prepare (see FIG. 35).
Thereafter, as shown in FIG. 33, an adhesive 202 (for example, an epoxy resin adhesive) is formed on the upper surface of the first stainless steel thin plate 260 on the portion where the laminated piezoelectric / electrostrictive element 24 is formed by screen printing. To do. Thereafter, as shown in FIG. 34, the laminated piezoelectric / electrostrictive element 24 is bonded to the first stainless steel thin plate 260 via the adhesive 202.
Thereafter, as shown in FIG. 35, an adhesive 200 (for example, an epoxy resin adhesive) is formed on each support portion 254 and 256 of the base 258 by screen printing.
Thereafter, the first stainless steel thin plate 260 on which the laminated piezoelectric / electrostrictive element 24 has already been formed is bonded onto one surface of each of the support portions 254 and 256 via the adhesive 200, and each support portion 254 is bonded. The second stainless steel thin plate 262 is bonded to the other surface of the second stainless steel plate 256 via the adhesive 200, and the first and second stainless steel thin plates 260 and 262 are further pressed in the direction of sandwiching the base 258. A device master 270 shown in FIG. The applied pressure is 0.1 to 10 kgf / cm.2It is.
Thereafter, as shown in FIG. 36, the device master 270 is cut at the portion of the cutting line 272 and separated into individual piezoelectric / electrostrictive devices 10B as shown in FIG. This cutting process was performed using a wire saw having a wire diameter of 0.1 mm and an interval of 0.2 mm. By using a wire saw, the width of the piezoelectric / electrostrictive element 24, the width of the thin plate portion 16a, and the widths of the adhesives 200 and 202 can be defined almost the same, although the materials are different from each other.
Next, in the fourth manufacturing method, as shown in FIG. 37, a rectangular hole 252 having a length of 1 mm × width of 8 mm is drilled in the center of a stainless steel plate 250 having a length of 1.6 mm × width of 10 mm × thickness of 0.9 mm. Then, a base body 258 having a rectangular annular structure in which support portions 254 and 256 are arranged on both sides of the hole 252 is manufactured.
Thereafter, an adhesive 200 (for example, an epoxy resin adhesive) is formed on each support portion 254 and 256 of the base 258 by screen printing.
Thereafter, as shown in FIG. 38, the first stainless steel thin plate 260 having a length of 1.6 mm × width of 10 mm × thickness of 0.05 mm is bonded onto one surface of each of the support portions 254 and 256 via the adhesive 200, A second stainless steel plate 262 having a length of 1.6 mm, a width of 10 mm, and a thickness of 0.02 mm is bonded to the other surface of each of the support portions 254 and 256 with an adhesive 200, and the first and second The stainless steel plates 260 and 262 are pressed in the direction in which the base 258 is sandwiched. The applied pressure is 0.1 to 10 kgf / cm.2It is.
Thereafter, an adhesive 202 (for example, an epoxy resin adhesive) is formed by screen printing on a portion of the upper surface of the first stainless steel thin plate 260 where the laminated piezoelectric / electrostrictive element 24 is to be formed.
Thereafter, as shown in FIG. 40, the laminated piezoelectric / electrostrictive element 24 is bonded to the first stainless steel thin plate 260 via the adhesive 202, and the device master 270 is manufactured.
Thereafter, as shown in FIG. 36, the device master 270 is cut at the portion of the cutting line 272 and separated into individual piezoelectric / electrostrictive devices 10B as shown in FIG.
A part of the piezoelectric / electrostrictive device 10B manufactured by the third and fourth manufacturing methods (for example, the fixing portion 22) is fixed, and a pair of electrodes 28 and 30 of the multilayer piezoelectric / electrostrictive element 24 is fixed. When the bias voltage of 15 V and the sine wave voltage of ± 15 V were applied and the displacement of the movable part 20 was measured, it was ± 1.2 μm. Further, the lowest resonance frequency indicating the maximum displacement was measured by sweeping the frequency as a sine wave voltage ± 0.5 V, and it was 50 kHz.
In the third and fourth manufacturing methods described above, the base 258 has a rectangular annular structure having a support portion 254 to be the movable portion 20 and a support portion 256 to be the fixed portion 22 later. 41, the hole 252 is widened, and a frame-like portion 254a that supports the first and second stainless steel thin plates 260 and 262 (at least a portion that substantially defines the thickness of the portion where the movable portion 20 intervenes later). And a rectangular annular structure having a support portion 256 to be the fixing portion 22 later.
