EP1104933A2 - Lampe à décharge à gaz à électrode pourvu d'un émetteur à oxyde - Google Patents

Lampe à décharge à gaz à électrode pourvu d'un émetteur à oxyde Download PDF

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Publication number
EP1104933A2
EP1104933A2 EP00204147A EP00204147A EP1104933A2 EP 1104933 A2 EP1104933 A2 EP 1104933A2 EP 00204147 A EP00204147 A EP 00204147A EP 00204147 A EP00204147 A EP 00204147A EP 1104933 A2 EP1104933 A2 EP 1104933A2
Authority
EP
European Patent Office
Prior art keywords
oxide
group
gas discharge
discharge lamp
coating
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.)
Withdrawn
Application number
EP00204147A
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German (de)
English (en)
Other versions
EP1104933A3 (fr
Inventor
Georg Dr. Philips Corp. Intel.Prop.GmbH Gärtner
Willem Jacobus Dr. Van Den Hoek
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.)
Philips Intellectual Property and Standards GmbH
Koninklijke Philips NV
Original Assignee
Philips Intellectual Property and Standards GmbH
Philips Corporate Intellectual Property GmbH
Koninklijke Philips Electronics NV
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Filing date
Publication date
Application filed by Philips Intellectual Property and Standards GmbH, Philips Corporate Intellectual Property GmbH, Koninklijke Philips Electronics NV filed Critical Philips Intellectual Property and Standards GmbH
Publication of EP1104933A2 publication Critical patent/EP1104933A2/fr
Publication of EP1104933A3 publication Critical patent/EP1104933A3/fr
Withdrawn legal-status Critical Current

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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
    • H01J61/04—Electrodes; Screens; Shields
    • H01J61/06—Main electrodes
    • H01J61/067—Main electrodes for low-pressure discharge lamps
    • H01J61/0675—Main electrodes for low-pressure discharge lamps characterised by the material of the electrode

