Granted Patent
Utility
US 5,651,528 · App. 08/431,271
Vacuum valve
Inventors:
Hugo Frei, Peter Keller, Martin Boesch
Patented Case
View Patent ↗
Granted: Jul 29, 1997
Filed: Apr 28, 1995
Inventors
Hugo Frei
Peter Keller
Martin Boesch
Assignee (at issue)
Balzers Aktiengesellschaft
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.