Piezo-electric/electrostrictive device and method of manufacturing same

According to the present invention, a piezoelectric / electrostrain device having a movable portion that operates based on the displacement operation of the piezoelectric / electrostrain element, or a displacement of the movable portion is displaced by the piezoelectric / electrostrain element. The present invention relates to a detectable piezoelectric / strain device and a method for manufacturing the same, and more particularly to a piezoelectric / strain device having excellent strength, impact resistance, and moisture resistance and capable of efficiently operating a large moving part and a method for manufacturing the same.

[0002] [Conventional Technology] Recently, in fields such as optics, magnetic recording, and precision machining, a displacement element capable of adjusting the optical path length and position on the submicron order has been required, and a piezoelectric / electrostrictive material (piezoelectric / electrolytic strain material For example, the development of a displacement element that utilizes the displacement caused by the inverse piezoelectric effect or the electrostrictive effect caused when a voltage is applied to a ferroelectric substance or the like is being promoted.

[0003] Conventionally, as such a displacement element, for example, as in JP-A-10-136665, a material made of a piezoelectric / electrostrictive material is provided in a plate-like body with holes to form a fixed portion and a movable portion. A piezoelectric actuator is disclosed in which a beam portion that supports them is integrally formed, and an electrode layer is provided on the beam portion. In this piezoelectric actuator, when a voltage is applied to the electrode layer, the beam portion expands and contracts in the direction connecting the fixed portion and the movable portion due to the inverse piezoelectric effect and the electric strain effect, so that the movable portion is placed in the plane of the plate-like body. It can be arcuate or rotationally displaced.

[0004] Further, in Japanese Patent Application Laid-Open No. 63-64640, regarding an actuator using a bimorph, the electrode of the bimorph is divided and provided, and the divided electrode is selected and driven to perform high-precision positioning. A technique for high-speed operation is disclosed, and this publication (particularly FIG. 4) shows a structure in which, for example, two bimorphs are used facing each other.

[0005] [Problems to be Solved by the Invention] However, since all the parts of these conventional actuators are made of a fragile and relatively heavy material, the mechanical strength is low, and the handling property and the impact resistance are improved. There was an inferior problem. Further, when improving the mechanical strength of these actuators, it has been conventionally performed to improve the strength of a portion that easily vibrates. Then, in order to achieve this, it is necessary to improve the direction of increasing the rigidity of the vibrating part, which affects the basic characteristics such as the resonance characteristic and the displacement of the actuator itself, and there is a problem that the adjustment becomes difficult.

[Means for Solving the Problems] The present invention is described in Japanese Patent Application No. 11-114669, Japanese Patent Application No. 11-259006, and Japanese Patent Application No. 11-259007, which were previously filed by the present inventor. It was conceived based on improving the impact resistance of the force sensor. Furthermore, with respect to the force sensor using a piezoelectric body described in US Application No. 09/501162, by arranging a viscoelastic body in a narrow groove formed on the lower surface of the abutment, an external impact applied to the working body is absorbed. This was achieved against the background of making it easier and improving the impact resistance of the diaphragm.

[0007] Therefore, in order to improve the impact resistance while reducing the influence on the basic characteristics of the device itself, the invention according to claim 1 is made.<u style="single">Have flexibility</u>With a pair of thin plates facing each other<u style="single">, The base end of both thin plates between these thin plates</u>The tip portion of the pair of thin plate portions is provided with a fixing portion for supporting.<u style="single">, Displaces with the displacement operation of the thin plate portion</u>A piezoelectric / electrostraining device having a movable portion and having one or more piezoelectric / electrostrain elements arranged in at least one thin plate portion of the pair of thin plate portions, wherein the thin plate portion and the movable portion<u style="single">When connecting with and / or</u>The thin plate portion and the fixed portion<u style="single">At the time of connection, a gap portion along the thin plate portion is formed, and the gap portion is formed.</u>A piezoelectric / electrostraining device characterized in that a filler is placed in a gap. As a result, even if the thin plate portion undergoes a large displacement due to a large external impact, the stress generated near the boundary line where the thin plate portion and the movable portion or the thin plate portion and the fixed portion are joined is dispersed in the filling of the void portion. The damage caused by stress concentration was eliminated and the impact resistance of the thin plate was improved. Here, the piezoelectric / electrostraining device is a concept including an element that mutually converts electrical energy and mechanical energy by a piezoelectric / electrostraining element. Therefore, it is most preferably used as an active element such as various actuators and vibrators, particularly as a displacement element utilizing displacement due to a reverse voltage effect or an electric distortion effect, and is also suitable as a passive element such as an acceleration sensor element or an impact sensor element. Can be used for.

[0008] The material of the filler may be an organic resin such as an adhesive, glass, a mixture of organic resin and ceramics, a metal, a mixture of metal and ceramics, or the like. Further, the filler may be porous or dense, and the harder the filler, the more porous it is, and the higher the flexibility, the more dense it is. Further, it is preferable that the filling layer is adhered to the thin plate portion, the moving portion and the fixing portion, and has springiness or flexibility by itself. Further, the filling material is preferably a viscoelastic body, and the viscoelastic property effectively absorbs an external impact. The shape of the gap portion on which the filling is arranged may be a rectangular shape, or the inner surface of the movable portion or the fixed portion facing the thin plate portion may be stepped or inclined. When the devices are laminated with a green sheet, the voids may be formed of either a single layer or a multilayer. When configured with a single layer spacing, the spacing thickness is 0.01 to 0.3 mm, the spacing depth is 0.03 to 1 mm, and (spacing thickness) / (spacing depth) is 0.01 or more and 10 or less. It is preferable, and more preferably 0.1 or more and 3 or less. On the other hand, in the case of a multi-layered structure, it is preferable to improve the thickness of the gap according to the longitudinal direction of the thin plate portion. Here, the spacing thickness of the gap portion refers to the length of the minimum spacing portion, and the spacing does not necessarily have to be uniform over the entire surface, and the spacing between the inlet portion or the bottom portion may be large.

[0009] Further, the manufacturing method of the above device is a thin plate portion.<u style="single">A pair</u>With the first ceramic green sheet<u style="single">, Becomes a gap</u>Has a first window<u style="single">plural</u>With a second ceramic green sheet<u style="single">, A second window that becomes a space between the thin plates and is shorter in length than the first window.</u>Have a window<u style="single">plural</u>The process of preparing the third ceramic green sheet and<u style="single">The second ceramic green sheet is arranged inside the first ceramic green sheet arranged at both ends, and the third ceramic green sheet is arranged inside the second ceramic green sheet. The second and third ceramic green sheets are sandwiched between a pair of first ceramic green sheets.</u>The process of producing the laminate and<u style="single">The first step of firing the laminate, the step of forming a piezoelectric / electrostrictive element on the surface of the first ceramic green sheet before or after firing the laminate, and the first firing of the laminate. The step of cutting out the piezoelectric / electrolytic strain device by cutting both ends of the second window portion in the width direction and at least one end in the length direction at a plane parallel to the stacking direction of the ceramic green sheet, and the above. A step of filling the voids formed by the first window portion of the piezoelectric / electrolytic strain device with a filler.</u>A method for manufacturing a piezoelectric / electrostrictive device, which comprises the above, is preferable. In addition, it becomes a thin plate part<u style="single">A pair</u>With the first ceramic green sheet<u style="single">, Sheets containing refractory metal and voids</u>Have a window<u style="single">plural</u>The process of preparing the second ceramic green sheet and<u style="single">A sheet containing a refractory metal is arranged inside the first ceramic green sheet arranged at both ends, and the second ceramic green sheet is arranged inside the sheet containing the refractory metal. A step of producing a laminate in which a sheet containing the refractory metal and a second ceramic green sheet are sandwiched between the first ceramic green sheets, a step of firing the laminate, and a step of firing the laminate. The step of forming a piezoelectric / electrolytic strain element on the surface of the first ceramic green sheet before or after firing, and the fired laminate are applied to both ends of the window portion in the width direction and at least one end in the length direction. Is cut along a plane parallel to the stacking direction of the ceramic green sheet to cut out the piezoelectric / electrolytic strain device.</u>A method for manufacturing a piezoelectric / electrostrictive device, which comprises the above, is also preferable. Further, it is preferable that the sheet containing the refractory metal is formed by a printing molding method.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of a piezoelectric / electrostrictive device according to the present invention will be described in detail. FIG. 1 is a perspective view of the piezoelectric / electrostrictive device 10. The piezoelectric / electrostrain device 10 includes a base 16 integrally formed with a pair of thin plate portions 12a and 12b that support each other and a fixing portion 14 that supports the pair of thin plate portions 12a and 12b, and each part of each of the pair of thin plate portions 12a and 12b is provided. Piezoelectric / electrostrictive elements 18a and 18b are formed and configured. Then, in the piezoelectric / electrostrain device 10, the pair of thin plate portions 12a and 12b are displaced by driving the piezoelectric / electrostrain elements 18a and / or 18b, or the displacement of the thin plate portions 12a and 12b is displaced by the piezoelectric / electrostrain element. It has a configuration to detect by 18a and / or 18b. Further, in the pair of thin plate portions 12a and 12b, each tip portion is thickened inward, and the thick portion is a movable portion 20a and 20b that is displaced by the displacement operation of the thin plate portions 12a and 12b. It will work. Hereinafter, the tip portions of the pair of thin plate portions 12a and 12b will be referred to as movable portions 20a and 20b.

