US3900754A - Electric discharge lamp - Google Patents

Electric discharge lamp Download PDF

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Publication number
US3900754A
US3900754A US434382A US43438274A US3900754A US 3900754 A US3900754 A US 3900754A US 434382 A US434382 A US 434382A US 43438274 A US43438274 A US 43438274A US 3900754 A US3900754 A US 3900754A
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United States
Prior art keywords
coating
lamp
lamp according
phosphate
metal
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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 - Lifetime
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US434382A
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English (en)
Inventor
David Robert Mason
Susan Margaret Cole
Maurice Arthur Cayless
David Osborn Wharmby
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Thorn Lighting Ltd
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Thorn Lighting Ltd
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Publication date
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Priority to US05/564,767 priority Critical patent/US3984590A/en
Application granted granted Critical
Publication of US3900754A publication Critical patent/US3900754A/en
Priority to US05/826,237 priority patent/USRE30165E/en
Anticipated expiration legal-status Critical
Expired - Lifetime 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
    • H01J61/30—Vessels; Containers
    • H01J61/35—Vessels; Containers provided with coatings on the walls thereof; Selection of materials for the coatings
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J17/00—Gas-filled discharge tubes with solid cathode
    • H01J17/02—Details
    • H01J17/04—Electrodes; Screens

Definitions

  • the present invention relates to electric discharge devices and more especially to discharge lamps the envelopes of which contain a fill of a reactive gas or vapour.
  • the invention is concerned with the provision of protective coatings on internal surfaces of such lamps.
  • discharge lamp have gas fills containing gases or vapours which are reactive or potentially reactive with materials commonly used for lamp envelopes and the internal components of the lamps.
  • gases or vapours which are reactive or potentially reactive with materials commonly used for lamp envelopes and the internal components of the lamps.
  • metal halide discharge lamps and metal vapour discharge lamps containing the vapours of reactive metals, such as sodium.
  • the radiation is produced by an electric are between two primary electrodes extending into an envelope, or are tube, containing mercury and one or more metallic halides which are at least partially vaporised and dissociated by the heat of the arc during operation of the lamp.
  • the envelope is commonly constructed of vitreous fused silica, although sometimes another transparent or translucent glass, ceramic or crystalline material is used.
  • attack by reactive fill substance on portions of the structure of a discharge lamp or device is reduced or prevented by providing, on at least those portions of the internal surface of the discharge envelope or the exposed surfaces of internal components which tend to react with the fill, a coating of a metal phosphate or arsenate glass.
  • the surfaces to be covered will usually include the internal surfaces of the envelope and the electrode supports.
  • ex ternal surfaces of the arc tube or components thereof may also be protected by a coating of metal phosphate or arscnate glass and thereby preserved from attack by gases or vapours in the outer envelope.
  • the protective coatings provided in accordance with this invention may be applied to conventional materials used for the fabrication of lamp components, for example to protect them from highly reactive fill substances, or they may enable cheaper and more readily available materials to be substituted for conventionally used materials without unacceptable loss in performance or life.
  • the coating is preferably derived from an aluminum phosphate complex as described in German Offenlegungschrift (DOS) No. 2,028,839 (British Pat. Nos. 1,322,722 and l,322,724), one or more of the metal phosphate or arsenate compositions prepared in accordance with DOS No. 2,235.65 l or from a composition comprising an aluminium phosphate and containing a titanium compound prepared in accordance with DOS No. 2,331,954. Combinations of these compositions can also be used.
  • DOS German Offenlegungschrift
  • preferred metal phosphates and arsenates are those of atomic number l2 to i4, 20 to 32, 39 to 50, 56 to 80, 90 or 92.
  • phosphate is here meant to include ortho-, metaand pyrophosphates together with phosphinates and phosphonates.
  • Especially preferred sources of metal phosphate coatings are solvent-soluble complex phosphates containing coordinated solvent groups, such as water or polar organic solvents, as described in DOS Nos. 2,028,839 and 2,235,651. Not only are the isolated complex phosphates themselves suitable, but the compositions which are therein described containing phosphate precursors may also be used.
  • Liquid coating compositions may be used which comprise a solution. of (a) a metal compound and (h) an oxyacid of phosphorus or arsenic, or a compound capable of forming such an oxyacid in the solution. At least part of the solvent may be organic. These compositions are capable of decomposing to a metal phosphate or arsenate on being heated.
