EP0085487B1 - Lampes à décharge - Google Patents

Lampes à décharge Download PDF

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Publication number
EP0085487B1
EP0085487B1 EP83300141A EP83300141A EP0085487B1 EP 0085487 B1 EP0085487 B1 EP 0085487B1 EP 83300141 A EP83300141 A EP 83300141A EP 83300141 A EP83300141 A EP 83300141A EP 0085487 B1 EP0085487 B1 EP 0085487B1
Authority
EP
European Patent Office
Prior art keywords
torr
spark gap
lamp
discharge lamp
electrodes
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP83300141A
Other languages
German (de)
English (en)
Other versions
EP0085487A2 (fr
EP0085487A3 (en
Inventor
James Richard Coaton
Barry Preston
Kevin Hick
Frederick James Leyland Crammond
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Thorn EMI PLC
Original Assignee
Thorn EMI PLC
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Thorn EMI PLC filed Critical Thorn EMI PLC
Publication of EP0085487A2 publication Critical patent/EP0085487A2/fr
Publication of EP0085487A3 publication Critical patent/EP0085487A3/en
Application granted granted Critical
Publication of EP0085487B1 publication Critical patent/EP0085487B1/fr
Expired legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J61/00—Gas-discharge or vapour-discharge lamps
    • H01J61/02—Details
    • H01J61/54—Igniting arrangements, e.g. promoting ionisation for starting
    • H01J61/547—Igniting arrangements, e.g. promoting ionisation for starting using an auxiliary electrode outside the vessel

