EP0886881A1

EP0886881A1 - Gas discharge lamp, in particular for motor-vehicle headlights

Info

Publication number: EP0886881A1
Application number: EP97916328A
Authority: EP
Inventors: Hartmut Seiler; Thomas Wizemann; Ingo Gorille; Wolfgang Pfaff; Wolfgang Schütze; Bernd Müller; Robert Kern
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1996-03-16
Filing date: 1997-03-06
Publication date: 1998-12-30
Anticipated expiration: 2017-03-06
Also published as: DE59701881D1; US6445129B1; DE19610387A1; EP0886881B1; JP2000506672A; WO1997035335A1

Abstract

The invention relates to a gas discharge lamp, in particular for motor-vehicle headlights, which has a maintaining-arc vessel (10) consisting of glass or the like and containing a gas. Two main electrodes (17, 18) protrude into said vessel by way of gas-tight electrode bushings (15, 16). A maintaining-arc distance is provided between the end regions of the main electrodes (17, 18), which regions are arranged in the maintaining-arc vessel (10), and an arc (19) forms along said maintaining-arc distance during operation. To achieve the lowest possible striking voltage, means for producing a creepage distance are provided along the inner vessel wall, or a spark gap (32), smaller than the maintaining-arc distance, in the form of the starting distance which is separate from the maintaining-arc distance.

Description

Gas discharge lamp, especially for motor vehicle windows

State of the art

The invention relates to a gas discharge lamp, in particular for motor vehicle headlights, according to the preamble of the main claim.

Gas discharge lamps or high-pressure gas discharge lamps are already used as standard in motor vehicle headlights, since they have a much better light output compared to conventional incandescent lamps and the spectral composition of the light is very similar to that of daylight. Depending on the ignition method used, these gas discharge lamps require an ignition voltage between the electrodes of between 6 kV and approximately 25 kV. This voltage initiates the ionization in the gas filling. To burn, ie to maintain the arc between the electrodes, only low voltages of about 50 V are then required, since sufficient charge carriers are then already available. However, the generation of the high ignition voltages places high demands on the electronic components used and on the insulation of the lamp base, the lamp holder and the components generating the high voltage (ignition inductance, ignition capacitor, etc.), particularly in the case of HF resonance ignition. Such gas discharge lamps, their use for motor vehicle headlights and various designs of ballasts for generating the ignition and braking voltage for such lamps are known for example from DE-OS 35 19 611 and from "Lamps and Lighting, 2nd edition, ST Henderson and A.M. Marsden, p. 328 ff. Due to the high ignition voltage caused by ¬ gentle problems, it is a general effort to reduce the ignition voltage, while a safe ignition must remain guaranteed.

ADVANTAGES OF THE INVENTION

The gas discharge lamp according to the invention with the characterizing features of the main claim has the advantage that the ignition voltage can be significantly reduced while maintaining a reliable ignition behavior, only relatively minor structural changes to the lamp or its electrodes being required. In view of the resulting reduced requirements on the components, this can make a significant contribution to reducing costs in the electronic ballast and also in the gas discharge lamp itself, since there, for example, significantly lower requirements are placed on the high-voltage resistance of the lamp base and the components arranged therein are put. A particularly significant cost reduction of the gas discharge lamp occurs when the ballast is integrated in the lamp base.

The measures listed in the subclaims permit advantageous developments and improvements of the gas discharge lamp specified in the main claim.

A particularly effective reduction in the ignition voltage can be achieved by at least one ignition electrode, which can be arranged separately from the main electrodes or molded onto them. In a first embodiment, this ignition electrode can be designed as a separate third electrode with its own gas-tight leadthrough through the burner vessel, the shorter ignition path being formed toward one of the main electrodes.

