Micro LED Color Switching by Current Density Without Conversion Layers

Solution Overview

Problem

Current micro light emitting diode display devices require a wavelength conversion layer to display various colors, which complicates the manufacturing process and increases costs, as they need to separately form light emitting elements for different wavelengths.

Innovation Solution

A micro light emitting diode display device that uses a single light emitting element with an active layer made of InGaN, where the driving current is time-divided to emit light of different wavelengths (red, green, and blue) without the need for a wavelength conversion layer, by adjusting the current density and duration in each period of a frame.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a wavelength conversion layer is used to display various colors, then color display capability is improved, but device complexity and manufacturing cost increase

Engineering Contradiction:

Improvecolor display capabilityVSAvoidstructure complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

A single light emitting element with InGaN active layer performs multiple functions by emitting different wavelengths (red, green, blue) through time-division multiplexing with adjusted current densities, replacing the need for separate light emitting elements and wavelength conversion layers for each color

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent combines the functions of multiple wavelength-specific light emitting elements and wavelength conversion layers into a single light emitting element that can dynamically adjust its emission wavelength through current density control and time-division multiplexing

Inventive Principle:

Principle #5Merging (Combining)

2Adaptability or versatility

If separate light emitting elements are formed for different wavelengths, then color display capability is improved, but manufacturing process complexity increases

Engineering Contradiction:

Improvecolor display capabilityVSAvoidmanufacturing process simplicity

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

A single light emitting element with InGaN active layer performs multiple functions by emitting different wavelengths (red, green, blue) through time-division multiplexing with adjusted current densities, replacing the need for separate light emitting elements and wavelength conversion layers for each color

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent changes the operating parameters (current density and time duration) of a single light emitting element to achieve different emission wavelengths, eliminating the need for separate elements with different material compositions and structures

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If a wavelength conversion layer is added, then various colors can be displayed, but production cost increases

Engineering Contradiction:

Improvecolor display capabilityVSAvoidmaterial quantity

Core Design Contradiction:

Adaptability or versatilityVSQuantity of substance

Solution Approach 1:

A single light emitting element with InGaN active layer performs multiple functions by emitting different wavelengths (red, green, blue) through time-division multiplexing with adjusted current densities, replacing the need for separate light emitting elements and wavelength conversion layers for each color

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent extracts and eliminates the wavelength conversion layer from the display structure, achieving color display directly through the light emitting element's ability to emit different wavelengths at different current densities

Inventive Principle:

Principle #2Taking out (Extraction)

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 simplifies the manufacturing process and reduces costs by allowing various colors to be displayed without a wavelength conversion layer, while maintaining efficient light emission by controlling the indium content in the active layer to shift the wavelength band based on current density.

Implementation Method 1

the light emitting element configured to emit a first light according to a driving current having a first current density, is configured to emit a second light according to a driving current having a second current density, and is configured to emit a third light according to a driving current having a third current density

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Implementation Method 2

An active layer of the light emitting element may include InGaN having an indium (In) content of about 30% to about 45%

Methodology Applied

Scientific EffectBandgap engineering:

Data Source

PatentUS12125838B2Display device and method for fabricating the same

Publication Date: 2024.10.22 SAMSUNG DISPLAY CO LTD

AI summary

A display device comprises a substrate, a pixel electrode on the substrate, a light emitting element on the pixel electrode, and a common electrode layer on the light emitting element, and configured to receive a common voltage, wherein the light emitting element configured to emit a first light according to a driving current having a first current density, is configured to emit a second light according to a driving current having a second current density, and is configured to emit a third light according to a driving current having a third current density.