Granted Patent
Utility
US 4,921,639 · App. 07/268,712
Ultrasonic humidifier
Inventor:
Bernard Chiu
Patented Case
View Patent ↗
Granted: May 1, 1990
Filed: Nov 9, 1988
Inventor
Bernard Chiu
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.