  • the solvent is selected from water or the wide range of organic solvents which dissolve the components of the composition.
  • the organic solvent when used. is preferably selected from alcohols, esters, ketones, aldehydes, nitrocompounds and ethers, especially monohy dric alcohols of the structure ROH, esters of the structure RCOOR ethers of the structure R'OR' ketones of the structure RCOR", nitrocompounds of the structure RNO and ethers of the structure OR, where R.
  • R are alkyl groups or substituted alkyl groups containing from I to it) carbon atoms each, and R" is a divalent alkyl group having from 4 to 7 carbon atoms one of which may be replaced by an oxygen atom.
  • Mixtures of one or more solvents may be used. Diluents may also be present, provided they do not bring about precipitation of the components of the composition.
  • Aliphatic alcohols containing 1 to 10 carbon atoms are particularly convenient, especially lower molecular weight alcohols containing 1 to 4 carbon atoms, for example methanol, ethanol, nor iso-propanol and substituted alcohols especially methoxyor ethoxy-ethanol.
  • Suitable esters are ethyl acetate or carbonate. Acetyl acetone may be used. Tetrahydrofuran is the most preferred ether to use, though dioxan may also be used.
  • Aromatic hydroxy compounds can be used, but solubility is low in such materials.
  • the composition may be formed by dissolving an isolated complex of the type described in the specifications referred to above in a solvent.
  • the metal compound may itself be a phosphate and so provide the oxyacid of phosphorus or arsenic, in which case an additional acid may be required to form a homogeneous solution, e.g. hydrochloric or nitric acid.
  • a wide range of metal compounds may be used. Sim ple inorganic compounds including oxides and hydroxides are suitable, as are salts such as halides, carbonates, nitrates, phosphates. perchlorates and cyanates. Sulphates may be used in some cases but they can be 3 disadvantageous owing to the difficult with which they are thermally decomposed.
  • salts of organic acids such as acetates. benzoates. oxalates. propionatcs or formates. Alkoxides are also useful.
  • co-ordination complexes of the metal may be used, for example complexes having ligands derived from acetylacetone. ethylenedithiol. ethanolamine, carbon monoxide or phosphines.
  • compositions are those in which the metal and oxyacid are present with atomic ratios of metal to phosphorus or arsenic from 1:0.l to l:2.9.
  • Preferred metals are aluminum, iron, chromium titanium, vanadium and tin.
  • a solvent-soluble aluminium phosphate may be used.
  • Normal aluminium orthophosphate is insoluble in water but soluble in dilute mineral acids (for example hydrochloric and nitric acids) and in some carboxylic acids (for example citric acid) and such solutions may be used for the purpose of this invention.
  • dilute mineral acids for example hydrochloric and nitric acids
  • carboxylic acids for example citric acid
  • solid complex aluminium phosphates containing the anion of the acid and chemically-bound water or alcohol (or a mixture thereof) may also be used.
  • the complex contains an alcohol group
  • ethyl alcohol, n-propyl alcohol or isopropyl alcohol although complexes with higher alcohols are known and may be used if desired.
  • the complex phosphates most commonly contain from three to five molecules of the hydroxy compound per phosphorus atom, for example water-containing complexes may have an empirical formula corresponding to AlPO .HCl.(H O), where x is in the range 3 to 5.
  • the complex aluminium phosphates containing alcohol and their solutions may be prepared by reacting aluminium compound. preferably halide, with an alcohol and phosphoric acid.
  • aluminium compound preferably halide
  • One such compound has the empirical formula Al P Cl H C O
  • the complex phosphate containing water can be made as above or by hydrolysing the alcoholcontaining complex phosphates or, for example, by contacting aluminium phosphate hydrate with gaseous hydrogen chloride.
  • Iron. chromium, vanadium titanium and tin phosphate-containing coatings may be prepared by dissolving a salt, preferably a halide, in an alcohol and adding phosphoric acid or a source thereof.
  • the glass layer should be free from pin-holes or other defect or imperfection which might cause it to break down during operation of the lamp.
  • the desired portions of the internal surface of the envelope and the surfaces of internal components which are exposed in the finished lamp are coated either separately or after assembly with a liquid composition capable of generating the desired metal phosphate or use nate. and subsequently heated to evaporate the solvent and cure the composition to form a defect-free metal phosphate or arsenate coating. It has been found valuable in the production of defectfree coatings to allow the applied liquid coating composition to drain thoroughly and thereafter to bake initially at a relatively low temperature to remove the solvent and subsequently at a controlled higher temperature to complete the formation of the protective coating. The preferred baking temperatures vary with the particular composition of coating material employed, but can be determined by experiment.
  • FIGS. 1, 2 and 3 are respective diagrammatic views of three forms of discharge device to which the invention may be applied.
  • FIG. 4 is a diagrammatic view of a fourth form of discharge device to which the invention may also be applied.
