Glass ceramic article with colored luminous display

Abstract

The invention relates to an article exhibiting at least one colored luminous zone, in particular a display, the article comprises at least one glass ceramic substrate having a light transmission of from 0.8% to 40% and an optical transmission of at least 0.1% for at least one wavelength comprised in the range of from 420 to 780 nm, at least one light source and at least one inkjet filter having a thickness comprised between 1 and 50 [mu] m, in this way, at least one colored light-emitting region, in particular a display, is formed in at least one region of the glass-ceramic substrate.

Description

Technical Field

[0001] The present invention relates to the field of glass ceramics. More precisely, it relates to articles (or products) made of glass ceramics, especially glass ceramic plates, which are especially used to cover or accommodate some heating elements, and the articles are equipped with a colored luminous display (or at least one colored luminous area) at at least one selected area of ​​the article. Background Art

[0002] The sales of articles such as cooking plates made of glass ceramic have been growing steadily since recent years. This success is explained in particular by the attractive aspect of these plates and by the ease with which they can be cleaned.

[0003] It is important to note that glass ceramics are initially a glass, called precursor glass (or mother glass or green glass), whose specific chemical composition enables controlled crystallization to occur through a suitable heat treatment (called ceramization). This specific structure of partial crystallization gives glass ceramics some unique properties.

[0004] There are in fact different types of plates made of glass-ceramic, each variant being the result of significant research and numerous experiments, taking into account that it is very difficult to make modifications on these plates and / or in their method of obtaining without risking adverse effects on the properties sought: in order to be able to be used as a cooking plate, a glass-ceramic plate should generally exhibit a transmission in the wavelengths of the visible range, which at the same time should be low enough to mask at least a portion of the stopped heating element placed underneath and high enough so that, depending on the situation (heating by radiation, heating by induction, etc.), the user can visually detect that the heating element is in operation for safety reasons; it should also exhibit a high transmission in the wavelengths of the infrared range, in particular in the case of plates for radiant cookers.

[0005] Most of the actual plates are dark, especially black, which is colored, for example, by using vanadium oxides of the initial materials added to the mother glass before melting, which give a lasting orange-brown hue associated with the reduction of vanadium after ceramicization. Other colorants, such as oxides of cobalt and manganese, can also be used. With a low transmittance below 600nm, these plates especially enable the visibility of red elements, such as heating elements reaching high temperatures or luminous displays based on red monochromatic electroluminescent diodes. There are also more transparent glass ceramic plates (such as KeraVision or KeraResin glass ceramics commercialized by EuroKera) that enable other "pure" colors (produced by monochromatic diodes), such as blue or green.

[0006] However, recently there has been a need to be able to visualize a greater variety of displays with a greater variety of colors, in particular by means of synthetic colors produced by mixing multiple wavelengths (in the case of white). The transmission coefficient of glass ceramic plates is not uniform over the entire visible spectrum, the relative amplitudes of the different (spectral) components of the transmitted light are generally modified therein, and the color after transmission can deviate strongly from the color produced by the source.

[0007] In particular, the technology based on electroluminescent diodes (LEDs) that is usually adopted to produce white light (for example using a blue light source covered with a phosphor that absorbs part of the light and re-emits yellow light) cannot be used to produce white through glass ceramics. While the balance between blue and yellow is initially such that their mixture gives the visual sensation of white, since through glass ceramics the absorption is not homogeneous (blue is strongly absorbed, yellow less), through glass ceramics the eye no longer perceives white, but rather, for example, rose, orange or red.

[0008] Likewise, the use of LEDs emitting multiple colors (e.g. formed by three monochromatic sources whose intensities are adjusted in an independent manner, such as an LED of the "RGB" type with three sources (red, green and blue)) in order to give, for example, white is not appropriate, the inhomogeneous absorption of the glass ceramic over the visible range unbalances the balance between the colors and likewise produces a rosy, orange or red appearance. The respective intensities of the RGB components can be adjusted, but the mixing should be perfect (especially spatially - good coverage of the light beam - and temporally - especially the same phase of a possible amplitude modulation of the beam) otherwise there are inhomogeneities; the spacing of the three emission zones is often the cause of a bad mixing, resulting in uneven colors. Likewise, the three R, G and B chips are subject to different aging and thermal drifts, so that colorimetric inhomogeneities appear over time. Depending on the manufacturing batches of the red, green and blue LEDs, color differences of the RGB LEDs from one another are also observed. RGB LEDs are also more bulky than the LEDs usually used for displays and more difficult to integrate on control panels.

[0009] For these reasons, the display of white or of most colors other than red, in particular of synthetic colors, does not exist in glass ceramics, which are particularly dark or colored, because due to their inhomogeneous absorption in the visible range, non-monochromatic light passing through it sees its color modified, which is all the more critical the wider its spectrum (such as for white sources). Summary of the invention

[0010] The object of the present invention is therefore to provide new and improved glass-ceramic articles (such as plates), in particular new glass-ceramic articles that are described as follows: they present a more diverse colored luminous display, in particular in addition to red and in particular white, which display does not present the disadvantages listed above, provides a wide range of precise colors, and is particularly suitable for dark and / or very absorbent and / or inherently colored plates. More particularly, the present invention has sought a solution that is easily suitable or applicable to all types of glass-ceramics (smooth or with picots or protrusions, clear or dark, colored or not, etc.), which solution makes it possible to obtain one or more zones of (multiple) selected colors, the colors obtained are uniform, the solution is moreover simple to implement and compatible with the manufacturing method of glass-ceramics and the constraints of their use.

[0011] This object is achieved by a novel article according to the invention, presenting at least one colored (in a broad sense also including white) luminous area (in particular a display), comprising: at least one glass-ceramic substrate (in particular a plate, which is used, for example, to cover or accommodate at least one heating element), the glass-ceramic substrate having a light transmission of from 0.8% to 40% and an optical transmission of at least 0.1% for at least one wavelength comprised in the range from 420 to 780 nm (in the visible range); at least one light source (and / or a display in which said source is integrated) and a thickness of Comprising at least one inkjet filter between 1 and 50 μm (which is (functionally) coupled to the source (also coupled to the plate, in particular resulting from the obtained colored area (the action / effect) of these three components)), so that at least one luminous area is formed, in particular on at least one area of ​​the glass-ceramic substrate, in particular a display (for example visualization of data / signals or decorative patterns), which is colored. As explained below, the filter can be combined (in terms of positioning) in particular to the source and / or the glass-ceramic substrate and / or an intermediate element (for example an extraction device), and is preferably connected to the glass-ceramic substrate.

[0012] By "inkjet filter" is understood an optical filter (acting on the transmission of light), in particular a color filter (acting on the transmission of wavelengths as a function of wavelength), printed (or applied) by inkjet (or obtained by inkjet printing), the filter in particular in the form of a film or layer, in particular based on at least one ink (which may include one or more organic and / or inorganic and / or mineral materials), and (semi-) transparent (in particular in the sense that it is transparent for certain (multiple) visible wavelengths and opaque / blocks / affects (multiple) other wavelengths, the filter furthermore generally exhibiting a light transmission of at least 5%, in particular at least 20%, and in particular at least 30%), in particular enabling absorption and / or reflection and / or re-emission of certain wavelengths of the visible spectrum. In a particularly advantageous manner, the filter is an absorbing filter (acting on the transmission of light by absorption of certain wavelengths, the absorbed light in particular being converted into heat and / or emitted at other wavelengths). It can be applied or printed on a glass ceramic substrate and / or on at least one light source and / or on an intermediate element, as explained below. At least one light source is (functionally) coupled to at least one such correction filter (that is to say the radiation it emits passes through said filter) in order to produce the sought display through the glass-ceramic substrate to which the assembly is combined.