Definitions

  • the invention relates to a gas discharge lamp, in particular a low-pressure gas discharge lamp, equipped with an electrode that consists of a support and a coating an electron emitting material which is an alkaline earth metal oxide selected from the Group calcium oxide, strontium oxide and barium oxide, and an oxide of a rare earth metal contains, includes.
  • the generation of light in a gas discharge lamp is based on the ionization and the resulting one electrical discharge of the atoms of the filling gas of the lamp when an electrical Electricity flows through the lamp. Electrons become from the electrodes of the lamp emitted and accelerated so strongly by the electric field between the electrodes, that when they collide with the gas atoms, they can excite and ionize them. When the gas atoms return to their basic state and when recombining Electrons and ions become a more or less large part of the potential energy in Radiation converted.
  • the amount of electrons that can be emitted by the electrodes depends on the work function of the electrodes for electrons.
  • Tungsten in the Usually used as an electrode metal has a relatively high work function. Therefore the electrode metal is usually coated with a material whose task it is to improve the electron-emitting properties of the electrode metal.
  • Characteristic of the electron-emitting coating materials of electrodes It is in gas discharge lamps that they contain an alkaline earth metal, either in the Form of the alkaline earth metal oxide or an alkaline earth metal-containing starting compound (precursor) for the alkaline earth metal oxide.
  • Low-pressure gas discharge lamps of a conventional type are therefore usually with electrodes equipped with tungsten wires with an electron-emitting coating, contains the oxides of the alkaline earth metals calcium, strontium and barium.
  • a tungsten wire is used, for example, with the Carbonates of the alkaline earth metals coated in a binder preparation. While pumping and baking the lamp, the carbonates at temperatures of about 1000 ° C converted into the oxides. After this "burning off” the electrode delivers they already have a noticeable emission current, which, however, is still unstable. It follows in generally another activation process. The activation process makes it original non-conductive ionic lattice of alkaline earth oxides in an electronic semiconductor transformed. Here, donor-type impurities become in the crystal lattice of the oxides built-in. These defects consist essentially of elemental alkaline earth metal, e.g. B. from calcium, strontium or barium.
  • the electron emission of such electrodes is based on this impurity mechanism.
  • the activation process has the purpose of to create sufficient amount of excess elemental alkaline earth metal by that the oxides in the electron-emitting coating at a prescribed Heating power can deliver the maximum emission current.
  • the electrode coating namely, continually loses alkaline earth metal during the life of the lamp, partly because the electrode coating evaporates slowly, partly due to the ion current is sputtered in the lamp.
  • the elemental alkaline earth metal is produced by reducing the alkaline earth oxide on the tungsten wire always supplied again during operation of the lamp. This subsequent delivery comes to a standstill, however, when the tungsten wire passes through a high-resistance interface (interface) made of tungsten oxide, alkaline earth silicate or alkaline earth tungstate is passivated.
  • DE 1 021 482 describes a method for producing an oxide cathode for low-pressure discharge lamps known whose activating substance from a mixture of barium oxide, Strontium oxide and calcium oxide exist, which are formed during the formation of the cathode Decomposition of the alkaline earth carbonates used as a starting substance as a result of heating arise, the alkaline earth carbonate mixture consisting of an inactive additive of at least one oxide of the following elements: titanium, germanium, aluminum and other elements of Group III of the Periodic Table of the Elements, in particular the rare earth metals, is added in such an amount that the total amount of Additional oxides in the finished cathode are at most equal to the amount in the least amount of alkaline earth metal oxide used and the cathode by heating up a temperature below 1000 ° C, preferably 800 ° to 900 ° C, is formed.
  • This process has the advantage that the carbonates decompose rapidly at low temperatures and the lamp does not contain carbon dioxide gas.
  • a gas discharge lamp equipped with an electrode, which is a carrier made of an electrode metal selected from the group of tungsten and the alloys containing tungsten, and a first coating from one first electron-emitting material, which is an alkaline earth metal oxide selected from the group calcium oxide, strontium oxide and barium oxide, and a rare earth metal oxide, selected from the group scandium oxide, yttrium oxide and europium oxide in one proportion a contains from 0.1 to 10% by weight.
