A
tiny ultrasonic piezo motor (2.8 x 2.8 x 6 mm) and drive ASIC (1.8 x 1.8 mm)
creates a miniature linear motion system that offers performance comparable to
much larger electromechanical systems using 40 percent lower power and less
than one-fourth the size. Target
applications are battery-operated hand-held devices, mobile phone cameras,
digital still and video cameras and miniature medical actuators used for
minimally invasive surgery.
The
SQUIGGLE RV motor from New Scale
Technologies is a new "reduced voltage" piezo micro motor that uses
multi-layer piezo technology from TDK-EPC
(formerly Epcos) to reduce the input voltage requirements. A NSD-2101 driver developed
in partnership with austriamicrosystems
controls the motor using a standard IA 2C interface.
The
drive IC accepts direct 2.3 to 5.5V dc battery power and uses patented
full-bridge switching technology to create the ultrasonic motor drive
frequency. The IC has patent-pending smart drive features built-in that
optimize motor performance while minimizing power consumption over a broad
range of operating and environmental conditions. A built in oscillator
eliminates the need for an external master clock.
"All
of the drive circuitry is on the IC," says Ralph Weber, product manager for New
Scale Technologies. "Using multilayer piezo technology, we have IP and patent
pending concepts like hybrid controls and frequency tracking on the chip. As a
result we almost double the force of our previous SQUIGGLE motor using half the
power. It really performs like an electromagnetic linear system at about one-quarter
of the size."
Weber
says that the multilayer piezo technology provides an interleaving of piezo
layers, and combining the layers in the piezo stack creates the same deflection
at a lower voltage than a full single layer, piezo stack. The drive IC also
uses a proprietary design to actively manage low power consumption. It offers a
power-down mode for minimal power consumption in stand-by and an idle mode for
reduced power consumption while maintaining frequency calibration.
"This
is a tremendous milestone for the piezo motor industry," says Weber. "We
are the first company to commercialize a piezoelectric motor system that
matches the low voltage operation of stepper motors while at the same time
using radically less space and power."
The
SQL-RV-1.8 motor achieves forces in excess of 50 gm and high resolution to 0.5
micrometer. It can run at speeds greater than 7 mm/sec with power consumption
of less than 350 mW when moving under typical loading conditions which
corresponds to a dc current of only 120 mA for a typical 3V dc battery. Its
unique self-locking design means that zero power is required to hold the motor
position.
New
Scale's TRACKER NSE-5310 linear encoder can be integrated with the SQUIGGLE RV
system for high system repeatability with submicron resolution. Its small size
provides an ability for designers to create tiny, high resolution integrated
closed-loop motion systems.
