Granted Patent
Utility
US 4,938,421 · App. 07/358,248
Cleaning liquid mixer for a water line, particularly for a surface cleaner
Inventors:
Robert C. Berfield, Ronald F. Meland
Patented Case
View Patent ↗
Granted: Jul 3, 1990
Filed: May 26, 1989
Inventors
Robert C. Berfield
Ronald F. Meland
Assignee (at issue)
SHOP VAC CORPORATION
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.