EP0670588B1 - Lampe aux halogénures métalliques - Google Patents

Lampe aux halogénures métalliques Download PDF

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Publication number
EP0670588B1
EP0670588B1 EP94301523A EP94301523A EP0670588B1 EP 0670588 B1 EP0670588 B1 EP 0670588B1 EP 94301523 A EP94301523 A EP 94301523A EP 94301523 A EP94301523 A EP 94301523A EP 0670588 B1 EP0670588 B1 EP 0670588B1
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EP
European Patent Office
Prior art keywords
halide lamp
metal
metal halide
sealed tube
lamp according
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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
Application number
EP94301523A
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German (de)
English (en)
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EP0670588A1 (fr
Inventor
Kouji Kawai
Shigeki Ishihara
Naoki Masuda
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Hamamatsu Photonics KK
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Hamamatsu Photonics KK
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Priority to JP4256287A priority Critical patent/JPH06111769A/ja
Application filed by Hamamatsu Photonics KK filed Critical Hamamatsu Photonics KK
Priority to EP94301523A priority patent/EP0670588B1/fr
Priority to DE1994603190 priority patent/DE69403190T2/de
Publication of EP0670588A1 publication Critical patent/EP0670588A1/fr
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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
    • H01J61/12—Selection of substances for gas fillings; Specified operating pressure or temperature
    • H01J61/18—Selection of substances for gas fillings; Specified operating pressure or temperature having a metallic vapour as the principal constituent
    • H01J61/20—Selection of substances for gas fillings; Specified operating pressure or temperature having a metallic vapour as the principal constituent mercury vapour

