Display Device Horizontal Sync Cycle Variation for EMI Noise Reduction
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Solution Overview
Problem
Display devices experience electromagnetic interference (EMI) noise due to the constant cycle of horizontal synchronization signals, which causes audible noise and interference.
Innovation Solution
The horizontal synchronization signal cycle is varied for each line and/or each frame in a display device, allowing for dynamic adjustment of the time interval between horizontal synchronization signals to mitigate EMI noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the horizontal synchronization signal is generated with a fixed cycle, then the display driving operation is stable and synchronized, but electromagnetic interference (EMI) noise and audible noise are generated
Solution Approach 1:
The patent applies dynamics by making the horizontal synchronization signal cycle variable rather than fixed. The timing controller dynamically adjusts the horizontal time cycle based on grayscale values of image data, changing the cycle length according to the complexity of the displayed content. This dynamic adjustment disrupts the constant frequency that causes EMI noise while maintaining stable display operation through adaptive synchronization.
Solution Approach 2:
The patent changes the parameter of the horizontal synchronization signal cycle from a fixed value to a variable value. Specifically, the horizontal time cycle is adjusted based on the grayscale threshold comparison of image data, with longer cycles used for darker grayscales and shorter cycles for lighter grayscales. This parameter change eliminates the constant frequency component that generates EMI noise while preserving display stability through context-adaptive timing.
2Object-generated harmful factors
If the horizontal time cycle is varied to reduce EMI noise, then electromagnetic interference noise is mitigated, but the complexity of the control system increases
Solution Approach 1:
The patent implements parameter changes by adjusting the horizontal time cycle based on grayscale threshold comparisons. The timing controller compares grayscale values against a threshold and selects between a first horizontal time cycle (for grayscales below threshold) and a second horizontal time cycle (for grayscales at or above threshold). This approach reduces EMI noise through variable cycling while keeping control complexity manageable by using simple threshold-based decision logic rather than complex algorithms.
Data Source
AI summary
A display device can include a display panel including touch electrodes and pixels arranged at intersection portions of data lines and gate lines, a controller unit configured to output a touch enable signal to distinguish a display driving section for displaying image and a touch driving section for providing a touch driving signal, a data driver configured to output a data voltage to each of the plurality of data lines and a gate driver configured to output a gate signal to each of the plurality of gate lines in the display driving section, and a touch driver configured to provide the touch driving signal to the touch electrodes in the touch driving section. Also, a frame section between a start of one cycle of a vertical synchronization signal and a start of a next cycle of the vertical synchronization signal comprises a plurality of long horizontal blank (LHB) sections.