EP2147460A2

EP2147460A2 - Flat uv discharge lamp, uses and manufacture

Info

Publication number: EP2147460A2
Application number: EP08788198A
Authority: EP
Inventors: Laurent Joulaud; Guillaume Auday; Didier Duron; Jingwei Zhang
Original assignee: Saint Gobain Glass France SAS; Compagnie de Saint Gobain SA
Current assignee: Saint Gobain Glass France SAS; Compagnie de Saint Gobain SA
Priority date: 2007-04-17
Filing date: 2008-04-17
Publication date: 2010-01-27
Also published as: FR2915314A1; WO2008145908A2; CN101681797A; FR2915314B1; KR20100036228A; JP2010525509A; US20100253207A1; CA2684180A1; WO2008145908A3

Abstract

The invention relates to a flat lamp (1) transmitting radiation in the ultraviolet, called a UV lamp, comprising: first and second flat dielectric walls (2, 3) facing each other, kept approximately parallel and sealed between them, thus defining an internal space (10) filled with a gas (7), at least the first dielectric wall being made of a material transmitting said UV radiation; electrodes consisting of the first and second electrodes (4, 5) at different given potentials, for a perpendicular discharge between the walls, at least the first electrode being based on a layer arranged to provide overall transmission of the UV; an emitting gas or a phosphor coating (6) on a main internal face (22, 32) of the first and/or second dielectric wall (2, 3), the phosphor emitting said UV radiation by being excited by the gas. The invention also relates to its uses and to its manufacture.

Description

UV DISCHARGE FLOOR LAMP USES AND MANUFACTURING

The present invention relates to the field of UV flat lamps (UV for ultraviolet) and in particular relates to flat UV discharge lamps and the uses of such UV lamps and its manufacture.

Conventional UV lamps are formed by fluorescent tubes

UV filled with mercury and arranged side by side to form an emitting surface. These tubes have a limited life. In addition, the homogeneity of the emitted UV radiation is difficult to obtain for large areas.

Finally, such lamps are heavy and bulky.

Document US4945290 discloses a UV UV beam discharge lamp transmitting bidirectional UV radiation, comprising:

first and second planar walls, made of sapphire or quartz, held substantially parallel and sealed together, thus delimiting an internal space filled with a source gas of the UV radiation,

two electrodes in the form of metal grids integrated in the quartz or on the external main faces of the first and second planar walls and at distinct given potentials for a perpendicular discharge between the walls.

US4983881 discloses a similar UV flat lamp with phosphor coatings on the inner major faces of the first and second dielectric walls, the phosphor emitting said UV radiation being excited by the plasma gas.

It is an object of the invention to provide a high performance reliable flat discharge UV lamp of alternative design and / or operation which is preferably simpler and easier to achieve for a wide range of applications. For this purpose, the invention proposes a flat discharge lamp transmitting a radiation in the ultraviolet, said UV, comprising:

- First and second plane dielectric walls facing each other, held substantially parallel to each other and sealed between they, thus delimiting an internal space filled with gas, the first wall at least being made of a material transmitting said UV radiation,

first and second electrodes at distinct given potentials for a perpendicular discharge between the walls

("Non-coplanar configuration"),

a first electrode on the external main face of the first dielectric wall, the at least one first electrode being a discontinuous layer thus arranged to allow an overall (optimal) transmission of the UV,

a second electrode integrated in the second dielectric wall or on the external main face of the second dielectric wall

a source of the UV radiation comprising the gas and / or a phosphor coating on an inner main face of the first and / or second dielectric wall, the phosphor emitting said UV radiation being excited by the gas. The flat discharge lamp according to the invention is simpler to manufacture and gives access in particular to opaque materials to make the first electrode and preferably the second electrode. The use of a discontinuous layer (monolayer or multilayer) makes it possible to adjust even to improve the threshold of transmission in particular to reinforce the homogeneity.

The first electrode (and preferably the second electrode) may be discontinuous by forming discrete (spaced apart) electrode regions and / or by being an electroconductive layer with non-layered (insulating) regions. It is possible to form a one-dimensional or two-dimensional network of electrode zones (row (s) of rows, bands, grid, etc.).

The UV lamp according to the invention can take dimensions of the order of those currently achieved with fluorescent tubes, or greater, for example of at least 1 m ² .

