| Number | Date | Country | Kind | 
|---|---|---|---|
| 100 33 101 | Jul 2000 | DE | 
| Number | Name | Date | Kind | 
|---|---|---|---|
| 2379243 | Milne | Jun 1945 | A | 
| 2755601 | Lux | Jul 1956 | A | 
| 3133533 | Sprague | May 1964 | A | 
| 4004378 | Maxey | Jan 1977 | A | 
| 5471970 | Sakarcan | Dec 1995 | A | 
| 5758561 | Curtsinger | Jun 1998 | A | 
| 6277017 | Ji | Aug 2001 | B1 | 
| 6408838 | Ogata et al. | Jun 2002 | B1 | 
| Number | Date | Country | 
|---|---|---|
| 1959323 | Apr 1967 | DE | 
| 9638718 | Oct 1997 | DE | 
| 0905075 | Feb 1982 | RU | 
| Entry | 
|---|
| Patent Abstract of Japan No. 03-287,382, Dec. 12, 1991. |