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Examples: P-286 - 289 disk translators (seep. 1-28), PL122 multilayer ben-
der actuators (p. 1-14). Shear Actuators Shear actuators can generatehigh forces and large displace-
ments. A further advantage is
their suitability for bipolaroperation, whereby the mid-position corresponds to a drive
voltage of 0 V. In shear mode,
unlike in the other modes, the
electric field is applied perpen-
dicular to the polarization
direction. (see Fig. 46). The cor-responding strain coefficient,d Piezo • Nano • Positioning Bender Type Actuators(Bimorph and Multimorph
Design) A simple bender actuator(bimorph design) consists of a
passive metal substrate gluedto a piezoceramic strip (seeFig.45a). A piezo bimorph
reacts to voltage changes the
way the bimetallic strip in a
thermostat reacts to tempera-
ture changes. When the ceram-
ic is energized it contracts or
expands proportional to theapplied voltage. Since themetal substrate does not
change its length, a deflection
proportional to the applied
voltage occurs. The bimorph
design amplifies the dimen-
sion change of the piezo, pro-viding motion up to severalmillimeters in an extremely
small package. In addition to
the classical strip form,
bimorph disk actuators where
the center arches when a volt-age is applied, are also avail-able. PZT/PZT combinations, whereindividual PZT layers are oper-
ated in opposite modes (con-
traction/expansion), are alsoavailable. Two basic versions exist: thetwo-electrode bimorph (serial
bimorph) and the three-elec-
trode bimorph (parallelbimorph), as shown in Fig. 45b.In the serial type, one of the
two ceramic plates is always
operated opposite to the direc-
tion of polarization. To avoid
depolarization, the maximum
electric field is limited to a fewhundred volts per millimeter.Serial bimorph benders are
widely used as force and accel-
eration sensors.In addition to the two-layerbenders, monolithic multilayer
piezo benders are also avail-
able. As with multilayer stackactuators, they run on a lower
operating voltage (60 to 100 V).Bender type actuators provide
large motion in a small pack-
age at the cost of low stiffness,
force and resonant frequency. Piezo actuators Piezo Actuators Nanopositioning &
Scanning Systems Nanopositioning &
Scanning Systems metal Active Optics / Steering Mirrors Active Optics / Steering Mirrors Tutorial: Piezo-
electrics in Positioning Tutorial: Piezo-
electrics in Positioning Capacitive Position sensors Capacitive Position
Sensors Piezo Drivers & Nano-
positioning controllers Piezo Drivers & Nano-
positioning Controllers Hexapods /
Micropositioning Hexapods /
Micropositioning Fig. 45 a. Bimorph design (strip and disk translator).
Fig. 45 b. Bender Actuators: Serial and parallel bimorphs.
Fig. 46. Material deformation in a shear actuator. Photonics Alignment
Solutions Photonics Alignment
Solutions Motion controllers Motion Controllers Ceramic Linear motors & Stages Ceramic Linear Motors & Stages Index Index 15 , has large-signal values ashigh as 1100 pm/V, providingdouble the displacement of lin-ear actuators of comparable
size based on d 33 .Shear actuators are suitable forapplications like piezo linear
motors, and are available as
both single-axis and two-axis
positioning elements. Examples: PX155 (p. 1-24), P-363 (p. 2-72),N-214 NEXLINE . ® Piezo-Walk ® motor (p. 10-12). 4-41
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