US2875358A - Sodium vapour electric discharge lamps - Google Patents

Sodium vapour electric discharge lamps Download PDF

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Publication number
US2875358A
US2875358A US483961A US48396155A US2875358A US 2875358 A US2875358 A US 2875358A US 483961 A US483961 A US 483961A US 48396155 A US48396155 A US 48396155A US 2875358 A US2875358 A US 2875358A
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lamp
envelope
discharge
sleeve
discharge envelope
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Expired - Lifetime
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US483961A
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English (en)
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Rigden Sydney Alfred Richard
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General Electric Company PLC
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General Electric Company PLC
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J61/00—Gas-discharge or vapour-discharge lamps
    • H01J61/02—Details
    • H01J61/30—Vessels; Containers
    • H01J61/34—Double-wall vessels or containers

Definitions

  • the first of the above requirements calls for the use of a discharge envelope of relatively large diameter, but as the diameter of the envelope is increased, its wall temperature for a given wattage dissipation in the discharge, and with it the operating vapour pressure of the sodium, is reduced, and too wide an enveloperesults in too low a sodium vapour pressure for high efficiency; a compromise has, therefore, to be madenbetween these requirements, and in order to obtain the best compromise it is desirable to provide means for conserving the heat of the discharge envelope to ⁇ enable as wide a diameter envelope as possible to be used consistent with its wall temperature not falling to an undesirably low value.
  • the heat conserving means usually empolyed consists of a highly evacuated outer jacket into which envelope is fitted.
  • the form at present ⁇ morst commonly used consists of a double-walled hollow cylinder closed at one end and the space between the walls of which is sealed and highly evacuated.
  • the discharge tube usually in the shape of a letter U, is inserted into the jacket from Vthe open end, and the lamp is operated with air present in the space between ⁇ the discharge envelope and the inner wall ofthe outer jacket, the evacuated space between the inner and outer walls of the jacket, ⁇
  • Dewar jacket which is usuallyknown as a Dewar jacket, providing the necessary heat conservation.
  • the inner wall of the Dewar jacket serves as a screen for the absorption of l infra-red ⁇ radiation from the discharge envelope, which screen is protected by the evacuated space from the loss of heat tothe outer atmosphere and thus helps to keep up the temperature Aof ⁇ the discharge envelope; the screen infra-red radiation emitted by the latter.
  • a disadvantage introduced by this last feature is that the presence of moisture in this air under conditions of, high humidity, such as may be l ⁇ 'experienced by a lamp used for street-lighting, tends to the discharge render star-ting of the lamp difficult or unreliable; in addition it is diicult to tell when a Dewar jacket has failed, and repeated use of such jackets can readily leadV to use of a lamp with a poor Dewar jacket, but. despitethese disadvantages the ⁇ Dewar-jacketed ⁇ lamp has beeny accepted for many years as the best form of sodiurri lamp.
  • combinationj may be described as a Dewar jacket having the discharge envelope sealed therein and the interiorevacuated, has also been proposed, but such a combination is very expensive tovmake and is not much more etiicient than ⁇ either the single-wall jacketed lamp or Dewar jacketed lamp alone.
  • l 1 4 We have now found that by the use of a particular form of discharge envelope and heat-conserving sleeve arrangement in a single wall type of evacuated jacket,
  • a sodium vapour electric discharge lamp of the positive ⁇ column type has an elongated tubular discharge envelope of U-shape Vco ⁇ n- ⁇ taining electrodesfor the passage of anelectric discharge and a quantity of sodium for providing; a sodium vapour discharge in normal" operation of the lamp together with a iilling of rare gas for enabling the lamp to start" and the sodiumvapour discharge to be developed, ⁇ the ⁇ discharge envelope is sealed into a single-walled outer jacket with a highly evacuated space between the inner surface ofthe jacket and the outer surface of ⁇ the ⁇ discharge envelope, and ⁇ each limb of the discharge cnvelope is individually provided with a sleeveof transparent heat-insulating material which lits closely round the limb along the whole or ⁇ the greater part, of the length of the limb.
