Waveguide Pupil Expander With Louvre Reflection Suppression

Solution Overview

Problem

Existing display systems face challenges in suppressing reflections of sunlight and stray light, particularly in head-up displays, which can degrade image quality and visibility.

Innovation Solution

Incorporating a waveguide pupil expander with a light control layer featuring a louvre structure or light absorbing materials to suppress specular reflections, and using a light turning element with prisms to control the direction of output image light, while also employing a waveguide with parallel reflective surfaces for internal reflection and waveguiding.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If a waveguide pupil expander is used to expand the viewing area, then the viewing area is expanded and image quality is enhanced, but reflections of sunlight and stray light are introduced that degrade visibility

Engineering Contradiction:

Improveviewing areaVSAvoidsunlight reflections

Core Design Contradiction:

Area of stationary objectVSObject-affected harmful factors

Solution Approach 1:

The optical component is divided into multiple surfaces with different functions: first and second major surfaces for waveguiding light, and one or more minor surfaces (edge faces) for suppressing reflections. This segmentation allows each surface to be optimized for its specific function without compromising the others.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different surfaces of the optical component are assigned different properties: the major surfaces are made reflective for waveguiding, while the minor surfaces are treated to suppress reflections. This local differentiation of properties resolves the contradiction by making each area perform its optimal function.

Inventive Principle:

Principle #3Local quality

2Use of energy by moving object

If reflective surfaces are used for waveguiding light, then light transmission is improved, but specular reflections of sunlight are enhanced

Engineering Contradiction:

Improvelight transmissionVSAvoidspecular reflections

Core Design Contradiction:

Use of energy by moving objectVSObject-generated harmful factors

Solution Approach 1:

The optical component is divided into multiple surfaces with different functions: first and second major surfaces for waveguiding light, and one or more minor surfaces (edge faces) for suppressing reflections. This segmentation allows each surface to be optimized for its specific function without compromising the others.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different surfaces of the optical component are assigned different properties: the major surfaces are made reflective for waveguiding, while the minor surfaces are treated to suppress reflections. This local differentiation of properties resolves the contradiction by making each area perform its optimal function.

Inventive Principle:

Principle #3Local quality

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Effectively reduces sunlight and stray light reflections, enhancing image quality and visibility in display systems, particularly in automotive head-up displays, by expanding the viewing area and reducing glare.

Implementation Method 1

a waveguide with parallel reflective surfaces for internal reflection and waveguiding

Methodology Applied

Scientific EffectInternal reflection: Reflection

Implementation Method 2

The louvre structure comprises an array of louvres arranged to supress reflections of sunlight received on an optical path to the first major surface

Methodology Applied

Scientific EffectLight blocking and scattering: Scattering

Implementation Method 3

At least one edge/edge face of the optical component is arranged to suppress specular reflection of light incident thereon

Methodology Applied

Scientific EffectSpecular reflection suppression: Reflection

Implementation Method 4

A light control layer is disposed over the first major surface of the optical component. The light control layer comprises a louvre structure

Methodology Applied

Scientific EffectLight direction control: Reflection

Data Source

PatentUS20260079340A1Display System and Light Control Element Therefor

Publication Date: 2026.03.19 ENVISICS LTD

AI summary

A display system and a waveguide pupil expander are described. The display system comprises an optical component having first and second major surfaces and one or more minor surfaces each defining an edge face of the optical component. One or more of the first and second major surfaces of the optical component are reflective. A light control layer is disposed over the first major surface of the optical component. The light control layer comprises a louvre structure comprising an array of louvres arranged to suppress reflections of sunlight received on an optical path to the first major surface. At least one edge face of the optical component is arranged to suppress specular reflection of light incident thereon. In embodiments, the optical component is a waveguide pupil expander.