DE202024101226U1 - Glazing with p-polarized head-up display coating and superior color properties - Google Patents

Abstract

A glazing (100, 200, 300) for a vehicle optimized for the reflection of p-polarized light, comprising:
at least one glass layer (201, 202), the glass layer having two surfaces, a first surface (8) adjacent to the interior of the vehicle and a second surface opposite the first surface; and a transparent, p-polarized light-reflecting coating (3) applied to at least a portion of the first surface (8) of said glass layer, the coating (3), counting from the glass surface, comprising:
at least one first dielectric layer (D1) having a refractive index greater than 1.6 and less than 1.8,
at least one second dielectric layer (D2) having a refractive index of less than or equal to 1.6,
at least a third dielectric layer (D3) having a refractive index greater than 1.6 and less than 1.8,
at least a fourth dielectric layer (D4) having a refractive index greater than or equal to 1.8,
at least a fifth dielectric layer (D5) having a refractive index of greater than 1.6 and less than 1.8, and
at least a sixth dielectric layer (D6) with a refractive index of less than or equal to 1.6.

Description

SCOPE OF INVENTION

The invention relates to the field of automotive glazing and in particular to automotive windshields with a coating that reflects p-polarized light particularly well and with head-up display capability.

BACKGROUND OF THE INVENTION

Head-up display (HUD) is a technology that displays information in such a way that the driver of a vehicle can keep an eye on the values of variables that are normally displayed on the instrument panel without having to look down. The driver can still see the surroundings in the direction of travel without having to look at the instrument panel to see speed, rpm and other values. The graphic acts like a virtual image that seems to float in space in front of the vehicle.

Modern HUD systems typically project an image onto a laminated glass panel, which consists of a layer of plastic sandwiched between and bonded to two layers of glass.

Each glass layer (2) of the laminate has two surfaces and an edge. The first glass layer (201) has a surface that forms part of the exterior of the vehicle and faces outward. This exterior surface is referred to as surface one (101). The opposite surface of glass layer one is surface two (102).

The second glass layer (202) of a laminate has a surface that immediately adjoins and forms part of the interior of the vehicle. This interior surface is referred to as surface four (104). The opposite side of glass layer two is surface three (103). Surfaces two (102) and three (103) are bonded together by the plastic bonding layer (4), which is also referred to as the intermediate layer.

A shade can also be applied to the glass. Shades are usually made of black enamel frit printed on either surface two (102), surface four (104), or both surfaces. The area not covered by a shade is the clear viewing area.

The laminate may have a coating on one or more of the surfaces. The laminate may also include a film (12) laminated between at least two plastic bonding layers (4), also referred to as an intermediate layer.

There are some challenges involved in producing windshields that are optimized for HUDs and display sharp, bright images.

Most of the existing HUD systems use the first surface seen from the vehicle interior (8), i.e. the surface (104) of a laminated windshield, to display the projected image. However, ordinary glass reflects less than 10% of the incident light. As a result, the image can be difficult to see in bright sunlight. Ghosting due to secondary reflections from the first surface (101) of the glazing and any coatings or films that may be present can also be a problem.

Illustration 6A shows a cross-section of a common laminated glass windshield and the path of the projected image. The HUD projector (24), mounted in the instrument panel of the vehicle, projects an image (30) onto surface four (104) of the inner glass layer (202) adjacent to the vehicle interior. The light enters the windshield at point one (51). At point one, some of the light is reflected due to the difference between the refractive indices of air and glass. This reflected image (31) is perceived by the observer (40) as the primary image. The transmitted portion of the beam is refracted upon entering the glass at point one (51). The beam strikes the first surface (101) of the outer glass layer (201) at point two (52). Again, some of the light is reflected at the air-glass interface. From point two (52), the reflected light travels through the glass and exits the glazing at point three (53), where it is perceived by the viewer as a secondary image (32), also called a "ghost image." The secondary image (32) is fainter than the primary image (31), but can be visible in the booth and outdoors under the right lighting conditions. The distance between the primary (31) and secondary (32) images, as well as the intensity ratio between them, also have an impact. When the two images overlap, the secondary image amplifies the brightness of the primary image, enhancing it. If the distance is too great, the impression of a double image is created, which is undesirable.

There are a number of methods that have been developed to minimize secondary images.

The most common solution to date is the use of a so-called “wedge” intermediate layer ( EP1880243A2 ; WO2009/071135A1 ). The plastic bonding layer (4) normally used in ordinary windshields has a uniform thickness, but the wedge interlayer does not. The thickness varies to slightly tilt the two layers of glass towards each other so that they are no longer parallel to each other, at least in the area where the image is projected. In this way, the position of the reflected secondary image can be moved closer to the primary image so that they overlap.

