EP0700579B1 - High-pressure discharge lamp and process for producing it - Google Patents

High-pressure discharge lamp and process for producing it Download PDF

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Publication number
EP0700579B1
EP0700579B1 EP94916137A EP94916137A EP0700579B1 EP 0700579 B1 EP0700579 B1 EP 0700579B1 EP 94916137 A EP94916137 A EP 94916137A EP 94916137 A EP94916137 A EP 94916137A EP 0700579 B1 EP0700579 B1 EP 0700579B1
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EP
European Patent Office
Prior art keywords
outer bulb
quartz glass
discharge vessel
discharge lamp
pressure discharge
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EP94916137A
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German (de)
French (fr)
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EP0700579A1 (en
Inventor
Christian Wittig
Dieter Lang
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Osram GmbH
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Patent Treuhand Gesellschaft fuer Elektrische Gluehlampen mbH
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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
    • H01J61/34—Double-wall vessels or containers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J9/00—Apparatus or processes specially adapted for the manufacture, installation, removal, maintenance of electric discharge tubes, discharge lamps, or parts thereof; Recovery of material from discharge tubes or lamps
    • H01J9/24—Manufacture or joining of vessels, leading-in conductors or bases
    • H01J9/26—Sealing together parts of vessels
    • H01J9/265—Sealing together parts of vessels specially adapted for gas-discharge tubes or lamps
    • H01J9/266—Sealing together parts of vessels specially adapted for gas-discharge tubes or lamps specially adapted for gas-discharge lamps

