EP1351278A2 - Metal halide lamp with ceramic discharge vessel - Google Patents

Abstract

The lamp has a ceramic discharge vessel with ends sealed by ceramic stoppers with capillaries for electrical lead through and sealed with glass solder and consisting of inner (13) and outer (14) parts. The composite inner part has a core pin (18) to which a coil tube (20) is applied as at least a double layer with an effective diameter of the coil tube wire that is less than or equal to the core pin diameter and fulfills specified conditions.

Description

Technical field

The invention is based on a metal halide lamp with a ceramic Discharge vessel according to the preamble of claim 1 in particular lamps with an output of at least 70 W, preferably from 100 W up to powers over 1000 W.

State of the art

EP-A 587 238 describes a metal halide lamp with a ceramic discharge vessel known, in which a two-part implementation in an elongated Stopper capillary by means of glass solder at the end of the Plug is sealed. The outer part of the bushing is permeable Material (niobium stick), the inner part made of halide-resistant material (for example a pen made of tungsten or molybdenum). The inner part 8 can have an envelope by the pin with a Spiral part is wrapped. The concept presented in this document however, it is only suitable for smaller outputs up to 150 W. poor adaptation of the thermal expansion coefficient leads at high outputs and correspondingly high temperature changes often to cracks in the wall of the ceramic capillary tube. This Cracks increase with increasing diameter of the molybdenum stick. A Similar solution is also described in WO 95/28732.

Another solution has so far been used for higher lamp outputs (up to approximately 400 W) applied, which is also described in EP-A 587 238, namely the Replacement of the inner Mo pin part with a cermet part. Its thermal Expansion coefficient can be set as desired between the other metal parts and that of ceramics. A disadvantage of cermet solutions is not only the high price, but also the inadequate strength of one achievable weld connection. In addition, it can be chemical Reactions occur between components of the cermet and the filling, due to the high operating temperatures.

So far there is no convincing for even higher lamp outputs Concept.

Presentation of the invention

It is an object of the present invention to use a metal halide lamp to provide a ceramic discharge vessel according to the preamble of claim 1, whose implementation is designed so that it is not only for small, but especially for larger wattages (typically 150 to 400 W) is suitable, so that for the first time a uniform basic concept is available stands.

This object is achieved by the characterizing features of claim 1 solved. Particularly advantageous configurations can be found in the dependent ones Claims.

With increasing wattage, the diameter usually also increases the implementation and therefore also the inner diameter of the Stopper capillary. Reliable for cracks in the sealing area to prevent this, another solution was therefore developed.

Specifically, it is a metal halide lamp with a ceramic Discharge vessel, in particular made of aluminum oxide, the discharge vessel has two ends, which are closed with ceramic plugs are (underneath is a separate part or an integral part of the discharge vessel trained part to understand), each an elongated capillary tube (hereinafter called stopper capillary), and by this Plug capillary is an electrically conductive two-part bushing that is covered on the discharge from an inner part and an outer pin-shaped Part exists, is led through vacuum-tight. The implementation is sealed on the outside of the stopper by glass solder. Implementation is inside an electrode with its shaft attached to the inside of the discharge vessel protrudes.

The inner part of the bushing contains a pin made of a halide resistant Metal (preferably molybdenum or tungsten or their alloys), whose diameter is a maximum of 0.5 mm, and that of one multilayer spiral, preferably a double layer, the same or equivalent material is encased. The material is preferably molybdenum for both the core pin and the multi-layer spiral. This has the decisive advantage that the absolute dimensions of each Components (core pin and helix) due to their small absolute dimensions are below a critical size, so that no cracks in the Melting area after melting and also during lamp operation occur. The electrode system remains due to the multi-layer spiral flexible so that tension caused by the expansion in operation or occur during the melting process can.

The bottom line is that all of these helix geometries cool down after the melting process due to the different expansion coefficients the implementation, especially the spiral, and the surrounding ceramics, i.e. the capillary and the one that passes on its pressure Enamel ceramic / glass solder, come under pressure. This Tensions have to be reduced by a single plastic deformation, by pushing the spiral into the core pin. It is advantageous here the smallest possible contact area.

The special effect of a double or multiple layer Gewendels is now that the stress relieving effect a second time and can be used very effectively by changing the outer layer presses into the inner layer. Because a spiral is much easier deformable as a solid core wire. This mechanism is particularly effective then when the outer layer is relative to the inner layer of the helix is wound in opposite directions, because then systematically crossing points with high Print run arise. The same applies to multiple layers.

