WO2004105082A2 - Thorium-free electrode with improved color stability - Google Patents
Thorium-free electrode with improved color stability Download PDFInfo
- Publication number
- WO2004105082A2 WO2004105082A2 PCT/IB2004/050769 IB2004050769W WO2004105082A2 WO 2004105082 A2 WO2004105082 A2 WO 2004105082A2 IB 2004050769 W IB2004050769 W IB 2004050769W WO 2004105082 A2 WO2004105082 A2 WO 2004105082A2
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- electrode
- thorium
- covering member
- electrode rod
- tip
- Prior art date
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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
- H01J61/04—Electrodes; Screens; Shields
- H01J61/06—Main electrodes
- H01J61/073—Main electrodes for high-pressure discharge lamps
- H01J61/0732—Main electrodes for high-pressure discharge lamps characterised by the construction of the electrode
-
- 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
- H01J61/073—Main electrodes for high-pressure discharge lamps
- H01J61/0735—Main electrodes for high-pressure discharge lamps characterised by the material of the electrode
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J61/00—Gas-discharge or vapour-discharge lamps
- H01J61/84—Lamps with discharge constricted by high pressure
- H01J61/86—Lamps with discharge constricted by high pressure with discharge additionally constricted by close spacing of electrodes, e.g. for optical projection
Definitions
- the present invention relates to an electrode comprising thorium as a minor component, a high pressure discharge lamp comprising said electrodes and a method of manufacturing therefore.
- Electrodes commercially used for HID lamps include a thoriated tungsten electrode having the form of a coil. Various attempts have been made to improve the electrode design but there is still the need of further improvements.
- EP-Al 1 148 534 discloses a high pressure mercury discharge lamp which achieves a long life of at least 3000 hours and in which variations in lamp characteristics are suppressed.
- This high-pressure discharge lamp comprises an electrode having a coil shape and being made of refractory metal.
- the refractory metal is applied on a discharge side tip of the electrode rod so as to cover a circumference of the electrode rod in a vicinity of the discharge side tip.
- the discharge side tip on which the covering member is applied is welded into a semi-sphere by intermittently heat fusing the discharge side tip according, for instance, to arc discharge or laser irradiation.
- the coil shape covering member is not laser melted on the electrode rod in such a manner that practically no visible internal cavities or unmelted ranges remains at least between the electrode rod and the coil since the coil is partially connected only on the electrode rod as well as the individual windings of the coil are not melted split-free to each.
- the electrode of EP-Al 1 148 534 posses an inferior heat conductivity as well as an increased danger of back burning or melt back of said electrode which leads for example to an increased release of thorium.
- GB-A 2 031 645 discloses an electrode without alkaline earth electron- emissive material for a miniature high pressure metal halide mercury lamp having a volume not exceeding 1 cc and a discharge current not exceeding 1 ampere comprises a slender tungsten shank with a few secondary turns of mandrel-less coiled-coil overwind thereon and preferably a balled distal end.
- the shank diameter is chosen in the range of 5 to 15 mils and above the size where melt-back starts at the intended lamp current, and the overwind is made of primary wire not exceeding 3 mils originally wound on a primary mandrel of 3 to 7 mils, subsequently removed.
- the coil shape covering member is not laser melted on the electrode rod in such a manner that practically no visible internal cavities or unmelted ranges remains since the coil is partially connected only on the electrode rod. Rather the individual windings of the coil are not melted split-free to each.
- the electrode of GB-A 2 031 645 posses an inferior heat conductivity as well as an increased danger of back burning or melt back of said electrode which leads for example to an increased release of thorium.
- the thermal stress both during run up and steady state operation conditions of a high pressure mercury-free xenon discharge lamp is increased compared to high pressure mercury containing discharge lamps.
- Tungsten and/or rhenium which forms the electrode melts and disperses, the electrode tip becomes deformed and wears due to the temperature of the electrode tip increasing excessively, while the dispersed tungsten and/or rhenium is deposited on the inner surface of the light-emitting tube, causing blackening. This blackening of the inner surface of the light-emitting tube causes premature degradation of light flux.
- the thermal stress electrode rods comprising thorium as a minor component for example with a thickness of 250 ⁇ m have the drawback of an increased electrode back burning or melt back which leads to accelerate crystallisation and to inferior light flux [lumen] maintenance, colour stability and dramatically reduced life time.
