The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 10, 2000
Filed:
Feb. 12, 1998
Bausan Yuan, San Jose, CA (US);
Ting-Chien Teng, Fremont, CA (US);
Nikon Corporation, Belmont, CA (US);
Abstract
A pair of complementary magnetic actuators controls a stage in a high-precision positioning instrument in a single coordinate direction. Additional pairs of complementary magnetic actuators can be used to provide control of the stage in other coordinate directions. A small current through the windings of both magnetic actuators provides a zero net force on the fine stage, thus maintaining the position of the fine stage. The small current used to control the fine stage minimizes the RMS power gain. By increasing the current in one magnetic actuator while decreasing the current in the other, a net force is generated for large accelerations of the stage. Control of the magnetic actuators is simplified by simultaneously increasing and decreasing the current through the windings of the complementary magnetic actuators prior to accelerating the stage. Additionally, a feedforward command can control the magnetic actuators to decrease the settling time of the system.