Granted Patent
Utility
US 4,914,593 · App. 07/204,386
Method for automatic depth control for earth moving and grading
Inventors:
Christopher O. Middleton, Colin L. Robson
Patented Case
View Patent ↗
Granted: Apr 3, 1990
Filed: Jun 9, 1988
Inventors
Christopher O. Middleton
Colin L. Robson
Assignee (at issue)
Spectra-Physics, 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.