Touch Panel Driver Signal Edge Separation for EMI Suppression
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Solution Overview
Problem
Touch panels experience deteriorated detection performance due to electromagnetic interference (EMI) caused by the driving signals applied to the electrodes and driving circuits.
Innovation Solution
The method involves a touch detection device with a panel of regularly arranged electrodes, a connector to form sensing channels, and a driver that outputs driving signals with different edges to different sensing channels, as well as a main controller that controls drivers to start input sensing at different times to prevent synchronization of signal edges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If driving signals are applied to electrodes to enable touch detection, then touch detection function is achieved, but electromagnetic interference (EMI) affects electrodes and driving circuits, deteriorating detection performance
Solution Approach 1:
The patent applies periodic action by alternating the polarity of driving signals applied to different sensing channels in a systematic sequence. The driver alternates between positive and negative voltage levels in a periodic manner, ensuring that adjacent sensing channels receive opposite polarity signals at any given time. This periodic polarity alternation creates opposing electromagnetic fields that cancel each other out, reducing EMI effects while maintaining continuous touch detection capability across all channels.
2Productivity
If driving signals with synchronized edges are applied to multiple sensing channels, then efficient parallel detection is achieved, but EMI effect is enhanced due to simultaneous edge transitions
Solution Approach 1:
The patent applies asymmetry by intentionally creating asymmetric timing relationships between driving signals applied to different sensing channels. Instead of applying identical synchronized signals to all channels, the driver offsets the phase and polarity of signals across different channels, ensuring that edge transitions occur at different times. This asymmetric signal distribution prevents simultaneous edge transitions that would otherwise constructively interfere and generate strong EMI, while still enabling parallel detection operations.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively suppresses the EMI effect, improving the detection performance of touch panels by minimizing electromagnetic interference between the electrodes and driving circuits.
Implementation Method 1
there is a problem in that EMI formed by the driving signal affects the plurality of electrodes and/or a plurality of driving circuits in the panel
Data Source
AI summary
A touch detection device includes a panel including a plurality of electrodes regularly arranged in rows and columns, a connector configured to electrically connect some of the electrodes to form a plurality of sensing channels, and a driver configured to provide driving signals to the sensing channels, wherein the driver parts different edges of the driving signals to different sensing channels.