Although this method is somewhat effective, it also has a number of disadvantages. Since reflection is only corrected in the vertical direction, the HUD image must be centered in the driver's field of view. Likewise, the projector must also be centered. Therefore, only a small part of the field of view can be used.

Another issue is the thickness of the interlayer. A certain minimum interlayer thickness is required to meet penetration and chip resistance requirements. Therefore, the wedge interlayer, which starts at this minimum thickness, is usually much thicker than the standard interlayer. This greater thickness makes lamination more difficult because it can lead to wrinkling and air entrapment. Wedge interlayers are also much more expensive than standard interlayers and add weight.

Another approach is to incorporate a HUD display film into the laminate. Laminates with HUD display films are typically made by inserting the film between two layers of plastic.

Different types of HUD display films have been developed.

One type of film is optimized to have a higher reflectance in the visible spectrum than ordinary glass, thus producing a higher image at the same level of illumination. At the same time, by reflecting a higher percentage of the incident light, less light is transmitted to surface one and the brightness of the secondary image is reduced. Because the film is closer to the image reflected from the glass surface, it is less likely to produce a distracting secondary image. This type of reflective HUD film sometimes has an anti-reflective coating applied to the fourth surface of a laminate, but it may also require a wedge-shaped plastic bonding layer.

Another type of HUD film is holographic film. Holographic films are also laminated between two plastic layers. The holographic patterns recorded on the film are illuminated and displayed using LASER light.

A third type of HUD film uses a projector that uses a primarily p-polarized (p-pol) light source.

We can describe the type of polarization of light using the plane of incidence. This is the plane that is spanned between the direction of propagation of the incident light and the normal vector of the glass surface. The angle between the two planes is the angle of incidence. Light that is polarized parallel to the spanned plane is called p-polarized. Light that is polarized perpendicular to this plane is called s-polarized.

An interesting phenomenon that we can take advantage of is the fact that p-polarized light does not produce reflection when the angle of incidence is at or near the Brewster angle. The Brewster angle is the angle at which polarized light passes perfectly through a transparent dielectric surface without being reflected. Another advantage of p-polarized light is that it is also visible through polarized sunglasses.

If we have a HUD projector that emits p-polarized light and we mount the projector so that the beam hits at the Brewster angle, the reflections at the two air interfaces, point one (51) and two (52), are eliminated. As a result, no image is formed. To form an image, the glass must be covered with a p-polarized reflective film.

A film optimized for reflecting p-polarized light is laminated into the windshield and used with a projector that emits primarily p-polarized light. By projecting the light beam at an appropriate angle, the reflections from surface one and surface four are largely eliminated, as are any secondary images. Another advantage of this approach is that a wedge interlayer and anti-reflection coating are not required.

The cross-section of a laminate with a p-polarized HUD film (14) is shown in 6B The p-polarized projector (24) projects an image (30). The light enters the surface four (104, 8) at point one (51) where there is no reflection. The light penetrates the second glass layer (202) and the first plastic bonding layer (4) and hits the p-polarized HUD film (14), where it is reflected by the film (14) at point five (55). The reflected image leaves the glazing at point four (54), where it is perceived as the primary image (31). Due to the projection angle and the p-polarization of the light source, secondary images are largely eliminated.

All three types of HUD films have a number of problems that limit widespread use. First, they require a second layer of the plastic interlayer, which increases both cost and weight. Also, the films themselves tend to be expensive. The edges of the film are difficult to hide. Additionally, lamination can be difficult due to the difference in thickness at the edges of the film. Wrinkling, adhesion and durability can also be an issue. Perhaps the biggest challenge is that the visible light transmittance for the windshield must be at least 70% according to regulations.

In another similar method, instead of laminating a p-polarized reflective HUD film, a coating optimized for the reflection of p-polarized light is applied to surface four, as shown in Figure 3B ( CN113031276A ) is shown.

In 3B is shown a laminate having a p-polarized reflective HUD coating (3) on the fourth surface (104,8). The projector (24) projects an image (30) using p-polarized light. The image (30) is reflected from the coating (3) at point one (51), creating the primary image (31). The transmitted portion of the image exits the glazing at point two (52), where there is no reflection. For a windshield having a HUD film (22) reflecting p-polarized light and a projector emitting primarily p-polarized light, there is only a single primary image. The image is also not dependent on the viewing angle. This also eliminates the additional cost and disadvantages of the second plastic bonding layer required with a laminate film and the wedge interlayer required with some methods.

In a variation of this method, coatings developed for other purposes, such as solar control, have been modified to increase reflectivity for p-polarized light.

An increasing percentage of vehicle windshields are manufactured with solar control coatings on the second or third surface. Solar control coatings, usually silver-based, are designed to be anti-reflective in the visible light range and highly reflective in the infrared range. A more recent trend is to develop these coatings with an increased p-polarized reflectance and to use a p-polarized projected image ( US$10,437,054 ; DE102014220189A1 ; WO2019046157A1 ). However, it is challenging to achieve sufficient p-polarized reflection in the visible region required for a high contrast ratio between the primary and secondary reflection of surfaces one and four.