- the use of electrode rods comprising thorium as a minor component with an increased thickness to easily withstands the thermal stress have the drawback due to the higher thermal load of such an electrode that the discharge bulb becomes cracks at the position where the electrode is gas tight sealed with the discharge bulb.
- the object of the present invention is to avoid the disadvantages mentioned above and to provide a tungsten and/or rhenium electrode comprising as a minor amount thorium or is free of thorium, a high pressure discharge lamp and a manufacturing method therefore which achieves desirably a life of at least 1500hrs, whereby the high pressure discharge lamp exhibits in particular an improved light flux [lumen] maintenance, reduced scandium loss, improved colour stability, reduced crystallisation as well as a diminished back burning or melt back of the electrodes.
- the above-described objective can be achieved by at least one electrode for a high pressure discharge lamp, whereby the electrode and/or the electrode tip is free of thorium, preferably thorium oxide, or comprises thorium, preferably thorium oxide, as a minor constituent, characterized in that the lamp has a color shift of ⁇ X (difference colour point to 15hrs) at 500 hrs.
- ⁇ X difference colour point to 15hrs
- preferably of ⁇
- preferably of ⁇
- preferably of ⁇
- preferably of ⁇
- preferably of ⁇
- preferably of ⁇
- preferably of ⁇
- the above-described objective can be furthermore achieved by at least on electrode for a high pressure discharge lamp, at least one electrode rod being made of a refractory metal material as a main constituent, whereby
- the electrode rod is free of thorium, preferably thorium oxide, or comprises thorium, preferably thorium oxide, as a minor constituent,
- a covering member made of refractory metal, free of thorium, preferably thorium oxide, is circumference coated on said electrode rod in a vicinity of the discharge side tip, whereby the entire surface of the electrode rod is completely coated over the range the covering member extends,
- the electrode rod tip of said electrode rod is not or at least partly coated with said covering member
- the electrode tip is formed into a ball like shape or semi-sphere electrode tip, whereby the covering member is circumference split free joint with said formed electrode tip.
- This above-described lamp has preferably also a color shift of ⁇ X (difference colour point to 15hrs) at 500 hrs. of ⁇
- preferably of ⁇ I 8 I , more preferably of ⁇ I 5 I , more preferably of ⁇ I 3 I , and most preferred of ⁇ 1 1 1 , and/ or a color shift of ⁇ Y (difference colour point to 15hrs) at 500 hrs. of ⁇
- preferably of
- preferably of ⁇
- preferably of ⁇
- preferably of ⁇
- preferably of ⁇
- preferably of ⁇
- preferably of ⁇
- the covering member is preferably heated up, e.g. thermally heated, and then heat coated on the electrode rod.
- the covering member is heated up to its softening point or melted and then coated on the electrode rod. More preferred, the covering member is coated by means of laser melting on the electrode rod.
- the electrode tip is preferably heat formed, into a ball like shape or semi- sphere electrode tip, whereby electrode tip is preferably heated up to its softening point or melted and then formed. More preferred the electrode tip is formed by means of laser melting into a ball like shape or semi-sphere.
- the thermal load of the covering member and/or the electrode tip during the heat step should be adjusted high enough so that all or mostly all of the thorium contained in the covering member and/or the electrode tip can be thermally removed.
- the electrode rod comprises as main component tungsten and/or rhenium, most preferred a tungsten rod free of thorium, preferably thorium oxide, which is doped with potassium (K), silicium (Si) and/or aluminum (Al) .
- K potassium
- Si silicium
- Al aluminum
- the covering member can be made of a refractory metal selected from the group comprising tungsten, tungsten doped with potassium (K), silicium (Si) and/or aluminum (Al), rhenium and or rhenium doped with potassium (K) ), silicium (Si) and/or aluminum (Al).
- a refractory metal selected from the group comprising tungsten, tungsten doped with potassium (K), silicium (Si) and/or aluminum (Al), rhenium and or rhenium doped with potassium (K) ), silicium (Si) and/or aluminum (Al).
- an electrode can be manufactured whereby the electrode tip of an electrode rod free of thorium or comprising thorium as a minor amount, such as ThO , is formed by means of laser-melt into a ball like shape or semi-sphere electrode tip, whereby the ball like shape or semi-sphere electrode tip becomes free of thorium.