[0011] At the boundary where the tip portions of the thin plate portions 12a and 12b and the movable portions 20a and 20b are joined, gap portions 20c and 20d are formed along the longitudinal direction of the thin plate portions 12a and 12b, and the gap portions are formed with gap portions 20c and 20d. Filling is provided. Similarly, gaps 14a and 14b are formed along the longitudinal direction of the thin plate portions 12a and 12b at the boundary portion where the base end portions of the thin plate portions 12a and 12b and the fixing portion 14 are joined, and the gap portions 14a and 14b are formed in these gap portions. Filling is provided.

[0012] The substrate 16 may have a hybrid structure in which the entire substrate 16 is made of ceramics or a combination of ceramics and a metal material.

[0013] Further, the substrate 16 has a structure in which each part is bonded with an adhesive such as an organic resin or glass, a ceramic integrated structure in which ceramic green laminates are integrated by firing, brazing, soldering, and eutectic bonding. Alternatively, a structure such as a metal integrated structure integrated by welding or the like can be adopted, and it is preferable that the base 16 is composed of a ceramic laminate in which the ceramic green laminate is integrated by firing.

[0014] Of these, the ceramic integrated product has high reliability of the joint portion and is advantageous for ensuring rigidity because the adhesive does not intervene in the joint portion of each portion and therefore the state change hardly occurs with time. In addition to having a structure, it can be easily manufactured by the ceramic green sheet laminating method described later.

[0015] As for the piezoelectric / electrolytic strain elements 18a and 18b, the piezoelectric / electrolytic strain elements 18a and 18b are prepared separately as described later, and the substrate 16 is brazed with an adhesive such as an organic resin or glass. In addition to being attached by soldering, eutectic bonding, etc., by using the film forming method, it is formed directly on the substrate 16 instead of the above attachment.

[0016] The piezoelectric / electrostrain elements 18a and 18b are configured to have a piezoelectric / electrostrain layer 22 and a pair of electrodes 24 and 26 formed on both sides of the piezoelectric / electrostrain layer 22, and the pair. One of the electrodes 24 and 26 is formed on at least a pair of thin plate portions 12a and 12b.

[0017] In the present embodiment, the piezoelectric / electrolytic strain layer 22 and the pair of electrodes 24 and 26 have a multilayer structure, respectively, and one electrode 24 and the other electrode 26 are staggered so as to have a substantially comb-like cross section. The case where the piezoelectric / electrolytic strain elements 18a and 18b are laminated and the portion where the one electrode 24 and the other electrode 26 overlap with the piezoelectric / electrolytic strain layer 22 sandwiched between them is a multi-stage configuration will be mainly described. The structure is not limited to the multi-layer structure, and may be a single-layer structure. In this case, the number of layers is not particularly limited, but is preferably 10 layers or less, and more preferably 5 layers or less. Further, it is possible to use only one of the piezoelectric / electrostrictive elements 18a and 18b, and a large number of elements may be different.

[0018] In FIG. 1, the piezoelectric / electrolytic strain layer 22 has a three-layer structure, and one electrode 24 is combed so as to be located on the lower surface of the first layer (side surfaces of the thin plate portions 12a and 12b) and the upper surface of the second layer. An example is shown in which the electrodes 26 are formed in a tooth shape, and the other electrode 26 is formed in a comb shape so as to be located 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 28 and 30 can be reduced by connecting and sharing one electrode 24 and the other electrode 26, respectively, so that the piezoelectric / electrolytic distortion elements 18a and 18b can be multi-layered. It is possible to suppress the accompanying increase in size.

[0019] The voltage applied to the pair of electrodes 24 and 26 is applied to the terminals 28 and 30 formed on both side surfaces (element forming surfaces) of the fixed portion 14 of the electrodes 24 and 26, respectively. It is supposed to be done through. At the positions of the terminals 28 and 30, the terminal 28 corresponding to one electrode 24 is formed near the rear end of the fixed portion 14, and the terminal 30 corresponding to the other electrode 26 on the external space side is close to the inner wall of the fixed portion 14. Is formed in.

[0020] In this case, the piezoelectric / electrostrictive device 10 can be fixed separately by using a surface different from the surface on which the terminals 28 and 30 are arranged, and as a result, the piezoelectric / electrostrictive device 10 can be fixed. High reliability can be obtained for both the fixation of 10 and the electrical connection between the circuit and terminals 28 and 30. In this configuration, terminals 28 and 30 are electrically connected to the circuit by a flexible printed circuit (also referred to as FPC), a flexible flat cable (also referred to as FFC), wire bonding, or the like.

[0021] By using the piezoelectric / electrolytic strain elements 18a and 18b having a multilayer structure in this way, the driving force of the actuator portions 19a and 19b is increased, so that a large displacement can be achieved and the piezoelectric / electrolytic strain device 10 itself can be displaced. By increasing the rigidity, a high resonance frequency can be achieved, and high-speed displacement operation can be easily achieved.

[0022] If the number of stages is increased, the driving force of the actuator units 19a and 19b can be increased, but the power consumption also increases accordingly. Therefore, when the number of stages is increased, the number of stages and the like are appropriately determined according to the application and the usage state. Just decide. Further, in the piezoelectric / electrostrain device 10 according to this embodiment, even if the driving force of the actuator portions 19a and 19b is increased by using the piezoelectric / electrostrain elements 18a and 18b, the thin plate portions 12a and 12b are basically used. Since the width (distance in the Y-axis direction) is invariant, it is a very preferable device for application to actuators such as positioning of a magnetic head for a hard disk used in a very narrow gap and ringing control.

Next, the operation of the piezoelectric / electrostrictive device 10 will be described with reference to FIG. First, when the two piezoelectric / electrostrain elements 18a and 18b are in the natural state, that is, when both the piezoelectric / electrostrain elements 18a and 18b are not performing displacement operation, they are fixed to the major axis m of the piezoelectric / electrostrain device 10. The central axis of part 14 is almost the same.

[0024] From this state, a sine wave Wa having a predetermined bias potential Vb is applied to the pair of electrodes 24 and 26 in one piezoelectric / electric strain element 18a, and the pair of electrodes 24 and 26 in the other piezoelectric / electric strain element 18b. A sine wave Wb having a phase different from that of the sine wave Wa is applied to 26.

