Display Data Driving Circuit With Segmented Gamma Offset Cancellation
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Solution Overview
Problem
Existing display devices, such as LCDs and OLEDs, face challenges in achieving accurate grayscale due to offset voltages in operational amplifier circuits, which affect the luminance of pixels.
Innovation Solution
A data driving circuit is designed with a gamma voltage generation circuit that includes multiple operational amplifier circuits connected to different points of a resistor string. These circuits employ offset elimination methods, such as auto-zeroing and chopping, to accurately generate gamma reference voltages, thereby eliminating offset voltages and improving grayscale accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a gamma voltage generation circuit uses operational amplifier circuits to divide power supply voltage and generate gamma reference voltages, then the luminance of pixels can be adjusted, but offset voltages in the operational amplifier circuits cause inaccurate grayscale
Solution Approach 1:
The patent divides the gamma voltage generation into multiple operational amplifier circuits (first, second, and third OACs) connected to different points of the resistor string. Each OAC independently generates gamma reference voltages, allowing segmented control and offset elimination through differential processing, thus improving grayscale accuracy while maintaining luminance adjustment capability
Solution Approach 2:
The patent implements offset voltage elimination by comparing and differentiating the output voltages from multiple operational amplifier circuits. The controller measures offset voltages in each OAC and applies compensation through feedback mechanisms, ensuring accurate grayscale representation while preserving the luminance control function
2Measurement precision
If multiple operational amplifier circuits are used to eliminate offset voltages through different methods, then grayscale accuracy is improved, but the circuit complexity increases
Solution Approach 1:
The patent employs multiple operational amplifier circuits that serve dual functions: generating gamma reference voltages for luminance control and enabling offset voltage elimination through differential processing. This multi-functionality approach improves grayscale accuracy without proportionally increasing circuit complexity, as the same hardware components perform multiple tasks
Solution Approach 2:
The patent performs preliminary offset voltage measurement and compensation by the controller before final gamma voltage generation. The controller pre-calculates and applies offset corrections to each operational amplifier circuit, ensuring accurate grayscale output while simplifying the overall circuit design by separating measurement and compensation functions
Data Source
AI summary
The present disclosure relates to an offset elimination operation of an internal operational amplifier of a data driving circuit and relates to a technique that applies different offset elimination methods for each position of an operational amplifier.