Method for treating a glass sheet to form a protective barrier and laminated glazing unit comprising such a protective barrier

Abstract

The invention relates to a method for treating a glass sheet (1) in order to obtain at least one barrier (20) for protecting a defined region of the sheet (1), referred to as the protected region (ZP), against propagation of glass fragmentation or cracking, the method comprising a treatment step consisting in producing at least one demarcation line (22) which, constituting the at least one barrier (20) for protecting the protected region (ZP), comprises a multiplicity of points (PI), each of which corresponds to a microchannel (30) obtained by a local modification of the material by means of a laser device generating a Bessel beam (F) or by laser filamentation and extending in a straight line through at least 80%, preferably 100%, of the thickness (e) of the glass sheet (1), orthogonal to the surfaces of the glass sheet (1). The present invention also relates to a laminated glazing unit (10), such as a side window or a windshield, comprising such a barrier (20) for protection against glass fragmentation or cracking.

Description

Description Title of the invention: Method for treating a sheet of glass to form a protective barrier and laminated glazing comprising such a protective barrier Technical field of the invention

[0001] The invention relates to a method of treating a sheet of glass to form a protective barrier and to laminated glazing comprising such a protective barrier.

[0002] The invention belongs to the field of laminated glazing and in particular to laminated glazing used in the field of transport, especially the automotive field. Technical background

[0003] In the automotive sector, laminated glass has various known uses. One example is its use in vehicle side windows, which are increasingly preferred over monolithic glass.

[0004] Side windows for vehicles, such as cars, buses, or trucks, are generally mounted with a sliding mechanism so they can be raised and lowered as needed. To achieve this, the structure in which the window is mounted (typically a door, framed or frameless) incorporates a window movement system. This system includes, for example, a motor that drives a linkage. This linkage has a bracket that attaches to the window. Therefore, the window must be configured to allow its connection to the window movement system.

[0005] The Applicant currently produces automotive side windows using a process called the "BT process," an acronym for "Transverse Bending," protected by various patents in the name of Saint-Gobain. These side windows are generally monolithic panes of glass heated to 650°C and then rapidly cooled to temper them while giving them a toroidal shape. This tempered glass has the dual advantage of being more resistant to mechanical stress and shattering into numerous small pieces if broken.

[0006] This fine fragmentation is called "Securit fragmentation." It protects vehicle occupants from serious cuts in the event of an accident or broken glass. This fragmentation meets the very precise specifications of the international standard R-43.

[0007] On such a monolithic glazing unit made from a single sheet of glass, the support for the movement system is fixed to the glazing by one or more holes made in said glazing. The hole(s) are made by drilling before tempering said glazing.

[0008] However, as mentioned previously, an alternative exists: the use of laminated sidelites (LSL). This is essentially a sandwich of two sheets of glass (or panes) that have been formed and hardened (in the sense that they are rapidly cooled) bonded together by an elastomeric interlayer, generally at least one sheet of PVB. In reality, the glass sheets composing these sandwiches do not reach the stress levels of tempered monolithic glass. Indeed, their thickness is too small to create, during cooling, a sufficient thermal gradient to generate the stresses necessary for Securit fragmentation. These panes are therefore described as "hardened" or "semi-hardened."

[0009] This last point does not pose a safety problem, as the PVB interlayer ensures the cohesion of the assembly in the event of an accident and thus prevents the projection of potentially harmful glass fragments. These laminated side windows are therefore used for three purposes: • Improved acoustic comfort thanks to the absorption properties of the PVB interlayer; • Improved resistance to burglary; • New properties for blocking UV radiation from the sun.

[0010] Nevertheless, these laminated side windows have a special construction compared to conventional monolithic tempered side windows.

[0011] Indeed, the current solution for attaching these laminated side windows to a door involves a plastic piece, added after manufacturing and glued to the glass, called a "holder" in English terminology. This solution complicates the process by adding an extra step.

[0012] Another solution is to drill the holes separately on each sheet of glass and then assemble them with an interlayer. However, this solution is complex because it requires aligning the holes on both sheets of glass during assembly. While this alignment is already complex for flat sheets of glass, the complexity increases with curved sheets of glass, shaped by curvature.

[0013] Another existing solution for drilling holes in the glazing is to have one pane of glass larger than the other (usually the outer pane) and to drill the holes in this larger, and generally thicker, pane. However, this point of contact with the holes is crucial for securing the glazing to the vehicle, and it is essential to ensure that... To maintain the cohesion of the area around the hole in case of impact and therefore breakage, particularly fragmentation. It is possible to add reinforcement such as an insert, but this again complicates the manufacturing of the glazing.

[0014] As an example, reference can be made to document WO-2021 / 191549 which presents in the preamble the prior art concerning side glazing, in particular for the connection with the movement system, and which discloses the use of an insert to reinforce the fixing part of the glazing.

[0015] We will remember from the above that the use of laminated glass as side glazing instead of monolithic glass is a first example of use and that in such a use the fixing part of the glass sheet having at least one hole constitutes a sensitive area to be reinforced, to be protected in case of breakage.

[0016] However, there are many other examples of the use of laminated glass in a vehicle, for example the windshield, the rear window or a panoramic roof.

[0017] According to a second example of use, laminated glass is used to form the windshield of the vehicle, again with the same advantages over monolithic glass as the aforementioned objectives.

[0018] Vehicles are increasingly equipped with Advanced Driver-Assistance Systems (ADAS), such as cameras or radar (for example, LiDAR), often positioned behind the windshield, inside the passenger compartment. The area of ​​the windshield through which these systems operate is therefore a sensitive zone that must be protected. Indeed, the propagation of glass fragments or cracks in this area, for example, following an impact such as from a stone chip, would affect the operation of these driver assistance systems. In the event of autonomous vehicle operation, the functioning of such driver assistance systems becomes a major safety concern.

[0019] As an example, it is known to strengthen the area of ​​a laminated glass by locally performing a heat treatment on the glass in order to obtain stresses that are different from those of the rest of the glazing.

[0020] In general, there is therefore a need to find solutions to protect sensitive areas of laminated glazing, particularly but not exclusively used as side windows or windscreens.

[0021] However, the inventors made a surprising discovery while working on samples of glass sheets with a laser device generating a Bessel beam, also known as laser filamentation. More precisely, they discovered that, under certain conditions, the laser beam caused a local modification of the material such that a "barrier effect" was obtained. In effect- In fact, they were able to observe, surprisingly, that the propagation of fragmentation or cracking in the glass sheet was blocked at the level of the area where the material had been modified by the laser beam. Summary of the invention

[0022] The aim of the present invention is therefore to solve at least some of the problems of the prior art by taking advantage of this discovery to offer a simple, reliable and economical solution to protect the sensitive areas of laminated glazing, typically during an impact that could cause the glass to break, i.e. fragment or crack.

