EP0604207B1 - Lampe à arc à halogénure métallique - Google Patents

Lampe à arc à halogénure métallique Download PDF

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Publication number
EP0604207B1
EP0604207B1 EP19930310407 EP93310407A EP0604207B1 EP 0604207 B1 EP0604207 B1 EP 0604207B1 EP 19930310407 EP19930310407 EP 19930310407 EP 93310407 A EP93310407 A EP 93310407A EP 0604207 B1 EP0604207 B1 EP 0604207B1
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EP
European Patent Office
Prior art keywords
arc tube
metal halide
lamps
arc
titanium oxide
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 - Lifetime
Application number
EP19930310407
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German (de)
English (en)
Other versions
EP0604207A1 (fr
Inventor
Robert G. Jenkins
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.)
Flowil International Lighting Holding BV
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Flowil International Lighting Holding BV
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Publication date
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Publication of EP0604207A1 publication Critical patent/EP0604207A1/fr
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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
    • H01J61/30—Vessels; Containers
    • H01J61/302—Vessels; Containers characterised by the material of the vessel

Definitions

  • This invention relates generally to a metal halide arc discharge lamp.
  • a typical metal halide arc discharge lamp includes a quartz or fused silica arc tube that is hermetically sealed within a borosilicate glass lamp envelope.
  • the arc tube itself hermetically sealed, has tungsten electrodes mounted therein and contains a fill material including mercury, metal halide additives and a rare gas to facilitate starting.
  • the lamp envelope is filled with nitrogen or another inert gas at less than atmospheric pressure. In other cases, particularly in low wattage lamps, the lamp envelope is evacuated.
  • Sodium is an important constituent in most high intensity metal halide arc discharge lamps, usually in the form of sodium iodide or sodium bromide. Sodium is used to improve the efficiency and colour rendering properties of the metal halide lamps. It has long been recognized that sodium loss during operation is a problem with metal halide discharge lamps having arc tubes that contain sodium halides. As sodium is lost through the arc tube wall, iodide is freed and combines with mercury to form mercury iodide. Mercury iodide leads to increased reignition voltages, thereby causing starting and lamp maintenance problems.
  • Sodium loss results from the movement or migration of sodium ions through the arc tube wall.
  • a first theory suggests that sodium loss is caused by the emission of ultraviolet (UV) photons from the arc tube. These UV photons cause electrons to be ejected from materials, such as metals, that are positioned within the outer jacket of the lamp. The electrons ejected from these materials collect on the outside surface of the arc tube and form a negatively charged layer. The build-up of negatively charged electrons along the outer surface of the arc tube attracts positively charged sodium ions from within the arc tube and enhances their migration through the quartz arc tube wall. Once the positively charged sodium ions reach the outer surface of the arc tube wall, they are neutralized by the electrons present on the surface of the arc tube, evaporate as atoms and travel to cold spots in the lamp where they condense.
  • UV photons ultraviolet
  • a second theory suggests that the loss of sodium from the arc tube is not primarily caused by UV radiation emitted from the arc tube. Rather, this theory suggests that the loss of sodium is due to the thermal migration of sodium ions through the arc tube wall during the operation of the lamp.
  • a coating of ZrO 2 is provided over metal surfaces positioned within the lamp envelope external to the arc tube.
  • the ZrO 2 coating prevents UV photons from reaching the metal surfaces, thereby preventing any electrons from being ejected therefrom.
  • ceramic tubes or other ceramic coatings have also been used to perform this function. This technique of shielding the metal surfaces within the lamp envelope suffers from disadvantages in that it increases the manufacturing costs of the metal halide lamps and may not be durable for extended burn life.