A similarly effective stress relief is conveyed if instead of several Layers a wound spiral wire is used. In this case arises even a particularly high pressure in the area of the contact surfaces on Core wire and on the inner wire because of the diameter of the core wire slightly smaller than that of the helical inner wire can. The diameter w of the wrapping wire is preferably 30 to 70% of the diameter W of the helix wire.

In lamp operation, the voltages are due to the low operation Temperatures at the sealing point (compared to the melting temperature) smaller than in the melting process. You can therefore by elastic deformation the components are dismantled. Plastic deformation would be here lead to premature leakage.

The outer part of the feedthrough is located in the stopper capillary Length sealed with glass solder. In addition there is a subsequent one Area of the inner part of the passage over a small part the length (approx. 1 to 2 mm) sealed with glass solder. It has proven to be essential for a long lifespan it was found that the inner part is a has outer dimensions that are at least 0.8 times and maximum corresponds to 0.98 times the inner diameter of the capillary.

Other essential requirements are that the maximum diameter of the core pin is less than or equal to 0.5 mm and that the diameter of the layers of the helix wire corresponds to the diameter of the core pin. However, the diameter of each layer is preferably smaller than that of the core pin. The diameters of the two layers do not have to be the same.

The lamp power is preferably between 100 and 1000 W, however also larger powers (2000 W and more) as well as smaller powers (for example 70 W) are possible.

If one designates D the diameter of the core wire and d that of the helix wire as well as K the inner diameter of the capillary, the following applies: 0.8 K ≤ S ≤ 0.98 K.

S is the total diameter of the inner part of the bushing, generally S = D + nd, where n is the number of formal layers. In the case of a double layer, S = D + 4d. According to the invention, it has been shown that reliable melting is achieved if the following applies to the diameter D of the core pin: 0.16 K ≤ D ≤ 0.40 K.

The following should also apply to the diameter d of the helical wire: 0.10 K ≤ d ≤ 0.195 K.

In the case of a different diameter of the two helical layers (d ₁ and d ₂ ), the following formulas should apply: d ₁ + d ₂ = 2 d. In other words, an effective mean diameter d can then be expected. In general, it can be expressed in several layers by d ₁ + .... + d _n = nd, so that d = (d ₁ + .... + d _n ) / n.

In a further alternative embodiment, which can be used from 150 W, the core wire is wrapped with a wound spiral wire. Basically, the following applies here if D is the core wire diameter, W is the filament wire diameter and w is the core wire diameter S = D + 2 (W + 2 w) with the boundary condition D> (W + 2w).

This boundary condition arises for technical winding reasons, since the Core wire must be thicker than the wound spiral wire.

The ranges for D and d given above also apply here.

The following applies to w 0.04 K <w <0.1 K.

With high wattages from 600 W (especially around 1000 W and more) it can occur that the maximum diameter according to the original o.e. Formula could be over 0.5 mm, but in the sense of a permanent seal should be avoided. In such cases, a is advantageous modified spiral used by either laying a third layer over the double layer is used, or by not removing at least one layer a single helix (single-coiled, sc), but from a double helix (coiled-coil, cc or wound wire) is similar to the above already described as an alternative for smaller wattages.

For wattages from 100 to 1000 W, in particular with double layers, the following applies particularly preferably: 0.25 K ≤ D ≤ 0.30 K.

The following should also apply to the diameter d of the helical wire: 0.12 K ≤ d ≤ 0.15 K.

The diameter of the core pin should preferably be at most 0.35 mm.

A well-coordinated relationship between spiral wire and core pin lies in the area (0.90 K - D) / 4 ≤ d ≤ (0.96 K - D) / 4.

The present invention uses a two-part implementation, consisting of an outer part which is adapted to the (aluminum oxide) ceramic in terms of its thermal expansion and is permeable to H ₂ and O ₂ (in particular a pin or tube made of niobium, but the use of tantalum is also possible) which is covered and sealed with glass solder, and an inner part which is halide-resistant and which is only partially covered and sealed with glass solder at its outer end. The inner part is a very thin wire made of molybdenum or of the higher melting tungsten. The tungsten can have a rhenium additive, either as an alloy or as a surface plating. The rhenium increases the high temperature resistance and corrosion resistance of the tungsten. While molybdenum is particularly suitable for fillings containing mercury, W is advantageously used for fillings free of mercury. In particular, W is also suitable for relatively small watt lamps from 70 W.

The inner part is on one side with the outer part (niobium stick or tube) and connected to the electrode on the other side.

The stopper can be made in one part, but also in several parts. For example can in a manner known per se a stopper capillary from an annular Be part of the plug.