Definitions

  • This invention relates to metal halide lamps and more particularly but not exclusively to high pressure sodium lamps using ceramic arc tubes and to the problems of starting such lamps.
  • the arc tubes of high pressure sodium vapour lamps usually contain an inert gas, typically xenon, in addition to the sodium, mercury and occasionally other additives such as cadmium.
  • the inert gas facilitates starting and during operation also acts as a buffer gas together with the mercury vapour.
  • Lamp starting is usually achieved by applying a voltage pulse higher than mains voltage or a train of such pulses across the arc tube and with a xenon filling pressure of between 1.33 kPa (10 torr) to 6.65 kPa (50 torr) at 300K a voltage pulse of the order 1.5 to 5kV usually suffices to start the lamp.
  • a voltage pulse of this order is within the requirements to avoid arcing between lamp components such as the cap and holders and satisfies the requirements for creepage and clearance distances and also gives satisfactory lamp performance for life and efficacy characteristics.
  • Xenon pressure would give further increases in efficacy, for example, if the xenon pressure is increased to within the range from 6.65kPa (50 torr) to 133kPa (1000 torr) at 300K the luminous efficacy would be increased, according to UK Patent No. 1,587,987, by about 15%.
  • a starting aid can comprise an auxiliary electrode in the form of a strip or spiral extending along or looped around the arc tube envelope.
  • a variety of starting aids are available but all have some shortcomings either in terms of cost or complexity or effectiveness. For example, to be effective, the strip or spiral mentioned above must be directly connected to one main electrode of the arc tube but if so connected it leads to sodium loss due to electrolysis through the arc tube wall and hence premature lamp failure.
  • GB-A-804,319 describes an electric flash discharge tube which includes an arc discharge tube having a pair of discharge electrodes and a trigger electrode assembly comprising a conductor, wound spirally around the arc tube and cooperating with the discharge electrodes, and a spark gap defined by two further electrodes.
  • One of the further electrodes is connected to the conductor of the trigger electrode assembly and the other further electrode is coupled through a multi vibrator circuit to one of the discharge electrodes so as to provide a series of pulses to the discharge tube causing the tube to flash.
  • GB-1,493,270 describes a discharge lamp including an arc tube having a pair of discharge electrodes and an auxiliary starting conductor connected to an inlead for one of the discharge electrodes by means of a coupling element.
  • the coupling element comprises a pair of further electrodes which are spaced apart from one another and acts as a capacitive coupling between the inlead and the auxiliary starting conductor.
  • An object of this invention is to provide a starting arrangement for a discharge lamp substantially free from such drawbacks, and if not free, certainly improved upon the performance of the prior art arrangements described above.
  • a discharge lamp having an arc discharge tube including first electrodes for supporting a discharge therebetween, inleads connected to said first electrodes, a starting aid including a conductor co-operating with the first electrodes and a spark gap element connected between the conductor and one of said inleads, said spark gap element comprising an envelope of insulating material defining a container enclosing a fill of gas or being evacuated and two further electrodes connected respectively with the conductor and said one inlead and being hermetically sealed to and projecting within the envelope to define a spark gap between the two further electrodes, the spark gap element being adapted to electrically isolate the lamp during normal running of the lamp and breakdown under high voltage pulses applied to start the lamp and being shielded from photo emission taking place between the first electrodes when the lamp is running.
  • the spark gap according to the invention provides a much simpler and less complex solution to a problem which has been present in the art for many years. It provides, for example:
  • Insulating material used in the construction of the spark gap should have high electrical resistivity of the order 10 6 0 hms cms at 650 K which is thought to be suitable for most lamp applications.
  • Aluminosilicate and borosilicate glasses come into this category. Of course other materials with higher resistivity, for example ceramic could be suitable.
  • Soda lime silicate glass which has lower resistivity of 10 5 ohm cms at 650 K could also be suitable depending on lamp duty. It is advantageous to have the co-efficient of expansion of the insulating material compatible with the co-efficient of expansion of the material of the conductors. The nearer these properties are to being the same the less tendency there is for cracking of seals to occur.
  • spark gap should be designed so that it will not breakdown below about 2 x mains voltage but should breakdown below about 1 x the applied starting voltage pulse.
  • the spark gap can be designed to meet a variety of conditions. It will also be clear to those skilled in the art that while the following description is in terms of a high pressure sodium vapour lamp the spark gap can be used in a variety of lamps requiring starting aids and ignitors or the like.
  • the lamp of the invention should include a small amount of argon or neon or a mixture thereof which we have found to aid starting with little influence on luminous efficacy.
  • a high pressure sodium vapour discharge lamp 10 according to one embodiment of the invention is shown in Figure 1.
  • This comprises an outer envelope 11 of borosilicate glass fitted to an Edison screw end portion 12 forming the base of the lamp 10.
  • the envelope 11 contains a ceramic arc discharge tube 13 suspended from a cross part 14 attached at one side 15 and, by means of an overhanging portion 16 to the other side 17 of a substantially rigid electrically conductive support rod 18.