- the electrode rod is by means of laser melting circulating coated with the covering member.
- the covering member can be laser melted circumference on a discharge side tip of said electrode rod in a vicinity of the discharge side tip before or during the electrode tip is formed by means of laser-melt to a ball like shape or semi- sphere electrode tip.
- an electrode can be manufactured whereby the covering member is laser melted circumference on a discharge side tip of an electrode rod free of thorium or comprises thorium as a minor constituent in a vicinity of the discharge side tip without that the electrode tip is laser-melt to a ball like shape or semi-sphere electrode tip.
- the electrode tip is at least partly covered by the laser melted covering member, if the electrode rod tip is thorium free. More preferably the electrode rod tip is completely covered by the laser melted covering member.
- thorium as used in the present invention comprises thorium oxide such as ThO 2 .
- thorium free means that neither thorium as element or as composition, such as thorium oxide, is contained. However, it is possible that at most traces of thorium close at the detection limit are contained. It is a further primary object of the present invention to prevent that ScJ3 of the filling will be reduced by reaction with compounds of thorium. By doing so, the colour shift of the lamp can be reduced significantly.
- the electrode of the present invention comprises an electrode rod with an electrode tip and a covering member, whereby the covering member surrounds the electrode rod to avoid back burning or melt back.
- the electrode rod with electrode tip used for the production of the electrode of the present invention comprises preferably thoriated tungsten and/or rhenium. It is also possible that the electrode rod comprises tungsten free of thorium and/or doped tungsten, whereby the tungsten can be doped with potassium (K), silicium (Si) and/or aluminum (Al).
- the electrode rod can comprise > 0 ppm to 5 ppm thorium, preferably ⁇ 1 ppm, more preferably ⁇ 0,1 ppm.
- Table II shows the colour shifts of several lamps, including lamps according to the present invention, using electrode rods with and without ThO 2 .
- the laser melted electrode tip of the invention comprises preferably 0 ppm thorium, such as thorium oxide, or at most traces of thorium.
- the range of the electrode where the electrode rod is coated with said covering member is free of thorium up to a layer depth of 10 ⁇ m to 150 ⁇ m, preferably up to a layer depth of 20 ⁇ m to 130 ⁇ m, more preferably up to a layer depth of 30 ⁇ m to 120 ⁇ m and most preferably up to a layer depth of 40 ⁇ m to 110 ⁇ m.
- the thorium free layer depth can be of 50 ⁇ m to 250 ⁇ m, preferably up to a layer depth of 60 ⁇ m to 225 ⁇ m, more preferably up to a layer depth of 70 ⁇ m to 200 ⁇ m and most preferably up to a layer depth of 80 ⁇ m to 170 ⁇ m.
- the layer depth is measured from the upper outer surfaces of the coated electrode range to the electrode axis in a range of 50 ⁇ m to 500 ⁇ m extending from the electrode tip along the coated electrode rod range.
- ThO 2 The release of ThO 2 leads to a decrease of scandium (Sc) and the sodium (Na) pressure of the ionizable filling.
- Sc scandium
- Na sodium
- a method for manufacturing an electrode comprising the steps: a) forming an electrode tip of an electrode rod comprising thorium as a minor amount, such as ThO 2 , by means of laser-melt to a ball like shape or semi-sphere electrode tip, whereby the ball like shape or semi-sphere electrode tip becomes free of thorium; b) contacting a covering member made of refractory metal and free of thorium (Th) by means of laser melting circumference at said ball like shape or semi- sphere electrode tip, whereby the laser melted covering member contacts completely split-free the ball like shape or semi-sphere electrode tip so that practically no visible internal cavities or unmelted areas remains; and c) coating said covering member by means of laser melting along its entire length circumference on said electrode rod so that practically no visible internal cavities or unmelted areas between the laser melted covering member and said electrode rod remains.
- thorium a minor amount, such as ThO 2
- an electrode it is suggested that: a) forming an electrode tip of an electrode rod free of thorium by means of laser-melt to a ball like shape or semi-sphere electrode tip; b) contacting a covering member made of refractory metal and free of thorium (Th) by means of laser melting circumference at said ball like shape or semi- sphere electrode tip, whereby the laser melted covering member contacts completely split-free the ball like shape or semi-sphere electrode tip so that practically no visible internal cavities or unmelted areas remains; and c) coating said covering member by means of laser melting along its entire length circumference on said electrode rod so that practically no visible internal cavities or unmelted areas between the laser melted covering member and said electrode rod remains.