[0023] According to a first aspect, the present invention relates to a method for treating a sheet of glass to obtain at least one protective barrier for a defined area of ​​said sheet, referred to as the protected area, against the propagation of fragmentation or cracking of the glass, said sheet of glass being intended to be joined to a second sheet of glass by means of an interlayer made of polymer material to form laminated glazing, said method comprising a treatment step consisting of creating at least one demarcation line which, constituting said at least one protective barrier of the protected area, comprises a multitude of points, each of which corresponds to a micro-channel obtained by a local modification of the material by means of a laser device generating a Bessel beam or a beam used for laser filamentation and extending in a straight line over at least 80%, preferably 100%, of the thickness of said sheet of glass,orthogonally to the surfaces of said sheet of glass.

[0024] According to other characteristics of the treatment process: - said treatment step consists of scanning said glass sheet with the Bessel beam generated by the laser device or with the beam used for laser filamentation to create the demarcation line constituting said at least one protective barrier against the propagation of a fragmentation or cracking of the glass to said protected area, said Bessel beam making it possible to create said multitude of impact points, each of which corresponds to a micro-channel obtained by a local modification of the material in the glass sheet; - the laser device generating the Bessel beam or the beam used for laser filamentation has a wavelength between 400 and 1100 nm, preferably a wavelength between 800 and 1100 nm, for example equal to 1032 nm or 1064 nm; - the Bessel beam is shaped to have a length that is at least equal to the thickness of said sheet of glass; - the laser device generating the Bessel beam has pulses generated with a working frequency between 1 and 1000 kHz; - the laser device generating the Bessel beam has an energy per pulse train which is between 100 and 10000 pJ, preferably between 1000 and 8000 pJ, each pulse train being able to be composed of 1 to 16 pulses, so that the energy per pulse is between 100 and 4000 pJ, preferably between 300 and 3000 pJ; - the laser device generating the Bessel beam has pulses with a duration between 0.1 and 100 ps, ​​preferably between 0.1 and 10 ps.

[0025] According to a second aspect, the present invention relates to laminated glazing, particularly for motor vehicles, comprising at least a first sheet of glass and a second sheet of glass joined by means of an interlayer of polymer material disposed between the first sheet of glass and the second sheet of glass, said laminated glazing being characterized in that at least one of said sheets of glass of the glazing comprises at least one protective barrier for a defined area of ​​said sheet, said at least one protective barrier being capable of protecting said protected area against the propagation of fragmentation or cracking of the glass and consisting of at least one demarcation line comprising a multitude of points, each of which corresponds to a micro-channel which, obtained by a local modification of the material by means of a laser device generating a Bessel beam or by laser filamentation,extends in a straight line over at least 80%, preferably 100%, of the thickness of said glass sheet and orthogonally to the surfaces of said glass sheet.

[0026] According to other characteristics of laminated glass: - two adjacent impact points produced by the Bessel beam or by laser filamentation are separated by a distance of between 1 and 50 pm, preferably between 5 and 20 pm; - the value of the distance between two points of impact is between two and seven times the diameter of the central lobe of the Bessel beam generated by the laser device or of the laser beam used for laser filamentation, said diameter of the central lobe being between 2 and 10 pm, preferably between 4 and 7 pm, for example equal to 5 pm; - the local modification of the material being obtained by means of the laser device generating the Bessel beam, characterized in that said at least one sheet of glass of the laminated glazing comprising the protective barrier has a thickness between 1 mm and 4 mm, preferably between 1.4 mm and 2.6 mm; - Laminated glass is specifically intended for use as a side window on a motor vehicle, said side window being mounted to slide relative to a door-type structure by means of an associated movement system, characterized in that said glass has an edge of the second glass pane that is recessed relative to the edge of the first sheet of glass on at least part of the perimeter of the glazing; - the first sheet of glass includes at least one hole for fixing said glazing to the movement system and in that said at least one demarcation line forming the protective barrier surrounds said at least one hole so as to form a protected area around said hole to guarantee the fixing of the glazing in the event of fragmentation or cracking occurring in the first sheet of glass; - the demarcation line extends over the area of ​​the first sheet of glass not covered by the second sheet of glass, or extends over the area of ​​the first sheet of glass covered by the second sheet of glass, or extends opposite the edge of the second sheet of glass; - laminated glass is in particular intended for use as a windscreen on a motor vehicle, in which the second sheet of glass includes a specific area such as an opening at which an accessory such as a camera or radar is fixed, characterized in that said demarcation line is made in the first sheet of glass so as to obtain a protected area opposite said specific area to guarantee the operation of said accessory in the event of fragmentation or cracking occurring in the first sheet of glass.

[0027] The invention also relates to a structure comprising an opening in which laminated glazing according to one of the preceding characteristics is arranged.

[0028] In a first example, the structure is designed to allow the laminated glass to slide within it, the structure including a movement system to enable the glass to slide. The use of laminated glass as a sliding side window in a vehicle door corresponds to such a first example.

[0029] In a second example, laminated glass is bonded to the opening. Using laminated glass as a windshield or rear window of a vehicle falls under this second example. Brief description of the figures

