Granted Patent
Utility
US 4,720,628 · App. 06/923,367
Optical process for determining the endpoint of a process via analog multiplication of photocell signals
Inventor:
Herbert G. Drake, Jr.
Patented Case
View Patent ↗
Granted: Jan 19, 1988
Filed: Oct 27, 1986
Inventor
Herbert G. Drake, Jr.
Assignee (at issue)
TEGAL 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.