EP2272082A2 - Field-emission flat lamp and the manufacture thereof - Google Patents

Abstract

The subject of the invention is a field-emission flat lamp (100) transmitting radiation in the visible and/or the ultraviolet, comprising: first and second plane dielectric walls (1, 2) with an anode (3) and a cathode (4) respectively, the first wall/anode assembly being transparent or generally transparent in the visible and/or the UV, a cathodoluminescent material, and electron-accelerating element that comprises an essentially mineral (6) and apertured dielectric plate and/or a discontinuous enamel-based dielectric layer (6"), the openings emerging (63) on at least what is called the free main face (61) of the plate facing the internal face (21) of the first wall, for said electron bombardment, said apertured plate (6) or said discontinuous enamel-based dielectric layer (6") bearing, on its free face (61), a third electrode (7) forming an accelerating electrode, or having a poled surface, thus creating an electron-accelerating remanent electric field. The invention also relates to the manufacture thereof.

Description

 FIELD EFFECT-EMITTING FLAME LAMP AND MANUFACTURE THEREOF

The invention relates to the field of flat lamps and more particularly relates to a flat field emission lamp transmitting radiation in the visible and / or ultraviolet (UV) and its manufacture.

Among the known flat lamps are flat discharge lamps that can be used as decorative or architectural lighting. These flat lamps typically consist of two sheets of glass held at a small distance from one another, generally less than a few millimeters, and hermetically sealed so as to enclose a gas under reduced pressure in which an electric discharge occurs. radiation generally in the ultraviolet range which excites a photoluminescent material which then emits visible light.

UV lamps are also based on this technology.

Planar lamps based on the field effect emission used for the backlighting of liquid crystal displays ("LCD" for liquid crystal display) are also known. Document US2007 / 0228928A1 thus proposes a field effect emission lamp, which comprises:

an anode in the form of an electroconductive layer based on mixed indium tin oxide (ITO) deposited on the internal face of the first glass sheet, supplied with a positive voltage and covered with a layer of phosphor capable of producing white light by electron bombardment,

a cathode which is an electroconductive layer deposited on the internal face of the second glass sheet fed by a negative voltage, layer in the form of electrode strips ("patterned in English"),

microtips for the emission of electrons, arranged on the electrode strips,

and a stack formed of a dielectric layer covered with a metal layer forming an accelerating electrode ("spoils" in English), the stack being in the form of strips crossing the anode strips.

Moreover, the document entitled "the vacuum packaging of a flat lamp using thermally grown carbon natubes" by D. Lee et al., Vacuum 74 (2004) pages 105-111, Elsevier discloses a planar emission field effect lamp (see figure Ib), for the LCD backlight, with

- as walls, sheets of silicosodocalcic glass,

- series of phosphorus emitting respectively in the red, green, blue, to produce white light,

- as anode, a layer of ITO,

as cathode, a Ti / Cr multilayer surmounted by a Fe or Ni catalyst for the growth of the emitting material,

as electron-emitting material, carbon nanotubes ("CNT" in English) deposited at high temperature on the catalyst,

as an accelerating electrode, a metal grid interposed in the internal space parallel to the glass sheets, connected via the second sheet of glass by contact transfer, in the form of an array of hexagonal openings of 250 μm in diameter and width mesh size of 30 μm (see Figure b). With this triode technology, the applied voltage is reduced. The above-mentioned field emission planar lamps have certainly advantages in terms of compactness, optical performance but remain complex or expensive. Also, the present invention aims to provide a flat lamp

(in the visible and / or UV) simplified, including manufacturing compatible with industrial requirements (ease and / or speed of manufacture, low scrap rate) without sacrificing its optical performance (uniformity and / or efficiency) nor increase its power consumption. For this purpose, the present invention provides a field-emission flat lamp transmitting radiation in the visible and / or ultraviolet, comprising:

- First and second dielectric walls (substantially) planar facing and with main surfaces maintained (substantially) parallel and spaced, the lamp being sealed at the periphery thus delimiting an internal space under vacuum,

a first electrode, called anode, extending in a plane parallel to the main surfaces and associated with the first wall, the first wall and anode assembly being (substantially) transparent or globally transparent in the visible and / or the UV, (at least) a luminophor material emitting visible and / or ultraviolet radiation by electron bombardment (in other words "cathodoluminescent"), the material being on the internal face of the first wall (for example deposited on this face) and closer of the internal space that the anode,

a second electrode, called a cathode, extending in a plane parallel to the main surfaces,

a material emitting said electrons having a shape factor of greater than 10, the material being on the cathode (directly or not on it), and preferably defining a plurality of so-called emitting zones,

an electron accelerator element interposed between the first and second walls, spaced from the first wall, extending in a plane substantially parallel to the main surfaces, and with a plurality of openings allowing said electrons to pass, said element comprising a dielectric plate; , essentially mineral and perforated, and / or a discontinuous dielectric layer based on enamel with openings opening on at least the main face, said free, opposite the inner face of the first wall,

for said bombardment of the electrons, the perforated plate or said enamel-based discontinuous layer being carrying on its free face a third electrode, forming an accelerating electrode, or said enamel-based discontinuous plate or layer having a polished surface creating a remanent electric field remanent electrons (a passive configuration),

the cathode being on the internal face of the second wall and / or when the openings of the perforated plate are chosen blind, in the bottom of the openings of the plate. The lamp according to the invention is simpler and more economical by using the perforated mineral dielectric plate or the accelerating enamel layer (outer surface).

To form the openings of the plate (possibly coated), or of the discontinuous enamel layer (s), it is easy to dispense with the photolithography techniques usually used for the screens of the prior art in order to form small-sized pixels, a technology necessary for etching the stack formed of the insulating layer, of the accelerating metal layer of the prior art, deposited layers conventionally by physical vapor deposition ^λ PVD '(spraying, evaporation, etc.) .

To form the perforated plate coated with an accelerating electrode according to the invention, it is possible to make a full layer (by any technique of deposition of layers: physical ^λ PVD ', chemical or ^λ CVD', by liquid ...) on a solid plate and then make the openings on the set. Alternatively, the openings can be made before coating by the accelerating electrode.

In an active configuration, it is possible to form on the cathode (which is preferably on the internal face of the second wall) successively - a layer of dielectric enamel,

a layer of conductive enamel.

In a passive configuration, a polished enamel layer may be formed on the cathode (which is preferably on the inner face of the second wall). The cathode itself may also be enamel conductive, including an enamel identical to that of the accelerating electrode.

According to the invention, enamel is understood to mean a layer at least partly vitreous, obtained by depositing and then firing a glass frit, optionally mixed with, for example, conductive inorganic fillers, if necessary.

The glass frit can be mixed before deposition with a binder or medium, usually organic, which will be removed during cooking.

The deposition of the vitreous layer according to the invention can be carried out by various selective deposition techniques, that is to say on certain predetermined areas spaced apart from each other (carrier spaces of the electron-emitting material), this to avoid any structuring , all masking, in particular photolithography type steps as already indicated. We choose in particular a liquid deposit, such as screen printing or inkjet, printing, pad printing ...

The apertures of the perforated plate and / or layer (s) of enamel may be relatively wide, especially micron or millimetric particularly in general lighting or backlight applications that do not require forming pixels, which gives greater freedom of manufacture.

The openings are preferably made by the face opposite to the accelerating layer. The various existing processes often result in the formation of slightly tapered apertures, the base of the (widest) cone being located on the side through which the openings are made. By making the opening by the face opposite to the accelerating layer, the emitting material is therefore subjected to a stronger accelerator field.

