EP2128888A2 - Mercury-free metal halide high pressure discharge lamp - Google Patents

Abstract

The lamp has two electrodes (2a, 2b) that are protruded into transparent and gas tight sealed discharge vessel (1), where the electrodes are opposite to one another. The discharge vessel has discharge space that is filled with a lamp filling, which comprises noble gas, elements of iron, zinc, halide, cobalt, tin, palladium, ruthenium, silver, zinc bromide, iron iodide and thallium iodide. The halide comprises bromide with percentage of 14 mole percent of total halogen quantity. An independent claim is also included for a photochemical process.

Description

Field of the invention

The invention relates to a high-pressure discharge lamp and in particular to a mercury-free metal halide high-pressure discharge lamp. Furthermore, the invention relates to an apparatus for generating ultraviolet radiation, comprising a mercury-free metal halide high-pressure discharge lamp. Such a mercury-free metal halide high-pressure discharge lamp can be used in particular in photochemical process plants, for example for lacquer curing, for disinfection and / or for tanning purposes.

State of the art

High pressure discharge lamps are gas discharge lamps. In conventional high-pressure discharge lamps, in a gas-tight discharge vessel under higher pressure, in addition to a noble gas, either mercury alone or, as in the more modern metal halide high-pressure discharge lamps, mercury combined with traces of metal halides. In the discharge vessel electrodes protrude, between which in the case of a sufficiently high electrical voltage difference, a self-sustaining gas discharge (an arc) is formed. High pressure discharge lamps generally emit a line spectrum, that is, lines are emitted in wavelengths characteristic of the mercury and admixtures. The mercury spectrum alone has large gaps, especially in the UV-A range, which are only filled by the admixtures. In addition to UV-A, high intensity discharge lamps emit significant amounts of UV-B, UV-C, visible light and infrared radiation. Examples of applications for high pressure discharge lamps can be found in the field of industrial and street lighting, in the illumination of shop displays, in stage lighting, in architecture and in beamers. Furthermore, high pressure discharge lamps are used in photochemical processes, such as for paint curing or disinfection. Another area of application is tanning lamps, which are used in particular in solariums.

The filling of high-pressure discharge lamps contains, on the one hand, a discharge gas (generally a metal halide, such as sodium iodide or scandium iodide), which constitutes the actual light-emitting material (light former), and, on the other hand, mercury, which serves primarily as a voltage gradient former and has essentially the function of Increase efficiency and burning voltage of the high pressure discharge lamp.

High-pressure discharge lamps of the type described above have been widely used because of their good color properties. The disadvantage, however, is that they contain mercury. Mercury-containing high-pressure discharge lamps must be disposed of in an orderly manner in order to isolate the mercury contained therein. Broken lamps also pose a danger that mercury will be released into the breathing air and may cause health problems. In addition, leaking mercury under amalgam formation may attack aluminum, which may, for example, lead to structural weakening of aircraft fuselages and for this reason has led to severe transport constraints for mercury-containing materials. Another disadvantage of mercury-containing tanning lamps is that they have a relatively high proportion of radiation in the UV-B range, which is carcinogenic effect.

For these reasons, it is desirable to provide a mercury-free high pressure discharge lamp. However, it is not possible to easily dispense with the known lamp types on the mercury content, without taking further action. A general problem with mercury-free high-pressure discharge lamps is that with the same lamp power in continuous operation, a lower burning voltage and thus a higher lamp current and a lower efficiency results.

From the WO-A-99/05699 For example, a mercury-free metal halide discharge lamp is known. It uses xenon as a buffer gas and an ionizable filling containing at least sodium iodide and zinc. However, for a satisfactory operation of the metal halide discharge lamp, certain requirements are to be placed on the geometry of the discharge vessel and the electrodes used. According to the WO-A-99/05699 For example, the electrode spacing EA and the inner diameter Di of the discharge vessel must satisfy the relation 1 ≦ EA / Di ≦ 4. This constitutes one Not inconsiderable limitation on the possible geometry of the discharge vessels used. In particular, not every long arc lamp meets these geometric requirements.

