JP3024763B2 - Stacked displacement element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an electromechanical transducer used for an actuator of an industrial robot, an ultrasonic motor, and the like. The present invention relates to an improvement of a stacked displacement element in which a plurality of sheets are stacked via an internal electrode to increase a displacement amount.

[Conventional technology]

Conventionally, a laminated piezoelectric element used for a displacement element used for a positioning mechanism of an XY stage, a braking brake, or the like is obtained by providing an electrode on a thin plate made of a piezoelectric ceramic material processed into a predetermined shape and polarizing it. And a method of joining with an organic adhesive directly or via a thin metal. However, when laminated using an adhesive as described above, the adhesive layer absorbs the displacement due to the vibration of the piezoelectric element, or the adhesive deteriorates due to high temperature environment or long-term use depending on the use conditions. There are disadvantages.

For this reason, a multilayer piezoelectric element of a multilayer chip capacitor structure type has recently been put to practical use. That is, as described in JP-B-59-32040, for example, a paste-like piezoelectric ceramic material obtained by adding and kneading a binder to raw material powder is formed into a thin plate having a predetermined thickness, and one side of this thin plate or A conductive material such as silver-palladium is applied to both surfaces to form internal electrodes. A predetermined number of the thin plates are stacked and pressed, processed into a predetermined shape, fired, and then ceramicized, and external electrodes are formed on both side surfaces of the stacked body. The laminated piezoelectric element with the above configuration has excellent adhesion between the thin plate made of the piezoelectric ceramic material and the internal electrode and stable thermal characteristics, so that it can be used sufficiently even in a high-temperature environment and can be used for a long time. , And there is an advantage that deterioration is extremely small.

[Problems to be solved by the invention]

In the multilayer piezoelectric element having the above configuration, in a case where a displacement is obtained by continuously applying a DC high voltage between electrodes as in an electronic component, when a silver-based material is used as an electrode material, a high humidity There is a problem that so-called migration occurs in an atmosphere, and eventually dielectric breakdown occurs. In other words, Ag forming the electrode is an element that is easily oxidized,
It is ionized (Ag +) in a high humidity atmosphere, attracted to the negative electrode by the applied voltage, and deposits on the negative electrode side. Such deposits grow like cedar leaves over time, lowering the insulation resistance between the electrodes and eventually causing a short circuit. As a means to prevent such migration, it is conceivable to form the electrode with a high melting point noble metal material such as Pt or Pd, but it is not preferable because the cost will increase as well as the performance will be improved. . It has also been proposed to cover an exposed portion of an internal electrode formed of a silver-based material with a film made of a metal having a migration property smaller than that of silver (see, for example, JP-A-62-62571). However, the work of covering the exposed portion after forming the laminate is extremely complicated, and cannot always be completely covered with the metal film. For example, it is necessary to allow penetration of external moisture through a pinhole or the like. There are still unsatisfactory points in terms of reliability. In addition to the above, as means for preventing intrusion of moisture in a high-humidity atmosphere, for example, coating means with a coating made of a resin material, means for sealing in a metal container, and the like have been tried. However, even if the coating is made of a resin material, the coating is not necessarily impervious to water impermeability, but also causes small cracks due to the operation of the element, or a slight gap at the boundary with the lead wire. Moisture may invade through the membrane. Further, in the case where the element is sealed in a metal container, not only the displacement of the element is suppressed, but also the whole volume is increased, and the cost is further increased. In any case, it is difficult to completely prevent migration with the above-mentioned conventional configuration, and there is a problem that the life is extremely short.

The present invention solves the above-mentioned problems in the prior art,
It is an object of the present invention to provide a stacked displacement element capable of completely preventing migration without causing a rise in cost.

[Means for solving the problem]

In order to achieve the above object, according to a first aspect of the present invention, a laminate comprising a plurality of thin plates made of an electromechanical conversion material laminated via internal electrodes formed so as to cover most of the thin plates. Is formed, and a pair of external electrodes to be alternately connected to the internal electrodes is provided on the side surface of the laminated body. In the laminated displacement element, the internal electrodes are surrounded around the outer periphery of the internal electrodes. An edge member made of the same electromechanical conversion material as the thin plate is provided integrally with the thin plate to form a non-displaced portion, and the lead portion is formed such that the internal electrode and the external electrode are formed to have a width smaller than the external dimensions of the internal electrode. A technical means is adopted in which the internal electrodes are electrically connected to each other via the edge member of the non-displacement portion so as to cut off the contact between the internal electrode and the outside air.

