Issued Patents 1989
Showing 1–1 of 1 patents
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 4816933 | Magnetic recording medium of particular coercive force, filling ratio, and protrusions and recording/reproducing method therefor | Toshiaki Izumi, Kiyoshi Noguchi, Hisae Shimizu | 1989-03-28 |