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CN-122003564-A - Optical structure with light guide

CN122003564ACN 122003564 ACN122003564 ACN 122003564ACN-122003564-A

Abstract

The invention relates to an optical structure (10) comprising-a light guide (40) having a decoupling element (60) on a rear face (42), the decoupling element (60) being configured to divert light guided by the light guide to a front face (41) of the light guide (40) opposite to the rear face, the light guide (40) being made of a first material having a first refractive index (n 1), -a protective layer (30) on the rear face (42) of the light guide (40) covering the decoupling element (60), the protective layer (30) being transparent, the protective layer (30) being made of a second material having a second refractive index (n 2), in which optical structure the first refractive index (n 1) is greater than the second refractive index (n 2), the difference between the first refractive index (n 1) and the second refractive index (n 2) being between 0.1 and 0.3.

Inventors

  • B. Delander
  • SANCHEZ VELVET
  • S. Rawls
  • P-L. Tashi

Assignees

  • 法雷奥照明公司

Dates

Publication Date
20260508
Application Date
20241010
Priority Date
20231012

Claims (15)

  1. 1. An optical structure (10), in particular for a motor vehicle, comprising: -a light guide (40) having decoupling elements (60) on a rear face (42), the decoupling elements (60) being configured to divert light guided by the light guide to a front face (41) of the light guide (40) opposite to the rear face, the light guide (40) being made of a first material having a first refractive index (n 1), -A protective layer (30; 300) covering the decoupling element (60) on the rear face (42) of the light guide (40), the protective layer (30) being transparent, the protective layer (30) being made of a second material having a second refractive index (n 2), The first refractive index (n 1) is larger than the second refractive index (n 2), the difference between the first refractive index (n 1) and the second refractive index (n 2) is between 0.1 and 0.3, and the contact between the light guide (40) and the protective layer (30; 300) forms a fully filled interface such that the decoupling element (60) is not visible in the absence of light incident into the light guide (40).
  2. 2. The optical structure (10) of claim 1, wherein the light guide (40) has an interface with air at a front face (41) of the light guide (40).
  3. 3. The optical structure (10) of claim 1, wherein the light guide receives an additional protective layer on a front face (41) of the light guide, the additional protective layer preferably having a first face in contact with the light guide and a second face opposite the first face, the second face having an interface with air.
  4. 4. The optical structure (10) of any one of the preceding claims, wherein the first material and the second material form one of a pair of materials (first material/second material) in the list of: polymethyl methacrylate nanocomposite coating Polycarbonate/poly (carbonate) methyl methacrylate Polycarbonate/silicone Polycarbonate/nanocomposite coating Polyurethane/silicone Polyurethane/polyethylene Glass/silicone -A glass/nanocomposite coating.
  5. 5. The optical structure (10) according to any one of the preceding claims, wherein the decoupling element (60) has a height of less than 500 micrometers, in particular less than 200 micrometers or less than 100 micrometers.
  6. 6. The optical structure (10) of any one of the preceding claims, comprising a decorative layer (20) placed facing the protective layer (30) of the optical structure and visible through the protective layer (30) of the optical structure and the light guide (40) without light being incident into the light guide via a front face of the light guide (40).
  7. 7. The optical structure (10) according to the preceding claim, wherein the decorative layer (20) and the protective layer (30) form a completely filled interface.
  8. 8. The optical structure (10) of any one of the preceding claims, wherein the light guide is rigid.
  9. 9. The optical structure (10) of the preceding claim, wherein the light guide has a thickness of greater than or equal to 1.5mm, preferably greater than or equal to 3 mm.
  10. 10. The optical structure (10) according to claim 8 or 9, wherein the light guide can form at least part of a motor vehicle component, such as a closed outer lens of a headlight or a rear lamp of a motor vehicle, or a trim part of a body part or a passenger compartment.
  11. 11. A lighting system (100), in particular for a motor vehicle, comprising: an optical structure (10) according to any one of the preceding claims, -A light source (50) configured to enter light into the light guide (40) via an entrance area configured such that the incident light is guided through the light guide (40) and reflected by a decoupling element (60) on a rear face of the light guide (40).
  12. 12. The lighting system (100) of claim 11, wherein the light source is positioned face-to-face with an area of the light guide (40) that is outside the protective layer (30).
  13. 13. The lighting system (100) of claim 11 or 12, comprising an opaque insert (70) that allows the light source to be hidden so as to block direct light from the light source.
  14. 14. The lighting system (100) according to any one of claims 11 to 13, wherein the lighting system (100) is configured to participate in performing a signaling function.
  15. 15. A motor vehicle component comprising the optical structure of claim 10, the light guide forming at least a portion of the vehicle component.