In the first aspect, the internal electrodes and the lead portions may be formed of a silver-based material, and the external electrodes may be formed of a non-silver-based material.

Further, the internal electrode can be formed of a silver-based material, and the lead portion and the external electrode can be formed of a non-silver-based material.

Further, in the second invention of the present application, in addition to the first invention, a buffer portion is provided between a non-displacement portion formed near the side portion of the laminate and a displacement portion formed inside the laminate. In addition, a technical means was adopted in which the displacement amount in the buffer portion was formed so as to increase sequentially from 0% in the portion in contact with the non-displacement portion to 100% in the portion in contact with the displacement portion.

In the second aspect of the present invention, it is preferable that the ratio of existence of the internal electrode in the buffer portion is sequentially increased from 0% in the non-displacement portion to 100% in the displacement portion.

In the second aspect of the invention, 0 at the site the value of the ratio d / d ₀ between the piezoelectric strain constant d ₀ of the material forming the piezoelectric strain constant d and the thin plate of the material forming the buffer portion, in contact with the non-displaced portion From 1 to 1 at a portion in contact with the displacement portion.

Further fixed in the second invention, the thickness t ₁ becomes insulating layer and the thickness t ₂ becomes the electrode layer on the thin plate forming the buffer portion in this order, t ₁ + t ₂ with respect to the thickness t of the internal electrodes = thereby formed to be t, it may be formed so as to sequentially decrease to zero at the site in contact with the displacement unit from t at the site in contact with the non-displaced portion of the thickness t ₁ of the insulating layer.

Next, in the present invention, it is preferable to use a piezoelectric material or an electrostrictive material as the electromechanical conversion material.

It is effective to use screen printing as a means for providing an internal electrode, an electrode layer and an insulating layer on a thin plate.

(Operation)

With the above configuration, for example, the internal electrode made of a silver-based material can be completely sealed in the laminate and the contact with the outside air can be cut off, so that the intrusion of moisture contained in the outside air into the laminate can be prevented. Can be.

In addition, a buffer is provided between a non-displacement portion formed near the side portion of the laminate and a displacement portion formed inside the laminate, and the displacement in the buffer is changed stepwise or continuously. As a result, an effect of preventing stress concentration due to a sudden change in displacement occurring at the boundary between the non-displacement portion and the displacement portion can be expected.

〔Example〕

FIG. 1 is a front view of an essential part showing a first embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a thin plate which is formed of a piezoelectric ceramic material, for example, into a square shape having a side of 10 mm and a thickness of 100 μm. Reference numeral 2 denotes an internal electrode, which is formed of a conductive material described later and is provided on the surface of the thin plate 1. Next, reference numeral 3 denotes an external electrode formed of a non-silver-based conductive material such as Ni or Pt.
A part of the internal electrode 2 is connected to both sides of a laminated body formed by laminating, for example, 100 thin plates 1 via a lead portion (not shown) every other layer to form a pair.

Next, FIG. 2 is a plan view showing the thin plate 1 in FIG. 1, and FIG. 3 is a sectional view taken along line AA in FIG. In both figures, 1a is an edge member, and 2a is a lead portion. That is, the internal electrode 2 is formed of, for example, a conventionally used silver-palladium alloy, for example, with a side of 9 mm, and the lead portion 2a is integrally provided so as to face the edge of the thin plate 1 or to protrude. Width w ₁ of the lead portion 2a is formed in 1mm, for example. Next, the edge member 1a is made of the same material as that of the thin plate 1 so as to surround the internal electrode 2 outside the internal electrode 2.
It is formed in a frame shape with a width w ₂ = 0.5 mm. Although the edge member 1a is formed to have the same thickness as the internal electrode 2, the edge member 1a and the lead 2
The a and the internal electrode 2 can be provided on the surface of the thin plate 1 by, for example, screen printing means. That is, first, a thin plate 1 having a thickness of 100 μm is formed from a raw material obtained by adding an organic binder, a plasticizer, an organic solvent, and the like to Pb (Zr, Ti) O ₃ powder, for example, by a doctor blade method. Next, a paste made of a silver-palladium alloy is fixed on the surface of the thin plate 1 by screen printing to form the internal electrodes 2 shown in FIGS. 2 and 3. In this case the lead
2a is also formed at the same time. The thickness of the internal electrode 2 and the lead portion 2a is preferably about 3 to 5 μm. Next, an edge member 1a is formed on the peripheral portion of the internal electrode 2 by screen printing. In this case, the internal electrode 2 and the lead portion are formed.
It is advisable to mask part 2a. The order of forming the internal electrode 2, the lead portion 2a, and the edge member 1a may be reversed. After laminating, for example, 100 sheets of the thin plates 1 formed as described above and crimping them, they are fired at 1050 to 1200 ° C. for 1 to 5 hours to obtain a 10 mm square sintered laminate. The external electrodes 3 to be provided on both side surfaces of the sintered laminate are formed by, for example, Ni plating or a combination of Ni and Au plating.

