Issued Patents 1989
Showing 1–4 of 4 patents
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 4880692 | Magnetic recording medium | Katsumi Ryoke, Akihiro Hashimoto, Tsutomu Okita, Kazuko Hanai | 1989-11-14 |
| 4880693 | Magnetic recording medium | Katsumi Ryoke, Akihiro Hashimoto, Tsutomu Okita, Takashi Yoneyama | 1989-11-14 |
| 4868060 | Magnetic recording medium | Katsumi Ryoke, Toshimitu Okutu, Yasuyuki Yamada | 1989-09-19 |
| 4803121 | Magnetic recording medium | Katsumi Ryoke, Toshimitu Okutu, Hideaki Kosha | 1989-02-07 |