Capacitive Input Surface Correction for Non-Uniform Press Detection

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Solution Overview

Problem

Tactile force sensing devices fail to accurately determine the presence of a pressing operation on a sensor operating surface with non-uniform hardness, leading to inconsistent detection criteria.

Innovation Solution

An input device with a foam layer having varying hardnesses and an electrostatic sensor that corrects electrostatic capacitance values using specific correction factors to align outputs across different hardness regions, allowing consistent detection based on fixed criteria.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a tactile force sensing device uses a sensor operating surface with non-uniform hardness, then the device can provide varied tactile feedback, but it becomes impossible to determine presence of a pressing operation based on fixed criteria

Engineering Contradiction:

Improvetactile feedback variationVSAvoidpressing operation detection accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent divides the sensor operating surface into multiple regions with different hardness characteristics. Each region is associated with a specific correction value that compensates for its local hardness properties. When a pressing operation is detected, the system identifies which region is activated and applies the corresponding correction value to the electrostatic capacitance value, enabling accurate detection despite hardness variations across different areas.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent introduces correction values as adjustable parameters that modify the electrostatic capacitance values based on the hardness characteristics of different regions. By changing the parameter (correction value) according to the location on the sensor operating surface, the system compensates for hardness variations and maintains consistent pressing operation detection criteria across all regions.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If the sensor operating surface has uniform hardness, then pressing operations can be detected using fixed criteria, but the device lacks the ability to provide differentiated tactile feedback across different regions

Engineering Contradiction:

Improvepressing operation detection consistencyVSAvoidtactile feedback differentiation

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The patent assigns different correction values to different regions of the sensor operating surface, creating local quality variations that enable differentiated tactile feedback. Each region's correction value is tailored to its specific hardness characteristics, allowing the device to provide customized tactile responses while maintaining accurate pressing operation detection through the application of appropriate correction factors.

Inventive Principle:

Principle #3Local quality

3Measurement precision

If correction values are applied to electrostatic capacitance values, then consistent pressing operation detection is achieved across regions with different hardness, but the device complexity increases

Engineering Contradiction:

Improvepressing operation detection accuracyVSAvoidcorrection system complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent pre-calculates and stores correction values for each region of the sensor operating surface before actual operation. These correction values are determined in advance based on the hardness characteristics of each region. During operation, the system simply retrieves and applies the appropriate pre-computed correction value, avoiding the need for complex real-time calculations and reducing operational complexity while maintaining detection accuracy.

Inventive Principle:

Principle #10Preliminary 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

Enables consistent detection of pressing operations regardless of surface hardness variations, providing uniform tactile feedback and accurate operation determination.

Implementation Method 1

an electrostatic sensor configured to detect an electrostatic capacitance value that changes in response to a displacement of the input section

Methodology Applied

Scientific EffectElectrostatic capacitance: Capacitance

Data Source

PatentUS20260072546A1Input device

Publication Date: 2026.03.12 ALPS ALPINE CO LTD

AI summary

An input device includes an input section having an operating surface to be operated by a manipulating body, detection electrodes provided on a back side of the operating surface, a measurement unit that measures an electrostatic capacitance value of each of the detection electrodes, and a correction unit that corrects the electrostatic capacitance value of each of the detection electrodes measured by the measurement unit. The input section includes portions where displacements with respect to a pressing operation on the operating surface by the manipulating body with a predetermined pressing force differ depending on positions on the operating surface. The correction unit corrects the electrostatic capacitance value of each of the detection electrodes using smaller correction values for cases where a displacement caused by the pressing operation performed at pressing positions overlapping the detection electrodes on the operating surface in a plan view becomes larger.