Issued Patents 1989
Showing 1–2 of 2 patents
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 4847480 | Focus error detecting apparatus | Takanori Maeda | 1989-07-11 |
| 4815060 | Optical pickup device with tracking and focusing utilizing a photodetector having four regions | — | 1989-03-21 |