Typically, the openings of the perforated plate or enamel-based layer (s) may have an average, minimum and / or maximum width (thus a characteristic dimension in the plane of the plate) greater than or equal to

10 μm, even greater than or equal to 100 μm or even greater than or equal to

1 mm.

The plate may be perforated before or after poling the plate or the accelerating layer above depending on the methods used to form the openings.

For example, a laser engraving (femtosecond in particular), a mechanical cutting with a diamond saw, sandblasting, a high pressure jet (water or other liquid) is used. To rectify the edges possibly in V and to obtain flanks

(Substantially) straight, one can for example supplement by a suitable chemical attack, for example acid attack (HF) of the glass, by plasma etching ("RIE" etc.), ion bombardment (IBE etc.).

The openings may be extended, elongated including substantially linear strips, and / or more specific, including geometric (round, square, rectangle, oval, ..).

The openings are not necessarily of the same size or shape. However, it is possible to prefer openings distributed substantially uniformly over the surface of the plate, for example a periodic network lines or rectangles or rounds, multiple networks (double periodic network), or even a pseudo periodic or aperiodic network.

One or more more or less extended zones of the plate and / or discontinuous enamel layer (s) may be devoid of openings to produce, for example, a differentiated illumination (dark zones and alternating light zones, for example). .

The openings are preferably of dimensions substantially equal to the dimensions of the emitting zones. The spacing (average) between these openings may be micron, even more preferably at least one hundred microns, or even millimetric. The spacing between two openings may be the same as or larger than the width of the openings. The lateral edges (flanks) of the openings may be substantially straight, substantially perpendicular to the internal face of the second wall.

The mineral plate, especially glass, as the enamel layer according to the invention has good mechanical strength, thermal and supports electron bombardment and sealing while being inexpensive.

The lamp according to the invention can be large, for example at least 0.1 or even 1 m ² .

Preferably, the transmission factor of the lamp according to the invention (at least second wall side) around the peak of said visible radiation and / or UV is greater than or equal to 50%, even more preferably greater than or equal to 70%, and even greater than or equal to 80%.

The plate can be flexible, semi rigid, preferably rigid. It is a self-supporting piece, in one or more pieces, to distinguish a layer.

In addition, the mineral dielectric plate and hole according to the invention is also preferable to a metal grid because easier to insert, to seal if necessary. In the prior art to be sufficiently resistant to withstand the thermal cycle during manufacture, vacuum, electron bombardment, an Invar® gate is used in practice, an expensive material based on nickel and iron.

The use of the mineral dielectric plate and perforated according to the invention also allows greater flexibility of manufacture: the deposition of the electron-emitting material can be achieved before or after mounting the plate, in particular before or after its adhesion on the second wall if necessary.

The plate may advantageously be based on a material chosen from a ceramic, a glass-ceramic, a glass in particular silicosodium-calcium. Preferably, the walls and / or the possibly perforated plate may be sheets of glass, in particular silicosodocalcique (in particular when the wall is not itself polished) this especially for a lamp.

In the case of a UV lamp, the walls or the perforated plate may preferably be a suitable glass or quartz. The plate may be thin, for example of thickness less than or equal to 1 mm, especially when it is attached to the second wall. In the case of a self-supporting glass plate, its thickness is preferably between 0.7 and 3 mm.

In the case of discontinuous layer (s) enamel, the thickness of each layer (dielectric or electroconductive) may be lower, typically between 1 and 50 microns, especially between 5 and 20 microns, or between 10 and 15 micrometers.

The plate may preferably be in one piece or even discontinuous, in the form of a plurality of plate pieces which may be of any shape (geometric: rectangular, square, etc.), more or less elongated, pieces spaced apart others by continuous openings. These pieces of plate can be preferably distributed homogeneously.

The lamp must be hermetic, the peripheral sealing can be done in different ways:

- by (at least) a seal: polymeric (silicone etc.), or mineral (glass frit, etc.),

by (at least) a peripheral frame bonded to the walls (and / or to the plate if appropriate), for example heat-sealed or bonded with a film, preferably mineral, such as a glass frit, film of a few hundred μm or less thick, the frame may also optionally be used as spacer, replace one or spacers punctual.

The seal may preferably be made by (at least) a seal, especially (essentially) mineral. The seal may be made for example between the first and second walls via their internal faces, the perforated plate being in the internal space and of smaller dimensions than the second wall.

The seal may also be made between the free face of the plate (which is optionally the inner face of the second wall) and the inner face of the first wall.

Also, it is preferred to choose a plate material with a coefficient of thermal expansion close to or similar to that of the first wall. The plate is then of substantially identical dimensions or even greater than the dimensions of the walls.

In addition, the arrangement of the perforated plate may be variable.

In a first configuration, the perforated plate is spaced from the second wall (by the vacuum) and openings are open on the face opposite to the free face (the opposite face being said lower face). A double peripheral sealing is then provided: first sealing between the free face of the perforated plate and the internal face of the first wall and second sealing between the perforated lower face and the internal face of the second wall.

The plate may be typically spaced from the second wall by a distance of less than or equal to a few mm and the first wall by a distance of less than or equal to a few mm.

In this double-seal configuration, the optional accelerating electrode is preferably integrated in a glass (reinforced glass) or better still on the lower face, and preferably in the form of an electroconductive layer.

The openings may be blind, made on the plate preferably forming the second wall.

Thus, in a second configuration, the second wall consists of the perforated plate with the blind openings (non-emergent on the lower face), preferably opening on (at least) one (same) edge of the second wall, and the cathode , in the form of an electroconductive layer, is in the bottom of the openings and fed by said edge (lateral or longitudinal) preferably hollowed out, this to facilitate the peripheral electrical connection. The emitting material is then housed in the bottom of these openings, on the cathode if necessary forming a catalyst or optionally surmounted by a catalyst.

The blind openings, in particular outlets, can be of any shape (polygonal, round, oval, etc.), and preferably in the form of grooves. The grooves can be parallel or not, in profile

(substantially) constant (rectangular, square ..) or not. The grooves may be longer or shorter, in particular in one or even in several parts and preferably then open on two opposite or adjacent edges facilitate the peripheral electrical connection.

In a third configuration the lower face of the plate is secured to the inner face of the second wall by a connecting means, preferably substantially mineral.

This connection may be peripheral, on localized (restricted) areas (by adhesive spots, etc.) but preferably this connection is distributed over the entire surface of the plate, for example a layer between the plate and the plate. second wall.

This connection between the second wall and the perforated plate must be compatible with the manufacturing process of the lamp: evacuation, heating ...

An essentially inorganic bonding means is thus preferred, thus having a good thermal and mechanical behavior, in particular a glass frit, such as a sintered frit or any other material, a solder or a solder (based on nickel, chromium, indium gold or tin). etc.), anodic sealing.

When the seal is made between the plate and the first wall, the connection between the second wall and the perforated plate preserves the hermeticity, and this connection is sealed with liquid water and / or steam.

For peripheral sealing in the form of a seal and for the connection plate and second wall (punctual or extended), one can use the same material, for example a glass frit deposited for example by screen printing.

For the sake of simplicity, in this third embodiment, the openings are preferably also open on the face opposite to the free face (therefore the lower face) and the cathode, the inner face of the second wall comprises an outer electroconductive layer of a connecting material between the second wall and the perforated plate, and electroconductive to form at least partly the cathode and / or a growth catalyst of the layer emitting material. This layer is thus at least bi-functional (bonding function coupled to an electrical function and / or growth catalyst). It is present under the emitting zone or zones and under the plate.

