Granted Patent
Utility
US 4,743,795 · App. 06/874,098
Multi-graded aperture masks
Inventor:
Roland Thoms
Patented Case
View Patent ↗
Granted: May 10, 1988
Filed: Jun 13, 1986
Inventor
Roland Thoms
Assignee (at issue)
BMC Industries, Inc.
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.