[0025] Then, at the stage where, for example, the maximum voltage is applied to the pair of electrodes 24 and 26 in the one piezoelectric / electric strain element 18a, the piezoelectric / electric strain layer in the one piezoelectric / electric strain element 18a. 22 contracts and displaces in the direction of its main surface. As a result, for example, as shown in FIG. 2, a stress is generated for one thin plate portion 12a in a direction for bending the thin plate portion 12a to the right, for example, as shown by an arrow A. Therefore, the one thin plate portion 12a is bent. The portion 12a bends to the right, and at this time, no voltage is applied to the pair of electrodes 24 and 26 in the other piezoelectric / electrolytic strain element 18b, so that the other thin plate portion 12b is one thin plate. It bends to the right following the bending of the part 12a. As a result, the movable portions 20a and 20b and the spacer member 37 are displaced to the right, for example, with respect to the major axis m of the piezoelectric / electrostrain device 10b. The amount of displacement changes according to the maximum value of the voltage applied to each of the piezoelectric / electrostrain elements 18a and 18b. For example, the larger the maximum value, the larger the amount of displacement.

[0026] In particular, when a piezoelectric / electrostrain material having a high coercive potential is applied as the constituent material of the piezoelectric / electrostrain layer 22, the minimum level of the above-mentioned sine waves Wa and Wb is slightly negative. The bias potential may be adjusted so as to reach the level. In this case, by driving the piezoelectric / electrostrain element (for example, the other piezoelectric / electrostrain element 18b) to which the negative level is applied, for example, the other thin plate portion 12b is in the same direction as the bending direction of one thin plate portion 12a. Stress is generated, and it becomes possible to increase the displacement amount of the movable portions 20a and 20b and the spacer member 37. That is, by using the waveform as described above, the piezoelectric / electric strain element 18b or 18a to which a negative level is applied supports the piezoelectric / electric strain element 18a or 18b which is the main body of the displacement operation. It can have the function of doing.

[0027] As described above, in the piezoelectric / electrostrain device 10 according to the present embodiment, the minute displacement of the piezoelectric / electrostrain elements 18a and 18b becomes a large displacement operation by utilizing the deflection of the thin plate portions 12a and 12b. Since it is amplified and transmitted to the movable portions 20a and 20b, the movable portions 20a and 20b can be largely displaced with respect to the long axis m of the piezoelectric / electrostrain device 10b.

[0028] In particular, in this embodiment, the movable portions 20a and 20b are provided with mounting surfaces 34a and 34b facing each other, and the distance Lc between the mounting surfaces 34a and 34b is set to about 1.5 of the length Df of the movable portions 20a and 20b. It is set to double, and one large spacer member 37 is adhered between the mounting surfaces 34a and 34b via the adhesive 38. In this case, a gap is provided between the mounting surfaces 34a and 34b facing each other, or a spacer member 37 lighter than the constituent members of the movable portions 20a and 20b is interposed between the mounting surfaces 34a and 34b facing each other. The weight of the movable parts 20a and 20b can be effectively reduced, and the resonance frequency can be increased without reducing the displacement amount of the movable parts 20a and 20b.

[0029] Here, the frequency indicates the frequency of the voltage waveform when the voltage applied to the pair of electrodes 24 and 26 is alternately switched to displace the movable portions 20a and 20b to the left and right, and is referred to as the resonance frequency. Indicates the maximum frequency at which the displacement motions of the movable parts 20a and 20b can follow in a predetermined vibration mode.

[0030] Further, in the piezoelectric / electrostrictive device 10 according to this embodiment, the movable portions 20a and 20b, the thin plate portions 12a and 12b, and the fixed portion 14 are integrated, and all the portions are fragile and relatively relatively. Since it does not need to be composed of a heavy material, piezoelectric / electrostrictive material, it has high mechanical strength, excellent handling, impact resistance, and moisture resistance, and is harmful in operation (for example, residual vibration during high-speed operation). It has the advantage of being less susceptible to the effects of noise and vibration.

[0031] Further, in this embodiment, when there is a gap between the mounting surfaces 34a and 34b facing each other, the movable portion 20a including one mounting surface 34a and the movable portion 20b including the other mounting surface 34b are provided. And become more flexible and more resistant to deformation. Therefore, the handling property of the piezoelectric / electrostrain device 10 is excellent.

[0032] Further, the surface areas of the movable portions 20a and 20b are increased due to the presence of the mounting surfaces 34a and 34b facing each other. Therefore, when other parts are attached to the movable portions 20a and 20b, the attachment area can be increased and the attachmentability of the parts can be improved. Here, considering the case where the parts are fixed by, for example, an adhesive, the articles are bonded not only through the main surfaces (front and / or back) of the movable portions 20a and 20b, but also through the mounting surfaces 34a and 34b facing each other. Therefore, the parts can be securely fixed.

[0033] Further, in this embodiment, the piezoelectric / electric strain elements 18a and 18b are provided with the piezoelectric / electric strain layer 22 and a pair of electrodes 24 and 26 formed on both sides of the piezoelectric / electric strain layer 22. Of the pair of electrodes 24 and 26, one of the electrodes 24 is formed directly on the side surface of at least the thin plate portions 12a and 12b. It can be efficiently transmitted to the movable parts 20a and 20b through the parts 12a and 12b, and the responsiveness can be improved.

[0034] In this embodiment, for example, as shown in FIG. 1, a portion (substantially driving portion 40) in which the pair of electrodes 24 and 26 overlap with the piezoelectric / strain layer 22 sandwiched between them is fixed. It is formed continuously from a part of 14 to a part of thin plate portions 12a and 12b. When the substantial drive portion 40 is further formed over a part of the movable portions 20a and 20b, the displacement operation of the movable portions 20a and 20b contradicts the deformation of the substantial drive portion 40 and the deformation of the thin plate portions 12a and 12b. Although it may not be possible to obtain a large displacement, in this embodiment, since the substantially driving portion 40 is formed so as not to be applied to both the movable portions 20a and 20b and the fixed portion 14, the movable portion 20a And the inconvenience that the displacement operation of 20b is restricted is avoided, and the displacement amount of the movable parts 20a and 20b can be increased.

[0035] On the contrary, when the piezoelectric / electrostrain elements 18a and 18b are formed on a part of the movable parts 20a and 20b, the substantially driving part 40 is changed from a part of the movable parts 20a and 20b to the thin plate parts 12a and 12b. It is preferable to form it so that it is positioned over a part of. This is because when the substantially driving portion 40 is formed over a part of the fixed portion 14, the displacement operation of the movable portions 20a and 20b is limited as described above.

[0036] In the above example, mounting surfaces 34a and 34b are provided on the movable portions 20a and 20b, and a spacer member 37 is bonded between them. In addition, end surfaces 34a and 34b are provided on the fixed portion 14. You may. In this case, for example, the movable portions 20a and 20b provided at the tip portions of the pair of thin plate portions 12a and 12b have a shape of being integrally connected, and the fixing portions 14 are provided with end faces 34a and 34b facing each other. ..

[0037] This makes it possible to firmly fix the piezoelectric / electrostrain device 10c to a predetermined fixed portion, in addition to the effect of having the mounting surfaces 34a and 34b facing each other to the movable portions 20a and 20b described above. , Reliability can be improved. The length of the substantially driving portion 40 is preferably 20% to 95%, more preferably 40% to 80% of the length of the thin plate portions 12a and 12b.

[0038] Here, the shape of the filler when the shape of the void portion is a rectangular shape has an embodiment as shown in FIG. In Fig. 1, the rectangular parallelepiped-shaped gap can be filled up to the opening, whereas in Fig. 3 (a), the filling is filled to the middle of the gap and the vicinity of the opening is open. A predetermined amount of filler is filled. It has the effect of making the end face shape of the filling uniform. Even if a cavity that is not filled with the filler is formed at the bottom of the void, the stress dispersion force is not affected so much. On the contrary, in FIG. 3 (b), the filler is arranged to the outside from the opening of the void, and when the adhesion of the filler is weak, the adhesion area is increased and the overall adhesion is increased. be able to. In particular, by forming the outer surface of the filling material into an R shape, the fixability can be improved and peeling from the end portion can be prevented. Further, the filling material may be arranged in a formed shape as shown in FIG. 3 (c). In this case, in addition to the physical characteristics of the filling material, the shape of the corner portion between the thin plate portion and the fixed portion or the movable portion becomes a stepped shape, in other words, a cornering structure of the corner portion, and a shape effect is added. Therefore, there is an effect that the stress concentration at the root of the thin plate portion can be further reduced.