Definitions

  • the invention relates to a high-pressure discharge lamp according to the preamble of claim 1 and a method for producing a high-pressure discharge lamp.
  • it is a high-pressure discharge lamp that is used for an optical imaging system, such as is suitable for a motor vehicle headlight.
  • EP-A 0 570 068 discloses such a lamp, which corresponds to the preamble of patent claim 1. It serves as a light source for a motor vehicle headlight.
  • This high-pressure discharge lamp has a discharge vessel made of quartz glass which is sealed on two sides and sealed by means of melted-in molybdenum, with two axially aligned electrodes which are each melted into one end of the discharge vessel.
  • An outer bulb made of quartz glass surrounds the discharge vessel.
  • FIG. 3 of this laid-open document shows a high-pressure discharge lamp with an essentially rotationally symmetrical outer bulb which is arranged coaxially with the discharge vessel and is fused to the sealed ends of the discharge vessel outside the molybdenum melting films.
  • EP-A 0 465 083 also describes a high-pressure discharge lamp falling under the preamble of patent claim 1.
  • This high-pressure discharge lamp has a discharge vessel made of quartz glass which is sealed on two sides and sealed by means of melted-in molybdenum, with two axially aligned electrodes which are each melted into one end of the discharge vessel.
  • Outside of the melted down Molybdenum foils each have a plate-like thickening with which an outer bulb made of quartz glass and surrounding the discharge vessel is fused in a gas-tight manner.
  • This type of outer bulb fixation on the discharge vessel by means of the plate-like thickenings is comparatively complex.
  • these plate-like thickenings must also be at a sufficient distance from the melted-in molybdenum foils in order not to endanger the sealing of the discharge vessel.
  • the patent US Pat. No. 5,196,759 discloses a high-pressure discharge lamp which is equipped with a tubular discharge vessel and a tubular outer bulb.
  • the outer bulb consists of quartz glass doped with additives that absorb ultraviolet rays. It surrounds the discharge vessel without contact. The ends of the outer bulb are sealed by means of melted-down molybdenum foil via the current leads protruding from the discharge vessel.
  • the Canadian laid-open specification CA 2,026,850 describes a high-pressure discharge lamp provided with an outer bulb, the discharge vessel of which is arranged obliquely to the longitudinal axis or outside the longitudinal axis of the outer bulb, in order to ensure an optimum light output as a function of the position of the discharge vessel and of the reflector type.
  • the high-pressure discharge lamps according to the invention are equipped with an outer bulb, the glass of which has a lower viscosity and thus a has a lower softening temperature than the quartz glass of the discharge vessel.
  • an outer bulb the glass of which has a lower viscosity and thus a has a lower softening temperature than the quartz glass of the discharge vessel.
  • the outer bulb is made of a so-called soft quartz glass provided with viscosity-reducing additives, while the thermally more highly stressed discharge vessel consists of undoped quartz glass.
  • Soft quartz glasses Compared to pure, undoped quartz glass (silica content of approx. 99.99 mole percent), they have a softening range at significantly lower temperatures and are therefore easier and more energy-efficient to process than pure quartz glass. Examples of such soft quartz glasses, which can advantageously be used as outer bulb glass, are disclosed in EP-A-0 601 391 (Art. 54 (3)). Alkaline earth metal borates in quartz glass are primarily used as viscosity-reducing dopants.
  • the outer bulb glass also contains additives of rare earth metal compounds which reduce the transparency of the outer bulb glass in the ultraviolet spectral range in order to reduce the UV emission of the high-pressure discharge lamp. Since these rare earth metal compounds absorbing UV rays themselves reduce the viscosity of the outer bulb glass, a sufficient amount of rare earth metal compounds in the outer bulb glass, ie with a weight fraction of these rare earth metal compounds of more than approx. 5 percent by weight, possibly the initially mentioned viscosity-reducing alkaline earth metal borates can be dispensed with.
  • the simple outer bulb attachment to the discharge vessel has a particularly advantageous effect in the case of high-pressure discharge lamps used in motor vehicle headlights, because no additional holder or frame parts are necessary here, which can lead to impairment of the light emission.
  • High-pressure discharge lamps used in motor vehicle headlights are usually in a horizontal position, i. that is, operated with a horizontally extending discharge path, so that the discharge arc experiences a convection-related sickle-like upward curvature in the earth's gravitational field.
  • the axis of symmetry of the essentially rotationally symmetrical outer bulb of the high-pressure discharge lamp according to the invention is arranged parallel to the connecting path of the discharge-side electrode ends.
  • the amount of the parallel shift corresponds approximately to the mean deflection of the discharge arc from the fictitious connecting section of the electrode ends. In this way it is ensured that the outer bulb wall does not produce mirror images of the curved discharge arc, which would cause disturbing reflections in the reflector and would lead to loss of light.
  • the outer bulb axis advantageously runs through the brightness center or maximum of the discharge arc, which is used for the imaging system.
  • the deflection of the discharge arc from the discharge path, that is the connecting path between the discharge-side ends of the electrodes about 0.3 mm to 1.0 mm.
  • the eccentric position of the outer bulb with respect to the connecting section of the discharge-side electrode ends or with respect to the discharge vessel axis - usually the electrodes run in the discharge vessel axis - can be ensured relatively simply by fixing the outer bulb and discharge vessel in eccentrically arranged chucks of a glass lathe when the outer bulb melts.
  • FIG. 1a the two electrodes 3 are arranged horizontally and lie in the axis AA of the outer bulb 1.
  • the ends of the electrodes 3 which face one another on the discharge side define a discharge path lying in the outer bulb axis AA.
  • a discharge arc 4 which is curved upward due to convection is formed between the ends of the electrodes 3 on the discharge side.
  • the outer bulb wall generates a real mirror image 4a of the discharge arc 4 below the axis AA, which leads to light losses and disturbing reflections when such a lamp is used in an imaging system.
  • FIG. 1b shows the arrangement of outer bulb 1 and electrodes 3 in a high-pressure discharge lamp according to the invention.
  • the electrodes 3 are arranged eccentrically in the outer bulb 1, so that the discharge path runs parallel to the outer bulb axis A-A, but does not coincide with it.
  • the distance of the electrodes or the discharge path to the outer bulb axis is chosen so that the outer bulb axis A-A runs through the center of brightness or maximum brightness of the discharge arc and the real mirror image 4a is largely coincident with the discharge arc 4.
  • the brightness center or maximum of the discharge arc 4 coincides with its mirror image.
  • the brightness center or maximum is the location on the center perpendicular between the two discharge-side electrode ends that has the highest luminance in the discharge arc 4.
  • FIG. 1 A high-pressure discharge lamp according to the invention is shown in FIG.
  • This exemplary embodiment is a metal halide lamp with a base on one side and an electrical power consumption of approximately 35 watts, which is preferably used in motor vehicle headlights.
  • This lamp has an essentially axially symmetrical, two-sided sealed discharge vessel 2, which is surrounded by an essentially rotationally symmetrical outer bulb 1.
  • the discharge vessel 2 has a discharge space with an ionizable filling enclosed in a gas-tight manner therein, as well as two opposing squeezing ends 5a, 5b, in each of which an axially arranged electrode 3 projecting into the discharge space is melted.
  • Both electrodes 3 are each electrically conductively connected to a power supply 7a, 7b via a molybdenum foil melt 6.
  • the outer bulb 1 is fastened directly on the pinch seals 5a, 5b of the discharge vessel 2, in the immediate vicinity of the end of the molybdenum foils 6 facing away from the discharge space. It consists of 1.0 percent by weight barium metaborate (BaB 2 O 4 ), 0.5 Weight percent ceraluminate (CeAlO 3 ), 0.5 weight percent praseodymium oxide (Pr 6 O 11 ) and 0.05 weight percent titanium oxide (TiO 2 ) doped quartz glass.
  • the discharge vessel 2 is made of undoped quartz glass and is fixed in the lamp base 9 by means of a tubular extension 8a of the pinch end 5a.
  • the power supply 7a close to the base runs inside the tubular extension 8a and makes electrical contact with one of the two connection cables 10, while the power supply 7b remote from the base is electrically conductively connected to the other connection cable 10 via a return 11, which has ceramic insulation.
  • This lamp is operated in a horizontal position, i.e. with a horizontal discharge path.
  • the lamp is oriented so that the return 11 runs below the outer bulb 1 (Fig. 2).
  • the outer bulb 1 is arranged eccentrically with respect to the discharge vessel 2 and with respect to the discharge path, which is defined by electrode ends on the discharge side.
  • the outer bulb axis A-A runs approx. 0.65 mm above and parallel to the discharge vessel axis and to the discharge path.
  • the distance between the outer bulb axis A-A and the discharge path or the discharge vessel axis B-B is exaggerated for clarity.
  • FIGS. 3a and 3b illustrate the production method of a high-pressure discharge lamp according to the invention, in particular the assembly of the outer bulb 1.
  • a completely prefabricated, essentially axially symmetrical discharge vessel 2 made of undoped quartz glass and a circular cylindrical, with 1.0 percent by weight barium metaborate ( BaB 2 O 4 ), 0.5 percent by weight of ceraluminate (CeAlO 3 ), 0.5 percent by weight of praseodymium oxide (Pr 6 O 11 ) and quartz glass tube 1 doped with 0.05 percent by weight of titanium oxide (TiO 2 ).
  • the discharge vessel 2 has two gas-tightly closed squeezing ends 5a, 5b and two axially running electrodes 3, each of which is electrically conductively connected to a power supply 7a, 7b via a molybdenum foil melt 6. Both power supply lines each run within a tubular extension 8a, 8b of the crimp ends 5a, 5b.
  • the quartz glass tube 1 is threaded onto the discharge vessel 2.
  • the discharge vessel 2 is held on the tubular extension 8a of the crimping end 5a in a first chuck 12a of a glass lathe, while a counter bearing 13 supports the discharge vessel 2 on the other tubular extension 8b.
  • the glass tube 1 is fixed together with a base 14, a washer, in a second chuck 12b of the glass lathe. Both chucks 12a, 12b of the glass lathe are arranged coaxially.
  • the quartz glass tube 1 is adjusted in such a way that the discharge space and both squeezing ends 5a, 5b are enveloped by the glass tube 1.
  • the base 14 brings about an eccentric arrangement of the glass tube 1 with respect to the discharge vessel 2, such that the discharge vessel axis B-B and the axis of rotation of the glass tube 1 are displaced parallel to one another by the thickness of the base 14.
  • the electrodes 3 lie in the discharge vessel axis B-B and the quartz glass tube 1 forms the outer bulb, this means that the outer bulb axis A-A and the discharge path defined by the electrode heads are likewise displaced parallel to one another by the thickness of the base 14.
  • the free end of the quartz glass tube 1, which is not clamped in the chuck 12b, is heated by means of an H 2 / O 2 burner 15 to the softening temperature of the quartz glass tube of approximately 1540 ° C., or to a temperature slightly above it, and with With the help of a cutting roller 16, it is rolled onto the squeezing end 5a of the discharge vessel 2 and fused with it.
  • the discharge vessel consisting of undoped quartz glass is still solid, since the softening temperature of the undoped quartz glass is approximately 1750 ° C., ie approximately 200 ° C. above the softening temperature of the quartz glass tube. In this way, the free end of the glass tube 1 is closed and fixed to the discharge vessel 2.
  • both chucks 12a, 12b rotate synchronously.
  • the other, still open end of the quartz glass tube 1 is closed in the same way by heating using an H 2 / O 2 burner 15.
  • the two tubular extensions 8a, 8b of the discharge vessel 2 are clamped in the chuck 12a, 12b of the glass lathe.
  • the glass tube 1 is fixed to the discharge vessel 2 by its already closed end, so that it does not have to be held in a holding device of the glass lathe.
  • the quartz glass tube 1 used in this exemplary embodiment has an inner diameter of approximately 8.8 mm, a wall thickness of 1.0 mm and a length of 25-32 mm.
  • the length of the prefabricated discharge vessel 2, including its tubular extensions, is approximately 150 mm, its inner diameter is approximately 2.3 mm, its wall thickness is approximately 1.3 mm and the electrode spacing is approximately 4-5 mm.
  • the most favorable value for the distance between the outer bulb axis A-A and the discharge path or the discharge vessel axis B-B was found to be 0.65 mm.
  • the tubular extension 8b is separated from the discharge vessel, while the other tubular extension 8a is shortened and used to base the high-pressure discharge lamp.
  • the base of the lamp is described, for example, in EP-A 455 884 and will therefore not be explained in more detail here.
  • a quartz glass can therefore also be used as the outer bulb glass, which has only a viscosity-reducing doping and no doping that absorbs UV rays.
  • quartz glasses suitable as outer bulb glass can be found in EP-A-0 601 391 (Art. 54 (3) EPC).
  • Rare earth metal additives other than those specified in the exemplary embodiment can also be used as the UV radiation-absorbing doping.
  • the UV radiation-absorbing doping sensibly ranges from about 0.1 to 1.5 percent by weight for rare earth metal additives and from about 0 to 0.15 percent by weight for titanium oxide. The percentages by weight always refer to the undoped quartz glass.
  • the viscosity-reducing alkaline earth metal borate content in particular the barium metaborate content in the quartz glass, is expediently about 0.05 to 2.0 percent by weight.
  • other viscosity-reducing quartz glass dopants can of course also be used. If the rare earth metal doping in quartz glass is sufficiently high, the alkaline earth metal borate additions can be reduced or even eliminated entirely, since the rare earth metal doping in quartz glass also has a viscosity-reducing effect.

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  • Manufacturing & Machinery (AREA)
  • Vessels And Coating Films For Discharge Lamps (AREA)

Abstract

The invention relates to a high-pressure discharge lamp with an outer bulb surrounding the discharge chamber and a process for its production. The outer bulb (1) is made of a glass with low viscosity and especially a lower softening temperature than the quartz glass of the discharge chamber (2) and is fused directly to the ends (5a, 5b) of the discharge chamber (2) which is sealed on both sides. The glass of the outer bulb is preferably a quartz glass doped with viscosity-reducing additives, especially alkaline earth borates, whereas the discharge chamber consists of undoped quartz glass. In addition, the quartz glass of the outer bulb is preferably doped with u/v radiation-absorbing rare earth metal additives. To avoid imaging errors, the axis of symmetry of the essentially rotation-symmetrical outer bulb (1) is shifted parallel to the section securing the electrode heads by an amount corresponding to the discharge arc curvature defined by convection with the lamp operating in a horizontal position.

Description

Die Erfindung betrifft eine Hochdruckentladungslampe gemäß dem Oberbegriff des Patentanspruchs 1 sowie ein Verfahren zur Herstellung einer Hochdruckentladungslampe.The invention relates to a high-pressure discharge lamp according to the preamble of claim 1 and a method for producing a high-pressure discharge lamp.

