GB504934A - Improvements in closures for evacuated envelopes and method of manufacturing the same - Google Patents

Abstract

504,934. Uniting metal to vitreous material by heat; cathode - ray tubes. DEHN, F. B. (Hygrade Sylvania Corporation) Nov. 1, 1937, No. 29858. [Class 36] [Also in Group XL] A vitreous plate 10, Fig. 3, surrounded by a metal frame 2 having its. inner edge 1 embedded in the periphery of the plate, is formed by clamping the outer portion of the frame between, clamping members 3, 8, Fig. 1, which also constitute a mould for shaping a molten mass of vitreous material into the plate. The vitreous mass is pressed outwardly into engagement with the edge of the frame by a plunger 9, the temperature of the mass when placed in the mould being such that the edge of the frame, which is preferably oxidized, is reised to a temperature of about 500‹ C. by the vitreous material when the latter is pressed into contact with the frame. The frame is preferably of an iron, nickel and cobalt alloy, the vitreous material being a glass having the same coefficient of expansion as the alloy. Fig. 4 shows a cathode ray tube, the window of which is formed by a device constructed as above. The rim of the frame 2 is sealed to a tapered metal tube 11 to which a glass stem tube 13 is sealed, with the interposition of a short sleeve 12 of metal known under the Registered Trade Mark " Kovar." Fig. 6 shows a device for closing the shell 37 of a metal radio tube and for supporting the electrode structure thereof. The device comprises a vitreous plate 34 having electrode-supporting and leading-in wires 35 sealed therein and formed with an exhaust tube 36. A flanged metal ring 33, adapted to be welded to the shell 37 has its inner edge embedded in the plate 34. The device is formed by pressing a molten mass of vitreous material around the wires 35 and into contact with the inner edge of the ring 33 by means of a mould 28, 29, as shown in Fig. 5. The wires 35 may also serve as contact pins.