- an electrode it is suggested that: a) placing a covering member made of refractory metal free of thorium (Th) on a thorium free electrode rod up to the electrode rod tip; b) coating said covering member by means of laser melting along its entire length circumference on said electrode rod so that practically no visible internal cavities or unmelted areas between the laser melted covering member and said electrode rod remains.
- Th thorium
- the electrode rod can be rotated; and/or - the laser can be rotated around the electrode.
- the covering member is a coil which is circumference completely coated along its entire length by means of laser melt in a vicinity of the discharge side tip on the electrode rod so that the completely melted covering member shows practically no gaps, has a smooth upper surface and practically no internal cavities or unmelted areas.
- the smooth upper surface can have a wave like form.
- the covering member such as a coil
- the covering member is laser melted to a preferably homogeneous coating mass, whereby the original form of the covering member is lost completely.
- An electrode rod which can be used in the present invention comprises preferably as a main component tungsten and/or rhenium and as a minor component thorium, such as thoriumoxid (Th0 2 ).
- a minor component thorium such as thoriumoxid (Th0 2 ).
- an electrode rod comprising: - tungsten and being free of thorium; or - potassium (K), silicium (Si) and/or aluminum (Al) doped tungsten free of thorium can be used according to the present invention, whereby potassium doped tungsten free of thorium is most preferred.
- the electrode rod based on the total weight of the electrode rod, can contain 0 weight-% to 5 weight-% thorium, preferably > 0 weight-% to ⁇ 2 weight-% thorium and more preferably > 0,001 weight-% to ⁇ 1 weight-% thorium. Further, the electrode rod can comprise accessory constituents selected from the group of Al, Ca, Cr, Cu, Fe, Mg, Mn, Ni, Si, Sn, Na, K, Mo and/or U.
- the electrode rod is doped with potassium (K), silicium (Si) and/or aluminium (Al), whereby the potassium content of said electrode rod, based on the total weight of the electrode rod, is of >0 ppm to ⁇ 500 ppm, preferably of >50 ppm to ⁇ 100 ppm.
- the Silicium content of said electrode rod, based on the total weight of the electrode rod can be of >0 ppm to ⁇ 300 ppm and preferably of >50 ppm to ⁇ 100 ppm.
- the Aluminum content of said electrode rod, based on the total weight of the electrode rod can be of >0 ppm to ⁇ 100 ppm and preferably of >10 ppm to 50 ppm.
- the electrode rod is covered by a covering member made of refractory metal free of thorium (Th), whereby the covering member is selected from the group comprising a coil, a tube, a tube with two openings at each end part or a tube with one closed end part and/or rings, whereby a wire coil is most preferred.
- Th refractory metal free of thorium
- the range of the electrode rod coated with the laser melted covering member forms the electrode head.
- the range of the electrode rod which forms the electrode head can comprise thoriated tungsten if the electrode tip is free of thorium.
- the tungsten can be doped with potassium (K), silicium (Si) and/or aluminum (Al), whereby potassium is preferred.
- the diameter of the electrode head can be of 250 ⁇ m to 550 ⁇ m, preferably 300 ⁇ m to 500 ⁇ m and more preferably 350 ⁇ m to 450 ⁇ m.
- the so covered electrode rod Due to the laser melt covering member the so covered electrode rod is up to a certain layer depth ThO 2 -free, whereby in the electrode core ThO 2 can still be present, if an thoriated tungsten electrode is used. Consequently, back burning or melt back of the so coated electrode prevents or reduces strongly a release of torium, such as ThO 2 .
- the electrode is still sufficiently warmed up in order to achieve a stable electric discharge.
- the electrode design according to the present invention reduces strongly back burning or melt back of the electrode over lifetime, thus an electrode deformation is prevented or reduced strongly which increases arc stability over lifetime.
- an arc instability can be prevented or an occurrence of an arc instability is very strongly shifted to the end of the lifetime of said high pressure discharge lamp.
