Liquid Crystal Driver Segmentation for EMI Reduction
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Solution Overview
Problem
Conventional multi-output liquid crystal drivers cause electromagnetic interference (EMI) due to simultaneous current flow in source lines, leading to spike-like noise and potential degradation in display image quality.
Innovation Solution
The output amplifiers are divided into groups with staggered output timing and sequence changes, preventing current convergence and ensuring uniform voltage distribution across pixel electrodes, thereby reducing EMI and maintaining high-quality display.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If all output terminals output the drive signal at the same timing, then the drive signal can be output efficiently, but currents converge causing large instantaneous current flow and spike-like noise
Solution Approach 1:
The output terminals are divided into multiple groups (first group and second group) with different output timing. The first group outputs at a first timing and the second group outputs at a second timing, preventing current convergence and reducing electromagnetic interference while maintaining efficient drive signal output.
2Productivity
If source lines are driven concurrently, then the liquid crystal panel can be driven efficiently, but large current flows causing EMI and potential display quality degradation
Solution Approach 1:
Source lines are divided into first source lines and second source lines, with the first source lines driven at a first timing and the second source lines driven at a second timing. This segmentation prevents current convergence, reduces electromagnetic interference, and maintains efficient panel operation.
Solution Approach 2:
The drive signal output is performed periodically with different timings for different groups. The output timing alternates between first timing for the first group and second timing for the second group, creating a periodic action that prevents simultaneous current flow and reduces EMI while maintaining drive efficiency.
3Object-generated harmful factors
If output timing is staggered between groups, then current convergence is avoided, but voltage distribution uniformity across pixel electrodes may be compromised
Solution Approach 1:
The output timing parameters are adjusted for different groups to stagger their operation. By controlling the timing parameters (first timing and second timing), the system avoids current convergence while ensuring that voltage distribution remains uniform across all pixel electrodes through precise timing control.
Data Source
AI summary
There is provided a display driver device (liquid crystal driver) causing no degradation in display image quality even when a plurality of signal lines (source lines) of a display panel are divided into a plurality of groups as a countermeasure against EMI. With a liquid crystal display driver device (the liquid crystal driver) for generating image signals to be impressed to respective signal lines of a display panel upon receiving display image data, and outputting the image signals in a lump, corresponding to every one line, according to an output timing signal inputted from outside, output amplifiers, in the last stage of the liquid crystal driver, for outputting the image signals, respectively, are divided into a plurality of groups, and the output amplifiers of respective groups are caused to undergo a periodical change in output sequence while the respective image signals are slightly staggered in output timing by the group.