LCD Common Line Control Circuit for Power and Crosstalk Reduction
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Solution Overview
Problem
Conventional liquid crystal display (LCD) common lines require frequent potential changes, leading to high power consumption, horizontal cross-talk due to high impedance, and perturbations in image quality from asynchronous switching between scan and common lines.
Innovation Solution
A control circuit is implemented for each common line, allowing independent voltage modulation and switching using two switching signals with opposite logic levels, avoiding connection of common lines and employing a double gate pulse method to control scan and common lines, thereby reducing RC delay and ensuring synchronized switching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If common lines are connected together and common electrode potential is changed frequently, then the LCD can operate with conventional driving means, but power consumption increases and horizontal cross-talk occurs
Solution Approach 1:
The patent divides the common lines into separate, independent lines for different rows instead of connecting them together. Each common line is controlled by its own control circuit, allowing independent voltage modulation and switching. This segmentation eliminates the need for all common lines to change voltage simultaneously, reducing power consumption and avoiding horizontal cross-talk while maintaining operational capability.
2Ease of operation
If common lines are connected together and common electrode potential is changed frequently, then the LCD can operate with conventional driving means, but horizontal cross-talk is produced due to high impedance
Solution Approach 1:
The patent segments the common lines into independent row-specific lines, each with its own control circuit. This physical and electrical separation prevents voltage changes on one common line from affecting adjacent lines, thereby eliminating horizontal cross-talk while preserving the ability to use conventional driving methods for each row independently.
3Device complexity
If common lines are connected together and asynchronous switching occurs between scan line and common line, then the LCD can operate with simple control, but perturbations on potential difference are generated affecting image quality
Solution Approach 1:
The patent introduces separate control circuits for each common line, enabling precise, independent timing control for each row's common line voltage changes. This allows the system to maintain simple overall control architecture while achieving precise synchronous switching between scan lines and common lines for each row, eliminating perturbations and ensuring high image quality.
Solution Approach 2:
The control circuits are designed to pre-coordinate the switching timing of common lines with the scan lines. By preparing and executing voltage changes in the correct sequence before actual pixel switching occurs, the system ensures synchronous operation without requiring complex real-time coordination, thus maintaining simple control while achieving precise timing.
Data Source
AI summary
A control circuit for a common line is provided. The control circuit is connected to each of common lines of a liquid crystal display. The control circuit modulates the voltage of each individual common line. The control circuit controls the switching time of the common line according to a pass pulse, and switches the voltage of the common line according to two switching signals. The two switching signals have opposite logic levels in the same frame time.