OLED Driving Circuit Periodic Compensation for Threshold Voltage Stability
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Solution Overview
Problem
The variation in threshold voltages of driving thin film transistors and organic light emitting diodes in OLED displays leads to deteriorated display quality and reduced lifetime due to prolonged turn-on state and continuous light emission, which existing technologies have not effectively addressed.
Innovation Solution
The method involves dividing a frame into light-emission and compensation sections, where the OLED emits light during the former and does not emit light during the latter, with compensation signals having lower voltage levels than data signals being supplied during the compensation phase to reduce variance in threshold voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the OLED maintains a turn-on state during the entire frame period for continuous light emission, then the display continuity and brightness are improved, but the threshold voltage variance increases and device lifetime decreases
Solution Approach 1:
The patent applies periodic action by dividing the frame period into light emission periods and compensation periods. During light emission periods, the OLED emits light normally. During compensation periods, the OLED stops emitting light and compensation signals are applied to reduce threshold voltage variance. This periodic alternation resolves the contradiction by allowing continuous display operation while periodically resetting the threshold voltages to maintain stability and extend device lifetime.
2Productivity
If the OLED operates continuously without interruption, then the productivity and display performance are improved, but the threshold voltage variance accumulates and deteriorates display quality
Solution Approach 1:
The patent implements periodic compensation cycles within the frame period. The display operates continuously with light emission periods maintaining productivity, while intermittently inserting compensation periods to reset threshold voltages. This periodic intervention prevents threshold voltage variance accumulation, thereby maintaining display quality uniformity without significantly impacting overall productivity.
Solution Approach 2:
The patent applies preliminary action by performing threshold voltage compensation before the variance significantly deteriorates display quality. The compensation periods are strategically positioned to reset the threshold voltages of driving transistors and OLEDs proactively, preventing the accumulation of variance that would otherwise lead to noticeable display quality degradation.
3Illumination intensity
If the frame period is fully utilized for light emission, then the brightness and visibility are improved, but the threshold voltage variance and mobility variance increase
Solution Approach 1:
The patent resolves this contradiction by periodically alternating between light emission periods that maintain brightness and compensation periods that reset threshold voltages and mobility. The light emission periods ensure adequate brightness and visibility, while the periodically inserted compensation periods prevent the accumulation of variance in threshold voltage and mobility, thereby maintaining electrical stability without significantly reducing overall brightness.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach periodically reduces the variance in threshold voltages of the driving thin film transistors and organic light emitting diodes, enhancing display quality and extending the OLED's lifespan by mitigating the effects of prolonged operation and continuous light emission.
Implementation Method 1
the first organic light emitting diode D1 emits light in a section (i.e., a light-emission section) from a falling point of the first gate pulse g1 in the frame to a rising point of a first gate pulse g1 in a next frame
Data Source
Figure 1~2
Figure 3~4
Figure 5A~5B
AI summary
Disclosed is a organic light emitting diode display and a method of driving an organic light emitting diode display that includes a first organic light emitting diode (D1), and a first driving circuit (110) to operate the first organic light emitting diode, the method includes supplying a first gate pulse (g1) and a second gate pulse (g1) to a first gate line (GL1) connected to the first driving circuit (110), and supplying a first data signal (d1) and a first compensation signal (r1) to a data line (DL) connected to the first driving circuit (110).