Touch Detection Module EMI Reduction via Dynamic Driving Schemes
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Solution Overview
Problem
Modern display devices with touch detection modules face challenges in reducing electromagnetic interference (EMI) radiation while maintaining accurate and swift touch detection, as existing methods either increase EMI radiation or prolong detection time.
Innovation Solution
A touch detection module that selectively adjusts the number of simultaneously driven touch driving electrodes and the sum of phases of these electrodes by combining or alternating between simultaneous and sequential driving schemes, using a touch driver circuit with a driving mode setter to control the number of electrodes and phases in each group, thereby reducing EMI radiation and enhancing detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If simultaneous driving scheme is used to drive multiple touch electrodes at the same time, then touch detection speed is improved, but EMI radiation increases
Solution Approach 1:
The patent divides the touch detection process into multiple groups of electrodes that are driven simultaneously in a segmented manner. Instead of driving all electrodes at once (which causes high EMI), the electrodes are divided into multiple groups, and each group is driven simultaneously but with different phase relationships. This segmentation reduces the peak EMI radiation while maintaining fast detection speed.
Solution Approach 2:
The patent employs periodic action by using different phase relationships (in-phase, anti-phase, quadrature phase) for driving electrode groups in different time periods or frames. By periodically changing the phase relationships between groups, the system maintains fast simultaneous detection while distributing EMI radiation over time, preventing sustained high-level interference.
2Object-generated harmful factors
If sequential driving scheme is used to reduce EMI radiation, then EMI radiation is reduced, but touch detection time increases
Solution Approach 1:
The patent merges the advantages of both simultaneous and sequential driving schemes. Multiple electrode groups are driven simultaneously (maintaining fast detection), but with controlled phase relationships that reduce EMI. This combines the speed benefit of simultaneous driving with the EMI reduction benefit of phased/sequential approaches.
Solution Approach 2:
The system dynamically adjusts the driving scheme by selectively changing phase relationships between electrode groups based on detection requirements. The touch driver circuit can adaptively switch between different phase configurations (in-phase, anti-phase, quadrature) to optimize both detection speed and EMI reduction in real-time conditions.
3Measurement precision
If the number of simultaneously driven electrodes is increased, then detection accuracy is improved, but EMI radiation increases
Solution Approach 1:
The patent applies local quality by assigning different phase characteristics to different groups of electrodes. Instead of uniformly driving all electrodes with the same phase (which would cause high EMI), each group has a specific phase relationship tailored to its position and function. This local differentiation maintains detection accuracy while reducing overall EMI radiation.
Solution Approach 2:
The system changes the phase parameter of the driving signals for different electrode groups. By adjusting phase relationships (0°, 180°, 90°/270°) rather than changing amplitude or frequency, the system maintains detection sensitivity and accuracy while controlling EMI radiation through phase-based interference cancellation.
Data Source
AI summary
A touch detection module includes driving electrodes extending parallel to each other, sensing electrodes crossing the driving electrodes, and a touch driver circuit for supplying touch driving signals to the driving electrodes and for detecting touch sensing signals through the sensing electrodes to determine touch position coordinates. The touch driver circuit selects between a group driving scheme and a sequential driving scheme for at least one frame. According to the group driving scheme, the touch driver circuit sorts the driving electrodes into groups, simultaneously drives driving electrodes in a same group among the groups, and drives the groups at different times. According to the sequential driving scheme, the touch driving circuit sequentially drives the driving electrodes.