In this case, the base 258 is fixed via the adhesive 200 so as to be sandwiched between the first and second stainless steel thin plates 260 and 262, and a device master 270 similar to that shown in FIG. 36 is manufactured. Further, in FIG. By cutting along the cutting line 272 as shown, for example, as shown in FIG. 44, a piezoelectric / electrostrictive device in which the movable portion 20 does not exist between the tip portions of the thin plate portions 16a and 16b can be manufactured.
As another manufacturing method, for example, as shown in FIG. 44, an adhesive 200 and a fixing portion 22 are arranged between the rear end portions of the thin plate portions 16a and 16b, respectively, and as shown by a two-dot chain line, Each of the thin plate portions 16a and 16b is arranged by disposing the adhesive 200, the movable portion 20 and the pressure spacer 310 between the thin plate portions 16a and 16b, respectively, and then pressing from both sides of the thin plate portions 16a and 16b, for example. The fixed portion 22 is fixed between the rear end portions via the adhesive 200, and the movable portion 20 is fixed to the tip portions of the thin plate portions 16a and 16b via the adhesive 200, respectively. In this case, since the pressure spacer 310 is not fixed to the movable portion 20 with an adhesive or the like, it can be easily removed after cutting along the cutting line 272. In addition, in order to adjust thickness (distance between the fixing | fixed part 22 and each thin plate part 16a and 16b) between the fixing | fixed part 22 and each thin-plate part 16a and 16b, 2nd of the thickness substantially the same as the movable part 20 is adjusted. The fixing portions (not shown) may be fixed between the fixing portion 22 and the thin plate portions 16a and 16b on both sides of the fixing portions via an adhesive 200.
Next, a fifth manufacturing method different from the third and fourth manufacturing methods described above will be described with reference to FIGS.
In the fifth manufacturing method, as in the third and fourth manufacturing methods described above, the device master 270 is formed by bonding the support portions 254 and 256 to the first stainless steel thin plate 260 and the second stainless steel thin plate 262. It can also be applied to the case where the piezoelectric / electrostrictive device 10B is manufactured and then separated into individual piezoelectric / electrostrictive devices 10B. The piezoelectric / electrostrictive elements 24a and 24b are formed on the thin plate portions 16a and 16b. The present invention can also be applied to the case where the piezoelectric / electrostrictive device 10B is manufactured by fixing the formed unit to the fixed portion 22 (and the movable portion 20 as appropriate) separately prepared.
In the following description, the support portion 256 and the fixing portion 22 that will later become the fixing portion 22 will be referred to as “fixing portion 22” for convenience, and the first and second stainless steel thin plates 260 and 262 that will become the thin plate portions 16a and 16b later. The thin plate portions 16a and 16b are referred to as “thin plate portions 16a and 16b” for convenience.
42, when the thin plate portions 16a and 16b are bonded to the fixing portion 22 via the adhesive 200, when a fluid adhesive is used, a place where the adhesive 200 is formed is defined. Therefore, it is preferable to provide steps 280am and 280bm in the thin plate portions 16a and 16b. Of course, when a highly viscous adhesive is used, it is not necessary to provide such a step. Further, in this example, it is assumed that a fluid adhesive is used when an object (not shown) is bonded between the open ends of the thin plate portions 16a and 16b, and the thin plate portions 16a and 16b are opened. Steps 280an and 280bn are also provided on the opposite surfaces of the ends. The steps 280am and 280an and 280bm and 280bn may be formed by stacking plate-like objects.
FIG. 43 shows a case where a highly viscous adhesive is used as the adhesive 200 used for bonding the fixing portion 22 and the thin plate portions 16a and 16b, and at least the portion to which the fixing portion 22 is bonded is as described above. The example which does not provide the level | step differences 280am and 280bm is shown.
FIG. 44 shows a case where a highly viscous adhesive is used as the adhesive 200 used for bonding the fixing portion 22 and the thin plate portions 16a and 16b, and has a structure in which the steps 280am and 280bm as described above are not provided. Show. In this example, it is assumed that a highly viscous adhesive is used when an object (not shown) is bonded between the open ends of the thin plate portions 16a and 16b, and the open ends of the thin plate portions 16a and 16b. Steps 280an and 280bn are not provided on the surfaces facing each other.
