Pixel Compensation Circuit for OLED Brightness Stability
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Solution Overview
Problem
In OLED display technologies, the change in source-drain voltage of the driving transistor affects the driving current, leading to slight changes in brightness, which compromises image display quality due to the saturation state of the driving transistor.
Innovation Solution
A pixel compensation device that includes a luminance conversion unit, emitting voltage calculation unit, and data conversion unit to calculate and adjust the emitting voltage data for sub-pixel units, generating luminance compensation data to maintain constant brightness while reducing power consumption by adjusting anode or cathode voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the driving transistor operates in saturation state to drive OLED, then the driving current can be controlled, but the brightness changes slightly due to source-drain voltage changes
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing compensation data in a lookup table (LUT) that corresponds to different emitting voltage offsets. Before actual display operation, the system pre-processes the compensation values based on the relationship between emitting voltage offset and luminance compensation, so that during runtime, only a simple table lookup and addition operation is needed to compensate for brightness changes, thereby maintaining brightness stability while keeping the driving transistor in saturation state.
2Use of energy by moving object
If emitting voltage is adjusted to reduce power consumption, then energy efficiency improves, but brightness stability deteriorates
Solution Approach 1:
The patent implements feedback by establishing a compensation mechanism where the emitting voltage offset (difference between preset emitting voltage and reference voltage) is calculated and used to retrieve corresponding luminance compensation data from a pre-stored lookup table. This compensation data is then added to the original luminance signal to counteract the brightness changes caused by emitting voltage adjustment, thereby maintaining brightness stability while achieving power consumption reduction through emitting voltage optimization.
3Illumination intensity
If emitting voltage offset calculation is implemented to compensate brightness, then brightness stability improves, but device complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing the complex compensation relationships in a lookup table during the design phase. The emitting voltage offset compensation data and corresponding luminance compensation data are pre-processed and stored in memory, so that during actual operation, the system only needs to perform simple operations: calculate the emitting voltage offset, lookup the corresponding compensation value in the pre-filled table, and add it to the original luminance signal. This approach transfers the complexity from runtime computation to design-time preparation, significantly reducing the operational complexity of the compensation circuit.
Data Source
AI summary
The present application provides a pixel compensation device, a pixel compensation method, a pixel driving device, a timing control module and a display apparatus. The pixel compensation device includes a luminance conversion unit, an emitting voltage calculation unit, an emitting voltage offset calculation unit and a data conversion unit. The data conversion unit is configured to read pre-stored emitting voltage offset compensation data for a driving transistor in a sub-pixel unit with respect to a gate-source voltage of the driving transistor and obtain corresponding first luminance compensation data based on the emitting voltage offset and the emitting voltage offset compensation data. The data conversion unit is further configured to generate source luminance data based on the luminance signal data and the first luminance compensation data and output the source luminance data to a source driving module.