CA1206193A - Multilayer electrostrictive element which withstands repeated application of pulses - Google Patents
Multilayer electrostrictive element which withstands repeated application of pulsesInfo
- Publication number
- CA1206193A CA1206193A CA000427828A CA427828A CA1206193A CA 1206193 A CA1206193 A CA 1206193A CA 000427828 A CA000427828 A CA 000427828A CA 427828 A CA427828 A CA 427828A CA 1206193 A CA1206193 A CA 1206193A
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- Prior art keywords
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- electrostrictive
- portions
- internal electrodes
- stack
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Classifications
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N30/00—Piezoelectric or electrostrictive devices
- H10N30/80—Constructional details
- H10N30/87—Electrodes or interconnections, e.g. leads or terminals
- H10N30/871—Single-layered electrodes of multilayer piezoelectric or electrostrictive devices, e.g. internal electrodes
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N30/00—Piezoelectric or electrostrictive devices
- H10N30/80—Constructional details
- H10N30/87—Electrodes or interconnections, e.g. leads or terminals
- H10N30/872—Connection electrodes of multilayer piezoelectric or electrostrictive devices, e.g. external electrodes
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N30/00—Piezoelectric or electrostrictive devices
- H10N30/80—Constructional details
- H10N30/87—Electrodes or interconnections, e.g. leads or terminals
- H10N30/872—Connection electrodes of multilayer piezoelectric or electrostrictive devices, e.g. external electrodes
- H10N30/874—Connection electrodes of multilayer piezoelectric or electrostrictive devices, e.g. external electrodes embedded within piezoelectric or electrostrictive material, e.g. via connections
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N30/00—Piezoelectric or electrostrictive devices
- H10N30/80—Constructional details
- H10N30/87—Electrodes or interconnections, e.g. leads or terminals
- H10N30/877—Conductive materials
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N30/00—Piezoelectric or electrostrictive devices
- H10N30/80—Constructional details
- H10N30/87—Electrodes or interconnections, e.g. leads or terminals
- H10N30/877—Conductive materials
- H10N30/878—Conductive materials the principal material being non-metallic, e.g. oxide or carbon based
Abstract
Abstract of the Disclosure:
In a multilayer electrostrictive element wherein electrostric-tive sections (31) are defined by internal electrodes (32) in a stack having a peripheral surface which has a predetermined outline perpendicularly of an axis of the stack, each internal electrode is given an outline which is approximately congruent with the predetermined outline. In order that external electrodes (33, 34) may readily be connected to the internal electrodes grouped into two, each internal electrode may have a peripheral end which is partly recessed from the predetermined outline, Alternatively, the internal electrodes of each group may be connected together by a conductor rod which passes through the electrostrictive sections, For a great number of internal electrodes, an element may be manufactured by laminating conductive-paste-printed green sheets transversely of the stack axis and then sintering the lamination, Each internal electrode may include a ceramic material, such as an electrostrictive material of the electrostrictive sections, another electrostrictive material of a lower sintering temperature, or glass,
In a multilayer electrostrictive element wherein electrostric-tive sections (31) are defined by internal electrodes (32) in a stack having a peripheral surface which has a predetermined outline perpendicularly of an axis of the stack, each internal electrode is given an outline which is approximately congruent with the predetermined outline. In order that external electrodes (33, 34) may readily be connected to the internal electrodes grouped into two, each internal electrode may have a peripheral end which is partly recessed from the predetermined outline, Alternatively, the internal electrodes of each group may be connected together by a conductor rod which passes through the electrostrictive sections, For a great number of internal electrodes, an element may be manufactured by laminating conductive-paste-printed green sheets transversely of the stack axis and then sintering the lamination, Each internal electrode may include a ceramic material, such as an electrostrictive material of the electrostrictive sections, another electrostrictive material of a lower sintering temperature, or glass,
Description
MULTILAYER ELECTROSTRICTIVE EIEMENT WHICH
WITHSTANDS REPEATED APPLICATION OF PULSES
Background of the Inventlont This inYention relates to an electrostrictive element or transducer of a multilayer structure ~hich is generally called a ~tacked chlp or ceramic capacit~r structure in the art, An electrostrtictive element acco~ding to this invention i8 apecifically useful in, among others, a prlnter head of an ~mpact printer or a relay, As described in a report contributed by Roderic Beresfo~d to "Electronics," November 3, 1981, pages 39 and 40, undPr the title of "Piezoelectric bsnder actuates tiny relays and dot-matrix prlnters," an electrostrictlve element is useful as a printer head, a rel~y, or the like. An electrostrictive element is actuated by a d.c, voltage repeatedly supplled thereto a ltage pul~e~
~hen used ln such field~ of application~.~ The element ~ust withstand ~15 repested applicatlon of suGh voltage pulse~. In other ~o~ds, the element mu~t have a long life e~en ~he~ a great number o~
voltaee pulses are applied thereto. Furthermore, it is de~irable tha~ the element ~hould g~e~rise to a great displacement, An~electxo6tr10tlve ele~ent of a s1mplest typs compri~es " . ~
; 20 an electro~trictlve piece of a~ electro6triotive ~aterial capable : ~ ~ of exh~bitlng a strong electrostrictive effect, m e piece ha6 a palr ~f electrodes ~9n the princlpal 0urfac0~. ~hen a d.c, voltage i8 suyplled be~een *he electrode~ to produce an electric :
: field in the piece, th~ plece elon~ate6 and contr~cts ln the , ~ . ~,, ~Z~ 3 direction of the electric field and transversely thersof, re~pective-ly. Such deformations or strains in the direction of the alectric field and in the tranæverse direction are called the longitudinal and the tran~verse electrostrict~ve effects. It i6 kno~n that the logltudinal electrostrictive effect or~inally giYes ri~e to twice to three time~ as great a deformation as the transverse electro~tricti~e effect, The longitudinal electrostricti~e effsct thexefore pro~ides a higher efficiency of conver~ion fro~ electric energy to mechanical energy. m e deformation in the longitudinal or the trans~erse direction depend6 on the field ~ntensit~y of the electric field produced in the electro~trictlve plece.
~ hen the transverse electrostricti~e effect is used, it is possible with a certain applied voltage to achieYe a displace-ment in the transverse direction in proportion to the dimension which the electrostrlctive piece ha~ in the transverRe direction.
~hen the longitudinal electrostrictive effect 18 ussd in order to use the higher efficiency of energy conversion, the displacement in the logitudinal direction does not grow for a giYen voltage ~ith an increase in the dimens~on which thë ple~e has in the longitudinal direction, Thl~ iB becau6e the field intensity becom0~ weak with the increased longitudinal dimension. It i6 therefore necessary on attaining a great dl~placement with the longitudinal electro~trictive effect to raise the applied voltage so as to strengthen the field inken~ity. ~ po~er souroe for a h~gh voltage iB, ho~ever, bulky and expensiVQ. Furthermore, a high voltage i8 objectionable in Yie~ of the danger inevitable during operation of the electrostrictive element 1nd also in view of the ~thstanding voltage of IC'~ which are u~ed in a driving circuit for the element, The element is tharefore gi~en the multilayer structu~e when the longitudinal eIectrostrictive effect is resorted to.
As will later be described in detail Hith reference to t~o of nearly ~hlrty figures of the accompanying dra~lng, a multilayer electrostrictive element comprises a plurality of electro~trictlve ~ection~ defined in a stack or lamination by a plurality of internal electrode~ which are perpendlcular *o an axi6 of the stack, The stack has a peripheral su~face which hae a predete~mined outline perpendicularly of the axis, For uee in a printer head or a relay, lt is p~eerred that the predeter-mined outline be four ~ides of a rectangle. A flrst external electrode is connected to alternate one6 of the internal electrodes and placed externally of the peripheral surface, A second external electrode ls onnected to others of tlle internal electrodes and pos~tioned externally of the periphe~al sur~`ace, At least one of the first and the second external electrodes ~ay be extended ln contact with the peripheral surface.` E~en ~n thi~ event, it is posslbe to understand that the ext~rnal electrode or electrodes are situated externally of the peripheral surface, With a multilayer electrostricti~e element, a ~reat displacement is achieYed at a 10N voltage even by ths u~e of the longitudinal electrostrictive e~fect. It is to be noted here that each lnternal electrode has an internal electrode outline which i~ po~itioned only partly on the peripheral surface for connection to the flrst or the second external electrode, In other words, each internal electrode has a~ internal electrode area whl¢h iB conslderably narroHar than a cros~-sectional arfls of the stack. As will later be discussed with reference to several figures of the accompanying drawing, it has now been con-firmed that this results in a short life which the electrostric-tive element has when repeatedly supplied with voltage pulses.
Moreover, this restricts the displacement small as compared with the displacement which is theoretically attainable.
Summar~ of__he Invention It is therefore an object of the presen-t invention to provide a multilayer electrostrictive element which has a long life even when voltage pulses are repeatedly applied to repeatedly drive the element.
It is another object of this invention -to provide an electrostrictive element of the type described, which provides a greater displacement as compared with that achieved by conventional electrostrictive elements.
Other objects of this invention will become clear as the description proceedsO
The present invention provides a multilayer electro-strictive element for dimensionally changing in a first direction in response to electrical pulses and for withstanding repeated application of said pulses, said element comprising: a stack for-med by a plurality of electrostrictive sections of an electro-strictive material and a plurality of internal electrodes sandwiched between said electrostrictive sectionsl said stack having a peri-pheral surface defining a cross-sectional area of said stack, each of said internal electrodes having peripheral ends on said peri-fS~
pheral surface and each of said internal electrodes having aninternal electrode area which is substantially equal to a cross-sectional area of said stack, first means for electrically connec-ting alternate ones of said internal electrodes together without connecting others of said internal electrodes, said first means including first insulating layer portions on a first area of said peripheral surface for covering respective peripheral ends of said others of said internal electrodes while leaving portions of said first area uncovered, each said first insulating layer por-tion covering the peripheral end of a respective internal elec-trode while extending in said firs-t direction substantially less than the entire distance between said respective first electrode and either adjacent first electrode to leave uncovered substan-tial portions of the surfaces of said electrostrictive sections in said first area of said peripheral surface, and a first conduc-tive layer continuously formed on both said first insulating layer portlons and on said uncovered portions of said first area; and second means for electrically connec-~ing said others of said internal electrodes together, said second means including insula-ting layer portions on a second area of said peripheral surfacefor covering respective peripheral ends of said alternate ones of said internal electrodes while leaving por-tions of said second area uncovered, and a second conductive layer continuously formed on both said second insulating layer portions and on said uncovered portions of said second area.
The invention will now be described in greater detail with reference to the accompanying drawings, in which:
-5a-Fig. 1 is a schematic longitudinal sectional vieT~J of a conventional electrostrictive element;
Fig. 2 is a top view of the electrostrictive element illustrated in Fig. 1:
Fig. 3 is a schemat-cal longitudinal sectional view of an electrostrictive element according to a first embodiment of the instant invention;
Fig. 4 is a top view of the electrostrictive element depicted in FigO 3;
Fig. 5 shows the life for conventional electrostrictive elements and for electrostrictive elements of the type shown in Figs. 3 and 4;
Fig. 6 shows the displacement a-ttained by the electro-strictive elements mentioned in connection with Fig. 5;
Fig. 7 schematically and partially shows a perspectively exploded view of an electrostrictive element according to a second ,.~
embodiment of this inYention~
-- Fig. 8 i6 a top view of the electrostrictlYe element illustrated in Fig, 7~
Fig, 9 schematically and partially sho~^ a perspectively explsded view of an electrostrictive element according to a modifica-tion of the element depicted in Figs, 7 a~d 8~
Fig. 10 i8 a top view of an electrostrictive elsment according to another mGdiflca*ion of the element illu~trated 1n Figs, 7 and 8~
Fig, 11 1~ a schematic top vie~ of an electrostricti~e element according to a third emboli~ent of this invention~
Fig. 12 shows the life ~or conventional electrostrictive elements and for electrostrictive elements of the structure depicted in Fig, 11;
Fig. 13 sho~s the displacement achieved by the elements mentioned in conjunction with Fig. 12;
Fig. 14 is a schematlc longitudinal sectional view of an electrostrictive element accordin~ to~a `fourth embodiment of this invention; ` `~
Fig. 15 iB a schematic top view of a green ~heet piece for u8e in manufacturing the element shown in Fig. 14~
P~g. 16 i5 a schematical longitudinal sectional ~iew of an electrostrictive element according to a flfth embadiment Gf this inYention~
Fig, 17 1~ a top view of the ele~ent illustrated in Fig, 16~
Fig, 18 as a schemat~c top vie~ of a gresn sheet piece ', for uae in ~a~u~acturing the element of the type depicted ln Figs, 16 and 17~
Fig. 19 is a schematic side vie~ of an electrostrictive element acco~ding to a sixth embodiment of this invention;
Fig, 20 shows the life for conventional electrostricti~e elements and for electrostrict~e elementa of the ty~e de~icted in Fig. 19 Fig, 21 sho~6 the displacement achieved by the element~
msntioned in conjunction wlth Fig, 20 Fig, 22 is a schematical longitudlnal sectional Y~e~
of an electrostrictive element accord~ng to a seventh embodiment of thi~ inventlons Fig, 2~ is a schematical longitudinal sectional view of an electrostrictive element according to an eighth embodiment of this invention;
Fig. 24, drawn on the righthand side of Fig, 18 merely for convenience of illustration; is a schematic perspective vlew of an electrostrictive element according to a n1nth e~bodiment of this invention~ ; ; ;
Fig, 25 shows the life for ele~trostrictiYe element~
according to a tenth embodiment of this invention~
Fig, 26 shows the displacement attained by the elements mentioned in connection with Fig, 25t Fig, 27 shows the life for electrostrictive elements accordin~ to an eleventh emb~diment of thls inventlon and ~or the elements mentloned in connection ~i*h Flgs. 25 and 26;
Fi~. 28 shows the life for electrostrictive element3 according to a twelfth embodiment of this invention and '~2(3~
Fig. 29 shows the displacement achieved-by the elements mentioned ln conjunction ~ith Fig. 28, D scription of the Preferred Embodiments~
Referring to Figs, 1 and 2, a con~entional ~ultilayer electro~tricti~e elament or transducer ~ill be described at first in order to facilitate an understanding of the present invention.
