Issued Patents All Time
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 5122710 | Rare earth phosphor blends for fluorescent lamp using four to five phosphors | Donald P. Northrop | 1992-06-16 |
| 4891550 | Phosphor blend for broad spectrum fluorescent lamp | Donald P. Northrop, Arpad Pirovic | 1990-01-02 |