[0013] The aforementioned filter is selected according to (or is suitable for or depends on) the glass ceramic (in the case of the optical transmission, or spectral transmission or spectral dispersion of the glass ceramic substrate, the optical / spectral transmission itself depends on the thickness and composition of the substrate) and possibly according to the light source, as explained below, so as to form at least one colored luminescent area with fixed colorimetric coordinates, in particular a colored area other than red, and in particular white or a colored area of ​​a synthetic color obtained by mixing multiple wavelengths.

[0014] The present invention demonstrates that the choice of a glass-ceramic (which is dark if necessary) presenting the optics and light transmission mentioned according to the invention, and its combination with filters selected as required, as described above, in order to compensate or correct the spectral dispersion of the glass-ceramic in a controlled manner, makes it possible to obtain the desired appearance of color, regardless of the initial spectrum of the light source seen through the glass-ceramic, without being restricted by the choice of the light source, nor by complex transformations of the light source or the glass-ceramic. The present invention further demonstrates that the use of inkjet filters with a thickness comprised between 1 and 50 μm makes it possible to advantageously obtain the improved glass-ceramic article sought, without the defects or disadvantages that can be observed in the case of other types of filters.

[0015] The filter selected according to the glass ceramic and possibly according to the source (according to the purpose sought as explained below) makes it possible to obtain the desired transmission of the filter / glass ceramic as a whole (with color correction or to obtain a neutral transmission, that is to say without modifying the original color of the source). The invention is particularly suitable for dark or colored glass ceramic panels, which meet the transmission criteria, and is equipped with the function of controlled coloring of the display. It makes it possible to achieve a given target color for a source of a given color and in particular to realize a display / display produced by a color that is the same or different from the original color, in particular white or a color that is new for the glass ceramic as a result. The invention also makes it possible to produce coloring areas that vary on the glass ceramic, by associating, for example, a specific coloring with a space or a function.

[0016] The invention also applies with the same advantages to planar glass-ceramic substrates as well as to those presenting non-planar surfaces or being equipped with irregularities, for example to glass-ceramic plates equipped with pointed teeth underneath, the inkjet filter according to the invention being able to conform to the irregular surfaces in question with a constant thickness, in contrast to other types of filters and / or those which are deposited with greater thickness.

[0017] For example, it has been shown that filters in the form of (multiple) polymer sheets do not make it possible to fit exactly to the surface of the tines, leaving empty spaces between these latter, which leads to different reflections between the glass ceramic and the filter, according to the positions located upright alongside the tines or between these latter. The path followed by the light is then not uniform over the entirety of the area equipped with the filter. The choice of filters deposited by screen printing makes it possible to eliminate these gaps and the resulting reflections, but on the contrary results in the thickness of the filter between the tines being greater than the thickness of the tines' peaks. Therefore, the light does not pass through filters of the same thickness over the entirety of the area concerned, which, if necessary (for example white display), leads to a net difference in the color produced between the peaks of the tines and the valleys of the tines. The application according to the invention by inkjet makes it possible to advantageously get rid of these two disadvantages (non-homogeneities of reflection and thickness) and to obtain a good uniformity of the color produced.

[0018] Furthermore, as explained below, the inkjet filter can advantageously be formed of a component that is heat-resistant to the temperatures to which the zone in question of the article according to the invention is subjected, for example to the temperatures to which a control panel of a glass-ceramic plate is exposed, in contrast to filters in the form of polymer sheets, which are less heat-resistant and should be deflected from the glass-ceramic in order not to be damaged, which increases the complexity of the filter implementation. The solution according to the invention is particularly simple to implement and durable.

[0019] Furthermore, once the spectrum of the filter enabling the desired color to be obtained has been determined, as explained below, there is not necessarily a polymer sheet (or combination of polymer sheets) that exhibits exactly this spectrum, which forces the selection of a filter that is closest to the target filter and forces a large number of different filters to be kept in stock. The target color cannot therefore be achieved in as precise a manner as desired. With such polymer filters, it is also not possible to finely adapt to the differences in the transmission spectrum of the glass ceramics caused by natural differences in the manufacturing process (such as differences in thickness and composition).

[0020] The selection of filters deposited by screen printing allows a better adjustment of the color by precise dosing of the amount of pigment for this type of filter, however, there are uncertainties in the weighing and this means preparing a specific solution for each manufacturing batch according to variations in the composition or thickness of the glass ceramic.

[0021] In the present invention, the adjustment of the colors is on the contrary particularly simple and precise. In particular, the filter is defined by the ratios between different colors, among which are generally basic or primary colors (such as cyan, magenta and yellow), for example by the ratios between cyan, magenta, yellow and black, and is advantageously obtained by the superposition of the (ink) deposition of each of the colors in the selected ratio (or ratio or proportion). It is then not necessary to prepare a solution with good ratios in advance; the ratios are simply entered into the press control software, for example, at the moment of printing. They can therefore be adjusted very easily according to the glass-ceramic batches used (thickness and composition are variable according to natural differences in the manufacturing method) so that a constant color produced across different batches of glass-ceramics is obtained under a given light source.

[0022] The article according to the invention can advantageously be a cooking plate, but can also be any other article made of glass-ceramic presenting a functional or decorative display, or even an article or module or assembly or system (having a main function) of a (decorative and / or functional) display having at least one light source coupled to at least one corrective filter, which is coupled to at least one glass-ceramic, in particular a plate, according to the invention.

[0023] By articles made of glass ceramics is understood not only articles made of glass ceramics but also articles made of any other similar material suitable for the same application (e.g. reinforced or unreinforced glass), which are particularly resistant to high temperatures and / or in particular exhibit zero or almost zero (e.g. less than 15.10 -7 K -1 , such as in the case of glass ceramic panels used in the case of radiant fire. Preferably, however, it is an object made specifically of glass ceramic.

[0024] Preferably, the article according to the invention is formed (as substrate) by a glass ceramic plate (thickness generally comprised between 3 and 4 mm, in particular about 4 mm), said glass ceramic plate being planar, or mostly or almost planar (in particular having a deflection from the diagonal of the plate of less than 0.1%, and preferably about zero), and said article according to the invention is intended for use as a cooking plate. Such a plate is generally intended to be integrated in a cooking or stovetop comprising said plate and some heating element, for example a halogen or radiant cooker or a heating element by induction.

[0025] The plate generally presents an "upper" face in the position of use (the visible face), another "lower" face in the position of use (often hidden, for example in the base or caisson of the stove), and a side edge (or side or thickness). The upper face is generally flat and smooth but may also present at least one raised area and / or at least one recessed area and / or at least one opening (for example if the plate incorporates an opening for accommodating a gas burner). The lower face may in particular be smooth or equipped with tines which increase its mechanical resistance and which are obtained, for example, by rolling. If necessary, in the case of tines, an index of resin may be applied to the lower face in order to smooth it, if necessary.

