EP1119868A1

EP1119868A1 - Gas discharge lamp and method for the production thereof

Info

Publication number: EP1119868A1
Application number: EP00958191A
Authority: EP
Inventors: Michael Seibold; Michael Ilmer; Angela Eberhardt
Original assignee: Patent Treuhand Gesellschaft fuer Elektrische Gluehlampen mbH
Current assignee: Osram GmbH
Priority date: 1999-08-05
Filing date: 2000-07-28
Publication date: 2001-08-01
Also published as: JP2003506847A; US6605892B1; TW457515B; HUP0200532A2; KR20010080030A; CA2346523A1; KR100442891B1; WO2001011653A1; HU223905B1; CA2346523C; DE19936865A1

Abstract

A gas discharge lamp comprising a discharge vessel which is, for instance, made up of a base plate, a front plate (2) and a frame (3), comprising at least one closing element (6) which closes a gas discharge opening in a gas-tight manner by introducing the closing element (6) into the gas discharge opening and subsequently melting said closing element. The closing element (6) is made of a material such as sintered glass which has a lower melting point than the rest of the discharge vessel. An additional connecting element between the closing element (6) and the adjacent wall of the discharge vessel(2) can be dispensed with.

Description

Gas discharge lamp and associated manufacturing process

Technical field

The invention relates to a gas discharge lamp and its manufacture.

In particular, the invention is directed to a gas discharge lamp which is designed for dielectrically impeded discharges, in which at least the electrode (s) of one polarity is (are) separated from the discharge volume in the discharge vessel of the lamp by a dielectric layer (dielectrically impeded electrode) ,

State of the art

With preferred embodiments, the invention is also directed to flat radiator lamps and their manufacture - in particular for dielectrically impeded discharges. The technology of gas discharge lamps, in particular of gas discharge lamps for dielectrically impeded discharges and in particular of flat radiator gas discharge lamps, is assumed to be state of the art here. As an example, reference is also made to the previous German patent application 197 11 890.9 by the same applicant, the disclosure content of which with reference to the lamp technology of flat-radiator gas discharge lamps for dielectrically disabled discharges is hereby included. In addition, the invention is also directed to rod-shaped discharge lamps, in particular for dielectrically impeded discharges. In this context, reference is made to WO98 / 49712, the disclosure content of which is included with reference to the lamp technology of rod-shaped discharge lamps for dielectrically disabled discharges. In the cited document, a rod-shaped aperture discharge lamp with at least one internal strip-shaped electrode is disclosed. One end of the tubular discharge vessel of the lamp is sealed gas-tight with a stopper which is fused to a part of the inner wall of the discharge vessel by means of glass solder. The strip-shaped inner electrode is led through the glass solder as a power supply to the outside. It is disadvantageous that a glass solder layer is required as a gas-tight connecting means between the stopper and the vessel wall.

Presentation of the invention

It is an object of the present invention to provide a gas discharge lamp, the discharge vessel of which can be closed in a gas-tight manner relatively easily.

This object is achieved according to the invention by a gas discharge lamp with a discharge vessel, characterized in that the discharge vessel has at least one closure element which has been fitted and melted into a discharge vessel opening and thereby closes the discharge vessel opening in a gas-tight manner.

Preferred embodiments of the gas discharge lamp according to the invention are the subject of the dependent claims. The manufacturing process of the gas discharge lamp according to the invention is the subject of the process claim.

Further preferred features of the manufacturing process can be found in the dependent claims.

The basic idea of the invention is to close one or more openings in a discharge vessel of a discharge lamp by melting a closure element fitted into the or each discharge vessel opening. In this way, an additional connection means, e.g. a glass solder layer as in the prior art, see between the closure element and the wall of the discharge vessel opening.

By heating it is achieved that the softening of the material of the closure element leads to a firm connection with and possibly to an adaptation of the shape to the wall of the discharge vessel opening. The term melting does not necessarily mean a transition to a liquid phase in the literal sense of the word. Rather, sufficient softening is also included, which on the one hand leads to sufficient adhesion of the softened material to the vessel wall immediately adjacent to the discharge vessel opening and, if necessary, to an adaptation of the shape thereof. Typically, a viscosity of the closure element of the order of 10 ⁶ dPa s (decipascal seconds) or less is aimed for when melting.

