EP3022763A1

EP3022763A1 - Gas discharge lamp and use thereof

Info

Publication number: EP3022763A1
Application number: EP14734840.3A
Authority: EP
Inventors: Erich Arnold; Christoph Söller; Igor Radosevic; Anke Schnabl; Gunther Desinger; Torsten Jenek; Günter PERLET; Norbert Fischer; Gerhard Damaschke; Theo Schneider; Bruno Uebbing
Original assignee: Heraeus Noblelight GmbH
Current assignee: Heraeus Noblelight GmbH
Priority date: 2013-07-18
Filing date: 2014-07-04
Publication date: 2016-05-25
Also published as: DE102013107694A1; CN105556639A; WO2015007548A1; EP3118888A1; EP3118888B1

Abstract

The invention relates to gas discharge lamps, in particular deuterium lamps, with a lamp bulb (2) filled with gas, comprising: an electrode housing with a front housing part (3) made of a non-electrically conductive material, a rear housing part (5), and a housing partition (4) which separates the front housing part (3) from the rear housing part (5). The front housing part (3) has a cathode (7), a cathode shielding window (8) arranged in front of the cathode (7), and a light outlet window (9) which emits light caused by the discharge towards the outside, and the rear housing part (5) receives an anode (6) which lies in the front housing part (3) on an optical axis A together with the light outlet window (9). The gas discharge lamp is characterized in that an outlet diaphragm (11) which has an adjustable electric potential and comprises a diaphragm opening (12) is arranged on the outside in front of the light outlet window (9), said diaphragm opening (12) lying on the optical axis A in projection of the light outlet window (9) and being spaced from said window. Damage to the lamp bulb material can be prevented by the outlet diaphragm. The invention further relates to the use of such gas discharge lamps for analytical purposes.

Description

Gas discharge lamp and its use

Description Technical background

The invention relates to a gas discharge lamp, in particular a

A deuterium lamp, comprising a lamp bulb filled with gas and an arrangement inside the lamp bulb, comprising: an electrode housing having a front housing part of non-electrically conductive material, a rear housing part and a housing intermediate wall separating the front housing part from the rear housing part, wherein the front housing part

Cathode, arranged in front of the cathode cathode and a light emission window, which emits light caused by discharge to the outside, and wherein the rear housing part accommodates an anode, which lies with the light exit window in the front housing part on an optical axis A.

Furthermore, the invention relates to a use of the gas discharge lamp for analytical purposes

As light sources for the generation of optical radiation in the visible, ultraviolet or infrared range gas discharge lamp are used. These

Gas discharge lamps consist of a filled with a filling gas

Lamp bulb in which two electrodes (cathode and anode) are arranged. When a voltage is applied between the electrodes, a gas discharge takes place, which is associated with the emission of optical radiation. The gas discharge causes a plasma state within the filling gas. The

Plasma consists partly or wholly of free positively and negatively charged particles (ions, electrons) whose motion is influenced by the strength of the field between the two electrodes and by special designs of the cathode and anode spaces within the lamp envelope. Deuterium lamps (deuterium filling gas) are generally constructed in such a way that particles from the cathode space and from the area of the Plasma arc between the cathode and anode can pass through the light exit window on the lamp envelope made of glass. It happens there

Changes in the glass of the lamp bulb, which leads to light absorption and - scattering and thus significantly reduces the life of the lamp.

State of the art

From EP 0 700 072 A2 a generic gas discharge lamp is known, which shows an improved, stable light output. The lamp has a

Lamp bulb made of quartz glass or other UV-transparent glass and has a housing whose rear part and the housing intermediate wall made of ceramic. The anode is located in the rear of the housing, just behind an opening in the housing intermediate wall, in which a

Focusing electrode (focusing electrode 26) designated shaped body partially protrudes. The housing front part is made of metal and has a light exit window. The housing front part is used as a front electrode (front electrode 23)

designated. In the front part of the housing is the cathode region, wherein the cathode of a so-called cathode box (cathode box) is surrounded by a wing of the front electrode (front housing part) and a

