Touch Sensing Device Flatness Index False Touch Prevention
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Solution Overview
Problem
Conventional touch sensing devices often make false determinations regarding touch status due to external objects like water drops or fingers, as capacitive coupling variations can fall outside predetermined thresholds even after the object is removed, leading to incorrect touch sensing status.
Innovation Solution
The method involves measuring initial and subsequent capacitive coupling amounts, calculating capacitive coupling variations, and using a flatness index within predetermined ranges to determine the touch status, preventing false determinations by updating reference data when conditions normalize.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the processor uses predetermined positive and negative thresholds to determine touch status based on capacitive coupling variation, then the touch sensing device can detect external objects like fingers, but it will make false determinations when water drops or other external objects are present
Solution Approach 1:
The patent changes the determination parameters from simple capacitive coupling variation thresholds to a flatness index calculation. The flatness index is computed by dividing the capacitive coupling variation by the sum of absolute variations of adjacent sensing points, creating a normalized parameter that accounts for local variations and eliminates false determinations caused by water drops or other external objects.
Solution Approach 2:
The patent introduces the flatness index as an intermediary parameter between the raw capacitive coupling variation and the touch status determination. This intermediary parameter processes the raw data through a specific calculation formula that considers local variations, serving as a mediator that filters out false signals before the final determination is made.
2Adaptability or versatility
If the processor updates reference 2D sensing information when external objects like water drops are present, then the reference data is updated, but subsequent touch detections become inaccurate because the reference already includes the external object's effect
Solution Approach 1:
The patent implements a feedback mechanism where the flatness index determination results feed back into the reference updating process. When the flatness index indicates no touch (even if capacitive coupling variation exceeds thresholds), the system feeds back a signal to prevent reference data updates, ensuring the reference remains accurate and free from external object contamination.
3Device complexity
If the processor uses simple capacitive coupling variation thresholds for touch determination, then the device complexity is low, but the measurement precision deteriorates due to false determinations from external objects
Solution Approach 1:
The patent transforms the simple threshold comparison parameter into a more sophisticated flatness index parameter. The transformation involves calculating the ratio of capacitive coupling variation to the sum of absolute variations of adjacent sensing points, which maintains computational feasibility while dramatically improving measurement precision and eliminating false determinations.
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 prevents false touch control determinations by ensuring accurate assessment of touch status, even after external objects are removed, by using a flatness index within specific reference values to confirm no external object is present.
Implementation Method 1
the driving and sensing circuit A12 of the touch sensing device A1 measures the capacitive coupling amount (such as the current value, voltage, capacitor or electrical charge amount) at each of all the sensing points A113 between the driving lines A111 and sensing lines A112
Data Source
AI summary
The present disclosure relates to a touch control device and touch determination method thereof. When a processor determines a capacitive coupling variation of a sensing point at a sensing panel of the touch sensitive device is smaller than a predetermined negative threshold or larger than a predetermined positive threshold, the processor then computes from local 2D sensing information of second 2D sensing information measured at the sensing point, to obtain a flatness index, The processor determine that the sensing point is not touched by any external object if the flatness index is between a predetermined flatness index negative reference value and a predetermined flatness index positive reference value that indicates the capacitive coupling amount at the sensing point is changed by the sensing point is not touched by any external object, whereby a false touch control determination due to removing water drop on the touch sensing panel can be prevented.