EP1074038A2

EP1074038A2 - Flat reflector lamp for dielectrically inhibited discharges with spacers

Info

Publication number: EP1074038A2
Application number: EP99945734A
Authority: EP
Inventors: Frank Vollkommer; Lothar Hitzschke
Original assignee: Patent Treuhand Gesellschaft fuer Elektrische Gluehlampen mbH
Current assignee: Osram GmbH
Priority date: 1998-04-20
Filing date: 1999-04-09
Publication date: 2001-02-07
Anticipated expiration: 2019-04-09
Also published as: CA2329085C; HUP0103677A2; CA2329085A1; US6531822B1; JP2002512425A; EP1074038B8; WO1999054916A2; DE59914995D1; TW439091B; KR100417432B1; EP1074038B1; KR20010042877A; DE19817480A1; DE19817480B4; HUP0103677A3; WO1999054916A3

Abstract

The invention relates to a flat reflector lamp for dielectrically inhibited discharges (14). Greater configuration flexibility is achieved in electrode design (11, 12) while simultaneously ensuring stability of the discharge vessel (1, 2) and preserving the possibility of minimum light reflection impairment by mounting the spacers (3) separated from the flat reflector frames (15) between the base plate (1) and the cover plate (2), the latter being arranged between the electrode strips (11, 12).

Description

Flat lamp for dielectrically disabled discharges with spacers

The present invention relates to a flat radiator lamp for dielectrically impeded discharges, which can be used in particular for backlighting display devices, in particular liquid crystal screens.

With regard to the prior art, reference is first made to the following applications by the same applicant, which form the technical basis for the following invention and whose disclosure content is included here:

DE 19636 965.7 = WO 97/01989

DE 19526211.5 = WO 97/04625 and

DE-P 4311 197.1 = WO 94/23442.

Accordingly, flat radiator lamps for dielectrically impeded discharges are known, in which the discharge vessel filled with a gas filling essentially consists of a base plate and a cover plate which are connected by a frame. The distance between the two plates is significantly smaller than their width and length.

The frame does not necessarily have to be designed as a separate component, but is defined in this invention in that it closes the discharge volume filled by the gas filling in the plane of the plates and between them to the outside. For example, the frame also be formed by a curved outer edge of one of the two plates, so that the frame forms, so to speak, the edge of a tub, the flat middle part of which is the base plate or ceiling plate.

Spacers are also known from the third publication mentioned above, which support the two plates of the discharge vessel against one another, but are motivated in this prior art by the fact that they carry or contain the electrodes of the lamp (cf. FIGS. 4a and 4b). .

The prior art also mentions EP 0 521 553 A2, which shows a flat gas discharge lamp with vacuum filling, which is protected from implosion by the stability of sufficiently thick walls of the floor and ceiling panels.

Furthermore, this document shows the possibility of buffer gas fillings for generating an atmospheric pressure of the gas fill, as is also the publication "A Fiat Fluorescent Lamp With Xe Dielectric Barrier Discharge" by T. Urakabe, S. Harada, T. Saikatsu and M. Karino (Special Issue "The Seventh International Symposium on the Science & Technology of Light Sources", J. Light & Vis. Env., Volume 20, No. 2, 1996, pages 20-25).

Spacers in the form of ribs running through almost the entire width of the flat radiator between the plates, which define an overall meandering discharge channel for a conventional mercury discharge by alternating cutouts to a frame of the discharge vessel, are shown in "Fiat Lamp Technology for LCDs" by R. Hicks and W. Halstead, SPIE, Volume 2219, Cockpit Displays (1994) The exact cross-section and length dimensions of the discharge channel defined by these spacers are essential for the so-called wall-stabilized mercury discharge. Comparable examples from the commercial prior art are shown in data sheets by the manufacturer Thomas Electronics, Inc. (100 Riverview Drive, Wayne, New Jersey 07470) "Fiat Fluorescent Lamps for LCD Backlighting".

Finally, an electrode arrangement is known from the second document cited at the beginning, in which the anodes and cathodes are formed in strips and alternate with one another in parallel, that is to say they are arranged offset on the base plate.

This invention is based on the technical problem of improving a flat lamp of the type described at the outset with regard to stability and light radiation properties.