[0030] Other features and advantages of the invention will become apparent upon reading the detailed description that follows, for an understanding of which reference should be made to the attached drawings in which: - Figures 1 and 2 are respectively a perspective view and a cross-sectional view schematically representing an example of laminated glazing and which also illustrate the constitution of such glazing formed of two sheets of glass assembled by means of an interlayer; - Figure 3 is a cross-sectional view schematically representing a part of laminated glazing according to a first embodiment in which said glazing is a side glazing whose sensitive area to be protected is constituted by the fixing part provided with at least one hole, said figure 3 further illustrating the fact that the laminated glazing comprises a sheet of glass which is larger than the other sheet of glass and which is provided with said hole; - Figures 4 and 5 are respectively a side view and a cross-sectional view schematically representing a first configuration of laminated glazing according to a first embodiment of the invention and which illustrates a first example of realization of the demarcation line in the form of a horizontal line forming a protective barrier according to the invention; - Figures 6 and 7 are respectively a side view and a cross-sectional view which, analogous to Figures 4 and 5, schematically represent the same laminated glazing after an impact which caused a fragmentation of the glass and which illustrate the barrier effect obtained thanks to the said demarcation line which, by blocking the fragmentation, protects the part of the glass sheet equipped with the hole for fixing the lateral glazing to the movement system; - Figures 8 and 9 are schematic representations of a Bessel type laser beam used to obtain laminated glazing in which at least one of the glass sheets has a protective barrier against the propagation of fragmentation or cracking of the glass in accordance with the teachings of the invention; - Figure 10 is a top view representing a sheet of glass with impact points obtained by scanning with the Bessel beam giving a demarcation line forming the protective barrier and which further illustrates the fact that the impact points of the line are all equidistant, separated by the same distance; - Figure 11 is a cross-sectional view passing through the demarcation line of the glass sheet according to Figure 10, which represents the protective barrier made up of micro-channels corresponding to the impact points resulting from a local modification of the material obtained with the Bessel beam and which illustrates said micro-channels extending in a straight line over the entire thickness of the glass sheet and orthogonally to the surfaces of said glass sheet; - Figures 12 to 14 are cross-sectional views which, similar to Figure 5, represent variants of the first embodiment with a protective barrier formed by a straight demarcation line extending horizontally below the visibility limit and which illustrates more particularly variants of positioning of said demarcation line so that the fixing part of the laminated glazing is an area protected against the propagation of fragmentation or cracking; - Figures 15 and 16 are side views schematically representing a laminated glazing identical to that of figure 4 according to the first embodiment, respectively before and after an impact which caused a fragmentation of the glass sheet with the exception of that of the protected area and which illustrate a second example of embodiment of the protective barrier formed by a circular demarcation line surrounding the hole made in the largest glass sheet for fixing the glazing to the movement system; - Figure 17 is a side view which, analogous to Figure 15, schematically represents a variant of an embodiment of laminated glazing according to the first embodiment intended to be used as lateral glazing and which illustrates a part of the fixing of the laminated glazing having two holes, each hole being surrounded by a circular demarcation line forming a protective barrier according to the second example of embodiment illustrated in Figures 15 and 16; - Figure 18 is a cross-sectional view schematically representing part of a laminated glazing according to a second embodiment in which said glazing is a windscreen whose protected area is constituted by the part of the first sheet of glass located opposite an accessory such as a camera or radar and which illustrates an example of the realization of a closed demarcation line (presenting for example a trapezoidal shape) to form around said protected area a protective barrier against the propagation of a fragmentation or cracking of the glass; - Figures 19 and 20 are respectively a cross-sectional view, similar to Figure 18, and a perspective view of a windscreen representing the second embodiment of laminated glazing after an impact which caused a crack in the outer sheet of glass and which illustrates the barrier effect obtained thanks to said demarcation line by blocking the propagation of the crack(s) in the glass sheet in order to protect said area to guarantee the operation of the accessory.

[0031] In the various figures, the demarcation line forming the protective barrier according to the invention is schematically represented by a multitude of points without the representation being to scale, otherwise the points could not be distinguished. Detailed description of the invention

[0032] In the following description, a laminated glazing according to the invention, particularly for motor vehicles, will be further described, respectively, according to a first embodiment in which said glazing is a side window intended to be mounted sliding in a door, with or without a frame, and a second embodiment in which said glazing is a windshield intended to be associated with an accessory, generally at least one driver assistance system such as a camera and / or radar (for example, a "LiDAR"), which is mounted directly behind the windshield, inside the vehicle.

[0033] We will describe in general terms the characteristics of a 10 laminated glazing as illustrated by figures 1 and 2.

[0034] Figure 1 illustrates an example of laminated glass 10 in its mounting position on the motor vehicle. Generally parallelepiped in shape, the laminated glass 10 comprises four peripheral sides, namely: a lower side 11, two opposite lateral sides 12, 14 and an upper side 13.

[0035] Subject to adapting the shape to its use, such laminated glass for motor vehicles constitutes, for example, a side window according to the first embodiment or a windshield according to the second embodiment. However, these examples are by no means exhaustive, and laminated glass could also be a rear window or even a roof window for the vehicle, known as a panoramic roof, said roof being either opening or fixed.

[0036] Laminated glass panes (10) are designed to be mounted in a structure (not shown), for example, in a door, with or without a frame, in the case of side windows, or directly onto the vehicle for a windshield, rear window, or roof. Generally, all these laminated glass panes have a roughly polygonal outline—albeit with curved segments—which very often has four peripheral sides, as illustrated in Figure 1, but their overall shape varies. In the case of side windows, some have only three peripheral sides. In these applications, the glass is usually curved, but it can also be flat.

[0037] More generally, laminated glass can also be used for applications other than motor vehicles, notably in aeronautics, in which case it can be disc-shaped—which amounts to having only one peripheral edge as defined in the present invention—or in buildings. The following description of the invention is applicable mutatis mutandis to any sheet of glass and, by extension, to any laminated glass, regardless of its overall shape and final application.

[0038] As can be seen in the cross-sectional view of Figure 2, the laminated glazing 10 comprises a first sheet 1 of glass, which constitutes the outer glass sheet of the glazing 10, and a second sheet 3 of glass, which constitutes the inner glass sheet. By convention, the term "exterior" refers to what is oriented towards the outside of the structure, such as a vehicle, and, in contrast, the term "interior" refers to what is oriented towards the inside, i.e., the passenger compartment in the case of a motor vehicle.

[0039] The outer and inner glass panes 1 and 3 can be of conventional type. Preferably, the outer glass pane 1 (the first pane) has a thickness chosen to be between 1.4 mm and 2.6 mm. The first glass pane 1 can be thicker, for example up to 4 mm or even more. for specific applications where increased mechanical strength is desirable. Conversely, the thickness of the outer glass pane 1 may be less than 1.4 mm for certain specific applications where lower mechanical strength is acceptable, but the thickness is preferably greater than or equal to 1 mm.

[0040] The inner glass sheet 3 (called second) of the glazing 10 has a thickness of less than 1.2 mm and more preferably less than or equal to 1 mm and more advantageously less than or equal to 0.7 mm.

[0041] In order to reduce the weight of laminated glass, it is also known to form laminated glass with a first sheet 1 of glass and a second sheet 3 of glass having different thicknesses. Thus, the inner second sheet 3 of the laminated glass has a thickness less than or equal to that of the outer first sheet 1 of glass.

[0042] Preferably, the first sheet 1 of glass located on the outside has a greater thickness than the second sheet 3 located on the inside because the attachment of the movement system is made on the first sheet 1 of glass.

[0043] The outer glass sheet 1 can be subjected to a treatment that increases its surface mechanical strength, for example by conventional heat treatment such as tempering or hardening, or by annealing, meaning without significant compression of its surfaces, as is most often the case with laminated automotive windshields. However, in both cases, it is advantageous for the edge of the glass sheet to be mechanically reinforced by applying edge compression stresses during its manufacturing process.

