Granted Patent
Utility
US 4,122,006 · App. 05/837,376
Screening apparatus
Inventors:
Elmer Christensen, Kenneth M. Cage
Patented Case
View Patent ↗
Granted: Oct 24, 1978
Filed: Sep 28, 1977
Inventors
Elmer Christensen
Kenneth M. Cage
Assignee (at issue)
Black Clawson Company, 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.