In a somewhat more general formulation than at the beginning, the solution according to the invention to this problem as a generic term is therefore based on a flat radiator lamp for dielectrically disabled discharges with a discharge vessel filled with a gas filling, which has an essentially flat base plate, an essentially flat and at least partially transparent ceiling plate, one of which Has plate connecting frame and at least one spacer supporting the two plates against each other, and with at least partially strip-like anodes and cathodes arranged in a projection on a plate plane essentially parallel to one another, a dielectric layer being arranged between the anodes and the gas filling.

Here, offset in parallel means that there is essentially an adjacent, essentially parallel cathode strip piece for each anode strip piece and vice versa.

The invention solves this technical problem in that the spacer is completely separated from the frame by a space and at least with its contact surfaces with the plates - or else entirely - is arranged in the projection between the electrode strips.

Accordingly, the invention proceeds from the conventional concept of spacers which are connected as ribs on at least one side to the frame of the discharge vessel. Rather, it has been recognized according to the invention that a sufficient stabilizing effect of the spacers is also possible if the spacers are only connected to the plates, but not directly to the frame. The main loads occur perpendicular to the planes of the plates, so that an elongated shape of the spacers and anchoring of the spacers to the frame is not necessary.

Furthermore, when a spacer is connected to the frame, there is also the problem that darkening due to the absorption in the frame and the spacer and due to the radiation contribution from the corresponding part of the discharge vessel accumulate at the point of contact. The darkening problem of a spacer or the frame can be countered with suitable measures. For this, reference is made to the parallel application “fluorescent lamp with spacers and locally thinned fluorescent layer thickness”, the disclosure content of which solutions are included here. However, if spacers and frames meet at the point of contact, compensation of the darkening becomes very difficult. This aspect plays a special role Role in the preferred field of application of this invention, namely flat radiator lamps for the backlighting of flat display devices, in particular liquid crystal screens.

Another advantage of the invention is the good gas flow dynamics within the discharge vessel when pumping out during manufacture. position process. For cleaning and filling a lamp according to the invention, instead of the conventional vacuum furnace method, which is not shown here, pump stem solutions can also be used, in which the discharge vessel is pumped out via the pump stem with a vacuum pump with simultaneous (possibly large progressing in the case of large lamps) heating and then via the pump stem is filled. The main disadvantage of the vacuum furnace solution is, in particular, the considerable outlay in the case of large-format lamps, which are of particular technical interest in connection with larger display devices and can also be produced relatively easily with the technology used here for flat lamp lamps with dielectrically impeded discharge.

Furthermore, the spacers according to the invention have the advantage that “local solutions” for spacers that can be coordinated with the geometric design of the electrode structure can be found by the task of the continuous rib geometry with connection to the frame. In particular in connection with the optimization of the uniformity of the light radiation In view of the fields of application mentioned, it is necessary to have the greatest possible scope when designing the electrode geometry.

According to the invention, it has now surprisingly been found that the electrode geometry, depending on the geometric extent of the desired spacers, can be designed with little or practically no consideration of the local positions of the spacer or spacers. In addition, there has been an expectation that an arrangement of spacers in positions with a strong field between the electrodes is unproblematic. In particular, the entire level of the discharge vessel (in the projection) can be filled and partially Find symmetrical electrode geometries. The spacers can also be largely freely positioned according to mechanical criteria without having to strongly adapt the electrode structure.

Regarding the details of the geometrical design of the electrode structures and the coordination with the discharge vessel geometry, reference is made to the relevant disclosure content of the following parallel applications by the same applicant:

"Flat fluorescent lamp for the backlight and liquid crystal display device with this flat fluorescent lamp" (file number PCT / DE98 / 00827),

"Flat radiator" (file number 19711 892.5),

"Gas discharge lamp with dielectrically disabled electrodes" (file number PCT / DE98 / 00826), which is included here.

As can be seen in the DE-P 43 11 197.1 already cited at the outset, the inventors initially assumed that the arrangement of spacers made it necessary to adapt the electrode configuration to the spacer geometry. Accordingly, was also in the case of electrode arrangements on or in the plates, for. B. in DE 195 26 211.5, expects that when spacers are inserted, large gaps between the individual subareas of the electrode configuration must be left free in order not to disturb the field distribution and undisturbed formation of the desired dielectric barrier discharges (see FIG. 6a) cited application).