The element co~prises a stack or lamination of a plurality of ~lectro6trictive section~ or segments 31 of an electrostrict~ve material capable of exhib~ting a strong electrostrietive effect.
The electrostrictlve section~ 31 are defined in the stack by a plurality of internal electrodes 32 which are indicated by thick lines and are disposed perpendicular to an axis of the stack with a predetermined spacing, Althou~h called "internal electrodes," the electrodes 32 may be placed on one or both of the top and the bottom surfaces of the stac~. The stack has a peripheral surface of a cross ~sction which is encloded ~ith or contained ~y a predetermined outllne. In the example being illustrated, the predetermined outline-cons~st~ of four side~
. ~, . .
of a rectangle. The peripheral surfac~ ha~ the predetermined outline throughout the stack, It is possible to render the predeter-mined ~pacing as small as several micron~, As seen fr~m Fig~, 1 and 2, each lnternal electrode 32 ha~ an end on the peripheral sur~ace. More particularly, alternate ones of the internal electrsdes 32 have their respectlve 27 end~ on one of four side 6urfaces of the ~tack. Othe~R of the internal electrodes 32 have the ends on an opposin~ side sur~aca of the ~tack as outlined by dashed lines ln Fig, 2, A first external electrode 33 is for~ed on the fir6t-mentioned side sur~ace .; .
ln contact with the ends of the alternate ones of the internal electrodes 32, A second external electrode 34 i3 ~ormed on the opposing side surface in contact ~ith the ends of the others of the intPrnal electrodes 32. First and second electrode ter~inals 36 and 37 are connected to the first and the second external electrodes 33 and 34, respectively.
~ hen a d.c. ~oltaee is supplied bet~een the electrode terminals 36 and 37, electric fields are produced in the respecti~e electrostrictiva section~ 31, The electrostricti~e element elongates axially of the stack, ~hen the d.c, Yoltage is repeatedly applied to the element a great num~er of time~ or repetitions as ~oltage pulseæ, the element is mechanically damaged particularly ~f the voltage i~ raised to achieve a great displacement. Furthermore, the elongation or displacement of the element is appreciably sm~ll as compared with the elongation which would theoretically be attained, As ~ill later be evidenced by various exa~ples in comparison with references, it has now been confirmed ~h~t such-defects of a conventional electrostrictive elemeht result from the fact that an area on which the internal electroaes 32 are superposed, is considerably narrower than a cross-sectional area of the stack, More specifically, the electric field is produced in each electrostric-tive section 31 su~stantially only at a centxal portion between the oppo ing internal electrodes 32, The electric field is weak at a peripheral portlon surrounding the central portlon. The elongation therefore takes place at such central portions of the respective electrostrictiYe s~ctions 31 and hardly occurs at the peripheral portions. m e elongation of the element as 3 whole is consequently advers01y affscted by the peripheral portions. Moreover, concentration of the stress takes place along the boundary bet~een the central and the peripheral portions, This results cracks or other machanlcal damage when a large number of voltage pulses are applied to the element.
Referring now to Figs. 3 and 4, an electrostrictive element according to a first embodiment of this invention comprises similar parts designated by like reference numerals. Each internal electrode 32, however, has a peripheral end of an inter~al electrode outline congruent w~th the predetermined outline which the peripheral surface of the stack has perpendicularly of the stack axis.
The peripheral ends of the respective internal electrodes 32 are positioned on the periphPral surface. Furthermore, each internal electrode 32 has an internal electrode area whioh is equal to the cross-sectional area of the stack. The first external electrode 33 ls positioned externally of the peripheral surface and is brought into contact with the peripheral ends of the alternate ones of the internal electrodes 32, The second external electrode 3~ is laid outwardly of the peripheral sUrface and connected to the peripheral ends of the other internal electr~des.
A~ Example I, electrostrictîve elements of the structure illustrated with refsrence to Figs. 3 and 4, ~ere manufactured as follows. At first, a slurry was prepared by suspending a mixture of presintered powder of a solid solution of lead ~agne~ium niobate Pb(Mgl~3Nb2~2)03 and lead tltanete PbTiO3 in a mol ratio of 9 to 1 and an organic binder, in an organic ~olvent i~ the manner kno~n in the art, The presintering ~a~ carried out at 800C for two hours, It is known that a sintered piece of the solid solution exhibits a strong electrostrictive effectO The slurry w~s applied onto a polyester film kno~n as a Mylar film by the doctor blade method to a thickness of several hundreds of microns ahd then dried, A green sheet thus formed, Nas pealed off the polyester film and subsequently cut into green sheet pieces of a predetermined size. Platinum paste was printed to form a platinum pa~te layer on a surface of each green sheet piece, The green sheet pieces with the prlnted platinu~ paste layers, were stacked, rendered integral in a hot pre3s, machined to predetermined dlmensions to expose the peripheral ends of the respective platinum paste layexs on the peripheral surface of each integral stack, and subsequently sintered at about 1200C
for one hour. The green sheet pieces became the electrostricti~e sections 31 (Fig. 3). Fired layers of the platinum paste became the internal electrodes 32.
Having been machined to the predetermined dimension~, each integral ~tack had a square cross section of 3 mm by 3 mm and a height of 10 mm. The spacing betweén~two adJacent-ones of the internal electrodes 32 was 250 microns. Lead wire~ were soldered to the peripheral ends o~ the respective 1nternal electrodes 32 so as to serve as the first and the second external electrodes 33 and 34 and ~o that a pair of ends of the respective lead wires serve as the *irst and the second electrode terminals 36 and 37.
As Reference I, electrostrictiYe elements of the con~ention-al structure illustrated w1th refererlce to F~gs, 1 and 2, were likewi6e manufactured, An area on ~hich the internal electrodes 32 were superpo6ed, W3S 84~/o of the cross-sectional area of 3~
the stack. ~e external electrodes 33 and 34,were for~ed by applying silver paste onto the side surfaces and then firing the paste, Turning now to Figo 5, a pulse sequence ~as continuously applied to each of the electrostrictive elements of Example I
and of ~eference I. Each pulse w2s a half of a sinusoidal ~ave of an amplitude of 250 volts, Each pulse had a pulse ~idth of 1 millisecond. As shown by an upper line 41, the elements of Example I showed a maximum d~splacement sf 4,1 microns. A lo~er curve 42 represents that the elements of Reference I sho~ed a maximum displacement of only 1,3 mic~on~. Each element of Example I ~as not damaged or broken even when the pulses were applied one hundred million times or repetitions as shown by the upper line 41. Each element of Reference I ~as damaged as indicated by a cross ~hen the pulses ~ere applied about twenty-five thousand times.
Turning further to Fig. 6, a d.c. voltage was applied to each of the electrostrictive elements o~ Example I and,of Reference I, Displacements were measured with the voltage varied, As is clear from upper and lower curves 43 and 44 for the elements of Example I and of Reference I, respectiYely, the elements of Example I showed twice to three tlmes as great a displacement as the elements of Reference X at a given voltage (and consequently at a given ~ield intensity).
Referring to Figs, 7 and 8, an electrostrictiYe element according to a second embodiment of this invention comprises similar parts designated by like reference numerals. Somewhat dlfferent fro~ the internal electrodes 32 described in con~junction ~ith Figs. 3 and 4, each internal electrode 32 has a peripheral e~d of an internal electrode outline which is approxi~ately congruent ~ith the predetermined outline of the stack, Each internal electrGde 32 has an internal electrode area which is a little narro~er 5 than the cross-sectional area of the stack, A* any rate, the internal electrode outlines of the respective internal electrode~
~2 are congruent with one another, More particularly, the peripher~l end of each internal electrode 32 comprises a first and ~ second peripheral part, The first peripheral par~, as herein called, is congruent with the predetermined outline except for the second peripheral part. The first peripheral parts of the respective internal electrodes 32 are situ~ted on the peripheral surface.
m e second peripheral parts of alternate ones of the ~nternal electrodes 32 are positioned in the stack so as to define a first area 46 on the peripheral surface, The second peripheral parts of others of the i~ternal electrodes 32 likew~se define a second area 47 on the peripheral surface, In the example beingillustrated, the predetermined outline again consis~s of four sides-of a rectangle, The second peripheral part of each intërnal electrode 32 ls arcuately recessed from one of the four sides. Furthermore, the first and the second areas 46 and 47 are de~ined on opposing side surfaces of the stack, In any event, the first and the second external electrodes 33 and 34 are formed on the first and the second areas 46 and 47, respectively, like in the element illustrated with reference to Figs, 1 and 2, As Example II, electrostrictive elements were ~anufactured as descrlbed in conjunction with the elements of Example I except that each internal electrode 32 (Fig, 7) had an internal electrode area which was 92~/o of the cross-sectional area of the stack.
Silver paste ~as applied ln stripe~ onto the fir~t and the Recond areas 46 and 47 and then fired into the first and the second external electrodes 33 and ~ m e electrode term1nals 36 and 37 ~ere attached to the respective exter~al electrodes 33 and 34~
The life tests and tests for the displacement were carried out for the electro6trictlYe elements of Example II and of Reference I as described in connectisn ~th Figs. 5 and 6.
The results were similar except that the maximum di~place~ent was 4Oo micron~ and a little smaller than that attained by tha elements of Example I.
Referring bac~ to Figs. 7 and 8, it is possible to form the first and the second areas 46 and 47 on two adjacent side surfaces of the stack. Alternati~ely, the second or arcuately recessed peripheral part may be offset along an outline which is co~gruent with the p~edeter~ined outline so that both the first and the second areas 46 and 47 may b.~ formed on one of the four side surfaces of the stack. In any event 9 the predetermined outline may be circular, olliptic, or the like.
Turning to Fig9 9, the second peripheral part may be a short linear portion ~hich intersects t~o adjace4t sides of the predetermired outline of a rectangular shape, In the example being illustrated, the ~ir~t area is formed on t~o adjacent side surfaces of the stack along an edge thereo~, The 6econd area is fiimilarly formed o~ two uther side surfaces. A~ described in connection with Figs, 7 and 8, the flr6t and the second areas may be formed so as to sha~e one of thP four side fiurface~ ~n ~2~
common~ In this event, it is possible to form the first and the second external electrodes on that one of the side surfaces, Turning further to Fig~ 10, the second peripheral part may be a line ~hich intersects opposing sides of the predeter~ined outllne of a rectangle. It may appear that the electrostrictive ela~ent depicted in Fig. 10 is similar to the conventional element, The fact i~ quite different in that the first peripheral part of each lnternal electrode 3~ is placed on a majDrity of the peripheral surface and in that the life i~ quite unexpectedly lengthened with the attainable displacement rendered astonishingly great, Referring to Fig, 11, an electrostricti~e element according to a third embodiment of this invPntion is similar in st~ucture to that illustrated with reference to Figs, 3 and 4 and that illustrated with refsrence to Fig6. 7 and 8 or Fig, 9 or 10 in that each internal electrode 32 has an internal electrode outline congruent with the predetermined outline of the stack and in that each internal electrode 32 has an.internal electrode.area whlch i5 narrower than the cross-seGtional area of the stack, respectively. The intexnal electrode area is rendered narrow by forming at least one hole through ~ach internal electrode ~2, In the illustrated example, nine holes are formed in a matrix con~ieuration in each internal electrode 32 of a square shape, As Exampleæ III, I~, and V, electrostrict~e ele~ents were manufacutured a~ described in conjunction with the elements of Example I and ~ith the internal electrode areas rendered 9~/o, 850/o, and 70/o of the cross-~ectional area, respecti~ely, . ; The hole~ were readily formed by screen printing the platinum ~L2~
paste onto the surface of each green ~heet piece. The first and the second external electrodes 33 and 34 (Figs, 3 and 4) ~ere formed by soldering a pair of lead wires to the peripheral ends of the respective internal electrodes 32 as described before, Turning to Fig, 12, tests for the life and the maximum displacement were carried out for the electrostrict1Ye elements of Examples IIl through V and of Reference I as described in connection ~ith ~`ig. 5, The life and the ~aximum displacement are shown by llnes 51, 52, and 53 for the elements of Examples III through V, respectively, and by the line 42 for the elements of Reference I as abo~e. Irrespective of the fact that each internal electrode area was narrower in the elements of Example V than the elements of Reference I, the line 53 shows an astonishing-ly long life ~ith an appreciably greater maximum displacement, Turning further to Fig. 13, displacements were measured as described ln connection with Fig. 6~ Curves 56, 57, and 58 show the results for the elements of Examples III through V, respectively, Despite the fact that each intern~l electrode area of the elements of Example I~ was not much wider than that in the element~ of Reference I, the cur~e 5~ sho~s a considerably greater displacement than that depicted by the cur~e 44 for the elements of ~eference ~ as in Fig. 6.
