Segmented Reflective Layer for Eyeglass Lens Light Guide
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Solution Overview
Problem
The reflective property of the light guide channel in spectacle lenses makes the user stand out when viewing surroundings, creating an optically striking difference from the rest of the lens.
Innovation Solution
A segmented reflective layer with transparent gaps is used, allowing increased transmissivity and reducing the visibility of the light guide channel, along with an angle-selective absorption layer to prevent scattered light, and optionally a second reflective layer with similar gaps for enhanced light guidance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a continuous reflective layer is used in the light guide channel, then light guidance efficiency is improved, but the user stands out clearly from other areas of the spectacle lens when viewing surroundings
Solution Approach 1:
The continuous reflective layer is divided into multiple discrete reflective segments spaced apart from each other. This segmentation allows light to pass through the gaps between segments, reducing the visibility of the light guide channel when viewing through the spectacle lens, while still maintaining sufficient light guidance efficiency through the reflective segments.
Solution Approach 2:
Different regions of the light guide channel are given different reflective properties. The reflective segments provide high reflectivity for light guidance, while the gaps between segments provide transparency for ambient light transmission. This local variation in optical properties resolves the contradiction between light guidance efficiency and visibility reduction.
2Object-affected harmful factors
If transparent gaps are introduced in the reflective layer, then transmissivity of the light guide channel is increased, but light guidance efficiency may be reduced
Solution Approach 1:
Instead of making the entire reflective layer transparent, only partial segments are made transparent while maintaining reflective segments. This partial action allows sufficient ambient light transmission through the gaps while preserving adequate light guidance efficiency through the remaining reflective segments, balancing both requirements.
3Manufacturing precision
If an angle-selective absorption layer is added to prevent scattered light, then image quality is improved, but device complexity increases
Solution Approach 1:
The angle-selective absorption layer serves multiple functions: it absorbs scattered light to improve image quality, and its angular selectivity allows it to differentiate between light paths from the light guide channel versus ambient light. This multi-functionality justifies the added complexity by providing both scattering prevention and selective light transmission.
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
The solution minimizes the visual distinction between the light guide channel and the rest of the spectacle lens, allowing better ambient light transmission and reducing unwanted reflections, enabling the user to perceive their surroundings more naturally while still viewing a virtual image.
Implementation Method 1
a first reflective layer that extends from the coupling section to the decoupling section and on which the light bundles are reflected for guidance up to the decoupling section
Implementation Method 2
an angle-selective absorption layer can be arranged in front of the at least one gap in the first reflective layer, which absorbs light that strikes the absorption layer at an angle from a predetermined first critical angle up to 90° and absorbs light that falls below at an angle of 0° up to a predetermined second limit angle
Data Source
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AI summary
The invention relates to an eyeglass lens for a display device (1), which display device can be placed on the head of a user and produces an image, wherein the eyeglass lens (3) has a front side (18) and a back side (15), an incoupling segment (11) and an outcoupling segment (13) spaced apart from the incoupling segment (11), and a light-conducting channel (12), which is suitable for conducting light bundles (9) of pixels of the produced image, which are coupled into the eyeglass lens (3) via the incoupling segment (11) of the eyeglass lens (3), in the eyeglass lens (3) to the outcoupling segment (13), by means of which the light bundles are coupled out of the eyeglass lens (3), wherein the light-conducting channel (12) has a first reflective layer (21, 22), which extends from the incoupling segment (11) to the outcoupling segment (13) and at which the light bundles (9) are reflected in order to conduct the light bundles to the outcoupling segment (13), wherein the first reflective layer (21, 22) has at least one transparent gap (24, 26).