TECHNOLOGY
New Digital Sensor With
Square Wave Output
The inGen Linear Direct sensor from Inprox Sensors uses
frequency of oscillation, which
provides output in the form of
a square that is then read
through a pulse train by a digital microprocessor.
Inprox Sensors has developed a
square wave output digital sensor
technology platform targeted
toward the gas and diesel engine markets. The inGen Linear Direct system
uses a suite of harsh-duty, noncontact,
frequency-based digital sensors that
run on an integrated circuit capable of
interfacing directly with a microprocessor without the need for internal or
external signal conditioning.
The sensor system is used to measure changes in pressure, temperature,
linear position, angle and vibration,
and works by using frequency of oscillation. This provides an output in the
form of a square wave, which is then
read through a pulse train by a digital
microprocessor. Multiple outputs,
such as position and temperature, can
also be read by the inGen sensor
using the same signal. Because the
sensor uses a time-based technology,
it does not rely on amplitude or signal
shape, which translates into less interference to impact the signal quality.
“Our natural square wave output
coupled with this kind of performance/
cost dynamic is really interesting to
our customers,” said Derek Weber,
Inprox vice president, sales North
America. “With today’s microprocessors’ ability to measure thousands of
Hz, the resolution is an order of magnitude better than existing technology.
The key is the way in which the inGen
signal is generated in the first place —
a sensor without the need for any signal conditioning.”
Inprox developed the inGen sensor
to replace less responsive analog
technology. “Standard analog methodology requires A/D (analog-to-digital)
signal conversion,” said Weber. “If the
underlying signal is unstable and
prone to error, then the pulse train will
only multiply and compound these
errors and inaccuracies.
“Analog sensing can be like trying to
see through a dirty window when your
fundamental bit information is inaccurate. Direct to digital outputs create a
reliable pulse train where compound
error terms that are the cause of most
inaccurate and unstable sensor signals are no longer an issue.”
All major component costs such as
the signal conditioning circuits and analog-to-digital converters have also been
removed from the design of the inGen
sensor, which Inprox said makes it a
more cost-effective product. Inprox initially targeted the sensor toward the
aerospace and automotive industries
but to date, it has been used in an array
of gas and diesel engine applications
including camshaft speed-position
sensing; fuel injector rack, throttle and
injector positioning; turbocharger boost
pressure and oil level sensing.
The sensor is also designed for commercial and military use, and with its
-166° to 842°F temperature range and
1202°F survivability rating, can be used
in extreme temperature applications.
“The most impressive attribute isn’t just
the ability to operate or service in these
temperatures,” Weber said, “but the
strain of cycling through temperatures
actually strengthens the sensor itself.
At the end of the life of certain systems,
this sensor might actually be the component in the best shape.”
Inprox Sensors is headquartered in
Boston, Mass., with locations in
Eastern and Western Canada, India,
China and Japan. The company’s
portfolio features measurement systems, embedded sensing products
and a full range of inductive proximity,
photoelectric, ultrasonic, laser, capacitive, ultraviolet, magnetic, safety and
fork sensors. dp