- the length of the electrode can be dimensioned in such a way that the electrode range which is gas tight joint with or sandwiched between the discharge bulb is 150 ⁇ m to 400 ⁇ m, preferably 200 ⁇ m to 350 ⁇ m and more preferably 250 ⁇ m to 320 ⁇ m.
- a part of the electrode range coated with the covering member can be gas tight joint with the discharge bulb.
- the discharge bulb of the discharge lamp of the present invention is preferrably based of quarz glas or ceramic,
- Tungsten possesses a higher heat conductivity compared with rhenium. For low temperatures ( ⁇ 500°C) it is about 2.9 times higher compared with rhenium and approximatly 2.6 times higher compared with tungsten rhenium alloy (75%/25%).
- each electrode having a diameter of 150 ⁇ m to 400 ⁇ m, more preferred of 200 ⁇ m to 350 ⁇ m and most preferred of 250 ⁇ m to 320 ⁇ m.
- the distance of the electrode rod which is not coated by a covering member up to the position where the electrode is joint or sandwiched with the inner dischare bulb of the burner can be of 0 ⁇ m to 5000 ⁇ m, preferably 10 ⁇ m to 3000 ⁇ m, more preferably 50 ⁇ m to 2000 ⁇ m and most preferably 60 ⁇ m to 1500 ⁇ m.
- the covering member is laser melted circumference on the electrode rod in a vicinity of the discharge side tip. It is important that the covering member is laser melted on the electrode rod such that practically no remaining defects such as internal cavities or unmelted areas are obtained.
- the covering member used is a coil after it is laser melted, the coil rings have been melted together so that an upper smooth surface is obtained and between the coated electrode and the laser melted coil practically no internal cavities or unmelted areas remain.
- the upper surface of the laser melted covering member can have a wavy surface.
- the electrode head i.e. the electrode range of the electrode rod coated with the laser melted covering member
- the electrode range of the electrode rod coated with the laser melted covering member can have a thickness of at least 250 ⁇ m to about 550 ⁇ m, preferably of between 300 ⁇ m to 500 ⁇ m and more preferably of between 350 ⁇ m to 450 ⁇ m. It is preferred that the melted covering member extends parallel along the electrode up to the electrode tip, whereby the electrode tip is not or at least partly or completely coated with the melted covering member.
- the laser melted covering member or electrode head has a lengthen of at least 300 ⁇ m to about 1500 ⁇ m, preferably of between 500 ⁇ m to 1300 ⁇ m and more preferably of between 800 ⁇ m to 1100 ⁇ m.
- thorium free electrode tip has a ball like or semi-sphere form
- such an electrode tip can have a lengthen of at least 250 ⁇ m to about 550 ⁇ m, preferably of between 300 ⁇ m to 500 ⁇ m and more preferably of between 350 ⁇ m to 450 ⁇ m.
- Another object of the present invention concerns a high pressure discharge lamp comprising a sealed discharge bulb containing an ionisable filling including an inert starting gas and according to the present invention two electrodes in opposition.
- the distance between the two opposed electrode tips is of at least 2,0 mm to about 5,0 mm, preferably of between 3,0 mm to 4,5 mm and more preferably of between 3,5 mm to 4,0 mm.
- the high pressure discharge lamp is most preferably a high pressure mercury-free discharge lamp and said inert starting gas is preferably xenon.
- a gas tight sealed discharge bulb of a high pressure discharge lamp of the present invention has - an inner diameter in the range of 2,0 mm to 3,0 mm, and/or, - an inner volume in the range of 15 ⁇ l to 40 ⁇ l, and/or, - a filling pressure at room temperature in the range of 5 bar to 20 bar.
- the discharge bulb preferably can have any suitable form.
- the inner contour of the discharge bulb can be cylindrically, elliptically or asymmetrically.
- the ionisable filling of the burner inside the discharge bulb comprises at least one of the components selected from the group of Scl 3 , Nal, InJ, ZnJ2, T1J, ThJ 4) AlBr3, InBr, HfBr4, A1J3, MgJ2, CeJ3, CsJ and/or DyI3.
- the ionisable filling does not contain mercury.
- the mercury-free ionisable filling based on the total weight of the ionisable filling, comprises the following components: - 0 -4 weight.-% ThJ ,
- the components of the ionisable filling are selected such that the total amount does not exceed 100 weight-%.
