Granted Patent
Utility
US 4,448,873 · App. 06/359,460
Negative working diazo contact film
Inventors:
John E. Walls, Major S. Dhillon
Patented Case
View Patent ↗
Granted: May 15, 1984
Filed: Mar 18, 1982
Inventors
John E. Walls
Major S. Dhillon
Assignee (at issue)
American Hoechst 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.