The present invention relates to a laminated glazing for use in a vehicle, in particular for use as a windscreen in a vehicle such as an automobile.

Conventional laminated glazings for automotive windscreens comprise two plies of soda-lime- silicate glass joined by a sheet of polyvinyl butyral (PVB). Typically, each glass sheet is 2.1mm thick and the PVB sheet is typically 0.76mm thick.

Examples of known vehicle windscreens are described in GB1225941A.

As is known in the art, a laminated automotive windscreen provides the driver of the vehicle with improved safety benefits. However, vehicle manufacturers are also addressing vehicle safety in the event of a forward collision with a pedestrian.

In the event of a collision with a pedestrian, the pedestrian may impact the vehicle windscreen thereby causing further injury to the pedestrian.

The present invention aims to provide a vehicle windscreen that is arranged to lower the risks of serious pedestrian injuries in case the vehicle collides with a pedestrian.

Accordingly, from a first aspect the present invention provides a laminated glazing for a vehicle windscreen comprising a first sheet of glazing material joined to a second sheet of glazing material by at least a first sheet of adhesive interlayer material, each of the first and second sheets of glazing material and the first sheet of adhesive interlayer material having a respective first major surface and opposing second major surface, wherein the second major surface of the first sheet of glazing material faces the first major surface of the second sheet of glazing material and the first sheet of adhesive interlayer material is between the first and second sheets of glazing material; further wherein at least a first weakening device is positioned between the first and second sheets of glazing material, the first weakening device being arranged to break at least one of the first and second sheets of glazing material in the event of an impact on the first major surface of the first sheet of glazing material; characterised in that the first weakening device is positioned in a first opening in the first sheet of adhesive interlayer material.

By providing the weakening device in an opening in the first sheet of adhesive interlayer material, the weakening device is part of the laminated glazing making it simple to implement the present invention into a vehicle.

Preferably at least a second weakening device is positioned in the first opening in the first sheet of adhesive interlayer material. In such embodiments, there are at least two weakening devices in the first opening in the first sheet of adhesive interlayer material. Preferably at least a second weakening device is positioned in a second opening in the first sheet of adhesive interlayer material. In such embodiments, the first sheet of adhesive interlayer material has at least two openings therein.

Preferably the laminated glazing further comprises at least one other weakening device between the first and second sheets of glazing material, the at least one other weakening device being positioned in a respective opening in the first sheet of adhesive interlayer material.

In some embodiments a barrier surrounds the first weakening device in the first opening, the barrier restricting the flow of interlayer material reaching the first weakening means during lamination.

Preferably the barrier is dimensionally stable during the lamination process.

Preferably the barrier is in the form of an annulus.

Preferably the barrier comprises a compressible material, preferably rubber.

Preferably the barrier comprises PET or polycarbonate.

Preferably the barrier is chemically inert with respect to the first sheet of adhesive interlayer material.

In some embodiments the first weakening device compnses at least one impacting device having a base portion for contacting the second major surface of the first sheet of glazing material and at least a first contact portion for contacting the first major surface of the second sheet of glazing material.

In the event of an impact with the laminated glazing on the first major surface of the first sheet of glazing material, the first contact portion of the impacting device contacts the first major surface of the second sheet of glazing material to cause the second sheet of glazing material to break.

Preferably the first contact portion is pointed.

Preferably the base portion of the impacting device tapers to the first contact portion.

Preferably the impacting device is cone shaped or pyramid shaped.

Preferably the first contact portion is harder than the second sheet of glazing material.

Preferably the first contact portion comprises at least one of boron nitride, boron carbide, tungsten carbide, and diamond.

Preferably at least a first raised portion extends from the base portion, the first raised portion having a first end adjacent the base portion and a second end opposite the first end of the first raised portion, the second end of the first raised portion comprising the first contact portion. Preferably the first raised portion is integrally formed with the base portion, although in some embodiments the first contact portion is made from a different material to the base portion.

Preferably the first raised portion is cone shaped or pyramid shaped or a spike.

In some embodiments the laminated glazing further comprises another weakening device positioned in another opening in the first sheet of adhesive interlayer material, wherein the first opening is spaced apart from the another opening by a first spacing.