FIG. 45 shows a case where a highly fluid adhesive is used as the adhesive 200 used for bonding the fixing portion 22 and the thin plate portions 16a and 16b. In particular, the adhesive 200 is applied to the thin plate portions 16a and 16b. An example in which protrusions 282am and 282bm are provided for partitioning the formation region is shown. Further, in this example, it is assumed that a fluid adhesive is used when an object (not shown) is bonded between the open ends of the thin plate portions 16a and 16b, and the thin plate portions 16a and 16b are opened. Protrusions 282an and 282bn are also provided on the opposite surfaces of the ends.
As shown in FIG. 46, in the example shown in FIG. 42, the size of the fixing portion 22, in particular, the area of the surface facing the step 280 of the thin plate portions 16a and 16b is made larger than the areas of the steps 280am and 280bm. May be. Thereby, for example, in the thin plate portions 16a and 16b, a substantial driving portion (a portion between the steps 280am and 280an and a portion between 280bm and 280bn) can be defined by the steps 280am and 280bm. As shown in FIG. 42, when the area of the surface facing the steps 280am and 280bm of the thin plate portions 16a and 16b in the fixing portion 22 is substantially the same as the areas of the steps 280am and 280bm, the fixing portion 22 and the steps 280am and A variation in size with 280 bm may affect the length of the substantial driving portion. 46 shows an example in which the fixing portion 22 is increased in the direction of the open ends of the thin plate portions 16a and 16b, it may be increased in the direction opposite to the above direction.
In FIGS. 42 to 46, the steps 280am, 280bm, 280an and 280bn, the protrusions 282am, 282bm, 282an and 282bn and the thin plate portions 16a and 16b are integrated with each other. Similarly, it may be provided by laminating with an adhesive. In the case of providing them integrally, the thin plate portions 16a and 16b are formed by thinning the plate member by etching, cutting or the like, and at the same time, the steps 280am, 280bm, 280an and 280bn and the protrusions 282am, 282bm, 282an and 282bn are integrated. Can be provided.
In the above example, the adhesives 200 and 202 are formed by screen printing. However, other methods such as dipping, dispenser, and transfer can be used.
Next, for example, various configurations relating to the adhesive 202 interposed between the thin plate portion 16 a and the laminated piezoelectric / electrostrictive element 24 and the adhesive 200 interposed between the thin plate portions 16 a and 16 b and the fixing portion 22. An example will be described with reference to FIGS. 47 to 52.
First, in the first method shown in FIG. 47, a large number of holes 290 are provided in the thin plate portion 16a, and the laminated piezoelectric / electrostrictive element 24 is bonded to the portion where the holes 290 are provided via the adhesive 202. Like that. In this case, since the adhesive 202 enters the hole 290, the adhesive area is substantially increased and the thickness of the adhesive 202 can be reduced. The thickness of the adhesive 202 is 5% or less of the total thickness of the multilayer piezoelectric / electrostrictive element 24, and is thick enough to absorb thermal stress due to the difference in thermal expansion coefficient between the thin plate portion 16a and the adhesive 202. The above is preferable.
The diameter of the holes 290 is preferably 5 μm to 100 μm, and the arrangement pattern may be a matrix or a staggered arrangement. Of course, a plurality of holes 290 may be arranged in a line. The arrangement pitch of the holes 290 is preferably 10 μm to 200 μm. Further, a recess (hole) may be used instead of the hole 290. In this case, the hole diameter is preferably 5 μm to 100 μm, and the arrangement pattern may be a matrix or a staggered arrangement. The arrangement pitch of the holes is preferably 10 μm to 200 μm. In particular, in the case of a recess (hole), for example, a rectangular shape may be used, and the opening area may be slightly smaller than the projected area of the piezoelectric / electrostrictive element 24 on the thin plate portion 16a. As a method for forming the hole 290 or the hole in the thin plate portion 16a, for example, etching, laser processing, punching, drilling, electric discharge processing, ultrasonic processing, or the like can be employed.
In the second method shown in FIG. 48, the surface 292 of the portion where the multilayer piezoelectric / electrostrictive element 24 is formed in the thin plate portion 16a is roughened by blasting, etching or plating. In this case, the lower surface 294 of the multilayer piezoelectric / electrostrictive element 24 is also roughened. Thereby, since the adhesion area is substantially increased, the thickness of the adhesive 202 can be reduced.