According to the JP 09293482 A , which discloses a metal vapor discharge lamp, are also made requirements on the geometric dimensions of the discharge vessel. The emphasis in this publication is on good energy conversion efficiency in the range between 200 and 250 nm, that is, in the UV-C range.

From the WO 2005/112074 A2 is a high-pressure discharge lamp is known, which is free of mercury. The ionizable filling of the discharge vessel used consists of xenon with a cold filling pressure of 11,800 hPa, 0.25 mg of sodium iodide, 0.18 mg of scandium iodide, 0.03 mg of zinc iodide and 0.0024 mg of indium iodide. In such a filled high-pressure discharge lamp, the problem of comparatively higher lamp current (compared with mercury-containing lamps) occurs. The electrodes which protrude into the discharge vessel are sealed by means of embedded molybdenum foils, and this molybdenum foil region connected to the electrode is exposed to a high thermal load during lamp operation. This can lead to a separation of the molybdenum foil from the quartz glass of the discharge vessel and to cracks in the glass and thus to premature failure of the lamp. To solve this problem proposes the WO 2005/112074 A2 to set the minimum distance of the respective molybdenum foil to the projecting into the interior of the discharge vessel end of the connected electrode to more than 5 mm. However, this only partially reduces the thermal load on the molybdenum foils.

The present invention is intended to overcome the disadvantages of the known prior art high pressure discharge lamps. In particular, it is the object of the present invention to provide an alternative mercury-free high-pressure discharge lamp based on metal halide, especially in the UV-A range, a high intensity can be realized with a variety of lamp geometries and compared to mercury-containing lamps no or only slightly higher Lamp current needed.

In particular, the high-pressure discharge lamp according to the invention should achieve at least 63% of the intensity of a comparable mercury-containing lamp. This value can be explained as follows: Typically, mercury-containing lamps are manufactured with batch spreads of 10% and are operated for economic reasons up to a further drop in intensity to 70%, so that replacement usually takes place at 63% of the initial nominal value.

The object of the invention is achieved by the subject matter of the independent claims. The dependent claims are directed to advantageous embodiments of the invention.

Description of the invention

The invention thus relates, in a first aspect, to a mercury-free metal halide high-pressure discharge lamp having a light-transmitting and gas-tight discharge vessel and two electrodes which protrude into the discharge vessel and are arranged opposite one another in the discharge vessel. The discharge vessel is filled with a lamp filling which comprises at least one noble gas, at least the elements iron and zinc and at least one halide, wherein the halide comprises bromide. The proportion of the bromide is at least 14 mol% of the total amount of halogen. For the ratio of zinc dikes in μmol / cm ³ and electric field strength E in V / cm between the electrodes, the relationship is 0.005 ≤ D / E ≤ 0.200.

The discharge lamp according to the invention basically corresponds to the outer shape of the discharge lamps customary in the prior art, but differs from these in the composition of the lamp filling. The invention is based on the finding that by special selection of the fillers on the one hand (with the compelling components noble gas, iron, zinc and halide, including necessarily bromide) and their quantitative vote on the other hand (proportion of bromide to the total amount of halide and zinc content) a mercury-free Lamp with high radiation power in the UV-A range can be obtained at the same time comparatively low power consumption, which can be realized with different piston shapes and sizes.

In the context of the invention, it has been recognized that adherence to a specific molecular weight of zinc, ie the molar amount of zinc (in μmol) in relation to the volume (in cm ³ ) of the discharge space of the lamp bulb, in relation to the electric field strength (in V / cm) , the quotient of burning voltage (in V) and the distance between the electrodes (in cm), has a significant importance in achieving the desired radiation efficiency. Similarly, the ratio of zinc dikes in μmol / cm ³ and electric field intensity E in V / cm is set between the electrodes according to the relationship of 0.005 ≦ D / E ≦ 0.200. Maintaining this range, a discharge lamp whose irradiance is at least 63% of a comparable mercury-containing lamp is obtained substantially independently of its external shape. Preferably, the quotient D / E is in the range of 0.01 to 0.18. An irradiance of 73% or more with respect to a comparable mercury-containing lamp can usually be realized when the ratio D / E is in the range of 0.025 to 0.165. To the ratio D / E is Furthermore, it should be noted that this is largely independent of the type of power supply to the electrodes and the ballast used. The reason for this is that field strength is a lamp characteristic that does not depend on power or power supply.

