CN117334559A

CN117334559A - Anode electrode of gas discharge lamp, method for manufacturing the same, and gas discharge lamp

Info

Publication number: CN117334559A
Application number: CN202310725686.XA
Authority: CN
Inventors: 马库斯·科沃杰伊奇克
Original assignee: Osram GmbH
Current assignee: Osram GmbH
Priority date: 2022-07-01
Filing date: 2023-06-19
Publication date: 2024-01-02
Also published as: DE102022116475A1; JP2024006958A

Abstract

The invention relates to an anode electrode (10) of a gas discharge lamp (14), comprising a crucible-like base part (26) made of an electrically conductive material, wherein the base part (26) provides a receiving opening (30) and a receiving space (32) adjoining the receiving opening (30), wherein a cooling medium having a melting point lower than the electrically conductive material is received in the receiving space (32), and comprising a closing cap (28) for closing the receiving opening (30), wherein the anode electrode (10) comprises a ventilation channel (38) connecting the receiving space (32) to the environment of the anode electrode (10), wherein an opening edge (40) surrounding the receiving opening (30) is welded to a cap edge (42) of the closing cap (28), wherein the ventilation channel (38) is closed by a closing part (44). According to the invention, the ventilation channel (38) is delimited in the circumferential direction of the ventilation channel (38) by a cover edge (42) on the one hand and by an opening edge (40) on the other hand.

Description

Anode electrode of gas discharge lamp, method for manufacturing the same, and gas discharge lamp

Technical Field

The invention relates to an anode electrode of a gas discharge lamp, comprising a crucible-like base part made of an electrically conductive material, wherein the base part provides a receiving opening and a receiving space adjoining the receiving opening, wherein a cooling medium having a melting point lower than the electrically conductive material is received in the receiving space, and comprising a closing cap for closing the receiving opening, wherein the anode electrode comprises a ventilation channel connecting the receiving space to the environment of the anode electrode, wherein an opening edge surrounding the receiving opening is welded to a cap edge of the closing cap, and wherein the ventilation channel is closed by the closing part. Furthermore, the invention relates to a gas discharge lamp having a transparent discharge vessel filled with a gas, an anode electrode arranged in the discharge vessel and a cathode electrode arranged in the discharge vessel, wherein the anode electrode and the cathode electrode are arranged at a predetermined spacing, wherein the gas discharge lamp is aligned in an intended operation such that the anode electrode is arranged vertically above the cathode electrode, wherein the anode electrode is supplied with an electrical anode potential, and the cathode electrode is supplied with an electrical cathode potential, wherein the electrical anode potential is greater than the electrical cathode potential. Finally, the invention also relates to a method of manufacturing an anode electrode of a gas discharge lamp, the method comprising the steps of: manufacturing a crucible-like base portion from a conductive material such that the base portion provides a receiving opening and a receiving space adjacent to the receiving opening; introducing a cooling medium having a melting point lower than that of the conductive material into the accommodating space; manufacturing a closing cap for closing the accommodating opening; introducing a vent channel into the anode electrode, the vent channel connecting the receiving space to the environment of the anode electrode; welding an opening edge surrounding the receiving opening to a lid edge of the closure lid; and the ventilation channel is closed by means of a closure.

Background

Lighting devices comprising gas discharge lamps, anodes of gas discharge lamps and methods of manufacturing anode electrodes are well known in the art and therefore do not substantially require separate literature to prove. Gas discharge lamps of the type in question (sometimes also referred to as gas discharge tubes, arc tubes, etc.) are used to provide light on the basis of supplied electrical energy. For this purpose, the gas discharge lamp has at least two operating electrodes which are arranged in the transparent discharge vessel at predetermined spacing intervals. The discharge vessel is usually hermetically closed and filled with a gas. The operating electrodes are supplied with current, so that in the case of a gas discharge, an arc can be formed between the two operating electrodes.

For this purpose, the operation electrodes can be supplied with the respective electric potentials from the outside via the electric wires, thereby enabling a predetermined voltage to be formed between the operation electrodes. For this purpose, the operating electrodes are typically connected to a suitable ballast which, in addition to providing the respective potential, is able to provide current in a suitable manner for the intended operation, so that the desired gas discharge can take place to generate light.

The discharge vessel is usually formed of a suitable material that is transparent to light, such as glass, in particular quartz glass, alumina ceramic or the like.

The gas in the discharge vessel can be formed from a single gaseous substance or from a gas mixture of a plurality of different gaseous substances. Furthermore, it is of course also possible to provide for the gas to develop into the desired substance at a later operating time by evaporation of solids and/or liquids in the discharge vessel. The gas need not have a fixed composition. For example, the gas composition can depend on the respective operating conditions of the gas discharge lamp. A substance or a mixture of substances, such as metal vapors of sodium, rare earth metals, mercury and/or the like, and if appropriate also halogen, for example in the form of halogen metal vapor lamps or the like, can also be used as gas. Furthermore, in particular in order to facilitate the ignition of the gas discharge lamp, rare gases, such as argon, xenon, krypton, neon and gas mixtures of halogens and other metals and/or the like, can be provided in the gas.