[0026] The article according to the invention is advantageously based on any glass-ceramic which intrinsically has a light transmission of from 0.8% to 40%, in particular from 2.3 to 40%, and an optical transmission of at least 0.1% for at least one wavelength included in the visible range, above 420 nm (and up to 780 nm) (determined in a known manner, making the ratio between the transmission intensity and the incident intensity at a given wavelength), and preferably for all wavelengths included in the range from 420 to 780 nm. By "intrinsic manner" it is understood that the plate itself possesses such a transmission, in the absence of any coating. Light transmission (T L) is measured according to the specification ISO 9050:2003 by using illumination D65 (also referred to as optical transmission), and is the total transmission (in particular integrated in the visible range and weighted by the sensitivity curve of the human eye), taking into account direct transmission and possible diffuse transmission, the measurement being carried out, for example, by means of a spectrophotometer equipped with an integrating sphere, the measurement for a given thickness then being converted, if necessary, into a reference thickness of 4 mm according to the specification ISO 9050:2003. The invention is particularly advantageously applicable to dark panels, in particular of black or brown appearance, which present such a transmission criterion, but the glass ceramic used presenting such a criterion can also be a clear glass ceramic, the solution according to the invention making it possible to obtain a luminous display of the exact color desired, with great flexibility of adaptation, for any panel of this range, in a simple manner and without the risk of altering other properties of the panel. DETAILED DESCRIPTION

[0027] In a first embodiment, the glass ceramic is particularly dark (in particular, L as calculated in the CIE colorimetric system from the transmission spectrum of the glass ceramic in the visible range). * A glass ceramic having a value of less than 70% (value less than 70%), which exhibits a light transmission in the visible range of 0.8% to 5%, in particular 0.8 to 2.5%, and an optical transmission of more than 0.1% for at least one wavelength in the visible range greater than 450 nm.

[0028] In another advantageous embodiment, the glass ceramic of the lithium aluminosilicate type exhibits (intrinsically) a light transmission of from 2.3% to 40%, in particular greater than 2.5%, in particular greater than 3.5%, and an optical transmission of at least 0.6% for at least one wavelength included in the range from 420 to 480 nm. In this case, whether the glass ceramic is clear or dark, it preferably exhibits at least one masking device intended to mask at least a portion of the underlying associated elements (in particular the heating device), if necessary, excluding the light emitter device / illumination zone and, if necessary, the heating device by radiation, the filter(s) being in this case essentially used in the unmasked luminous zone.

[0029] In particular, glass ceramics comprising the following components and / or obtained by ceramizing a glass from the following components (with the following limitations expressed in weight percentages) are advantageously used: SiO 2 :52-75%;Al 2 O 3 :18-27%;Li 2 O:2.5-5.5%; K 2 O: 0-3%; Na 2O: 0-3%; ZnO: 0-3.5%; MgO: 0-3%; CaO: 0-2.5%; BaO: 0-3.5%; SrO: 0-2%; TiO 2 :1.2-5.5%; ZrO 2 :0-3%;P 2 O 5 : 0-8%, and preferably, with the following limits expressed by weight percentage: SiO 2 :64-70%;Al 2 O 3 :18-21%; Li 2 O: 2.5-3.9%; K 2 O: 0-1.0%; Na 2 O: 0-1.0%; ZnO: 1.2-2.8%; MgO: 0.20-1.5%; CaO: 0-1%; BaO: 0-3%; SrO: 0-1.4%; TiO 2 :1.8-3.2%; ZrO 2 : 1.0-2.5%.

[0030] The glass ceramic may also include up to 1% by weight of non-essential components which do not affect the melting of the mother glass or lead to subsequent devitrification of the glass ceramic. In the case of black or brown glass ceramics, for example, colorants may be added to the composition. For example, the composition of the plate may advantageously include vanadium oxide in a ratio comprised between 0.01% and 0.2%, preferably less than or equal to 0.05%, or even less than or equal to 0.04%. The preferred content of vanadium oxide is comprised between 0.01 and 0.03%.

[0031] The glass ceramic may also contain the following other colorants (weight limit) for concealing the heating element and possibly in combination with vanadium oxide: Fe 2 O 3 : 0-0.2%; CoO: 0-1%, and preferably 0-0.12%, even NiO, CuO and / or MnO. The glass ceramic may also include tin oxide (or other reducing agents, such as metal sulfides) at a ratio of less than 0.5%, which promotes the reduction of vanadium during the ceramicization step, especially causing the appearance of color.

[0032] The preferred dark glass-ceramics according to the invention generally comprise crystals of a β-quartz structure in the residual glass phase and have an absolute value of a coefficient of expansion of advantageously less than or equal to 15.10. -7 / ℃, even less than or equal to 5.10 -7 / ℃.

[0033] As defined previously, the article according to the invention also comprises at least one light source, which may be continuous or discontinuous and, if necessary, a plurality of sources (whose number and their arrangement may vary for homogenizing the illumination). The source or sources may be integrated in / coupled to one or more display type structures (e.g. electroluminescent diodes called "7 segments" or liquid crystals), to an electronic control panel coupled to a touch-sensitive and digital display, etc. The light sources are preferably formed by electroluminescent diodes (or DELs or LEDs in English), which are more or less spaced apart, possibly associated to one or more light guides, as mentioned below. Diodes are advantageous in the invention in terms of, among other things, volume, efficiency, durability and tolerance to environmental conditions (heat, etc.).

[0034] The diode can be packaged, that is to say comprising a semiconductor component and an encapsulation (e.g. made of epoxy or nylon type resin) which encapsulates the semiconductor component. The diode can also be a semiconductor chip without a collimating lens, e.g. of the order of a hundred μm or mm in size, possibly with a micro-encapsulation (e.g. protection).

[0035] The diode can be carried by a support or barrette or base, which can present a surface (flat or inclined) that is treated and / or made reflective for better luminous efficiency, for example coated with a paint or coating and / or a mirror layer, and / or coupled to a white or metal reflector for better guiding the emitted radiation.

[0036] The assembly of the source or sources (with the plate or with another component of the article, such as a control panel, for example) can be carried out by welding, clipping, laminating, etc., if necessary via another element; for example, a diode can be mounted, which is welded on a carrier, which is itself placed on the bottom of a metal profile, by clipping or laminating the profile. The positioning of the source or sources (relative to the plate, in particular) is adapted to enable a display through the glass ceramic.

[0037] The sources, as well as their power supplies and actuators, may be dissociated or not so as to enable simultaneous or separate illumination of the desired illumination zones as desired. Each source may be monochromatic (pure color), or may be polychromatic, in particular in the case where a plurality of monochromatic sources are combined (e.g. LED RGB) for emitting a polychromatic spectrum (synthetic color). The present invention advantageously enables correction of the inhomogeneous absorption of the polychromatic spectrum of the one or more sources through the glass ceramic (e.g. for white LEDs), and is particularly suitable for articles using polychromatic emission sources (alone or in combination).

[0038] By "monochromatic light source" it is understood that the light source exhibits a single emission peak in the range of visible wavelengths and such as the width of the peak varies from 1 to 100 nm, preferably from 5 to 50 nm.

