Granted Patent
Utility
US 4,992,807 · App. 07/518,955
Gray scale printhead system
Inventor:
Christopher Thomson
Patented Case
View Patent ↗
Granted: Feb 12, 1991
Filed: May 4, 1990
Inventor
Christopher Thomson
Assignee (at issue)
Delphax Systems
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.