  • the support rod 18 is welded to a main electrical inlead 19 projecting through a borosilicate glass stem 20. Spring-like brackets attached to the support rod 18 ensure the arc tube is properly centred within the lamp envelope.
  • the cross piece 14 is attached to a niobium tube 21 hermetically sealed to the discharge arc tube 13 and the tube 21 in turn is connected to discharge electrode 22 thus forming one main electrical inlead for the arc tube.
  • a second niobium tube 23 which is a sliding fit on a support wire 25 welded to a substantially rigid electrically conductive rod 26 projecting through the borosilicate glass stem 20.
  • a flexible conductive foil 27 is attached to the niobium tube 23 and the substantially rigid rod 26 and this arrangement thus forms a second main electrical inlead to the discharge electrode 24. This arrangement allows for movements of the components due to temperature expansion effects.
  • niobium tube end closure arrangement which is shown in greater detail in Figure 2 is but one of several possible arrangements and the particular arrangement of end closure chosen is not critical to the invention.
  • the niobium tube 23 is hermetically sealed within an alumina plug 28, which in turn is hermetically attached by means of a suitable sealing composition 29 within the discharge tube 13.
  • the niobium tube 23 carries a shank 30 supporting the discharge electrode 24.
  • the arc tube of the above lamp can have a gas filling comprising a mixture of 90 to 98% xenon, with the balance of 2-10% being argon, neon or a combination of both filled to a total pressure of between 6.65kPa (50 torr) and 133kPa (1000 torr) at 300K.
  • the argon and or neon gives some improvement in starting, with little influence on luminous efficacy.
  • the arc tube contains charges of sodium and mercury which during lamp operation will produce a partial pressure of sodium of 5.32kPa (40 torr) to 53.2kPa (400 torr) and a partial pressure of mercury of 5.32kPa (40 torr) to 186kPa (1400 torr).
  • the outer glass envelope of the lamp 10 is usually evacuated to minimise losses but in some cases may be gas filled with a non-reactive gas or mixture.
  • a means of gettering, for example ring 36, is included in the outer envelope to clear up impurities such as hydrogen
  • a spark gap generally indicated at 38 is provided.
  • One end 39 of the spark gap is connected to the inlead 26 while the other end 40 is connected to a conductive wire 41.
  • This wire 41 loops around the arc tube as shown an cooperates with the discharge electrodes 22 and 24 to facilitate the starting of the lamp.
  • the end of the wire 41 remote from the spark gap 38 is anchored within an insulating member 42 attached to the rod 18.
  • the insulating member 42 is a solid piece of borosilicate glass with the conductive wire 41 embedded therein.
  • FIG 3 a linear version is shown comprising a length of aluminosilicate glass forming an elongate envelope 43 defining a container sealed at each end 44 and 45 around co-axial conductors 46 and 47 thereby hermetically sealing the conductors 46 and 47 within the envelope 43.
  • the envelope 43 can be evacuated or enclose a fill of air or one or more gas species the pressure of which, together with the spark gap, may be used to control the breakdown voltage.
  • a spark gap as shown in figure 3 typically could be 14 mm in overall length with an outside diameter of 3 mm.
  • the conductors 46 and 47 could be molybdenum wire 0.3 mm in diameter and with a gap between the conductors of between 1 to 1 mm.
  • the conductors 46 and 47 can be joined to stainless steel wires 48 and 49 approximately 0.7 mm in diameter which assists in the mounting and assembly procedure.
  • a spark gap as described contains a fill of argon at a pressure between 9.98kPa (75 torr) and 33.25kPa (250 torr) and would be arranged to break down between 1,000 and 3,000 volts.
  • a different version of spark gap is shown in figure 4. This comprises a bulbous envelope portion 50 also defining a container having one end 51 pinch sealed around spaced parallel conductors 52 and 53 thereby hermetically sealing the conductors within the envelope 50.
  • the envelope in this case is of alumino silicate glass, approximately 8 mm in diameter and about 8mm long.
  • the conductors are as before, molybdenum wire approximately 0.3 mm in diameter which are joined to 0.7 mm diameter stainless steel wires 54 and 55.
  • the gap between the conductors is between 1/2 to 1mm, the bulb is filled with argon, in the range 9.98kPA (75 torr) to 33.25kPa (250 torr). Breakdown is arranged to occur in the range 500 to 2000 volts.
  • spark gap 38 In operation we have found that if the spark gap is positioned such that it is directly exposed to the light from the arc tube some photo electric emission can take place between the electrodes. In one test we found a current of the order of 7 micro amps existed. We find, however, that we can prevent this by providing suitable shielding, for example by providing screens around the spark gap, or by locating the spark gap in an area not exposed to the light. Another alternative is to provide the spark gap 38 with a suitable non-conducting covering of opaque material 56 and 57 as shown in figures 3 and 4 (much exaggerated for purposes of illustration) respectively. Such a covering could be, for example, zirconia.
  • a lamp incorporating the spark gap of the invention will be placed in circuit with a suitable igniter which will provide high voltage pulses of the order 1.5 to 5 KV.
  • the spark gap provided will be arranged to break down under these high voltage pulses and will then be able to pass current to the wire conductor 41 to facilitate the starting of lamp.
  • no current will pass across the spark gap and hence no sodium loss will be incurred through leakage current circulating in the conductor 41 drawing out sodium ions through the arc tube. No resetting of component parts is required and it will be evident from the description that the design of spark gap is extremely simple and economical.
  • the spark gap may be used with any discharge lamp in which the ignition phase is preceeded by the application of a high voltage pulse.
  • the ignition phase is preceeded by the application of a high voltage pulse.