[0039] By "polychromatic light source" is understood a light source which exhibits at least two emission peaks of different wavelengths in the range of visible wavelengths. The color perceived (visually by the user) then results from the mixture between the different wavelengths. It may concern an LED, and / or a display of (multiple) LEDs, having an emission spectrum exhibiting a main emission peak and a further emission peak which is, for example, fluorescent, broader than the main peak and generally of lower intensity. A polychromatic LED emits in particular according to a first emission (strong or weak intensity) comprised between 400 and 500 nm and according to a second emission (strong or weak intensity) in the visible range beyond 500 nm (such as is the case with an LED formed by at least one electroluminescent crystal and (multiple) photoluminescent phosphors).

[0040] As a source, in particular a white LED can be used, which is manufactured, for example, from a semiconductor crystal chip, such as gallium / indium nitride (InGaN), which emits in blue, covered with a transparent resin (such as silicone or epoxy) containing an inorganic phosphor (for example YAG:CE), which absorbs blue and emits in yellow. As further examples of advantageous multicolor LEDs, in particular the following LEDs or displays can be cited: LED or "high brightness LED" series, Nichia's Nichia Helios, Nichia Rigel, "LED type lamp", NSSM, NSSW, NSEW, NS9 and NS2 series, OSRAM's white series and LW Q38E, LW L283 and LW Q38G reference numbers, Philips Lumileds' Rebel White" and K2" series, LEDs with reference numbers E1S19, E1S27, E1S62, E1S66, E1S67, E1SAG, E1SAP, EASAA, EASAU, EASAV, E1L4x and E1L5x from Toyoda Gosei, LEDs with reference numbers HSMW-C120, HSMW-C130, HSMW-C191, HSMW-C197 and HSMW-C265 from Avago Technologie, LEDs with reference numbers LTW-C193TS5 and LTW-C191TS5 from LITE-ON, LEDs with reference numbers WH104L-H, WH104-NZ and WH107 from Seoul Semiconductor, LEDs with reference numbers 19-213 / T1D-KS1T1B2 / 3T from Everlight, etc.

[0041] Examples of displays with LEDs include the white 7-segment displays with reference numbers HDSM-431W and HDSM-433W from Avago Technologies, or the white 7-segment displays with reference numbers FN1-0391W010JBW and FN1-0391W050JBW from FORGE EUROPA, the "Dot ” matrix display, for example: reference number TA20-11YWA; KingBright's "Bar Graph ” bar display, for example reference number DC10YWA. Note that a display with (multiple) LEDs is a light-emitting display device whose “primary” light source consists of (multiple) LEDs, and these devices are generally composed of light-emitting “segments” (for example, 7-segment displays), dots (matrix displays) or bars, a segment is generally formed by a reflector, the one or more LEDs are generally inserted into one end of the reflector, and the light is guided to the other end (apparent), the inner wall of the reflector can be diffuse and / or the apparent ends of the segments can be covered with a highly transparent plastic material.

[0042] As already mentioned, the article may comprise, in addition to the one or more sources, at least one waveguide intended to propagate light from one part of the article to another (in particular by total internal reflection or by metal reflection), the light source then being attached to a guide and cooperating therewith, so as to emit its light radiation into its interior for the guide to transmit it, the one or more light sources being emitted / coupled through, for example, the sides or flanks of the guide. The guide is advantageously clear or transparent (that is to say, presenting, in the case of the guide, a light transmission of at least 30%). L), and is generally added (assembled after having been separately designed) on the underside of the substrate. It can be organic and / or plastic (for example made of polycarbonate or polymethyl methacrylate PMMA), or inorganic, and preferably inorganic; in particular, it concerns glass. The article according to the invention can include a plurality of guides, each dedicated to one or more lighting zones, or an integral guide, which is optionally provided with an opening. The guides can be connected to the substrate by bonding and / or clamping, or by encapsulation, etc. The assembly of the guides can be carried out directly on the substrate, or on another part of the article or the carrier on which the article is assembled, for example in the case of a cooking module or device, the guides can be connected to the caisson of the cooking device on which the substrate is assembled (the caisson can, if necessary, constitute part of the article). Among other things, the guides make it possible to better conduct the light to the desired lighting zone, in particular when the substrate is of a dark color.

[0043] The article according to the invention may also comprise at least one means for extracting the radiation emitted by the one or more sources in the illumination zone, for example one or more diffusing elements or treatments, in particular extraction means, such as the addition of a layer on the surface and / or by any differentiated treatment or texturing of the surface (partially or over the entire surface) (of the waveguide if necessary), such as laser etching, enamel printing, chemical (acid, etc.) or mechanical (sandblasting, etc.) etching, etc. The extraction surface may also be prepared, for example, if necessary in the thickness of the guide, according to internal etching techniques, for example by laser. The one or more extraction means enable the radiation to be extracted from the guide towards the desired illumination zone. If necessary, the geometry and the roughness of the edge of the waveguide may also be processed so as to enable a controlled and local extraction of the light. The one or more extraction means may be combined, if necessary, with another treatment that enables the illumination zone to be targeted, for example with a screen-printed mask on the substrate (masking certain areas and preventing the passage of light).

[0044] As defined according to the invention, the claimed article further comprises at least one inkjet filter, which is generally placed between the source and the substrate (and in particular occupies a fixed position) and which may be coupled to (that is to say, fixed directly or indirectly (e.g. via another component) and simply not removable once placed) the source and / or the substrate, and / or possibly to another intermediate element (e.g. such as the aforementioned light extraction means), said intermediate element advantageously being transparent (that is to say, in the case of an intermediate element, presenting a light transmission T of at least 30%). L ), as explained below. Preferably, it is bonded to (or fixed to) the glass ceramic.

[0045] The filter is formed by depositing at least one layer of ink (or in the form of at least one layer of ink) by inkjet at selected places on the substrate and / or on the source and / or on an intermediate element between the substrate and the source in question. The inkjet technology enables (advantageously under computer control) direct deposition on different types of supports (even fragile (other layers)) of the article according to the invention, without contact and with only the necessary amount of ink. The liquid ink pressed through one or more capillaries separates into droplets, each droplet being, if necessary, electrically or magnetically projected and / or deflected during its projection towards the printing support. The printed image is then formed by numerous interlaced small ink spots. Printing can be carried out continuously or on demand, the thickness of the final layer corresponding to the inkjet filter obtained (formed by the droplets) being comprised according to the invention between 1 μm and 50 μm so as to enable the sought (filter) effect to be achieved while being compatible with the method for manufacturing the article according to the invention, in particular allowing efficient and rapid deposition and drying, the thickness of the inkjet filter obtained being preferably greater than 5 μm and less than 30 μm, and for example of the order of 10 to 20 μm.

[0046] The composition of the filter is determined so that it acts on or compensates the light transmission through the plate in a selected, controlled and reproducible manner (the filter presents a spectral dispersion different from that of the glass ceramic for this purpose). According to the invention, the filter is based on (multiple) inks, multiple inks of primary colors being advantageously superimposed for forming the layers constituting the filter. The ink can be chosen in particular from different kinds of common inks (pigmented or soluble colorant-based inks, water- or solvent-based inks, hot melt inks, photopolymerizable inks (or UV inks), etc.). In order to avoid clogging of the nozzles during printing of the filter, the ink is generally a polymer ink (or based on (multiple) polymers, which (these) polymers in particular form the medium mentioned below), the formulation of the ink however being able to include (simultaneously, for example as a colorant, or possibly alternatively) other types of components (metallic, ceramic, etc.), in particular in the form of nanoparticles, etc. The composition of the ink that can be used to obtain the filter according to the invention generally comprises a colorant or pigment (for example 1 to 10% by weight of the ink, in particular 1 to 5%), one or more media and / or one or more solvents (for example 35 to 90% by weight of the ink), and if necessary one or more additives (such as plasticizer(s), wetting agent(s), surfactant(s), pH or viscosity regulator(s), evaporation slowing agent(s), conductor(s), antimicrobial(s), antifungal(s), antioxidant(s), etc., in a ratio generally not exceeding 15% by weight). The pigments can be inorganic or organic, the colorants and / or pigments are especially dissolved or dispersed in the media and / or solvent of the ink, such as a resin of the silicone, epoxy, polyamide or acrylic type, a UV drying media, or an inorganic matrix of the sol-gel type, the solvent can be based on alcohol, methyl ethyl ketone, ethyl acetate, water, etc. Preferably, the one or more inks used are based on acrylic (or formed by an acrylic medium), such as based on acrylate(s), diacrylate(s), etc. In particular, these are inks that have soluble (or dissolved) colorants.