  • a metal halide lamp comprising an arc tube housed within an outer jacket, the arc tube comprising a sealed envelope and a fill material consisting substantially of mercury, metal halide additives including a sodium halide and a rare gas, characterised in that said arc tube envelope is of vitreous silica doped with between one hundred and fifty to three hundred and fifty parts per million by weight of titanium oxide.
  • a method for making such a lamp is defined in claim 5.
  • the vitreous silica may be formed by doping quartz sand with a titanium compound, such as titanium oxide, prior to melting.
  • a titanium compound such as titanium oxide
  • the preferred concentration of the titanium oxide dopant is approximately two hundred and fifty parts per million by weight.
  • Preferred metal halide discharge lamps of the present invention utilizing arc tubes formed from the titanium oxide doped quartz can demonstrate increased lumen output and lumen maintenance.
  • Fig. 1 illustrates a typical metal halide arc discharge lamp in which embodiments of the present invention can be utilized. It should be understood that Fig. 1 is provided merely for illustrative purposes and that the preferred arc tubes of the present invention can be used with any type of metal halide arc tube lamp, including those having structures that differ from the example shown in Fig. 1.
  • a lamp 2 includes a lamp envelope 4 and an arc tube 6 mounted within lamp envelope 4.
  • the arc tube 6 is a metal halide arc discharge tube having characteristics that are described below.
  • Lower support means 8 comprises a U-shaped support made up of vertical wires 14 and 16 extending from a base wire 18.
  • the vertical wires 14 and 16 are welded to a strap 20 that supports the lower end of the arc tube 6.
  • Upper support means 10 similarly comprises a U-shaped support made up of vertical wires 22 and 24 extending from a base wire 26.
  • the vertical wires 22 and 24 are welded to a strap 28 that supports the upper end of the arc tube 6.
  • Electrode energy is coupled to the arc tube 6 through a base 28.
  • a pair of stiff lead-in wires 30 and 32 are electrically connected to the base 28.
  • Lead-in wire 32 is welded to base wire 18 of the lower support means 8.
  • An additional lead-in wire 34 is electrically connected to vertical wire 16 of lower support means 8.
  • Lead-in wire 34 is connected, via a molybdenum foil 36, to an electrode 38 within the arc tube 6.
  • a resistor 40 is attached to lead-in wire 30 and to a connector 42.
  • Connector 42 is connected, via a molybdenum foil 44, to a starting probe 46.
  • a lead-in wire 48 is attached, via a molybdenum foil 50, to an electrode 52.
  • Lead-in wire 48 is electrically connected to stiff lead-in wire 30 through a thin conducting lead 54.
  • the molybdenum foils 36, 44 and 50 are located in press seals at opposite ends of arc tube 6.
  • the present invention is directed to improving an arc tube for use in a metal halide lamp such as the one shown in Fig. 1.
  • the arc tube of the present invention is formed of a titanium oxide doped vitreous silica.
  • the vitreous silica is fused quartz that is made from a melt doped with TiO 2 .
  • This doped quartz is hereafter referred to as "ozone free quartz" because the titanium oxide dopant reduces the emission of UV radiation from the arc tube that would produce ozone.
  • the titanium oxide in the ozone free quartz may help to retard the movement of sodium ions through the arc tube wall.
  • the titanium oxide in the ozone free quartz absorbs UV radiation so that the amount of UV radiation emitted from the arc tube is reduced.
  • one theory regarding the cause of sodium loss in metal halide lamps suggests that UV photons emitted from the arc tube cause electrons to be ejected from materials in the outer jacket, thereby generating a negatively charged layer that attracts positively charged sodium ions through the arc tube wall. Consequently, by reducing the amount of UV radiation emitted from the arc tube, it is believed that the use of ozone free quartz results in a reduction of sodium loss from the arc tube of the metal halide discharge lamp.
  • the concentration of titanium oxide in the ozone free quartz utilized for the test run described above was 250 parts per million by weight. However, it is believed that the advantages of the present invention can be achieved with ozone free quartz having various other concentrations of titanium oxide within the range of 150 to 350 parts per million by weight. Additionally, although TiO 2 was used as the dopant in forming the ozone free quartz, other titanium compounds could also be utilized that form titanium oxide when heated. Examples of other titanium compounds that are believed to be suitable for use as a dopant are titanium nitrate and compounds from the family of titanium alkoxides, such as tetrabutyl titanate. Similarly, although the arc tubes utilized in the test lamps were formed from doped quartz, it should be appreciated that arc tubes embodying the present invention can also be formed from other types of vitreous silica such as synthetic silica produced from silane.
