Automotive glazing system having a reversible metal electrodeposition cell

Abstract

A laminated glazing system having a reversible metal electrodeposition cell is disclosed. The glazing system comprises a glazing and a control unit, wherein the glazing comprises a first glass layer, a second glass layer, at least one bonding layer a reversible metal electrodeposition cell and a control unit. The glazing of the system of the disclosure has good contrast between the darkest state and the clearest state, having both privacy and transparency features as required for automotive standards, provides thermal comfort and has improved energy consumption.

Description

AUTOMOTIVE GLAZING SYSTEM HAVING A REVERSIBLE METAL ELECTRODEPOSITION CELL

[0001] The present disclosure falls in the field of automotive glazing and relates to a glazing system having a reversible metal electrodeposition cell.Background

[0002] Switchable devices have emerged as a class of next-generation optoelectronics with the development of smart switchable glazing, such as smart windows or roofs. Switchable glazing is commonly manufactured including different technologies such as polymer dispersed liquid crystal (PDLC), suspended particle device (SPD), liquid crystal (LC), and electrochromic (EC). In general, by applying a voltage, the properties of the material cell change, and the glazing can be switched from one state to another state. Usually, those states refer to the darkest state (low light transmission state) and the clearest state (high light transmission state). Each of these technologies has its own drawbacks and challenges when integrated into a glazing for automotive applications.

[0003] For instance, liquid crystal-based technologies, such as LC and PDLC cells, offer control over transparency levels of the glazing but have a limited range of color choices; they are not effective in blocking infrared (IR) light, which negatively influences the optimal heat control of the vehicle; and require continuous voltage supply to maintain the desired state. On the other hand, SPD devices primarily switch only between a transparent and a dark state which does not allow to cover light transmission states in between these two opposite states; in addition, they also require a continuous energy supply. EC devices have also a limited color choice and have a slower switching speed.

[0004] Besides the nature of each switchable technology as mentioned above, different issues are still of great concern for selecting an appropriate switchable device to be integrated into glazing for automotive applications. One of the main challenges refers to the total visible light transmission (VLT) achieved when switching from the darkest state to the clearest state or vice versa. Sufficient contrast between these two states is needed to have both privacy and transparency properties for the automotive window when needed. For instance, EC cells used in automotive applications switch from a VLT of 3% in the darkeststate to 21 % in the clearest state, which does not provide sufficient opaqueness for the darkest state nor sufficient transparency for the clearest state mode.

[0005] Color neutrality is also a key factor when switching technologies are integrated into automotive glazing; for instance, SPD or PDLC do not have a high color neutrality, particularly a high black color neutrality, which would be a desired feature for roofs and sidelites in a vehicle.

[0006] Another issue relates to the thermal comfort inside of the automobile. Automotive glazing usually includes coatings and / or plastic interlayers that reflect IR light to prevent excessive heating of the vehicle during summer days. A disadvantage of the current state of the art is that this approach also reduces the IR transmitted to the cabin during cold days increasing the need for cabin heating and therefore increasing the power consumption of the vehicle. To this date, automotive switchable cells have not been able to dynamically reflect IR light providing solar protection that allows to tune cabin temperature by changing the optical state of the cell. In addition, many of the current technologies use high voltage during their operation, for instance, SPD operates at approximately 100 V and PDLC at 48 V. Therefore, there is also a need for a glazing including low-voltage switchable cells with improved power consumption.

[0007] On top of this, automotive safety requirements in connection to the glazing need to be complied with. In the later days, glazing suitable for automotive applications also needs to be curved, so as to be integrated into the vehicle as a roof or windshield. Therefore, it is also necessary that switchable devices be flexible in order to reach the desired curvature.

[0008] In consequence, there is need to provide a glazing suitable for automotive applications that includes an alternative switchable technology that covers most of the advantages of the switchable devices known to this date and that overcomes the issues and challenges mentioned above.BRIEF SUMMARY

[0009] The present disclosure provides a solution for the above-mentioned issues providing a glazing system including a switchable device known as a reversible metal electrodeposition cell.

[0010] In one aspect, the disclosure provides a glazing system comprising a glazing and a control unit, wherein the glazing comprises a first glass layer having an outer major surface, surface one, and an inner major surface, surface two, wherein the outer major surface is opposite to the inner major surface; a second glass layer having an inner major surface, surface three, and an outer major surface, surface four, wherein the outer major surface is opposite to the inner major surface; at least one bonding layer arranged between the inner major surface of the first glass layer and the inner major surface of the second glass layer; and a reversible metal electrodeposition cell arranged between the first glass layer and the second glass layer and being in contact with the at least one bonding layer; and wherein the control unit is configured to apply an electrical field to the system, and wherein the reversible metal electrodeposition cell has electrically controllable optical properties.