[0047] It is noted that the colored substances, in particular colorants or pigments, used to realize the aforementioned filters are preferably heat-resistant. For example, pigments of carbon black, phthalocyanines, lithocyanine red, diaryls, etc. can be advantageously used, which are used in particular by mixing and dispersed, for example, in a resin of styrene-acrylic or phenolic type. As indicated previously, the inks used are in particular UV-dried acrylic inks (or inks of acrylic medium), which are stable in temperature and to light, such as, for example, the ink commercialized by the company Agfa under the reference Anapurna M.

[0048] Advantageously, the size of the particles present in the ink or inks used to obtain the filter according to the invention is, if necessary, less than 1 μm and the sedimentation viscosity of the ink or inks is comprised between 5 and 15 mPa.s. Advantageously still, the surface tension / surface tension of the ink or inks is comprised between 15 and 50 mN / m.

[0049] Inkjet filters are generally filters by absorption, the absorption being controlled in particular by a compound of the colorant or pigment type, thereby advantageously enabling the selected effect or color to be obtained whatever the angle of incidence of observation.

[0050] The inkjet filter used according to the invention furthermore generally exhibits a light transmission of at least 5%, in particular at least 20% and in particular at least 30%.

[0051] As indicated before, the filter is realized by inkjet printing, in particular on a glass ceramic substrate and / or the source and / or the intermediate element, and is preferably bonded to the glass ceramic substrate.

[0052] If necessary, the adhesion of the ink to its support, in particular when the support is a glass material (in particular a glass ceramic substrate or source), is enhanced by prior treatment (in particular to the support) and / or by the addition of a composition or additive or suitable ingredients (for example in the composition of the ink and / or on the surface of the support). In particular and preferably, the support (or the part of the object to which the ink is applied / should receive the ink) is treated before the deposition of the ink, by depositing a chemical adhesion promoter (or a layer of accretion or primary structuring) and / or by non-chemical surface treatment (or preparation), in particular of the plasma type.

[0053] In a first embodiment, the surface of the support is prepared / treated beforehand by a plasma treatment (corona or preferably atmospheric plasma treatment).

[0054] In a second preferred embodiment of the invention, the adhesion of the ink to its carrier is enhanced by previously depositing between the ink and its carrier at least one climbing layer, in particular a layer of a suitable primary structure, and in particular a layer based on (multiple) silanes and / or (multiple) (poly)siloxanes, as described in detail below. It is also possible to combine a surface preparation treatment of the plasma type with the deposition of an adhesion promoter (for example one or more silanes applied by plasma).

[0055] As indicated previously and preferably, at least one layer of clinging or adhesion of the primary structure is present between the inkjet filter and the part of the article or the carrier on which the filter is applied. The primary structure can be applied in particular by rubbing (a fabric is dipped in the primary structure and said fabric is passed over the carrier, wherein the excess is possibly withdrawn (in particular by a new rubbing, wherein the fabric is for example soaked with the same solvent as the primary structure), leaving a primary film), coating on a roller or by sputtering (spraying), coating by centrifugation (spin coating), curtain, screen printing, or inkjet, or even plasma treatment, etc., the coating being generally carried out in a simple and effective manner by rubbing (or wiping on / off technique with the excess being withdrawn), and in particular carried out so that a primary monomolecular type layer (thickness of the order of one or several molecules) is left on the carrier (the excess being withdrawn if necessary).

[0056] The primary structure is formed in particular and advantageously from one or more compounds based on silanes (in particular mixtures of silanes), which are in particular functionalized, such as one or more aminosilanes and / or one or more methacrylate silanes (for example 3-(trimethoxysilyl)propyl methacrylate) and / or one or more epoxysilanes, which are generally dissolved (in particular aqueous or in a solvent such as, for example, isopropanol) before application. The primary structure can then be present in the form of a solution of (multiple) pure silanes. If necessary, the primary structure (in particular an aqueous solution of silanes) can also include other compounds, in particular be stabilized by the addition of other compounds (such as organometallic compounds in the case of aminosilanes). The primary structure can also or alternatively be formed from one or more compounds based on (poly)siloxanes (which are in particular functionalized).

[0057] The thickness of the filter (or of one or more layers forming the filter) applied to at least a portion of the article according to the invention (directly or indirectly by previously applying a primary structure as previously indicated) is comprised between 1 and 50 μm, the thickness of the possible primary structure being generally of the order of 1 or a few angstroms (in particular a monolayer as previously indicated).

[0058] After deposition of the ink or inks forming the filter according to the invention, the curing of said ink layer or layers can be carried out in different ways depending on the composition of the ink used, for example: at ambient temperature or by drying and / or heating (thermally, by infrared (IR) radiation or by ultraviolet (UV) etc., the great printing speeds and the nature of the support often dictate forced drying, the curing being carried out in particular by evaporation of the solvent, by polymerization of one of the components of the fluid, by oxidation (in particular by oxygen in the air), by absorption or penetration in the printed support (often activated by heat), by melting etc. Preferably, the curing is carried out by polymerization of at least one of the components of the ink, for example under the effect of ultraviolet radiation.

[0059] In order to obtain the sought target color (such as visually perceived) and / or the sought compensator effect (for example the case where a neutral transmission through the object is sought without changing the color of the source, whatever the source), the selection of the filter specifically suitable for each case depends, inter alia, on the glass-ceramic plate used, the sought color (and in this case the color of the source used) or the desired effect (in the case of neutral transmission whatever the source), and on the filters used.

[0060] In a first embodiment, if it is desired to perfectly compensate the transmission of the glass ceramic so that the glass ceramic / filter as a whole does not change the color of the source (neutral transmission, constant or approximately constant, for example with a variation of about 0.5% over the transmission range considered), the filter sought depends first of all on the glass ceramic and should function regardless of the light source used. It is therefore characterized as universal and capable of correcting the chromatic dispersion introduced by a glass ceramic of a given thickness and composition (especially in the form of a plate as in the present invention). The universal filter is selected so that the total optical transmission (transmitted light intensity over the light intensity emitted / incident by the source) through the filter+glass ceramic as a whole is T T (λ) (for each wavelength λ considered, the transmission is measured at normal incidence or at a more appropriate angle of incidence according to the selected conditions of use) is (equal to one) a constant in any considered spectral range (or for any (one or more) considered wavelengths). To this end, the minimum value T of the (optical) transmission of the glass-ceramic in the considered spectral range is determined. Vmin , and to find a filter (more precisely the composition of the filter, that is to say the relative amounts of inks suitable for obtaining said filter, for example cyan, magenta, yellow and black) which makes it possible to obtain a value equal to T Vmin The constant T T (λ) regardless of the wavelength of the spectral range under consideration, where the difference T T (λ)-T VminIt is almost preferred that the value does not exceed 0.1, and particularly preferably does not exceed 0.01 (in other words, minimizing T T (λ)-T Vmin ).