Preferably the first spacing is between 0.5cm and 50cm, more preferably between 0.5cm and 40cm, more preferably between 0.5cm and 30cm, more preferably between 0.5cm and 20cm, more preferably between 0.5cm and 10cm.

In some embodiments the first opening is spaced apart from a peripheral edge of the laminated glazing.

Preferably the first opening is spaced apart from the peripheral edge of the laminated glazing by between 1cm and 20cm, more preferably between 1cm and 15cm, more preferably between 1cm and 10cm, more preferably between 1cm and 9cm or 8cm or 7cm or 6cm or 5cm.

Preferably the first opening is spaced apart from a peripheral edge of the laminated glazing configured to be a lower edge of the laminated glazing when installed in a vehicle.

In some embodiments the first opening is in a region of the laminated glazing having an obscuration band thereon.

In some embodiments the first and/or second sheet of glazing material comprises one or more weak points or lines arranged to weaken the laminated glazing in the event of an impact therewith.

Preferably the weak points or lines are on a major surface of the first and/or second sheet of glazing material.

In some embodiments the laminated glazing is a part of a vehicle windscreen for installing in a vehicle.

In some embodiments there are a plurality of openings in the first sheet of adhesive interlayer material.

Preferably the plurality of openings are spaced apart from a peripheral edge of the laminated glazing configured to be the lower edge of the laminated glazing when installed in a vehicle. Preferably the plurality of openings are arranged in a line. Preferably the line is parallel to a peripheral edge of the laminated glazing, more preferably a peripheral edge configured to be the lower edge of the laminated glazing when installed in a vehicle.

In some embodiments the first sheet of glazing material has a thickness between 1mm and 5mm, preferably between 1.3mm and 3mm

In some embodiments the second sheet of glazing material has a thickness between 1mm and 5mm, preferably between 1.3mm and 3mm.

In some embodiments the second sheet of glazing material is thinner than the first sheet of glazing material.

In some embodiments the first major surface of the first sheet of glazing material is a convex surface and the second major surface of the second sheet of glazing material is a convex surface.

In some embodiments there is only a single sheet of adhesive interlayer material between the first and second sheets of glazing material.

In some embodiments the first opening in the first sheet of adhesive interlayer material is circular.

In some embodiments the first opening in the first sheet of adhesive interlayer material is oval, or square, or rectangular, or trapezoidal, or triangular.

In some embodiments the first opening in the first sheet of adhesive interlayer material has at least a first axis of symmetry, preferably a first and a second axis of symmetry.

In embodiments wherein the first opening is one of a plurality of openings, it is preferred that each opening in the plurality of openings has the same shape, and/or the same area.

The laminated glazing has other preferable features.

Preferably the laminated glazing is curved in at least one direction. Preferably the radius of curvature in the at least one direction is between 500mm and 20000mm, more preferably between 1000mm and 8000mm.

Preferably the first sheet of adhesive interlayer material compnses polyvinyl butyral (PVB), acoustic modified PVB, a copolymer of ethylene such as ethylene vinyl acetate (EVA), polyurethane (PU), poly vinyl chloride (PVC), a copolymer of ethylene and methacrylic acid (EMA) or Uvekol (a liquid curable resin).

Preferably the at least one sheet of adhesive interlayer material has a thickness between 0.3mm and 2.3mm, more preferably between 0.3mm and 1.6mm, most preferably between 0.3 and 0.8mm. Preferably the first and/or second sheet of glazing material has a thickness between 1mm and

3mm.

Preferably the first and/or second sheet of glazing material has a thickness between 1 4mm and 2.8mm, more preferably between 1.6mm and 2.3mm.

Preferably the thickness of the laminated glazing is between 3mm and 10mm.

Preferably the first and/or second sheet of glazing material is a sheet of soda-lime-silicate glass, in particular a sheet of float glass.

Preferably the first and/or second sheet of glazing material is a sheet of alkali aluminosilicate glass.

Preferably the first and/or second sheet of glazing material comprises at least about 6wt%

(percent by weight) aluminium oxide (AI ₂ O ₃ ).

