COVER GLASS SHEET HAVING DIFFERENTIAL TEXTURE - Patent application

Abstract

The present invention relates to a cover glass sheet (10) configured to cover at least one display device, having an outer sheet surface and an inner sheet surface, the inner sheet surface facing the display device and comprising a layer of opaque paint, the outer sheet surface defining a) at least one viewing zone (1) that allows visualization of at least a portion of the screen of the display device, the viewing zone (1) being defined by a boundary line P display b) at least one opaque zone (2) corresponding to said layer of opaque paint and directly surrounding at least 10 to 100% of the display boundary, said opaque zone having an opaque arithmetic amplitude value Ra (op) The outer sheet surface further comprises at least one textured zone (3) covering 0.5% to 99.5% of the opaque zone, said textured zone directly surrounding at least 5% of the display boundary and having a textured arithmetic amplitude value Ra (tex) The average surface roughness is defined as: Ra (op) and Ra (tex) The absolute difference between is at least 25 nm.

Description

[Technical field]

[0001] The present invention relates to a cover glass sheet for display applications that exhibits excellent optical properties while being aesthetically pleasing. [Background technology]

[0002] It is well known to use cover glass on a display to provide the necessary protection of the display. In some display applications, such as displays for the automotive industry, the cover glass sheet is generally larger than the display and is specially designed to be attached to a specific location in the automobile, such as the dashboard, the center armrest, the door armrest, etc. In such applications, the cover glass sheet can be much larger than the display. The design and aesthetics in such applications are very important to obtain commercial success.

[0003] To maximize the functionality of the display device, the surface of the cover glass sheet above the display screen is typically textured to improve its optical properties, such as reducing glare and flashing. A smooth, glossy, and black appearance is typically expected on the remaining surfaces of the cover glass sheet.

[0004] Thus, such a cover glass sheet, larger than the display device, which is protected and partially textured to improve the display device's functionality, would result in unacceptable differences in rendering between the zones of the cover glass sheet covering the display device and the zones not covering the display device, especially when the display is turned off. This difference in appearance would be further increased if the zones of the cover glass sheet not covering the display device were smooth and glossy for decorative purposes. Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention therefore addresses the technical problem of balancing the rendering of a partially textured cover glass while maintaining its excellent optical properties. [Means for solving the problem]

[0006] The present invention relates to a cover glass sheet configured to cover at least one display device. The cover glass sheet has an outer sheet surface and an inner sheet surface, the inner sheet surface facing the display device and including a layer of opaque paint. The outer sheet surface comprises: i. at least one display zone that allows at least a portion of the screen of the display device to be visualized, the display zone having a boundary line P display A display zone having ii. at least one opaque zone corresponding to said layer of opaque paint and immediately surrounding at least 10-100% of the display boundary line, said opaque zone having an opaque arithmetic amplitude value Ra (op) An opaque zone having an average surface roughness defined by Includes.

[0007] The outer sheet surface further includes at least one textured zone covering 0.5% to 99.5% of the opaque zone, the textured zone directly surrounding at least 5% of the display boundary and having a textured arithmetic amplitude value Ra (tex) The average surface roughness is defined as Ra (op) and Ra (tex) The absolute difference between (op) -Ra (tex) |≧25 nm).

[0008] 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 drawings]

[0009] [Figure 1a]1 shows a plan view of a cover glass sheet according to one embodiment of the present invention, where an opaque zone completely surrounds a viewing zone, and a textured zone disposed within the opaque zone completely surrounds the viewing zone. [Figure 1b] FIG. 1b shows a cross-sectional view of a display unit including the cover glass sheet of FIG. 1a along line AA'. [Diagram 2] 1 shows a plan view of a cover glass sheet according to one embodiment of the present invention, where the display device has a polyhedral shape and the opaque zones and corresponding textured zones differ in shape from the display zones. [Diagram 3] 1 shows a plan view of a rectangular cover glass sheet according to one embodiment of the present invention, including two opaque zones disposed on either lateral side of a rectangular viewing zone, each of which includes a thin textured zone adjacent to the lateral side of the viewing zone. [Figure 4] 1 shows a plan view of a cover glass sheet according to one embodiment of the present invention, where a layer of opaque paint defining a corresponding opaque zone on the outer sheet surface of the cover glass sheet is added only to a portion of the inner sheet surface of the cover glass sheet. [Diagram 5] 1 shows a plan view of a cover glass sheet according to one embodiment of the present invention, including a display zone, an opaque zone, and a textured zone, as well as a second textured zone. [Figure 6] 1 shows a plan view of a cover glass sheet according to one embodiment of the present invention, the cover glass sheet including several display zones and their corresponding textured zone or zones, as well as several second textured zones. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] It is an object of the present invention to provide a cover glass sheet for use in display applications that provides excellent optical performance while maintaining excellent aesthetic properties.