In a further advantageous embodiment, the ignition electrode can be arranged as a separate third electrode on the outside of the burner vessel and in turn forms the ignition path towards one of the main electrodes. In this embodiment, only a very slight structural change in the conventional gas discharge lamps is necessary, that is to say that this ignition electrode can also be retrofitted to conventional gas discharge lamps, in particular to one of tube-like extensions which lead through the electrodes for the main electrodes of the lamp included. In this case, the ignition electrode expediently encompasses one of the two main electrodes in a ring-shaped or partially ring-shaped manner. If the tubular extension of the burner vessel has a constriction, the ignition electrode is advantageously arranged on this constriction or extends into it, since a particularly short ignition distance and a correspondingly significant reduction in the ignition voltage can then be achieved.

In all the embodiments mentioned so far, the ignition electrode can either be designed as a true third electrode or a galvanic connection with one of the main electrodes, which enables the ignition part of the ballast to be operated completely separately from the other electronics. This means that only the ignition part of the ballast needs to be resistant to high voltages, but not the majority of the components that are required for low-ohmic normal operation. However, it is it is also possible to electrically connect the ignition electrode to the main electrode which is not involved in the formation of the ignition path, as a result of which the structure and the voltage feeds are simplified overall.

In a further advantageous embodiment, the at least one ignition electrode is arranged in the interior of the burner vessel, where it is better protected against external influences and where the connection to one of the main electrodes can be implemented easily and inexpensively. This embodiment can be realized in an advantageous manner in that the ignition electrode is connected to the one main electrode and extends to a point in the vicinity of the other main electrode, which in the operating state lies below this other main electrode. The ignition electrode is expediently designed as a rod-like or wire-like side arm of the one main electrode and can therefore be manufactured together with it as a one-piece component, the free end of the ignition electrode opening in particular on the wall of the burner vessel, or else the ignition electrode is as Metallization formed on the inside of the burner vessel and extends for connection to the one main electrode up to its electrode leadthrough, so that an electrical connection is automatically established. Such metallization or metal vapor deposition is comparatively inexpensive to apply in the normal production process of the lamp.

Starting from the electrode leadthrough, the metallization at least partially encompasses the main electrode and preferably extends essentially to the free end region of this main electrode, so that a sliding spark gap can form from there. A clearer reduction in the ignition voltage can be achieved by Shaped or 1 i chtref1 ector-like metallization can be achieved, which extends at least along the area of the focal distance to the area of the other main electrode. The primary reflector-like metallization preferably extends essentially over the lower half of the combustion chamber of the burner vessel in the operating position and has the additional advantage of a vehicle headlight Xür__das Function ^"of ~ ^{päTisonstlTn"} necessary Blen ^'de mitübernimmt to the prescribed set Hei 1 -dark limit and protect oncoming traffic before a glare. In the case of reflective properties, most of the otherwise lost light can be used to illuminate the road, provided that an application in a motor vehicle headlight is provided.

In a further advantageous embodiment, each of the two main electrodes is connected to an ignition electrode, between which a spark or glow spark gap is formed as an ignition gap.

In a first constructive embodiment, the ignition electrodes are designed as lateral arms of the main electrodes and extend in particular to form a sliding spark gap up to the inner glass wall of the burner vessel. The ignition electrodes are designed as rod-like or wire-like arms or as tapered lateral formations on the main electrodes, a particularly high electrical field being produced at the tapered ends, so that the ignition voltage can thereby be significantly reduced. In the case of rod-like or wire-like arms, the ignition electrodes preferably extend obliquely to one another up to the ignition plug and are arranged below the main electrodes during operation. As a result, very short ignition distances can be achieved with a correspondingly significantly reduced ignition voltage. The Arcs arising after the ignition sparks then migrate automatically through the thermal conditions in the combustion chamber to the location between the main electrodes.

In an alternative constructive embodiment, the two ignition electrodes are in the form of metallizations, each of which extends for connection to the main electrodes up to their electrode bushings. Here too, corresponding designs are possible, as in the case of a single electrode formed by a metallization, where the advantages already described also occur. In the case of two such ignition electrodes, the design variation possibilities are even greater, and in particular, sliding spark gaps can be formed as ignition gaps along the inner wall of the burner vessel.