With the above configuration, the internal electrode 2 made of silver-palladium is completely shielded or sealed at the upper and lower surfaces by the thin plate 1 and the peripheral portion by the edge member 1a, so that it is never exposed to the outside air. Therefore, generation of migration peculiar to the silver-based material can be completely prevented.

Further, the internal electrode 2 is formed of silver-palladium, and the lead portion 2a and the external electrode 3 are formed of platinum and Ni plating, that is, non-silver-based material, so that the internal electrode 2 made of silver-based material is completely exposed to the outside air. Therefore, the occurrence of silver migration can be more completely prevented. In this case, the lead 2a made of platinum is a very small area,
Since the amount of expensive platinum used is small, there is no concern about high costs.

Next, the device having the above configuration has an effect that migration can be completely prevented, but has some improvements. That is, as shown in FIGS. 2 and 3, the overlapping portion of the internal electrode 2 forms a displacement portion. However, since the internal electrode 2 does not exist in the portion where the peripheral edge member 1a is provided, a non-displacement portion is formed. It becomes a displacement part, and a large strain is generated at the boundary between them, and the stress is concentrated. For this reason, the thin plate 1 or the whole element may be broken. In some cases, the non-displacement portion hinders the displacement of the displacement portion, and the displacement inherent to the piezoelectric ceramic material cannot be obtained.
In the second invention of the present application, the above points are further improved,
The purpose is to further improve the electromechanical conversion efficiency and reliability. In order to achieve the above object, as described above, a buffer portion described later is provided between a non-displacement portion represented by the edge member 1a and a displacement portion represented by the internal electrode.

By providing the buffer portion, a large strain generated at the boundary between the non-displacement portion and the displacement portion is eliminated, and therefore, the destruction of the thin plate 1 and the entire displacement element due to stress concentration is prevented. That is, in the buffer portion, the displacement is zero at a portion in contact with the non-displacement portion, but the displacement is changed stepwise or continuously until reaching the displacement portion.

FIGS. 4 to 6 are enlarged plan views of essential parts showing an example of forming a buffer in the second embodiment of the present invention, and the same parts are denoted by the same reference numerals as in FIGS. 2 and 3. .
First, in FIG. 4, a buffer portion c is provided between a displacement portion a represented by the internal electrode 2 and a non-displacement portion b represented by the edge member 1a. Reference numeral 21 denotes a partial electrode, which is formed in a plurality of stripes substantially parallel to the edge member 1a, and is formed so that the width of the stripes is gradually reduced from the internal electrode 2 side toward the edge member 1a side. In order for the partial electrode 21 to function as a part of the internal electrode 2, a conductive member 21 a is provided between the partial electrodes 21 and between the partial electrode 21 and the internal electrode 2. In FIG. 4, the internal electrode 2, the partial electrode 21 and the conductive member 21 are shown for easy understanding.
Although a is not a cross section, a is indicated by hatching.

With the above configuration, in the buffer section c provided with the partial electrodes 21, displacements corresponding to the widths of the respective stripes are produced, though not so much as in the displacement sections a provided with the internal electrodes 2, and these displacements are caused by the edge. Since it gradually increases from 0% at the portion contacting the non-displacement portion b where the member 1a is provided, to 100% at the portion contacting the displacement portion a, a buffering effect of the displacement can be expected.

Next, the one shown in FIG. 5 is one in which the partial electrode 21 is formed by a plurality of triangles whose bases are on the side of the internal electrode 2.
In the figure, the partial electrode 21 is formed by a plurality of circles,
The diameter closer to the displacement portion a is larger and the diameter closer to the non-displacement portion b is smaller, and both have the same displacement buffering action as that shown in FIG.

Next, the thin plates provided with the partial electrodes 21 as described above were laminated in the same manner as in the above-described embodiment to obtain a laminated displacement element as shown in FIG. The partial electrodes 21 and the conductive members 21a shown in FIGS. 4 and 5 can be printed simultaneously with the internal electrodes 2 by, for example, screen printing.

