Pixel Circuit Driving Method for OLED Display Current Error Compensation
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Solution Overview
Problem
Existing light-emitting devices face errors in driving current due to non-uniformity and errors in electric characteristics, particularly when gradation values are not specifically designated, limiting effective compensation of driving current errors across various gradation values.
Innovation Solution
A method of driving a pixel circuit that includes a light-emitting device, a driving transistor, and a storage capacitance, where the voltage across the storage capacitance is reset and asymptotically converged to a threshold voltage, with a compensating operation duration variably set based on gradation values, allowing for accurate suppression of driving current errors by adjusting the time duration of the compensating operation according to gradation values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed compensating operation duration is used, then the compensation is simple to implement, but driving current errors cannot be effectively suppressed across multiple gradation values
Solution Approach 1:
The compensating operation duration is made variable rather than fixed, allowing the compensation period to be dynamically adjusted based on the gradation value. This enables effective suppression of driving current errors across multiple gradation values by adapting the compensation time to the specific gradation requirements.
Solution Approach 2:
The duration of the compensating operation is changed as a controllable parameter based on the gradation value. By adjusting this temporal parameter, the system achieves accurate driving current suppression for different gradation levels without requiring complex additional circuitry.
2Reliability
If the compensating operation duration is extended to suppress errors at low gradation values, then driving current accuracy improves across all gradation values, but the overall operation time increases
Solution Approach 1:
The compensating operation duration is dynamically adjusted based on the gradation value. For low gradation values where error suppression is critical, the duration is extended. For higher gradation values where less compensation is needed, the duration is reduced, thus optimizing the balance between accuracy and time efficiency.
Solution Approach 2:
The time parameter of the compensating operation is varied according to the gradation value. This parameter change strategy allows the system to use longer compensation times only when necessary (at low gradation values), thereby maintaining high driving current accuracy while minimizing overall operation time.
Data Source
AI summary
There is provided a method of driving a pixel circuit. The method includes: performing a compensating operation of asymptotically causing the voltage across the storage capacitance to converge with a voltage corresponding to a threshold voltage of the driving transistor by applying a first reference voltage to the gate of the driving transistor, over a time duration variably set according to a gradation value designated to the pixel circuit, in a compensating period after the elapse of the resetting period; changing the voltage across the storage capacitance from a voltage set by the compensating operation to a voltage corresponding to the gradation value by applying a gradation voltage corresponding to the gradation value from a signal line to the gate of the driving transistor, in a writing period after the elapse of the compensating period.