Tungsten metallization is particularly suitable as the metallization.

A further advantageous embodiment of the invention consists in that the main electrodes have a cross-sectional profile with a pointed corner, in particular a triangular profile 1. Since the electrodes extend to the glass inner wall on the electrode leadthrough, glass appears at the separation point. Electrode has a very large dielectric jump, so that high field strengths occur. This effect is supported by the pointed corner, so that a sliding discharge is formed on the glass wall even at relatively low ignition voltages, and here too - like in the other exemplary embodiments - the arc migrates upwards due to thermal effects and finally burns at the broadened cross-sectional area. This can be supported by the fact that the mutually facing surfaces of the Main electrodes are inclined in opposite directions to their longitudinal axes, the regions of the main electrodes which are closer to one another being wider and the regions which are more distant from one another are tapering.

DRAWING

Fourteen embodiments of the invention are in the

Drawing shown and explained in more detail in the following description. Show it:

1 shows a cross-sectional illustration of a first exemplary embodiment with an outer ring-shaped ignition electrode,

2 shows a cross-sectional illustration of a second exemplary embodiment with a wire ring-shaped outer ignition electrode,

3 shows a cross-sectional illustration of a third exemplary embodiment with an ignition electrode which is carried out separately through the burner vessel,

4 shows a cross-sectional illustration of a fourth exemplary embodiment with an inner ignition electrode formed by a metallization,

5 shows a cross-sectional representation of a fifth exemplary embodiment with a differently designed inner electrode formed by a metallization,

6 is a cross-sectional view of a sixth exemplary embodiment with two inner ignition electrodes formed by metallization,

7 shows a cross-sectional illustration of a seventh exemplary embodiment with two ignition electrodes designed as lateral extensions of the main electrodes,

8 shows a cross-sectional illustration of an eighth exemplary embodiment with one as a side Extension of a main electrode formed ignition electrode,

9 shows a cross-sectional illustration of a ninth exemplary embodiment with an outer igniter that engages in a constricted area of the burner vessel,

10 shows a cross-sectional illustration of a tenth exemplary embodiment with two ignition electrodes designed as tapered lateral extensions of the main electrodes,

11 is a cross-sectional view of one of the main electrodes provided with the extensions,

12 shows a cross-sectional illustration of an eleventh exemplary embodiment with two main electrodes having a wedge profile,

13 is a cross-sectional view of the profile of one of the main electrodes,

14 is a cross-sectional view of a twelfth

Exemplary embodiment with an electrode shape modified compared to FIG. 12,

15 is a cross-sectional view of a thirteenth embodiment with an outer ignition electrode formed by a metallization, which also serves as a light reflector, and

16 shows a cross-sectional illustration of a fourteenth exemplary embodiment with an inner ignition electrode formed by a metallization, which also serves as a light reflector.

DESCRIPTION OF THE EMBODIMENTS

The gas discharge lamp or high-pressure gas discharge lamp shown in FIG. 1 as the first exemplary embodiment essentially consists of a burner vessel 10 which is made of glass or another transparent, temperature- resistant material and has a central combustion chamber 12 with a flattened spherical shape or ellipsoidal shape, which has two tubular extensions 13, 14 on opposite sides. The outer end regions of these tubular extensions 13, 14 are designed as gas-tight electrode bushings 15, 16 for two rod-shaped main electrodes 17, 18, which extend slightly into the combustion chamber 12 from both sides. The arc ¹⁹ is formed during operation between these two main electrodes 17, 18.