  • surfaces of electric discharge lamps and devices or compo nents thereof tending to react with the lamp contents are provided with coatings of the phosphate or arsenate glasses described above.
  • FIGS. 1 to 3 are shown three examples of discharge devices or lamps.
  • the arc tube or envelope 10 is constructed of vitreous fused silica, into which are sealed electrodes 11 on tungsten shanks l2, electrically connected to external leads or connectors 13 through molybdenum foil pinch seals 14.
  • An exhaust tube 15 is provided in the wall of the tube 10 and is sealed off in the finished lamp, as shown in the drawmg.
  • the form of lamp shown in FIG. 1 commonly contains a mixture of the iodides of scandium, sodium, thorium and mercury, in addition to metallic mercury and a quantity of argon gas.
  • An additional auxiliary electrode 16 may be sealed through one end of the tube 10 for starting purposes.
  • An are tube of this kind is normally sealed in an outer glass jacket (not shown) which is either evacuated or filled with an inactive gas, and which may be coated with a phosphor.
  • Lamps of this type are commonly designated MB] or MBIF lamps.
  • Other lamps of this construction contain the halides of aluminium or tin, and are commonly referred to as molecular arc lamps.
  • the form of lamp shown in FIG. 2 may contain the halides of sodium, gallium, thallium and mercury, together with metallic mercury and a rare gas such as xenon. These lamps are very compact and operate at a higher pressure than those of FIG. I. They are not normally operated in an outer envelope (although they may sometimes be) and are commonly designated Compact Source lamps, or CSI lamps.
  • Theform of lamp shown in FIG. 3 has a longer and narrower arc tube than those of FIG. I, and is designed to operate without an hermetically sealed outer jacket, but usually in a special closed fitting.
  • These lamps may contain similar halide mixtures to those used in the type of lamp shown in FIG. I, but other versions intended for photochemical and other special purposes contain other halides, such as the iodides of gallium, indium or bismuth. Lamps of this type are commonly designated MBIL lamps.
  • FIG. 4 a further type of arc tube 10 which is made of a translucent ceramic material, such as alumina, or a transparent crystalline material, such as crystalline alumina or sapphire, and in which electrodes ll are sealed, either through metallic caps 17 or ceramic plugs sealed to the ends.
  • the metallic caps are often of niobium or a niobium alloy, which is particularly reactive with metallic halide compounds.
  • Lamps of this type frequently contain highly reactive metallic elements, such as sodium or the other alkali metals, which cannot be used in arc tubes constructed of vitreous silica or most glasses.
  • the arc tubes of these lamps are commonly fitted within outer jackets.
  • Such interactions with the lamp components are not limited to normal chemical reactions with the halides in their solid, liquid or gaseous forms.
  • the presence of the discharge and the associated electric fields permits a much wider range of interaction, erosion or attack, involving the products of dissociation of the compounds, and excited or ionized species derived from them.
  • Electrolytic processes may produce further reactions, and may increase the rate of which some of the interactions occur.
  • impurity gases or vapours commonly present in lamp envelopes such as water vapour or oxygen may give rise to still further reactions, and enhance the rate of others. Traces of such impurities are commonly left in the gaseous filling during processing, or are introduced with the halides, or may be released from the various components by the action of the discharge.
  • oxygen-containing impurities in lamps containing aluminium trichloride can in some circumstances produce chlorine by the reaction:
  • the present invention can be utilized to prevent, control or reduce the incidence of, deleterious interactions of these kinds between the metallic or halide contents and the components of the lamp in contact with them, by coating the surfaces in contact with the metals or halides with a protective layer of metal phosphate or arsenate glass composition which is resistant to interactions of these kinds.
  • the surfaces to be protected usually include the internal surface of the envelope and the exposed surfaces of the electrode leads or supports, and metal end caps when present, together with, when possible, the regions where different components join.
  • the active surface of the electrodes will not normally be covered. Such surface coatings are shown as coatings 16 in the figures.
  • the metallic caps 17 of lamps of the type shown in FIG. 4 are susceptible to reaction with impurity gases or vapours such as water vapour or oxygen in the surrounding outer jacket.
  • the leads adjacent to the arc tube in lamps of the type shown in FIG. 3 are liable to reaction with the sur rounding air in the fitting. Both these may be protected by external coatings of this type.
  • the protective layer should be effectively free from pinholes or other defects or imperfections which will cause it to break down during operation of the lamp, although a substantial degree of protection, and consequent improvement in lamp quality may be obtained in some cases when such perfection is not fully achieved.
  • the coating In a preferred method of providing the coating, it is applied to the whole of the interior of the arc tube after the components have been substantially assembled. This has the advantage that the regions where the components join, which are often particularly susceptible to attack, are fully coated.
