Reference-Input Capacitive Sensing for Environmental Drift Correction

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Solution Overview

Problem

Capacitive sensor devices in portable electronic devices suffer from drift due to environmental influences such as temperature and humidity changes, leading to faulty proximity signal detection.

Innovation Solution

A capacitive sensor device with a capacitance-measuring circuit and separate reference sense input, adaptively determining correction coefficients based on current and previously measured reference values to correct for environmental drift in real time, using various filtering and threshold-based methods to optimize drift compensation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If environmental drift compensation is implemented using fixed correction coefficients, then drift correction is achieved, but correction accuracy deteriorates under varying environmental conditions

Engineering Contradiction:

Improvedrift correction accuracyVSAvoidenvironmental condition adaptability

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The patent implements dynamic adaptation of correction coefficients based on current environmental conditions. The system continuously monitors environmental parameters and adjusts the correction coefficients in real-time, transitioning from static fixed coefficients to dynamic adaptive coefficients that respond to changing conditions, thereby resolving the contradiction between correction accuracy and environmental adaptability

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system employs feedback mechanisms where measured drift values from reference sensors are fed back to update and refine correction coefficients. This closed-loop approach allows the system to learn from past performance and continuously optimize correction accuracy while maintaining adaptability to new environmental conditions

Inventive Principle:

Principle #23Feedback

2Measurement precision

If multiple correction coefficients are stored for different environmental conditions, then correction accuracy improves, but device complexity increases

Engineering Contradiction:

Improvedrift correction accuracyVSAvoidcorrection coefficient management

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

Instead of managing multiple discrete correction coefficient sets, the system changes the parameter approach by using continuous environmental parameter measurements to dynamically calculate appropriate correction values. This transforms the problem from discrete coefficient selection to continuous parameter-based adjustment, reducing complexity while maintaining accuracy

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The system implements self-service through automatic adaptation where the capacitive sensor device autonomously determines and applies appropriate correction coefficients based on its own environmental measurements, eliminating the need for external calibration or manual coefficient management, thereby reducing operational complexity

Inventive Principle:

Principle #25Self-service

3Measurement precision

If real-time drift correction is performed, then measurement accuracy improves, but processing time and computational load increase

Engineering Contradiction:

Improvecapacitance measurement accuracyVSAvoidcorrection processing time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The system performs preliminary actions by pre-calculating and storing correction coefficient relationships or lookup tables for common environmental conditions. When real-time correction is needed, the system quickly retrieves or interpolates from these pre-prepared data structures, significantly reducing processing time while maintaining correction 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

Effectively removes environmental drift from capacitance measurements, enhancing the accuracy of proximity detection by compensating for temperature and other environmental changes.

Implementation Method 1

measure, using the capacitance-measuring circuit, a current main value of capacitance seen by the main sense input and a current reference value of capacitance seen by the reference sense input

Methodology Applied

Scientific EffectCapacitance: Capacitance

Data Source

PatentUS12474185B2Capacitive sensor device with drift compensation

Publication Date: 2025.11.18 SEMTECH CORP

AI summary

A capacitive sensor device with a capacitance-measuring circuit, a main sense input and a reference sense input, wherein the capacitive sensor device is configured to measure, using the capacitance-measuring circuit, a current main value of capacitance seen by the main sense input and a current reference value of capacitance seen by the reference sense input, wherein the capacitive sensor device is configured to store one previously measured reference value, and wherein the capacitive sensor device is configured to use 1) the current main value, 2) the current reference value and the previously measured reference value, and 3) a current correction coefficient, the capacitive sensor device being configured to adaptively determine the current correction coefficient based on the current reference value and the previously measured reference value, for determining a corrected current main value of capacitance; the capacitive sensor device can be used in a portable electronic device.