Referring to Figs, 14 and 15, an electrostrictive element aocordin~ to a fourth embodiment of this inYention is similar to that described with reference to Fig. ll in that each internal electrode 32 ha6 a smaller hole 61 of a predetermined inside diameter and a greater hole 62 of a greater inside diameter as exemplified in Fig, 15, Each internal electrode outline is preferably 1~
congruent with the predetermined outline ~hich the peripheral surface of the stack has perpendicularly of the stack axis, In the example being illustrated, the internal electrode outline consi&ts of four sides of a square. Furthermore, the smaller and the greater holes 61 and 62 are positioned symmetrically on a line bisecting opposing sides of the square on both sides of another line bisecting other opposing sides. Each electrostrictive section 31 on ~hich the internal electrode 32 is formed, has two holes in registration ~ith the smaller and the greater holes 61 and 62. One of the holes formed through the electrostrictive section 31 has the predetermined inside diameter and indicated at 63, The other hole of the electrostrictive section 31 also has the predetermined inside diameter, As best shoHn in Fig, 14, electrostrictive sections 31 ~ith such internal electrodes 32 are stacked so that the smaller and the greater holes of alternate ones of the internal electrodes 32 may be aligend with the greater and the smaller holes of others of the internal electrodes 32 7 respect~vel~. A first conductor rod 64, ~hich serves for the fir6t external electrode 33 (Figs.
1 or 3), ~ills the smaller holes of the alternate ones of the internal electrodes 32 in contact with such internal electrodes 32 and passes through the greater holes of the other internal electrodes and tho~e of the holes of the electrostricti~e elements 31 which are aligncd with the smaller holes of the alternate ones of the internal electrodes 32 and consequently with the greater holes of the other internal electrodes, Similarly, a second conductor rod 65 fills the smaller holes of the sther internal electro1es in contact therewith and passes through the ~%~
greater holes of the alternate ones of the internal electrodes 32 and the other holes of the electrostrictive sections 31 to serve for the second external electrode 34, In contrast to the external electrodes 33 and 3L~ of each electrostrictive element illustrated ~ith reference to Figs, 3 and 4, it is readily possible to stably connect the conductors 64 and 65 to the alternate ones of the internal electrodes 32 and to the other internal electrodes, respectively.
As EXample YI, electrostrictive elements were manufactured with the structure described in conjunction ~ith Figs. 14 and 15. A pair of holes of a co~mon inside diameter was drill~d through each green sheet piece formed as described in connection with Example I. As depicted in Fig. 15, platinum paste was screen printed on the drilled green sheet piece to leave a blank area f a greater diameter around the hole 63 of the green sheet piece and was filled in the holes, such as 63, of each green sheet piece, As described in connection ~ith Example I, the green sheet pieces with the printed and filling .platinum paste were stacked, rendered integral, and then sintered. During the sintering process, the platinum paste filling the respectivs holes of the stacked green sheet pieces was fired into platinum rods to serve as -the conductor rods 64 and 65. When the spacing between two ad~acent internal electrodes 32 was 0.1 mm, it ~as confirmed that the predeter~ined inside diameter of 0 15 mm and the greater inside diameter of o.6 m~ were suffi.clent to r~adily and stably proYlde the conductors 64 and 65 without any short circuit between the successive internal electrodes 32. Incidentally, the elements "; had a square cross section of 10 mm by 10 ~m, ~6~3 Turning back to Fig. 15, it is unnecessar~ thzt the smaller and the greater holes 61 and 62 be circular. Regardless of the shape or shapes of the holes 61 and 62, the smaller hole 61 should have a smaller inside measure, ~hich may be called a predetermined in3ide measure. The greater holes 62 should have a greater inside measure preferably in common. It is also unnecessary that the holes 61 and 62 be symmetrically situated on both sides of the cent~r of the internal electrode 32. It is only necessary on ~anufacburing th~ stack of electrostrictive sectionæ 31 that the smaller holes 61 of alternate ones o~ the internal electrode~ 32 be aligend with the greater holes 62 of others of the internal electrodes 32 with the greater holes 62 of the alternate ones of the internal electrodes 32 aligned with the smaller holes 61 of the other internal electrodes. For example, it is possible to form the "holes" in each green sheet piece of a rectangular cross section by forming deeply arcuately recessed indents from one of the four sides of the rectangle.
Referring to Figs. 16 and 17, an;électrostrictive ele~ment according to a fifth embodiment of this invention compri~es similar parts designated by like reference numerals. It is possible to understand that the element being illustrated is similar to that described ln connection with Fig. 11, More particularly, each internal electrode 32 has an internal electrode outline congruent with the predetermined outli~e whieh the peripheral surface of the stack has perpendioular to the stack axis. A
peripheral end of each internal electrode 32 is situated ~n the peripheral surfaceO An~ internal electlode area whlch the internal electrode 32 has orthogonally of the ~tack axis, is narro~er than the cross-sectional area of the ~tacX. The area is ~enderzd narrow by a plurality of parallel holes formed thrDugh each internal electrode 32 with a common height parallel to the stack axis.
For the reason ~hich ~ill presently become clear, the holes in the respective internal electrodes 32 are preferably aligned parallel to the stack axis. The electrostricti~e section~ 31 are continuous throughout the stack through the aligned hole More particularly referring to Figs. 16 and 17, each internal electrode 32 comprises a plurality of inter~al electrode s~ctions, each haYing a predetermined width parallel to the stack axis and a section end~ The internal electrode sections of each internal electrode 32 are arranged at a predetermined distance.
The internal electrcde 32 preferably co~.prises a conductor piece 66 on the peripheral surface of the stack in contact with the section er.ds of the respective internal electrode sections.
The conductor piece or pieces 66 pro~ide a part of the peripheral end. The first external electrode 33 is formed by soldering or otherwise attaching a lead wire either to ~he conductor piece 66 of alternate ones of the internal electrodes 32 or to those of the internal electrode sections of the alternate ones of the internal electrodes 32 which are placed on the peripheral surface, The second ex~ernal electrodç 34 is formed by similarly connecting another lead wire to the peripheral ends o* others of the internal electrodes 3Z. It is possible to form a pair of such conductor pieces in contact with both ends of each internal electrode section for each internal electrode 3Z, Turning to Fig, 18, a green sheet piece 67 is for use ir. manufacturin~ an electrostrictive element of the structure ~L ~7D~
illustrated ~ith reference to Figs, 16 and 17, Platinum paste is printed in stripes on the grean sheet piece as exemplified at 68, The element is manufactured by stacking a predetermined number, such as thirty qheets, of the green sheet pieces 67 with 3 the platinum paste stripes 68, rendering the lamination integral in a hot prRss, and subsequently sintering the integral lamination.
The platinum paste stripes 68 provide the internal electrode sections of the respective intexnal electrodes 32. The gree~
sheet portions bet~een layers of the internal electrode sections provide the electrostricti~e sections 31 ~hich are continuous as described aboYe. The green sheet pieces 67 with the printed stripes 68 enable the element to be readily manufactured ~ith a smaller number of green sheet pieces as compared with the elements described in connection with Examples I through VI as will shortly become clear.
As Example VII, electrostrictive elements ~ere ~anufactured as follows, Green sheet pieces were manufactured as in Example I, Each green sheet piece was about 3 mm ~ide;, 10 ~ long, and 100 microns thick, Platinum paste was scrèen pr~nted on each ~reen sheet pi~ce, Each platinu~ paste strlpe 68 (Fig. 18) had P ~idth selected between 20 and 30 microns. Each blank area lef'l between two adjacent platinum paste stripes 68 had a width whish was selected between 20 and 30 microns. Thirty green sheet pieces ~ith the printed stripes, ~ere stacked for each electrostxic-ti~e element with the plat~num pa~te stripes printed on bothsurfaces of the green sheet piece which was to be placed at an end of the lamlnation, It is to be noted in this Gonnect~on ; that a stack and an axi~ of stack oftan referred to in the instant 3~
specification, should refer to a stack of the electrostrictive sections ~1 (Figs, 1, 3, and the like) rather than to a stack or lamination of the green sheet pieces 67 under consideratio~.
The stacked green sheet pieces 67 uere processed as described in connection Hith Example I, Silver paste wa~ printed on the peripheral surface of each element and ~as fired into the conductor pieces 66 (Fig. 17), It ~as readily possible to ~anufacture an electrostrictive element in which a great number of electrostric-tive sections 31 ~ere defined between the inte~nal electrode~
~2, Referring to Fig, 19, an electro6trictive element according to a sixth embodiment of th~s invention comprises similar part~
designated by like reference nu~erals. The internal s~ructure may be similar to that described in connection with the conventional electrostrictive element ~ith reference to Fig.6 1 and 2. It is, houever, to be noted that those parts of the electrostrictiYe section~ 31 (Flg. 1) are removed at selected heights of the stack which do not contribute to the electro~trie~iv~ effect, By way of example, indents or groove~ 71 are formëd OD the peripheral surface, Each indent 71 may be formed along the whole periphery of the peripheral surface by a diamond cutter, When attention is dlrected to a ~irst peripheral part defined by ths bottom of each indent 71, it is understocd that the internal electrode outline of each internal electrode 32 (Fig, 1) is approximately congruent ~ith an outline ~hich the first peripheral part has perpPndicular to the stack axis and which may again be called the predetermined outline, ~he peripheral surface further comprises second peripheral parts from which ., each indent 71 is recessed to define the first peripheral part, Each lnternal electrode 32 has an end on the second peripheral part as Hill be understood from Figs. 1 and 2. In order that even a part of the internal electrod~s 32 may not be removed, it ~s preferred that each indent ~1 be formed only partly along the periphery. For exemple, each indent 71 may be formed in two parts along the Ride surfaces depicted in Fig. 2 at the tsp and ths bottom of ~he figure~
A~ Example VIII, electrostrictiYe elements ~ere manufactured like the elements of Re~erence I except that inde~t~ were machined by a diamond cutter along the whole periphery after the first and the second external electrodes 33 and 34 (Fig. 19) were formed.
$ach indent 71 was 0.1 mm wide in the direction parallel to the stack axis and 0.1 mm deep perpendicularly of the axis. The center to center dlstance be~ween tho adjacent indents 71 wa~
WITHSTANDS REPEATED APPLICATION OF PULSES
Background of the Inventlont This inYention relates to an electrostrictive element or transducer of a multilayer structure ~hich is generally called a ~tacked chlp or ceramic capacit~r structure in the art, An electrostrtictive element acco~ding to this invention i8 apecifically useful in, among others, a prlnter head of an ~mpact printer or a relay, As described in a report contributed by Roderic Beresfo~d to "Electronics," November 3, 1981, pages 39 and 40, undPr the title of "Piezoelectric bsnder actuates tiny relays and dot-matrix prlnters," an electrostrictlve element is useful as a printer head, a rel~y, or the like. An electrostrictive element is actuated by a d.c, voltage repeatedly supplled thereto a ltage pul~e~
~hen used ln such field~ of application~.~ The element ~ust withstand ~15 repested applicatlon of suGh voltage pulse~. In other ~o~ds, the element mu~t have a long life e~en ~he~ a great number o~
voltaee pulses are applied thereto. Furthermore, it is de~irable tha~ the element ~hould g~e~rise to a great displacement, An~electxo6tr10tlve ele~ent of a s1mplest typs compri~es " . ~
; 20 an electro~trictlve piece of a~ electro6triotive ~aterial capable : ~ ~ of exh~bitlng a strong electrostrictive effect, m e piece ha6 a palr ~f electrodes ~9n the princlpal 0urfac0~. ~hen a d.c, voltage i8 suyplled be~een *he electrode~ to produce an electric :
: field in the piece, th~ plece elon~ate6 and contr~cts ln the , ~ . ~,, ~Z~ 3 direction of the electric field and transversely thersof, re~pective-ly. Such deformations or strains in the direction of the alectric field and in the tranæverse direction are called the longitudinal and the tran~verse electrostrict~ve effects. It i6 kno~n that the logltudinal electrostrictive effect or~inally giYes ri~e to twice to three time~ as great a deformation as the transverse electro~tricti~e effect, The longitudinal electrostricti~e effsct thexefore pro~ides a higher efficiency of conver~ion fro~ electric energy to mechanical energy. m e deformation in the longitudinal or the trans~erse direction depend6 on the field ~ntensit~y of the electric field produced in the electro~trictlve plece.