Cathode slot electrode (cathode slit electrode 27) is formed. The

Kathodenbox causes a reliable ignition and a stable potential in the cathode compartment, whereby the operating state with respect to the maintenance and direction of the charge carrier path from the cathode over the molding body (focusing electrode 26) to the anode gains in stability. Once the discharge is triggered to form a plasma, the electric circuit for adjusting the desired luminosity of the gas discharge lamp is set so that the potential of the molded article is negative or zero, thereby optimizing the discharge guidance from the cathode to the anode and the shape of the plasma can be. DE 10 2008 062 410 A1 relates to a deuterium lamp in which

Side discharges and a concomitant erosion on the

Discharge path between cathode and anode focusing moldings be avoided. According to FIG. 2 from DE 10 2008 062 410 A1, the housing front part and the intermediate wall are made of ceramic, the rear wall of the housing is made of metal. The cathode in the front housing part is partially surrounded by the ceramic housing front, in addition, is a metallic

Cathode shield provided. The molding and the

Kathodenabschirmfenster are electrically isolated from each other, so that no side stream is formed. The ceramic housing front part has an opening for the jet outlet, through which, in the unfavorable case, charged particles can also pass from the plasma to the lamp bulb surface.

In another variant according to DE 10 2008 062 410 A1, only the

The cathode compartment or the cathode shielding window made of electrically insulating material, the entire housing, the intermediate wall, and the molded body, however, are made of metal. Also in this construction of the deuterium lamp, the formation of side streams is avoided. The metallic housing front part has an opening for the jet exit in the direction of the lamp bulb, which in this case is provided with a dazzle-type attachment. Since the attachment forms a unit with the metallic housing, it can not be attributed any independent electrical potential. The attachment has here only the function of a holder for a possible filter plate.

Technical task

The discharge lamps described here have the disadvantage that during operation particles which are released in the electrode housing, whether from the cathode space or from the area of the plasma arc between cathode and anode, can pass through the light exit window onto the lamp envelope made of glass and cause damage there. The intensity or the

Lifespan of the gas discharge lamp decreases significantly. The particles can change the glass of the lamp bulb so that it comes to light absorption and / or light scattering.

It is therefore an object of the invention to provide a gas discharge lamp, which shows no damage to the lamp bulb material during operation and thus a Increasing the intensity and the life of the lamp causes. The

Gas discharge lamp should also be easy and inexpensive to manufacture.

General description of the invention

This object is achieved on the basis of a gas discharge lamp of the type mentioned in the present invention, that an outlet aperture having an adjustable electrical potential is arranged outside the light exit window with an aperture, wherein the aperture is in projection of the light exit window on the optical axis A and from this one Distance has.

The gas discharge lamp according to the invention comprises one with gas,

in particular deuterium, filled lamp envelope, being within the

Lamp bulb, an electrode housing is arranged, which has a front housing part made of non-electrically conductive material, a rear housing part and the front separating from the rear housing part housing intermediate wall. In the front housing part is the cathode compartment with a cathode and arranged in front of this Kathodenabschirmfenster. The anode compartment with an anode is located in the rear housing part. The anode faces an opening in the housing intermediate wall and a light exit window in the front housing part, so that the anode, the opening in the housing intermediate wall and the light exit window lie on an optical axis A. The light caused by the discharge is emitted to the outside via the light emission window. According to the invention, an outlet panel having an adjustable electrical potential is arranged with an aperture outside the front housing part and in front of the light exit window. The

Aperture is in projection of the light exit window and has a distance from this. The center of the aperture and that of the

Light exit window thus lie on the optical axis A of the gas discharge lamp. The electrical potential of the exit aperture affects the electrical

Field in the region of the light exit window, so that a kind of shield is created, which protects the lamp bulb from harmful particles from the Electrode housing protects. The electrical potential of the exit aperture can be of similar magnitude as the potential of the cathode screen window, but it is adjustable independently of this. In addition, the geometry of the exit aperture plays a role, so that a minimum distance between the light exit window and aperture is necessary to bring the shielding effect sufficiently advantage. The interaction of the geometrical relationships of the exit aperture and the electrical potential of the exit aperture affects the electric field in the region of

Light emission window, which in turn affects the movement of particles (ions, electrons) from the plasma or particles that arise in the electrode housing during operation of the lamp.

