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Rotational Piezoelectric Actuator

IP.com Disclosure Number: IPCOM000034176D
Original Publication Date: 1989-Jan-01
Included in the Prior Art Database: 2005-Jan-26
Document File: 2 page(s) / 41K

Publishing Venue

IBM

Related People

Duerig, UT: AUTHOR [+2]

Abstract

Manipulation of probes and tools often requires very minute rotations which are difficult to produce, in particular under UHV conditions. The actuator consists of a circular piezoelectric disk 1 having a shaft 2 mounted at the disk's center hub 3 and a pair of radial slits 4, 5 arranged diametrically opposite one another. Top and bottom faces of disk 1 each carry four electrodes 6 through 9 providing four piezoelectric sectors, a through d (Fig. 1). Application of a voltage of alternating polarity to said sectors will result in a mechanical distortion of disk 1 (Fig. 2). The net effect of this distortion is a displacement of the center of mass of sectors a, b and d, c, respectively. Thus, a torque proportional to the velocity of displacement is exerted on shaft 2 mounted at the center hub 3 of disk 1.

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Rotational Piezoelectric Actuator

Manipulation of probes and tools often requires very minute rotations which are difficult to produce, in particular under UHV conditions. The actuator consists of a circular piezoelectric disk 1 having a shaft 2 mounted at the disk's center hub 3 and a pair of radial slits 4, 5 arranged diametrically opposite one another. Top and bottom faces of disk 1 each carry four electrodes 6 through 9 providing four piezoelectric sectors, a through d (Fig. 1). Application of a voltage of alternating polarity to said sectors will result in a mechanical distortion of disk 1 (Fig. 2). The net effect of this distortion is a displacement of the center of mass of sectors a, b and d, c, respectively. Thus, a torque proportional to the velocity of displacement is exerted on shaft 2 mounted at the center hub 3 of disk 1. Rotary motion of shaft 2 is obtained by applying a sawtooth-like drive voltage to the four pairs of piezoelectric electrodes 6 through 9. The fast rising edge of the signal causes a torque sufficient to overcome the friction in the shaft's bearings, enabling rotation of shaft 2 owing to conservation of angular momentum. During the slowly decaying tail of the signal, piezoelectric disk 1 is restored to its initial position with respect to shaft 2. Since the torque exerted during restoration is very small, shaft 2 will remain fixed in its bearings. With a commercially available piezoelectric disk of 32 mm diameter and 3 mm thick, driv...