Preferably, the transmission factor of the lamp according to the invention around the peak of said UV radiation may be greater than or equal to at 50%, even more preferably greater than or equal to 70%, and even greater than or equal to 80%.

The lamp must be hermetic, the peripheral seal may be made in different ways: - by a seal (polymeric, silicone type, or mineral, type sintered glass),

by a peripheral frame bonded to the walls (by gluing or any other means, for example a film based on glass frit), for example made of glass. The frame may optionally be used as a spacer, replace one or more spacers.

The dielectric walls serve as capacitive protection of the electrodes against ion bombardment.

Each electrode can be associated with the outer face of the dielectric wall in different ways: it can directly deposited on the outer face (preferred solution for the first electrode) or be on a dielectric carrier element, which is assembled to the wall of so that the electrode is pressed against its outer face.

This dielectric carrier element, which is preferably thin, may be a plastic film, in particular a lamination interlayer with a counter-glass for mechanical protection, or a dielectric sheet, for example glued by a resin or an inorganic seal, preferably at the periphery for passing through. UV where appropriate.

Suitable plastics are, for example: polyurethane (PU) used as flexible, ethylene / vinyl acetate copolymer (EVA) or polyvinyl butyral (PVB), these plastics serving as laminating interlayer, for example with a thickness between 0.2 mm and 1.1 mm, in particular between 0.3 and 0.7 mm, optionally carrying an electrode (preferably the second electrode),

rigid polyurethane, polycarbonates and acrylates, such as polymethyl methacrylate (PMMA), used in particular as a rigid plastic, optionally carrying an electrode (preferably the second electrode).

It is also possible to use PE, PEN or PVC or else polyethylene terephthalate (PET), the latter being thin, in particular between 10 and 100 μm, and capable of carrying the second electrode.

If necessary, it naturally ensures compatibility between different plastics used, including their good adhesion.

Naturally, any added dielectric element is chosen to transmit said UV radiation if it is disposed on one emitter side of the UV lamp.

UV radiation can be transmitted from one side only: the first wall. In this case, it is possible to choose a second electrode forming a UV-reflective solid layer and / or a second UV-absorbing dielectric wall and preferably with a coefficient of expansion close to the first wall. It is also possible to choose any type of electrode material (opaque or not), for example a wire or interlayer electrode in a lamination of the second wall with a counter glass or a rigid plastic.

Preferably, the UV radiation may be bidirectional, of the same intensity or intensity distinct from both sides of the lamp.

To gain compactness, manufacturing time and / or UV transmission, the first (and preferably the second electrode chosen as a layer) can preferably be deposited

(directly) on the outer face and not be covered by a dielectric (including a dielectric (film etc) covering the surface.

It may optionally provide a discontinuous protective layer (for example dielectric) superimposed on the layer.

A functional sub-layer (for example dielectric, barrier, hooking, etc.) may be provided under the electrode layer, and preferably discontinuous and in a manner analogous to the electrode layer.

With an electrode material transmitting said UV radiation, one can naturally increase the transmission by the discontinuities of the layer II can be in particular a very thin layer of gold, for example of the order of 10 nm, or of alkali metals such as potassium, rubidium, cesium, lithium or potassium for example from 0.1 to 1 micron, or be an alloy for example with 25% sodium and 75% potassium.

The electrode material is not necessarily sufficiently transparent to UV. An electrode material (first and preferably second electrode) relatively opaque to said UV radiation is, for example: - fluorine-doped tin oxide (SnO ₂ : F), or antimony, zinc doped or alloyed with at least one of the following: aluminum, gallium, indium, boron, tin (for example ZnO: Al, ZnO: Ga, ZnO: In, ZnO: B, ZnSnO),

indium oxide doped or alloyed, in particular with zinc (IZO), gallium and zinc (IGZO), tin (ITO), the conductive oxides are for example deposited under vacuum,

- a metal: silver, copper or aluminum, molybdenum gold, tungsten, titanium, nickel, chromium, platinum

The layer forming first and preferably second electrode may be deposited by any known means of deposition, such as liquid deposits, vacuum deposition (especially magnetron sputtering, evaporation), pyrolysis (powder or gaseous route) or by screen printing, by ink jet by scraping or more generally by printing.