[0011] In a reversible metal electrodeposition (RME) cell, an electrolyte containing metal ions is disposed between a pair of electrodes on which atoms of the same metal reside. In response to a voltage applied to the electrodes, metal dissolves from one electrode and deposits on the other. By reversing the polarity of the voltage, the direction in which the metal migration occurs is reversed. Therefore, RME cells have a different functioning mechanism in comparison to previous switching technologies such as SPD wherein microscopic droplets of liquid containing needle-like particles, are suspended in a matrix; or PDLC wherein liquid crystals are dispersed into a polymer material.

[0012] Integrating a reversible metal electrodeposition cell (RME) into automotive glazing provides a system suitable for automotive applications, having an optimal total visible light transmission (VLT) when switching from the darkest state to the clearest state or vice versa. Because of its working mechanism, RME cells enable drivers and passengers to actively control the transparency, reflectance, I R properties and color of the glazing; and provide good contrast between the darkest state and the clearest state, having both privacy and transparency features as required for automotive standards. In an embodiment of the disclosure, the glazing in the glazing system has a VLT in the darkest state ranging from0.005% to 2% and a VLT in the clearest state is greater than or equal to 2%.

[0013] The good contrast between the clearest and darkest state of the RME cell, which provides both privacy and transparency to the glazing as needed, also allows the projection of whatever static or dynamic items on the inner surface of the glazing, when installed in a vehicle, without the projection being visible from the outside when the glazing is in the darkest state.

[0014] Additionally, the RME cell integrated into the glazing system provides thermal comfort since it reflects IR light to some degree. In an embodiment, the glazing in the glazing system has a TTS in the darkest state less or equal than 16% and a TTS in the clearest state ranging from 16 to 70%. The glazing system might also be configured to switch between states when incident IR light is perceived providing a dynamic thermal control.

[0015] The glazing system of the disclosure also has improved energy consumption in comparison with high-voltage switchable cells like SPD or PDLC.

[0016] The glazing in the glazing system of the disclosure has a value of a* ranging from - 15.0 to 15.0 and b* ranging from -15.0 to 15.0 when measured in the CIELAB color scale.

[0017] Additionally, since RME cells can be made of flexible materials, this makes them optimal to be integrated into curved glazing for automotive applications.

[0018] In a second inventive aspect, it is disclosed an automotive roof, windshield or sidelite window having the automotive glazing system including the RME cell as mentioned previously.

[0019] In a third inventive aspect, it is disclosed a vehicle having the automotive glazing system including the RME cell as mentioned previously.Brief Description of the Several Views of the Drawings

[0020] These and other features and advantages of the disclosure will be seen more clearly from the following detailed description of preferred embodiments provided only by way of illustrative and non-limiting examples in reference to the attached drawings.

[0021] FIG. 1 A illustrates a cross section of a general embodiment of the disclosure.

[0022] FIG. 1 B illustrates a cross-section of a general embodiment of the disclosure further including an obscuration.

[0023] FIG. 2A illustrates a cross-section of a general embodiment of the disclosure further including additional coatings.

[0024] FIG. 2B illustrates a cross-section of a general embodiment of the disclosure further including additional interlayers.

[0025] FIG. 3 illustrates a cross-section of an example of a reversible metal electrodeposition cell.LISTING OF DRAWING ELEMENTS100 glazing system200 glazing201 first glass layer202 second glass layer101 outer major surface of the first glass layer102 inner major surface of the first glass layer103 inner major surface of the second glass layer104 outer major surface of the second glass layer4 bonding layer4.1 additional interlayer5 reversible metal electrodeposition (RME) cell501 first substrate502 first electrode503 electrolyte504 second electrode505 second substrate506 metal layer10 control unit6 obscuration7 solar control coating8 additional coatingDETAILED DESCRIPTION

[0026] The present disclosure can be understood by reference to the detailed descriptions, drawings, examples, and claims, of this disclosure. It should be noted, however, that this disclosure is not limited to the specific compositions, articles, devices, and methods disclosed unless otherwise specified, as such can, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing aspects only and is not intended to limit the scope of the disclosure.

[0027] The following terminology is used throughout the whole document to describe the features of the disclosure.

[0028] The term “layer”, as used in this context, shall include the common definition of the word, i.e.: a sheet, quantity, or thickness, of material, typically of some homogeneous substance.

[0029] The term “cell” as used in this context refers to a switchable layer.

