Film-Based Lightguide With Folded Coupling Stack
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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 limitations in coupling sufficient light flux into thinner lightguides, leading to design constraints and production inefficiencies, particularly with thick light sources and large input coupling optics.
Innovation Solution
A light emitting device featuring a film-based lightguide with a thickness not exceeding 0.5 millimeters, utilizing an array of coupling lightguides folded to form a stack for light input, where a light source directs light into the lightguide region through total internal reflection, and light extraction features are used to exit the lightguide, with a low contact area cover to manage light output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If conventional thick lightguides (2mm and larger) are used, then sufficient light flux can be coupled in, but the device thickness and volume increase
Solution Approach 1:
The lightguide is segmented into multiple thin lightguide layers (each less than 0.5mm thick) stacked together with coupling lightguides in between. This segmentation allows each layer to be thin enough for compactness while the stack collectively provides sufficient light flux coupling area, resolving the contradiction between thinness and light coupling efficiency
Solution Approach 2:
The invention transitions from a single thick lightguide (one-dimensional thickness) to a multi-layer stacked structure (three-dimensional arrangement). By stacking multiple thin lightguide layers with coupling lightguides, the system achieves both thin individual layers and sufficient total light coupling area through the vertical stacking dimension
2Strength
If rigid frames are used to house light emitting devices, then structural support is provided, but design flexibility and component adaptability are reduced
Solution Approach 1:
The invention replaces rigid frames with flexible thin film lightguides that can be laminated onto various surfaces including curved surfaces. This allows the light emitting device to adapt to different form factors and design configurations while maintaining structural integrity through the film structure itself rather than requiring external rigid framing
3Reliability
If large input coupling optics are used, then sufficient light can be directed into the lightguide, but device volume increases
Solution Approach 1:
The coupling system is segmented into multiple coupling lightguides distributed across the stack, each with small input edges. This segmentation eliminates the need for large monolithic coupling optics, as the collective input area of multiple small coupling edges provides sufficient light coupling without requiring large-volume optical components
Solution Approach 2:
The invention moves light coupling from a planar arrangement (requiring large lateral area for coupling optics) to a three-dimensional stacked arrangement. By stacking multiple coupling lightguides vertically, the system achieves sufficient total coupling area without increasing the lateral footprint, thereby reducing overall device volume
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 solution enables thinner, lighter, and more scalable light emitting devices with improved design flexibility and production efficiency, allowing for effective light distribution and reduced volume, suitable for larger display sizes.
Implementation Method 1
light from each coupling lightguide combining with light from one or more other coupling lightguides of the array of coupling lightguides and totally internally reflecting within the lightguide region
Data Source
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AI summary
A light emitting device includes a film lightguide. The lightguide includes a lightguide region and an array of coupling lightguides continuous with the lightguide region, each terminating in a bounding edge and folded such that the bounding edges define a light input surface. A light source emits light into the light input surface. Light propagates within each coupling lightguide to the lightguide region, with light from each coupling lightguide combining with light from one or more other coupling lightguides and totally internally reflecting within the lightguide region. One or more light extraction features frustrate the totally internally reflected light such that light exits the lightguide in a light emitting region. Surface relief features on a surface of a low contact area cover are adjacent to a region of the lightguide with one or more of the surface relief features contacting the lightguide. A method of producing a device is disclosed.