Definitions

  • the present invention generally relates to a metal halide lamp as described in the first part of claim 1 and, more particularly, to contents which are contained in a hermetically sealed tube of a metal halide lamp.
  • Such a lamp is known from EP-A-0 169 510, which will be discussed later.
  • a metal halide lamp is a lamp in which a metal halide is added in a sealed tube, in which mercury vapor is contained at a high pressure, to improve the luminous efficacy and color rending properties, and is widely used for general illumination.
  • a conventional metal halide lamp is fabricated by charging, in a light-transmitting quartz tube, an inert gas, e.g., argon (Ar), at least one kind of halide (LnX 2 or LnX 3 : where Ln is a rare earth metal, e.g., scandium (Sc), yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thul
  • tungsten (W) as the base material of electrodes is liberated by sputtering during use, and free tungsten reacts with silicon dioxide (SiO 2 ) as a constituent component of the sealed tube to deposit on the inner wall surface of the sealed tube, thereby blackening the tube wall within a short period of time. Blackening of the tube wall decreases the luminous efficacy and lumen maintenance factor. When the lumen maintenance factor decreases to about 70%, the metal halide lamp becomes inappropriate for practical use.
  • the present invention seeks to provide a long-life metal halide lamp in which blackening of the tube wall can be prevented.
  • a metal halide lamp comprising a sealed tube and a pair of electrodes comprising tungsten, wherein the sealed tube contains gas mixture including an inert gas, mercury, at least one rare earth metal, bromine, iodine, and at least one alkali metal, wherein the relative amounts of bromine, iodine, rare earth metal and alkali metal are defined by 3 ⁇ M(Br)/M(Ln) ⁇ 2, and [M(Br) + M(I)-M(NA)]/M(Ln) > 4.5, where M(Br) is the number of moles of bromine, M(I) is the number of moles of iodine, M(NA) is the number of moles of alkali metal and M(Ln) is the number of moles of rare earth metal.
  • the total number of moles of bromine and iodine must be in excess of the total number of moles of the rare earth metals.
  • Excess here means that when bromine and iodine react with all the rare earth metals, bromine or iodine that does not react with the rare earth metals remains. Accordingly, even when tungsten is emitted from the electrodes during electric discharge, it can be captured by iodine or bromine.
  • Fig. 1 is a view of a metal halide lamp according to an embodiment of the present invention, and shows the principle of function of the present invention.
  • This metal halide lamp has a transparent quartz sealed tube and a pair of electrodes using tungsten as the base material. The respective electrodes are mounted on the sealed tube with hermetically passing through the wall surface of the sealed tube. The inner end portions of these electrodes are opposed to each other.
  • Argon (Ar), a rare earth metal (Ln), mercury (Hg), cesium (Cs), iodine (I), and bromine (Br) are contained in the sealed tube.
  • these contents are charged in the tube in the form of atoms or compounds. More specifically, bromides of the rare earth metal (LnBr 2 and LnBr 3 ), mercury iodide (HgI 2 ), cesium iodide (CsI), argon gas, and mercury are charged in the tube during the manufacture.
  • the amounts of bromine and iodine are in excess of the amount of rare earth metals.
  • Fig. 1 when arc discharge is started between a pair of opposed electrodes 2 and 3 which are made of tungsten as the base material, mainly in a high-temperature (2,000°C or more) area near the electrodes 2 and 3, most of the contents are ionized. Tungsten of the electrodes 2 and 3 is also emitted from the electrodes 2 and 3 by sputtering and is ionized.
  • bromine or iodine are recombined with cesium, and bromine or iodine are also recombined with rare earth metal. Further, mercury and tungsten are set in the atomic state. The excesses of bromine and iodine which are not recombined with the rare earth metal and cesium are also set in the atomic state. Since bromine has a higher reactivity than iodine, bromine is combined with cesium and rare earth metal before iodine is combined therewith. Therefore, in this medium-temperature area, most of the halogens in the atomic state are iodine.
  • a medium-temperature a range of 1,000°C or more to less than 2,000°C
  • tungsten tends to be combined with iodine. Unlike bromine, even when iodine is combined with mercury, it is quickly separated from mercury. When the amounts of free tungsten and iodine are sufficient with respect to each other, all tungsten atoms are captured by halogens, mainly iodine. Therefore, tungsten will not react with silicon dioxide which is an element constituting the sealed tube. Thereafter, the materials produced in the low-temperature area are circulated in a cycle indicated by arrows due to heat convection.
  • Tungsten iodides WI 2 , WI 3 and WI 4
  • halides of rare earth metal LnX 2 and LnX 3
  • silicon dioxide the low-temperature area
  • these products do not highly react with silicon dioxide, a long period of time is required until the tube wall is blackened to such a degree that the sealed tube is inappropriate for practical use.
  • free tungsten can be captured mainly by iodine and set in the halogen cycle, so that the effect of suppressing blackening of the tube wall is much enhanced.
