Granted Patent
Utility
US 4,663,128 · App. 06/709,056
Pulling head for a crystal growing furnace
Inventor:
Walter Helgeland
Patented Case
View Patent ↗
Granted: May 5, 1987
Filed: Mar 6, 1985
Inventor
Walter Helgeland
Assignee (at issue)
Ferrofluidics 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.