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Actuator, Positioning stage, Positioning table, Linear positioning table, Piezoelectric motor
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| 205 Williamson Square Franklin, TN 37064 Tel: 615/595-6665 Fax: 615/595-6610 | ||||||||||||||||||||||||||||||
| the stiffness of the external load is high enough to prevent expansion of the PZT. Typical blocked pressure levels are 5 to 7 ksi (34 to 48 MPa). | ||||||||||||||||||||||||||||||
| Strengths of Piezo-Actuators Given the relatively small displacement that a PZT stack can develop, piezo actuators have unique design considerations. For example, piezo-actuators excel in precision positioning applications where small, high-force moves are desirable. When fabricating, measuring, or testing extremely small structures or features, piezo-actuators can provide very smooth and continuous motion over a range of a few microns to a few millimeters. With proper system design, piezo-actuators hold the potential for high speed operation. Generally, the response time of a piezo-stack is limited by the speed of sound in the material. Therefore, natural frequency of a PZT stack may be several kiloHertz. Even with the added mass and lower stiffness of an amplification mechanism, the natural frequency of an amplified piezo-actuator may be a few kiloHertz. Additionally, when designed and constructed properly, piezo-actuators can exhibit the following strengths. • solid-state construction with zero backlash, stiction, or cogging • low or zero power position hold capability • very high frequency response (bandwidth) • very high force per unit area (force and stroke directly scales with size) • little or no outgassing or particle generation as flexure based designs have little or no friction and require no lubrication • relatively low heat generation • highly scaleable and reliable | ||||||||||||||||||||||||||||||
| Figure 3 - DSM LPA-100 piezo-actuator uses a simple lever-arm mechanical amplification. (PZT stack is green -output is in vertical direction) | ||||||||||||||||||||||||||||||
| Ze ro Potential Applied Positive Potential Applied | ||||||||||||||||||||||||||||||
| PZT | ||||||||||||||||||||||||||||||
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| Figure 4 - PZT uni-morph patch amplification | ||||||||||||||||||||||||||||||
| Figure 5 - A miniature piezo actuator for a 70 um displacement switching application uses a uni-morph amplification concept. | ||||||||||||||||||||||||||||||
| Summary DSM's piezo-actuators harness the small precise amount of expansion generated by the piezoelectric effect to produce a wide range of actuator solutions. With proper design, piezo-actuators have performance attributes and properties that can be valuable in precision positioning, vibration control, and scanning applications. Smooth, precise motion from the sub-nanometer to multiple-millimeter level is possible with a variety of solid-state actuation/amplification mechanisms. | ||||||||||||||||||||||||||||||
| Producing Force: PZT stacks are displacement-generating devices. They expand proportionally to the applied electric field or actuation voltage. Maximum motion or expansion of the PZT occurs at maximum actuation voltage. When an external load resists the motion of the PZT expansion, the PZT stacks apply a force that is a function of the stiffness of the external load. The PZT stacks can generate a very high level of pressure against an external load if | ||||||||||||||||||||||||||||||
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| v. 060224, p. 2 | ||||||||||||||||||||||||||||||