Adjusting device for microscopic movements

The description relates to an adjusting device 1 for microscopic movements and comprising a carrier element 3 with, fixed on the carrier element 3, drive elements 6a, 6b, 6c which have a piezoelectric transducer which utilises the shear effect and which have a bearing element 5 which rests on the drive elements 6a, b, c. So that such an adjusting device 1, regardless of its position, is able to carry out high-precision reproducible microscopic movements, in particular also movements in a vertical direction being possible while under load, the form and disposition of drive element 6 and bearing element 5 are designed for the performance of a guided microscopic movement. In addition, a pressure applying device 8 is provided which presses the bearing element 5 and the drive element 6 against one another with a predetermined force. Preferably, the pressure applying device comprises at least one magnet 17 which attracts the bearing element 5 with an adjustable force. According to particular embodiments, guided rotary movements are also feasible with the adjusting device according to the invention.

DESCRIPTION 
The invention relates to an adjusting device for microscopic movements, 
with a carrier element with, fixed on the carrier element, at least one 
drive element comprising a piezoelectric transducer which utilises the 
shear effect, and with a bearing element which rests on the drive element. 
An adjusting device for linear or angular displacements of carrier plates 
in relation to base plates is known for example from DE-PS 20 29 715. Such 
adjusting devices comprise spindles, micrometers and screws for performing 
linear and rotary movements. For guiding the carrier plates on the base 
plates, the carrier plates are provided with grooves in which run balls 
for example. 
However, this prior art adjusting device cannot be used for mechanically 
high-precision movement patterns in microtechnique, because the fine 
adjustment desired for these applications cannot be attained by the 
aforesaid mechanical displacement means. 
Known from DE-PS 76 13 73 is a mechanical adjusting device for electron 
microscopes with which however no fine adjustment in the sub-nanometer 
range is possible. Adjustment of the table which has to rest on a sliding 
surface is accomplished by means of adjusting screws which move the table 
against thrust members. The adjustment path is limited by the spring 
travel of the counter-thrust members, the increase in opposing force 
leading to a nonlinear adjustment characteristic as the compression of the 
springs increases. Nor is a reproducible movement possible since a 
laterally clearance-free mounting can be accomplished only with extreme 
difficulty. 
Particularly in the case of scanning tunnel microcroscopy with which 
surface structures can be examined with a resolution in the sub-nanometer 
range are adjustment means required which correspondingly permit of a 
displacement or a rotary movement in the sub-nanometer range. 
In order to cope with these needs, micromanipulators have been developed 
such as are known from DE-PS 36 10 540. Such a micromanipulator is capable 
of microscopic movement of objects in X-, Y- and Z-directions, where the 
object is resting on three hollow cylinder-like piezoelectric movement 
elements. These tiny piezoelectric tubes have on one wall of the cylinder 
a closed electrically conductive coating and on the other wall of the 
cylinder a plurality of electrically insulated conductive partial 
coatings. By applying voltages between the electrically conductive 
coatings, the small piezoelectric tubes can be bent in any desired 
directions. By rapidly bending and straightening the tubes, the object 
placed on these piezoelectric tubes is displaced in a stepwise manner. 
However, this micromanipulator has a number of drawbacks. The movement of 
the object is not reporducible and in particular it is not 
uni-dimensionally guided. This means that during reverse movement of the 
object, the starting point is not attained again but in fact in the case 
of surface examinations in high-resolution microscopy, in which the same 
areas of the surface have to be approached many times in reproducible 
fashion, this is a vital requirement. 
A further disadvantage lies in the fact that the micromanipulator is only 
capable of moving the object horizontally. Movement of the object in a 
vertical plane is not provided for, nor is it possible, since in this case 
the object would not be reliably supported on the piezoelectric tubes. It 
is true that there is mention of the possibility of the object being 
pressed down onto the piezoelectric tubes by a spring but this only 
increases the stability of the arrangement as a whole. Therefore, use in 
any plane other than the horizontal plane is not made possible by it. 
Other obstacles to this are also the minimal loading capacity and in 
particular the minimal lateral stability of the piezoelectric tubes which 
in particular have a tendency to break when they are bent by the applied 
voltage and are loaded at the same time. 
