Granted Patent
Utility
US 6,389,641 · App. 09/094,756
Dual mode debris pickup machine
Inventors:
Steven L. Boomgaarden, Michael L. Blehert, Gregory J. Engel
Patented Case
View Patent ↗
Granted: May 21, 2002
Filed: Jun 15, 1998
Inventors
Steven L. Boomgaarden
Michael L. Blehert
Gregory J. Engel
Assignee (at issue)
TENNANT COMPANY
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.