200 to 40 for the laminated displacement element manufactured as above
A voltage of 0 V was applied for 10 minutes to perform polarization processing, and the characteristics were measured. 7 and 8 are diagrams showing the relationship between the amount of displacement, the applied voltage, and the number of times of driving, respectively. As a comparative example, the same piezoelectric ceramic sheet material as described above was used, and a laminated displacement element having a configuration lacking the partial electrode 21 or the buffer portion c shown in FIGS. 4 to 6 was manufactured. As is clear from FIGS. 7 and 8, A for the present example has a displacement of 20 to 30% larger for the same applied voltage and B for the same applied voltage as compared to B for the comparative example. That is, it is recognized that the life is also significantly improved. Note B ₁ in FIG. 8 is a life end point due to dielectric breakdown occurred.

Next, FIGS. 9 and 10 are enlarged plan views of essential parts showing a third embodiment of the present invention, and the same parts are denoted by the same reference numerals as in FIGS. 4 to 6. First, in FIG. 9, reference numeral 7 denotes a hole, and a plurality of holes are provided on the internal electrode 2 on the thin plate 1 in the region of the buffer portion c. The number of non-displacement portions b is larger than that of the displacement portions a. Arrange to increase.
In this case, the internal electrodes 2 are not cross-sectionally illustrated but hatched for easy understanding. In FIG. 9, the diameter of the hole 7 is formed to be the same, and the installation interval is different between the displacement part a side and the non-displacement part b side. Next
In the embodiment shown in FIG. 10, the diameter of the holes 7 provided in the internal electrode 2 on the thin plate 1 in the region of the buffer portion c is formed differently, and the installation intervals are the same, but the holes 7 on the non-displacement portion b side are formed. Has a larger diameter than that of the displacement portion a. 9 and 10 may be formed in combination. In order to form the internal electrode 2 having the above structure, the same screen printing means of silver-palladium paste as in the above embodiment can be applied. In this case, masking corresponding to the holes 7 is previously formed on the screen. You should keep it.

According to the above configuration, in the buffer section c, the existence ratio of the internal electrodes 2 on the thin plate 1 sequentially increases from 0% in the non-displacement section b to 100% in the displacement section a.
Is a displacement amount corresponding to the existence ratio of the internal electrode 2, and gradually increases from 0 in the non-displacement portion b to the maximum displacement amount in the displacement portion a. Therefore, a displacement buffering effect similar to that of the above-described embodiment can be expected, the displacement amount of the entire displacement element can be increased, and the number of driving times and the life can be greatly improved.

FIG. 11 is an enlarged plan view of a main part showing a fourth embodiment of the present invention, and the same portions are denoted by the same reference numerals as those in the above embodiment. Eleventh
In the drawing, a non-displacement portion b is formed by a thin plate 11 and a buffer portion c is formed by thin plates 12 to 14, which are integrally fixed to the thin plate 1 constituting the displacement portion a, and an internal electrode (shown in FIG. Is provided. The thin plates 11 to 14 are not cross sections, but are hatched for easy understanding. Note that the piezoelectric strain constants of the thin plates 1 and 11 to 14 were respectively set to d ₀ and
When d _{11 to} d ₁₄ , d ₁₁ ≒ 0 and d ₁₂ <d ₁₃ <d ₁₄ <d ₀
It is formed of materials having different compositions so that Generally, when the buffer portion c is formed of n thin plates 12 to (11 + n), d ₁₁ <d ₁₂ <... <D _{11 + n} <d ₀ . Therefore, the larger the value of n, the smaller the difference between the piezoelectric strain constants of adjacent thin plate constituent materials. The thin plate 1 having such a configuration
In order to form 11 to 14, for example, after forming a laminate having a thickness corresponding to the width of the thin plates 11 to 14, the laminate is sliced in parallel with the end face of the laminate to a size corresponding to the thickness of the thin plate 1, Thin plate 1
By pressing in the thickness direction together with the above, they can be integrated as shown in FIG.