In K. Besocke "Ein neues Konzept fur die Raster-Tunnel-Mikroskopie/A New 
Concept for Scanning Tunnel Microscopy", in a special reprint from the 
1987/88 Annual Report of the Nuclear Research Division of Julich GmbH, pp. 
23 to 31, there is a description of a microadjustment device in which, in 
addition to the use of the piezoelectric tubes such as are known from 
EP-00 27 517, a specimen holder is also used and comprises a bearing ring. 
The supporting surfaces of the piezoelectric tubes are screwed oblique 
planes, so that upon actuation of the piezoelectric tubes, the bearing 
ring is rotated and at the same time performs a movement parallel with the 
piezoelectric tubes. Even this arrangement does not permit of any 
reproducible movements. 
Known from EP 00 27 517 is an adjusting device in which an H-shaped 
piezoelectric member moves along like a worm in a trough-like guide 
member. The construction and control with four-phase driving currents is 
complicated and expensive and also has the drawback that the moving 
piezoelectric member can only accept a very low loading in the direction 
of movement. Where this development is concerned, the piezoelectric member 
can carry little more than its own weight in a vertical direction since 
otherwise there is an uncontrolled sliding of the piezoelectric member in 
the guide arrangement. 
Furthermore, an absolute dimensional precision of the guide member and of 
the piezoelectric member in the micrometer range or even better is 
required. Manufacturing costs are high, therefore. 
Known from the in-house publication "Micro Positioning Systems" of Messrs. 
BURLEIGH INSTRUMENTS is the so-called Inchworm. In a concentric 
disposition within three tube-like piezoelectric elements, two of which, 
by varying their diameters, clamp the movable element while the third one 
moves the cylinder by altering its length. A significant disadvantage of 
this construction is the inadequate security against rotation and the 
necessary manufacturing precision since here again an easily-moving fit in 
the sub-micrometer range is required and this calls for corresponding 
manufacturing costs. 
A so-called XY-Walker is known from Kiyohiko Uozumi "Novel three 
dimensional positioner and scanner for the STM using shear deformation of 
piezo ceramic plates" in the Japanese Journal of Applied Physics, Vol. 27, 
No. 1, January 1988, page L 123 to L 126. On the under side of the object 
to be moved are fixed several piezoelectric transducers of which at least 
two permit a raising of the object while at least two others perform a 
shear movement in order to displace the object sideways. The piezoelectric 
transducers must be so actuated that whenever the object is raised the 
shear movement of the other piezoelectric transducers is performed. This 
shear movement must persist until such time as the object has been lowered 
again and is thus resting on the sheared piezoelectric transducers. 
Afterwards, the sheared piezoelectric transducers are sheared in the 
opposite direction and the entire object is raised again. This adjusting 
device does not offer any reproducible guided movements either and it can 
only be used for horizontal movements. 
Therefore, the object of the present invention is to provide an adjusting 
device which, while being of simple construction and comprising only a few 
component parts, guarantees high-precision and reproducible microscopic 
movements regardless of its position, especially movements under load and 
in a vertical direction being possible. 
This problem is resolved by an adjusting device in accordance with the 
features set out in claim 1. A particular embodiment for rotary movements 
is the object of claim 2. Advantageous further developments are the 
objects of the sub-claims. 
The invention is based on the knowledge that where adjusting devices in the 
micro range are concerned, the driving element and the guide means do not 
have to constitute two separate devices in order to be able to perform a 
guided movement within the micro range. A simple construction of an 
adjusting device for microscopic movements is achieved in that the drive 
elements which comprise piezoelectric transducers with a shear capability 
produce not only the movement of the bearing element but in addition also 
guide the bearing element in the direction of movement. 
According to the invention, only the drive element and the bearing element 
are in their form and disposition constructed for reciprocal mounting and 
for the execution of a guided microscopic movement. The device can be so 
designed that the bearing element or the carrier element performs the 
microscopic movements, as a movable element. 
The adjusting device according to the invention can be constructed to 
perform both linear and also rotary movements. Preferably, by reason of 
its design, the bearing element is adapted to the form and/or disposition 
of the drive element as a safeguard against rotation about the direction 
of movement if it is constructed as a linear adjusting device or against 
displacement if it is constructed as a rotary adjusting device. 
