Granted Patent
Utility
US 4,467,891 · App. 06/508,400
Lock mechanism for extension ladder
Inventor:
Jonathan L. Shaw
Patented Case
View Patent ↗
Granted: Aug 28, 1984
Filed: Jun 27, 1983
Inventor
Jonathan L. Shaw
Assignee (at issue)
AT&T Technologies Incorporated
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.