Insbesondere handelt es sich um eine Hochdruckentladungslampe, die für ein optisches Abbildungssystem, wie z.B. für einen Kfz-Scheinwerfer geeignet ist.In particular, it is a high-pressure discharge lamp that is used for an optical imaging system, such as is suitable for a motor vehicle headlight.

Die EP-A 0 570 068 offenbart eine derartige, dem Oberbegriff des Patentanspruchs 1 entsprechende Lampe. Sie dient als Lichtquelle für einen Kfz-Scheinwerfer. Diese Hochdruckentladungslampe besitzt ein zweiseitig, mittels Molybdäneinschmelzungsfolien abgedichtetes Entladungsgefäß aus Quarzglas mit zwei axial darin ausgerichteten Elektroden, die jeweils in einem Entladungsgefäßende eingeschmolzen sind. Ein aus Quarzglas bestehender Außenkolben umgibt das Entladungsgefäß. Figur 3 dieser Offenlegungsschrift zeigt eine Hochdruckentladungslampe mit einem im wesentlichen rotationssymmetrischen Außenkolben, der koaxial zum Entladungsgefäß angeordnet und außerhalb der Molybdäneinschmelzungsfolien mit den abgedichteten Enden des Entladungsgefäßes verschmolzen ist. Bei dieser Art der Außenkolbenbefestigung besteht die Gefahr, daß beim Verschmelzen des Außenkolbens mit den Entladungsgefäßenden die Molybdänfolieneinschmelzung des Entladungsgefäßes beschädigt wird und das Entladungsgefäß nicht mehr gasdicht verschlossen ist. Diese Gefahr läßt sich bei Lampen gemäß der EP-A 0 570 068 dadurch verringern, daß die Verschmelzung von Außenkolben und Entladungsgefäß in ausreichendem Abstand von der Molybdänfolienabdichtung erfolgt.EP-A 0 570 068 discloses such a lamp, which corresponds to the preamble of patent claim 1. It serves as a light source for a motor vehicle headlight. This high-pressure discharge lamp has a discharge vessel made of quartz glass which is sealed on two sides and sealed by means of melted-in molybdenum, with two axially aligned electrodes which are each melted into one end of the discharge vessel. An outer bulb made of quartz glass surrounds the discharge vessel. FIG. 3 of this laid-open document shows a high-pressure discharge lamp with an essentially rotationally symmetrical outer bulb which is arranged coaxially with the discharge vessel and is fused to the sealed ends of the discharge vessel outside the molybdenum melting films. With this type of outer bulb attachment, there is a risk that when the outer bulb melts with the discharge vessel ends, the molybdenum foil melt-down of the discharge vessel will be damaged and the discharge vessel will no longer be sealed gas-tight. In the case of lamps according to EP-A 0 570 068, this risk can be reduced in that the outer bulb and the discharge vessel are fused at a sufficient distance from the molybdenum foil seal.

Die EP-A 0 465 083 beschreibt ebenfalls eine unter den Oberbegriff des Patentanspruchs 1 fallende Hochdruckentladungslampe. Diese Hochdruckentladungslampe besitzt ein zweiseitig, mittels Molybdäneinschmelzungsfolien abgedichtetes Entladungsgefäß aus Quarzglas mit zwei axial darin ausgerichteten Elektroden, die jeweils in einem Entladungsgefäßende eingeschmolzen sind. Außerhalb der eingeschmolzenen Molybdänfolien weisen die Entladungsgefäßenden jeweils eine tellerartige Verdickung auf, mit denen ein aus Quarzglas bestehender, das Entladungsgefäß umschließender Außenkolben gasdicht verschmolzen ist. Diese Art der Außenkolbenfixierung am Entladungsgefäß mittels der tellerartigen Verdickungen ist vergleichsweise aufwendig. Außerdem müssen diese tellerartigen Verdickungen ebenfalls einen ausreichenden Abstand zu den eingeschmolzenen Molybdänfolien aufweisen, um die Abdichtung des Entladungsgefäßes nicht zu gefährden.EP-A 0 465 083 also describes a high-pressure discharge lamp falling under the preamble of patent claim 1. This high-pressure discharge lamp has a discharge vessel made of quartz glass which is sealed on two sides and sealed by means of melted-in molybdenum, with two axially aligned electrodes which are each melted into one end of the discharge vessel. Outside of the melted down Molybdenum foils each have a plate-like thickening with which an outer bulb made of quartz glass and surrounding the discharge vessel is fused in a gas-tight manner. This type of outer bulb fixation on the discharge vessel by means of the plate-like thickenings is comparatively complex. In addition, these plate-like thickenings must also be at a sufficient distance from the melted-in molybdenum foils in order not to endanger the sealing of the discharge vessel.

Die Patentschrift US 5,196,759 offenbart eine mit einem soffittenartigen Entladungsgefäß und einem ebenfalls soffittenartigen Außenkolben ausgestattete Hochdruckentladungslampe. Der Außenkolben besteht aus einem mit Ultraviolettstrahlen absorbierenden Zusätzen dotiertes Quarzglas. Er umschließt das Entladungsgefäß berührungsfrei. Die Enden des Außenkolbens sind über den aus dem Entladungsgefäß herausragenden Stromzuführungen mittels Molybdänfolieneinschmelzungen abgedichtet.The patent US Pat. No. 5,196,759 discloses a high-pressure discharge lamp which is equipped with a tubular discharge vessel and a tubular outer bulb. The outer bulb consists of quartz glass doped with additives that absorb ultraviolet rays. It surrounds the discharge vessel without contact. The ends of the outer bulb are sealed by means of melted-down molybdenum foil via the current leads protruding from the discharge vessel.

Die kanadische Offenlegungsschrift CA 2,026,850 beschreibt eine mit einem Außenkolben versehene Hochdruckentladungslampe, deren Entladungsgefäß schräg zur Längsachse oder außerhalb der Längsachse des Außenkolbens angeordnet ist, um in Abhängigkeit von der Lage des Entladungsgefäßes und vom Reflektortyp eine optimale Lichtausbeute zu gewährleisten.The Canadian laid-open specification CA 2,026,850 describes a high-pressure discharge lamp provided with an outer bulb, the discharge vessel of which is arranged obliquely to the longitudinal axis or outside the longitudinal axis of the outer bulb, in order to ensure an optimum light output as a function of the position of the discharge vessel and of the reflector type.

Es ist die Aufgabe der Erfindung, eine Hochdruckentladungslampe gemäß dem Oberbegriff des Patentanspruchs 1 bereitzustellen, die insbesondere für Lampen mit kleinen Abmessungen, das sind niederwattige Hochdruckentladungslampen bis zu einer elektrischen Leistung von ca. 150 W, eine möglichst einfache und sichere Befestigung des Außenkolbens gewährleistet, sowie ein Verfahren zur Herstellung einer solchen Hochdruckentladungslampe anzugeben.It is the object of the invention to provide a high-pressure discharge lamp according to the preamble of patent claim 1, which ensures that the outer bulb is attached to the outer bulb as simply and securely as possible, in particular for lamps with small dimensions, that is, low-wattage high-pressure discharge lamps up to an electrical output of approximately 150 W. and to specify a method for producing such a high-pressure discharge lamp.

Diese Aufgabe wird erfindungsgemäß durch die kennzeichnenden Merkmale des Patentanspruchs 1 gelöst. Besonders vorteilhafte Ausführungen der Erfindung sind in den Unteransprüchen beschrieben.This object is achieved by the characterizing features of claim 1. Particularly advantageous embodiments of the invention are described in the subclaims.