Another problem with many state-of-the-art coatings is that they use metallic and/or conductive oxide layers in addition to the dielectric layers. In our recent application, we demonstrated a p-polarized reflective coating on surface four of a laminate based on an ultra-thin metal (or alloy) layer between two dielectric layers. One of the disadvantages of this type of coating is that it attenuates high frequency (RF) radio waves, thus affecting connectivity with 5G or other high frequency waves. Even at nanometer-scale thicknesses, these conductive layers are highly reflective in the radio frequency (RF) range, causing electromagnetic interference (EMI). The range of many RF devices is reduced or they stop working altogether when used in a vehicle that has even just the windshield with a conductive coating. This problem has been recognized and such windshields are not allowed in some countries.

The state-of-the-art p-polarized reflective coatings all have two disadvantages. They tend to have insufficient p-polarization reflection at high angles of incidence (AOI), such as at 65 degrees (Rp(65)) in the red, green and blue (RGB) spectral ranges. The other disadvantage is that they have a strongly wavelength-dependent Rp(65) curve, which significantly unbalances the RGB p-polarization reflection. This also affects the color neutrality of the reflection and usually also the transmission. The state-of-the-art coatings are based on layer sequences containing at least one dielectric layer with a low refractive index (L) followed by a combination sequence of dielectric layers with a high refractive index (H), where the low refractive index layer has a refractive index of not more than 1.6 and the high refractive index layer has a refractive index of not less than 1.8.

It is desirable that the perceived contrast between the primary and each of the secondary images is greater than 50:1. It is also desirable that the reflectivity for p-polarized light at the selected RGB wavelengths (eg 469, 532 and 629 nm) and for general light with mixed polarization (normalized to eye sensitivity) is at least 20% and not more than 30%, respectively. It is mandatory that at least 70% of the general visible light in the driver's field of vision is transmitted by the windshield.

It would be desirable to have a reflective p-polarization coating that meets the above requirements, eliminates “ghosting” and is EMI compatible.

BRIEF SUMMARY OF THE INVENTION

The invention relates to a glazing with a p-polarization reflective coating applied to the surface of the glazing facing the vehicle interior. The coating is optimized to achieve high R _p (65) values at 469, 532 and 629 nm while having an overall mixed polarization reflectance of less than 30% and a visible light transmission (T _vis ) of at least 70%.

The prior art p-polarization reflective coatings use high and low refractive index dielectric layers to alter the spectral properties of the coating. The inventor's simulated and experimental results have shown that adding dielectric materials with a third, intermediate (M) range of refractive index, which lies between the high and low refractive index ranges, can significantly improve both reflected and transmitted color neutrality and increase the reflection of p-polarized light in the visible spectrum. In addition, no conductive layers are required, so there are no problems with EMI.

In its simplest form, the coating applied to the inner surface of the glazing consists of six dielectric layers whose refractive index falls into three ranges, namely low, medium and high. The layers are applied in the order of refractive index, starting from the glass surface, from medium, low, medium, high, medium, low.

Additional dielectric layers can be added to further tune the spectral properties.

A HUD image consisting essentially of p-polarized light is projected onto at least a portion of the coated surface.

• • Die innenliegende Glasoberfläche (8), wird zur Oberfläche, die das Primärbild reflektiert.
• • Sekundäre „Geisterbilder“ werden eliminiert.
• • Das HUD-System wird weniger empfindlich gegenüber dem Einfallswinkel.
• • Ist geeignet für die gesamte Oberfläche der Verglasung.
• • Keine elektromagnetische Interferenz (EMI); kompatibel mit 5G; erfüllt die Vorschriften in Ländern wie Singapur.
• • Eine keilförmige Zwischenschicht ist nicht mehr erforderlich, so dass keine Probleme mit der Laminierung auftreten.
• • Eine holografische HUD-Folie ist nicht mehr erforderlich, daher gibt es keine Probleme mit der Laminierung.
• • Geringere Kosten im Vergleich zur Verwendung von holografischen Keil- oder HUD-Filmen.
• • Das Bild kann mit polarisierten Brillen betrachtet werden.
• • Ermöglicht Augmented Reality.

Advantages of the invention:

• • The inner glass surface (8) becomes the surface that reflects the primary image.
• • Secondary “ghost images” are eliminated.
• • The HUD system becomes less sensitive to the angle of incidence.
• • Suitable for the entire surface of the glazing.
• • No electromagnetic interference (EMI); compatible with 5G; meets regulations in countries like Singapore.
• • A wedge-shaped intermediate layer is no longer required, so there are no problems with lamination.
• • A holographic HUD film is no longer required, so there are no problems with lamination.
• • Lower cost compared to using holographic wedge or HUD films.
• • The image can be viewed with polarized glasses.
• • Enables augmented reality.