The outer layer, which is preferably a monolayer directly on the inner face, may advantageously be made of a material chosen from nickel, chromium, iron, cobalt and their mixtures (especially NiCr).

Regarding the emitting material, the form factor corresponds to the ratio width (maximum if variable) on height (maximum if variable).

The material can be of various shapes: filamentary, tubular, conical. The emitting material may have tips, especially metal, typically tungsten, micron or submicron.

These tips may preferably be oriented towards the first wall, in particular be substantially 90 ° from the first wall.

The emitting material may also be based on zinc oxide nanowires. The typical dimensions of such nanowires are as follows: length ranging from 1 to 10 microns, preferably from 3 to 5 microns, diameter ranging from 50 to 500 nanometers, preferably from 100 to 300 nm.

These zinc oxide nanowires can advantageously be obtained, at low temperature, by electrochemical deposition. The publication titled

"Controlled growth of two-dimensional and one-dimensional ZnO nanostructures on Indium Tin Oxide coated glass by direct electrodeposition", by Pradhan et al., Langmuir 2008, 24, 9707-9716, describes in particular a method of this type, in which one deposits ZnO nanowires on a glass substrate coated with an electroconductive layer of indium tin mixed oxide (ITO) by immersing it in a solution of zinc nitrate Zn (NO ₃ ) 2.6H ₂ O and in establishing a potential difference of -1.1 V relative to a counter-electrode.

The emitting material may also be based on amorphous carbon in layers, in particular graphitic or more preferably in the form of nanotubes. The thickness of the carbon nanotube layer may typically be at 100 nm, of the order of one micron, or between 1 and 10 μm. The width of the nanotubes is typically of the order of 10 nm.

The form factor is preferably greater than or equal to 100, or even greater than or equal to 1000.

The carbon nanotubes can be deposited by any known method at a temperature compatible with the selected substrate:

chemical-assisted plasma deposition "PECVD" in particular with atmospheric plasma (AP-PECVD) as described in the publication titled "growth of carbon nanotubes by atmospheric pressure enhanced chemical vapor deposition unsing NiCr catalyst" by Se-Jin Kying and others , Surface and coatings technology, 201 (2007) 5378-5382,

thermal growth deposition as carried out by Ijin Nanotech Co Itd in the previously cited prior art document by Lee et al.

for example, screen printing deposition as described in the document titled CNT-FED fabricated using photosensitive CNT paste of S Jik-Kwon et al., Journal of Information Display, Vol. 5, No. 4, 2004. Two acceleration configurations are possible according to the invention.

In the active configuration, the accelerating electrode in the form of an electroconductive layer, in particular a metallic layer, which may preferably be on a sub-layer (alkali barrier, hung, etc.), in particular a layer based on silica or nitride silicon and / or covered by a protective overcoat, in particular a layer of silica or silicon nitride.

An electroconductive layer may preferably be chosen as a metal layer, for example a silver layer, in particular screen printed (silver enamel, etc.), or a conductive metal oxide layer.

This accelerating layer is not necessarily full, completely covering. It can be discontinuous, forming strips, conductive tracks, in particular be arranged in a grid. This accelerating layer may also be deposited under vacuum, in particular by magnetron sputtering, before or after the formation of the openings, or deposited by screen printing or by ink jet.

When the plate is smaller than the second wall, the accelerating electrode can be fed peripherally by the first wall via a metallized spacer or a paste or conductive adhesive.

In the passive configuration, a surface is polished, which in particular makes it possible to further reduce the operating voltage.

In a first passive configuration, the glass plate (possibly forming the second wall) itself can be polished. In a second, original passive configuration, the plate (for example made of glass or quartz, and / or possibly forming the second wall) may comprise a polished layer. This layer may for example be based on silica. The polished layer may also be a polished enamel. The plate may also be optionally polished. The thickness of the polished layer may for example be of the order of one micron.

Preferably, a silica layer, deposited under vacuum, in particular by magnetron sputtering or evaporation, or by chemical vapor deposition (CVD), is chosen. The silica layer is deposited before or after the formation of the openings.

The polished layer may also be enamel, especially from a vitreous material deposited by selective deposition techniques such as screen printing, inkjet, or printing, as already seen.

In a third, original passive configuration, the poled layer, directly on the cathode, is a polished enamel.

Thus, against all odds, an enamel-based layer (formed by firing glass frit) can be polished.

"Polished material" generally means a material having at at least one of its surfaces a remanent electric field. By extension, a "polished surface" (plate and / or reported layer) of the material is thus defined as being the surface area where the remanent electric field is created. The remanent electric field is preferably oriented perpendicular to the surface of the material. It is usually created by a process of placing the heated material under a strong electric field. Some glasses, crystals or polymers are especially polished (have underwent so-called "poling" treatment) to give them properties in nonlinear optics, in particular second harmonic generation. In the case of glasses (for example of amorphous silica), the remanent field is linked to the migration of cations, in particular alkali (Li ⁺ , Na ⁺ , K ⁺ ...) or alkaline earth (Mg ²⁺ ) ions. , Ca ²⁺ , Sr ²⁺ , Ba ²⁺ ...). This local depletion of cations at the extreme glass surface creates an extremely intense internal electric field. The poling also generates a very strong residual field, because it is confined to a very small thickness (sometimes of the order of a few micrometers).

The migration of sodium ions present as impurities in a glass under the action of an electric field is described in the publication R / A.Myers, Optical letters, vol. 161, 1991, pl732.

The polished material is preferably chosen from glasses (in particular based on silica) and glass-ceramics. "Silica-based glass" means glasses whose chemical composition comprises at least 50% by weight of SiO ₂ .

The mineral materials are preferred in particular because of their behavior during sealing. Glasses, in particular based on silica, among which include silica glass (also called amorphous silica), are particularly advantageous. Preferably, the polished material (from a glass frit or a conventional layer) is a silica-based glass comprising less than 1% by weight of alkaline oxides, in particular a glass comprising silica and alkaline earth oxides such as CaO, MgO, SrO, BaO. Pure silica has indeed a very high melting point (more than 1700 ⁰ C), which requires the use of very expensive fusion processes. The addition of alkaline earth oxides makes it possible to reduce the melting point, and to employ fusion processes conventionally used in glassmaking. It is thus possible to develop these glasses at temperatures of less than or equal to 1700 ^° C. or even 1600 ^° C. The presence of alkaline oxides (Li ₂ O, Na ₂ O, K ₂ O) also contributes to facilitating the fusion glass. Their total content is, however, preferably limited to less than 1% by weight, because their presence in large quantities contributes to reducing the life of the residual field. The silica-based glass may also contain other oxides such as Al ₂ O ₃ or B ₂ O ₃ , the latter facilitating melting. The silica-based glass may advantageously have one of the compositions described in application EP 1 433 758. The poling creates at at least one surface (called polished surface) of the dielectric material a remanent electric field over a thickness preferably between 0.5 and 50 microns, especially between 5 and 20 microns. The polishing treatment generally consists in creating a voltage of the order of a few hundred or thousands of volts by means of two plane electrodes between which (and in contact with which) is placed the material to be polished. Generally, the material is heated to a temperature of about 100 to about 500 ⁰ C, typically of the order of 300 ⁰ C, so as to promote the migration of the cations to the cathode. The remanent electric field created by the poling is preferably between 0.01 and 1 GV / m, in particular between 0.1 and 1 GV / m.

