Dielectric barrier discharge lamp with a base

Translation of description of equivalent WO 03098653 A2

The dielectric barrier Entiadungslampe with base

Technical field

The invention relates to a dielectric barrier discharge lamp.

The term "dielectric barrier discharge lamp" encompasses sources of electromagnetic radiation based on dielectric barrier gas discharges. The spectrum of the radiation may be both the visible region and the UV (ultraviolet) / VUV (vacuum ultraviolet) region and the IR (infrared) range include. Further, a phosphor layer for converting VUV radiation into radiation of longer wavelengths, for example, UVA or visible radiation (light) may be provided.

A dielectric barrier discharge lamp is defined as at least a so-called dielectric barrier electrode advance. A dielectrically impeded electrode is separated from the interior of the discharge vessel or of the discharge gas by a dielectric. This dielectric - dielectric barrier - for example, can be as a run the E- elec- trode dielectric layer covering, or it is formed by the discharge vessel of the lamp itself, namely, when the electrode on the outside of the wall of the discharge vessel is arranged. The latter is referred to hereinafter as an abbreviation "outer electrode".

The present invention relates to a dielectric barrier discharge lamp which has at least a substantially strip-shaped outer electrode of the aforementioned kind. Furthermore, the lamp comprises an elongated or tubular, closed at both ends discharge vessel enclosing an ionizable filling.

The ionizable filling usually comprises a noble gas, for example xenon or a gas mixture. During the gas discharge, which is preferably operated by means of a pulsed operating method described in US 5,604,410, so-called excimers are formed. Ex- cimere are excited molecules, eg Xe₂*, Which emit electromagnetic radiation when they return to the generally unbonded ground state. In the case of Xe₂*, The maximum of the molecular band radiation at about 172 nm.

Thereby such lamps are suitable as UVΛ / UV lamps in the process, for example, the surface cleaning, photolysis, ozone generation, metallization and UV curing. For this purpose it is usually necessary to operate the lamp directly into a vacuum process gas atmosphere or vacuum. Here suitable arrangements for gas-tight installation of such heaters are to meet in a corresponding process chamber.

State of the art

From document US 6,060,828, in particular Figures 5a to 5c, such a lamp with Edison screw base for general illumination is already known. This lamp includes a coil-shaped electrode inside the discharge vessel. In addition, four strip-shaped electrodes are arranged on the outer wall of the discharge vessel.

EP-A 1,088,335 discloses a suitable for UV irradiation dielectric barrier discharge lamp with a base. Although the base has a flange which is connected by means of casting compound with the pinch of the lamp and is suitable for low pressure applications. However, this concept for high-vacuum is less suitable. Another disadvantage is that relatively much sealing compound is needed when the entire room to fill between the pinch and the cylindrical inner wall of the base sleeve. But if gaps are released, there is a vacuum in vacuum applications in the area between the Quetschfußende and subsequent sealing. Then there is the risk of parasitic gas discharges between the power supply lines.

Summary of the Invention

The object of the present invention is to provide an improved dielectric barrier discharge lamp. Another aspect is that the dielectric barrier discharge lamp is to be used in a vacuum environment.

This object is achieved with a dielectric barrier discharge lamp having a base, said discharge lamp comprising: an elongate, closed at both ends discharge vessel whose wall surrounds an ionizable filling, electrodes, wherein at least one of the electrodes being an inner electrode, that is arranged inside the discharge vessel and at least one of the electrodes is an outer electrode, that is arranged on the outside of the wall of the discharge vessel, a power supply for the at least one inner electrode and a lamp base, the gas-tight through which at least one inner electrode is connected to the power supply, characterized in that the base a pipe comprises, which is fitted the discharge vessel at lampenfußseitigen end and surrounds the lamp base.

Particularly advantageous configurations are given in the dependent claims.

The basic idea of ​​the invention is to put on the lampenfußseitige end of the discharge vessel of the dielectric barrier discharge lamp, a tube surrounding the lamp base. This is a gas-tight

Separation between the two power supply lines for the external or domestic nenelektrode possible. In this way, the aforementioned parasitic gas discharges between the power supply lines can be prevented at low pressure.

To enable also have different diameters for the discharge vessel and the attached thereto tube, it may be expedient to provide a suitable transition area. In this case the tube includes a cylindrical and a conical portion, the conical section connecting the discharge vessel to the cylindrical portion.

For gas-tight installation of the lamp according to the invention in a process chamber, the tube expediently additionally means for densities.

In a preferred embodiment, this means is realized by a Kleinflanschdichtung for sealing which is fitted over the tube. For this purpose are in principle commercially available, possibly suitably modified vacuum to-Kleinflanschdichtungen for glass tubes. The power supply for the external electrodes, as well as the outer electrodes themselves are formed as a conductor track-like structure. The thickness of these structures is typically only a few micrometers. This enables a gas-tight passage of the arranged on the outside of the tube current lead of the outer electrodes by the O-ring usually used as a seal for vacuum-small flanges. In addition, the lamp end facing away from the tube expediently a connector, for example of the type BNC - HT, is provided which is connected to the two power supply lines. Further details can be found in the embodiment.