The nature of the gas discharge can be determined by the composition of the gas. In addition, the gas discharge and the operating electrode typically release heat, which also results in an operating pressure in the gas discharge tube.

In order to produce high brightness levels, the gas discharge lamp can be designed in the manner of a high-pressure gas discharge lamp or an ultra-high-pressure gas discharge lamp. In this case, the gas discharge mainly occurs in the region where the arc is formed between the operation electrodes, so that the arc discharge can be provided. The high-pressure gas discharge lamp may be used, for example, as a mercury vapor lamp, a xenon arc lamp or a krypton arc lamp or the like. In the intended operation, a gas pressure of approximately 1MPa can be present in such a gas discharge lamp. In the case of ultra-high pressure gas discharge lamps, such as high pressure mercury vapor lamps, xenon short arc lamps or the like, the pressure in the gas can even reach about 10MPa or more, such as 20MPa or even 30MPa, during the intended operation.

In particular in the case of high-pressure gas discharge lamps and ultra-high-pressure gas discharge lamps, the operating electrode usually comprises or is formed from tungsten. The electrodes can be of pin or rod type design, and can optionally have coils. In the case of such gas discharge lamps, the current density in the gas is usually so great that the low-voltage discharge can immediately become an arc discharge at start-up, so that the internal pressure increases further due to the temperature rise and any evaporation of the filling components. In addition to the operating electrode, an ignition electrode may be provided, for example in the case of a mercury vapor lamp or the like.

Due to the high current density during gas discharge, the opposing operating electrode may be exposed to high thermal stresses during expected operation, which can lead to a change in the respective electrode states of the at least two operating electrodes.

In principle, a gas discharge lamp can be supplied with a DC voltage or an AC voltage. However, especially in the case of high powers, at least in some cases, only direct voltage is usually supplied to the gas discharge lamp. In this case, one of the operation electrodes (e.g., the cathode electrode) is supplied with a first potential, and the second one of the operation electrodes (i.e., the anode electrode) is supplied with a second potential that is greater than the first potential. In this case, the gas discharge lamp is designed such that the anode electrode is arranged above the cathode electrode in the vertical direction. Thus, particularly in the region of the anode electrode, particularly high thermal stresses can be present, whereas in contrast stresses of the cathode electrode can be relieved. In view of the high thermal stress of the anode electrode, for example, it is known from JP 2009-140793A that the anode electrode is designed as a hollow body, so that the anode electrode has an accommodation space for the metal. The melting point of the metal contained in the containing space is lower than the material forming the anode electrode or the hollow body of the anode electrode. In the intended operation, the metal disposed in the accommodation space can be changed into a liquid or gaseous state, thereby improving heat dissipation of the tip of the anode electrode facing the cathode electrode by providing convection. Whereby the load capacity of the anode electrode can be increased.

Even though this teaching has proven its value, there are drawbacks. In the manufacture of an anode electrode according to JP 2009-140793A, it has proved problematic that the anode electrode must have an air supply hole. At the end of the anode electrode manufacturing process, the gas supply hole is closed by means of a metal droplet. In particular in the case of tungsten-based anode electrodes, the production of the gas supply holes has proven to be critical, since tungsten-based conductive materials are often extremely brittle and hard. The result is a technically very complex manufacturing process, which, in addition, leads to a non-negligible reject rate.

Disclosure of Invention

The basic object of the present invention is to provide an improved anode electrode with which the above-mentioned disadvantages, in particular in respect of manufacturing the anode electrode, can be reduced.

With respect to the anode electrode of the type in question, the invention proposes in particular: the venting channel is delimited in the circumferential direction of the venting channel by the cover edge on the one hand and the opening edge on the other hand.

In relation to a gas discharge lamp of the type in question, the invention proposes in particular: the anode electrode is designed according to the present invention.

With respect to the method of the type in question, the invention proposes in particular: the vent channel is designed such that the vent channel is delimited in the circumferential direction of the vent channel by the cap edge on the one hand and the opening edge on the other hand.

Furthermore, the invention is based on the following idea: if the venting channel is formed at least in the lid edge or at least in the opening edge, drilling of the venting channel can be avoided. This allows the venting channel to be formed on at least one surface (i.e. the lid edge or the opening edge) by a suitable material removal method before the closing lid closes the receiving space. Thus, for example, the vent channel may be obtained by milling in a chip removal method, as well as by means of laser removal, water jet removal and/or the like. Thus, the problem of drilling holes in hard and brittle materials can be avoided, so that waste products in the manufacturing process of the anode electrode can be reduced as a whole. Furthermore, the present invention can tolerate flaking of material during vent channel fabrication, as material flaking occurs in areas that have substantially no impact on the subsequent intended use of the anode electrode. This deviation proves to be substantially irrelevant for the subsequent intended use according to the design of the invention. Thus, the expenditure involved in manufacturing the ventilation channel can be greatly reduced. Furthermore, since substantially only surface finishing is required, the invention also largely avoids the formation of cracks in the material of the base part or of the closure cap. Therefore, the present invention not only improves the reliability of the anode electrode, but also ensures fewer scrap parts. Therefore, the invention can save materials and cost.

