Organic EL Drive Method for Simultaneous Transistor and Element Degradation Compensation
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Solution Overview
Problem
Existing drive methods for organic EL display devices cannot simultaneously compensate for the degradation of both drive transistors and organic EL elements within a sufficient time frame, leading to variations in brightness and reduced display quality.
Innovation Solution
A drive method that detects and compensates for the degradation of both drive transistors and organic EL elements by using a monitor line to measure current and voltage characteristics, allowing for simultaneous correction of video signals across a pixel matrix, ensuring adequate time for detection and emission periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional drive method is used to detect and compensate for degradation, then either drive transistor degradation or organic EL element degradation can be compensated, but not both simultaneously within a sufficient time frame
Solution Approach 1:
The patent segments the detection process into two distinct phases: a drive transistor detection period where transistor characteristics are measured, and an organic EL element detection period where element characteristics are measured. This segmentation allows each component to be detected and compensated separately within the same frame period, resolving the contradiction by enabling both types of degradation compensation without requiring excessive time.
Solution Approach 2:
The patent implements periodic detection cycles where the drive transistor and organic EL element are detected alternately at different time points within each frame period. The drive transistor is detected during the detection period, and the organic EL element is detected during the emission period, creating a periodic pattern that ensures both components are monitored regularly without extending the total time beyond one frame period.
2Reliability
If the detection period is extended to compensate for both drive transistor and organic EL element degradation, then compensation accuracy improves, but the time available for light emission decreases
Solution Approach 1:
The patent performs drive transistor detection during a detection period that occurs before the organic EL element emission period. By detecting and compensating for drive transistor degradation in advance during the detection period, the system prepares the drive parameters beforehand, allowing the subsequent emission period to be used fully for light emission without requiring additional time for transistor compensation.
Solution Approach 2:
The patent ensures continuous useful action by overlapping the detection and emission functions within the same frame period. While the drive transistor is being detected during the detection period, the system is preparing for the emission period where organic EL elements emit light. This continuous alternation between detection and emission phases ensures that both compensation functions are performed without creating idle time that would reduce light emission duration.
3Measurement precision
If separate detection periods are used for drive transistor and organic EL element, then detection precision improves, but the overall frame period becomes too long
Solution Approach 1:
The patent merges the drive transistor detection period and organic EL element detection period into a single integrated frame period. The drive transistor detection occurs during a detection period, and the organic EL element detection occurs during the emission period, both within the same frame period. This merging of detection functions into one unified time cycle maintains high measurement precision for both components while preventing the frame period from becoming excessively long, thus preserving frame rate productivity.
Data Source
AI summary
A monitor line electrically connectable with sources of drive transistors and positive electrodes of electro-optical elements is provided. A drive method includes a step of detecting the characteristics of a drive transistor, a step of detecting the characteristics of an electro-optical element, a step of storing characteristics data obtained on the basis of a result of the detection of the characteristics, as correction data for correcting a video signal, and a step of correcting the video signal on the basis of the correction data. Here, the length of a selection period is set to be equal for a monitored row and an unmonitored row. In addition, a potential given to the monitor line for the detection of the characteristics of the drive transistors and a potential given to the monitor line for the detection of the characteristics of the electro-optical elements are made different.