Geometrical Waveguide Illuminator for Head-Mounted Displays
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Solution Overview
Problem
Head-mounted display devices face challenges with bulky, unbalanced, and heavy components, particularly in compact and efficient light sources and illuminators for reflective or transmissive display panels, which affect user comfort and performance.
Innovation Solution
A geometrical waveguide illuminator using a thin slab of transparent material with slanted partial reflectors for out-coupling light, allowing for compact, non-color-selective, and efficient illumination of display panels, including reflective and transmissive pixel arrays, with optional diffusers and polarization-selective reflectors for enhanced performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional light sources and illuminators are used in head-mounted display devices, then sufficient illumination can be provided, but the device becomes bulky, unbalanced, and heavy
Solution Approach 1:
The patent extracts the illumination function from a separate bulky light source and integrates it into the waveguide structure itself. The waveguide acts as both the light transmission medium and the illuminator, with light coupling elements directly embedded in the waveguide to provide illumination without requiring external heavy components
Solution Approach 2:
The illumination system is nested within the waveguide structure. Light coupling elements are embedded inside or on the waveguide, and the illumination function is nested within the existing light transmission path, eliminating the need for separate external illuminators
2Illumination intensity
If conventional illuminators are used, then adequate light can be provided, but the device complexity increases
Solution Approach 1:
The patent merges the waveguide and illuminator into a single integrated component. The waveguide structure itself performs the illumination function through embedded light coupling elements, eliminating the need for separate illuminator assemblies and reducing overall device complexity
Solution Approach 2:
The waveguide serves multiple functions simultaneously: it transmits light from the display and provides illumination through its embedded light coupling elements. This multi-functionality reduces the number of separate components needed in the system
3Illumination intensity
If tight parallelism tolerances are required for illumination, then uniform broad beams can be produced, but manufacturing costs increase
Solution Approach 1:
The patent changes the geometric parameters of the light coupling elements (such as their angle, size, and distribution) to optimize light outcoupling. By carefully designing these parameters, the system achieves uniform broad illumination beams without requiring tight parallelism tolerances, thereby reducing manufacturing costs
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 solution provides a compact, efficient, and cost-effective illuminator that relaxes parallelism tolerances, enabling the production of broad, uniform illuminating beams for both miniature and large display panels, improving user comfort and display performance without degrading image sharpness or increasing manufacturing costs.
Implementation Method 1
propagating a light beam in a lightguide by a series of internal reflections from first and second opposed outer surfaces of the lightguide
Implementation Method 2
portions of the light beam are out-coupled by a plurality of slanted partial bulk reflectors inside the lightguide
Data Source
AI summary
An illuminator for illuminating a display panel includes a lightguide with an array of buried slanted bulk reflectors that out-couple portions of the light beam propagating in the lightguide through one of the lightguide surfaces. Polarization beam-splitting slanted surfaces may be used to provide polarized output. Such an illuminator may be used with a reflective display panel operating by polarization. The beam-splitting slanted surfaces operate as a polarizer, providing polarized illuminating light. The light reflected by the reflective panel may propagate back through the illuminator, and the polarization beam-splitting slanted surfaces may operate also as analyzer.