~ hen the transverse electrostricti~e effect is used, it is possible with a certain applied voltage to achieYe a displace-ment in the transverse direction in proportion to the dimension which the electrostrlctive piece ha~ in the transverRe direction.
~hen the longitudinal electrostrictive effect 18 ussd in order to use the higher efficiency of energy conversion, the displacement in the logitudinal direction does not grow for a giYen voltage ~ith an increase in the dimens~on which thë ple~e has in the longitudinal direction, Thl~ iB becau6e the field intensity becom0~ weak with the increased longitudinal dimension. It i6 therefore necessary on attaining a great dl~placement with the longitudinal electro~trictive effect to raise the applied voltage so as to strengthen the field inken~ity. ~ po~er souroe for a h~gh voltage iB, ho~ever, bulky and expensiVQ. Furthermore, a high voltage i8 objectionable in Yie~ of the danger inevitable during operation of the electrostrictive element 1nd also in view of the ~thstanding voltage of IC'~ which are u~ed in a driving circuit for the element, The element is tharefore gi~en the multilayer structu~e when the longitudinal eIectrostrictive effect is resorted to.
As will later be described in detail Hith reference to t~o of nearly ~hlrty figures of the accompanying dra~lng, a multilayer electrostrictive element comprises a plurality of electro~trictlve ~ection~ defined in a stack or lamination by a plurality of internal electrode~ which are perpendlcular *o an axi6 of the stack, The stack has a peripheral su~face which hae a predete~mined outline perpendicularly of the axis, For uee in a printer head or a relay, lt is p~eerred that the predeter-mined outline be four ~ides of a rectangle. A flrst external electrode is connected to alternate one6 of the internal electrodes and placed externally of the peripheral surface, A second external electrode ls onnected to others of tlle internal electrodes and pos~tioned externally of the periphe~al sur~`ace, At least one of the first and the second external electrodes ~ay be extended ln contact with the peripheral surface.` E~en ~n thi~ event, it is posslbe to understand that the ext~rnal electrode or electrodes are situated externally of the peripheral surface, With a multilayer electrostricti~e element, a ~reat displacement is achieYed at a 10N voltage even by ths u~e of the longitudinal electrostrictive e~fect. It is to be noted here that each lnternal electrode has an internal electrode outline which i~ po~itioned only partly on the peripheral surface for connection to the flrst or the second external electrode, In other words, each internal electrode has a~ internal electrode area whl¢h iB conslderably narroHar than a cros~-sectional arfls of the stack. As will later be discussed with reference to several figures of the accompanying drawing, it has now been con-firmed that this results in a short life which the electrostric-tive element has when repeatedly supplied with voltage pulses.
Moreover, this restricts the displacement small as compared with the displacement which is theoretically attainable.
Summar~ of__he Invention It is therefore an object of the presen-t invention to provide a multilayer electrostrictive element which has a long life even when voltage pulses are repeatedly applied to repeatedly drive the element.
It is another object of this invention -to provide an electrostrictive element of the type described, which provides a greater displacement as compared with that achieved by conventional electrostrictive elements.
Other objects of this invention will become clear as the description proceedsO
The present invention provides a multilayer electro-strictive element for dimensionally changing in a first direction in response to electrical pulses and for withstanding repeated application of said pulses, said element comprising: a stack for-med by a plurality of electrostrictive sections of an electro-strictive material and a plurality of internal electrodes sandwiched between said electrostrictive sectionsl said stack having a peri-pheral surface defining a cross-sectional area of said stack, each of said internal electrodes having peripheral ends on said peri-fS~
pheral surface and each of said internal electrodes having aninternal electrode area which is substantially equal to a cross-sectional area of said stack, first means for electrically connec-ting alternate ones of said internal electrodes together without connecting others of said internal electrodes, said first means including first insulating layer portions on a first area of said peripheral surface for covering respective peripheral ends of said others of said internal electrodes while leaving portions of said first area uncovered, each said first insulating layer por-tion covering the peripheral end of a respective internal elec-trode while extending in said firs-t direction substantially less than the entire distance between said respective first electrode and either adjacent first electrode to leave uncovered substan-tial portions of the surfaces of said electrostrictive sections in said first area of said peripheral surface, and a first conduc-tive layer continuously formed on both said first insulating layer portlons and on said uncovered portions of said first area; and second means for electrically connec-~ing said others of said internal electrodes together, said second means including insula-ting layer portions on a second area of said peripheral surfacefor covering respective peripheral ends of said alternate ones of said internal electrodes while leaving por-tions of said second area uncovered, and a second conductive layer continuously formed on both said second insulating layer portions and on said uncovered portions of said second area.
The invention will now be described in greater detail with reference to the accompanying drawings, in which:
-5a-Fig. 1 is a schematic longitudinal sectional vieT~J of a conventional electrostrictive element;
Fig. 2 is a top view of the electrostrictive element illustrated in Fig. 1:
Fig. 3 is a schemat-cal longitudinal sectional view of an electrostrictive element according to a first embodiment of the instant invention;
Fig. 4 is a top view of the electrostrictive element depicted in FigO 3;
Fig. 5 shows the life for conventional electrostrictive elements and for electrostrictive elements of the type shown in Figs. 3 and 4;
Fig. 6 shows the displacement a-ttained by the electro-strictive elements mentioned in connection with Fig. 5;
Fig. 7 schematically and partially shows a perspectively exploded view of an electrostrictive element according to a second ,.~
embodiment of this inYention~
-- Fig. 8 i6 a top view of the electrostrictlYe element illustrated in Fig, 7~
Fig, 9 schematically and partially sho~^ a perspectively explsded view of an electrostrictive element according to a modifica-tion of the element depicted in Figs, 7 a~d 8~
Fig. 10 i8 a top view of an electrostrictive elsment according to another mGdiflca*ion of the element illu~trated 1n Figs, 7 and 8~
Fig, 11 1~ a schematic top vie~ of an electrostricti~e element according to a third emboli~ent of this invention~
Fig. 12 shows the life ~or conventional electrostrictive elements and for electrostrictive elements of the structure depicted in Fig, 11;
Fig. 13 sho~s the displacement achieved by the elements mentioned in conjunction with Fig. 12;
Fig. 14 is a schematlc longitudinal sectional view of an electrostrictive element accordin~ to~a `fourth embodiment of this invention; ` `~
Fig. 15 iB a schematic top view of a green ~heet piece for u8e in manufacturing the element shown in Fig. 14~
P~g. 16 i5 a schematical longitudinal sectional ~iew of an electrostrictive element according to a flfth embadiment Gf this inYention~
Fig, 17 1~ a top view of the ele~ent illustrated in Fig, 16~
Fig, 18 as a schemat~c top vie~ of a gresn sheet piece ', for uae in ~a~u~acturing the element of the type depicted ln Figs, 16 and 17~
Fig. 19 is a schematic side vie~ of an electrostrictive element acco~ding to a sixth embodiment of this invention;
Fig, 20 shows the life for conventional electrostricti~e elements and for electrostrict~e elementa of the ty~e de~icted in Fig. 19 Fig, 21 sho~6 the displacement achieved by the element~
msntioned in conjunction wlth Fig, 20 Fig, 22 is a schematical longitudlnal sectional Y~e~
of an electrostrictive element accord~ng to a seventh embodiment of thi~ inventlons Fig, 2~ is a schematical longitudinal sectional view of an electrostrictive element according to an eighth embodiment of this invention;
Fig. 24, drawn on the righthand side of Fig, 18 merely for convenience of illustration; is a schematic perspective vlew of an electrostrictive element according to a n1nth e~bodiment of this invention~ ; ; ;
Fig, 25 shows the life for ele~trostrictiYe element~
according to a tenth embodiment of this invention~
Fig, 26 shows the displacement attained by the elements mentioned in connection with Fig, 25t Fig, 27 shows the life for electrostrictive elements accordin~ to an eleventh emb~diment of thls inventlon and ~or the elements mentloned in connection ~i*h Flgs. 25 and 26;
Fi~. 28 shows the life for electrostrictive element3 according to a twelfth embodiment of this invention and '~2(3~
Fig. 29 shows the displacement achieved-by the elements mentioned ln conjunction ~ith Fig. 28, D scription of the Preferred Embodiments~
Referring to Figs, 1 and 2, a con~entional ~ultilayer electro~tricti~e elament or transducer ~ill be described at first in order to facilitate an understanding of the present invention.
The element co~prises a stack or lamination of a plurality of ~lectro6trictive section~ or segments 31 of an electrostrict~ve material capable of exhib~ting a strong electrostrietive effect.
The electrostrictlve section~ 31 are defined in the stack by a plurality of internal electrodes 32 which are indicated by thick lines and are disposed perpendicular to an axis of the stack with a predetermined spacing, Althou~h called "internal electrodes," the electrodes 32 may be placed on one or both of the top and the bottom surfaces of the stac~. The stack has a peripheral surface of a cross ~sction which is encloded ~ith or contained ~y a predetermined outllne. In the example being illustrated, the predetermined outline-cons~st~ of four side~
. ~, . .
of a rectangle. The peripheral surfac~ ha~ the predetermined outline throughout the stack, It is possible to render the predeter-mined ~pacing as small as several micron~, As seen fr~m Fig~, 1 and 2, each lnternal electrode 32 ha~ an end on the peripheral sur~ace. More particularly, alternate ones of the internal electrsdes 32 have their respectlve 27 end~ on one of four side 6urfaces of the ~tack. Othe~R of the internal electrodes 32 have the ends on an opposin~ side sur~aca of the ~tack as outlined by dashed lines ln Fig, 2, A first external electrode 33 is for~ed on the fir6t-mentioned side sur~ace .; .
ln contact with the ends of the alternate ones of the internal electrodes 32, A second external electrode 34 i3 ~ormed on the opposing side surface in contact ~ith the ends of the others of the intPrnal electrodes 32. First and second electrode ter~inals 36 and 37 are connected to the first and the second external electrodes 33 and 34, respectively.
~ hen a d.c. ~oltaee is supplied bet~een the electrode terminals 36 and 37, electric fields are produced in the respecti~e electrostrictiva section~ 31, The electrostricti~e element elongates axially of the stack, ~hen the d.c, Yoltage is repeatedly applied to the element a great num~er of time~ or repetitions as ~oltage pulseæ, the element is mechanically damaged particularly ~f the voltage i~ raised to achieve a great displacement. Furthermore, the elongation or displacement of the element is appreciably sm~ll as compared with the elongation which would theoretically be attained, As ~ill later be evidenced by various exa~ples in comparison with references, it has now been confirmed ~h~t such-defects of a conventional electrostrictive elemeht result from the fact that an area on which the internal electroaes 32 are superposed, is considerably narrower than a cross-sectional area of the stack, More specifically, the electric field is produced in each electrostric-tive section 31 su~stantially only at a centxal portion between the oppo ing internal electrodes 32, The electric field is weak at a peripheral portlon surrounding the central portlon. The elongation therefore takes place at such central portions of the respective electrostrictiYe s~ctions 31 and hardly occurs at the peripheral portions. m e elongation of the element as 3 whole is consequently advers01y affscted by the peripheral portions. Moreover, concentration of the stress takes place along the boundary bet~een the central and the peripheral portions, This results cracks or other machanlcal damage when a large number of voltage pulses are applied to the element.
Referring now to Figs. 3 and 4, an electrostrictive element according to a first embodiment of this invention comprises similar parts designated by like reference numerals. Each internal electrode 32, however, has a peripheral end of an inter~al electrode outline congruent w~th the predetermined outline which the peripheral surface of the stack has perpendicularly of the stack axis.
The peripheral ends of the respective internal electrodes 32 are positioned on the periphPral surface. Furthermore, each internal electrode 32 has an internal electrode area whioh is equal to the cross-sectional area of the stack. The first external electrode 33 ls positioned externally of the peripheral surface and is brought into contact with the peripheral ends of the alternate ones of the internal electrodes 32, The second external electrode 3~ is laid outwardly of the peripheral sUrface and connected to the peripheral ends of the other internal electr~des.
A~ Example I, electrostrictîve elements of the structure illustrated with refsrence to Figs. 3 and 4, ~ere manufactured as follows. At first, a slurry was prepared by suspending a mixture of presintered powder of a solid solution of lead ~agne~ium niobate Pb(Mgl~3Nb2~2)03 and lead tltanete PbTiO3 in a mol ratio of 9 to 1 and an organic binder, in an organic ~olvent i~ the manner kno~n in the art, The presintering ~a~ carried out at 800C for two hours, It is known that a sintered piece of the solid solution exhibits a strong electrostrictive effectO The slurry w~s applied onto a polyester film kno~n as a Mylar film by the doctor blade method to a thickness of several hundreds of microns ahd then dried, A green sheet thus formed, Nas pealed off the polyester film and subsequently cut into green sheet pieces of a predetermined size. Platinum paste was printed to form a platinum pa~te layer on a surface of each green sheet piece, The green sheet pieces with the prlnted platinu~ paste layers, were stacked, rendered integral in a hot pre3s, machined to predetermined dlmensions to expose the peripheral ends of the respective platinum paste layexs on the peripheral surface of each integral stack, and subsequently sintered at about 1200C
for one hour. The green sheet pieces became the electrostricti~e sections 31 (Fig. 3). Fired layers of the platinum paste became the internal electrodes 32.
