Vehicle Door Handle Contact Sensing Against Water Droplet Misoperation

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Solution Overview

Problem

Smart key systems for vehicles struggle to differentiate between human contact and water droplets, leading to misoperations due to similar electrostatic capacitance readings, especially in rainy conditions, which complicates the design and increases manufacturing costs.

Innovation Solution

A contact sensing device with a comparator unit, sensing electrode, and determination unit that uses a guide groove to guide water droplets and compares sensing results with reference values to accurately distinguish between human contact and water droplets, preventing misoperations and reducing manufacturing costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If electrostatic capacity type lock sensor electrodes are used to enable contactless unlocking, then convenience is improved, but misoperation due to water droplet adhesion occurs

Engineering Contradiction:

Improvecontactless unlockingVSAvoidmisoperation prevention

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The sensing electrode is divided into multiple regions with different areas. By comparing the sensing results from these segmented regions, the system can distinguish between water droplets (which typically contact only part of the electrode) and human hands (which contact the entire electrode), thereby preventing misoperation while maintaining contactless unlocking capability

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the sensing electrode are designed with different areas to create local quality variations. This allows the system to detect spatial distribution patterns of capacitance changes, enabling differentiation between water droplets and human contact based on the local sensing characteristics of each region

Inventive Principle:

Principle #3Local quality

2Measurement precision

If multiple sensing electrodes with different areas are used to improve discrimination accuracy, then measurement precision is improved, but device complexity increases

Engineering Contradiction:

Improvehuman contact vs water droplet discriminationVSAvoidsensing electrode configuration

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The sensing electrode is segmented into multiple regions with different areas, allowing the system to detect spatial patterns of capacitance changes. This segmentation enables accurate discrimination between water droplets and human contact by analyzing which regions are activated, without requiring multiple separate sensing components

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A single sensing electrode structure serves multiple functions: it detects both the presence and spatial distribution of objects, distinguishes between different object types (water droplets vs hands), and provides sufficient information for accurate identification without requiring additional separate sensing elements

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 misoperations by accurately differentiating between human contact and water droplets, enhancing the reliability of smart key systems while reducing design complexity and manufacturing costs.

Implementation Method 1

electrostatic capacity type lock sensor electrodes

Methodology Applied

Scientific EffectElectrostatic capacitance: Capacitance

Implementation Method 2

change of stray capacitances generated between a lock sensor electrode and human bodies is merely sensed

Methodology Applied

Scientific EffectStray capacitance: Parasitic Capacitance

Data Source

PatentUS11280119B2Contact sensing device, proximity/contact sensing device, door handle device and control method of the door handle device, and electronic key system

Publication Date: 2022.03.22 ROHM CO LTD

AI summary

The door handle device includes: a contact sensing unit including a guide groove and a contact sensing electrode, the guide groove configured to guide a water droplet falling on a door, the contact sensing electrode disposed in the guide groove and configured to sense a contact with the door; a locking unit configured to execute unlocking and locking of a door; and a control unit configured to instruct to the locking unit to keep locking the door if determining that the water droplet is in contact with the door, on the basis of a sensing result by the contact sensing electrode. There are provided: a contact sensing device; a door handle device and a control method for such a door handle device; and an electronic key system, for preventing a misoperation due to a water droplet adhering to a door handle of vehicles, which has an electrostatic locking mechanism.