Granted Patent
Utility
US 5,669,578 · App. 08/532,199
Crush-proof extrusion core
Inventor:
Ming Ma
Patented Case
View Patent ↗
Granted: Sep 23, 1997
Filed: Sep 22, 1995
Inventor
Ming Ma
Assignee (at issue)
NCR 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.