FIGS. 12 (a) and 12 (b) are plan views showing examples of means for forming the buffer portion c having the structure shown in FIG. That is, a laminated body of the thin plates 11 to 14 is formed as described above, and sliced into a dimension corresponding to the thickness of the thin plate 1 in parallel with the end face of the laminated body, and the short side portion is formed as shown in FIG. Is cut into 45 ° to form a trapezoidal buffer piece 10. Next, as shown in FIG. 12 (b), the buffer pieces are attached to the four sides of the thin plate 1 forming the displacement portion.
10 can be arranged, surrounded in a frame shape, and integrated by press working or the like. After forming the laminated body of the thin plates 11 to 14, the buffering pieces 10 as shown in FIG. 12 (a) are formed without slicing, and the buffering pieces 10 are formed on the four side surfaces of the block-shaped thin plate material 10a. The slice may be sliced in a crimped state.

FIG. 13 is a plan view showing another example of the means for forming the buffer section c having the structure shown in FIG. In FIG. 13, the thin plates 11 to 14 formed in a frame shape are sequentially arranged around the thin plate 1 on which a displacement portion is to be formed, and then integrated by pressing in the thickness direction by press working or the like.

After the thin plates 1 and 11 to 14 are integrally formed as described above, an internal electrode (not shown) is fixed on the displacement portion a and the buffer portion c, and laminated as in the above-described embodiment.

With the above configuration, in the buffer section c, each thin plate
12-14 cause displacement amount corresponding to the piezoelectric strain constant d ₁₂ to d ₁₄ of the material constituting the can increase sequentially displacement from 0 in the non-displacement portion b to the maximum value of the displacement portion a.
Therefore, it is possible to expect the same displacement buffering effect as in the above-described embodiment and the accompanying effect.

Next, FIG. 14 is an enlarged sectional view of a main part showing a fifth embodiment of the present invention. In FIG. 14, reference numeral 8 denotes an insulating layer, which is fixed on the thin plate 1 forming the non-displacement portion b and the buffer portion c, and a part of the internal electrode 2 is laminated on the insulating layer 8 in the buffer portion c. . Note that the thicknesses t ₁ and t ₂ of the insulating layer 8 and the internal electrode 2 in the buffer section c are formed such that t ₁ + t ₂ = t in relation to the thickness t of the internal electrode 2 in the displacement section a. together, from t at a portion contacting a thickness t ₁ of the insulating layer 8 and the undisplaced portion b, it is formed to sequentially decreases continuously to zero at the portion contacting with the displacement unit a. In this case above
The change in t ₁ may be changed stepwise or discontinuously.

With the above configuration, since the insulating layer 8 having the thickness t ₁ exists in the buffer section c, the driving voltage applied to the thin plate 1 becomes smaller than the value at the displacement section a, and the driving voltage at the portion in contact with the non-displacement section b It increases sequentially or stepwise from 0 to the maximum value at the part in contact with the displacement part a. Therefore, since the displacement also changes in proportion to the drive voltage, the same effect of buffering the displacement as in the above embodiment and the accompanying effect can be expected.

In this embodiment, the case where the planar outer contour shape of the thin plate and the internal electrode is a square is shown, but a circular shape other than a square, a rectangle, and other geometric shapes can be arbitrarily selected. As the electromechanical conversion material for forming the thin plate, not only the piezoelectric ceramic material such as lead zirconate titanate shown in this embodiment, but also other piezoelectric materials as well as the Curie temperature lower than room temperature, The same effect as described above can also be expected for a stacked displacement element using an electrostrictive material having a feature that there is no need for the displacement and that the displacement amount is large and the hysteresis is small. As such an electrostrictive material, for example, (Pb _0.916 La _0.084 )
(Zr _0.65 Ti _0.35 ) _0.979 O ₃ , (Pb _0.85 Sr _0.15 ) (Zr
_0.51 Ti _0.34 Zn _0.0125 Ni _0.0375 Nb _0.10 ) O ₃ , (Pb _0.85 Sr _0.15 ) (Zr _0.50 Ti _0.30 Zn _0.05 Ni _0.05 Nb
_0.10 ) O ₃ etc. can be used. In this embodiment,
For example, in the second embodiment, stripes, triangles, and circles are shown as configuration examples of partial electrodes constituting a part of the internal electrodes.
In the third embodiment, circular holes are shown as the shapes of the holes provided in the internal electrodes. However, the present invention is not limited to these shapes, and other arbitrary shapes can be selected. In other words, the existence ratio of the internal electrode (including the partial electrode) in the buffer portion is changed from 0% in the non-displacement portion to the displacement ratio in the displacement portion.
What is necessary is just to form so that it may increase to 100% sequentially. Also, an example in which a screen printing method is used as a means for forming a partial electrode and an internal electrode has been described, but is not limited thereto.
The effect is the same by other means such as plating, vapor deposition, coating and the like. Further, as a material for forming the lead portion for electrically connecting the internal electrode and the external electrode and the external electrode, Au,
One or more of Pt, Pd, Ir, Rh, Os, and Ru, or an alloy thereof can be used. Although an example in which a pair of external electrodes is provided on the opposing surface of the laminate has been described, they may be provided on adjacent surfaces, respectively, or a pair may be provided on one side surface.