It is known that the dielectric impedance of the discharges on the dielectric layers complicates and changes over time

Space charge systems are created. Together with the created utilities Potentials lead to complex, time-varying field strength arrangements, even in areas that at first glance might appear to be field-free. At first, considerable interfering interactions of spacers with these time-changing electric fields were expected.

In particular, it could be assumed that an arrangement of spacers in non-field-free spaces or directly between electrode strips leads to significant inhomogeneities or contracted discharge channels through effective shortening of the discharge lengths, ie through a capacitive “short circuit” due to the displacement current in the generally dielectric Material of the spacer leads.

The problem was also expected that the areas of spacers, which are not insignificant in comparison to the electrode strips, by capacitive coupling to electrode potentials could lead to considerable effective enlargements of the area of certain electrodes and could, as it were, cause discharges.

The surprising finding on which this invention is based is that, when the dielectric discharges are formed by the electrical operating mode described in detail in DE-P 43 11 197.1 (again included here), a "reminder function" of the typical partial discharge structures that arise arises, so to speak This reminder function has not only a temporal but also a local component. This means that the pulses of the active power coupling separated by dead times lead to re-ignition processes of individual partial discharges at preferably the same places, presumably because, in the sense of a temporal reminder function, a remaining restionization distinguishes these points from neighboring ones. However, in contrast to conventional gas discharges, the partial discharges surprisingly lead to a physical “life of their own” that is largely decoupled and that can hardly be disturbed by adding spacers in the immediate vicinity.

Just as the term “frame” is functionally defined in the context of this invention, this also applies to the term “spacer”. Specifically, this means that the spacer does not necessarily have to form a component that is separate from the base plate (or ceiling plate). Rather, e.g. For example, a base plate can also be produced as a spacer by means of flat recesses with projections remaining in these recess surfaces. In particular, the discharge vessel of a flat lamp according to the invention can also be constructed from essentially two main components, namely a base plate, in which the frame and spacers are already formed in one piece, and a ceiling plate. This can be achieved by deep drawing or pressing, sandblasting and other methods.

One embodiment of the invention now uses electrode structures which determine the local distribution of the partial discharges beyond the determination by the geometry of the electrode strips. Such structures are disclosed, inter alia, in the previously cited DE 196 36 965.7, to which reference is made in this regard. Possible u. a. Protrusions on the cathodes, layer thickness variations of the dielectric, changes in the width of the electrodes, etc.

Such distributions of the electrode structures and thus of the partial discharges are preferred, which form an alternating row on both sides of a cathode strip. It should first be noted that the terms “cathode” and “anode” used in this application are to be understood functionally. This means that with bipolar operation, an invented According to the lamp according to the invention, the electrodes alternately perform the anode and cathode functions and therefore the statements made in this application for anodes or cathodes must apply to all electrodes in such cases. If, in the case of an alternating row of partial discharges, one or more spacers are to be placed, then practically all arrangements between the partial discharges are possible according to the invention in which there is no direct overlap between the spacer and a partial discharge. According to the invention, however, it has been found to be particularly advantageous to arrange the spacers at the level of a partial discharge, viewed in the direction of the strip, but on the other side.

In the unipolar case, it should also be noted that the partial discharges have a direction with respect to their compatibility with an adjacent spacer, which runs from the cathode to the anode. This means that a spacer arranged in the "back" in the sense of this direction of the partial discharges can be brought particularly close to the partial discharge without being disruptive.

In principle, however, other arrangements of the spacers are also suitable, for example between the partial discharges, but not in the center, but rather between the already mentioned height of the partial discharge on the opposite side and an adjacent partial discharge on the side of the spacer. Finally, arrangements are also possible at locations that do not lie in a strip containing partial discharges between electrodes, but rather, for example, between two individual anodes of a double “double anode” (see applications “flat radiators” and “gas discharge lamp with dielectrically impeded electrodes”) reference is made to the description of the exemplary embodiments. In connection with the gaps provided according to the invention between the spacers and the frame of the flat radiator discharge vessel, the stabilizing effect of the spacers can be optimized in that they divide the lateral dimensions of the discharge vessel essentially into equal sections. Specifically, this means that if a spacer is used, this is arranged approximately in the middle of the surface of the flat radiator, two spacers which divide the corresponding greater length of the flat radiator into thirds, etc., and analogously for two-dimensional spacer arrangements.