Die erfindungsgemäßen Hochdruckentladungslampen sind mit einem Außenkolben ausgestattet, dessen Glas eine geringere Viskosität und damit eine tiefere Erweichungstemperatur als das Quarzglas des Entladungsgefäßes besitzt. Dadurch wird beim Anschmelzen des Außenkolbens an das Entladungsgefäß nur das Außenkolbenglas, nicht aber das Quarzglas des Entladungsgefäßes erweicht. Aufgrund der unterschiedlichen Erweichungstemperaturen besteht deshalb nicht die Gefahr, daß die abgedichteten Entladungsgefäßenden beim Anschmelzen des Außenkolbens wieder aufgeschmolzen und beschädigt werden. Es ist sogar möglich, den Außenkolben unmittelbar an die Quetschdichtungen der Entladungsgefäßenden anzuschmelzen, ohne dabei die Abdichtung der Entladungsgefäßenden, die durch die darin eingebetteten Molybdänfolien gewährleistet wird, zu beeinträchtigen. Dadurch kann die Baulänge der erfindungsgemäßen Hochdrukkentladungslampe im Vergleich zu den oben als Stand der Technik zitierten Lampen verkürzt werden.The high-pressure discharge lamps according to the invention are equipped with an outer bulb, the glass of which has a lower viscosity and thus a has a lower softening temperature than the quartz glass of the discharge vessel. As a result, only the outer bulb glass, but not the quartz glass of the discharge vessel, is softened when the outer bulb melts onto the discharge vessel. Because of the different softening temperatures, there is therefore no danger that the sealed discharge vessel ends will be melted and damaged again when the outer bulb melts. It is even possible to melt the outer bulb directly onto the pinch seals of the discharge vessel ends without impairing the sealing of the discharge vessel ends, which is ensured by the molybdenum foils embedded therein. As a result, the overall length of the high-pressure discharge lamp according to the invention can be shortened in comparison to the lamps cited above as prior art.

Vorteilhafterweise ist der Außenkolben aus einem mit viskositätserniedrigenden Zusätzen versehenen, sogenannten weichen Quarzglas gefertigt, während das thermisch höher belastete Entladungsgefäß aus undotiertem Quarzglas besteht. Weiche Quarzgläser haben, verglichen mit reinem, undotiertem Quarzglas (Kieselsäuregehalt von ca. 99,99 Molprozent), einen bei deutlich tieferen Temperaturen angesiedelten Erweichungsbereich und lassen sich daher einfacher und energiesparender verarbeiten als reines Quarzglas. Beispiele für derartige, vorteilhaft als Außenkolbenglas verwendbare weiche Quarzgläser sind in der EP-A-0 601 391 (Art. 54(3)) offenbart. Als viskositätserniedrigende Dotiermittel werden vor allem Erdalkalimetallborate im Quarzglas eingesetzt. Vorteilhafterweise enthält das Außenkolbenglas aber auch Zusätze von Seltenen-Erdmetall-Verbindungen, die die Transparenz des Außenkolbenglases im ultravioletten Spektralbereich vermindern, um die UV-Emission der Hochdruckentladungslampe zu reduzieren. Da diese UV-Strahlen absorbierenden Seltenen-Erdmetall-Verbindungen selbst die Viskosität des Außenkolbenglases vermindern, kann bei einem ausreichenden Gehalt an Seltenen-Erdmetall-Verbindungen im Außenkolbenglas, d. h., bei einem Gewichtsanteil dieser Seltenen-Erdmetall-Verbindungen von mehr als ca. 0,5 Gewichtsprozent, möglicherweise auf die anfangs genannten viskositätsemiedrigenden Erdalkalimetallborate verzichtet werden.Advantageously, the outer bulb is made of a so-called soft quartz glass provided with viscosity-reducing additives, while the thermally more highly stressed discharge vessel consists of undoped quartz glass. Soft quartz glasses Compared to pure, undoped quartz glass (silica content of approx. 99.99 mole percent), they have a softening range at significantly lower temperatures and are therefore easier and more energy-efficient to process than pure quartz glass. Examples of such soft quartz glasses, which can advantageously be used as outer bulb glass, are disclosed in EP-A-0 601 391 (Art. 54 (3)). Alkaline earth metal borates in quartz glass are primarily used as viscosity-reducing dopants. Advantageously, however, the outer bulb glass also contains additives of rare earth metal compounds which reduce the transparency of the outer bulb glass in the ultraviolet spectral range in order to reduce the UV emission of the high-pressure discharge lamp. Since these rare earth metal compounds absorbing UV rays themselves reduce the viscosity of the outer bulb glass, a sufficient amount of rare earth metal compounds in the outer bulb glass, ie with a weight fraction of these rare earth metal compounds of more than approx. 5 percent by weight, possibly the initially mentioned viscosity-reducing alkaline earth metal borates can be dispensed with.

Besonders vorteilhaft wirkt sich die einfache Außenkolbenbefestigung am Entladungsgefäß bei in Kfz-Scheinwerfern eingesetzten Hochdruckentladungslampen aus, weil hier keine zusätzlichen Halter- oder Gestellteile nötig sind, die zu einer Beeinträchtigung der Lichtemission führen können. In Kfz-Scheinwerfern eingesetzte Hochdruckentladungslampen werden üblicherweise in horizontaler Lage, d. h., mit horizontal verlaufender Entladungsstrecke, betrieben, so daß der Entladungsbogen im Gravitationsfeld der Erde eine konvektionsbedingte sichelartige Aufwärtskrümmung erfährt. Um Abbildungsfehler im Scheinwerfer zu vermeiden, ist die Symmetrieachse des im wesentlichen rotationssymmetrischen Außenkolbens der erfindungsgemäßen Hochdruckentladungslampe gegen die Verbindungsstrecke der entladungsseitigen Elektrodenenden parallelverschoben angeordnet. Der Betrag der Parallelverschiebung entspricht ungefähr der mittleren Auslenkung des Entladungsbogens aus der fiktiven Verbindungsstrecke der Elektrodenenden. Auf diese Weise wird gewährleistet, daß die Außenkolbenwandung keine Spiegelbilder des gekrümmten Entladungsbogens erzeugt, die störende Reflexe im Reflektor verursachen und zu Lichtverlusten führen würden.The simple outer bulb attachment to the discharge vessel has a particularly advantageous effect in the case of high-pressure discharge lamps used in motor vehicle headlights, because no additional holder or frame parts are necessary here, which can lead to impairment of the light emission. High-pressure discharge lamps used in motor vehicle headlights are usually in a horizontal position, i. that is, operated with a horizontally extending discharge path, so that the discharge arc experiences a convection-related sickle-like upward curvature in the earth's gravitational field. In order to avoid imaging errors in the headlamp, the axis of symmetry of the essentially rotationally symmetrical outer bulb of the high-pressure discharge lamp according to the invention is arranged parallel to the connecting path of the discharge-side electrode ends. The amount of the parallel shift corresponds approximately to the mean deflection of the discharge arc from the fictitious connecting section of the electrode ends. In this way it is ensured that the outer bulb wall does not produce mirror images of the curved discharge arc, which would cause disturbing reflections in the reflector and would lead to loss of light.

Vorteilhafterweise verläuft die Außenkolbenachse durch das Helligkeitszentrum bzw. -maximum des Entladungsbogens, das für das Abbildungssytem genutzt wird. Bei Hochdruckentladungslampen kleiner Leistung (unter 100 Watt), die in Kfz-Scheinwerfern Verwendung finden, beträgt die Auslenkung des Entladungsbogens aus der Entladunsstrecke, das ist die Verbindungsstrecke zwischen den entladungsseitigen Enden der Elektroden, etwa 0,3 mm bis 1,0 mm.The outer bulb axis advantageously runs through the brightness center or maximum of the discharge arc, which is used for the imaging system. At High-pressure discharge lamps of low power (less than 100 watts) that are used in motor vehicle headlights, the deflection of the discharge arc from the discharge path, that is the connecting path between the discharge-side ends of the electrodes, about 0.3 mm to 1.0 mm.

Die exzentrische Lage des Außenkolbens bezüglich der Verbindungsstrecke der entladungsseitigen Elektrodenenden beziehungsweise bezüglich der Entladungsgefäßachse - üblicherweise verlaufen die Elektroden in der Entladungsgefäßachse - kann relativ einfach dadurch gewährleistet werden, daß Außenkolben und Entladungsgefäß beim Anschmelzen des Außenkolbens in exzentrisch zueinander angeordneten Spannfuttern einer Glasdrehbank fixiert sind.The eccentric position of the outer bulb with respect to the connecting section of the discharge-side electrode ends or with respect to the discharge vessel axis - usually the electrodes run in the discharge vessel axis - can be ensured relatively simply by fixing the outer bulb and discharge vessel in eccentrically arranged chucks of a glass lathe when the outer bulb melts.

