LED Superstrate Wavelength Conversion for Far-Field Color
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Solution Overview
Problem
Conventional LED arrays face issues with color quality, especially in the far field, due to varying light output profiles of individual LEDs, leading to undesirable color tone at wide viewing angles and increased costs, particularly as some colors like red are more expensive to produce.
Innovation Solution
The integration of a light-transmissive layer with wavelength-conversion and color-filtering materials, along with an opaque encapsulant, allows for the production of multi-color LED devices that can alter the spectrum of less expensive LEDs like blue and green to produce colors such as red, reducing pixilation and the 'screen door effect' by spreading light uniformly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional LED arrays use individual red, green, and blue LEDs mounted on a PCB, then color output is achieved, but manufacturing cost increases particularly for red LEDs and color quality deteriorates in the far field at wide viewing angles
Solution Approach 1:
The patent replaces expensive red LEDs with inexpensive blue LEDs combined with a phosphor conversion layer. The blue LEDs excite the phosphor material which then emits red light, achieving the same color output at lower cost. This substitution directly addresses the technical contradiction by using cheaper components while maintaining color quality through optical conversion rather than relying on expensive red LED chips.
Solution Approach 2:
The patent employs a composite structure combining blue LEDs with phosphor materials (such as red, green, and blue phosphors in various configurations) to create the desired color output. This composite approach allows the system to leverage the advantages of blue LEDs (lower cost, better far-field performance) while using phosphor conversion to achieve the required color spectrum, thereby resolving the contradiction between manufacturing cost and color quality consistency.
2Adaptability or versatility
If individual LEDs with different light output profiles are used in an array, then color variety is achieved, but far field color quality deteriorates at wide viewing angles due to varying light cones
Solution Approach 1:
The patent changes the optical parameters of the LED system by introducing phosphor conversion layers with specific emission characteristics. Instead of relying on the inherent wide light cones of individual colored LEDs, the system uses phosphor materials with controlled emission profiles that maintain consistent color output across wide viewing angles. This parameter change in the light emission mechanism resolves the contradiction between color variety and far-field color consistency.
Solution Approach 2:
The phosphor layer acts as an intermediary between the blue LED light source and the final color output. Rather than using individual red, green, and blue LEDs that each have problematic light output profiles, the patent uses phosphor materials to convert blue light into the desired color spectrum. This intermediary approach maintains color variety while achieving consistent far-field performance, as the phosphor emission is less directional than direct LED emission.
3Manufacturing precision
If more expensive red LEDs are used to achieve accurate color output, then color quality improves, but manufacturing cost increases
Solution Approach 1:
The patent directly applies this principle by substituting expensive red LEDs with inexpensive blue LEDs combined with phosphor conversion. The blue LEDs serve as a cost-effective alternative that, when combined with appropriate phosphor materials, can produce red light output with comparable accuracy to traditional red LEDs, thereby achieving color accuracy without the high manufacturing cost.
Solution Approach 2:
The patent replaces the mechanical/electronic system of individual red LED chips with an optical conversion system using blue LEDs and phosphor materials. This substitution changes the fundamental mechanism from direct red light emission to blue light excitation of phosphor, achieving the same functional result (red color output) through a different physical mechanism that is more cost-effective.
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-quality LED device with improved far-field color consistency and reduced pixilation, enhancing viewing angles and contrast while streamlining manufacturing by replacing expensive LEDs with more affordable alternatives.
Implementation Method 1
one or more regions of a wavelength-conversion material disposed in at least a portion of a first side of the light-transmissive layer
Implementation Method 2
one or more regions of a color-filtering material disposed on at least one side of the light-transmissive layer
Data Source
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.