| Number | Date | Country | Kind |
|---|---|---|---|
| 3-10351[U] | Feb 1991 | JPX |
| Number | Name | Date | Kind |
|---|---|---|---|
| 2158925 | Braswell | May 1939 | |
| 2502985 | Paulson | Apr 1950 | |
| 2879940 | Cornell | Mar 1959 | |
| 3593517 | Knippler | Jul 1971 | |
| 3890777 | Stanish | Jun 1975 |
| Number | Date | Country |
|---|---|---|
| 3940254 | Jun 1991 | DEX |
| 1018684 | Jan 1953 | FRX |
| 2473202 | Jul 1981 | FRX |
| Entry |
|---|
| Patent Abstracts of Japan vol. 5, No. 157 (P-83) (829) Oct. 8, 1981. |