Granted Patent
Utility
US 5,618,246 · App. 08/500,488
Collapsible play tunnel structures
Inventor:
Yu Zheng
Patented Case
View Patent ↗
Granted: Apr 8, 1997
Filed: Jul 10, 1995
Inventor
Yu Zheng
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.