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Improved Glide Test of Thin Film Disks using a BIMORPH Piezoelectric Transducer, Small Glide Head

IP.com Disclosure Number: IPCOM000106472D
Original Publication Date: 1993-Nov-01
Included in the Prior Art Database: 2005-Mar-21
Document File: 4 page(s) / 154K

Publishing Venue

IBM

Related People

Schar, TW: AUTHOR

Abstract

A reduced size read-write head is provided with a two layer piezoelectric transducer (PZT) which produces electrical signals as the head contacts the surface of a rotating, recording disk. The reduced head size provides improved compliance of the head and the adjacent rotating disk when compared to larger heads flying above the same rotating disk. The simple two lead electrical connections to the two layer piezoelectric transducer are compatible with the single ended channels common to many glide testers but the two layer piezoelectric transducer provides more sensitivity to the longitudinal and transverse bending motions of the read-write head than the more common single layer piezoelectric transducer.

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Improved Glide Test of Thin Film Disks using a BIMORPH Piezoelectric Transducer, Small Glide Head

      A reduced size read-write head is provided with a two layer
piezoelectric transducer (PZT) which produces electrical signals as
the head contacts the surface of a rotating, recording disk.  The
reduced head size provides improved compliance of the head and the
adjacent rotating disk when compared to larger heads flying above the
same rotating disk.  The simple two lead electrical connections to
the two layer piezoelectric transducer are compatible with the single
ended channels common to many glide testers but the two layer
piezoelectric transducer provides more sensitivity to the
longitudinal and transverse bending motions of the read-write head
than the more common single layer piezoelectric transducer.  Improved
compliance coupled with the greater sensitivity to the read-write
head bending modes provides a sensor able to detect contact of a
read-write head and an adjacent, rotating disk at more consistent
head/disk spacings.

      A device was built to sense contact between a read-write head
and an adjacent, rotating disk.  A reduced size read-write head was
provided with a two layer piezoelectric transducer similar in width
and length to the read-write head to produce electrical signals
related to head/disk contact.  Although previous patents have been
issued for similar devices, e.g., [*], this device differs in several
areas.  First, because of the small read-write head size, the
piezoelectric transducer must be placed between the head and the
suspension rather than adjacent to the suspension.  Second, the
piezoelectric transducer described in that patent is replaced with a
simple, two layer piezoelectric transducer with opposite direction
poling and an electrical configuration which provide sensitivity to
head vibrations caused by head/disk contact while attenuating
sensitivity to non-contact vibrations.  This assembly is relatively
low cost and simple to make requiring a read-write head, a two layer
piezoelectric transducer with two electrical leads, and a means of
suspending the head/transducer assembly above the rotating disk.  A
simple, single ended electrical channel which is common on many glide
testers is used for signal conditioning and interpretation.

      The reduced-size read-write head was chosen to match technology
currently used or being implemented in most new designs for rigid
disk, magnetic recording, storage devices.  Its dimensions (1.6mm X
2.5mm X 0.4mm) are roughly one half those for heads commonly used for
most piezoelectric glide testing.  Matching the read-write head size
of this design to that used for current storage device designs
insures that the this piezoelectric sensor design complies similarly
to the heads used to manufacture the storage devices.  If the larger
head size commonly employed for glide testing was used, the variation
in head/disk spacing would be roughly three t...