Source Driver Adaptive Offset Cancellation for Display Panels
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Solution Overview
Problem
Conventional output buffer offset voltage cancellation techniques in source drivers for display panels are ineffective under varying display data conditions, leading to inaccurate gray levels and increased power consumption.
Innovation Solution
The implementation of a row-based, per-column row-based, and sub-pixel-wise input offset voltage cancellation modes using chopper modes A and B, dynamically adjusting the offset voltage to match the input voltage within a threshold, reducing offset voltage and enhancing gray level accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional output buffer offset voltage cancellation techniques are used, then the circuit structure remains simple, but gray level accuracy deteriorates under varying display data conditions
Solution Approach 1:
The patent implements dynamic offset voltage cancellation by continuously monitoring the actual output voltage of each output buffer and adjusting the offset compensation in real-time based on varying display data conditions. This dynamic approach allows the system to adapt to different operating conditions and maintain high gray level accuracy throughout the display refresh cycle.
Solution Approach 2:
The patent employs feedback mechanisms where the actual output voltage of each output buffer is monitored and fed back to the offset cancellation circuitry. This feedback enables the system to detect and correct offset voltage errors, ensuring accurate gray level reproduction even when display data conditions change during operation.
2Measurement precision
If conventional offset voltage cancellation is applied, then power consumption is reduced, but gray level accuracy deteriorates due to inability to compensate under varying conditions
Solution Approach 1:
The system dynamically adjusts the offset compensation based on actual operating conditions, applying cancellation only when and where needed. This dynamic operation maintains high gray level accuracy while minimizing unnecessary power consumption that would occur with continuous static compensation.
Solution Approach 2:
The patent changes the offset voltage parameter dynamically based on monitored output conditions and display data variations. By adjusting this parameter in response to actual system state, the patent achieves accurate gray level reproduction while optimizing power consumption by avoiding unnecessary compensation operations.
3Measurement precision
If dynamic offset voltage adjustment is implemented, then gray level accuracy improves, but device complexity increases
Solution Approach 1:
The patent segments the offset cancellation function into individual output buffer units, where each buffer has its own offset compensation circuitry that operates independently. This segmentation allows for localized adjustments without requiring complex system-wide control, thereby improving gray level accuracy while limiting the increase in overall device complexity.
Solution Approach 2:
Each output buffer in the patent performs self-diagnosis and self-correction of offset voltage errors by monitoring its own output and automatically adjusting its compensation. This self-service capability eliminates the need for complex external control circuits, achieving high gray level accuracy without proportionally increasing device complexity.
Data Source
AI summary
A display panel subsystem adaptively employs one of three types of input offset voltage cancellation modes based on an analysis of gray level values of sub-pixels for each row un a frame of image data. The system selects a candidate row within a selected group of rows and applies a first chopper mode to each sub-pixel in the candidate row. Under a row-based mode, the system applies a second chopper mode to each sub-pixel included in a row having gray level values matching the candidate row. Under a per-column row-based mode, the system applies the row-based mode on a per-column basis. Under a sub-pixel-wise mode, for each column, the system changes a chopper mode applied to a sub-pixel in a subsequent row relative to the last state of the chopper mode in a row having the same gray level value as a corresponding sub-pixel in the subsequent row.