  • the active areas of the electrodes may also be coated in this process, but the coating on these will normally be removed when the arc is first struck, or the lamps first operated.
  • the protective coating may alternatively be applied by coating the components individually before assembly. This method might be used, for example, where it is essential that the active surface of the electrode is not brought into contact with the coating material or any products of reaction associated with it, or it might be used when required by a particular manufacturing technique.
  • the coating can be applied by filling, injecting or spraying the inside of the arc tube with the complex or a solution of the complex and subsequently removing or draining any surplus, or it can be applied to the individual components by any of the methods described in DOS No. 2,235,651.
  • the complex is then decomposed by heating to yield a phosphate (or arsenate) of layer by heating at a temperature below l000C as described in the same specification.
  • the construction and processing of the lamp is then completed in the normal way. The following is one example of the application of the invention.
  • a 400W aluminium chloride discharge lamp with an arc tube of the form shown in FIG. 1 is protected by coating the inside of the arc tube 10 in the following manner.
  • a solution is prepared by adding slowly and with stirring, 4.646 g anhydrous aluminium chloride to 9l.458 g methanol. 3.866 G orthophosphoric acid (88%) is then added.
  • the resultant solution is dispensed from a hypodermic syringe, through the lamp exhaust tube 15, before this is sealed off. It is distributed around the inside of the arc tube, which is then inverted and left to drain, leaving only a thin layer adhering to the inside surfaces.
  • the resultant coating is baked at lOC in a vacuum for l hour and finally formed by baking at 400C for 3 minutes.
  • the lamp is then processed in the normal manner for discharge lamps of this type to give an arc tube of volume 2.2 cm which contains 7.4 mg AlCl and 44 mg Hg together with a pressure of 20 Torr of argon at room temperature.
  • arc tube of volume 2.2 cm which contains 7.4 mg AlCl and 44 mg Hg together with a pressure of 20 Torr of argon at room temperature.
  • the arc is struck and the glass layer on the active surface of the electrode is removed, leaving the protective layer over the internal surfaces of the arc tube and the cooler parts of the electrode structures.
  • the layer substantially increases the resistance of the cooler parts of the electrode leads from erosion by the chloride vapour, preventing blackening of the envelope surface by deposited tungsten and other reaction products.
  • the silica is also protected from reaction with the aluminium chloride.
  • aluminium phosphate or arsenate coatings may be used, prepared from solutions of halogen-containing complex phosphates or arsenates of aluminium as disclosed in DOS No. 2,331,954, coating the internal lamp surfaces, and heating to cure the coating under the conditions substantially as disclosed in the same Application.
  • coatings may be used prepared from liquid compositions of other metal compounds and oxyacids of phosphorus or arsenic as disclosed in DOS No. 2,235.65 l, coating the internal lamp surfaces and heating under the conditions substantially as disclosed in the same Application, the remainder of the processing following the same general lines as in the above preferred example.
  • the essential feature of the invention is the provision of a continuous layer consisting essentially of a metal phosphate or arsenate glass covering the interior surface of the envelope or any internal components that could react with the full or contents of the lamp at the operating temperatures.
  • any external surfaces to be protected may be coated either before or after assembly.
  • An electrical discharge lamp comprising: an arc tube;
  • components including a pair of spaced electrodes in said arc tube and respective conductive leads or supports for said electrodes;
  • a transparent, defect-free, solution-deposited protective coating of a vitreous compound selected from metal phosphates and arsenates on at least the internal surface of the arc tube and the exposed surfaces of said leads or supports which tend to react with said fill during operation of the lamp.
  • a lamp according to claim I further comprising metallic end caps on said tube, the internal surface of said end caps being also provided with said coating.
  • a lamp according to claim I further comprising a coating of a metal phosphate or arsenate glass on the external surfaces of said are tube and components of said lamp.
  • a lamp according to claim 3 further comprising a light-transmitting outer jacket enclosing said are tube and components.
  • a lamp according to claim 1 wherein said coating comprises a phosphate or arsenate glass of at least one of the metals aluminium. iron, chromium, titanium, vanadium and tin.
  • a lamp according to claim 1 wherein said coating is composed of an aluminium phosphate glass.
  • a lamp according to claim I wherein said coating is the deposited and baked residue of a solvent-soluble complex phosphate or arsenate.
  • a lamp according to claim I wherein said coating comprises the deposited and baked residue of a compound of said metal and an acid moiety selected from oxyacids of phosphorous or arsenic.