The zinc acts as a stress-increasing filling substance. It prevents a voltage drop between the electrodes and thus increases the residual voltage available for generating radiation. The zinc is preferably filled in the form of zinc halide, in particular zinc bromide and / or zinc iodide. However, it is not preferred to use the element zinc in the form of metallic zinc. Zinc is the less noble metal compared to the element iron that is also present in the lamp filling. Metallic zinc could therefore react with iron halide to form zinc halide and metallic iron. This iron would deposit as a solid on the wall of the discharge vessel and thus on the one hand no longer be available as a radiation-active substance and on the other hand lead to a blackening of the bulb. Both would reduce the radiation yield.

The quantities according to the invention relate to a state of the lamp filling in which the components are virtually completely evaporated and converted into the gas phase. In concrete terms, at least 70% by weight, in particular at least 80% by weight, of the lamp filling are in the gaseous state. In particular, the quantities refer to a completely transferred into the gas phase lamp filling.

Also important for the invention is the proportion of bromide in the lamp filling. According to the invention this amounts to at least 14 mol% of the total amount of halogen. The halogen can either consist entirely of bromide or of a mixture of halides. In the case of a halide mixture, preference is given in particular to iodide as further halide. The halide is used in a conventional manner to ensure the halogen cycle, facilitates the evaporation of the metallic components of the lamp filling and counteracts a blackening of the lamp envelope. The halide is usually introduced in bound form into the discharge space, ie in the form of a metal halide.

Another important component of the lamp filling of the discharge lamp according to the invention is iron. This can be filled into the discharge space as metallic iron and / or in the form of an iron halide, in particular in the form of iron iodide. The amount of iron is preferably between 0.1 and 2.5 μmol Fe / cm ^{3 of} the internal volume of the discharge space, in particular at 0.25 to 2 μmol / cm ³ . The addition of iron is a significant increase in spectrally integrated UV-A radiation in the wavelength range of 315 nm to 400 nm achieved. In this way, the 365 nm emission line of mercury in mercury-containing metal halide high-pressure lamps can be replaced. The increase of the spectrally integrated UV-A radiation can be up to a factor of 2.5 compared to a structurally identical mercury-containing high-pressure discharge lamp.

Finally, at least one noble gas is present in the discharge lamp according to the invention as a mandatory component of the lamp filling. In principle, the noble gas may be any known noble gas. However, preference is given to using xenon and / or argon and in particular xenon alone. The noble gas serves mainly to improve the starting characteristics of the discharge lamp. The pressure of the inert gas is suitably in the range of a few hPa up to several hundred hPa, for example between 10 and 600 hPa, preferably between 50 hPa and 400 hPa.

In addition to the above-mentioned components, the lamp filling may contain further constituents, in particular further metallic elements. These serve mainly to fill in the line spectrum to obtain the desired spectral distribution. For example, the lamp fill may include at least one of thallium, cobalt, tin, palladium, ruthenium, and silver. These metals are preferably added in the form of their halides, bromide and / or iodide are again preferred. A preferred lamp fill contains, for example, zinc bromide, iron iodide and thallium iodide. In addition, zinc iodide may also be added. On the other hand, sodium halides and in particular sodium iodide are preferably dispensed with in order to avoid the undesired intense spectral lines of this metal.

As already mentioned, the invention is suitable for use in a large number of differently shaped lamp envelopes. Lamp geometry and size have little influence on the radiation power achieved. In this respect, no special requirements are made on the dimensions of the discharge vessel, as for example in the WO-A-99/05699 or JP 0929348 A the case is. The high-pressure discharge lamp may be a short-arc or long-arc lamp. Thus, the discharge vessel, for example, be substantially spherical, oval or elongated cylindrical. Conveniently, quartz glass is used for the lamp envelope, as usual in the prior art. The gas-tight closure is preferably achieved by means of crimp sealing, wherein molybdenum foils are preferably used for connecting the electrodes. The electrodes are also basically formed as in the prior art. It is not imperative that the electrodes are arranged in a symmetrical manner in the discharge vessel or identical.

