EP1080483B1 - Flat discharge lamp and method for the production thereof - Google Patents

Description

Technical field

The invention is based on a flat discharge lamp according to the The preamble of claim 1. The invention also relates to a method according to the preamble of the process claim for the production of this Discharge lamp.

The term "discharge lamp" includes sources of electromagnetic Radiation based on gas discharges. The spectrum of radiation can both the visible area and the UV (ultraviolet) / VUV (vacuum ultraviolet) range and the IR (infrared) range include. A phosphor layer can also be used for conversion be provided invisible in visible radiation.

These are in particular also flat discharge lamps so-called dielectric barrier electrodes. The are dielectric handicapped electrodes typically in the form of thin metallic strips realized on the outer and / or inner wall of the discharge vessel are arranged. If all electrodes are located on the inner wall, at least some of the electrodes must face the inside of the discharge vessel be completely covered with a dielectric layer. Discharge lamps of this type are known for example from EP 0 363 832 (Fig. 3) and the German patent application P 197 11 892.5 (FIGS. 3a, 3b) are known.

Flat discharge lamps - also known as flat spotlights - show Discharge vessel, which consists of a floor and ceiling plate, e.g. of glass, which are connected to each other via a frame.

A frame can be dispensed with if the floor and / or Ceiling part is not flat but is shaped so that only when assembled a discharge vessel is already formed in the base and ceiling part. For example the base and / or ceiling part can be shaped like a tub, e.g. by deep drawing. In the case of very large flat lamps, this is also the case At least the majority of the shaped floor or ceiling part approximately plan and therefore needs a stabilization or several support points.

In the following, therefore, under the terms floor and ceiling slab also structures are understood, which may not be complete but are at least predominantly (approximately) plan.

The discharge vessel contains a gas filling of a defined composition and filling pressure and must therefore be evacuated before filling. consequently the discharge vessel must have both negative pressure - namely during the Manufacture of the lamp - as well as the subsequent filling pressure, which is less than Atmospheric pressure, for example between 10 kPa and 20 kPa, withstand permanently. This fatigue strength is according to information from glass manufacturers with a value of about 8 MPa and results depending on from the glass thickness used, from the maximum deflection over a distance between two supports. The latter is reversed proportional to the glass thickness used and also depends on a certain one Temperature from the pressure difference between the inside of the Discharge vessel and outside.

Consequently, the fatigue strength can be given for a given pressure difference and temperature, even with thin glasses, by shortening the distance between two camps. For this you use support points over the base of the discharge vessel in a sufficient position and Number can be arranged. The mutual nearest neighbor distance of the Bases are dimensioned so that the desired route length at none Place is exceeded.

State of the art

The support points usually consist of a glass rod section, glass ring, Glass tube or a glass ball, its height or its diameter correspond to the frame height. So far, the support points were replaced by a suitable one Sintered glass glued to the floor and / or ceiling plate. The glue only fixes the support points, but is too thin to accommodate height differences to be able to compensate. Support points made up of two different components Viscosity exist and for Compensation of height differences between ground and ceiling plate of a plasma display are used are from JP-A-08/185802 known.

Integrated glass webs are also known. There is a possibility to process a solid material by sandblasting so that the base plate in appropriate thickness, as well as the glass webs in the desired shape and height arise. In this case, too, the cover glass is bonded and glass web by gluing with a sintered glass.

Another possibility is the integration of the webs through heat treatment the glass, such as B. deep drawing using negative pressure or dead weight or presses. Here, the floor or ceiling plate is over your Softening point heated and using a mold according to standard procedures shaped.

Presentation of the invention

It is an object of the present invention an improved manufacturing process of flat discharge lamps.

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

A prerequisite for the stabilization considerations mentioned at the beginning of the discharge vessel by means of support points is that at all support points sufficient, bilateral contact to the floor and ceiling slab guaranteed is. If a support point has no contact on both sides, it falls as an effective support. As a result, the free distance in the area doubles this ineffective support point, radially from this and in the plane looking at the plates. This may be the target Line length exceeded and the fatigue strength reduced inadmissibly. For this reason, unevenness in the floor and ceiling slab must the footprint of the discharge space and height tolerances of the frame be taken into account and balanced. This prepares in particular increased with increasing number of support points and increasing area Trouble.

The invention proposes support points, each consisting of two components. These two components are distinguished by the fact that they have distinctly different viscosities when the vessel is joined, that is to say at the joining temperature. Here, a component works as a so-called "hard part" and has a very high viscosity, typically more than 10 ⁹ dPa s, preferably 10 ¹¹ dPa s and more at the joining temperature. A soda lime glass, for example, is suitable. The other component works as a so-called "soft part", with a low viscosity which is matched to the joining temperature in the range from typically 10 ⁸ dPa s to approx. 10 ⁵ dPa s or less, ie at the joining temperature, possibly with little application of force, given a defined and non-destructive deformation. Sintered glass or lead glass, for example, is suitable.