[0030] Laminates, in general, are articles comprised of multiple layers of thin, relative to their length and width, material, with each thin layer having two oppositely disposed major faces, typically of uniform thickness, which are permanently bonded to one and other across at least one major face of each layer. The layers of a laminate may alternately be described as sheets or plies. Safety glazing is a glazing that conforms to all applicable industry and government regulatory safety requirements for the application.

[0031] Typically, laminated automotive safety glazing is made by bonding two glass layers, a first glass layer 201 and a second glass layer 202 together using a bonding layer 4 comprised of a sheet of transparent thermoplastic. The first glass layer 201 has an outer major surface 101 , surface one, and an inner major surface 102, surface two, wherein the outer major surface 101 is opposite to the inner major surface 102. The second glass layer 202 has an inner major surface 103, surface three, and an outer major surface 104, surface four, wherein the outer major surface 104 is opposite to the inner major surface 103. At least one bonding layer 4 is arranged between the inner major surface 102 of the first glass layer 201 and the inner major surface 103 of the second glass layer 202. An obscuration 6 may be also applied to the glazing.

[0032] FIG. 1A depicts an embodiment of the disclosure wherein the glazing system 100 comprises a glazing 200 having a first glass layer 201 , a second glass layer 202, at least one bonding layer 4 bonding the adjacent layers, a reversible metal electrodeposition cell 5 arranged between the first and second glass layers and in contact with the at least one bonding layer 4, and a control unit 10.

[0033] In an embodiment of the disclosure, the types of glass layers that may be used include but are not limited to soda lime, aluminosilicate, lithium aluminosilicate, borosilicate, and glass ceramics. In a preferred embodiment, first glass layers 201 , and second glass layer 202 are soda lime glass layers.

[0034] In yet another embodiment, the thickness of the first and second glass layers may vary widely and thus be ideally adapted to the requirements of the individual cases. In another embodiment, the thickness of each glass layer of the glazing of the disclosure ranges from 0.3 mm to 5 mm, preferably such as between 0.5 mm and 4.0 mm or between 1.5 mm and 3.8 mm, e.g. about 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, 2.0 mm, 2.1 mm, 2,2 mm, 2.3 mm, 2.4 mm, 2.5 mm, 2.6 mm, 2.7 mm, 2.8 mm, 2.9 mm, 3.0 mm, 3.1 mm, 3.2 mm, 3.3 mm, 3.4 mm, 3.5 mm, 3.6 mm, 3.7 mm or 3.8 mm. Particular thickness for the first and second glass layers is 2.1 mm.

[0035] The bonding layer 4 has the primary function of bonding the major faces of adjacent layers to each other. The material selected is typically selected from plastics, for automotive use; the most used bonding layer is polyvinyl butyral (PVB). In addition to polyvinyl butyral, ethylene vinyl acetate (EVA), thermoplastic polyurethane (TPU), polyolefin elastomers (PoE), optical adhesive resins (OCR), optically clear adhesive (OCA), liquid optically clear adhesives (LOCA) and any combination thereof may be used. In an embodiment, the bonding layer are also designed to provide solar and / or optical properties, to the glazing, such as UV protection, IR reflection, dampen sound and / or with tinted colors.

[0036] LOCA is the acronym for Liquid Optically Clear Adhesive and refers to an adhesive material suitable for bonding substrates in contact with it. LOCAs have high optical performance measured in terms of light transmission and low haze. Before bonding, LOCA is initially in a liquid state which allows it to flow and adapt to different shapes having variablethicknesses. Then, to become rigid LOCAs usually undergo a chemical / physical process (curing reaction) that polymerizes the liquid into a rubber-like texture. When needed, LOCAs properties can be modified by using additives and / or stabilizers. In the context of this disclosure, when a LOCA is mentioned, it refers to its rigid configuration as a rubber and / or thermoset material unless mentioned otherwise.

[0037] In an embodiment, the thickness of the bonding layer 4 ranges from 0.3 mm to 2.0 mm, particularly from 0.5 mm to 1.5 mm. In another embodiment, the bonding layer 4 has a thickness of, of about of at most or at most about 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm, 1.1 mm, 1.2 mm, 1.3 mm 1.4 mm and 1.5 mm. Particular thicknesses for the bonding layer 4 are for instance 0.38 mm, 0.631 mm, 0.76 mm and 0.81 mm.

[0038] In the context of this disclosure, a reversible metal electrodeposition cell should be understood as a cell that responds to external stimuli by changing optical, electrical and / or mechanical properties, thus providing dynamic control over light transmission, having at least two states, a darkest state and a clearest state.