Moreover, the positions and types of electrodes can be variable. The electrodes (anode and / or cathode and / or optional accelerating layer) may be in the form of layers. Unless otherwise indicated, in the present invention the term layer may refer to a monolayer or a multilayer.

Unless otherwise indicated, the electroconductive layers (anode and / or cathode and / or accelerating layer if any) may be deposited by any means known to those skilled in the art such as deposits by liquid means, in particular by screen printing or inkjet, vacuum deposition (magnetron sputtering, evaporation), by pyrolysis (powder or gas route).

The cathode can cover substantially entirely the inner face of the second wall (excluding emargetting). The cathode may comprise one (or even consist of) an electroconductive layer. The cathode may be continuous or discontinuous, especially only in the given emitting zone or zones, for example in the form of bands (solid or open), conductive tracks. The cathode can in particular be arranged in a grid.

The cathode is not necessarily transparent or globally transparent. As non-transparent electrode material (layer or wire) can be used for example a metal material such as tungsten, copper or nickel.

In particular, the cathode may be a metallic electroconductive layer optionally forming a catalyst for growth of the emitting layer material, in particular a material selected from nickel, chromium, iron, cobalt and mixtures thereof.

However, it is also possible to envisage for the cathode a (full) transparent layer (in the visible): - based on a thin pure or alloy metallic layer, in particular silver, possibly between two single or mixed conductive oxide layers and / or doped, forming a transparent multilayer,

based on a single or mixed and / or doped conductive metal oxide, such as fluorine doped tin oxide, mixed indium tin oxide (ITO).

It is also possible to choose a LiF layer for the cathode. The possible accelerating electrode may cover substantially the entire free face of the plate. The accelerating electrode may be continuous or discontinuous, in the form of strips (solid or open), be arranged in a grid. The accelerating electrode may be based on woven or non-woven son, solid tape or braided, for example partially embedded in the plate.

In active configuration, the accelerating electrode may be based on

(nano) metal particles - in particular (nano) particles of gold and / or silver or conductive oxides, (nano) particles preferably in an even more preferably mineral binder. It may in particular be an enamel layer, comprising, after firing, a vitreous binder and

(nano) metal particles. This electroconductive layer, especially in the form of enamel, can be for example screen-printed or deposited by ink jet.

The anode can be made of any transparent conductive material that passes the visible and / or UV. The anode can be:

- Is associated with the outer face of the first wall, affixed (directly or not) to this face or integral with this face (in contact or separated by any known adhesive means),

- is associated with the inner face of the first wall, in particular deposited directly on this face or on a sub-layer,

it is partially integrated on the surface or entirely in the first wall (type reinforced glass). The anode can thus cover substantially entirely the face (internal or external) of the first wall (excluding unmapping). The anode can be thus continuous (full layer) or discontinuous, in the form of strips (full or open), arranged in grid (for a global transparency). Preferably, the electroconductive layer forming the anode is on a sub-layer (alkaline barrier, hooked etc.), in particular a layer of silica or silicon nitride.

The anode is preferably an electroconductive layer on the inner face of the first wall. The anode may be in the form of a transparent electroconductive (full) layer or a relatively opaque, discontinuous layer (for overall transparency).

We can prefer an anode in the form of a (full) transparent layer (in the visible):

based on a thin pure or alloyed metallic layer, in particular silver, optionally between two single or mixed conductive oxide and / or doped layers, forming a transparent multilayer,

based on a single or mixed and / or doped conductive metal oxide, such as fluorine-doped tin oxide, mixed indium tin oxide (ITO). The opaque electroconductive layer anode (in the visible and / or the UV) may be based on (nano) metal particles - in particular (nano) particles of gold and / or silver or conductive oxides, (nano) particles preferably in an even more preferably mineral binder. This opaque and discontinuous electroconductive layer may for example be screen printed or deposited by ink jet.

The anode may alternatively be based on woven or non-woven yarns, joined or not, solid or braided ribbon, etc. for example partially incorporated in the first wall or in external dielectrics.

For the UV lamp, the anode may be based on a material transmitting UV radiation. An electroconductive material transmitting UV radiation may be 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 0.1 to 1 micron, or be an alloy for example with 25% sodium and 75% potassium. As already mentioned, if the material of the anode (and / or the cathode and / or any accelerating electrode) is absorbent or reflective to UV and / or visible light, the anode ((and / or the cathode and / or the possible accelerating electrode) is adapted to allow an overall transmission to said UV or visible radiation.

More precisely, it is thus possible to form substantially parallel strips having a width 11 and being spaced apart by a distance d1, the ratio 11 on d1 being between 10% and 50%, to allow a UV or visible overall transmission of at least 50% of the side of the electrodes, the ratio ll / dl can also be adjusted according to the transmission of the associated wall.

It is also possible to form a network of essentially elongated conductive patterns such as conductive lines (similar to very fine bands) or conducting wires themselves, these patterns being able to be substantially rectilinear or wavy, zigzag, etc. This network can be defined by a given pitch pi (not minimal in case of plurality of steps) between patterns and a so-called width of 12 patterns (maximum in case of plurality of widths). Two sets of patterns can be crossed. This network can be organized in particular as a grid, such as a fabric, a canvas, etc. Also, it is possible to obtain an overall UV or visible transparency by adapting the ratio 11 to dl as a function of the desired transparency as already described and / or by using the network of conductive patterns and adapting, depending on the desired transparency. , the width 12 and / or the pitch pi. 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.

As examples, a conductive network (grid, etc.) can be used on a glass or on a plastic sheet, for example of the PET type, with a pitch pi of between 100 μm and 300 μm, and a width of 10 to 10 μm. 20 microns or a network of son embedded in at least a part in a interlayer lamination, with a pitch pi between 1 and 10 mm, in particular 3 mm, and a width 12 between 10 and 50 microns, especially between 20 and 30 microns.

With regard to the power supply, the anode may be electrically powered to a positive potential V1 typically between 1000V and 3000V, preferably by a supply structure (commonly called "bus bar") outside or less outward outside .

The cathode is electrically powered at a negative or even zero (grounded) continuous potential V2, preferably by an external or external power supply structure. For electrical safety, electromagnetic shielding can be provided. For example, a sufficient dielectric thickness is provided above the anode (only thickness of the first wall or thickness combined with an added transparent dielectric). It is also possible to provide a transparent outer conductor element that is anode and electrically isolated from the anode and grounded, for example it is a single or multilayer transparent electroconductive layer) or a generally transparent grid associated with the anode. the outer face of the first wall, the anode being on the inner face. This layer can also have a low-emissive function or solar control. In a first embodiment:

Vl is between 1000 V and 3000 V,

- V2 is grounded.

In a second embodiment:

- Vl is between 500 V and 1500 V, - V2 is between -500 V and -1500 V.

The accelerating electrode may be electrically powered at a DC potential V3 typically between 100 V and 800 V.

Naturally, the flat lamp may be provided with spacers, in particular glass, beads or other, distributed on the surface. It is possible to provide a spacer of the peripheral frame type, in particular for small lamp sizes, which peripheral frame can possibly be used for sealing.

The walls can be kept at a constant distance. The walls can be of any shape: the outline of the substrates can be polygonal, concave or convex, in particular square or rectangular, or curve, radius constant or variable curvature, in particular round or oval.

Preferably, the first and second walls may be a silicosodocalcic, borosilicate glass sheet. The glass can be clear, extraclear.

It is possible to coat and / or treat at least the first wall to ensure an optical effect, in particular a colored effect, a decoration effect by screen printing or the like, with structured relief, a frosted effect, or a diffusing, anti-reflective layer.

