Granted Patent
Utility
US 4,530,706 · App. 06/312,201
Respirator cartridge end-of-service life indicator
Inventor:
John A. Jones
Patented Case
View Patent ↗
Granted: Jul 23, 1985
Filed: Oct 19, 1981
Inventor
John A. Jones
Assignee (at issue)
American Optical 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.