[0039] In a RME cell, an electrolyte containing metal ions is disposed between a pair of electrodes on which atoms of the same metal reside. In response to a voltage applied to the electrodes, metal dissolves from one electrode and deposits on the other. By reversing the polarity of the voltage, the direction in which the metal migration occurs is reversed. RME cells are bistable systems having a clearest state and a darkest state. An applied voltage is used to generate the transition between those states, the transition might occur from the darkest to the clearest state or vice versa. In an embodiment the glazing in the glazing system of the disclosure has a total visible light transmission (VLT) in the darkest state ranging from 0.005% to 2% and a VLT in the clearest state is greater than or equal to 2%; preferably the VLT in the clearest state ranges from 2 to 85%; more preferably having a VLT in the darkest state ranging from 0.01 % to 2% and a VLT in the clearest state ranging from 2 to 78%, and even more preferably having a VLT in the clearest state ranging from 2 to 38%.

[0040] VLT is calculated using a specialized measurement tool. A light source is placed on one side of the glazing and a photodetector on the other side. The amount of visible light passing through is measured. The value is typically expressed as a percentage. The higherthe number the more visible light is able to pass through. Various instruments are sold that may be used to measure VLT provided that they conform to the standard ISO 9050 (2003). In the context of this disclosure, the total solar transmittance (TTS) is measured according to standard ISO 13837 (2021).

[0041] In an embodiment of the disclosure, the RME cell is arranged between the first glass layer and the second glass layer and being in contact with the at least one bonding layer. The RME cell can also be embedded within the bonding layer.

[0042] In another embodiment, the glazing system provides high thermal control. Particularly, the glazing in the glazing system has a TTS in the darkest state less or equal than 16% and a TTS in the clearest state ranging from 16 to 70%; more preferably a TTS in the clearest state ranging from 16 to 65%; even more preferably a TTS in the clearest state ranging from 16 to 44%. In the context of this disclosure, the total solar transmittance (TTS) is measured according to standard ISO 13837 (2021).

[0043] In the context of this disclosure, the control unit 10 is configured to apply an electrical field to the system, particularly the control unit 10 provides a current and / or voltage allowing the reversible metal electrodeposition cell switch from the darkest to the clearest state of vice versa.

[0044] In yet another embodiment, the control unit is configured to provide an electrical field to the glazing depending on the incident radiation e.g. IR, providing a dynamic thermal control. In the context of this disclosure, dynamic thermal control should be understood as the ability to change the TTS of the system as the incident radiation changes, for instance visible light, on the command of the user or the car itself when adapted with proper sensors and computing. In a preferred embodiment of the disclosure, the glazing system provides a dynamic thermal control by changing the TTS of the glazing. In yet another embodiment the TTS and the VLT of the glazing follow the same behavior, i.e. if one of them increases, the other one too and vice versa.

[0045] In an additional embodiment, the voltage applied to the glazing system ranges between 1 to 3 V.

[0046] FIG. 1 B depicts another embodiment of the disclosure having the same configuration depicted in FIG. 1A but further including an obscuration 6.

[0047] Obscurations are commonly used on glazing to hide the mounting adhesive and other features and may be a black enamel frit printed or an insert made of a painted or an opaque plastic material. When included the obscuration is arranged on surface two of the first glass layer, and / or surface three of the second glass layer and / or surface four of the second glass layer. Obscurations can be printed on top of other additional coatings, such as the solar control coatings. The obscuration needs to be opaque in the sense of difficulty to see through rather than blocking all light. The typical obscuration light transmission is less than 5%, preferably less than 3% and more preferably equal to 0%.

[0048] The glass layers may have additional coatings applied on them by Magnetron Sputtered Vacuum Deposition (MSVD) as well as other methods known in the art, such as pyrolytic, spray, chemical vapor deposition (CVD), dip, sol-gel, etc. These additional coating or coatings include but are not limited to solar control, anti-reflective, low emissivity (Low-E), anti-fingerprint, color control coating and any combination thereof. In an embodiment, these coatings are disposed in the inner mayor surface of the first glass layer and / or the outer major surface of the second glass layer. Usually, the coatings applied in the inner major surface of the first glass layer are solar control coatings.

[0049] FIG. 2A depicts another embodiment of the disclosure having the same configuration depicted in FIG. 1A but further including a solar control coating 7 on the inner major surface of the fist glass layer 102 and an additional coating 8; such as a Low-E coating on the outer major surface 104 of the second glass layer.

