Thin film actuator having transversely oriented structural stiffeners to increase actuator stroke

Patent metadata

Field	Value
Publication number	US-11489461-B2
Application number	US-202016883605-A
Country	US
Kind code	B2
Filing date	May 26, 2020
Priority date	May 26, 2020
Publication date	Nov 1, 2022
Grant date	Nov 1, 2022

Abstract

A thin film actuator having transversely oriented structural stiffeners that serve to increase actuation stroke that results from longitudinal curvature. The thin film actuator may be deployed within electromechanical devices such that an actuatable deflection of a tip of the actuator plate produces the actuation stroke. The thin film actuator may include an actuator plate affixed to a substantially rigid frame structure. The actuator plate protrudes along a longitudinal axis away from the frame structure such that the actuator plate is cantilevered from the frame structure by some distance along this longitudinal axis. The thin film actuator includes a piezoelectric film on a surface of the actuator plate. Activation of the piezoelectric film generates tensile stress or compressive stress at the surface, thereby inducing a bending moment that causes the actuator plate to undergo longitudinal curvature and some lesser degree of transverse curvature.

First claim

What is claimed is:

1. A microelectromechanical system (MEMS) actuation device, comprising:
an actuator plate having a base that is mechanically coupled to a frame structure, wherein the actuator plate protrudes from the frame structure along a longitudinal axis that extends from the base of the actuator plate to a tip of the actuator plate;
a piezoelectric film deposited on a first surface of the actuator plate, wherein activation of the piezoelectric film, via a drive signal, applies a bending moment to the actuator plate that causes:
transverse curvature of the actuator plate along a transverse axis,
and longitudinal curvature of the actuator plate along the longitudinal axis; and

a plurality of structural stiffeners protruding from at least one of the first surface of the actuator plate or a second surface of the actuator plate that is opposite the first surface, wherein individual structural stiffeners are aligned substantially parallel to the transverse axis to increase a moment of inertia that resists the transverse curvature.

2. The MEMS actuation device of claim 1 , wherein the piezoelectric film has a first nominal thickness and the actuator plate has a second nominal thickness that is at least three times greater than the first nominal thickness, and wherein individual structural stiffeners protrude a distance of at least three times the second nominal thickness.

3. The MEMS actuation device of claim 1 , wherein the plurality of structural stiffeners protrude from the second surface of the actuator plate a distance that is at least twenty times a nominal thickness of the piezoelectric film.

4. The MEMS actuation device of claim 1 , wherein the plurality of structural stiffeners includes at least three individual stiffeners that protrude from the actuator plate a distance that is at least three times a nominal thickness of the actuator plate.

5. The MEMS actuation device of claim 4 , wherein the nominal thickness of the actuator plate is at least five times greater than a nominal thickness of the piezoelectric film.

6. The MEMS actuation device of claim 1 , wherein the longitudinal curvature, of the actuator plate about the transverse axis with which the individual structural stiffeners are aligned substantially parallel to, produces an actuator stroke that corresponds to a deflection of the tip of the actuator plate.

7. The MEMS actuation device of claim 1 , wherein the plurality of structural stiffeners protrudes from the second surface of the actuator plate that is opposite the first surface on which the piezoelectric film is deposited.

8. The MEMS actuation device of claim 1 , wherein the piezoelectric film is lead zirconate titanate (PZT).

9. The MEMS actuation device of claim 1 , wherein a length from the base of the actuator plate to the tip of the actuator plate is at least fifty times a nominal thickness of the actuator plate, and wherein the structural stiffeners protrude from the actuator plate a distance that is at least three times the nominal thickness of the actuator plate.

10. An actuation device, comprising:
an actuator plate that protrudes from a frame structure along a longitudinal axis that extends from a base of the actuator plate to a tip of the actuator plate, wherein the actuator plate has a nominal thickness;
a piezoelectric film that, upon activation via a drive signal, causes a combination of: transverse curvature of the actuator plate along a transverse axis and longitudinal curvature of the actuator plate along the longitudinal axis; and
one or more transversely oriented structural stiffeners that are aligned substantially orthogonal to the longitudinal axis resist transverse curvature, of the actuator plate during the activation of the piezoelectric film, thereby at least partially mitigating increases to an area moment of inertia of the actuation device along the longitudinal axis, wherein individual transversely oriented structural stiffeners have a nominal height that is greater than the nominal thickness of the actuator plate.

11. The actuation device of claim 10 , wherein the nominal height of the individual transversely oriented structural stiffeners is at least three times greater than the nominal thickness of the actuator plate.

12. The actuation device of claim 10 , wherein the individual transversely oriented structural stiffeners protrude from a first surface of the actuator plate that is opposite a second surface, of the actuator plate, on which the piezoelectric film is disposed.

13. The actuation device of claim 12 , wherein the nominal height that the individual transversely oriented structural stiffeners protrude from the first surface is at least twenty times greater than a nominal thickness of the piezoelectric film on the second surface.

14. The actuation device of claim 10 , wherein the transverse bending produces an actuator stroke that corresponds to a deflection of the tip of the actuator plate.

15. The actuation device of claim 10 , wherein the longitudinal axis extends linearly from the base of the actuator plate to the tip of the actuator plate.

16. The actuation device of claim 10 , wherein the longitudinal axis is a curved axis that extends non-linearly from the base of the actuator plate to the tip of the actuator plate.

17. The actuation device of claim 10 , wherein the actuator plate is mechanically coupled to a scanning mirror, and wherein an amount of angular rotation that is induced into the scanning mirror increases directly with increases in the longitudinal curvature of the actuation device.

18. A system, comprising:
a controller that generates drive signals; and
an actuator that includes:
an actuator plate that extends from a base that is affixed to a frame structure along a longitudinal axis to a tip that is coupled to an actuatable component,
a plurality of transversely oriented stiffeners protruding from a first surface of the actuator plate, and
an actuation material disposed on a second surface of the actuator plate that is opposite the first surface, wherein application of the drive signals to the actuation material results in a combination of transverse curvature of the actuator plate along a transverse axis and longitudinal curvature of the actuator plate along the longitudinal axis.

19. The system of claim 18 , wherein the longitudinal curvature produces an actuator stroke that corresponds to a deflection of the tip of the actuator plate.

20. The system of claim 18 , wherein a nominal height of the plurality of transversely oriented stiffeners is at least twenty times greater than a nominal thickness of the actuation material.

Assignees

• Microsoft Technology Licensing Llc

Inventors

• Mutikainen Risto Heikki
• Riekkinen Tommi
• Mattila Marco
• Chekurov Nikolay

Classifications

• H02N2/028

  along multiple or arbitrary translation directions, e.g. XYZ stages · CPC title

• B81B3/0043

  Increasing angular deflection · CPC title

• H02N2/065

  Large signal circuits, e.g. final stages · CPC title

• G02B26/0858 Primary

  the reflecting means being moved or deformed by piezoelectric means · CPC title

• H02N2/043 Primary

  Mechanical transmission means, e.g. for stroke amplification · CPC title