[0044] The inner glass pane (layer 3) is preferably subjected to a treatment that increases its mechanical strength. This treatment can be a thermal hardening process (called semi-tempering). For thinner panes of glass, chemical tempering is preferred, as this creates a surface zone of the glass that is under compression while a central zone is under tensile stress. The chemical tempering technique is well-established: see, for example, the article "Ion exchange for glass strengthening" by René Gy in Materials Science & Engineering: B, Vol. 149 No. 2, 25 / 03 / 2008, Elsevier, ISSN: 0921-5107, pp. 159-165. Naturally, the composition of the glass panes (layers 1 and 3) is chosen to be compatible with the treatments applied to them.

[0045] In a manner known per se, an interlayer 2, consisting of at least one sheet of polymer material, is placed between the two glass sheets 1, 3 and serves to hold them together by adhesion, as shown in Figure 2. This can conventionally be at least one sheet of polyvinyl butyral (PVB), for example, 0.76 mm thick. Alternatively, it can be any other suitable material such as a sheet of ethylene-vinyl acetate (EVA) or of Polyurethane. Depending on the glazing application, it may also be a resin poured between the glass panes 1 and 3, which is then polymerized. The thickness of the polymer layer forming the interlayer 2 can vary. The interlayer 2 can also consist of several superimposed polymer sheets made of the same material or different materials, particularly depending on desired properties, such as acoustic attenuation.

[0046] We will now describe the first embodiment of the invention illustrated in particular in figures 3 and 4 and according to which said laminated glazing 10 is a lateral glazing.

[0047] In this first embodiment, the laminated glazing 10 is configured such that the outer edge 3a of the inner glass sheet 3 (or second glass sheet), located below the visibility limit LV of the glazing (when the glazing is mounted in its operating position in the door), is recessed relative to the outer edge la of the outer glass sheet 1 (or first glass sheet) by a non-zero distance referred to as DI. Due to this recess, such laminated glazing 10 is sometimes called "asymmetrical" glazing, since glass sheet 1 and glass sheet 3 are not identical in shape. For example, the distance DI is between 3 and 5 cm and varies depending on the application, particularly the vehicle and the glazing movement system 10.

[0048] According to the guidelines of application WO-2022 / 162309-A1, it is also possible to create a recess around the entire perimeter of the glazing unit 10, and not just to accommodate the fixing portion of the glazing. The recess distance is then generally small. Preferably, the recess distance is at least 1 mm, and more preferably at least 2 mm, or even at least 3 mm, which facilitates the recessed positioning of the inner pane of glass 3 relative to the outer pane of glass 1 during assembly, taking into account positioning tolerances. The recess distance can be constant around all or part of the perimeter of the glazing unit 10, but can also vary, for example, be different depending on the side of the glazing.

[0049] In the case of the automotive side window 10, the outer glass pane 1 includes at least one hole 40 for attaching the window 10 with a sliding system. In Figures 3 to 5, the laminated glass pane 10 has one hole 40; alternatively, in Figure 17, it has two holes 40. The hole(s) 40 are located in the portion of the outer glass pane 1 that is not covered by the inner glass pane 3.

[0050] The fixing part of the glazing 10, consisting of the outer glass sheet 1 which is not covered by the inner glass sheet 3, is more fragile and cannot maintain its cohesion in case of breakage because it is not held in place by the sandwich formed by the interlayer 2 and said sheet 3 of interior glass.

[0051] In the first embodiment, where the laminated glass 10 forms a side window, the fixing portion of the glass sheet 1, which has at least one hole 40, constitutes a vulnerable area requiring protection in case of breakage caused by an impact, particularly protection against the propagation of fragmentation or cracking. Indeed, breakage of the fixing portion of the glass sheet 1 around hole 40 would result in the laminated glass 10 no longer being fixed to the movement system but free, and potentially ejected, especially if the door is frameless.

[0052] As explained in the preamble, the inventors, working with a laser device generating a Bessel beam on glass, discovered the existence of a "barrier effect" against the propagation of fragmentation or cracking. A possible application of this discovery of the barrier effect is precisely to use it to protect a sensitive area of ​​laminated glazing, such as the fixing part of the first (outer) glass pane, which has at least one hole in the case of the first embodiment concerning side glazing.

[0053] Following their discovery, the inventors were also able to demonstrate achieving the same "barrier effect" by implementing laser filamentation. Compared to a laser device generating a Bessel beam, laser filamentation uses a laser beam emitted by a laser source but which is not shaped optically. This is why laser filamentation for forming a protective barrier has a more limited application in terms of glass thickness and tint compared to a Bessel beam.

[0054] Thus, such laser filamentation can be used as an alternative to the Bessel beam for sheets of untinted glass, i.e., clear glass, with a thickness of less than 2 mm. When the glass sheet is tinted and / or has a thickness greater than 2 mm, then the protective barrier 20 is advantageously obtained with a laser device generating a Bessel beam.

[0055] According to a first aspect, the invention relates to a method for treating a sheet 1 of glass to obtain at least one protective barrier 20 of a defined area of ​​said sheet 1, referred to as the protected area ZP, against the propagation of fragmentation or cracking of the glass, said sheet 1 of glass being intended to be joined to a second sheet 3 of glass by means of an interlayer 2 made of polymer material to form a laminated glazing 10, said method comprising a treatment step consisting of creating at least one demarcation line 22 which, constituting said at least one protective barrier 20, The protection zone ZP includes a multitude of points PI, each of which corresponds to a micro-channel 30 obtained by a local modification of the material by means of a laser device 500 generating a Bessel beam F or by laser filamentation and extending in a straight line over at least 80%, preferably 100%, of the thickness (e) of said glass sheet 1, orthogonally to the surfaces of said glass sheet 1.

[0056] Advantageously, said treatment step consists of scanning said glass sheet 1 with the Bessel beam F generated by the laser device 500 (alternatively the beam used for laser filamentation) to create the demarcation line 22 constituting said at least one barrier 20 for protection against the propagation of a fragmentation or cracking of the glass to said protected zone ZP, said Bessel beam F enabling said multitude of impact points PI to be created, each of which corresponds to a micro-channel 30 obtained by a local modification of the material in the glass sheet 1.

[0057] The laser device 500 generating a Bessel F beam will be described in more detail later with reference to figures 8 and 9, as well as the protective barrier 20 formed by the demarcation line 22 and in particular the impact points (PI) and the micro-channels 30 with reference to figures 10 and 11.

[0058] The treatment process according to the invention is carried out on a sheet of glass in a flat state, for example forming a panel, preferably cut to the dimensions and shape determined by the application, either before its shaping and assembly to constitute the laminated glazing 10, or here carried out in addition on the sheet 1 of glass intended to be arranged on the outside of the glazing.

[0059] The implementation of the process results in a glass sheet 1 incorporating a protective barrier 20, referred to as "anti-fragmentation" or "anti-cracking," which advantageously protects a specific sensitive area as defined by the application. The protective barrier 20 consists of at least one demarcation line 22 configured to protect a protected area ZP from any fragmentation or cracking of the glass, said protected area ZP being defined according to the application.