Outer electrical connecting wires 20, 21 are connected to the two main electrodes 17, 18 via connecting elements 22, which can be formed, for example, as molybdenum foils. The electrical connecting wires 20, 21 still run over a certain distance in tubular extensions 23, 24 of the extensions 13, 14, the electrode bushings 15, 16 between the extensions 13, 24 and the tubular extensions 23, 24, the connecting elements 22 and the hold the respective connection ends of the main electrodes 17, 18 or connection wires 20, 21. During manufacture, the main electrodes 17, 18 connected to the electrical connecting wires 20, 21 are inserted into the lateral connecting tubes of the combustion chamber 12, these connecting tubes being fused in the connecting area such that the connecting areas are melted and the extensions 13, 14 on the one hand and the tubular extensions 23, 24, on the other hand, are formed on both sides of the electrode bushings 15, 16. In the following exemplary embodiments, the electrical connection wires 20, 21, the connecting elements 22 and the tubular extensions 24, 24 are not shown, although it would of course also be possible in principle to implement such a simpler version. It continues to simplify in all of ^the exemplary embodiments, the representation of an L ^{on the} pen base s is dispensed with, for example one of the extensions 13, 14 could be embedded in such a lamp base, the second main electrode pointing away from this lamp base being returned to the lamp base via an external line. Other known designs of burner vessels are of course also possible for 1 s.

On the extension 13 arranged to the left of the combustion chamber 12 there is an annular metal band which forms an ignition electrode 25. As a result, this ignition electrode 25 concentrically surrounds the main electrode 17. Instead of a metal band, a band-shaped metallization can also take place, a partial ring form also being able to take the place of the ring form.

The ignition electrode 25 is electrically connected to the right main electrode 18 outside the burner vessel 10, while the main electrode 17, which runs concentrically in the ignition electrode 25, is connected to another voltage termination of a ballast device (not shown) for generating a combustion and ignition voltage. Since the distance between the ignition electrode 25 and the main electrode 17 is significantly smaller than the distance between the two main electrodes 17, 18, a significantly lower ignition voltage is sufficient for the ignition. For example, the ignition voltage can be reduced from 18 kV to 4 kV. After the occurrence of an ignition spark or ignition arc, this migrates due to the thermal conditions in the combustion chamber to the combustion path between the main electrodes, which creates the arc 19, which has an electrical arc curvature upwards, since the hot gas in the arc due to its lower density moves upwards against gravity. It is of course also possible to design the ignition electrode 25 as a true third electrode without a galvanic connection to one of the two main electrodes 17, 18. Then the ignition voltage can be formed in a separate ignition part of the circuit separately from the rest of the electronics, so that only this ignition part needs to be resistant to high voltages, but not the majority of the other components that are required for the low-voltage combustion mode to generate the internal voltage.

The second exemplary embodiment shown in FIG. 2 largely corresponds to the first exemplary embodiment, an ignition electrode 26 designed as a wire ring replacing the band-shaped ignition electrode 25, this wire ring being arranged at the connection point between the left extension 13 and the combustion chamber 12.

In the third exemplary embodiment shown in FIG. 3, a rod-shaped or wire-shaped ignition electrode 27 is passed through the wall of the combustion chamber 12 via a gas-tight electrode passage 28, the free end of this ignition electrode 27 ending in the vicinity of the left main electrode 17, so that a relatively short ignition distance can be formed. Otherwise the previous explanations apply.

In the fourth exemplary embodiment shown in FIG. 4, an ignition electrode 29 in the form of a metallization or metal vapor deposition is arranged on the inner surface of the burner vessel 10. This metallization extends over the inner surface of the right extension 14 and still projects somewhat as an all-round metal 1 i si erung into the combustion chamber 12, essentially to the end region of the Haupt¬ electrode 18. Of this all-round metal 1 i si erung 30 extends from a narrow metallization 31 in the Longitudinal direction along the combustion chamber 12 and extends essentially to the attachment point of the left extension 13, that is to say in the vicinity of the left main electrode 17.

When switching on, an ignition arc 32 is therefore first formed between the end of the metallization web 31 and the left main electrode 17, which then expands to form an arc 19 between the two main electrodes 17, 18 for the thermal reasons mentioned.