Die Erfindung wird nachstehend anhand eines bevorzugten Ausführungsbeispiels näher erläutert. Es zeigen:

Figur 1a
eine schematische Darstellung der axialen Anordnung der Elektroden innerhalb des Außenkolbens mit Entladungsbogen und dessen von der Außenkolbenwandung erzeugtes Spiegelbild (ohne Entladungsgefäß)
Figur 1b
eine schematische Darstellung der exzentrischen Anordnung der Elektroden bezüglich des Außenkolbens bei den erfindungsgemäßen Lampen (ohne Entladungsgefäß)
Figur 2
eine schematisierte Abbildung einer erfindungsgemäßen Hochdruckentladungslampe mit übertrieben dargestellter exzentrischer Außenkolbenanordnung
Figur 3a
illustriert die Montage des Außenkolbens bei einer erfindungsgemäßen Hochdruckentladungslampe
Figur 3b
illustriert die Montage des Außenkolbens bei einer erfindungsgemäßen Hochdruckentladungslampe
The invention is explained below with reference to a preferred embodiment. Show it:
Figure 1a
a schematic representation of the axial arrangement of the electrodes within the outer bulb with discharge arc and its mirror image generated by the outer bulb wall (without discharge vessel)
Figure 1b
a schematic representation of the eccentric arrangement of the electrodes with respect to the outer bulb in the lamps according to the invention (without discharge vessel)
Figure 2
a schematic representation of a high-pressure discharge lamp according to the invention with an exaggerated eccentric outer bulb arrangement
Figure 3a
illustrates the assembly of the outer bulb in a high-pressure discharge lamp according to the invention
Figure 3b
illustrates the assembly of the outer bulb in a high-pressure discharge lamp according to the invention

Die Figuren 1a und 1b dienen zur Erläuterung der Entstehung und Vermeidung von Spiegelbildem durch die Außenkolbenwandung. Sie sind stark schematisiert. Außerdem wurde in beiden Figuren der Einfachheit halber das Entladungsgefäß nicht abgebildet. In Figur 1a sind die beiden Elektroden 3 horizontal angeordnet und liegen in der Achse A-A des Außenkolbens 1. Die einander zugewandten entladungsseitigen Enden der Elektroden 3 definieren eine in der Außenkolbenachse A-A liegende Entladungsstrecke. Im Betriebszustand bildet sich zwischen den entladungsseitigen Enden der Elektroden 3 ein konvektionsbedingt aufwärts gekrümmter Entladungsbogen 4 aus. Die Außenkolbenwandung erzeugt unterhalb der Achse A-A ein reelles Spiegelbild 4a des Entladungsbogens 4, das zu Lichtverlusten und zu störenden Reflexen bei Verwendung einer derartigen Lampe in einem Abbildungssystem führt.Figures 1a and 1b serve to explain the formation and avoidance of mirror images through the outer bulb wall. They are highly schematic. In addition, the discharge vessel was not shown in both figures for the sake of simplicity. In FIG. 1a, the two electrodes 3 are arranged horizontally and lie in the axis AA of the outer bulb 1. The ends of the electrodes 3 which face one another on the discharge side define a discharge path lying in the outer bulb axis AA. In the operating state, a discharge arc 4 which is curved upward due to convection is formed between the ends of the electrodes 3 on the discharge side. The outer bulb wall generates a real mirror image 4a of the discharge arc 4 below the axis AA, which leads to light losses and disturbing reflections when such a lamp is used in an imaging system.

Figur 1b zeigt die Anordnung von Außenkolben 1 und Elektroden 3 bei einer erfindungsgemäßen Hochdruckentladungslampe. Die Elektroden 3 sind exzentrisch im Außenkolben 1 angeordnet, so daß die Entladungsstrecke parallel zur Außenkolben-achse A-A verläuft, aber nicht mit dieser zusammenfällt. Der Abstand der Elektroden beziehungsweise der Entladungsstrecke zur Außenkolben-achse ist dabei so gewählt, daß die Außenkolbenachse A-A durch das Helligkeitszentrum beziehungsweise Helligkeitsmaximum des Entladungsbogens verläuft und das reelle Spiegelbild 4a mit dem Entladungsbogen 4 weitgehend zur Deckung gebracht wird. Dadurch fällt das Helligkeitszentrum bzw. -maximum des Entladungsbogens 4 mit seinem Spiegelbild zusammen. Als Helligkeitszentrum bzw. -maximum wird derjenige, auf der Mittelsenkrechten zwischen den beiden entladungsseitigen Elektrodenenden liegende Ort bezeichnet, der die höchste Leuchtdichte im Entladungsbogen 4 aufweist.FIG. 1b shows the arrangement of outer bulb 1 and electrodes 3 in a high-pressure discharge lamp according to the invention. The electrodes 3 are arranged eccentrically in the outer bulb 1, so that the discharge path runs parallel to the outer bulb axis A-A, but does not coincide with it. The distance of the electrodes or the discharge path to the outer bulb axis is chosen so that the outer bulb axis A-A runs through the center of brightness or maximum brightness of the discharge arc and the real mirror image 4a is largely coincident with the discharge arc 4. As a result, the brightness center or maximum of the discharge arc 4 coincides with its mirror image. The brightness center or maximum is the location on the center perpendicular between the two discharge-side electrode ends that has the highest luminance in the discharge arc 4.

In Figur 2 ist eine erfindungsgemäße Hochdruckentladungslampe abgebildet. Bei diesem Ausführungsbeispiel handelt es sich um eine einseitig gesockelte Halogenmetalldampflampe mit einer elektrischen Leistungsaufnahme von ca. 35 Watt, die vorzugsweise in Kfz-Scheinwerfern verwendet wird. Diese Lampe weist ein im wesentlichen axialsymmetrisches, zweiseitig abgedichtetes Entladungsgefäß 2 auf, das von einem im wesentlichen rotationssymmetrischen Außenkolben 1 umgeben ist. Das Entladungsgefäß 2 besitzt einen Entladungsraum mit einer gasdicht darin eingeschlossenen ionisierbaren Füllung sowie zwei einander gegenüberliegende Quetschenden 5a, 5b, in denen jeweils eine in den Entladungsraum hineinragende, axial angeordnete Elektrode 3 eingeschmolzen ist. Beide Elektroden 3 sind jeweils über eine Molybdänfolieneinschmelzung 6 mit einer Stromzuführung 7a, 7b elektrisch leitend verbunden. Der Aussenkolben 1 ist direkt auf den Quetschdichtungen 5a, 5b des Entladungsgefäßes 2, in unmittelbarer Nähe des vom Entladungsraum abgewandten Endes der Molybdänfolien 6 befestigt. Er besteht aus mit 1,0 Gewichtsprozent Bariummetaborat (BaB2O4), 0,5 Gewichtsprozent Ceraluminat (CeAlO3), 0,5 Gewichtsprozent Praseodymoxid (Pr6O11) und 0,05 Gewichtsprozent Titanoxid (TiO2) dotiertem Quarzglas. Das Entladungsgefäß 2 ist aus undotiertem Quarzglas gefertigt und mittels einer rohrartigen Verlängerung 8a des Quetschendes 5a im Lampensockel 9 fixiert. Die sockelnahe Stromzuführung 7a verläuft innerhalb der rohrartigen Verlängerung 8a und stellt den elektrischen Kontakt zu einem der beiden Anschlußkabel 10 her, während die sockelferne Stromzuführung 7b über eine Rückführung 11, die eine Keramikisolierung aufweist, mit dem anderen Anschlußkabel 10 elektrisch leitend verbunden ist.A high-pressure discharge lamp according to the invention is shown in FIG. This exemplary embodiment is a metal halide lamp with a base on one side and an electrical power consumption of approximately 35 watts, which is preferably used in motor vehicle headlights. This lamp has an essentially axially symmetrical, two-sided sealed discharge vessel 2, which is surrounded by an essentially rotationally symmetrical outer bulb 1. The discharge vessel 2 has a discharge space with an ionizable filling enclosed in a gas-tight manner therein, as well as two opposing squeezing ends 5a, 5b, in each of which an axially arranged electrode 3 projecting into the discharge space is melted. Both electrodes 3 are each electrically conductively connected to a power supply 7a, 7b via a molybdenum foil melt 6. The outer bulb 1 is fastened directly on the pinch seals 5a, 5b of the discharge vessel 2, in the immediate vicinity of the end of the molybdenum foils 6 facing away from the discharge space. It consists of 1.0 percent by weight barium metaborate (BaB 2 O 4 ), 0.5 Weight percent ceraluminate (CeAlO 3 ), 0.5 weight percent praseodymium oxide (Pr 6 O 11 ) and 0.05 weight percent titanium oxide (TiO 2 ) doped quartz glass. The discharge vessel 2 is made of undoped quartz glass and is fixed in the lamp base 9 by means of a tubular extension 8a of the pinch end 5a. The power supply 7a close to the base runs inside the tubular extension 8a and makes electrical contact with one of the two connection cables 10, while the power supply 7b remote from the base is electrically conductively connected to the other connection cable 10 via a return 11, which has ceramic insulation.

