Granted Patent
Utility
US 6,184,640 · App. 09/299,466
DC brushless motor, magnetic bearing device and turbomolecular pump device
Inventor:
Toshiaki Kawashima
Patented Case
View Patent ↗
Granted: Feb 6, 2001
Filed: Apr 26, 1999
Inventor
Toshiaki Kawashima
Assignee (at issue)
Seiko Seiki Kabushiki Kaisha
This patent predates the USPTO's electronic file wrapper — prosecution documents from this era exist only in the Patent Office's paper records. A certified copy of the file history can be ordered from the USPTO's paper archives.