The gaps formed between the spacers should have a certain size in the sense of the invention, in particular the gaps to the frame. It is preferred that the gaps are more than simple, better more than twice the distance between the ceiling and floor slabs from each other.

Similarly, another size important for the invention can be scaled based on the plate spacing. At the beginning, the one of the two panels forming the light exit side was already referred to as the ceiling panel. In order to reduce the optical impairment of the light radiation via this ceiling plate, another idea of the invention is to make the contact surface between the spacer and the wall considered here as small as possible. This is countered by mechanical considerations, namely the avoidance of a punctiform load on the wall (generally made of glass) by the spacer. However, this disadvantage is accepted in favor of minimizing the area which has been darkened or which can be brightened up by reducing the layer thickness. It is preferred to restrict this contact surface two-dimensionally, ie to extend it less in every direction conceivable in this plane. On the other hand, there are cases, especially linear running spacers, in which a restriction of the contact surface in only one direction (perpendicular to the spacer line) is advantageous.

Expressed more specifically, this means that spacers with more or less "punctiform" contact surfaces on the ceiling plate can be limited in all directions by restricting this contact surface. However, according to the invention, this is not absolutely necessary. B. occur by cylindrical or prismatic spacers which are then made sufficiently narrow in at least one direction.

A quantitative characterization of this limitation of the contact surface refers to the distance bridged by the spacer of the discharge vessel. B. on the plate spacing of a flat lamp fluorescent lamp. Here, the described small expansion of the contact surface should be less than 30%, preferably less than 20% or 10% of this distance.

Another important embodiment of the invention relates to the stability of the discharge vessel with the spacers in the case of thermal cycles, as they occur inevitably in lamp operation. In the elaboration of the invention, it has been found to be essential to match the thermal expansion coefficient of the various main components of the discharge vessel and the spacers. In particular, the thermal expansion coefficient of the spacers should be in the range of ± 30% of the expansion coefficient of the main components of the discharge vessel. The main components of the discharge vessel are those components whose thermal expansion is essential for the thermal expansion of the overall discharge vessel due to their geometric dimensions and their function in the discharge vessel. In the case of a flat radiator, these are e.g. B. the two plates and the frame connecting them. Mismatches in this area, depending on the extent of the thermal loads during operation, lead to internal tension and displacements of the vessel components and the spacers with one another and thus to instabilities and loosening of connections or even breakage of the lamp.

Soft glasses have proven to be cheap materials for the spacers. Such soft glasses can also be used in a form further processed in terms of materials, e.g. B. as a flour or glass solder held together by a binding material. Finally, various ceramic materials come into question, in particular Al 0 ₃ ceramic. With regard to the question of the choice of material and the coefficient of expansion, reference is made to the parallel application already cited "fluorescent lamp with spacers and locally thinned phosphor layer thickness".

With regard to the minimization of the contact surface of the spacer on the transparent surface of the wall, it has been found that a fixed connection between the spacer and the wall is not necessarily advantageous. Rather, it can be advantageous to attach the spacer only to the other side, that is to say to the opposite wall, with which it is fixed during the overall assembly. By means of a suitable geometric design, the wall with the transparent surface then merely rests on the spacer, no further connecting materials such as glass solders, adhesives or the like being provided. This allows the contact area to be reduced to a minimum.

Furthermore, this also offers a gain in terms of any thermal expansion differences between the two walls connected by the spacer. In the event of transverse displacements which arise as a result, the wall which is only in contact can slip against the spacer before excessive stresses occur. A further possibility for reducing the optical disturbances due to an image of the spacer consists in sheathing it with a phosphor layer. As a result, the spacer on the other side of the transparent wall does not appear more or less pronounced as shading, apart from the immediate area of the system between the spacer and the wall. There is too little ultraviolet light to stimulate the phosphor to a significant extent.