  • the ozone free quartz Prior to forming the ozone free quartz into tubes, it was vacuum baked to a low hydroxyl content indicated by a Beta OH of 0.0005 to 0.0007 nm -1 . Testing indicated that the amount of UV radiation emitted from the ozone free quartz was reduced to approximately zero at wavelengths below approximately 200 nm, with the 50% UV cut-off at approximately 240 nm. This test verifies that the use of ozone free quartz should successfully reduce the UV radiation emitted from the arc tube. As a result, the amount of photons available for ejecting electrons from materials in the outer jacket should be significantly reduced, thereby reducing sodium loss in comparison to metal halide lamps having arc tubes formed from conventional fused quartz.
  • Figs. 2(a) - 2(d) show a comparison of the results of a first test comparing the performance of the four lamps having ozone free quartz arc tubes (indicated by plots 30, 32, 34 and 36) with the four standard production lamps (indicated by plots 31, 33, 35 and 37).
  • Figs. 2(a)-2(d) are graphs of arc tube voltage, lumen output, colour temperature and colour rendering index, respectively, as a function of time.
  • the lamps having arc tubes made from ozone free quartz displayed roughly a 20% improvement in both lumen output and lumen maintenance at 6,000 hours from the standard production lamps (indicated by plot 33).
  • the improvement in lumen output and lumen maintenance indicates that lamps utilizing ozone free quartz arc tubes have a significant performance advantage over lamps with arc tubes made from conventional fused quartz.
  • Figs. 2(a) - 2(d) An analysis of Figs. 2(a) - 2(d) demonstrates that the lamps having arc tubes made from ozone free quartz not only demonstrated improved lumen output and lumen maintenance, but also did not demonstrate any significant deficiencies with regard to other lamp characteristics.
  • the lamps made with arc tubes of ozone free quartz had a higher voltage rating, their voltage reached a plateau at approximately 3,000 hours and thereafter remained steady while the voltage of the standard production lamps continued to rise in an undesirable fashion.
  • the colour rendering index (CRI) remained lower for the lamps utilizing the ozone free quartz arc tubes for the majority of the test.
  • the voltage plateau and lower colour rendering index for the lamps having ozone free quartz arc tubes is believed to be the result of a reduction in sodium loss from those arc tubes.
  • Figs. 3(a) - 3(d) are graphs showing the relative concentrations of various ion species as a function of time for the lamps having arc tubes made from ozone free quartz (indicated by plots 38, 40, 42 and 44) and the standard production lamps (indicated by plots 39, 41, 43 and 45). These graphs show no major differences in the arc species contents between the groups, although the iodine content of the ozone free group (indicated by plot 44) hit a plateau early while that of the control group (indicated by plot 45) gradually dropped.
  • the similarity of values for scandium and sodium in the two groups of lamps suggests that the higher lumen production in the group of lamps with the ozone free quartz arc tubes did not result from heating of those arc tubes.
  • Figs. 4(a) - 4(d) illustrate the results of a second lamp test which utilized double ended lamps of a nonstandard design.
  • the control group (indicated by plots 47, 49, 51 and 53) utilized standard 175W production arc tubes while the test group (indicated by plots 46, 48, 50 and 52) utilized lamps that were made at the same time and were identical except for the use of arc tubes formed from ozone free quartz.
  • Many of the lamps in both groups failed early in the test as a result of oxidation at the inleads of the outer jacket. However, those that survived showed that the lamps with the ozone free arc tubes again had higher lumen output and lumen maintenance than the lamps with the conventional quartz arc tubes.
  • Embodiments of the present invention may provide an arc discharge lamp wherein sodium loss from the arc tube is relatively low; and further may provide a metal halide discharge lamp having increased light output.