FIG. 48 shows an example in which the surface of the thin plate portion 16a and the lower surface of the piezoelectric / electrostrictive element 24 (surface facing the thin plate portion 16a) are roughened, but the surface having the smaller adhesive force with the adhesive 202 is roughened. For example, even if only the surface of the thin plate portion 16a is roughened, there is a sufficient effect. As the surface roughness, for example, when viewed from the center line average roughness, Ra = 0.1 μm to 5 μm is preferable, and more preferably 0.3 μm to 2 μm.
In the third method shown in FIG. 49, the protrusion shape of the adhesive 200, in particular, the protrusion shape of the adhesive 200 to the inner wall 22a of the fixing portion 22 is made to have a curvature 296. In this case, it is preferable that the radius of curvature is 0.05 mm or more and the protruding shape is linear or includes a linear portion. The curvature 296 of the protruding portion of the adhesive 200 is formed by, for example, inserting a cylindrical core material into the space formed by the thin plate portions 16a and 16b and the inner wall 22a of the fixing portion 22 before the adhesive 200 is cured. Can be realized. Actually, it is controlled by the physical properties and the coating amount of the adhesive 200 so that at least the protruding shape does not become convex.
Thereby, since the inner wall 22a of the fixing portion 22 and the inner walls of the thin plate portions 16a and 16b are also used as the bonding surfaces, the bonding area can be increased and the bonding strength can be increased. Further, the stress concentration on the joint portion (corner portion) between the inner wall 22a of the fixed portion 22 and the inner walls of the thin plate portions 16a and 16b can be effectively dispersed.
The fourth method shown in FIG. 50 is to chamfer the corner portions of the inner wall 22a of the fixed portion 22 to form a tapered surface 298. By appropriately adjusting the chamfering angle and the radius of curvature, the amount of protrusion of the adhesive 200 can be stabilized, local variations in adhesive strength can be suppressed, and the yield can be improved.
As a method for chamfering the corner portion, for example, it is preferable to preliminarily grind and polish the portion to be the corner portion of the support portion 256 to form the tapered surface 298 before assembly. Of course, the chamfering may be performed after assembly. In this case, laser processing, ultrasonic processing, sandblasting, etc. are preferably employed.
In the fifth method shown in FIG. 51, for example, when the thin plate portions 16a and 16b are manufactured, punching is usually performed. In this case, a flash 300 is generated. The generated flash 300 may be removed before assembly, but may be left as it is. In this case, it is preferable to define the direction of the generated flash 300 in consideration of handling, the bonding direction of each member, the ease of control over the amount of adhesive, and the like. In the example of FIG. 51, a state in which the flash 300 of the thin plate portions 16a and 16b is directed outward is shown.
In the sixth method shown in FIG. 52, as described above, the thickness of one thin plate portion 16a is made larger than the thickness of the other thin plate portion 16b. And when using as the actuator part 204, it is preferable to form the lamination type piezoelectric / electrostrictive element 24 on one thin plate part 16a. Even when used as a sensor, the laminated piezoelectric / electrostrictive element 24 is preferably formed on one thin plate portion 16a.
As another method, for example, when the laminated piezoelectric / electrostrictive element 24 is bonded to the thin plate portions 16a and 16b via the adhesive 202, the lower surface of the laminated piezoelectric / electrostrictive element 24 is, for example, ZrO.2A layer may be interposed as an underlayer.
Further, when the stainless thin plates 260 and 262 (see FIG. 33, etc.) are used as the thin plate portions 16a and 16b, the longitudinal direction of the thin plate portions 16a and 16b and the cold rolling direction of the stainless thin plates 260 and 262 are substantially matched. It is preferable to make it.
Note that the piezoelectric / electrostrictive layer 26 constituting the multilayer piezoelectric / electrostrictive element 24 is preferably laminated by about 3 to 10 layers.
According to the piezoelectric / electrostrictive devices 10A and 10B described above, various transducers, various actuators, frequency domain functional parts (filters), transformers, vibrators and resonators for communication and power, resonators, discriminators, etc. In addition to active elements, it can be used as sensor elements for various sensors such as ultrasonic sensors, acceleration sensors, angular velocity sensors, impact sensors, and mass sensors, and in particular, displacement of various precision parts such as optical equipment and precision equipment. It can be suitably used for various actuators used in mechanisms for positioning, positioning and angle adjustment.