The high-pressure discharge lamp according to the invention can be operated with any suitable ballasts, wherein the ballasts lead to different current and voltage entries for the same constant power input. The desired radiation efficiency of the mercury-free metal halide high-pressure discharge lamp can be achieved independently of the respective mode of operation of the lamp. This is explained by the fact that the radiation-determining filling fraction in the discharge vessel (at least metallic iron and / or at least one iron halide) remains the same in different modes of operation.

The mercury-free metal halide high-pressure discharge lamp according to the invention is preferably used in a device for generating ultraviolet radiation, in particular in the UV-A range. The preferred use of the mercury-free metal halide high pressure discharge lamp is that in a photochemical process plant, for example for paint curing, disinfection and / or for tanning purposes.

Figur 1

eine schematische Darstellung einer Hochdruckentladungslampe mit einer ersten Geomet- rie;

Figur 2

eine schematische Darstellung einer Hochdruckentladungslampe mit einer zweiten Geo- metrie;

Figur 3

eine schematische Darstellung einer Hochdruckentladungslampe mit einer dritten Geomet- rie;

Figur 4

das Spektrum einer quecksilberhaltigen Lampe des Standes der Technik;

Figur 5

das Spektrum einer erfindungsgemäßen quecksilberfreien Lampe;

Figur 6

einen Vergleich der Spektren der Figuren 4 und 5;

Figur 7

ein Diagramm, das die Abhängigkeit der integrierten Strahlungsintensität vom Bromidanteil der verwendeten Halogene gemäß einer ersten Versuchsreihe mit einer Lampengeometrie gemäß Figur 1 darstellt; und

Figur 8

ein Diagramm, das die Abhängigkeit der integrierten Strahlungsintensität vom Verhältnis der Zinkkonzentration zu elektrischer Feldstärke darstellt.

The invention will be described in more detail below with reference to the accompanying drawings. The figures describe only preferred embodiments, to which the invention is not limited. In the drawings show schematically:

FIG. 1

a schematic representation of a high-pressure discharge lamp with a first geome- rie;

FIG. 2

a schematic representation of a high pressure discharge lamp with a second geometry;

FIG. 3

a schematic representation of a high-pressure discharge lamp with a third Geomet- rie;

FIG. 4

the spectrum of a mercury-containing lamp of the prior art;

FIG. 5

the spectrum of a mercury-free lamp according to the invention;

FIG. 6

a comparison of the spectra of FIGS. 4 and 5 ;

FIG. 7

a diagram showing the dependence of the integrated radiation intensity of the bromide content of the halogens used according to a first series of experiments with a lamp geometry according to FIG. 1 represents; and

FIG. 8

a diagram showing the dependence of the integrated radiation intensity on the ratio of zinc concentration to electric field strength.

In the following, exemplary test series and the results obtained are described. In various series of experiments, mercury-free metal halide high-pressure discharge lamps were provided with different fillings. The integrated radiation intensity of the high-pressure discharge lamp produced in this way was compared with the integrated radiation intensity of a structurally identical mercury-containing lamp. Subsequently, the geometry of the lamps used was varied to investigate a possible influence of the lamp geometry on the integrated intensity. Furthermore, the lamps were operated at different operating modes to investigate a possible influence of the different modes of operation on a change in efficiency, that is, the integrated radiation intensity of the high-pressure discharge lamp according to the invention, compared with a structurally identical mercury-containing high-pressure discharge lamp. Furthermore, the discharge lamps were operated with different ballasts.