[0039] Next, a preferable configuration example of the piezoelectric / electrolytic strain device 10 according to the present embodiment will be described.

[0040] First, in order to ensure the displacement operation of the movable portions 20a and 20b, the distance Dg that the substantially driving portion 40 of the piezoelectric / electrostrain elements 18a and 18b takes over the fixed portion 14 or the movable portions 20a and 20b. Is preferably 1/2 or more of the thickness Dd of the thin plate portions 12a and 12b.

The ratio Da / Db of the distance (distance in the X-axis direction) Da between the inner walls of the thin plate portions 12a and 12b and the width (distance in the Y-axis direction) Db of the thin plate portions 12a and 12b is 0.5 to 20. It is configured to be. The ratio Da / Db is preferably 1 to 15, and more preferably 1 to 10. The specified value of this ratio Da / Db is a regulation based on the discovery that the displacement amount of the movable parts 20a and 20b can be increased and the displacement in the XZ plane can be predominantly obtained.

On the other hand, the ratio De / Da of the length (distance in the Z-axis direction) De of the thin plate portions 12a and 12b to the distance Da between the inner walls of the thin plate portions 12a and 12b is preferably 0.5 to 10. More preferably, it is 0.5 to 5. The specified value of this ratio De / Da can increase the displacement amount of the movable parts 20a and 20b in which the spacer member 37 is interposed, and can perform the displacement operation at a high resonance frequency (a high response speed can be achieved). It is a regulation based on the discovery.

[0043] Therefore, the piezoelectric / electrostrain device 10 according to this embodiment suppresses the displacement or vibration in the Y-axis direction, has excellent high-speed response, and has a large displacement at a relatively low voltage. For the structure, the ratio Da / Db is preferably 0.5 to 20 and the ratio De / Da is 0.5 to 10, and more preferably the ratio Da / Db is 1 to 10 and the ratio De / Da should be 0.5 ~ 5.

[0044] Further, for example, in the piezoelectric / electrostrain device 10, both inner walls of the pair of thin plate portions 12a and 12b, the inner walls of the movable portions 20a and 20b, the inner wall of the spacer member 37 (and the inner wall of the adhesive 38), and the fixing portion. A hole 42 is formed by the inner wall of 14, and it is preferable to fill the hole 42 with a gel-like material, for example, silicon gel. Normally, the presence of the filler limits the displacement operation of the movable parts 20a and 20b, but in this embodiment, the weight reduction due to the formation of the end faces 34a and 34b on the movable parts 20a and 20b is performed. Since the displacement amount of the movable parts 20a and 20b is increased, the limitation of the displacement operation of the movable parts 20a and 20b by the filler is canceled, and the effect due to the presence of the filler, that is, the high resonance frequency is increased. And rigidity can be ensured.

[0045] Further, the length (distance in the Z-axis direction) Df of the movable portions 20a and 20b is preferably short. This is because the weight can be reduced and the resonance frequency can be increased by shortening the length. Further, when the article is sandwiched, the displacement can be improved. However, in order to secure the rigidity of the movable parts 20a and 20b in the X-axis direction and ensure their displacement, the ratio Df / Dd of the thin plate parts 12a and 12b to the thickness Dd should be 2 or more, preferably 5. It is desirable to do the above.

[0046] The actual dimensions of each part are the joint area for attaching parts to the movable parts 20a and 20b, the joint area for attaching the fixed part 14 to other members, and the attachment of electrode terminals and the like. It will be determined in consideration of the junction area, the strength of the entire piezoelectric / electrolytic strain device 10, the durability, the required displacement amount, the resonance frequency, the drive voltage, and the like.

Specifically, for example, the distance Da between the inner walls of the thin plate portions 12a and 12b is preferably 100 μm to 2000 μm, and more preferably 200 μm to 1600 μm. The width Db of the thin plate portions 12a and 12b is preferably 50 μm to 2000 μm, more preferably 100 μm to 500 μm. The thickness Dd of the thin plate portions 12a and 12b is set to Db&gt; Dd in relation to the width Db of the thin plate portions 12a and 12b so that the fanning displacement, which is a displacement component in the Y-axis direction, can be effectively suppressed. It is preferably 2 μm to 100 μm, more preferably 10 μm to 80 μm.

[0048] The length De of the thin plate portions 12a and 12b is preferably 200 μm to 3000 μm, and more preferably 300 μm to 2000 μm. The lengths Df of the moving portions 20a and 20b are preferably 50 μm to 2000 μm, more preferably 100 μm to 1000 μm, and even more preferably 200 μm to 600 μm.

With such a configuration, the displacement in the Y-axis direction does not exceed 10% with respect to the displacement in the X-axis direction, but it is low by appropriately adjusting within the above-mentioned dimensional ratio and the actual size range. It can be driven by voltage and has an extremely excellent effect of suppressing the displacement component in the Y-axis direction to 5% or less. That is, the movable portions 20a and 20b are substantially displaced in the uniaxial direction called the X-axis direction, and moreover, they are excellent in high-speed response and can obtain a large displacement at a relatively low voltage.

[0050] Further, in the piezoelectric / electrolytic strain device 10, the shape of the device is not a plate shape as in the conventional case (the thickness in the direction orthogonal to the displacement direction is small), but the movable portions 20a and 20b and the fixed portion 14 are formed. It has a rectangular parallelepiped shape (thickness in the direction orthogonal to the displacement direction is large), and a pair of thin plate portions 12a and 12b are provided so that the movable portions 20a and 20b and the side surfaces of the fixed portion 14 are continuous. The rigidity of the piezoelectric / electrolytic strain device 10 in the Y-axis direction can be selectively increased.

That is, in the piezoelectric / electrostrain device 10 adopting this dimensional configuration, only the movements of the movable portions 20a and 20b in the plane (in the XZ plane) can be selectively generated, and the movable portions 20a and 20b can be generated. It is possible to suppress the movement in the YZ plane (the movement in the so-called fanning direction).

[0052] Next, each component of the piezoelectric / electrostrictive device 10 according to this embodiment will be described.

[0053] As described above, the movable portions 20a and 20b are portions that operate based on the driving amount of the thin plate portions 12a and 12b, and various members are attached according to the purpose of use of the piezoelectric / electrostrictive device 10. .. For example, when the piezoelectric / electrostrictive device 10 is used as a displacement element, a shielding plate for an optical shutter or the like is attached, and particularly when it is used for positioning a magnetic head of a hard disk drive or a ringing suppression mechanism, it is magnetic. Members that require positioning, such as a head, a slider with a magnetic head, and a suspension with a slider, are attached.

[0054] As described above, the fixed portion 14 is a portion that supports the thin plate portions 12a and 12b and the movable portions 20a and 20b. For example, when used for positioning the magnetic head of the hard disk drive, the fixed portion 14 is a VCM (voice). By supporting and fixing the fixing portion 14 to the carriage arm attached to the coil motor), the fixing plate attached to the carriage arm, the suspension, or the like, the entire piezoelectric / electrolytic strain device 10 is fixed. Further, the fixing portion 14 may be provided with terminals 28 and 30 and other members for driving the piezoelectric / electrostrain elements 18a and 18b.

[0055] The materials constituting the movable portions 20a and 20b and the fixed portion 14 are not particularly limited as long as they have rigidity, but ceramics to which the ceramic green sheet laminating method described later can be applied can be preferably used. Specific examples thereof include materials containing stabilized zirconia, partially stabilized zirconia and other zirconia, alumina, magnesia, silicon nitride, aluminum nitride, and titanium oxide as main components, and a mixture thereof as the main component. However, in terms of high mechanical strength and toughness, zirconia, particularly a material containing stabilized zirconia as a main component and a material containing partially stabilized zirconia as a main component are preferable.

[0056] As described above, the thin plate portions 12a and 12b are portions driven by the displacement of the piezoelectric / electrostrain elements 18a and 18b. The thin plate portions 12a and 12b are flexible thin plate-shaped members, and the expansion and contraction displacements of the piezoelectric / electrostrain elements 18a and 18b arranged on the surface are amplified as bending displacements, and the movable portions 20a and 20b. Has the function of transmitting to. Therefore, the shapes and materials of the thin plate portions 12a and 12b need only be flexible and have mechanical strength to the extent that they are not damaged by bending deformation, and the responsiveness and operability of the movable portions 20a and 20b can be improved. It can be appropriately selected in consideration.

