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Browse Prior Art Database

Side Electrode Bending Beam Piezoelectric Motion Generators

IP.com Disclosure Number: IPCOM000116324D
Original Publication Date: 1995-Aug-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 2 page(s) / 105K

Publishing Venue

IBM

Related People

Lee, FC: AUTHOR [+3]

Abstract

A piezoelectric motion generator design, called Side Electrode Bending Beam (SEBB) is described. The basic concept can be best illustrated in Fig. 1. A rectangular piezoelectric beam is polarized across its lateral thickness. Two metal electrodes are deposited on two longitudinal parallel faces, asymmetrically covering only a portion but not completely of those faces. In Fig. 1a, the electrodes extend from the top edges and cover about 70% of the faces. The area without the metal electrode coverage is an inactive zone. The piezoelectric material under the inactive zone can be polarized or not polarized since the polarization in this section will not contribute to the motion without covering electrodes.

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Side Electrode Bending Beam Piezoelectric Motion Generators

      A piezoelectric motion generator design, called Side Electrode
Bending Beam (SEBB) is described.  The basic concept can be best
illustrated in Fig. 1.  A rectangular piezoelectric beam is polarized
across its lateral thickness.  Two metal electrodes are deposited on
two longitudinal parallel faces, asymmetrically covering only a
portion but not completely of those faces.  In Fig. 1a, the
electrodes extend from the top edges and cover about 70% of the
faces.  The area without the metal electrode coverage is an inactive
zone.  The piezoelectric material under the inactive zone can be
polarized or not polarized since the polarization in this section
will not contribute to the motion without covering electrodes.  As an
appropriate voltage difference is applied on the electrode pair, the
piezoelectric material sandwiched in between would change its
dimensions, e.g., in Fig. 1b, an extension of its length of the top
part of the beam.  The lower portion of the beam in the inactive zone
does not change dimension.  The net result is the beam would bend and
concave downward.  Fig. 1c illustrates the case in which an opposite
polarity voltage difference is applied to the electrodes causing them
to bend and concave upward.

      It is also possible to arrange the SEBB design in a "push-pull"
mode, as illustrated in Figs. 2 and 3.  The electrode on each face is
split into top and bottom parts with a small inactive strip in the
middle (Fig. 2a).  Piezoelectric polarization on the top part is
opposite to the lower part.  The two electrode pairs on each face are
electrically connected.  As an appropriate voltage difference is
applied between the front and back electrode pairs, piezoelectric
material on the top part experiences extension while the lower part
undergoes contraction.  This causes the beam to bend and concave
downward (Fig. 2b).  Similar to Fig. 1c, if the driving voltage
difference changes polarity, the beam would bend and concave upward
as shown in Fig. 2c.  Fig. 3 shows a situation where the
piezoelectric polarization is uniform.  The top electrode on the
front face is electrically c...