Laser decoating of coated glass article

Abstract

The present invention relates to a glass article (A) comprising a glass sheet (2) comprising a first surface (21) and a second surface (22) opposite to the first surface; and an ink layer (3) disposed on at least a portion of the second surface of the glass sheet The ink layer has a thickness value comprised between 1μm and 50μm; an average thickness and a standard deviation; and wherein the standard deviation is equal to or lower than the lowest of either (a) 3µm or (b) 20% of the average thickness.

Description

Laser decoating of coated glass articleField of the InventionThe present invention relates glass articles comprising an ink layer of uniform thickness for perforation by laser ablation.Background ArtParticularly in the car industry, it is common to use cover glass sheets as decorative interior design elements and / or to protect and hide displays. Cover glass sheets can be specifically designed to fit a specific location in the car such as the dashboard, the central armrest, the door armrest,... When used to protect and hide displays, it could be that the cover glass sheet is larger, even much larger than the display device. Hence, their design and aesthetics are critical to the commercial success.The car industry is therefore still looking for high end technical solutions to provide aesthetically pleasing car interior elements to improve the overall driver experience. Furthermore, it is of interest to the car industry to use such superior decor elements to protect and hide display devices. When such display device is in the Off mode, it should be completely invisible to the car user whereas in the On mode, the display should be perfectly visible and provide the expected high resolution and optical properties. Whether used as design element or as dead front article, at least one face of the glass sheet is covered by a ink layer.Laser decoating is a recent technology that is increasingly used in different applications to achieve high resolution decoating patterns. Laser decoating is done by scanning the pulsing laser beam on the glass surface.To provide the necessary optical and aesthetic properties, it is critical that the laser decoating is achieved in a very accurate way at a microscopic level. In particular, the discrete openings created by laser decoating needs to be as small as possible so that keep the openings invisible to visual inspection. It requires precise use of laser energy and avoidance of excessive thermal damage. Decoating patterns should not create visual artefacts, which affect the quality of the display.Furthermore, it is critical that the laser decoating is achieved in a very accurate way at the macroscopic level for uniform appearance since appearance needs to be visually pleasant for the end-user and for the functionality to be enhanced. The decoating pattern, shape and spacing must be designed in a way to optimize both appearance and functionality with respect to the targeted application (i.e. location in the vehicle, type of display / lighting, etc.).Therefore there is still a need in the art to provide an efficient and cost effective solution to provide glass articles wherein the ink layer is decoated in a very accurate manner both at microscopic and macroscopic levels.Summary of the InventionThe present invention relates to a glass article comprising a glass sheet having a first surface and a second surface opposite to the first surface; and an ink layer disposed on at least a portion of the second surface of the glass sheet. The ink layer has a thickness value comprised between 1pm and 50pm; an average thickness and a standard deviation and its standard deviation is equal to or lower than the lowest of either (a) 3pm (< 3pm) or (b) 20% (< 20%) of the average thickness. Preferably, its standard deviation is equal to or lower than the lowest value of either (a) 2pm (< 2pm) or (b) 10% (< 10%), preferably 5% (< 5%), more preferably 2% (< 2%) of the average thickness.The ink layer is preferably an organic based ink, more preferably an acrylic ink or an epoxy ink. In preferred embodiments, the ink layer has a thickness of equal to or greater than 2pm (> 2pm), preferably equal to or greater than 3pm (> 3pm), more preferably equal to or greater than 5pm (> 5pm) and / or equal to or lower than 40pm (< 40pm), preferably equal to or lower than 30pm (< 30pm), preferably equal to or lower than 25pm (< 25pm), preferably equal to or lower than 20pm (< 20pm), preferably equal to or lower than 15pm (< 15pm), more preferably equal to or lower than 12pm (< 12pm). It is preferred that the ink layer has a light transmittance equal to or lower than 50% (TLD4 < 50%), preferably equal to or lower than 30% (TLD4 < 30%), preferably equal to or lower than 10% (TLD4 < 10%), preferably equal to or lower than 5% (TLD4 < 5%) and more preferably equal to or lower than 2% (TLD4 < 2%).In a preferred embodiment, the ink layer further comprises a perforated zone comprising discrete openings having dimension equal to or lower than 200pm. The discrete openings are typically spaced from each other by a distance equal to or lower than 200pm, preferably equal to or lower than 150pm, more preferably by a distance equal to or lower than 100pm. The discrete opening are preferably inthe shape of lines having a width of equal to or lower than 30pm (W < 30pm), preferably equal to or lower than 20pm (W < 20pm), preferably equal to or lower than 10pm (W < 20pm).In another embodiment, the first surface of the glass sheet further comprises at least one decorative roughened zone bordered by a border area. The least one decorative roughened zone has a mean surface roughness defined by an arithmetic amplitude value, Ra(ZOnej and defined by an spacing value, Rsm(zone). The border area has a mean surface roughness defined by an arithmetic amplitude value, Ra(border), and defined by a spacing value, Rsmjborder). It is preferred that the absolute difference between Ra(ZOnej and Rajborder) is at least 25nm ( | RajZOne) - Rajborder) | 25nm) and / or the absolute difference between RsmjZOne) and Rsmjborder) is at least 2pm ( | RsmjZOne) - Rsmjborder) | > 2pm).The glass sheet can be a strengthened glass sheet, preferably a chemically strengthened glass sheet. The first surface of the glass sheet can be coated with an anti-finger print coating and / or an anti- reflective coating. It is preferred that the thickness of the glass sheet is equal to or lower than 2mm, preferably equal to or lower than 1.6mm, more preferably equal to or lower than 1.3mm.The present invention further relates to a dead front article comprising the glass article described above and at least a display device having at least a screen. The second surface of the glass sheet is facing the display device and is perforated. The perforated zone is positioned in a complementary fashion to the screen. It is preferred that the first surface of the glass sheet comprises further at least one roughened zone positioned in a complementary fashion to the perforated zone. It is further preferred that the at least one roughened zone provides a clarity equal to or lower than 80%, preferably equal to or lower than 50%, more preferably equal to or lower than 30%.The present invention further relates to a method for producing the glass articles and the dead front articles of the present invention. The present invention also relates to the use of the glass article and of the dead front article for car interior application, home appliances and / or integrated interactive display.Other aspects and advantages of the embodiments will become apparent from the following detailed description taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the described embodiments.Brief description of the drawingsFigure 1 shows a cross-sectional view of a portion of a glass article according to one embodiment of the present invention wherein the ink layer comprises a perforated zone.Figure 2 shows an extended cross-sectional view of a portion of a glass article according to one embodiment of the present invention illustrating discrete openings of the perforated zone.Figure 3 shows a cross-sectional view of a dead front article that comprises one embodiment of a glass article and a screen of a display device.Figure 4 shows top views of the first surface of the glass sheet of two different glass articles according to two embodiments of the present invention. Figure 4(a) shows a first surface of the glass sheet of a glass article comprising one roughened zone picturing a wood grain pattern. Figure 4(b) shows a first surface of the glass sheet of another glass article comprising two roughened zones picturing a geometrical pattern.Figure 5 shows 2D microscope images of two glass articles wherein an ink layer has been decoated by laser ablation. Figure 5(a) shows a comparative glass article and figure 5(b) shows a glass article according to the invention.Figure 6 shows top views of two deadfront articles in the On mode. Figure 6(a) shows a dead front article of the prior art and figure 6(b) shows a dead front article according to the invention.Detailed description of the InventionThe present invention relates to a glass article that comprises a glass sheet having a first surface and a second surface opposite to the first surface. An ink layer is deposited on at least a portion, preferably on the entire area, of the second surface.Typically the ink layer has a thickness of 1pm to 50pm. The ink layer can be further perforated by laser ablation to create a perforated zone. The glass article of the present invention can be used as a decorative car interior element or as a dead front article. An ink layer is applied to the surface of the glass sheet for decorative and / or opacity purposes. Again for decorative purposes and / or to provide visual access to a screen of a display device, a portion of the ink layer is typically decoated by laser.The discrete openings created by laser decoating within the ink layer must have the required sharpness to provide the required decorative effect and / or the required optical quality. It has been surprisingly found that the uniformity of the ink layer is critical to achieve consistent qualitative laser decoating. Uniformity refers herein to the thickness and the ablation threshold of the materials forming the layer. In particular, it has been further found that for lasers with pulse duration less than 50ps, which is preferred for decorative applications to reduce thermal damage, the uniformity of the ink layers becomes even more critical.Decoating process preferably uses the lowest possible laser energy to keep the discrete openings width as small as possible while still removing the ink layer completely. Furthermore, one laser pass is preferably required to maintaining very sharp small dimension of the discrete openings, avoid the complexity and processing time of laser multiple passes. It has been found that if the thickness is not uniform, higher energy and / or more than one