Capacitive Touch Panel Dual-Threshold Detection for Deformation

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Solution Overview

Problem

Capacitive touch panels with an air layer between the touch panel and the front panel are prone to erroneous operations where measurement values decrease and eventually disappear due to deformation under load, causing incorrect detection of touch events.

Innovation Solution

Implementing a reference value system with two threshold values to differentiate between signal intensity increases and decreases, ensuring that even significant changes in measurement values due to deformation are treated as valid signals, preventing the disappearance of measurement values.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of repair

If an air layer is provided between the touch panel and the front panel, then ease of repair and cost reduction are improved, but measurement accuracy deteriorates due to deformation under load causing erroneous operations

Engineering Contradiction:
Improveease of repairVSAvoidmeasurement accuracy
Core Design Contradiction:
Ease of repairVSMeasurement precision

Solution Approach 1:

The patent changes the detection parameters by introducing two threshold values (first threshold and second threshold) instead of a single threshold. This allows the system to detect touch events even when measurement values decrease due to deformation, as the dual-threshold mechanism can identify valid touch signals that would otherwise be rejected by a conventional single-threshold system.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent implements dynamic threshold adjustment based on the detection state. The system dynamically determines whether to use the first threshold or second threshold based on the current measurement value and its change pattern, allowing adaptive response to deformation conditions while maintaining accurate touch detection.

Inventive Principle:
Principle #15Dynamics

2Stability of the object's composition

If the front panel is bonded to the touch panel with adhesive, then structural stability is improved, but replacement complexity increases when the front panel needs to be replaced

Engineering Contradiction:
Improvestructural stabilityVSAvoidreplacement complexity
Core Design Contradiction:
Stability of the object's compositionVSEase of repair

Solution Approach 1:

The patent segments the touch display assembly into separable components: the touch panel and the front panel are kept as independent modules with an air layer between them. This segmentation allows the front panel to be replaced independently without replacing the entire touch panel assembly, significantly reducing repair complexity and cost.

Inventive Principle:
Principle #1Segmentation

3Device complexity

If a single threshold value is used for touch detection, then device complexity is reduced, but reliability deteriorates when deformation causes measurement values to disappear

Engineering Contradiction:
Improvedetection system complexityVSAvoidtouch detection reliability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent implements a feedback mechanism where the system continuously monitors measurement values and their changes, compares them against dynamically selected thresholds, and adjusts detection decisions based on this feedback. This feedback loop ensures reliable touch detection even when measurement values fluctuate due to deformation, as the system can distinguish between valid touch signals and deformation-induced variations.

Inventive Principle:
Principle #23Feedback

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

Prevents erroneous operations by maintaining accurate detection of touch events even under deformation, enhancing the reliability and usability of capacitive touch panels with an air layer.

Implementation Method 1

a capacitive touch panel provided on a display panel

Methodology Applied
Scientific EffectElectrostatic capacitance: Capacitance

Implementation Method 2

a capacitance of each electrode is detected by an input processing part. When a conductor such as a finger touches a surface of the touch panel, the capacitance of each electrode increases.

Methodology Applied
Scientific EffectElectrostatic capacitance detection: Capacitance

Implementation Method 3

the object to be sensed (finger or conductor) acts as an electrostatic shield for blocking lines of electric force between the intersections of the X electrodes and the Y electrodes

Methodology Applied
Scientific EffectElectrostatic shield: Electrostatics

Data Source

PatentEP2437146B1Display device equipped with touch panel
Publication Date: 2017.07.19 PANASONIC LIQUID CRYSTAL DISPLAY CO LTD
  • EP2437146B1 patent drawingFigure 1
  • EP2437146B1 patent drawingFigure 2
  • EP2437146B1 patent drawingFigure 3A~3B

AI summary

Provided is a display device equipped with a touch panel, including a front panel (12) arranged above a capacitive touch panel (400) at a predetermined distance away therefrom, in which the touch panel includes a plurality of X electrodes and a plurality of Y electrodes, and the X electrodes are sequentially applied with pulse signals and the Y electrodes receive the pulse signals. When an arbitrary point on the front panel (12) is touched, the touch panel computes a touched point on the touch panel by using both the received pulse signals obtained from the Y electrodes in a case where the front panel (12) is not deformed and the received pulse signals obtained from the Y electrodes in a case where the front panel is deformed. With this, an erroneous operation in which a measurement value is lowered to finally disappear is prevented.