[0011] The present invention addresses the technical problem of rendering differences between a viewing zone, which is textured to obtain good optical properties, and an opaque zone, which is preferably black and shiny. This is especially evident when the display device is switched off. The invention is therefore based on defining at least a third zone, hereafter called "textured zone", on the outer surface of the cover glass sheet, partially covering the opaque zone and positioned around the viewing zone. Such a third zone is textured such that its average surface roughness is different from that of the opaque zone. The addition of such a textured zone on the opaque zone around the viewing border significantly reduces the rendering differences and thus significantly improves the aesthetics of the cover glass sheet while maintaining good optical performance.

[0012] The viewing zone on the outer surface of the cover glass sheet allows the display device to be visualized. Therefore, the surface of the viewing zone is usually textured to provide good optical performance, such as anti-glare and / or anti-flashing properties. There is also an increasing demand in the display market to combine anti-glare / anti-flashing solutions for cover glass sheets with a comfortable and smooth tactile feel (often referred to as satin, silk or soft touch). Except for the viewing zone, the inner sheet surface of the cover glass sheet is generally covered completely or partially by an opaque layer to provide a dark appearance. As a result, the opaque zone, on the outer surface of the cover glass sheet, on which the corresponding opaque zone is defined, usually has a smooth and glossy surface, especially when used in automotive applications. When the display device is turned off, both the viewing zone and the opaque zone darken and thus absorb light radiation. However, the rendering between these two zones is very different. In fact, the opaque zone absorbs light radiation to a large extent, while the viewing zone absorbs light radiation but also reflects and diffuses it. Such a difference in reflection gives a rendering difference. This rendering difference becomes more noticeable depending on the relative position of the user with respect to the display unit. In fact, the more the user's field of view is tilted, the more problematic the rendering difference becomes. Surprisingly, it has been found that such rendering difference can be significantly mitigated by a careful and specifically positioned texturing of the opaque zone. The invention is based on the surprising technical discovery that this reflection difference between the opaque zone and the display zone can be significantly reduced by texturing a portion of the opaque zone around the display border. The specific texture of such a textured zone significantly increases the diffusion of the reflection on the outer surface of the cover glass sheet. The light interaction difference on the inner surface is hidden, so that the rendering difference is significantly mitigated while allowing the optical performance of the display zone to be maintained, especially when viewed at an oblique angle. It is further an object of the invention to texture a portion of the opaque zone in a different way depending on the relative position of the user to the display unit.

[0013] The present invention relates to a cover glass sheet configured to cover one or more display devices. The cover glass sheet has an outer sheet surface and an inner sheet surface, the inner sheet surface facing the one or more display devices.

[0014] For the avoidance of doubt, the term "surrounding" as used herein means "surrounding the outside." As shown in Figure 1a, the cover glass sheet (10) comprises the following zones on its outer sheet surface: (a) at least one display zone (1) making it possible to visualize the screen of a corresponding display device. Each display zone is bounded by a border P display The size and shape of the display zone may correspond to or differ from the size and shape of the display screen, e.g., the size may be smaller and / or the shape may have any shape while the display may remain conventional. In some examples, it may be more convenient and cost-effective to create a circular or any other shaped display field by designing one or more circular or any other shaped display zones on a conventional rectangular display device, as long as it allows visualization of part or all of the display screen. (b) at least one opaque zone (2) corresponding to a layer of opaque paint added to the inner sheet surface. By definition, such a layer of opaque paint is added to the inner sheet surface except the indicia zone. It can be added to all or a part of the remaining inner sheet surface. It surrounds 10 to 100% of the indicia boundary line. If there are several opaque zones, all opaque zones preferably have the same opaque arithmetic amplitude value Ra (op)In a preferred embodiment, the layer of opaque paint directly surrounds at least 25%, at least 50%, preferably 75%, more preferably 90%, even more preferably 100% of the display boundary. Corresponding to each display zone is at least one opaque zone. An opaque zone is a zone on the outer sheet surface of the cover glass sheet defined by a corresponding zone of the inner sheet surface to which a layer of opaque paint is added. It does not cover the display zone. It may further cover all or only a part of the remaining surface of the inner sheet surface. The outer sheet surface of the cover glass sheet may have a plurality of opaque zones on each lateral side of the rectangular display zone, as depicted in FIG. 3, for example. (c) at least one textured zone (3) covering 0.5% to 99.5% of the opaque zone. In one embodiment, the textured zone preferably covers 1% to 75% of the opaque zone, more preferably 2% to 60%, even more preferably 5% to 50% of the opaque zone. In another embodiment, the textured zone preferably covers 80% to 99.5% of the opaque zone, preferably 90% to 98% of the opaque zone, even more preferably 92% to 95% of the opaque zone. The textured zone is positioned around and in direct contact with the display border, thus directly surrounding at least 5%, better still 10%, preferably 25%, more preferably 50%, even more preferably 75%, even more preferably 90%, and ideally 100% of the display border. The average surface roughness of the textured zone is determined by the textured arithmetic amplitude value Ra (tex) The outer sheet surface of the cover glass sheet may have a plurality of textured zones, as depicted in Figure 3, with the opaque zone encompassing the textured zone on each lateral side of the rectangular viewing zone. The textured zones may have any shape, and do not necessarily conform to the shapes of the viewing zone and the opaque zone as shown in Figure 2. In some embodiments, it may also occur that the textured zone extends outside the opaque zone.