pass, is needed at thicker areas to have complete decoating and this could damage the surface of the glass sheet.Therefore, the objective of the present invention is to provide cost effective glass articles of superior quality and rendering. By 'cost effective', it is herein understood as being manufactured by a fast, simple and efficient manufacturing process.In particular, the object of the present invention is to obtain a superior decorative rendering of the glass article when used as a decorative design elements. It is a further objective to obtain a superior optical rendering of the image that is displayed when the glass article is used in combination with a display device.GLASS ARTICLEThe present invention relates to a glass article that comprises a glass sheet comprising a first surface and a second surface opposite to the first surface. When used in a car application, the first surface being opposite to the second surface, will face the interior of the car and the driver and the second surface faces the carrier.An ink layer is deposited on at least a portion, preferably on the full surface - also referred to as entire area, of the second surface. By 'entire area', it is intended to mean that the majority of the surface is provided with the ink layer. The term 'majority' is intended to mean almost the entire surface area, preferably the entire surface area. However, it cannot be excluded that some insignificant part(s) of the surface are not covered. The term 'insignificant' would mean having no substantial impact on the dedicated performance.The ink layer has a thickness comprised between 1pm and 50pm. It is characterised by a thickness average and a standard deviation wherein its standard deviation is equal to or lower than the lowest value of either (a) 3pm (< 3pm) or (b) 20% (< 20%) of the average thickness.Preferably, the standard deviation of the ink layer is equal to or lower than the lowest value of either (a) 2pm (< 2pm) or (b) 10% (< 10%), preferably 5% (<5%), more preferably 2% (< 2%) of the average thickness.The thickness of the ink layer can be measured by a 3D optical confocal microscope. Within the ink layer, a line of 35 pm width is laser decoated across the length of the glass sheet to expose the glass surface (decoated area) and provide the zero height reference. The laser decoating process is done with a laser source with pulse duration of 10 ps and wavelength of 1064nm. The laser beam has Gaussian profile. The laser beam is coupled to a galvo scanner equipped with an f-theta lens, which has a focal length of 100 mm. The laser beam diameter at the focus of the lens is approximately 20 um. The other laser parameters are as follows: pulse repetition rate 1 MHz, average power 16 W, scanning velocity 2750 mm / s. Attention should be paid not to damage the surface of the glass sheet. The microscope will map the height of an area 100 pm x 100 pm. This 100 pm x 100 pm area should include at least part of the decoated area to provide the height reference point. The thickness of the ink layer within the scanned area is estimated by the software integrated in the microscope and provides a single thickness value. This measurement is repeated 10 times with a distance of 0.5 cm between each measurement.The thickness of the ink layer is typically comprised between 1pm and 50pm (lpm < thickness < 50pm). Preferably to provide minimal light blocking, the ink layer thicknesses is equal to or greater than 2pm (> 2pm), preferably equal to or greater than 3pm (> 3pm), more preferably equal to or greater than 5pm (> 5pm). Preferably for ease of decoating and cost effectiveness, the ink layer's thickness is equal to or lower than 40pm (< 40pm), preferably equal to or lower than 30pm (< 30pm), preferably equal to or lower than 25pm (< 25pm), preferably equal to or lower than 20pm (< 20pm), preferably equal to or lower than 15pm (< 15pm), more preferably equal to or lower than 12pm (< 12pm). The minimum and maximum thicknesses are mean values of layer thickness. Thickness is measured in the direction perpendicular to the glass sheet faces.Furthermore, it is generally advantageous if the thickness of the ink layer is not too large. This facilitates the removal by laser ablation. This is also advantageous for light transmission through the openings in the area of the ink layer. If the ink layer is too thick, the walls of the openings will have a corresponding length and will absorb an unnecessary amount of light. On the other hand, ink layersthat are too thin are also unfavorable, in particular in view of ensuring a sufficient degree of light blocking. Preference is given to layer thicknesses of equal to or greater than more than 1 pm (> 1pm), equal to or greater than more than 2 pm (> 2pm) equal to or greater than more than 3 pm (> 3pm) and equal to or greater than more than 5 pm (> 5pm) that are generally necessary to suppress the transmission of the light from the display panel. A thickness of the opaque layer of 25pm or less, it is possible to suppress the narrowing of the viewing angle. The minimum and maximum thicknesses given above are mean values of layer thickness.Within the scope of the invention, the ink layer can refer to a single layer of a single material or to several sub-layers of the same or different material(s). When serval layers are encompassed within the ink layer, it is the total thickness of all sub-layers that are herein considered. Preferably, the ink layer is a single layer for ease of production and / or ease of laser decoating technique.Suitable for use in the present invention are the following ink layers that can deposited by any conventional deposition process. The ink layer can be deposited on either the air side or the tin side of the glass sheet manufactured by a float process.The ink layer is typically a layer having a lower transmittance of visible light than the glass sheet, in the visible spectral range from 380 nm to 780 nm. It exhibits typically a LTD4 light transmittance equal to or lower than 50% (LTD4 < 50%). Preferably, the ink layer has a light transmittance equal to or lower than 30% (LTD4 < 30%), preferably equal to or lower than 10% (LTD4 < 10%), preferably equal to or lower than 5% (LTD4 < 5%) and more preferably equal to or lower than 2% (LTD4 < 2%) to provide opacity. TLD4 is determined according to the IS09050 standard for a thickness of 4 mm at a solid observation angle of 2° (with illuminant D65) and for a wavelength range between 380 and 780 nm.The ink is not particularly limited. Suitable inks are inorganic type inks containing a ceramic fired body or the like, organic type inks containing a dye or a pigment and / or an organic resin. Preferred are solvent based organic inks and more preferred are acrylic inks (acrylic networks with color imparting pigments0or epoxy inks.The ink layer can be semitransparent layers, contrast layers and / or color layers. Semi-transparent layers may include a region of solid colour or a design of two or more colours, that can potentially provide a decorative pattern. Contrast layer can be used to enhance the visibility or contrast between the colours of the semi-transparent layers. Color layer can include multiple colors across the layer and / or specific colors in specific regions. It can be a continuous layer or discontinuous, i.e., color is only provided in certain locations.The ink layer can be printed onto the substrate using a CMYK color model or other color models that incorporate white ink.The ink can be thermal or UV cured ink. In particular, the ink is composed of at least one or more colorants and a carrier. The colorants can be soluble or insoluble in the carrier. The colorants can dry colorants in the form of a fine powder. Such fine powders have particles that are typically from lOnm to 500nm in size. Using the CMYK color model, the colorant provides cyan, magenta, yellow, and / or key (black) colors. For white inks, the colorant can be any of a variety of suitable pigments, such as TiCk, SbjOa, BaSC, BaS04:ZnS, ZnO, and (PbCOa^PbfOH)?. The colorants are dissolved or suspended in the carrier.The carrier can serve as a binder to create adhesion to the surface upon which the ink is applied. Further, in some embodiments, additives can be included in the carrier to improve adhesion to glass surfaces. Non-limiting examples of carriers for the colorant include propylene glycol monomethyl ether, diethylene glycol diethyl ether, dimethylacetamide, and toluene. Generally, such carriers solidify at temperatures from 80°C to 200°C. In general, the ink includes from 0.5% - 6% by volume of the colorant and 94% - 99.5% by volume of the carrier.Printing methods include, but are not limited to, ink jet printing, screen printing, and transfer decoration over the second face of the glass sheet.LASER DECOATINGIn a preferred embodiment of the present invention, the ink layer deposited on the second surface of the glass sheet comprises one or more perforated zone(s) comprising discrete openings. Please refer to Figure 1 which is a schematic cross-sectional view of a portion of a glass article (A) of the present invention comprising a glass sheet (2) comprising a first surface (21) and a second surface (22) opposite to the first surface and an ink layer (3) disposed on the second surface of the glass sheet. The ink layer comprises a perforated zone (5) comprising discrete openings (4).Laser ablation is typically used to produce the perforated zone in the ink layer. An apparatus for laser ablation is used to create a multitude of discrete openings or holes within the ink layer. The pattern of openings defines a perforated zone allowing light that is incident onto ink layer to pass through the ink layer and the glass sheet so that the perforated zone demonstrate a light transmission (LTD4) typically comprised between 5% and 70% depending on the application. Preferably, the perforated zone has a light transmission LTD4 equal to or greater than 10% (LTD4 > 10%), more preferably a LTD4equal to or greater than 15% (LTD4 > 15%), LTD4 equal to or greater than 30% (LTD4 > 30%). Preferably, the perforated zone has a light transmission LTD4 equal to or lower than 50% (LTD4 < 50%).The glass article of the present invention can have one more perforated zone(s). Perforated zone(s) can be used to create decorative patterns that are visible with incident light and / or to provide visual access to screens. Any light source can be suitable in the form of display module as well as any light sources for producing graphics, icons, images, displays, etc. Exemplary displays include LED (light emitting diode) displays, a DLP (digital micromirror device) MEMS chip, LCDs (liquid crystal displays), OLED (organic light emitting diode) displays, transmissive displays and the like. Combinations of different perforated zones of different functions can be used to create appealing designs.Typically, the apparatus for laser ablation comprises a laser and a device for guiding the laser beam emitted by the source over the coated