EP0002848B1 - Electrical high-pressure metal vapour discharge lamp - Google Patents

Electrical high-pressure metal vapour discharge lamp Download PDF

Info

Publication number
EP0002848B1
EP0002848B1 EP19780200339 EP78200339A EP0002848B1 EP 0002848 B1 EP0002848 B1 EP 0002848B1 EP 19780200339 EP19780200339 EP 19780200339 EP 78200339 A EP78200339 A EP 78200339A EP 0002848 B1 EP0002848 B1 EP 0002848B1
Authority
EP
European Patent Office
Prior art keywords
strip
discharge tube
shaped coating
lamp
discharge lamp
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
EP19780200339
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0002848A1 (en
Inventor
Cornelis Adrianus Joannes Jacobs
Johannes Van Esdonk
Josephus Maria Ruts
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.)
Koninklijke Philips NV
Original Assignee
Philips Gloeilampenfabrieken NV
Koninklijke Philips Electronics NV
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 Philips Gloeilampenfabrieken NV, Koninklijke Philips Electronics NV filed Critical Philips Gloeilampenfabrieken NV
Publication of EP0002848A1 publication Critical patent/EP0002848A1/en
Application granted granted Critical
Publication of EP0002848B1 publication Critical patent/EP0002848B1/en
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
    • H01J61/541—Igniting arrangements, e.g. promoting ionisation for starting using a bimetal switch
    • H01J61/544—Igniting arrangements, e.g. promoting ionisation for starting using a bimetal switch and an auxiliary electrode outside the vessel