FIG. 1 shows a schematic representation of a high-pressure discharge lamp with a first geometry. It comprises a cylindrical discharge vessel 1 into which a pair of electrodes with two electrodes 2a and 2b projects. The two electrodes 2a and 2b face each other with a distance d of 33 mm. The distance is measured from electrode tip to electrode tip. Between the electrodes, an arc is formed with a corresponding potential difference. The inner diameter ID of the discharge vessel is 10.5 mm in the first geometry. The internal volume IV of the discharge vessel is 3.1 cm ³ .

FIG. 2 shows a schematic representation of a high-pressure discharge lamp with a second geometry. Compared to the first geometry, in the high pressure discharge lamp with the second geometry, the electrode gap d is greatly increased. He is now 110 mm. The inner diameter ID of the discharge vessel 1 was only slightly increased in contrast. It is 16.5 mm for the second geometry. The internal volume IV is 24 cm ³ .

FIG. 3 shows a schematic representation of a high-pressure discharge lamp with a third geometry. The electrode spacing d between the electrodes 2a and 2b is 30 mm. The inner diameter ID of the discharge vessel is 21.5 mm, its inner volume IV at 9.5 cm ³ .

The high-pressure discharge lamps with the geometries 1, 2 and 3 were now provided with different lamp fillings. The integrated intensity of the lamps was measured in the range of 315 to 400 nm. In each case a structurally identical mercury-containing high-pressure discharge lamp, that is, the in FIGS. 1, 2 and 3 For comparison purposes, lamps were provided with a mercury-containing filling and the integrated intensity of the mercury-containing lamp in the range between 315 and 400 nm was determined for reference purposes. The corresponding examples are given below and summarized in Table 1:

Comparative Example 1

In a discharge vessel made of quartz glass corresponding to that of the FIG. 1 80 hPa argon, 12 mg mercury, 0.70 mg iron iodide and 0.02 mg Thalliumiodid were filled. The mercury-containing discharge lamp thus obtained was operated with a power of 400 W, a lamp voltage of 114 V, a lamp current of 3.5 A and a power factor of 0.99. The spectrum of the comparison lamp is in Fig. 4 played.

Comparative Example 2

In a discharge vessel made of quartz glass corresponding to that of the FIG. 1 400 hPa xenon, 3.0 mg zinc iodide, 0.98 mg iron iodide and 0.02 mg thallium iodide were charged. The mercury-free and bromide-free discharge lamp thus obtained was operated with a power of 400 W, a lamp voltage of 60 V, a lamp current of 6.73 A and a power factor of 0.99.

example 1

In a discharge vessel made of quartz glass corresponding to that of the FIG. 1 400 hPa xenon, 2.0 mg zinc iodide, 0.5 mg zinc bromide, 0.95 mg iron iodide and 0.02 mg thallium iodide were charged. The mercury-free discharge lamp according to the invention thus obtained was operated with a power of 400 W, a lamp voltage of 75 V, a lamp current of 5.35 A and a power factor of 0.99.

Examples 2 to 10

On the basis of example 1, further discharge lamps according to the invention were produced. The respective lamp filling is given in Table 1. The power factor was 0.99 each. For the lamp according to Example 7, the spectrum obtained is in Fig. 5 shown. Fig. 6 gives a comparison of the mercury-containing lamp of Comparative Example 1 with the lamp according to the invention of Example 7, by the spectra of both lamps are shown superimposed.

Comparative Example 3

In a discharge vessel made of quartz glass corresponding to that of the FIG. 2 50 hPa argon, 23 mg mercury, 1.96 mg iron iodide and 0.02 mg Thalliumiodid were filled. The resulting mercury-containing and bromide-free discharge lamp was operated with a power of 1200 W, a lamp voltage of 140 V, a lamp current of 9 A and a power factor of 0.95. Such lamps are used for example for UV curing. In deviation from the other examples, here and in the following examples 11 to 13, the radiation intensity was measured at a distance of 130 cm from the lamp.

Example 11

A discharge lamp according to the invention corresponding to Comparative Example 3 was produced using the method described in FIG FIG. 2 Fumed silica discharge vessel produced by xenon, 6.0 mg of zinc bromide, 1.96 mg of iron iodide and 0.24 mg thallium iodide are introduced into this 50 hPa. The thus obtained mercury-free discharge lamp according to the invention was operated with a power of 1200 W, a lamp voltage of 103 V, a lamp current of 12.3 A and a power factor of 0.95.