[0015] The cover glass sheet of the present invention has a Ra (op) and Ra (tex) The absolute difference between (op) -Ra (tex) |≧25 nm), preferably at least 50 nm (|Ra (op) -Ra (tex) |≧50 nm), more preferably at least 100 nm (|Ra (op) -Ra (tex) |≧100 nm), and even more preferably at least 200 nm (|Ra (op) -Ra (tex) The opaque zone is defined as a region having an opaque arithmetic amplitude value Ra (op) and the textured zone has an average surface roughness defined by a textured arithmetic amplitude value Ra (tex) For the avoidance of doubt, Ra (op) is not measured in the opaque zone which is further textured to become the textured zone. (op) and Ra (tex) The absolute difference between is 2 microns or less, preferably 1 micron or less.

[0016] In one embodiment, which is preferred for aesthetic reasons and / or ease of processing, the display zone has an average surface roughness Ra of the textured zone. (tex) The average surface roughness is defined by the indicated arithmetic amplitude value Rad (Rad=Ra (tex) ). The typical average surface roughness Ra(op) of the opaque zone is between 0.1 nm and 5 nm, preferably between 0.1 nm and 3 nm. The typical average surface roughness Ra(tex) of the textured zone is between 0.025 microns and 2 microns, preferably between 0.05 microns and 1 micron, more preferably between 0.1 microns and 1 micron. The typical average surface roughness Rad of the display zone is between 0.05 microns and 2 microns, preferably between 0.1 microns and 1 micron.

[0017] In a preferred embodiment of the present invention, the cover glass sheet may include at least one second textured zone (4) indirectly surrounding the display border. The second textured zone is contained within the opaque zone but is not in direct contact with the display border. The second textured zone has a second textured arithmetic amplitude value Ra2 (tex) Preferably, the surface roughness is defined as Ra (op) and Ra2 (tex) The absolute difference between (op) -Ra2 (tex) |≧25 nm), more preferably at least 50 nm (|Ra (op) -Ra2 (tex) |≧50 nm), and even more preferably at least 100 nm (|Ra (op) -Ra2 (tex) |≧100 nm), and even better at least 200 nm (|Ra (op) -Ra2 (tex) |≧200 nm). It has been found that such a second textured surface contributes positively to the overall aesthetic performance of the cover glass sheet and further mitigates rendering differences. Furthermore, it has been found that the addition of one or more second textured zones can be used to provide guidance for the user's finger to reach and activate functions on the display. In a preferred embodiment, at least one second textured zone covers 5% to 90% of the opaque zone, preferably 5% to 75% of the opaque zone, preferably 5% to 60% of the opaque zone, more preferably 5% to 50% of the opaque zone. In a preferred embodiment for aesthetic reasons and / or ease of processing, the average surface roughness Ra2 of the second textured zone is 0.01 mm. (tex) is the average surface roughness Ra1 of the textured zone (tex) In another preferred embodiment, the second textured arithmetic amplitude value Ra2 (tex) is equal to the indicated average surface roughness Rad (Ra2 (tex) =Rad).

[0018] The cover glass sheet of the present invention is configured to cover one or more display devices, each of which defines an individual display zone having a respective display border. One or more opaque zones may correspond to each display zone on the outer sheet surface of the cover glass sheet. One or more textured zones may correspond to each opaque zone on the outer sheet surface of the cover glass sheet. The opaque zones may further include one or more second textured zones. Thus, when reference is made to technical features characterizing a display zone, an opaque zone, a textured zone and / or a second textured zone, this should be understood to apply to all display zones, opaque zones, textured zones and second textured zones of the cover glass sheet of the present invention.