Since the fluorescent coating of the spacer increases the contact area on the wall, it should be made clear that the lighting of this fluorescent layer means that the area of contact of the fluorescent layer on the wall does not appear as a shadow to the extent that there is sufficient ultraviolet light for excitation, to an extent comparable to the uncoated spacer is available. Accordingly, the effective contact surface to be assessed in the sense of the above explanations for minimizing the contact surface is that of the spacer without the phosphor layer (or only with areas of the phosphor layer that are not sufficiently excited).

According to the invention, a further possibility for brightening the surroundings of the spacer consists in a reflective coating of an area of the spacer facing the transparent wall. This increases the coupling of the light diffusely distributed within the discharge vessel into the region of the phosphor layer on the wall which is thinned according to the invention.

So far there has been talk of stabilization in connection with the function of the spacers. However, a differentiation is possible here: Due to their geometry, flat radiator lamps are mechanically endangered from two main directions. On the one hand, flat, extended discharge vessels are at risk of breakage due to bending stress. This is a consequence of the leverage that occurs. Even here, the invention offers a significant improvement in that the corresponding stabilization of the discharge vessel can be achieved without significant restrictions for the arrangement of the electrodes and the uniformity of the light radiation.

Another aspect is the implosion of flat lamp lamps with a vacuum gas filling. Since, according to the invention, a stable discharge vessel can now also be produced with respect to the risk of implosion without being too severely restricted elsewhere in the design of the lamp (see above), vacuum gas fillings are to be regarded as the preferred case of the invention. They avoid the need for buffer gas additives to produce an internal pressure in the discharge vessel which is adapted to the external atmospheric pressure. This avoids possible technical disadvantages of the buffer gas additives and creates an adequate technical alternative.

A final essential aspect of the invention is the surprising high voltage suitability of the electrode structures despite the spacers arranged nearby. High-voltage suitability with regard to the amplitudes of a pulsed electrical supply, for example, can be of interest in view of an increase in the yield of the lamp. This applies in particular to the application for backlighting liquid crystal displays which absorb a large part of the light output of the lamp.

It has been found in the work on this invention that short distances between the electrodes necessary at lower voltage amplitudes deteriorate this yield. The same applies to an excessive reduction in the pressure of the gas filling. Finally, especially in the pulsed operating mode for the active power inputs, Coupling only available for a short time, so that relatively high voltages are necessary in order to achieve an adequately high lamp power on average.

In this sense, the invention is preferably directed to flat radiator lamps designed for supply voltage amplitudes of at least 600 V, particularly preferably 800 V or 1000 V or 1200 V.

To clarify the invention, exemplary embodiments of the invention are described in more detail with reference to the figures. Details disclosed here can also be essential to the invention in other combinations.

In detail shows:

Figure 1 is a sectional view that forms a cross section in a plane perpendicular to the levels of a floor slab and a ceiling slab by a spacer between the floor and ceiling slab;

FIG. 2 shows three different variants of the arrangement of such a spacer in a typical electrode structure of a flat radiator lamp;

Figure 3 shows an exemplary arrangement of a pattern of spacers according to one of the variants shown in Figure 2;

Figure 4 is an arrangement comparable to Figure 3, but for another application.

Figure 1 illustrates a typical example of a spacer according to the invention in a detail and cross-sectional view. There is a precision glass ball 3 made of soft glass with a diameter of 5 mm between a base plate 1 and a ceiling plate 2 of a flat lamp. In addition to soft glass, there are also other dielectric materials, e.g. B. ceramics or other glasses in question, as well as materials based on glass powder or ceramic powder and additionally contain a binder or the like, for. B. glass solder. An important aspect in addition to the dielectric properties, however, are the thermal expansion coefficients already discussed elsewhere.

The glass ball 3 is coated with a phosphor layer 4, which is also on the base plate 1 and on the ceiling plate 2.

The glass ball 3 is soldered to the base plate 1 via a glass solder in the area 5 in order to fix it during assembly. It is only on the ceiling plate 2. Around this contact surface 6, the phosphor layer 4 of the ceiling panel 2 is wiped out in a certain area 7.