[0057] The thickness Dd of the thin plate portions 12a and 12b is preferably about 2 μm to 100 μm, and the combined thickness of the thin plate portions 12a and 12b and the piezoelectric / strain elements 18a and 18b is 7 μm to 500 μm. preferable. The thickness of the electrodes 24 and 26 is preferably 0.1 μm to 50 μm, and the thickness of the piezoelectric / strain layer 22 is preferably 3 μm to 300 μm.

[0058] As the material constituting the thin plate portions 12a and 12b, ceramics similar to the movable portions 20a and 20b and the fixed portion 14 can be preferably used, and zirconia, particularly a material and a portion containing stabilized zirconia as a main component. A material containing stabilized zirconia as a main component is most preferably used because it has high mechanical strength even if it is thin, has high toughness, and has low reactivity with a piezoelectric / electrolytic strain layer or an electrode material.

[0059] In the stabilized zirconia and the partially stabilized zirconia, those stabilized and partially stabilized as follows are preferable. That is, compounds that stabilize and partially stabilize zirconia include yttrium oxide, ytterbium oxide, cerium oxide, calcium oxide, and magnesium oxide, and by adding or containing at least one of these compounds, or by adding or containing one of them. The target zirconia can be stabilized not only by adding the compounds of the above, but also by adding these compounds in combination.

[0060] 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 in the case of cerium oxide. It is preferably ~ 50 mol%, preferably 8 ~ 20 mol%, and in the case of calcium oxide or magnesium oxide, it is preferably 5 ~ 40 mol%, preferably 5 ~ 20 mol%, and among them, yttrium oxide is particularly preferable. Is preferably used as a stabilizer, and in that case, it is preferably 1.5 to 10 mol%, more preferably 2 to 4 mol%. Alumina, silica, transition metal oxides, etc. can be added in the range of 0.05 to 20 wt% as additives such as sintering aids, but as a method for forming the piezoelectric / electrolytic strain elements 18a and 18b, When the calcination integration by the film forming method is adopted, it is also preferable to add alumina, magnesia, a transition metal oxide or the like as an additive.

[0061] It is desirable that the average crystal particle size of zirconia is 0.05 to 3 μm, preferably 0.05 to 1 μm so that mechanical strength and a stable crystal phase can be obtained. Further, as described above, for the thin plate portions 12a and 12b, the same ceramics as those of the movable portions 20a and 20b and the fixed portion 14 can be used, but preferably, substantially the same material is used. However, it is advantageous in terms of reliability of the joint portion, strength of the piezoelectric / electrolytic strain device 10, and reduction of manufacturing complexity.

[0062] Piezoelectric / electrostrain elements 18a and 18b have at least a piezoelectric / electrostrain layer 22 and a pair of electrodes 24 and 26 for applying an electric field to the piezoelectric / electrostrain layer 22, and are unimorph type. Piezoelectric / electrostrain elements such as the bimorph type can be used, but the unimorph type combined with the thin plate portions 12a and 12b is superior in the stability of the amount of displacement generated and is advantageous for weight reduction. Suitable for piezoelectric / electrostraining devices 10.

[0063] As shown in FIG. 1, it is preferable that the piezoelectric / electrostrain elements 18a and 18b are formed on the side surfaces of the thin plate portions 12a and 12b in that the thin plate portions 12a and 12b can be driven more greatly.

Piezoelectric ceramics are preferably used for the piezoelectric / electric strain layer 22, but electric strain ceramics, ferroelectric ceramics, or antiferroelectric ceramics can also be used. However, when this piezoelectric / electric strain device 10 is used for positioning the magnetic head of a hard disk drive, the linearity between the displacement amount of the moving parts 20a and 20b and the drive voltage or output voltage is important, so that the strain history It is preferable to use a small material, and it is preferable to use a material having a coercive force 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 antimonthrate, lead manganese tungstate, and cobalt niobate. Examples thereof include ceramics containing lead acid acid, barium titanate, sodium bismuth titanate, potassium niobate sodium, strontium bismuth tantrate, etc. alone or as a mixture.

[0066] In particular, a product having a high electromechanical coupling coefficient and a piezoelectric constant, having a small reactivity with the thin plate portions (ceramics) 12a and 12b at the time of sintering the piezoelectric / electrolytic strain layer 22, and having a stable composition can be obtained. In this respect, a material containing lead zirconate, lead titanate, and lead magnesium niobate as main components, or a material containing sodium bismuth titanate as a main component is preferably used.

[0067] Further, the materials include lanthanum, calcium, strontium, molybdenum, tungsten, barium, niobium, zinc, nickel, manganese, cerium, cadmium, chromium, cobalt, antimony, iron, ittium, tantalum, lithium, bismuth, and tin. You may use ceramics containing oxides such as, etc. alone or in combination.

[0068] For example, by adding lanthanum or strontium to lead zirconate titanate, lead titanate titanate, and lead magnesium niobate, which are the main components, it may be possible to obtain advantages such as adjustment of coercive electric field and piezoelectric characteristics. is there.

[0069] It is desirable to avoid the addition of materials that are easily vitrified, such as silica. This is because a material such as silica easily reacts with the piezoelectric / strain material during the heat treatment of the piezoelectric / strain layer 22, fluctuates its composition, and deteriorates the piezoelectric characteristics.

[0070] On the other hand, the pair of electrodes 24 and 26 of the piezoelectric / electrolytic strain elements 18a and 18b are preferably solid at room temperature and are made of a metal having excellent conductivity, for example, aluminum, titanium, chromium, etc. Metals such as iron, cobalt, nickel, copper, zinc, niobium, molybdenum, ruthenium, palladium, rhodium, silver, tin, tantal, tungsten, iridium, platinum, gold, lead, etc., or alloys thereof are used, and further. A cermet material in which the same or different materials as the piezoelectric / electrolytic strain layer 22 or the thin plate portions 12a and 12b are dispersed may be used.

[0071] The material selection of the electrodes 24 and 26 in the piezoelectric / strain elements 18a and 18b is determined depending on the method of forming the piezoelectric / strain layer 22. For example, when one electrode 24 is formed on the thin plate portions 12a and 12b and then the piezoelectric / electrolytic strain layer 22 is formed on the one electrode 24 by firing, the piezoelectric / electrolytic strain layer is formed on the one electrode 24. It is necessary to use refractory metals such as platinum, palladium, platinum-palladium alloy, and silver-palladium alloy that do not change even at the firing temperature of 22, but after forming the piezoelectric / electrolytic strain layer 22, the piezoelectric / electrolytic strain Since the other electrode 26 of the outermost layer formed on the layer 22 can be electrode-formed at a low temperature, a low melting point metal such as aluminum, gold, or silver can be used as a main component.

[0072] Further, the thickness of the electrodes 24 and 26 is not a little a factor of reducing the displacement of the piezoelectric / strain elements 18a and 18b, so that the electrodes formed after firing the piezoelectric / strain layer 22 are particularly suitable. It is preferable to use a material such as an organic metal paste which can obtain a denser and thinner film after firing, for example, gold-resinate paste, platinum-resinate paste, silver-resinate paste and the like.

[0073] In the above example, the thickness of the movable portions 20a and 20b integrally formed at the tip portions of the thin plate portions 12a and 12b is made thicker than the thickness Dd of the thin plate portions 12a and 12b. The thickness of the movable portions 20a and 20b may be substantially the same as the thickness Dd of the thin plate portions 12a and 12b. As a result, when the article is attached to the movable portions 20a and 20b, it is possible to attach the article so as to sandwich the article having a size corresponding to the distance between the thin plate portions 12a and 12b between the movable portions 20a and 20b. In this case, the adhesive region (eg, adhesive 38) for attaching the article corresponds to the moving parts 20a and 20b.

