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EP-4738682-A1 - PIEZOELECTRIC INERTIAL DRIVE ROTARY STAGE

EP4738682A1EP 4738682 A1EP4738682 A1EP 4738682A1EP-4738682-A1

Abstract

A piezoelectric inertial drive rotary stage including a piezoelectric inertial driver and a rotor (180). The driver includes a mounting portion (100), a friction portion (135, 136) coupling to the rotor, a movement portion (140) between the mounting portion and friction portion, a piezoelectric element (120) with first end bonded to the mounting portion and second end bonded to a movement portion, the movement portion transferring the motion of the piezoelectric element to the friction portion to drive the rotor.

Inventors

  • HE, Houxi
  • GAO, RENLONG

Assignees

  • Thorlabs, Inc.

Dates

Publication Date
20260506
Application Date
20251028

Claims (12)

  1. A piezoelectric inertial drive rotary stage, comprising: a rotor (180, 280, 380); a piezoelectric inertial driver configured to move the rotor (180); the driver including: a mounting portion (100, 200, 300) configured to mount to a holder; a first connection portion (130, 230, 330) and a second connection portion (131, 231, 331) arranged with an angle θ tolerance in the range from 0 degree to 180 degrees between the first and second connection portions, the first and second connection portions having their respective first and second friction portions (135, 136, 235, 236, 335, 336) at their distal ends; a first movement portion (140, 240, 340) including: a first end connected to a first piezoelectric element (120, 220, 320); and a second end connected to the first connection portion (130, 230, 330); a first flexure portion (105, 205, 305) including a first end connected to the mounting portion; and a second end connected to the movement portion (140, 240, 340) via a flexible hinge (145, 245, 345); wherein the first piezoelectric element is arranged with its first end bonded to the mounting portion and its second end bonded to the movement portion; and wherein when an electrical signal is applied to the first piezoelectric element, the first piezoelectric element expands or contracts according to the electrical signal, and the expansion or contraction of the first piezoelectric element causes the movement portion to move, which causes the rotor to move via the first friction portion (135, 235, 335).
  2. The piezoelectric inertial drive stage of claim 1, wherein the electrical signal includes a slow ramped up electrical field followed by a sudden drop electrical field.
  3. The piezoelectric inertial drive stage of claim 1, wherein the electrical signal includes a sharp increase electrical field followed by a slow drop electrical field.
  4. The piezoelectric inertial drive stage of claim 1, the friction portions are made from a wear-resistant material.
  5. The piezoelectric inertial drive stage of claim 1, wherein the second connection portion (131) decreases a backward movement of the rotor via the second friction portion and the second connection portion is further configured as a supporting structure for the rotor.
  6. The piezoelectric inertial drive stage of claim 1, wherein the driver includes a second movement portion including: a first end connected to a second piezoelectric element (221); and a second end connected to the second connection portion (231); wherein the second end of the first flexure portion (205) is connected to the second movement portion (241); wherein the second piezoelectric element is arranged with its first end bonded to the mounting portion and its second end bonded to the second movement portion; wherein when a second electrical signal is applied to the second piezoelectric element, the second piezoelectric element expands or contracts according to the second electrical signal, and the expansion or contraction of the second piezoelectric element causes the second movement portion to move, which causes the rotor to move via the second friction portion (236).
  7. The piezoelectric inertial drive stage of claim 6, wherein the first and second electrical signals are configured to cause the first piezoelectric element to expand and the second piezoelectric element to contract, and vice versa.
  8. The piezoelectric inertial drive stage of claim 1, wherein the second end of the first flexure portion (305) is connected to a second and third flexure portions (350, 351) configured to reduce a deformation of the movement portion (340) by transferring a push force from the piezoelectric element to the second and third flexure portions.
  9. The piezoelectric inertial drive stage of claim 8, wherein the second and third flexure portions comprises a plurality of rods with intersecting connections, and an angle tolerance between adjacent rods is in the range from 0 degree to 180 degrees.
  10. The piezoelectric inertial drive stage of claim 8, wherein each of the plurality of rods, an angle between adjacent rods, and a width of each individual rods are selected to obtain a preferred stiffness of the third and fourth flexure portions.
  11. The piezoelectric inertial drive stage of claim 1, 6 or 8, wherein a length and a width of the first and second connection portions are selected to obtain a desired cycle motion distance.