surface of the glass substrate. For example a galvanometer scanner can be employed as the device for guiding the laser beam over the surface. Means for displacing the glass sheet may be provided alternatively or in addition to a galvanometer scanner. As known by those skilled in the art that, decoating can be done with one or multiple laser beams simultaneously to increase the processing speed. It can be achieved either by splitting one laser beam or using multiple laser sources and multiple scanners. The splitting of the laser beam can happen before or inside the scanner head. Particularly suitable for this purpose is an X-Y table, also referred to as a cross table. In such an embodiment, the laser beam can be hold stationary and the openings with the desired shape can be introduced into the decorative layer by moving the X-Y table with the glass sheet substrate placed thereon. In order to ensure consistent high accuracies, it is also possible to use a synchronized scanning and displacing apparatus. In this case, the movement of table or another means for displacing the glass sheet is synchronized with the deflection of the scanner, e.g. galvanometer scanner.For focusing the laser beam on the surface in order to achieve the highest possible intensity, appropriate focusing optics may be provided. Focusing optics can be arranged downstream of galvanometer scanner. However, it will be apparent to those skilled in the art that other configurations suitable to focus the laser beam onto the glass sheet are likewise possible. In order to achieve short focal lengths it is favorable to arrange the focusing optics behind the galvanometer scanner as seen in the beam direction. A focusing optical system, in particular a lens or group of lenses or a focusing mirror with a focal length of less than 300 mm, is preferred.For locally removing the ink layer to create discrete openings which extends through the ink layer, the device for guiding the laser beam moves the laser beam over the surface, and the laser is adjusted sothat the ablation threshold of the material of the ink layer is exceeded and thus the ink layer is removed at the point of impingement. However, the output power of the laser is adjusted so that the ablation threshold of the glass sheet, is not reached so that only the ink layer is removed. For glass the ablation threshold for a laser wavelength of 1064 nm is approximately 5.2*1017 W / m2.It is therefore advantageous if the materials of the glass substrate and of the ink layer are selected so that the ablation threshold of the material of the glass substrate is higher than the ablation threshold of the ink layer, in particular in the infrared spectral range, more particularly at a wavelength of 1064 nm.The laser beam guiding device is controlled by a control device which may for instance execute a program that translates the shape and location of the pattern feature into control signals by means of which the laser beam is moved over the surface by the laser beam guiding device. Preferably, the control device also controls the laser, in particular with regard to switching on and off and laser emission.According to one exemplary embodiment, a pulsed laser was selected which can be sufficiently well focused to ablate dots. This can be achieved with a neodymium-YAG laser with a wavelength of 1064 nm and a pulse length of 10 ps. A scanner with optics having a focal length of 255 mm can be employed. The M2 factor is less than 1.4, preferably less than 1.2. The tubular beam has a diameter of 12 mm. Average output power 50W at 200 kHz is typically reduced to about 4 W. Other lasers may also be used. In particular a laser with a wavelength of 532 nm and a pulse length in the range 1 - 50 ns is advantageous : the smaller wavelength allows for better focusing and the longer pulse length will prevent the material to become stained which is disadvantageous in case of light colored layer. Furthermore, lasers in the ns range have a distinct cost advantage over lasers in the short ps range.Figure 2 is a schematic extended cross-sectional view of a portion of a glass article (A) comprising a glass sheet (2) with an ink layer (3) on its second surface (22). Discrete openings (4, 4b) have been introduced into the ink layer (3). In the example shown on the right of Figure 2 the wall of the discrete opening (4) is substantially perpendicular to the glass sheet (2). According to another embodiment illustrated on the left, the discrete opening (4b) may taper from the outer surface of the ink layer (3) toward the second surface (22) of the glass sheet (2), i.e. being wide at one end and narrowing down at the other end. Such tapered discrete opening may be advantageous for introducing an opening even into rather thick ink layer by repeated or stepwise ablation. Preferably, however, the angle a between the wall of discrete opening and the surface normal of the glass sheet is smaller than 20°,preferably smaller than 15°. This angle is the mean angle of the wall which can be easily determined trigonometrically from the ratio of the width of the opening at the substrate to the width at the surface of ink layer and the thickness of ink layer.It is recognized in the art that laser ablation may cause a dark discoloration of the ink layer. If the ink layer itself is dark, such discoloration and hence the openings will remain invisible. However, this is different for ink layers having a light color hue. In this case, the dark discoloration may be visible at the edges of the opening. This can be counteracted by adjusting the pulse frequency of the laser and the rate at which the laser beam is directed over the ink layer such that the points of incidence of the laser pulses do not excessively overlap each other, which results in the desired dot pattern.According to a preferred embodiment, a top-hat profile of the laser beam is used in order to minimize the thermal impact in the peripheral area of the opening to be produced so as to avoid the staining effect. In this case, the edge regions of the initially Gaussian beam which have not enough energy for ablating the ink but yet have enough energy to heat the ink layer to an extent to cause discoloration thereof, are eliminated. Another advantage of a top-hat profile is better contour definition, since a Gaussian profile does not permit to remove multi-layered systems with sharp contours, although this effect might cause blurring on a micrometer scale that is hardly visible or not visible at all to the eye.Laser decoating is typically achieved on the second surface of the glass sheet, i.e. directly on the decorative layer. However, it has been surprisingly found that laser decoating from the opposite side i.e. the first surface (21) of the glass sheet is more effective. The discrete openings (4, 4b) have a tubular shape across the decorative layer (3) as illustrated in Figure 2. To create the discrete opening (4, 4b), the laser beam will vaporize a very small region close (4i, 4bi) to the second glass surface (22) that will push away the remaining material. Laser decoating from the first surface of the glass sheet is therefore faster and more efficient.1. Discrete openingsThe perforated zone comprises discrete openings. By 'discrete opening', it is typically understood that, each discrete opening has one of the dimension (diameter, longest axis or width) in the micrometer scale, typically lower than 200pm. Dimension is commonly understood as the diameter in case of circular shape, longest axis in case of elliptical shape or width in case of lines. The discrete openings are distinct from one another in the perforated display area. Discrete openings are commonly understood as discrete openings through the entire thickness of the opaque layer.The discrete openings can created via a single or multiple laser pulses. The discrete openings have a dimension equal to or lower than 200pm, preferably equal to or lower than 100pm, preferably equal to or lower than 85pm, preferably equal to or lower than 60pm, preferably equal to or lower than 30 pm, preferably equal to or lower than 20 pm, more preferably equal to or lower than 10 pm. When the glass article of the present invention is used as a dead front article, is it further preferred that discrete openings have a dimension equal to or lower than 60pm, preferably equal to or lower than 30pm, preferably equal to or lower than 20pm, more preferably equal to or lower than 10pm. Dimension is typically equal to or greater than 1pm, preferably greater than 3pm more preferably greater than 5pm. Indeed, it has been found that too small discrete openings can interact with the light (from the screen) and create artefacts as well as extending the time of the laser decoating step. The width of the discrete opening is measured at the bottom of the coating or at the glass sheet surface exposed in the opening. Dimension is the diameter is case of circular shape, longest axis in case of elliptical shape or width in case of lines.The discrete openings or holes generally have the shape of circular dots. However, the discrete opening may as well have the shape of elongated ovals or other geometries. Preferably the holes have the shape of lines. Indeed, it is preferred to produce openings having the shape of long straight lines, positioned parallel to one other. Discrete openings in the shape of lines are preferred because of their faster processing speed. Preferably, the discrete openings in the shape of lines have a width of equal to or lower than 30pm (< 30pm), preferably equal to or lower than 20pm (< 20pm), more preferably equal to or lower than 10pm (< 10pm). For long straight lines, it is advantageous to use a polygon scanner, because when stitching long lines a small offset might quickly be produced. Due to the offset, the line would become wider at the crossing point and therefore would appear much brighter at this point when backlit.These discrete openings form a pattern as a whole. The spacing between the individual discrete openings should be less than 200pm (< 200pm), preferably less than 150pm (< 150pm), more preferably less than 100pm (< 100pm). Typically above 7pm (>7pm), preferably above 10pm (>10pm), more preferably above 15pm (>15pm). The spacing distance is measured center to center of the discrete openings. For discrete openings in the form of ovals or lines, the spacing distance in measured center to center in the direction normal to the length of the line.A further process parameter is the percentage of the a^in relation to the total surface area within the perforated zone. This percentage is described by a ratio of ablated surface area to non-processed surface area within the perforated zone, i.e. the core area.In the case of dot-shaped discrete openings, the ratio of ablated surface area to non-processed surface area is determined according to the formula : R2* 100% / a2; wherein r is the radius of a dot and a is the spacing between two dots. In the case of discrete openings having a different shape, the