[0061] In general, the spectral range considered is the visible spectral range (all wavelengths included between 380 nm and 780 nm, in particular between 420 and 780 nm). The universal filter chosen makes it possible to preserve the color of the source whatever it is (transmission T T (λ) is the same for all visible wavelengths), only the intensity is changed (for T Vmin Alternatively, the spectral range may be more narrowed (for example between 420 and 600 nm), which allows a certain colorimetric dispersion (or deviation between the perceived color and the color of the source), but maximizes the final visual flux perceived, and in particular may be chosen to be restricted to the spectral range in which the human eye is most sensitive to the electromagnetic radiation received. For example, in the case where the spectral luminous efficiency V(λ) (defined by the International Commission on Illumination) enabling the expression of the luminous flux perceived by the human eye reaches its maximum value of 1 for a wavelength of 555 nm, the T considered Vmin The value of may be that measured at about 555 nm, or, as another example, in the case where V(λ) is greater than 0.5 from 510 nm to 610 nm (with photopic vision, that is, daytime vision), the T considered Vmin The value of may be that over the spectral range comprised between 510 nm and 610 nm.

[0062] According to T Vmin , it is thus possible to infer the transmission T of the filter being sought F (λ),T T (λ) depends on the filter transmission T, in particular according to the composition of the filter and its thickness. F (λ) and the transmittance T of glass ceramics V (λ) (In the simplest case, by especially neglecting reflections at interfaces, we first have the approximation T T (λ) = T F (λ)x T V (λ)). The filter is then implemented, for example, empirically, by successive trials to achieve the desired (transmission spectrum) T F (λ) (that is, it minimizes T T (λ)-T Vmin , for example, so that |T T (λ)-T Vmin|≤0.1, or by numerical / algorithmic optimization, etc., variables (of the filter) intervening in the transmission (e.g. concentration of the pigment, type of pigment, thickness of the filter, etc.), these filter-dependent variables are adjusted during this optimization.

[0063] In another embodiment or variant, when the light source is fixed (the filter is therefore optionally dependent on the glass ceramic and the source) and the attempt is made to find the original color of the source or a color close to it after transmission through the glass ceramic / filter ensemble, the spectral range considered (wherein T is determined in particular) Vmin ) is the emission range of the source. Alternatively, in the same manner as above, a certain amount of colorimetric dispersion may be allowed so as to maximize the perceived final visual flux, for example by selecting (the spacing of) one or more wavelengths in the emission range of the source so that the product F e (λ) x V(λ) is normalized to 1 (that is, for each wavelength, the F e The maximum value of (λ) x V(λ) divided by F e (λ)x V(λ), F normalized to 1 e All values ​​of (λ)xV(λ) are then included between 0 and 1), where Fe(λ) indicates the spectral density of the energy flux of the source for a given wavelength band, greater than 0.1.

[0064] In a third embodiment, when the light source is fixed, the filter can be determined so that after transmission through the glass ceramic / filter assembly a target color different from the initial color of the source is obtained. Vmin Instead, the colorimetric coordinates (x c ,y c ) and seek a filter that makes it possible to obtain the energy flux T emitted by the source / filter / glass-ceramic whole T (λ)xF e (λ) associated colorimetric coordinates (x, y), so that the value d = ((x c ) 2 +(yy c ) 2 ) 1 / 2 is minimized, in particular less than or equal to 0.05, preferably less than or equal to 0.01 and even more preferably less than or equal to 0.005. If necessary, due to the phenomenon of metamerism (visual perception of the same color under the same illumination), multiple filters can be identified, and the selection can be further refined, in particular by selecting the solution / filter that gives the largest final luminous flux (for example, for values ​​of λ between 380 and 780 nm, maximizing K x∫T T (λ)x Fo (λ) x V(λ) dλ, K is a constant equal to 683 lm / W for photopic vision (luminous flux perceived by the eye for a 1 W light source emitting at 555 nm).

[0065] From the colorimetric coordinates (x, y) determined in this way, it is also possible to infer the transmission T of the filter sought. F (λ), the calculation formula is again selected empirically as described above, depending in particular on the composition of the filter and its thickness, in order to achieve the desired transmission criterion / spectrum T by successive tests. F (λ) (ie its minimized value d), or by numerical / algorithmic optimization etc., the (filter) variables that intervene in the transmission, these variables being adjusted during this optimization depending on the selected filter.

[0066] Some examples of filters are given below. In the case of an inkjet filter formed according to the invention by deposition of a mixture of colorants or pigments dispersed in a medium, and if N absorbers (e.g. pigments and / or colorants, and possibly a medium in particular in the case where the medium absorbs light not negligibly) are arranged to be mixed and then applied under a glass ceramic plate, the optimal composition of this colored mixture can be identified according to the objective sought (neutral transmission, color retained from the original color of the source or color different from the original color of the source), from the Beer-Lambert law (always valid in our case), which enables the absorbance A of a mixture of N absorbers to be predicted: where ε i is the molar absorptivity of each species, I is the length of the optical path in the mixture, and C i is the molar concentration of each species. So the modeled T T (λ,C 1 , ..., C N ), the transmission of the whole {mixture of variable composition + glass ceramic}. According to the selected mode (realization of a universal filter or realization of a filter for a given glass ceramic and source, where the target color is the same as or different from the color of the source), it is thus possible to seek to optimize (C1 ， .., C N ) so that |T T (λ)-T Vmin |≤0.1, or calculate the transmitted flux T T (λ,C 1 , ..., C N )F e (λ) associated colorimetric coordinates (x(C 1 , ..., C N ), y(C1 , ..., C N )), then optimize (C 1 , ..., C N ) so that d=((xx c ) 2 +(yy c ) 2 ) 1 / 2 ≤ 0.05, and preferably ≤ 0.01, as explained before.

[0067] The present invention also relates to a method for selecting (and / or adjusting) at least one inkjet filter for realizing (multiple) glass ceramics ((multiple) plates) presenting at least one colored luminous area, in particular a display area (such as described above according to the purpose sought).

[0068] As already mentioned, each inkjet filter is positioned (coupled) relative to the substrate and the corresponding source so as to modify the light transmission through the glass ceramic, and it is generally positioned on the lower side of the glass ceramic (in the illumination zone). Each filter can be made according to the purpose sought, in each case of the species, as mentioned in the aforementioned selection method.

[0069] The combination of source / inkjet filter / glass ceramic makes it possible to obtain a colored or white display through the glass ceramic, which makes it possible to obtain the light effects that are particularly sought in terms of design. The article according to the invention can then present one or more luminous / display areas with functional and / or decorative (pictures, logos, alphanumeric signals, etc.) uses, which are generally observed on the main face (especially the top) of the glass ceramic substrate. The one or more zones can be in any zone of the glass ceramic substrate (including the heating zone), and can have multiple (color, brightness level) distinguished luminous / display zones, and / or each zone can itself present a different color, for example one zone can be two-color.