BRIEF DESCRIPTION OF THE DIFFERENT VIEWS OF THE DRAWINGS

• 1A shows a cross-section of the configuration 100 of the invention, a monolithic tempered glazing with a glass layer (2) (202) and the p-polarization HUD coating (3) on the inner surface (8).
• 1B shows a cross-section of the configuration 200 of the invention. The glazing consists of a plastic bonding layer (4) between two glass layers (2) (201, 202) and the p-polarization coating (3) on the inner surface (8).
• 1C shows a cross-section of configuration 300. It corresponds to configuration 200 with the addition of a solar control coating (20) applied to surface two (102) of the first glass layer (201).
• 2A shows a six-layer coating with six dielectric layers, with refractive indices of the type high (H), medium (M) or low (L).
• 2 B shows a layer sequence with ten dielectric layers, with refractive indices of type high (H), medium (M) or low (L).
• 3A is a table showing the thickness in nanometers (nm) of each of the layers of Examples 1 to 4.
• 3B shows a HUD system with a p-polarization projector and a laminate with a p-polarization reflective coating (3) on the fourth surface (104,8).
• 4A shows the spectral properties of the coating from Example 1.
• 4B shows the spectral properties of the coating from Example 2.
• 5A shows the spectral properties of the coating from Example 3.
• 5B shows the spectral properties of the coating from Example 4.
• 6A shows a conventional HUD system.
• 6B shows a conventional HUD system in which the laminate further comprises a HUD film (14) laminated within the laminate between the two layers of the plastic bonding layer (4).

REFERENCE NUMBERS OF THE DRAWINGS

2

Glass layer

3

p-polarization reflective coating

4

Bonding/adhesive layer (plastic intermediate layer)

8th

Surface of the glazing facing the vehicle interior

14

HUD Movie

20

Sun protection coating.

24

HUD projector

30

Projected image

31

Primary perceived image

32

Secondary image

33

Tertiary image

40

Observer's eye point

51

Point one

52

Point two

53

Point three

54

Point four

55

Point five

101

Outside of glass layer 1 (201), surface number one

102

Inside of glass layer 1 (201), surface number two

103

Outside of glass layer 2 (202), surface number three

104

Inside of glass layer 2 (202), surface number four

201

outer glass layer

202

inner glass layer

100

Cross section of a monolithic single-pane glazing with HUD coating (3) on the second surface (102)

200

Cross-section of a laminated glazing with HUD coating (3) on surface four (104)

300

Cross section of a laminated glazing with HUD coating (3) on the fourth surface (104) and a solar control coating on the second surface (102)

DETAILED DESCRIPTION OF THE INVENTION

The present disclosure can be understood by reference to the detailed descriptions, drawings, examples, and claims of this disclosure. However, the content of this disclosure is not limited to the specific compositions, articles, devices, and methods described herein, but these may, of course, vary unless explicitly stated otherwise. It should also be noted that the terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting.

The structure of the invention is described in terms of the layers comprising the coating and the glazing. The term "layer" is used in this context in its usual sense: a layer of material, typically of a homogeneous substance and one among several.

When layers of very different thickness are shown in the following figures, it is not always possible to show them to scale without losing the clarity of the illustration. Unless otherwise stated, all figures are for illustrative purposes and should not be considered to scale; this should therefore not be understood as a restriction.

The invention can be applied over a wide range of glass pane thicknesses. Typical automobile windshields have glass layers ranging from 1.4 mm to 3.8 mm, but this is not a limitation.

Likewise, the invention can be used in conjunction with numerous glass compositions.

The glass layers can be tempered, heat-strengthened or chemically hardened.

The invention is not limited to laminated glass windshields. The invention can be used on all glazed openings of a vehicle, even those that only require a single layer of glass.

A sequence of layers is called a layer sequence. When describing a layer sequence, we use the convention of numbering the layers in the order in which they are applied to the substrate. Also, if there are two layers, we refer to the one that is closer to the substrate as the "bottom" layer. Thus, the layer applied last is the "top" and the layer applied first is the "bottom". The top of a single layer is the side furthest from the substrate, while the bottom is the side facing the substrate.

The spectral properties of the coated glazing are described using the following standard industry terminology.

T _vis , visible light transmittance, is the integrated transmittance over the visible spectrum, adjusted to the sensitivity of the human eye. T _vis is normally measured at a specific angle, for example T _vis (0). The measurement is made according to the ISO 9050:2003 standard: "Glass in building - Determination of luminous transmittance, direct sunlight transmittance, total solar energy transmittance and ultraviolet transmittance and the corresponding glazing factors".