- the mercury- free ionisable filling based on the total weight of the ionisable filling, comprises at least: - 0 - 4 weight-% ThJ 4 ,
- a high pressure discharge lamp according to the present invention in particular a high pressure mercury-free xenon discharge lamp, can have
- Fig. 1 shows an example of an electrode for a high pressure discharge lamp with a coil surrounding said electrode rod in a vicinity of the discharge side tip;
- Fig. 2 shows and example of an electrode of the present invention after a coil is laser melted circumference of the electrode rod in a vicinity of the discharge side tip;
- Fig. 3 shows a partially cut away view showing the structure of a gas tight sealed discharge bulb with two opposing electrodes according to the present invention whereby the electrode tip of said electrode rod is not covered by a covering member.
- Fig. 4 shows an electrode design of the present invention
- Fig. 5 is a drawing showing variations in light flux [lumen] maintaining rate over life time of high pressure discharge lamps of the present invention.
- Fig. 1 shows an electrode rod (1) for a high pressure discharge lamp with a coil (2) surrounding said electrode rod (1) in a vicinity of the discharge side tip (3). As shown in Fig. 1, the coil (2) does not extend over the electrode tip (3) of said electrode rod (1).
- Fig. 2 shows the electrode (4) of fig.1 for a high pressure discharge lamp with a laser melted coil (5) surrounding said electrode rod (1) in a vicinity of the discharge side tip (3).
- the coil member rings (2) has been melted together (5) so that an upper surface is obtained having practically no visible internal cavities.
- the laser melted coil (5) becomes an uniform melted form having practically no unmelted areas.
- the upper surface of the melted covering member (5) has a smooth upper surface.
- Fig. 3 is a partially cut away view showing the structure of a gas tight sealed discharge bulb (6) with to opposing electrodes (4) of the present invention.
- the electrode tip (3) of said electrode rod (1) is not covered by a covering member (5) but formed by means of laser melting to a ball like shape (3). Further, Fig. 3 shows that the electrode rod (1) is not fully covered parallel along the electrode axis (7) up to the inner discharge bulb surface (8).
- Fig. 4 shows an example of a preferred electrode design of the present invention.
- the electrode rod has a total lengths of 6 mm, an electrode rod diameter of 300 ⁇ m.
- the shaft diameter of the coated electrode rod with laser melted covering member is 390 ⁇ m and the lengths of the laser melted covering member is 1.1 mm.
- Fig. 5 showing variations in light flux [lumen] maintaining rate over life time of high pressure mercury-free xenon discharge lamps of the present invention compared to the same high pressure discharge lamps with thoriated tungsten electrode, except that the electrode is not coated by a covering member.
- the thorium free electrode tip is obtained for example by laser melting the thorium free covering member on the electrode rod.
- the thermal load of the electrode tip during the laser melting step is high enough so that all or mostly all of the thorium contained in the electrode tip can be thermally removed.
- Lamps of the present invention can be preferably used in the field of automotive such as head lamps.
- a high pressure mercury-free xenon discharge lamp is provided with a discharge bulb, two electrodes placed so as to be in opposition with a distance of 3,7 mm between the two electrodes.
- the electrode rod of thoriated tungsten 1 wt.-% ThO 2 has a total lengths of 6 mm, an electrode rod diameter of 300 ⁇ m.
- the shaft diameter of the coated electrode rod with laser melted covering member is 390 ⁇ m and the lengths of the laser melted covering member is 1,1 mm.
- the electrode range coated with the covering member extends inside the burner and is not joint or sandwiched with the discharge bulb.
- the volume of the discharge bulb of the discharge lamp is 22 ⁇ l and the inner gas pressure at room temperature is 9,5 bar.
- the electrode is coated with a laser melted coil.
- the coil is made of tungsten doped with potassium and free of thorium.
- the laser melted coil has a melted form with a smooth upper surface whereby the melted coil has practically no unmelted areas.
- the electrode head which is formed of the electrode rod range witch is coated with the melted coil (electrode head) has a diameter of 390 ⁇ m and a lengths of 1,1 mm.