Diese Lampe wird in horizontaler Lage, d.h., mit horizontal verlaufender Entladungsstrecke, betrieben. Dabei ist die Lampe so orientiert, daß die Rückführung 11 unterhalb des Außenkolbens 1 verläuft (Fig. 2). Der Außenkolben 1 ist exzentrisch bzgl. des Entladungsgefäßes 2 und bzgl. der Entladungsstrecke, die durch entladungsseitigen Elektrodenenden definiert wird, angeordnet. Die Außenkolbenachse A-A verläuft ca. 0,65 mm oberhalb und parallel zur Entladungsgefäßachse sowie zur Entladungsstrecke. In Figur 2 ist der Abstand zwischen der Außenkolbenachse A-A und der Entladunsstrecke bzw. der Entladungsgefäßachse B-B der Deutlichkeit halber übertrieben groß dargestellt.This lamp is operated in a horizontal position, i.e. with a horizontal discharge path. The lamp is oriented so that the return 11 runs below the outer bulb 1 (Fig. 2). The outer bulb 1 is arranged eccentrically with respect to the discharge vessel 2 and with respect to the discharge path, which is defined by electrode ends on the discharge side. The outer bulb axis A-A runs approx. 0.65 mm above and parallel to the discharge vessel axis and to the discharge path. In Figure 2, the distance between the outer bulb axis A-A and the discharge path or the discharge vessel axis B-B is exaggerated for clarity.

Die Figuren 3a und 3b illustrieren das Herstellungsverfahren einer erfindungsgemäßen Hochdruckentladungslampe, insbesondere die Montage des Außenkolbens 1. Zur Herstellung einer erfindungsgemäßen Lampe werden als Vorerzeugnisse ein komplett vorgefertigtes, im wesentlichen axialsymmetrisches Entladungsgefäß 2 aus undotiertem Quarzglas sowie ein kreiszylindrisches, mit 1,0 Gewichtsprozent Bariummetaborat (BaB2O4), 0,5 Gewichtsprozent Ceraluminat (CeAlO3), 0,5 Gewichtsprozent Praseodymoxid (Pr6O11) und mit 0,05 Gewichtsprozent Titanoxid (TiO2) dotiertes Quarzglasrohr 1 verwendet. Das Entladungsgefäß 2 besitzt zwei gasdicht verschlossene Quetschenden 5a, 5b und zwei axial verlaufende Elektroden 3, die jeweils über eine Molybdänfolieneinschmelzung 6 mit je einer Stromzuführung 7a, 7b elektrisch leitend verbunden sind. Beide Stromzuführungen verlaufen jeweils innerhalb einer rohrartigen Verlängerung 8a, 8b der Quetschenden 5a, 5b.FIGS. 3a and 3b illustrate the production method of a high-pressure discharge lamp according to the invention, in particular the assembly of the outer bulb 1. To produce a lamp according to the invention, a completely prefabricated, essentially axially symmetrical discharge vessel 2 made of undoped quartz glass and a circular cylindrical, with 1.0 percent by weight barium metaborate ( BaB 2 O 4 ), 0.5 percent by weight of ceraluminate (CeAlO 3 ), 0.5 percent by weight of praseodymium oxide (Pr 6 O 11 ) and quartz glass tube 1 doped with 0.05 percent by weight of titanium oxide (TiO 2 ). The discharge vessel 2 has two gas-tightly closed squeezing ends 5a, 5b and two axially running electrodes 3, each of which is electrically conductively connected to a power supply 7a, 7b via a molybdenum foil melt 6. Both power supply lines each run within a tubular extension 8a, 8b of the crimp ends 5a, 5b.

Zur Montage des Außenkolbens wird das Quarzglasrohr 1 auf das Entladungsgefäß 2 aufgefädelt. Das Entladungsgefäß 2 wird dabei an der rohrartigen Verlängerung 8a des Quetschendes 5a in einem ersten Spannfutter 12a einer Glasdrehbank gehaltert, während ein Gegenlager 13 das Entladungsgefäß 2 an der anderen rohrartigen Verlängerung 8b abstützt.To assemble the outer bulb, the quartz glass tube 1 is threaded onto the discharge vessel 2. The discharge vessel 2 is held on the tubular extension 8a of the crimping end 5a in a first chuck 12a of a glass lathe, while a counter bearing 13 supports the discharge vessel 2 on the other tubular extension 8b.

Das Glasrohr 1 ist zusammen mit einer Unterlage 14, einem Unterlegblech, in einem zweiten Spannfutter 12b der Glasdrehbank fixiert. Beide Spannfutter 12a, 12b der Glasdrehbank sind koaxial angeordnet. Das Quarzglasrohr 1 wird derart justiert, daß der Entladungsraum und beide Quetschenden 5a, 5b vom Glasrohr 1 umhüllt werden. Die Unterlage 14 bewirkt eine exzentrische Anordnung des Glasrohres 1 bzgl. des Entladungsgefäßes 2, derart daß die Entladungsgefäßachse B-B und Rotationsachse des Glasrohres 1 um die Dicke der Unterlage 14 gegeneinander parallelverschoben sind. Da die Elektroden 3 in der Entladungsgefäßachse B-B liegen und das Quarzglasrohr 1 den Außenkolben bildet, bedeutet das, daß die Außenkolbenachse A-A und die durch die Elektrodenköpfe definierte Entladungstrecke ebenfalls um die Dicke der Unterlage 14 gegeneinander parallelverschoben sind.The glass tube 1 is fixed together with a base 14, a washer, in a second chuck 12b of the glass lathe. Both chucks 12a, 12b of the glass lathe are arranged coaxially. The quartz glass tube 1 is adjusted in such a way that the discharge space and both squeezing ends 5a, 5b are enveloped by the glass tube 1. The base 14 brings about an eccentric arrangement of the glass tube 1 with respect to the discharge vessel 2, such that the discharge vessel axis B-B and the axis of rotation of the glass tube 1 are displaced parallel to one another by the thickness of the base 14. Since the electrodes 3 lie in the discharge vessel axis B-B and the quartz glass tube 1 forms the outer bulb, this means that the outer bulb axis A-A and the discharge path defined by the electrode heads are likewise displaced parallel to one another by the thickness of the base 14.

Das freie Ende des Quarzglasrohres 1, das nicht im Spannfutter 12b eingespannt ist, wird mittels eines H2/O2-Brenners 15 auf die Erweichungstemperatur des Quarzglasrohres von ca. 1540 °C, bzw. auf eine geringfügig darüber liegende Temperatur, erhitzt und mit Hilfe einer Schneidrolle 16 auf das Quetschende 5a des Entladungsgefäßes 2 aufgerollt und mit diesem verschmolzen. Bei dieser Temperatur ist das aus undotiertem Quarzglas bestehende Entladungsgefäß noch fest, da die Erweichungstemperatur des undotierten Quarzglases bei ca. 1750 °C, also um ungefähr 200 °C oberhalb der Erweichungstemperatur des Quarzglasrohres liegt. Auf diese Weise wird das freie Ende des Glasrohres 1 verschlossen und am Entladungsgefäß 2 fixiert.The free end of the quartz glass tube 1, which is not clamped in the chuck 12b, is heated by means of an H 2 / O 2 burner 15 to the softening temperature of the quartz glass tube of approximately 1540 ° C., or to a temperature slightly above it, and with With the help of a cutting roller 16, it is rolled onto the squeezing end 5a of the discharge vessel 2 and fused with it. At this temperature, the discharge vessel consisting of undoped quartz glass is still solid, since the softening temperature of the undoped quartz glass is approximately 1750 ° C., ie approximately 200 ° C. above the softening temperature of the quartz glass tube. In this way, the free end of the glass tube 1 is closed and fixed to the discharge vessel 2.

