|
| US4477700 | 14 nov 1983 | 16 okt 1984 | Rogers Corporation | Tactile membrane keyboard with elliptical tactile key elements |
| US4536625 | 13 apr 1984 | 20 aug 1985 | | Keyboard design |
| US4571466 | 6 aug 1984 | 18 feb 1986 | Kokoku Rubber Industrial Company Limited | Spring unit for a keyboard |
| US4855174 | 19 mar 1986 | 8 aug 1989 | | Lagging-reinforced structure |
| US6657146 | 15 nov 2000 | 2 dec 2003 | Thomson Licensing, S.A. | Button ball and alignment rib |