In this case, it has proven to be advantageous if the anode electrode is of two-part design, i.e. has a crucible-like base part on the one hand and a closure cap for closing the receiving opening on the other hand. By means of the receiving opening, a cooling medium can be introduced into the receiving space during the production of the anode electrode. Only when the cooling medium is arranged in the receiving space, the receiving opening is closed by means of the closing cap. The edge of the opening surrounding the receiving opening is then welded to the edge of the cover of the closure. Once the opening edge is welded to the cover edge, the only remaining venting connection between the receiving space and the environment of the anode electrode is the venting channel. The vent channel may allow for fluid compensation during anode electrode manufacturing, such as fluid compensation based on temperature changes. Particularly if the electrically conductive material is a material with a very high melting point, such as tungsten, molybdenum or the like, a large temperature difference occurs during the manufacturing process, so that, for example, a part of the space of the receiving space which is not filled with the cooling medium is still fluidly connected to the environment of the anode electrode via the ventilation channel. The ventilation channel is closed off from the outside by the closure only when the compensation process is sufficiently completed or reaches a predetermined state.

For example, the closure can be a metal melt which is placed in the form of drops or the like from the outside on the mouth opening of the venting channel and is preferably connected to the material of the closure and/or the base part by a corresponding welding process. The receiving space can thus be completely sealed off from the environment of the anode electrode. Thus, during expected operation, escape of the cooling medium from the accommodation space into the discharge vessel can be largely avoided, thereby disturbing the functioning of the gas discharge lamp. At the same time, it is thus ensured that the cooling medium remains in the anode electrode during the intended operation or during use, so that the desired cooling function can be reliably provided during the intended service life.

The cover edge and the opening edge are preferably designed in a manner that matches each other, so that a reliable connection can be achieved. Furthermore, the ring welding can be realized in a simple manner, for example using inert gas welding or the like.

Since the vent channel is delimited in the circumferential direction by the lid edge and the opening edge, for example, only one recess may be provided in the opening edge or in the lid edge to provide the vent channel. Of course, it is also possible to provide corresponding recesses on both sides of the two edges, which recesses are aligned accordingly in the assembled state such that they together can form a ventilation channel. However, it is preferred that the recess is formed only in the lid rim.

The anode electrode is preferably of substantially cylindrical design, with a recess formed in one end of the cylinder. In order to close the receiving opening, the cover edge is arranged opposite the opening edge, so that the two edges can be connected from the outside by means of welding. In this case, it is preferable to provide that the welding does not close the ventilation channel yet. Only after the compensation process (in particular the temperature, the gas expansion and/or the like) has been sufficiently eliminated can the opening be closed off from the outside by the closure (for example in the form of an additional weld point), in particular in a material-fitting manner. Thus, the anode electrode is prepared to a large extent for intended use.

In principle, the ventilation channel can have a circular and/or angular cross section. It is particularly advantageous if the ventilation channel has an approximately rectangular cross section, which can be formed in a simple manner by milling in the opening edge and/or the cover edge. In principle, an approximately triangular cross section or the like may also be provided. For example, the shape of the cross section may be selected according to the tool, machining method, etc. used to make the groove. The diameter of the vent channel can be, for example, about 1mm to about 2mm.

The vertical direction refers to a direction substantially along the direction of gravity.

According to a further development, it is proposed that the closing cap is formed from an electrically conductive material with a higher melting point than the cooling medium, in particular from the same material as the base part. Therefore, the sealing cap can effectively promote the conductivity of the electrode. In particular, the closing cap can be used to provide an electrical connection of the anode electrode. In principle, however, the closing cap need not be made of the same electrically conductive material as the base part. Advantageously, however, the closure cap is formed from the same material as the base portion. Furthermore, this is particularly advantageous for high thermal stresses that occur during expected operation. Therefore, the reliability of the anode electrode can be further improved.

Preferably, the cooling medium comprises at least partially a metal. The cooling medium can include, for example, copper, silver, gold, alloys thereof, and/or the like. The cooling medium is preferably formed only partly of metal. It is particularly advantageous if the cooling medium is selected such that chemical interactions with the electrically conductive material of the base part and of the closure cap are largely avoided. This can be achieved with the above-mentioned materials, in particular in the case of using tungsten or a tungsten alloy as the conductive material of the base part and/or the closing part.