A modification of the embodiment shown in FIG. 4 is shown in FIG. 16. There, an ignition electrode 60 takes the place of the ignition electrode 29, likewise in the form of an internal metal coating or metal vapor deposition, in which, based on an all-round metal coating 61, essentially the all-round metal 1 corresponds to 30, instead of a narrow metallization bar 31, a wide, reflector-like metallization 62 now extends to the left main electrode 17 and opens there at a metallization ring 63 encompassing this left main electrode 17. The reflector-like metallization 62 extends over the lower half of the combustion chamber 12 in the operating position shown, ie up to the height of the main electrodes 17, 18. Of course, narrower designs are also conceivable.

In particular in motor vehicle headlights, the light emitted downwards cannot be used and must be shielded by an aperture. As a result, the prescribed Hei 1 dark limit can be set in order to protect oncoming traffic from glare. In the exemplary embodiment shown in FIG. 16, such an additional screen can be omitted and its function is taken over by the metallization 62. If the metal 1 is chosen appropriately, the metallization has reflective layers Properties, so the majority of the otherwise lost light can be used and used to illuminate the street. When switching on, like in FIG. 4, an ignition arc 32 is first formed between the left edge of the metallization ring 63 and the left main electrode 17.

For the function, it is in principle irrelevant whether the metallization is applied inside the burner vessel 10 or on the outside thereof. In Fig. 15, an ignition electrode 64 in the form of an outer metal 1 i si erung or outer metal 1 vaporization is shown. Otherwise, an all-round metallization 65 corresponds to the all-round metallization 61 of FIG. 16, a reflector-like metallization 66 corresponds to the reflector-like metallization 62, and a metallization ring 67 corresponds to the metallization ring 63. In contrast to FIG. 16, it can be used as an outer metallization All-round metallization 65, of course, does not reach the main electrode 18. It therefore continues along the electrode feed-through 16 and the extension 24 and is contacted there via a contact wire 68 and connected via a line 69 on the one hand to ground and on the other hand to the electrical connecting wire 21.

The fifth exemplary embodiment shown in FIG. 5 largely corresponds to the fourth exemplary embodiment, only the metallization web 31 being omitted and an ignition electrode 33 being formed only by an all-round metallization which corresponds to the all-round metallization 30.

At the transition between the free all-round edge of the ignition electrode 33 and the glass inner surface of the combustion chamber 12, a very large jump in dielectric occurs. When created As a result, very high field strengths occur, and this effect is further supported by the sharp edge at the end of the metallization. This excessive field strength reduces the ignition voltage required for the flashover. The first discharge is formed as a sliding discharge 34 on the glass wall and as a flashover between the glass wall at the connection point combustion chamber 12 / extension 13 and the left main electrode 17.

The sixth exemplary embodiment shown in FIG. 6 largely corresponds to the fifth exemplary embodiment, ignition electrodes 35, 36 designed as all-round metallization being provided on both main electrodes 17, 18. Here too, a sliding discharge along the glass wall between the ignition electrodes 35, 36 is formed in a corresponding manner.

In a modification of the exemplary embodiment shown in FIG. 6, metallization webs, not yet shown, can also be provided, which extend from one or both ignition electrodes 35, 36 to the other ignition electrode.

In the seventh exemplary embodiment shown in FIG. 7, rod-like or wire-like ignition electrodes 37, 38 extend obliquely downward from the main electrodes 17, 18 towards the glass wall and open there at a small distance from one another which ^extends the ignition ^path bi 1 det. These ignition electrodes 37, 38 extending laterally from the main electrodes 17, 18 can either be integrally formed or welded on.