  • each said diameter is to be taken asethe maximum diameter Ain the .corresponding cross-section, that is to say, as the longest straight line which can :be drawn joining two points on the inner or v outer periphery, yas vthe case may be, of the cross-section.
  • each sleeve is only slightly greater, rfor example not more than two millimetres greater, than the external diameter of the limb on which it is tted; the sleeve may be a sliding fit on the limb but must not be in such intimate contact with it that the sleeve constitutes in effect ⁇ (as regards thickening of the wall of the Qnot -in any case be less .than that customarily used in the yevacuated Vouter jackets of known lamps of thekind rto-which this invention relates,.that is to say, the residual gas pressure must Inot be substantially higher than 10-3 millimetres of mercury.
  • yA vsuitably high degree of Vvacuum can beensured during manufacture of the lamp -fby vexhausting the ⁇ outer jacket to a high degree, preferably at least 4 vmillimetres mercury, and then dis persingagetter Within the jacket to clean up residual gas; the getter should not, of course, be so vdispersed as to obscure .any appreciable part of the outer jacket or dischargeenvelope'through which light is required to emerge in use'of'the lamp.
  • Theuse of a getter is also desirable for ensuring the maintenance of a high degree of vacuum within the outer jacket, in use of the lamp, by absorbing :.occludedpgas which :may beliberated from the walls of .the Vjacket and discharge envelope, or from other parts Within Vthe jacket, and a sucient excess of getter for absorbing such occluded-gas throughout 4the normal'life a lamp in ac- Con-dance with the invention are of transparent heatinsulating material means .that the material must be a good fabsorber 'or reflector fof infrared ⁇ radiation so as,
  • the term transparent means that the @sleeves must absorb little or vnone of the 1visible radiation from the discharge.
  • the wall thickness of the sleeves should, of course, Vbe such yas to .give a high infra-red In Vgeneral glass will be the most suitable and con- .-venient material ,for the sleeves,jbut other materials, for example quartz, which have similar properties and are Y otherwise suitablejfor use in lamps in accordance with the invention, andV in particular .are capable of with- -standing fthe heatdeveloped in, operation of the lamp .ing means vare not 'necessary for securing .the required
  • the sleeves may merely be slid onto the limbs and retained in position'without the use :of spacing means and without being coaxial with the limbs.
  • spacing means mayin some .cases be desirable for.preventing'rattling'of thesleeves on v.thedischarge envelope.
  • each sleeve may be attached to the limb on which it is fitted at one or more regions whose total axial length is small compared with the axial length of the said limb.
  • a sleeve is attached to the limb of the discharge envelope on which it is tted in this way, it should be attached .to it for only a relatively short axial distance, so that the area of contact between the limb and the sleeve will be small compared with the surface area ofthe discharge envelope andthe heat conserving eect of the sleeve will not be appreciably reduced.
  • each sleeve is attached to the limb at a single region only, and in such an arrangement the attachment of each sleeve to its respective limb is preferably elected at the free end of the corresponding limb of the discharge envelope.
  • each sleeve may be sealed to the pinch formed at the -end of the limb over which the sleeve is fitted, provided that the thermal expansion coefficient of the glass of the sleeve is simlar to that ofthe glass of the discharge envelope.
  • the sealing in of the electrode lead or leads and the sealing of a sleeve to the respective limb of the discharge envelope may conveniently be carried out in a single 0peration, the lead or leads, the discharge envelope and the sleeve being held in predetermined relative positions in which they are. to1 be sealed together, lfor, example rlimb are ysqueezed together, for example by a pair ,of
