Issued Patents All Time
Showing 1–5 of 5 patents
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 4604606 | Audio signalling device | — | 1986-08-05 |
| 4581496 | Diaphragm for attenuating harmonic response in an electroacoustic transducer | — | 1986-04-08 |
| 4558305 | Multiple tone signaling device | Donald Black, James Pirtle | 1985-12-10 |
| RE30620 | High output smoke and heat detector alarm system utilizing a piezoelectric transducer and a voltage doubling means | Michael T. Burk | 1981-05-19 |
| 4213121 | Chime tone audio system utilizing a piezoelectric transducer | Richard L. Learn | 1980-07-15 |