OLED Pixel Circuit Driving Method for Real-Time Threshold Voltage Compensation

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Solution Overview

Problem

Existing OLED display technologies face challenges in compensating for the drift of characteristic parameters of drive transistors, particularly the threshold voltage, which can lead to display defects due to the inability of internal compensation to follow instantaneous variations and external compensation not being able to instantaneously adjust during display operations.

Innovation Solution

A method and device for driving a pixel circuit that includes a light emitting element, a drive transistor, a storage capacitor, and switch circuits, allowing for a data write phase, detection phase, and internal compensation phase to dynamically adjust and detect the driving current, enabling real-time compensation of the threshold voltage and other parameters.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If internal compensation is performed during display operation, then the threshold voltage variation can be followed instantaneously, but other characteristic parameters of the drive transistor cannot be compensated

Engineering Contradiction:

Improveresponse speed to threshold voltage variationVSAvoidcompensation coverage for different parameters

Core Design Contradiction:

SpeedVSAdaptability or versatility

Solution Approach 1:

The patent divides the compensation function into multiple independent modules: threshold voltage compensation (internal), mobility compensation, and leakage current compensation. Each module operates independently during display periods, allowing comprehensive parameter compensation without affecting response speed. The segmentation enables parallel compensation of multiple parameters simultaneously.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent performs preliminary detection of characteristic parameters during non-display periods before actual display operation begins. This preliminary action captures threshold voltage, mobility, and leakage current values in advance, enabling instantaneous compensation during display periods without sacrificing response speed or comprehensive parameter coverage.

Inventive Principle:

Principle #10Preliminary action

2Adaptability or versatility

If external compensation is performed during non-display operations, then all characteristic parameters can be detected and compensated, but the compensation cannot follow threshold voltage variation instantaneously

Engineering Contradiction:

Improvecompensation coverage for different parametersVSAvoidresponse speed to threshold voltage variation

Core Design Contradiction:

Adaptability or versatilityVSSpeed

Solution Approach 1:

The patent implements continuous compensation by executing both internal compensation (during display periods for instantaneous response) and external compensation (during non-display periods for comprehensive parameter detection) in a continuous cycle. This ensures uninterrupted compensation coverage for all parameters while maintaining instantaneous response capability during display operation.

Inventive Principle:

Principle #20Continuity of useful action

Solution Approach 2:

The patent employs periodic alternation between internal compensation mode (during display periods) and external compensation mode (during non-display periods). This periodic action allows the system to switch between instantaneous threshold voltage compensation and comprehensive parameter compensation, achieving both high response speed and complete parameter coverage through time-division multiplexing.

Inventive Principle:

Principle #19Periodic action

3Measurement precision

If detection is performed during non-display operations only, then comprehensive parameter detection is possible, but compensation cannot adjust during display operations

Engineering Contradiction:

Improvedetection accuracy of characteristic parametersVSAvoidcompensation adjustment capability during display

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The patent segments the detection and compensation functions into distinct phases: external detection phase (non-display periods) for comprehensive parameter measurement, and internal compensation phase (display periods) for real-time adjustment. This segmentation allows high-precision detection during non-display periods while enabling continuous compensation during display periods, maximizing both measurement accuracy and productivity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent performs preliminary comprehensive detection of all characteristic parameters during non-display periods, storing the detected values for use during display periods. This preliminary action ensures high measurement precision is achieved without compromising real-time compensation capability during display operation, as all necessary parameter values are pre-acquired and ready for instantaneous adjustment.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS10546531B2Pixel circuit driving method and display device

Publication Date: 2020.01.28 BOE TECHNOLOGY GROUP CO LTD

AI summary

A method of driving a pixel circuit. The pixel circuit includes a light emitting element, a drive transistor, a storage capacitor connected between a gate and a source of the drive transistor, a first switch circuit, a second switch circuit, and a third switch circuit. The method includes: performing a data write phase including: bringing a second node out of conduction with the second power supply voltage by the first switch circuit, and charging the storage capacitor via the first switch circuit with a data voltage applied to the data line; performing a detection phase including directing a driving current generated by the drive transistor based on the data voltage to the sensing line via the third switch circuit; and detecting a magnitude of the driving current.