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US-12619071-B2 - Composite pane for a head-up display comprising a heatable sensor region

US12619071B2US 12619071 B2US12619071 B2US 12619071B2US-12619071-B2

Abstract

A composite pane with an HUD region and a sensor region is provided with an electrically conductive coating that reflects the p-polarized radiation of the HUD projector. The electrically conductive coating has precisely one electrically conductive layer based on silver, below which a lower dielectric layer or layer sequence with a refractive index of at least 1.9 is arranged and above which an upper dielectric layer or layer sequence with a refractive index of at least 1.9 is arranged. The ratio of the optical thickness of the upper dielectric layer or layer sequence to the optical thickness of the lower dielectric layer or layer sequence is at least 1.7. A busbar provided for connection to a voltage source is arranged on both sides of the sensor region and is connected to the coating such that a current path for a heating current is formed between the busbars.

Inventors

  • Lisa SCHMADTKE
  • Jan Hagen
  • THOMAS GALLINELLI
  • Stephan GILLESSEN
  • Jefferson DO ROSARIO

Assignees

  • SAINT-GOBAIN GLASS FRANCE

Dates

Publication Date
20260505
Application Date
20220309
Priority Date
20210422

Claims (18)

  1. 1 . A composite pane for a head-up display (HUD) with a heatable sensor region, comprising: an outer pane with an exterior-side surface and an interior-side surface, an inner pane with an exterior-side surface and an interior-side surface, wherein the interior-side surface of the outer pane is joined to the exterior-side surface of the inner pane via a thermoplastic intermediate layer, an electrically conductive coating on the interior-side surface of the outer pane, on the exterior-side surface of the inner pane, or within the intermediate layer, wherein the composite pane has an HUD region that is provided for irradiation by an HUD projector with p-polarized radiation, and has a sensor region that is provided for transmission of electromagnetic radiation for a sensor directed toward the interior-side surface of the inner pane, and wherein the electrically conductive coating is adapted to reflect the radiation of the HUD projector, the electrically conductive coating has precisely one electrically conductive layer based on silver, a lower dielectric layer or lower dielectric layer sequence, whose refractive index is at least 1.9, is arranged below the electrically conductive layer, an upper dielectric layer or upper dielectric layer sequence, whose refractive index is at least 1.9, is arranged above the electrically conductive layer, a ratio of an optical thickness of the upper dielectric layer or upper dielectric layer sequence to an optical thickness of the lower dielectric layer or lower dielectric layer sequence is at least 1.7, the electrically conductive coating is present within the sensor region so as to completely cover the sensor region, and wherein a busbar provided for connection to a voltage source is arranged in each case on both sides of the sensor region and is connected to the electrically conductive coating such that a current path for a heating current is formed between the busbars, with said current path running across the sensor region.
  2. 2 . The composite pane according to claim 1 , that has light transmittance of at least 70% at an angle of incidence of 0° and light transmittance of at least 50% at an angle of incidence of 73.5°.
  3. 3 . The composite pane according to claim 1 , wherein a ratio of a transmittance of p-polarized light to a transmittance of s-polarized light at an angle of incidence of 70° is at least 1.20.
  4. 4 . The composite pane according to claim 1 , which has, in a spectral range from 400 nm to 680 nm, an averaged reflectance for p-polarized radiation of at least 10%, wherein a difference between a maximally occurring reflectance and a mean value of the reflectance as well as a difference between a minimally occurring reflectance and the mean value of the reflectance for p-polarized radiation is at most 3%.
  5. 5 . The composite pane according to claim 1 , which has an upper edge, a lower edge, and two side edges extending therebetween, wherein one busbar is arranged between the sensor region and one side edge of the two side edges and the other busbar is arranged between the sensor region and the other side edge of the two side edges.
  6. 6 . The composite pane according to claim 1 , wherein a heated region of the electrically conductive coating arranged between the busbars has an area of 20 cm 2 to 100 cm 2 , while a majority of the composite pane is not heated by the electrically conductive coating.
  7. 7 . The composite pane according to claim 1 , wherein a region of the electrically conductive coating that contains the busbars and the sensor region situated therebetween is electrically isolated from the surrounding electrically conductive coating by an insulation line.
  8. 8 . The composite pane according to claim 1 , wherein the electrically conductive layer has a geometric thickness of 8 nm to 14 nm.
  9. 9 . The composite pane according to claim 8 , wherein the electrically conductive layer has a geometric thickness of 10 nm to 12 nm.
  10. 10 . The composite pane according to claim 8 , wherein the electrically conductive layer has a geometric thickness of 10 nm to 11 nm.
  11. 11 . The composite pane according to claim 1 , wherein the optical thickness of the upper dielectric layer or upper dielectric layer sequence is from 100 nm to 200 nm, and the optical thickness of the lower dielectric layer or lower dielectric layer sequence is from 50 nm to 100 nm.
  12. 12 . The composite pane according to claim 11 , wherein the optical thickness of the upper dielectric layer or upper dielectric layer sequence is from 130 nm to 170 nm, and the optical thickness of the lower dielectric layer or lower dielectric layer sequence is from 60 nm to 90 nm.
  13. 13 . The composite pane according to claim 1 , wherein the upper dielectric layer or upper dielectric layer sequence and the lower dielectric layer or lower dielectric layer sequence, independently of one another, have, in each case: an anti-reflection layer based on silicon nitride, optionally, a matching layer based on zinc oxide, and optionally, a refractive-index-enhancing layer based on a mixed silicon-metal nitride.
