| Number | Date | Country | Kind |
|---|---|---|---|
| 2-318853 | Nov 1990 | JPX | |
| 2-318854 | Nov 1990 | JPX |
| Number | Name | Date | Kind |
|---|---|---|---|
| 2630751 | Cranston et al. | Mar 1953 | |
| 3031368 | Zent | Apr 1962 | |
| 3245860 | Aurich et al. | Apr 1966 | |
| 3547737 | Vici | Dec 1970 | |
| 3580785 | Mihalkanin | May 1971 | |
| 4264398 | Pruitt | Apr 1981 | |
| 4436550 | Ferree | Aug 1982 | |
| 4502905 | Jung et al. | Mar 1985 | |
| 4602976 | Fukuda et al. | Jul 1986 | |
| 4756143 | Lancaster | Jul 1988 | |
| 4790896 | Schmalhotz | Dec 1988 | |
| 5041185 | Ohashi et al. | Aug 1991 |
| Number | Date | Country |
|---|---|---|
| 4032511 | Apr 1992 | DEX |
| 7321512 | Jan 1974 | FRX |
| 63-248616 | Oct 1988 | JPX |
| Entry |
|---|
| European Search Report (Feb. 9, 1993). |