For an adjusting device which performs linear movements, it is in 
particular advantageous for the movable element of be a partially 
cylindrical rod the cylinderal surface of which rests on at least three 
piezoelectric transducers or on a piezoelectric transducer which has three 
supporting surfaces. The three supporting points are preferably disposed 
in the manner of a tripod. 
To ensure a guided movement of the movable element, it is necessary 
according to the range of use for the bearing element and the disposition 
or the form of the driving element(s) to be adapted to one another. The 
shear effect offers the only advantage that the thickness of the 
piezoelectric transducer at right-angles to the adjusting device remains 
constant during deflection and that for an identically applied voltage the 
deflection is independent of the thickness of the transducer. Thus, 
manufacturing tolerances are immaterial and in particular any desired 
configuration is possible and the thicknesses may vary. 
Saving on a separate guide device also reduces the friction losses so that 
the force applied by the piezoelectric transducers can be used entirely 
for moving the movable element. Consequently, yet another movement of the 
movable element is made possible if this element has to be moved in a 
vertical direction and is carrying a load. 
Instead of a partially cylindrical rod, it is also possible to use a rod 
with a polygonal cross-section, and in this case the rod has two of its 
lateral surfaces resting on at least three support points on the drive 
element(s). According to the intended purpose, so it is possible also for 
four or more drive elements to be used. 
A further embodiment envisages the bearing element consisting of a plate 
with a guide groove which is preferably formed by two parallel cylindrical 
rods. 
This bearing element likewise rests on at least three drive elements or one 
drive element with three support points, the bearing element resting on 
two drive elements in the guide groove formed by the two cylindrical rods 
and, with the plate, resting on the third drive element. The two drive 
elements engaging the cylindrical rods ensure an accurate linear guidance, 
while the third drive element takes over a supporting function and 
provides a safeguard against rotation. 
In order to be able to carry out rotary movements, the bearing element is 
in a preferred embodiment constructed as a rotationally symmetrical 
component which has a peripheral surface. It may for example be a cylinder 
or a cone, the drive element and thus also the piezoelectric transducer 
being adapted to the form of the peripheral surface. In order to bring 
about a rotary movement of the bearing element, the drive element is 
polarised in the peripheral direction so that when a voltage is applied to 
the piezoelectric transducer, this latter performs a shearing action in 
the peripheral direction and entrains the bearing element in so doing. 
The carrier element which carries the drive element or elements can, in the 
case of this embodiment, simultaneously take over the function of the 
pressure applying means if it at least partially encloses the drive 
element and is subject to an initial mechanical tension so that the drive 
element presses against the rotationally symmetrical component. 
According to a further embodiment, the bearing element is constructed as a 
turntable. 
This may take the form of a truncated cone the conical surface of which 
rests on at least three piezoelectric transducers which are substantially 
equidistant from one another. According to a further embodiment, the 
bearing element constructed as a turntable has a clearance-free pivot 
bearing and rests on at least one and preferably two drive elements. The 
pivot bearing is preferably a sphere which rests in a conical recess in 
the turntable. The distances from the bearing point to the piezoelectric 
transducers and between the respective piezoelectric transducers are 
preferably substantially equal. In this developed embodiment, the bearing 
and guidance are not produced exclusively by the bearing element and the 
drive element. 
A rotary movement can also be combined with a linear movement. In this 
case, instead of the conical recess in the turntable, a groove can be 
provided in which rests a further drive element which performs the linear 
movement of the turntable. 
The drive elements on which the surface of the turntable rests comprises 
piezoelectric members the shear movement of which acts in various 
directions. A part of the piezoelectric element acts in a radial direction 
while the other part acts in a tangential direction. 
Another essential constituent part of the adjusting device according to the 
invention resides in the pressure applying means which make sit possible 
for the movable element to be fixed, allowing the adjusting device to be 
used in any desired position. The pressure applying means presses the 
bearing element with a preferably adjustable or structurally predetermined 
force against the drive elements. 
The pressure applying means is so disposed that the force exerted by it 
acts at right-angles to the direction of movement of the movable element. 
This embodiment offers the advantage that the maximum travel path of the 
movable element is not limited by the ejection device, as is the case with 
the state of the art. Instead, the entire adjustment path is likewise 
limited by the length of the movable element, while the utmost precision 
and reproducibility are retained. 