[0019] Detailed explanation of the figure FIG. 1a shows one embodiment of the present invention, in which a cover glass sheet (10) is configured to cover a rectangular display device and has a display zone (1). The opaque zone (2) is defined by opaque paint added to all inner sheet surfaces of the cover glass sheet, not the display zone. The display zone (1) is slightly smaller than the surface of the display screen. The opaque zone (2) immediately surrounds 100% of the display boundary. The textured zone (3) also immediately surrounds 100% of the display boundary and is completely contained within the opaque zone. FIG. 1b shows a cross-sectional view of a display unit (20) including the cover glass sheet of FIG. 1a (10) and a display device (30) along line A-A'. As depicted in FIG. 1b, the inner surface of the cover glass sheet (7) is covered by a layer of opaque paint (5) that defines an opaque zone (2) on the corresponding surface on the outer surface of the cover glass sheet (6). It can be seen that the opaque paint covers a small portion of the inner sheet on the display screen, and therefore the display zone is slightly smaller than the surface of the display screen. The textured zone (3) immediately surrounds the display border and is entirely contained within the opaque zone.

[0020] FIG. 2 shows a variation of the embodiment of FIG. 1a, in which the textured zone (3) has a different shape than the display zone (1).

[0021] Figure 3 shows one embodiment of the present invention, where a cover glass sheet (10) is configured to cover a rectangular display device and has one viewing zone (1). Opaque paint is added to all inner sheet surfaces of the cover glass sheet, but not to the viewing zone, and defines two opaque zones (2) immediately surrounding the lateral sides of the viewing boundary. Two textured zones (3) also immediately surrounding the lateral sides of the viewing boundary, each fully contained within a corresponding opaque zone.

[0022] Figure 4 shows one embodiment of the present invention, where a cover glass sheet (10) is configured to cover a rectangular display device and has one viewing zone (1). An opaque zone (2) is defined by opaque paint added to only a portion of the remaining inner sheet surface, excluding the viewing zone. The opaque zone immediately surrounds three sides of the rectangular viewing boundary. Two textured zones (3) immediately surround the lateral sides of the viewing boundary.

[0023] Figure 5 shows one embodiment of the present invention, where a cover glass sheet (10) is configured to cover a rectangular display device and has one display zone (1). An opaque zone (2) is not a display zone, but is defined by opaque paint added to all inner sheet surfaces of the cover glass sheet, and immediately surrounds 100% of the display boundary. Two textured zones (3) immediately surround the lateral sides of the display boundary and are completely contained within the opaque zone. The outer sheet surface of the cover glass sheet further includes several second textured zones (4) contained within the opaque zone.

[0024] FIG. 6 shows an embodiment of the present invention, in which a cover glass sheet (10) is configured to cover several display devices having their respective viewing zones (1a), (1b), (1c) and (1d). The opaque zone (2) is defined by opaque paint added to only a portion of the remaining inner sheet surface, excluding the viewing zones. In fact, a small portion of the inner sheet surface on the cover glass sheet is not covered by the opaque paint. The opaque zone immediately surrounds about 65% of the viewing boundary of the viewing zone (1b) and completely surrounds the viewing boundary of the viewing zones (1a), (1c) and (1d). The textured zone (3a) immediately surrounds about 50% of its respective viewing boundary and is completely contained within the opaque zone. The textured zone (3b) immediately surrounds about 65% of its respective viewing boundary and is completely contained within the opaque zone. The textured zones (3c) and (3d) immediately surround 100% of their respective viewing boundary and are completely contained within the opaque zone. The cover glass sheet further comprises several second textured zones (4) indirectly surrounding the display border.

[0025] The invention also relates to a display unit comprising the cover glass sheet described above and a display device positioned below the display zone. Preferably, the display unit further comprises an optical joint arranged between the display device and the inner sheet surface of the cover glass sheet.

[0026] The present invention relates to the use of cover glass sheets or display units for automotive interior applications, consumer electronics and / or integrated interactive displays. The cover glass sheets and display units according to the present invention are particularly suitable for vehicle interior glazing, such as consoles, dashboards, automotive exterior windows, glass trim elements, etc., where more complex shapes are required by automotive manufacturers.

[0027] Overview For display applications, it is known to texture the outer surface of the cover glass sheet to provide anti-glare and / or anti-flash performance as well as a certain gentle tactile feel. According to the present invention, the outer sheet surface of the cover glass sheet is textured. By "textured surface" we mean a surface that has been treated by mechanical or chemical methods to remove a certain amount of glass material and impart a certain surface texture / roughness. We describe chemically etched glass where material removal occurs by chemical reaction / treatment (i.e. acid etching). We describe mechanically etched glass where material removal occurs by mechanical reaction / treatment (i.e. sandblasting). Chemical etching (i.e. using HF and / or fluoride compounds) is preferred as it allows the achievement of a roughness and, therefore, optical properties and aesthetics that are appropriate for the target application.

