Source Driver Offset Cancel Controller for LCD Image Quality
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Solution Overview
Problem
Conventional liquid crystal display (LCD) source drivers fail to maintain optimal image quality due to offset voltage inconsistencies, particularly when switching between 1H and 2H inverted drive modes, leading to degraded image quality and vertical striping irregularities.
Innovation Solution
A source driver with an offset cancel controller circuit that dynamically controls the polarity of the offset voltage based on the pattern select signal, allowing for optimal inversion cycles matching the data signal polarity cycles, ensuring even distribution of data signals and improved image quality across both 1H and 2H inverted drive modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the polarity of data signals is inverted in 2H inverted drive mode (every two pixels in vertical direction), then the burning phenomenon is prevented, but the offset voltage of the amplifier causes vertical striping irregularities and degraded image quality
Solution Approach 1:
The patent applies periodic action by inverting the polarity of the offset voltage at specific intervals (every other horizontal line) to counteract the DC component accumulation caused by 2H inverted drive. This periodic inversion compensates for the offset voltage effects while maintaining the burning prevention benefits of the inverted drive mode.
Solution Approach 2:
The patent changes the parameter of offset voltage polarity dynamically based on the drive mode. By switching the offset voltage polarity between positive and negative states according to a control signal, the system adapts to different inverted drive modes (1H or 2H) and eliminates vertical striping while preserving the anti-burning effect.
2Manufacturing precision
If the polarity of offset voltage is inverted for every one pixel in vertical direction, then the image quality is improved in 1H inverted drive mode, but the solution does not work for 2H inverted drive mode
Solution Approach 1:
The patent achieves universality by designing an offset voltage polarity inversion mechanism that works with both 1H and 2H inverted drive modes. The control circuit receives a mode indication signal and automatically adjusts the inversion pattern accordingly, making the system compatible with different drive modes without requiring separate solutions for each mode.
Solution Approach 2:
The patent implements dynamics by making the offset voltage polarity inversion adaptable to different drive modes. The inversion pattern is dynamically adjusted based on whether 1H or 2H inverted drive is used, allowing the system to optimize image quality for each specific mode while maintaining a unified architecture.
3Device complexity
If a fixed inversion cycle is used for offset voltage polarity, then the circuit operation is simplified, but the image quality degrades when switching between different inverted drive modes
Solution Approach 1:
The patent applies dynamics by making the inversion cycle adaptive rather than fixed. The control circuit dynamically adjusts the inversion pattern based on the detected inverted drive mode, achieving optimal image quality for both 1H and 2H modes while maintaining relatively simple circuit operation through automated mode-based control.
Data Source
AI summary
A source driver which can control the spatial cycle of inverting the polarity of offset voltage in response to the spatial cycle of inverting the polarity of data signal. The liquid crystal display device according to the present invention has an LCD panel, having data lines, and source drivers for supplying data signal to the data lines. The source driver includes an offset cancel control circuit for generating an offset cancel control signal and an amplifier used for generating the data signal, which is configured so as to invert the polarity of the offset voltage in response to the offset cancel control signal OCC. The offset cancel controller circuit receives the pattern select signal PSEL specifying the cycle of inverting the polarity of the offset voltage of the amplifier to generate the offset cancel control signal in response to the pattern select signal PSEL.