MicroLED Pixel Layout Using Yellow Emitters for Efficient White Output

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Solution Overview

Problem

MicroLED displays face challenges in achieving efficient white display due to the low external quantum efficiency (EQE) of red microLEDs, which dominates the electrical power consumption and affects the overall display efficiency.

Innovation Solution

Incorporating a fourth microLED that emits light at a visible wavelength proximate the red-green locus, such as yellow or amber, to improve the display efficiency by reducing the contribution of the less efficient red microLEDs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If red microLEDs are used to achieve white display with conventional RGB color balance, then the display can produce white light, but the overall display efficiency is significantly reduced due to the low external quantum efficiency of red microLEDs

Engineering Contradiction:

Improvewhite display efficiencyVSAvoidelectrical power consumption

Core Design Contradiction:

Illumination intensityVSUse of energy by moving object

Solution Approach 1:

The patent changes the color balance parameters from conventional RGB to RGBY by introducing yellow microLEDs with wavelengths of 560-590nm. This parameter change allows the display to achieve the same white point (D65) while significantly improving efficiency, as yellow microLEDs have much higher external quantum efficiency than red microLEDs

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses a composite approach by combining four different types of microLEDs (red, green, blue, and yellow) in each pixel. This composite RGBY structure allows the system to leverage the high efficiency of yellow microLEDs while maintaining the color rendering capabilities of red microLEDs, thereby improving overall display efficiency

Inventive Principle:

Principle #40Composite materials

2Ease of manufacture

If red microLEDs with low external quantum efficiency are used, then the display can achieve conventional color balance, but the efficiency at the white point is dominated by the poor performance of red LEDs

Engineering Contradiction:

Improvecolor balance achievementVSAvoiddisplay efficiency

Core Design Contradiction:

Ease of manufactureVSProductivity

Solution Approach 1:

The patent introduces yellow microLEDs with specific wavelength parameters (560-590nm) to change the color balance parameters from RGB to RGBY. This allows achieving the same D65 white point while improving efficiency by reducing reliance on low-efficiency red microLEDs

Inventive Principle:

Principle #35Parameter changes

3Device complexity

If conventional RGB microLED configuration is used, then the display structure is simple, but the efficiency is limited by the 5% external quantum efficiency of red microLEDs compared to 20% for green and blue

Engineering Contradiction:

ImprovemicroLED configurationVSAvoidpower consumption

Core Design Contradiction:

Device complexityVSUse of energy by moving object

Solution Approach 1:

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent applies local quality by assigning different functions to different microLEDs within the pixel: yellow microLEDs handle the yellow-green portion of the spectrum with high efficiency, while red microLEDs are used only where necessary for color rendering, reducing their overall contribution to power consumption

Inventive Principle:

Principle #3Local quality

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 addition of a yellow or amber microLED significantly enhances the overall efficiency of the microLED display, nearly doubling the efficiency at the white point by diluting the impact of the low-efficiency red microLEDs.

Implementation Method 1

Each of the pixels may include a red InGaN microLED, a green InGaN microLED, a blue InGaN microLED, and a yellow/amber InGaN microLED

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Data Source

PatentUS12315413B2MicroLED display

Publication Date: 2025.05.27 LUMILEDS SINGAPORE PTE LTD

AI summary

A display, system and method of providing a display are described. The display includes sets of microLEDs. Each set of microLEDs corresponds to one of a plurality of pixels of the display and produces a combination of light that forms a color of the corresponding one of the pixels. Lenses control an emission angle and emission profile of the light emitted by the sets of microLEDs. Each set of microLEDs has a red microLED that emits red light, a green microLED that emits green light, a blue microLED that emits blue light, and another microLED that emits light along a red-green locus. The red-green locus light is selected to enhance efficiency at a white point to compensate for reduced emission from the red microLED dependent on a size of the red microLED.