Issued Patents All Time
Showing 1–2 of 2 patents
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 4797904 | Transmitter for | Johannes H. M. Velthof | 1989-01-10 |
| 4742534 | Telephone receiving equipment for recognizing predetermined combinations of voice-frequency signalling components | Robert J. M. Verbeek, Rudolf Van Bokhorst, Johannes H. M. Velthof | 1988-05-03 |