[0060] Thanks to the treatment process according to the invention, a laminated glazing 10 is obtained after the implementation of said process on at least one of the glass sheets of the laminated glazing 10, preferably the first glass sheet 1 located on the outside in the case of a side glazing or a windshield.

[0061] According to a second aspect, the invention therefore relates to a laminated glazing 10, in particular for motor vehicles, comprising at least a first sheet 1 of glass and a second sheet 3 of glass assembled by means of an interlayer 2 of polymer material disposed between the first sheet 1 of glass and the second sheet 2 of glass, said laminated glazing 10 being characterized in that at least one 1 of said sheets 1, 3 of glass of the glazing 10 comprises at least a barrier 20 for the protection of a defined area of ​​said sheet 1, said protected zone ZP, said at least one protective barrier 20 being capable of protecting said protected zone ZP against propagation of fragmentation or cracking of the glass and consisting of at least one demarcation line 22 comprising a multitude of points PI, each of which corresponds to a micro-channel 30 which, obtained by a local modification of the material by means of a laser device generating a Bessel beam F or a beam used for laser filamentation, extends in a straight line over at least 80%, preferably over 100%, of the thickness (e) of said glass sheet 1 and orthogonally to the surfaces of said glass sheet 1.

[0062] FIRST METHOD OF IMPLEMENTATION Figure 3 is a cross-sectional view schematically representing part of a laminated glazing 10 according to a first embodiment in which said glazing 10 is a lateral glazing.

[0063] In the case of such laminated glazing 10, the protected area ZP is constituted by the fixing part which, having at least one hole 40, is formed by the uncovered part of the glass sheet 1 which is larger than the other glass sheet 3.

[0064] Figures 4 and 5 represent a first configuration of a laminated glazing 10 according to the first embodiment. More particularly, Figures 4 and 5 illustrate a first example of the realization of the demarcation line 22 in the form of a straight line extending horizontally from one edge to the other, parallel to the visibility limit LV of the glazing and below it, to form the "anti-fragmentation" or "anti-cracking" protective barrier 20 according to the invention.

[0065] The protected zone ZP by the barrier 20 is thus formed by the entire fixing portion of the glazing 10, which constitutes the uncovered glass sheet 1. Indeed, in the first glazing configuration, the protective barrier 20 extends above the edge 3a, as visible in Figure 4, to completely separate the fixing portion of the outer glass sheet 1 that is not covered by the inner glass sheet 3. However, the straight demarcation line 22 forming the protective barrier 20 could be located at a different height.

[0066] According to an alternative embodiment of the first configuration illustrated in Figure 12, the protective barrier 20 is arranged beyond the edge 3a of the inner glass pane 3, that is, on the portion of the outer glass pane 1 that is not covered by said inner glass pane 3. The demarcation line 22 forming the barrier 20 is identical to that illustrated in Figure 3 in that it extends in a straight line or horizontally from one edge to the other, parallel to and below the visibility limit LV of the glazing.

[0067] According to another embodiment of the first configuration illustrated in In Figure 13, the protective barrier 20 is positioned opposite the edge 3a of the inner glass sheet 3. The demarcation line 22 forming the barrier 20 is again identical to that illustrated in Figure 3 in that it extends in a straight line or horizontally from one edge to the other, parallel to the visibility limit LV of the glazing and below it.

[0068] According to yet another variant of the first configuration illustrated in Figure 14, the protective barrier 20 is arranged on the part of the outer glass sheet 1 which is covered by the inner glass sheet 3 (as in Figure 5).

[0069] Similar to figures 4 and 5, figures 6 and 7 schematically represent the same laminated glazing 10 after an impact which caused a fragmentation of the glass of at least the first outer sheet 1.

[0070] Figures 6 and 7 illustrate more particularly the barrier effect obtained thanks to the said demarcation line 22 forming the barrier 20 which by blocking fragmentation protects the fixing part of the glass sheet 1 equipped with the hole 40.

[0071] Thanks to the protective barrier 20, the side glazing is guaranteed to remain fixed to the movement system even after an impact and fragmentation of the glass sheet 1, thus ensuring safety by preventing any detachment followed by ejection of the laminated glazing 10.

[0072] The demarcation line 22, forming the protective barrier 20 in the glass sheet 1 of the laminated glazing 10, such as that shown in Figures 3 to 7 above, is advantageously produced using a laser device 500 generating a Bessel beam F, as seen in Figures 8 and 9, or alternatively by laser filamentation. The generated laser beam F is such that it allows the creation of a demarcation line 22 with a geometric shape adapted to the application.

[0073] In the case of the first embodiment (side glazing) and according to a first example of embodiment illustrated by figures 4 and 5 as well as figures 6 and 7, the demarcation line 22 is made in the form of a straight line extending from one edge to the other and parallel below the limit of visibility to form the barrier 20 of protection of the fixing part of the laminated glazing 10 which, formed by the first sheet 1 of glass (uncovered) and provided with at least one or even two holes 40, constitutes the protected zone (PZ) in accordance with the teachings of the invention.

[0074] In the case of the first embodiment (side window) and according to a second embodiment illustrated by figures 15 and 16 as well as the variant of figure 17, the demarcation line 22 is made in the form of a closed circular line surrounding each hole 40 of the first sheet 1 of glass (uncovered) to form said protective barrier 20.

[0075] In the case of the second embodiment (windshield), the demarcation line- tion 22 is made in the form of a closed line following a geometric pattern such as a quadrilateral such as a rectangle or a trapezoid delimiting a protective barrier 20 around a protected area ZP which is defined according to the accessory 5, so as to guarantee its operation in case of fragmentation or cracking in the first sheet 1 of glass of the laminated glazing 10.

[0076] We will describe in more particular below a laser device 500 configured to generate a Bessel beam F with reference to figures 8 and 9. Advantageously, the treatment according to the invention is carried out with a Bessel beam, alternatively a beam configured to carry out laser filamentation is used.

[0077] In order to enable the creation of the demarcation line 22 forming the protective barrier 20, the laser device 500 further comprises at least one laser source 510 and optical means 520, the whole being configured to shape the beam from the laser source 510 in order to obtain a Bessel F beam.

[0078] Such a Bessel beam F, visible in figure 8, is characterized by a cross-sectional profile comprising a central point Pc and at least one ring A or corona whose center is said central point Pc. This central point Pc is the region where the beam intensity is highest.

[0079] The laser source 520 of the laser device 500 used is also characterized by a wavelength. More specifically, the laser device 500 is such that it emits in a wavelength range for which both the glass and the interlayer 2 are transparent – ​​typically in the visible or near-infrared range.

