Electrical generator or motor structure – Non-dynamoelectric – Thermal or pyromagnetic
Reexamination Certificate
2000-03-28
2001-12-25
Mullins, Burton S. (Department: 2834)
Electrical generator or motor structure
Non-dynamoelectric
Thermal or pyromagnetic
C060S527000, C337S141000, C361S164000
Reexamination Certificate
active
06333583
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to electromechanical systems, and more particularly to microelectromechanical systems.
BACKGROUND OF THE INVENTION
MicroElectroMechanical Systems (MEMS) have been developed as alternatives to conventional electromechanical devices, such as relays, actuators, valves and sensors. MEMS devices are potentially low-cost devices, due to the use of microelectronic fabrication techniques. New functionality also may be provided, because MEMS devices can be much smaller than conventional electromechanical devices.
A major breakthrough in MEMS devices is described in U.S. Pat. No. 5,909,078 entitled Thermal Arched Beam Microelectromechanical Actuators to Wood et al. (Wood), the disclosure of which is hereby incorporated herein by reference. Wood discloses a family of thermal arched beam microelectromechanical actuators that include an arched beam which extends between spaced-apart supports on a microelectronic substrate. The arched beam expands upon application of heat thereto. For example, as described in Wood, a current is passed through the arched beams to cause thermal expansion thereof. Alternatively, as described in Wood, the thermal arched beams are heated by an external heater across an air gap.
When used as a microelectromechanical actuator, thermal expansion of the arched beam can create relatively large displacement and relatively large forces while consuming reasonable power. Thermal arched beams can be used to provide actuators, relays, sensors, microvalves and other MEMS devices. Other thermal arched beam microelectromechanical devices and associated fabrication methods are described, for example, in U.S. Pat. No. 5,994,816 to Dhuler et al. entitled Thermal Arched Beam Microelectro-mechanical Devices and Associated Fabrication Methods, the disclosure of which is hereby incorporated herein by reference. Notwithstanding the above, there continues to be a need to further improve MEMS devices.
SUMMARY OF THE INVENTION
The present invention can provide thermally actuated microelectromechanical structures including thermally actuated arched beams on heaters, wherein the arched beams remain on heaters as the arched beams displace. Accordingly, the present invention may provide improved transient thermal response and improved thermal efficiency. In particular, the arched beam on the heater moves therewith as the arched beam displaces. Therefore, heat can be directly applied to the arched beam, thereby allowing a reduction in thermal loss due to an air gap between the heater and the arched beam.
In contrast, conventional systems may include an air gap between a heater and a beam. Unfortunately the air gap can increase the thermal resistance and hence reduce heat flux. The air gap can also deteriorate the transient thermal response of the system.
According to the present invention an air gap between the heater and arched beam may not need to be heated with the arched beam, thereby allowing improved transient thermal response. Displacing the heater as the arched beam displaces may further reduce thermal loss and transient thermal response by reducing the separation between the heater and the arched beam as the arched beam displaces.
In particular, microelectromechanical structures according to the present invention can include spaced-apart supports on a microelectronic substrate and a beam, preferably an arched beam, that extends between the spaced-apart supports and that expands upon application of heat thereto to thereby cause displacement of the beam. The beam is on a heater that applies heat to the beam and displaces with the beam as the beam displaces.
In one embodiment of the present invention, a second beam extends between spaced-apart supports. The first and second beams are attached to a coupler on the heater, wherein the heater displaces with the coupler. The coupler may mechanically strengthen the coupling between the first and second beams. In another embodiment, the first and second beams are separate from the coupler and are located thereon.
In another embodiment according to the present invention, a scalable microelectromechanical structure can include moveable spaced-apart supports on a microelectronic substrate and a cross-beam that extends between the moveable spaced-apart supports. A first arched beam is arched in a first predetermined direction and expands in the first predetermined direction upon application of heat thereto to thereby cause displacement of the first arched beam relative to the moveable spaced-apart supports. A first arched beam is on a first heater that applies heat thereto and displaces with the first arched beam as the first arched beam displaces. A second arched beam is arched in a second predetermined direction and expands in the second predetermined direction upon application of heat thereto to thereby cause displacement of the second arched beam relative to the moveable spaced-apart supports. The second arched beam is on a second heater that applies heat thereto and displaces with the second beam as the second beam displaces.
In another embodiment according to the present invention, the spaced-apart supports are on heaters, wherein the heaters can move with the moveable spaced-apart supports.
REFERENCES:
patent: 4864824 (1989-09-01), Gabriel et al.
patent: 5335498 (1994-08-01), Komatsu et al.
patent: 5619177 (1997-04-01), Johnson et al.
patent: 5909078 (1999-06-01), Wood et al.
patent: 5994816 (1999-11-01), Dhuler et al.
patent: 61-190177 (1986-08-01), None
patent: 61-199477 (1986-09-01), None
patent: 5-284765 (1993-10-01), None
U.S. Patent Application Entitled: Multi-Dimensional Scalable Displacement Enabled Microelectromechanical Actuator Structures and Arrays; Filed May 3, 1999.
Cowen Allen
Hill Edward A.
Mahadevan Ramaswamy
Wood Robert L.
JDS Uniphase Corporation
Mullins Burton S.
Myers Bigel & Sibley & Sajovec
LandOfFree
Microelectromechanical systems including thermally actuated... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Microelectromechanical systems including thermally actuated..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Microelectromechanical systems including thermally actuated... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2562815