  • the sealing of the two sleeves to their respective limbs by this method may be eiectedsimultaneously if desired.
  • each sleeve is attached to a limb at more than one region,l the regions of attachment ⁇ should not'hermetically close the space 'between the limb and the sleeve bounded by these regions, in order to allow'said space to be'exhausted when th outer jacket is evacuated.
  • a further increase in efficiency may sometimes be obtained by providing one or more further sleeves of transparent heat-insulating material of the Vkind aforesaid oneach limb of the discharge envelope, each such further sleeve extending-along the whole or greater part of the length of -tne corresponding limb of the discharge envelope.
  • each such further sleeve tits closely round the sleeve which it immediately surrounds, that, is to say, the Yinternal diameter of each said further .sleeve 'is preferably not more than 50% greater than the external diameter of the sleeve whichV it immediately surrounds, the diameters being .taken in va cross-section atr right angles to ,the axes of Athesleeves, said diameters to be taken as the maXimllm diameters (ashereinbeforesaid) -in the :cross-section if Vthe, sleeves .are not of circular 'cross-section. 4Preferably said diameters differ by ⁇ only a few millmetres, for example not more than two millimetres. l i
  • the plurality of sleeves on each limb may be loosely tted, or they may be supported Vfrom each other and the discharge envelope by suitable spacers, or they may be attached together at one or more regions of small axial length, -for example with glass sleeves of suitable thermal expansion coeiicent they may all be sealed together and to the pinched end of the limb ofthe discharge envelope at the time of forming said pinch.
  • the elect of the sleeves in reducing the rate of loss of heat from the discharge envelope in a lamp in accordance with the invention may be utilised to increase the lamp etciency in two diterent ways; thus either the lamp may be arranged to operate at a higher sodium vapour ⁇ pressure than possible for the same current density with a lamp of similar construction not provided with the sleeve or sleeves, or the diameter ofthe discharge envelope in the lamp in accordance with the invention may be increased over that used in the unsleeved lamp to enable the former to attain the same vapour pressure at a lower current density than is possible with the latter.
  • the lamp shown therein comprises a substantially U-shaped discharge envelope 1 of glass, each limb 2 of which is approximately 32 centimetres long and has an internal diameter ⁇ of l5 millmetres, with a wall thickness of about 1.0 millimetre, the inner surface of the envelope being of sodium resistant glass.
  • the discharge envelope is iilledA with neon containing 0.5% by volume of argon at a total pressure of 10 millmetres of mercury, together with about 1 gramme of sodium.
  • the lamp electrodes 3, ⁇ which are of the kind ⁇ employed ⁇ in known kinds of sodium lamp, are mounted ⁇ near the ends of the discharge envelope so as to provide an arc length of ⁇ 600 millmetres.
  • the discharge envelope 1 is mounted within a cylindrical glass outer jacket 4, of approximately 50millimetres ⁇ outside diameter and wall thickness of about 1. ⁇ 5 millimetres, closed at one end by a dome-shaped end portion 5 and at the opposite end by a pinched foot-tube 6, the outer ends of the leads 7 to the lamp electrodes 3 being connected to two stout mounting wires 8 which are sealed ⁇ into the pinch 9 of the foot-tube forrsupporting the envelope in position within the jacket, the mounting wires connecting the leads 7 to two contact ⁇ terminals 10 of a bayonet ltype lamp cap 11 which isfsealed by means of a suitable cement to the end of the outer jacket.
  • the mounting wires ⁇ 8 themselves pass through holes ina circu lar mica disc 17 which is heldin position coaxially within the outer jacket 4 by means of an additional support wire 18 sealed into the pinch between the'mounting wires,
  • the mica disc serving to prevent lateral movement of the ⁇ mounting Wires ⁇ 8 and so holding the ends ofthe discharge envelope 1 in position within the outer jacket.
  • the curvedend of the U-shap'ed discharge envelope 1 is supportedcentrally within ⁇ the outer jacket 4 near to the domed end thereof by means of a length of Wire 12 which passes through a tubular glass bush 13 carriedbetween the limbs of the discharge envelope, a wire loop 14 which fits closely aroundthe two limbs, and which is spot welded to the wire on opposite sides of the discharge envelope, holding the envelope in position on the wire, and the two ends of the wire being spot welded to curved metal plates 15 arranged to bear against the inner surface of the outer jacket, thus supporting the envelope within the jacket.
