|
| US4490055 | 30 Jun 1982 | 25 Dic 1984 | International Business Machines Corporation | Automatically adjustable delay function for timed typamatic |
| US4824269 | 1 Feb 1988 | 25 Abr 1989 | | Variable color display typewriter |
| US4934852 | 11 Abr 1989 | 19 Jun 1990 | | Variable color display typewriter |
| US5982357 | 12 Mar 1997 | 9 Nov 1999 | Key Tronic Corporation | Computer keyboard systems and methods for determining excessive key stroke force |