Piezo Actuator with Motorized Adjustment Screw
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Solution Overview
Problem
Piezo actuators face limitations in providing both slow/long stroke position adjustment and fast/short stroke scanning within a single device, particularly in applications requiring sub-micron to millimeter displacements, as existing solutions fail to integrate these functionalities effectively.
Innovation Solution
The design incorporates a piezo inertia driver with a clamp and two piezo stacks, where one stack causes parallel movement of jaws on a threaded screw, and a piezo amplifier with a second stack inducing horizontal movement through flex hinges, enabling net rotation and translation of the screw via controlled voltage application, combining for both long travel adjustments and high-frequency scanning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a piezo actuator uses flexure based mechanical structures to amplify motion, then displacement is improved to 100s of microns, but the device cannot provide both long stroke position adjustment and high frequency fine adjustment simultaneously
Solution Approach 1:
The patent divides the actuator into two independent functional segments: a piezo amplifier for high-frequency fine adjustment (sub-micron to 100s of microns) and a motorized adjustment screw for long-stroke position adjustment (few millimeters). Each segment operates independently with its own drive mechanism, allowing both functions to coexist without interference and be controlled separately to achieve versatile operation.
2Speed
If the piezo actuator moves at high velocity to achieve fast scanning, then speed is improved, but engagement with the shaft is lost causing slippage
Solution Approach 1:
The patent introduces a clamp mechanism with jaws that mechanically engages the threaded screw as an intermediary between the piezo inertia driver and the screw. This clamp maintains reliable engagement during high-velocity operation by providing positive mechanical contact, preventing slippage while allowing the piezo actuator to operate at high speeds for fast scanning applications.
3Reliability
If the piezo actuator moves at slow velocity to maintain engagement with the shaft, then reliability is improved, but scanning speed is reduced
Solution Approach 1:
The patent employs dynamic control of the clamp mechanism, adjusting the engagement force between the clamp jaws and the threaded screw based on operational requirements. During high-speed scanning, the clamp provides firm engagement to prevent slippage, while during positioning operations, it maintains reliable contact. This dynamic adjustment of engagement characteristics allows the system to achieve both high scanning speeds and reliable engagement maintenance as needed.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration allows for precise, high-frequency scanning and slow, long travel position adjustments, enabling applications like mirror steering and laser beam stabilization with enhanced displacement and speed capabilities.
Implementation Method 1
a first piezo stack mounted in said clamp configured to cause parallel movement of said first jaw element relative to said second jaw element; wherein when an alternating voltage is applied to the first piezo stack, the first piezo stack is configured to cause a parallel back-and-forth movement of the first movable jaw relative to the second jaw by expansion and contraction of the first piezo stack as a result of the applied alternating voltage
Implementation Method 2
a second piezo stack; wherein one end of the second piezo stack is coupled to the first side wall and the other end of the second piezo stack is coupled to the second side wall; wherein when a second voltage is applied to the second piezo stack, the second piezo stack is configured to cause a horizontal movement of the side walls by expansion or contraction of the second piezo stack
Implementation Method 3
a top wall, a bottom wall, a first and second side walls, the walls being joined by flex hinges; wherein the second piezo stack is configured to cause a horizontal movement of the side walls by expansion or contraction of the second piezo stack, the horizontal movement is configured to cause a perpendicular movement of the top wall via the flex hinges
Implementation Method 4
a threaded screw; wherein the piezo inertia driver includes: a clamp having a first movable jaw configured to engage with the threaded screw on a first side... resulting in a net rotation of the threaded screw, and the rotation is configured to cause a first translation movement of the threaded screw
Data Source
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AI summary
A piezoelectric actuator with integrated features to provide linear displacement of a threaded rod is presented. One mechanism provides mechanically amplified piezo motion for high speed/short travel position scanning whereas the other provides a low speed/long travel piezo motorized position adjustment. Mechanical amplifier incorporates one or more piezo stacks in longitudinal axis with preload to translate an amplified motion in the order of a few times in the transverse axis, perpendicular to the piezo stack motion. The piezo amplified output travel is transmitted to the internally threaded features of the other mechanism where a screw with a ball at the end to push a desired surface for high speed scanning mode translation. The internally threaded feature of the other mechanism is also operated by a secondary piezo stack which produces slip- stick motion steps to rotate the screw in one direction or the other to produce a slow speed/long travel mode.