The inventive arrangement of the exit aperture and by their electrical potential are thus by the aforementioned particles

caused sputtering effects or other damage to the lamp bulb material prevents, which prolongs the life of the lamp at a stable, high light intensity.

Advantageous embodiments of the invention can be found in the dependent claims. In an advantageous embodiment, the invention provides that the

Exit orifice is designed as a U-profile, whose legs are the front

Touch the housing part and form the distance to the light exit window. The use of a U-profile as exit aperture is a solution that is easy to implement in terms of assembly. The leg length is easy to dimension in standard components. The aperture can be mounted in advance in such U-profiles by punching, so that only a cutting to length of the required for each lamp U-profile is required as an exit panel. In general, the U-profile is arranged approximately over the entire height of the front housing part, which is in view of the shielding effect of this

Exit aperture particularly positive effect. The U-profile may have at one or more points approaches that as attachment and / or

Contacting positions serve. However, these approaches affect the

Basic shape of the U-profile not. An alternative and also preferred embodiment of the exit aperture is that of the ring shape. In the annular formation, the exit aperture encloses the light exit window, whereby the shielding space created by this embodiment of the exit aperture can be further developed in front of the light exit window by the choice of the ring diameter and a ring profile with respect to optimum protection of the lamp envelope from damage by any particles from the plasma , It has proved to be advantageous if the annular exit aperture has an angle profile, one leg determines the distance to the light exit window, or if the annular

Exit aperture has a semi-circular profile whose diameter determines the distance to the light exit window. The exit aperture, whether it is a U-profile or ring-shaped, is preferably made of a metal. Metal as a good electrically conductive material is available in a variety of geometric shapes, so that metal is particularly suitable as a material for the exit aperture. A preferred metal for this application is nickel or a nickel-base alloy. Other metals are in principle also suitable, as far as the electric

Conductivity, processability and ambient temperatures in the

Lamp bulbs do not limit their use or exclude.

It has been proven if the distance between the aperture and

Light emission window is at least one millimeter. Limiting the distance between the light exit window and the aperture is the distance of the exit aperture to the lamp envelope. However, direct contact of the exit aperture with the lamp envelope must be avoided as this is too

cause mechanical damage to the lamp bulb and thus affect the function and life of the gas discharge lamp. On the other hand, the minimum distance of 1 mm to the light exit window is necessary to create a space in front of the light exit window, which forms a kind of shield for emerging from the electrode housing or the plasma particles relative to the lamp envelope. This shielding space has its effect also with regard to limiting the temperature of the lamp bulb, at least in the

Area of the light exit. In an advantageous embodiment of the invention, the electrical potential of the exit aperture is adjustable by a connection to a lying outside the electrode housing voltage source. With this embodiment, it is possible to set the electric potential regardless of the potential in the region of the light emission window and in the region of the cathode shielding window. Especially with regard to a fine adjustment of the potential, this is advantageous. As a voltage source, for example, a laboratory power supply is suitable, which ensures a precise adjustment of low voltage values up to voltage values in the range of up to 100 volts. An alternative and equally preferred way of adjusting the electrical potential of the exit aperture is that the electrical potential is adjustable by connection to the cathode shield window. For this purpose, a contact between the exit panel and cathode shield is necessary. For the electrical contact between the exit aperture and the cathode shielding window, it is important that the connection has the lowest possible contact resistance. The location of the electrical connection is of minor importance.

Advantageously, the connection between the exit aperture and the cathode shielding window is effected through the front housing part by means of at least one metallic rivet which at the same time mechanically fastens the exit aperture to the front housing part. The riveted joint ensures a good conductive connection between the exit aperture and the cathode shield window, which is also clean and precise in design. The rivet is set through the front housing part and also serves to attach the

Exit panel on the front of the housing. Basically, in place of

Rivet also a connection by means of a screw possible, which is optionally set by a hole through the front housing part. The front housing part itself is made of electrically non-conductive material, that is usually made of a ceramic material such as

Alumina.

To exclude corrosive changes in the connection between the exit aperture and the cathode shield window, which in turn causes the electric field in the Area of the light emission window, it has proved to be advantageous if the exit aperture, the cathode shield and the rivet of the same metal.