[0070] The article according to the invention may, if necessary, comprise other elements and / or layers in addition to the aforementioned components. For example, when it comes to a cooking module, the article may be equipped with (or associated with) functional element(s) or additional decoration(s) (frame, (s) connector(s), (s) cable(s), (s) control element(s) etc.). It may comprise various functional and / or decorative coatings, which are based on enamels, paints etc. For example, one of the faces of the substrate may comprise a layer of decorative enamel, masking (for avoiding, for example, direct vision of the source) or other functions (homogenization of the lighting etc.).

[0071] The invention also relates to a cooking and / or high temperature maintaining device (or apparatus) (e.g. a stove, an insertable cooking table, a furnace, etc.) comprising at least one article according to the invention, and which comprises one or more heating elements, such as one or more radiation or halogen elements and / or one or more gas burners and / or one or more heating devices by induction, if necessary. The article according to the invention may also comprise a cooking device comprising one or more heating elements in addition to the elements previously described in the definition of the invention. The invention encompasses both cooking devices comprising a single plate and devices comprising a plurality of plates, each of which is single-fire or multi-fire, if necessary. By the term "fire", it is understood that the cooking is localized. The invention also relates to a mixed cooking device, in which one or more cooking plates comprise multiple types of fire (gas fire, radiation, halogen or induction fire). In addition, the invention is not limited to the manufacture of cooking modules or plates for stoves or cooking tables. The articles manufactured according to the invention may also be other planar modules or plates, which should exhibit a great insensitivity to temperature variations.

[0072] The cooking device, in addition to the internal heating element, generally also includes an operating and / or control device, the internal element is covered by a glass ceramic substrate, through which a display other than red is visible, and if necessary, at least one masking device is equipped on one side or inside it, which is used to mask at least a part of the internal element.

[0073] The invention also relates to a method for manufacturing an article according to the invention, wherein at least one inkjet filter having a thickness comprised between 1 and 50 μm is integrated, in particular printed, on at least one zone of a glass-ceramic substrate and / or a source and / or an intermediate element between substrate and source, such as selected according to the invention as mentioned above, in particular according to the selection method mentioned above. The filter is inserted in particular in the form of a layer, which is deposited on the source or glass-ceramic substrate, as mentioned above. The filter is advantageously inserted after the ceramicization of the precursor glass (or mother glass or green glass) that enables the glass-ceramic substrate to be obtained.

[0074] For recollection, the manufacture of glass-ceramic plates is generally carried out as follows: in a melting furnace, a glass of the composition selected for forming a glass-ceramic is melted, the molten glass is then rolled into standard strips or sheets, by passing the molten glass between rolling rollers and cutting the glass strip into the desired dimensions. The plate thus cut is then ceramized in a manner known per se, consisting in firing the plate according to a selected thermal profile for transforming the glass into a polycrystalline material called "glass-ceramic", whose coefficient of expansion is zero or almost zero and whose resistance to thermal shocks can be up to 700° C. Ceramics generally comprises a step of increasing the temperature stepwise up to a nucleation range, which is generally located in the neighborhood of the glass transformation range; a step of passing through the nucleation interval in several minutes, a new stepwise increase in temperature up to the temperature of the ceramizing stage (palier), maintaining the temperature of the ceramizing stage during several minutes, and then rapid cooling down to ambient temperature. If necessary, the method also comprises a cutting operation (generally before ceramization), for example by means of a water jet, mechanical scoring with a roller, etc., followed by a shaping operation (grinding, chamfering, etc.).

[0075] The invention also relates to the use of at least one inkjet filter having a thickness comprised between 1 and 50 μm in a lighting device integrated in a glass-ceramic article for obtaining an article exhibiting at least one colored luminous area, in particular a display.

[0076] Further details and advantageous features emerge below from the description of a non-limiting embodiment of the invention.

[0077] Comparative example: In the present example, the article realized is a planar cooking module comprising a (substrate) glass-ceramic plate, commercialized by the company Eurokera under the reference KeraVision, the plate presenting a smooth upper side and a smooth lower side (the face may also be equipped with teeth) and a thickness of 4 mm, the article also comprising a white LED display (light source) (7-segment display) commercialized by the company AVAGO Technologies under the reference HDSM-431W, and also comprising a combination of two filters selected from the series of color filters for lighting commercialized by the companies LEE FILTERS or Rosco, the light source being fixed under the plate and the filter added under the glass-ceramic plate being located between the source and the plate. In operation, the source emits a light beam which passes through the filter / plate complex at the display area. The distance between the source and the plate is less than or equal to 5 mm, it may in particular be less than 2 mm, or even 1 mm.

[0078] The filter is selected in such a way that it is desired to obtain a warm white display from a white display (with target colorimetric coordinates x c=0.350,y c =0.315), the initial colorimetric coordinates of the white display were also measured (x 0 =0.33±0.01,y 0 = 0.29 ± 0.01). Two lists of color-pass absorption filters, produced by the companies LeeFilters and Rosco, in the form of colored (PET type) polymer films were arranged. It was sought to determine which filter(s) to insert between the display and the glass ceramic plate for obtaining the target color.

[0079] The density F of the energy flux of the measurement source e (λ), and the spectral optical transmission of the filter and the glass ceramic (the transmission measurement on a glass ceramic plate whose textured (toothed) surface is eliminated by polishing if necessary is carried out with the aid of an integrating sphere, for example the SPH-12-X model from SphereOptics, coupled to a spectrometer, for example the CAS140 model from Instrument Systems). For the N envisaged combinations of one or more Lee Filters or Rosco color filters with a glass ceramic plate (T T (λ) i＝1...N , then calculate the corresponding transmitted flux (T T (λ)F e (λ) i＝1...N The colorimetric coordinates (x i ,y i ) i＝1...N , and all these points (x i ,y i ) i＝1...N Placed in the CIE 1931 chromaticity diagram. Retaining a filter combination that enables to obtain an energy flux T corresponding to that emitted by the source / filter / glass-ceramic whole T (λ)x F o (λ) associated colorimetric coordinates (x, y), so that the value d = ((x c ) 2 +(yy c ) 2 ) 1 / 2 is minimized, in particular less than or equal to 0.05, preferably less than or equal to 0.01.

[0080] It is observed that, in the case of the use of a single filter list, d is not minimized within the fixed limits. On the contrary, it is observed that the use of a combination of 2 LEE FILTERS filters, in this case filters 063 and 243, enables the desired target color to be obtained given the display and the glass ceramic plate. The measured value is 0.002 and the brightness obtained, which characterizes the visual perception of luminosity, is also 71 cd / m 2 The white color obtained through the article exhibits the following colorimetric coordinates x=0.348, y=0.314).

[0081] After inserting the filter between the plate and the source, some thermal tests were also carried out by moving a hot pan upright next to the filter. The pan was heated by boiling water (after moving, a temperature of about 60° C. was generated under the glass ceramic), cooking French fries (after moving, a temperature of about 85° C. was generated under the glass ceramic), or an empty pan (after moving, a temperature of about 200° C. was generated under the glass ceramic).

[0082] The filter in contact with the glass ceramic deformed in each case after the hot pan was moved. After a 1 mm spacing of the filter from the glass ceramic plate, deformation was only observed in the case of moving the empty hot pan. After a 2.5 mm spacing of the filter from the glass ceramic plate, no deformation was observed.