An electrode material (first electrode and preferably second electrode) relatively opaque to said UV radiation is for example based on metal particles or conductive oxides, for example those already mentioned),

We can choose nanoparticles, therefore of nanometric size,

(for example with a nanometric maximum dimension, and / or a nanoscale D50), especially of size between 10 and 500 nm, or even less than

100 nm, to facilitate the deposition formation of fine patterns (for a sufficient overall transmission for example), in particular by screen printing.

Like (nano) metal particles (sphere, flake or "Flake" ...), we can choose in particular (nano) particles based on Ag, Au, Al, Pd, Pt, Cr, Cu, Ni.

The (nano) particles are preferably in a binder. The resistivity is adjusted for the concentration of (nano) particles in a binder. The binder can be optionally organic, for example acrylic resins, epoxy, polyurethane, or be developed by sol-gel (mineral, or inorganic organic hybrid ...).

The (nano) particles can be deposited from a dispersion in a solvent (alcohol, ketone, water, glycol, etc.). Commercial products based on particles that can be used to form the first and / or second electrode are the products sold by Sumitomo Metal Mining Co. Ltd.

- X100®, X100®D ITO particles dispersed in a resin binder (optional) and with ketone solvent, - X500® ITO particles dispersed in an alcohol solvent,

- CKR® silver particles coated with gold, in an alcohol solvent,

- CKRF® agglomerated gold and silver particles.

The desired resistivity is adjusted according to the formulation. Particles are also available from Cabot Corporation of USA (e.g. Product No. AG-D-G-100-Sl), or "Harima Chemicals, Inc." from Japan (NP Series).

Preferably, the particles and / or the binder are essentially mineral.

For the first electrode and preferably for the second electrode (especially if bidirectional radiation is desired), one chooses:

a screen printing paste, in particular:

a paste loaded with (nano) particles (as already mentioned, preferably with silver and / or gold): a conductive enamel (a silver-glass frit), an ink, a paste conductive organic (polymer matrix), PSS-PEDOT (from Bayer, Agfa) and polyaniline,

a sol-gel layer with (nano) conducting particles (metal) precipitating after printing,

a conductive ink loaded with (nano) particles (as already mentioned, preferably with silver and / or gold) deposited by ink jet, for example the ink described in the document US 20070283848

Preferably, the first electrode (and the second electrode) is essentially mineral.

The arrangement of the first electrode (and preferably the second electrode if appropriate) can be obtained directly by deposition (s) of electroconductive material (s) in order to reduce manufacturing costs. This avoids poststructures, for example dry and / or wet etchings, often using lithography processes (exposure of a resin to radiation and development). This direct network arrangement can be obtained directly by one or more appropriate deposition methods, preferably a liquid deposit, by printing, in particular planar or rotary, for example by using an ink pad, or by ink jet ( with a suitable nozzle), by screen printing ("screen or silk printing" in English), by simple scraping.

By screen printing, we choose a synthetic fabric, silk, polyester, or metal with a mesh width and mesh fineness adapted.

The first and / or second electrode can thus be mainly in the form of a series of equidistant bands, which can be connected by a particularly peripheral band for a common power supply. The strips may be linear, or be of more complex shapes, non-linear, for example bent, V-shaped, corrugated, zigzag. The strips may be linear substantially parallel, having a width 11 and being spaced apart by a distance dl, the ratio 11 on d1 being between 10% and 50%, to allow a overall UV transmission of at least 50%, the ratio ll / dl can also be adjusted according to the transmission of the associated wall.

More broadly, the first and / or second electrode may be at least two sets of crossed strips (or lines), for example organized in fabric, canvas, grid.

For example, for all series of bands, the same band size and spacing between adjacent bands is chosen.

Moreover, each band can be full or open structure.

For the second electrode, the solid strips may in particular be formed from contiguous conducting wires (parallel or braided, etc.) or from a ribbon (made of copper, to be glued, etc.).

The solid strips may be from a coating deposited by any means known to those skilled in the art such as liquid deposits, vacuum deposits (magnetron sputtering, evaporation), by pyrolysis (powder or gas route) or by serigraphy.

To form strips, in particular, it is possible to use masking systems to directly obtain the desired distribution, or to burn a uniform coating by laser ablation, chemical or mechanical etching. Each open-structure band may also be formed of one or more series of conductive patterns forming a network. The pattern is in particular geometric elongated or not (square, round, etc.).

