Granted Patent
Utility
US 4,988,424 · App. 07/362,645
Mask and method for making gradient sputtered coatings
Inventors:
Danny L. Woodward, Chester Thrasher
Patented Case
View Patent ↗
Granted: Jan 29, 1991
Filed: Jun 7, 1989
Inventors
Danny L. Woodward
Chester Thrasher
Assignee (at issue)
PPG 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.