So that the pressure applying device does not retard the movement of the 
bearing element, this latter, according to one embodiment, likewise 
comprises at least one piezoelectric transducer which has shear 
capability. This piezoelectric transducer which is part of the pressure 
applying means acts by reason of spring force and presses on the bearing 
element, performing the appropriate shear movement in the same way as the 
other piezoelectric transducers. By virtue of the fact that in this case 
the bearing element rests solely on drive elements, friction losses are 
minimised. The disposition of the spring loaded piezoelectric transducer 
is such that it presses the bearing element against and thus clamps it on 
the drive elements. This ensures that the movable element can be reliably 
secured in any position and that by virtue of the clamping effect the 
movable element can also be loaded in opposition to the direction of 
movement without this leading to an uncontrolled sliding of the movable 
element during the movement process or even when at rest. 
If a partially cylindrical rod or a cross-sectionally polygon rod is used 
as the movable element, the spring loaded piezoelectric transducer 
preferably engages the flat surface of the rod and in this way presses the 
rod against the piezoelectric transducer on which the semicylindrical 
surface of the rod or, if it is of polygonal cross-section, its lateral 
surfaces rest. 
With rod-shaped bearing elements, it has proved to be advantageous for the 
pressure applying means to comprise in addition to the spring loaded 
piezoelectric transducer also a fixed piezoelectric transducer which is 
disposed at a distance from the spring loaded transducer when the spring 
loaded transducer and the additional piezoelectric transducer are disposed 
one beside the other at right-angles to the direction of movement of the 
rod, a rotation of the bar about the longitudinal axis is effectively 
prevented. 
In accordance with a further embodiment, the pressure applying device may 
consist of magnets which are disposed at a distance from the bearing 
element. The magnet or magnets is or are preferably disposed on the fixed 
component between the drive elements and by the forces of magnetic 
attraction they press the bearing element against the drive elements. This 
pressure applying means has the advantage that no additional friction 
losses occur and that the side of the rod remote from the drive elements 
is freely accessible over its entire length. 
By the use of piezoelectric transducers which have shear capability, 
parallelepiped piezoelectric elements can be used which can accept a far 
greater load than for example the small piezoelectric tubes known from the 
state of the art. 
An essential advantage is the compact overall height of the shearing 
piezoelectric elements of less than 1 mm, while the Besocke type tubes 
typically have a length of 10 mm. The result is a substantially improved 
stability in the lateral direction both with regard to force effect and 
also with regard to vibration sensitivity. 
Deflection of the piezoelectric transducers depends upon a material 
constant and upon the applied voltage pulse. To permit large step sizes, 
it may for particular applications be advantageous for a plurality of 
piezoelectric transducers to be disposed on one another because in this 
case the deflections of the individual piezoelectric transducers are added 
to one another. The piezoelectric elements are in each case separated by 
an electrically conductive coating which is needed in order to apply the 
voltage pulse to the piezoelectric elements. 
Since the step size also depends upon the applied voltage pulse, the 
piezoelectric transducers are connected to a control unit which is 
constructed to deliver different voltage pulses. In addition to the value 
of the voltage pulse, also the time pattern of the voltage pulse is 
important. If the voltage is increased slowly (flat pulse flank) until it 
reaches its maximum value, the piezoelectric transducer reacts with a 
correspondingly slow shear movement. In this case, during the shear 
movement of the piezoelectric transducers, the bearing element is 
entrained. If after reaching the maximum voltage value the voltage is 
rapidly removed (steep pulse flank), the piezoelectric transducer returns 
to its starting position at a corresponding speed, the bearing element 
remaining in its position by reason of the mass of inertia. 
The other possibility resides in firstly passing through the steep flank of 
the voltage pulse with the result that the piezoelectric transducer by 
virtue of its rapid shear movement and the mass of inertia of the bearing 
element slides along the bearing element. If then the slow flank of the 
voltage pulse is travelled, then the piezoelectric transducer moves at 
correspondingly low speed back to its starting position, entraining the 
bearing element with it. 
These movement steps can be performed in rapid sequence one after another 
so that even translatory or rotary movements of the order of millimetres 
can be accomplished within a few seconds. Surprisingly, it has been found 
that for the same maximum voltage a more rapid cycle of movements can be 
achieved if it is first the gentle slope of the voltage pulse and only 
then the steep slope of the voltage pulse which is traversed. 
