Monolithic stage positioning system and method
AssigneeElectro Scientific Industries, Inc.
InventorJoseph G. Frankel
Life of this patent
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Abstract
A magnetically levitated monolithic stage positioning system includes linear three phase motors and coil windings connected to the monolithic stage that interact with a ferromagnetic base. The linear three phase motors may be excited to provide motion in an X-axis direction, motion in a Y-axis direction, and rotation about a Z-axis. The monolithic stage is levitated on an air bearing. The plurality of coil windings connected to the monolithic stage may serve to magnetically preload the air bearing. The plurality of coil windings may be excited to provide motion in a Z-axis direction and rotation of the monolithic stage about the X-axis and about the Y-axis.
Claims20
A system for positioning a workpiece, the system comprising:
- a monolithic stage configured to support the workpiece, the monolithic stage comprising a plurality of linear forcers;
- a ferromagnetic base positioned below the monolithic stage;
- an air bearing between the monolithic stage and the ferromagnetic base, the air bearing to provide a levitating force to the monolithic stage;
- a magnetic track coupled to the base plate, the magnetic track creating a magnetic field, the linear forcers each operable to carry a current through the magnetic field created by the magnetic track, the currents generating forces to provide planar motion to the monolithic stage in three degrees of freedom;
- and
- at least one coil winding attached to the monolithic stage, the at least one coil winding to provide motion in at least one other degree of freedom using magnetic attraction with the ferromagnetic base plate.
A method for positioning a workpiece, the method comprising:
- providing a monolithic stage to carry a workpiece;
- generating an air bearing between a ferromagnetic base and the monolithic stage by forcing pressurized air out of an orifice in the monolithic stage, the air bearing providing a levitating force to the monolithic stage;
- generating a magnetic field using a magnetic track;
- selectively driving a current through a plurality of linear forcers attached to the monolithic stage in the presence of the magnetic field, such that the current selectively generates forces to provide planar motion to the driven linear forcers;
- and
- selectively driving a current through at least one coil winding attached to the monolithic stage to provide motion in at least one other degree of freedom using magnetic attraction with the ferromagnetic base.
A system for positioning a workpiece, the system comprising:
- means for carrying a workpiece on a monolithic stage;
- means for generating an air bearing between a ferromagnetic base and the monolithic stage by forcing pressurized air out of an orifice in the monolithic stage, the air bearing providing a levitating force to the monolithic stage;
- means for generating a magnetic field using a magnetic track;
- means for selectively driving a current through a plurality of linear forcers attached to the monolithic stage in the presence of the magnetic field, such that the current selectively generates forces to provide planar motion to the driven linear forcers;
- and
- means for selectively driving a current through at least one coil winding attached to the monolithic stage to provide motion in at least one other degree of freedom using magnetic attraction with the ferromagnetic base.
Dependencies are inferred from the claim text.