Front-lit Illumination Module Using Polarized Lightguide
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Solution Overview
Problem
Achieving high efficiency, brightness, and uniformity in front-lit illumination lightguides for virtual and augmented reality applications remains a challenge, particularly in maintaining these performance attributes without increasing the form factor of the illumination module.
Innovation Solution
The implementation of a front-lit illumination module with a polarized lightguide, coupled with a microLED array and dual source configuration, along with polarization-selective components such as a polarization-selective diffuser and polarization recycling capabilities, to optimize light distribution and coupling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a front-lit illumination lightguide is used for VR/AR displays, then the display can be compact and lightweight, but achieving high efficiency, brightness, and uniformity becomes difficult
Solution Approach 1:
The illumination system is segmented into multiple independent microLED sources arranged in an array, with each microLED contributing to the overall illumination. This segmentation allows for better control of light distribution and improved uniformity across the display while maintaining a compact form factor.
Solution Approach 2:
The patent employs polarization-selective components including a polarization-selective diffuser and polarization recycling elements that create different optical paths for different polarization states of light. This local quality differentiation optimizes light coupling efficiency and brightness distribution specifically within the constrained front-lit architecture.
2Device complexity
If conventional illumination sources are used, then the design is simpler, but efficiency and brightness performance are insufficient
Solution Approach 1:
The patent changes the polarization state parameter of light through polarization-selective components. By controlling and manipulating the polarization parameters of light from microLED sources, the system achieves significantly improved coupling efficiency into the lightguide, transforming an otherwise inefficient conventional design into a high-performance illumination system.
Solution Approach 2:
The illumination module combines multiple materials and components with different optical properties: microLEDs for light generation, polarization-selective diffusers for light redistribution, and polarization recycling elements for efficiency enhancement. This composite approach integrates various functional materials to achieve superior illumination efficiency while maintaining design feasibility.
3Productivity
If polarization-selective components are added to optimize light distribution, then efficiency and brightness improve, but device complexity increases
Solution Approach 1:
The patent merges multiple functions into integrated components: the polarization-selective diffuser simultaneously performs light diffusion and polarization selection, while polarization recycling elements combine reflection and polarization filtering in a single component structure. This merging reduces the number of discrete components and simplifies the overall device architecture despite the advanced optical functionality.
Solution Approach 2:
The polarization-selective components serve multiple functions within the illumination system: they control light distribution uniformity, optimize coupling efficiency into the lightguide, manage polarization states for enhanced brightness, and enable compact integration of the illumination module. This multi-functionality justifies the added component complexity by delivering multiple performance benefits simultaneously.
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 enhances the efficiency, brightness, and uniformity of the illumination, effectively addressing the challenges of achieving commercially relevant performance in front-lit illumination lightguides while maintaining a compact form factor.
Implementation Method 1
the lightguide being configured to transmit light of a first polarization state and reflect light of a second polarization state orthogonal to the first polarization state
Implementation Method 2
a lightguide optically coupled via coupling optics to the plurality of light sources and adapted to direct the illuminating light to the LCoS panel
Implementation Method 3
a plurality of light sources configured to generate illuminating light
Data Source
AI summary
An illumination module includes a LCoS panel, a plurality of light sources configured to generate illuminating light, and a lightguide optically coupled via coupling optics to the plurality of light sources and adapted to direct the illuminating light to the LCoS panel, the lightguide being configured to transmit light of a first polarization state and reflect light of a second polarization state orthogonal to the first polarization state. The plurality of light sources may include a microLED array.