For a UV lamp, the first wall may be of a dielectric material transmitting UV radiation. The material for one or the walls may be chosen preferably from quartz, silica, magnesium fluoride (MgF ₂ ) or calcium fluoride (CaF ₂ ), a borosilicate glass, a glass with less than 0.05% Fe ₂ O ₃ .

As examples for thicknesses of 3 mm:

magnesium or calcium fluorides transmit more than 80% or even 90% over the entire range of UVs, ie UVA (between 315 and 380 nm), UVB (between 280 and 315 nm), the 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, like Schott's borofloat, transmits more than 70% over the entire range of UVA,

silicosodocalcic glasses with less than 0.05% Fe ₂ O ₃ , in particular Saint-Gobain's Diamant glass, Pilkington's Optiwhite glass and Schott's B270 glass, transmit over 70% or even 80% over the entire range of UVA. However, a silica-based glass, such as Planilux glass sold by Saint-Gobain Glass, has a transmission greater than 80% beyond 360 nm, which may be sufficient for certain embodiments and applications.

The spacing between the two walls may be fixed by the spacers to a value of the order of 0.3 to 5 mm, especially less than or equal to about 2 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, are deposited on a glass sheet. a diameter less than or equal to the diameter of the spacers, the spacers are rolled on said glass sheet preferably inclined so that a single spacer is glued on each point of glue. The second glass sheet is then applied to the spacers and the peripheral seal is deposited.

The spacers may be made of a non-conductive material. Preferably, they are made of glass, in particular of soda-lime type.

In one embodiment, the lamp may be produced by first manufacturing a sealed enclosure where the intermediate air gap is at atmospheric pressure and then evacuating, preferably (at least) secondary. According to this embodiment, one of the walls, preferably the first wall, comprises in its thickness a hole obstructed by a sealing means, preferably mineral.

All or part of the inner face may be coated with the cathodoluminescent material. In particular, it is possible to provide only certain areas of the surface of cathodoluminescent material in order to create on the same surface predefined illumination areas (respectively UV emission). The lighting zones may possibly constitute decorative motifs or constitute a display such as a logo or a mark.

The cathodoluminescent material may advantageously be selected or adapted to determine the color of the illumination in a wide range of colors.

For a lamp, one can choose the usual phosphors. For a UV lamp, there are particular phosphors emitting in the UVC. Mention may be made of materials doped with Pr or Pb such that: LaPO ₄ : Pr; CaSO ₄ : Pb etc.

There are also phosphors emitting in UVA or near UVB. Mention may be made of gadolinium doped materials such as YBO ₃ : Gd; the

YB ₂ O ₅ : Gd; LaP ₃ O ₉ : Gd; 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; the LaB ₃ O ₈ : Gd,

Pr; (CaZn) ₃ (PO ₄ ) ₂ : TI. There are also phosphors emitting in

UVA. For example, LaPO ₄ : Ce; (Mg, Ba) AluOi 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.

Uniformity can be evaluated by contrast (the ratio of the difference between the maximum luminance and the minimum luminance and the sum of the maximum luminance and the minimum luminance). A contrast of less than 80% or even less than or equal to 50% is preferred. The total efficiency of the lamp can be evaluated by the efficiency in Lumen / W is the ratio between the radiating power (optical or UV) and the electric power injected. A yield greater than or equal to 10 lumens / W is easily obtained. The lamp (UV) according to the invention may have radiation

(essentially) monodirectional (first wall side).

In a lamp configuration (UV) with a single emitting face, the other wall may be opaque, for example a glass-ceramic, or even be a non-glass dielectric, preferably with a neighbor expansion coefficient. The lamp (UV) according to the invention may have a bidirectional radiation (first side wall). For example, a differentiated illumination can be produced.

On the side of the second wall the overall transmission in the visible and / or in the UV may be greater than 50%, in particular by sufficiently limiting the area of the emitting area (s) for example a surface area (s) Transmitter (s) less than or equal to 50% of the inner surface of the lamp. The second wall assembly (glass for example) and cathode may further preferably have a global transmission in the visible of at least 70%. Finally, the cathode may be transparent (in full layer) or generally transparent (in strips, grid etc.) as already described.

The lamp emitting in the visible according to the invention can be used for decoration, for a backlight display screens (LCD, television, monitor ..). The invention aims for example the production of illuminating architectural or decorative elements and / or display function (identifying elements, logo or luminous mark), such as particularly flat luminaires, luminous walls in particular suspended, luminous slabs. .. The lamp emitting in the visible according to the invention can in particular form:

an illuminating window portion (a transom, etc.) of a building or means of locomotion, in particular a train window, a porthole of a boat cabin or aircraft,

- an illuminating roof including a means of locomotion land, air or sea,

- an internal partition between rooms or between two compartments of means of locomotion terrestrial, aerial or maritime, - a showcase, an element of street furniture, a furniture facade, a refrigerator shelf.

The lamp can be laminated with a first counter-glass associated with the second wall by a lamination interlayer (PVB, PU, EVA ..) or with a second against glass associated with the second wall by a lamination interlayer (PVB, PU , EVA ...).

The UV lamp according to the invention can be used both in the industrial field for example for aesthetics, biomedical, electronics or foodstuffs than in the domestic field, for example for the decontamination of tap water, pool drinking water, air, drying

UV, polymerization.

By choosing a radiation in the UVA or in the UVB, the UV lamp according to the invention 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),

- for dermatological treatments (in particular, UVA radiation at 308 nm),

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 to reduce odors in a refrigerator or dirt.

By choosing radiation in the UVB, the UV lamp according to the invention serves to promote the formation of vitamin D on the skin.

By choosing radiation in the UVC, the UV lamp according to the invention 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 according to the invention is used in particular for the treatment of surfaces, in particular before deposition of active layers for the electronics. computing, optics, semiconductors ... The UV lamp according to the invention can be integrated, for example, in household electrical equipment such as a refrigerator or kitchen tablet.

It may further be advantageous to add in the lamp (UV) (at least) a coating having a given functionality, coating (s) on the outer face (s) of one or more walls. It could be :

a coating with a function of blocking infrared wavelength radiation, for example for electromagnetic compatibility,

and / or an anti-fouling coating (photocatalytic coating comprising at least partially crystallized TiO ₂ in anatase form)

and / or an antireflection stack of the type for example Si ₃ NVSiO ₂ ZSi ₃ NVSiO ₂ .

The polished surface plate and walls can also be supplied separately, sold as a kit and ready for assembly.

The invention thus also relates to the use of a perforated plate with a polished surface, especially chosen from a polished glass plate or a dielectric plate (glass, quartz, (ceramic) ceramic) with a base layer. of polished silica or polished enamel, in a field effect emission flat lamp, as an accelerating element for the electrons.

The invention thus also relates to the use of a discontinuous layer of polished enamel, in a plane lamp emission by field effect, as accelerator element of the electrons.

More generally, the invention also relates to the use of a perforated plate or a discontinuous enamel layer with a polished surface, especially chosen from a polished glass plate, a polished enamel layer, a dielectric plate with a polished silica layer or with a polished enamel layer, as an electron accelerating element in a field emission plain lamp. The invention also relates to a method for manufacturing a lamp as described above comprising the connection of the second wall and the perforated plate with polished surface and with openings opening on the face opposite to the free face, by a binding material - preferably (essentially) inorganic and electroconductive - forming at least partly metal catalyst and / or cathode This material is preferably deposited both on the inner face of the second wall and on the opposite face of the plate.

