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No-Work-Type Actuator With Laminated PZT Beam Spring

IP.com Disclosure Number: IPCOM000043110D
Original Publication Date: 1984-Jul-01
Included in the Prior Art Database: 2005-Feb-04
Document File: 2 page(s) / 70K

Publishing Venue

IBM

Related People

Lane, R: AUTHOR [+3]

Abstract

A no-work magnet actuator is considered as a superior design for a high speed printer actuator because of its fast response and rapid settle out. In the design of the no-work magnet actuator, the most difficult task is to match the spring force to the magnet force as nearly as possible with a sufficient safety factor to assure the spring being restored to rest position for next firing. As shown in Fig. 1, the force from the permanent magnet, curve A, has to be higher than the spring force, curve B. The spring force provides the print energy, and the magnet force restores the spring. Since the magnet force is proportional to the second power of the displacement and the spring force varies linearly with the displacement, the stroke of the actuator is limited by the safety margin of two forces (point E in Fig. 1).

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No-Work-Type Actuator With Laminated PZT Beam Spring

A no-work magnet actuator is considered as a superior design for a high speed printer actuator because of its fast response and rapid settle out. In the design of the no-work magnet actuator, the most difficult task is to match the spring force to the magnet force as nearly as possible with a sufficient safety factor to assure the spring being restored to rest position for next firing. As shown in Fig. 1, the force from the permanent magnet, curve A, has to be higher than the spring force, curve B. The spring force provides the print energy, and the magnet force restores the spring. Since the magnet force is proportional to the second power of the displacement and the spring force varies linearly with the displacement, the stroke of the actuator is limited by the safety margin of two forces (point E in Fig. 1). To increase the stroke, the strength of the permanent magnet has to be increased. That will require more electrical power for the buck-out coil. Or one can increase the stiffness of the spring, but that will result in the actuator being extremely stroke sensitive. Both are not desirable solutions. This article describes the use of a piezoelectric ceramic (PZT) laminated beam as the spring structure for a no-work magnet actuator. By energizing the PZT, the beam spring will bend towards the magnet to reduce the gap to the point where the magnet force is clearly higher than the spring force (point D in Fig. 1). This will allow one to use a less powerful magnet and a small buck-out coil, also an increase in the actuator stroke. In addition, by energizing the PZT in the forward printing motion, it can give an additional force to control the flight time and the print energy for various printing requirements. Since the bending of the PZT also produces an electrical voltage, it is also possible to get a feedback signal from PZT to control the motion of the actuator. Typical designs of the disclosed print actuator (mul...