In addition, the piezoelectric / electrostrictive device and the manufacturing method thereof according to the present invention are not limited to the above-described embodiments, and various configurations can be adopted without departing from the gist of the present invention.
As described above, according to the piezoelectric / electrostrictive device and the manufacturing method thereof according to the present invention, the life of the piezoelectric / electrostrictive device, the handling property, the mounting property of the component to the movable part, or the fixing property of the device are improved. As a result, the movable part can be greatly displaced at a relatively low voltage, and at the same time, the displacement operation of the piezoelectric / electrostrictive device, particularly the movable part, can be speeded up (high resonance frequency). In addition, it is difficult to be affected by harmful vibrations, can respond at high speed, has high mechanical strength, has excellent handling properties, impact resistance, and moisture resistance, as well as accurate vibration of moving parts. A sensor element that can be detected well can be obtained.
FIG. 1 is a perspective view showing a configuration of a piezoelectric / electrostrictive device according to a first embodiment.
FIG. 2 is a perspective view showing a first modification of the piezoelectric / electrostrictive device according to the first embodiment.
FIG. 3 is a perspective view showing a second modification of the piezoelectric / electrostrictive device according to the first embodiment.
FIG. 4 is a perspective view showing a third modification of the piezoelectric / electrostrictive device according to the first embodiment.
FIG. 5 is a perspective view showing a fourth modification of the piezoelectric / electrostrictive device according to the first embodiment.
FIG. 6 is a perspective view showing a fifth modification of the piezoelectric / electrostrictive device according to the first embodiment.
FIG. 7 is a perspective view showing another example of a piezoelectric / electrostrictive device according to a fifth modification.
FIG. 8 is a perspective view showing a sixth modification of the piezoelectric / electrostrictive device according to the first embodiment.
FIG. 9 is a perspective view showing a seventh modification of the piezoelectric / electrostrictive device according to the first embodiment.
FIG. 10 is a perspective view showing another example of the piezoelectric / electrostrictive element with a part thereof omitted.
FIG. 11 is a perspective view showing another example of the piezoelectric / electrostrictive element with a part thereof omitted.
FIG. 12 is an explanatory diagram showing a case where the piezoelectric / electrostrictive element is not performing a displacement operation in the piezoelectric / electrostrictive device according to the first embodiment.
FIG. 13A is a waveform diagram showing a voltage waveform applied to one piezoelectric / electrostrictive element, and FIG. 13B is a waveform diagram showing a voltage waveform applied to the other piezoelectric / electrostrictive element.
FIG. 14 is an explanatory diagram showing a case where the piezoelectric / electrostrictive element performs a displacement operation in the piezoelectric / electrostrictive device according to the first embodiment.
FIG. 15 is a perspective view showing a case where the other piezoelectric / electrostrictive device is fixed to a movable part of one piezoelectric / electrostrictive device.
FIG. 16A is an explanatory diagram showing a necessary process of laminating ceramic green sheets in the first manufacturing method, and FIG. 16B is an explanatory diagram showing a state in which a ceramic green laminate is formed.
FIG. 17A is an explanatory view showing a state in which the ceramic green laminate is fired to form a ceramic laminate, and FIG. It is explanatory drawing which shows the state adhere | attached on the surface.
18 is an explanatory view showing a state in which a hybrid laminate is obtained by bonding a metal plate to a ceramic laminate in the first manufacturing method. FIG.
FIG. 19 is an explanatory view showing a state where the hybrid laminate is cut along a predetermined cutting line to produce a piezoelectric / electrostrictive device according to a first modification.
FIG. 20A is an explanatory diagram showing a necessary process of laminating ceramic green sheets in the second manufacturing method, and FIG. 20B is an explanatory diagram showing a ceramic green laminate.
FIG. 21A is an explanatory view showing a state in which a ceramic green laminate is fired to form a ceramic laminate, and a hole is filled with a filler, and FIG. It is explanatory drawing which shows the state which adhere | attached on the laminated body and was set as the hybrid laminated body.
FIG. 22 is an explanatory view showing a state in which a piezoelectric / electrostrictive element configured as a separate body is bonded to the surface of a metal plate of a hybrid laminate.
FIG. 23 is an explanatory view showing a state in which a hybrid laminate is cut along a predetermined cutting line to produce a piezoelectric / electrostrictive device according to a first modification.
FIG. 24 is a perspective view showing a configuration of a piezoelectric / electrostrictive device according to a second embodiment.
