LED Array Wavelength Conversion for Uniform Color Viewing Angles
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Solution Overview
Problem
Conventional LED arrays face challenges in maintaining consistent color quality across viewing angles due to differing light output profiles of individual LEDs, leading to undesirable color quality and increased costs, particularly with more expensive red LEDs, and suffer from the 'screen door effect' in video displays.
Innovation Solution
The integration of phosphor conversion material and color filtering layers with wavelength-conversion layers allows for the production of multi-color LEDs that replace expensive LEDs with less expensive alternatives, improving far-field color consistency and reducing the 'screen door effect' by spreading light to fill gaps between pixel arrays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional LED arrays use individual LEDs with different light output profiles, then each LED can be optimized for its specific color, but color quality becomes inconsistent across viewing angles
Solution Approach 1:
The patent applies color filtering layers with specific spectral transmission characteristics to modify the light output of LEDs. Each color filter layer (red, green, blue) is designed to transmit its corresponding color while blocking other wavelengths, ensuring consistent color quality across different viewing angles by filtering the broader LED emission spectrum
Solution Approach 2:
The invention combines multiple layers including phosphor conversion material, color filtering layers, and encapsulating layers to create a composite optical system. This multi-layer composite structure integrates wavelength conversion and color filtering functions to achieve uniform color output across viewing angles
2Reliability
If expensive red LEDs are used to achieve accurate color quality, then color accuracy improves, but manufacturing cost increases
Solution Approach 1:
The patent replaces expensive red LEDs with cheaper blue LEDs combined with phosphor conversion material and red color filtering layers. This substitution uses lower-cost components to achieve the same color output, significantly reducing manufacturing costs while maintaining color accuracy
Solution Approach 2:
The invention changes the wavelength parameters by using blue LEDs (shorter wavelength) with phosphor down-conversion to generate red light (longer wavelength). This parameter transformation allows using cheaper blue LED technology instead of expensive red LED technology while achieving identical color output
3Illumination intensity
If LED arrays are used in video screens, then light emission is achieved, but reflected light reduces contrast and image sharpness
Solution Approach 1:
The patent employs color filtering layers that not only select specific wavelengths for accurate color emission but also reduce overall reflected light by absorbing non-transmitted wavelengths. This selective filtering minimizes harmful reflections while maintaining desired light emission for video display applications
4Illumination intensity
If individual LEDs have wider light output cones, then light intensity increases, but color quality deteriorates at the extents of the viewing region
Solution Approach 1:
The patent uses color filtering layers to restrict the spectral content of the wider light output cones, ensuring that even though the angular spread is wide, the color quality remains consistent by transmitting only the desired wavelength ranges for each color channel
Solution Approach 2:
The invention applies different color filtering characteristics to different color channels (red, green, blue) to compensate for their individually different light output profiles. Each color filter layer is optimized for its specific wavelength range to ensure uniform color quality across the entire viewing region
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 approach results in a lower-cost, high-efficiency LED device with improved far-field color consistency and reduced pixilation, enhancing viewing angle and contrast while maintaining individual color quality.
Implementation Method 1
The integration of phosphor conversion material and color filtering layers with wavelength-conversion layers allows for the production of multi-color LEDs
Implementation Method 2
The integration of phosphor conversion material and color filtering layers with wavelength-conversion layers allows for the production of multi-color LEDs
Data Source
Figure 1~2A
Figure 2B
Figure 3A~3B
AI summary
Light emitting diode (LED) devices and systems include a superstrate (e.g., a light-transmissive layer), at least one region of wavelength- conversion material in the light-transmissive layer, and LEDs attached to the superstrate at the location of the wavelength-conversion material. An encapsulant layer is formed over and/or around the LEDs with an opaque or clear material. Additional color filter layers are optionally applied to the light- transmissive layer. A method for producing LED devices and systems includes providing a superstrate with a wavelength-conversion material region formed therein, attaching LEDs to the superstrate at the die-attach layer, forming conductive surfaces on a side of the LED opposite the die- attach layer, dispensing an encapsulant layer to at least partially encapsulate the LEDs, and forming one or more electrical traces to electrically interconnect the conductive surfaces of at least some of the LEDs with each other.