Granted Patent
Utility
US 3,934,372 · App. 05/513,633
Portable upblast cleaning head
Inventors:
Philip H. Diehn, John C. Bergh
Patented Case
View Patent ↗
Granted: Jan 27, 1976
Filed: Oct 10, 1974
Inventors
Philip H. Diehn
John C. Bergh
Assignee (at issue)
Wheelabrator-Frye Inc.
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.