| 摘要 |
592,163. Piezo - electric crystals. BRUSH DEVELOPMENT CO. Feb. 19, 1943, No. 2835. Convention date, July 7, 1941. [Class 40 (v)] A piezo-electric device comprising a watersoluble crystal unit, has a moisture-proof sheath or envelope for thermit and a layer of moisture-proof material coating the entire unit between the sheath and the unit to prevent the spread of moisture between the unit and the sheath. In Fig. 4, the crystal unit comprises two plates 10, 11 of Rochelle salt, having an internal graphite electrode 14 and outer electrodes 15 connected by a foil strip 16, the external leads being not shown. The unit is first given a coating 21 of adhesive waterproof material such as shellac, which also serves to round the edges and corners and so facilitate the provision of a sheath or envelope 22 of tin foil. Finally, a second coating 23 is provided outside the tin foil, Slight modifications are also described, Figs. 5 and 6 (not shown). Specification 454,595 and U.S.A. Specification 2,266,333 are referred to. |