In order not to impair the lamp itself, that is to say in particular the discharge vessel possibly made of several parts, the electrodes, possibly functional layers such as dielectric barriers, phosphors, etc., when the closure element is being melted, the material of the closure element is selected such that its Softening temperature below that of remaining materials used, especially for the discharge vessel. In particular, the softening temperature of the closure element is relatively low, so that typical melting temperatures are in the range between approximately 350 ° C. and 600 ° C., for example 400 ° C. On the one hand, the outgassing from the materials of the discharge vessel that occurs at higher temperatures can thereby be prevented or at least kept relatively low. Furthermore, the thermal load on the discharge vessel becomes relatively low, as a result of which mechanical damage due to tension or thermal changes in the material can be almost avoided. The viscosity of the closure element is typically at least, two better at least three powers of ten less than that of the discharge vessel, with a significantly higher softening temperature, in the example 520 ° C.

The or each closure element is a prefabricated semi-finished product, e.g. a molded part made of sintered glass, for example lead borosilicate (Pb-Si-BO), bismuth borosilicate (Bi-Si-BO), zinc borosilicate (Zn-Si-BO), zinc bismuth borosilicate glass (Zn -Bi-Si-BO) or phosphate glass (SnO-ZnO-P ₂ 0 ₅ ). The discharge vessel, on the other hand, consists of a glass customary for this purpose, such as soda lime silicate glass.

Such an opening, which according to the invention is closed by melting a closure element, can be a filling opening for pumping out and filling, which must be closed after filling. In this case, the closure element can have the shape of a plug, for example, which is inserted into the filling opening after filling and then melted and then closes the filling opening in a gas-tight manner. A sleeve with a thickened edge, ie a type of collar with a bore, which serves here as the actual filling opening, is also suitable as the closure element. This variant has the advantage that the closure element already before Filling can be used in the opening of the discharge vessel. After filling, the closure element only has to be melted and the opening thus closed in a gas-tight manner.

In addition, however, it can also be an opening through which, for example, an electrical feedthrough is placed and which is to be sealed, the feedthrough being to be melted down. In this case too, it is favorable to provide the closure element to be melted as a thickened edge of the opening. Then, when the glass softens, it can evenly close the opening from all sides of the opening. If the opening is a filling opening, the diameter of the opening can be 1-5 mm, for example.

As already explained at the beginning, the invention is preferably directed to flat radiator discharge vessels. These can be constructed from a base plate and a front plate and a frame connecting the two plates. A favorable arrangement of a filling opening can lie in the frame because the light radiation is particularly little impaired thereby. This also applies to electrical feedthroughs. However, arrangements in the base plate or in the ceiling plate are also possible, with clever accommodation in an edge region being preferred in order not to disturb the light radiation and the discharge electrode profile.

Tubular discharge lamps are otherwise less affected by the problem of the targeted, favorable arrangement of a filling opening, since a discharge tube initially has an opening at both ends which is suitable for filling and which has to be closed, for example by the closure elements according to the invention. The heating for melting the closure element can in any case be carried out by heat radiation, for example in an oven or by means of an IR radiator, or by a flame.

With regard to the device suitable for such process steps, the invention is also directed to carrying out the process in a vacuum oven for pumping out and filling at a controlled elevated temperature at the same time.

Description of the drawings

The invention is explained in more detail below on the basis of several exemplary embodiments, the features disclosed here also being essential to the invention individually or in combinations other than those shown. Show it:

Figure 1 is a schematic cross-sectional view through a flat radiator discharge vessel before closing according to the invention according to a first embodiment of the invention;

FIG. 2 shows a detail of FIG. 1 with the filling opening closed;

Figure 3 shows a detail with an alternative filling opening to Figure 1 before closing according to a second embodiment of the invention;

Figure 4 shows the embodiment of Figure 3 after closing;

Figure 5 is a schematic representation of a production line for the inventive method. In the two exemplary embodiments of the invention shown in FIGS. 1-5, a filling opening in a discharge vessel is closed with a glass closure element by melting. According to the first embodiment, the closure element can be arranged in one of the plates, and after the second in the frame of a flat radiator discharge vessel.

