Optical Combiners With Recycle Optics to Recover Wasted Display Light
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Solution Overview
Problem
Wearable heads-up displays face inefficiencies in redirection optics, leading to wasted power consumption and non-uniform displays due to trade-offs between optic efficiency and display uniformity.
Innovation Solution
Incorporation of recycle optics within optical combiners to redirect unused display light back into the system, combined with expander and uniformization optics to enhance efficiency and uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If redirection optics are used to redirect display light from the light engine to the user's eye, then the display can be formed visible to the user, but a significant portion of the display light is not efficiently utilized, leading to increased power consumption
Solution Approach 1:
The patent implements feedback by redirecting unused display light that passes through the outcoupler optic back toward the outcoupler region through recycle optics. This creates a closed-loop system where light that would otherwise be wasted is fed back into the optical path, allowing it to be outcoupled and contribute to the display image, thereby improving overall light utilization efficiency and reducing power consumption.
Solution Approach 2:
The patent recovers discarded light by capturing display light that passes through the outcoupler optic without being outcoupled. The recycle optics redirect this previously discarded light back into the optical path, allowing it to be utilized for forming the display image. This recovery process eliminates waste and improves system efficiency.
2Manufacturing precision
If redirection optics are used to redirect display light, then the display can be formed visible to the user, but the display appears non-uniform due to trade-off between optic efficiency and display uniformity
Solution Approach 1:
The patent applies local quality by implementing uniformization optics specifically in regions where non-uniformity occurs. The uniformization optics are strategically positioned to address local brightness variations and hotspots in the display, improving overall uniformity without requiring a complete redesign of the entire optical system. This localized approach maintains high optic efficiency while correcting uniformity issues.
Solution Approach 2:
The patent changes optical parameters by introducing uniformization optics that modify the spatial distribution of light intensity. These optics adjust parameters such as beam uniformity, hotspot distribution, and intensity profiles to achieve a more uniform display appearance while maintaining the high efficiency of the redirection optics.
3Illumination intensity
If a light engine outputs extra bright light to compensate for inefficient redirection optics, then the display can be sufficiently bright, but the light engine requires larger size and is subjected to more stringent safety concerns
Solution Approach 1:
The patent ensures continuity of useful action by keeping display light in circulation through the recycle optics. Instead of allowing light to be wasted after a single pass through the outcoupler, the system continuously redirects unused light back into the optical path, maximizing the utilization of each photon generated by the light engine. This reduces the total light output requirement and allows for a smaller, safer light engine.
Solution Approach 2:
The patent recovers light that would otherwise be discarded, reducing the total light output requirement from the light engine. By capturing and redirecting unused light back into the display path, the system achieves sufficient display brightness with a smaller light engine that operates at lower power levels, thereby reducing safety concerns.
4Use of energy by moving object
If high efficiency redirection optics are used, then power consumption is reduced, but display uniformity deteriorates with non-uniform appearance and hotspots
Solution Approach 1:
The patent applies local quality by introducing uniformization optics that specifically address uniformity issues in problem areas without affecting the overall high efficiency of the redirection optics. These localized corrections target hotspots and non-uniform regions, allowing the system to maintain high power efficiency while achieving acceptable display uniformity.
Solution Approach 2:
The patent changes local optical parameters through uniformization optics that adjust intensity distribution, beam uniformity, and hotspot characteristics. These parameter adjustments are made in specific regions where uniformity problems occur, allowing the system to maintain high overall efficiency while achieving acceptable local uniformity.
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
Improves power efficiency by reducing wasted light and enhances display uniformity, ensuring a larger eyebox and consistent visibility across various eye positions.
Implementation Method 1
a recycle optic positioned to receive display light travelling in a volume of the optical combiner away from the outcoupler region and redirect the received display light back towards the outcoupler region
Implementation Method 2
an expander optic positioned to receive display light from the incoupler optic and redirect the received display light towards the outcoupler region
Implementation Method 3
a uniformization optic positioned to receive display light from the incoupler optic and redirect the received display light towards the outcoupler region
Data Source
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AI summary
Systems, devices, and methods for directing display light employ one or more optical combiners that include recycle optics such as diffraction gratings, which can receive wasted display light travelling in a volume of an optical combiner, and redirect the wasted display light towards other optics so the wasted display light may be effectively used to produce a display. The optical combiners may also include a uniformization optic which can redistribute non-uniform display light, to produce a more uniform display, which in turn enables higher efficiency optics to be used.