Capacitive Proximity Sensor for Occupancy Detection

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Solution Overview

Problem

Existing proximity sensing technologies rely on line-of-sight, unreliable weight measurements, or physical contact, which are not effective for detecting occupancy, especially in applications like child vehicle seats or home monitoring, and fail to provide a reliable detection range through materials like fabric or clothing.

Innovation Solution

A capacitive proximity sensor with a dual-plate capacitor design, featuring a ground plane and electrode loop that generates a uniform electric field, allowing for detection of objects up to 1-2 inches away without physical contact, and is flexible enough to be placed in curved areas, such as child seats, using a flexible printed circuit board and wireless communication for automated detection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If line-of-sight sensing (camera images) is used, then detection can be performed, but it requires direct visual contact and cannot detect through materials like fabric or clothing

Engineering Contradiction:

Improvedetection reliabilityVSAvoiddetection through materials

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent replaces optical line-of-sight sensing with capacitive sensing that detects changes in electrical field capacitance. This substitution allows detection through non-conductive materials like fabric and clothing, eliminating the limitation of requiring direct visual contact while maintaining detection reliability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If weight measurement is used, then occupancy detection can be performed, but it provides unreliable measurements

Engineering Contradiction:

Improveoccupancy detection reliabilityVSAvoidweight measurement precision

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent replaces mechanical weight measurement with capacitive sensing that measures changes in electrical field properties. This substitution provides more reliable occupancy detection by measuring the capacitive effect of the human body on the electric field, which is not subject to the same reliability and precision issues as weight-based systems.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If physical contact with sensor is required, then detection can be performed, but it reduces ease of operation and requires manual activation

Engineering Contradiction:

Improvedetection accuracyVSAvoidmanual activation requirement

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The capacitive sensor automatically detects occupancy through the capacitive effect of the human body on the electric field, eliminating the need for manual activation or physical contact with the sensor. The system serves itself by continuously monitoring capacitance changes and automatically determining occupancy status.

Inventive Principle:

Principle #25Self-service

4Manufacturing precision

If rigid sensor structure is used, then manufacturing precision can be maintained, but flexibility and adaptability to curved surfaces are reduced

Engineering Contradiction:

Improvesensor fabrication precisionVSAvoidflexibility for curved surfaces

Core Design Contradiction:

Manufacturing precisionVSAdaptability or versatility

Solution Approach 1:

The patent implements the capacitive sensing elements on flexible printed circuit boards, allowing the sensor to conform to curved surfaces like child seat contours while maintaining manufacturing precision through standardized PCB fabrication processes.

Inventive Principle:

Principle #30Flexible shells and thin films

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 capacitive proximity sensor provides improved detection range and flexibility, enabling reliable occupancy detection in various applications, including child safety, home monitoring, and industrial uses, while reducing the need for manual activation and improving sensitivity through statistical analysis of capacitance changes.

Implementation Method 1

an electrode loop disposed adjacent to and substantially coplanar with the ground plane to form an electric field in response to the input signal

Methodology Applied

Scientific EffectCapacitive coupling: Capacitance

Implementation Method 2

form an electric field in response to the input signal

Methodology Applied

Scientific EffectElectric field: Electric Field

Data Source

PatentUS11112521B2Capacitive proximity sensing

Publication Date: 2021.09.07 INTEL CORP

AI summary

A capacitive proximity sensor may include a proximity sensing capacitor to provide a voltage output based on a voltage input, the capacitor including a ground plane and an electrode loop capacitively coupled to the ground plane. The proximity sensor may include a processor to detect an object proximity based on a change in the voltage output. This proximity sensor provides automated detection of a person, and thereby reduces the need for a vehicle occupant or child caregiver to activate a sensor by pressing a button. The use of a capacitance-based proximity sensor reduces issues associated with fabric, clothing, or other materials separating the proximity sensor from a person.