Power plants – Motor operated by expansion and/or contraction of a unit of... – Mass is a solid
Reexamination Certificate
2000-02-04
2001-12-11
Nguyen, Hoang (Department: 3748)
Power plants
Motor operated by expansion and/or contraction of a unit of...
Mass is a solid
C060S527000
Reexamination Certificate
active
06327855
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to the field of mechanical systems and methods and more particularly, to mechanical actuators and methods.
Bimorph microactuators are discussed, for example, in the reference by M. Edward Motamedi et al. entitled Development Of Micro-Electro-Mechanical Optical Scanner. (Opt. Eng. 36(5) 1346-1353, May 1997.) In particular, bimorph microactuators are micromachined beams whose curvatures can be controlled by applying electrical signals. The simplest bimorph actuator is a composite beam with different structural and electrical properties in its individual layers. The behavior of a bimorph actuator can depend on the dimensions, densities, elastic coefficients, thermal expansion coefficients, and/or piezoelectric properties of the individual layers making up the beam.
The use of a bimorph actuator beam in a monolithic silicon integrated optical micro-scanner is discussed in the reference by S. Calmes et al. entitled Resonating Large Angle And Low Consumption Micromachined Optical Scanner. (SPIE Vol. 3276, pp. 96-102, 1998.) In this reference, the device includes a mirror located on the tip of a thermal bimorph actuator beam. The device is excited electrothermomechanically at its resonance frequency, enabling large angular deflections at low power consumption. Additional bimorph actuator structures are discussed in the reference by Xi-Qing Sun et al. entitled A Bistable Microrelay Based On Two-Segment Multimorph Cantilever Actuators (Proceedings of the IEEE Micro Electro Mechanical Systems, 1998, pp. 154-159). The disclosures of each of the Motamedi et al., Calmes et al., and Sun et al. references are hereby incorporated herein in their entirety by reference.
Notwithstanding the bimorph actuators discussed above, there continues to exist a need in the art for improved actuators and methods of forming the same.
SUMMARY OF THE INVENTION
An actuator according to the present invention may comprise a serpentine arrangement of alternating actuating and opposing segments wherein the actuating segments deflect in response to actuation thereof. In particular, the actuating segments may bend or deflect in a first direction during actuation while the opposing segments do not deflect significantly or deflect in a direction opposite that of the actuating segments. The opposing segments can thus increase an overall deflection of the actuator without increasing the length of the actuating segments. Moreover, the actuator is scalable so that a greater deflection can be achieved by adding additional alternating actuating and opposing segments. By providing opposing segments to deflect in a direction opposite that of the actuating segments, greater deflections can be obtained. Alternately, the opposing segments may deflect in the same direction as the actuating segments but to a lesser degree.
A micromechanical system according to the present invention can include a substrate, an actuator, and an actuated element. In particular, the actuator can include a serpentine arrangement of alternating actuating and opposing segments anchored at a first end thereof to the substrate wherein the actuating segments deflect in response to actuation thereof so that a second end of the serpentine arrangement moves relative to the substrate upon deflection of the actuating segments. The actuated element is attached to the second end of the serpentine arrangement so that the actuated element moves relative to the substrate upon deflection of the actuating segments.
More particularly, each of the actuating segments may comprise a bimorph segment including a first layer of a first material having a first coefficient of thermal expansion and a second layer of a second material having a second coefficient of thermal expansion different than the first coefficient of thermal expansion so that the actuating segments deflect in response to changes in temperature thereof. In addition, the alternating actuating and opposing segments may comprise parallel beams, and a second end of the serpentine arrangement may rotate about an axis perpendicular to the parallel beams. The substrate may also include a trench therein adjacent the serpentine arrangement to reduce interference with the actuator.
The system may also include a second actuator including a second serpentine arrangement of alternating actuating and opposing segments anchored at a first end thereof to the substrate. The actuating segments of the second actuator may deflect in response to actuation thereof so that a second end of the second serpentine arrangement moves relative to the substrate upon deflection of the actuating segments, and the second end of the second serpentine arrangement can be attached to the actuated element. In addition, the system may include an electrical path between the respective second ends of the first and second serpentine arrangements of the respective first and second actuators, and a signal generator. The signal generator can be coupled between the first ends of the first and second serpentine arrangements of the respective first and second actuators so that an electrical signal generated by the signal generator actuates the actuating segments of the first and second serpentine arrangements.
Actuators, systems, and methods according to the present invention can thus provide increased ranges of rotation and/or motion in micromechanical systems.
REFERENCES:
patent: 5903380 (1999-05-01), Motamedi et al.
patent: 6044646 (2000-04-01), Silverbrook
patent: 6067797 (2000-05-01), Silverbrook
patent: 6070851 (2000-06-01), Tsai et al.
patent: 0875780 A2 (1998-11-01), None
patent: WO 99/24783 (1999-05-01), None
Manalis, Scott Robert,Optical Detection for Microfabricated Cantilever Arrays,Dissertation (1998).
Elwenspoek, M., et al., Active joints for microrobot limbs,J. Micromech. Microeng.,vol. 2, pp. 221-223 (1992).
Lin, G., et al., Design, Fabrication, and Testing of a C-Shape Actuator, The 8thInternational Conference on Solid-State Sensors and Actuators, and Eurosensors, pp. 416-419 (Stockholm, Sweden, Jun. 25-29, 1995).
Suh, John W., et al., Organic thermal and electrostatic ciliary microactuator array for object manipulation,Sensors and Actuators A,vol. 58, pp. 51-60 (1997).
Lin, Yuh-Sheng, et al., Thermally Actuated Bimorph Microactuators,Journal of the Chinese Society of Mechanical Engineers,vol. 18, No. 6, pp. 525-531 (1997).
Sun, Xi-Qing, et al., A Bistable Microrelay Based on Two-Segment Multimorph Cantilever Actuators,The Eleventh Annual International Workshop on Micro Electro Mechanical Systems, IEEE,pp. 154-159 (1998).
Calmes, S., et al., Resonating Large Angle and Low Consumption Micromachined Optical Scanner,SPIE,vol. 3276, pp. 96-102 (1998).
Motamedi, M. Edward, et al., Development of micro-electro-mechanical optical scanner,Opt. Eng.,vol. 36, pp. 1346-1353 (May 1997).
Motamedi, M. E., et al., MOEM scan engine for bar code reading and factory automation,SPIE,vol. 3276, pp. 66-80 (1998).
Dhuler Vijayakumar Rudrappa
Hill Edward A.
JDS Uniphase Inc.
Myers Bigel & Sibley & Sajovec
Nguyen Hoang
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