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  • Vessels And Coating Films For Discharge Lamps (AREA)
  • Formation Of Various Coating Films On Cathode Ray Tubes And Lamps (AREA)
US434382A 1973-01-19 1974-01-18 Electric discharge lamp Expired - Lifetime US3900754A (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
US05/564,767 US3984590A (en) 1974-01-18 1975-04-03 Electric discharge lamp
US05/826,237 USRE30165E (en) 1973-01-19 1977-08-19 Electric discharge lamp

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB295373A GB1463056A (en) 1973-01-19 1973-01-19 Electric discharge lamp

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US05/564,767 Division US3984590A (en) 1974-01-18 1975-04-03 Electric discharge lamp
US05/826,237 Reissue USRE30165E (en) 1973-01-19 1977-08-19 Electric discharge lamp

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US (1) US3900754A (it)
JP (1) JPS5526588B2 (it)
BE (1) BE809913A (it)
CA (1) CA1050605A (it)
DE (1) DE2402422C3 (it)
FR (1) FR2214966B1 (it)
GB (1) GB1463056A (it)
IE (1) IE38744B1 (it)
IT (1) IT1009576B (it)
LU (1) LU69187A1 (it)
NL (1) NL7400807A (it)
SE (1) SE391835B (it)
ZA (1) ZA74278B (it)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4256988A (en) * 1977-01-17 1981-03-17 Thorn Lighting Limited Incandescent halogen lamp with protective envelope coating
DE3110818A1 (de) * 1980-03-24 1981-12-24 Gte Products Corp., Wilmington, Del. Bogenentladungslampe
DE3110810A1 (de) * 1980-03-24 1982-01-28 Gte Products Corp., Wilmington, Del. Metalldampflampe
DE3110809A1 (de) * 1980-03-24 1982-02-04 Gte Products Corp., Wilmington, Del. Metallhalogenid-bogenentladungslampe
US4987341A (en) * 1987-01-23 1991-01-22 Heimann Gmbh Flash lamp with metal coating on an outer end of an electrode thereof
US5032762A (en) * 1990-07-16 1991-07-16 General Electric Company Protective beryllium oxide coating for high-intensity discharge lamps
DE4422778A1 (de) * 1993-06-29 1995-01-12 Matsushita Electric Works Ltd Metalldampf-Bogenentladungslampe
US5473226A (en) * 1993-11-16 1995-12-05 Osram Sylvania Inc. Incandescent lamp having hardglass envelope with internal barrier layer
US20030146705A1 (en) * 2002-02-01 2003-08-07 Phoenix Electric Co., Ltd. Ultra-high pressure discharge lamp

