Capacitive Input Device Reference Value Correction

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Solution Overview

Problem

Existing electrostatic capacitance-type input devices face erroneous operations due to environmental changes and substrate deformation, leading to incorrect detection of finger position, especially in devices with resin substrates exposed to temperature variations.

Innovation Solution

An input device with a control unit that updates a reference value based on electrostatic field variations, determining the difference between detection values and a predetermined range to correct for erroneous operations by adjusting the reference value when the detection state is consistent, thereby preventing false detection outputs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the input device uses electrostatic capacitance detection to achieve high sensitivity finger position detection, then detection sensitivity is improved, but erroneous operations occur due to environmental changes and substrate deformation

Engineering Contradiction:

Improvedetection sensitivityVSAvoidoperational accuracy

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The control unit performs preliminary actions by detecting whether the finger has approached the input device before executing operations. It pre-judges the detection state and only updates the reference value when certain conditions are met, preventing erroneous operations from being processed while maintaining high detection sensitivity.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system implements feedback by continuously monitoring the detection value and comparing it with the reference value. When the difference exceeds a predetermined threshold, the control unit updates the reference value. This feedback mechanism allows the system to adapt to environmental changes and substrate deformation while maintaining operational accuracy.

Inventive Principle:

Principle #23Feedback

2Reliability

If the reference value is updated frequently to adapt to environmental changes, then operational accuracy is improved, but false updates occur when the finger is not actually operating the device

Engineering Contradiction:

Improveoperational accuracyVSAvoidfalse detection updates

Core Design Contradiction:

ReliabilityVSLoss of information

Solution Approach 1:

The control unit performs preliminary detection to determine whether the finger has actually approached the input device before allowing reference value updates. This pre-judgment mechanism ensures that only legitimate user interactions trigger reference value updates, preventing false updates from environmental changes or substrate deformation.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system replaces simple threshold-based updates with a more sophisticated evaluation mechanism that considers the detection value, reference value, and predetermined thresholds. This substitution allows the system to distinguish between legitimate user input and false signals from environmental changes, reducing false updates while maintaining adaptability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If the detection threshold is set low to detect subtle electrostatic field variations, then detection sensitivity is improved, but erroneous operations increase due to substrate expansion or deformation

Engineering Contradiction:

Improvedetection sensitivityVSAvoiderroneous operations from temperature changes

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The system uses feedback by continuously comparing the detection value with the reference value and updating the reference value when the difference exceeds a predetermined threshold. This feedback mechanism allows the system to distinguish between subtle legitimate inputs and larger variations caused by temperature changes or substrate deformation, maintaining sensitivity while filtering out erroneous operations.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system changes the parameter for reference value updates based on the relationship between detection values and reference values. By dynamically adjusting when updates occur (only when the difference exceeds the threshold), the system maintains high detection sensitivity for subtle variations while ignoring larger variations caused by environmental factors like temperature changes.

Inventive Principle:

Principle #35Parameter changes

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 solution effectively prevents erroneous operations by updating the reference value, allowing for high sensitivity detection of finger input and reducing false positives caused by substrate expansion or deformation due to temperature changes.

Implementation Method 1

when a finger of the user touches the coordinate input device and the device is pushed, the electrostatic field between the X electrodes and Y electrodes is varied, and a voltage change due to the variation in the electrostatic field is output from each of the Y electrodes

Methodology Applied

Scientific EffectElectrostatic field variation: Electrostatics

Data Source

PatentUS7834860B2Input device

Publication Date: 2010.11.16 ALPS ALPINE CO LTD

AI summary

An electrostatic capacitance type input device includes a plurality of electrodes, and detects coordinate position on the basis of a variation in an electrostatic capacitance between the electrodes. The device corrects an erroneous operation in which the device is not properly operated but certain coordinate positions are continuously detected.