FIG. 25 is a perspective view showing another configuration of the piezoelectric / electrostrictive device according to the second embodiment.
FIG. 26 is an enlarged view showing a configuration example of a multilayer piezoelectric / electrostrictive element.
27 is an enlarged view showing a preferred configuration example of the multilayer piezoelectric / electrostrictive element shown in FIG. 26. FIG.
FIG. 28 is an enlarged view showing another configuration example of the multilayer piezoelectric / electrostrictive element.
29 is an enlarged view showing a preferred configuration example of the multilayer piezoelectric / electrostrictive element shown in FIG. 28. FIG.
30 is a perspective view showing still another configuration of the piezoelectric / electrostrictive device according to the second embodiment. FIG.
FIG. 31 is an explanatory diagram showing a preferable dimensional relationship of the piezoelectric / electrostrictive device according to the second embodiment.
FIG. 32 is an explanatory view showing a state in which a rectangular hole-shaped base is manufactured by drilling a rectangular hole in the center of a stainless steel plate in the third manufacturing method.
FIG. 33 is an explanatory view showing a state in which an adhesive is formed on the first stainless steel sheet.
FIG. 34 is an explanatory view showing a state in which a laminated piezoelectric / electrostrictive element is bonded to a first stainless steel plate via an adhesive.
FIG. 35 is an explanatory diagram showing a state in which the first and second stainless steel thin plates are bonded to the base via an adhesive.
FIG. 36 is an explanatory diagram showing a state in which the fabricated device master is cut.
FIG. 37 shows a fourth manufacturing method in which a rectangular hole is formed in a central portion of a stainless steel plate to form a rectangular ring-shaped substrate, and the first and first substrates are bonded to the substrate via an adhesive. It is explanatory drawing which shows the state which adhere | attaches 2 stainless steel thin plates.
FIG. 38 is an explanatory view showing a state in which the first and second stainless steel thin plates are bonded to the base via an adhesive.
FIG. 39 is an explanatory view showing a state in which an adhesive is formed on the first stainless steel sheet.
FIG. 40 is an explanatory view showing a state in which the laminated piezoelectric / electrostrictive element is bonded to the first stainless steel plate via an adhesive.
FIG. 41 is an explanatory view showing a state in which the first and second stainless steel thin plates are bonded to the base of another example via an adhesive.
FIG. 42 is an explanatory diagram showing an example in which a step is provided in at least a portion to which the fixing portion is bonded among the thin plate portions in the fifth manufacturing method.
FIG. 43 is an explanatory diagram showing an example in which no step is provided in at least a portion of the thin plate portions to which the fixing portion is bonded in the fifth manufacturing method.
FIG. 44 is an explanatory diagram showing an example in which no step is provided in each thin plate portion in the fifth manufacturing method.
45 is an explanatory view showing an example in which, in the fifth manufacturing method, a protrusion for forming an adhesive section is provided in a portion of each thin plate portion to which a fixing portion is bonded. FIG.
FIG. 46 is an explanatory diagram showing an example in which a fixing portion is enlarged in the fifth manufacturing method.
FIG. 47 is an explanatory diagram showing a first method (providing a hole in a thin plate portion).
FIG. 48 is an explanatory diagram showing a second method (thinning the surface of the thin plate portion and the piezoelectric / electrostrictive element).
FIG. 49 is an explanatory diagram showing a third method (providing curvature at the protruding portion of the adhesive);
FIG. 50 is an explanatory diagram showing a fourth method (chamfering corner portions of the fixing portion).
FIG. 51 is an explanatory diagram showing a fifth technique (turning the beam outward);
FIG. 52 is an explanatory diagram showing a sixth technique (changing the thickness of the thin plate portion).
FIG. 53 is a block diagram showing a piezoelectric / electrostrictive device according to a conventional example.
10A, 10Aa to 10Ag, 10B ... Piezoelectric / electrostrictive device
12 ... holes 16a, 16b ... thin plate portions
24 ... Piezoelectric / electrostrictive element 152A, 152B ... Metal plate
200, 202 ... Adhesive 204 ... Actuator
208 ... tip of multilayer body 258 ... substrate
270 ... Device master
280am, 280bm, 280an, 280bn ... step
282am, 282bm, 282an, 282bn ... projection
Fixed to a fixed portion that is a rectangular body, a pair of opposing rectangular plate-like thin plate portions fixed to a pair of opposing side surfaces of the fixed portion, and a pair of opposed surfaces of the pair of thin plate portions, respectively A pair of opposed movable parts,
Of the pair of thin plate sections, a piezoelectric / electrostrictive device pressure electric / electrostrictive element on at least one thin portion is formed,
Each of the pair of thin plate portions is made of metal,
Of the one thin plate portion, the piezoelectric / electrostrictive element is formed on a surface opposite to the surface facing the other thin plate portion,
The pair of movable portions, the piezoelectric / electrostrictive device, characterized in that the closed end faces facing each other.
