WO2001035442A1

WO2001035442A1 - Discharge lamp comprising an electrode holder

Info

Publication number: WO2001035442A1
Application number: PCT/DE2000/003516
Authority: WO
Inventors: Rainer Kling; Reinhold Wittkötter
Original assignee: Patent-Treuhand-Gesellschaft für elektrische Glühlampen mbH
Priority date: 1999-11-05
Filing date: 2000-10-06
Publication date: 2001-05-17
Also published as: DE19953533A1; TW495798B

Abstract

The invention relates to a discharge lamp (1) which is preferably equipped for dielectrically hindered discharge. The invention is characterized in that a holder (10) is used in order to hold an electrode (6) in a position and to secure said electrode. Said electrode is located at a distance from the walls (3) of the discharge chamber (2) pertaining to the discharge lamp (1).

Description

Discharge lamp with electrode holder

Technical field

The invention relates to a discharge lamp with a discharge space filled with a discharge medium and with an electrode running in the discharge space at a distance from the vessel walls.

Discharge lamps with a dielectric barrier discharge are a special type of discharge lamp. Here, the electrode and / or a counter electrode or a plurality of counter electrodes are separated from the discharge in the discharge space by at least one dielectric. The invention is not exclusively directed, but preferably, to discharge lamps for dielectrically impeded discharges.

State of the art

In such discharge lamps, a voltage is applied between the electrode and the counter electrode, which is also located in the discharge space or at the discharge space, as a result of which a discharge occurs between the electrode and the counter electrode in the discharge medium. During this discharge incoherent radiation is released. Depending on the type of lamp structure and in particular the discharge medium, ultraviolet or infrared radiation or visible light is emitted. Such a lamp is described for example in DE 196 36 965 AI. A distinction is made between so-called bipolar and so-called unipolar discharge lamps.

In the case of a unipolar discharge lamp, one of the two electrodes permanently forms the anode and the other electrode forms the cathode. It is sufficient to separate the anode from the discharge by the dielectric. A wall of the discharge space can also serve as the dielectric. In this case, only the cathode is located in the discharge space, whereas the anode or the anodes are applied to the outside of the wall. This can be, for. B. are strips of a gold or platinum paste, which are printed directly on the wall.

In the case of the bipolar discharge lamp, the two electrodes are not distinguished from one another and both are shielded by a dielectric. By appropriate voltage changes, one electrode and sometimes the other electrode form the anode.

The discharge lamps are preferably fed with an in principle unlimited sequence of extremely short voltage pulses with a high repetition frequency. Please refer to W094 / 23442.

It is clear that successful and efficient discharge depends on the distance between the electrode and the counter electrodes. This applies in particular to discharge lamps with a dielectric barrier discharge, in which the efficiency depends strongly on the precise geometry of the discharge regions in the discharge space. Because of this dependence on the electrode geometry, even small changes in the position of an electrode would lead to a large reduction in the efficiency of the discharge lamp. Presentation of the invention

It is therefore an object of the present invention to provide a discharge lamp in which a precise fit of the electrode in the discharge space is ensured in a simple manner.

This object is achieved in that the discharge lamp has a holder made of non-conductive material, which fixes the electrode at a predetermined position in the discharge space.

The electrode can preferably have an elongated shape that extends essentially in a main direction of extension. The exact shape of the electrode is arbitrary. So it can be longitudinal strips, waveforms, for example in a sinusoidal shape, zigzag electrodes, a coil or the like.

Accordingly, the holder preferably has an elongated support element which extends in the main direction of extension of the electrode and which supports the electrode in at least one partial area. For example, the support element can be designed such that the electrode is supported only in one end region. Of course, the support element can, however, also be so long that the electrode is supported over the entire length.

The support element is, for example, a support rod or a support tube. However, it can also be an elongated, plate-shaped support element or the like.

In a particularly preferred embodiment, the electrode extends helically around the support element on at least a partial area of the longitudinal extent. The advantages of this spiral electrode and the advantages resulting structure of the discharges are shown in the previously cited DE 196 36 965 AI.

The electrode can be applied to the holder or an element of the holder in the form of a correspondingly structured conductive coating, for example made of gold or platinum paste. So z. B. be applied in this way a helical electrode on a extending in the direction of extension of the support rod or support tube. Strip-shaped, wave-shaped or zigzag-shaped electrodes can, for example, be applied to an elongated, plate-shaped support element.