Due to the very small distance between the ignition electrodes 37, 38, the ignition can take place with a very low ignition voltage, since the breakdown voltage in gases is approximately proportional to the electrode gap. The arrangement and design of the electrode extensions in relation to the vessel wall ensures that the arc that arises following the ignition sparks or ignition arcs also migrates here to the location between the main electrodes 17, 18 due to the thermal conditions in the combustion chamber, where it also passes without the Ignition electrodes 37, 38 would burn. An arc burning between the ignition electrodes 37, 38 is cooled to a greater extent by the proximity of the vessel wall than an arc which has a larger wall distance. The arc thus moves to the location of the combustion chamber, where it finds the greatest possible distance from the vessel wall and thus experiences the least possible cooling. The physical reason for the arc to migrate to the zone of least possible cooling is to be seen in the fact that the charge carrier generation in the arc and at the electrodes increases with increasing temperature and thus the internal resistance of the arc decreases. This ground migration is also supported by the fact that, due to its lower density, the hot gas in the arc migrates upward against gravity, which ultimately leads to a slight arc curvature upward in the case of stationary arcs 19. These physical backgrounds are particularly easy to show in this exemplary embodiment, but they also apply analogously to the other exemplary embodiments.

In the eighth exemplary embodiment shown in FIG. 8, only the left main electrode 17 has an ignition electrode 39 which extends laterally from this main electrode 17 and extends obliquely downward into the area below the free end of the other main electrode 18 up to the glass wall extends. Here too, an ignition spark is formed between the free end of the ignition electrode 39 and the right main electrode 18 as a result of the contact with the glass wall, it can be designed partly as a sliding spark and partly as a flashover spark, this ignition spark or ignition arc then in turn migrating upward and becoming the arc 19 between the main electrodes 17, 18, as shown in FIG. 8 schematic see figure 11 is.

In the ninth embodiment shown in FIG. 9, an indentation 40 of the glass wall is provided between the combustion chamber 12 and the lateral extensions 13, 14. An ignition electrode 41 designed as a metal strip extends along the left extension 13 into this indentation 40, as a result of which a particularly small distance from the left main electrode 17 and a correspondingly low ignition voltage are achieved.

Instead of the ignition electrode 41, other outer electrode shapes, e.g. According to the exemplary embodiments shown in FIGS. 1 and 2, or metallizations occur, these electrodes either extending into the indentation 40 or being arranged in an annular manner therein.

In the tenth exemplary embodiment shown in FIG. 10, a simplified burner vessel 42 without lateral extensions 13, 14 is shown, which in turn contains a flattened or el 1 i psoid-like combustion chamber 43. Two main electrodes 44, 45 extend into this combustion chamber from two opposite sides and, according to FIG. 11, have a round cross section, that is to say they are rod-shaped. The electrode leadthroughs through the walls of the burner vessel 42 must, of course, again be gas-tight. In the area of entry into the combustion chamber 43, the main electrodes 44, 45 each point downwards during operation extending jagged, tapered extensions, which form two ignition electrodes 46, 47. The tips of these ignition electrodes 46, 47 open on the inner wall of the vessel.

Here too, on the one hand, due to the geometry, that is to say the pointed shape of the ignition electrodes 46, 47, and on the other hand because of the jump in voltage, sliding discharges 34 form between the tips of the ignition electrodes 46, 47 along the vessel wall even at relatively low voltages. Due to thermal effects, the arc initiated as a sliding discharge then migrates upwards again and then burns between the main electrodes 44, 45.

The eleventh exemplary embodiment shown in FIGS. 12 and 13 largely corresponds to the tenth exemplary embodiment shown in FIGS. 10 and 11. Separate ignition electrodes 46, 47 are dispensed with, for this purpose correspondingly arranged main electrodes 48, 49 with a triangular or wedge-shaped cross-sectional profile are provided, as shown in FIG. 13. The main electrodes 48, 49 therefore have a downward-pointing pointed edge 50, at which in turn a high field strength is formed at the transition point between the metal of the main electrodes 48, 49 and the material of the vessel wall, so that a sliding discharge 34 is again formed, which that corresponds essentially to the tenth embodiment. After an arc has formed, it in turn migrates upwards and burns at the upper ends of the main electrodes 48, 49, where these are made wider as a result of the wedge shape. This upward migration is further supported by the beveling of the end faces of the main electrodes 48, 49. According to the twelfth exemplary embodiment shown in FIG. 14, however, the bevels of the end faces of the main electrodes 48, 49 can be used can also be dispensed with, the main electrodes 48, 49 shown in FIG. 14 likewise having the cross-sectional shape shown in FIG. 13.