  • a cylindrical glass sleeve 16 having an internal diameter of 18.0 ⁇ millmetres, which is approximately 1.0 millimetre larger than the external diameters of the limbs, the sleeves, which have a wall ⁇ thickness of about 0.5 to 0.75 millimetre, extending the whole length ofthe limb of the discharge envelope.
  • Axial movement of the sleeves 16 on the limbs of the discharge envelope is prevented by means of wire stops 8 spotwelded to the mounting wires 8, and bent so as to hold the sleeves against the wire loop 14 which surrounds the discharge envelope 1.
  • the space between the discharge envelope 1 and the Y outer jacket 4 is highly evacuated, and contains a getter element 19 attached to the support wire 18 for providing a coating of getter material on part of the wall of the outer jacket near to the pinched foot-tube 6, the getter material serving to absorb occuluded gas which may ⁇ be liberated from the glass walls surrounding the evacuated space during the ⁇ life of the lamp and so maintain the vacuum.
  • the mica disc 17 besides acting asa support for the lamp serves to prevent the evaporated getter material from spreading into the spacel between the'discharge envelope and outer jacket andmayalsoserve to reduce heat losses ⁇ t-o a certain extent by reilectingtback part of the ⁇ heat radiated from the discharge envelope 1 in the direction ofthe glass pinch9. As an aid to starting the.
  • the jacket For processing the lamp ⁇ partsfor the evacuation of the outer jacket, the following method was used.
  • the outer jacket was then evacuated to a pressure ofabout 10-4 millmetres Y hausted to a pressure of ⁇ about 10*4 millimtres of mercury, and then refilled witha ⁇ second quantity of dry .oxygen-free nitrogen at the same pressure as before, the
  • This lamp is intended to be operatediwithfla ⁇ nominal lone ou the wire;
  • each limb of the discharge envelope in a lamp substantially as described with ref- ,erence to Figures l and 2 could be provided, if desired, with 'a further glass sleeve litting closely over .the sleeve '16.
  • 'In one such lamp having a discharge envelope with -anrarc length of 400 millimetres and a tube bore of l5 millimetres, and arranged to operate at a current density o1.z approximately 0.34 amp.
  • the lamp shown .therein alsoV comprises a .U-shaped discharge envelope 1 mounted within a cylindrical glass louter jacket 4, the internal diameter of the discharge envelope being about .l5 yrnillirnetres and the length -of the limbs 2 of the envelope being such as to provide an arc length of 600 millimetres between the lamp electrodes 3; the envelope, which has a wall thickness of about one millimtre, hasV the'same gas and sodium metal i'illing as the lamp ⁇ described with reference to Figures ⁇ l .and 2.v
  • the curved end 23-of the discharge envelope l is supportedwithin the jacket 4 by means of a length of iwire 1 2. which passes through a tubular glass bush 13 .carriedbetween the limbs 2 of the envelope, as in the -glarnp shown in Figures l and 2, and two curved metal wire loop 14 which tits closely round the two limbs and spot welded to the wire 12 on opposite Vsides of the envelope prevents ,transverse movement of the enve- At the other end ofthe .lamp the outer jacket is closed by a pinched foot ,tube .G'having two mounting wires 8 sealed into the pinch and connected at their outer ends tothe terminals 10 of a bayonet type lamp cap 11 secured to :the jacket as vin Vthe lamp previously described.
  • the jacket are :bent back away from the discharge envelope 1 so as lto lie along the foot tube, and are connected to the respective electrode leads 7 by means of two nickel sleeves 20, one pair of leads 7 and the bent back end of the corresponding mounting wire 8 being inserted into .the same end of one of the sleeves and being secured in place vby spot welding.
  • a .sheet of mica 1 7 extends across the outer jacket with its ends in contact with the inner surface thereof aS an additional support for thedischarge envelope as in the lamp shown in Figures l and 2, although in this lamp the electrode leads 7 themselves extend through holes provided in the sheet', the connection to the mounting wires S taking place on the opposite side of the ⁇ sheet to the discharge envelope. s The space between the discharge envelope 1.
