GB715479A - Improvements relating to electric discharge tubes - Google Patents

Abstract

715,479. Electric discharge lamps. METROPOLITAN-VICKERS ELECTRICAL CO., Ltd. May 28, 1952 [July 19, 1951], No. 17183/51. Class 39(1) An electric discharge device adapted for connection to a vacuum system to provide by glow discharge an indication of the state of the vacuum comprises an inner transparent discharge tube 1 closed at one end with an electrode 3 sealed therethrough and open at the other end where it is encircled by a sealing ring 13 of rubber or other resilient material so located between co-operating flanges provided on an outer protective tube 2 and on a mounting member 10' connected to the vacuum system that the action of drawing together the flanges by a union nut 11 on mounting the device presses the ring 13 inwardly against the inner tube 1 to form a seal therewith. One of the flanges can be chamfered as shown or both flanges can be chamfered as shown in Fig. 1 (Prov.). A spring loaded contact 4 abuts against a portion of the electrode 3 outside the inner tube 1 and is arranged inside an insulating member 20 having a skirt portion screwed into the end of the tube 2 and housing a plug and socket connecter 19 to a high tension conductor. In the construction shown in Fig. 3 of the drawings accompanying the Provisional Specification the insulating member 20, preferably made of moulded plastic material, is rotatably secured to the tube 2, which may be made of metal, by spinning over the tube 2 at 21 so that the lead 6 can enter in a desired direction. The member 20 and tube 2 may be made integrally of moulded plastic material. In the construction shown in Figs. 1 (Prov.) and 2 the spring loaded contact 4 is arranged inside a closed end of the outer tube 2 and is connected to a terminal element 5 surrounded by a rubber protective cover 7 having a sleeve 14 accommodating the voltage supply conductor, 6, 6<SP>1</SP>, Fig. 1 (Prov.): or is connected to a button contact 15 engaged by a spring clip connector 16 connected through a soldering joint 17 to the supply conductor 6, 6<SP>1</SP>. The connector 16, &c., is housed in an insulating cover 18, preferably of moulded plastic material, and the tube 2 may be of metal with an insulating bushing for the contact 15 or may be of moulded plastic material. The tube 2 is provided with a window 8 for observing the glow discharge in the tube 1.