Description

Optical structure with light guide The field of the invention is that of optical structures, in particular for motor vehicles, comprising a light guide for turning light and illuminating, for example, a body part, a protective outer lens (such as the outer lens of a headlight or a rear lamp), or the inner surface of a motor vehicle. In order to give a vehicle specific lighting feature or to create a lighting environment in the passenger compartment, it is increasingly common to introduce lighting systems that allow to create a lighting pattern when the light source of the lighting system is activated. For producing a visual effect, it may be desirable that the lighting pattern or even the lighting system is not visible when the light source is turned off. Thus, the light emitting pattern only appears when the light source is activated. For this purpose, decorative elements are usually placed on top of the lighting system. Thus, the decorative element conceals the lighting system such that the pattern is not visible when the lighting system is turned off. However, when the lighting system is activated, the decorative element cuts off some of the light emitted by the lighting system, which reduces the optical efficiency of the lighting system. It is therefore desirable to provide a lighting system that allows for a better optical efficiency of generating a lighting pattern when on and is not visible when off. A subject of the invention is therefore an optical structure, in particular for a motor vehicle, comprising: A light guide having decoupling elements on a rear face, the decoupling elements being configured to divert light guided by the light guide to a front face of the light guide opposite the rear face, the light guide being made of a first material having a first refractive index (n 1), -A protective layer covering the decoupling elements on the rear face of the light guide, the protective layer being transparent, the protective layer being made of a second material having a second refractive index (n 2). In the optical structure, the first refractive index (n 1) is larger than the second refractive index (n 2), the difference between the first refractive index (n 1) and the second refractive index (n 2) is between 0.1 and 0.3, and the contact between the light guide and the protective layer forms a completely filled interface, such that the decoupling element is not visible in the absence of light incident into the light guide. Layers with a high transmission coefficient are referred to as "transparent layers" (in particular with respect to transparent protective layers). If the inherent transmittance of the layer is considered, the layer may be considered transparent when the transmittance of the layer is greater than 95% or 99%. The inherent transmissivity of this layer is determined by ignoring fresnel reflections at its interface, which depend on the refractive index of the adjoining material. If the transmittance of the layer in air is considered, the layer may be considered transparent when the transmittance of the layer is greater than 85% or 90%. The decoupling elements allow one or more light emitting patterns to be formed when light is introduced into the light guide. In case the decorative layer is positioned face-to-face with the protective layer, light does not need to pass through the decorative layer to leave the optical structure (because the decoupling element is configured to divert light guided by the light guide to a front face of the light guide opposite to a rear face receiving the protective layer), which gives the optical structure good optical efficiency. In the present invention, the difference between the first refractive index (n 1) and the second refractive index (n 2) is advantageously chosen to be greater than 0.1 in order to ensure that light incident into the light guide is guided through the light guide by total internal reflection, and less than 0.3 such that light originating from the environment outside the optical structure is deflected as little as possible by refraction at the interface between the light guide and the protective layer. In addition, the contact between the light guide and the protective layer forms a completely filled interface. A completely filled interface refers to an interface that does not contain any air or bubbles. Such a completely filled interface makes it possible to avoid parasitic reflections at the interface between the light guide and the protective layer, which would allow the decoupling pattern to be seen. A completely filled interface is obtained by directly joining the two components at the interface. Thus, the interface between the light guide and the protective layer is airless, which allows to minimize the deflection of light at the interface between the light guide and the protective layer. By means of the difference between the first refractive index (n 1) and the second refractive index (n 2) and the completely filled in