For the "hard" part there are basically almost any shapes conceivable, in particular also rod sections, pipe sections, pipes, balls, Rings, rods, etc. In principle, almost also are suitable for the "soft" part any shapes, e.g. B. rings, cylinder pieces, truncated cones, plates or channels. However, the shapes of both components are in any case suitable to coordinate with each other. The viscosities of such sintered glass parts are achieved through coordinated mixing ratios of different sintered glasses, according to standard procedures, such as B. pressing, casting, extruding and subsequent Sintered. It is possible to use these sintered parts immediately in the desired dimensions or through to produce a mechanical processing prior to sintering. In addition, the two components can also be used from the outset be connected to a one-piece support point.

The function of a two-component support point in the manufacture of a flat discharge lamp is that its height before the lamp is deliberately exceeded the height of the frame, for example a range from a tenth of a millimeter to a few millimeters, in particular between approximately 0.5 mm and 2 mm , As a result, the ceiling tile only rests on the support points before the joining process. When the joining temperature is reached, the "soft" part of the support points becomes low-viscosity enough, typically in the order of 10 ⁷ dPa s, to deform under the weight of the ceiling tile. The ceiling plate sinks onto the frame pasted with solder, for example glass solder, and fuses with it. In this way the lamp is sealed.

The great advantage of this approach is the following. Because the ceiling tile always lies on all support points during this process, levels itself each support point itself to the required height, i.e. exactly so that each Support point has contact on both sides with the floor or ceiling plate.

This property also enables the two-component support point, the Lamp pumpless in a vacuum oven filled with filling gas under filling pressure to manufacture, since the lamp when the joining temperature is reached closes independently.

In extreme cases, the support points can also for the most part each consist of a low-viscosity component and a high-viscosity one Separating layer as a second component, which sinters on the low-viscosity Prevents component to the floor or ceiling plate. As Release agent can also serve as a fluorescent material.

Description of the drawings

Figur 1a

einen Teilschnitt durch eine flache Entladungslampe vor dem hermetischen Verschließen des Entladungsgefäßes,

Figur 1b

einen Teilschnitt durch eine fertige flache Entladungslampe,

Figur 2

einen Teilschnitt durch eine weitere flache Entladungslampe zur Erläuterung der Höhenausgleichswirkung der zweikomponentigen Stützstellen.

The invention will be explained in more detail below with the aid of several exemplary embodiments. Show it:

Figure 1a

a partial section through a flat discharge lamp before the hermetic sealing of the discharge vessel,

Figure 1b

a partial section through a finished flat discharge lamp,

Figure 2

a partial section through a further flat discharge lamp to explain the height compensation effect of the two-component support points.

Figures 1a and 1b each show a schematic partial section through a flat discharge lamp 1 before hermetically sealing the discharge vessel 2 or in the finished state.

First, the electrodes are usually on the bottom and / or Ceiling tile applied, e.g. by means of printing technology, possibly in addition dielectric layers, phosphor layers, etc., for clarity because of but is not shown. Otherwise, the expert the process steps for realizing these features are familiar.

In a next step, a peripheral frame 3 is made using glass solder 4 applied to the base plate 5. The height of the frame 3 above the inner wall the base plate 5 is approximately 5 mm. Likewise, on the ceiling tile 6 applied a circumferential glass solder path 4. Frame, floor and Ceiling plate are made of soda lime glass. The glass solder 4 serves when later joining the individual parts to merge and Sealing base plate 5 and ceiling plate 6 with the frame 3.

Then circular cylinder pieces 7 made of alkali blue glass (40% by weight PbO content) upright at the desired mutual distance on the base plate 5 arranged. Then a glass ball is placed on each circular cylinder piece 7 8 made of soda lime glass. The circular cylinder pieces 7 have following dimensions: height = 1.8 mm, outer diameter = 4 mm and Inner diameter = 2.8 mm. The diameter of the glass balls 8 is approx. 5 mm. As a result, the respective overall height of the two-part is before the joining process Support points 7, 8 above the base plate 5 larger than the corresponding one Height of the frame by about 1 mm.

Now the ceiling plate 6 is placed on the balls 8 and the entire arrangement from base plate 5, frame 3 with glass solder 4, two-part support points 7, 8 and ceiling plate 6 in an evacuable oven (not shown).

Then the oven is at a temperature of about 350 ° C for about 30 minutes evacuated to largely remove impurities. Because at the temperature of approx. 350 ° C the circular cylinder pieces 7 are not yet sufficiently low-viscosity are, the ceiling panel 6 and the frame 3 during this Vertical step not yet merged.

After the baking and evacuation have been completed, the furnace and, since that Discharge vessel 2 is still open, consequently also the interior between the floor 5- and ceiling plate 6 filled with filling gas, here xenon.