A particularly preferred embodiment is a cylindrical discharge space with an internal electrode extending along the cylinder axis and a support element. It is consequently a discharge lamp with a central or concentric central electrode. It is advisable to apply a plurality of strip-shaped counter electrodes running parallel to the cylinder axis on the outer walls of the discharge space. In this way, the entire discharge space can be used effectively, the geometric arrangement required for this being relatively easy to generate. The problem that arises in this case of an exact central or concentric position of the central electrode during manufacture and continuous operation is solved by the invention.

The support element advantageously projects from an end face opposite a lamp base into the discharge space and is fastened to the corresponding end wall. In particular in the case of longer discharge vessels, a base on both sides can also be advantageous. Then the side of the pump stem is overlapped by a base. In a preferred embodiment, the discharge space is closed on one side by squeezing. Here, a metal foil is embedded, which serves as an electrical feedthrough for the inner electrode. This is attached to the metal foil, for example soldered on, and is partly pinched with one end, so that the electrode is held on one side by the pinch.

In order to prevent a displacement of the electrode in the longitudinal direction of the support element, this advantageously has a holding projection extending transversely to the longitudinal direction of the supporting element or a holding recess. The retaining projection can be corresponding knobs, lugs, spikes, etc., the retaining recess can be a groove or the like. Such knobs or lugs, for example, can be used to very well prevent a wire helix that runs around a support tube or a support rod against longitudinal displacement be secured.

An alternative embodiment of the holder provides that there is a spacer between the electrode and a wall of the discharge space transversely to the main direction of extent of the electrode. Such a spacer can be a type of hook or pin which is attached to a wall and holds the electrode in position. Preferably, several such spacers are used along the main longitudinal extent of the electrode.

A preferred embodiment of this spacer is a holding disk which is arranged transversely to the main direction of extent of the electrode and extends between the walls of the discharge space and through which the electrode extends at a predetermined position. Such a holding disk ensures secure positioning in any direction. Of course, it is also possible to use the support element and additionally spacers running transversely thereto. This is particularly useful when manufacturing very long lamps.

In a further alternative embodiment, the electrode is at least partially surrounded by at least part of the holder. For example, the electrode can be melted into dielectric material. In this case, the electrode, which can have any shape, is virtually integrated into the holder. Such a lamp is also suitable for bipolar operation and for fillings with noble gas halides.

In a simple embodiment, the electrode is arranged at least partially within the support tube, the support tube being constructed as described above. The inner electrode can in turn be applied to the inner wall of the support tube in the form of a structured conductive coating. In a preferred embodiment, it is a helical inner electrode that runs inside the support tube and is supported by the walls of the support tube. Of course, the support tube can again be supported on its longitudinal extent by spacers or retaining washers.

In an advantageous development of the invention, the holder or part of the holder is designed as a pump stem or as part of a pump stem. With this pump handle, the gas conditions in the discharge space are adjusted during production, i.e. the air in the discharge space is pumped out by the pump handle and the gas required as the discharge medium, for example an inert gas, is filled in.

The additional use of the holder as a pump stem is particularly useful in the embodiment with a support tube. This support tube can be attached to the wall of the discharge vessel such that it protrudes through the wall with one end. The discharge space can then be pumped out through the support tube and filled with gas. The support tube is then melted and closed in the usual way outside the discharge space as a pump stem.

Such a method for producing a discharge pump using the inserted holder as a pump stem or using a pump stem part as a holder is particularly simple and inexpensive.

Description of the drawings

The invention is explained in more detail below with reference to the accompanying drawings using exemplary embodiments. The features shown can be essential to the invention not only in the combinations mentioned but also individually or in other combinations. They represent:

FIG. 1 shows a schematic side view of a discharge lamp with a cylindrical discharge space and an axial central electrode, which is held by a support tube,

FIG. 2 shows a cross section through a discharge space according to FIG. 1, but with an alternative holder in the form of a hook-shaped spacer,

FIG. 3 shows a cross section through a discharge space according to FIG. 1, but with a further alternative holder in the form of a holding disc, FIG. 4 shows a cross section through a discharge space according to FIG. 1 with a fourth alternative holder comprising a plurality of holding rods running transversely between the walls of the discharge space,

5 shows a cross section through a discharge space according to FIG. 1 with an axially extending support tube and a plurality of radially extending cross supports.

Figure 1 shows a first embodiment of a discharge lamp according to the invention. This discharge lamp 1 has a discharge space 2 in a quartz glass vessel which is held on one side in a base 5. The discharge space 2 is the space in the discharge vessel filled with discharge medium.

The present exemplary embodiment is an excimer discharge lamp which is filled with xenon. With such an excimer discharge lamp, VUV radiation is generated with high efficiency, which is used industrially, for example in the cleaning of wafers, for ozone production or for water purification.

