OLED Driving Circuit Threshold Voltage Correction Method
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Solution Overview
Problem
The variance in threshold voltage characteristics of driving transistors in OLED elements leads to brightness imbalances across pixels, deteriorating visual quality, as existing methods require extended writing periods to correct these fluctuations.
Innovation Solution
A driving method and circuit that utilize a repetitive process within a unit period, dividing it into a first period for correcting unbalanced driving current and a second period for supplying data voltage, allowing time-sharing of operations to correct threshold voltage imbalances without extending the writing period, thereby improving brightness uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the writing period is extended to implement sufficient threshold voltage correction, then the brightness uniformity is improved, but the productivity is deteriorated
Solution Approach 1:
The patent segments the unit period into two distinct periods: a first period dedicated to threshold voltage correction and a second period for data writing. This temporal segmentation allows the correction operation to be performed separately without extending the overall writing period, as the correction occurs in parallel with the selection of multiple scanning lines during the first period.
Solution Approach 2:
The patent performs threshold voltage correction in advance during the first period before the data writing operation in the second period. By correcting the threshold voltage of the driving transistor beforehand, the system ensures brightness uniformity is achieved without requiring additional time during the data writing phase, thus maintaining productivity.
2Manufacturing precision
If the writing period is extended to correct threshold voltage fluctuations, then the visual quality is improved, but the loss of time is worsened
Solution Approach 1:
The unit period is divided into a first period for correction and a second period for data writing. This segmentation allows correction operations to be performed on multiple scanning lines simultaneously during the first period, achieving visual quality improvement without extending the total time required for the complete write operation.
Solution Approach 2:
The patent implements periodic correction by repeating the unit period comprising both correction and data writing phases. During each first period, threshold voltage correction is performed periodically for selected scanning lines, ensuring visual quality is maintained across frames without requiring continuous extension of the writing period.
3Productivity
If multiple scanning lines are selected for correction simultaneously, then the productivity is improved, but the device complexity is worsened
Solution Approach 1:
The patent merges the correction operations for multiple scanning lines into a single first period within the unit period. By selecting and correcting multiple scanning lines simultaneously during this shared time window, the system improves correction speed and productivity without requiring separate correction circuits for each scanning line, thus avoiding excessive device complexity.
Data Source
AI summary
A method for driving a light-emitting device in which a plurality of pixel circuits are arranged in correspondence with the intersection of a plurality of scanning lines and a plurality data lines, the pixel circuit having a light-emitting element and a driving transistor that controls the current amount of a driving current flowing the light-emitting device, comprises repeating the process within unit period including a first period and a second period following the first period, wherein the second period process includes selecting one scanning line of the plurality of scanning lines, and supplying and holding a data voltage corresponding to the luminance of the light-emitting element to a gate of the driving transistor via the data lines with respect to the plurality pixel circuits connected the selected scanning lines, and wherein the first period process includes selecting two or more scanning lines of the plurality of scanning lines, and correcting the unbalance of the driving current output from the driving transistor in the plurality of pixel circuits connected to the selected scanning lines.