Time Division Driving for Blue OLED Pixel Circuits

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Solution Overview

Problem

The blue organic light-emitting diodes (OLEDs) in active matrix OLED (AMOLED) panels have low luminous efficiency and short service life, leading to deteriorated image quality and shortened panel lifespan.

Innovation Solution

A pixel circuit is designed with multiple blue OLEDs driven in a time division manner, where the blue sub-pixel is segmented into portions, and only a portion is displayed at a time, using a driver circuit with input and driving transistors and storage capacitors to control the emission of blue OLEDs, while also driving red and green sub-pixels concurrently.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Duration of action of stationary object

If a single blue OLED is used in each blue sub-pixel, then the device complexity is low, but the service life of the blue sub-pixel is short

Engineering Contradiction:

Improveservice life of blue sub-pixelVSAvoiddevice complexity of pixel circuit

Core Design Contradiction:

Duration of action of stationary objectVSDevice complexity

Solution Approach 1:

The blue sub-pixel is divided into multiple blue OLEDs (N blue OLEDs) that can be independently controlled. By segmenting the blue sub-pixel into multiple emissive elements, the patent enables time-division multiplexed driving, where only a subset of blue OLEDs is activated in each frame, thereby extending the service life of individual OLEDs while maintaining display quality.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements periodic action by driving different sets of blue OLEDs in alternating time periods. The driving circuit activates a first set of blue OLEDs during one period and a second set during another period, creating a cyclic driving pattern that distributes the operational burden and extends the overall service life of the blue sub-pixel.

Inventive Principle:

Principle #19Periodic action

2Illumination intensity

If multiple blue OLEDs are driven simultaneously, then the luminous output is increased, but the service life of blue sub-pixel is reduced

Engineering Contradiction:

Improveluminous output of blue sub-pixelVSAvoidservice life of blue sub-pixel

Core Design Contradiction:

Illumination intensityVSDuration of action of stationary object

Solution Approach 1:

The patent uses periodic action to drive multiple blue OLEDs in alternating time periods. During each period, a subset of blue OLEDs is activated to provide sufficient luminous output, while other blue OLEDs remain inactive. This cyclic activation pattern ensures that no single OLED is continuously stressed, thereby extending service life while maintaining adequate illumination intensity through temporal multiplexing.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent ensures continuity of useful action by continuously activating at least one blue OLED in each time period. The driving circuit is designed to switch between different sets of blue OLEDs in a continuous manner, ensuring that the blue sub-pixel maintains luminous output without interruption, while distributing the operational load to extend the service life of individual OLEDs.

Inventive Principle:

Principle #20Continuity of useful action

3Use of energy by moving object

If blue OLEDs are driven with high current, then the luminous efficiency is improved, but the service life is shortened

Engineering Contradiction:

Improveluminous efficiency of blue OLEDVSAvoidservice life of blue OLED

Core Design Contradiction:

Use of energy by moving objectVSDuration of action of stationary object

Solution Approach 1:

The patent applies partial action by activating only a subset of blue OLEDs in each time period rather than all blue OLEDs simultaneously. This partial activation reduces the current density and operational stress on individual OLEDs, thereby extending their service life while maintaining adequate luminous efficiency through the cumulative effect of multiple OLEDs contributing over time.

Inventive Principle:

Principle #16Partial or excessive action

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 prolongs the service time of blue sub-pixels and increases the overall service life of the AMOLED panel by balancing the luminescence time of blue, red, and green sub-pixels, maintaining image quality and extending panel durability.

Implementation Method 1

each blue sub-pixel includes N blue organic light-emitting diodes (OLEDs)... drive the N blue OLEDs in a time division manner

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Data Source

PatentUS9536474B2Pixel circuit having a plurality of blue organic light-emitting diodes and driving method thereof

Publication Date: 2017.01.03 BOE TECHNOLOGY GROUP CO LTD

AI summary

The present disclosure provides a pixel circuit, its driving method, an array substrate and a display device. The pixel circuit includes a plurality of pixels, each of which includes a blue sub-pixel and a driving module for driving the blue sub-pixel. The blue sub-pixel includes N blue OLEDs, and N is a positive integer greater than 1. The driving module is configured to drive the N blue OLEDs in a time division manner. According to the present disclosure, the blue sub-pixel is segmented into several portions, and merely a portion of the blue sub-pixel is displayed each time. As a result, it is able to prolong the service time of the blue sub-pixel, thereby to increase the service life of an AMOLED panel.