EP2052405B1 - Starter member for a low-pressure discharge lamp - Google Patents

Abstract

Disclosed is a starter member to which a mercury-absorbing layer is applied and which can be used in low-pressure mercury discharge lamps. A starter member for a low-pressure amalgam discharge lamp comprises a mercury-absorbing layer on a base. A coating layer which is provided on the mercury-absorbing layer has a getter effect and prevents the material of the mercury-absorbing layer from coming off.

Description

Technical area

The present invention understood a starter body for a low-pressure discharge lamp, d. H. in particular a low-pressure mercury discharge lamp and an amalgam low-pressure discharge lamp, a low-pressure discharge lamp with such a starting body and a method for producing such a starting body.

State of the art

Low-pressure mercury discharge lamps, which have pure mercury in contrast to amalgam low-pressure discharge lamps for generating the luminous flux in the discharge vessel, have the advantage that the mercury vapor pressure at room temperature and thus the initial luminous flux are relatively high.

In Fig. 1 the luminous flux over the starting time for mercury low-pressure discharge lamps is reproduced. Fix. 1 it can be seen that the instantaneous light shortly after switching on the low-pressure discharge lamp is only at a size of 30% compared to the stabilized value present after 180 seconds.

From the publication DE 69607741T2 a device for the release of mercury for the absorption of reactive gases and the electrode shielding in low-pressure discharge lamps is known, wherein on a metallic strip in a cold rolling process side by side strips of mercury-emitting material and powdered getter material be rolled out. From these strips so-called shielding can be formed, which are arranged in the vicinity of the electrode or surrounding it. As a result, emitter material removed by sputtering can be prevented from being deposited on the phosphor layer in the electrode region, thus preventing blackening. The getter materials avoid reactive gases, such as hydrogen, oxygen and water, which impair the functional efficiency of the fluorescent tubes. In such a low-pressure discharge lamp, the metallic strip has the function of mercury release, reactive gas sorption, and electrode shielding. However, the luminous flux profile of such a low-pressure mercury discharge lamp does not yet fully meet the expectations of consumption.

Amalgam low-pressure discharge lamps have a low mercury vapor pressure at room temperature, whereby the initial luminous flux is relatively low, and the start-up time is also relatively long due to only a slow increase in the vapor pressure after switching on.

In a known embodiment of the amalgam low-pressure discharge lamps, both a working amalgam and a starting amalgam are provided. The starting amalgam is located near the helix, for example on the glass bead holding the power supply wires together. Such a Aniaufärnalgam the start-up time can be reduced. The prerequisite is that sufficient time is available before switching on, so that a sufficient amount of mercury is absorbed by the starting amalgam.

Out Fig. 2 It can be seen that in such amalgam low-pressure discharge lamps up to about 2000 seconds after the start of the low-pressure discharge lamp, a lumen hole occurs. This is due to the fact that after a release of the mercury from the start-up flag, a supersaturation of the gas phase with mercury occurs. When the working amalgam has substantially completely taken up the liquid mercury, the luminous flux begins to rise again.

The documents EP1069595 and EP176627 disclose low-pressure mercury discharge lamps with a starter body as an additional flag in the vicinity of each of the electrodes. The start-up body has a mercury-absorbing indium layer through which mercury can be absorbed before the start of the lamp.

Presentation of the invention

The object of the present invention is to provide a starting body for a low-pressure discharge lamp, by which an increased luminous flux after switching on the low-pressure discharge lamp is enabled and the life of the lamp is increased. Furthermore, a low-pressure discharge lamp is to be created with such a starter body and a method for producing such a starter body.

This object is achieved by the features of claims 1, 2, 7 and 13.

There is provided a starter body for a mercury toggle pressure discharge lamp, which has a mercury-containing layer through which mercury can be accommodated in the time-out of the lamp between two starts. As a result, the startup behavior of the low-pressure discharge lamp can be improved.

The start-up body has a coating layer covering the mercury-absorbing layer at least in sections, which does not form amalgam with mercury and which preferably comprises titanium. This makes it possible to reduce the oxidation of the mercury-absorbing layer, which can occur, for example, during the production process, and at the same time achieve a getter effect.

Furthermore, according to the invention, a starter body for an amalgam low-pressure discharge lamp is provided, which has a mercury-absorbing layer, by means of which mercury can be accommodated before the start of the lamp, and a coating which at least partially covers the mercury-absorbing layer. The coating mix mercury does not form an amalgam and preferably has titanium. In this way, the getter effect can also be utilized in amalgam low-pressure discharge lamps and the oxidation behavior of the mercury-absorbing layer can be improved. As a result, a lightening hole of shorter length and lower depth can be obtained.

