Pixel Circuit Driving Method for OLED Compensation
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Solution Overview
Problem
Existing light emitting devices face challenges in securing sufficient time for compensation operations of driving transistors due to the need to complete both compensation and recording operations within a horizontal scanning period, which restricts the number of scanning lines and affects error compensation in threshold voltage and mobility.
Innovation Solution
The method involves time-divisionally supplying gradation potentials to signal lines and executing a first compensation operation before the start of each unitary period, using a separate electric supply line for reference potentials, allowing for extended compensation time without increasing scanning line selection time, and optionally including a second compensation operation after gradation potential supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the horizontal scanning period is extended to secure sufficient time for compensation operation, then the compensation accuracy is improved, but the number of scanning lines that can be displayed is restricted
Solution Approach 1:
The compensation operation is performed in advance during a compensation period that occurs before the scanning line selection period. By executing the compensation operation preliminarily using the holding capacitor and reference potential supply, the patent ensures sufficient compensation time without extending the horizontal scanning period, thereby maintaining high scanning line capacity while achieving accurate threshold voltage compensation.
2Device complexity
If one signal line is used for both reference potential supply and gradation potential supply, then the device complexity is reduced, but the time required for compensation operation is insufficient
Solution Approach 1:
The patent segments the potential supply functions by using separate signal lines for reference potential supply and gradation potential supply. This segmentation allows the reference potential to be supplied independently during the compensation period without interfering with the gradation potential supply, thereby securing sufficient time for the compensation operation while maintaining clear functional separation.
3Manufacturing precision
If the voltage across the holding capacitor is made to approach the threshold voltage through compensation operation, then the error in threshold voltage is compensated, but the time required for this operation is considerable
Solution Approach 1:
The compensation operation is performed in advance during a dedicated compensation period before the scanning operation begins. By using the holding capacitor to maintain the compensated voltage and performing the asymptotic approach to threshold voltage preliminarily, the patent achieves accurate threshold voltage error compensation without requiring considerable time during the active scanning period.
Data Source
AI summary
A method of driving a plurality of pixel circuits. The pixel circuits are disposed corresponding to intersections between a plurality of scanning lines and a plurality of signal lines. Each of the pixel circuits includes: a light emitting element; a driving transistor; a holding capacitor; and a selection switch electrically interconnecting the signal line and the gate of the driving transistor at the time of the selection of the scanning line. The method includes: supplying a gradation potential to each signal line during a first period, selecting the scanning line during a second period, and supplying the gradation potential to the gate of the driving transistor; controlling the driving transistor of each of the pixel circuits to be in an ON state, supplying a reference potential to the gate of the corresponding driving transistor, and executing a first compensation operation and supplying driving current to the light emitting element.