Issued Patents 1989
Showing 1–2 of 2 patents
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 4886703 | Magnetic recording medium | Kazuo Hasumi, Hideomi Watanabe, Tsutomu Okita, Katsumi Ryoke | 1989-12-12 |
| 4803121 | Magnetic recording medium | Katsumi Ryoke, Masatoshi Takahashi, Toshimitu Okutu | 1989-02-07 |