percentage of the ablated surface area in relation to the total surface area is determined by the ratio of the summed surface areas of the discrete openings to the surface area of the non-processed surface within the perforated zone. Such areas will appear lighter or darker to the viewer, depending on the underlying layer. However, areas with an ablated percentage surface area of less than 1%, in particular less than 0.5% of the total surface area are rather uninteresting, since light applications will appear slightly pixelated. Therefore, in order to obtain an area with the highest possible resolution, surface with an ablated percentage surface area of more than 0.8%, preferably more than 1%, most preferably more than 1.5% have to be selected.It has been found that in some applications, total surface area can create a different color appearance. In order to mitigate or eliminate the different color appearance, a transition area can be created in which the ablated percentage surface area is reduced versus the core area by less than 2% per mm, preferably less than 1% per mm, more preferably less than 0.5% per mm. In this case, the reduction may be accomplished so that the ablated percentage surface area is preferably reduced to less than 0.5% of the total surface area at the side of the transition region adjoining the non-ablated area. The value of the gradient of the percentage surface area in the transition area may either be constant in the entire transition area or may vary. In case of a varying gradient, the aforementioned limit values refer to a mean value averaged along the gradient over the entire width of the transition area. Hence, in such embodiment, the perforated zone comprises a core area and a transition area.Therefore, in a preferred embodiment, a transition area is created within the perforated zone along the periphery of the core area, in which further dots are ablated so that the percentage surface area, determined by the ratio of ablated surface area to non-processed surface area is lower on average within the transition area than within the core area. The percentage of the total ablated surface area comprising the core area and the transition area, can be from 10% up to 70% of the total surface area of the perforated zone. Such percentage surface areas can be achieved with smaller discrete openings or with larger spacings of the discrete openings.If the glass sheet is provided with a very light color ink layer or very dark color ink layer, the described measure might not be sufficient, since under these conditions a sufficient dead front effect is possibly not created. For example, lines having a width of 10 pm may clearly be visible especially against a light decorative layer. It has been found that the dead front effect can be improved by a technique knownas dithering which is used, for example in computer graphics, to create the illusion of a greater color depth, for example when images have to be reproduced with reduced color depth due to technical limitations. In this case, the lacking colors are approximated by a specific arrangement of the pixels from available colors. In this way, hard color transitions are avoided.2. Cleaning stepRegardless of the layer thickness, the material removed by the laser might fall back on the surface in the form of dust. This dust can affect the ongoing decoating process. Furthermore, if the glass article is intended to be bonded with a display device, such dust can be detrimental. Ideally, the laser decoating device should be coupled with an exhaust pipe, which extracts the dust while they are in the air. Ideally, the glass article is washed after decoating to completely remove the contamination. The washing can consist of multiple steps using water and detergent. An additional ultrasonic washing step can be included to improve the cleaning efficiency. The final step is to rinsed the glass with pure or di-ionized water.Decorative and / or Optical Roughened zoneSurface roughness, often referred to as surface texture, is the very well-known measure of the fine- scale irregularities or variations on the surface of a material. It consists of microscopic peaks and valleys that are typically the result of the manufacturing process used to create the surface. This characteristic is distinct from larger-scale variations like waviness or form errors.The first surface of the glass sheet can be roughened partially to create one more different roughened zone(s) or can be roughened on the entire surface. The roughening of the first surface can be used to provide technical or decorative properties to the glass articles. Roughening structures can provide haptic properties as well as optical properties such as haze, gloss, haze and / or clarity to the first surface. Those properties can be used to provide optical properties to display devices and / or to create a decorative pattern.For ease of processing, the discrete openings of the perforated zone typically form a regular pattern, i.e. having regular dimension and / or regular spacing. The spacing distance is characterised by an average spacing and a standard deviation. Regular spacing means that its standard deviation is equal to or lower than 10%, preferably equal to or lower than 5%, more preferably equal to or lower than 2% of the average spacing. Dimension is characterised by an average dimension and a standard deviation. Regular dimension means that its standard deviation is equal to or lower than 10%,preferably equal to or lower than 5%, more preferably equal to or lower than 2% of the average dimension.To achieve high processing speeds, regular decoating patterns are preferred and line decoating patterns are even more preferred. However such regular decoating patterns cause optical artefacts such as diffraction and / or the Moire effect when the glass article is used in combination with a light source such as a screen. Therefore, it is preferable that the first surface comprises further an optical roughened zone positioned in a complementary fashion to the perforated zone; and the glass sheet within that optical roughened zone, provides a clarity equal to or lower than 80%, preferably equal to or lower than 50%, more preferably equal to or lower than 30%. By "positioned in a complementary fashion", it is understood that the optical roughened zone has substantially the same overall shape, perimeter shape, design, and / or pattern, and occupy at substantially the same relative surface area than the perforated zone. This means that the optical roughened zone and the perforated zone on the opposite surface are designed to match each other in terms of their geometrical features (same overall shape, perimeter shape, design, and / or pattern...) and the level of overlap. Such embodiment of the present invention achieves the combined effect of efficient and cost effective laser decoating processing of the regular pattern while a see-through zone of superior quality and rendering by avoiding optical artefacts. Clarity is measured with the parameters and device (BYK Haze-gard i) required in ASTM standard D1003 with illuminant C. "Clarity" corresponds to the portion of light that is transmitted through the glass and scattered by the final glass surface away with a different angle than the direct transmission direction (similar or parallel to the incident light rays direction) within a solid angle of 2.5° away from the direct transmission direction.A decorative roughened zone is a zone imparting a decorative design to the glass article of the present invention to enhance the aesthetic appearance by including patterns and / or colors to create a visually appealing design. The decorative design achieved by one or more roughened zone(s) can picture a leather grain pattern, a wood grain pattern, a fabric pattern, a stone pattern, a brushed metal finish pattern, a carbon fiber pattern, a geometrical pattern and / or logos.Hence, the present invention further related to a glass article wherein the first surface can further comprise at least one decorative roughened zone bordered by a border area and / or another decorative roughened zone. The decorative roughened zone is typically defined by (i) an area of relatively higher surface roughness bordered by at least one border area of relatively lower surface roughness or (ii) an area of relatively lower surface roughness bordered by at least one area of relatively higher surface roughness. Also contemplated in the present invention : the decorativeroughened zone is defined by (i) an area of relatively higher surface roughness bordered by at least one border area of even higher surface roughness or (ii) an area of relatively lower surface roughness bordered by at least one area of even lower surface roughness.By "roughened", it is typically understood that the roughened zone is characterized by the roughness features of arithmetic amplitude value Ra (nm) and spacing value Rsm (pm) roughness values defined in the standard ISO 4287-1997. The roughness is a consequence of the existence of surface irregularities / patterns. These irregularities consist of bumps called "peaks" and cavities called "valleys". On a section perpendicular to the textured surface, the peaks and valleys are distributed on either side of a "center line" (algebraic average) also called "mean line". In a profile and for a measurement along a fixed length (called "evaluation length"):- Ra being the an arithmetic mean height value (amplitude value) corresponds to the average height difference of microstructures, meaning the arithmetic average of absolute values of height differences between the peaks and valleys. Ra measure the distance between this average and the "line" and gives an indication of the height of the patterns on the textured surface;- Rsm being the mean width of the profile elements (spacing value) is the average distance between two successive passages of the profile through the "mean line"; and this gives the average distance between the "peaks" and therefore the average value of the widths of the patterns.The roughness values according to the invention may be measured with a profilometer using 2D profiles (according to ISO4287 standard). Alternatively, one can use the technique of 3D profilometry (according to ISO 25178 standard) but isolating a 2D profile which then gives access to the parameters defined in the ISO4287 standard.According to the invention, the roughness values are measured with a Gaussian filter, which is a filter of long wavelengths, also called profile filter Ic. It is used for separating the components of roughness / texture from components of undulation of the profile. The evaluation length, L, according to the invention is the length of the profile used to evaluate the roughness. Base length, I, is the part of the evaluation length used to identify irregularities characterizing the profile to assess. The evaluation length, L, is divided / cut into n base lengths, I, which depend on the profile irregularities. The base length, I, corresponds