  • a preferable condition of "excess" described above is expressed by a relation of numbers of moles as follows: [M(Br) + M(I)]/M(Ln) > 4.5 where M(Br) is the number of moles of bromine atoms, M(I) is the number of moles of iodine atoms, and M(Ln) is the number of moles of rare earth metal atoms.
  • Fig. 2 is a view showing the principle of a case wherein bromine is not added at all and only an excess of iodine is charged in a sealed tube.
  • iodine is combined with the rare earth metal, cesium and tungsten.
  • the iodide of the rare earth metal is combined less than the bromide of the rare earth metal, substitution reaction of the rare earth metal with silicon dioxide of the sealed tube often occurs.
  • the rare earth metal tends to deposit on the inner wall surface of the sealed tube, thereby decreasing the service life when compared to a case wherein bromine is contained in the sealed tube.
  • M(Br)/M(Ln) ⁇ 2 The upper limit of the above value is preferably 3 from the results of various experiments. More specifically, 3 ⁇ M(Br)/M(Ln) ⁇ 2
  • a rugby-ball like spherical quartz sealed tube having a major axis of 25 mm, a minor axis of 21 mm, an internal volume of 3.2 cc, and an interelectrode distance of 7 mm was used.
  • Argon gas was contained as an initiating inert gas, and the pressure in the sealed tube was set to 6.65 to 39.9 kPa (50 to 300 torr).
  • the electrodes were made of tungsten as the base material. Cesium was contained to prevent flickering of the lamp.
  • the present invention is not intended to be limited to the above-mentioned size or pressure, etc.
  • Table 1 indicates the compositions, electrical characteristics, optical characteristics, and the like of the contents (excluding argon) of Examples 1 to 9 according to the present invention.
  • two or more kinds of rare earth metals appropriately selected from dysprosium (Dy), holmium (Ho), thulium (Tm), neodymium (Nd) and erbium (Er); an alkali metal, i.e., cesium (Cs); iodine (I); bromine (Br); and mercury (Hg) were contained in the sealed tube to satisfy the relations (2) and (4).
  • the rare earth metals and the alkali metal were charged in the form of iodides or bromides in Examples 1 to 9.
  • the electrical characteristics indicate the initial value
  • the lumen maintenance factor of the optical characteristics is a proportion of the value of the luminous flux at a lapse of a predetermined period of time with respect to the initial value of the luminous flux at the central area on the screen when light was projected from the metal halide lamp of each example which is mounted in an overhead projector.
  • x represented a case wherein the lumen maintenance factor was less than 70% before the lapse of 48 hours since the start of light emission
  • ⁇ represented a case wherein the lumen maintenance factor was 70% or more at the lapse of 48 hours but was less than 70% at the lapse of 500 hours
  • o represented a case wherein the lumen maintenance factor was between 70% or more and less than 80% at the lapse of 500 hours
  • o represented a case wherein the lumen maintenance factor was 80% or more at the lapse of 500 hours.
  • Example 1 As is understood from Table 1, it is apparent that in any of Examples 1 to 9, a high lumen maintenance factor was maintained over a long period of time, and blackening of the tube wall was prevented. Especially, in Example 1 wherein 10.75 x 10 -8 mole of rare earth metals (dysprosium, holmium, and thulium), 0.51 x 10 -6 mole of cesium, 32.76 x 10 -6 mole of iodine, and 27.75 x 10 -6 mole of bromine were contained in the sealed tube, the lumen maintenance factor was maintained at 90% over 1,000 hours and 85% after 1,630 hours, thereby obtaining an excellent result.
  • rare earth metals disprosium, holmium, and thulium
  • Samples 1 to 4 of Table 2 exhibit the performance of each metal halide lamp in which the composition of the contents does not satisfy conditions (2) and (4).
  • Samples 2 and 3 show cases of conventional metal halide lamps wherein experiments were conducted without charging bromine.
  • Sample 4 shows a case of a metal halide lamp in which bromine was charged together with iodine. In Sample 4, however, the relationship between numbers of moles does not satisfy the above conditions. It is apparent that in these Samples 2 and 4 the lumen maintenance factors become less than 70% after 48 hours, so that blackening of the tube wall occurs in an early period.
  • Fig. 3 is a graph showing service life data of Example 1 of the present invention and that of Sample 2. The excellence of the present invention can be clearly recognized from Fig. 3.
  • a ceramic sealed tube mainly a light-transmitting alumina (Al 2 O 3 ) tube
  • quartz (SiO 2 ) sealed tube in place of the quartz (SiO 2 ) sealed tube, because the mechanism of blackening of the alumina tube and preventing it is substantially similar to the one for the quartz tube.
  • a sealed tube which is made of a synthetic transparent glass material comprising quartz or alumina doped with a metal oxide, e.g., ZrO 2 or TiO 2 .
  • the sealed tube need not to be completely transparent but one, e.g., made of frosted glass, that can partly transmit light therethrough may be used instead.
  • the inert gas in the sealed tube is not limited to argon gas, but other gases, e.g., helium, neon, krypton, xenon, or radon gas, can be used.