Furthermore, it is proposed that the cooling medium at least partially comprises an electrode gas. The electrode gas is preferably an inert gas which preferably does not interact with the electrically conductive material of the base part or the closing cap, particularly preferably also with the cooling medium, during the intended use of the anode electrode. In particular, no chemical action occurs. The electrode gas used can be, for example, a rare gas (e.g., argon, xenon, neon, etc.). Of course, it is also possible to provide a gas mixture which fills the remaining part of the accommodation space which is not filled with metal in solid or liquid form. It is particularly advantageous if the electrode gas is a gas which is used anyway during the welding process for connecting the closure cap to the base part (for example, in an inert gas welding process capable of using argon).

The conductive material preferably comprises tungsten. Tungsten is particularly suitable as a material for the base part, preferably also for the closure part, due to its physical properties, in particular its particularly high melting point. The advantages of the invention are particularly evident when tungsten is used, since tungsten is particularly unsuitable for drilling as a hard and brittle material. The invention makes it possible to avoid drilling, so that particularly advantageous production can be achieved exactly with this material.

According to a further development, it is proposed that the opening edge is of planar design. The opening edge is preferably substantially completely flat. The opening edge can provide an annular edge surface that can be in good contact with a correspondingly designed lid edge. The edge width of the opening edge can preferably substantially correspond to the wall thickness of the base part. However, the edge width selected can also be different as desired.

It is particularly advantageous if the cover rim has a recess which at least partially forms the ventilation channel. The vent channel is preferably formed primarily by a recess in the lid rim. This has the following advantages: the process of manufacturing the vent channel need essentially only be performed on the closure cap. Since only the closing cap has to be machined, by a suitable arrangement of the closing cap an advantageous and reliable manufacture of the venting channel can be achieved. For example, it can be provided that the cover rim has a material thickness suitable for producing a recess, so that the processing of the closure can be reliably effected without damaging the closure.

Furthermore, it is proposed that the closing cap has, on the outside facing away from the receiving opening, a connecting means for mechanically connecting the closing cap to the electrode terminals of the gas discharge lamp. Thus, it is ensured that the electrical connection of the anode electrode within the gas discharge lamp is achieved in a simple manner. For example, it can be provided that the closure cap has a connection means on the outsideBlind holeThe connecting rod of the gas discharge lamp can be arranged in the blind hole. The connecting rod can be formed of an electrically conductive material (e.g., molybdenum, etc.). The connecting rod can be connected to the closure cap by welding, pressure and/or the like. Thus, by means of the connecting rod, it is also possible to simultaneously position the anode electrode in a desired position within the discharge vessel of the gas discharge lamp. Thus, both an electrical connection of the anode electrode and a reliable mechanical positioning of the anode electrode can be achieved.

According to a further development, it is proposed that on the inner side facing the receiving opening, the closure cap has at least one biasing element (Absatz) for centering the closure cap with respect to the receiving opening. For example, the biasing member can be formed by a web or the like, and the longitudinal extent of the biasing member is selected in accordance with the inner diameter of the receiving opening, so that reliable centering can be achieved. In particular if the receiving opening is of substantially circular design or has a substantially circular inner diameter, provision can be made for the biasing element to be designed as a substantially cylindrical biasing element which engages in the receiving opening in the closed state. In particular in the region of the ventilation channel, provision can be made for the biasing element to have a corresponding recess in order to achieve a ventilation connection of the ventilation channel with the receiving space in the closed state. However, the recess or depression formed in the lid rim that provides the vent passage may also extend at least partially into the biasing member. This makes it possible in a simple manner to provide a connection to the ventilation channel despite the biasing member.

Furthermore, it is proposed to hermetically close the accommodation space by welding the opening edge to the cover edge. In particular, this does not involve ventilation channels. The ventilation channels are preferably individually closed. However, by means of welding, it is ensured that a sealed closure is achieved at least outside the region of the ventilation channel. Thus, a sealed closure of the receiving space can be achieved for the subsequent intended use.

With respect to the method of the type in question, it is also proposed to provide the venting channel by forming a groove at least in the lid edge or at least in the opening edge. In principle, it is only necessary to provide a recess in the lid edge or in the opening edge. However, the present invention is not limited thereto, and it can be prescribed that a groove is formed in the lid edge and in the opening edge. In this case, it is preferably provided that the two recesses in the lid edge and in the opening edge face one another during closing, so that they can together form a ventilation channel. However, it is particularly advantageous if the recess is formed only in the cover rim.

The advantages and effects indicated for the anode electrode according to the invention apply equally to the gas discharge lamp according to the invention and to the method according to the invention and vice versa. Thus, method features may also be expressed as apparatus features, and vice versa.

The features and feature combinations mentioned in the description above and the features and feature combinations mentioned in the following description of the figures and/or individually shown in the figures can be used not only in the respectively specified combination but also in other combinations without departing from the scope of the invention.

