Number | Date | Country | Kind |
---|---|---|---|
2731690 | Oct 1977 | DEX |
Number | Name | Date | Kind |
---|---|---|---|
2117398 | Brown, Jr. | May 1938 | |
2484886 | Henry | Oct 1949 | |
4120039 | Fischer | Oct 1978 | |
4128889 | Ojima et al. | Dec 1978 |
Entry |
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IBM Technical Disclosure Bulletin "Optical Key Board" by J. J. Sharp et al., vol. 5, No. 10, Mar. 1963, p. 127. |