Each series of patterns may be defined by equidistant patterns, with a given pitch said pi between adjacent patterns and a width called 12 patterns. Two sets of patterns can be crossed. This network can be organized in particular as a grid, as a fabric, a canvas. These patterns are for example metal such as tungsten, copper or nickel.

Each open-structure strip may be based on conductive wires (for the second electrode) and / or conductive tracks.

Also, it is possible to obtain a global UV transmission by adapting the ratio 11 to d1 of the series or series of bands according to the desired transmission and / or adapting, depending on the desired transmission, the width 12 and / or pitch pi of open structure strips.

Thus, the ratio of width 12 to pitch pi may preferably be less than or equal to 50%, preferably less than or equal to 10%, even more preferably less than or equal to 1%.

For example, the pitch pi may be between 5 μm and 2 cm, preferably between 50 μm and 1.5 cm, even more preferably 100 μm and 1 cm, and the width 12 may be between 1 μm and 1 mm, preferably between 10 and 50 microns. For example, a network of conductive tracks can be used

(Grid, etc.) with a pitch pi between 100 microns and 1 mm, or 300 microns, and a width 12 from 5 microns to 200 microns, less than or equal to 50 microns or even between 10 to 20 microns.

A network of conducting wires for the second electrode may have a pitch pi between 1 and 10 mm, especially 3 mm, and a width 12 between 10 and 50 microns, especially between 20 and 30 microns.

For the second electrode, the wires may be integrated at least partly in the second dielectric wall associated, or alternatively at least partially integrated in a lamination interlayer, in particular PVB or PU.

When the gas is UV source then in order to change UV, the gas must be replaced and it is then necessary to adapt the conditions of discharge and UV emission (pressure, supply voltage, gas height, etc.) accordingly. If one chooses the phosphor coating (s) according to the UV or UV that one wishes to produce, independently of the conditions of discharge. It is also not necessary to change excitatory gas.

In particular, there are luminophores emitting in the UVCs from a VUV radiation for example produced by one or more rare gases (Xe, Ar, Kr, etc.). For example, UV radiation at 250 nm is emitted by phosphors after excitation by VUV radiation of less than 200 nm. Mention may be made of materials doped with Pr or Pb such as: LaPO ₄ : Pr, CaSO ₄ : Pb etc. There are also phosphors emitting in UVA or near

UVB also from VUV radiation. Mention may be made of gadolinium doped materials such as YBO ₃ : Gd; YB ₂ O ₅ : Gd; LaP ₃ O ₉ : Gd; the

NaGdSiO ₄ ; YAI ₃ (BO ₃ ) ₄ : Gd; YPO ₄ : Gd; the YAIO ₃ : Gd; SrB ₄ O ₇ : Gd; LaPO ₄ : Gd; the LaMgB ₅ O _0: Gd, Pr; LaB ₃ O ₈ : Gd, Pr; (CaZn) ₃ (PO ₄ ) ₂ : TI.

In addition, there are UVA-emitting phosphors from UVB or UVC radiation for example produced by mercury or preferably gas (s) such as rare and / or halogenated gases (Hg, Xe / Br, Xe / I, Xe / F, Cl ₂ ,...). For example, LaPO ₄ : Ce; the (Mg, Ba) AI ₁₁ Oi ₉ ) Ce; BaSi ₂ O ₅ ) Pb; the YPO ₄ : This; (Ba, Sr, Mg) ₃ Si ₂ O ₇ : Pb; SrB ₄ O ₇ : Eu. For example, UV radiation greater than 300 nm, especially between 318 nm and 380 nm, is emitted by phosphors after excitation by UVC radiation of the order of 250 nm.

Thus, the gas may consist of a gas or a mixture of gases chosen from rare gases and / or halogens. The level of halogen (mixed with one or more rare gases) may be chosen less than 10%, for example 4%. Halogenated compounds can also be used. Rare gases and halogens have the advantage of being insensitive to climatic conditions. Table 1 below indicates the radiation peaks of the UV emitting gas emitting UV and / or exciters of the phosphors.

Table 1

Even more preferentially, one or more rare gases, in particular xenon, will be chosen as excitatory gas. Naturally, to maximize the discharge zone and for a homogeneous discharge, the first and second electrodes, continuous or in pieces, may extend over surfaces of dimensions at least substantially equal to the surface of the walls inscribed in the internal space.