The exemplary embodiments explained below are preferred embodiments of the present invention. The features and feature combinations indicated in the description above and the features and feature combinations mentioned in the description of the exemplary embodiments below and/or individually shown in the drawings can be used not only in the respectively specified combination but also in other combinations. Therefore, the invention should also be regarded as including or disclosing embodiments which are not explicitly shown and explained in the drawings, but which are derivative and can be produced by means of separate combinations of features of the explained embodiments. The features, functions and/or effects described by means of the exemplary embodiments can each individually represent the respective features, functions and/or effects of the present invention, which should be regarded as independent of each other and also individually urge the present invention independent of each other. Thus, the exemplary embodiments are also intended to include combinations other than those described in the illustrated embodiments. Furthermore, the described embodiments may be supplemented by other features, functions, and/or effects of the invention that have been described.

Drawings

In the drawings, like reference numerals denote like features or functions.

In the drawings:

fig. 1 shows an ultra-high-pressure gas discharge lamp in a schematic cross-sectional view, with two operating electrodes arranged in a gas discharge vessel;

fig. 2 shows in a schematic side view an anode electrode as one of the operating electrodes of the gas discharge lamp shown in fig. 1;

FIG. 3 shows a schematic cross-sectional view of the anode electrode shown in FIG. 2 along line III-III in FIG. 2;

fig. 4 shows a schematic cross-section as in fig. 3, but according to the anode electrode shown in fig. 2 along the section line IV-IV in fig. 3;

fig. 5 shows a schematic perspective view of the outside of the closing cap of the anode electrode shown in fig. 2;

fig. 6 shows a schematic perspective view as in fig. 5 from the inside of the closure cap;

fig. 7 shows a detail of the schematic view shown in fig. 2, in which the welding of the closing cap to the base part of the anode electrode is shown; and

fig. 8 shows a schematic side view as in fig. 7, in which the mouth opening of the ventilation channel is closed with a closure in the region of the weld seam.

Detailed Description

Fig. 1 shows a gas discharge lamp 14 in a schematic cross-sectional view, which in this case is designed as an ultra-high pressure mercury lamp. The gas discharge lamp 14 comprises a transparent discharge vessel 18, which in this case is formed from quartz glass. The anode electrode 10 and the cathode electrode 12 are disposed in the discharge tube 18 as operation electrodes. The two operating electrodes are arranged at a distance from each other, in this case a distance of about 11mm. The distance can vary depending on the design of the gas discharge lamp 14. In this case, the discharge vessel 18 is of approximately cylindrical design and has an outer diameter of approximately 130 mm. The height dimension of the discharge vessel 18 is about 160mm. These dimensions may also vary depending on the design.

In the intended operation, the gas discharge lamp 14 is oriented such that the anode electrode 10 is disposed vertically above the cathode electrode 12. In the intended operation, the anode electrode 10 is supplied with an electrical anode potential 22 and the cathode electrode 12 is supplied with an electrical cathode potential 24. The electric anode potential 22 is greater than the cathode potential 24. Thus, in the intended operation, the gas discharge lamp 14 is supplied with a DC voltage. In the embodiment considered, it is envisaged that the electrical power of the gas discharge lamp 14 is about 12kW. Depending on the design, the power can also be lower or higher.

Further, a gas 16 surrounding the anode electrode 10 and the cathode electrode 12 is provided within the discharge tube 18. In this case, the gas 16 contains mercury vapor. However, other gas components may be present here, depending on the design. Alternative gases or gas mixtures may also be provided as gas 16.

The anode electrode 10 is mechanically and electrically connected to an anode terminal 52 which not only serves as an electrical connection for supplying the anode potential 22, but at the same time also positions the anode electrode 10 within the discharge vessel 18. The same applies to the cathode electrode 12, which is mechanically and electrically connected to the cathode terminal 54. Further, the cathode terminal 54 is used to supply the cathode potential 24 to the cathode electrode 12 and to position the cathode electrode 12 within the discharge tube 18. The anode terminal 52 and the cathode terminal 54 can be made of a suitable material (e.g., molybdenum, etc.). In this case the anode terminal 52 and the cathode terminal 54 are of substantially rod-shaped design and electrical terminals (not shown) are provided at opposite ends of each electrode for connecting the gas discharge lamp 14. The anode terminal 52 and the cathode terminal 54 pass through the wall of the discharge tube 18 so that they can be electrically contacted. The discharge vessel 18, in particular the discharge vessel 18 associated with the leads of the anode terminal 52 and the cathode terminal 54, is implemented in a sealed manner to prevent escape of the gas 16, in particular when the gas discharge lamp 14 is in the intended operation. Gas is likewise unable to enter the discharge vessel 18 from the environment of the gas discharge lamp 14.

Fig. 2 shows the anode electrode 10 of the gas discharge lamp 14 shown in fig. 1 in a schematic side view. Fig. 2 shows that the anode electrode 10 has a crucible-like base portion 26 made of an electrically conductive material. In this case, the conductive material includes tungsten. The base part has an electrode tip 60 which is arranged facing the cathode electrode 12 in the state in which the anode electrode 10 is arranged in the gas discharge lamp 14. A closing cap 28 is provided at the end of the anode electrode 10 opposite the electrode tip 60, which closing cap will be explained in more detail below. Furthermore, as can be seen from fig. 2, the mouth opening of the ventilation channel 38 is formed substantially centrally between the base part 26 and the closure cap 28. This will also be explained in more detail below.

