Granted Patent
Utility
US 5,678,539 · App. 08/574,273
Respirator with an input and output unit
Inventors:
Ernst-Wilhelm Schubert, Roland Zarske, Hans R. Wagner
Patented Case
View Patent ↗
Granted: Oct 21, 1997
Filed: Dec 18, 1995
Inventors
Ernst-Wilhelm Schubert
Roland Zarske
Hans R. Wagner
Assignee (at issue)
DRAGERWERK AKTIEGESELLSCHAFT
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.