OLED Pixel Circuit Sensing and Compensation
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Solution Overview
Problem
Existing organic light-emitting display technologies face challenges in real-time compensation for degradation of pixel circuits due to the time-consuming voltage-sensing method and increased circuit size required for current-sensing methods.
Innovation Solution
A display device and method that perform simultaneous voltage-sensing and current-sensing of pixel circuits, allowing for real-time compensation during both power-off and display periods by utilizing a data-sensing circuit with shared amplifiers and optimized sensing periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If voltage-sensing method is used to compensate for threshold voltage, then sensing accuracy is improved, but sensing time increases significantly (30 ms to 5-10 minutes for UHD resolution)
Solution Approach 1:
The patent performs voltage sensing during the power-off period before the display operates, preparing compensation data in advance. The sensing controller executes the voltage-sensing method during the power-off period, and the timing controller stores the sensed data for subsequent real-time compensation during display operation, eliminating the need for time-consuming sensing during active display.
Solution Approach 2:
The patent implements periodic sensing during power-off intervals and uses this data for continuous compensation during display periods. The system alternates between sensing phases (power-off) and compensation phases (display operation), achieving both accurate measurement and real-time application without continuous time consumption.
2Loss of time
If current-sensing method is used to reduce sensing time, then sensing speed is improved, but circuit size increases due to separate amplifiers
Solution Approach 1:
The patent makes the amplifier in the data driver circuit perform multiple functions: it serves as the sensing amplifier during power-off periods and as the data output amplifier during display periods. This multi-functional design eliminates the need for separate amplifiers dedicated solely to sensing, thereby reducing circuit size while maintaining fast sensing capability.
Solution Approach 2:
The patent merges the sensing circuit functions with the existing data driver circuit by having the sensing controller control the timing controller to utilize the same amplifier hardware for both sensing operations and data output operations, consolidating circuit elements and reducing overall circuit complexity.
3Device complexity
If voltage-sensing method is performed during power-off period, then real-time compensation is not achieved, but circuit complexity is reduced
Solution Approach 1:
The patent implements a feedback mechanism where the sensing controller periodically senses threshold voltage during power-off periods, the timing controller stores this compensation data, and the system applies this feedback during subsequent display operations to continuously compensate for degradation, achieving real-time compensation effect through periodic feedback loops.
Solution Approach 2:
The patent performs compensation sensing in advance during power-off periods and prepares compensation data before display operation begins. This preliminary action allows the system to have compensation data ready for immediate application during display, achieving real-time compensation capability without requiring complex continuous sensing circuits.
Data Source
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AI summary
A display device includes: a pixel circuit including a switching transistor connected to a data line, a storage capacitor connected to the switching transistor, a driving transistor connected to the storage capacitor, an organic light-emitting diode connected to the driving transistor and a sensing transistor connected between a sensing line and the driving transistor; and a data-sensing circuit including a first selector connected to the data line and the sensing line, a second selector connected to an output terminal of an amplifier, the first selector and a feedback capacitor, where the second selector selectively connects the output terminal of the amplifier to the first selector and the feedback capacitor, a third selector connected to the sensing line, and a fourth selector connected to the output terminal of the amplifier and the third selector.