[0083] Example according to the invention: In this example, it is sought to achieve a filter by absorption, which is suitable for obtaining the white appearance sought previously with the displays and panels mentioned in the comparative examples, by inkjet printing according to the invention on a glass ceramic substrate. The ink used is a UV-dried, temperature- and light-stable acrylic ink, selected, for example, from the inks of Anapurna M commercialized by the company Agfa. The glass ceramic is previously coated by rubbing on its underside, in the display area above the source, with a monomolecular layer of a primary structure in the form of aminosilanes (commercialized by the company Sika France under the reference number Hydropep 100) dissolved in water and stabilized by an organometallic compound. A database is arranged that incorporates the filter spectra generated from possible mixtures between the colors used, the colors being in particular the primary colors (especially cyan / magenta / yellow / black). For each filter of the color library, the color point (x, y) of the source seen through the plate plus the filter is determined, and the filter is selected, which makes it possible to obtain a corresponding energy flux T emitted by the source / filter / glass ceramic as a whole. T (λ)x F e (λ) associated colorimetric coordinates (x, y), so that the value d = ((x c ) 2+(yy c ) 2 ) 1 / 2 is minimized, in particular is less than or equal to 0.05, preferably less than or equal to 0.01 and still more preferably less than or equal to 0.005.

[0084] The filter thus selected is printed on the lower layer of the aforementioned primary structure of the glass ceramic by inkjet printing with a thickness of about 10 μm (by using, for example, an Anapurna M printer with a printing configuration of at least 4 passes), the filter resulting from a mixture between the colors of the printer. The filter selected in this example for obtaining the sought white color is then produced from a mixture of 76% (relative to the ratio of the maximum ratio that the printer can deliver for this color) of the cyan primary color ink of the Anapurna M brand commercialized by the company Agfa and 34% (relative to the maximum ratio that the printer can deliver for this color) of the yellow primary ink of the Anapurna M brand commercialized by the company Agfa, these inks being based on diacrylate d'oxybis(méthyl-2,1-éthanediyle), isodecyl acrylate and acrylate.

[0085] The measured value is 0.000, and the brightness obtained to characterize the visual perception of luminance is also 109 cd / m 2 , which brightness is better than that obtained with the polymer filter. The white color obtained through the article exhibits the following colorimetric coordinates x=0.350, y=0.315, which corresponds to the white color sought.

[0086] The same thermal tests as those carried out in the comparative example have also been carried out on articles equipped with inkjet filters thus obtained, of a thickness of about 10 μm, by moving a hot pan upright alongside the filter. No deformations or optical consequences were observed in any case. Thus a better thermal resistance was observed for the article according to the invention than in the case of using the polymer filter according to the comparative example. The solution according to the invention then uses a composition that is heat-resistant to all the temperatures to which the control panel is exposed, whether for inductive or radiative applications, which is not the case with solutions of the polymer filter type, in which the filter should deviate from the glass ceramic by at least 1 mm, thereby increasing the complexity of the implementation of the filter.

[0087] The articles according to the invention, in particular the plates, can be used in particular advantageously for realizing new series of cooking plates for stoves or cooking tables, but can also be used advantageously for realizing oven panels (e.g. doors or door parts) or panel panel elements and the like.

Claims

1. An article presenting at least one colored luminescent display area, said article comprising at least one glass-ceramic substrate having a light transmission from 0.8% to 40% and an optical transmission of at least 0.1% for at least one wavelength included in the range from 420 to 780 nm, at least one light source and at least one optical filter, said at least one optical filter being obtained by inkjet printing and coupled to the light source, said filter having a thickness between 1 and 50 μm, said filter presenting at least 5% light transmission so as to form at least one colored luminescent display area in at least one area of ​​the glass-ceramic substrate, said filter being obtained from one or more inks, each ink comprising at least one medium and / or solvent in a ratio of 35 to 90% by weight, at least some colorants or pigments in a ratio of 1 to 10% by weight, and one or more additives in a ratio of 0 to 15% by weight, said medium being a UV-dried acrylic medium.

2. The article according to claim 1, characterized in that The filter is a color filter obtained by superposition of deposition of a plurality of colors.

3. The article according to claim 1, characterized in that The filter is a color filter defined by a ratio between colors.

4. The article according to claim 1, characterized in that The filter is a color filter defined by the ratio between cyan, magenta, yellow and black.

5. The article according to claim 1, characterized in that The size of the particles in said one or more inks is less than 1 μm, the deposition viscosity of said one or more inks is comprised between 5 and 15 mPa.s and the surface tension of said one or more inks is comprised between 15 and 50 mN / m.

6. The article according to claim 1, characterized in that The inkjet filter is applied or printed on the glass ceramic substrate and / or on the at least one light source and / or on the at least one intermediate element.

7. The article according to claim 1, characterized in that The portion of the article to which the filter is applied is treated prior to deposition of the ink, by depositing an adhesion promoter and / or by a non-chemical surface treatment.

8. The article according to claim 7, characterized in that The part of the article to which the filter is applied is treated, before the deposition of the ink, by a non-chemical surface treatment of the plasma type.

9. The article according to claim 7, characterized in that Between the inkjet filter and the part of the article to which the filter is applied there is at least one climbing layer or a layer of an adhering primary structure based on one or more silanes and / or on one or more siloxanes or polysiloxanes.

10. The article according to claim 9, characterized in that The one or more silanes are one or more aminosilanes and / or one or more methacrylate silanes and / or one or more epoxy silanes.

11. The article according to claim 1, characterized in that The filter is selected according to the glass ceramic so that at least one colored luminescent area of ​​a composite color obtained by mixing a plurality of wavelengths and / or white is formed.

12. The article according to claim 1, characterized in that The filter is selected according to the light source so that at least one colored light emitting area other than red is formed.

13. The article according to claim 11, characterized in that The filters are selected so as to form at least one white or colored light emitting area of ​​a composite color obtained by mixing a plurality of wavelengths.

14. The article according to claim 1, characterized in that The filter is a filter which compensates for the transmission of the glass ceramic, so that the glass ceramic and the filter as a whole exhibit an approximately constant total optical transmission in a selected spectral range.

15. The article according to claim 1, characterized in that One or more filters are used to obtain a selected target color that is the same as or different from the original color of the source.

16. An article according to claim 1 or a device for cooking and / or maintaining high temperatures comprising an article according to any one of claims 1 to 15 and comprising one or more heating elements.

17. Method for selecting at least one inkjet filter for realizing an article according to one of claims 1 to 16, which presents at least one colored luminous display area, according to which the colorimetric coordinates (x c ,y c ), and a filter is sought which makes it possible to obtain the colorimetric coordinates (x, y) associated with the energy flux emitted by the source and the filter and the glass-ceramic monolith, such that the value d=((xx c ) 2 +(yy c ) 2 ) 1 / 2 Less than or equal to 0.05, wherein the filter is coupled to a source so as to produce the sought display, wherein the filter is obtained from one or more inks, each ink comprising at least a UV dried acrylic medium, at least some colorant or pigment and one or more additives.

18. Method for manufacturing an article according to one of claims 1 to 16, wherein at least one inkjet filter is integrated on at least one region of the glass-ceramic substrate and / or the source and / or an intermediate element between the substrate and the source, the thickness of the inkjet filter being comprised between 1 and 50 μm, The selection is performed according to the selection method of claim 17.