Definitions

  • the invention relates to an electrical high-pressure metal vapour discharge lamp comprising an elongate discharge tube provided near each of its two ends with a respective internal main electrode, the wall of the discharge tube consisting substantially wholly of aluminium oxide, a strip-shaped coating being present over at least a portion of the outer surface of the wall of the discharge tube, this coating containing a first electrically conductive elementary material as well as a second material counteracting evaporation of the first material, and in which at least part of the first material is in direct contact with the aluminium oxide, the strip-shaped coating being fastened over substantially its whole length to the discharge tube and forming in use, part of a starting auxiliary device for starting a discharge between the main electrodes.
  • a prior art electrical high-pressure metal vapour discharge lamp of the type defined above is, for example, disclosed in Dutch Patent Application no. 7304860.
  • a drawback of that known high-pressure metal vapour discharge lamp is that, for promoting the starting of a discharge between the main electrodes, the strip-shaped wall coating is connected to an internal auxiliary electrode of the discharge tube. This requires an additional electric feed-through through the wall of the discharge tube.
  • An electrical high-pressure metal vapour discharge lamp is characterized in that the strip-shaped coating extends along substantially the whole path between the main electrodes, and in that this strip-shaped coating has a width smaller than 0.5 mm over at least 90% of its length and the first material of the strip-shaped coating consists for 16 to 90% by volume of an element from the group molybdenum, tungsten, tantalum, niobium and carbon, and the second material of the strip-shaped coating consists of one or more oxides which, at a temperature of 1500 Kelvin, have vapour pressure below 1.3 10- 4 Pa.
  • the narrow width, over the greater portion of the length of this auxiliary electrode implies that the auxiliary electrode intercepts the light generated in the discharge tube to a very small extent only.
  • This invention has furthermore the advantage that more of the first material can be included in the strip-shaped coating than would be possible in the case of a solid strip on the discharge tube. In addition, it is a good electrically-conducting material. The following should be noted by way of explanation. With the narrow width of not more than 0.5 mm of the strip-shaped coating, a sufficient low ohmic resistance thereof per running centimeter of length can - in the case of a solid metal - only be realized with a fairly thick layer of that metal.
  • the strip-shaped coating may have a width exceeding 0.5 mm for a short length, for example, where there is a connecting terminal for electrically connecting the strip-shaped coating to the circuit of the lamp.
  • a discharge lamp provided with a strip-shaped coating on the outside of the discharge tube, which extends along the whole path between the main electrodes, is known in itself from USP 2.542.345.
  • the width of the coating of this known lamp is about 1 mm.
  • the known lamp is a low pressure metal vapour discharge lamp of which the wall of the discharge tube is made of glass and will have a temperature during operation that does not exceed 100°C (375 K).
  • the strip-shaped coating consists of a solid metal conductor covered by a second material suitable for adherence to the discharge tube. This implies that the electrically conduction material is not in direct contact with the discharge tube.
  • An advantage of a direct contact of the electrically conductive material of the auxiliary electrode with the wall of the discharge tube is that, compared with the above prior art lamp, it gives a more reliable ignition of the discharge in the discharge tube.
  • the first material of the strip-shaped coating is molybdenum or carbon, this first material being uniformly distributed in the second material of the strip-shaped coating.
  • the strip-shaped coating consists, by volume, of approximately 80% Molybdenum + 10% A1 2 0 3 + 10% CaO.
  • the discharge lamp is, for example, a high-pressure sodium vapour discharge lamp the discharge tube of which also contains a starting gas, for example xenon, at a filling pressure of less than 2.7 kPa.
  • the discharge tube contains sodium and xenon, the filling pressure of the xenon exceeding 6.7 kPa, the circumference of a transverse cross-section through the discharge tube being between 10 and 40 mm.
  • a high-pressure discharge lamp according to the invention may comprise a discharge tube, the strip-shaped coating of which is not electrically connected to the lamp circuit.
  • the strip-shaped coating has a floating potential in use, preferably, however, in a high-pressure metal vapour discharge lamp according to the invention, the strip-shaped coating is electrically connected to one of the main electrodes of the discharge tube.
  • reference numeral 1 denotes a discharge tube whose wall consists mainly of densely sintered aluminium oxide. This tube is located in an outer bulb 2.
  • Reference numeral 3 denotes a base of the lamp.
  • the discharge tube 1 comprises two internal main electrodes 4 and 5, respectively, located near the ends of this discharge tube.
  • the main electrode 4 Via a feed-through 6 the main electrode 4 is connected to a metal conductor 7 connected to a pole wire 8 which is curved around the discharge tube 1.
  • This form of the pole wire 8 has the advantage that annoying shadows are avoided.
  • Pole wire 8 is electrically connected to a contact of the base 3 of the lamp.
  • An extended portion 9 of the pole wire 8 serves, together with a support 10, for supporting and centring the discharge tube 1 in the outer bulb 2.
  • Via a tubular feed-through 11 the main electrode 5 is mechanically fastened to a metal conductor 12. The electrical connection is effected via a metal conductor 13. The other end of the conductor 12 is connected to a further contact in the base
  • the discharge tube is provided with a strip-shaped external auxiliary electrode 20 in the form of a local -ciating on the outer surface of the discharge tube 1.
  • the auxiliary electrode 20 extends over substantially the whole distance between the main electrodes 4 and 5.
  • the auxiliary electrode is approximately 0.2 mm wide, its composition by volume is: a mixture of 80% Molybdenum, 10% AI 2 0 3 and 10% CaO.
  • the two mentioned oxides AI 2 0 3 and CaO have, at a temperature of 1500 Kelvin, a vapour pressure below 1.3 10- 4 Pa.
  • the discharge tube 1 comprises a conducting nickel sleeve 21 which also extends over the auxiliary electrode 20 and is in electrical contact therewith.
  • the other electrode of capacitor 23 is constituted by a portion of the metal conductor 13 which provides the electrical connection between the main electrode 5 and the conductor 12.
  • the discharge tube 1 contains both sodium and mercury as well as xenon.
  • the xenon pressure at 300 Kelvin is approximately 27 kPa.
  • the space between the discharge tube 1 and the outer bulb 2 is evacuated.
  • the described lamp is, for example ignited by means of a starter (not shown) provided with a thyristor, for example as disclosed in Dutch Patent Application no. 6904456.
  • the lamp In the operating condition of the lamp shown in Figure 1 the lamp is connected through an inductive stabilisation impedance of approximately 0.3 Henry to an a.c. mains supply of approximately 220 Volts, 50 Hertz. Further details of the described lamp are included in the following table.
  • the temperature of the coldest spot in the discharge tube 1 is - in the operating condition of the lamp according to the invention - approximately 1000 Kelvin.
  • a sodium vapour pressure in the discharge tube 1 of approximately 17 kPa corresponds therewith.
  • the average temperature within the discharge tube 1 in the operating condition of the lamp is approximately 2400 Kelvin.
  • the average temperature of the wall of the discharge tube is approximately 1500 Kelvin. At this temperature of 1500 Kelvin the vapour pressure of the oxides of the strip-shaped auxiliary electrode is - as already mentioned above - small. So there is only a low degree of evaporation of said oxides.
  • the voltage required between the main electrodes 4 and 5 for starting the discharge is in the present case approximately 2 kVolts.
  • the strip-shaped coating 20 of Figure 1 is approximately 35 microns thick. Its ohmic resistance per running centimetre is approximately 0.1 kOhm.
  • the strip-shaped coating 20 is applied to the wall of the discharge tube by means of a pen.
  • this pen is first dipped into a suspension of 8096 molybdenum powder with 10% aluminium oxide and 10% calcium oxide in butyl acetate.
  • a firing operation is performed at 1600 Kelvin for 30 minutes in a reducing atmosphere. This results in a proper adhesion to the wall of the discharge tube 1 over the full length of the strip-shaped coating 20.
  • that strip-shaped coating can, for example, also be applied to the discharge tube by means of a pen.
  • Figure 2 shows a perpendicular cross-section 100 of a second discharge tube, enlarged three times relative to that of the discharge tube 1 of Figure 1.
  • tube 100 consists mainly of aluminium oxide.
  • a strip-shaped molybdenum coating 101 is provided on tube 100.
  • a tungsten top coating 102 is applied over coating 101.
  • the full width of the strip is approximately 0.2 mm. To indicate the various layers, the strip is not drawn to scale in Figure 2.
  • An advantage of the described strip-shaped coatings in a lamp according to the invention - as opposed to starting wires - is that the strip-shaped coatings are always very close to the main electrode path without requiring an additional measure such as subjecting it to a tensile load - as is the case with starting wires.