More precisely for the assembly, the following steps can be provided: the plate is bonded to the second wall;

spacers are deposited on the perforated plate,

the first wall and the perforated plate, optionally with a polished surface, are assembled in parallel,

the inner space is sealed by means of a peripheral sealing material of the first wall and the plate or on the second wall.

In all the configurations of lamps according to the invention (plate spaced from the second wall, glued to the second wall, forming the second wall), it is possible for the vacuum to provide the following steps: - replace, via a hole made in the one of the walls, the atmosphere contained in the internal space by a vacuum preferably secondary,

- obstruct the hole with a sealing means.

In the case of a plate forming the second wall, the vacuum hole can be formed at the same time as the blind holes.

To replace the atmosphere with the gas, it is possible to use a method of pumping through a double or multiple glazing structure as described in particular in document EP-A-645 516. It proposes as a sealing material a glass suspension. sintered solder. This material is placed in the form of a ball at the outer end of the hole from the beginning of manufacture, evacuated through this piece, then softened so as to obstruct the hole.

Another method is described in FR-A-2 774 373, where a low-melting alloy is proposed as a sealing material. This material can be placed in the form of a piece of shape adapted to the outer end of the hole from the beginning of manufacture, it is evacuated through this piece, and then melted to seal it on the wall of the hole. way to obstruct the latter.

A preferred method according to the invention is to obstruct the hole with a sealing pellet covering the outer hole of the hole. This pellet, advantageously metallic, can be glued to the wall by welding. Furthermore, preferably, the electron-emitting material is deposited on the internal face of the second wall through the openings opening on the face opposite to the free face of the plate, the plate placed on the internal face or preferably already tied to the inner face. The method of manufacturing the lamp according to the invention is preferably such that it comprises successively:

the deposit on the cathode on the internal face of the second wall, in a discontinuous manner, of a layer based on a glass frit, particularly by ink jet or screen printing, the firing to form the enamel layer ,

a poling step of the enamel layer.

Other details and characteristics of the invention will appear from the detailed description which follows, made with reference to the appended drawings in which: FIG. 1 represents a schematic side sectional view of a plane field effect lamp emitting in the visible in a first embodiment;

FIG. 2 is a schematic view from above of the glass plate holed on the glass sheet with an electron emitting material used in the first embodiment illustrated in FIG. 1;

FIG. 3 is a diagrammatic side sectional view of a visible field-effect flat-field lamp in a second embodiment; FIG. 3bis is a schematic partial side sectional view of a field-effect flat lamp emitting in the visible in a variant of the second embodiment;

FIG. 4 represents a schematic view from above of the glass plate holed on the glass sheet with an electron-emitting material used in the second embodiment illustrated in FIG. 3;

FIG. 5 is a schematic top view of a glass plate pierced in pieces on a glass sheet with an electron-emitting material in another embodiment of the invention; Fig. 6 is a schematic side sectional view of a field-emitting, field-effect flat lamp in a third embodiment;

FIG. 7a is a schematic view from above of the glass plate holed on the glass sheet with an electron emitting material used in the third embodiment illustrated in FIG. 6 and FIG. 7b is a variant thereof;

Fig. 8 is a schematic side sectional view of a field-emitting, field-effect flat lamp in a fourth embodiment.

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 field effect lamp 100 comprising two walls composed respectively of first and second glass sheets 1, 2 for example silicosodocalcic of approximately 3.15 mm thick, having an internal main face 11, 21 and an outer main face 12, 22.

In an internal space 10 between the glass sheets 1, 2 reigns a vacuum preferably secondary. First, the inner face 11 carries a conductive coating 3 forming an anode and a coating of cathodoluminescent material 5 for example one or phosphores to produce a white light.

The anode 3 is directly deposited on the inner face 11 or on a barrier sub-layer, for example made of silicon nitride (not shown). The anode 3 is for example a silkscreened silver layer arranged to be generally transparent, for example a grid, or a (full) transparent electroconductive layer such as a multilayer to silver.

Alternatively, the anode 3 can be associated with the first sheet 1 in different ways: it can be deposited on the outer or inner face of an electrical insulating carrier element, this carrier element being assembled to the first sheet so that the This element may for example be a plastic film of the EVA or PVB type or a plurality of plastic films, for example made of PET, PVB and PU.

The anode 3 can also be in the form of a metal grid integrated in a plastic film or even in the first sheet then forming a reinforced glass or even in the form of son parallel to each other.

The cathode 3 may also be sandwiched between a first electrical insulator and a second electrical insulator, the assembly being assembled to the first sheet 1. The anode may for example be interposed between two plastic sheets.

Another combination of electrical insulators is as follows: a sheet of PVB is taken as the first electrical insulator which will be used to bond the second electrical insulator and carrier of the anode such as a PET sheet, the anode being between the sheet of PVB and the PET sheet. The inner face 21 carries a conductive coating 4 forming the cathode 4.

The cathode 4 is preferably directly deposited on the inner face 21 of the second sheet. The anode 4 is for example a (full) layer based on NiCr, typically 50 to 100 nm thick. On the inner face 21 of the second plate 2, is integral with a perforated silicosodocalcic glass plate 6, for example about 0.7 mm thick. This plate 6 is provided with a so-called free or upper main face 61 (face facing the first wall) and a so-called lower main face (facing the second wall) 62. The perforated plate 6 and the second wall 2 are secured by the cathode 4 which is solder material. Alternatively, it can provide a bonding (peripheral or distributed on the surface) for example with a sealing frit.

The openings 63 of the plate open from the main faces 61, 62 and are uniformly distributed over the surface of the plate. The openings 63 are, for example, an array of staggered rectangular patterns, about 1 mm wide and spaced about 1 mm apart, as shown in FIG.

The upper face 61 is covered with an electroconductive layer 7 forming an accelerating electrode, for example a silkscreened silver layer, optionally arranged in a grid. The electroconductive layer 7 may also be an enamel layer comprising a vitreous binder and conductive metal charges (for example silver particles), typically with a thickness of between 10 and 15 microns. It can also be a thin layer, for example indium tin oxide (ITO), fluorine doped tin oxide (SnO ₂ : F), aluminum doped zinc oxide. (ZnO: AI), made of metal such as silver or molybdenum, deposited by conventional techniques (PVD, CVD).

By way of example, a solid glass plate 6 may be coated by a cathodic sputtering process of an electroconductive layer 7 made of indium tin oxide and then pierced by the face opposite to the layer 7 by a technique such as sanding, laser cutting (possibly assisted by hydrofluoric acid) or water jet to form openings 63.

The inner face 21 further comprises carbon nanotubes 8 deposited through the openings on the cathode 4 also forming growth catalyst of these nanotubes.

The anode 3 is connected to a power supply source, for example via a flexible foil, and an external supply structure 33 is formed, for example made of silkscreened silver enamel. The anode 3 is at a continuous potential Vl of the order of 1000 V to 3000 V. For electrical protection, a transparent electroconductive layer 3 ', for example a conductive oxide, is grounded (V4 is equal to 0 V) is present on the outer face 12 of the first wall. A feed structure 33 ', for example enameled with silkscreened silver, is formed for this layer 3'. In addition, the first wall is laminated with a PVB 13 against a glass l '.

The cathode 4 is electrically powered via a flexible foil, and a sealing external supply structure 43 is formed, for example in screen printed silver enamel. To do this, the plate 6 may be slightly set back from the second plate 2. The cathode 4 is at a DC potential V2 preferably equal to 0 V (grounded).