The lamp has a central helical electrode 6 within the cylindrical discharge space. This is the cathode, which is at a negative high voltage. On the outside of the wall 3 delimiting the discharge space 2 there are a plurality of strip-shaped electrodes 7 running parallel to the cylinder axis. These are the anodes 7. They are consequently separated from the discharge space 2 by the wall 3. The lamp is therefore designed for dielectrically impeded discharges.

As the holder 10, the lamp 1 has an axial support tube 9 which projects from the end wall 4 opposite the lamp base 5 into the discharge space 2 of the discharge vessel. The helical elec- trode 6 is partially guided around this support tube 9. In order to prevent displacement of the helical electrode 6 in the axial direction, a holding projection 12 in the form of a knob is formed on the support tube 9.

The holder consists of a temperature-resistant, non-conductive material, preferably glass, quartz glass or ceramic.

During manufacture, the discharge space 2 is first closed on the side of the end wall 4 opposite the base region, the support tube 9 being sealed and fixed in a central opening 8 in the end wall 4. To form the end wall 4 with the enclosed support tube 9, the open cylindrical vessel is heated and the support tube 9 is held by suitable aids, while the cylinder wall falls inwards under the action of heat. This closure can also be done by crushing.

To apply the helix 6 to the support tube 9 or to insert the support tube 9 into the helix 6, the helix 6 is screwed onto the support tube 9, with the holding projection 12 moving between the helical gears.

Subsequently, the filament 6 is also squeezed within the base region when the cylindrical discharge space 2 is closed in a vacuum-tight manner (not visible). In the area of the opposite end wall 4, it is held by the support tube 9.

The support tube 9 is also used as a pump stem by pumping the discharge space 2 through the support tube 9 and filling it with gas via the tube 9. In the case of longer discharge lamps, it makes sense for at least one, preferably a plurality of openings 11 to be arranged along the support tube 9 in the tube side walls in order to enable the discharge space 2 to be pumped out quickly and effectively. Of course, if it is not used as a pump stem, a corresponding rod made of solid material can also be used instead of the support tube 9. Likewise, it is alternatively possible that the support tube 9 or a corresponding support rod is not only held in the end wall 4, but extends longitudinally through the entire discharge space 2 into the base region 5 and is optionally also fastened in the end wall in the base region 5 , for example, is pressed in during production. As in the exemplary embodiment shown, the helix 6 can be a wire helix. Alternatively, however, the helix can also be applied to the support tube 9 or a corresponding support rod by means of a conductive paste, for example gold or platinum paste or the like. In the case of a continuous support tube 9 or support rod, which is also squeezed in the base area, it is advantageous if the electrode 6 is formed by a wire or a metal foil in the pinch area and then the electrode is made from the structured area in the discharge space 2 above the pinch point , conductive coating on the support tube 9 or the support rod, -whereby, of course, the lower area of the helix consisting of wire or metal foil and the upper area of the helix are contacted accordingly.

Because of the holder according to the invention, it is possible to manufacture lamps according to the exemplary embodiment according to FIG. 1 in almost any length. Currently, a maximum length of 20 cm can be produced without such a holder, without a secure fit of the electrode 6 being endangered. Experimentally, lamps with a length of more than 85 cm are currently being produced in the manner according to the invention.

In the embodiment shown, the support tube 9 is relatively long. In another embodiment, not shown, the support tube is only approx. 2 cm long and supports an approx. 12 cm long spiral only in the end area.

FIGS. 2-5 each show alternative exemplary embodiments for a holder.

The exemplary embodiment shown in FIG. 2 is a hook-shaped spacer 14, which is fastened at one end to the wall 3 of the discharge space 2, for example is melted down. At the other end, it is attached to the electrode coil 6. In order to hold a helix 6 securely over a longer distance in this way, a plurality of hooks 14 should be arranged along the longitudinal direction of the helix 6, these also advantageously running radially outward in different directions. A favorable distance between such spacer hooks 14 is approximately 15 cm.

Figure 3 shows as a spacer a continuous holding disc 15 through which the coil 6 runs in the middle. This holding disc 15 supports the helix 6 on all sides with respect to the walls 3.

FIG. 4 shows a holder in the form of two holding rods 16, 17 running one behind the other in the longitudinal direction of the helix 6, each of which extends across the discharge space 3 from one wall side to the other. These holding rods 16, 17 are fastened to the wall 3 on at least one side, for example melted. In this version, too, it makes sense if several such rods 16, 17 are used in succession in the longitudinal extension of the helix 6.

