Local Active Matrix Display Architecture for 100% Emission Duty Cycle

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional display technologies face challenges in achieving high multiplexing ratios and optimal LED efficiency, particularly at high frame rates, due to limitations in emission duty cycle and driving current requirements, which can lead to reduced peak brightness and lifetime degradation.

Innovation Solution

A local active matrix display architecture that combines digital driving capability from pixel driver chips with sample-and-hold and current source functionality from a thin film transistor layer, allowing for 100% emission duty cycle and reduced driving currents, decoupling emission time from programming time to achieve optimal LED efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If conventional display technologies use traditional driving methods, then device complexity is reduced, but emission duty cycle is limited and LED efficiency decreases at high frame rates

Engineering Contradiction:

Improveemission duty cycleVSAvoiddriving circuit complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The display is divided into multiple LPM groups, with each group independently driven by a pixel driver chip. This segmentation allows simultaneous driving of multiple LED matrices, achieving 100% emission duty cycle while distributing the driving complexity across multiple independent units rather than requiring a single complex driving circuit

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A thin film transistor (TFT) layer is introduced as an intermediary between the pixel driver chips and the LED matrices. The TFT layer provides sample-and-hold capability and current source functionality, enabling the decoupling of emission time from programming time and achieving high emission duty cycle without directly increasing pixel driver chip complexity

Inventive Principle:

Principle #24Intermediary (Mediator)

2Illumination intensity

If driving current is increased to maintain peak brightness at high multiplexing ratios, then brightness is maintained, but LED lifetime degrades

Engineering Contradiction:

Improvepeak brightnessVSAvoidLED lifetime

Core Design Contradiction:

Illumination intensityVSReliability

Solution Approach 1:

The thin film transistor layer provides continuous current sourcing capability to the LED matrices, maintaining steady peak brightness without requiring periodic current spikes. This continuous useful action allows high multiplexing ratios to be achieved while keeping driving currents at optimal levels for LED efficiency and lifetime

Inventive Principle:

Principle #20Continuity of useful action

Solution Approach 2:

The system changes the driving parameters by implementing local active matrix control with independent pixel driver chips for each LPM group. This allows optimization of driving current per group, maintaining peak brightness at 100 mA (optimal for LED efficiency) rather than requiring higher currents, thus extending LED lifetime while achieving high multiplexing ratios

Inventive Principle:

Principle #35Parameter changes

3Productivity

If emission time is coupled with programming time in conventional architectures, then device complexity is reduced, but emission duty cycle cannot reach 100% and LED efficiency decreases

Engineering Contradiction:

Improveemission duty cycleVSAvoidarchitecture complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The architecture transitions from a single-layer conventional display structure to a stacked three-dimensional structure with pixel driver chips, TFT layer, and LED matrices in separate layers. This dimensional change allows independent optimization of driving and display functions, enabling 100% emission duty cycle through the decoupling of emission time from programming time via the intermediate TFT layer

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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 solution enables operation at higher multiplexing ratios with reduced power consumption and complexity, maintaining optimal LED efficiency and extending OLED and micro LED lifetimes, while allowing for larger LED matrix sizes and flexible display panel designs.

Implementation Method 1

the TFT layer provides sample-and-hold and current source capability per sub-pixel

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 2

the TFT layer provides sample-and-hold and current source capability per sub-pixel

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 3

an array of light emitting diodes on the thin film transistor layer

Methodology Applied

Scientific EffectLight emitting diode effect: Light Emitting Diode

Implementation Method 4

Each pixel driver chip may be electrically connected to a corresponding matrix of LEDs and corresponding local pixel circuit matrix in the TFT layer

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Data Source

PatentUS12125431B2Local active matrix architecture

Publication Date: 2024.10.22 APPLE INC

AI summary

A local active matrix display panel, circuits and methods of operation are described. In an embodiment, a local active matrix display panel includes an array of pixel driver chip, a thin film transistor layer in electrical contact with the array of pixel driver chips, and an array of light emitting diodes electrically connected with the thin film transistor layer.