It is preferred if the mercury-absorbing layer has indium, by means of which a rapid uptake and release of mercury can be realized.

The titanium-containing coating is preferably made of titanium powder, concretes and water, so that an excellent Getterwirkung is feasible.

In a preferred embodiment, titanium is applied in an amount of about 1 to 2 mg, preferably 1.5 mg, so that, with good blockage of the oxidation of the mercury-absorbing layer, excellent uptake and release of mercury by the mercury-accepting Layer is feasible and at the same time the getter effect of the coating layer can be realized.

The starting body preferably has a base body which is made of stainless steel, since it does not undergo amalgam compound with mercury.

Furthermore, according to the invention, a low-pressure discharge lamp is provided with a discharge vessel, two electrodes and a starter body described above, which is arranged in the vicinity of at least one of the electrodes. In this way, it is ensured that when the titanium coating layer is applied, the required temperature range for the getter effect of the titanium can be achieved.

In one embodiment of the low-pressure discharge lamp, a starter body is assigned to each of the electrodes, so that the starting behavior of the low-pressure discharge lamp is promoted at each electrode.

It is preferable that the distance between the startup body and a helix of an electrode is selected in such a manner that the temperature at the startup body is in the range between 250 ° C and 400 ° C, more preferably in the range between 300 and 350 ° C to achieve an excellent gettering effect.

The distance between the starting body and a helix of an electrode is preferably 1 to 2 mm, so that the temperature at the starter body for the getter effect can be achieved.

The mercury-absorbing layer is more preferably provided in such an amount at the starter body that the amount of mercury released by the starter body substantially compensates for the loss of mercury due to adsorption in the starting phase of the lamp. As a result, supersaturation of the gas phase with mercury is avoided and an excellent start-up behavior is achieved.

It is further preferred that the mercury-absorbing layer is provided on the starter body in an amount such that it absorbs mercury in the range of about 5 to 10% of the amount of mercury in the discharge vessel. By experiments of the inventors has been found that this area is favorable for a particularly fast start of the low-pressure discharge lamp.

Furthermore, a method is provided for producing a starter body for a low-pressure discharge lamp, comprising the steps of providing a base body, applying a mercury-absorbing layer to the base body and providing a paste comprising titanium, and applying it at least in sections to the mercury-absorbing layer. As a result, it is possible in a simple manner to produce a starter body with a lower device-related finding.

It is preferable that the coating layer is applied by dip coating, which simplifies the manufacturing process. In a further step, after the application of the mercury-absorbing layer and of titanium, the base body can be dried so that the starting body is seductive in a short time.

It is preferred that the steps of depositing titanium and drying be repeated at least once to achieve the desired layer thickness.

Particularly advantageous embodiments can be found in the dependent claims.

Brief description of the drawings

• Fig. 1 eine Darstellung des Lichtstroms über dar Anlaufzeit bei einer Quecksilber-Niederdruckentladungslampe,
• Fig. 2 den relativen Lichtstrom über der Zeit bei einer Amalgam-Niederdruckentladungslampe,
• Fig. 3 ein Anlaufflag mit einer aufgebrachten quecksilberaufnehmenden Schicht für eine Quecksilber-Niederdruckentladungslampe,
• Fig. 4 ein Anlaufflag mit aufgebrachter Indiumschicht und aufgebrachter titanhaltiger Schicht für eine Quecksiiber-Niederdruckentladungslampe bzw. eine Amalgam-Niederdruckentladungslampe, und
• Fig. 5 ein Entladungsgefäß einer Quecksilber-Niederdruckentladungslampe mit erfindungsgemäßen An-aufflags in schematischer Darstellung.

The invention will be explained in more detail with reference to a preferred embodiment. Show it:

• Fig. 1 a representation of the luminous flux over the startup time in a low-pressure mercury discharge lamp,
• Fig. 2 the relative luminous flux over time in an amalgam low-pressure discharge lamp,
• Fig. 3 a start-up flag with a deposited mercury-absorbing layer for a low-pressure mercury discharge lamp,
• Fig. 4 a start-up flag with applied indium layer and applied titanium-containing layer for a low-pressure mercury discharge lamp or an amalgam low-pressure discharge lamp, and
• Fig. 5 a discharge vessel of a low-pressure mercury discharge lamp with An-onflags invention in a schematic representation.