The accelerating electrode 7 is electrically powered, for example via a flexible foil, and an external supply structure 73, for example enameled with silkscreened silver, is formed. It is at a continuous potential V3 between 100 V and 800 V. The first wall 1 and the perforated plate 6 are associated with facing their faces 11, 61 and are assembled by means of a sealing frit 9. The sealing is thus preferably chosen mineral.

The spacing between the latter 1, 6 may be imposed (at a value generally less than 5 mm) by glass spacers 10 'arranged (preferably homogeneously) between them. Here, the spacing is of the order from 0.3 to 5 mm, for example from 0.4 to 2 mm.

The spacers 10 'may have a spherical shape, cylindrical, cubic or other polygonal cross-section for example cruciform. The spacers may be coated with a phosphor identical to or different from the luminophore 5.

Alternatively, it is possible to use a peripheral spacer frame (thus at the edge of the plate) and possibly spacers in the center.

For the evacuation, the first wall 1 has near the periphery a hole (not shown) throughout its thickness, a few millimeters in diameter whose outer orifice is obstructed by a sealing pellet (not shown) including copper welded on the outer face.

The spacers 10 'are deposited and glued at predefined locations, for example by means of an automaton, and the wall 1 and the plate 6 are compared. The sealing frit is then deposited and sealed at a high temperature.

The atmosphere contained in the sealed enclosure is then removed by means of a pump through the sealing hole. When the secondary vacuum is reached, the sealing pellet is presented in front of the opening of the sealing hole, around which a bead of solder alloy has been deposited. A heat source is activated near the weld so as to cause softening of the weld, the wafer is gravitational plate against the orifice of the hole and is thus welded to the substrate 1 forming a hermetic plug. The cathodoluminescent material can produce a uniform, white light. This material 5 can advantageously be selected or adapted to determine the color of the lighting in a wide range of colors.

For decorative lighting, it is possible to form light areas of different colors, and / or shapes and / or sizes, an alternation of illuminated area (s) and dark areas.

It is also possible to vary the light intensities for example by varying the thicknesses of cathodoluminescent material.

In a first variant not shown, the accelerating electrode may be a polished silica layer or a polished enamel layer typically of thickness between 10 and 15 microns. In a second variant not shown, the plate is replaced by a dielectric layer of enamel, typically of thickness between

10 and 15 micrometers, on which is deposited an electroconductive layer of conductive enamel, typically of thickness between 10 and 15 microns. For example, it is possible to make deposits by screen printing.

The first enamel layer can be fired before the second enamel layer is deposited. Alternatively, the first enamel layer can only be dried before the deposition of the second enamel layer, the two layers then being subjected together to the baking treatment. In the embodiment of Figure 3, the structure 200 of the lamp basically takes the structure of Figure 1 apart:

- the accelerating electrode and its power supply are removed,

the plate 6 'is polished forming a remanent field 70 at the surface (as shown in the detail view of FIG. 3),

the openings 63 'are a network of rectangular patterns in rows and columns (see FIG. 4),

- the lamination and the protective conductor are eventually removed. The chemical weight composition of the glass of the plate 6 ', of the aluminoborosilicate type devoid of alkaline oxides, is the following (in percents):

This type of composition has the advantage of having a lifetime of the remnant field greater than 2 years.

In a variant shown in Figure 3a, which is a partial sectional view of the lamp 200 ', the polished plate is replaced by a polished enamel layer 6 "typically of thickness between 10 and 15 micrometers. act for example of an enamel obtained from a lead-free glass frit marketed by Ferro under the reference VN 821. The frit is mixed with a medium and then deposited by screen printing or inkjet before baking. The poling creating a remanent electric field 70 "may be substantially the entire thickness of the layer or surface.

Optionally, also shown schematically in FIG. 3bis, the carbon nanotubes are also replaced by 8 "ZnO nanowires deposited on the cathode.

The poling is carried out by heating the glass or enamel at 300 ^° C. and subjecting it to a static electric field of 3 kV. To do this the glass substrate or the enamel is kept in contact between two metal electrodes. The surface remanent electric field is of the order of 0.9 GV / m, measured using the static electricity measuring device marketed under the reference JCI 140 CF by John Chubb Instrumentation. The depth of the superficial zone, seat of the residual field, is estimated by Secondary Ion Mass Spectrometry (SIMS). This technique makes it possible to detect a very strong local depletion of calcium, on a surface area of about 10 micrometers.

In an alternative embodiment shown in Figure 5, the polished plate is discontinuous, in the form of plate pieces 6 distributed on the surface, the openings 63 then being continuous. The area delimited by the pieces of plate is inscribed in the internal space. The seal is made between the first and second walls.

In the embodiment of FIG. 6, the structure 300 of the lamp basically takes up the structure of FIG. 3 apart from: - the plate 2 'is made of silicosodocalcic glass with blind holes

23 'and forms the second wall 2',

the plate 2 'is coated on an internal surface 21 with a silica-based layer 60, deposited by spraying and then polished to form the remanent field 70' (as shown in the detail view of FIG. 6), - the openings blinds 23 'are in the form of parallel grooves emerging on a lateral edge of the second wall itself hollowed out 23,

the cathode 4 is discontinuous, being present in the bottom of the blind openings 23 'and on the hollow side edge 23 of electrical connection (see FIG. 7a) of the cathode 4, edge surmounted by the bus bar 43,

- The seal 9 is formed between the inner face of the second wall and the inner face of the first wall (with separate joint heights in the hollowed-edge region of connection and the other peripheral areas).

The layer 60 may also be a polished enamel layer, especially whose thickness is typically between 10 and 15 microns. It may be for example an enamel obtained from a lead-free glass frit marketed by Ferro under the reference VN 821. The frit is mixed with a medium and then deposited by screen printing or inkjet before cooking. Poling is typically performed by heating the sample at 300 ^° C. for 80 minutes under an electric field of 1 kV.

As an alternative assembly shown in Figure 7b, the entire periphery of the plate 2 'is recessed to keep the same height of sealing. In the embodiment of Figure 8, the structure 400 of the lamp basically takes the structure of Figure 3 apart:

the carbon nanotubes are replaced (in whole or in part) by 8 'tungsten microtips,

the cathode 4 'is transparent, for example a conductive oxide layer,

the plate 6 'is in the internal space, of smaller dimension than the second wall, the sealing is between the two walls 1, 2,

the plate 6 'is secured to the second wall 2 by a frit-glass type sintering frit 40, present at the periphery, the spacing between the openings 63 is at least twice the width of the openings 63 (the drawing n' being not to scale). By choosing the spacing of the openings, the cathode material 4 and peripheral sealing, this lamp produces a more bi directional illumination (thus on both sides of the lamp), and which can remain differentiated (as symbolized by the distinct width arrows).

The examples which have just been described in no way limit the invention.

All asymmetries and assembly variants are possible both for openings (blind or open, of any possible shape), for the electrodes (choice of material, shape), or the sealing or the possible connection between plate and second wall.

The light areas can also form a network of geometric patterns (lines, pads, rounds, squares or any other shape) and the spacings between patterns and / or pattern sizes can be variable.

As a variant, UV lamps are produced by choosing a catholuminescent and a first wall (or even a second wall) of suitable materials.

