Pixel Circuit Segmentation for Micro-LED Color Stability

Solution Overview

Problem

Inorganic light-emitting devices like micro-LEDs experience variations in luminous efficiency based on the wavelength of emitted light, leading to deviations in color coordinates and white balance due to high voltage, which deteriorates image quality.

Innovation Solution

A pixel circuit design with independent duty ratios for each color, utilizing two compensation circuits that alternately drive light-emitting elements during different frames, and mask signals to control data voltage application, ensuring operation within the maximum efficiency region without degrading image quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If voltage is increased to achieve peak luminous efficiency for certain colors, then luminous efficiency is improved, but color coordinates and white balance deviate from target values, resulting in deterioration of image quality

Engineering Contradiction:

Improveluminous efficiencyVSAvoidcolor coordinates and white balance

Core Design Contradiction:

Loss of energyVSManufacturing precision

Solution Approach 1:

The pixel circuit is divided into two separate circuits: a first circuit for driving light-emitting elements of first colors (e.g., red, green) and a second circuit for driving light-emitting elements of second colors (e.g., blue). Each circuit independently controls its respective light-emitting elements, allowing optimization of driving voltage for each color group without compromising overall image quality

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different driving voltages are applied to different color groups based on their specific luminous efficiency characteristics. The first circuit applies optimized voltages for red and green light-emitting elements, while the second circuit applies optimized voltages for blue light-emitting elements, ensuring each operates at peak efficiency without causing color coordinate deviations

Inventive Principle:

Principle #3Local quality

2Illumination intensity

If voltage is increased to improve luminous efficiency, then luminance becomes too high, but this causes color coordinates to deviate from target values, deteriorating image quality

Engineering Contradiction:

ImproveluminanceVSAvoidcolor coordinates

Core Design Contradiction:

Illumination intensityVSManufacturing precision

Solution Approach 1:

The pixel circuit is divided into two separate circuits: a first circuit for driving light-emitting elements of first colors (e.g., red, green) and a second circuit for driving light-emitting elements of second colors (e.g., blue). Each circuit independently controls its respective light-emitting elements, allowing optimization of driving voltage for each color group without compromising overall image quality

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different driving voltages are applied to different color groups based on their specific luminous efficiency characteristics. The first circuit applies optimized voltages for red and green light-emitting elements, while the second circuit applies optimized voltages for blue light-emitting elements, ensuring each operates at peak efficiency without causing color coordinate deviations

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS20250232710A1Pixel circuit and display device including the same

Publication Date: 2025.07.17 LG DISPLAY CO LTD

AI summary

A pixel circuit can include a light-emitting element, a first driving transistor, a second driving transistor, a first emission switch transistor configured to electrically connect the first driving transistor to the light-emitting element in response to a light emission signal, and a second emission switch transistor configured to electrically connect the second driving transistor to the light-emitting element in response to the light emission signal. Also, the pixel circuit can include a first circuit configured to charge a first data voltage during a first driving period and transfer the light emission signal to the first emission switch transistor during a second driving period, and a second circuit configured to transmit the light emission signal to the second emission switch transistor during the first driving period and charge a second data voltage during the second driving period.