GB815782A - Improvements in or relating to electric discharge lamps - Google Patents

Abstract

815,782. Discharge lamps. GENERAL ELECTRIC CO. Ltd. March 15, 1956 [April 14, 1955], No. 10757/55. Class 39(1). A discharge lamp of the type comprising a U-shaped envelope 1 mounted or arranged for mounting within a cylindrical single or double walled outer jacket 6 has a supporting device in the form of a spring clip 15 having opposed spring members 16 clipped over the curved end of the envelope, and resilient abutment members 17 which bear against the inner surface of the outer jacket. The spring members 16 can bear against the outer surfaces of tubular glass sleeves 23 fitting closely around the limbs of the envelope, as described in Specification 801,482, and can also bear against the inner surface of the outer jacket. The part of the device 15 having the spring members 16 is connected to the part having the abutment members 17 by four bentover tags 20. In modifications the two parts of the device 15 can be connected by spot welding or by means of a metal eyelet within the holes 21, or the whole device 15 can be stamped or pressed from a single flat sheet. The exhaust pipe 22 is arranged at the centre of the curved end of the envelope and fits within holes 21 in the supporting device 15. The filling comprises neon containing 0À75 per cent. by volume of argon at a total pressure of 14 mms, together with about 1 gram of sodium, and the inner surface of the envelope has a coating of sodium resistant glass. Movement of the glass sleeves 23 is prevented at one end by a coiled spring metal strip 14 located in a circular gap 12 in the curved end of the envelope and at the other end by a substantially rectangular mica sheet 24 with curved ends. The sheet 24 has holes for the passage of electrode leads 5 and is supported by two wires 25 twisted round a different pair of the electrode leads and passing through two indentations 26 in the sheet 24 and winding helically around a different one of the sleeves 23. The end of one of the spring members 16 is turned over on to a mica tag 27 which provides an anchor for the two wires 25 which can act as starting aids. The mounting wires 9 are each connected to a corresponding pair of the leads 5 by a metal sleeve 13 which fits over and is welded to the end of the wire 9, the ends of the pair of leads 5 and the corresponding wire 25. A closed conducting loop 29 including a cored getter wire 28 can be heated by eddy currents and is supported by a wire 30. The wire 28 is shielded from the mica sheet 24 and the envelope 1 by a channel shaped shield member 31.