Claims

1. A field-emission flat lamp transmitting a radiation in the visible and / or the ultraviolet (100 to 400) comprising: - first and second dielectric walls (1, 2, 2 ') plane opposite and with main surfaces held parallel and spaced apart, the lamp being sealed at the periphery (9), thus delimiting an internal space (10) under vacuum,

a first electrode (3), called anode, extending in a plane parallel to the main surfaces and associated with the first wall (1), the first wall and anode assembly being transparent or generally transparent in the visible and / or UV,

a luminophor material emitting visible radiation (5) and / or ultraviolet (UV) by electron bombardment, the material being on the inner face (11) of the first wall and being closer to the internal space than the anode,

a second electrode (4), called a cathode, extending in a plane parallel to the main surfaces, a material emitting said electrons (8, 8 ', 8 ") having a shape factor greater than 10, the material being on the cathode, an electron accelerating element interposed between the first and second walls, spaced from the first wall, extending in a plane substantially parallel to the main surfaces and with a plurality of openings allowing said electrons to pass, characterized in that said element electron accelerator comprises an essentially mineral (6,6 ', 2') and perforated dielectric plate and / or a discontinuous enamel-based dielectric layer (6 "), the apertures being open (63, 63 ', 23') on at least the so-called free main face (61) of the plate facing the inner face (11) of the first wall, and in that, for said electron bombardment, said perforated plate (6) or said layer is Continuous enamel base (6 ") carries on its free face (61) a third electrode (7), forming an accelerating electrode, or the perforated plate (6 ', 2') or the discontinuous layer based on enamel (6 ") has a polished surface (60), thereby creating a remanent electric field (70, 70 ', 70") accelerating electrons, and in that the cathode is on the inner face (21) of the second wall (2) and / or, when the openings (23 ') of the perforated plate are selected blind, in the bottom of the openings of the plate (2). ').

2. Plane lamp (100 to 400) according to claim 1 characterized in that the plate (6, 6 ', 2') is based on a material selected from a ceramic, a glass-ceramic, a glass.

3. Plane lamp (100 to 400) according to one of the preceding claims characterized in that the walls (1, 2, 2 ') are glass sheets, in particular silicodio-calcium, or quartz.

4. Plane lamp (100 to 300) according to one of the preceding claims, characterized in that the seal, preferably by at least one mineral seal, is formed between the free face (62) of the plate (6, 6). ') and the inner face of the first wall (21).

5. Planar lamp according to one of the preceding claims characterized in that the perforated plate is spaced from the second wall and openings are open on the face opposite to the free face.

6. Planar lamp (300) according to one of claims 1 to 4 characterized in that the second wall (2 ') consists of the perforated plate (2') with the blind openings (23 '), preferably opening on a edge of the second wall, and the cathode, is in the bottom of the openings, in the form of an electroconductive layer, and electrically powered (43) by said preferably hollow edge (23).

7. Plane lamp (100, 200, 400) according to one of claims 1 to 4 characterized in that the face (62) of the plate opposite the free face (61) is integral with the inner face (21) of the second wall (2) by a connection means (4, 40), preferably a mineral one, in particular a glass frit (40), a solder (4), a weld, an anodic seal.

8. plane lamp (100, 200, 400) according to the preceding claim characterized in that openings are open on the opposite face (62) to the free face (61), and the inner face (21) of the second wall comprises an outer electroconductive layer (4) of a connecting material between the second wall and the perforated plate, and electroconductive to at least partly form the cathode and / or a growth catalyst of the emitting material (8) in a layer.

9. Lamp plane (100, 200, 400) according to the preceding claim characterized in that the outer peripheral layer (4), which is preferably a monolayer directly on the inner face, is a material selected from nickel, chromium , iron, cobalt and mixtures thereof.

10. Plane lamp (100 to 300) according to one of the preceding claims characterized in that the emitter material (8) is based on carbon, especially in the form of nanotubes.

11. Lamp plane (400) according to one of claims 1 to 9 characterized in that the emitting material comprises metal tips (8 '), including tungsten, micron scale or submicron.

12. Plane lamp (200 ') according to one of claims 1 to 9 characterized in that the emitting material is based on zinc oxide nanowires (8 ").

13. Lamp plane (100) according to one of the preceding claims characterized in that the accelerating electrode (7) on the perforated plate comprises an electroconductive layer, in particular metal, and preferably is on a sub-layer including a layer based silica or silicon nitride.

14. Lamp plane (300) according to one of the preceding claims characterized in that the plate (2 '), optionally polished, is coated with a polished silica base layer (60) or polished enamel.

15. Plane lamp (100 to 300) according to one of the preceding claims characterized in that the cathode (4) comprises a metallic electroconductive layer (4) forming a growth catalyst of the emitting material (8) in a layer, in particular a material selected from nickel, chromium, iron, cobalt and mixtures thereof.

16. Lamp plane (100 to 400) according to one of the preceding claims characterized in that the anode (3) is on the inner face (11) of the first wall in the form of a transparent electroconductive layer or a discontinuous metal layer, in particular arranged in a grid, and preferably the anode is on a barrier sub-layer including a layer of silica or silicon nitride.

17. Plane lamp (100 to 400) according to one of the preceding claims, characterized in that the anode (3) is supplied with a positive DC potential (V1), the cathode (4) is grounded (V2). , and in that optionally comprises an electrical protection element (3 ') associated with the outer face (12) of the first wall which is either a transparent and grounded electroconductive layer (V4) or a transparent dielectric.

18. Planar lamp (400) according to one of the preceding claims characterized in that the side of the second wall, the overall transmission in the visible and / or UV is greater than or equal to 50%, and the area surface (s) issuer (s) being preferably less than or equal to 50% of the inner surface of the lamp.

19. Plane lamp (100 to 400) according to one of the preceding claims, characterized in that the lamp emitting in the visible forms a decorative or architectural element, an element with a display function, such as especially planar luminaires, walls especially luminous suspended, bright slabs, backlighting of display screens.

20. Planar lamp (100 to 400) according to one of the preceding claims, characterized in that the lamp emitting in the visible forms a part of illuminating window of building or illuminating window of means of locomotion terrestrial, aerial or maritime an illuminating roof means of locomotion, an internal partition between rooms or between two compartments of means of locomotion terrestrial, aerial or maritime, a window, a piece of street furniture, a front of furniture, a refrigerator shelf, or in that the lamp UV is used for aesthetics, as a tanning lamp, biomedical, electronics or for food, for the decontamination of tap water, swimming pool drinking water, air, UV drying, polymerization .

21. Use of a perforated plate (2 ', 6') or a layer of discontinuous enamel (6 ") with a polished surface, especially chosen from a polished glass plate (2 ', 6'), a polished enamel layer (6 "), a dielectric plate with a polished silica base layer (60) or with a polished enamel layer, as an electron accelerating element in a field effect emission flat lamp (200) at 400).

22. A method of manufacturing the lamp (100, 200, 400) according to one of claims 1 to 20 comprising the connection of the second wall (2) and the perforated plate (6, 6 ') which has openings opening on the face opposed (61) to the free face (62) by a connecting material at least partly forming a catalyst of the layer emitting material and / or the cathode.

23. A method of manufacturing the lamp (100, 200, 400) according to the preceding claim characterized in that the connecting material is deposited on the inner face of the second wall and on said opposite face of the plate.

24. A method of manufacturing the lamp (100, 200, 400) according to one of claims 22 to 23 characterized in that one carries out the deposition of the electron emitting material (8) on the inner face of the second wall through openings opening on the opposite side to the free face of the plate.

25. A method of manufacturing the lamp (200 ') according to one of claims 1 to 20 characterized in that it comprises successively: - the deposit on the cathode on the inner face of the second wall, discontinuously, d a layer based on sintered glass, particularly by inkjet or screen printing,

baking to form the enamel layer (6 "),

a poling step of the enamel layer (6 ").