Während des Verschmelzens von Quarzglasrohr 1 und Quetschdichtung 5a rotieren beide Spannfutter 12a, 12b synchron.During the melting of quartz glass tube 1 and pinch seal 5a, both chucks 12a, 12b rotate synchronously.

Das andere, noch offene Ende des Quarzglasrohres 1 wird auf die gleiche Weise durch Erhitzen mittels eines H2/O2-Brenners 15 verschlossen. Hierzu werden die beiden rohrartigen Verlängerungen 8a, 8b des Entladungsgefäßes 2 in die Spannfutter 12a, 12b der Glasdrehbank eingespannt. Das Glasrohr 1 ist während dieses Schmelzprozesses durch sein bereits verschlossenes Ende am Entladungsgefäß 2 fixiert, so daß es nicht in einer Haltevorrichtung der Glasdrehbank gehaltert werden muß.The other, still open end of the quartz glass tube 1 is closed in the same way by heating using an H 2 / O 2 burner 15. For this purpose, the two tubular extensions 8a, 8b of the discharge vessel 2 are clamped in the chuck 12a, 12b of the glass lathe. During this melting process, the glass tube 1 is fixed to the discharge vessel 2 by its already closed end, so that it does not have to be held in a holding device of the glass lathe.

Das bei diesem Ausführungsbeispiel verwendete Quarzglasrohr 1 besitzt einen Innendurchmesser von ca. 8,8 mm, eine Wandstärke von 1,0.mm und eine Länge von 25-32 mm. Die Länge des vorgefertigten Entladungsgefäßes 2, einschließlich seiner rohrartigen Verlängerungen beträgt ungefähr 150 mm, sein Innendurchmesser etwa 2,3 mm, seine Wandstärke ca. 1,3 mm und der Elektrodenabstand ca. 4-5 mm. Als günstigster Wert für den Abstand zwischen der Außenkolbenachse A-A und der Entladungsstrecke bzw. der Entladungsgefäßachse B-B wurde bei diesem Ausführungsbeispiel 0,65 mm ermittelt.The quartz glass tube 1 used in this exemplary embodiment has an inner diameter of approximately 8.8 mm, a wall thickness of 1.0 mm and a length of 25-32 mm. The length of the prefabricated discharge vessel 2, including its tubular extensions, is approximately 150 mm, its inner diameter is approximately 2.3 mm, its wall thickness is approximately 1.3 mm and the electrode spacing is approximately 4-5 mm. In this exemplary embodiment, the most favorable value for the distance between the outer bulb axis A-A and the discharge path or the discharge vessel axis B-B was found to be 0.65 mm.

Nach der Montage des Außenkolbens wird die rohrartige Verlängerung 8b vom Entladungsgefäß abgetrennt, während die andere rohrartige Verlängerung 8a gekürzt und zur Sockelung der Hochdruckentladungslampe benutzt wird. Die Sockelung der Lampe ist beispielsweise in der EP-A 455 884 beschrieben und soll daher hier nicht näher erläutert werden.After assembly of the outer bulb, the tubular extension 8b is separated from the discharge vessel, while the other tubular extension 8a is shortened and used to base the high-pressure discharge lamp. The base of the lamp is described, for example, in EP-A 455 884 and will therefore not be explained in more detail here.

Die Erfindung beschränkt sich nicht auf das näher beschriebene Ausführungsbeispiel. So kann als Außenkolbenglas auch ein Quarzglas verwendet werden, das nur eine viskositätserniedrigende Dotierung aufweist und keine UV-Strahlen absorbierende Dotierung besitzt. Beispiele für derartige, als Außenkolbenglas geeignete Quarzgläser finden sich in der EP-A-0 601 391 (Art. 54(3) EPC). Als UV-Strahlen absorbierende Dotierung können auch andere Seltene-Erdmetall-Zusätze als die im Ausführungsbeispiel angegebenen verwendet werden. Die UV-Strahlen absorbierende Dotierung bewegt sich sinnvollerweise für Seltene-Erdmetall-Zusätze im Bereich von ca. 0,1 bis 1,5 Gewichtsprozent und für Titanoxid im Bereich von ca. 0 bis 0,15 Gewichtsprozent. Die Gewichtsprozentangaben beziehen sich immer auf das undotierte Quarzglas. Der viskositätserniedrigende Erdalkalimetallboratgehalt, insbesondere der Bariummetaboratgehalt im Quarzglas beträgt sinnvollerweise ca. 0,05 bis 2,0 Gewichtsprozent. Abgesehen von Bariummetaborat können natürlich auch andere viskositätserniedrigende Quarzglasdotierungen verwendet werden. Bei ausreichend hoher Seltenen-Erdmetall-Dotierung im Quarzglas können die Erdalkalimetallboratzusätze reduziert werden oder gar ganz entfallen, da die Seltenen-Erdmetall-Dotierung im Quarzglas ebenfalls eine vikositätserniedrigende Wirkung ausübt.The invention is not limited to the exemplary embodiment described in more detail. A quartz glass can therefore also be used as the outer bulb glass, which has only a viscosity-reducing doping and no doping that absorbs UV rays. Examples of such quartz glasses suitable as outer bulb glass can be found in EP-A-0 601 391 (Art. 54 (3) EPC). Rare earth metal additives other than those specified in the exemplary embodiment can also be used as the UV radiation-absorbing doping. The UV radiation-absorbing doping sensibly ranges from about 0.1 to 1.5 percent by weight for rare earth metal additives and from about 0 to 0.15 percent by weight for titanium oxide. The percentages by weight always refer to the undoped quartz glass. The viscosity-reducing alkaline earth metal borate content, in particular the barium metaborate content in the quartz glass, is expediently about 0.05 to 2.0 percent by weight. In addition to barium metaborate, other viscosity-reducing quartz glass dopants can of course also be used. If the rare earth metal doping in quartz glass is sufficiently high, the alkaline earth metal borate additions can be reduced or even eliminated entirely, since the rare earth metal doping in quartz glass also has a viscosity-reducing effect.

Claims (11)

  1. High-pressure discharge lamp, consisting of
    - a discharge vessel (2) which is sealed at two ends, consists of quartz glass and is surrounded by an outer bulb (1),
    - two electrodes (3), which are arranged inside the discharge vessel (2) and are each fixed in one end (5a, 5b) of the discharge vessel (2), the ends (5a, 5b) being designed as pinch seals with molybdenum foils (6) melted into them,
    characterized in that
    - the outer bulb (1) consists of a glass which has a lower softening temperature than the quartz glass of the discharge vessel (2),
    - the outer bulb (1) is fused to the discharge vessel (2) in immediate proximity to the pinch seals (5a, 5b).
  2. High-pressure discharge lamp according to Claim 1, characterized in that the outer bulb (1) consists of quartz glass which is provided with dopants that lower the viscosity and, in particular, the softening temperature of the quartz glass.
  3. High-pressure discharge lamp according to Claim 1, characterized in that the outer bulb (1) is fused to the pinch seals (5a, 5b) in immediate proximity to that end of the molybdenum foil (6) which is remote from the discharge space.
  4. High-pressure discharge lamp according to Claims 1 or 2, characterized in that the dopants contain alkaline earth metal borates.
  5. High-pressure discharge lamp according to Claims 1 or 2, characterized in that the dopants contain rare-earth metals or rare-earth metal compounds.
  6. High-pressure discharge lamp according to Claim 4, characterized in that the quartz glass of the outer bulb (1) is doped with 0.05 to 2.0 per cent by weight of barium metaborate (BaB2O4).
  7. High-pressure discharge lamp according to Claim 5, characterized in that the quartz glass of the outer bulb (1) is doped with 0.1 to 1.5 per cent by weight of cerium aluminate (CeAlO3).
  8. High-pressure discharge lamp according to Claim 5, characterized in that the quartz glass of the outer bulb (1) is doped with 0.1 to 1.5 per cent by weight of praseodymium oxide.
  9. High-pressure discharge lamp according to Claim 1, characterized in that the outer bulb (1) is essentially rotationally symmetric and its symmetry axis is shifted parallel relative to a straight line extending through the electrode heads by an amount which is determined by the gravitationally-induced upward curvature of the discharge arc when the lamp is in a horizontal operating position.
  10. Process for producing a high-pressure discharge lamp according to Claim 1, characterized in that the production process contains the following fabrication steps:
    - producing a discharge vessel (2) with an ionizable fill enclosed therein, and with two ends (5a, 5b) which are closed off in gas-tight fashion and into each of which an axially arranged electrode (3) is melted,
    - fitting the outer bulb (1) over the discharge vessel (2) and aligning it relative thereto, so that the outer bulb (1) at least partly covers the two ends (5a, 5b) of the discharge vessel,
    - heating the outer bulb (1) and rolling its softened ends onto the ends (5a, 5b) of the discharge vessel.
  11. Process for producing a high-pressure discharge lamp according to Claim 10, characterized in that the ends (5a, 5b) of the discharge vessel (2) are designed as pinch seals with molybdenum foils (6) enclosed therein, and the outer bulb (1) is fused to the pinch seals (5a, 5b).
EP94916137A 1993-05-25 1994-05-25 High-pressure discharge lamp and process for producing it Expired - Lifetime EP0700579B1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE4317369A DE4317369A1 (en) 1993-05-25 1993-05-25 High-pressure discharge lamp and manufacturing method for a high-pressure discharge lamp
DE4317369 1993-05-25
PCT/DE1994/000600 WO1994028576A1 (en) 1993-05-25 1994-05-25 High-pressure discharge lamp and process for producing it