For simplicity and to facilitate sealing, the first and second dielectric walls may be of identical materials or at least close expansion coefficient.

The material transmitting said UV radiation from the first or second dielectric wall may preferably be chosen from quartz, silica, magnesium fluoride (MgF ₂ ) or calcium fluoride (CaF ₂ ), a borosilicate glass, a silicosodocalcic glass in particular with less

0.05% Fe ₂ O ₃ .

As an example for thicknesses of 3 mm: magnesium or calcium fluorides transmit more than 80% or even 90% over the entire range of UVs that is to say UVA (between 315 and 380 nm) ), UVB (between 280 and 315 nm), UVC

(between 200 and 280 nm), or VUV (between about 10 and 200 nm), quartz and certain high purity silicas transmit more than 80% or even 90% over the entire range of UVA, UVB and UVC,

borosilicate glass, such as Schott borofloat, transmits more than 70% over the entire range of UVAs, silicosodocalcic glasses with less than 0.05% Fe III or Fe ₂ Cb, in particular Saint Diamond glass. -Gobain, Pilkington Optiwhite glass, Schott B270 glass, transmit more than 70% or even 80% over the entire range of UVA. A soda-lime glass, such as Planilux glass sold by Saint-Gobain, has a transmission greater than 80% beyond 360 nm, which may be sufficient for certain embodiments and applications.

In the UV plane lamp structure according to the invention, the gas pressure in the internal space can be of the order of 0.05 to 1 bar. The dielectric walls can be of any shape: the contour of the walls can be polygonal, concave or convex, in particular square or rectangular, or curved, in particular round or oval.

The dielectric walls may be slightly curved according to the same radius of curvature, and are preferably maintained at a constant distance, for example by a spacer (for example peripheral frame) or spacers (punctual etc.) at the periphery or preferably distributed (regularly, uniformly ) in the internal space. For example it is glass beads. These spacers, which may be described as punctual when their dimensions are considerably smaller than the dimensions of the glass walls, may affect various shapes, including spherical, spherical bi-truncated parallel faces, cylindrical, but also parallelepiped polygonal section, including in cross, as described in WO 99/56302.

The spacing between the two dielectric walls can be fixed by the spacers to a value of the order of 0.3 to 5 mm. A technique for depositing spacers in vacuum insulating glass units is known from

FR-A-2 787 133. According to this method, glue dots, in particular enamel deposited by screen printing, of a diameter, are deposited on a glass plate. less than or equal to the diameter of the spacers, the spacers are rolled on the glass plate preferably inclined so that a single spacer is glued on each point of glue. The second glass plate is then applied to the spacers and the peripheral seal is deposited.

The spacers are made of a non-conductive material to not participate in discharges or short circuit. Preferably, they are made of glass, in particular of soda-lime type. To avoid a loss of light by absorption in the material of the spacers, it is possible to coat the surface of the spacers with a transparent or UV reflective material or with a phosphor material identical to or different from that used for the wall (s) ( s).

In one embodiment, the UV lamp can be produced by first producing a sealed enclosure where the intermediate air gap is at atmospheric pressure, then evacuating and introducing the plasma gas to the desired pressure. According to this embodiment, one of the walls comprises at least one hole pierced in its thickness obstructed by a sealing means.

The UV lamp may have a total thickness less than or equal to 30 mm, preferably less than or equal to 20 mm.

Preferably the walls are sealed by a peripheral sealing gasket which is inorganic, for example based on glass frit.

The first electrode may be at a potential lower than the second electrode, especially in a configuration with an emitter side, the second electrode may then be protected by dielectric.

The first electrode may be at a potential less than or equal to

400 V (typically peak voltage), preferably less than or equal to 220 V, still more preferably less than or equal to 110 V and / or at a frequency f is less than or equal to 100 Hz, preferably less than or equal to 60 and again more preferably less than or equal to 50 Hz.

Vl is preferably less than or equal to 220 V and the frequency f is preferably less than or equal to 50 Hz. The first electrode may preferably be grounded.

The supply of the UV lamp can be alternative, periodic, especially sinusoidal, impulse, square (square etc.).

The UV lamp as described above can be used both in the industrial field for example for aesthetics, electronics or for food or in the domestic field, for example for the decontamination of tap water, water Pool drinking, air, UV drying, polymerization.