After all, unlike the prior art, it doesn't matter how the outer part is inserted deep into the capillary. It's just one Minimum depth of 2 mm necessary for a reliable seal. The maximum insertion depth should preferably be 50% of the thermal reasons Do not exceed the length of the capillary.

The outer part is over its length located in the stopper capillary completely melted into the glass solder, the inner part over a length from about 1 to 2 mm at its outer end. It is important that the niobium stick due to the corrosive attack of the filling on niobium completely by glass solder is covered.

Brief description of the drawings

Figur 1

eine Metallhalogenidlampe mit keramischem Entladungsgefäß

Figur 2

den Endbereich der Lampe der Figur 1 im Detail

Figur 3

ein weiteres Ausführungsbeispiel eines Endbereichs

Figur 4 und 5

je ein weiteres Ausführungsbeispiel eines Endbereichs.

The invention will be explained in more detail below with the aid of several exemplary embodiments. They show schematically:

Figure 1

a metal halide lamp with a ceramic discharge vessel

Figure 2

the end of the lamp of Figure 1 in detail

Figure 3

another embodiment of an end region

Figures 4 and 5

each another embodiment of an end region.

Preferred embodiment of the invention

FIG. 1 shows schematically a metal halide lamp with an output of 150 W shown. It consists of a lamp axis defining cylindrical outer bulb 1 made of quartz glass, squeezed on two sides (2) and is socketed (3). The axially arranged discharge vessel 4 made of A1203 ceramic is cylindrical or bulbous in shape and has two ends 6. It is by means of two power leads 7, which with the base parts 3 over foils 8 are connected, held in the outer bulb 1. The power supply lines 7 are welded to bushings 9, 10, each in an end plug 12 are fitted at the end 6 of the discharge vessel. The plug part is as an elongated capillary tube 12 (capillary) executed. The end 6 of the discharge vessel and the stopper capillary 12 are, for example, together sintered directly.

The bushings 9, 10 each consist of two parts. The outer part 13 is designed as a niobium stick and extends up to about a quarter of the Length of the capillary tube 12 into this. The inner part 14 extends within the capillary tube 12 towards the discharge volume. It stops on the discharge side Electrodes 15, consisting of an electrode shaft 16 Tungsten and one pushed onto the discharge end of the shaft Spiral 17. The inner part 14 of the implementation, specifically the core pin, is in each case with the electrode shaft 15 and with the outer Part 13 of the bushing welded.

In addition to an inert ignition gas, the discharge vessel is filled, e.g. Argon, from mercury and additives to metal halides. Is possible for example, the use of a metal halide filling without Mercury, preferably xenon and in particular a high ignition gas Pressure well above 1.3 bar can be selected.

An end region of the discharge vessel is shown in detail in FIG. 2. As Implementation 9, 10 serves a system consisting of a niobium stick (or also tube) as outer part 13 with a diameter A and a thin one Molybdenum pin 18 (diameter B, see table below) 1) as part of the inner part 14, over the two layers of a molybdenum coil 20 are each pushed with a wire diameter C. The total length of the capillary tube 12 is about 17 mm, that of the niobium stick 13 D, and that of the inner part 14 is E, with an inner diameter of the stopper capillary from F.

The niobium pin 13 is on the discharge side with the core pin 18 made of molybdenum butt welded. The core pin 18 is the same on the discharge side Way welded to the electrode shaft 16.

The niobium pin 13 is inserted approximately 3 mm deep into the capillary 12 and sealed by means of glass solder 19. It is important that the glass solder completely covers this niobium stick and that the beginning of the inner part (1 to 2 mm) is still covered by the glass solder. power characteristic 150 W. 250 W. 400 W. Nb pin diameter (mm) A 0.88 1.00 1.30 Diameter of Mo core pin (mm) B 0.25 0.30 0.30 Diameter of Mo coil (mm) C 0.15 0.18 0.25 Length of Nb pin (mm) D 8th 10 12 Inner part length (mm) e 10 13 17 Min. Inner diameter of capillary tube (mm) F 0.90 1.05 1.35

In one embodiment of a 150 W lamp according to FIG the dimensions of the enclosed Tab. 1 used. Are in the same way the preferred dimensions are also given for wattages of 250 W and 400 W.