  • the outer vjacket 4 is exhausted and contains a getter Velement 19 welded to the end ofa support wire 1S which is sealed at its opposite end into the pinch of the foot tube 6 between ⁇ the two mounting wires 8, the end of the support wire 158 to which the getter element is attached beingpbent back in -a similar manner to the mounting wires S so as to lie along the foot tube 6.
  • each limb 2 of the discharge envelope 1 there is iittedover each limb 2 of the discharge envelope 1 a cylindrical transparentV glass sleeve 16 having an internal diameter of approximately 18 millimetres, which is of the order of 1.0 millimetre larger 'than the external diameter of the limbs, the sleeves, which have a wall thickness of about 0.5 to 0.75 millimetre, extending substantially the whole length of the limbs and being sealed to the limbs on which they are fitted, by the sealing of one end of each sleeve to the pinch 24 at the end of the limb into which the electrode leads '7 are sealed.
  • the sleeves 16 are thus supported ,coaxially on their respective limbs, and rattling or' the sleeves is thereby prevented.
  • the sealing of the sleeves to the limbs prevents relative axial movement between vthe sleeves and the limbs from taking place, thereby dispensing with the need for additional stops at the ends of the sleeves.
  • the sealing in of the electrode leads 7 at the ends of the discharge envelope 1 and the sealing of the sleeves 16 to the limbs 2 is conveniently elected in a singleV operation, the electrodesf, the discharge envelope l and-the the glass sleeves 16 in a similar manner to thelamp ,shown in Figures l and 2, and is intended to be operated at a nominal wattage dissipation of S5 watts and a current density of ⁇ about 0.35 amp. persquare centimetre. With ⁇ such a lamp operating under these conditions we have succeeded in obtaining ,an initial luminous efficiency of about lumens per watt.
  • the discharge enveloper of the lamp substantially as described by way of example with reference to Figures 3 and 4 of the drawings may be provided with one or more additional transparent heat- -insulating Sleeves if desired, kand .these additional sleeves can be ttedloosely over Ythesleeves 1 6, although in Some cases they may be attached to the sleeves 16 and to the discharge envelope 1.
  • a sodium vapour electric discharge lamp of the positive column type having an elongated tubular discharge envelope of U-shape containing electrodes for the passage of an electric discharge and a quantity of sodium for providing a sodium vapour discharge in normal operation of the lamp together with a tilling of rare gas for enabling the lamp to start and the sodium Vapour discharge to be developed, wherein the discharge envelope is sealed into a single-walled outer jacket with a highly evacuated space between the inner surface of the jacket and the outer surface of the discharge envelope, and wherein each limb of the discharge envelope is individually provided with a sleeve of transparent heat-insulating material which ts closely round the limb along at least the greater part of the length of the limb.
  • each sleeve is not more than two millimetres greater than the external diameter of the limb on which the sleeve is :tted.
  • a sodium vapour lamp according to claim 1 including a getter material within the outer jacket for absorbing residual gas within said highly evacuated space and maintaining a high degree of vacuum within said space during the life of the lamp.
  • a sodium vapour lamp according to claim 1 wherein the said sleeves are held on the limbs of the discharge envelope by means which restrain the sleeves against relative longitudinal displacement, but without the sleeves being attached to the limbs and without the interventlon of spacing means between the sleeves and the limbs.
  • each said sleeve is of glass.
  • each sleeve is attached to the limb on which it is ntted at at least one region 'ti/hose axial length is small compared with the axial length of said limb.
  • each sleeve is attached to the limb on which it is fitted at a single region only.
  • each limb of the discharge envelope is provided with at least one further transparent heat-insulating sleeve each of which ts closely over the sleeve which it immediately surrounds and extends along the whole or the greater part of the corresponding limb of the discharge envelope.