Preferred embodiment of the invention

Fig. 3 shows a starter body for a low-pressure mercury discharge lamp according to the first embodiment. This starting body 1 has a base body 2 made of flat material in strip form, which is preferably made of stainless steel. This round body 2 is divided approximately in the middle by a constriction 4 in two halves. The one of the halves, in Fig. 3 the right half, serves to fix the start-up flag adjacent to one electrode of the low-pressure discharge lamp and the other half, in Fig. 3 the left half serves to apply a mercury-absorbing layer 6.

In the exemplary embodiment shown, this mercury-absorbing layer 6 has indium. By the applied layer 6 is mercury from the discharge vessel of the low-pressure discharge lamp, in which the starter body 1 is introduced, are recorded in the off state of the low-pressure discharge lamp and delivered at power.

Since the start-up flag is located close to the heated electrode, quick release of the mercury occurs. This released mercury is said to compensate for the loss of mercury due to the physical adsorption of mercury on the fluorescent layer on the inside of the discharge vessel. Thus, it is preferable that the amount of indium be provided in such a manner that the amount of mercury taken up and discharged from the indium layer is at least as large as the amount of Hg in the lamp starting phase Due to the physical adsorption by the phosphorus layer of mercury is taken, but preferably is so large that at complete evaporation in the lamp, a vapor pressure of a few pascals is generated.

• Da das Entladungsgefäß im Laufe des Herstellungsprozesses erhöhten Temperaturen ausgesetzt ist, oxidiert das Indium auf dem Anlaufkörper, woraus sich wiederum ein verschlechtertes Anlauf verhalten der Niederdruckentladungslampe ergibt. Diese Oxidation kann zwar durch eine Vergrößerung des Abstandes des Anlauf körpers von der Quetschung minimiert werden, aber dadurch ergeben sich andere Nachteile, wie z.B. zu lange Lampenenden.

By a starter body 1 according to the invention, the light starting current after switching on the mercury low-pressure discharge lamp in comparison to that of Fig. 1 elevated. The provision of an indium layer on a starter body for low-pressure mercury discharge lamps, but also for amalgam low-pressure discharge lamps, results in a large number of problems:

• Since the discharge vessel is exposed to elevated temperatures during the manufacturing process, the indium oxidizes on the starter body, which in turn results in a deteriorated start-up behavior of the low-pressure discharge lamp. Although this oxidation can be minimized by increasing the distance of the run body from the pinch, but this results in other disadvantages, such as too long lamp ends.

The amount of indium is reduced by a variety of factors. The indium creeps along a gradient from low temperature to higher temperature, with the strobe usually being heavily oxidized. Furthermore, sputtering of indium occurs by the discharge, in particular due to additional contamination of the lamp and with a galvanic connection between the starter body and the Stroz. Although a bypass solution is the introduction of the starting body in the glass bead, resulting in more manufacturing problems. An overdose The amount of indium beyond the amount of 0.5 to about 1 mg per flag used in the present invention leads to increased costs in the production of the indium layer.

In amalgam low-pressure discharge lamps, a strong overshoot of the mercury vapor pressure occurs during the start-up phase, whereby the in Fig. 2 emerges after approximately two minutes. Although this overshoot can be reduced by a reduction in Indiurzu nenge, but there are the oxidation losses, which are mentioned above, so that a reduction in the amount of indium is not a solution.

In the discharge vessel impurities are present from the pumping process. Furthermore, impurities arise over the life of the lamp, in particular due to the decomposition of water due to the discharge, whereby, for example, the hydrogen concentration increases over the lifetime. This manifests itself in an increase in the burning voltage, which adversely affects the life of the lamp. These effects can be reduced by long process times and high pumping temperatures. However, this results in an increased production cost.

The above-mentioned disadvantages of the mercury-emitting layer on the starter body 1 from Fig. 3 can be characterized by a starter body 10 Fig. 4 , which can be used in low-pressure mercury discharge lamps and low-pressure discharge amalgam discharge lamps, are eliminated. The basic body 2 with constriction 4 and the mercury-absorbing layer 6 of the starting body 10 out Fig. 4 match those out Fig. 3 , On the mercury-absorbing layer 6 is in Fig. 4 in addition, a coating layer 8 comprising titanium is applied.

• Als erstes wird eine Paste aus Titanpulver und einem rheologischen Additiv vorbereitet und anschließend diese Paste durch Tauchbeschichtung auf den Anlaufkörper 1, der die Indiumbeschichtung 6 aufweist, aufgetragen. Anschließend erfolgt ein Trocken der Überzugsschicht. In Abhängigkeit von der gewünschten Schichtdicke und der gewünschten Menge an Titan am Anlaufkörper 10 kann die Tauchbeschichtung und das Trocknen einmal oder mehrmals wiederholt werden.