Tungsten and platinum metals are particularly suitable as materials for interior metallizations. All non-oxidizable metals with a melting point above approx. 1000 C can be used for external metal insulations. Are metallizations applied on the outside covered with a temperature-resistant and oxygen-impermeable protective layer, e.g. B. SiOo or a ceramic layer, so less noble metals with melting temperatures above 1100 C can be used, such as Chromium, nickel, molybdenum.

Claims

claims

1. Gas discharge lamp, in particular for motor vehicle headlights, with a burner vessel made of glass or the like containing a gas. , into which two main electrodes protrude via gas-tight electrode bushings, a burning path being formed between the end regions of the main electrodes arranged in the burner vessel, along which an arc is formed during operation, characterized in that means for generating a sliding spark gap (34) are provided along the inner vessel wall and / or a spark gap (32) that is shorter than the firing path as an ignition path, which is spatially separated from the firing path.

2. Gas discharge lamp according to claim 1, characterized gekenn¬ characterized in that the burner vessel (10) consists essentially of a combustion chamber (12) and two extending from this in the opposite direction, each one of the main electrodes (17, 18) containing tubular extensions (13, 14) which have the electrode bushing (15, 16) at opposite end regions.

3. Gas discharge lamp according to claim 1 or 2, characterized in that at least one ignition! electrode (25-27, 29, 33, 35-39, 41, 46, 47, 60, 64) is provided.

4. Gas discharge lamp according to claim 3, characterized gekenn¬ characterized in that the ignition electrode (27) is formed as a separate third electrode with its own gas-tight electrode bushing (28) through the burner vessel (10) and the shorter ignition path is formed towards one of the main electrodes.

5. Gas discharge lamp according to claim 3, characterized gekenn¬ characterized in that the ignition electrode (25, 26, 41, 64) is arranged as a separate third electrode on the outside of the Brenner¬ vessel (10) and to one of the main electrodes (17) towards the ignition path.

6. Gas discharge lamp according to claim 2 and 5, characterized in that the ignition electrode (25, 26, 41) is arranged on one of the tubular extensions (13).

7. The gas discharge lamp as claimed in claim 6, characterized in that the ignition electrode (41) is arranged on a constriction (40) of the tubular extension (12) or extends into it.

8. Gas discharge lamp according to one of claims 5 to 7, characterized in that the ignition electrode (25, 26, 64) engages around one of the two main electrodes (17) in a ring or part 1 ring shape.

9. Gas discharge lamp according to claim 8, characterized gekenn¬ characterized in that the ignition electrode (25, 26, 64) is formed by a metal strip, a metallization or a wire ring on the outside of the burner vessel (10).

10. Gas discharge lamp according to one of claims 4 to 9, characterized in that the ignition electrode (25, 26, 27, 41, 64) is electrically connected to the main electrode (18) not involved in the formation of the ignition path i st.

11. The gas discharge lamp as claimed in claim 3, characterized in that the at least one ignition electrode (29, 33, 35-39, 46, 47, 60) is arranged in the interior of the burner vessel (10, 43).

12. Gas discharge lamp according to claim 11, characterized ge indicates that the ignition electrode (29, 39, 60) is connected to the one main electrode (18 or 17) and up to a point in the vicinity of the other main electrode (17 or 18) which lies below this other main electrode in the operating state.

13. Gas discharge lamp according to claim 12, characterized in that the ignition electrode (39) is designed as a rod-like or wire-like side arm of the one main electrode (17).

14. Gas discharge lamp according to claim 13, daduruch ge indicates that the free end of the ignition electrode (39) opens onto the wall of the burner vessel (10).