Families Citing this family (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4196232A (en) * 1975-12-18 1980-04-01 Rca Corporation Method of chemically vapor-depositing a low-stress glass layer
NL8202778A (nl) * 1982-07-09 1984-02-01 Philips Nv Lagedrukkwikdampontladingslamp.
DE3236462A1 (de) * 1982-10-01 1984-04-05 Patent-Treuhand-Gesellschaft für elektrische Glühlampen mbH, 8000 München Hochdruckentladungslampe mit sockel und zugehoeriger fassung
US4528478A (en) * 1983-06-09 1985-07-09 Gte Products Corporation Single-ended metal halide discharge lamp with minimal color separation
CA1255746A (en) * 1983-06-09 1989-06-13 George J. English Single-ended metal halide discharge lamps and process of manufacture
US4557700A (en) * 1983-06-09 1985-12-10 Gte Products Corporation Metal halide discharge lamp gas fill process to provide minimal color separation
JPS6220236A (ja) * 1985-07-19 1987-01-28 Hitachi Ltd 電球型蛍光灯
US4998036A (en) * 1987-12-17 1991-03-05 Kabushiki Kaisha Toshiba Metal vapor discharge lamp containing an arc tube with particular bulb structure
DE4235743A1 (de) * 1992-10-23 1994-04-28 Heraeus Noblelight Gmbh Hochleistungsstrahler
DE19730888A1 (de) * 1997-07-18 1999-01-28 Bosch Gmbh Robert Gasentladungslampe mit niedriger Zündspannung

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2030397A (en) * 1931-12-18 1936-02-11 Gen Electric Composite glass container
US2393469A (en) * 1942-08-03 1946-01-22 Corning Glass Works Fluorescent glass and lamp made therefrom

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2030397A (en) * 1931-12-18 1936-02-11 Gen Electric Composite glass container
US2393469A (en) * 1942-08-03 1946-01-22 Corning Glass Works Fluorescent glass and lamp made therefrom

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4256988A (en) * 1977-01-17 1981-03-17 Thorn Lighting Limited Incandescent halogen lamp with protective envelope coating
DE3110818A1 (de) * 1980-03-24 1981-12-24 Gte Products Corp., Wilmington, Del. Bogenentladungslampe
DE3110810A1 (de) * 1980-03-24 1982-01-28 Gte Products Corp., Wilmington, Del. Metalldampflampe
DE3110809A1 (de) * 1980-03-24 1982-02-04 Gte Products Corp., Wilmington, Del. Metallhalogenid-bogenentladungslampe
US4321504A (en) * 1980-03-24 1982-03-23 Gte Products Corporation Low wattage metal halide arc discharge lamp
US4987341A (en) * 1987-01-23 1991-01-22 Heimann Gmbh Flash lamp with metal coating on an outer end of an electrode thereof
US5032762A (en) * 1990-07-16 1991-07-16 General Electric Company Protective beryllium oxide coating for high-intensity discharge lamps
DE4422778A1 (de) * 1993-06-29 1995-01-12 Matsushita Electric Works Ltd Metalldampf-Bogenentladungslampe
US5500571A (en) * 1993-06-29 1996-03-19 Matsushita Electric Works, Ltd. Metal vapor discharge lamp
US5473226A (en) * 1993-11-16 1995-12-05 Osram Sylvania Inc. Incandescent lamp having hardglass envelope with internal barrier layer
US20030146705A1 (en) * 2002-02-01 2003-08-07 Phoenix Electric Co., Ltd. Ultra-high pressure discharge lamp
US6713963B2 (en) * 2002-02-01 2004-03-30 Phoenix Electric Co., Ltd. Ultra-high pressure discharge lamp

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Publication number Publication date
BE809913A (fr) 1974-05-16
DE2402422A1 (de) 1974-07-25
GB1463056A (en) 1977-02-02
IE38744B1 (en) 1978-05-24
FR2214966A1 (it) 1974-08-19
IT1009576B (it) 1976-12-20
JPS49104477A (it) 1974-10-03
LU69187A1 (it) 1974-04-08
CA1050605A (en) 1979-03-13
JPS5526588B2 (it) 1980-07-14
IE38744L (en) 1974-07-19
AU6468274A (en) 1975-07-24
FR2214966B1 (it) 1980-01-11
DE2402422B2 (de) 1978-03-23
DE2402422C3 (de) 1978-11-30
NL7400807A (it) 1974-07-23
ZA74278B (en) 1975-05-28
SE391835B (sv) 1977-02-28

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