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  • Discharge Lamp (AREA)

Claims (12)

  1. Lampe aux halogénures métalliques comprenant :
       un tube scellé capable d'émettre de la lumière par lui-même et une paire d'électrodes comprenant du tungstène en tant que matière de base et agencées de manière sensiblement parallèle l'une à l'autre dans le tube scellé, dans laquelle le tube scellé contient un mélange gazeux comprenant un gaz inerte, du mercure, au moins un métal des terres rares, du brome, de l'iode et au moins un métal alcalin, caractérisée en ce que les quantités relatives de brome, d'iode, de métal des terres rares et de métal alcalin sont définies par 3 ≥ M(Br) / M(Ln) ≥ 2,
    Figure imgb0022
     et [M(Br) + M(I) - M(NA)] / M(Ln) > 4,5,
    Figure imgb0023
     où M(Br) est le nombre de moles de brome, M(I) est le nombre de moles d'iode, M(NA) est le nombre de moles de métal alcalin et M(Ln) est le nombre de moles de métal des terres rares.
  2. Lampe aux halogénures métalliques selon la revendication 1, dans laquelle les quantités relatives de brome, d'iode, de métal des terres rares et de métal alcalin sont définies par 2,95 ≥ M(Br) / M(Ln) ≥ 2,2,
    Figure imgb0024
     et [M(Br) + M(I) - M(NA)] / M(Ln) > 4,6.
    Figure imgb0025
  3. Lampe aux halogénures métalliques selon la revendication 1 ou 2, dans laquelle le tube scellé comprend du quartz.
  4. Lampe aux halogénures métalliques selon la revendication 1 ou 2, dans laquelle le tube scellé comprend une céramique.
  5. Lampe aux halogénures métalliques selon la revendication 4, dans laquelle la céramique est de l'oxyde d'aluminium.
  6. Lampe aux halogénures métalliques selon la revendication 1 ou 2, dans laquelle le tube scellé comprend une matière synthétique en verre transparent contenant du quartz dopé avec un oxyde métallique.
  7. Lampe aux halogénures métalliques selon la revendication 1 ou 2, dans laquelle le tube scellé comprend une matière synthétique en verre transparent contenant de l'oxyde d'aluminium dopé avec un oxyde métallique.
  8. Lampe aux halogénures métalliques selon la revendication 6 ou 7, dans laquelle l'oxyde métallique est du ZrO2 ou du TiO2.
  9. Lampe aux halogénures métalliques selon l'une quelconque des revendications 1 à 8, dans laquelle le gaz inerte est choisi parmi l'argon, l'hélium, le néon, le krypton, le xénon et le radon.
  10. Lampe aux halogénures métalliques selon l'une quelconque des revendications 1 à 9, dans laquelle le métal des terres rares est au moins l'un des métaux parmi le scandium, l'yttrium, le lanthanum, le cérium, le praséodyme, le néodyme, le prométhium, le samarium, l'europium, le gadolinium, le terbium, le dysprosium, l'holmium, l'erbium, le thulium, l'ytterbium et le lutétium.
  11. Lampe aux halogénures métalliques selon l'une quelconque des revendications 1 à 10, dans laquelle le métal alcalin est au moins l'un des métaux parmi le lithium, le sodium, le potassium, le rubidium et le césium.
  12. Lampe aux halogénures métalliques selon l'une quelconque des revendications 1 à 11, dans laquelle au moins du fluor ou du chlore est contenu dans le tube scellé à la place de ou en association avec le brome.
EP94301523A 1992-09-25 1994-03-02 Lampe aux halogénures métalliques Expired - Lifetime EP0670588B1 (fr)

Priority Applications (3)

Application Number Priority Date Filing Date Title
JP4256287A JPH06111769A (ja) 1992-09-25 1992-09-25 メタルハライドランプ
EP94301523A EP0670588B1 (fr) 1992-09-25 1994-03-02 Lampe aux halogénures métalliques
DE1994603190 DE69403190T2 (de) 1994-03-02 1994-03-02 Metallhalogenidlampe

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP4256287A JPH06111769A (ja) 1992-09-25 1992-09-25 メタルハライドランプ
EP94301523A EP0670588B1 (fr) 1992-09-25 1994-03-02 Lampe aux halogénures métalliques

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EP0670588A1 EP0670588A1 (fr) 1995-09-06
EP0670588B1 true EP0670588B1 (fr) 1997-05-14

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Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5866981A (en) * 1995-08-11 1999-02-02 Matsushita Electric Works, Ltd. Electrodeless discharge lamp with rare earth metal halides and halogen cycle promoting substance
JPH10283993A (ja) * 1997-04-03 1998-10-23 Matsushita Electron Corp メタルハライドランプ
US20090146571A1 (en) * 2007-12-06 2009-06-11 Russell Timothy D Metal halide lamp with halogen-promoted wall cleaning cycle
US8482198B1 (en) * 2011-12-19 2013-07-09 General Electric Company High intensity discharge lamp with improved startability and performance

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5532338A (en) * 1978-08-29 1980-03-07 Mitsubishi Electric Corp Metal halide lamp
DE3427280C2 (de) * 1984-07-24 1986-06-12 Patent-Treuhand-Gesellschaft für elektrische Glühlampen mbH, 8000 München Metallhalogenid-Hochdruckentladungslampe
DE3512757A1 (de) * 1985-04-10 1986-10-23 Philips Patentverwaltung Gmbh, 2000 Hamburg Metallhalogenid-hochdruckgasentladungslampe
DE4030202A1 (de) * 1990-09-24 1992-03-26 Patent Treuhand Ges Fuer Elektrische Gluehlampen Mbh Metallhalogenid-hochdruckentladungslampe

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EP0670588A1 (fr) 1995-09-06

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