[0080] Advantageously, the laser device 500 generating the Bessel F beam has a wavelength between 400 and 1100 nm, preferably a wavelength between 800 and 1100 nm, for example equal to 1032 nm or 1064 nm.

[0081] To create the demarcation line 22, the Bessel beam F is shaped so that its length is at least equal to the thickness (e) of the glass sheet. The length LB of the Bessel beam is shown in Figure 8.

[0082] To shape said Bessel beam F to the desired length LB, a laser device 500 and parameters such as those found in the article Meyer et al. Appl. Phys. Lett. 114, 201105 (2019) are used for example.

[0083] This allows us to have a Bessel beam F whose length LB is at least equal to 80% of the thickness (e) of the outer glass sheet 1, preferably to 100% of the thickness (e), that is to say over the entire thickness of the treated glass sheet.

[0084] The 500 laser device generating the Bessel F beam or laser filamentation also exhibits power and operating frequency characteristics, the latter being characteristic of the time between each pulse. Indeed, the A laser beam (F) has a natural frequency related to its wavelength, but also an operating frequency. The operating frequency is related to the fact that the laser beam is pulsed and that the pulses are generated at a certain frequency, called the operating frequency.

[0085] The laser beam treatment involves locally modifying the material of the outer glass sheet 1. This modification is a localized embrittlement of the material that propagates through the glass sheet. This embrittlement takes the form of microchannels 30, each microchannel 30 extending over 80% to 100% of the glass thickness (e). Most clearly visible in Figure 11, the microchannels 30 form the protective barrier 20, which also prevents cracks from propagating to the protected zone ZP.

[0086] The demarcation line 22 is thus created by a relative displacement (for example, a sweep) between the glass sheet and the Bessel beam F so that said demarcation line 22 can be produced. Preferably, the laser device 500 is mounted to move relative to the glass sheet.

[0087] The demarcation line 22 consists of a plurality of points – called impact points PI – each point corresponding to an impact of the laser beam. The distance “d” between each impact point PI is such that it allows each PI point to treat an area of ​​the glass sheet without impacting an adjacent point, as seen in Figure 10.

[0088] Indeed, the Bessel beam F is such that it creates stress in the glass sheet. Advantageously, the treatment process is carried out on a flat glass sheet, that is to say before its shaping (for example by curving) and its assembly to obtain laminated glazing 10.

[0089] If two impact points Plj and Plj+i are too close, then the impact point Plj+i influences the preceding impact point Plj. This influence can manifest itself in the fact that the stresses induced by the beam's impact on point Plj+i lead to a reduction or modification of the stresses due to the beam's impact on point PI. Thus, it is possible that the microchannels created by the beam's impact on point Plj will close upon the beam's impact on point Plj+i, such that using the beam at point Plj+i would render point Plj inoperative.

[0090] According to an important feature, the invention therefore proposes to define a distance "d" between two adjacent points of impact (Plj; Plj+i) allowing to avoid this problem of interference.

[0091] To achieve this, the distance "d" between two points of impact (PI) is chosen to depend on the dimensions of the laser beam. More specifically, the diameter of the Bessel beam, and in particular the width of the central lobe Pc in the focusing zone, is used. Indeed, the central lobe is the most energetic region of the beam, that is to say, the region that impacts the glass sheet most intensely. therefore the area to be used as a reference.

[0092] Advantageously, a distance "d" between two points of impact (PI) is chosen to be equal to a value between two and seven times the diameter D of the central lobe Pc of the Bessel beam F. The diameter (D) of the central lobe (Pc) is, for example, between 2 and 10 pm, preferably between 4 and 7 pm, for example equal to 5 pm.

[0093] Advantageously, the distance "d" between two points of impact (PI) will be between 1 and 50 pm, preferably between 5 and 20 pm.

[0094] To achieve this distance, two parameters of the laser 500 device are taken into account. These parameters are, on the one hand, the relative speed of movement between the glass sheet and the laser 500 device and, on the other hand, the operating frequency.

[0095] Indeed, the relative speed of movement represents the difference in speed between the glass sheet placed on a support and the laser device 500, meaning that both the glass sheet and / or the laser device 500 can move. This speed of movement can also be called the scanning speed.

[0096] The operating frequency is the frequency at which the pulses are generated.

[0097] These two quantities are therefore linked, such that the scanning speed and the operating frequency allow us to define the maximum step size between two impact points (PI). Indeed, the operating frequency is expressed in Hertz (s⁻¹), while the scanning speed is expressed in m / s or mm / s; the ratio between the two gives a value in m or mm.

[0098] In this case, it is necessary that the ratio between the scan rate and the operating frequency be equal to a value between two and seven times the diameter (D) of the central lobe (Pc). This allows us to determine the frequency and scan rate values ​​used.

[0099] Advantageously, the operating frequency is between 1 and 1000 kHz. In other words, the laser device 500 generating the Bessel beam (F) produces pulses with an operating frequency between 1 and 1000 kHz.

[0100] Advantageously, the laser device 500 generating the Bessel beam (F) has an energy per pulse train which is between 100 and 10000 pj, preferably between 1000 and 8000 pj, each pulse train being able to be composed of 1 to 16 pulses, so that the energy per pulse is between 100 and 4000 pj, preferably between 300 and 3000 pj.

[0101] The pulses of the laser beam also exhibit characteristics such as a duration characteristic. Indeed, the amount of energy depends on the intensity of the pulse but also on its duration.

[0102] Advantageously, the laser device generating the Bessel beam (F) presents pulses with a duration between 0.1 and 100 ps, ​​preferably between 0.1 and 10 ps.

[0103] In one variant, each pulse of the laser beam is composed of at least two sub-pulses. This means that the Laser 500 device is designed so that each pulse is actually a train of pulses. These pulses also have a duration ranging from 0.1 to 100 ps, ​​or even from 0.1 to 10 ps.

[0104] The pulse frequency, related to the duration between two pulses in the same pulse train, is higher than the operating frequency. The frequencies between two pulses in the same pulse train are at least an order of magnitude higher than the operating frequency.

[0105] Figure 11 represents the protective barrier 20 consisting of microchannels 30 corresponding to the impact points (PI) resulting from a local modification of the material obtained with the Bessel F beam.

[0106] As illustrated in Figure 11, the microchannels 30 extend in a straight line across the entire thickness (e) of the glass sheet 1 and orthogonally to the surfaces of said glass sheet 1. Each microchannel 30 has a substantially circular shape with a diameter (D) corresponding to that of the central lobe (Pc) of the Bessel beam F.

