OLED Pixel Circuit Segmentation for High-Frequency Display Uniformity

Solution Overview

Problem

High-frequency OLED display products face challenges with uneven display due to insufficient charge storage and threshold voltage compensation in pixel circuits, leading to reduced display effectiveness.

Innovation Solution

The proposed display device incorporates a pixel circuit configuration that includes a first reset sub-circuit, a node control sub-circuit, a light emitting control sub-circuit, and a second reset sub-circuit, which work together to provide a stable voltage to the light emitting element, ensuring adequate compensation and uniform display.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If conventional pixel circuits are used in high-frequency OLED displays, then the display refresh rate can be increased, but the charge storage and threshold voltage compensation become insufficient leading to uneven display

Engineering Contradiction:

Improvedisplay refresh rateVSAvoiddisplay uniformity

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The pixel circuit is divided into multiple functional sub-circuits: a first reset sub-circuit for initial voltage setting, a node control sub-circuit for data signal processing and threshold compensation, a light emitting control sub-circuit for driving the OLED, and a second reset sub-circuit for maintaining light emitting element voltage. This segmentation allows each sub-circuit to specialize in specific compensation tasks, ensuring adequate charge storage and threshold voltage compensation even at high refresh rates.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The first reset sub-circuit performs preliminary voltage initialization on the first node before the data signal is written. This preliminary action ensures that the node starts with a known stable voltage state, enabling proper subsequent compensation operations and preventing display unevenness that would occur with insufficient charge storage.

Inventive Principle:

Principle #10Preliminary action

2Device complexity

If simple pixel circuit configuration is used, then device complexity is reduced, but compensation effect is insufficient leading to poor display uniformity

Engineering Contradiction:

Improvepixel circuit configurationVSAvoiddisplay uniformity

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The pixel circuit is divided into multiple functional sub-circuits: a first reset sub-circuit for initial voltage setting, a node control sub-circuit for data signal processing and threshold compensation, a light emitting control sub-circuit for driving the OLED, and a second reset sub-circuit for maintaining light emitting element voltage. This segmentation allows each sub-circuit to specialize in specific compensation tasks, ensuring adequate charge storage and threshold voltage compensation even at high refresh rates.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The node control sub-circuit performs threshold voltage compensation by detecting the voltage state of the first node and adjusting it through the second and third nodes until a threshold condition is met. This feedback mechanism ensures precise compensation of transistor threshold voltage variations, improving display uniformity without requiring overly complex circuit structures.

Inventive Principle:

Principle #23Feedback

3Reliability

If multi-sub-circuit configuration is implemented, then compensation effect and display uniformity are improved, but device complexity increases

Engineering Contradiction:

Improvedisplay uniformityVSAvoidpixel circuit configuration

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The node control sub-circuit performs multiple functions: it processes the data signal, compensates for threshold voltage variations through the second and third nodes, and controls the timing of these operations. By making this sub-circuit multi-functional, the overall device complexity is reduced despite having multiple specialized sub-circuits, as one sub-circuit handles multiple critical tasks.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The first reset line connected to the ith row is electrically connected with the second reset line connected to the (i+1)th row, creating a shared reset path that reduces the total number of independent reset lines needed across the display. This merging of reset functions maintains the compensation effectiveness while reducing overall device complexity.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS12315442B2Display device and driving method therefor

Publication Date: 2025.05.27 CHENGDU BOE OPTOELECTRONICS TECH CO LTD

AI summary

A display device includes light emitting elements arranged in a matrix and pixel circuits arranged in a matrix. A pixel circuit includes a first reset sub-circuit, a node control sub-circuit, a light emitting control sub-circuit and a second reset sub-circuit. The first reset sub-circuit is configured to provide a signal of an initial signal line to a first node. The node control sub-circuit is configured to provide a signal of a data signal line to a second node, and compensate the first node until a voltage of the first node meets a threshold condition. The light emitting control sub-circuit is configured to provide a signal of a first power supply line to the second node and provide a signal of a third node to a light emitting element. The second reset sub-circuit is configured to provide a signal of the initial signal line to the light emitting element.