Real-Time TFT Compensation in OLED Displays
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Solution Overview
Problem
Existing organic light emitting display devices face challenges in achieving uniform image quality due to non-uniformity in threshold voltage and mobility characteristics of driving TFTs, which limits real-time compensation and is sensitive to environmental factors, leading to accuracy issues and luminance differences between pixels.
Innovation Solution
The method involves sensing characteristics of driving TFTs at power-on and power-off times to generate initial and updated compensation data, allowing for real-time compensation during image display by using a sensing unit, compensation data calculating unit, and panel driving unit to adjust data voltages for each pixel, thereby reducing sensing errors and increasing compensation accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If real-time sensing is performed during blank intervals between frames, then compensation can be updated continuously, but sensing accuracy is reduced due to data voltages supplied immediately before sensing
Solution Approach 1:
The patent performs sensing operations during blank intervals between frames before the next data voltage is supplied. By completing the sensing action in advance (during the blank interval), the system can accurately measure the voltage state without interference from upcoming data voltage changes, thus maintaining both real-time updates and sensing accuracy
Solution Approach 2:
The patent implements periodic sensing during blank intervals between frames. This periodic action allows the system to continuously update compensation data at regular intervals (when blank intervals occur) while maintaining accurate measurements, as each sensing cycle is separated by the next data voltage supply cycle
2Productivity
If compensation is performed for all pixels simultaneously, then compensation speed increases, but sensing errors increase due to environmental sensitivity
Solution Approach 1:
The patent segments the pixel array into multiple regions and processes them in sequential batches during blank intervals. Instead of attempting to sense all pixels simultaneously (which would increase environmental sensitivity and errors), the system divides the large task into smaller manageable segments that can be processed one after another, maintaining both speed and accuracy
Solution Approach 2:
The patent performs preliminary compensation for all pixels using initial compensation data before real-time sensing begins. This preliminary action establishes a baseline compensation state, and subsequent real-time sensing only needs to make incremental updates, reducing the impact of environmental factors during the sensing process
3Device complexity
If the same data voltage is applied to all driving TFTs, then manufacturing complexity is reduced, but image uniformity deteriorates due to TFT characteristic deviations
Solution Approach 1:
The patent applies different compensation voltages to different pixels based on their individual TFT characteristics. Each pixel receives a customized compensation voltage calculated from its sensed threshold voltage and mobility values, allowing local optimization of image uniformity while maintaining a simple overall control architecture
Solution Approach 2:
The patent implements a feedback mechanism where the actual voltage state is sensed during blank intervals, and compensation data is updated based on the sensed values. This feedback loop continuously adjusts the compensation voltages to maintain image uniformity, compensating for TFT characteristic deviations without requiring complex manufacturing processes
4Duration of action of stationary object
If sensing is performed during blank intervals, then image display is not interrupted, but compensation range is limited by ADC output range
Solution Approach 1:
The patent performs preliminary compensation for all pixels using initial compensation data before real-time sensing begins. This preliminary action establishes a baseline compensation state, and subsequent real-time sensing only needs to make incremental updates within the ADC range, effectively extending the compensation range while maintaining display continuity
Solution Approach 2:
The patent performs sensing operations periodically during blank intervals between frames. By distributing sensing operations over multiple blank intervals, the system can accumulate compensation data that extends beyond the immediate ADC output range, while the display remains uninterrupted during the sensing operations
Data Source
AI summary
A method of driving an organic light emitting display device includes sensing characteristics of driving TFTs of pixels to generate sensing data at a power-on time when the organic light emitting display device is powered on, merging initial compensation data and the sensing data at the power-on time to compensate for the characteristics of the driving TFTs of all the pixels, displaying an image in a driving mode and sequentially sensing characteristics of driving TFTs of a plurality of pixels in units of one horizontal line in real time during a blank interval between frames, and sequentially compensating for the characteristics of the driving TFTs of the pixels in units of one horizontal line in real time by using a real-time sensing data generated by real-time sensing.