According to the quality of the bearing surface, experience shows that the 
smallest reliable step size is about 20 nm. An even more precise 
positioning can be achieved by utilising the entraining effect if the rate 
of rise of the voltage pattern is not too rapid. 
Thus, over and above stepwise positioning, continuous positioning is 
possible, a relative accuracy of approx. 1 nm being typically possible 
over a total range of some 100 nm up to 1 .mu.m. To this end, the control 
unit is designed with an additional facility for continuous actuation. 
For greater adjustment paths or angles, the absolute positioning accuracy 
of the adjusting device can be considerably increased by integrating a 
path of positioning measurement facility. By feed-back of the path or 
position signal, a predetermined position can be attained precisely. This 
feed-back can be used both for stepwise and also for continuous 
positioning. 
Although the bearing element can rest directly on the piezoelectric 
transducers, it is advantageous in the light of friction losses to provide 
at least one punctiform support. Such a support consists of a ball fixed 
on a ball seating which is in turn disposed on that side of the 
piezoelectric transducer which is towards the bearing element. The ball 
consists of aluminium oxide while the bearing element is preferably made 
from hardened steel. Other combinations of materials may also be used so 
long as the support and the bearing element do not tend to seize under the 
forces which occur. 
The adjusting device (sic!) according to the invention can be combined with 
one another in any desired manner, so that X-, Y-, Z-adjusting devices can 
be provided or even adjusting devices in which a rotary movement can be 
combined with a linear movement or a plurality of rotary movements can be 
combined with one another. 
If an embodiment of adjusting device is chosen in which the carrier element 
serves as a stationary element, then the movable element may be endless. 
This provides particularly an opportunity for the continuous feed of 
material. For example, a soldering or welding wire can be continuously 
supplied with a high level of positioning accuracy.

FIG. 1 shows an adjusting device 1 for linear displacements. As shown in 
FIG. 3, a total of four drive elements 6a, 6b, 6c and 6d are mounted on a 
stationary carrier element 2 which has a base plate 3 and a support arm 4. 
These drive elements comprise a support 27 (see FIG. 9) comprising a ball 
7 and a ball seating 12. Resting on the balls 7 is the movable bearing 
element 5 which can be displaced in the direction of the arrow by means of 
piezoelectric transducers 33 which have a shear capability. 
For fixing the bearing element 5, a pressure applying device 8 is provided 
which is mounted on a support arm 4. On the under side of a movable 
support plate 11 there is fixed a piezoelectric transducer 9b which 
belongs to the pressure applying device and the ball 7 of which presses 
down on the bearing element 5 from above. The force with which the 
piezoelectric transducer 9b presses on the movable element 5 is determined 
by the spring 10 which is biased on the under side of the support arm 4. 
Fixed on the support arm 4 is a further piezoelectric transducer 9a which 
likewise presses on the movable element 5 from above. 
As FIG. 2 shows, the bearing element 5 consists of a semicylindrical rod 
the cylindrical surface 23 of which rests on the balls 7 of the drive 
elements 6a to 6d. The two piezoelectric transducers 9a and 9b of the 
pressure applying device 8 press from above on the flat surface 26 of the 
movable element 5. In this view, the two piezoelectric transducers 9a and 
9b are disposed one beside the other. This prevents the rod 5 rotating 
about the longitudinal axis 29 when linear movement is being performed. 
The effect of the spring force transmitted by the piezoelectric transducer 
9b is that the movable bearing element 5 rotates slightly about the 
longitudinal axis 29, its flat surface 26 coming to rest on the 
piezoelectric transducer 9a. If the force of the spring 10 is suitably 
adjusted, a stable position of the movable bearing element 5 is achieved 
and at the same time a clamping effect is accomplished which prevents the 
movable bearing element slipping, for example when the adjusting device is 
being used vertically. 
FIG. 3 shows that a total of four drive elements 6a, 6b, 6c and 6d are 
disposed under the movable bearing element 5. According to FIG. 4, three 
drive elements 6a to 6c are provided which are disposed in the manner of a 
tripod under the movable element 5. 
