Granted Patent
Utility
US 4,151,722 · App. 05/812,198
Automatic defrost control for refrigeration systems
Inventors:
Benjamin R. Willitts, Elmer D. Zickwolf
Patented Case
View Patent ↗
Granted: May 1, 1979
Filed: Jul 1, 1977
Inventors
Benjamin R. Willitts
Elmer D. Zickwolf
Assignee (at issue)
Emhart Industries, 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.