Multi-Waveguide LED Illumination Panels for Lower Optical Loss
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Solution Overview
Problem
Conventional edge-lit illumination systems face challenges in efficiently coupling light into planar light guides, leading to optical losses and suboptimal performance, particularly when guiding light over large areas.
Innovation Solution
A stepped light guide illumination system featuring a first sheet with attached smaller-area sheets, light extraction features, and light sources optically coupled to the edges of these sheets, allowing for light input through the broad-area surface and utilizing reflective layers to enhance light distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If edge-lit illumination systems are used to illuminate large-area light guides, then the light guide can cover a large area, but light coupling efficiency decreases and optical losses increase
Solution Approach 1:
The patent inverts the conventional edge-lit illumination approach by implementing face-lit illumination instead. Light sources are positioned at the broad-area surface of the light guide rather than at the edges, fundamentally changing the illumination geometry to improve light coupling efficiency and reduce optical losses across large areas
Solution Approach 2:
The patent transitions from one-dimensional edge illumination to two-dimensional face illumination. By distributing light sources across the broad-area surface rather than confining them to edges, the system achieves better light distribution and coupling efficiency across the entire light guide area
2Area of stationary object
If light is guided over long distances from input edges, then large-area illumination is achieved, but optical losses increase due to material absorption and scattering
Solution Approach 1:
The patent segments the illumination approach by using multiple light sources distributed across the broad-area surface rather than relying on a single edge input. This segmentation allows light to be introduced at multiple points, reducing the distance each photon must travel and minimizing cumulative optical losses
Solution Approach 2:
The patent introduces optical coupling elements as intermediaries between light sources and the light guide. These coupling elements, positioned at the broad-area surface, facilitate more efficient light transfer into the guide compared to direct edge coupling, reducing losses over long guidance distances
3Device complexity
If conventional edge-lit systems are used, then simple structure is maintained, but light coupling efficiency into the light guide is insufficient
Solution Approach 1:
The patent employs optical coupling elements as intermediaries to bridge the light source and light guide. These elements, which may include lenses or prisms positioned at the broad-area surface, enhance the coupling efficiency by matching optical impedances and directing light more effectively into the guide, overcoming the limitations of direct edge coupling
Solution Approach 2:
The patent changes the geometric parameters of illumination by transitioning from edge-based to face-based lighting. This parameter change fundamentally alters the light entry geometry, enabling superior coupling efficiency while maintaining practical system complexity through standardized optical components
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 system improves light coupling efficiency, reduces energy waste, and enhances light output uniformity across large areas by leveraging face-lit waveguide principles and reflective surfaces.
Implementation Method 1
guiding light long distances from light input edges is associated with optical losses in the light guide material
Implementation Method 2
a first plurality of light extraction features formed in a surface of the first sheet, a second plurality of light extraction features formed in a surface of the second sheet
Data Source
AI summary
A multi-waveguide illumination panel has a base sheet with a front surface and an opposing back surface. A plurality of planar optical waveguides is attached to the back surface at distinct locations. Each planar optical waveguide is optically coupled at an edge to a LED source. Light extraction structures are formed in or on a surface of each planar optical waveguide and configured to emit light towards the base sheet. The light extraction structures associated with a first planar optical waveguide define a first two-dimensional pattern, and the light extraction structures associated with a second planar optical waveguide define a second two-dimensional pattern different from the first. The LED sources may be individually controllable. Optional elements include reflective layers covering back surfaces of the waveguides, diffusive layers covering front surfaces of the waveguides, opaque light control layers positioned near the LED sources, and an image print on the base sheet.