Micro LED Driving Circuit Using Double Gate Transistor for Color Reproducibility

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Solution Overview

Problem

Conventional micro LED display devices face challenges in color reproducibility due to wavelength shifts when using the PAM driving method, which affects gradation expression and leads to screen distortion, especially in large displays composed of modular panels.

Innovation Solution

The proposed micro LED driving circuit incorporates a PWM circuitry and a CCG circuitry, utilizing a double gate transistor to adjust the light emitting time of micro LEDs and maintain a constant current during emission, thereby improving color reproducibility and addressing issues related to power consumption and luminance uniformity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If PAM driving method is used to control gradation through current adjustment, then gradation expression is achieved, but wavelength shifts occur causing color reproduction deterioration

Engineering Contradiction:

Improvegradation expression capabilityVSAvoidcolor reproduction accuracy

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent changes the control parameter from current magnitude (PAM) to time duration (PWM), where gradation is expressed by adjusting the light emission time rather than current level. This parameter change eliminates wavelength shifts while maintaining gradation capability.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs periodic light emission control through PWM signaling, where the micro LED is switched on and off in periodic cycles with varying duty cycles to achieve different gray levels. This periodic action maintains constant current while controlling perceived brightness through time modulation.

Inventive Principle:

Principle #19Periodic action

2Ease of operation

If current magnitude is adjusted for gradation control, then gray levels are expressed, but color wavelength changes causing screen distortion

Engineering Contradiction:

Improvegradation controlVSAvoidcolor wavelength stability

Core Design Contradiction:

Ease of operationVSStability of the object's composition

Solution Approach 1:

The patent transitions from current magnitude control to time-based control, where the same constant current is applied but for different durations. This parameter substitution maintains color wavelength stability while achieving the desired gradation control effect.

Inventive Principle:

Principle #35Parameter changes

3Area of stationary object

If multiple modular micro LED panels are connected for large display, then display size is increased, but color wavelength differences between modules cause gradation problems

Engineering Contradiction:

Improvedisplay areaVSAvoidgradation uniformity across modules

Core Design Contradiction:

Area of stationary objectVSManufacturing precision

Solution Approach 1:

The PWM driving circuit provides a universal control method that works consistently across all modular panels. By using time-based control with constant current, the same driving mechanism achieves uniform gradation expression across different modules, eliminating wavelength mismatch issues.

Inventive Principle:

Principle #6Universality (Multi-functionality)

4Productivity

If PAM driving method is used, then gradation is achieved through current control, but power consumption increases due to continuous current flow

Engineering Contradiction:

Improvegradation expressionVSAvoidpower consumption

Core Design Contradiction:

ProductivityVSUse of energy by moving object

Solution Approach 1:

The patent uses periodic pulsed current delivery where the micro LED conducts current only during the on-period of the PWM cycle. During the off-period, current is completely stopped, significantly reducing average power consumption while maintaining the same perceived brightness through temporal integration.

Inventive Principle:

Principle #19Periodic action

Data Source

PatentUS20250078730A1Micro LED driving circuit comprising double gate transistor and micro LED display device comprising thereof

Publication Date: 2025.03.06 SEOUL NATIONAL UNIVERSITY R&DB FOUNDATION

AI summary

The present invention relates to a micro LED driving circuit including a double gate transistor, and includes a PWM circuitry for controlling the emission time of the micro LED; and a CCG circuitry that controls a constant current to be supplied while the micro LED emits light based on the PWM data voltage.