to the "cut-off" wavelength (or limit wavelength) of the Gaussian filter (I = Ic). Typically, the evaluation length is of at least five times the base length. In roughnessmeasurements, a short wavelength filter (profile filter Is) is also commonly used to eliminate the effects of very short wavelengths which are background noise.The decorative roughened zone has Ra value, Ra(ZOnej. The border area has Ra value, Rajborder). In order to create a significant difference of visual and tactile rendering; there is preferably an absolute difference between Ra(ZOne) and Rajborder) of at least 25 nm ( | RajZOne) - Rajborder) | > 25 nm); preferably at least 50nm ( | RajZOne) - Rajborder) | > 50nm), more preferably at least lOOnm ( | RajZOne) - Rajborder) | > lOOnm), and even more preferably at least 200nm ( | RajZOne) - Rajborder) | > 200nm). Typically, the absolute difference between RajZOne) and Rajborder) is no more than 2 microns, preferably no more than 1 micron.The decorative roughened zone can also be characterised by the spacing value Rsm, RsmjZOne). The border area can also be characterised by the spacing value Rsm, Rsmjborder). In order to create a significant difference of visual and tactile rendering; there is preferably an absolute difference between Rsm jZOne) and Rsmjborder) is at least 2 pm ( | RsmjZOne) - Rsm(border) | > 2 pm); preferably at least 3pm ( | Rsmjzone) -Rsmjborder) | > 3pm), preferably at least 10pm ( | RsmjZOne) -Rsmjborder) | > 10pm), more preferably at least 20pm ( | RsmjZOne) - Rsmjborder) | > 20pm ), and even more preferably at least 30pm ( | Rsmjzone) - Rsmjborder) | > 30pm). Typically, the absolute difference between RsmjZOne) and Rsmjborder) is no more than 150pm, preferably no more than 100pm.When multiple decorative roughened zones are created, there is preferably an absolute difference between RaljZOne) and Ra2jZOne) of at least 25 nm ( | RaljZOne) - Ra2jZOne) | > 25 nm) and there is preferably an absolute difference between Rsml jZOne) and Rsm2jZOne) is at least 2 pm ( | RsmljZOne) - Rsm2jZOne) | > 2 pm), to create a significant difference of visual and tactile rendering. In some embodiments, the decorative roughened zones can overlap as well.For superior tactile response of the consumer to the decorative design of the layer, one focuses on the absolute difference between RajZOne) and Rajborder) that could preferably be comprised between, 50nm-500nm and on the absolute difference between RsmjZOne) and Rsmjborder) that could preferably be comprised between 2pm-100pm.For some decorative design such as a silk pattern, a stone pattern, and / or a brushed metal finish pattern, the optical properties of gloss and diffusion properties can be of high interest. Preferably, gloss value is equal to or lower than 150 G.U. (gloss < 150 G.U.), preferably equal to or lower than 120 G.U. (gloss < 120 G.U.), more preferably equal to or lower than 90 G.U. (gloss < 90 G.U.). The gloss ismeasured in accordance with the ASTM standard D523-14 dated May 4, 2017, at the specific angle of 60°.Preferably, the glass article of the present invention comprises two decorative roughened zones or even multiple decorative roughened zones to create sophisticated decorative designs such as a leather grain pattern, a wood grain pattern, a fabric pattern, a stone pattern, a brushed metal finish pattern, a carbon fiber pattern and / or a geometrical pattern or even logos. A wood decorative pattern created by one decorative roughened zone and a geometrical pattern created by two decorative roughened zones are illustrated in Figure 4 (a) and (b).Whether for optical properties or decorative purposes, roughnening can be achieved before or after the deposition of the ink layer. The roughened zone can be achieved by etching (acid, alkaline, liquid or vapor), laser texturing, sand blasting, embossing, rolling, mechanical polishing, engraving, and / or vapor deposition (e.g., chemical or physical vapor deposition), preferably by etching. Acid etching is preferred since it provides process control, short process time and flexibility. Partial roughening phase can be used to create the at least one roughened zone: A portion of the first surface is masked with an etch resistant material and exposed to an etching solution to generate a certain level of surface roughness characterized by specific arithmetic amplitude Ra and spacing Rsm features and to generate the at least one roughened zone. The mask is then removed.The glass article of the present invention can have one more perforated zone(s). Perforated zone(s) can be used to create decorative patterns that are visible with incident light source and / or to provide visual access to the screen of display device. Any light source can be suitable in the form of display module as well as any light sources for producing graphics, icons, images, displays, etc. Exemplary displays include LED (light emitting diode) displays, a DLP (digital micromirror device) MEMS chip, LCDs (liquid crystal displays), OLED (organic light emitting diode) displays, transmissive displays and the like. Combinations of different perforated zones of different functions can be used to create appealing designs.The car industry is further looking for high end quality glass article to hide display devices. The present invention therefore further relates that the combination of the glass article with a display device. They are referred to as 'deadfront article' since when the display device is in the Off mode, it should becompletely invisible to the car user whereas in the On mode, the display should be perfectly visible and provide uniform resolution and optical properties. Therefore a further objective of the present invention is provide high quality dead front article, that provides superior decorative rendering and / or a superior optical rendering of the image that is displayed.The present invention further relates to a dead front article that comprises the glass article of the present invention and at least a display device having at least a screen. The perforated zone is positioned in a complementary fashion to the screen.By 'in a complementary fashion', it is meant that the positioning of the perforated zone corresponds to the positioning of the screen. It is it is herein understood that the perforated zone of the opaque layer has substantially the same overall shape and occupy substantially the same relative surface area than the screen of the display device. By 'substantially the same relative surface area', it is herein understood that that the perforated zone covers at minimum 75% of the screen, preferably 90% of the screen, preferably at minimum 100% of the screen. The discrete openings of the perforated zone allows to visualize at least part of the at least one screen of at least one display device. It can be contemplated that the surface of the perforated zone extends beyond the surface of the screen, in particular when the perforated zone comprises a transition area. Figure 3 is a schematic cross- sectional view of one embodiment of the dead front article (B) of the present invention that comprises a glass sheet (2) and a screen (6) of a display device wherein discrete openings (4) have been created in the ink layer (3) to form the perforated zone (5). The screen is positioned in a complementary fashion to the perforated zone. Preferably, the first surface (21) of the glass sheet comprises a roughened zone (1) which is positioned in a complementary fashion to the perforated zone.The invention is typically implemented so that the glass article is positioned above the display device so that the first surface (21) of the glass sheet (2) faces the user and the second surface (22) of the glass sheet faces the display. Hence the ink layer (3) is deposited on the second surface (22) of the glass sheet (2) that faces away from the user. Accordingly, the light from a light source will therefore first pass through the ink layer through openings, then through the glass substrate and will then exit from the opposite face (21).For use within a dead front article, the thickness is preferably equal to or more than 3pm to suppress the transmission of the light from the display panel. With a thickness of the ink layer of 25pm or less, it is possible to suppress the narrowing of the viewing angle.When the display is Off, the discrete openings having such very limited size, allow the ink layer to perfectly hide the screen of the display device and the potential decorative roughened zone(s) provide(s) a very pleasant aesthetic experience to the user. In contrast, when the display is On, the user sees perfectly the image displayed on the screen via the perforated display zone, while hiding the ink layer. The size and position of the discrete openings are selected so that in a backlit state the image displayed by the screen is perfectly visible, while a sufficient dead front effect is established in the off state.For the dead front article of the present invention, the discrete openings have preferably a size equal to or lower than 60pm, preferably equal to or lower than 30 pm, preferably equal to or lower than 20 pm, more preferably equal to or lower than 10 pm. Preferably, the discrete openings are in the shape of lines having a width of less than 30pm (< 30pm), preferably of less than 20pm (< 20pm), more preferably less than 10pm (< 10pm).For the dead front article of the present invention, the glass sheet is preferably a thin glass to reduce the light optical path and therefore the reduce light reflection and improve clarity on diffuse areas. In a preferred dead front embodiment the thickness of the glass sheet is equal to or lower than 2mm, preferably equal to or lower than 1.6mm, more preferably equal to or lower than 1.3mm and even more preferably equal to or lower than 0.7mm.The glass may be flat or totally or partially curved to correctly fit with the particular design of the vehicle or the potentially glass support, as the shape requires for the application.Glass sheet productionThe glass article of the present invention can be rna^nufactujed_from_a lar^rjmoth ^lass_subsj:rate by the following method described in WO2017 / 038853 filed by Asahi Glass Co LTD under application number WO2016JP75415 on 31 August 2016 incorporated herein by reference. This method comprises: (1) a step for preparing a glass material which has a first main surface and a second main surface, said main surfaces opposing each other; (2) a step for laser-irradiating the first main surface of the glass material so that an in-plane void area, wherein a plurality of voids are aligned, is formed in the first main surface and, at the same time, a plurality of inner void rows consisting of one or morealigned voids are formed from the in-plane void area toward the second main surface; and (3) a step for subjecting the glass material, in which the inner void rows are formed, to a chemical strengthening treatment. Please refer to the step of providing the glass material : Step 110 described in