R _vis , the visible reflectance, is the integrated reflectance over the visible spectrum, adjusted to the sensitivity of the human eye. R _vis is usually measured at a specific angle, for example R _vis (0). The measurement is made according to the ISO 9050:2003 standard: "Glass in building - Determination of luminous transmittance, direct sunlight transmittance, total solar energy transmittance and ultraviolet transmittance and the corresponding glazing factors".

R _p , p-polarized reflectance, is a measure of how much p-polarized light in the visible region of the spectrum is reflected by a glazing.

T _mix is the spectral dependence of the transmittance measured without preferred polarization. It can also be written as T _mix (λ), the transmittance in a specific spectral range (visible, IR, UV) or at a specific wavelength, such as T _mix (625nm) or T _mix (550nm). T _mix is usually measured at a specific angle, for example T _mix (65).

R _mix is the spectral dependence of the reflectance measured without preferred polarization. It can be written as R _mix (λ), the reflectance over a specific spectral range (visible, IR, UV) or at a specific wavelength, such as R _mix (625nm) or R _mix (550nm). R _mix is usually measured at a specific angle, for example R _mix (65).

The CIELAB color coordinates, also known as L*a*b*, are a standard defined by the International Commission on Illumination. It quantifies color as three values: L* for perceived brightness and a* and b* for the four primary colors of human vision: red, green, blue and yellow.

Advantageously, this invention can produce a coating whose CIELAB color coordinates for both transmitted and reflected light are in the range of -0.30 to +0.30, for both a* and b*.

The HUD coating of the invention can be used in a variety of glazing configurations.

In the case of monolithic glazing, i.e. glazing with only one layer of glass (2), the coating is applied to surface two (102). Figure 1A shows a cross-section through an embodiment of the invention comprising a single glass substrate (202) with the p-polarization reflective HUD coating of the invention (3) on the second surface (102). This configuration (100) is suitable for tempered glass.

shows a cross-section through an embodiment of the invention in which the p-polarization reflecting HUD coating is applied to surface four (104) of the second glass layer (202) This configuration (200) would be used for a typical laminated glass pane.

is similar to that of with the addition of a solar control coating (20) applied to surface two (102) of the first glass layer (201), the outer glass layer. This configuration (300) is typical for laminated glass with solar control.

It is well known in the field that the spectral properties of a vacuum-deposited coating depend on the materials used, the layer thicknesses, the deposition conditions and the sequence of the layers. By carefully selecting the layer materials and the deposition parameters, the coating can be designed and optimized for the desired spectral properties.

An important physical property is the refractive index of the material. The spectral properties of the coating can be significantly altered by applying alternating layers of high (H) and low (L) refractive index materials. In this way, the metallic layers of solar control coatings are made transparent to the visible wavelength range while maintaining a high reflectance in the infrared range. Surprisingly, it has been found that the addition of a third refractive index range, referred to here as the mid-range (M), between the high and low refractive indexes can further improve the spectral properties and allow a higher level of optimization.

The invention comprises a glazing with a p-polarization reflecting coating (3) applied to the surface facing the vehicle interior (8). The reflectance of the coating is optimized to achieve high R _p (65) values at 469, 532 and 629 nm, while maintaining an integrated mixed polarization reflectance at zero degrees below 30% and a T _vis > 70%.

The p-polarization reflecting coating (3) is applied by magnetron sputtered vacuum deposition (MSVD). However, other methods can also be used.

The angles at which the image is projected can vary between 45 and 75 degrees. However, angles of 62 to 74 degrees are more practical. An angle of incidence (AOI) of 65 degrees is used in this invention as the angle preferred by automobile manufacturers. A typical HUD projector used in conjunction with this invention has a high proportion of p-polarization, e.g. 80% or even 90%, optimally 99.9%. In other words, the HUD projector emits mainly p-polarized light.

The p-polarization reflecting coating of the present invention is completely dielectric, i.e. it contains no conductive layers and therefore does not cause electromagnetic interference.

Starting from the glass surface, the coating comprises a sequence of layers that does not have a single L/H (high-index/low-index) layer sequence. Instead, the sequence comprises a series of L/M/H (low-index/medium-index/high-index) layer sequences, where M (medium-index) is a layer with a refractive index greater than 1.6 and less than 1.8 (all refractive indices refer to the measurement at a reference wavelength of 550 nm).

The L (low refractive index) dielectric layer of the invention has a refractive index of 1.6 or less. Typical examples of L layers are silicon oxide (SiOx) and silicon oxide nitride (SIOxNy) properly matched to obtain the required index. The SiOx typically has an index of 1.48, while SiOxNy is typically between 1.48 and 1.599.

The H-layer (high refractive index) dielectric layer of the invention has a refractive index of 1.8 or more. Typical examples of H-layers within the scope of the invention are titanium oxide (TiOx) and niobium oxide (NbOx). Their refractive indices are typically about 2.32 and 2.35, respectively.

