Optically Redundant Light Emitting Device Using Stacked Bent Lightguides
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Solution Overview
Problem
Conventional light emitting devices, such as displays and backlights, face challenges in reducing thickness and volume due to the limitations of coupling light flux into thinner lightguides, leading to design constraints and production inefficiencies, particularly with thick lightguides and large light sources.
Innovation Solution
An optically redundant light emitting device is developed, featuring a light transmitting film with an array of bent coupling lightguides that receive light from multiple light sources, ensuring uniform luminance and color distribution through total internal reflection, allowing for thinner and more flexible designs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If thick lightguides (2mm and larger) are used to receive light from the edge, then the light flux coupling is sufficient, but the device thickness and volume remain large
Solution Approach 1:
The lightguide is divided into multiple thinner lightguide sections (e.g., three 0.2mm lightguides instead of one 2mm lightguide). Each thin lightguide section is optically coupled to receive light from light sources, achieving sufficient light flux coupling while dramatically reducing the overall device thickness and volume.
Solution Approach 2:
Multiple thin lightguide sections are stacked and optically coupled in a nested configuration, where light from multiple light sources is coupled into multiple thin lightguides that are positioned close together. This nested arrangement of light sources and thin lightguides enables efficient light flux coupling within a compact volume.
2Volume of moving object
If thin lightguides are used to reduce device thickness, then the device becomes thinner, but the ability to couple sufficient light flux into the lightguide is limited
Solution Approach 1:
Multiple thin lightguides are optically merged/combined to function as a unified light distribution system. By optically coupling multiple light sources to multiple thin lightguides and positioning them in close proximity, the system achieves sufficient total light flux coupling while maintaining thin individual lightguide profiles, thus reducing device thickness.
3Illumination intensity
If large light sources and large input coupling optics are used, then sufficient light flux is coupled into the lightguide, but the system size becomes large
Solution Approach 1:
The single large light source and large coupling optic system is segmented into multiple smaller light sources (e.g., three LED arrays) with corresponding thin lightguides. Each light source-lightguide pair is compact, and when arranged in a stacked configuration, the total system area is significantly reduced compared to a single large system, while achieving sufficient light flux coupling.
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 achieves VESA 9-spot sampled spatial luminance uniformity greater than 70% and color non-uniformity less than 0.2, enabling thinner, lighter, and more scalable light emitting devices with improved design flexibility and production efficiency.
Implementation Method 1
The light travels by total internal reflection through the light transmitting film to the light emitting area
Data Source
AI summary
An optically redundant light emitting device includes a light transmitting film comprising an array of coupling lightguides extending from a light emitting area defined within the light transmitting film. Each coupling lightguide is bent to form a stacked array of coupling lightguides. A first group of light sources comprising at least one light source is positioned to emit light into the stacked array of coupling lightguides, and a second group of light sources comprising at least one light source is positioned to emit light into the stacked array of coupling lightguides. A first optical path of the light emitted from the first group of light sources overlaps with a second optical path of the light from the second group of light sources in each coupling lightguide.