Examples 12 and 13

On the basis of example 11, further discharge lamps according to the invention were produced. The respective lamp filling is given in Table 1.

Comparative Example 4

In a discharge vessel made of quartz glass corresponding to that of the FIG. 3 50 hPa argon, 42 mg mercury, 2.1 mg iron iodide and 0.06 mg Thalliumiodid were filled. The resulting mercury-containing and bromide-free discharge lamp with a power of 700 W, a Lamp voltage of 130 V, a lamp current of 5.4 A and a power factor of 0.95 operated.

Example 14

A discharge lamp according to the invention corresponding to Comparative Example 4 was produced by using the in FIG. 3 Quartz glass discharge vessel produced by xenon, 1.5 mg of zinc bromide, 2.94 mg of iron iodide and 0.06 mg thallium iodide are introduced into this 400 hPa. The resulting mercury-free discharge lamp according to the invention was operated with a power of 700 W, a lamp voltage of 53 V, a lamp current of 13.5 A and a power factor of 0.95.

Examples 15 to 19

Based on example 14, further discharge lamps according to the invention were produced. The respective lamp filling is given in Table 1.

For all discharge lamps listed in Table 1 their radiation efficiency was determined. This is the radiation intensity (in (W / m ² ) / nm) of the respective lamp in the wavelength range of interest from 315 to 400 nm. Measurement is made at a distance of 115 cm from the lamp. In each case, the radiation intensity integrated over this wavelength range is determined, ie the area below the spectrum in the wavelength range from 315 to 400 nm. The relative radiation intensities are indicated in the table. The integrated radiation intensity of the mercury-containing comparative lamps of each lamp group is set at 100%. The radiation intensity of the remaining lamps of the group are given as a fraction of the 100% intensity (see right-hand column in Table 1, "Efficiency" = relative integrated radiation intensity).

The results of the series of measurements show that the discharge vessel must contain not only noble gas but also at least iron and zinc, halide and, below that, bromide in order to achieve an acceptable integrated intensity in the range 315 to 400 nm. Furthermore, it has been found that further conditions must be imposed on the proportion of bromide and on the ratio of zinc D densities and electric field E between the electrodes if the mercury-free metal halide high pressure discharge lamp is to achieve at least 63% efficiency. The proportion of the bromide must be at least 14 mol% of the total amount of halogen. For the ratio of molds of zinc D in μmol / cm ³ and electric field strength E in volts / cm between the electrodes the relation 0.005 ≤ D / E ≤ 0.200 applies. In order to achieve greater efficiency, it is necessary to increase the proportion of bromide in the total amount of halogen and to further restrict the range for the ratio of zinc molds and electric field strength E. Measured in each case at saturation, in which at least about 70% of the lamp filling of the discharge vessel is in vapor form.

FIG. 7 shows a diagram showing the dependence of the integrated intensity of the bromide content of the halogens used according to a first series of experiments with a lamp geometry according to FIG. 1 represents. In this example, an approximately linear relationship is found between the bromide content of the total amount of halogen and the integrated intensity in the wavelength range of interest between 315 nm and 400 nm. If a minimum efficiency of 63% is required, a minimum bromide content is obtained from the intersection of the degrees of equilibrium with the 63% mark to a bromide amount of at least 14 mol% of the total amount of halogen.

FIG. 8 shows a diagram representing the dependence of the integrated intensity of the ratio zinc concentration to electric field strength. The data recorded with lamps of all three geometries was entered in the diagram. Between the measuring points a compensation curve was laid. According to this compensation curve, an increase in integrated intensity occurs as the ratio of zinc concentration to electric field increases. In the range between about 0.06 (μmol / cm ³ ) / (volts / cm) and about 0.12 (μmol / cm ³ ) / (volts / cm), a maximum integrated intensity of up to about 92% achieved. In the course of the curve flattens off slowly. If at least one integrated intensity of 63% is required, the graph shows that the ratio of the densities of zinc D in μmol / cm ³ and electric field strength E in volts / cm between the electrodes satisfies the condition 0.005 ≤ D / E ≤ 0.200 must meet.