Having been machined to the predetermined dimension~, each integral ~tack had a square cross section of 3 mm by 3 mm and a height of 10 mm. The spacing betweén~two adJacent-ones of the internal electrodes 32 was 250 microns. Lead wire~ were soldered to the peripheral ends o~ the respective 1nternal electrodes 32 so as to serve as the first and the second external electrodes 33 and 34 and ~o that a pair of ends of the respective lead wires serve as the *irst and the second electrode terminals 36 and 37.
As Reference I, electrostrictiYe elements of the con~ention-al structure illustrated w1th refererlce to F~gs, 1 and 2, were likewi6e manufactured, An area on ~hich the internal electrodes 32 were superpo6ed, W3S 84~/o of the cross-sectional area of 3~
the stack. ~e external electrodes 33 and 34,were for~ed by applying silver paste onto the side surfaces and then firing the paste, Turning now to Figo 5, a pulse sequence ~as continuously applied to each of the electrostrictive elements of Example I
and of ~eference I. Each pulse w2s a half of a sinusoidal ~ave of an amplitude of 250 volts, Each pulse had a pulse ~idth of 1 millisecond. As shown by an upper line 41, the elements of Example I showed a maximum d~splacement sf 4,1 microns. A lo~er curve 42 represents that the elements of Reference I sho~ed a maximum displacement of only 1,3 mic~on~. Each element of Example I ~as not damaged or broken even when the pulses were applied one hundred million times or repetitions as shown by the upper line 41. Each element of Reference I ~as damaged as indicated by a cross ~hen the pulses ~ere applied about twenty-five thousand times.
Turning further to Fig. 6, a d.c. voltage was applied to each of the electrostrictive elements o~ Example I and,of Reference I, Displacements were measured with the voltage varied, As is clear from upper and lower curves 43 and 44 for the elements of Example I and of Reference I, respectiYely, the elements of Example I showed twice to three tlmes as great a displacement as the elements of Reference X at a given voltage (and consequently at a given ~ield intensity).
Referring to Figs, 7 and 8, an electrostrictiYe element according to a second embodiment of this invention comprises similar parts designated by like reference numerals. Somewhat dlfferent fro~ the internal electrodes 32 described in con~junction ~ith Figs. 3 and 4, each internal electrode 32 has a peripheral e~d of an internal electrode outline which is approxi~ately congruent ~ith the predetermined outline of the stack, Each internal electrGde 32 has an internal electrode area which is a little narro~er 5 than the cross-sectional area of the stack, A* any rate, the internal electrode outlines of the respective internal electrode~
~2 are congruent with one another, More particularly, the peripher~l end of each internal electrode 32 comprises a first and ~ second peripheral part, The first peripheral par~, as herein called, is congruent with the predetermined outline except for the second peripheral part. The first peripheral parts of the respective internal electrodes 32 are situ~ted on the peripheral surface.
m e second peripheral parts of alternate ones of the ~nternal electrodes 32 are positioned in the stack so as to define a first area 46 on the peripheral surface, The second peripheral parts of others of the i~ternal electrodes 32 likew~se define a second area 47 on the peripheral surface, In the example beingillustrated, the predetermined outline again consis~s of four sides-of a rectangle, The second peripheral part of each intërnal electrode 32 ls arcuately recessed from one of the four sides. Furthermore, the first and the second areas 46 and 47 are de~ined on opposing side surfaces of the stack, In any event, the first and the second external electrodes 33 and 34 are formed on the first and the second areas 46 and 47, respectively, like in the element illustrated with reference to Figs, 1 and 2, As Example II, electrostrictive elements were ~anufactured as descrlbed in conjunction with the elements of Example I except that each internal electrode 32 (Fig, 7) had an internal electrode area which was 92~/o of the cross-sectional area of the stack.
Silver paste ~as applied ln stripe~ onto the fir~t and the Recond areas 46 and 47 and then fired into the first and the second external electrodes 33 and ~ m e electrode term1nals 36 and 37 ~ere attached to the respective exter~al electrodes 33 and 34~
The life tests and tests for the displacement were carried out for the electro6trictlYe elements of Example II and of Reference I as described in connectisn ~th Figs. 5 and 6.
The results were similar except that the maximum di~place~ent was 4Oo micron~ and a little smaller than that attained by tha elements of Example I.
Referring bac~ to Figs. 7 and 8, it is possible to form the first and the second areas 46 and 47 on two adjacent side surfaces of the stack. Alternati~ely, the second or arcuately recessed peripheral part may be offset along an outline which is co~gruent with the p~edeter~ined outline so that both the first and the second areas 46 and 47 may b.~ formed on one of the four side surfaces of the stack. In any event 9 the predetermined outline may be circular, olliptic, or the like.
Turning to Fig9 9, the second peripheral part may be a short linear portion ~hich intersects t~o adjace4t sides of the predetermired outline of a rectangular shape, In the example being illustrated, the ~ir~t area is formed on t~o adjacent side surfaces of the stack along an edge thereo~, The 6econd area is fiimilarly formed o~ two uther side surfaces. A~ described in connection with Figs, 7 and 8, the flr6t and the second areas may be formed so as to sha~e one of thP four side fiurface~ ~n ~2~
common~ In this event, it is possible to form the first and the second external electrodes on that one of the side surfaces, Turning further to Fig~ 10, the second peripheral part may be a line ~hich intersects opposing sides of the predeter~ined outllne of a rectangle. It may appear that the electrostrictive ela~ent depicted in Fig. 10 is similar to the conventional element, The fact i~ quite different in that the first peripheral part of each lnternal electrode 3~ is placed on a majDrity of the peripheral surface and in that the life i~ quite unexpectedly lengthened with the attainable displacement rendered astonishingly great, Referring to Fig, 11, an electrostricti~e element according to a third embodiment of this invPntion is similar in st~ucture to that illustrated with reference to Figs, 3 and 4 and that illustrated with refsrence to Fig6. 7 and 8 or Fig, 9 or 10 in that each internal electrode 32 has an internal electrode outline congruent with the predetermined outline of the stack and in that each internal electrode 32 has an.internal electrode.area whlch i5 narrower than the cross-seGtional area of the stack, respectively. The intexnal electrode area is rendered narrow by forming at least one hole through ~ach internal electrode ~2, In the illustrated example, nine holes are formed in a matrix con~ieuration in each internal electrode 32 of a square shape, As Exampleæ III, I~, and V, electrostrict~e ele~ents were manufacutured a~ described in conjunction with the elements of Example I and ~ith the internal electrode areas rendered 9~/o, 850/o, and 70/o of the cross-~ectional area, respecti~ely, . ; The hole~ were readily formed by screen printing the platinum ~L2~
paste onto the surface of each green ~heet piece. The first and the second external electrodes 33 and 34 (Figs, 3 and 4) ~ere formed by soldering a pair of lead wires to the peripheral ends of the respective internal electrodes 32 as described before, Turning to Fig, 12, tests for the life and the maximum displacement were carried out for the electrostrict1Ye elements of Examples IIl through V and of Reference I as described in connection ~ith ~`ig. 5, The life and the ~aximum displacement are shown by llnes 51, 52, and 53 for the elements of Examples III through V, respectively, and by the line 42 for the elements of Reference I as abo~e. Irrespective of the fact that each internal electrode area was narrower in the elements of Example V than the elements of Reference I, the line 53 shows an astonishing-ly long life ~ith an appreciably greater maximum displacement, Turning further to Fig. 13, displacements were measured as described ln connection with Fig. 6~ Curves 56, 57, and 58 show the results for the elements of Examples III through V, respectively, Despite the fact that each intern~l electrode area of the elements of Example I~ was not much wider than that in the element~ of Reference I, the cur~e 5~ sho~s a considerably greater displacement than that depicted by the cur~e 44 for the elements of ~eference ~ as in Fig. 6.
Referring to Figs, 14 and 15, an electrostrictive element aocordin~ to a fourth embodiment of this inYention is similar to that described with reference to Fig. ll in that each internal electrode 32 ha6 a smaller hole 61 of a predetermined inside diameter and a greater hole 62 of a greater inside diameter as exemplified in Fig, 15, Each internal electrode outline is preferably 1~
congruent with the predetermined outline ~hich the peripheral surface of the stack has perpendicularly of the stack axis, In the example being illustrated, the internal electrode outline consi&ts of four sides of a square. Furthermore, the smaller and the greater holes 61 and 62 are positioned symmetrically on a line bisecting opposing sides of the square on both sides of another line bisecting other opposing sides. Each electrostrictive section 31 on ~hich the internal electrode 32 is formed, has two holes in registration ~ith the smaller and the greater holes 61 and 62. One of the holes formed through the electrostrictive section 31 has the predetermined inside diameter and indicated at 63, The other hole of the electrostrictive section 31 also has the predetermined inside diameter, As best shoHn in Fig, 14, electrostrictive sections 31 ~ith such internal electrodes 32 are stacked so that the smaller and the greater holes of alternate ones of the internal electrodes 32 may be aligend with the greater and the smaller holes of others of the internal electrodes 32 7 respect~vel~. A first conductor rod 64, ~hich serves for the fir6t external electrode 33 (Figs.
1 or 3), ~ills the smaller holes of the alternate ones of the internal electrodes 32 in contact with such internal electrodes 32 and passes through the greater holes of the other internal electrodes and tho~e of the holes of the electrostricti~e elements 31 which are aligncd with the smaller holes of the alternate ones of the internal electrodes 32 and consequently with the greater holes of the other internal electrodes, Similarly, a second conductor rod 65 fills the smaller holes of the sther internal electro1es in contact therewith and passes through the ~%~
greater holes of the alternate ones of the internal electrodes 32 and the other holes of the electrostrictive sections 31 to serve for the second external electrode 34, In contrast to the external electrodes 33 and 3L~ of each electrostrictive element illustrated ~ith reference to Figs, 3 and 4, it is readily possible to stably connect the conductors 64 and 65 to the alternate ones of the internal electrodes 32 and to the other internal electrodes, respectively.
As EXample YI, electrostrictive elements were manufactured with the structure described in conjunction ~ith Figs. 14 and 15. A pair of holes of a co~mon inside diameter was drill~d through each green sheet piece formed as described in connection with Example I. As depicted in Fig. 15, platinum paste was screen printed on the drilled green sheet piece to leave a blank area f a greater diameter around the hole 63 of the green sheet piece and was filled in the holes, such as 63, of each green sheet piece, As described in connection ~ith Example I, the green sheet pieces with the printed and filling .platinum paste were stacked, rendered integral, and then sintered. During the sintering process, the platinum paste filling the respectivs holes of the stacked green sheet pieces was fired into platinum rods to serve as -the conductor rods 64 and 65. When the spacing between two ad~acent internal electrodes 32 was 0.1 mm, it ~as confirmed that the predeter~ined inside diameter of 0 15 mm and the greater inside diameter of o.6 m~ were suffi.clent to r~adily and stably proYlde the conductors 64 and 65 without any short circuit between the successive internal electrodes 32. Incidentally, the elements "; had a square cross section of 10 mm by 10 ~m, ~6~3 Turning back to Fig. 15, it is unnecessar~ thzt the smaller and the greater holes 61 and 62 be circular. Regardless of the shape or shapes of the holes 61 and 62, the smaller hole 61 should have a smaller inside measure, ~hich may be called a predetermined in3ide measure. The greater holes 62 should have a greater inside measure preferably in common. It is also unnecessary that the holes 61 and 62 be symmetrically situated on both sides of the cent~r of the internal electrode 32. It is only necessary on ~anufacburing th~ stack of electrostrictive sectionæ 31 that the smaller holes 61 of alternate ones o~ the internal electrode~ 32 be aligend with the greater holes 62 of others of the internal electrodes 32 with the greater holes 62 of the alternate ones of the internal electrodes 32 aligned with the smaller holes 61 of the other internal electrodes. For example, it is possible to form the "holes" in each green sheet piece of a rectangular cross section by forming deeply arcuately recessed indents from one of the four sides of the rectangle.
Referring to Figs. 16 and 17, an;électrostrictive ele~ment according to a fifth embodiment of this invention compri~es similar parts designated by like reference numerals. It is possible to understand that the element being illustrated is similar to that described ln connection with Fig. 11, More particularly, each internal electrode 32 has an internal electrode outline congruent with the predetermined outli~e whieh the peripheral surface of the stack has perpendioular to the stack axis. A
peripheral end of each internal electrode 32 is situated ~n the peripheral surfaceO An~ internal electlode area whlch the internal electrode 32 has orthogonally of the ~tack axis, is narro~er than the cross-sectional area of the ~tacX. The area is ~enderzd narrow by a plurality of parallel holes formed thrDugh each internal electrode 32 with a common height parallel to the stack axis.
