Issued Patents 1989
Showing 1–3 of 3 patents
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| D304564 | Attendant telephone switchboard | Sadao Isozaki, Yasuko Yajima | 1989-11-14 |
| D303801 | Direct station telephone selector | Sadao Isozaki, Yasuko Yajima | 1989-10-03 |
| D300029 | Direct station telephone selector stand | Sadao Isozaki, Yasuko Yajima | 1989-02-28 |