Further experiments with the mercury-free metal halide high-pressure discharge lamps according to the invention were carried out. For example, the lamps were operated during normal operation and during under-load operation. This was done at points A and B, as in Fig. 1 shown, carried out a temperature measurement. For example, at 350 W (Example No. 7) near the melting point of the iron halide from 680 ° C to 1050 ° C, only a relatively small efficiency change was found from 87% to 75%. The different modes of operation have little influence on the measured efficiency. This is explained by the fact that radiation is ultimately the iron or Eisenhalogenidfüllung the lamps. This remains unchanged in different modes.

In further experiments, the discharge lamps were operated with a variety of ballasts, which resulted in the same constant power input to a different current and voltage input. For example, a first geometry lamp (Example # 4) was operated with a commercially available inductor (power factor 0.85) and with a square wave electronic ballast (power factor 0.99). In both cases, the same efficiency value of 85% was measured. The use of different ballasts also has no influence on the expected efficiency value. This is essentially explained by the fact that the field strength is a lamp characteristic that hardly depends on power or power supply.

It has been found that it is quite possible to provide a mercury-free metal halide high-pressure discharge lamp capable of achieving a minimum efficiency of 63% (compared to a mercury reference lamp) with only certain requirements for the filling of the high-pressure discharge lamp are, however, no additional requirements on the lamp geometry are necessary. Furthermore, it has been possible to provide a mercury-free metal halide high pressure discharge lamp which operates without sodium iodide. The importance of the bromide content in the total amount of halogen for the efficiency of the lamp was recognized and also the importance of the ratio of zinc D densities and electric field strength E between the electrodes was recognized. From these findings, the conditions were derived, which are to be placed on a filling of the discharge vessel of the mercury-free metal halide high-pressure discharge lamp according to the invention.

The mercury-free metal halide high-pressure discharge lamp according to the invention can be used in particular for photochemical process plants, in particular for paint curing, for disinfection and / or for tanning purposes. In these and other fields of use, an environmentally friendly and yet efficient high-pressure discharge lamp can now be used. <b><u> TABLE 1 </ u></b> Example no. IV / cm ³ ID / mm d / mm Pressure / hPa noble gas Hg / mg ZnI ₂ / mg ZnBr ₂ / mg FeI ₂ / mg TlI / mg Radiation intensity / W / m ² Power / W Burning voltage / V Lamp current / A Efficiency /% Vgl.bsp. 1 3.1 10.5 33 80 ares 12 0 0 0.7 0.02 8.15 400 114 3.5 100 Vgl.bsp. 2 3.1 10.5 33 400 Xe 0 3 0 0.98 0.02 4.45 400 60 6.73 55 1 3.1 10.5 33 400 Xe 0 2 0.5 0.95 0.02 5.6 400 75 5.35 68.7 2 3.1 10.5 33 400 Xe 0 1.5 1 0.98 0.02 5.82 400 73 5.53 71.4 3 3.1 10.5 33 400 Xe 0 1 1.5 0.98 0.02 6.24 400 76 5.32 76.6 4 3.1 10.5 33 400 Xe 0 0 2 0.98 0.02 6.78 400 80 5.05 83.4 5 3.1 10.5 33 400 Xe 0 0 0.5 0.98 0.02 6.19 400 64 6.31 76 6 3.1 10.5 33 400 Xe 0 0 1 0.98 0.02 6.52 400 73.6 5.39 80 7 3.1 10.5 33 400 Xe 0 0 1.5 0.98 0.02 7.17 400 76.2 5.3 88 8th 3.1 10.5 33 400 Xe 0 0 2.5 0.98 0.02 6.47 400 80 5.05 79.5 9 3.1 10.5 33 400 Xe 0 0 3 0.98 0.02 5.94 400 86 5.18 73 10 3.1 10.5 33 400 Xe 0 0 3.5 0.98 0.02 5.37 400 86 5.18 66 Vgl.bsp. 3 24 16.5 110 50 ares 23 0 0 1.96 0.02 15.92 1200 140 9 100 11 24 16.5 110 50 Xe 0 0 6 1.96 0.24 13.4 1200 103 12.3 84 12 24 16.5 110 50 Xe 0 0 4 1.96 0.24 14.3 1200 98 12.9 90 13 24 16.5 110 50 Xe 0 0 1 1.96 0.24 11.5 1200 82 15.4 73 Vgl.bsp. 4 9.5 21.5 30 50 ares 42 0 0 2.1 0.06 14.4 700 130 5.4 100 14 9.5 21.5 30 400 Xe 0 0 1.5 2.94 0.06 11.5 700 53 13.5 80 15 9.5 21.5 30 400 Xe 0 0 3 2.94 0.06 13.06 700 61 11.3 90.7 16 9.5 21.5 30 400 Xe 0 0 4.5 2.94 0.06 13.25 700 70 10 92 17 9.5 21.5 30 400 Xe 0 0 6 2.94 0.06 12.7 700 73 9.6 88 18 9.5 21.5 30 400 Xe 0 0 7.5 2.94 0.06 11.3 700 81 8.6 78.8 19 9.5 21.5 30 400 Xe 0 0 9 2.94 0.06 10.5 700 87.5 8th 73