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  • Vessels And Coating Films For Discharge Lamps (AREA)
  • Discharge Lamps And Accessories Thereof (AREA)
US483961A 1954-01-27 1955-01-25 Sodium vapour electric discharge lamps Expired - Lifetime US2875358A (en)

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Application Number Priority Date Filing Date Title
GB2517/54A GB801482A (en) 1954-01-27 1954-01-27 Improvements in or relating to sodium vapour electric discharge lamps

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US (1) US2875358A (en(2012))
BE (1) BE535143A (en(2012))
DE (1) DE1132240B (en(2012))
FR (1) FR1118185A (en(2012))
GB (1) GB801482A (en(2012))
MY (1) MY5900012A (en(2012))
NL (1) NL88712C (en(2012))

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3054921A (en) * 1960-12-08 1962-09-18 Union Carbide Corp Electric lamp
US4441045A (en) * 1979-11-14 1984-04-03 U.S. Philips Corporation Low-pressure sodium vapor discharge lamp
US4600856A (en) * 1984-05-21 1986-07-15 Gte Products Corporation Compact low pressure arc discharge lamp
US4658177A (en) * 1984-07-13 1987-04-14 Patent-Treuhand Gesellschaft Fur Elektrische Gluhlampen Mbh Electric lamp with oriented current conductors extending through a press seal
US20070018579A1 (en) * 2003-05-16 2007-01-25 Koninklijke Philips Electronics N.V. Lamp and method of manufacturing a lamp
US20110148296A1 (en) * 2009-12-22 2011-06-23 Osram Gesellschaft Mit Beschraenkter Haftung High-pressure discharge lamp

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5043623A (en) * 1990-12-06 1991-08-27 Gte Products Corporation Reflector lamp assembly including metal halide arc tube

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2087745A (en) * 1935-09-23 1937-07-20 Gen Electric Lamp unit
US2120480A (en) * 1937-02-26 1938-06-14 Roy C Baker Insulating terminal for neon tubes
US2194300A (en) * 1937-09-24 1940-03-19 Gen Electric Vapor lamp and method of operation
US2228327A (en) * 1929-05-04 1941-01-14 Hans J Spanner Discharge device
US2392305A (en) * 1943-04-13 1946-01-08 Westinghouse Electric Corp High efficiency fluorescent lamp

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AT139286B (de) * 1933-06-27 1934-11-10 Patent Treuhand Ges Fuer Elektrische Gluehlampen Mbh Doppelwandige elektrische Leuchtröhre.
DE653077C (de) * 1936-04-17 1937-11-18 Patra Patent Treuhand Einsockelige elektrische Entladungsroehre, insbesondere Metalldampfentladungslampe
DE703012C (de) * 1938-02-18 1941-04-04 Saarbruecker Gluehlampenfabrik Gas- oder dampfgefuellte, von einem Vakuummantel umgebene Entladungslampe

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2228327A (en) * 1929-05-04 1941-01-14 Hans J Spanner Discharge device
US2087745A (en) * 1935-09-23 1937-07-20 Gen Electric Lamp unit
US2120480A (en) * 1937-02-26 1938-06-14 Roy C Baker Insulating terminal for neon tubes
US2194300A (en) * 1937-09-24 1940-03-19 Gen Electric Vapor lamp and method of operation
US2392305A (en) * 1943-04-13 1946-01-08 Westinghouse Electric Corp High efficiency fluorescent lamp

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3054921A (en) * 1960-12-08 1962-09-18 Union Carbide Corp Electric lamp
US4441045A (en) * 1979-11-14 1984-04-03 U.S. Philips Corporation Low-pressure sodium vapor discharge lamp
US4600856A (en) * 1984-05-21 1986-07-15 Gte Products Corporation Compact low pressure arc discharge lamp
US4658177A (en) * 1984-07-13 1987-04-14 Patent-Treuhand Gesellschaft Fur Elektrische Gluhlampen Mbh Electric lamp with oriented current conductors extending through a press seal
US20070018579A1 (en) * 2003-05-16 2007-01-25 Koninklijke Philips Electronics N.V. Lamp and method of manufacturing a lamp
US7372207B2 (en) 2003-05-16 2008-05-13 Koninklijke Philips Electronics, N.V. Lamp and method of manufacturing a lamp
US20110148296A1 (en) * 2009-12-22 2011-06-23 Osram Gesellschaft Mit Beschraenkter Haftung High-pressure discharge lamp

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FR1118185A (fr) 1956-06-01
GB801482A (en) 1958-09-17
DE1132240B (de) 1962-06-28
MY5900012A (en) 1959-12-31
BE535143A (en(2012))
NL88712C (en(2012))

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