[0034] to

[0041] , to the step of laser filamentation : Step 130 described in

[0042] to

[0078] , to the step of chemical strengthening : Step 120 described un

[0079] to

[0093] and to the separattion step : step 140 described in

[0094] to

[0133] from the corresponding EP publication EP3345877A, all incorporated herein by reference.The method may further comprise a step of cold bending after the step of separating. The cold bending is particularly appreciated for bending glass articles for interior and exterior glazing part for automotive such as glass console, dashboard, trim element for door, pillars, windshields, side windows, back windows, sun roofs, separation walls,... Cold bending is any assembling operation in which an initially flat thin glass element is deformed into a final non-flat configuration in the assembly. The thin glass in the final assembly present a permanent unbalance of surface stresses between its two main surfaces. The assembling operation can be any kind of technology allowing to keep the thin glass in a non-flat configuration: gluing, laminating, mechanical retainers (screws, rivet, casing,...),..., applied either at punctual places or on the full surface. Preferably, for reasons of weight and to be able to cold bend easily the thickness of the glass article may be from 0.1 to 2.2 mm, 0.5 to 2.1 mm. When used within a deadfront article, the glass article typically covers display devices having a screen display diagonal of from 2.5cm to 25cm, preferably from 8cm to 40cm.Typically, the thickness of the glass sheet ranges from 0.5 to 25 mm. Preferably, the glass sheet has a sheet thickness of 2.0 mm or more, preferably of 3.0 mm or more, preferably of 3.5 mm or more, preferably of 4.5 mm or more; preferably of 5.5 mm or more, preferably of 7.5 mm or more, preferably of 9.5 mm or more and more preferably of 11.5 mm or more. Typically, the sheet thickness is of 20 mm or less, preferably 15 mm or less.1. Glass compositionThe composition of the glass is preferably appropriate to be chemically tempered and for transportation applications. The glass sheet may be a soda-lime-silicate glass, an alumino-silicate glass, an alkali-free glass, a boro-silicate glass, etc. Preferably, the glass sheet of the invention is made of a soda-lime glass or an alumino-silicate glass. The glass sheet according to the invention may be a glass sheet obtained by a floating process, a drawing process, a rolling process or any other process known to manufacture a glass sheet starting from a molten glass composition. The glass may be clear glass, extra-clear glass or colored glass, comprising one or more component (s) / colorant(s) in an appropriateamount as a function of the effect desired. Colored glass includes grey, green or blue float glass. In some circumstances, colored glass may be advantageous to provide for appropriate and desired color of the final glazing, within the limitations of applicable legislation.Soda-lime-silicate glass relates to any mineral glass which comprises the following components in weight percentage, expressed with respect to the total weight of glass (Comp. A). More preferably, the glass composition (Comp. B) is a soda-lime-silicate-type glass with a base glass matrix of the composition comprising the following components in weight percentage, expressed with respect to the total weight of glass.Other advantageous glass compositions for the mineral glass of the present invention, comprise the following components in weight percentage, expressed with respect to the total weight of glass:According to certain embodiments of the invention, the glass may have a composition comprising a total iron (expressed in terms of FejOa) content ranging from 0.002 to 0.06 weight%. A total iron (expressed in the form of FejOa) content of less than or equal to 0.06 weight% makes it possible to obtain a glass with almost no visible coloration. Preferably, the composition comprises a total iron (expressed in the form of FejOa) content ranging from 0.002 to 0.04 weight%. More preferably, the composition comprises a total iron (expressed in the form of FejOa) content ranging from 0.002 to 0.020 weight%. Advantageously, for extra-clear glass, the composition comprises a total iron (expressed in the form of FejOa) content ranging from 0.002 to 0.015 weight% for the lowest visible light absorption.2. Glass strengtheningThe glass sheet according to the invention can advantageously be strengthened : a heat strengthened glass, a thermally toughened glass, or a chemically strengthened glass.Heat strengthened glass is heat treated using a method of controlled heating and cooling which places the glass surfaces under compression and the glass core under tension. This heat treatment method delivers a glass with a bending strength greater than annealed glass but less than thermally toughened safety glass.Thermally toughened safety glass is heat treated using a method of controlled heating and cooling which puts the glass surface under compression and the glass core under tension. Such stresses cause the glass, when impacted, to break into small granular particles instead of splintering into jagged shards.Chemical strengthening of a glass article is a heat induced ion-exchange, involving replacement of smaller alkali sodium ions in the surface layer of glass by larger ions, for example alkali potassium ions. Increased surface compression stress occurs in the glass as the larger ions "wedge" into the small sites formerly occupied by the sodium ions. Such a chemical treatment is generally carried out by immerging the glass in an ion-exchange molten bath containing one or more molten salt(s) of the larger ions, with a precise control of temperature and time.3. Additional layersAccording to the application, intended use and / or properties desired, various layer(s) / treatment(s) can be deposited / done on the face of the glass article or glass sheet, that faces the user.Suitable coating may be a solar control coating, a low emissivity coating, an insulating coating, a conductive coating, an antireflective coating, an anti-fog coating, and the like. The single layers of the coating, may typically comprise one or more metals, non-metals, semi-metals, semiconductors, or alloys, compounds, composites, combinations and blends thereof. A single layer may have a physical thickness of from 0.5 nm to 500 nm, while a multilayer coating may have a total physical thickness of from 5 nm to 1000 nm. Examples of coatings may include dielectric coatings comprising multiple layers of dielectric materials. Dielectric materials may include metal oxides, nitrides, carbides, oxynitrides, oxycarbides, oxycarbonitrides, or the like.According to another embodiment of the invention, the glass article can be preferably coated with at least one antireflection layer. This embodiment is advantageous in the case of use of the glass article of the invention as front cover of a screen. An antireflection layer can, for example, be a layer based on porous silica having a low refractive index or it can be composed of several layers (stack), in particular a stack of layers of dielectric material alternating layers having low and high refractive indexes and terminating in a layer having a low refractive index. According to still another embodiment of the invention, the glass article has an antibacterial layer / treatment. Advantageously, according to this embodiment, the glass article has said antibacterial layer / treatment on the second surface that has been roughened. For example, such an antibacterial treatment could be a diffusion of silver ions in the bulk of the glass sheet close to the outer surface.Advantageously, according to one embodiment, the glass article has an anti-fingerprint layer and / or and / or easy to clean coating and / or treatment on the first surface of the glass sheet. In a preferred embodiment, the glass article has at least one anti-fingerprint layer / treatment so as to reduce or prevent fingerprints from registering. Anti-fingerprint (AFP) coating is a specialized surface treatment designed to reduce the visibility of fingerprints and smudges on surfaces. It is achieved by incorporating hydro- / oleophobic properties, making the surface hydrophobic (repelling water) and oleophilic (attracting oils), which minimizes fingerprint marks An anti-fingerprint coating may prove useful to avoid interferences of light from the viewing area. The fingerprints will be less visible from the outside, and provide for improved aesthetics. Examples of anti-fingerprint coatings include fluorinated polyethers, silanes, fluoro-silanes, siloxanes, fluorinated siloxanes, phosphonates, fluoro- organic compounds, perfluorocarbon-containing materials, and the like. These anti-fingerprint coatings are known in the art.The present invention also relates to methods for producing the glass article and for producing the dead front