[0028] The textured surface of a glass sheet is usually characterized by its surface texture or roughness, and in particular by the Ra value (expressed in microns or nm) defined in the standard ISO 4287-1997. The texture / roughness is the result of the presence of surface irregularities / patterns. These irregularities consist of protuberances, 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", also called "mean line" (algebraic mean). For measurements in a profile and along a fixed length (called "evaluation length"), Ra (amplitude value) corresponds to the average difference of the texture, which means the arithmetic mean of the absolute value of the difference between the peaks and the valleys. Ra measures the distance between this mean and the "line" and gives an indication of the height of the pattern on the textured surface.

[0029] The roughness value according to the invention can be measured by a profilometer using a 2D profile (according to the ISO4287 standard). Alternatively, one can use techniques of 3D profilometry (according to the ISO25178 standard) that later give access to the parameters defined in the ISO04287 standard, in isolation from the 2D profile. According to the invention, the roughness value is measured by a Gaussian filter, which is a long wavelength filter also called profile filter λc. It is used to separate the roughness / texture component from the waviness component of the profile. The evaluation length L according to the invention is the length of the profile used to evaluate the roughness. The base length l is the part of the evaluation length used to identify the irregularities that characterize the profile to be evaluated. The evaluation length L is divided / cut into n base lengths l, which depend on the irregularities of the profile. The base length l corresponds to the "cut-off" wavelength (or limit wavelength) of the Gaussian filter (l=λc). Typically, the evaluation length has at least 5 times the base length. In roughness metrology, a short wavelength filter (profile filter λs) is also commonly used to remove the effects of very short wavelengths that are background noise.

[0030] In order to generate a differential average surface roughness between the display zone, the opaque zone, the textured zone and / or the second textured zone, the partial texture can be generated by any known method that allows selectively texturing the glass surface and thereby generating one or more textured zones. For example, when considering generating the texture according to the invention by chemical etching, known methods can be used that use a protective mask that is resistant to the chemical etching process and that is subsequently removed, thereby allowing only certain parts / zones of the glass surface to be exposed to the etching process. The resulting etched texture zones on the glass surface correspond to the negative of the previously applied mask.

[0031] The cover glass sheet of the present invention is a) providing a partially textured mother glass substrate having opposed first and second major surfaces, the partial texture typically being present on the first major surface (and may also be present on the second major surface or both); b) irradiating at least a first major surface of the glass substrate with a laser to form at least one separation line on the first major surface, the separation line defining a contour line and extending in a depth direction from the first major surface to the second major surface, to separate at least one cover glass sheet from the glass substrate, the cover glass sheet having a size smaller than that of the mother glass substrate; c) separating the at least one partially textured cover glass sheet from the mother glass substrate according to at least one separation line; In turn, the glass substrate can be made from a larger mother glass substrate by a process that includes:

[0032] The above method may comprise a further step, after the irradiation step b) and before the separation step c), in which the mother glass substrate is chemically strengthened. This embodiment is advantageous in order to make it possible to strengthen the cover glass sheet or sheets at its main surfaces and also at its edges. The cover glass sheets are therefore more resistant to scratching and mechanical stresses / loads. According to this embodiment, after the mother glass substrate is chemically strengthened, (i) the level of potassium (or the most aggressive ion) at the first and second main surfaces of the cover glass sheet or sheets is greater than the level of potassium (or the most aggressive ion) at the edges of the cover glass sheet or sheets, and (ii) the level of potassium at the edges of the cover glass sheet or sheets is greater than the level of potassium in the bulk of the cover glass sheets. As the level of potassium at the edge faces of the cover glass sheet or sheets increases during chemical strengthening, they are more resistant to external load stresses.

[0033] The conditions of chemical strengthening are not particularly limited. Chemical strengthening can be performed, for example, by immersing the mother glass substrate in a molten salt at 380°C to 500°C for 1 minute to 72 hours. As the molten salt, a nitrate can be used. For example, when the lithium ions contained in the glass substrate are replaced by larger alkali metal ions, a molten salt containing at least one of sodium nitrate, potassium nitrate, rubidium nitrate, and cesium nitrate can be used. Furthermore, when the sodium ions contained in the glass substrate are replaced by larger alkali metal ions, a molten salt containing at least one of potassium nitrate, rubidium nitrate, and cesium nitrate can be used. Furthermore, when the potassium ions contained in the glass substrate are replaced by larger alkali metal ions, a molten salt containing at least one of rubidium nitrate and cesium nitrate can be used. In addition, one or more types of salts such as potassium carbonate can be further added to the molten salt. In this case, a low-density layer having a thickness of 10 nm to 1 μm can be formed on the surface of the mother glass substrate.