Fig. 3 shows the anode electrode 10 in a schematic cross-sectional view along the line III-III in fig. 2. As can be seen from fig. 3, the base portion 26 provides a receiving opening 30 and a receiving space 32 adjoining the receiving opening 30. A cooling medium having a melting point lower than that of the conductive material (tungsten in this case) is accommodated in the accommodating space 32. In this case the cooling medium comprises a metal 34, which in this case is formed of silver or a silver alloy. In alternative embodiments, metals (e.g., silver, gold, etc.) can be provided herein, and optionally corresponding alloys can also be provided herein. Furthermore, it can be seen that the accommodation space 32 is not completely filled with metal 34. An electrode gas 36 (in this case argon) is disposed between the opening edge 40 of the receiving opening 30 and the metal 34. This will be explained in more detail below. In alternative embodiments, some other gases (preferably inert gases, in particular noble gases), gas mixtures and/or the like can also be provided herein.

Furthermore, as can be seen from fig. 3, the receiving opening 30 is closed by means of a closing cap 28. The vent passage 38 connects the accommodation space 32 to the environment of the anode electrode 10. Furthermore, as can be seen from fig. 3, an opening edge 40 surrounding the receiving opening 30 is formed in the region of the receiving opening 30.

In the embodiment considered, the anode electrode 10 is designed to have a substantially cylindrical cross section. The opening edge 40 surrounding the receiving opening 30 is formed by means of a wall (not marked) of the base part 26. In this case, the opening edge 40 is of substantially circular design, more specifically, approximately perpendicular to the longitudinal axis 62 of the anode electrode 10. In the embodiment considered, it is envisaged that the radial extent of the opening edge 40 corresponds approximately to the radial thickness of the wall of the base portion 26.

Furthermore, as can be seen from fig. 3, the closure cap 28 has a cap edge 42, which is also of substantially annular design. In the closed state, the opening edge 40 is in contact with the cover edge 42. As will be explained below, a material-fitting connection is formed around the edges 40, 42 that are in contact with each other in order to create a good, reliable and sealed connection between the base portion 26 and the closure cap 28, which connection is preferably fluid-tight.

The upper right end region of fig. 3 also shows a vent channel 38 which connects the accommodation space 32 to the environment of the anode electrode 10. In the intermediate production state or production intermediate state of the anode electrode 10 (as shown in fig. 3), the ventilation channel 38 is open, so that a fluid connection exists between the accommodation space 32 and the environment of the anode electrode 10. This will be explained in more detail below.

Fig. 4 shows a cross-sectional view of the anode electrode 10 as in fig. 3. Although fig. 4 shows a cross-sectional view of the anode electrode 10 shown in fig. 2 rotated approximately 90 degrees. Thus, in essence, the illustration in fig. 4 differs from that in fig. 3 only in that the vent channel 38 is not visible. Thus, this is a cross-sectional view of the anode electrode 10 shown in fig. 2 but taken along the line IV-IV in fig. 3.

Furthermore, it can be seen from fig. 3 and 4 that on the outer side 48 (fig. 5) facing away from the receiving opening 30, the closing cap 28 has connection means in the form of a blind hole 50 for the mechanical and electrical connection of the closing cap 28 to the anode terminal 52 of the gas discharge lamp 14.

Fig. 5 and 6 each show a perspective view of the closure cap 28. Fig. 5 shows a perspective view of the outer side 48 of the closure cap 28. A blind hole 50 for connection to an anode terminal 52 is shown. In this case, the closing cap 28 is made of the same material (i.e., tungsten) as the base portion 26. In addition, it can be seen that the closure cap 28 has a recess 46.

Fig. 6 shows a perspective view of the inner side of the closure cap 28, which in the assembled state faces the receiving opening 30. It can be seen that the closure cap 28 provides a cap edge 42, which cap edge 42 is in contact with the opening edge 40 in the assembled state. Further, as can be seen in fig. 6, a groove 46 extends radially inwardly from the outer circumference of the closure cap 28 or cap rim 42. In this case, the recess 46 is of substantially groove-shaped design. This can be achieved, for example, by milling or other suitable material removal methods. In principle, however, it can also be provided that the closure cap 28 is produced integrally with the recess 46 in the cap rim 42 in a single production step.

As can be seen from fig. 3 in combination with fig. 6, the venting channel 38 formed by the recess 46 is delimited in the circumferential direction of the venting channel 38 by the cap edge 42 on the one hand and by the opening edge 40 on the other hand (fig. 3). That is, the walls of the vent channel 38 are formed by the lid edge 42 and the opening edge 40. Outside the recess 46, both the opening edge 40 and the cover edge 42 are of substantially planar design.

