Transparent Sparse MicroLED Array for Unobstructed Eye Tracking
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Solution Overview
Problem
Current technologies for integrating light sources with eyewear do not effectively allow for transparent infrared microLED illuminators that enable users to view real or virtual scenes without obstruction, particularly in augmented, virtual, and mixed-reality applications.
Innovation Solution
The integration of transparent microLED light sources with sparse arrays of microLEDs and thin conductive paths on a flexible transparent substrate, allowing light to pass through while providing power and control signals, enabling infrared eye motion tracking and optional visible light displays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If microLEDs and conductive paths are integrated into eyewear for illumination and display, then functional capabilities (eye tracking, visible display) are improved, but transparency and unobstructed viewing are degraded
Solution Approach 1:
The patent employs ultra-thin flexible transparent substrates (e.g., polyimide films) as the base for mounting microLEDs and conductive paths. These thin films minimize optical obstruction while providing mechanical support, enabling the array to maintain high transparency in the visible spectrum while supporting functional components for illumination and display
Solution Approach 2:
The patent applies different transparency characteristics to different regions and components: the substrate and adhesive layers are optimized for visible light transparency, while the microLEDs and conductive paths are positioned and dimensioned to be invisible or minimally obstructive in the visible spectrum but functional in infrared and displayed wavelengths
2Illumination intensity
If microLEDs are made small and spaced apart to improve transparency, then transparency is improved, but manufacturing precision and alignment difficulty worsen
Solution Approach 1:
The patent divides the microLED array into modular units or strings that can be manufactured and tested independently before final assembly. This segmentation allows for standardized manufacturing processes with built-in alignment features, reducing the overall manufacturing complexity while maintaining the sparse, transparent configuration
Solution Approach 2:
The patent introduces intermediate alignment structures such as transparent conductive adhesive layers with patterned conductive traces that serve as both electrical connections and alignment references. These intermediaries provide registration marks and mechanical guidance that simplify the placement of individual microLEDs while maintaining precise positioning in the final assembly
3Illumination intensity
If conductive paths are made thin to improve transparency, then transparency is improved, but electrical conductivity and signal integrity worsen
Solution Approach 1:
The patent employs composite conductive structures combining multiple materials with complementary properties: transparent conductive oxides (such as ITO or IZO) provide visible light transparency with electrical conductivity, while metallic traces or particles embedded in the adhesive layer provide enhanced conductivity. This composite approach achieves both transparency and reliable electrical connections
Solution Approach 2:
The patent uses transparent conductive adhesive layers that serve dual functions: as the bonding medium for mounting microLEDs and as the conductive path for electrical connections. This eliminates the need for separate opaque conductive traces, maintaining transparency while providing reliable electrical pathways through the adhesive material itself
4Illumination intensity
If sparse array configuration is used to improve transparency, then transparency is improved, but the quantity of light emitting elements and display resolution worsen
Solution Approach 1:
The patent utilizes infrared-emitting microLEDs that are invisible to the human eye for eye tracking and illumination functions, allowing dense packing of functional elements without compromising visible transparency. For visible display, the system employs high-brightness microLEDs with optimized spacing and size parameters to achieve sufficient resolution while maintaining the transparent appearance
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
Enables transparent microLED light sources that allow unobstructed viewing of scenes while providing infrared eye tracking and visible information, suitable for AR, VR, and MR systems without noticeable microLEDs or conductive paths.
Implementation Method 1
positioning a transparent adhesive between the flexible transparent material and a transparent substrate, and bonding, by the transparent adhesive, the flexible transparent material to the transparent substrate
Implementation Method 2
Infrared light emitting microLEDs... may be arranged to detect information about a user, for example as part of a system that tracks a user's eye motion
Implementation Method 3
LEDs may be combined with one or more wavelength converting materials (generally referred to herein as 'phosphors') that absorb light emitted by the LED and in response emit light of a longer wavelength
Data Source
AI summary
A method of forming one or more transparent microLED light sources comprises preparing or obtaining a flexible transparent sheet on which are disposed a plurality of inorganic microLEDs and conductive paths configured to power the plurality of inorganic microLEDs, positioning a solid transparent sheet of adhesive between the flexible transparent sheet and a transparent substrate, and bonding the transparent sheet of adhesive to the flexible transparent sheet and to the transparent substrate to form a laminated structure. The conductive paths and the microLEDs are arranged to form at least one sparse microLED array.