GB602236A - Improvements in or relating to contacts of electron discharge devices - Google Patents

Abstract

602,236. Caps for discharge tubes ; metalto-glass seals. GENERAL ELECTRIC CO., Ltd., NIXON, R. D., and HILL, R. T. J. May 31, 1944, No. 10496. [Classes 36 and 38 (i)] [Also in Group XL (a)] In a contact element of the type consisting of a recessed metal button 6, Fig. 2, containing a terminal 8 and having a peripheral flange 9, the recessed portion of the button decreases in size towards the bottom of the recess, e.g. is of frusto-conical shape, as shown. The button 6 is sealed directly into an aperture of the glass envelope of a cathode-ray tube, the terminal 8 being intended for a snap connection. In the sealing operation the glass envelope is pierced at a suitably heated point by an internal gas pressure momentarily applied and a chuck holding the button is lowered to place it at the position shown in Fig. 2, the chuck is removed, and an inverted cone of gas jets is allowed to play on the button ; this causes the button to settle into its final position in the aperture with the flange 9 engaging the outer surface of the envelope 5, Fig. 1 (not shown). The button 6 may be of sheet chromium-iron alloy containing 16 per cent chromium, and the envelope may be of soda glass or lead glass whose coefficients of linear expansion are 10. 8 x 10<-6> and 9.6 x 10<-6> per degree Centigrade respectively. The button may act as a connection to an internal graphite coating of a cathode-ray tube. The Provisional Specification states that the coefficients of expansion of the button and the glass envelope are approximately the same.