This application process can be carried out, for example, as follows:

• First, a paste of titanium powder and a rheological additive is prepared, and then this paste is applied by dip coating on the starter body 1 having the indium coating 6. Subsequently, a drying of the coating layer takes place. Depending on the desired layer thickness and the desired amount of titanium on the starter body 10, the dip coating and the drying can be repeated one or more times.

With such a coating layer 8 applied at least in sections to the mercury-absorbing layer 6, oxidation during the production process can be greatly reduced without the start-up behavior of the low-pressure discharge lamp deteriorating. Further, the coating layer is a great hindrance to the creep of the indium along the temperature gradient. Also, sputtering of indium is greatly reduced because the coating layer is the outer layer and thus sputtered as the first titanium.

In amalgam low-pressure discharge lamps can also make a significant reduction in the amount of indium, which can reduce costs and overshoot the luminous flux is reduced.

Since the coating layer: greatly reduces oxidation of indium, the distance between helix and starter body can be reduced, for example, to 1 to 2 mm. As a result, the starter body can be heated faster and results in a faster start-up behavior compared to starter bodies, which are mounted at a greater distance from the helix.

With a small distance between helix and starter body of the starter body is now hot enough so that the coating layer can have a Gettervairkung, especially for hydrogen, resulting from the decomposition of water. As a result, it is possible to extend the service life.

When designing the coating layer, in particular with regard to its thickness and the grain size, mercury diffusion both in the direction of the mercury transfer of the layer 6 and the mercury uptake of the layer 6 as well as the function of the coating layer as a getter, as an oxidation resistance and creep barrier must be considered.

The improved casserole behavior due to the starter bodies 1 and 10 according to the invention also has an effect on the use of the electronic ballasts for the low-pressure discharge lamp. In the circuit structure, the increased luminous flux after switching on the low-pressure discharge lamp can be considered.

In Fig. 5 a mercury low-pressure discharge lamp is shown, which has a discharge vessel 12, the three vessel segments 12a, 12b, 12c, the discharge spaces are interconnected. Each of these segments 12a, 12b, 12c is substantially U-shaped. To simplify the drawing, the segments, normally arranged in 120 ° symmetry, are shown side by side. Low-pressure discharge lamps with such discharge vessels are sold by OSRAM, for example, under the name "DULUX EL". The inner surfaces of the discharge vessel 12 are coated with a powder of fluorescent material and the discharge vessel is filled with a noble gas, preferably argon or neon, as well as with mercury vapors.

At each of the end portions of the discharge vessel, an electrode 14, 16 is provided, each of the electrodes has power supply wires 18a, 18b, 20a, 20b, which are led out of the discharge vessel and which are fixed by a glass bead 22, 24 and to the respective coils 26, 28 lead. Between the glass beads 22, 24 and respective helix 26, 28, a start-up body 10 according to the invention adjacent to helix 26, 28 is provided. At the central segment 12B of the discharge vessel 12, a cold spot 30 is shown, at which liquid mercury accumulates in the usual suspended operation of the lamp.

During operation of the lamp, the temperature at this cold spot determines the mercury vapor pressure in the lamp. When the lamp is turned off, the starter bodies 10 cool down, causing them to absorb mercury from the gaseous phase, which is supplied by the cooling point 30 until it has reached equilibrium.

When the lamp is turned on, the starter bodies 10 heated faster than the cooling point 30. During the start of the lamp from the gas phase lost mercury is therefore replenished much faster over the starter body than the cooling point, which ultimately leads to an improvement of the start-up behavior.

Due to the proximity to the helices 26, 28, the starter body 10 causes rapid release of mercury, while liquid mercury is present at the cold spot 30 due to the low temperature present and slow mercury release occurs when the low-pressure discharge lamp is switched on.

In the amalgam low-pressure discharge lamps, not shown in the figures, due to the different vapor pressure of work amalgam and starting amalgam in the on and off phases of the lamp, a redistribution of the mercury of starting amalgam in the Arbeitsamalgam and in the opposite direction. In the switch-on phase, a cold spot is formed in the meantime, by which the lamp is made into a mercury lamp.

For the working amalgam, any working amalgam can be used in the amalgam low-pressure discharge lamps according to the invention, for example a working amalgam introduced into the pump stanchion, in front of which, for example, an iron disk or iron ball is arranged, which prevents the working amalgam from penetrating into the discharge vessel. In addition, the work amalgam can be introduced, for example, applied to expanded metal in the discharge vessel. The distance between the helix and the starting amalgam is lower than the distance between the helix and the working amalgam.

