Search

WO-2026092909-A1 - WINDSCREEN WITH REFLECTIVE COATING AND ANTI-REFLECTIVE COATING AND PROJECTION ARRANGEMENT FOR A HEAD-UP DISPLAY

WO2026092909A1WO 2026092909 A1WO2026092909 A1WO 2026092909A1WO-2026092909-A1

Abstract

The present invention relates to a windscreen (10) for a head-up display (HUD), comprising an outer pane (1) and an inner pane (2), which are connected to each other by means of a thermoplastic intermediate layer (3), which has at least one HUD region (A) and which is provided at least in the HUD region (A) with a reflective coating (20) which is located on the interior-side surface (II) of the outer pane (1), on the exterior-side surface (III) of the inner pane (2) or within the intermediate layer (3) and is suitable for reflecting p-polarized radiation, wherein the windscreen (10) is provided at least in the HUD region (A) with an anti-reflective coating (30) which is located on the interior-side surface (IV) of the inner pane (2) and has an optically low-refractive-index layer (31) with a thickness of 120 nm to 180 nm and a refractive index of less than 1.4, based on a wavelength of 550 nm.

Inventors

  • HAGEN, JAN
  • RASTEGAR, Hadi

Assignees

  • SAINT-GOBAIN SEKURIT FRANCE

Dates

Publication Date
20260507
Application Date
20250915
Priority Date
20241029

Claims (15)

  1. 1. Windscreen (10) for a head-up display (HUD), comprising an outer pane (1) with an outer surface (I) and an inner surface (II) and an inner pane (2) with an outer surface (III) and an inner surface (IV), wherein the inner surface (II) of the outer pane (1) and the outer surface (III) of the inner pane (2) are connected to each other via a thermoplastic intermediate layer (3) which has at least one HUD area (A) and which is provided, at least in the HUD area (A), with a reflective coating (20) arranged on the inner surface (II) of the outer pane (1), on the outer surface (III) of the inner pane (2), or within the intermediate layer (3) and which is suitable for reflecting p-polarized radiation, wherein the windscreen (10) is provided, at least in the HUD area (A), with an anti-reflective coating (30) arranged on the inner surface (IV) of the inner disk (2) is arranged and has an optically low refractive index layer (31) with a refractive index of less than 1.4, based on a wavelength of 550 nm, wherein the optically low refractive index layer (31) has a thickness of 120 nm to 180 nm.
  2. 2. Windscreen (10) according to claim 1, wherein the refractive index of the optically low refractive layer (31) is at most 1.35, preferably at most 1.3.
  3. 3. Windscreen (10) according to claim 1 or 2, wherein the optically low refractive index layer (31) is formed on the basis of nanoporous silicon oxide, doped silicon oxide, magnesium fluoride or calcium fluoride, preferably on the basis of nanoporous silicon oxide.
  4. 4. Windscreen (10) according to claim 3, wherein the optically low refractive index layer (31) is a sol-gel layer based on nanoporous silicon oxide in which closed and/or open nanopores are formed, preferably with a size of 1 nm to 500 nm, particularly preferably from 1 nm to 100 nm, most preferably from 20 nm to 80 nm. 35 SAINT-GOBAIN SEKURIT FRANCE 2024339-WO-PCT
  5. 5. Windscreen (10) according to one of claims 1 to 4, wherein the optically low refractive index layer (31) has a thickness of 120 nm to 170 nm.
  6. 6. Windscreen (10) according to one of claims 1 to 5, wherein the anti-reflective coating (30) consists exclusively of the optically low refractive index layer (31).
  7. 7. Windscreen (10) according to one of claims 1 to 5, wherein an optically high refractive index layer (32) with a refractive index of more than 1.9 is arranged below the optically low refractive index layer (31), and wherein the antireflection coating (30) preferably consists exclusively of the optically low refractive index layer (31) and the optically high refractive index layer (32).
  8. 8. Windscreen (10) according to claim 7, wherein the optically high refractive index layer (32) is based on silicon nitride, silicon metal nitride or titanium oxide.
  9. 9. Windscreen (10) according to claim 7 or 8, wherein the optically high refractive index layer (32) has a thickness of 5 nm to 50 nm, preferably 10 nm to 30 nm.
  10. 10. Windscreen (10) according to one of claims 1 to 9, wherein the reflective coating (20) has at least one electrically conductive layer (21) based on silver, preferably exactly one electrically conductive layer (21) based on silver.
  11. 11. Windscreen (10) according to claim 10, wherein the reflective coating (20) is configured such that - below the electrically conductive layer (21) a lower dielectric layer or sequence of layers (22a, 22b, 22c) is arranged, the refractive index of which is at least 1.9, and - above the electrically conductive layer (21) an upper dielectric layer or sequence of layers (23a, 23b, 23c) is arranged, the refractive index of which is at least 1.9, wherein the ratio of the optical thickness of the upper dielectric layer or sequence of layers (23a, 23b, 23c) to the optical thickness of the lower dielectric layer or sequence of layers (22a, 22b, 22c) is at least 1.7. SAINT-GOBAIN SEKURIT FRANCE 2024339-WO-PCT
  12. 12. Projection arrangement for a head-up display, comprising - a windshield (10) according to one of claims 1 to 11 and - an imaging unit (4) which is directed towards and illuminates the HUD area (A).
  13. 13. Projection arrangement according to claim 12, wherein the imaging unit (4) irradiates the HUD area (A) with p-polarized radiation and with an angle of incidence (a) of 60° to 70°.
  14. 14. Projection arrangement according to claim 12 or 13, wherein the outer surface (I) of the outer disk (1) and the inner surface (IV) of the inner disk (2) are aligned parallel to each other.
  15. 15. Projection arrangement according to any one of claims 12 to 14, wherein the outer pane (1) and the inner pane (2) are made of soda-lime glass. ```