[0107] The demarcation line 22 creates a protective barrier 20 on the outer glass sheet 1, preventing fracturing—that is, fragmentation or cracking—from propagating to the other side of the demarcation line 22. Thus, this barrier 20 protects the portion of the outer glass sheet 1 not covered by the inner glass sheet 3, as the micro-channels 30 prevent crack propagation, as illustrated in particular by Figures 6 and 7.

[0108] A second example of the realization of the protective barrier 20 formed by a circular demarcation line 22 surrounding the hole 40 made in the largest sheet 1 of glass will be described below with reference to figures 15 and 16, for the fixing of the glazing 10 to the movement system.

[0109] Compared with the first example of implementation illustrated in particular in figures 3 to 6, the demarcation line 22 is therefore not made in the form of a line extending in a straight line from one edge to the other, parallel to the visibility limit LV of the glazing and below it.

[0110] Figures 15 and 16 schematically represent a laminated glazing 10 identical to that of Figure 4 according to the first embodiment, respectively before and after an impact which caused a fragmentation of the sheet 1 of glass with the exception of that of the protected area ZP surrounding the hole 40.

[0111] Figure 17 shows an alternative embodiment of laminated glazing 10 according to the first embodiment intended for use as side glazing and illustrates a fixing portion of the glazing 10 comprising two holes 40, each hole 40 being surrounded by a protected zone ZP by means of a circular demarcation line 22 forming a protective barrier 20 similar to that according to the second embodiment illustrated in the previous figures 15 and 16.

[0112] In the first embodiment, the first sheet 1 of glass thus includes at least one hole 40 for fixing said glazing 10 to the movement system and said at least one demarcation line 22 forming the protective barrier 20 surrounds said at least one hole 40 so as to form a protected zone ZP around said hole 40 to guarantee the fixing of the glazing 10 in the event of fragmentation or cracking occurring in the first sheet 1 of glass.

[0113] In this second embodiment, the protective barrier 20 is arranged to isolate annular protected areas ZP around the hole(s) 40 as seen in figures 15, 16 and 17. According to this second embodiment, the demarcation line(s) 22 are used to isolate defined areas and not the entire fixing part as in the first embodiment.

[0114] In this first embodiment, the protected areas ZP are the holes 40 in the outer glass sheet 1 used for fixing the movement system, the protective barrier 20 then taking the form of the circular demarcation line 22 around the hole or holes 40.

[0115] It will be understood, however, that if each hole 40 can be individually surrounded by a demarcation line 22, in an alternative not shown the two holes 40 visible on figure 17 could be surrounded by a single demarcation line 22 for example in the shape of an ellipse.

[0116] Of course the invention is by no means limited to an application to a side window according to the first embodiment but could also be applied in a similar way to other laminated glazing 10 for motor vehicles such as a rear window or a panoramic roof which moreover can similarly include holes for the passage of a windshield wiper shaft or an antenna typically around which a protected area ZP would be made delimited by a demarcation line 22 forming a protective barrier 20.

[0117] Furthermore, it will be understood that the barrier effect obtained works in both directions, that is to say on both sides of a demarcation line 22 forming a protective barrier 20 made according to the teachings of the invention.

[0118] Thus, to illustrate that the barrier effect according to the invention is not unidirectional, one can, for example, consider the case of a laminated glazing 10 consisting of a roof with a hole intended to allow the passage of a vehicle antenna. In this example, if a crack were to start from the edge of the hole, then the crack would be stopped by a demarcation line 22 surrounding it, thanks to which said crack would not propagate beyond the demarcation line 22 to the entire roof. Preferably, a protective barrier 20 is then made in each of the two panes of glass that make up the laminated glazing 10.

[0119] SECOND METHOD OF IMPLEMENTATION A second embodiment illustrated in figures 18 to 20 will be described below, in which the laminated glazing 10 forms a vehicle windscreen.

[0120] Figure 18 represents part of a laminated glazing 10 according to a second embodiment in which said glazing is a windscreen whose protected area ZP is constituted by the part of the first sheet 1 of glass located opposite an accessory 5 such as at least one Advanced Driver Assistance System (ADAS) like a camera or a radar (LiDAR).

[0121] Figure 18 illustrates an example of the realization of a closed demarcation line 22 (presenting for example a quadrilateral shape, in a triangular variant) to form around said protected area ZP a barrier 20 for protection against the propagation of a fragmentation or cracking of the glass.

[0122] Figures 19 and 20 represent said laminated glazing 10 which has suffered an impact, for example from gravel, which has caused a crack 100 in the outer sheet 1 of glass, said crack 100 having one or more cracks.

[0123] Advantageously, figures 19 and 20 illustrate the barrier effect obtained by said demarcation line 22 by blocking the propagation of the crack(s) of the cracking 100 in the glass sheet 1 in order to protect said protected area ZP in order to guarantee the operation of the accessory 5.

[0124] Compared to a side glazing according to the first embodiment, the laminated glazing 10 comprises two sheets 1 and 3 having the same dimensions, i.e., without any indentation. The laminated glazing 10 includes a specific area 3b. This specific area 3b is used for the installation of the accessory 5, such as a camera or radar, as shown in Figure 18.

[0125] The specific area 3b is then at least as large as the camera's field of view at the distance from the outer glass sheet 1. Accessory 5 is, for example, glued to the inner glass sheet 3 or to the outer glass sheet 1. To achieve this, the inner glass sheet 3 is drilled to accommodate accessory 5.

[0126] In this second embodiment, the outer glass sheet 1 must remain intact because cracks would result in poor image quality for the camera and therefore malfunction of the camera function. The situation would be analogous to a radar whose operation would be affected by a crack located opposite it in the glass sheet 1. Consequently, the sensitive area to be protected on such a windshield is the portion of the first glass sheet 1 of the laminated glazing 10 that is located opposite the accessory. 5, of specific zone 3b.

[0127] In this second mode, the protective barrier 20 extends into the first sheet 1 of glass of the windscreen to protect the said sensitive area located opposite the specific area 3b. It is understood from this that the demarcation line 22 encircles the specific area to be protected as visible in figure 18.

[0128] The demarcation line 22 is arranged so that at a minimum the area defined by said demarcation line 22 is identical to the surface of the specific area 3b, i.e. the field of vision of the accessory 5 at the distance of the outer glass sheet 1.

[0129] Preferably, the specific area 3b is masked with an opaque layer such as enamel. This opaque layer, applied to either of the glass sheets, advantageously also masks the demarcation line 22.

[0130] As previously stated, the first embodiment (side glazing) and the second embodiment (windscreen) of the laminated glazing 10 are given as non-limiting examples of application of the invention.

[0131] The laminated glass unit (10) is designed to be installed in a structure (not shown). This structure is a roof, a vehicle door, or the vehicle itself, depending on the type of laminated glass unit. The structure housing the laminated glass unit is considered to have an opening, and the glass unit is sized to be larger than this opening.

