Granted Patent
Utility
US 4,821,750 · App. 07/121,816
Cigarette filters
Inventor:
Colin L. Browne
Patented Case
View Patent ↗
Granted: Apr 18, 1989
Filed: Nov 16, 1987
Inventor
Colin L. Browne
Assignee (at issue)
Celanese GmbH
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.