Granted Patent
Utility
US 4,301,978 · App. 06/027,412
Electro-magnetic thread tension control for sewing machines
Inventors:
John A. Herr, Wolfgang Jaffe
Patented Case
View Patent ↗
Granted: Nov 24, 1981
Filed: Apr 5, 1979
Inventors
John A. Herr
Wolfgang Jaffe
Assignee (at issue)
The Singer Company Limited
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.