article of the present invention. The method comprises the following steps. Steps b) + c) and d) can be performed in any order : a) providing a glass sheet comprising a first surface and a second surface opposite to the first surface; b) depositing an ink layer on at least a portion, preferably on the entire area, of a second surface of a glass sheet; wherein the ink layer has a. a thickness value comprised between 1pm and 50pm; b. an average thickness and a standard deviation; c. wherein the standard deviation is equal to or lower than the lowest of either (a) 3pm (< 3pm) or (b) 20% (< 20%) of the average thickness. c) optionally, creating by laser ablation a perforated zone within the ink layer via discrete openings having dimension equal to or lower than 200pm. ; d) optionally, forming at least one roughened zone on the first surface of the glass.The laser ablation Step c) can be performed as soon as coating deposition step b) has occurred.In a preferred embodiment, optional step d) wherein the at least a roughened zone is formed can be achieved via an etching process comprising at least the steps of : i. disposing an etch resistant mask on a portion of the first surface of the glass sheet; ii. etching the first surface of the glass sheet to form a decorative pattern; ill. removing the etch resistant mask.In the embodiment wherein a roughened zones is created for decorative purposes, step d) can be repeated for each decorative roughened zone(s) to be formed.As described above, typically, the discrete openings will be typically created by directing a pulsed laser beam onto the ink layer to locally remove the ink layer by ablation, repeatedly at different locations, thereby producing a pattern of a multitude of discrete openings defining a perforated zone in the ink layer above the screen of the display device so that the ink layer becomes semi-transparent in the perforated zone.The present invention also relates to the use of the glass article and of the dead front article for car interior application, home appliances and / or integrated interactive display.The person skilled in the art realizes that the present invention is by no means limited to the preferred embodiments described above. On the contrary, many modifications and variations are possible within the scope of the appended claims. It is further noted that the invention relates to all possible combinations of features, and preferred features, described herein and recited in the claims or in the described embodiments.It is well understood by persons skilled in the art that, as used herein the terms "a", "an" or "the" means at least "one" and should not be limited to "only one" unless explicitly stated otherwise. As used herein, spatial or directional terms, such as "inner", "outer", "above", "below", "top", "bottom", and the like, relate to the invention as it is shown in the drawing figures. However, it is to be understood that the invention can assume various alternative orientations and, accordingly, such terms are not to be considered as limiting. Further, all numbers expressing dimensions, physical characteristics, processing parameters, quantities of ingredients, reaction conditions, and the like, used in the specification and claims are to be understood as being modified in all instances by the term "about". Accordingly, unless indicated to the contrary, the numerical values set forth in the following specification and claims are approximations that can vary depending upon the desired properties sought to be obtained by the present invention. In the following description, unless otherwise specified, expression "substantially" mean to within 10%, preferably to within 5%.Furthermore, the terms first, second and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequence, either temporally, spatially, in ranking or in any other manner. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein. When it is described that a constituent element (e.g., a first constituent element) is "(functionally or communicatively) coupled to" or is "connected to" another constituent element (e.g., a second constituent element), it should be understood that the constituent element may be directly connected to the another constituent element or may be connected to the another constituent element through another constituent element (e.g., a third constituent element).EXAMPLESExample 1 : Glass article of the present inventionA glass sheet of 1.1mm thickness (8cm x 20cm) of a type of alumino-silicate glass composition sold under the Trademane 'Falcon Glass' by AGC Glass Europe was washed with an aqueous detergent and dried.An ink layer was applied to the second surface of the glass sheet covering 100% of the second surface. The ink layer is an organic black ink material that was deposited by silk screen printing in a layer of 10pm thickness. As very commonly performed by persons skilled in the art, the ink viscosity and printing processing parameters have been adjusted to provide a ink layer of uniform thickness :The lowest limit between Bpm limit and the 20% of the average thickness limit, is the 20% of the average thickness limit being 1.96 pm. The standard deviation is 1.54pm and therefore lower than the lowest of either (a) Bpm or (b) 20% of the average thickness limits.Discrete opening in the form of parallel lines are obtained by laser decoating to create a perforated zone within the coating. The discrete openings are in the form of straight lines with a width of about 25 pm and the distance between the lines is set at 60 pm. The decoating process is done with a lasersource with pulse duration of 10 ps and wavelength of 1064nm. The laser beam has Gaussian profile. The laser beam is coupled to a galvo scanner equipped with an f-theta lens, which has a focal length of 100 mm. The laser beam diameter at the focus of the lens is approximately 20 um. The other laser parameters are as follows: pulse repetition rate 1 MHz, average power 16 W, scanning velocity 2750 mm / s.Figure 5(b) is a 2D microscope image of a glass article (A) with the ink layer (3) of the present invention. The ink layer (3) has been decoated by laser ablation. Discrete openings (4) in the shape of straight lines (in dark grey) have been achieved. The first surface of the glass sheet can be seen through the line openings - dark grey in the picture. The surface of the remaining ink layer can be seen in the picture in medium grey and the remaining ink is also in the shape of straight lines. As it can be seen in Figure 5(b) the remaining ink lines are of uniform thickness without any ink bumps and therefore the decoated lines of discrete openings (4) are very uniform in width.When the glass article was used in a dead front article, the perforated zone was created to cover the entire surface of the screen. In Figure 6 (b), the glass article of the present invention is used in combination with a display device to form a dead front article. The rendering of the image when the dead front article is in the ON mode is of high quality and hardly any of the ink layer remains visible.Example 2 : Glass article of the present inventionExample 1 was repeated and the ink layer was deposited by silk screen printing in a layer of 30pm thickness. The ink viscosity and printing processing parameters have been adjusted to provide a ink layer:The lowest limit between 3pm limit and the 20% of the average thickness limit is the 3pm limit. The standard deviation is 2.29 pm and therefore lower than the lowest of either (a) 3pm or (b) 20% of the average thickness limits. Example 3 : comparative exampleComparative example 3 refers to the same glass sheet have the same ink layer deposited on the second surface and wherein the same perforated zone is created by the same laser ablation process than in example 1. However, because of the ink viscosity and / or printing processing conditions, the ink layer is not sufficiently uniformly deposited on the glass sheet. It is characterized by the following thickness values :The lowest limit between 3pm limit and the 20% of the average thickness limit is the 20% of the average thickness limit being 2.05 pm. The standard deviation is 2.15 pm and therefore higher than the lowest of either (a) 3pm or (b) 20% of the average thickness limits.Figure 5(a) is a 2D microscope image of a comparative glass article. The "ink medium grey lines" comprises spots of lighter color (3a) indicating ink bumps of higher thickness. As it can be seen in Figure 5 (a) they are many 'ink bumps' that rends laser decoating non uniform with line decoating of highly variable thickness, resulting in discrete openings of very poor sharpness. In Figure 6(a), the comparative glass article is used in combination with a display device to form a dead front article. The rendering of the image when the dead front article is in the ON mode is of low quality with portion of ink layer remaining visible.

