Granted Patent
Utility
US 5,138,733 · App. 07/674,123
Ultrasonic toothbrush
Inventor:
Robert T. Bock
Patented Case
View Patent ↗
Granted: Aug 18, 1992
Filed: Mar 25, 1991
Inventor
Robert T. Bock
Assignee (at issue)
Sonex International 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.