FIG. 5 shows a movable bearing element 5 of triangular cross-section. The 
rod 5 has its lateral faces 25a and 25b resting on the already described 
drive elements 6a to 6d. The pressure applying device 8 presses down from 
above onto the flat surface 26. Also shown in this view are two 
piezoelectric transducers 9a and 9b which clamp the movable bearing 
element 5 on the drive elements 6a to 6d. 
FIG. 6 shows a bearing element 5 of hexagonal cross-section. The rod has 
two lateral surfaces 25a, 25b resting on just one appropriately formed 
drive element 6 which has a piezoelectric transducer which is capable of 
shear in the direction of the rod. 
By the shape given to the drive element 6 and the piezoelectric transducers 
9 in conjunction with the hexagonal cross-section of the rod 5, guidance 
is achieved in the direction of movement and at the same time the rod 5 is 
secured against rotation. From the other side, the pressure applying 
device 8 presses down on two further side faces 25c, 25d. In this 
illustration, only one correspondingly shaped piezoelectric transducer 9 
is provided which presses the movable bearing element 5 with a clamping 
action against the drive element 6. 
FIGS. 5a and 7 show further embodiments of the bearing element 5. This 
latter comprises two cylindrical rods 16a and 16b which are connected to 
each other. Furthermore, a plate 15 is disposed on the cylindrical rod 
16b. 
FIG. 5a shows that the two cylindrical rods 16a and 16b form a guide groove 
30 in which the ball 7 of the drive element 6b is centered. A further 
drive element 6c is disposed beneath the plate 15 which likewise rests on 
a ball 7. In this embodiment, only the piezoelectric transducer 9a bears 
down under spring force on the plate 15 of the movable bearing element 5. 
FIG. 7 shows a further version of the pressure applying device 8. Instead 
of a pressure applying device acting from above, there are below the 
bearing element 5 a plurality of magnets 17a to 17d on the base plate 
which attract the bearing element 5 which consists of ferromagnetic 
material, pressing it in this way onto the three drive elements 6a to 6c 
which are likewise disposed on the base plate 3. 
FIG. 8 shows a drive element 6 which in this form also uses the pressure 
applying device. The piezoelectric transducer 33 has a piezoelectric body 
13 of a piezoelectric material with a shear capacity and which has on its 
top and bottom surfaces respective electrically conductive coatings 14a, 
14b connected to a control unit 18. The control unit 18 delivers a voltage 
pulse to the piezoelectric transducer 33 so that this moves out of its 
inoperative position A into a shear position B. The shear position B of 
the piezoelectric transducer 33 is shown by the broken lines. Fixed on the 
upper electrical coating 14a is the ball seating 12 with the ball 7 which 
is preferably made from aluminium oxide. The ball 7 is moved as a result 
of the shear movement (position B). 
Deflection of the ball 7 from its inoperative position depends inter alia 
upon the applied voltage and the material constants of the piezoelectric 
material. In order to achieve large step sizes, it is possible as shown in 
FIG. 9a for the piezoelectric transducer 33 to be composed of a plurality 
of piezoelectric elements 13a to 13c which are isolated from one another 
by respective conductive coatings 14b and 14c. The bottom and top 
piezoelectric elements 13c, 13a also comprise an electrically conductive 
coating 14a and 14d. These electrically conductive coatings 14a to 14d are 
likewise connected to the control unit 18. Since when the voltage pulse is 
applied all the piezoelectric elements 13a to 13c perform the same shear 
movement, the individual deflections become cumulative. 
FIGS. 9a and 9b show a ball 7 on a ball seating 12, the ball and ball 
seating constituting a punctiform support. 
Shown in FIG. 9b is a piezoelectric transducer 33 in which the 
piezoelectric elements 13a, 13b shear in different directions. Preferably, 
the shear directions are at right-angles to one another. 
FIG. 10 shows the time related pattern of the voltage pulse applied to the 
piezoelectric transducer. The curve 1 firstly shows a slowly rising 
voltage pattern (gentle slope) and the steep voltage drop (the steep side 
of the pulse) which is adjacent to it. The overall duration of the pulse 
t.sub.e -t.sub.o preferably amounts to 0.2 to 2 msec. The voltage value is 
around 500 V and the shear deflection of the piezoelectric transducer 
amounts to approx. 200 nm. This voltage pattern has the effect that the 
shear movement of position A shown in FIG. 8 moves slowly to position B 
while the return movement from position B to position A is performed 
rapidly. 