FIG. 1 shows a schematic cross section through a flat radiator discharge vessel. The number 1 designates a base plate and the number 2 a front plate and the number 3 a frame that connects the two plates. These components consist of soda-lime silicate glass and were connected to one another in a previous joining process step by means of a glass solder layer denoted by 4. The resulting discharge vessel has an essentially rectangular cross section and a rectangular plan (not shown). It is used to produce a flat spotlight with dielectrically impeded discharges for backlighting a flat screen or for general lighting. Accordingly, electrode strips are printed on the top side of the base plate 1 in the figure within the area delimited by the frame 3, part of the electrodes being covered with a dielectric layer. These details are of no further interest here and are therefore not shown. Reference is made to the disclosure content of the application 19711 890.0 already cited.

In any case, the presence of the electrode strips on the base plate 1 is the reason for the arrangement of a filling opening 5 in the front plate 2. The filling opening 5 in FIG. 1 lies essentially centrally for the sake of simplicity; in a specific embodiment, however, an edge position is preferred for reasons already explained. A glass sleeve 6 is inserted into the filling opening 5 in the form of a thickened collar as a closure element. The closure element 6 consists of a relatively low-melting sintered glass, for example lead borosilicate glass (Pb-Si-BO). In a heating phase, this closure element 6 is heated to a temperature of approximately 400 ° C., whereby it softens to a viscosity of less than 10 ⁶ dPa s, and is drawn into the filling opening 5 as a drop by the surface tension. After cooling, the filling opening 5 is closed in the manner shown schematically in FIG. 2, the relatively low heating required for softening the closure element 6 not adversely affecting the rest of the discharge vessel. It is indicated in the drawing that the closure element 6 closing the filling opening 5 produces a slight ripple compared to the rest of the front plate 2. For this reason, the above-mentioned arrangement close to the wall is preferable.

An alternative to this is shown in FIGS. 3 and 4, with FIG. 3 showing the state of a filling opening 5 ′ which is still unlocked and FIG. 4 the closed state. According to Figure 3, a filling opening 5 'is provided in a frame 3', the frame 3 'thus has a gap. A collar sleeve 6 'is inserted into the filling opening 5' in a manner similar to that shown in FIG. 1, which otherwise corresponds to the explanations given above for FIG.

After the heating phase up to the softening point of the closure element 6 ', the filling opening 5' is closed by the melted closure element 6 ', as shown in FIG. This variant offers the advantage of the smallest possible impairment of the light emission properties of the gas discharge lamp.

According to FIG. 5, the part of the manufacturing method according to the invention takes place in a schematically represented production line consisting of three stations 7, 8 and 9. As illustrated by the arrow drawn in on the left in FIG. 5, a structure composed of the base plate 1, the front plate 2, the frame 3 and the closure element 6 and provided with glass solder 4 at the appropriate points is inserted into the first station 7, a continuous furnace for joining these semi-finished products. The discharge vessel is inserted therein by heating to a temperature between 240 ° and 520 ° C. A protective gas atmosphere is present in the continuous furnace. By thorough rinsing, the contaminants emerging at the elevated temperatures, in particular binders from the glass solder 4, are expelled.

The temperature in the continuous furnace 7 is increased to such an extent that the glass solder 4 softens and the parts to be joined are joined when the joint solder has a viscosity of significantly less than 10 ⁶ dPa s. Temperatures of 520 ° C are typically required for this. The protective gas atmosphere essentially serves to prevent oxidation of the luminescent material (not shown in the figures) in the discharge vessel at the elevated temperatures. A (significantly more complex and therefore more expensive) vacuum oven is not required in station 7.

After the joining and cooling to a temperature with a viscosity of the glass solder 4 of over 10 ¹⁰ dPa s, the discharge vessel is introduced into the second station 8, the closure element 6 still corresponding to the state shown in FIGS. 1 and 3. Therefore, the interior of the discharge vessel via the filling opening 5 is still open. In the vacuum furnace 8 is therefore pumped through the filling opening 5, the discharge vessel being kept at a temperature of 250 ° -300 ° C. suitable for supporting further desorption processes and with regard to the elevated temperature suitable for the subsequent melting of the closure element 6.

Alternatively, the closure element 6 can also be applied only in the vacuum oven 8. After sufficient pumping, an atmosphere corresponding to the desired gas filling of the gas discharge lamp is set in the vacuum furnace 8 and penetrates into the discharge vessel through the filling opening 5.

