Granted Patent
Utility
US 4,540,946 · App. 06/564,358
Variable characteristic filters
Inventors:
Antonio J. Sainz, Victor C. Roberts
Patented Case
View Patent ↗
Granted: Sep 10, 1985
Filed: Dec 22, 1983
Inventors
Antonio J. Sainz
Victor C. Roberts
Assignee (at issue)
NATIONAL RESEARCH DEVELOPMENT 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.