[0050] In the context of this disclosure, solar control coatings limit the quantity of solar energy entering the vehicle passenger compartment. Such coatings are known in the state of the art, and typically comprised a at least one silver inclusive layer. In the context of this disclosure, the RME cell provides thermal control in some extend, therefore the inclusion of solar control coatings, such as Ag, might be redundant or even unnecessary depending on the final product features.

[0051] Low-E coating adds thermal insulation properties to a glazing by reducing its emissivity (the heat energy in mid-infrared range), especially when it is used in conjunction with a solar-control coating, which blocks a significant portion of direct solar energy in the near-IR spectral region. This combination has proved especially useful in panoramic glass roofs.

[0052] Anti-reflective coatings have seen increased use in automotive glazing applications considering that the interior reflection may be distracting with all of the light-emitting gadgets mounted in the instrument panel and other parts of the cabin.

[0053] An anti-fingerprint coating is desirable since fingerprints on the glass are more noticeable with the decoupled light backlighting them.

[0054] In preferred embodiments, coatings that combine two or more of the mentioned functionalities are included in the disclosure.

[0055] In different embodiments, the glazing of the glazing system may include additional interlayers, such interlayers are designed to provide solar and / or optical properties to the glazing, such as UV protection, IR reflection, dampen sound and / or with tinted colors. In the context of this disclosure, additional interlayers are arranged between the first and second glass layers of the laminate, but do not necessarily act as a bonding interlayer. In an embodiment, when UV protection and IR reflection interlayers are included, they are selected from different plastic materials such as TPU based functional film, TAC, XI R and PET, such as UCSF, reflective films such as WCFs, among other materials. In an embodiment, when dampen sound interlayers are included, they are comprised whole or in part of a layer of polymer that is softer and more flexible than that normally used. Additional embodiments of the present disclosure include a plastic interlayer with tinted colors, such as grey or brown plastic interlayers, such as PVB, to control the color of the full glazing. Additional embodiments could have both functions, sound control and tinting. An example of this configuration is depicted in FIG. 2B which shows a glazing system 100 as depicted in FIG. 1A further including an additional interlayer 4.1. '

[0056] The thickness of the additional interlayer 4.1 ranges from 0.3 mm to 2.0 mm, particularly from 0.5 mm to 1.5 mm. In another embodiment, the additional interlayer 4.1 hasa thickness of, of about of at most or at most about 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm, 1.1 mm, 1.2 mm, 1.3 mm 1.4 mm and 1.5 mm. In another embodiment, when a dampen sound bonding layer is included, the bonding layer thickness ranges from 0.51 mm to 0.83 mm, particular thicknesses are for instance 0,51 mm, 0.76 mm and 0.81 mm.

[0057] Additional interlayers might also be arranged between the interface of adjacent glass and bonding layer and / or of adjacent RME cell and bonding layer.

[0058] The glazing system of the disclosure includes a reversible metal electrodeposition (RME) cell as known in the state of the art, examples can be found for instance in US 5923456A, US20230323553 and US2022128878 which are incorporated here by reference. As an example, a general configuration and functioning of the cell 5 is provided in FIG. 3 which includes a first substrate 501 , a first electrode 502, an electrolyte 503, a second electrode 504, and a second substrate 505. As mentioned previously, these cells operate through the reversible electrochemical deposition of a metal on and off an electrode forming the metal layer 506 as depicted. The electrolyte 503 is placed between the electrodes and includes solubilized metal ions that can be deposited upon application of a direct current DC to form the metal layer 506. Suitable materials for each layer as well as other functioning particularities of these cells are known in the state of the art.

[0059] In a preferred embodiment, the first and second substrates 501 , 505 are transparent and flexible layers. In yet another embodiment, the first and second substrates are selected from different materials such as, but not limited to polyethylene terephthalate (PET) and polyimide (PI). In the context of this disclosure, a transparent substrate layer has a total visible light transmission (VLT) of at least 80%, preferably from 80 to 90% and more preferably of at least 86%.

[0060] In another embodiment, the first and second electrodes 502, 504 are selected from the group comprising indium tin oxide (ITO), fluorine doped tin oxide (FTO), carbon nanotubes, silver nanowires and a combination thereof.

[0061] In another embodiment, the electrolyte 503 contains metal ions such as tungsten, copper and / or silver that can be deposited upon application of an electrical field generating a metal layer.