For an advantageous gettering effect of the coating layer 6 both in low-pressure mercury discharge lamps and in amalgam low-pressure discharge lamp, it is preferred if the starting body is heated to a temperature in the range of 250 ° C to 400 ° C, more preferably between 300 ° C and 350 ° C is.

The present invention is not limited to the use of indium as the material for the mercury-absorbing layer 6 and the use of titanium as the material for the coating layer, but any source of mercury may be used for the mercury-absorbing layer and any material for the coating layer by which the loss process of the material of the mercury-absorbing layer is avoided and in which a getter effect is present in the operating range used for low-pressure discharge lamps.

Disclosed is a starter body, on which a mercury-absorbing layer is applied, and which is applicable to low-pressure mercury discharge lamps. A starter body for an amalgam low-pressure discharge lamp has on a base body a mercury-absorbing layer on which a coating layer is located, through which a loss process of the material of the mercury-absorbing layer can be prevented and has the gettering effect.

Claims (16)

1. Startup element (1) for a mercury low-pressure discharge lamp, which startup element comprises a mercury-absorbing layer (6), by means of which mercury can be absorbed prior to starting of the lamp, and with a coating (8), which does not form an amalgam with mercury, preferably comprises titanium and covers at least sections of the mercury-absorbing layer (6).
2. Startup element (10) for an amalgam low-pressure discharge lamp, which startup element has: a mercury-absorbing layer (6), by means of which mercury can be absorbed prior to starting of the lamp, and a coating (8), which does not form an amalgam with mercury, preferably comprises titanium and covers at least sections of the mercury-absorbing layer.
3. Startup element according to one of the preceding claims, wherein the mercury-absorbing layer (6) comprises indium.
4. Startup element according to one of the preceding claims, wherein the titanium-comprising coating (8) is at least partially composed of titanium powder.
5. Startup element according to one of the preceding claims, wherein, by means of the coating (8), titanium is applied in a quantity of approximately 1.0 to 2.0 mg/cm², preferably approximately 1.5 mg/cm², in flocks.
6. Startup element according to one of the preceding claims, wherein the startup element has a basic body (2) made from stainless steel onto which the mercury-absorbing layer (6) and the titanium-comprising coating (8) are applied.
7. Low-pressure discharge lamp with a discharge vessel, two electrodes (14, 16) and a startup element (1, 10) according to Claim 1 or 2, wherein the startup element (1, 10) is arranged in the vicinity of at least one of the electrodes, preferably as an additional flag between the attachment webs of the lamp.
8. Low-pressure discharge lamp according to Claim 7, wherein a startup element (1, 10) according to Claim 1 is associated with each of the electrodes (14, 16).
9. Low-pressure discharge lamp according to Claim 7 or 8, wherein the distance between the startup element (1, 10) and a filament (26, 28) of an electrode (14, 16) has been selected in such a way that the temperature at the startup element (1, 10) is in the range of between 250°C and 400°C, more preferably in the range of between 300 and 350°C.
10. Low-pressure discharge lamp according to one of Claims 7 to 9, wherein the distance between the startup element (1, 10) and a filament (26, 28) of an electrode is 1 to 2 mm.
11. Low-pressure discharge lamp according to one of Claims 7 to 10, wherein the mercury-absorbing layer (6) has been provided on the startup element (1, 10) in such a quantity that the quantity of mercury released by the startup element at least compensates for the loss of mercury caused by adsorption in the starting phase of the lamp.
12. Low-pressure discharge lamp according to one of Claims 7 to 11, wherein the mercury-absorbing layer (6) has been provided on the startup element in such a quantity that said layer generates a vapor pressure of a few pascals in the lamp within a typical off time of the lamp of a few hours given complete evaporation.
13. Process for the production of a startup element for a low-pressure discharge lamp having the steps of a) providing a basic body (2), b) applying a mercury-absorbing layer (6) to the basic body, and c) providing a slurry which comprises titanium and applying said slurry to at least sections of the mercury-absorbing layer (6).
14. Process according to Claim 13, wherein, in step c), the application takes place by means of dip-coating.
15. Process according to Claim 13 or 14 with a step d), which follows on from step c) and in which the basic body (2) coated with the mercury-absorbing layer and titanium is dried.
16. Process according to Claim 15 with a step e), which follows on from step d) and in which steps c) and d) are repeated at least once.

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