Touch Screen Driving Signal Timing for EMI Reduction
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Solution Overview
Problem
Consumer electronic devices with touch sensitive screens experience cyclical electromagnetic interference due to the cyclical driving signals used in mutual capacitive detection, which can interfere with other wireless communication systems, particularly those using spread spectrum communication protocols.
Innovation Solution
A touch sensitive controlling method and device that continuously drives electrodes of a touch sensitive screen three times, with two cease-driving durations between the drivings being different, to reduce cyclical electromagnetic interference by making the driving signals less ordered and more scattered, thereby avoiding coincidence with communication protocols' cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cyclical driving signals are used for touch sensitive screen detection, then touch detection function is achieved, but electromagnetic interference with wireless communication systems occurs
Solution Approach 1:
The patent applies periodic action by using three continuous drivings with different cease-driving durations to create a driving signal pattern that is periodic yet non-cyclical. This breaks the regular cyclical pattern that causes EMI while maintaining the necessary periodic detection function for touch sensitivity.
Solution Approach 2:
The patent changes the parameter of cease-driving duration by making the two cease-driving durations different from each other. This parameter variation disrupts the cyclical pattern that causes electromagnetic interference while preserving the touch detection capability.
2Ease of operation
If cyclical driving signals are emitted at regular intervals, then touch screen control is maintained, but information transmission in communication systems is blocked or interfered with
Solution Approach 1:
The patent uses periodic action with three continuous drivings where the cease-driving durations between drivings are different. This creates an irregular periodic pattern that maintains touch screen controllability while avoiding the regular cyclical interference that blocks information transmission in communication systems.
Solution Approach 2:
The patent applies asymmetry by making the two cease-driving durations different from each other. This asymmetric timing pattern breaks the symmetry of regular cyclical signals, thereby reducing interference with communication systems while maintaining ease of touch screen operation.
3Productivity
If regular cyclical driving signals are used, then touch detection efficiency is maintained, but interference with spread spectrum communication systems increases
Solution Approach 1:
The patent employs periodic action through three continuous drivings with different cease-driving durations. This creates an irregular periodic pattern that maintains touch detection efficiency by ensuring regular detection cycles while reducing interference with spread spectrum communication systems through the non-uniform timing.
Solution Approach 2:
The patent changes the timing parameter by making the cease-driving durations different, which disrupts the regular cyclical pattern that causes interference with communication systems while preserving the detection efficiency necessary for productive touch operation.
Data Source
AI summary
A touch sensitive processing method applicable to a touch sensitive processing device connecting with a touch sensitive screen, wherein the touch sensitive screen includes multiple first electrodes being parallel to each other and multiple second electrodes being parallel to each other, wherein both the first and the second electrodes form multiple intersectional points, the touch sensitive processing device comprises a driving circuit configured to connect with at least one of the first electrodes of the touch sensitive screen; a sensing circuit configured to connect with the second electrodes; and a processor configured to connect with the driving circuit and the sensing circuit and to perform the touch sensitive processing method, wherein the touch sensitive processing method comprising: commanding the driving circuit to continuously drive the at least one of the first electrodes three times; and commanding the sensing circuit to detect changes in capacitance by the second electrodes for detecting an object, wherein two cease-driving durations between the three drivings are different.