  12. The piezoelectric inertial drive stage of claim 1, 6 or 8, further comprising additional piezoelectric elements and friction portions, wherein the number of friction parts is the same or different from the number of piezoelectric elements.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Application 63/715,106, filed on November 1, 2024, the contents of which are incorporated by reference herein. TECHNICAL FIELD The present disclosure generally relates to positioning stage, and more particularly to a compact piezoelectric inertial drive rotary stage. BACKGROUND Based on inverse piezoelectric effect, piezoelectric actuators or motors could transfer electrical field into mechanical strain or movement, which could be used in some motion control applications. A simple piezoelectric actuator could be a piezoelectric element, which could be a monolayer polarized piezoelectric material with electrodes. Under a certain electrical field, the piezoelectric element could deform (expand, contract or shear) in one direction, but the strain is typically lower than several parts per thousand, which means the displacement of the moving part of most monolayer piezoelectric elements with several millimeters' dimension are limited to several microns. Then a multilayer structured piezoelectric actuator, consisting of stacked piezoelectric layers (mechanically in series) that are sandwiched between interdigitated electrodes (electrically in parallel) is used to add up the deforming of each layer to achieve displacement up to a few hundred microns. But the strain remains several parts per thousand according to the mechanically bond in series. Furtherly, a mechanical amplifier with specified structure is used to amplify the displacement of the piezoelectric actuator, but the amplified displacement is still limited to several millimeters. To get rid of the limited displacement and achieve a larger travel range, a piezoelectric motor or called piezoelectric drive system has been developed with typically a stator or called driver and a rotor, which has a small movement in a cycle of the driver driven by a piezoelectric element and could accumulate small movements when repeating this cycles many times to finally achieve large travel. The travel range of such a piezoelectric motor is typically limited only by the travel range of the rotor. Piezoelectric inertial motor or called piezoelectric inertial drive stage is one kind of piezoelectric motor, in which the piezoelectric element could be integrated into either the stator or the rotor, the rotor could achieve a small movement in a cycle of the driving of the piezoelectric element due to the inertia of the masses of the components involved. The description provided in the background section should not be assumed to be prior art merely because it is mentioned in or associated with the background section. The background section may include information that describes one or more aspects of the subject technology. The patents US7535661B2 and US7462974B2 describe the piezoelectric inertial driving actuator comprising a fixing member, a moving piezo element, an oscillation substrate with spring, a moving body that is arranged on the oscillation substrate and is moved by inertia with the substrate. These designs have not introduced any special design on the spring. The patent US8520327B2 is a typical piezoelectric inertial motor with piezoelectric element integrated in the stator or called "piezoelectric inertia driver." This piezoelectric inertia driver consists of a rigid body portion and a continuous, flexible resilient member with a drive surface portion, an axially rigid portion and an S-shaped resilient portion. This patent has mainly claimed the S-shaped resilient portion and has not introduced any special design on the drive surface and the stiffness of drive portion. The patent US8593033B2 describes a piezoelectric motor with multiple piezoelectric elements as stator, to drive the rotor by individually control of the multiple piezoelectric elements. This patent does not have any flexure portion to enhance the homing of the piezoelectric elements. The patent US9312790B2 is a typical piezoelectric inertial motor with piezoelectric element integrated in the stator. This patent has claimed a flexure portion consisting of a tapered spring having a first end with a first width, a second end with a second width, and a turn portion with a turn width, wherein the first width and the second width are smaller than the turn width, which is different from the S-shaped resilient portion in patent US8520327B2. This patent has also introduced a friction pad on the drive surface and preload member but the stiffness of the flexure portion is low and limit the driver's performance. SUMMARY An embodiment of the present disclosure may relate to designing a series of simple and compact structures in the piezoelectric inertial driver for the inertial drive stage. The dual-point contacting design allows the drivers to be easily mounted and preloaded to the rotary stages with only one set screw, and also decreases the reverse displacement during the slip phase of the stick-slip cycle. Different from the pat