For the reason ~hich ~ill presently become clear, the holes in the respective internal electrodes 32 are preferably aligned parallel to the stack axis. The electrostricti~e section~ 31 are continuous throughout the stack through the aligned hole More particularly referring to Figs. 16 and 17, each internal electrode 32 comprises a plurality of inter~al electrode s~ctions, each haYing a predetermined width parallel to the stack axis and a section end~ The internal electrode sections of each internal electrode 32 are arranged at a predetermined distance.
The internal electrcde 32 preferably co~.prises a conductor piece 66 on the peripheral surface of the stack in contact with the section er.ds of the respective internal electrode sections.
The conductor piece or pieces 66 pro~ide a part of the peripheral end. The first external electrode 33 is formed by soldering or otherwise attaching a lead wire either to ~he conductor piece 66 of alternate ones of the internal electrodes 32 or to those of the internal electrode sections of the alternate ones of the internal electrodes 32 which are placed on the peripheral surface, The second ex~ernal electrodç 34 is formed by similarly connecting another lead wire to the peripheral ends o* others of the internal electrodes 3Z. It is possible to form a pair of such conductor pieces in contact with both ends of each internal electrode section for each internal electrode 3Z, Turning to Fig, 18, a green sheet piece 67 is for use ir. manufacturin~ an electrostrictive element of the structure ~L ~7D~
illustrated ~ith reference to Figs, 16 and 17, Platinum paste is printed in stripes on the grean sheet piece as exemplified at 68, The element is manufactured by stacking a predetermined number, such as thirty qheets, of the green sheet pieces 67 with 3 the platinum paste stripes 68, rendering the lamination integral in a hot prRss, and subsequently sintering the integral lamination.
The platinum paste stripes 68 provide the internal electrode sections of the respective intexnal electrodes 32. The gree~
sheet portions bet~een layers of the internal electrode sections provide the electrostricti~e sections 31 ~hich are continuous as described aboYe. The green sheet pieces 67 with the printed stripes 68 enable the element to be readily manufactured ~ith a smaller number of green sheet pieces as compared with the elements described in connection with Examples I through VI as will shortly become clear.
As Example VII, electrostrictive elements ~ere ~anufactured as follows, Green sheet pieces were manufactured as in Example I, Each green sheet piece was about 3 mm ~ide;, 10 ~ long, and 100 microns thick, Platinum paste was scrèen pr~nted on each ~reen sheet pi~ce, Each platinu~ paste strlpe 68 (Fig. 18) had P ~idth selected between 20 and 30 microns. Each blank area lef'l between two adjacent platinum paste stripes 68 had a width whish was selected between 20 and 30 microns. Thirty green sheet pieces ~ith the printed stripes, ~ere stacked for each electrostxic-ti~e element with the plat~num pa~te stripes printed on bothsurfaces of the green sheet piece which was to be placed at an end of the lamlnation, It is to be noted in this Gonnect~on ; that a stack and an axi~ of stack oftan referred to in the instant 3~
specification, should refer to a stack of the electrostrictive sections ~1 (Figs, 1, 3, and the like) rather than to a stack or lamination of the green sheet pieces 67 under consideratio~.
The stacked green sheet pieces 67 uere processed as described in connection Hith Example I, Silver paste wa~ printed on the peripheral surface of each element and ~as fired into the conductor pieces 66 (Fig. 17), It ~as readily possible to ~anufacture an electrostrictive element in which a great number of electrostric-tive sections 31 ~ere defined between the inte~nal electrode~
~2, Referring to Fig, 19, an electro6trictive element according to a sixth embodiment of th~s invention comprises similar part~
designated by like reference nu~erals. The internal s~ructure may be similar to that described in connection with the conventional electrostrictive element ~ith reference to Fig.6 1 and 2. It is, houever, to be noted that those parts of the electrostrictiYe section~ 31 (Flg. 1) are removed at selected heights of the stack which do not contribute to the electro~trie~iv~ effect, By way of example, indents or groove~ 71 are formëd OD the peripheral surface, Each indent 71 may be formed along the whole periphery of the peripheral surface by a diamond cutter, When attention is dlrected to a ~irst peripheral part defined by ths bottom of each indent 71, it is understocd that the internal electrode outline of each internal electrode 32 (Fig, 1) is approximately congruent ~ith an outline ~hich the first peripheral part has perpPndicular to the stack axis and which may again be called the predetermined outline, ~he peripheral surface further comprises second peripheral parts from which ., each indent 71 is recessed to define the first peripheral part, Each lnternal electrode 32 has an end on the second peripheral part as Hill be understood from Figs. 1 and 2. In order that even a part of the internal electrod~s 32 may not be removed, it ~s preferred that each indent ~1 be formed only partly along the periphery. For exemple, each indent 71 may be formed in two parts along the Ride surfaces depicted in Fig. 2 at the tsp and ths bottom of ~he figure~
A~ Example VIII, electrostrictiYe elements ~ere manufactured like the elements of Re~erence I except that inde~t~ were machined by a diamond cutter along the whole periphery after the first and the second external electrodes 33 and 34 (Fig. 19) were formed.
$ach indent 71 was 0.1 mm wide in the direction parallel to the stack axis and 0.1 mm deep perpendicularly of the axis. The center to center dlstance be~ween tho adjacent indents 71 wa~
2.0 mm, Parts into which the external electrodes 33 and 34 were divided by each indent 71, were connected together by lead wires, Each internal electrode area was 84/o of a cross-sectional area which the above-described second peripheral parts had in common.
Turning to Eig. 20, measurements were carrled out for the life and the maximum displacement of the eleotrostrictiv~
elements of Example VIII and of Reference I as described in connection with Fig, 5, The life was qu1te unexpectedly improved as shown by an upper line 72 for the elementæ of Example VIII. The max~mum displacement was 1.9 microns and waæ a little improved as Gompared with that attalned by the slement~ of Reference I and depicted by the lower ~in0 42 as in Flg, 5.
1;~0~i~3 Turning further to Fig. 21, the depende~cy of di~place~ent on the applied Yoltage ~as tested as described in conjunct~on with Fig. 6 for the elements of Eaxmple VIII and of Reference I. The results for the elements of EXample VIII are illustrated by an upper curve 74. Those for the Reference I are shoHn by the lower curve 44 a3 in Fig. 6.
Referring no~ to Fig, 22, an electrostrictive element according to a seventh embodiment of this in~ention is ~lmilar to that lllustrated with reference to Fi~s, 3 and 4. The first exter~al electrode 33 comprises fir3t insulating layer portions 76 on a first area 46 (Fig, 8) to cover the respective peripheral ends of the above-mentioned others of the internal electrodes 32 leaving first area portion~ uncovered on the first area 46 between the insulating layer poxtions 76. The second external electrode 34 comprises second insulating layer portions 77 on a second area 47 (F~g. 8) to co~er the respectiYe pertpheral ends of the above-mentiuned alternate ones of the internal alectrodes , 32 leaYing second area portions on the,sec,ond area 47 between . . , the second insulating layer portions j~. The ~irst external electrode 33 further comprises a f~rst condu¢tive layer 78 on the first insulating layer portions 76 a~ld on the first area portion~, The second external electrode 34 further comprises a second conductive layer 79 on the second insulating layer portions 7? and on the ~econd area portions, It is ~ith this possible to reaaily and stably for~ the fir~t and the second external electrodes 33 and 34.
As Example IX, electrostrictive elementa were ~anufactured like the element~ of Example I. The inSffrnal stxucture ~as as ~36~
~3 de cribed ~ith reference to Fig. 22, Tha integral stack of green sheet pleces with prints, was sintered at about 1250C for one hour. Epoxy re in was screen printed to provide the first and the second insulating layer portions 76 and 7~. The first and the second conductive layers 78 and 79 ~ere formed by evaporation.
It was very readily feasible to form the first and the second external electrodes 33 a~d 34 in stable contact with the pertinent ones of the internal electrodes 320 Turning to Fig~ 23, an electrostrictive elemen~ according -to an eiehth embodiment of this lnvention comprises similar parts designated by llke reference numerals. First and second layer portions 81 and 82 of an opto~setting resinous material, such as a photoresist material, are substituted for the first and the second insulating layer portions 76 and 77, respectiYely, The resinous material is photosensitive. Some of such materials become insoluble in a solvent at portions irradiated with rays.
Others of the m~terials become insoluble in a solvent at other portions, As Example X, electrostrictiveielements were ~anufactured like the elements of Example IX. After the sinterlng procesfi, a resinous material which becomes insoluble at the po~tions exposed to ultra~ilot rays, was applied onto the peripheral surface in two stripes along a first and a second area of each element.
A mask wa~ formed on each ~tripe, On the fir~t area, the mask was formed to cover ~he stripe at portions at which the peripheral ends cf alternate ones of the internal electrode~ 32 (Fig. 23) ~ere expo~ed oa the peripheral surfacç. On the second area, the mask was formed to cover the strlpe at portions at ~hich the peri~heral ends of other internal electrodes are exposed.
UncoYered portions of the stripes were i~radiated by ultraviolet rays. Those portions of the stripes which ~ere under the ma~ks and not irradiated by the ultraviolet rays, ~ere removed together with the overlying masks by a solvent, The remaining portions o~ the stripes were cured at a temper~ture of about 900DC to become the layer portions 81 and 82. A metal layer was evaporated to~ards each of the first and the second areas to provide the conductive layers 78 and 79. It was very easy to insure stable connection of the first and the second external electrodes 33 and 34 to the pertinent ones of the internal electrodes 32.
Turning further to r`ig, 24, an electrostrictive element according to a ninth embodiment of this invention is similar in structure to those illustrated uith reference to Figs. 22 and 23. Instead of the insulating layer portions ~6 and 77 or 81 and 82, first metal layer portions 83 are formed ~n the first area 46 in contact with the respective peripheral ends of alternate ones of the internal electroles 32, On the~second area 4? . second metal layer portion~ 84 are formed in cohtàct ~ith the resp~ctive peripheral ends of other internal electrodes. As described in connection with Fi~s. 3 and 4, first and second lead ~ires 86 and 87 are soldered or other~ise connected to the ~etal layer portions 83 and 84 on thP first and the ~econd areas ~6 and 47, respectiYely. It is now understood that the first external electrode 33 comprises the first metal layer portions 83 and the first lead wire 86 and the second external electrode 34, the second metal layer portions 84 and the second lead wire 87, It is po3sible to raise the efficiency of production when the lead wires 86 and 87 are connected to the metal layer portions 83 and-84 either by thermocompression bonding or ultrasonic bonding, both kno~n in the art of manufacturing IC'~, As Example XI, electrostrictive elemen~s Here manufactured like the elements of Example IX~ After the sintering process, the first and the second metal layer portions 83 and 84 (Fig.
24) were formed ~y firing silver paste. E~aporation of aluminium or gold was equally well effective in manufacturing the metal layer portions 83 and 84.
Referring back to Figs. 3 and 4, an electrostrictive element accoraing to a tenth embodiment of this in~ention is similar in structure to that illustr;ated with reference theretoO
Each internal electrode 32 is, ho~ever, made of an electroconductive material which consists essentially of a metal, such as platinum or palladium, and up to 60~/o by weight of the electrostrictive material of whlch the electrostrictive sections 31 are made.
It was already known in the art of manufacturing stacked chip capacitors that electrodes made of a ~etal do not tenaciously adhere to ceramic pieces among which the electrodes are interposed and that the strength of adhesion between each ceramic piece and the electrodes is improved when po~der of the ceramic material is included in the electrodes ~o as to ~ake the electrodes ha~e nearly the same coeff`icien* of thermal expansion as the ceramic piece. Although similar in structure, it has not yet been confirmed as regards multilayer electrostrictive elements whether or not inclusion of an electrostrictiYe ~aterial in the lnternal electrodes ~ould improYe the strength of adhesion bet~een the electrostrictiYe ~; sections and the internal electrodes because each multilayer JL~
electrostricti~e element used either in a printer head or in a relay, is subjected to an appreciably great amount of elon~ation a great number of times in the direction of stack of the electrostric-tive sections and the internal electrodes. As ~ill presently become clear, it has no~ been confirmed that an electrostr~ctive element of ths type being illustrated, is very excellent as regards the strength of adhesion in questionO
As Example XII, electrostrictiYe element ~ere manufactured as desc~ibed in connection ~ith the elements of Example I. Ths platinum paste was, ho~eYer, applied onto the green sheet pieces with the presintered po~der added thereto ln various proportions.
The mixture of the platinum paste and the presintered powder was successfully sintered into the material of the internal electrodes during the sintering process.
1~ Referring to Fig. 25, the life was tested by the use of a pulse sequence which is similar to the 3equence described in conjunction with Fig. 5 except that the amplitude of the sinusoidal wave was 400 volts rather than 250 volts. -~he curve shows the relationship bet~een the life and the percèntage by weight of the electrostrictive material. As in Fig. 5, the life was measured by the number of pulses which gavæ riss to cracks or other mechanical damages ln the electrostrictive elements.
