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Piezo-Electric Accelerometers

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Piezo-electric accelerometers based on ferro electric ceramics first surfaced in the late 40's as means of collecting data on the dynamic behaviour of airframes and a variety of military and avionic hardware, supplanting the heavier, less robust velocity transducer. Early devices comprised a piezo-ceramic disc sandwiched between a reaction mass and a cylindrical base (the means of attachment to the test object), and this manner of construction features in several manufacturers products today.

However the art has moved on; disadvantages inherent in this compression disc design, namely high strain sensitivity and cross axis error, preclude their use for many applications and have directly led to several innovations whereby the acceleration/charge conversion is accomplished by means of a shear couple applied to a piezo-ceramic plate or tube.

Specifically, our KONIC design (UK pat 1507251), comprising a truncated hollow piezo-ceramic cone, spigot, and concentric reaction mass, provides virtual isolation of the sensing element from mounting induced strain, with the further benefit of minimal cross axis error deriving from its radial symmetry.

In addition, the KONIC sensing element is mechanically preloaded, temperature constraint imposed by use of adhesives is eliminated. The various configerations outlined above are clarified in fig 1.

KONIC accelerometers are produced in sizes from 1.5gm, weight, 2pC/g sensitivity upwards, maximum 90gm., 300pC/g.

Piezo-ceramic shear plate technology is employed at the periphery of the KONIC range as offering miniaturisation advantages, and sensitivity enhancement by virtue of parallel plate construction.

We have a wide range of industrial accelerometers (vibration sensors).