〔The invention's effect〕

Since the present invention has the configuration and operation as described above, the internal electrode made of a silver-based material can be completely sealed, and migration can be completely prevented. Further, since the buffer portion is formed between the non-displacement portion and the displacement portion, it is possible to eliminate the occurrence of cracks or the like due to an increase in strain or stress concentration, which has the effect of greatly improving reliability.

[Brief description of the drawings]

FIG. 1 is a front view of an essential part showing a first embodiment of the present invention, FIG. 2 is a plan view showing a thin plate in FIG. 1, FIG. 3 is a sectional view taken along line AA in FIG. 6 to 6 are enlarged plan views of a main part showing an example of forming a buffer in the second embodiment of the present invention, and FIGS. 7 and 8 show the relationship between the amount of displacement, the applied voltage and the number of times of driving, respectively. FIG. 9, FIG. 9 and FIG. 10 are enlarged plan views of essential parts showing a third embodiment of the present invention, FIG. 11 is an enlarged plan view of essential parts showing a fourth embodiment of the present invention, and FIG. (B) is a plan view showing an example of the buffer section forming means having the configuration shown in FIG. 11, and FIG. 13 is a plan view showing another example of the buffer section forming means having the configuration shown in FIG. FIG. 14 is an enlarged sectional view of a main part showing a fifth embodiment of the present invention. 1, 11-14: thin plate, 1a: edge member, 2: internal electrode, 7: hole, 8: insulating layer,
a: displacement part, b: non-displacement part, c: buffer part.

Claims (7)

(57) [Claims] 1. A laminated body is formed by laminating a plurality of thin plates made of an electromechanical conversion material via internal electrodes formed so as to cover most of the thin plates, and forming a laminated body on a side surface of the laminated body. In a laminated displacement element having a pair of external electrodes to be alternately connected to electrodes every other layer, an edge made of the same electromechanical conversion material as a thin plate is provided outside the peripheral edge of the internal electrode so as to surround the internal electrode. The member is provided integrally with the thin plate to form a non-displacement portion, and the internal electrode and the external electrode are electrically connected to each other via a lead portion formed to have a width smaller than the external dimension of the internal electrode, Wherein the contact between the internal electrode and the outside air is cut off via the edge member. 2. The multilayer displacement element according to claim 1, wherein the internal electrodes and the lead portions are formed of a silver-based material, and the external electrodes are formed of a non-silver-based material. 3. The multilayer displacement element according to claim 1, wherein the internal electrodes are formed of a silver-based material, and the lead portions and the external electrodes are formed of a non-silver-based material. 4. A buffer portion is provided between a non-displacement portion formed near a side surface portion of the laminate and a displacement portion formed inside the laminate, and a displacement amount in the buffer portion comes in contact with the non-displacement portion. 0% at the part to 100 at the part in contact with the displacement part
%. The laminated displacement element according to claim 1, wherein the displacement element is formed so as to increase sequentially to%. 5. The multilayer displacement element according to claim 4, wherein the existence ratio of the internal electrodes in the buffer portion is formed so as to increase sequentially from 0% in the non-displacement portion to 100% in the displacement portion. 6. The displacement unit value of the ratio d / d ₀ between the piezoelectric strain constant d ₀ of the material forming the piezoelectric strain constant d and the thin plate of the material forming the buffer portion, from 0 in the portion contacting with the non-displaced portion 5. The stacked displacement element according to claim 4, wherein the stacked displacement element is formed so as to sequentially increase to 1 at a portion in contact with. 7. An insulating layer having a thickness of t ₁ and an electrode layer having a thickness of t ₂ are fixed in this order on a thin plate forming a buffer portion, and t ₁ + t ₂ = t with respect to the thickness t of the internal electrode. While forming so that
The thickness claim (4) of the formed so as to sequentially decrease the t ₁ to t in the portion contacting with the non-displaced portion to 0 in the portion contacting with the displacement unit multilayer displacement element according insulating layer.