Turning to Fig, 26, the maximum d~splace~ent ~as measured for the ~lements of Example XII. The curve sho~s the relationship between the ~axlmum displacement and the psrcentage by weight of the electrostrictive material, A seen from Figs. 25 and 26, an increase in the co~tent of the electrostrictive mat0rial ls effsct1ve in lengthening ., the life. Despite the relatively high voltage of 400 Yolts, the life exceeded one hundred million pulses when the content was in excess of 20/o by weightO The content beyond 30/o by weight, howev~r, tended to decrease the maxlmum displacement.
When the content ~as 600/o by weight, the maximum displacement decreased to ~bout a half, It is believed that this results from a decrease in an effective area of each internal electrode.
Summarizi~g, the content should be 600~o by ~eight or less and should most preferably be selccted between 20/o and 30/o by ~eight. It is to be noted that a zero content of the electrostric-tive material corresponds to the electrostricti~e element of the type illustrated with reference to Figs~ 3 and 4.
Turning back to Figs. 3 and 4 again9 an electrostrictive element according to an eleventh embodiment of this in~ention has the structure illustrated ~ith reference thereto, Each internal electrode 32 is, however, made of an electroconductive material which consists essentially of a metal, such as platinum or palladium, and an additional electrostrictiYe material ~hich can be sintered at a temperature lo~er than the electrostri^tive material of ~ the electrostrictiYe sections 31, It is believed that the additional electrostricti~e material is better than the material of the electrostrictivs sections 31 because the additional electrostrictive material is at least partly turned into liquid phase during the ~interin~ process, As Exampl~ XIII, electrostrictive elements were manufactured as described in conjunction ~ith the e~ements of Example I except for the following. Green sheet pieces were manufactured by the use of first presintered powder consisting essentially of lead ?
magnesium niobate and lead titanate in a mol ratio of 65 to 35.
The presintering was carried out at 850C for two hours. Second presintered powder was prepared, ~hich consisted essent1ally of lead magnesium niobate and lead titanate in a mol ratio of 9 to 1 as described in connection with Examples I through XII.
An electroconductive material was prepared by adding the second presintered powder to platinum paste in variou~ proportions, Sintering of stacks of the predetermined dimensions was carried out at 1280~C for one hour, As ~eference IIi electrostrictive elements were ~2nufactured like the elements of Example XII. The first presintered poHder ~as used only for the electrostrictive sections, Sintering was carried out at 1280C for one hour as in Example XIII. It is to be noted that the elements of Reference II as herein called, are electrostrictl~e elements according to an aspect of this invent~on and are not conv~ntional ëlectrostrictiYe elements, Turning to Fig. 27, the life was tested a~ described with reference to ~ig, 25. An upper CUrVQ,88 shows the llfe of the elements of Exanlple XIII for various contents of an electrostric-t~e ~aterial into which the second presintered powder was sinteredin the internal electrodes. A lo~er curve 89 likewise shows the l~fe fsr the ~lement~ o~ Reference II, It was confirmed that the content of an electrostrictive material of a lo~er sintering temperature, should preferably be selected between 0 and ~Q/o by weight because a higher content tended to reduce the ~axi~u~
displacement. It ~as furthermore Yound that the particle size of the presintered powder should preferably be up to 1 or 2 microns, 6~
~1 , Referring to Figs. 3 and 4 once again, an electrostricti~e element according to a twelfth embodiment of this invention is similar in structure, Instead of a single metal or an alloy, each lnternal electrode 32 is made of an electroconductive material 5 which consists essentially of platinum or palladium and up to 10/o by weight of glass, As Example XIV, electrostrictive elements were manufactured like those of Example XII. Zero to 20~/o by Height of soda glass was used instead of the presintered powder on coating the green sheet pieces.
Turning to Fig, 28, the life was tested as described in conjunction ~ith Fig, 25 for the elements of Example XIV.
When the internal electrodes did not inolude glass like the elements of Example I, the li~e for the pulses of the amplitude of 400 volts was of the order of two million pulses. It is clear that the life ~as astonishingly lengthened when the content of glass was 2/o by Height or more, Finally referring to ~'ig, 29, th~ maximum displacement was measured as described in connection with Fig. 26. When the content of glass was 8/o by weight, the maximum displacement showed a tendency of gradual decrease. When the content was 10/o by weight, the maximum displace~ent decearesed to about a half, While this in~ention has thus far been described ~ith reference to the accompanying drawlng, it willnow readily be possible for one skilled in the art to carry this in~ention into effect in ~arious other ~anners, ~'or instance, ths external electrodes 33 and 34 or the conductor rods 64 and 65 may not necessarily be parallel to the stack axis but may haYe a helical or the like form. Addition of the electrostrictive ~aterial or glass to the ~nternal electrod~s 32 is equally ~ell applicable with excellent results to the electrostrictive elzments illustrated ~ith reference to Figs. ? and 8 and othereD Use of the insulating layer portions 76 and 77 or 81 and 82 or of the metal layer portions 83 and 84; is preferable for ea~y and stzble connection of the external electrodes 33 and 34 ~ith the inte~nal electrodes 32 also ~hen the peripheral ends of the respzctive internal electrodes 32 are entirely situated on the peripheral surface of the ~tack as described in conjunction ~ith Fig. 11 or Figs, 16 and 17.
Turning to Eig. 20, measurements were carrled out for the life and the maximum displacement of the eleotrostrictiv~
elements of Example VIII and of Reference I as described in connection with Fig, 5, The life was qu1te unexpectedly improved as shown by an upper line 72 for the elementæ of Example VIII. The max~mum displacement was 1.9 microns and waæ a little improved as Gompared with that attalned by the slement~ of Reference I and depicted by the lower ~in0 42 as in Flg, 5.
1;~0~i~3 Turning further to Fig. 21, the depende~cy of di~place~ent on the applied Yoltage ~as tested as described in conjunct~on with Fig. 6 for the elements of Eaxmple VIII and of Reference I. The results for the elements of EXample VIII are illustrated by an upper curve 74. Those for the Reference I are shoHn by the lower curve 44 a3 in Fig. 6.
Referring no~ to Fig, 22, an electrostrictive element according to a seventh embodiment of this in~ention is ~lmilar to that lllustrated with reference to Fi~s, 3 and 4. The first exter~al electrode 33 comprises fir3t insulating layer portions 76 on a first area 46 (Fig, 8) to cover the respective peripheral ends of the above-mentioned others of the internal electrodes 32 leaving first area portion~ uncovered on the first area 46 between the insulating layer poxtions 76. The second external electrode 34 comprises second insulating layer portions 77 on a second area 47 (F~g. 8) to co~er the respectiYe pertpheral ends of the above-mentiuned alternate ones of the internal alectrodes , 32 leaYing second area portions on the,sec,ond area 47 between . . , the second insulating layer portions j~. The ~irst external electrode 33 further comprises a f~rst condu¢tive layer 78 on the first insulating layer portions 76 a~ld on the first area portion~, The second external electrode 34 further comprises a second conductive layer 79 on the second insulating layer portions 7? and on the ~econd area portions, It is ~ith this possible to reaaily and stably for~ the fir~t and the second external electrodes 33 and 34.
As Example IX, electrostrictive elementa were ~anufactured like the element~ of Example I. The inSffrnal stxucture ~as as ~36~
~3 de cribed ~ith reference to Fig. 22, Tha integral stack of green sheet pleces with prints, was sintered at about 1250C for one hour. Epoxy re in was screen printed to provide the first and the second insulating layer portions 76 and 7~. The first and the second conductive layers 78 and 79 ~ere formed by evaporation.
It was very readily feasible to form the first and the second external electrodes 33 a~d 34 in stable contact with the pertinent ones of the internal electrodes 320 Turning to Fig~ 23, an electrostrictive elemen~ according -to an eiehth embodiment of this lnvention comprises similar parts designated by llke reference numerals. First and second layer portions 81 and 82 of an opto~setting resinous material, such as a photoresist material, are substituted for the first and the second insulating layer portions 76 and 77, respectiYely, The resinous material is photosensitive. Some of such materials become insoluble in a solvent at portions irradiated with rays.
Others of the m~terials become insoluble in a solvent at other portions, As Example X, electrostrictiveielements were ~anufactured like the elements of Example IX. After the sinterlng procesfi, a resinous material which becomes insoluble at the po~tions exposed to ultra~ilot rays, was applied onto the peripheral surface in two stripes along a first and a second area of each element.
A mask wa~ formed on each ~tripe, On the fir~t area, the mask was formed to cover ~he stripe at portions at which the peripheral ends cf alternate ones of the internal electrode~ 32 (Fig. 23) ~ere expo~ed oa the peripheral surfacç. On the second area, the mask was formed to cover the strlpe at portions at ~hich the peri~heral ends of other internal electrodes are exposed.
UncoYered portions of the stripes were i~radiated by ultraviolet rays. Those portions of the stripes which ~ere under the ma~ks and not irradiated by the ultraviolet rays, ~ere removed together with the overlying masks by a solvent, The remaining portions o~ the stripes were cured at a temper~ture of about 900DC to become the layer portions 81 and 82. A metal layer was evaporated to~ards each of the first and the second areas to provide the conductive layers 78 and 79. It was very easy to insure stable connection of the first and the second external electrodes 33 and 34 to the pertinent ones of the internal electrodes 32.
Turning further to r`ig, 24, an electrostrictive element according to a ninth embodiment of this invention is similar in structure to those illustrated uith reference to Figs. 22 and 23. Instead of the insulating layer portions ~6 and 77 or 81 and 82, first metal layer portions 83 are formed ~n the first area 46 in contact with the respective peripheral ends of alternate ones of the internal electroles 32, On the~second area 4? . second metal layer portion~ 84 are formed in cohtàct ~ith the resp~ctive peripheral ends of other internal electrodes. As described in connection with Fi~s. 3 and 4, first and second lead ~ires 86 and 87 are soldered or other~ise connected to the ~etal layer portions 83 and 84 on thP first and the ~econd areas ~6 and 47, respectiYely. It is now understood that the first external electrode 33 comprises the first metal layer portions 83 and the first lead wire 86 and the second external electrode 34, the second metal layer portions 84 and the second lead wire 87, It is po3sible to raise the efficiency of production when the lead wires 86 and 87 are connected to the metal layer portions 83 and-84 either by thermocompression bonding or ultrasonic bonding, both kno~n in the art of manufacturing IC'~, As Example XI, electrostrictive elemen~s Here manufactured like the elements of Example IX~ After the sintering process, the first and the second metal layer portions 83 and 84 (Fig.
24) were formed ~y firing silver paste. E~aporation of aluminium or gold was equally well effective in manufacturing the metal layer portions 83 and 84.
Referring back to Figs. 3 and 4, an electrostrictive element accoraing to a tenth embodiment of this in~ention is similar in structure to that illustr;ated with reference theretoO
Each internal electrode 32 is, ho~ever, made of an electroconductive material which consists essentially of a metal, such as platinum or palladium, and up to 60~/o by weight of the electrostrictive material of whlch the electrostrictive sections 31 are made.
It was already known in the art of manufacturing stacked chip capacitors that electrodes made of a ~etal do not tenaciously adhere to ceramic pieces among which the electrodes are interposed and that the strength of adhesion between each ceramic piece and the electrodes is improved when po~der of the ceramic material is included in the electrodes ~o as to ~ake the electrodes ha~e nearly the same coeff`icien* of thermal expansion as the ceramic piece. Although similar in structure, it has not yet been confirmed as regards multilayer electrostrictive elements whether or not inclusion of an electrostrictiYe ~aterial in the lnternal electrodes ~ould improYe the strength of adhesion bet~een the electrostrictiYe ~; sections and the internal electrodes because each multilayer JL~
electrostricti~e element used either in a printer head or in a relay, is subjected to an appreciably great amount of elon~ation a great number of times in the direction of stack of the electrostric-tive sections and the internal electrodes. As ~ill presently become clear, it has no~ been confirmed that an electrostr~ctive element of ths type being illustrated, is very excellent as regards the strength of adhesion in questionO
As Example XII, electrostrictiYe element ~ere manufactured as desc~ibed in connection ~ith the elements of Example I. Ths platinum paste was, ho~eYer, applied onto the green sheet pieces with the presintered po~der added thereto ln various proportions.
The mixture of the platinum paste and the presintered powder was successfully sintered into the material of the internal electrodes during the sintering process.
1~ Referring to Fig. 25, the life was tested by the use of a pulse sequence which is similar to the 3equence described in conjunction with Fig. 5 except that the amplitude of the sinusoidal wave was 400 volts rather than 250 volts. -~he curve shows the relationship bet~een the life and the percèntage by weight of the electrostrictive material. As in Fig. 5, the life was measured by the number of pulses which gavæ riss to cracks or other mechanical damages ln the electrostrictive elements.