The M-layer used in this invention is SiOxNy tuned to have an index greater than 1.6 and less than 1.8. The results presented in this invention refer to SiOxNy with an index of 1.78.

The HUD-capable vehicle glazing according to the invention comprises at least one glass layer in which the disclosed optimized p-polarization reflective coating is applied to at least a portion of the surface of the glass layer adjacent to the interior of the vehicle.

The layer sequence (3) extending from the glass surface comprises: at least one first dielectric layer (D1) with a refractive index greater than 1.6 and less than 1.8, at least one second dielectric layer (D2) with a refractive index less than or equal to 1.6, at least one third dielectric layer (D3) with a refractive index greater than 1.6 and less than 1.8, at least one fourth dielectric layer (D4) with a refractive index greater than or equal to 1.8, at least one fifth dielectric layer (D5) with a refractive index greater than 1.6 and less than 1.8, and at least one sixth dielectric layer (D6) with a refractive index less than or equal to 1.6.

The first (D1), third (D3) and fifth (D5) dielectric layers of the coating consist of SiOxNx, SiAlOx or AlOx and have a thickness in the range of 5 to 100 nm, and typically in the range of 15 to 70 nm.

The second dielectric layer (D2) of the coating consists of SiOx or SiOxNy, has a refractive index in the range of 1.480 to 1.599 and a thickness in the range of 20 to 120 nm and typically in the range of 40 to 90 nm.

The fourth dielectric layer (D4) of the coating consists of TiOx, ZrTiOx, ZrOx, ZnSnOx, ZnTiOx, ZnZrOx, SiZrOx, SiZrTiOx or NbOx, has a refractive index in the range of 2,000 to 2,400 and has a thickness in the range of 20 to 120 nm, typically in the range of 30 to 80 nm.

However, the glazing can also consist of a laminate with several layers of glass and one or more plastic connecting layers.

The glazing may further comprise other coatings and films, including solar control coatings, applied to one of the surfaces adjacent to a plastic bonding layer.

The head-up display coating of this disclosure may also include additional layers that provide solar protection properties.

The table in Figure 3A shows the thickness of each of the layers of Examples 1 to 4 in nanometers (nm). These thicknesses were carefully calculated using computer simulations and verified by experimental results. However, since the thickness required to achieve a particular spectral characteristic depends very strongly on the thickness and composition of the adjacent layers, significant deviations can occur and these values are not to be understood as a limitation. Likewise, the composition of the individual layers as described in the examples can vary, which also affects the layer thickness. The specific sequence of materials and layer thicknesses as disclosed is not to be understood as a limitation. The crucial feature is the refractive index of each layer and the sequence of H/M/L dielectrics.

The disclosed p-polarization reflective coating provides a perceived contrast between the primary and each of the secondary images of greater than 50:1. It also maintains the intensity of reflected p-polarized light at the selected RGB wavelengths (e.g. 469, 532 and 629 nm) and general mixed polarization light (normalized to eye sensitivity) at a minimum of 20% and a maximum of 30%, respectively, while achieving a transmission of at least 70% of general visible light.

When the image is projected onto the surface of the glazing adjacent to the vehicle interior, or part thereof, and at an angle of incidence relative to the glass surface of between 60 and 75 degrees, the image has the following optical characteristics: a p-polarisation reflection of at least 15% at 469 nm, 532 nm and 629 nm, an integrated mixed polarisation reflection (31) R _vis at 0 degrees of not more than 30%.