A second possibility is illustrated by the curve II in which, starting at 
t.sub.o, the voltage is raised to its maximum value within a period of 
less than 10 .mu.sec which corresponds to a rapid shear movement. This is 
then followed by a slow abatement of voltage which again reaches zero 
value after the time t.sub.e. In this way, a slow return movement of the 
piezoelectric transducer is achieved. 
In addition, curve III appears in the drawing. It corresponds to the curve 
I but for reversed polarisation of the transducer. 
FIG. 11 shows a rotary adjustment device 1 in which the movable bearing 
element 5 is constructed as a turntable. The turntable has as 
frustoconical shape and its conical surface 20 rests on the drive elements 
6a and 6b which are fitted in a trough-shaped stationary carrier element 
2. The drive elements 6a and 6b are so disposed on the stationary carrier 
element 2 that they perform the shear movement in a rotary direction. From 
above, the pressure applying device 8 which takes the form of the 
stationary piezoelectric transducer 9b, 9c and the spring loaded 
piezoelectric transducer 9a, presses down on the turntable 5. 
Instead of the pressure applying device 8, FIG. 12 shows a magnetic 
pressure applying device. The magnets 17a to 17d are likewise disposed on 
the stationary trough-like component 2 underneath the turntable 5. The 
force lines 19 extend at right-angles to the under side of the turntable 
5. 
As shown in FIG. 13, a total of three drive elements 6a to 6c are 
equidistantly disposed on the conical surface 20. 
FIG. 14 shows a further embodiment of turntable 5 which takes the form of a 
circular disc in the peripheral surface 28 of which there is incorporated 
a groove 21 in which rest the balls 7 of the drive elements 6a, 6b. With 
this embodiment, only two drive elements 6a and 6b (not shown) are needed, 
while the third piezoelectric transducer 9a is at the same time spring 
loaded and constitutes the pressure applying device 8. 
In FIGS. 15, 15a, the turntable 5 is mounted on a ball 36 disposed in the 
centre of the turntable. The drive elements 6a and 6b are, in this 
embodiment, disposed on the under side of the turntable 5. 
Shown in FIGS. 15b, c, d is an adjusting device for linear and rotary 
movement. The turntable 5 which in the illustration here takes the form of 
a portion of a circle, has on its under side a groove 34 in which rests 
the ball 7 of a further drive element. The groove 34 is preferably 
V-shaped so that the turntable 5 is also laterally guided. In the view 
shown here, the groove 34 is disposed at a right-angle to the long side 
33. The turntable also rests on the two drive elements 6c, 6b which 
perform the rotary movement, as FIGS. 15, 15a show. FIGS. 15b and 15c show 
the turntable combined with two different pressure applying devices which 
have already been described. In FIG. 16, rotationally symmetrical 
component 31 takes the form of a cylindrical rod 5 which is axially 
disposed in a drive element 6 which takes the form of a cylinder from 
which a portion has been cut out. The drive element 6 has its outer 
periphery pressed by the base plate 3 against the peripheral surface 32 of 
the rod. The piezoelectric electric transducer 33 contained in the drive 
element 6 is polarised along the periphery and the electrodes 14a, 14b are 
formed by the inner and outer surfaces of the cylinder. 
FIG. 17 shows a multiple adjusting device which is constructed from a total 
of three adjusting devices 1, 1' and 1" according to the invention. The 
bottom adjusting device 1 is a rotary adjusting device such as is 
described as illustrated in FIG. 12. Fixed on the turntable 5 is a linear 
adjusting device 1' which has a movable bearing element 5' of triangular 
cross-section. The turntable 5 at the same time constitutes the stationary 
element 2 of the adjusting device 1'. Mounted on the movable element 5' is 
a further linear adjusting device 1" which has a movable element 5". Here, 
too, the movable element 5' is at the same time the stationary element of 
the adjusting device 1". The pressure applying devices of the three 
adjusting devices 1, 1' and 1" are formed by magnets 17, 17' and 17" which 
are respectively disposed beneath the movable elements 5, 5' and 5".