Light Steering Backlight With Directional Extraction Features
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Solution Overview
Problem
Existing flat illuminators for backlighting and lighting applications face challenges in efficiently directing light to multiple viewers and adjusting light direction electronically, with prior solutions limited in creating multiple viewing zones without increasing lightguide thickness or extending beyond normal boundaries.
Innovation Solution
The solution involves an array of independently controllable light sources positioned along one edge of a lightguide with novel light extraction features that allow light to be directed in different zones by varying the shape and orientation of extraction features, enabling multiple, preferably three or more, switchable viewing zones without significant thickness increase, using a reflector sheet and optionally a turning film for enhanced control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If light extraction features are added to direct light in different directions, then multiple viewing zones can be created, but the lightguide thickness increases
Solution Approach 1:
The patent applies local quality by varying the shape and orientation of light extraction features at different locations on the lightguide surface. Each region has extraction features specifically configured to direct light toward particular viewing zones, enabling multiple viewing directions without increasing overall lightguide thickness. The extraction features include regions with different geometries (e.g., first regions for first viewing zones, second regions for second viewing zones) to achieve directional control locally.
2Adaptability or versatility
If more light extraction features are implemented to create multiple viewing zones, then light can be directed to multiple viewers, but the device complexity increases
Solution Approach 1:
The patent implements universality by designing a single lightguide structure that performs multiple functions: it guides light from a single light source and simultaneously directs it to multiple different viewing zones through strategically positioned extraction features. The same lightguide and extraction feature structure enables switching between different viewing modes (single viewer, multiple viewers, different directions) without requiring separate optical components for each function.
Solution Approach 2:
The patent applies segmentation by dividing the light extraction surface into distinct regions, where each region contains extraction features configured for specific viewing zones. This segmentation allows independent optimization of each region's light extraction characteristics while maintaining a unified lightguide structure, reducing overall complexity compared to using separate optical elements for each viewing zone.
3Use of energy by moving object
If light is directed to specific zones only, then power consumption is reduced, but illumination uniformity becomes harder to maintain
Solution Approach 1:
The patent applies parameter changes by varying the geometric parameters of light extraction features (such as size, shape, orientation, and density) across different regions of the lightguide. These parameter variations are specifically designed to compensate for non-uniform light distribution when directing light to specific zones, ensuring that each viewing zone receives appropriate illumination levels while maintaining overall brightness uniformity across the display surface.
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
This approach enhances light efficiency by directing light to specific zones, reducing power consumption, and maintaining uniform brightness and appearance across zones, suitable for various display modes including autostereoscopic and directional displays, while maintaining a thin lightguide profile.
Implementation Method 1
light extraction features that extract light from a lightguide
Implementation Method 2
light extraction features that extract light from a lightguide
Implementation Method 3
optionally a turning film for enhanced control
Data Source
AI summary
An illumination system comprises a lightguide (12) having a plurality of light extraction features (LEFs); and a plurality of independently controllable light sources (11a, 11b, 11c). The LEFs have a preferred direction, with light that is incident on an LEF along the preferred direction of the LEF being extracted from the lightguide generally parallel to a reference plane, and light that is incident on an LEF not along the preferred direction of the LEF being extracted from the lightguide at an extraction angle to the reference plane, the extraction angle being related by a response function to an incidence angle between the light propagation direction and the preferred direction of LEF. The shape of the LEFs varies with distance from a reference point or respective reference point so that the response function becomes larger with increasing distance of the LEFs from the reference point.