Landscapes

  • Vessels And Coating Films For Discharge Lamps (AREA)

Claims (7)

  1. Lampe à halogénures métalliques comprenant un tube à arc logé à l'intérieur d'une chemise extérieure, le tube à arc comportant une ampoule scellée (6) et un matériau de remplissage comprenant substantiellement du mercure, des additifs d'halogénures métalliques incluant un halogénure de sodium et un gaz rare,
    caractérisée en ce que
    la dite ampoule (6) du tube à arc est en silice vitreuse dopée avec entre 150 et 350 parts par million en poids d'oxyde de titane.
  2. Lampe à halogénures métalliques selon la revendication 1, dans laquelle la concentration d'oxyde de titane dans la silice vitreuse est de 250 parts environ par million en poids.
  3. Lampe à halogénures métalliques selon la revendication 1 ou 2, dans laquelle la silice vitreuse est du quartz fondu.
  4. Lampe à halogénures métalliques selon l'une quelconque des revendications 1, 2 ou 3, dans laquelle la dite lampe comprend, en outre, un ensemble de support (8, 10) du tube à arc et des moyens (28, 30, 32, etc...) pour appliquer l'énergie au dit tube à arc.
  5. Procédé de fabrication d'une lampe à halogénures métalliques selon l'une quelconque des revendications 1 à 4, caractérisé en ce que l'ampoule (6) du tube à arc est réalisée en ajoutant un composé de titane aux matériaux bruts lors d'une étape de fusion, de telle façon que la silice vitreuse dopée avec de l'oxyde de titane soit obtenue pour former la dite ampoule.
  6. Procédé selon la revendication 5, dans lequel le composé de titane est de l'oxyde de titane.
  7. Procédé selon la revendication 5, dans lequel le composé de titane forme de l'oxyde de titane lorsqu'il est chauffé.
EP19930310407 1992-12-22 1993-12-22 Lampe à arc à halogénure métallique Expired - Lifetime EP0604207B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US99560392A 1992-12-22 1992-12-22
US995603 1997-12-22

Publications (2)

Publication Number Publication Date
EP0604207A1 EP0604207A1 (fr) 1994-06-29
EP0604207B1 true EP0604207B1 (fr) 2000-06-14

Family

ID=25541994

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19930310407 Expired - Lifetime EP0604207B1 (fr) 1992-12-22 1993-12-22 Lampe à arc à halogénure métallique

Country Status (3)

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EP (1) EP0604207B1 (fr)
CA (1) CA2112063A1 (fr)
DE (1) DE69328857T2 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10224943B4 (de) * 2001-06-05 2009-04-16 Koito Mfg. Co., Ltd. Entladungskolben

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3148300A (en) * 1961-08-04 1964-09-08 Gen Electric Lamp having envelope of glass opaque to ultraviolet radiation
US3988628A (en) * 1974-06-13 1976-10-26 General Electric Company Metal halide lamp with titania-silicate barrier zone in fused silica envelope
FR2599890B1 (fr) * 1986-06-09 1990-02-02 Ushio Electric Inc Enveloppe en silice fondue pour lampe a decharge
US5196759B1 (en) * 1992-02-28 1996-09-24 Gen Electric High temperature lamps having UV absorbing quartz envelope

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10224943B4 (de) * 2001-06-05 2009-04-16 Koito Mfg. Co., Ltd. Entladungskolben

Also Published As

Publication number Publication date
DE69328857D1 (de) 2000-07-20
EP0604207A1 (fr) 1994-06-29
DE69328857T2 (de) 2001-02-22
CA2112063A1 (fr) 1994-06-23

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