With regard to the size of the aperture of the exit aperture, it has proven useful if it is greater than the light exit window. Through this

Design of the aperture is taken into account the fact that the light cone emanating from the plasma in the interior of the front housing part is not or only slightly limited by the aperture in the exit aperture. This measure is particularly important in terms of the highest possible light output of the gas discharge lamp of importance.

For gas discharge lamp, a borosilicate glass is preferably used as the material for the lamp envelope. The borosilicate glass is chemical and

temperature resistant and for the desired wavelength range of

Gas discharge lamp sufficiently transparent. Such a lamp bulb is therefore well suited for gas discharge lamps, which are used for example in spectrophotometers.

Gas discharge lamp with the aforementioned features are used for analytical purposes, in particular as a light source in spectral analysis.

embodiment

The invention is based on a patent drawing and a

Embodiment explained in more detail. In detail shows:

1 shows a representation of the gas discharge lamp according to the invention

Based on a schematic cross section, Figure 2 is a front perspective view of the housing a

Gas discharge lamp according to the invention and

3a, 3b are each a perspective view from above of the housing of

FIG. 2 In FIG. 1, a deuterium lamp 1 is shown schematically in cross section along the optical axis A. The lamp 1 has a lamp bulb 2 and a two-part housing, consisting of a front housing part 3 with a housing intermediate wall 4 made of ceramic, in this case aluminum oxide, as well as a rear housing part 5 made of metal. The lamp bulb 2 is filled with gas, here deuterium. In the rear housing part 5 is the anode 6. In the front housing part 3, a cathode 7 and an existing of a nickel sheet cathode shield 8 are arranged. Furthermore, the front housing part 3 has a light exit window 9 which faces the anode 6 and forms with it the optical axis A of the gas discharge lamp. The cathode shield window 8 has an opening 16 in the direction of the optical axis A. During operation of the lamp 1, a discharge forms between the cathode 7 and the anode 6, which provides a continuous UV spectrum. To increase the radiation intensity, a shaped body 10 is arranged in front of the opening 17 of the housing intermediate wall 4 and the anode 6, which constricts the plasma in the form of a sphere by means of charge carrier concentration.

The light cone (not shown) resulting from the discharge and formation of the plasma passes along the optical axis A through the

Light exit window 9 in the direction of the lamp bulb 2. Outside on the front housing part 3, in front of the light exit window 9, an exit aperture 1 1 is arranged from a nickel plate with a U-profile. The exit aperture 1 1 has an aperture 12 which is in projection to the light exit window 9, wherein the aperture 12 with a diameter of 8 mm is slightly larger than the light exit window 9 with a diameter of 6 mm. The U-profile of

Exit aperture 1 1 has two legs 13, 13 'with a leg length of about

3.5 mm. The legs 13, 13 'of the U-profile of the exit aperture 1 1 determine the distance of the aperture 12 from the light exit window 9. Alternatively to the U-profile of the exit aperture 1 1, this can also be used as an annular angle profile

be formed, whose one annular leg 13 has a leg length of about 3.5 mm and thus determines the distance between the aperture 12 and the light exit window 9. Via a rivet 14, the exit aperture 1 1 is attached to the front housing part 3 and at the same time electrically conductively connected to the cathode shield 8. The rivet 14 consists of a nickel Base alloy and is positioned in a setting process through the ceramic housing front part 3 therethrough. By the invention

Arrangement of the exit aperture 1 1, the electric field in the region of

Kathodenabschirmfensters 8 and the light exit window 9 and approximately adjusted to the level of the potential at the cathode screen. In this area is to be expected with a potential in the order of 10 to 20 volts, whereas between cathode 7 and anode 6 about 60 to 100 V are applied. The deuterium lamp 1 according to the invention is thus suitable as

Light source to be used in a spectrophotometer. Even with permanent operation of up to more than 2000 hours, there is no damage to the lamp bulb 2 due to increased light absorption or light scattering.

Figure 2 shows only the light-emitting housing, which is located within a lamp envelope, not shown. In a perspective front view, the exit aperture 1 1 can be seen with a circular aperture 12. The aperture 12 is in the extension of the light exit window 9, which is not completely visible in Figure 2. The exit aperture 1 1 is formed as an elongated component with a U-profile, which is fastened with a rivet 14 on the front housing part 3 and via the contacting portion 15 with the

Cathode shield 8 is electrically connected.

