| 摘要 |
624,013. Discharge lamps. PHILIPS LAMPS, Ltd. Sept. 18, 1946, No. 28007. Convention date, Aug. 13, 1942. [Class 39 (i)] In a high-pressure mercury vapour discharge device comprising one or more incandescent electrodes which are heated solely by the discharge during operation, each electrode comprises a tungsten strip or band 2, Fig. 2, folded so as to have are-entrant part which contains the electron emissive substance 4, the ends of the band or strip being secured to the same part of a lead-in conductor so that the band or strip forms a substantially closed surface. The strip or band 2 may be heart-shaped as in Fig. 2, or flattened as in Fig. 3, and its thickness in microns is less than 100 times the operating current in amperes, while its width is at least 10 times its thickness, e.g. it may be 0.1 mm. thick, 5 mms. wide, and 20 mms. long. The emissive substance 4 is barium and/or strontium oxide with, if desired, quartz powder, and the filling is a rare gas such as argon at 4 mms. and mercury vapour which is unsaturated ; the total vapour pressure during operation is about one atmosphere. The tube emits visible or ultra-violet light and works on A.C. |
