OLED Threshold Voltage Compensation Using Dual-Bank Memory Segmentation
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Solution Overview
Problem
Organic light emitting displays face a reduction in lifespan due to changes in the characteristics of driving transistors over time, leading to a decrease in driving current and luminance differences between subpixels, resulting in issues like horizontal stripes and reduced image quality.
Innovation Solution
An organic light emitting display system that includes a data driver, a memory with two banks, and a sensing circuit unit to measure threshold voltages and provide compensation data, allowing for real-time compensation by writing and reading previous and new compensation data separately across the memory banks to maintain consistent subpixel performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If threshold voltage compensation is implemented using a single memory bank, then compensation data can be stored, but reading and writing operations conflict causing display abnormalities
Solution Approach 1:
The memory is divided into two separate banks (first bank and second bank) to avoid read-write conflicts. During odd frames, the first bank stores compensation data while the second bank displays; during even frames, they switch roles. This segmentation eliminates interference between read and write operations, ensuring display stability without requiring complex arbitration logic.
2Reliability
If real-time compensation data is written during display period, then compensation can be applied, but display abnormalities occur due to simultaneous read operations
Solution Approach 1:
The system uses periodic frame-based operations where odd frames are dedicated to writing compensation data and even frames to reading and displaying. This periodic alternation ensures that write and read operations never occur simultaneously, eliminating display abnormalities while maintaining continuous real-time compensation across all frames.
3Reliability
If compensation data is not updated frequently, then memory operations are simple, but transistor characteristic changes are not compensated, reducing lifespan
Solution Approach 1:
The sensing circuit continuously monitors threshold voltage changes of driving transistors in real-time, and the data driver continuously updates compensation data based on this feedback. This continuous feedback loop ensures that transistor characteristic changes are promptly detected and compensated, maintaining performance consistency and extending display lifespan through an appropriately complex but effective compensation mechanism.
Data Source
AI summary
An organic light emitting display and a method for driving the same are disclosed. The organic light emitting display includes a display panel, a data driver supplying a data signal to the display panel, a memory which is positioned inside or outside the data driver and includes at least two banks, and a sensing circuit unit which measures a threshold voltage of at least one driving transistor included in the display panel and provides compensation data. The data driver separately writes and reads previous compensation data and new compensation data provided by the sensing circuit unit in the at least two banks of the memory.