Preferably the first and/or second sheet of glazing material is chemically strengthened i.e. chemically strengthened glass. When the first and/or second sheet of glazing material is chemically strengthened, preferably the chemically strengthened sheet of glazing material has a thickness less than 1.2mm, more preferably between 0.3mm and 1mm, even more preferably between 0.4mm and 0.9mm.

The present invention also provides from a second aspect use of a laminated glazing according to the first aspect of the present invention as a windscreen in a vehicle for reducing the potential for injury to a person involved in a collision with the vehicle.

The present invention will now be described with reference to the following figures (not to scale) in which:

Figure 1 is a plan view of a laminated glazing according to the present invention;

Figure 2 is a schematic cross-sectional view of the laminated glazing shown in figure 1 along the line M-M’

Figure 3 is a schematic exploded isometric view of the laminated glazing shown in figure 1 ;

Figure 4 is a schematic exploded cross-sectional view of the laminated glazing shown in figure 1 along the line M-M’;

Figure 5 is an isometric view of an impacting device used in the laminated glazing shown in figures 1-4;

Figure 6 is an isometric view of another impacting device for use in the laminated glazing shown in figures 1-4; Figure 7 is a schematic exploded isometric view of another laminated glazing similar to that shown in figure 1;

Figure 8 is a plan view of an impacting device for use in the laminated glazing shown in figure 7;

Figure 9 is a cross-sectional view of the impacting device shown in figure 8 along the line N-ΆG ; and

Figure 10 is the view from inside a vehicle that has a windscreen in accordance with the present invention installed therein.

Figure 1 shows a plan view of a laminated glazing in accordance with the present invention. In this example the laminated glazing 1 is a vehicle windscreen.

In plan view the windscreen 1 is substantially trapezoidal and has lower comers a and b and upper comers c and d. The lower edge a-b lies closest to the vehicle bonnet when the windscreen 1 is installed in a vehicle.

The laminated glazing 1 has an obscuration band 6 extending around the peripheral edge thereof.

With reference to figures 1, 2, 3 and 4 the laminated glazing 1 comprises a first sheet of glass 3 joined to a second sheet of glass 5 by means of a sheet of polyvinyl butyral (PVB) 7.

The first sheet of glass 3 has a first major surface 3a and an opposing second major surface 3b. The second sheet of glass 5 has a first major surface 5a and an opposing second major surface 5b. The sheet of PVB 7 has a first major surface 7a and a second opposing major surface 7b.

The second major surface 3b faces the first major surface 5a and the sheet of PVB 7 is between the first and second sheets of glass 3, 5.

In this example the first sheet of glass 3 is an outer sheet of glass and the second sheet of glass is an inner sheet of glass.

Using conventional nomenclature, the first major surface 3a of the first sheet of glass 3 is “surface one” (or SI) of the laminated glazing 1. The second major surface 3b of the first sheet of glass 3 is “surface two” (or S2) of the laminated glazing 1. The first major surface 5a is “surface three” (or S3) of the laminated glazing 1. The second major surface 5b of the second sheet of glass 5 is “surface four” (or S4) of the laminated glazing 1.

In this example each of the first and second glass sheets 3, 5 has a thickness less than 4mm. In this example the first glass sheet 3 has a thickness of 2.1mm and the second glass sheet 5 has a thickness of 1 8mm. The sheet of PVB 7 has a thickness of 0.76mm but may have a thickness between 0.3mm and 1.6mm. On a portion of the second major surface 5b of the second sheet of glass 5 is an obscuration band 6. The obscuration band has an optically opaque region 6a and a fade out region 6b comprising a plurality of optically opaque dots.

The obscuration band may be on any major surface 3a, 3b, 5a, 5b, either individually or in any combination thereof.

The first and/or second sheet of glass may have a soda-lime-silicate composition. A typical soda- lime-silicate glass composition is (by weight), S1O2 69 - 74 %; AI2O3 0 - 3 %; Na ₂ 0 10 - 16 %; K ₂ 00 - 5 %; MgO 0 - 6 %; CaO 5 - 14 %; S03 0 - 2 %; Fe ₂ C> ₃ 0.005 - 2 %. The glass composition may also contain other additives, for example, refining aids, which would normally be present in an amount of up to 2 %. The soda-lime-silicate glass composition may contain other colouring agents such as C03O4, NiO and Se to impart to the glass a desired colour when viewed in transmitted light. The transmitted glass colour may be measured in terms of a recognised standard such as BS EN410.