Claims (12)

A mercury-free metal halide high-pressure discharge lamp having a light-transmitting and gas-tight discharge vessel and two electrodes which project into the discharge vessel and are arranged opposite one another in the discharge vessel;
wherein the discharge vessel is filled with a lamp filling comprising:
at least one noble gas,
at least the elements iron and zinc as well
at least one halide, wherein the halide comprises bromide, and wherein the proportion of the bromide is at least 14 mol% of the total amount of halogen and for the ratio of molds of the zinc D in .mu.mol / cm ³ and electric field strength E in V / cm between the electrodes Relationship applies: 0.005 ≤ D / E ≤ 0.200. The mercury-free metal halide high pressure discharge lamp according to claim 1, wherein the iron is filled in the form of metallic iron and / or at least one iron halide. Mercury-free metal halide high-pressure discharge lamp according to claim 1 or 2, wherein the iron in an amount of 0.1 to 2.5 .mu.Mol / cm ^{3 of} the internal volume of the discharge space, in particular from 0.25 to 2 μmol / cm ³ , is filled. Mercury-free metal halide high-pressure discharge lamp according to one of the preceding claims, in which the zinc is filled in the form of zinc halide, in particular zinc bromide and / or zinc iodide. A mercury-free metal halide high pressure discharge lamp according to any one of the preceding claims, wherein the lamp fill contains at least one of thallium, cobalt, tin, palladium, ruthenium and silver. The mercury-free metal halide high pressure discharge lamp of claim 5, wherein the lamp fill contains zinc bromide, iron iodide and thallium iodide. The mercury-free metal halide high pressure discharge lamp of claim 6, wherein the lamp fill further contains zinc iodide. Mercury-free metal halide high-pressure discharge lamp according to one of the preceding claims, wherein the at least one noble gas comprises xenon and / or argon and in particular consists of xenon. A mercury-free metal halide high pressure discharge lamp according to any one of the preceding claims, wherein the lamp fill contains no sodium iodide. A mercury-free metal halide high pressure discharge lamp according to any one of the preceding claims, wherein the ratio of zinc dikes in μmol / cm ³ and electric field intensity E in V / cm between the electrodes has the following relation: 0.01 ≤ D / E ≤ 0.18 and in particular 0.025 ≦ D / E ≦ 0.165. An apparatus for generating ultraviolet radiation comprising the mercury-free metal halide high pressure discharge lamp according to any one of claims 1 to 10. Use of the mercury-free metal halide high-pressure discharge lamp according to one of Claims 1 to 10 in a photochemical process installation, in particular for lacquer curing, for disinfection and / or for tanning purposes.

Images