[0034] By applying a chemical strengthening treatment to a mother glass substrate, in which at least one separation line defines the contour line of at least one cover glass sheet, a compressive stress layer can be formed at the first and second major surfaces of the glass substrate and at the edge of one or more glass articles. The thickness of the compressive stress layer corresponds to the penetration depth of the alkali metal ions for substitution. For example, when potassium nitrate is used to substitute sodium ions by potassium ions, the thickness of the compressive stress layer can be 5 μm to 50 μm for soda-lime glass, and the thickness of the compressive stress layer for aluminosilicate glass is 10 μm to 100 μm. For aluminosilicate glass, the penetration depth of the alkali metal ions is preferably 10 μm or more, more preferably 20 μm or more.

[0035] The method may further comprise a step of cold bending after the separation step c). Cold bending is understood to be intended for bending glass articles, especially for interior and exterior glazing parts of automobiles, such as glass consoles, dashboards, trim elements for doors, pillars, windshields, side windows, back windows, sunroofs, separation walls, etc. Cold bending is any assembly operation in which initially flat thin glass elements are transformed into a final non-flat configuration during assembly. The thin glass in the final assembly presents a permanent imbalance of surface stresses between its two main surfaces. The assembly operation may be any kind of technique that allows to maintain the thin glass in a non-flat configuration, such as gluing, laminating, mechanical retainers (screws, rivets, casings, etc.) applied in point-like places or over the entire surface.

[0036] The cover glass sheet obtained by the above method is characterized in that it has at least one edge exhibiting an angle formed between the first and second major surfaces, each of which is equal to 90°±7°. Furthermore, the cover glass sheet obtained by the above method exhibits a level of potassium at the first and second major surfaces of the glass article that is greater than the level of potassium at the edge of the glass article, which level of potassium at the edge of the glass article is greater than the level of potassium in the bulk of the cover glass sheet. With an increased level of potassium at the edge of the article, the edge will have a greater mechanical resistance.

[0037] The cover glass sheet according to the invention may have a thickness of 0.03 to 19 mm, preferably 0.03 to 6 mm. Preferably, for weight reasons and to allow easy low-temperature bending, the thickness of the cover glass sheet may be 0.1 to 2.2 mm, 0.5 to 2.1 mm. The cover glass sheet usually covers a display device having a display diagonal of 8 cm to 25 cm, preferably 8 cm to 40 cm.

[0038] The opaque paint that is added onto the inner sheet surface of the cover glass sheet can be an enamel compound, an epoxy-based compound, or a polyurethane-based compound.

[0039] The cover glass sheet according to the invention is made from a glass whose matrix composition is not particularly limited and which can therefore belong to different categories. The glass can be soda-lime-silicate glass, alumino-silicate glass, alkali-free glass, boro-silicate glass, etc. Preferably, the glass sheet according to the invention is made from soda-lime glass or alumino-silicate glass.

[0040] According to one embodiment of the invention, the glass sheet has a composition comprising, in contents expressed as percentages of the total weight of the glass, the following: SiO255~85% Al2O30-30% B2O30~20% Na2O 0~25% CaO 0~20% MgO 0~15% K2O 0~20% BaO 0~20%

[0041] In one preferred embodiment, the glass sheet has a composition comprising, in contents expressed as percentages of the total weight of the glass, the following: SiO255~78% Al2O30-18% B2O30-18% Na2O 5~20% CaO 0~10% MgO 0~10% K2O 0~10% BaO 0~5%

[0042] In a more preferred embodiment, the glass sheet has a composition comprising, in contents expressed as percentages of the total weight of the glass, the following: SiO265~78% Al2O30-6% B2O30-4% CaO 0~10% MgO 0~10% Na2O 5~20% K2O 0~10% BaO 0~5%

[0043] In an alternative more preferred embodiment, the glass sheet has a composition comprising, in contents expressed as percentages of the total weight of the glass: SiO255~70% Al2O3 6-18% B2O30-4% CaO 0~10% MgO 0~10% Na2O 5~20% K2O 0~10% BaO 0~5%

[0044] Ideally, according to these last two embodiments, the glass composition is free of B2O3 (meaning that it is not added intentionally, but may be present in very small amounts as an undesirable impurity). Such two soda-lime type base glass composition embodiments have the advantage of being inexpensive, although they consequently have only poor mechanical resistance.

[0045] According to an advantageous embodiment of the invention, which can be combined with the above-mentioned embodiments in the base glass composition, the glass sheet has a composition comprising a total iron content (expressed in terms of Fe2O3) in the range of 0.002 to 0.06% by weight. A total iron content of 0.06% by weight or less (expressed in the form of Fe2O3) makes it possible to obtain glass sheets that have almost no visible coloration and allow a high level of flexibility in aesthetic design (for example, no distortion occurs during white silk printing of some glass elements of smartphones). The minimum value makes it possible not to end up penalizing too much for the cost of the glass, although small iron values ​​often require expensive and very pure starting materials and further purification of these. Preferably, the composition comprises a total iron content (expressed in the form of Fe2O3) in the range of 0.002 to 0.04% by weight. More preferably, the composition comprises a total iron content (expressed in the form of Fe2O3) in the range of 0.002 to 0.02% by weight. In a most preferred embodiment, the composition comprises a total iron content (expressed in the form Fe2O3) in the range of 0.002 to 0.015 wt.%.