EXAMPLES

• 1. Example one includes a laminated automotive windshield having a 2.1 mm thick inner (202) and outer glass layer (201) of clear soda lime with a 0.76 mm thick PVB interlayer (4) and a transparent six-layer HUD coating (3) applied to the innermost surface (104) of the inner glass pane (201). Black frit shading is printed on both the second (102) and fourth (104) surfaces. The cross section of this configuration (200) is shown in Figure 1B The layer sequence is shown in Figure 2A The layer thicknesses are as follows (starting from the glass surface): a 75 nm thick SiOxNy layer, an 85 nm thick SiOx layer, a 23 nm thick SiOxNy layer, a 53 nm thick TiOx layer, a 30 nm thick SiOxNy layer and a 70 nm thick SiOx layer. T _vis is 75.3%; R _vis = 19.2%. R _p (65) values at 469, 532 and 629 nm are 21.3%, 23.2% and 16.1%, respectively. The transmitted CIELAB color values for T _mix (0) are: a*= - 0.6; b*= 0.7. The reflected CIELAB color values for R _mix (0) are: a*= -1.7; b*= 1.2. The spectral distributions of the p-polarized and mixed-polarized reflection in the visible part of the spectrum are shown in Figure 4A shown.
• 2. Example two is similar to the automotive laminated glass from example one, with the difference that that the coating consists of ten layers. The layer thicknesses are as follows (starting from the glass surface): a 16 nm thick SiOxNy layer with M index, a 55 nm thick SiOx layer with L index, a 12 nm thick SiOxNy layer with M index, a 43 nm thick TiOx layer with H index, a 34 nm thick SiOxNy layer, a 41 nm thick SiOx layer with L index, a 56 nm thick SiOxNy layer with M index, a 42 nm thick TiOx layer with H index, a 53 nm thick SiOxNy layer with M index and a 46 nm thick SiOx layer with L index. The HUD coating is applied to the entire area of surface four.
• 3. T _vis is 74.9%; R _vis = 25.10%. The R _p (65) values at 469, 532 and 629 nm are 25.2%, 31.2% and 20.01% respectively. The transmitted CIELAB color values at zero degrees from the normal (T _mix (0)) are: a*= - 0.05; b*= - 0.33. The reflected CIELAB color values at zero degrees from the normal (R _mix (0)) are: a*= + 0.11; b*= + 0.69. The layer sequence is shown in Figure 2 B The spectral distributions of the p-polarized and mixed-polarized reflection in the visible part of the spectrum are shown in Figure 4B shown.
• 4. Example three is similar to the automotive laminated glass of example two, except that the coating layer thicknesses are as follows (starting from the glass surface): a 16 nm thick SiOxNy layer, a 56 nm thick SiOx layer, a 12 nm thick SiOxNy layer, a 40 nm thick TiOx layer, a 34 nm thick SiOxNy layer, a 40 nm thick SiOx layer, a 57 nm thick SiOxNy layer, a 49 nm thick TiOx layer, a 50 nm thick SiOxNy layer, and a 46 nm thick SiOx layer. T _vis is 76.1%; R _vis = 23.9%. The R _p (65) values at 469, 532, and 629 nm are 22.3%, 30.8%, and 20.3%, respectively. The transmitted CIELAB color values at zero degrees from the normal (T _mix (0)) are: a*= 0.00; b*= - 0.14. The reflected CIELAB color values at zero degrees from the normal (R _mi (0)) are: a*= 0.00; b*= + 0.31. The spectral distributions of the p-polarized and mixed-polarized reflection in the visible part of the spectrum are shown in Figure 5A shown.
• 5. Example four is similar to the automotive laminated glass of example two, except that the layer thicknesses of the coating are as follows (starting from the glass surface): a 16 nm thick SiOxNy layer, a 70 nm thick SiOx layer, a 10 nm thick SiOxNy layer, a 43 nm thick TiOx layer, a 32 nm thick SiOxNy layer, a 45 nm thick SiOx layer, a 63 nm thick SiOxNy layer, a 45 nm thick TiOx layer, a 53 nm thick SiOxNy layer and a 40 nm thick SiOx layer.
• T _vis is 76.2%; R _vis = 23.8%. The R _p (65) values at 469, 532 and 629 nm are 20.0%, 30.3% and 21.0% respectively. The transmitted CIELAB color values for T _mix (0) are: a*= 0.22; b*= - 0.09. The reflected CIELAB color values for R _mix (0) are: a*= 0.48; b*= + 0.20. The spectral distributions of the p-polarized and mixed-polarized reflection in the visible part of the spectrum are shown in Figure 5B shown.

MODELS OF IMPLEMENTATION

1. 1. Embodiment one is a monolithic tempered glazing (100) with the transparent HUD coating from example one.
2. 2. Embodiment two is a monolithic tempered glazing (100) with the transparent HUD coating from example two.
3. 3. Embodiment three is a monolithic tempered glazing (100) with the transparent HUD coating from example three.
4. 4. Embodiment four is a monolithic tempered glazing (100) with the transparent HUD coating from example four.
5. 5. Embodiment five is a laminated glass windshield having an infrared reflective solar control coating (20) on surface two (102) of the first (outer) glass layer (201). The cross-section of this configuration (300) is shown in Figure 1C shown.
6. 6. Embodiment six is similar to example two. The glazing also includes an infrared reflective solar control coating (20) on surface two (102) of the first (outer) glass layer (201). The cross-section of this configuration (300) is shown in Figure 1C shown.
7. 7. Embodiment seven is similar to example three. The glazing also includes an infrared reflective solar control coating (20) on surface two (102) of the first (outer) glass layer (201). The cross-section of this configuration (300) is shown in Figure 1C shown.
8. 8. Embodiment eight is similar to example four. The glazing further comprises an infrared reflective solar control coating (20) on the surface two (102) of the first (outer) glass layer (201). The cross section This configuration (300) is shown in Figure 1C shown.