15. Gas discharge lamp according to claim 5, 11 or 12, dadurcn characterized in that the ignition electrode (29, 33, 60, 64) is designed as a metallization, which is for connection to a main electrode (18) inside up to its electrode bushing or outside up extends to a connection contact element (68).

16. The gas discharge lamp as claimed in claim 15, characterized in that the metallization forming the ignition electrode (29, 33), at least partially, engages around the main electrode (18), starting from the electrode feedthrough, and in particular is cup-shaped.

17. Gas discharge lamp according to claim 16, characterized in that the main electrode (18) at least partially encompassing the ignition electrode (29, 33) extends substantially to the free end region of this main electrode (18).

18. Gas discharge lamp according to one of claims 15 to 17, characterized in that the ignition electrode (29, 60, 64) is formed at least along the region of the burning path as a strip-like or light reflector-like metallization (31, 62, 66).

19. The gas discharge lamp as claimed in claim 18, characterized in that the light reflector-like metallization (62, 64) is essentially over the lower half of the combustion chamber (12) of the burner vessel in the operating position

(10) extends.

20. Gas discharge lamp according to claim 18 or 19, characterized in that the strip-shaped or light reflector-like metallization (31, 62, 66) extends to a ring-like the other main electrode (17) encompassing metallization ring (63, 67).

21. Gas discharge lamp according to claim 11, characterized in that each of the two main electrodes (17, 18, 44, 45) with an ignition! Electrode (35, 36, 37, 38, 46, 47) is connected, between which the spark gap (32) and / or sliding spark gap (34) is formed as an ignition gap.

22. A gas discharge lamp according to claim 21, characterized in that the ignition electrodes (37, 38, 46, 47) are designed as side arms of the main electrodes (17, 18, 44, 45).

23. A gas discharge lamp according to claim 22, characterized in that the ignition electrodes (37, 38, 46, 47) extend to form a sliding spark gap (34) up to the inner vessel wall.

24. Gas discharge lamp according to claim 22 or 23, characterized in that the ignition electrodes (37, 38, 46, 47) are designed as rod-like or wire-like lateral arms or as tapered lateral formations on the main electrodes (17, 18, 44, 45) .

25. Gas discharge lamp according to one of claims 21 to 24, characterized in that the ignition electrodes (37, 38) run obliquely up to the ignition path and are arranged below the main electrodes (17, 18) during operation.

26. Gas discharge lamp according to claim 21, characterized ge indicates that the two ignition electrodes 835, 36) are formed as metallizations, which extend to the connection with the main electrodes (17, 18) in each case up to their electrode bushings.

27. Gas discharge lamp according to claim 26, characterized ge indicates that the Zündelektrodεn (35, 36) starting from the electrode bushings through the burner vessel (10) the main electrodes (17, 18) each at least partially 1 white se umgrei fen.

28. The gas discharge lamp as claimed in claim 27, characterized in that the central electrodes (17, 18) at least partially encompassing the lead electrodes (35, 36) extend essentially to the free end regions of these main electrodes (17, 18).

29. Gas discharge lamp according to one of claims 15 to 20, 26 to 28, characterized in that the Metallisie¬ rungen inside is a metallization of tungsten or a platinum metal or the outside is a metallization of a ni chtoxi di erbaren metal with a melting point above about 1000 C or a less noble metal coated with an oxygen-impermeable protective layer with a melting point above approx. 1100 ° C.

30. Gas discharge lamp according to claim 1, characterized in that the main electrodes (48, 49) have a cross-sectional profile with a pointed corner, which points downward during operation.

31. Gas discharge lamp according to claim 30, characterized in that the cross-sectional profile is a triangular profile, in particular a wedge-like triangular profile.

32. Gas discharge lamp according to claim 30 or 31, characterized in that the mutually facing end faces of the main electrodes (48, 49) are inclined in opposite directions to their longitudinal axes.

33. The gas discharge lamp as claimed in claim 32, characterized in that the regions of the main electrodes (48, 49) which are closer to one another are wider and the regions which are more distant from one another taper to a point.