The temperature in the oven is then increased to approx. 520 ° C. The circular cylinder pieces 7 are so far viscous, on the order of approximately 10 ⁶ dPas, that the ceiling plate 6 sinks onto the frame 3. The glass solder 4 is also low-viscosity, in the order of approximately 10 ⁵ dPa s, that it joins the base plate 5 and the cover plate 6 with the frame 3 to form a gas-tight discharge vessel 2. During the lowering of the ceiling plate 6, the individual support points 7, 8 level to the exactly required height such that each support point 7, 8 has contact with the floor 5 or ceiling plate 6 on both sides. The viscosity of the floor and ceiling slab, frame and glass balls is more than 10 ⁹ dPa s at the joining temperature of 520 ° C.

The advantageous effect of automatic leveling of the two-component Support points 7, 8 are particularly evident in FIG schematic partial section through a flat lamp 1 'with respect to the Base plate 5 shows oblique ceiling plate 6. This skew is caused by that the left part 3a of the frame is higher than the right part 3b. to Clarification, this undesirable skew is greatly exaggerated. Similar Skewing can also occur due to locally fluctuating plate thicknesses and / or insufficient flatness of the plates or the like be caused. In Figure 2 is clearly recognizable that the heights of the circular cylinder pieces 71-73 from the right increase to the left and in this way the different distances compensate between base plate 5 and ceiling plate 6.

In one variant (not shown), the "hard" component consists of each a tube made of soda lime silicate glass and the "soft" component from one Lead glass gutter. A pipe is partially embedded in a channel and thus forms a support point that runs parallel to one side of the base plate extends one side of the frame. This variant has the advantage that these support points the plates made of pipe and gutter quasi linear instead of punctiform as above support. This can be particularly advantageous for very large lamps be, because then instead of very many balls with rings only relatively few Pipes with gutters are required.

Depending on the requirements of the lamp, additional process steps can optionally be carried out are interposed, for example to apply a Luminous and or reflective layer etc.

In addition, the lamp can also be equipped with a pump tube for evacuation or filling the finished assembled discharge vessel. In this case, an oven that can be evacuated and filled can be dispensed with become. The manufacturing process is then modified such that initially the discharge vessel is assembled in the furnace as described above and with a pump tube is provided. Then the discharge vessel Evacuated via the pump tube and simultaneously heated in the oven. After that the discharge vessel is filled with the filling gas via the pump tube and finally closed. The lamp is finished.

Claims (7)

1. Method for producing a flat discharge lamp having

   a discharge vessel,

   which discharge vessel has a cover plate and a base plate,

   support points between the cover plate and base plate,

   which support points in each case comprise two components of different viscosity, the viscosity of the first component being lower at the jointing temperature than the viscosity of the second component,

   electrodes which are arranged on the discharge vessel wall,
   and having the following method steps:

   applying a hermetically sealing means to the base plate and/or cover plate,

   arranging the two-component support points on the base plate, the dimensions of the support points perpendicular to the plane of the cover plate or base plate initially being larger than the final spacing provided between the base plate and cover plate,

   mounting the cover plate on the base plate with the aid of the support points,

   inserting the base plate with support points, sealing means and cover plate into an evacuable furnace,

   evacuating and heating the furnace, in particular for the purpose of removing gaseous impurities, the temperature inside the furnace being only so high that the first components of the support points are still sufficiently highly viscous reliably to prevent sinking of the cover plate,

   filling the furnace with the filling gas to the filling pressure provided for the lamp, and

   heating the furnace to the jointing temperature, at which the first components of the support points become of sufficiently low viscosity such that the cover plate finally sinks to the final spacing provided between the cover plate and base plate, the sealing means simultaneously at least partially attaining a sufficiently low viscosity to join the cover plate and base plate together.
2. Method according to Claim 1, in which the sealing means comprises a frame which is provided on its underside and/or top side with a glass solder, which glass solder attains at the jointing temperature a viscosity sufficiently low to ensure a connection and, after cooling, a hermetic seal between the base plate and frame, on the one hand, and between the frame and cover plate, on the other hand.
3. Method according to Claim 1 or 2, in which the first components comprise rings or pieces of a circular cylinder, and the second components comprise balls.
4. Method according to Claim 3, in which when the two-component support points are being arranged the rings or pieces of a circular cylinder are firstly arranged on the base plate, and subsequently a ball is respectively mounted on each ring or on each piece of a circular cylinder.
5. Method according to Claim 4, in which the inside diameter of the rings or pieces of a circular cylinder are smaller than the diameters of the balls in such a way that the balls are fixed in the rings or pieces of a circular cylinder.
6. Method according to one of the preceding claims, in which the second components consist of glass.
7. Method according to one of the preceding claims, in which the first components consist of sintered glass, in particular of Pb-B-Si-O and/or Bi-B-Si-O and/or Pb-Bi-(Zn)-B-Si-O, the Zn component being optional.

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