Issued Patents All Time
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 4846502 | Tamper evident document and use thereof | John C. H. Chang | 1989-07-11 |
| 4448445 | Pressure-sensitive record system | John C. H. Chang | 1984-05-15 |
| Patent # | Title | Co-Inventors | Date |
|---|---|---|---|
| 4846502 | Tamper evident document and use thereof | John C. H. Chang | 1989-07-11 |
| 4448445 | Pressure-sensitive record system | John C. H. Chang | 1984-05-15 |