  • an electrode which is a carrier made of an electrode metal selected from the group of tungsten and the alloys containing tungsten
  • a first coating from one first electron-emitting material which is an alkaline earth metal oxide selected from the group calcium oxide, strontium oxide and barium oxide, and a rare earth metal oxide, selected from the group scandium oxide, yttrium oxide and europium oxide in one proportion a contains from 0.1 to 10% by weight.
  • the passivation of the electrode metal is reduced in such a gas discharge lamp. so that alkaline earth metal is released from the oxide over a longer period of time and the work function of the electrode remains low. This is the ignition phase shortened the lamp.
  • the addition of a rare earth metal oxide causes selected from the group scandium oxide, yttrium oxide and europium oxide in a proportion a contains from 0.1 to 10 wt .-%, a reduction in the evaporation of elemental Alkaline earth metal and therefore an extended service life.
  • the electrode has both high initial emission as well as sufficient elemental alkaline earth metal over the entire Lamp life. The availability of sufficient elemental alkaline earth metal causes high poisoning resistance to oxygen at the same time.
  • a second coating from a second electron-emitting Material which is an alkaline earth metal oxide selected from the group calcium oxide, strontium oxide and barium oxide, and a rare earth oxide selected from the group scandium oxide, Contains yttrium oxide and europium oxide in a proportion b of 2.0 to 20% by weight, is arranged.
  • a between the carrier and the first coating third coating of a noble metal selected from the group rhenium, cobalt, Nickel, ruthenium, palladium, rhodium, iridium, and platinum.
  • a noble metal selected from the group rhenium, cobalt, Nickel, ruthenium, palladium, rhodium, iridium, and platinum.
  • the first electron-emitting material is zirconium oxide contains. It can also be preferred that the second electron-emitting material Contains zirconium oxide.
  • the first electron-emitting substance is a Metal powder preparation from a metal, selected from the group aluminum, silicon, Titanium, zirconium, hafnium, tantalum, molybdenum, tungsten and their alloys, with a powder coating made of a noble metal, selected from the group rhenium, Cobalt, nickel, ruthenium, palladium, rhodium, iridium and platinum.
  • a metal selected from the group aluminum, silicon, Titanium, zirconium, hafnium, tantalum, molybdenum, tungsten and their alloys
  • a noble metal selected from the group rhenium, Cobalt, nickel, ruthenium, palladium, rhodium, iridium and platinum.
  • Fig. 1 shows schematically the generation of light in a fluorescent lamp.
  • Gas discharge lamps can be divided into low-pressure lamps and high-pressure lamps become. They differ in the type of discharge stabilization.
  • Fig. 1 shows a low-pressure discharge lamp with mercury filling, e.g. a fluorescent lamp.
  • a gas discharge lamp consists of a glass tube 1 in rod, ring or U shape.
  • the electrodes 2 are located at the ends of the tube Two-pin base 3.
  • the inside of the glass tube is provided with a fluorescent layer 4, whose chemical composition is the spectrum of light or its color certainly.
  • the glass tube contains a small amount Mercury or mercury vapor, which stimulates to glow under operating conditions, the Hg resonance line at a wavelength of 253.7 nm in the ultraviolet range emitted.
  • the UV radiation emitted excites the phosphors in the phosphor layer to emit light in the visible area 5.
  • the lamp further comprises means for igniting and for operating such.
  • a gas discharge lamp according to the invention contains an electron-emitting electrode, the one support made of an electrode metal and a first coating, the one contains electron-emitting substance.
  • the carrier made of an electrode metal usually consists of tungsten or one Tungsten alloy, possibly with a molybdenum core.
  • the carrier can be used as a Wire, spiral, spiral, shaped as a corrugated wire, tube, ring, plate or ribbon. He will generally heated directly by the flow of electricity.
  • the support can be made of an electrode metal additionally a coating of a precious metal selected from the group rhenium, Cobalt, nickel, ruthenium, palladium, rhodium, iridium, platinum. It preferably consists of a 0.1 to 2 ⁇ m thick iridium or rhenium layer.
  • the raw mass for the electron-emitting substance of a first is placed on the carrier Coating applied.
  • the carbonates of the alkaline earth metals selected from the group calcium, strontium and Barium
  • a rare earth oxide selected from the group scandium oxide, yttrium oxide and europium oxide in a proportion of 0.1 to 10 wt .-% mixed.
  • the weight ratio of calcium carbonate: strontium carbonate: barium carbonate equal to 1: 1.25: .6 or 1: 12: 22 or 1: 1.5. 2.5 or 1: 4: 6.