In the exemplary embodiment according to FIG. 5, an axially extending support tube 9 is again used. This axially extending support tube 9 is supported by a plurality of radially extending cross supports 18, which extend between the support tube 9 and the side wall 3 of the discharge space 2. ken, supported. This version is particularly useful for the manufacture of very long lamps.

Alternatively, it is of course possible to combine the support tube 9 or a corresponding support rod made of solid material with any spacers, as shown in FIGS. 2, 3 and 4. In particular, the use of the holding disks 15 according to FIG. 3 lends itself to this.

In a further exemplary embodiment, not shown, the axially extending support tube does not run inside the coil 6 but outside the coil 6. Thus, the inner helical electrode 6 is also shielded from the outer electrodes by a dielectric, namely the wall of the support tube. Such a lamp is also suitable for bipolar operation and for fillings with noble gas halides. Another alternative is to completely surround the electrode with dielectric material, for example to melt the electrode into dielectric material. The electrode can again have any shape. In this case, the electrode is virtually integrated into the holder.

Under certain conditions, the latter embodiment may be disadvantageous because of the relatively large dielectric strength between the electrode and the discharges caused by the walls of the support tube. In favor of lower operating voltages, it can then make more sense not to cover the electrode with thicker-walled parts of the holder. Rather, a dielectric layer applied, for example printed or brushed on, as a thinner coating should then be used - if at all. Such a layer thickness can also be set when melting into the holder.

Claims

claims

1. Discharge lamp (1) with a discharge space (2) filled with a discharge medium and with an electrode (6) extending in the discharge space (2) from the walls (3) of the discharge space (2), characterized by a holder (10, 14 , 15, 16, 17, 18) made of non-conductive material, which fixes the electrode (6) at a predetermined position in the discharge space (2).

2. Discharge lamp according to claim 1, characterized in that the electrode (6) has an elongated shape extending substantially in a main direction of extension.

3. Discharge lamp according to claim 1 or 2, characterized in that the holder (10) has an elongated in the main direction of extension of the electrode (6) extending support element (10) which supports the electrode (6) on at least a portion.

4. Discharge lamp according to claim 3, characterized in that the support element (10) has a support rod or a support tube (9).

5. Discharge lamp according to claim 3 or 4, characterized in that the electrode (6) at least on one. Part of its longitudinal extent extends helically around the support element (10).

6. Discharge lamp according to one of the preceding claims, characterized in that the discharge space (2) is cylindrical and the

The electrode (6) and / or the support element (10) extend along the axis of the twist.

7. Discharge lamp according to one of the preceding claims, characterized in that the support element (10) from a lamp- base (5) opposite end protrudes into the discharge space (2) and is fastened in or on the end wall (4).

8. Discharge lamp according to one of the preceding claims, characterized in that the supporting element (10) has a holding projection (12) extending transversely to the longitudinal direction of the supporting element or a holding recess.

9. Discharge lamp according to one of the preceding claims, characterized in that the holder (14, 15) has a spacer (14, 15) extending between the electrode (6) and a wall (3) of the discharge space (2) transversely to the main direction of extension ,

10. Discharge lamp according to claim 9, characterized in that the spacer (15) is arranged transversely to the main direction of extension of the electrode (6), between the walls (3) of the discharge space (2) extending holding disc (15) through which the electrode (6) runs through at a predetermined position.

11. Discharge lamp according to one of the preceding claims, characterized in that the electrode is applied to the holder in the form of a structured, conductive coating.

12. Discharge lamp according to one of the preceding claims, characterized in that the electrode is at least partially surrounded by at least part of the holder.

13. Discharge lamp according to claim 12, characterized in that the electrode is at least partially arranged within a support tube.

14. Discharge lamp according to claim 13, characterized in that the electrode extends helically within at least a portion of its longitudinal extent within the support tube.

15. Discharge lamp according to one of the preceding claims, characterized in that the holder (10) or part of the holder as

Pump stem or is formed as part of a pump stem.

16. Discharge lamp according to claim 15, characterized in that the holder (10) has an elongated tube (9) which protrudes with one end through a wall (4) of the discharge space (2) and along its longitudinal extent in the discharge space (2) the

Has opening (11) penetrating the tube wall.

17. Discharge lamp according to one of the preceding claims, characterized in that the holder consists of glass, quartz glass or ceramic.

18. Discharge lamp according to one of the preceding claims, characterized in that the discharge lamp (1) is designed for dielectrically impeded discharges.

19. A method for producing a discharge lamp according to one of the preceding claims, wherein the holder (10) or part of the holder is used as a pump stem or part of a pump stem.