Touch Noise Filtering via Capacitance Difference Restoration

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Solution Overview

Problem

In integrated capacitive touch panels with liquid crystal panels, noise interference from OLED circuits affects sensing accuracy, leading to incorrect touch point identification due to increased capacitance and noise signals.

Innovation Solution

A method involving a touch device with a processing unit that calculates capacitance difference values and restoration signals for touch electrodes, reducing noise interference by subtracting connection capacitance values and adding capacitance difference values to restore accurate capacitance values for improved sensing accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the capacitive touch panel is integrated with the liquid crystal panel using in-cell or on-cell methods, then the integration and compactness are improved, but noise interference from OLED circuits increases causing sensing accuracy to deteriorate

Engineering Contradiction:

Improveintegration of touch panel and liquid crystal panelVSAvoidsensing accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent segments the capacitance measurement process into multiple scanning cycles, separating the measurement of different electrode groups. By alternately selecting and measuring adjacent electrode groups in different cycles, the system isolates the capacitance values of individual electrodes from the noise interference, enabling accurate touch detection despite the integrated structure's electromagnetic interference.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent changes the measurement parameters by performing multiple scanning cycles with alternating electrode group selections. The capacitance values are measured under different cycle conditions, and through comparative analysis of these varying measurements, the system extracts accurate capacitance data while filtering out the noise interference inherent in the integrated display structure.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If multiple scanning cycles are performed to measure capacitance values, then the accuracy of touch detection is improved, but the time consumption increases

Engineering Contradiction:

Improvetouch detection accuracyVSAvoidtime consumption

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent performs multiple scanning cycles, which is more than the single cycle that would be sufficient for basic measurement. This excessive action ensures that capacitance values are accurately captured despite noise interference, with the multiple cycles providing redundant measurements that can be analyzed to filter out anomalies and confirm accurate touch detection.

Inventive Principle:

Principle #16Partial or excessive action

Solution Approach 2:

The patent implements periodic scanning cycles that alternately measure different electrode groups. This periodic measurement approach allows the system to collect capacitance data from multiple time points, enabling the identification of consistent patterns that indicate genuine touch events versus random noise, thereby improving accuracy while managing time consumption through structured periodic measurement.

Inventive Principle:

Principle #19Periodic action

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

The method effectively reduces noise interference, enhancing the sensing accuracy of touch panels by isolating noise signals and calculating corrected capacitance values for precise touch point detection.

Implementation Method 1

For a capacitive touch panel, capacitive changes resulted from electrostatic contact between transparent electrodes and human body occur, and the coordinates of touch points are detected according to current or voltage generated due to the capacitive changes.

Methodology Applied

Scientific EffectCapacitive changes: Capacitance

Implementation Method 2

capacitive changes resulted from electrostatic contact between transparent electrodes and human body occur

Methodology Applied

Scientific EffectElectrostatic contact: Electrostatics

Data Source

PatentUS10331281B2Method for filtering touch noise and touch device

Publication Date: 2019.06.25 EVERDISPLAY OPTRONICS (SHANGHAI) CO LTD

AI summary

The present disclosure relates to a method for filtering touch noise and a touch device. The method includes: when normal signals for at least one row of the touch electrodes are input to the touch panel, obtaining a standard capacitance value of each of the touch electrodes, and obtaining a connection capacitance value of each of the touch electrodes; for each of the touch electrodes: subtracting a connection capacitance value of another touch electrode, which is in the same row with and adjacent to the touch electrode in a first direction, from the connection capacitance value of the touch electrode to obtain a capacitance difference value; from the last touch electrode, calculating the capacitance value of the restoration signal for each touch electrode along a second direction opposite to the first direction. Coordinates are calculated according to the capacitance values of the restoration signals for individual touch electrodes.