[0132] Advantageously, the positioning of said at least one demarcation line 22 depends on the mounting of the glazing 10 in the structure. Indeed, the laser treatment used to form the protective barrier 20 is likely to be visible. To prevent said demarcation line 22 from being visible to the user on a laminated side glazing 10, the demarcation line 22 is positioned so that it is hidden when the laminated glazing 10 is mounted on the vehicle.

[0133] Alternatively, the glazing 10 can be configured to have one pane recessed relative to the other and at least one specific area. In this case, it is evident that said glazing 10 is likely to include at least two demarcation lines 22 according to the invention to protect each part of the glazing requiring protection.

Claims

Demands

1. Laminated glazing (10), particularly for motor vehicles, comprising at least a first sheet (1) of glass and a second sheet (3) of glass bonded together by means of an interlayer (2) of polymer material disposed between the first sheet (1) of glass and the second sheet (2) of glass, said laminated glazing (10) being characterized in that at least one (1) of said sheets (2, 3) of glass of the glazing (10) comprises at least one barrier (20) for protecting a defined area of ​​said sheet (1), referred to as the protected area (PA), said at least one barrier (20) being capable of protecting said protected area (PA) against the propagation of fragmentation or cracking of the glass and consisting of at least one demarcation line (22) comprising a multitude of points (PI), each of which corresponds to a micro-channel (30) which,obtained by local modification of the material by means of a laser device (500) generating a Bessel beam (F) or by laser filamentation, extends in a straight line over at least 80%, preferably over 100%, of the thickness (e) of said glass sheet (1) and orthogonally to the surfaces of said glass sheet (1).

2. Laminated glazing (10) according to claim 1, characterized in that two adjacent impact points (PI; Plj; Plj+i) produced by the Bessel beam (F) or by laser filamentation are separated by a distance (d) between 1 and 50 pm, preferably between 5 and 20 pm.

3. Laminated glazing (10) according to claim 2, characterized in that the value of the distance (d) between two points of impact (PI) is between two and seven times the diameter (D) of the central lobe (Pc) of the Bessel beam (F) generated by the laser device (500) or of the laser beam used for laser filamentation, said diameter (D) of the central lobe (Pc) being between 2 and 10 pm, preferably between 4 and 7 pm, for example equal to 5 pm.

4. Laminated glazing (10) according to any one of claims 1 to 3, wherein the local modification of the material is obtained by means of the laser device (500) generating the Bessel beam (F), characterized in that said at least one sheet (1) of glass of the laminated glazing (10) comprising the protective barrier (20) has a thickness (e) between 1 mm and 4 mm, preferably between 1.4 mm and 2.6 mm.

5. Laminated glazing (10) according to any one of the preceding claims, in particular intended for use as a side window on a motor vehicle, said side window being mounted sliding relative to a door-type structure by means of an associated movement system, characterized in that said glazing (10) has an edge (3a) of the second sheet (3) of glass which is set back relative to the edge (la) of the first sheet (1) of glass on at least part of the perimeter of the glazing (10).

6. Laminated glazing (10) according to claim 5, characterized in that the first sheet (1) of glass comprises at least one hole (40) for fixing said glazing (10) to the displacement system and in that said at least one demarcation line (22) forming the protective barrier (20) surrounds said at least one hole (40) so as to form a protected zone (PZ) around said hole (40) to ensure the fixing of the glazing (10) in the event of fragmentation or cracking occurring in the first sheet (1) of glass.

7. Laminated glazing (10) according to claim 5, characterized in that the demarcation line (22) extends over the area of ​​the first sheet (1) of glass not covered by the second sheet (3) of glass or extends over the area of ​​the first sheet (1) of glass covered by the second sheet (3) of glass or extends opposite the edge (3a) of the second sheet (3) of glass.

8. Laminated glazing (10) according to any one of claims 1 to 4, in particular intended for use as a windscreen on a motor vehicle, wherein the second sheet (3) of glass comprises a specific area (3b) such as an opening at which an accessory (5) such as a camera or radar is fixed, characterized in that said demarcation line (22) is made in the first sheet (1) of glass so as to obtain a protected area (PA) opposite said specific area (3b) to ensure the operation of said accessory (5) in the event of fragmentation or cracking occurring in the first sheet (1) of glass.

9. A method for treating a sheet (1) of glass to obtain at least one barrier (20) protecting a defined area of ​​said sheet (1), referred to as the protected area (PA), against the propagation of fragmentation or cracking of the glass, said sheet (1) of glass being intended to be bonded to a second sheet (3) of glass by means of an interlayer (2) of polymer material to form laminated glazing (10), said method comprising a treatment step consisting of creating at least one demarcation line (22) which, constituting said at least one barrier (20) protecting the protected area (PA), comprises a multitude of points (PI), each of which corresponds to a micro-channel (30) obtained by a local modification of the material by means of a laser device generating a Bessel beam (F) or a beam used for laser filamentation and extending in a straight line over at least 80%, preferably 100%, of the thickness (e) of said glass sheet (1), orthogonally to the surfaces of said glass sheet (1).

10. A treatment method according to claim 9, characterized in that said treatment step consists of scanning said glass sheet (1) with the Bessel beam (F) generated by the laser device (500) or with the beam used for laser filamentation to create the demarcation line (22) constituting said at least one barrier (20) protecting against the propagation of a fragmentation or cracking of the glass to said protected zone (ZP), said Bessel beam (F) making it possible to create said multitude of impact points (PI) each of which corresponds to a micro-channel (30) obtained by a local modification of the material in the glass sheet (1).

11. Processing method according to claim 10, characterized in that the laser device generating the Bessel beam (F) or the beam used for laser filamentation has a wavelength between 400 and 1100 nm, preferably a wavelength between 800 and 1100 nm, for example equal to 1032 nm or 1064 nm.

12. Processing method according to claim 10 or 11, characterized in that the Bessel beam (F) is shaped to have a length (LB) which is at least equal to the thickness (e) of said glass sheet (1).

13. Processing method according to any one of claims 10 to 12, characterized in that the laser device generating the Bessel beam (F) has pulses generated with a working frequency between 1 and 1000 kHz.

14. A treatment method according to any one of claims 10 to 13, characterized in that the laser device generating the Bessel beam (F) has an energy per pulse train which is between 100 and 10000 pJ, preferably between 1000 and 8000 pJ, each pulse train being able to be composed of 1 to 16 pulses, so that the energy per pulse is between 100 and 4000 pJ, preferably between 300 and 3000 pJ.

15. A treatment method according to any one of claims 12 to 14, characterized in that the laser device generating the Bessel beam (F) has pulses whose duration is between 0.1 and 100 ps, ​​preferably between 0.1 and 10 ps.

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