  14. 14 . The composite pane according to claim 1 , wherein the outer pane and the inner pane are made of clear soda lime glass.
  15. 15 . The composite pane according to claim 1 , which is a vehicle windshield, wherein the sensor region is arranged outside and the HUD region is arranged at least partially within the field of vision B or I according to ECE-R43, wherein the field of vision B or I is not heated by the electrically conductive coating.
  16. 16 . A projection assembly for a head-up display (HUD), comprising: a composite pane according to claim 1 , a sensor attached to the interior-side surface of the inner pane and directed toward the sensor region, and an HUD projector, which is directed toward the HUD region and whose radiation is p-polarized.
  17. 17 . The projection assembly according to claim 16 , wherein the sensor is an IR sensor, a light sensor, a UV sensor, a camera, a radar system, or a lidar system.
  18. 18 . The projection assembly according to claim 16 , wherein the radiation of the projector strikes the windshield at an angle of incidence of 60° to 70°.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is the U.S. National Stage of PCT/EP2022/055998, filed Mar. 9, 2022, which in turn claims priority to European patent application number 21169769.3 filed Apr. 22, 2021. The content of these applications are incorporated herein by reference in their entireties. The invention relates to a composite pane for a head-up display (HUD) comprising a heatable sensor region as well as a projection assembly containing this for a head-up display. Modern automobiles are increasingly equipped with so-called head-up displays (HUDs). With an HUD projector, typically in the region of the dashboard, images are projected onto the windshield, reflected there, and perceived by the driver as a virtual image behind the windshield (from his perspective). Thus, important data can be projected into the driver's field of vision, for example, the current driving speed, navigation or warning messages, which the driver can perceive without having to take his eyes off the road. HUDs are known in which the HUD projector is operated with p-polarized radiation. Since the typical angle of incidence in vehicles is about 65° and thus close to Brewster's angle for an air/glass transition (56.5° for soda lime glass), no significant reflection occurs at the pane surfaces. This avoids the occurrence of an offset ghost image (“ghost”), which occurs with HUD projectors with s-polarized radiation due to reflection from both external surfaces and is typically remedied with costly wedge-shaped films or glass panes in order to arrange the two surfaces with an angle relative to one another such that the ghost image coincides with the primary image. Instead, the windshield has a reflection coating as a reflection surface for the p-polarized radiation. Such HUDs are disclosed, for example, in DE102014220189A1, WO2019046157A1, and US2017242247A1. The post-published international application WO2021104800A1 discloses a windshield with a reflection coating for the p-polarized radiation of an HUD projector. The reflection coating has a single silver layer, as a result of which high transparency is ensured. By specific selection of the dielectric layer modules situated above and below this silver layer, good reflection characteristics for p-polarized radiation are achieved, in particular, high average reflectance and color-neutral display. In addition to HUDs, sensors on windshields are increasingly widespread. Examples include video cameras, night vision cameras, residual light amplifiers, laser rangefinders, passive infrared detectors, radar or lidar sensors, which can also be used in combination, for example, in driver assistance systems (ADAS, Advanced Driver Assistance Systems). The sensor is attached to the windshield on the interior side and associated with a sensor region (typically above the central field of vision) and is suitable for detecting electromagnetic radiation that passes through the sensor region from the outside. For the sensors to function optimally, the sensor region must have certain optical properties. These include relatively high transmittance in the red spectral range (about 600 nm to 700 nm), high transmittance of light that strikes the windshield at a relatively flat angle, and relatively high transmittance of p-polarized radiation compared to s-polarized radiation (to suppress reflections from, for example, a wet road). If the windshield is equipped with an electrically conductive coating, this typically has a negative effect on said optical properties. Consequently, the coating is often removed in the sensor field, as disclosed, for example, in WO2010136400A1, making production of the windshield more complex. The unpublished international application PCT/EP2021/077996 discloses a windshield with a reflection coating for the p-polarized radiation of an HUD projector. Here, as well, the reflection coating has a single silver layer. The windshield also has a sensor field that is likewise covered with the reflection coating. It is also desirable for the sensor region to be heatable such that, as needed, it can be freed of ice, frost, dew, or other moisture buildup. For example, heating wires or printed heating conductors can be arranged in an uncoated sensor region, as disclosed, for example, in EP2510745B1 or WO2012031907A1. However, such intrinsically opaque heating conductors reduce light transmittance and can lead to undesirable optical effects, for example, scattering effects, which negatively affect the functionality of the sensor. The unpublished international application PCT/EP2022/050333 discloses a windshield with a heatable sensor field using a heatable film. The unpublished international application PCT/EP2021/086176 discloses a windshield with an electrically conductive coating based on a transparent conductive oxide (TCO) that is used to heat a sensor field. There continues to be a need for composite panes that can be used as a projection surface for an HUD with p