Tab. 2 shows the typical inside diameter of the capillary tube as well as the minimum and maximum permissible diameters of the core pin 18 (D) and the helix 20 (d) for different performance levels. The same diameter is assumed for both layers, which is often the simplest and best solution. However, the diameter of the two layers can also be different, in particular the diameter of the outer layer can be selected to be significantly smaller (30% and more) than that of the inner layer. power stage typ. capillary inner diameter D-min D-max d-min d-max [W] [mm] [mm] [mm] [mm] [mm] 70 0.80 0,128 0.32 0.116 0.164 100 0.85 0,136 0.34 0.123 0.174 150 0.95 0,152 0.38 0.138 0.195 200 1 0.16 0.4 0.145 0,205 250 1.1 0.176 0.44 0,159 0.226 300 1.2 0.192 0.48 0.174 0.246 350 1.3 0.208 0.5 0.193 0,267 400 1.4 0.224 0.5 0.218 0.287 600 1.5 0.24 0.5 0,242 0.308 1000 2.2 0.352 0.5 0.414 0,451 2000 3.1 *) *) *) power stage typ. capillary inner diameter D-preferred min D-preferred max d-preferred min d-preferred max [W] [mm] [mm] [mm] [mm] [mm] 70 0.80 0.16 0.24 0.12 0.156 100 0.85 0.17 0,255 0,128 0.166 150 0.95 0.19 0.285 0.143 0.185 200 1 0.2 0.3 0.15 0.195 250 1.1 0.22 0.33 0,165 0.214 300 1.2 0.24 0.35 0.183 0.234 350 1.3 0.26 0.35 0,205 0.253 400 1.4 0.28 0.35 0.228 0,273 600 1.5 0.3 0.35 0.25 0.292 1000 2.2 *) *) *) 2000 3.1 *) *) *) *) power stage typ. capillary inner diameter D optimized d optimized [W] [mm] [mm] [mm] 70 0.80 0.20 0.14 100 0.85 0.212 0,149 150 0.95 0.237 0.166 200 1 0.25 0,175 250 1.1 0,275 0.192 300 1.2 0,295 0.211 350 1.3 0,305 0.232 400 1.4 0.315 0,254 600 1.5 0,325 0,275 1000 2.2 *) 2000 3.1 *) *)

Furthermore, Table 3 is a preferred one for different power levels Range given for the values discussed in Table 2. Finally is Table 4 shows an optimal value for D and d for specific wattages.

With high-wattage power levels, the specified condition is partial no longer easily feasible, in these cases alternatives can also be provided Techniques are used.

The simplest alternative is to use another layer of the helix 21 as shown in Figure 3. In this version of a triple helix 21 for a 1000 W lamp, the core wire has a diameter of 0.35 mm and the coiled wire a diameter of 0.29 mm.

Further examples of this technique are shown in Table 5, the power level, the inner diameter of the capillary tube and the diameters of the core pin and the helical wire being indicated. Of course, the diameter of individual layers can also differ here. Examples of three-layer spiral power stage typ. capillary inner diameter D D [W] [mm] [mm] [mm] 600 1.5 0.3 0.19 1000 2.2 0.35 0.29 2000 3.1 0.45 0.42

Finally, a similar effect can also be achieved in that instead of a multiple layer of a spiral, a double-spiral spiral (cc) is used in single or double position. The simple location a double helix corresponds to approximately three times Location of a single helix. The core wire of the spiral which acts formally as a middle layer, usually a larger diameter than the wire spun on it, the inner and outer layer forms.

The principle is shown in FIG. The molybdenum core wire 25 has a diameter of 0.35 mm for a 1000 W lamp. The cc coil (one layer) applied thereon has an inner pin 26 (core wire of the coil) with a diameter of 0.35 mm (formally middle layer) and a wire spun thereon with a diameter of 0.25 mm, which thus formally inner and outer layer 27 and 28 forms. Tab. 6 shows several examples of such high-wattage lamps. Examples of simple cc filaments: D = inner core wire; W = core wire Gewendel; w = spiral wire power stage typ. capillary inner diameter D W w [W] [mm] [mm] [mm] [mm] 600 1.5 0.3 0.2 0.18 1000 2.2 0.35 0.32 0.27 2000 3.1 0.45 0.43 0.41

The double layer of a double helix corresponds approximately a formal sixfold layer of a simple spiral. It is in each case the diameter of the layers varies.

According to FIG. 5, a double layer of a cc coil is on the core wire 30 applied, each layer is a double helix (cc) with core wire. The Dimensions of the two layers can be different. The first layer has a first core pin 31 (formally it forms the second layer) around which one Coil is wound, which formally form the first and third layers 32, 33. In the same way, the second layer has a second core pin 34 (formal fifth layer), around which a coil is wound, which formally is the fourth and sixth layer 35, 36 forms.