Other glass composition may be used, such as alkali aluminosilicate glass, and the first and/or second sheet of glass may be chemically strengthened. When using chemically strengthened glass sheets, the thickness of such glass sheets may be less than 1mm, preferably in the range 0.4mm to 0.9mm.

The sheet of PVB 7 has a plurality of circular openings 9 therein (only one of which is labelled in figure 1). In the example illustrated, there are nine circular openings 9 arranged in a row (labelled 9a) substantially parallel to the lower edge a-b of the laminated glazing 1. That is, the centre of each opening 9 lies in a line substantially parallel to the lower edge a-b of the laminated glazing 1. Each opening 9 is the same diameter. In other embodiments, the openings 9 may have different shapes and/or area.

Each opening 9 communicates at one end with the first major surface 7a and at the other end with the second major surface 7b.

Located in the circular opening 9 is a ring 11 of rubber or other similar compressible material (i.e. other elastic polymer or elastomer). The ring 11 may be an O-ring.

Positioned in the ring 11 is an impacting device 13 in the form of a unitary formed particle. An example of such a particle includes a precision shaped grain of the type provided by 3M™ under the trademark Cubitron™.

The impacting device 13 has a base portion 15 for contacting the second major surface 3b of the first sheet of glass 3 and a pointed portion 17 for contacting the first major surface 5a of the second sheet of glass 5.

Each opening 9 in the row of openings 9a has a respective ring 1 la and impacting device 13a positioned therein. The base portion 15 is circular and fits inside the ring 11. The diameter of the base portion 15 may be slightly less than the inner diameter of the ring 11.

In the embodiment as shown in figure 2, the base portion 15 is in contact with second major surface 3b of the first sheet of glass 3 and the pointed portion 17 is in contact with the first major surface 5a of the second sheet of glass 5. In other embodiments, the impacting device 13 may be sized to be movable in the space between the glass sheets 3, 5 such that the base portion 15 and/or the pointed portion 17 are not permanently in contact with the respective glass surfaces in the laminated glazing 1.

Upon an impact occurring in the direction of arrow 19 (on the first major surface 3a of the laminated glazing 1) the impacting device 13 causes the second sheet of glass 5 to break as the pointed portion 17 becomes pressed against the first major surface 5a of the second sheet of glass 5. The impacting device 13 has a hardness greater than the second sheet of glass 5 and causes cracks to propagate in the second sheet of glass 5.

Upon breaking, pieces of the broken second sheet of glass 5 may remain joined to the sheet of adhesive interlayer material (in this example PVB) 7.

The second sheet of glass 5 may have microcracks previously generated in the vicinity of the contact with the pointed portion to enable the second sheet of glass 5 to break more easily, for example being formed as described in US2005/0175844A1 and/or US2006/0138798A1.

Figure 5 shows in more detail the impacting device 13 and the ring 11. The ring 11 is a circular annulus and has an outer diameter 1 la and an inner diameter 1 lb.

The impacting device 13 has a circular base portion 15 tapering to a pointed portion 17. The impacting device 13 is a conical shaped particle and may be solid or hollow.

The base portion 15 has a diameter 15a and in some embodiments is sized to be a snug fit in the ring 11. In other embodiments, the diameter 15a is less than the inner diameter 1 lb.

The impacting device 13 has a height 16, the height being the distance between the base portion 15 and the end of the pointed portion 17. The height 16 is preferred to be the same as the thickness of the sheet of PVB 7, although the height may be slightly less than the thickness of the sheet of PVB 7 (and therefore less than the spacing between the first and second sheets of glass 3, 5).

Figure 6 shows another impacting device 23 for use in the present invention. In this example the impacting device is a unitary particle in the form of a square pyramid, which may be a right square pyramid.

The impacting device has a square base portion 25 and a pointed portion 27. The impacting device 23 may be incorporated into any shape opening in the sheet of PVB 7, for example a circular opening 9. Preferably a ring of material is used into which the base of the particle 23 fits. The ring of material may be a square ring and the material may be compressible i.e. a rubber.

