Data Driver Phase Difference Control for EMI Suppression
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Solution Overview
Problem
High-speed operation of data drivers in display devices leads to electromagnetic interference (EMI), causing periodic light and dark stripes in images, which degrade image quality.
Innovation Solution
A data driver configuration that includes a resistance circuit, a selector unit, and a phase difference control unit to delay output node selection based on the input gradation signal, particularly in high or low tonal ranges, to distribute voltage and current change timings and suppress EMI.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-speed operation is implemented to meet higher-definition display requirements, then productivity is improved, but electromagnetic interference increases causing image quality degradation
Solution Approach 1:
The patent applies periodic action by intentionally introducing timing shifts (phase differences) in the operation of multiple source drivers. Instead of operating all source drivers simultaneously at high speed, the patent staggers their operation timing periodically, which distributes the electromagnetic radiation events over time and reduces peak EMI levels while maintaining overall high-speed operation capability
2Object-affected harmful factors
If operation timing is shifted for each source driver to suppress EMI, then electromagnetic interference is reduced, but periodic light and dark stripes appear in the displayed image
Solution Approach 1:
The patent applies local quality by selectively applying timing shifts only to specific source drivers based on their position in the array. The control unit determines which source drivers require timing adjustments based on local EMI characteristics and image quality requirements, rather than uniformly shifting all drivers. This localized approach allows EMI suppression while minimizing the impact on image quality
3Productivity
If multiple source drivers operate simultaneously at high speed, then productivity is improved, but the cumulative electromagnetic interference causes malfunction of electronic circuits
Solution Approach 1:
The patent applies segmentation by dividing the operation of multiple source drivers into separate time segments or phases. Instead of all source drivers operating simultaneously, the control unit segments their operation timing so that they activate at different moments. This segmentation reduces the cumulative radiation noise generated by simultaneous high-speed operation while maintaining overall productivity
Data Source
AI summary
Provided is a data driver configured to drive a display unit that includes a two-dimensional matrix of pixels, the data driver including: a resistance circuit to which a plurality of reference voltages with different values are applied, the resistance circuit including a plurality of output nodes configured to output the reference voltages and voltages obtained by dividing the reference voltages; a selector unit configured to select one of the plurality of output nodes in accordance with a value of an input gradation signal, and cause a voltage corresponding to the value of the gradation signal to be output; and a phase difference control unit configured to perform control to delay an output node selection operation by the selector unit in the case where an input gradation signal is included in a predetermined high tonal range or a predetermined low tonal range.