Table 7 shows the dimensions of the core pin and the double helix for different wattages. The latter is used for both layers. Examples of two layers of a cc coil; D = inner core wire; W = core wire Gewendel; w = spiral wire power stage typ. capillary inner diameter D W w [W] [mm] [mm] [mm] [mm] 600 1.5 0.2 0.15 0.08 1000 2.2 0.25 0.2 0.13 2000 3.1 0.28 0.28 0.19

Table 8 shows the dimensions of the core pin and the wound coil (one layer of a cc coil) for 150 - 400 W. The latter is only one layer on the core pin in these embodiments. A concrete example is a 150 W lamp with a feedthrough that has a Mo part, in which the core wire has a diameter of 0.3 mm, while the helical wire has an inner winding wire of 0.13 mm diameter, which with a thin wire of 0.07 mm diameter is wound. Formally, this results in a three-layer spiral with any number of crossing points. The advantage of this embodiment is in particular that the core wire also has only contact points with the coil, while in the sc versions the innermost layer has a continuous contact surface on the core wire. This example corresponds to the illustration in FIG. 4. Examples of a layer of a cc coil; D = inner core wire; W = core wire Gewendel; w = spiral wire power stage typ. capillary inner diameter D W w [W] [mm] [mm] [mm] [mm] 150 0.95 0.3 0.13 0.07 250 1.0 0.4 0.16 0.07 400 1.3 0.5 0.2 0.1

Normally, all layers are tightly wrapped. However, it is not excluded that a small distance (up to 20% of the wire diameter) of the individual turns is observed. A slope factor that is too large has the disadvantage that the gaps as an additional undesirable Dead volume for the filling act.

Claims (14)

Metal halide lamp with ceramic discharge vessel (4), the discharge vessel having two ends (6) which are closed with ceramic plugs, each of which contains an elongated capillary tube (12), hereinafter referred to as stopper capillary, with an inner diameter K, and through which stopper capillary (12) an electrically conductive bushing (9, 10) which, based on the discharge, consists of an inner (14) part and an outer part (13), and is sealed on the outside with glass solder (18) so that the outer part the leadthrough is sealed with glass solder over its length located in the stopper capillary, while an adjoining area of the inner part of the leadthrough is sealed over a small part of the length from 1 to 2 mm with glass solder, an electrode (16) on the leadthrough is fastened with a shaft (15) which projects into the interior of the discharge vessel, the outer diameter S of the inner part is matched to the inner diameter K, characterized in that the inner part (14) is a composite component which comprises a core pin (18) with a diameter D to which a helix is applied at least as a double layer, with a effective diameter d of the helical wire, the following relationships being fulfilled: 0.8 K ≤ S ≤ 0.98 K d ≤ D D Max ≤ 0.5 mm 0.16 K ≤ D ≤ 0.40 K. 0.10 K ≤ d ≤ 0.195 K. Metal halide lamp according to claim 1, characterized in that both layers of the filament are formed by a simple wire. Metal halide lamp according to claim 2, characterized in that the two layers are wound in opposite directions to one another. Metal halide lamp according to claim 2, characterized in that the following applies: 0.12 K ≤ d ≤ 0.195 K. Metal halide lamp according to claim 2, characterized in that the following applies: 0.25 K ≤ D ≤ 0.30 K, 0.12 K ≤d ≤ 0.15 K. Metal halide lamp according to claim 2, characterized in that D ≤ 0.35 mm. Metal halide lamp according to claim 2, characterized in that the following applies: (0.90 K -D) / 4 ≤ d ≤ (0.96 K -D). Metal halide lamp according to claim 2, characterized in that the wire diameter of the first and second layers is the same. Metal halide lamp according to claim 1, characterized in that the filament comprises a triple layer. Metal halide lamp according to claim 1, characterized in that the helix comprises at least one layer which is itself double-wound, an inner wire with a diameter W being wound around a wire with a diameter w, so that formally a triple layer of thickness W + 2w is achieved becomes. Metal halide lamp according to claim 10, characterized in that the filament comprises two layers which are wound twice, so that a sixfold layer is formally achieved. Metal halide lamp with ceramic discharge vessel according to claim 1, characterized in that the discharge vessel consists of Al ₂ O ₃ . Metal halide lamp with ceramic discharge vessel according to claim 1, characterized in that the components of the inner part (14) consist predominantly of one of the metals molybdenum and tungsten. Metal halide lamp with ceramic discharge vessel according to claim 1, characterized in that the outer part (13) is a pin or tube made of niobium.

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