OLED Pixel Driving Circuit with Dual Alternating Circuits

Solution Overview

Problem

OLED display panels face issues with variations in gray scale brightness and non-uniformity due to changes in threshold voltage and mobility of thin-film transistors over time under DC bias, leading to reduced service life.

Innovation Solution

A pixel driving circuit with a driving control circuit and two driving circuits, where the first and second driving circuits are alternately turned on and off by effective and ineffective voltage signals, allowing them to enter a recovery state, thereby maintaining initial transistor characteristics and prolonging panel life.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the driving transistor operates continuously under DC bias to control OLED brightness, then the light emitting control is achieved, but the threshold voltage and mobility of the transistor vary over time causing gray scale non-uniformity

Engineering Contradiction:

Improvelight emitting controlVSAvoidgray scale uniformity

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent implements periodic action by alternating the working state and recovery state of the driving transistor. The first and second driving circuits are alternately activated in different frames, allowing each circuit to enter recovery state when the other is working. This periodic switching prevents continuous DC bias operation, reducing threshold voltage drift and mobility degradation, thereby maintaining gray scale uniformity over time.

Inventive Principle:

Principle #19Periodic action

2Duration of action of moving object

If the driving transistor operates continuously under DC bias, then the brightness control is maintained, but the service life of the OLED panel is reduced

Engineering Contradiction:

Improvebrightness control durationVSAvoidpanel service life

Core Design Contradiction:

Duration of action of moving objectVSDuration of action of stationary object

Solution Approach 1:

The patent applies periodic action by designing a dual driving circuit system where the first and second driving circuits alternate their operation. Each circuit works for one frame then enters recovery state for the next frame, creating a periodic on-off pattern. This prevents continuous operation that would cause transistor degradation, thereby extending the overall service life of the OLED panel while maintaining continuous brightness control capability.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent segments the driving function into two separate driving circuits (first driving circuit and second driving circuit) that share the driving task. By dividing the continuous driving responsibility into alternating segments, each circuit can rest and recover while the other is active, reducing cumulative stress on individual transistors and extending panel lifespan.

Inventive Principle:

Principle #1Segmentation

3Device complexity

If a single driving circuit is used to drive the OLED, then the circuit structure is simple, but the transistor characteristics vary over time causing non-uniform gray scale

Engineering Contradiction:

Improvecircuit structureVSAvoidgray scale uniformity

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent segments the driving function into two separate driving circuits (first driving circuit and second driving circuit) that share the driving task. By dividing the continuous driving responsibility into alternating segments, each circuit can rest and recover while the other is active, reducing cumulative stress on individual transistors and extending panel lifespan.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements periodic action by alternating the working state and recovery state of the driving transistor. The first and second driving circuits are alternately activated in different frames, allowing each circuit to enter recovery state when the other is working. This periodic switching prevents continuous DC bias operation, reducing threshold voltage drift and mobility degradation, thereby maintaining gray scale uniformity over time.

Inventive Principle:

Principle #19Periodic action

Data Source

PatentUS10510296B2Pixel driving circuit and pixel driving method, array substrate and display device

Publication Date: 2019.12.17 BOE TECHNOLOGY GROUP CO LTD

AI summary

Disclosed is a pixel driving circuit, comprising a driving control circuit, a first driving circuit and a second driving circuit. The driving control circuit is configured to control one of the first driving circuit and the second driving circuit to be turned on under the condition the first scanning line outputs an effective voltage signal, and control the other of the first driving circuit and the second driving circuit to be turned on under the condition the second scanning line outputs an effective voltage signal. The first driving circuit is configured to drive the light emitting circuit to emit light under control of the driving control circuit. The second driving circuit is configured to drive the light emitting circuit to emit light under control of the driving control circuit.