Description

SAINT-GOBAIN SEKURIT FRANCE 2024339-WO-PCT Windscreen with reflective and anti-reflective coating, and projection arrangement for a head-up display. The invention relates to a windshield and a projection arrangement equipped therewith for a head-up display. Modern vehicles are increasingly equipped with so-called head-up displays (HUDs). A projector, typically located in the dashboard area, projects images onto the windshield's viewing area, where they are reflected and perceived by the driver as a virtual image (from their perspective) behind the windshield. This allows important information to be projected into the driver's field of vision, such as current speed, navigation instructions, or warnings, which the driver can see without taking their eyes off the road. Head-up displays can thus significantly contribute to improving road safety. Windshields for vehicles, especially motor vehicles such as passenger cars, are designed as laminated glass (laminated safety glass), consisting of an outer and an inner pane laminated together with a thermoplastic interlayer. HUD projectors typically illuminate the windshield at an angle of incidence of approximately 65°, which is close to the Brewster angle for an air-glass interface (57.2° for soda-lime glass). This fact can be exploited for a clear HUD projection: if the HUD projector uses p-polarized radiation, it will hardly reflect the radiation at the external glass surfaces of the windshield. Instead, the windshield is coated with a reflective coating suitable for reflecting the p-polarized radiation to generate the displayed image. Since there is only one significant reflection plane, namely the reflective coating, a clear display image is produced without ghosting (or with only faint ghosting, which is due to residual reflection at the external glass surfaces if the angle of incidence deviates slightly from Brewster's angle). Examples can be found in DE102014220189A1, EP3187917B1 and WO2021104800A1. Such reflective coatings often contain silver layers and are therefore located inside the windshield between the outer and inner panes to protect the corrosion-prone silver layers from contact with the atmosphere and the associated corrosion. Windshields with such coatings SAINT-GOBAIN SEKURIT FRANCE 2024339-WO-PCT Reflective coatings typically also exhibit a significant reflectivity of s-polarized radiation, which is reflected particularly from the inner surface of the windshield. This can lead to unwanted reflections on the windshield, resulting from the reflection of s-polarized light (or the s-polarized components of unpolarized light). The reflected light may include (desired or undesired) s-polarized radiation from the HUD projector and/or radiation not originating from the HUD projector (for example, from displays in the vehicle's instrument cluster). Such reflections can be distracting to the viewer, distract the driver, or even render the HUD projection difficult to see. WO2021209201 A1 discloses in comparative example 2 a generic windscreen for a HUD with a reflective coating on the outer surface of the inner pane, comprising a single silver layer, and an antireflective coating on the inner surface of the inner pane. The antireflective coating is a layer of nanoporous silicon oxide with a thickness of 100 nm. WO2023052228A1 discloses a generic windscreen for a HUD with a reflective coating on the interior surface of the outer pane or the exterior surface of the inner pane, comprising at least one silver layer, and an antireflective coating on the interior surface of the inner pane. The antireflective coating has a single high-refractive-index layer and a single low-refractive-index layer, the low-refractive-index layer having a thickness of at most 60 nm and being formed, for example, from sputtered silicon dioxide with a refractive index of 1.45. The present invention is based on the objective of providing a further improved windshield for a head-up display (HUD) which is equipped with a reflective coating that is intended to reflect, in particular, p-polarized light from an imaging unit, whereby disturbing reflections on the windshield are to be avoided or at least reduced, especially such reflections which are due to the reflection of s-polarized light. SAINT-GOBAIN SEKURIT FRANCE 2024339-WO-PCT The object of the present invention is achieved according to the invention by a windshield according to claim 1. Preferred embodiments are described in the dependent claims. The windshield according to the invention for a head-up display is designed as a laminated glass and comprises an outer pane and an inner pane, which are bonded together via a thermoplastic intermediate layer. The windshield is intended to separate the interior (vehicle interior) from the external environment in the forward-facing window opening of a vehicle. For the purposes of the invention, the inner pane refers to the pane of the windshield facing the interior. The outer pane refers