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Abstract
Description
Claims
Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2006530894A JP2007515750A (en) | 2003-05-26 | 2004-05-25 | Thorium-free electrode for improved color stability |
EP04734718A EP1649492A2 (en) | 2003-05-26 | 2004-05-25 | Thorium-free electrode with improved color stability |
CN2004800143739A CN101292324B (en) | 2003-05-26 | 2004-05-25 | Thorium-free electrode with improved color stability |
US10/557,685 US7808180B2 (en) | 2003-05-26 | 2004-05-25 | Thorium-free electrode with improved color stability |
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP03101517 | 2003-05-26 | ||
EP03101517.5 | 2003-05-26 | ||
EP03103831 | 2003-10-16 | ||
EP03103831.8 | 2003-10-16 |
Publications (2)
Publication Number | Publication Date |
---|---|
WO2004105082A2 true WO2004105082A2 (en) | 2004-12-02 |
WO2004105082A3 WO2004105082A3 (en) | 2008-01-17 |
Family
ID=33477639
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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PCT/IB2004/050769 WO2004105082A2 (en) | 2003-05-26 | 2004-05-25 | Thorium-free electrode with improved color stability |
Country Status (5)
Country | Link |
---|---|
US (1) | US7808180B2 (en) |
EP (1) | EP1649492A2 (en) |
JP (2) | JP2007515750A (en) |
CN (1) | CN101292324B (en) |
WO (1) | WO2004105082A2 (en) |
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WO2008122912A2 (en) * | 2007-04-05 | 2008-10-16 | Philips Intellectual Property & Standards Gmbh | Mercury-free high intensity gas-discharge lamp |
DE102008026521A1 (en) | 2008-06-03 | 2009-12-10 | Osram Gesellschaft mit beschränkter Haftung | Thorium-free high-pressure discharge lamp for high-frequency operation |
US7808180B2 (en) | 2003-05-26 | 2010-10-05 | Koninklijke Philips Electronics N.V. | Thorium-free electrode with improved color stability |
WO2010128452A1 (en) * | 2009-05-07 | 2010-11-11 | Koninklijke Philips Electronics N.V. | Mercury-free high-intensity gas-discharge lamp |
US7982377B2 (en) * | 2004-10-20 | 2011-07-19 | Koninklijke Philips Electronics N.V. | High-pressure gas discharge lamp |
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US7652415B2 (en) * | 2005-10-20 | 2010-01-26 | General Electric Company | Electrode materials for electric lamps and methods of manufacture thereof |
CN101855702A (en) * | 2007-09-24 | 2010-10-06 | 皇家飞利浦电子股份有限公司 | Thorium-free discharge lamp |
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JP2010049983A (en) * | 2008-08-22 | 2010-03-04 | Harison Toshiba Lighting Corp | Metal halide lamp and headlight for automobile |
DE112008003969B4 (en) * | 2008-09-05 | 2017-11-09 | Osram Gmbh | Electrode for a discharge lamp, corresponding manufacturing method and corresponding discharge lamp |
WO2010029487A2 (en) | 2008-09-10 | 2010-03-18 | Philips Intellectual Property & Standards Gmbh | Discharge lamp with improved discharge vessel |
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- 2004-05-25 WO PCT/IB2004/050769 patent/WO2004105082A2/en active Application Filing
- 2004-05-25 JP JP2006530894A patent/JP2007515750A/en not_active Withdrawn
- 2004-05-25 EP EP04734718A patent/EP1649492A2/en not_active Withdrawn
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Publication number | Priority date | Publication date | Assignee | Title |
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US7808180B2 (en) | 2003-05-26 | 2010-10-05 | Koninklijke Philips Electronics N.V. | Thorium-free electrode with improved color stability |
US7982377B2 (en) * | 2004-10-20 | 2011-07-19 | Koninklijke Philips Electronics N.V. | High-pressure gas discharge lamp |
WO2008122912A2 (en) * | 2007-04-05 | 2008-10-16 | Philips Intellectual Property & Standards Gmbh | Mercury-free high intensity gas-discharge lamp |
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Also Published As
Publication number | Publication date |
---|---|
CN101292324A (en) | 2008-10-22 |
CN101292324B (en) | 2012-11-14 |
EP1649492A2 (en) | 2006-04-26 |
US20070182332A1 (en) | 2007-08-09 |
JP2010140916A (en) | 2010-06-24 |
JP2007515750A (en) | 2007-06-14 |
WO2004105082A3 (en) | 2008-01-17 |
US7808180B2 (en) | 2010-10-05 |
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