Washing Machine Door Lock Resistance Sensing Against Moisture Errors

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

The existing door lock switch in washing machines is prone to detection errors due to moisture permeation, leading to incorrect on/off signal detection and potential safety hazards when the door is not fully closed, as moisture causes short circuits between lock and unlock contacts.

Innovation Solution

An apparatus that uses a variable resistance meter connected to a gear system within the door lock switch, which outputs a resistance value varying with the lever position, allowing a detection unit to accurately determine the door's opening and closing state, thereby preventing power activation when the door is not fully closed.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a door lock switch with lock/unlock contacts is used to detect door opening and closing, then the door can be locked securely during operation, but moisture permeation causes short circuits between contacts leading to detection errors

Engineering Contradiction:

Improvedoor detection reliabilityVSAvoidmoisture-induced short circuit

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the mechanical contact-based door lock switch with a non-contact sensor system. Specifically, it uses a magnet attached to the door and a corresponding sensor on the main body that detects the magnet's position without physical contact. This eliminates the short circuit problem caused by moisture while maintaining reliable door state detection through magnetic field interaction instead of electrical contact.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Device complexity

If lock/unlock contacts are used for door detection, then the door lock function is achieved, but the structure becomes complex and prone to detection errors

Engineering Contradiction:

Improvedoor lock switch structureVSAvoiddetection accuracy

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent eliminates the complex mechanical contact structure by using a magnetic detection system. A magnet is attached to the door, and a sensor on the main body detects the magnet's position to determine door state. This non-contact approach simplifies the structure by removing multiple contact points, springs, and housing components while improving reliability through contactless detection that is immune to moisture and wear.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If the door lock switch performs both door lock and power on/off functions, then safety is improved by preventing operation when door is open, but moisture causes erroneous detection leading to potential safety hazards

Engineering Contradiction:

Improvesafety controlVSAvoidmoisture permeation

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the moisture-vulnerable mechanical contact switch that controls both door locking and power functions with a non-contact magnetic sensor system. The sensor detects the door's position via magnetic field interaction, providing reliable input for both the door lock mechanism and the power control circuit. This eliminates erroneous detection caused by moisture while maintaining the integrated safety control function.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces a magnet as an intermediary element that mediates between the door and the sensor system. The magnet attached to the door creates a magnetic field that the sensor detects without physical contact, serving as an intermediary that transmits door position information while being immune to moisture interference. This intermediary approach allows reliable detection for safety control functions without the short circuit problems of direct electrical contacts.

Inventive Principle:

Principle #24Intermediary (Mediator)

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

This solution enhances the reliability of door detection, prevents erroneous power activation, and reduces material costs by simplifying the inner structure, eliminating the need for surface contact and thus minimizing moisture-induced detection errors.

Implementation Method 1

a variable resistance meter to output a resistance value of which varies according to movement of the locking lever

Methodology Applied

Scientific EffectElectrical Resistance: Electrical Resistance

Data Source

PatentUS9085845B2Apparatus to detect opening and closing of door in washing machine

Publication Date: 2015.07.21 SAMSUNG ELECTRONICS CO LTD

AI summary

An apparatus to detect opening and closing of a door in a washing machine by detecting a resistance value varying according to a lever position of a door lock switch. In the apparatus to detect opening and closing of a door in a washing machine, since a resistance meter is added to the inside of a component with the contact being eliminated therefrom, it may be possible to simplify an inner structure of the component and to reduce material costs. In addition, opening and closing of a door is accurately detected as a resistance value of the resistance meter varies by rotation of a gear instead of surface contact between contacts, and thus it may be possible to prevent a detection error in the event of contact short circuits due to moisture and to enhance component reliability.