The impacting devices 13, 23 are suitably hard compared to the first and/or second sheet of glass 3, 5. Suitable material for the impacting devices 13, 23 (in particular the pointed portions 17, 27) includes boron nitride, boron carbide, tungsten carbide, and diamond.

Instead of being unitary formed, the impacting devices 13, 23 may have a multi -component construction, in particular at the pointed portion. For example, the pointed portion may be a diamond tip.

Figure 7 shows an exploded schematic perspective view of another laminated glazing 31 in accordance with the present invention. In this example, the laminated glazing 31 is a vehicle windscreen having the same configuration in plan view as the windscreen 1 shown in figure 1.

The laminated glazing 31 has a first sheet of glass 33 joined to a second sheet of glass 35 by means of a sheet of PVB 37.

Each of the first and second sheets of glass 33, 35 have a soda-lime-silicate composition. Either or both of the first and second sheets of glass 33, 35 may be chemically strengthened.

The sheet of PVB 37 has four elongate openings therein arranged towards a lower edge a-b of the laminated glazing 31. The elongate openings are arranged in two rows, a first lower row containing the elongate opening 39 and a second row (above the first row) containing openings 39’, 39” and 39”. Each row is arranged to be parallel with the lower edge a-b of laminated glazing 31.

Positioned in the elongate opening 39 is a suitable sized ring of elastomeric material 41.

Positioned in each elongate opening 39’, 39” and 39’” is a respective suitable sized ring of elastomeric material 4 G, 4 G ’, 4 G ” .

Positioned in the ring 41 is an impacting device 43. Positioned in the ring 4G is an impacting device 43’. Positioned in the ring 41” is an impacting device 43”. Positioned in the ring 4G” is an impacting device 43’”.

The impacting devices 43, 43’, 43” and 43”’ are each configured in a similar way, and have the same width, although the impacting device 43 is longer than the impacting devices 43’, 43” and 43’”.

The impacting devices 43, 43’, 43” and 43”’ each comprise a base portion and a plurality of raised portions extending from the base portion. The raised portions face towards the second sheet of glass 35. The impacting devices 43, 43’, 43” and 43’” function in essentially the same way as the impacting device 13 shown in figures 2-4. In the event of an impact in the direction of the arrow 19, at least one of the raised portions of at least one ofthe impacting devices 43, 43’, 43” and 43’” contacts and is pressed into the major surface of the second sheet of glass 35 facing the first sheet of glass 33 to cause the second sheet of glass 35 to break.

Figure 8 shows more detail of the impacting device 43’ positioned in the ring 41 ’ Figure 9 is a cross-sectional view along the lineN-N of figure 8.

With reference to figures 8 and 9, the impacting device 43’ has a base portion 45’ and sixteen raised portions 53 extending upwards therefrom (only one of which is labelled).

The raised portions 53 each have a square pyramid form having a respective base portion 55 and pointed portion 57. Each raised portion has the same height and the pointed portions of the raised portions 53 lie in a plane that is parallel with the inner facing surface of the second sheet of glass 35.

The raised portions 53 may be integrally formed with the base portion 45’. Suitable material for the raised portions 53 includes suitable hard materials relative to the second sheet of glass 35 including boron nitride, boron carbide, tungsten carbide.

The other two impacting devices 43” and 43” are configured in the same way as the impacting device 43’. The impacting device 43 is similar to the impacting device 43’ except the base portion thereof is longer and there are more raised portions extending upwards therefrom.

In an alternative embodiment, one or more ofthe elongate openings 39, 39’, 39” and 39”’ in the sheet of PVB 37 contains two weakening devices, for example two impacting devices of the type shown in figure 8, or one type as shown in figure 8 and one type as shown in figure 5 or 6.

Figure 10 is a schematic view from the inside of a vehicle that has a windscreen 101 according to the present invention installed therein.

The vehicle windscreen 101 is similar to the vehicle windscreen 1 shown in figures 1-4 and includes an outer pane of glass joined to an inner pane of glass by a sheet of adhesive interlayer, which is this example is PVB.

