Folded Film Lightguide for Reflective Spatial Light Modulator
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional light emitting devices with edge-lit configurations using rigid lightguides are limited in reducing thickness and volume, restricting design flexibility and production methods due to difficulties in coupling sufficient light flux into thinner lightguides, which is challenging for larger display sizes and requires thick frames and large input coupling optics.
Innovation Solution
A light emitting device comprising a reflective spatial light modulator and a frontlight with a light mixing region between the light emitting region and an array of coupling lightguides, where the light source is positioned behind the electrical display connector, and the lightguide is folded to form a stack defining a light input surface, allowing light to enter and propagate through the lightguide via total internal reflection, with a thickness not exceeding 0.5 millimeters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If rigid lightguides with thickness of 2 mm or larger are used, then sufficient light flux can be coupled into the lightguide, but the thickness and overall volume of the display cannot be reduced
Solution Approach 1:
The lightguide is divided into multiple thin lightguide layers (each less than 0.5 mm thick) stacked together. This segmentation allows each layer to be sufficiently thin for reduced overall thickness while maintaining light coupling capability through the array structure. The multiple layers work collectively to transport sufficient light flux.
Solution Approach 2:
The patent transitions from a single thick lightguide (one-dimensional thickness) to multiple thin stacked lightguide layers (three-dimensional stacking). This dimensional change from planar to volumetric arrangement enables thinness in the display plane while maintaining light transport capability through the stack depth.
2Length of moving object
If thin lightguides with thickness less than 0.5 mm are used, then the thickness and volume of the display can be reduced, but it becomes difficult to couple sufficient light flux into the lightguide
Solution Approach 1:
Multiple thin lightguide layers are merged into a stacked array structure where each layer contributes to the total light flux transport. The combined effect of all layers in the stack provides sufficient light flux capability while maintaining thin individual layer thickness for reduced display profile.
Solution Approach 2:
The stacked lightguide array serves multiple functions: each thin layer provides light transport while the collective stack provides sufficient total light flux, alignment registration is achieved through integrated features, and the structure enables both thinness and brightness simultaneously through the multi-layer configuration.
3Quantity of substance
If large light sources and large input coupling optics are used, then sufficient light flux can be achieved, but the device volume increases and design flexibility is restricted
Solution Approach 1:
The patent uses flexible thin-film lightguide layers instead of rigid bulk lightguides. This enables thin-film fabrication techniques and flexible form factors, reducing device volume while maintaining light flux through the stacked array configuration. The flexible nature allows for compact integration with the display.
4Reliability
If one lightguide per pixel (fiber optic based systems) is used, then light coupling can be achieved, but the volume is large and alignment tolerances are low
Solution Approach 1:
The lightguide structure uses nested alignment features where registration marks and alignment structures are integrated within and between layers. This nested approach provides robust alignment tolerance by incorporating multiple levels of alignment guidance within the stacked configuration.
Solution Approach 2:
The stacked lightguide array uses replicated structures across multiple layers with consistent geometric patterns and alignment features. This copying approach across layers simplifies manufacturing and maintains alignment tolerance by using identical, reproducible structures rather than unique custom 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
This configuration enables thinner and more flexible light emitting devices with improved light distribution and reduced volume, allowing for larger display sizes and increased design flexibility while maintaining efficient light coupling and extraction.
Implementation Method 1
Light from the light source enters into the light input surface and propagates by total internal reflection within each coupling lightguide to the lightguide region
Data Source
AI summary
A display includes a reflective spatial light modulator and a frontlight formed from a film having a light mixing region positioned along the film between a light emitting region and an array of coupling lightguides. In one embodiment, the light mixing region of the film and an electrical display connector are folded behind an active display area of the reflective spatial light modulator such that a light source positioned on the electrical display connector emits light into the array of coupling lightguides. In one embodiment, the light source and the reflective spatial light modulator are electrically driven by electrical connections on the flexible electrical display connector.