| Number | Name | Date | Kind |
|---|---|---|---|
| 3100301 | Black | Aug 1963 | |
| 3751794 | Kay | Aug 1973 | |
| 3785277 | Schmitt | Jan 1974 | |
| 4394952 | Crane | Jul 1983 | |
| 4623083 | Pagano | Nov 1986 | |
| 4645113 | Webber | Feb 1987 | |
| 4824004 | Hanson | Apr 1989 | |
| 4846923 | Lines | Jul 1989 | |
| 5379513 | Thompson et al. | Jan 1995 | |
| 5600882 | Beane | Feb 1997 | |
| 5617622 | Anderson | Apr 1997 |
| Number | Date | Country |
|---|---|---|
| 1 258 792 | Jan 1968 | DE |
| 24-48 545 | Apr 1976 | DE |
| 2 773 097 | Jul 1999 | FR |
| Entry |
|---|
| EPO European Serach Report, dated Apr. 17, 2000, 4 pgs. |