The sheet of PVB contains nine openings in a lower region thereof. Three of the openings on the left hand side of the lower region are circular (group 103), so are similar to the opening 9 in the sheet of PVB 7 of figures 1-4; three of the openings in the lower central region are elongated (group 105), so are similar to the elongate openings 39’, 39” and 39” in the sheet of PVB 37 of figure 7; and three of the openings on the right hand side of the lower region are also circular (group 107), so are similar to the opening 9 in the sheet of PVB 7 of figures 1-4. Positioned in each of the openings in group 103 and group 107 is a ring of material and an impacting device, such as impacting device 13 shown in figures 2-4. The ring of material prevented the PYB from flowing to the impacting device in the opening during lamination, which would otherwise reduce the effectiveness of the impacting device.

Positioned in each of the openings in group 105 is an elongate ring of material and an impacting device, such as impacting device 43’ shown in figures 7 and 8. The elongate ring of material (such as ring of rubber 4 of figure 7 and 8) prevented the PVB from flowing to the impacting device in the opening during lamination, which would otherwise reduce the effectiveness of the impacting device.

The windscreen 101 also has an obscuration band thereon (below line 106). The obscuration band ensures the openings 103, 105, 107 and associated rings of material/impacting devices are not visible from inside the vehicle.

The arrangement of openings may be different for a different vehicle. Also, there may be openings with associated rings and impacting devices that extend up the left and/or right side of the windscreen 101, or into other regions thereof.

In the previous examples, one or more of the glass sheets may be provided with a weakness of the type described in US2005/0175844A1 and US2006/0138798A1.

Furthermore, in the previous examples a ring of material was used to prevent interlayer material from flowing into the opening in the sheet of adhesive interlayer material during a suitable lamination process to join first and second sheets of glass by means of the sheet of adhesive interlayer material. Such a lamination process uses suitably high temperature and pressure. If the interlayer material flows into the opening to contact the impacting device, the performance thereof in breaking a glass sheet may be reduced.

Whilst it may be possible to control the lamination process such that the adhesive interlayer material does not flow to the impacting device, this is not preferred because it is difficult to control how the adhesive interlayer flows during lamination. Hence, it is preferred to use a barrier in the opening to prevent such flow of the adhesive interlayer material.

The laminated glazing 1 shown in figures 1-4 may be made as follows.

The first sheet of glass 3 is placed onto a suitable support such as a table with a horizontal surface. Next, a sheet of PVB is provided and the openings 9 are made in the sheet of PVB, for example by punching out or cutting, to give sheet of PVB 7 with openings therein. The sheet of PVB 7 with openings 9 therein is then positioned on the first sheet of glass 3. Next, a rubber O-ring 11 is positioned into each opening 9. Next, an impacting device 13 is positioned inside each rubber O-ring in each opening 9 so that the respective rubber O-ring surrounds the respective impacting device 13.

Next, a second sheet of glass 5 is positioned on the sheet of PVB 7. The unlaminated stack of components is then laminated at a suitably high temperature and pressure to join the first sheet of glass 3 to the second sheet of glass 5 by the sheet of PVB 7. During lamination, no PVB was able to flow past the O-rings 11 because each O-ring 11 forms a seal with the inner facing surfaces of the first and second sheets of glass 3, 5 (surface 3b of the first sheet of glass 3 and surface 5a of the second sheet of glass 5) so that each impacting device 13 remains in an opening in the PVB and not in direct contact with the sheet of PVB 7.

If a liquid resin is used instead of a sheet of adhesive interlayer material prior to joining the first sheet of glass to the second sheet of glass, the above method is modified.

The first sheet of glass 3 is provided with a barrier around the periphery thereof. The O-rings 11 are then positioned on the first sheet of glass 3 in the desired location, and an impacting device 13 is positioned inside each O-ring 11. Next, the liquid resin is poured on the first sheet of glass 3 and is prevented from contacting the impacting devices 13 because of the O-rings 11 surrounding each impacting device. The O-rings 11 act as a barrier to the liquid resin in the same way as discussed above when using a sheet of PVB and suitably high temperature and pressure for the lamination process.

Next, the second sheet of glass 5 is positioned on the uncured resin, which may be partially cured. The resin is allowed to fully cure, thereby joining the first sheet of glass 3 to the second sheet of glass 5

The present invention finds particular application as a windscreen for a vehicle such as an automobile, lorry, truck or bus.