The piezoelectric / electrostrictive device according to claim 1,
The distance between the end faces of the pair of movable parts is equal to or longer than the length of the side face of the movable part extending toward the fixed part .
The piezoelectric / electrostrictive device according to claim 1 ,
The movable part has a cut part,
A piezoelectric / electrostrictive device according to claim 1, wherein a part of the cut portion constitutes the end surfaces facing each other.
The piezoelectric / electrostrictive device according to claim 1 or 2 ,
The same member as the constituent member of the movable part or a plurality of different members are interposed between the opposing end surfaces,
The piezoelectric / electrostrictive device according to claim 1, wherein an area of a surface of the member facing the end face is substantially the same as an area of the end face.
The piezoelectric / electrostrictive device according to claim 4 .
A piezoelectric / electrostrictive device, wherein at least one of the plurality of members is an organic resin.
The piezoelectric / electrostrictive device according to claim 4 or 5 ,
A hole is formed by the opposing inner walls of the pair of thin plate portions, the inner wall of the plurality of members facing the fixing portion, and the inner wall of the fixing portion facing the inner walls of the plurality of members ,
A piezoelectric / electrostrictive device, wherein the hole is filled with a gel material.
A rectangular movable body, a pair of opposing rectangular plate-like thin plate portions fixed to a pair of opposing side surfaces of the movable portion, and a pair of opposing surfaces of the pair of thin plate portions, respectively. A pair of opposing fixed parts,
A piezoelectric / electrostrictive device in which a piezoelectric / electrostrictive element is formed on at least one of the pair of thin plate portions,
The pair of fixing portions have end faces facing each other, and the piezoelectric / electrostrictive device according to claim 1.
The piezoelectric / electrostrictive device according to claim 7,
The fixed portion has a cut portion,
The piezoelectric / electrostrictive device according to claim 7 or 8,
The same member as the constituent member of the fixed portion or a plurality of different members are interposed between the opposing end surfaces,
2. The piezoelectric / electrostrictive device according to claim 1, wherein an area of a surface of the member facing the end face is substantially the same as an area of the end face.
The piezoelectric / electrostrictive device according to claim 9,
The piezoelectric / electrostrictive device according to claim 9 or 10,
A hole is formed by the opposing inner walls of the pair of thin plate portions, the inner wall of the plurality of members facing the movable portion, and the inner wall of the movable portion facing the inner walls of the plurality of members,
The piezoelectric / electrostrictive device according to any one of claims 1 to 11,
The piezoelectric / electrostrictive device is characterized in that the movable portion and the fixed portion are formed of a ceramic base body which is formed by firing a ceramic green laminate and further cutting away unnecessary portions.
The piezoelectric / electrostrictive device according to any one of claims 1 to 12 ,
2. The piezoelectric / electrostrictive device according to claim 1, wherein the piezoelectric / electrostrictive element has a film shape and is fixed to the thin plate portion with an adhesive.
The piezoelectric / electrostrictive device according to claim 13 ,
The piezoelectric / electrostrictive device, wherein the adhesive is made of an organic resin.
A piezoelectric / electrostrictive device, wherein the adhesive is made of glass, brazing material or solder.
The piezoelectric / electrostrictive device according to any one of claims 13 to 15 ,
The piezoelectric / electrostrictive element is
A piezoelectric / electrostrictive device comprising a piezoelectric / electrostrictive layer and a pair of electrodes formed on the piezoelectric / electrostrictive layer.
The piezoelectric / electrostrictive device according to claim 16 ,
A piezoelectric / electrostrictive device, wherein the piezoelectric / electrostrictive layer and a plurality of the pair of electrodes are formed in a laminated form.
The piezoelectric / electrostrictive device according to any one of claims 1 to 17 ,
A piezoelectric / electrostrictive device, wherein a gap is formed between the end faces facing each other.
