Independent Shift Registers for OLED Luminance Compensation
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Solution Overview
Problem
Active matrix-type organic EL display devices face issues with luminance nonuniformity and degradation due to variations in drive transistor characteristics, leading to decreased current efficiency and burn-in, which conventional compensation techniques struggle to address effectively.
Innovation Solution
A display device configuration with independent writing control and monitoring control shift registers, where the writing control shift register has a higher current drive capability than the monitoring control shift register, allowing for precise measurement and compensation of drive current without degrading display quality or causing abnormal operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional compensation techniques are used to address drive transistor variations, then manufacturing precision is improved, but device complexity increases due to additional control circuits and monitoring requirements
Solution Approach 1:
The display device is divided into multiple independent blocks, each with its own drive circuit and compensation mechanisms. This segmentation allows localized compensation without requiring system-wide complex control, reducing overall device complexity while maintaining manufacturing precision through distributed correction of luminance nonuniformity
Solution Approach 2:
The patent implements feedback mechanisms where drive currents are monitored and compensation signals are generated based on detected variations. This feedback loop enables automatic correction of luminance nonuniformity caused by transistor characteristics, improving manufacturing precision without requiring manual calibration or overly complex external control systems
2Measurement precision
If drive current measurement is performed for compensation, then measurement precision is improved, but loss of time occurs due to additional measurement periods
Solution Approach 1:
The patent performs drive current measurements during idle periods or before normal display operation begins. By conducting measurements in advance during non-display time slots, the system obtains precise measurement data without causing time loss during actual display operation, maintaining both measurement precision and display continuity
Solution Approach 2:
The measurement and compensation process is implemented periodically rather than continuously. The system measures drive currents at specific intervals and applies compensation at designated periods, which reduces the overall time loss compared to continuous monitoring while maintaining sufficient measurement precision through regular sampling
Data Source
AI summary
A display device that is configured to include two independent shift registers and is capable of performing a monitoring process without causing the degradation of display quality or the occurrence of abnormal operation is implemented. In a display device including: a writing control shift register composed of a plurality of first unit circuits (30) each including a first boost circuit (320) and a first output node reset circuit (330); and a monitoring control shift register composed of a plurality of second unit circuits (40) each including a second boost circuit (420) and a second output node reset circuit (430), current drive capability of the first boost circuit (320) is higher than current drive capability of the second boost circuit (420), and current drive capability of the second output node reset circuit (430) is higher than current drive capability of the first output node reset circuit (330).