Now the lamp, including the closure element 6, is heated to a temperature of approximately 400 ° C., as a result of which the latter melts and is drawn into the filling opening 5 as a drop by the surface tension. The lamp or the closure element 6 is then cooled and solidifies in the form shown in FIGS. 2 and 4 and encloses the gas filling enclosed in the discharge vessel.

The closed discharge vessel is then introduced into the third station 9, a further continuous furnace, and is cooled there to about 50 ° C. by a defined control of the furnace temperature or by transporting the lamp along a distance corresponding to a defined temperature profile within the continuous furnace 9. The finished discharge vessel can then be removed according to the arrow drawn on the right in FIG. 5. Since, as already mentioned, it is a discharge vessel which is already provided with electrode strips and bushings (compare the already cited application 197 11 890.9), the gas discharge lamp is essentially completed.

Although the invention was explained in more detail on a flat radiator, its advantageous effect is also retained in other vessel geometries, in particular in the rod-shaped discharge lamps already mentioned, for example aperture lamps for office automation and automotive technology.

In addition, as already mentioned, the closure element can only be inserted into the discharge vessel opening after the lamp has been filled and then melted. In this variant, the closing element, of course, no longer have its own filling opening but can, for example, be designed as a type of stopper, which then, after it has been melted, also closes the discharge vessel opening in a gas-tight manner.

Claims

claims

1. A gas discharge lamp with a discharge vessel, characterized in that the discharge vessel has at least one closure element (6; 6 '), and the or each closure element (6; 6') closes a discharge vessel opening (5; 5 ') in a gas-tight manner without any connecting means the or each closure element (6; 6 ') was inserted into the or a discharge vessel opening (5; 5') and then melted.

2. Gas discharge lamp according to claim 1, wherein the closure element (6; 6 ') consists of a material which melts in comparison to the rest of the discharge vessel (1-3).

3. Gas discharge lamp according to claim 2, wherein the low-melting material (6; 6 ') is a sintered glass or glass solder.

4. Gas discharge lamp according to claim 2 or 3, wherein the low-melting material (6; 6 ') consists of one or more of the following compounds: Pb-Si-BO, Bi-Si-BO, Zn-Si-BO, Zn-Bi Si-BO,

SnO-ZnO-P ₂ 0 ₅ .

5. Gas discharge lamp according to one of the preceding claims, wherein the lamp is suitable for operation by means of dielectrically hindered discharge and for this purpose has at least one dielectrically hindered electrode.

6. Gas discharge lamp according to one of the preceding claims, in which the discharge vessel is a flat radiator discharge vessel and has a base plate (1), a frame (3; 3 ') and a front plate (2), the closure element in the frame (3') or is provided in the base or front plate (2).

7. Gas discharge lamp according to one of claims 1 to 5, in which the discharge vessel is a tubular discharge vessel of a rod-shaped gas discharge lamp and one or both ends of this discharge vessel is or are closed with the aid of the or each of a closure element.

8. Gas discharge lamp according to one of the preceding claims, which has at least one dielectric barrier electrode.

9. A method for producing a gas discharge lamp with features according to one or more of the preceding claims, characterized by the following method steps for the gas-tight sealing of a discharge vessel opening (5; 5 '):

Providing a closure element (6; 6 ') as a molded part, suitable for the discharge vessel opening (5; 5'),

• Insert the closure element (6; 6 ') into the discharge vessel opening (5; 5') and melt the closure element (6; 6 ') in such a way that the discharge vessel opening (5; 5') is sealed gas-tight.

10. The method according to claim 9, wherein the closure element (6; 6 ') before melting has the shape of a sleeve with a collar and opening (5; 5'), wherein the closure element opening (5; 5 ') is closed during melting.

11. The method according to claim 9 or 10, wherein the closure element opening (5; 5 ') is a pump and / or filling opening.

12. The method according to claim 11, wherein the closure element opening (5; 5 ') has a diameter in the range of 1-5 mm.

13. The method according to any one of claims 9 to 12, wherein the closure element (6; 6 ') is heated to a temperature at which its viscosity is of the order of 10 ⁶ dPa s or less.

14. The method according to any one of claims 9 to 13, wherein the temperature of the closure element (6; 6 ') during melting is in the range between about 350 ° C and 600 ° C.

15. The method according to any one of claims 9 to 14, wherein at the melting temperature the viscosity of the closure element (6; 6 ') is at least three powers of ten less than that of the rest of the discharge vessel (1-4).