Source Driver Offset Removal via Alternating Amplifier Polarity
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Solution Overview
Problem
The offset effect of amplifiers in source drivers for TFT-LCDs causes display quality deterioration due to voltage deviations, leading to image stripes, which existing methods have not effectively addressed.
Innovation Solution
A source driver with a positive amplifier and a negative amplifier, controlled by an input and output controller, alternates the application of gray-level voltages to source lines between frames to average and remove the effects of positive and negative deviations, thereby mitigating the offset impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional amplifier is used in the source driver, then the amplifier can amplify the gray-level voltage to drive the source line, but the amplifier introduces an offset deviation that causes image stripes and deteriorates display quality
Solution Approach 1:
The source driver is segmented into multiple independent amplifier units, each responsible for driving specific source lines. Each amplifier unit can be independently configured with different offset characteristics, allowing the system to compensate for deviations in individual amplifiers by using amplifiers with complementary offset characteristics in different segments.
Solution Approach 2:
The invention changes the operational parameters of the amplifiers by alternating their activation states between positive and negative deviation modes. By controlling which amplifier drives which source line at different time intervals, the system dynamically adjusts the offset parameter to cancel out cumulative deviations and maintain display quality.
2Reliability
If multiple amplifiers with different offset characteristics are used, then the offset effect can be compensated for, but the device complexity increases due to the need for multiple amplifiers and control logic
Solution Approach 1:
Each amplifier unit is designed with multi-functionality, capable of operating in different modes (positive deviation, negative deviation, or compensated mode) depending on the control signals received. This universal design allows a single amplifier hardware unit to serve multiple functions, reducing the need for separate dedicated amplifiers for each function while maintaining offset compensation capability.
Solution Approach 2:
The amplifier configuration is made dynamic rather than static. The control logic dynamically selects which amplifier drives which source line based on real-time offset characteristics and display requirements. This dynamic reconfiguration allows the system to adapt to changing conditions without requiring permanent complex hardware arrangements, thereby managing device complexity while maintaining compensation effectiveness.
3Reliability
If the amplifier offset is corrected continuously, then display quality can be maintained, but the switching elements must continuously switch which amplifier drives which source line, increasing operational complexity
Solution Approach 1:
Instead of continuous correction, the system employs periodic action by correcting amplifier offsets at specific time intervals (e.g., during blanking periods or at frame boundaries). The control logic periodically switches between different amplifier configurations to compensate for accumulated deviations, rather than continuously switching. This periodic approach maintains display quality while significantly reducing the operational complexity and wear on switching elements.
Data Source
AI summary
A source driver and a source line driving method capable of removing the offset effect of an amplifier for every two frames. The source driver includes an amplification unit, an input controller and an output controller. The amplification unit includes a positive amplifier outputting an output voltage having a positive deviation relative to an input voltage applied thereto and a negative amplifier outputting an output voltage having a negative deviation relative to an input voltage applied thereto. The input controller transfers a first gray-level voltage corresponding to a driving voltage of a first source line and a second gray-level voltage corresponding to a driving voltage of a second source line adjacent to the first source line to the amplification unit in response to input positive control signals or input negative control signals. The output controller applies the output voltage of the positive amplifier or the output voltage of the negative amplifier to the first or second source line in response to output positive control signals or output negative control signals.