[0074] The piezoelectric / electrolytic strain device 10 can be suitably used for various sensors such as an ultrasonic sensor, an acceleration sensor, an angular velocity sensor, an impact sensor, and a mass sensor, and can be used between the end faces 34a and 34b or the thin plate portions 12a and 12b. By appropriately adjusting the size of the object to be attached, there is a further advantage that the sensitivity of the sensor can be easily adjusted.

Next, as a preferred embodiment of the present invention, the case where the piezoelectric / electrostrain device 10 according to the second to fourth modifications includes end faces 34a and 34b as a preferred embodiment will be described with reference to FIG. 4 and the following. To do. Therefore, the present invention may be used even in an embodiment that does not include the end faces 34a and 34b.

[0076] First, as shown in FIG. 4, the piezoelectric / electrostrain device 10a according to the second modification has almost the same configuration as the piezoelectric / electrostrain device 10 described so far, but has a gap portion and a gap portion. The composition of the filling material differs in the following points. The gaps 14a and 14b have a stepped structure, and the closer to the thin plate, the deeper the groove depth. As a result, the concentrated stress generated at the boundary line between the thin plate portion and the movable portion and the fixed portion can be more effectively dispersed, and the wide gap portion contributes more to the impact absorption and the stress concentration is efficient. Can be dispersed. In particular, the other electrode 26 located on the lower surface of the first layer is formed substantially continuously over the side surfaces of the thin plate portions 12a and 12b, the movable portions 20a and 20b, and the fixing portion 14, and further, on the side surface of the fixing portion 14. Partially separated to form the slit 70. The purpose of providing the slit 70 is to drive the actuator in the rear end portion 72 (the portion from the rear end side end portion of the slit 70 to the rear end portion of the fixed portion 14) of the piezoelectric / electrostrain elements 18a and 18b. Do not let it, 2 : Make it difficult for a short circuit to occur at the end of one terminal 28, 3 : The electrode material is arranged on the lower surface of the piezoelectric / strain layer 22 at the rear ends of the piezoelectric / strain elements 18a and 18b. If it is not preferable to provide the slit 70, the slit 70 does not necessarily have to be provided and may be omitted. Further, FIG. 5 shows the shape of the filling material to be filled in the gap portion, and FIG. 5A shows the filling material being filled to the middle of the gap portion and the vicinity of the opening portion is open. Even if a cavity that is not filled with the filler is formed at the bottom of the void, the stress dispersion force is not affected so much. On the contrary, in FIG. 5 (b), the filler is arranged to the outside from the opening of the void, and when the adhesion of the filler is weak, the adhesion area is increased to increase the overall adhesion. be able to. In particular, by forming the outer surface of the filling material into an R shape, the fixability can be improved and peeling from the end portion can be prevented. In FIG. 5 (c), the material of the filling material is different for each layer forming the void portion. It is preferable to appropriately select physical properties such as elastic modulus and porosity, as well as adhesive force to the constituent material, and use a combination that exhibits the effect of stress dispersion.

Next, in the piezoelectric / electrostrain device 10b according to the third modification, the depth of the gap portion in FIG. 4 has two stages, whereas the gap portion in FIG. 6 has an infinite number of stages. It has a diagonal structure. As a result, the concentrated stress generated at the boundary line between the thin plate portion and the movable portion and the fixed portion can be more effectively dispersed, and the wide gap portion contributes more to the impact absorption and the stress concentration is efficient. Can be dispersed. Further, FIG. 7 shows the shape of the filling material to be filled in the gap portion, and FIG. 7A shows the filling material filled to the middle of the gap portion and the vicinity of the opening portion is open. Even if a cavity that is not filled with the filler is formed at the bottom of the void, the stress dispersion force is not affected so much. On the contrary, in FIG. 7 (b), the filler is arranged to the outside from the opening of the void, and when the adhesion of the filler is weak, the adhesion area is increased to increase the overall adhesion. be able to. In particular, by forming the outer surface of the filling material into an R shape, the fixability can be improved and peeling from the end portion can be prevented.

[0078] Further, in the piezoelectric / electrostrain device 10c according to the fourth modification, as shown in FIG. 8, the filler is arranged in the gap between the thin plate portion and the movable portion and the fixed portion with a substantially uniform thickness. Has been done. Such a filling is preferably formed at the same time that the thin plate portion, the moving portion and the fixing portion are integrally formed of ceramic, and is preferably a refractory metal or a mixture of a refractory metal and ceramic.

Next, a method of manufacturing the piezoelectric / electrolytic strain device 10 will be described with reference to FIGS. 9 to 12. In the piezoelectric / electrostrain device 10, the constituent material of each member is ceramics, and as the constituent elements of the piezoelectric / electrostrain device 10, the base 16 excluding the piezoelectric / electrostrain elements 18a and 18b, that is, the thin plate portions 12a and 12b, is fixed. It is preferable to manufacture the parts 14 and the movable parts 20a and 20b by using the ceramic green sheet laminating method, while the piezoelectric / electrostrain elements 18a and 18b and the terminals 28 and 30 are thin films and thick films. It is preferable to manufacture by using a film forming method such as.

[0080] According to the ceramic green sheet laminating method capable of integrally molding each member of the substrate 16 of the piezoelectric / electrostrictive device 10, the state of the joint portion of each member hardly changes with time. This is a method that has high reliability of the joint portion and is advantageous for ensuring rigidity.

[0081] Further, since the manufacturing method shown below is excellent in productivity and moldability, the piezoelectric / electrostrictive device 10 having a predetermined shape can be obtained in a short time and with good reproducibility.

[0082] Specifically, the first manufacturing method of the piezoelectric / electrostrictive device 10 according to the present embodiment will be described. Here, let's define it. The laminate obtained by laminating the ceramic green sheets is defined as the ceramic green laminate 58 (see, for example, FIG. 10), and the ceramic green laminate 58 fired and integrated is the ceramic laminate 60 (for example, FIG. 10). 11), and the ceramic substrate 16 (see FIG. 12) is defined as the ceramic laminate 60 in which unnecessary parts are cut off and the moving parts 20a and 20b, the thin plate parts 12a and 12b, and the fixing part 14 are integrated. Is defined as.

[0083] Further, in this manufacturing method, a plurality of piezoelectric / electrolytic strain devices 10 are arranged in the same substrate in the vertical direction and the horizontal direction, respectively, and finally the ceramic laminate 60 is cut into chip units. , A large number of piezoelectric / electrolytic strain devices 10 are taken in the same process, but for the sake of simplicity, the explanation will be made mainly of one piezoelectric / electric strain device 10.

[0084] First, a binder, a solvent, a dispersant, a plasticizer, or the like is added to and mixed with a ceramic powder such as zirconia to prepare a slurry, which is defoamed and then subjected to a reverse roll coater method, a doctor blade method, or the like. , A ceramic green sheet having a predetermined thickness is produced.

[0085] Next, the ceramic green sheet is processed into various shapes and thicknesses as shown in FIG. 9 by a method such as punching using a die or laser processing to form a plurality of ceramics for forming a substrate. Get a green sheet.

[0086] These ceramic green sheets 50A to 50D, 51A and 51B, 52A and 52B are made of a plurality of (for example, four) ceramics in which at least a window portion 54 for forming a space between the thin plate portions 12a and 12b is formed. The green sheets 50A to 50D are continuously formed with the window portion 54 for forming a space between the thin plate portions 12a and 12b and the window portion 100 for forming the movable portions 20a and 20b having the end faces 34a and 34b facing each other. Multiple (for example, 7) ceramic green sheets 102A to 102G, and multiple (for example, 2) ceramic green sheets 51A and 51B in which window portions 100a forming gaps 14a and 14b are continuously formed, and later Prepare a plurality of (for example, two) ceramic green sheets 52A and 52B to be the thin plate portions 12a and 12b.

After that, as shown in FIG. 10, the ceramic green sheets 50A to 50D, the ceramic green sheets 51A to 51B, and the ceramic green sheets 102A to 102G are sandwiched between the ceramic green sheets 52A and 52B, and these ceramic green sheets 50A to 50D, 51A, 51B, 52A and 52B and 102A to 102G are laminated and crimped to obtain a ceramic green laminate 58. In this laminating, the ceramic green sheets 102A to 102G are positioned in the center and laminated. At this time, due to the presence of the windows 100 and 100a, a portion where pressure is not applied during crimping is generated. Therefore, it is necessary to change the order of lamination and crimping so that such a portion does not occur. Then, the ceramic green laminate 58 is fired to obtain a ceramic laminate 60 (see FIG. 11).