By choosing a radiation in the UVA or in the UVB, the UV lamp as described above can be used:

as a tanning lamp (in particular 99.3% in the UVA and 0.7% in the UVB according to the standards in force), in particular integrated in a tanning booth,

for the photochemical activation processes, for example for a polymerization, in particular of glues, or a crosslinking or for the drying of paper,

for the activation of fluorescent material, such as ethidium bromide used in gel, for nucleic acid or protein analyzes, for the activation of a photocatalytic material for example for reducing odors in a refrigerator or the dirt. By choosing radiation in the UVB, the lamp serves to promote the formation of vitamin D on the skin.

By choosing radiation in the UVC, the UV lamp as described above can be used for the disinfection / sterilization of air, water or surfaces by germicidal effect, especially between 250 nm and 260 nm.

By choosing a radiation in the far UVC or preferably in the VUV for the production of ozone, the UV lamp as described above is used in particular for the treatment of surfaces, in particular before deposition of active layers for electronics, computing, optics, semiconductors, ... The lamp can be integrated for example in household appliances such as refrigerator, kitchen shelf.

The subject of the invention is also the UV lamp manufacturing method, in particular of the type described above, in which a discontinuous electrode (first electrode and / or second electrode) is formed for global UV transmission directly by deposit. by liquid on the main face of a dielectric wall is formed by the arrangement of the directly by liquid deposition on the outer face (coated with a layer or not) of the first wall is particularly preferred a technique printing, (flexography, pad printing, roll ..) and in particular screen printing or inkjet.

Moreover, a peripheral electrical supply zone of the electrodes is generally formed. This zone, for example forming a strip is called "bus bar", and itself connected, for example by brazing or welding to a supply means (via a foil, a wire, a cable ..). This area may extend along one or more sides.

This power supply zone can be screen printed, in particular enamel with silver.

Also, it may be preferable to form at least one peripheral power supply zone of the discontinuous electrode during the step of depositing said electrode by screen printing (preferably of a conductive enamel) or even by ink jet. This method of manufacturing the UV electrode is suitable for the UV lamp as described above or for a lamp

UV with electrodes on the inner faces, or one on an inner face, the other on an outer face.

Further details and advantageous features of the invention appear on reading the example of the UV plane lamp illustrated in Figure 1 below which schematically shows a side sectional view of a UV flat discharge lamp in a mode of embodiment of the invention.

It is specified that for the sake of clarity the various elements of the objects represented are not necessarily reproduced on the scale.

FIG. 1 shows a flat UV 1 discharge lamp comprising first and second plates 2, 3, for example rectangular, each having an outer face 21, 31 and an inner face 22, 32. The lamp 1 emits a bidirectional UV radiation by its outer faces 21, 31. The surface of each plate 2, 3 is for example of the order of Im ² or beyond and their thickness of 3 mm.

The plates 2, 3 are associated with facing their internal faces 22, 32 and are assembled by means of a peripheral seal delimiting the internal space, here by a sealing frit 8, for example a glass frit thermal expansion coefficient close to that of the plates 2, 3.

Alternatively, the plates are assembled by an adhesive for example silicone (forming a seal) or by a heat-sealed glass frame. These sealing methods are preferable if plates 2, 3 are chosen with coefficients of expansion that are too distinct.

The spacing between the plates is imposed (at a value generally less than 5 mm) by glass spacers 9 arranged between the plates. Here, the spacing is for example 1 to 2 mm.

The spacers 9 may have a spherical shape, cylindrical, cubic or other polygonal cross-section for example cruciform. The spacers may be coated, at least on their side surface exposed to the plasma gas atmosphere, with a UV reflective material.

The first plate 2 has near the periphery a hole 13 pierced in its thickness, a few millimeters in diameter, the outer orifice is obstructed by a sealing pad 12, in particular copper welded to the outer face 21.

In the space 10 between the plates 2, 3 reigns a reduced pressure of 200 mbar xenon 7 to emit exciting radiation in the UVC. The lamp 1 serves for example as a tanning lamp.

The internal faces 22, 32 carry a coating 6 of luminophor material emitting radiation in the UVA preferably above 350 nm such as YPO ₄ : Ce (peak at 357 nm) or (Ba, Sr, Mg) ₃ If ₂ 0 ₇ : Pb (peak at 372 nm) or SrB ₄ O ₇ : Eu (peak at 386 nm).