Publications (2)

Publication Number Publication Date
EP0700579A1 EP0700579A1 (en) 1996-03-13
EP0700579B1 true EP0700579B1 (en) 1997-07-30

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US (1) US5726532A (en)
EP (1) EP0700579B1 (en)
KR (1) KR100281341B1 (en)
CA (1) CA2163132C (en)
DE (2) DE4317369A1 (en)
HU (1) HU215885B (en)
WO (1) WO1994028576A1 (en)

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DE102007018614A1 (en) 2007-04-19 2008-10-23 Osram Gesellschaft mit beschränkter Haftung High pressure discharge lamp and vehicle headlight with high pressure discharge lamp
DE102007043165A1 (en) 2007-09-11 2009-03-12 Osram Gesellschaft mit beschränkter Haftung High pressure discharge lamp for use in vehicle headlight, has ionizable filling containing xenon halides of zinc, where portion of zinc halide in ionizable filling is smaller or equal to specific value of discharge vessel volume
DE102008014096A1 (en) 2008-03-05 2009-09-10 Osram Gesellschaft mit beschränkter Haftung Tungsten electrode for high-pressure discharge lamps and high-pressure discharge lamp with a tungsten electrode
DE102008026521A1 (en) 2008-06-03 2009-12-10 Osram Gesellschaft mit beschränkter Haftung Thorium-free high-pressure discharge lamp for high-frequency operation
DE102008057703A1 (en) 2008-11-17 2010-05-20 Osram Gesellschaft mit beschränkter Haftung Mercury-free discharge lamp
WO2011057903A1 (en) 2009-11-12 2011-05-19 Osram Gesellschaft mit beschränkter Haftung Mercury-free high-pressure discharge lamp with a reduced amount of zinc halide
DE102013223708A1 (en) 2013-11-20 2015-05-21 Osram Gmbh High-pressure discharge lamp for motor vehicle headlights
DE102015211915A1 (en) 2015-06-26 2016-12-29 Osram Gmbh High-pressure discharge lamp for motor vehicle headlights

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DE19707669A1 (en) * 1997-02-26 1998-08-27 Patent Treuhand Ges Fuer Elektrische Gluehlampen Mbh Method of manufacturing a high pressure discharge lamp
JP3463557B2 (en) * 1998-03-20 2003-11-05 ウシオ電機株式会社 Discharge lamp
EP0964431B2 (en) † 1998-06-12 2007-04-04 Matsushita Electric Industrial Co., Ltd. Discharge lamp
JP3415533B2 (en) * 2000-01-12 2003-06-09 エヌイーシーマイクロ波管株式会社 High pressure discharge lamp
JP2001357818A (en) * 2000-06-13 2001-12-26 Koito Mfg Co Ltd Discharge lamp bulb and its manufacturing method
DE10260129A1 (en) * 2002-12-19 2004-07-01 Patent-Treuhand-Gesellschaft für elektrische Glühlampen mbH lighting unit
DE10260125A1 (en) * 2002-12-19 2004-07-01 Patent-Treuhand-Gesellschaft für elektrische Glühlampen mbH lighting unit
CN103985625B (en) * 2005-05-23 2017-06-27 皇家飞利浦电子股份有限公司 High-intensity discharge lamp
US8242678B2 (en) * 2008-02-14 2012-08-14 Harison Toshiba Lighting Corp. Automotive discharge lamp
EP2529390B1 (en) * 2010-01-28 2019-06-26 Lumileds Holding B.V. Burner with reduced height and method of manufacturing a burner
DE102011082323A1 (en) * 2011-09-08 2013-03-14 Osram Ag High-pressure discharge lamp for motor vehicle headlights
DE102014204932A1 (en) 2014-03-17 2015-09-17 Osram Gmbh High pressure discharge lamp
DE102015200162A1 (en) 2015-01-08 2016-07-14 Osram Gmbh High pressure discharge lamp

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Cited By (11)

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Publication number Priority date Publication date Assignee Title
DE102007018614A1 (en) 2007-04-19 2008-10-23 Osram Gesellschaft mit beschränkter Haftung High pressure discharge lamp and vehicle headlight with high pressure discharge lamp
US8310156B2 (en) 2007-04-19 2012-11-13 Osram Ag High-pressure discharge lamp and vehicle headlight with high-pressure discharge lamp
DE102007043165A1 (en) 2007-09-11 2009-03-12 Osram Gesellschaft mit beschränkter Haftung High pressure discharge lamp for use in vehicle headlight, has ionizable filling containing xenon halides of zinc, where portion of zinc halide in ionizable filling is smaller or equal to specific value of discharge vessel volume
DE102008014096A1 (en) 2008-03-05 2009-09-10 Osram Gesellschaft mit beschränkter Haftung Tungsten electrode for high-pressure discharge lamps and high-pressure discharge lamp with a tungsten electrode
DE102008026521A1 (en) 2008-06-03 2009-12-10 Osram Gesellschaft mit beschränkter Haftung Thorium-free high-pressure discharge lamp for high-frequency operation
DE102008057703A1 (en) 2008-11-17 2010-05-20 Osram Gesellschaft mit beschränkter Haftung Mercury-free discharge lamp
US8736165B2 (en) 2008-11-17 2014-05-27 Osram Gesellschaft Mit Beschraenkter Haftung Mercury-free discharge lamp having a translucent discharge vessel
WO2011057903A1 (en) 2009-11-12 2011-05-19 Osram Gesellschaft mit beschränkter Haftung Mercury-free high-pressure discharge lamp with a reduced amount of zinc halide
DE102009052999A1 (en) 2009-11-12 2011-05-19 Osram Gesellschaft mit beschränkter Haftung High pressure discharge lamp
DE102013223708A1 (en) 2013-11-20 2015-05-21 Osram Gmbh High-pressure discharge lamp for motor vehicle headlights
DE102015211915A1 (en) 2015-06-26 2016-12-29 Osram Gmbh High-pressure discharge lamp for motor vehicle headlights

Also Published As

Publication number Publication date
WO1994028576A1 (en) 1994-12-08
EP0700579A1 (en) 1996-03-13
KR100281341B1 (en) 2001-03-02
HU9503378D0 (en) 1996-01-29
DE59403570D1 (en) 1997-09-04
CA2163132C (en) 2002-04-09
HU215885B (en) 1999-03-29
DE4317369A1 (en) 1994-12-01
US5726532A (en) 1998-03-10
HUT72240A (en) 1996-04-29
CA2163132A1 (en) 1994-12-08

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