  • the mixture of alkaline earth oxides and rare earth metal oxide can be coprecipitated be prepared by making a solution of the alkaline earth metal nitrate a water soluble Compound of the rare earth metals is added, and then by adding sodium carbonate the alkaline earth carbonates and the rare earth oxides are precipitated.
  • the electron-emitting material may contain other components, e.g. B. zirconia.
  • a metal powder of the metals can be made from the electron-emitting material from the group aluminum, silicon, titanium, zircon, hafnium, tantalum, molybdenum, tungsten and their alloys with a metal from the group of rhenium, rhodium, palladium, Iridium and platinum coated with a powder coating of iridium, rhenium, rhodium, Platinum, palladium nickel and cobalt is provided.
  • A is preferred Metal powder with an average grain size of 2-3 ⁇ m with a thickness of 0.1 to 0.2 ⁇ m Powder coating used.
  • CVD processes can be used as powder coating processes how to use fluid bed CVD. This coated metal powder becomes the raw mass attached.
  • the raw mass can also be mixed with a binder. It is then through Brushing, dipping, cataphoretic deposition or spraying are applied to the carrier.
  • a second electrode coating can be provided between the carrier and the first electrode coating be arranged, which are made of a second electron-emitting material, an alkaline earth metal oxide selected from the group calcium oxide, strontium oxide and barium oxide, and a rare earth oxide selected from the group scandium oxide, Contains yttrium oxide and europium oxide in a proportion b of 2.0 to 20 wt .-%.
  • the second electron-emitting material can also be zirconium oxide or Metal powder of the metals from the group aluminum, silicon, titanium, zircon, hafnium, Tantalum, molybdenum, tungsten and their alloys with a metal from the group Rhenium, rhodium, palladium, iridium and platinum, which are made with a powder coating Iridium, rhenium, rhodium, platinum, palladium nickel and cobalt is included.
  • the coated electrodes are melted into the lamp ends.
  • the electrodes are formed while the lamp is being evacuated and filled.
  • the electrode wire is heated to a temperature of 1000 ° C to 1200 ° C by direct current passage.
  • the alkaline earth carbonates are converted to the alkaline earth oxides with the release of CO and CO 2 and then form a porous sintered body.
  • the activation takes place, the purpose of which is to supply excess elemental barium embedded in the oxides.
  • the excess barium is created by reducing barium oxide.
  • barium oxide is reduced by the released CO or the carrier metal.
  • there is a current activation which enables the creation of the required free barium through electrolytic processes at high temperatures.
  • the oxides When the lamp is operating, the oxides then slowly evaporate under ion bombardment in the focal spot.
  • a triple-wound tungsten wire is coated with iridium with a layer thickness of 1.0 ⁇ m.
  • iridium with a layer thickness of 1.0 ⁇ m.
  • 3% by weight of scandium oxide powder with an average grain size of 2 ⁇ m and 3% by weight of zirconium metal is added to a triple carbonate mixture of BaCO 3 : SrCO 3 : CaCO 3 in a ratio of 1.6: 1.25: 1 and processed into a suspension with butyl acetate and nitrocellulose. This suspension is used to coat the coated tungsten wire, which is then inserted into a lamp bulb and heated to 1000 ° C.
  • the carbonates of the alkaline earth metals change into their Oxides and the zirconium metal in zirconium oxide. This burn-in process can connect another activation process.
  • Such a lamp has a long service life, a shortened ignition phase, a low one Work function of 1.42 eV and an electrical conductivity improved by a factor of 2.
  • 3 wt .-% yttrium oxide powder with an average grain diameter of 2.5 microns is mixed with a triple carbonate of BaCO 3 : SrCO 3 : CaCO 3 in a ratio of 2.5: 1.5: 1, suspended with butyl acetate and nitrocellulose and spread on a double-coiled tungsten wire, which is then inserted into a lamp bulb and heated to 1000 ° C.
  • This burn-in process can be followed by an activation process.
  • Such a lamp is characterized by an extended service life and increased resistance to poisoning.
  • An electron-emitting mass is produced from a triple carbonate of Ba-CO 3 : SrCO 3 : CaCO 3 in a ratio of 6: 4: 1, to which 0.02% by weight of europium oxide powder is added by coprecipitation, and a further 3% by weight of europium oxide an average grain diameter of 4.0 ⁇ m.
  • the mixture is suspended with butyl acetate and nitrocellulose and spread on a triple-wound tungsten wire, which is then inserted into a lamp bulb and heated to 1000 ° C. This burn-in process can be followed by an activation process.
  • Such a lamp is characterized by an extended service life, increased resistance to poisoning and robust behavior when switched quickly.