[0062] In the context of this disclosure, color is valuable appearance parameter for the glazing. Color can be described mathematically. Cl ELAB is one of the many color spaces to describe color shifts, one of its advantages is that those shifts on the CIELAB diagram are perceived proportionally by the human eye. The CIELAB L*, a*, b* color space mathematically describes all perceivable colors in three dimensions: L* for perceptual lightness, a* for green- red, and b* for blue-yellow. See Hunter Lab, Applications Note, "Insight on Color," Vol. 8, No. 7 (2008). In the CIELAB color space, the L* axis runs from top to bottom. The maximum L* value is 100, which indicates a perfect reflecting diffuser (i.e., the lightest white). The minimum L* value is 0, which indicates a perfect absorber (i.e., the darkest black). Positive a* is red. Negative a* is green. Positive b* is yellow. Negative b* is blue. CIELAB a* or b* values equal to 0 indicate no red-green or blue-yellow color appearance, in which case the article would appear pure white. In contrast, a* or b* values that deviate far from 0 indicate that light is non-uniformly absorbed or reflected. As a* or b* values deviate from 0, the color may no longer appear as bright white. One of the most important attributes of the CIELAB model is device independence, which means that the colors are defined independent of their nature of creation or the device they are displayed on.

[0063] The L*, a*, and b* values of the CIELAB color scale can be obtained using any CIELAB color measurement instrument and are calculated from known formulas. See Hunter Lab, Applications Note, "Insight on Color," Vol. 8, No. 7 (2008).

[0064] Thus, the uniqueness of the CIELAB space is in its perceived uniformity. A change in the numerical difference between two color coordinates is proportionate difference in color perceived by the eye.

[0065] In an embodiment, the glazing of the system of the disclosure is color neutral having a value of a* ranging from -15.0; 15.0 to and a value of b* ranging from -15.0 to 15.0, more preferably a* ranging from -8.0; 8.0 to and b* ranging from -8.0 to 8.0 when measured in the CIELAB color scale.

[0066] The glazing of the system of the disclosure may also be curved. A “curved glazing” shall be understood as a glazing where the layer(s) are curved (as a result of a bendingprocess, such as a cold and / or hot bending process). The terms “curved” and “bent” are understood as synonyms.

[0067] The term hot bending when applied to glass layer should be understood as a process involving heating the glass layer to at least the lower end of the glass transition range where plastic deformation can take place. The exact temperature and heating time varies depending on the glass composition and on the complexity of the shape to be achieved. The softened glass is then bent to the desired shape using conventional techniques already described (gravity, press or a combination thereof). Once the glass has been shaped, it undergoes a controlled cooling process until room temperature, to ensure the required stress levels and avoid undesired optical distortions.

[0068] Glass can be bent without heating. Very thin chemically tempered glass, in which an ion exchange process is used to strengthen the glass is sometimes used in a non-thermal bending process known as cold bending. Cold bending is a relatively new technology. As the name suggests, the glass is bent, while cold to its final shape, without the use of heat. However, as the glass only undergoes elastic deformation, at any point on the bent area of the glass one side, i.e., major surface, of the glass will have a substantially higher level of stress than on the opposite side of the glass. If annealed glass is used, one side will be in compression and the other in tension.

[0069] In the context of the disclosure, to evaluate the complexity associated with the shape of a curved glass layer of the glazing, the inverse process of the bending process is considered. According to said inverse process, the glass layer is bent from target shape to flat. Thus, the inverse process is a flattening process. A finite element model can be implemented for the flattening process and solved by a structural non-linear solver such as Abaqus. The Maximal Compressive Strain (MCS) is defined herein as the maximal area strain that is generated on the mid-surface of the glass layer during the flattening process, that corresponds to the opposite (that is with a minus sign) of the minimal area strain for the bending process. For a point on the mid-surface, area strain corresponds to the sum of maximal and minimal in-plane principal components of the strain tensor for the same point. The finite element model is based on elastic properties of glass. Mid-surface is formallydefined as the imaginary surface that is equidistant from outer and inner surfaces of the glass layer.

[0070] In an embodiment, evaluation of the MCS value for an actual glass layer of the glazing can be made according to a method comprising the following steps:

[0071] (1) Scanning the glass layer surface to obtain a computer file including a cloud of points or a mesh that represents accurately the glass layer surface and size. Any surface of the glass layer may be scanned (i.e. any major surface of the glass layer), preferably a convex major surface of the glass layer, such as the surface intended to be an outer surface of the glazing when the glazing is in an operating position.

[0072] (2) Building a continuous surface that interpolates the cloud of points or mesh, for example using a CAD software.

[0073] (3) Building a finite element mesh from the obtained surface, the finite element mesh comprising nodes and shell elements, for example triangular and / or quadrilateral shell elements, such as S3 and / or S4 elements in Abaqus. Preferably, the finite element mesh is fine enough for the MCS value to be unchanged if the mesh is further refined.