Turning to Fig, 26, the maximum d~splace~ent ~as measured for the ~lements of Example XII. The curve sho~s the relationship between the ~axlmum displacement and the psrcentage by weight of the electrostrictive material, A seen from Figs. 25 and 26, an increase in the co~tent of the electrostrictive mat0rial ls effsct1ve in lengthening ., the life. Despite the relatively high voltage of 400 Yolts, the life exceeded one hundred million pulses when the content was in excess of 20/o by weightO The content beyond 30/o by weight, howev~r, tended to decrease the maxlmum displacement.
When the content ~as 600/o by weight, the maximum displacement decreased to ~bout a half, It is believed that this results from a decrease in an effective area of each internal electrode.
Summarizi~g, the content should be 600~o by ~eight or less and should most preferably be selccted between 20/o and 30/o by ~eight. It is to be noted that a zero content of the electrostric-tive material corresponds to the electrostricti~e element of the type illustrated with reference to Figs~ 3 and 4.
Turning back to Figs. 3 and 4 again9 an electrostrictive element according to an eleventh embodiment of this in~ention has the structure illustrated ~ith reference thereto, Each internal electrode 32 is, however, made of an electroconductive material which consists essentially of a metal, such as platinum or palladium, and an additional electrostrictiYe material ~hich can be sintered at a temperature lo~er than the electrostri^tive material of ~ the electrostrictiYe sections 31, It is believed that the additional electrostricti~e material is better than the material of the electrostrictivs sections 31 because the additional electrostrictive material is at least partly turned into liquid phase during the ~interin~ process, As Exampl~ XIII, electrostrictive elements were manufactured as described in conjunction ~ith the e~ements of Example I except for the following. Green sheet pieces were manufactured by the use of first presintered powder consisting essentially of lead ?
magnesium niobate and lead titanate in a mol ratio of 65 to 35.
The presintering was carried out at 850C for two hours. Second presintered powder was prepared, ~hich consisted essent1ally of lead magnesium niobate and lead titanate in a mol ratio of 9 to 1 as described in connection with Examples I through XII.
An electroconductive material was prepared by adding the second presintered powder to platinum paste in variou~ proportions, Sintering of stacks of the predetermined dimensions was carried out at 1280~C for one hour, As ~eference IIi electrostrictive elements were ~2nufactured like the elements of Example XII. The first presintered poHder ~as used only for the electrostrictive sections, Sintering was carried out at 1280C for one hour as in Example XIII. It is to be noted that the elements of Reference II as herein called, are electrostrictl~e elements according to an aspect of this invent~on and are not conv~ntional ëlectrostrictiYe elements, Turning to Fig. 27, the life was tested a~ described with reference to ~ig, 25. An upper CUrVQ,88 shows the llfe of the elements of Exanlple XIII for various contents of an electrostric-t~e ~aterial into which the second presintered powder was sinteredin the internal electrodes. A lo~er curve 89 likewise shows the l~fe fsr the ~lement~ o~ Reference II, It was confirmed that the content of an electrostrictive material of a lo~er sintering temperature, should preferably be selected between 0 and ~Q/o by weight because a higher content tended to reduce the ~axi~u~
displacement. It ~as furthermore Yound that the particle size of the presintered powder should preferably be up to 1 or 2 microns, 6~
~1 , Referring to Figs. 3 and 4 once again, an electrostricti~e element according to a twelfth embodiment of this invention is similar in structure, Instead of a single metal or an alloy, each lnternal electrode 32 is made of an electroconductive material 5 which consists essentially of platinum or palladium and up to 10/o by weight of glass, As Example XIV, electrostrictive elements were manufactured like those of Example XII. Zero to 20~/o by Height of soda glass was used instead of the presintered powder on coating the green sheet pieces.
Turning to Fig, 28, the life was tested as described in conjunction ~ith Fig, 25 for the elements of Example XIV.
When the internal electrodes did not inolude glass like the elements of Example I, the li~e for the pulses of the amplitude of 400 volts was of the order of two million pulses. It is clear that the life ~as astonishingly lengthened when the content of glass was 2/o by Height or more, Finally referring to ~'ig, 29, th~ maximum displacement was measured as described in connection with Fig. 26. When the content of glass was 8/o by weight, the maximum displacement showed a tendency of gradual decrease. When the content was 10/o by weight, the maximum displace~ent decearesed to about a half, While this in~ention has thus far been described ~ith reference to the accompanying drawlng, it willnow readily be possible for one skilled in the art to carry this in~ention into effect in ~arious other ~anners, ~'or instance, ths external electrodes 33 and 34 or the conductor rods 64 and 65 may not necessarily be parallel to the stack axis but may haYe a helical or the like form. Addition of the electrostrictive ~aterial or glass to the ~nternal electrod~s 32 is equally ~ell applicable with excellent results to the electrostrictive elzments illustrated ~ith reference to Figs. ? and 8 and othereD Use of the insulating layer portions 76 and 77 or 81 and 82 or of the metal layer portions 83 and 84; is preferable for ea~y and stzble connection of the external electrodes 33 and 34 ~ith the inte~nal electrodes 32 also ~hen the peripheral ends of the respzctive internal electrodes 32 are entirely situated on the peripheral surface of the ~tack as described in conjunction ~ith Fig. 11 or Figs, 16 and 17.
Claims (4)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A multilayer electrostrictive element for dimensionally changing in a first direction in response to electrical pulses and for withstanding repeated application of said pulses, said element comprising: a stack formed by a plurality of electro-strictive sections of an electrostrictive material and a plurality of internal electrodes sandwiched between said electrostrictive sections, said stack having a peripheral surface defining a cross-sectional area of said stack, each of said internal electrodes having peripheral ends on said peripheral surface and each of said internal electrodes having an internal electrode area which is substantially equal to a cross-sectional area of said stack, first means for electrically connecting alternate ones of said internal electrodes together without connecting others of said internal electrodes, said first means including first insulating layer portions on a first area of said peripheral surface for cov-ering respective peripheral ends of said others of said internal electrodes while leaving portions of said first area uncovered, each said first insulating layer portion covering the peripheral end of a respective internal electrode while extending in said first direction substantially less than the entire distance be-tween said respective first electrode and either adjacent first electrode to leave uncovered substantial portions of the sur-faces of said electrostrictive sections in said first area of said peripheral surface, and a first conductive layer continuously for-med on both said first insulating layer portions and on said uncovered portions of said first area; and second means for elec-trically connecting said others of said internal electrodes together, said second means including insulating layer portions on a second area of said peripheral surface for covering respec-tive peripheral ends of said alternate ones of said internal elec-trodes while leaving portions of said second area uncovered, and a second conductive layer continuously formed on both said second insulating layer portions and on said uncovered portions of said second area.
2. An electrostrictive element as claimed in Claim 1, where-in said first means comprises first layer portions of a photo-sensitive resin on a first area of said peripheral surface to cover the respective peripheral ends of said others of the internal electrodes leaving first area portions uncovered on said first area and a first conductive layer on said first layer portions and on said first area portions, said second means comprising second layer portions of said photosensitive resin on a second area of said peripheral surface to cover the respective peripheral ends of said alternate ones of the internal electrodes leaving second area portions uncovered on said second area and a second conductive layer on said second layer portions and on said second area portions.
3. An electrostrictive element as claimed in Claim 1, where-in each internal electrode is made of an electroconductive material consisting essentially of a metal and an additional electrostric-tive material of a sintering temperature which is lower than a temperature of sintering the electrostrictive material of said electrostrictive sections.
4. An electrostrictive element as claimed in Claim 1, where-in said electroconductive material includes up to 40% by weight of said additional electrostrictive material.
Applications Claiming Priority (24)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP57079039A JPS58196079A (en) | 1982-05-11 | 1982-05-11 | Electrostrictive effect element |
| JP79035/1982 | 1982-05-11 | ||
| JP57079038A JPS58196078A (en) | 1982-05-11 | 1982-05-11 | Electrostrictive effect element |
| JP79036/1982 | 1982-05-11 | ||
| JP57079034A JPS58196074A (en) | 1982-05-11 | 1982-05-11 | Electrostrictive effect element |
| JP57079035A JPS58196075A (en) | 1982-05-11 | 1982-05-11 | Electrostrictive effect element |
| JP57079037A JPH065794B2 (en) | 1982-05-11 | 1982-05-11 | Electrostrictive effect element |
| JP57079036A JPH0671102B2 (en) | 1982-05-11 | 1982-05-11 | Electrostrictive effect element |
| JP79038/1982 | 1982-05-11 | ||
| JP79039/1982 | 1982-05-11 | ||
| JP79037/1982 | 1982-05-11 | ||
| JP79034/1982 | 1982-05-11 | ||
| JP78445/1982 | 1982-05-12 | ||
| JP78444/1982 | 1982-05-12 | ||
| JP57078448A JPS58196072A (en) | 1982-05-12 | 1982-05-12 | Electrostrictive effect element |
| JP57078444A JPS58196068A (en) | 1982-05-12 | 1982-05-12 | Electrostrictive effect element |
| JP57078445A JPS58196069A (en) | 1982-05-12 | 1982-05-12 | Electrostrictive effect element |
| JP57078447A JPS58196071A (en) | 1982-05-12 | 1982-05-12 | Electrostrictive effect element |
| JP57078449A JPS58196073A (en) | 1982-05-12 | 1982-05-12 | Electrostrictive effect element |
| JP78449/1982 | 1982-05-12 | ||
| JP57078446A JPS58196070A (en) | 1982-05-12 | 1982-05-12 | Electrostrictive effect element |
| JP78447/1982 | 1982-05-12 | ||
| JP78448/1982 | 1982-05-12 | ||
| JP78446/1982 | 1982-05-12 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1206193A true CA1206193A (en) | 1986-06-17 |
Family
ID=27583373
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000427828A Expired CA1206193A (en) | 1982-05-11 | 1983-05-10 | Multilayer electrostrictive element which withstands repeated application of pulses |
Country Status (5)
| Country | Link |
|---|---|
| US (1) | US4523121A (en) |
| EP (1) | EP0094078B1 (en) |
| AU (1) | AU553391B2 (en) |
| CA (1) | CA1206193A (en) |
| DE (1) | DE3378393D1 (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2487165A (en) * | 1946-10-10 | 1949-11-08 | August E Miller | Crystal electrode |
| US2894317A (en) * | 1954-06-07 | 1959-07-14 | Spence T Marks | Method for constructing a barium titanate blast velocity gauge |
| US3154700A (en) * | 1961-01-09 | 1964-10-27 | Joseph T Mcnaney | Piezoelectric transducer force to motion converter |
| US3179826A (en) * | 1961-09-14 | 1965-04-20 | Trott Winfield James | Piezolelectric assembly |
| CH429228A (en) * | 1964-12-10 | 1967-01-31 | Kistler Instrumente Ag | Piezoelectric installation body for installation in a piezoelectric transducer |
| US3349259A (en) * | 1965-05-27 | 1967-10-24 | Kistler Instr Corp | Piezoelectric pressure transducer |
| FR96113E (en) * | 1967-12-06 | 1972-05-19 | Ibm | Semiconductor device. |
| US3521090A (en) * | 1968-03-15 | 1970-07-21 | Us Navy | Piezoelectric transducer with electrically conductive mounting rods |
| US3586889A (en) * | 1968-11-04 | 1971-06-22 | Gco | Means for resiliently mounting transducer elements between a housing and an inertial mass |
| US3686518A (en) * | 1970-09-02 | 1972-08-22 | Clinton S Hartmann | Unidirectional surface wave transducers |
| US3982144A (en) * | 1974-08-23 | 1976-09-21 | The United States Of America As Represented By The Secretary Of The Navy | Directional low-frequency ring hydrophone |
| MX143980A (en) * | 1974-10-03 | 1981-08-17 | Physics Int Co | IMPROVEMENTS TO APPARATUS THAT USES A PLURALITY OF PIEZOELECTRIC DISCS |
| SE436675B (en) * | 1975-08-12 | 1985-01-14 | Ki Politekhnichsky I Im 50 Let | ELECTRIC ENGINE OPERATED BY PIEZOELECTRIC FORCES |
| FR2425599A1 (en) * | 1978-05-10 | 1979-12-07 | Commissariat Energie Atomique | Fluid flow control valve - uses voltage applied across piezoelectric element to lift valve member off seat |
| US4328441A (en) * | 1980-01-31 | 1982-05-04 | Minnesota Mining And Manufacturing Company | Output circuit for piezoelectric polymer pressure sensor |
-
1983
- 1983-05-09 EP EP83104556A patent/EP0094078B1/en not_active Expired
- 1983-05-09 DE DE8383104556T patent/DE3378393D1/en not_active Expired
- 1983-05-10 CA CA000427828A patent/CA1206193A/en not_active Expired
- 1983-05-10 AU AU14422/83A patent/AU553391B2/en not_active Expired
- 1983-05-11 US US06/493,583 patent/US4523121A/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| EP0094078A2 (en) | 1983-11-16 |
| EP0094078B1 (en) | 1988-11-02 |
| AU1442283A (en) | 1983-11-17 |
| US4523121A (en) | 1985-06-11 |
| EP0094078A3 (en) | 1984-09-12 |
| DE3378393D1 (en) | 1988-12-08 |
| AU553391B2 (en) | 1986-07-10 |
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