Furthermore, as can be seen from fig. 3, 4 and 6, on the inner side 56 facing the receiving opening 30, the closure cap 28 has a biasing element 58 for centering the closure cap 28 relative to the receiving opening 30. In the embodiment considered, the biasing member 58 is formed to mainly surround the longitudinal axis 62 (not shown) of the closing cap 28 and the anode electrode 10. In the region of the recess 46, the biasing element 58 is cut off in order to be able to establish a fluid connection between the receiving space 32 and the environment of the anode electrode 10 via the ventilation channel 38. In alternative embodiments, it is also contemplated that the groove 46 extends into the biasing member 58, so that the biasing member 58 is only interrupted by the groove 46.

Hereinafter, the manufacture of the anode electrode 10 will be explained in more detail with reference to fig. 7 and 8, fig. 7 and 8 respectively showing detailed views of the anode electrode 10 at different stages of its manufacture corresponding to the illustration of fig. 2.

First, as shown in fig. 3 and 4, the crucible-like base portion 26 is made of tungsten. Thus, the base portion 26 provides the accommodation opening 30 and the accommodation space 32 adjacent to the accommodation opening 30. Then, the metal 34 is introduced into the accommodation space 32 through the accommodation opening 30.

The closing cap 28 for closing the receiving opening 30 can be produced independently of this, for example in parallel with the production of the base part 26. In this case, too, the closing cap 28 is made of tungsten. In this case, the closure cap 28 can first be produced in a single method step, as shown in fig. 4.

The venting channel 38 is formed in the closure cap 28 such that the venting channel 38 is delimited in the circumferential direction of the venting channel 38 by a cap edge 42 on the one hand and by an opening edge 40 on the other hand. For this purpose, the venting channel 38 is provided by forming a recess 46 in the cover rim 42. In principle, in alternative embodiments, it can also be provided that a recess 46 is formed in the opening edge 40. Further, a combination of these approaches can be provided.

As shown in fig. 3 and 4, the base portion 26 is then closed by means of a closure cap 28. Here, it can be seen from fig. 2 that the mouth opening of the ventilation channel 38 is still temporarily open. In this case, the sealing of the anode electrode 10 occurs in an argon atmosphere. In this case, it has proved to be advantageous if the electrode gas 36 is likewise formed essentially of argon.

As shown in fig. 7, the closure cap 28 is then placed on the base portion 26, thereby closing the receiving opening 30, and the opening edge 40 surrounding the receiving opening 30 is welded to the cap edge 42 of the closure cap 28. During this welding process, the mouth opening of the vent channel 38 remains open, thereby ensuring that the receiving space 32 remains connected to the environment of the anode electrode 10. This allows pressure compensation of thermal stresses caused by welding. In addition, steam that occurs during the welding process and has entered the receiving space 32 can escape at least partially into the environment of the anode electrode 10 via the ventilation channel 38.

In this case, the welding is performed by inert gas welding under an argon atmosphere. Therefore, it has proven advantageous that the electrode gas 36 is also argon. Purging the containment space 32 with argon can be provided during or after welding. After the weld has been applied and the predetermined thermal state of the anode 10 has been reached according to fig. 7, the mouth opening of the ventilation channel 38 is closed with a closing portion 44. In the embodiment considered, this is likewise a welding operation, by means of which a material-fitting connection with the closure cap 28 and the base part 26 and the weld seam applied thereto can be achieved. The receiving space 32 is thus sealed off from the environment of the anode electrode 10.

The anode electrode 10 is thus completed and can be used for further processing of the gas discharge lamp 14.

Even though only a single vent channel 38 is provided in the embodiment under consideration, a plurality of vent channels 38 may be provided in alternative embodiments. The vent channels need not be of the same design, but are preferably of substantially the same design. In this regard, it will be apparent to those skilled in the art how to adjust the fabrication of the anode electrode 10 accordingly.

Even if inert gas welding is proposed for the manufacture of the anode electrode 10, alternatively, for example, the use of laser-based welding or electron beam welding or the like may be provided for closing at least the mouth opening of the vent channel 38.

In summary, it has proven advantageous if the anode electrode 1 according to the invention can have a smaller size than the prior art. Furthermore, the ventilation channel 38 can be manufactured in a more flexible and simpler manner than in the prior art and can also be arranged in a variable position. In summary, the manufacture of the anode electrode 10 according to the invention has proved to be significantly simplified with respect to the prior art, in particular in respect of the use of brittle and hard materials, such as tungsten. The preparation method can remarkably reduce the formation of cracks. Finally, the manufacturing can be further simplified, since the welding step of connecting the closing cap 28 to the base portion 26 and the welding step of closing the mouth opening of the ventilation channel 38 are arranged substantially close to each other.

The exemplary embodiments are merely to explain the present invention and are not intended to limit the present invention.