[0088] The number and order of crimping for laminating and integrating are not limited. Depending on the structure, for example, the shape of the window portion 54, the number of ceramic green sheets, and the like can be appropriately determined so as to obtain a desired structure.

[0089] The shapes of the windows 54 do not have to be all the same and can be determined according to the desired function. Further, the number of ceramic green sheets and the thickness of each ceramic green sheet are not particularly limited.

[0090] In crimping, the stackability can be further improved by applying heat. In addition, ceramic powder (preferably having the same or similar composition as the ceramic used for the ceramic green sheet is preferable from the viewpoint of ensuring reliability), paste mainly composed of binder, slurry, etc. are applied and printed on the ceramic green sheet. Then, by using the bonding auxiliary layer, the stackability of the ceramic green sheet interface can be improved. When the ceramic green sheets 52A and 52B are thin, it is preferable to use a plastic film, particularly a polyethylene terephthalate film whose surface is coated with a silicone-based release agent.

Next, as shown in FIG. 11, piezoelectric / electrolytic strain elements 18a and 18b are applied to both surfaces of the ceramic laminate 60, that is, surfaces corresponding to the surfaces on which the ceramic green sheets 52A and 52B are laminated, respectively. Form. As the forming method of the piezoelectric / electrolytic strain elements 18a and 18b, a thick film forming method such as a screen printing method, a dipping method, a coating method and an electrophoresis method, an ion beam method, a sputtering method, a vacuum deposition, an ion plating method, etc. A thin film forming method such as chemical vapor deposition (CVD) or plating can be used.

By forming the piezoelectric / electrostrain elements 18a and 18b using such a film forming method, the piezoelectric / electrostrain elements 18a and 18b and the thin plate portions 12a and 12b are integrated without using an adhesive. It can be joined and arranged in a specific manner, reliability and reproducibility can be ensured, and integration can be facilitated.

[0093] In this case, it is preferable to form the piezoelectric / electrostrain elements 18a and 18b by the thick film forming method. In particular, if the thick film forming method is used in the formation of the piezoelectric / electrolytic strain layer 22, particles of piezoelectric ceramics having an average particle size of 0.01 to 5 μm, preferably 0.05 to 3 μm, a paste or slurry containing powder as a main component, or a suspension or the like This is because it can be formed into a film using an emulsion, sol, or the like, and good piezoelectric / electrolytic strain characteristics can be obtained by firing the film.

[0094] The electrophoresis method has an advantage that the film can be formed with high density and high shape accuracy. Also, screen printing method, it is possible to the film formation and patterning simultaneously manufacturing it is advantageous to simplify the forming process.

[0095] Specifically, the formation of the piezoelectric / electrostrain elements 18a and 18b will be described. First, the ceramic green laminate 58 is fired at a temperature of 1200 ° C to 1600 ° C and integrated to obtain the ceramic laminate 60, and then the thin plate portions 12a and 12b are placed at predetermined positions on both surfaces of the ceramic laminate 60. The first one electrode 24 is printed and fired, then the piezoelectric / strain layer 22 is printed and fired, and the other electrode 26 paired with the first one electrode 24 is printed and fired. , These are repeated a predetermined number of times (when the piezoelectric / electric strain elements 18a and 18b are composed of the multilayer piezoelectric / electric strain layer 22) to form the piezoelectric / electric strain elements 18a and 18b. Then, terminals 28 and 30 for electrically connecting the electrodes 24 and 26 to the drive circuit are printed and fired.

[0096] Further, the first one electrode 24 of the lowermost layer is printed and fired, and the first other electrode 26 paired with the piezoelectric / electrolytic strain layer 22 and the first one electrode 24 is printed and fired. Then, the piezoelectric / electrolytic strain elements 18a and 18b may be formed by repeating printing and firing in this unit a predetermined number of times.

[0097] Here, platinum (Pt) is used as one electrode 24, lead zirconate titanate (PZT) is used as the piezoelectric / electrolytic strain layer 22, gold (Au) is used as the other electrode 26, and silver is used as terminals 28 and 30. When the material is selected so that the firing temperature of each member becomes lower according to the stacking order, such as (Ag), resintering of the previously fired material does not occur at a certain firing stage, and the electrode material, etc. It is possible to avoid the occurrence of problems such as peeling and aggregation.

[0098] By selecting an appropriate material, it is also possible to sequentially print the members of the piezoelectric / electrostrain elements 18a and 18b and the terminals 28 and 30 and integrally fire them at one time, and the outermost layer. After forming the piezoelectric / electrolytic strain layer 22 of the above, the electrode 26 or the like of the outermost layer can be provided at a low temperature.

[0099] Further, the members and terminals 28 and 30 of the piezoelectric / electrolytic strain elements 18a and 18b may be formed by a thin film forming method such as a sputtering method or a thin film deposition method, and in this case, heat treatment is not always required. do not do.

[0100] In the formation of the piezoelectric / electrolytic strain elements 18a and 18b, the piezoelectric / electrolytic strain elements 18a and 18b are formed in advance on both surfaces of the ceramic green laminate 58, that is, on the respective surfaces of the ceramic green sheets 52A and 52B. It is also preferable to fire the ceramic green laminate 58 and the piezoelectric / strain elements 18a and 18b at the same time. In the simultaneous firing, the ceramic green laminate 58 and all the constituent films of the piezoelectric / electrolytic strain elements 18a and 18b may be fired, and one electrode 24 and the ceramic green laminate 58 may be fired at the same time. Alternatively, a method of simultaneously firing the ceramic green laminate 58 with another constituent film other than the other electrode 26 can be mentioned.

[0101] As a method of simultaneously firing the piezoelectric / electric strain elements 18a and 18b and the ceramic green laminate 58, a precursor of the piezoelectric / electric strain layer 22 is formed by a tape forming method or the like using a slurry raw material, and the precursor is formed. The precursor of the piezoelectric / electrolytic strain layer 22 before firing is laminated on the surface of the ceramic green laminate 58 by thermal pressure bonding or the like, and fired at the same time to form the movable parts 20a and 20b, the thin plate portions 12a and 12b, and the piezoelectric / electric strain layer. A method of manufacturing 22 and the fixing portion 14 at the same time can be mentioned. However, in this method, it is necessary to form the electrode 24 in advance on the surface of the ceramic green laminate 58 and / or on the piezoelectric / strain layer 22 by using the film forming method described above.

[0102] As another method, electrodes 24 and 26, which are constituent layers of the piezoelectric / electrolytic strain elements 18a and 18b, are screen-printed on at least the portions of the ceramic green laminate 58 that will eventually become the thin plate portions 12a and 12b. The piezoelectric / electrolytic strain layer 22 may be formed and fired at the same time.

[0103] The firing temperature of the constituent films of the piezoelectric / electrolytic strain elements 18a and 18b is appropriately determined depending on the constituent materials thereof, but is generally 500 ° C to 1500 ° C, and the piezoelectric / electrolytic strain layer 22. The temperature is preferably 1000 ° C to 1400 ° C. In this case, in order to control the composition of the piezoelectric / strain layer 22, it is preferable to sinter in the presence of an evaporation source of the material of the piezoelectric / strain layer 22. When the piezoelectric / electrolytic strain layer 22 and the ceramic green laminate 58 are fired at the same time, it is necessary to match the firing conditions of both. The piezoelectric / electrostrain elements 18a and 18b are not necessarily formed on both sides of the ceramic laminate 60 or the ceramic green laminate 58, and may of course be only one side.