On the outside of the ceiling panel 2, which consists of transparent special glass B270 from the manufacturer DESAG, a thin frosted glass overlay 8 is formed, on which a prism film 9 rests (Brightess Enhancement film from the manufacturer 3M).

Under the fluorescent layer 4 on the base plate there is also a reflective layer 10. For further details, reference is made to the already cited application “fluorescent lamp with spacers and locally thinned fluorescent layer thickness”, in which there is an analog figure.

FIG. 2 now illustrates three different variants of the arrangement of such a spacer 3, represented by the letters A, B and C, in a typical electrode configuration of a flat radiator lamp, to which reference is further made to the application “gas discharge lamp with dielectrically disabled electrodes”. The electrodes shown in FIG. 2 correspond to a projection onto a plate plane. 2 therefore does not initially determine whether the anodes 11 and the cathodes 12 are deposited on or in the same plate or on or in different plates.

The former case is to be preferred from the perspective of a simplification of the manufacturing process and is shown, for example, in FIG. 6a of DE 195 26 211.5 already cited. The second case has certain advantages, for which reference is made to FIG. 9b of the likewise already cited application “gas discharge lamp with dielectrically impeded electrodes”. If FIG. 2 of the present application is viewed not as a top view but as a projection, it applies to both Cases.

Furthermore, in FIG. 2, in the right and in the left half of the illustration, two electrode configurations are shown which are different insofar as the distance between the nose-like projections 13 on the cathodes 12 (cf. DE 196 36 965.7) is quadrupled. The delta-shaped partial discharges are denoted by 14.

First, A denotes a possibility in which the glass ball 3 lies in the projection onto a plate level between the individual anodes of a twin anode arrangement 11. For the reasons already mentioned of the complicated and time-varying space charge distributions on the dielectric layers, at least on the anodes, this area is by no means really field-free. Rather, the discharges between the cathodes 12 assigned to the respective individual anodes and these individual anodes are never really symmetrical. However, in comparison to the positions B and C between the electrodes of different polarity, which are shown below, the least difficulties could still be expected here. In fact, this position A is also a possible position and the glass ball 3 can essentially be positioned as desired in the vertical direction of the figure 2 indicated by the arrows.

Surprisingly, however, the second option B shown results as a preferred variant in the context of this invention, in which the glass ball 3 lies to a certain extent in the back of a nose-like projection 13 between a cathode 12 and a single anode of the twin anode 11.

For relatively large distances between the nose-like projections 13, as shown in the left half of FIG. 2, there is also a position C different from position B. This position could appear to be less problematic than B, since the glass ball 3 of the partial discharge 14 on the immediately adjacent nose-like projection 13 comes relatively close to the other side of the cathode 12. This does not apply to position C. However, it has been found that the “sensitivity” of the partial discharges 14 is not isotropic with regard to the close proximity of a spacer 3 in the two-dimensional drawing plane. Rather, it turns out that the partial discharge 14 is to a certain extent from the projection 13 "looks" at the adjacent anode. Specifically, this means that with particularly narrow distances between the electrode strips 11 and 12 and with an arrangement of the spacers 3 sufficient for a position C in principle, the distance B of the partial discharges 14 is found to be more favorable.

Basically, all positions shown here and also other less symmetrical positions are possible according to the invention. It must essentially be avoided that the spacers 3 form no overlap with the immediate discharge region of each partial discharge 14, which is a visible delta. The sensitivity that occurs with regard to an approach between the spacers 3 and partial discharges 14 is also dependent on the voltage used. power supply amplitudes. If, in certain exceptional situations, the individual discharges cannot be localized sufficiently by their own lighting, they can at least be found on the basis of their emission in the infrared or UV range.

FIG. 3 shows a case largely corresponding to the right half of the figure in FIG. 2, in which variant B is used for the arrangement of the spacer 3. Partial discharges 14 are no longer shown here, but a complete arrangement of a larger number of 49 glass spheres 3, which in a largely uniform distribution form a pattern over essentially the entire area of a discharge vessel (not shown). The distances between the outer glass ball 3 and the edges of the discharge vessel essentially correspond to the distances between the balls, so that overall the width and length of the rectangular discharge vessel are subdivided into uniform subunits.