A soda-lime glass such as the Planilux sold by the Saint-Gobain company is chosen which ensures a UVA transmission around 350 nm greater than 80% at low cost. Its coefficient of expansion is about 90 10 ^-8 K ^-1 .

In another variant, a gadolinium-based phosphor, and a borosilicate glass (for example with an expansion coefficient of about 32 × 10 ^-8 K ^-1 ) or a silicodio-calcium glass with less than 0.05% Fe ₂ are chosen. O ₃ , and a rare gas such as xenon alone or mixed with argon and / or neon.

Of course, other phosphors and a borosilicate glass can be chosen to transmit UVA at around 300-330 nm.

In another variant, the lamp 1 emits in the UVC, for a germicidal effect, then a luminophore is chosen such as LaPO ₄ : Pr or CaSO ₄ : Pb and for the walls, silica or quartz as well as a rare gas such as xenon, preferably alone or mixed with argon and / or neon.

The first electrode 4 is on the outer face 21 of the first wall 2 (always transmitting side). The second electrode 5 is on the outer face 31 of the second wall 3 (possibly emitter side).

Each electrode 4, 5 is in the form of a discontinuous layer at a single potential. Each electrode 4, 5 is in the form of at least one series or even two crossed series of strips 41, 51, for example solid strips. Preferably, the strips 41, 51 are of width 11 and of similar interband spacings d1.

The material of the first electrode (at least) is relatively opaque to UV, the band width ratio 11 is then adapted to the width of the interband space d1 accordingly to increase the overall UV transmission (for each series).

For example, a ratio of width 11 to width d1 of the interband space of the order of 20% or less is chosen, for example the width 11 is equal to 4 mm and the width d1 of the interelectrode space is equal to 2 cm.

The electrode material 4, 5 is for example silver preferably deposited by screen printing: for example a silver enamel or an ink with nanoparticles of silver and / or gold. The electrode material may alternatively be deposited in a thin layer by spraying and then etched.

Thus one can for example choose the Planilux glass with a copper layer, or silver or fluorine doped tin oxide which is etched to form the electrodes 4, 5 with a width equal to 1 mm and a gap of 5 mm to obtain an overall transmission of about 85% from 360 nm, while maintaining a very satisfactory homogeneity.

Planilux glasses can also be chosen for the walls, each having a fluorine-doped tin oxide layer which is etched to form the electrodes 4, 5 with a width equal to 1 mm and a gap equal to 5 mm to obtain an overall transmission of about 85% from

360 nm, keeping a very satisfactory homogeneity.

As a variant, each strip has an open structure (for example 15 to 50 μm wide and spaced apart by 500 μm and is screen printed) and may for example be formed of a network of conductive patterns, for example geometric (square, round , ... lines, grid), to further increase the overall UV transmission.

Alternatively, the electrodes 4, 5 are discontinuous layers extending on the faces and arranged in a grid, for example with a track width of between 15 and 50 μm and spaced apart by 500 μm, made by screen printing. For example, InkTec Nano Silver Paste Inks TEC PA 030 ™ ink is selected or a glass frit made of silver is screen printed.

In another variant embodiment, the second electrode 5 is a full aluminum layer forming a UV mirror. In a last variant embodiment, the second electrode 5 is a grid integrated in the wall 3 or embedded in an EVA or PVB interlayer type of lamination with a counter glass.

Each of the electrodes 4, 5 is fed via a flexible foil 11, 11 'or alternatively via a welded wire. The first electrode 4 is at a VO potential of the order of 1100 V and of frequency between 10 and 100 kHz, for example 40 kHz. The second electrode 5 is grounded.

Alternatively, the electrodes 4 and 5 are fed for example by signals in phase opposition, for example respectively at 550 V and -550 V.

The first electrode is preferably grounded and the second electrode is powered by the high frequency signal when only one side is emitter. Indeed, the second electrode can be protected. The first electrode 4 may be in electrical connection with a current supply band (commonly called "bus bar") which covers the crossed strips 51 (or the gate in the variant), at the periphery of at least one edge (for example). longitudinal example) of the first wall 2 and on which is welded a wire or a foil. The second electrode 5 may be in electrical connection with a current supply strip (commonly called "bus bar") which covers the crossed strips (or the grid in the variant), at the periphery of at least one edge (for example longitudinal) of the second wall and on which is welded a wire or a foil. These strips can be enameled with silkscreened silver or be deposited by ink jet, in particular at the same time as the electrodes (thus providing a solid peripheral band and sufficiently wide).