[0074] (4) Associating to the shell elements the elastic properties of glass. In an embodiment, the following properties are used: E-modulus = 70 GPa and Poisson ratio = 0.22.

[0075] (5) Rotating the finite element mesh in a way that it be essentially horizontal in the initial state of the analysis.

[0076] (6) Defining a static non-linear analysis.

[0077] (7) Creating boundary conditions for z-coordinates that will displace each individual node from its original z-coordinate to z=0, wherein z-direction is perpendicular to the horizontal plane. No boundary conditions on x- and y-coordinates are defined, so the shape can unfold in a natural manner during the flattening process, without generating artificial strains. It is allowed to fix x- and y-coordinates for one single node in the center of the finite element mesh to constrain rigid body motion and help convergence.

[0078] (8) Running the static non-linear analysis.

[0079] (9) Building a field output that is defined as the sum of maximal and minimal in-plane principal strains. MCS value is the maximal value of this field output found in the mid-surface of the glass layer.

[0080] In an embodiment, at least one glass layer of the glazing has a Maximal Compressive Strain (MCS) greater than 7.

[0081] In an embodiment, every glass layer of the glazing has a Maximal Compressive Strain (MCS) greater than 7. In an embodiment, the glazing has two glass layers and both glass layers have a Maximal Compressive Strain (MCS) greater than 7.

[0082] In an embodiment of the disclosure, the glazing including the RME cell is an automotive roof, a windshield and / or a sidelite window. In yet another embodiment, the glazing as described is included in a vehicle.

[0083] In an embodiment, a projector system is included in the vehicle to project static or dynamic items in the glazing which acts as a projection screen. Particularly, the glazing of the glazing system of the disclosure allows the projection of items on the inner surface of the glazing, when installed in a vehicle, without the projection being visible from the outside, when the glazing is in the darkest state.Examples.

[0084] Example 1 .

[0085] This example relates to a vehicle sidelite laminate including the following configuration: The glazing is a laminated sidelite, with a length of 550 mm and a width of 450 mm. The first glass layer 201 and second glass layer are comprised of a clear soda-lime glass composition with a thickness of 2.1 mm. A black obscuration 6 is printed on surface two 102 of the first glass layer 201 and on surface four 104 of the second glass layer 202. Two PVB layers having each layer a thickness of 0.76 mm are used as bonding layers 4. Additionally, a reversible metal electrodeposition RME cell is embedded within the PVB having a thickness of 0.38 mm.

[0086] The glazing system is connected to a control unit 10 that that switches between the lightest and darkest states using a power supply of 1 V. The VLT of the glazing when measured in the clearest state is of 81.3%, while the VLT when measured in the darkest stateis of 0.1 %. Additionally, The TTS of the glazing when measured in the clearest state is of 65.5%, and the TTS when measured in the darkest state is of 14.7%. Additionally, a* and b* when measured in the clearest state are respectively -3.1 and 1.3 and a* and b* when measured in the darkest state are respectively 0 and 0.

[0087] Example 2.

[0088] Example two is similar to example one, further including a solar control coating (e.g. Ag) deposited on surface two of the first glass layer 201.

[0089] The VLT of the glazing when measured in the clearest state is of 62.6%, while the VLT when measured in the darkest state is of at least 0.1 %. Additionally, The TTS of the glazing when measured in the clearest state is of 35.0%, and the TTS when measured in the darkest state is of 13.8%. Additionally, a* and b* when measured in the clearest state are respectively -3.1 and 4.9 and a* and b* when measured in the darkest state are respectively 0 and 0.

[0090] Example 3

[0091] Example three is similar to example two, further including a Low-E coating deposited on surface four 104 of the second glass layer 202.

[0092] The VLT of the glazing when measured in the clearest state is of 61.2%, while the VLT when measured in the darkest state is of 0.1 %. Additionally, The TTS of the glazing when measured in the clearest state is of 31 .6%, and the TTS when measured in the darkest state is of 9.1 %. Additionally, a* and b* when measured in the clearest state are respectively -3.3 and 5.1 and a* and b* when measured in the darkest state are respectively 0 and 0.1.

[0093] Example 4

[0094] Example four is similar to example one further including an acoustic PVB layer having a thickness of 0.51 mm placed between the first glass layer 2.1 and the PVB bonding layer 4.

[0095] Example 5.

[0096] Example five is similar to example one except for the bonding layer 4. Instead of PVB, a silicon-based LOCA having a thickness of 1.5 mm is used as bonding layer.