[0046] According to another embodiment of the invention in combination with the above embodiment regarding the Fe2O3 content, the glass has a composition comprising chromium with a content such as 0.0001%≦Cr2O3≦0.06%, expressed as a percentage of the total weight of the glass. Preferably, the glass has a composition comprising chromium with a content such as 0.002%≦Cr2O3≦0.06%. This chromium content makes it possible to obtain a glass with a greater IR transmission, which is therefore advantageous when using the glass sheet in a touch panel that uses optical IR touch technologies such as planar scattering detection (PSD) or frustrated total internal reflection (FTIR) (or any other technology requiring a large transmission of IR radiation) to detect the position of one or more objects (e.g. a finger or a stylus) on the surface of the glass sheet.

[0047] The cover glass sheet according to the invention can advantageously be prestressed glass. By prestressed glass is meant heat strengthened glass, heat toughened glass or chemically strengthened glass. Heat strengthened glass is heat treated using a controlled heating and cooling method that places the glass surface under compression and the glass core under tension. This heat treatment method provides a glass with a bending strength greater than annealed glass but less than heat toughened safety glass.

[0048] Heat-toughened safety glass is heat treated using a controlled heating and cooling method that places the glass surfaces under compression and the glass core under tension. Such stresses cause the glass to break into small granular particles upon impact, instead of breaking into jagged shards.

[0049] Chemical strengthening of glass articles is a thermally induced ion exchange that involves the replacement of smaller alkali sodium ions in the surface layer of the glass with larger ions, such as alkali potassium ions. As the larger ions are "wedged" into the smaller sites previously occupied by the sodium ions, increased surface compressive stresses are developed in the glass. Such chemical treatments are typically carried out by immersing the glass in an ion exchange molten bath containing one or more molten salts of the larger ions with precise control of temperature and time. Aluminosilicate type glass compositions, such as those in Asahi Glass Co., Ltd.'s DragonTrail® product line or Corning Inc.'s Gorilla® product line, are also known to be very efficient for chemical tempering.

[0050] With respect to the preferred method for producing the cover glass sheets of the present invention from a larger mother glass substrate, the chemical strengthening and resulting properties described above are not intended to be limited to said production method and may be applied to cover glass sheets regardless of the production method used.

[0051] Depending on the application, intended use and / or desired properties, various layer(s) / treatments can be deposited / performed on the cover glass sheet of the present invention, on one or both sides of the cover glass sheet.

[0052] According to one embodiment of the present invention, the cover glass sheet can be coated with at least one transparent and conductive thin layer. The transparent and conductive thin layer according to the present invention can be, for example, a layer based on SnO2:F, SnO2:Sb or ITO (indium tin oxide), ZnO:Al or even ZnO:Ga. According to another embodiment of the present invention, the cover glass sheet can be coated with at least one anti-reflection layer. This embodiment is advantageous when using the cover glass sheet according to the present invention as a front cover of a screen. The anti-reflection layer according to the present invention can be, for example, a layer based on porous silica, having a low refractive index, or it can be composed of several layers (stacks), in particular a stack of alternating layers of dielectric materials, having low and high refractive indexes and terminating with a layer having a low refractive index. According to yet another embodiment, the glass sheet has at least one anti-fingerprint layer / treatment to reduce or prevent fingerprints from being left behind. Advantageously, according to this embodiment, the glass sheet has said anti-fingerprint layer / treatment on the second textured surface. Such a layer / treatment may be combined with a transparent and conductive thin layer deposited on the opposite side. Such a layer / treatment may be combined with an anti-reflective layer deposited on the same side. According to yet another embodiment of the invention, the glass sheet has an anti-bacterial layer / treatment. Advantageously, according to this embodiment, the glass sheet has said anti-bacterial layer / treatment on the second textured surface. For example, such an anti-bacterial treatment could be a diffusion of silver ions in the bulk of the glass sheet close to the outer surface.

[0053] The term "at least" is intended herein to mean "one or more." The following examples are provided for illustrative purposes and are not intended to limit the scope of the present invention. EXAMPLES

[0054] Example 1 A cover glass sheet of the configuration of Figure 1 was designed, the rectangular cover glass sheet having a total length of 300 mm and a total width of 150 mm. Its outer sheet surface includes a rectangular viewing zone having a length of 260 mm and a width of 120 mm, forming a viewing boundary of 760 mm. The opaque zone is defined by opaque paint added to all of the inner sheet surface, not the viewing zone, and surrounds 100% of the viewing boundary. The viewing zone covers 90% of the surface of the viewing screen. The rectangular textured zone has a length of 270 mm and a width of 130 mm, and surrounds 100% of the viewing boundary. The textured zone covers 28% of the opaque zone.

