Granted Patent
Utility
US 4,851,640 · App. 07/120,233
Frost plug heater
Inventor:
Edward Smith
Patented Case
View Patent ↗
Granted: Jul 25, 1989
Filed: Nov 13, 1987
Inventor
Edward Smith
Assignee (at issue)
The Budd 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.