[0097] Example 6

[0098] Example six relates to a vehicle sidelite laminate including the following configuration:

[0099] - a first clear soda lime glass layer 201 having a thickness of 2.1 mm;

[0100] - a PVB interlayer having a thickness of 0.38 mm;

[0101] - a UCSF interlayer having a thickness of 0.05 mm;

[0102] - a PVB interlayer having a thickness of 0.38 mm;

[0103] - a reversible metal electrodeposition RME cell having a thickness of 0.38 mm;

[0104] -a PVB interlayer having a thickness of 0.76 mm; and

[0105] -a second clear soda lime glass layer 201 having a thickness of 2.1 mm.

[0106] The glazing system is also connected to a control unit 10 that that switches between the lightest and darkest states using a power supply of 1 V. The VLT of the glazing when measured in the clearest state is of 79.1%, while the VLT when measured in the darkest state is of at least 0.1 %. Additionally, The TTS of the glazing when measured in the clearest state is of 56.1 %, and the TTS when measured in the darkest state is of 14.1 %. Additionally, a* and b* when measured in the clearest state are respectively -3.1 and 4.9 and a* and b* when measured in the darkest state are respectively 0 and 0.

Claims

CLAIMSWhat is claimed is:

1. An automotive glazing system comprising; a glazing and a control unit, wherein the glazing comprises, a first glass layer having an outer major surface, surface one, and an inner major surface, surface two, wherein the outer major surface is opposite to the inner major surface; a second glass layer having an inner major surface, surface three, and an outer major surface, surface four, wherein the outer major surface is opposite to the inner major surface; at least one bonding layer arranged between the inner major surface of the first glass layer and the inner major surface of the second glass layer; and a reversible metal electrodeposition cell arranged between the first glass layer and the second glass layer and being in contact with the at least one bonding layer; wherein the control unit is configured to apply an electrical field to the system; and wherein the reversible metal electrodeposition cell has electrically controllable optical properties.

2. The automotive glazing system of claim 1 , wherein the glazing has a total visible light transmission (VLT) in the darkest state ranging from 0.005% to 2% and a VLT in the clearest state is greater than or equal to 2%.

3. The automotive glazing system of claim 1 , wherein the glazing has a TTS in the darkest state less or equal than 16% and a TTS in the clearest state ranging from 16 to 70%.

4. The automotive glazing system of any one of claims 1 to 3, wherein the glazing has a value of a* ranging from -15.0 to 15.0 and b* ranging from -15.0 to 15.0 when measured in the Cl ELAB color scale.

5. The automotive glazing system of any one of claims 1 to 4, wherein the first glass layer and the second glass layer are selected from the group comprising soda lime, aluminosilicate, lithium aluminosilicate, borosilicate and glass ceramics.

6. The automotive glazing system of any one of claims 1 to 5, wherein the at least one bonding layer is selected from the group comprising polyvinyl butyral (PVB), ethylene vinyl acetate (EVA), thermoplastic polyurethane (TPU), polyolefin elastomers (PoE), optical adhesive resins (OCR), optically clear adhesive (OCA) liquid optical clear adhesive resins (LOCA) and a combination thereof.

7. The automotive glazing system of any one of claims 1 to 6, further comprising a coating selected from the group comprising a solar control coating, an anti-reflective coating, a Low-E coating, an anti-fingerprint coating, a color control coating and combinations thereof; and being disposed in the inner mayor surface of the first glass layer and / or the outer major surface of the second glass layer.

8. The automotive glazing system of any one of claims 1 to 7, wherein the at least one bonding layer is dampen sound layer and / or tinted color interlayer.

9. The automotive glazing system of any one of claims 1 to 8, further including additional interlayers such as dampen sound interlayers and tinted color interlayers.

10. The automotive glazing system of any one of claims 1 to 9, wherein the glazing is curved.11 . The automotive glazing system of any one of claims 1 to 10, wherein at least one glass layer of the glazing has a Maximal Compressive Strain (MCS) greater than 7.

12. The automotive glazing system of any one of claims 1 to 11 , wherein the reversible metal electrodeposition cell has a multilayer layer structure comprising: a first substrate; a first electrode layer; an electrolyte layer;a second electrode layer; and a second substrate.

13. The automotive glazing system of claim 12, wherein the first and second substrates are transparent and flexible layers.

14. An automotive roof, windshield or sidelite window comprising a glazing system according to any of the preceding claims.

15. A vehicle comprising an automotive glazing system according to any of the preceding claims.

16. The vehicle of claim 15 further including a projector system wherein the glazing acts as a projection screen.

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