Alternatively you can either be connected by direct fusion with the free end of the tube, a metal vacuum flange using transition glasses or a glass flask.

In addition, the power supply line for the outer electrode need not necessarily be arranged similar conductor track on the outer side of the tube. Since the outer electrodes are preferably at ground potential, it may also be advantageous to the external electrodes directly, for example by means of a suitable spring contact to connect with the metallic process chamber.

If in any case, as explained above, the lamp according to the invention by means of the seal base in a gastight manner is installed in a process chamber, the attached pipe separates surrounded by the air pressure power supply to the inner electrode of that part associated with the outer electrode current feeder, which is exposed to the process gas atmosphere or vacuum. Thereby, the aforementioned parasitic discharges between the lying at different potential operating current leads can be effectively prevented.

Brief Description of Drawing

In the following the invention using an exemplary embodiment is illustrated. The figure shows:

a plan view of a dielectric barrier discharge lamp according to the invention with base, including base adapter (sectional view).

Preferred embodiments of the invention

In the figure, an inventive dielectric barrier discharge lamp 1 is shown schematically with base. It is a UV / VUV radiator, for example for surface cleaning, photolysis, ozone generation, metallization or UV curing. This lamp is designed for an electrical power of about 20 W.

The discharge lamp 1 has a circular cylindrical discharge vessel 2 from 0.7 mm to 1, 5 mm thick quartz glass. The discharge vessel 2 has one NEN outer diameter of about 40 mm and a length of about 120 mm. The interior of the discharge vessel 2 is filled with Xenon at a pressure of 20 kPa.

At a first end the discharge vessel 2 is dome-sealed and has an exhaust tip 3 in the center of the dome. In the area of ​​the exhaust tube 3 opposite lamp foot is fused quartz tube 4 to the discharge vessel. 2 Alternatively it can be added by means of glass solder this quartz tube. The quartz tube 4 has a conical portion 5 and a circular cylindrical section. 6 The conical section 5 connects the tubular discharge vessel 2 with the circular cylindrical section 6, its outer diameter is approximately 25 mm. On lamp-penabgewandten end of the quartz tube 4 a connector 7 of the type BNC - arranged HT.

On the outside of the discharge vessel 2 are six Außenelektro- the 8a-8f (external electrodes 8d-8f are shown in FIG. 1 not visible) in the form of 12 cm long, about 1 to 1, 5 mm wide, thin strip of platinum, etc. - quidistant and mounted parallel to the lamp longitudinal axis. The ends of the strip electrodes 8a-8f are connected to each other with a circumferential platinum strip 9, 10th Of a platinum strip 9, which is mounted in the immediate vicinity of the connection between the discharge vessel 2 and the quartz tube 4 is connected to a further strip of platinum eleventh This additional platinum strip 11 runs on the outside of the quartz tube 4 and ends on the connector 7, with its first pole it is connected. In this way, these platinum strip 11 acts as a power supply for the Außenelektro- 8a-8f.

On the circular cylindrical section 6 of the quartz tube 4, a modified base adapter 12 is located on the type ISO KF 40 (sectional view). It comprises a vacuum small flange 13 and thus screwed inner sleeve 14. The inner sleeve 14 pushes a metal ring 15 an O-ring 16 against a bevel 17 of the small flange 13. This seals this ser O-ring 16 against the outside of the quartz tube 4. A further O-ring 18 is inserted in an internal groove 19 on the threaded free end of the inner sleeve fourteenth This stress-free, gas-tight storage of the lamp 1 is achieved in the socket adapter 12th An annular groove 20 on the sealing side of the small flange 13 serves (not shown) for installation (not shown) in a process chamber for receiving a known centering with O-ring.

At the top of the pump 3 the opposite end, the discharge vessel tapers 3 and proceeds in a pinch 21st The Quetschdich- device 21 ensures by means of a sealing film 22 made of molybdenum, a gas-tight connection of the inner electrode 23 to an external power supply 24. This power supply 24 is connected to the second pole of the connector plug 7 (not shown).

The inner electrode 23 is centrally arranged inside the discharge vessel 2 coiled metal wire. The press seal 21 opposite end of the coil electrode 23 is fixed in the exhaust tube. 3 The respective diameter of the metal wire and the coil are 1 mm or 8 mm. The pitch - ie the distance within which the helix executes a complete revolution - is 12 mm.

Details of the operation of the electrodes during lamp operation are in the already cited US 6060828, in particular in the description of Figures 5a to 5c will be described.