OLED Display Aging Compensation via Self-Diagnostic Test Images
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Solution Overview
Problem
Existing OLED displays face challenges in compensating for aging of organic materials and transistor components, leading to non-uniformity and reduced efficiency, as previous methods require complex circuitry and cannot accurately account for differential aging rates or transistor threshold voltage changes.
Innovation Solution
A method involving a drive transistor with voltage measurement circuitry to measure and compensate for changes in OLED and transistor characteristics, using test voltages to determine threshold voltage and OLED resistance changes, allowing for complete compensation without extensive circuitry or continuous measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If timing, calculation, and storage circuitry is added to track display operating time, then aging compensation is achieved, but device complexity increases
Solution Approach 1:
The OLED display performs self-diagnosis by utilizing its existing display function to generate test images that reveal aging characteristics. The display itself serves as both the object being tested and the testing apparatus, eliminating the need for external timing and calculation circuitry. The controller simply captures images at different time points and compares them to detect aging.
Solution Approach 2:
Test images serve as an intermediary medium to indirectly measure OLED aging. Instead of directly measuring physical degradation, the system uses visual test patterns displayed on the OLED to detect aging through image capture and comparison, simplifying the measurement mechanism.
2Measurement precision
If continuous measurement and accumulation of drive current is performed for each pixel, then aging compensation precision is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The OLED display autonomously generates test images that traverse across the entire display area, allowing comprehensive measurement of all pixels without requiring individual measurement circuitry for each pixel. The display's own scanning mechanism is utilized for measurement purposes.
Solution Approach 2:
The system performs periodic measurements by capturing test images at different time intervals. Instead of continuous measurement, discrete snapshots are taken and compared, reducing the measurement burden while maintaining adequate precision for aging compensation.
3Reliability
If the controller remains continuously associated with the display to track operating time, then aging compensation accuracy is maintained, but ease of operation and adaptability decrease
Solution Approach 1:
The system performs preliminary measurements by capturing test images at scheduled intervals and stores them for later comparison. This allows the display to be measured during normal operation without requiring continuous controller association, enabling flexible display relocation and use.
Solution Approach 2:
The system creates copies of test images at different time points and compares these copies to detect aging. The actual display can be moved or reassigned while the image copies remain for analysis, decoupling the display from continuous controller supervision.
4Measurement precision
If extensive circuitry is used for measurement and compensation, then measurement precision is improved, but ease of manufacture and device complexity worsen
Solution Approach 1:
The OLED display uses its inherent display functionality to perform measurement, eliminating the need for separate measurement circuitry. The same pixels that display images also serve as the measurement subject, and the existing controller infrastructure is repurposed for measurement tasks.
Solution Approach 2:
The controller serves multiple functions: it drives the display for normal operation, captures test images, compares images to detect aging, and applies compensation. This multi-functionality eliminates the need for dedicated measurement and compensation circuitry, simplifying manufacturing.
Data Source
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AI summary
A method of compensating for changes in an OLED drive circuit includes: providing a drive transistor; providing a first voltage source and a first switch; providing an OLED device connected to the drive transistor. Voltages are measured and used to compensate for changes in the OLED drive transistor.