Micro-LED Color Display With Reflective Optics and Wavelength Conversion
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Solution Overview
Problem
Current high-resolution display technologies face limitations in achieving thin, flexible, and high-efficiency color displays due to the size and tolerance issues of packaged LEDs, which restrict pixel pitch and require complex drive electronics, and existing solutions like LCDs and OLEDs have inefficiencies in color production and viewing angle independence.
Innovation Solution
A color display apparatus comprising unpackaged micro-LEDs, reflective optical elements, and wavelength conversion elements, where the micro-LEDs emit light that is redirected towards wavelength conversion elements to produce different color wavelengths, allowing for high-resolution, flexible, and low-power displays with reduced cross-talk and independent color output across viewing angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If packaged LEDs are used to form display arrays, then the display can be assembled using standard PCB assembly techniques, but the pixel pitch cannot be reduced below about 1 mm due to component size and assembly tolerance limitations
Solution Approach 1:
The invention segments the LED into unpackaged micro-LED dies extracted directly from a monolithic wafer, eliminating the packaged LED structure. This segmentation allows individual micro-LEDs to be positioned with sub-5-micrometer precision using wafer-level extraction and transfer techniques, enabling pixel pitches below 1 mm while simplifying the overall assembly process by removing lead-frames and plastic packages.
Solution Approach 2:
The invention replaces the mechanical PCB assembly process with a wafer-level micro-LED transfer system. Instead of using standard surface-mount assembly machines with ±30 micrometer accuracy, the patent employs wafer extraction and direct transfer methods that achieve sub-5-micrometer positioning precision, enabling high-resolution displays with pixel pitches below 1 mm.
2Adaptability or versatility
If arrays of packaged LEDs emitting in different wavelength bands are used to provide color pixels, then color display is achieved, but the operating voltage of different color LEDs is different, adding cost and complexity to drive electronics
Solution Approach 1:
The invention uses a single wavelength conversion layer that can convert blue or UV LED light into multiple different wavelengths corresponding to different colors. This universal approach allows one LED type to perform the function of multiple different-colored LEDs, eliminating the need for separate drive electronics for each color and simplifying the overall system while maintaining full color display capability.
Solution Approach 2:
The invention introduces a wavelength conversion layer as an intermediary between the blue/UV LED and the final displayed color. This conversion layer mediates the light wavelength transformation, allowing a single LED type to produce multiple colors through phosphor or quantum dot materials, thereby eliminating the complexity of driving multiple different-voltage LED types.
3Loss of energy
If wavelength conversion materials are placed close to micro-LEDs to convert light efficiently, then conversion efficiency is high, but the operational temperature of wavelength conversion materials increases, reducing efficiency and lifetime
Solution Approach 1:
The invention separates the wavelength conversion function from the immediate vicinity of the micro-LED by positioning the conversion layer at a distance and using optical elements to redirect light. This spatial separation in another dimension allows efficient light redirection while reducing thermal coupling, thereby maintaining conversion efficiency while lowering the operational temperature of the wavelength conversion materials and extending their lifetime.
4Shape
If thin, flexible display structures are used to achieve flexibility and curved shapes, then the display can be folded and curved, but maintaining high luminance and efficiency becomes more difficult
Solution Approach 1:
The invention replaces traditional mechanical light-guiding structures with micro-LEDs and optical elements that can be integrated onto flexible substrates. The unpackaged micro-LED structure and thin-film optical components enable high luminance output while maintaining flexibility, allowing the display to be bent, folded, or curved without compromising light emission intensity or efficiency.
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 enables high-resolution, flexible, and efficient color displays with low power consumption, high contrast, and increased color gamut, while reducing operational temperature and complexity, and allows for thin, curved, and foldable designs with minimal bezel width.
Implementation Method 1
each of the plurality of wavelength conversion elements is arranged to receive light emitted by one or more LEDs of the plurality of LEDs, convert the received light into light of a different colour wavelength band
Implementation Method 2
each of the plurality of reflective optical elements is arranged to re-direct at least part of the light emitted by one or more LEDs of the plurality of LEDs towards one or more of the plurality of wavelength conversion elements
Data Source
AI summary
A colour micro-LED display apparatus comprises an array of reflective optical elements and an array of micro-LED pixels with a uniform emission colour across the array arranged between the array of reflective optical elements and an output substrate. Light from the micro-LEDs is directed into the reflective optical elements and is incident on scattering regions in the apparatus. Colour converted scattered light is transmitted by the output substrate. A thin and efficient display apparatus may be provided with high spatial and angular colour uniformity and long lifetime.