Landscapes

  • Discharge Lamps And Accessories Thereof (AREA)
  • Vessels And Coating Films For Discharge Lamps (AREA)

Claims (8)

1. Une lampe à décharge (10) comprenant un tube à arc à décharge (13) comportant des premières électrodes (22, 24) pour entretenir entre elles une décharge, des éléments d'alimentation électrique (19, 26) reliés auxdites premières électrodes (22, 24), un auxiliaire d'amorçage comprenant un conducteur (41) coopérant avec les premières électrodes (22, 24) et un élément formant éclateur (38) connecté entre le conducteur (41) et un (26) desdits éléments d'alimentation électrique, ledit élément formant éclateur (38) comprenant une enveloppe (43; 50) en matière isolante définissant un récipient renfermant un remplissage de gaz ou mis sous vide et deux électrodes additionnelles (46, 47; 52, 53) reliées respectivement au conducteur (41) et audit premier élément d'alimentation électrique (26) et hermétiquement scellées sur et faisant saillie à l'intérieur de l'enveloppe (43; 50) pour définir un éclateur entre les deux autres électrodes (46, 47; 52, 53), l'elément formant éclateur (38) étant adapté pour isoler électriquement la lampe (10) pendant son fonctionnement normal et pour claquer sous l'effet d'impulsions de haute tension appliquées pour l'amorçage de la lampe (10), et étant protégé (56; 57) contre une photo-émission se produisant entre les premières électrodes (22, 24) quand la lampe est en marche.
2. Une lampe à décharge selon la revendication 1, dans laquelle ladite enveloppe (43; 50) contient un remplissage d'air.
3. Une lampe à décharge selon la revendication 1, dans laquelle ladite enveloppe (43; 50) contient un gaz rare.
4. Une lampe à décharge selon la revendication 3, dans laquelle ledit gaz rare est de l'argon sous une pression rentrant dans la plage comprise entre 5,32 kPa (40 torrs) et 53,3 kPa (400 torrs).
5. Une lampe à décharge selon la revendication 1, dans laquelle l'élément formant éclateur est protégé par une matière opaque non conductrice (56; 57) recouvrant ladite enveloppe (43; 50).
6. Une lampe à décharge selon la revendication 5, dans laquelle ladite matière opaque non conductrice est de l'oxyde de zirconium.
7. Une lampe à décharge selon une quelconque des revendications 1 à 6 se présentant sous la forme d'une lampe à décharge à vapeur de sodium à haute pression, dans laquelle ledit tube à arc contient un remplissage se composant de 90 à 98 % de xenon, le complément étant choisi pour être formé d'argon et de néon séparément ou en combinaison, et le remplissage résultant de gaz étant effectué à une pression totale rentrant dans la plage comprise entre 6,65 kPa (50 torrs) et 133 kPa (1000 torrs) à 300°K.
8. Une lampe à décharge selon la revendication 7, dans laquelle le tube à arc à décharge contient un remplissage choisi à partir:
d'argon à une pression de 9,98 kPa (75 torrs) à 33,25kPa (250 torrs);
de xénon à une pression de 6,65 kPa (50 torrs) à 133 kPa (1000 torrs);
de sodium dont la pression partielle est comprise entre 5,32 kPa (40 torrs) et 53,2 kPa (400 torrs) pendant le fonctionnement de la lampe;
de mercure dont la pression partielle est comprise entre 5,32 kPa (40 torrs) à 186 kPa (1400 torrs) pendant le fonctionnement de la lampe.
EP83300141A 1982-01-29 1983-01-12 Lampes à décharge Expired EP0085487B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB8202526 1982-01-29
GB8202526 1982-01-29

Publications (3)

Publication Number Publication Date
EP0085487A2 EP0085487A2 (fr) 1983-08-10
EP0085487A3 EP0085487A3 (en) 1983-08-17
EP0085487B1 true EP0085487B1 (fr) 1988-11-09

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ID=10527958

Family Applications (1)

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EP83300141A Expired EP0085487B1 (fr) 1982-01-29 1983-01-12 Lampes à décharge

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Country Link
EP (1) EP0085487B1 (fr)
AU (1) AU563791B2 (fr)
DE (1) DE3378445D1 (fr)
ZA (1) ZA83585B (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102010029068A1 (de) * 2010-05-18 2011-11-24 Osram Gesellschaft mit beschränkter Haftung Verfahren zum Herstellen einer Hochspannungsschaltfunkenstrecke

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4491766A (en) * 1982-06-24 1985-01-01 North American Philips Lighting Corporation High pressure electric discharge lamp employing a metal spiral with positive potential
GB8330774D0 (en) * 1983-11-18 1983-12-29 Emi Plc Thorn Sealed beam lamps
DE9013279U1 (de) * 1990-09-19 1990-11-22 Patent-Treuhand-Gesellschaft für elektrische Glühlampen mbH, 81543 München Einseitig gesockelte Hochdruck-Entladungslampe
JP3208087B2 (ja) * 1997-04-18 2001-09-10 松下電器産業株式会社 メタルハライドランプ

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB804319A (en) * 1954-06-04 1958-11-12 Siemens Edison Swan Ltd Improvements relating to electronic flash discharge tubes
JPS5718301B2 (fr) * 1973-12-28 1982-04-15
US4179640A (en) * 1977-12-05 1979-12-18 Westinghouse Electric Corp. Hid sodium lamp which incorporates a high pressure of xenon and a trigger starting electrode

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102010029068A1 (de) * 2010-05-18 2011-11-24 Osram Gesellschaft mit beschränkter Haftung Verfahren zum Herstellen einer Hochspannungsschaltfunkenstrecke

Also Published As

Publication number Publication date
EP0085487A2 (fr) 1983-08-10
AU563791B2 (en) 1987-07-23
ZA83585B (en) 1983-11-30
EP0085487A3 (en) 1983-08-17
AU1055383A (en) 1983-08-04
DE3378445D1 (en) 1988-12-15

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