Claims

CLAIMS1. A glass article (A) comprising : a) a glass sheet (2) comprising a first surface (21) and a second surface (22) opposite to the first surface; b) an ink layer (3) disposed on at least a portion of the second surface of the glass sheet, wherein the ink layer has : o a thickness value comprised between 1pm and 50pm; o an average thickness and a standard deviation; o wherein the standard deviation is equal to or lower than the lowest of either (a) 3pm or (b) 20% of the average thickness.

2. A glass article according to claim 1 wherein the standard deviation is equal to or lower than the lowest value of either (a) 2pm or (b) 10%, preferably 5%, more preferably 2% of the average thickness.

3. A glass article according to any one of the preceding claims wherein the ink layer is an organic based ink, preferably an acrylic ink or an epoxy ink.

4. A glass article according to any one of the preceding claims wherein the ink layer has a thickness of equal to or greater than 2pm (> 2pm), preferably equal to or greater than 3pm (> 3pm), more preferably equal to or greater than 5pm (> 5pm) and / or equal to or lower than 40pm (< 40pm), preferably equal to or lower than 30pm (< 30pm), preferably equal to or lower than 25pm (< 25pm), preferably equal to or lower than 20pm (< 20pm), preferably equal to or lower than 15pm (< 15pm), more preferably equal to or lower than 12pm (< 12pm).

5. A glass article according to any one of the preceding claims wherein the ink layer has a light transmittance equal to or lower than 50% (TLD4 < 50%), preferably equal to or lower than 30% (TLD4 < 30%), preferably equal to or lower than 10% (TLD4 < 10%), preferably equal to or lower than 5% (TLD4 < 5%) and more preferably equal to or lower than 2% (TLD4 < 2%) wherein TLD4 is determined according to the IS09050 standard for a thickness of 4 mm at a solid observation angle of 2° (with illuminant D65) and for a wavelength range between 380 and 780 nm.

6. A glass article according to any one of the preceding claims wherein the ink layer further comprises a perforated zone (5) comprising discrete openings (4) having dimension equal to or lower than 200pm.

7. A glass article according to claim 6 wherein the discrete openings are spaced from each other by a spacing distance equal to or lower than 200pm, preferably equal to or lower than 150pm, more preferably by a distance equal to or lower than 100pm.

8. A glass article according to any one of the preceding claims 6 to 7 wherein the discrete opening are in the shape of lines having a width (W) equal to or lower than 30pm (W < 30pm), preferably equal to or lower than 20pm (W < 20pm), preferably equal to or lower than 10pm (W < 20pm).

9. A glass article according to any one of the preceding claims wherein the first surface further comprises at least one decorative roughened zone bordered by a border area; wherein the least one decorative roughened zone has a mean surface roughness defined by an arithmetic amplitude value, Ra(ZOne) and defined by a spacing value, RSITIfzone); wherein the border area has a mean surface roughness defined by an arithmetic amplitude value, Rajborder), and defined by an spacing value, Rsmjborder), and wherein the absolute difference between Ra(ZOne) and Rajborder) is at least 25nm ( | Rajzone) - Rajborder) | > 25nm) and / or the absolute difference between RsmjZOne) and Rsmjborder) is at least 2pm ( I Rsmjzone) - Rsmjborder) | > 2pm).

10. A glass article according to any one of the preceding claims wherein the glass sheet is a strengthened glass sheet, preferably a chemically strengthened glass sheet.

11. A glass article according to any one of the preceding claims wherein the first surface of the glass sheet is coated with an anti-finger print coating and / or an anti-reflective coating.

12. A glass article according to any one of the preceding claims wherein the thickness of the glass sheet is equal to or lower than 2mm, preferably equal to or lower than 1.6mm, more preferably equal to or lower than 1.3mm.

13. A dead front article (B) comprising the glass article (A) according to any one of the preceding claims 6 to 13 and at least a display device having at least a screen (6) whereinthe second surface (22) of the glass sheet is facing the display device and wherein the perforated zone (5) is positioned in a complementary fashion to the screen.

14. A dead front article according to claim 13 wherein the first surface comprises further at least one roughened zone (1) positioned in a complementary fashion to the perforated zone.

15. A dead front article according to claim 14 wherein the at least one roughened zone provides a clarity equal to or lower than 80%, preferably equal to or lower than 50%, more preferably equal to or lower than 30%.

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