Claims

1. Flat discharge lamp (1) transmitting a radiation in the ultraviolet, said UV, comprising: - first and second dielectric walls (2, 3) plane facing each other, held substantially parallel and sealed together, thus delimiting a space gas filled inner wall (10), the at least one first dielectric wall being of a material transmitting said UV radiation, - first and second electrodes (4, 5), at distinct given potentials, for a perpendicular discharge between walls

a first electrode on the external main face (21) of the first dielectric wall, a second electrode (5) integrated in the second dielectric wall or on the external main face (31) of the second dielectric wall,

a source of the UV radiation comprising the gas (7) and / or a phosphor coating (6) on an inner main face (22, 32) of the first and / or second dielectric wall (2, 3), the phosphor emitting said UV radiation by being excited by the gas, characterized in that the at least one first electrode is a discontinuous layer, arranged to allow for overall transmission of the UV.

2. UV lamp (1) according to claim 1, characterized in that the first electrode (4) is deposited on the outer face (21) and preferably is not covered by a dielectric covering the surface.

3. UV lamp according to one of claims 1 or 2, characterized in that the second electrode is a layer preferably arranged to allow a global transmission of UV.

4. UV lamp (1) according to one of the preceding claims, characterized in that the UV radiation is bidirectional, that is to say on both sides of the lamp.

5. UV lamp (1) according to one of the preceding claims, characterized in that the first electrode (4) is in the form of a series of equidistant strips (41) or at least two crossed series of parallel strips, each band having a width 11 and being spaced apart by a distance d1 from an adjacent band, and in that the ratio 11 on d1 is between 10% and 50%.

6. UV lamp (1) according to one of the preceding claims, characterized in that the second electrode (5) is discontinuous, in particular in the form of a series of equidistant strips (51), layer, or at least two crossed series of parallel bands, each band having a width 11 and being spaced apart by a distance d1 from an adjacent band, and in that the ratio 11 on d1 is between 10% and 50%.

7. UV lamp (1) according to one of the preceding claims, characterized in that the first electrode and / or the second electrode is in the form of strips, each formed of one or more series of conductive patterns, in conductive tracks, defined by a given pitch said pi between patterns and a so-called width of 12 patterns, the ratio width 12 on pitch pi being less than or equal to 50%.

8. UV lamp (1) according to one of the preceding claims, characterized in that the first electrode, and preferably the second electrode, is organized as a grid.

9. UV lamp (1) according to one of the preceding claims, characterized in that the first electrode, and preferably the second electrode, is based on conductive particles, including silver and / or gold, optionally in a binder.

10. UV lamp (1) according to one of the preceding claims, characterized in that the first electrode, and preferably the second electrode, is a conductive enamel or conductive ink including silver and / or gold.

11. UV lamp (1) according to one of the preceding claims, characterized in that the material transmitting said UV radiation is selected from quartz, silica, magnesium fluoride or calcium, a borosilicate glass, a particular silicosodocalcic glass with less than 0.05% Fe ₂ O ₃ .

12. UV lamp according to claim, characterized in that the gas (7) consists of a rare gas, including xenon, or a mixture of gases selected from rare gases and halogenated gases.

13. Use of the UV lamp (1) according to one of the preceding claims in the field of aesthetics, electronics, food.

14. Use of the UV lamp (1) according to one of the preceding claims as a tanning lamp, in particular integrated in a tanning booth, for dermatological treatment, for the disinfection or sterilization of surfaces, air, water and tap water, drinking water, swimming pool, for the treatment of surfaces in particular before deposition of active layers, to activate a photochemical process of the polymerization or crosslinking type, for paper drying, for analyzes using materials fluorescent, for activation of a photocatalytic material.

15. A method of manufacturing a UV lamp characterized in that one forms a discontinuous electrode for a global UV transmission directly by liquid deposition on the main face of a dielectric wall.

16. A method of manufacturing the UV lamp according to claim 15 characterized in that one forms said electrode arrangement by printing, in particular by screen printing or inkjet.

17. A method of manufacturing the UV lamp according to one of claims 15 or 16 characterized in that one forms at least one peripheral power supply zone of the discontinuous electrode. during the step of depositing the first electrode by screen printing or by ink jet.