[0055] TIFF0007667786000001.tif31170

[0056] Example 2 A cover glass sheet of the configuration of FIG. 5 was designed, the rectangular cover glass sheet having a total length of 500 mm and a total width of 250 mm. Its outer sheet surface includes a rectangular viewing zone having a length of 150 mm and a width of 100 mm, forming a viewing border of 500 mm. The opaque zone is defined by opaque paint added to all of the inner sheet surface, not the viewing zone, and surrounds 100% of the viewing border. Two textured zones are individually positioned directly relative to the respective widths of the viewing zone, each having a length of 10 mm and a width of 100 mm, and together surrounding 40% of the viewing border. The textured zones together cover 1.8% of the opaque zone. The surface of the second textured zone covers approximately 4% of the opaque zone.

[0057] TIFF0007667786000002.tif31170 [Explanation of symbols]

[0058] 10 Cover Glass Sheets 20 Display unit 30 Display device 1 Display Zone 2. Opaque Zone 3 Textured Zones 4 Second Textured Zone 5 layers of opaque paint 6 Outer surface of cover glass sheet 7 Inner surface of cover glass sheet

Claims

1. A cover glass sheet (10) configured to cover at least one display device, the cover glass sheet (10) having an outer sheet surface and an inner sheet surface, the cover glass sheet (10) being for automotive interior applications, home appliances and / or integrated interactive displays, the inner sheet surface facing the display device and including a layer of opaque paint, the outer sheet surface being: a) at least one display zone (1) allowing at least a part of the screen of the display device to be visualized, the display zone having a border P ｄｉｓｐｌａｙ A display zone (1) having b) at least one opaque zone (2) corresponding to said layer of opaque paint and immediately surrounding at least 10-100% of said boundary line P display, said opaque zone having an opaque arithmetic amplitude value Ra （ｏｐ） (2) an opaque zone having an average surface roughness defined by A cover glass sheet (10) comprising: The outer sheet surface further comprises at least one textured zone (3) covering 0.5% to 99.5% of the opaque zone, the textured zone directly surrounding at least 5% of the boundary line P display and having a textured arithmetic amplitude value Ra （ｔｅｘ） and having an average surface roughness defined by Ra （ｏｐ） and Ra （ｔｅｘ） The absolute difference between （ｏｐ） -Ra （ｔｅｘ） |≧25 nm) A cover glass sheet (10) characterized by:

2. Ra （ｏｐ） and Ra （ｔｅｘ） The absolute difference between is at least 50 nm (|Ra （ｏｐ） -Ra （ｔｅｘ） 2. The cover glass sheet of claim 1, wherein the thickness of the cover glass sheet is 1 nm.

3. The marking zone is the average surface roughness Ra of the textured zone. （ｔｅｘ） The average surface roughness defined by the indicated arithmetic amplitude value Rad (Rad = Ra （ｔｅｘ） 3. The cover glass sheet of claim 1 , further comprising:

4. A cover glass sheet according to any one of the preceding claims, wherein the layer of opaque paint immediately surrounds at least 25% of the boundary line P display.

5. A cover glass sheet according to any one of the preceding claims, wherein the textured zone covers between 1% and 75% of the opaque zone.

6. A cover glass sheet according to any one of the preceding claims, wherein the textured zone covers between 80% and 99.5% of the opaque zone.

7. 7. A cover glass sheet according to any one of the preceding claims, wherein the textured zone directly surrounds at least 10% of the boundary line Pdisplay.

8. The outer sheet surface indirectly surrounds the boundary line P display and has a second textured arithmetic amplitude value Ra2 （ｔｅｘ） and further comprising at least a second textured zone having an average surface roughness defined by Ra （ｏｐ） and Ra2 （ｔｅｘ） The absolute difference between （ｏｐ） -Ra2 （ｔｅｘ） 8. The cover glass sheet according to claim 1 , wherein the thickness of the cover glass sheet is 100 nm or more.

9. The cover glass sheet according to any one of claims 1 to 8, wherein the cover glass sheet is a thermally strengthened or chemically strengthened glass sheet.

10. A cover glass sheet according to any one of the preceding claims, wherein the outer sheet surface is coated with an anti-reflective layer.

11. A display unit comprising a cover glass sheet according to any one of the preceding claims and a display device positioned below the display zone.

12. The display unit of claim 11 further comprising an optical interface disposed between the display device and an inner sheet surface of the cover glass sheet.

13. Use of a cover glass sheet according to any one of claims 1 to 10 or a display unit according to claim 11 or 12 for automotive interior applications, in household appliances and / or integrated interactive displays.

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