Figures 3a and 3b show two variants of a view from above of the housing according to the figure 2. Here are the cathode 7 with the

Kathodenabschirmfenster 8 in the front housing part 3 and the anode 6 in the rear housing part 5, as well as the exit aperture 1 1 according to the invention on the front housing part 3 can be seen. The cathode shield window 8

differs slightly in the two figures: In Figure 3a has the

Kathodenabschirmfenster 8 a the light exit window 9 comprehensive

Contacting section 15, which is connected via a rivet 14 with the exit panel 1 1 and attached and electrically contacted. 3b, the contacting section is formed by two webs 15 ', 15 ", which are spaced apart from the light exit window 9. Two rivets 14, 14' connect the exit screen 1 1 to the cathode shielding window 8 via the two webs 15 ', 15" Both variants ensure the function of the exit panel 1 1 as Abbruchnungsnunn to prevent damage to the lamp bulb 2, so that they are permanently suitable for use in devices for spectral analysis.

Claims

Patent claims

Gas discharge lamp, in particular deuterium lamp (1), with a lamp bulb filled with gas

(2), comprising:

an electrode housing with a front housing part (3) made of non-electrically conductive material, a rear housing part (5) and a front housing part

(3) separating from the rear housing part (5).

Housing partition

(4), wherein the front housing part (3) comprises a cathode (7), a cathode shielding window (8) arranged in front of the cathode (7) and a light exit window (9) which emits light caused by discharge to the outside, and wherein the rear Housing part (5) accommodates an anode (6), which lies with the light exit window (9) in the front housing part (3) on an optical axis A, characterized in that an exit aperture (1 1 ) having an adjustable electrical potential with an aperture opening ( 12) outside in front of the light exit window (9)

is arranged, the aperture opening (12) being in projection of the

Light exit window (9) lies on the optical axis A and is at a distance from it.

Gas discharge lamp according to claim 1, characterized in that the exit panel (1 1) is designed as a U-profile, the legs (13; 13 ') touch the front housing part (3) and the distance to

Determine the light exit window (9).

Gas discharge lamp according to claim 1, characterized in that the exit aperture (1 1) is annular.

Gas discharge lamp according to claim 3, characterized in that the annular exit aperture (1 1) has an angle profile, one leg (13; 13 ') of which determines the distance to the light exit window, or that the annular outlet aperture (1 1) has a semicircular profile, whose diameter determines the distance to the light exit window.

5. Gas discharge lamp according to one of the preceding claims, characterized in that the exit aperture (1 1) is formed from a metal.

6. Gas discharge lamp according to claim 5, characterized in that the metal comprises nickel or a nickel-based alloy.

7. Gas discharge lamp according to one of the preceding claims, characterized in that the distance between the aperture opening (12) and

Light exit window (9) is at least 1 mm.

8. Gas discharge lamp according to one of the preceding claims, characterized in that the electrical potential of the outlet diaphragm (1 1) can be adjusted by a connection to a voltage source located outside the electrode housing.

9. Gas discharge lamp according to one of claims 1 to 7, characterized

characterized in that the electrical potential of the exit aperture (1 1) can be adjusted by a connection to the cathode shielding window (8).

10. Gas discharge lamp according to claim 9, characterized in that the connection between the exit aperture (1 1) and the cathode shielding window (8) takes place through the front housing part (3) by means of at least one metallic rivet (14; 14 '), which at the same time covers the outlet aperture ( 1 1 ) mechanically attached to the front housing part (3).

1 1 . Gas discharge lamp according to claim 10, characterized in that the exit diaphragm (1 1), the cathode shielding window (8) and the rivet (14; 14') consist of the same metal.

12. Gas discharge lamp according to one of the preceding claims, characterized in that the aperture opening (12) of the exit aperture (1 1) is larger than the light exit window (9).

13. Gas discharge lamp according to one of the preceding claims, characterized in that the material of the lamp bulb (2).

Borosilicate glass is.

14. Use of the gas discharge lamp according to one of claims 1 to 13 for analytical purposes, in particular as a light source

Spectral analysis.