A glazing for a vehicle optimized for the reflection of p-polarized light, comprising a unique transparent p-polarized light reflecting coating comprising at least six dielectric layers applied to the surface of the glazing facing the vehicle interior. The glazing also includes a head-up display projector that emits substantially p-polarized light. The HUD image is projected onto at least a portion of the coated surface of the glazing. The coating consists of dielectric layers whose refractive index falls into three ranges: low, medium and high. The layers are applied in order of refractive index of medium, low, medium, high, medium, low, starting from the glass surface.

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions.

Cited patent literature

• EP1880243A2 [0012]
• WO 2009/071135 A1 [0012]
• CN113031276A [0026]
• US10437054 [0029]
• DE 102014220189 A1 [0029]
• WO 2019046157 A1 [0029]

Claims (17)

A glazing (100, 200, 300) for a vehicle optimized for the reflection of p-polarized light, comprising: at least one glass layer (201, 202), the glass layer having two surfaces, a first surface (8) adjacent to the interior of the vehicle and a second surface opposite the first surface; and a transparent, p-polarized light-reflecting coating (3) applied to at least a portion of the first surface (8) of said glass layer, the coating (3) comprising, counting from the glass surface: at least one first dielectric layer (D1) with a refractive index greater than 1.6 and less than 1.8, at least one second dielectric layer (D2) with a refractive index of less than or equal to 1.6, at least one third dielectric layer (D3) with a refractive index greater than 1.6 and less than 1.8, at least one fourth dielectric layer (D4) with a refractive index of greater than or equal to 1.8, at least one fifth dielectric layer (D5) with a refractive index of greater than 1.6 and less than 1.8, and at least one sixth dielectric layer (D6) with a refractive index of less than or equal to 1.6. A glazing for a vehicle according to the preceding claim, wherein the glazing (100, 200, 300) has a total visible light transmittance of at least 70%. The glazing for a vehicle according to any one of the preceding claims, wherein one of the first (D1), third (D3) and fifth (D5) dielectric layers consists of SiOxNx, SiAlOx or AlOx. A glazing for a vehicle according to any one of the preceding claims, wherein the first (D1), third (D3) and fifth (D5) dielectric layers have a thickness in the range of 5 to 100 nm, and typically in the range of 15 to 70 nm. A glazing for a vehicle according to any one of the preceding claims, wherein the second dielectric layer (D2) consists of SiOx and SiOxNy. A glazing for a vehicle according to any one of the preceding claims, wherein the second dielectric layer (D2) has a refractive index in the range 1.480 to 1.599. A glazing for a vehicle according to any one of the preceding claims, wherein the second dielectric layer (D2) has a thickness in the range of 20 to 120 nm and typically in the range of 40 to 90 nm. A glazing for a vehicle according to any one of the preceding claims, wherein the fourth dielectric layer (D4) consists of TiOx, ZrTiOx, ZrOx, ZnSnOx, ZnTiOx, ZnZrOx, SiZrOx, SiZrTiOx or NbOx. A glazing for a vehicle according to any one of the preceding claims, wherein the fourth dielectric layer (D4) has a refractive index in the range 2,000 to 2,400. A glazing for a vehicle according to any one of the preceding claims, wherein the fourth dielectric layer (D4) has a thickness in the range of 20 to 120 nm and typically in the range of 30 to 80 nm. A vehicle glazing according to any one of the preceding claims, wherein the coating (3) further comprises at least one seventh dielectric layer (D7) having a refractive index greater than 1.6 and less than 1.8, at least one eighth dielectric layer (D8) having a refractive index greater than or equal to 1.8, at least one ninth dielectric layer (D9) having a refractive index greater than 1.6 and less than 1.8 and at least one tenth dielectric layer (D10) having a refractive index less than or equal to 1.6. A glazing for a vehicle according to any one of the preceding claims, wherein the glazing is laminated with at least one additional glass layer (201) and at least one plastics bonding layer (4). An automotive glazing according to any preceding claim, wherein the glazing further comprises a laminate having a solar control coating (20) disposed on a surface in contact with and immediately adjacent to the plastics bonding layer (4). An automotive glazing according to any preceding claim, wherein the p-polarized light-reflecting coating (3) comprises additional layers providing solar control properties. A glazing for a vehicle according to any one of the preceding claims, further comprising a head-up display projector (24) emitting mainly p-polarized light, whereby an image (30) is projected onto at least a portion of the glazing adjacent to the vehicle interior (8). surface of the glass layer (202) with the coating (3) at an angle of incidence relative to the glass surface of between 60 and 75 degrees, and wherein the image (30) has a p-polarized reflection (31) of at least 15% at 469 nm, 532 nm and 629 nm. Glazing for a vehicle according to Claim 15 with an integrated mixed polarization reflection at 0 degree entrance angle of less than or equal to 30%. A glazing for a vehicle according to any one of the preceding claims, wherein the coating (3) has CIELAB colour coordinates for both transmitted and reflected light, the values of both a* and b* being between -0.30 and 0.30.

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