Landscapes

  • Discharge Lamps And Accessories Thereof (AREA)
  • Vessels And Coating Films For Discharge Lamps (AREA)
EP19780200339 1977-12-16 1978-12-04 Electrical high-pressure metal vapour discharge lamp Expired EP0002848B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
NL7713950A NL7713950A (nl) 1977-12-16 1977-12-16 Elektrische hogedrukmetaaldampontladingslamp.
NL7713950 1977-12-16

Publications (2)

Publication Number Publication Date
EP0002848A1 EP0002848A1 (en) 1979-07-11
EP0002848B1 true EP0002848B1 (en) 1981-08-05

Family

ID=19829774

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19780200339 Expired EP0002848B1 (en) 1977-12-16 1978-12-04 Electrical high-pressure metal vapour discharge lamp

Country Status (6)

Country Link
EP (1) EP0002848B1 (ja)
JP (2) JPS5488676A (ja)
CA (1) CA1116684A (ja)
DE (1) DE2860920D1 (ja)
HU (1) HU180274B (ja)
NL (1) NL7713950A (ja)

Families Citing this family (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA1167973A (en) * 1980-10-02 1984-05-22 Joseph M. Proud Low energy starting aid for high intensity discharge lamps
DE69323026T2 (de) * 1992-10-08 1999-07-01 Koninklijke Philips Electronics N.V., Eindhoven Hochdruckentladungslampe
DE19631188A1 (de) * 1996-08-02 1998-02-05 Heraeus Kulzer Gmbh Entladungslampenanordnung
US6628079B2 (en) 2000-04-26 2003-09-30 Cornell Research Foundation, Inc. Lamp utilizing fiber for enhanced starting field
US6456005B1 (en) * 2000-10-31 2002-09-24 General Electric Company Materials and methods for application of conducting members on arc tubes
US6563265B1 (en) * 2000-11-06 2003-05-13 General Electric Company Applying prealloyed powders as conducting members to arc tubes
US6897615B2 (en) 2001-11-01 2005-05-24 Axcelis Technologies, Inc. Plasma process and apparatus
WO2005027184A2 (en) * 2003-09-17 2005-03-24 Koninklijke Philips Electronics N.V. Gas discharge lamp
WO2009030265A1 (de) * 2007-08-29 2009-03-12 Osram Gesellschaft mit beschränkter Haftung Lampe mit direkt aufgebrachter zündhilfsvorrichtung
JP5578526B2 (ja) 2008-07-10 2014-08-27 コーニンクレッカ フィリップス エヌ ヴェ ハイブリッドアンテナを備えた高圧ナトリウム放電ランプ
JP6650456B2 (ja) 2014-12-12 2020-02-19 ルミレッズ ホールディング ベーフェー 車両ヘッドライト用のガス放電ランプ

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2542345A (en) * 1948-08-16 1951-02-20 Gen Electric Electric discharge lamp
DE1764866A1 (de) * 1968-08-21 1971-11-18 Patra Patent Treuhand Anordnung zur Wiederzuendung einer betriebswarmen Quecksilberdampf-Hochdruckentladungslampe mit Zusaetzen
US4065370A (en) * 1975-11-18 1977-12-27 The United States Of America As Represented By The Secretary Of The Army Method of ion plating a thin metallic strip for flashlamp starting
US4047064A (en) * 1976-06-16 1977-09-06 Gte Sylvania Incorporated Flash tube having enclosed trigger wire

Also Published As

Publication number Publication date
HU180274B (en) 1983-02-28
DE2860920D1 (en) 1981-11-05
CA1116684A (en) 1982-01-19
JPS5488676A (en) 1979-07-13
EP0002848A1 (en) 1979-07-11
NL7713950A (nl) 1979-06-19
JPS58165849U (ja) 1983-11-04

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