A frame 15 of the discharge vessel is also indicated here. It can be seen that the spacers 3 are separated from each other and from the frame by more than twice their diameter and thus the plate spacing.

In this case, a relatively large number of spacers have been used because the electrode arrangement in FIG. 3 is designed for a flat radiator lamp for the backlighting of a liquid crystal screen. Weight considerations play an important role, so that the ceiling plate 2 and the base plate 1 must be designed relatively thin.

A different exemplary embodiment is outlined in FIG. 4. Here, the distances between the spacers 3 are set further in the case of a locally comparable electrode structure. Here is an electrical shown the structure for a flat radiator signal lamp, which is part of a traffic light. In this application, the weight of the flat lamp is less important than in the previous one. For the rest, the glass plates of the flat radiator lamp have to be designed more strictly than in the case of a screen in order to protect against environmental influences, impacts and the like. For this reason, stabilization by spacers 3 is not necessary to the extent as in the previous embodiment. For this application, reference is also made to the European application "signal lamp and fluorescent materials therefor" with the file number 97122800.2 from the same applicant.

The electrode structure is characterized by a round, enveloping overall shape. The frame 15 of the discharge vessel runs in a circle between the bus-like electrode guides on the right and left in FIG. 4 and the immediate discharge region which can be recognized by the nose-like projections 13. The area within this frame is again subdivided by the arrangement of the spacers 3 into essentially equal distances.

Claims

claims

1. Flat lamp for dielectrically disabled discharges (14) with a discharge vessel filled with a gas filling, which has an essentially flat base plate (1), an essentially flat and at least partially transparent ceiling plate (2), a frame (15 ) and at least one spacer (3) supporting the two plates (1, 2) against one another, and with at least partially strip-like anodes (11) and cathodes (12) arranged parallel to one another in a projection on a plate plane, between the Anode and the gas filling a dielectric layer is arranged,

characterized in that the spacer (3) is completely separated from the frame (15) by an intermediate space and is arranged at least with its contact surfaces with the plates (1, 2) in the projection between the electrode strips (11, 12).

2. Flat lamp according to claim 1 with electrode structures (13) for local fixing of partial discharges (14), in which the spacer (3) is arranged between the locations of fixed partial discharges.

3. Flat lamp according to claim 2, in which the electrode structures (11, 12) define the partial discharges (14) in alternating rows on both sides of a cathode strip and the spacer (3) at least with the contact surfaces in the projection between the locations of two the same side of adjacent partial discharges and viewed in the direction of the strip is arranged approximately at the level of a partial discharge on the opposite side of this strip.

4. Flat radiator lamp according to one of the preceding claims, in which the spacer or spacers (3) divide the lateral dimensions of the discharge vessel into substantially equal sections.

5. Flat radiator lamp according to one of the preceding claims, wherein the space is larger than the distance between the plates (1, 2).

6. Flat lamp according to one of the preceding claims, wherein the contact surface between the spacer (3) and the ceiling plate (2) in at least one direction in the area is narrower than 30% of the distance between the plates (1, 2).

7. Flat lamp according to claim 6, wherein the contact surface between the spacer (3) and the ceiling plate (1, 2) in all directions in the area is narrower than 30% of the distance of the plates.

8. Fluorescent lamp according to one of the preceding claims, in which the spacer (3) has a thermal expansion coefficient which corresponds to that of the main components (1, 2, 15) of the discharge vessel with a tolerance of + 30%.

9. Fluorescent lamp according to one of the preceding claims, wherein the spacer (3) consists essentially of soft glass, a substantially soft glass-containing material or a ceramic material.

10. Fluorescent lamp according to one of the preceding claims, in which the spacer (3) rests without connecting material on the ceiling plate (2).

11. Fluorescent lamp according to one of the preceding claims, wherein the spacer (3) has an outer fluorescent coating (4).

12. Fluorescent lamp according to one of the preceding claims, wherein the spacer has a reflective coating in a region facing the ceiling plate.

13. Flat lamp according to one of the preceding claims, in which the gas filling has negative pressure.

14. Flat lamp according to one of the preceding claims designed for supply voltage amplitudes of at least 600 V.