Granted Patent
Utility
US 4,828,694 · App. 07/142,071
Filter with filtration envelope spacing means
Inventor:
Hayden Leason
Patented Case
View Patent ↗
Granted: May 9, 1989
Filed: Jan 11, 1988
Inventor
Hayden Leason
Assignee (at issue)
Filtertek 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.