LCD Timing Controller Buffer Waveform Shaping for EMI Reduction
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Solution Overview
Problem
Existing LCD driving apparatuses are costly and limit design flexibility due to the need for expensive filter arrays to minimize electro-magnetic interference (EMI), which are often required to manage signal waveforms.
Innovation Solution
A method and apparatus that utilize buffers within the timing controller to transform rectangular waveforms of gate control signals, data control signals, and video data into sloped waveforms, reducing the need for filter arrays and effectively minimizing EMI without increasing manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If filter arrays are used to minimize EMI, then EMI reduction is achieved, but manufacturing cost increases
Solution Approach 1:
The patent extracts the EMI filtering function from the traditional filter array and relocates it to the timing controller's buffer circuits. By taking out the filtering function from a separate hardware component and integrating it into the existing control logic, the design eliminates the need for expensive filter arrays while maintaining EMI mitigation capabilities.
Solution Approach 2:
The timing controller's buffer circuits are designed to perform multiple functions: signal buffering, waveform transformation (rectangular to sloped), and EMI filtering. This multi-functionality allows a single component to replace what would traditionally require separate filter arrays, reducing overall system cost and complexity.
2Object-affected harmful factors
If filter arrays are used to minimize EMI, then EMI reduction is achieved, but design flexibility is limited
Solution Approach 1:
The patent merges the EMI filtering function with the timing controller's existing buffer circuits. By combining these functions into a single integrated unit, the design achieves EMI reduction without adding separate filter components that would constrain PCB layout and design flexibility.
Solution Approach 2:
The buffer circuits dynamically transform rectangular waveforms into sloped waveforms to reduce EMI. This dynamic waveform transformation is controlled through software or configuration settings within the timing controller, allowing flexible adjustment without hardware changes, thereby maintaining design adaptability.
3Ease of operation
If rectangular waveforms are used for control signals, then signal transmission is simple, but EMI generation increases
Solution Approach 1:
The patent changes the waveform parameter from rectangular to sloped by using buffer circuits with controlled charging/discharging characteristics. This parameter transformation reduces the high-frequency content and sharp edges that cause EMI, while maintaining the essential timing and control functions of the signals.
Solution Approach 2:
The buffer circuits act as intermediaries between the rectangular waveform sources and the final output. These buffers transform the waveform shape through their inherent RC time constants, providing a smooth transition that reduces EMI without requiring changes to the original signal generation logic.
Data Source
AI summary
A apparatus and method for driving a liquid crystal display that minimizes the generation of electro-magnetic interference (EMI) in a cost effective manner includes a gate control signal generator that generates a gate control signal using a externally inputted synchronizing signal, a data control signal generator that generates a data control signal using the synchronizing signal, a data aligner that re-aligns externally inputted video data, a plurality of buffers at output terminals of the gate control signal generator, the data control signal generator and the data aligner, and a control unit that applies control signals to the buffers to control current values of signals outputted by the buffers.