[0104] Next, among the ceramic laminates 60 on which the piezoelectric / electrostrain elements 18a and 18b are formed, the side portion and the tip portion of the ceramic laminate 60 are cut along the cutting lines C1, C2, and C5. To excise. By this cutting, as shown in FIG. 12, the piezoelectric / electric strain elements 18a and 18b are formed on the ceramic substrate 16, and the piezoelectric / electric parts 20a and 20b having the end faces 34a and 34b facing each other are formed. Obtain the distortion device 10. The cutting timing may be cut along the cutting lines C1 and C2 and then along the cutting line C5, or may be cut along the cutting line C5 and then cut along the cutting lines C1 and C2. .. Of course, these cuttings may be performed at the same time. Further, the end face of the fixing portion 14 facing the cutting line C5 may also be appropriately cut when, for example, the total length of the piezoelectric / electrostrain device is precisely controlled.

[0105] In this manufacturing method, the piezoelectric / electrolytic strain elements 18a and 18b are formed on the ceramic substrate 16 at the same time as the unnecessary portion is cut off from the ceramic laminate 60, and the ceramic substrates 16 have end faces 34a and 34b facing each other. Since the piezoelectric / electrolytic strain device 10 in which the movable portions 20a and 20b are formed can be obtained, the manufacturing process can be simplified and the yield of the piezoelectric / electrolytic strain device 10 can be improved. In this case, it is particularly preferable to arrange a plurality of piezoelectric / electrolytic strain devices 10 in the vertical direction and the horizontal direction on the same substrate and take a large number of them in the same process. As a cutting method, in addition to machining such as dicing and wire sawing, laser machining such as YAG laser and excimer laser and electron beam machining can be applied.

[0106] Further, the ceramic substrate 16 is cut out by combining these processing methods. For example, it is preferable that the cutting lines C1 and C2 (see FIG. 11) are processed by wire sawing, and the end faces of the fixed portion 14 and the movable portions 20a and 20b orthogonal to the cutting lines C1 and C2 are diced.

[0107] By the way, in the above-mentioned manufacturing method of the piezoelectric / strain device 10, since the piezoelectric / strain elements 18a and 18b are formed on the thin plate portions 12a and 12b by integral firing, the piezoelectric generated during firing is formed. Due to the shrinkage of the electrostrain layer 22 and the difference in thermal expansion ratio between the pair of electrodes 24 and 26 and the piezoelectric / electrostrain layer 22 and the thin plate portions 12a and 12b, for example, the thin plate portions 12a and 12b and the piezoelectric / electrostrain element 18a and 18b are slightly displaced toward the hole 42 so as to be convex, and are in a state where the shape is distorted. Piezoelectric / strain elements 18a and 18b (particularly piezoelectric / strain layer 22) and a thin plate Internal residual stress is likely to occur in parts 12a and 12b.

[0108] For the generation of internal residual stress in the thin plate portions 12a and 12b and the piezoelectric / electrolytic strain layer 22, in addition to the above-mentioned integral firing, separate piezoelectric / electrolytic strain elements 18a and 18b are attached to the thin plate portions 12a and 12b. For example, it also occurs when bonding with an adhesive. That is, when the adhesive is fixed or cured, internal residual stress is generated in the thin plate portions 12a and 12b and the piezoelectric / electrolytic strain layer 22 due to the curing shrinkage of the adhesive or the like. Further, when heating is required for the immobilization or curing, the internal residual stress becomes large.

[0109] When the piezoelectric / electric strain device 10 is used in this state, even if a predetermined electric field is applied to the piezoelectric / electric strain layer 22, the movable portions 20a and 20b may not show a desired displacement. This is because the material properties of the piezoelectric / strain layer 22 and the displacement operation of the movable parts 20a and 20b are hindered by the internal residual stress generated in the thin plate portions 12a and 12b and the piezoelectric / strain layer 22. Is.

[0110] Therefore, in this manufacturing method, after the piezoelectric / electrostrain elements 18a and 18b are formed, the periphery of the movable portions 20a and 20b is cut off. By this cutting, end faces 34a and 34b facing each other are formed on the movable portions 20a and 20b, but these end faces 34a and 34b are formed by the internal residual stress generated in the thin plate portions 12a and 12b and the piezoelectric / strain layer 22. Move toward each other, and the widths of the end faces 34a and 34b after the movement become, for example, a second predetermined width W2 shorter than the predetermined width W1. More specifically, the second predetermined width W2 is not exactly parallel and is shorter at the tip.

[0111] The movement of the end faces 34a and 34b is accompanied by the release of the internal residual stress generated in the thin plate portions 12a and 12b and the piezoelectric / strain layer 22. When the piezoelectric / electrostrain device 10 is used with the internal residual stress released, the moving parts 20a and 20b exhibit displacement operations almost as designed and exhibit good device characteristics. This effect is the same when a part of the portion to be the fixed portion 14 is cut off to form end faces 34a and 34b facing each other on the fixed portion 14, and in this case, the thin plate portions 12a and 12b and the piezoelectric portion 14 are formed. / The internal residual stress generated in the electrolytic strain layer 22 is released by the movement of the end faces 34a and 34b formed in the fixed portion 14 and facing each other. Regarding the opposing end faces 34a and 34b, the same effect can be obtained by forming not only the central portion of the movable portion 20a and 20b or the fixed portion 14 but also the portion deviated from the center.

[0112] In the excision shown in FIG. 11, it is preferable to heat-treat at 300 ° C to 800 ° C after the excision. This is because defects such as microcracks are likely to occur in the piezoelectric / electrostrain device 10 due to processing, but the defects can be removed by the heat treatment, and reliability is improved. Further, after the heat treatment, it is preferable to leave it at a temperature of about 80 ° C. for at least 10 hours to perform an aging treatment. This is because the aging treatment can further relieve various stresses and the like received in the manufacturing process and contribute to the improvement of the characteristics.

[Effect of the Invention] As described above, according to the first aspect of the present invention, the thin plate portion and the movable portion.<u style="single">When connecting with and / or</u>The thin plate portion and the fixed portion<u style="single">At the time of connection</u>Due to the presence of the voids in which the filling is placed, even if the thin plate portion undergoes a large displacement due to a large external impact, the stress generated near the boundary line where the thin plate portion and the movable portion or the thin plate portion and the fixed portion are joined is generated. It is dispersed in the voids, eliminating the damage that was conventionally caused by stress concentration, reducing the effect on the basic characteristics of the piezoelectric / electrolytic strain device, and improving the impact resistance of the thin plate.

BRIEF DESCRIPTION OF THE DRAWINGS [FIG. 1] FIG. 1 is a perspective view of a piezoelectric / electrostrictive device.

FIG. 2 is an explanatory diagram showing the operation of a piezoelectric / electrostrictive device.

FIG. 3 is an explanatory view showing another shape of the filling material filled in the void portion.

FIG. 4 is a perspective view of a piezoelectric / electrostrictive device having other voids.

5 is an explanatory view showing another shape of the filling shown in FIG. 4. FIG.

FIG. 6 is a perspective view of a piezoelectric / electrostrictive device having other voids.

FIG. 7 is an explanatory view showing another shape of the filling shown in FIG.

FIG. 8 is a perspective view of a piezoelectric / electrostrictive device having other voids.

FIG. 9 is an explanatory diagram of each green sheet to be laminated.

10 is an explanatory view in which the green sheets of FIG. 9 are laminated.

FIG. 11 is an explanatory view showing a state body before excision in which a piezoelectric layer is formed.

FIG. 12 is an explanatory diagram of a piezoelectric / electrostrain device after excision.

[Explanation of symbols] 10 Piezoelectric / electrostrictive device, 11, 11a , 11b , 12, 12a, 12b Thin plate part, 14 Fixed part, 14a, 14b Void part, 16 . Base, 18a, 18b Piezoelectric / strain element, 19a, 19b Piezoelectric / strain layer, 20a, 20b Movable part, 20c, 20d Void part, 22 Piezoelectric / strain layer, 24,26 Electrodes, 28,30 Terminals, 34a, 34b Mounting surface, 36 Voids, 37 Spacer members, 38 / Adhesives, 40 Substantial drive parts, 42 Holes, 50A ~ 50G, 51A, 51B, 52A, 52B, 102A ~ 102G Ceramic green sheet, 54,100,100a Window part, 58 Ceramic green laminate, 60 Ceramic laminate, C1, C2, C5 ... Cutting line.