List of reference numerals

10. Anode electrode

12. Cathode electrode

14. Gas discharge lamp

16. Gas and its preparation method

18. Discharge tube

20. In the vertical direction

22. Anodic potential

24. Cathode potential

26. Base portion

28. Closure cap

30. Accommodating opening

32. Accommodation space

34. Metal material

36. Electrode gas

38. Ventilation channel

40. Edge of opening

42. Cover edge

44. Closure part

46. Groove

48. Outside is provided with

50. Blind hole

52. Anode terminal

54. Cathode terminal

56. Inside of the inner side

58. Biasing member

60. Electrode tip

62. Longitudinal direction

Claims

1. An anode electrode (10) of a gas discharge lamp (14), comprising a crucible-like base part (26) made of an electrically conductive material, wherein the base part (26) provides a receiving opening (30) and a receiving space (32) adjoining the receiving opening (30), wherein a cooling medium having a melting point lower than the electrically conductive material is received in the receiving space (32), and the anode electrode comprises a closing cap (28) for closing the receiving opening (30), wherein the anode electrode (10) comprises a ventilation channel (38) connecting the receiving space (32) to the environment of the anode electrode (10), wherein an opening edge (40) surrounding the receiving opening (30) is welded to a cap edge (42) of the closing cap (28), wherein the ventilation channel (38) is closed by a closing part (44),

wherein,

the ventilation channel (38) is delimited in the circumferential direction of the ventilation channel (38) on the one hand by the cover edge (42) and on the other hand by the opening edge (40).

2. The anode electrode according to claim 1,

wherein,

the closing cap (28) is formed of an electrically conductive material having a higher melting point than the cooling medium.

3. The anode electrode according to claim 1 or 2,

wherein,

the cooling medium comprises at least in part a metal (34).

4. The anode electrode according to claim 1 or 2,

wherein,

the cooling medium includes, at least in part, an electrode gas (36).

5. The anode electrode according to claim 1 or 2,

wherein,

the conductive material comprises tungsten.

6. The anode electrode according to claim 1 or 2,

wherein,

the wall of the vent channel (38) is formed by the cover edge (42) and the opening edge (40).

7. The anode electrode according to claim 1 or 2,

wherein,

the vent channel (38) has a rectangular cross section.

8. The anode electrode according to claim 1 or 2,

wherein,

the opening edge (40) is of flat design.

9. The anode electrode according to claim 1 or 2,

wherein,

the cover rim (42) has a recess (46) for at least partially forming the vent channel (38).

10. The anode electrode according to claim 1 or 2,

wherein,

on an outer side (48) facing away from the receiving opening (30), the closing cap (28) has a connecting device (50) for mechanically connecting the closing cap (28) to an electrode terminal (52) of the gas discharge lamp (14).

11. The anode electrode according to claim 1 or 2,

wherein,

on an inner side (56) facing the receiving opening (30), the closing cap (28) has at least one biasing element (58) for centering the closing cap (28) relative to the receiving opening (30).

12. The anode electrode according to claim 1 or 2,

wherein,

-hermetically closing the accommodation space (32) by welding the opening edge (40) to the cover edge (42).

13. The anode electrode according to claim 1,

wherein,

the closing cap (28) is formed of the same material as the base portion (26).

14. A gas discharge lamp (14) having a transparent discharge vessel (18) filled with a gas (16), an anode electrode (10) arranged in the discharge vessel (18) and a cathode electrode (12) arranged in the discharge vessel (18), wherein the anode electrode (10) and the cathode electrode (12) are arranged at predetermined spacing intervals, wherein the gas discharge lamp (14) is aligned in an intended operation such that the anode electrode (10) is arranged above the cathode electrode (12) in a vertical direction (20), wherein the anode electrode (10) is supplied with an electrical anode potential (22), the cathode electrode (12) is supplied with an electrical cathode potential (24), wherein the electrical anode potential (22) is larger than the electrical cathode potential (24),

wherein,

the anode electrode (10) is designed as an anode electrode as claimed in any one of claims 1-13.

15. A method of manufacturing an anode electrode (10) of a gas discharge lamp (14), the method comprising the steps of:

-manufacturing a crucible-like base part (26) from an electrically conductive material such that the base part (26) provides a receiving opening (30) and a receiving space (32) adjoining the receiving opening (30),

introducing a cooling medium having a melting point lower than that of the electrically conductive material into the accommodation space (32),

-manufacturing a closing cap (28) for closing the containing opening (30),

introducing a ventilation channel (38) into the anode electrode (10), which connects the accommodation space (32) to the environment of the anode electrode (10),

-welding an opening edge (40) surrounding the receiving opening (30) to a lid edge (42) of the closing lid (28), and

closing the ventilation channel (38) by means of a closure (44),

wherein,

the ventilation channel (38) is designed such that the ventilation channel (38) is delimited in the circumferential direction of the ventilation channel (38) by the cover edge (42) on the one hand and the opening edge (40) on the other hand.

16. The method according to claim 15,

wherein,

the venting channel (38) is provided by forming a groove (46) at least in the cover edge (42) or at least in the opening edge (40).