Granted Patent
Utility
US 4,575,619 · App. 06/608,348
Electrical heating unit with serpentine heating element
Inventor:
Ludwig Porzky
Patented Case
View Patent ↗
Granted: Mar 11, 1986
Filed: May 8, 1984
Inventor
Ludwig Porzky
Assignee (at issue)
Federal Signal 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.