The piezoelectric / electrostrictive device according to any one of claims 1 to 18 ,
A piezoelectric / electrostrictive device having a structure in which internal residual stress generated in the thin plate portion and / or the piezoelectric / electrostrictive element at the time of manufacture is released by forming the end faces facing each other. .
Wherein the pair of thin plate portions, a manufacturing method of a piezoelectric / electrostrictive device pressure electric / electrostrictive element on at least one thin portion is formed,
The first substrate, Engineering and as you produce a second substrate by fixing a metal plate with a thin plate portion after,
By at least one ablation process, manufacturing method of the piezoelectric / electrostrictive device and having a degree Engineering you forming the movable portion to have a mutually facing end surfaces with respect to the second substrate.
The method of manufacturing a piezoelectric / electrostrictive device according to claim 20 ,
The first base is composed of a ceramic laminate,
Laminating and firing at least one ceramic green sheet having at least a window portion to produce a ceramic laminate,
Said thin plate portion and formed of a metal plate and fixed with an adhesive have a hybrid laminate manufacturing step of manufacturing a hybrid laminate after the ceramic laminate,
The ceramic laminate manufacturing process includes:
A method of manufacturing a piezoelectric / electrostrictive device , comprising firing a plurality of ceramic green sheets having a window portion for forming the movable portion having at least end surfaces facing each other to produce the ceramic laminate .
A rectangular movable body, a pair of opposing rectangular plate-like thin plate portions fixed to a pair of opposing side surfaces of the movable portion, and a pair of opposing surfaces of the pair of thin plate portions, respectively. A pair of opposed movable parts,
A method for manufacturing a piezoelectric / electrostrictive device in which a piezoelectric / electrostrictive element is formed on at least one of the pair of thin plate portions,
A step of producing a second substrate by fixing a metal plate, which will later become a thin plate portion, to the first substrate;
Forming the fixing portion having end faces facing each other by at least one excision process on the second substrate. A method for manufacturing a piezoelectric / electrostrictive device, comprising:
The method of manufacturing a piezoelectric / electrostrictive device according to claim 22,
A hybrid laminate production step of producing a hybrid laminate by fixing a metal plate to be the thin plate portion later to the ceramic laminate via an adhesive,
A method of manufacturing a piezoelectric / electrostrictive device, comprising firing a plurality of ceramic green sheets having a window portion for forming the fixing portion having at least end faces facing each other to produce the ceramic laminate.
In the manufacturing method of the piezoelectric / electrostrictive device according to any one of claims 20 to 23 ,
A method for manufacturing a piezoelectric / electrostrictive device, comprising a step of fixing the piezoelectric / electrostrictive element to an outer surface of the metal plate to be a thin plate portion later with an adhesive.
The method of manufacturing a piezoelectric / electrostrictive device according to claim 24 ,
The piezoelectric / electrostrictive element is fixed to the outer surface of the metal plate in advance before the metal plate to be the thin plate portion is fixed to the first substrate. Device manufacturing method.
In the manufacturing method of the piezoelectric / electrostrictive device according to claim 24 or 25 ,
A method for manufacturing a piezoelectric / electrostrictive device, wherein an adhesive made of an organic resin is used as the adhesive.
A method for manufacturing a piezoelectric / electrostrictive device, wherein an adhesive made of glass, brazing material or solder is used as the adhesive.
The method for manufacturing a piezoelectric / electrostrictive device according to claim 20 or 22 ,
The first substrate is made of metal,
A method for manufacturing a piezoelectric / electrostrictive device, comprising: a step of manufacturing the first substrate by laminating at least one metal sheet having at least a window portion.
The method for manufacturing a piezoelectric / electrostrictive device, wherein the first base is made of a bulk metal member.
The method for manufacturing a piezoelectric / electrostrictive device according to any one of claims 20 to 29 ,
A method of manufacturing a piezoelectric / electrostrictive device, comprising a step of interposing a plurality of members different from the constituent members of the movable portion or the fixed portion between the end faces facing each other.
The method of manufacturing a piezoelectric / electrostrictive device according to claim 30 ,
A method of manufacturing a piezoelectric / electrostrictive device, wherein an organic resin is used as at least one member among the plurality of members.
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US09/524,042 US6498419B1 (en) 1999-10-01 2000-03-13 Piezoelectric/electrostrictive device having mutually opposing end surfaces and method of manufacturing the same
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