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Self Calibrating Apparatus for Piezoelectric Shock Sensors in DASD

IP.com Disclosure Number: IPCOM000110103D
Original Publication Date: 1992-Oct-01
Included in the Prior Art Database: 2005-Mar-25
Document File: 2 page(s) / 77K

Publishing Venue

IBM

Related People

Chainer, TJ: AUTHOR [+3]

Abstract

Disclosed is a scheme that permits an in-situ calibration of a piezoelectric shock sensor incorporated into a DASD. This permits the use of low-cost sensors in which the variations in material properties and changes due to aging can be corrected for by periodic calibrations.

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Self Calibrating Apparatus for Piezoelectric Shock Sensors in DASD

       Disclosed is a scheme that permits an in-situ calibration
of a piezoelectric shock sensor incorporated into a DASD.  This
permits the use of low-cost sensors in which the variations in
material properties and changes due to aging can be corrected for by
periodic calibrations.

      With the advent of portable and laptop computers, the
environment in which DASDs will need to operate will include greater
exposure to shock and vibrations.  To avoid the possibility of an
adjacent track being overwritten due to a shock input during a write
operation, these DASDs will necessarily need some form of shock
sensing.  The timely detection of a shock would permit the system to
abort the write operation and thus avoid the overwrite error.

      Various forms of shock sensors exist.  The most common are
those that use piezoelectrics as the sensors.  Commercial sensors,
however, are expensive due to the need for careful material
preparation and the individual calibration of each device.  With the
ability of in-situ calibration (as described below), the use of
inexpensive commercial piezoelectric materials should be possible,
thereby lowering the cost of the sensors substantially.

      An essential element needed for the calibration of the sensor
is the application of an alternating force of a known amplitude.  The
alternating force is needed because piezoelectrics are charge devices
where the fixed component of their output bleeds away rapidly due...