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  • Discharge Lamp (AREA)
EP00204147A 1999-11-29 2000-11-21 Lampe à décharge à gaz à électrode pourvu d'un émetteur à oxyde Withdrawn EP1104933A3 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19957420A DE19957420A1 (de) 1999-11-29 1999-11-29 Gasentladungslampe mit Oxidemitter-Elektrode
DE19957420 1999-11-29

Publications (2)

Publication Number Publication Date
EP1104933A2 true EP1104933A2 (fr) 2001-06-06
EP1104933A3 EP1104933A3 (fr) 2004-08-25

Family

ID=7930740

Family Applications (1)

Application Number Title Priority Date Filing Date
EP00204147A Withdrawn EP1104933A3 (fr) 1999-11-29 2000-11-21 Lampe à décharge à gaz à électrode pourvu d'un émetteur à oxyde

Country Status (5)

Country Link
US (1) US6680574B1 (fr)
EP (1) EP1104933A3 (fr)
JP (1) JP2001189145A (fr)
CN (1) CN1298197A (fr)
DE (1) DE19957420A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2004008483A1 (fr) * 2002-07-17 2004-01-22 Philips Intellectual Property & Standards Gmbh Lampe à décharge de gaz basse pression à électrodes

Families Citing this family (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10242241A1 (de) * 2002-09-12 2004-03-25 Philips Intellectual Property & Standards Gmbh Niederdruckgasentladungslampe mit Ba TiO3-ähnlichen Elektronen-Ermittersubstanzen
CN1306554C (zh) * 2004-04-20 2007-03-21 陈宗烈 无灯丝热阴极荧光灯
DE112006002464T5 (de) * 2005-09-14 2008-07-24 Littelfuse, Inc., Des Plaines Gasgefüllter Überspannungsableiter, aktivierende Verbindung, Zündstreifen und Herstellungsverfahren dafür
US7633216B2 (en) * 2005-11-28 2009-12-15 General Electric Company Barium-free electrode materials for electric lamps and methods of manufacture thereof
US7633226B2 (en) * 2005-11-30 2009-12-15 General Electric Company Electrode materials for electric lamps and methods of manufacture thereof
US20080237541A1 (en) * 2007-03-30 2008-10-02 General Electric Company Thermo-optically functional compositions, systems and methods of making
EP2147455A1 (fr) * 2007-05-10 2010-01-27 Philips Intellectual Property & Standards GmbH Lampe à décharge de gaz à remplissage de gaz comprenant du chalcogène
US7786661B2 (en) * 2008-06-06 2010-08-31 General Electric Company Emissive electrode materials for electric lamps and methods of making
DE102009021235B4 (de) * 2009-05-14 2018-07-26 Osram Gmbh Entladungslampe mit beschichteter Elektrode
US20120187871A1 (en) * 2009-09-17 2012-07-26 Osram Ag Low-pressure discharge lamp
CN102142342B (zh) * 2011-03-03 2012-07-25 广州慧沣电子科技有限公司 一种钡钨电极的制备方法
CN103560061A (zh) * 2013-07-26 2014-02-05 江西耀宇光电科技有限公司 一种灯丝材料及其制备工艺

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR694941A (fr) * 1929-07-02 1930-12-09 Tubes à décharge, en particulier tubes luminescents et irradiants
NL95838C (fr) 1952-04-24
NL6804720A (fr) * 1968-04-04 1969-10-07
US4303848A (en) * 1979-08-29 1981-12-01 Toshiba Corporation Discharge lamp and method of making same
US5585694A (en) * 1990-12-04 1996-12-17 North American Philips Corporation Low pressure discharge lamp having sintered "cold cathode" discharge electrodes
US5847498A (en) * 1994-12-23 1998-12-08 Philips Electronics North America Corporation Multiple layer composite electrodes for discharge lamps
WO1997049108A1 (fr) * 1996-06-20 1997-12-24 Mitsubishi Denki Kabushiki Kaisha Cathode de tube electronique
US5962977A (en) * 1996-12-20 1999-10-05 Ushiodenki Kabushiki Kaisha Low pressure discharge lamp having electrodes with a lithium-containing electrode emission material

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2004008483A1 (fr) * 2002-07-17 2004-01-22 Philips Intellectual Property & Standards Gmbh Lampe à décharge de gaz basse pression à électrodes

Also Published As

Publication number Publication date
CN1298197A (zh) 2001-06-06
JP2001189145A (ja) 2001-07-10
DE19957420A1 (de) 2001-05-31
EP1104933A3 (fr) 2004-08-25
US6680574B1 (en) 2004-01-20

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