Micromachined Silicon Variable Capacitance Accelerometers
THE CAPACITIVE ACCELEROMETER
Function of Capacitive Accelerometers
Capacitive accelerometers sense a change in electrical capacitance,
with respect to acceleration, to vary the output of an energized circuit.
The sensing element consists of two parallel plate capacitors acting
in a differential mode.These capacitors operate in a bridge circuit, along with two fixed
capacitors, and alter the peak voltage generated by an oscillator
when the structure undergoes acceleration. Detection circuits
capture the peak voltage, which is then fed to a summing amplifier
that processes the final output signal.
Structure of Capacitive Accelerometers
Capacitive accelerometers sense a change in electrical capacitance,
with respect to acceleration, to vary the output of an energized circuit.When subject to a fixed or constant acceleration, the capacitance
value is also a constant, resulting in a measurement signal proportional
to uniform acceleration, also referred to as DC or static acceleration.PCB’s capacitive accelerometers are structured with a diaphragm,
which acts as a mass that undergoes flexure in the presence of
acceleration. Two fixed plates sandwich the diaphragm, creating
two capacitors, each with an individual fixed plate and each sharing
the diaphragm as a movable plate. The flexure causes a capacitance
shift by altering the distance between two parallel plates, the
diaphragm itself being one of the plates.The two capacitance values are utilized in a bridge circuit, the
electrical output of which varies with input acceleration.
Article by PCB Piezotronics Inc
Design and Application
A 5-page technical article by Tom Connolly of Endevco Corp.
To view complete pdf file, click here
Visit their website at www.endevco.co.uk
For details of ACCELEROMETER Suppliers, who can provide detailed information,
please click SUPPLIERS, then select ACCELERATION, VIBRATION or SHOCK sections...
Home - Website - Search - Suppliers - Links - New Products - Catalogues - Magazines
Problem Page - Applications - How they work - Tech Tips - Training - Events
