Pixel Circuit Driving Method for Gray Scale Current Error Compensation
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Solution Overview
Problem
Existing light emitting devices with driving transistors face errors in driving current due to non-uniform electrical characteristics, which are not effectively compensated across various gray scale values, especially when specific gray scale values are not designated.
Innovation Solution
A method of driving a pixel circuit that involves a light emitting element, a driving transistor, and a storage capacitor, where the voltage between the storage capacitor's ends approaches the threshold voltage of the driving transistor through a compensation period, and the temporal length of this operation is adjusted based on the gray scale value to minimize errors in driving current across multiple gray scale values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed temporal length is used for the compensation operation, then the device complexity is reduced, but the manufacturing precision of driving current deteriorates for non-specific gray scale values
Solution Approach 1:
The patent applies dynamics by making the temporal length of the compensation operation variable rather than fixed. The control circuit dynamically adjusts the duration of the compensation period based on the detected gray scale value, allowing optimal compensation time for each gray scale level. This resolves the contradiction by enabling high precision driving current control across all gray scale values without requiring overly complex predetermined control schemes.
Solution Approach 2:
The patent changes the temporal parameter (duration) of the compensation operation based on the gray scale value. By varying the compensation time length according to the specific gray scale level being displayed, the system achieves accurate driving current control for multiple gray scale values. This parameter adjustment allows the same circuit to adapt to different operational requirements without increasing complexity.
2Manufacturing precision
If the temporal length of compensation operation is extended, then the driving current precision is improved, but the productivity of the display refresh cycle is reduced
Solution Approach 1:
The system dynamically adjusts the compensation operation duration based on the gray scale value requirements. For gray scale values requiring higher precision, the compensation time is extended appropriately, while for other cases, the compensation time is kept shorter. This dynamic adjustment ensures high driving current precision when needed while maintaining overall display refresh productivity.
Solution Approach 2:
The patent applies partial action by providing extended compensation time only when and where it is truly needed (for specific gray scale values requiring higher precision). Rather than extending the compensation period for all operations, the system applies the extended duration selectively, thus achieving high precision for critical cases without sacrificing overall refresh rate productivity.
3Speed
If the voltage between storage capacitor ends is rapidly changed, then the response speed is improved, but the reliability of voltage matching with threshold voltage deteriorates
Solution Approach 1:
The patent uses periodic action by implementing a controlled compensation operation that gradually changes the voltage between the storage capacitor ends over a specific time period. This gradual, periodic voltage adjustment ensures accurate matching with the driving transistor threshold voltage, improving reliability. The compensation occurs in a dedicated time period within the display cycle, maintaining both speed and accuracy.
Solution Approach 2:
The system performs preliminary compensation action before the actual display output. By预先 (in advance) adjusting the storage capacitor voltage to match the threshold voltage during the compensation period, the system ensures accurate voltage matching is achieved before the driving current is finalized. This preliminary action prevents errors from propagating to the final display output.
Data Source
AI summary
There is provided a method of driving a pixel circuit that includes a light emitting element; a driving transistor that is connected to the light emitting element in series; and a storage capacitor that is interposed between a gate of the driving transistor and a path, which is formed between the light emitting element and the driving transistor.