Piezo-Disc Touch Sensor Assembly for Metallic Refrigerator Panels

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Solution Overview

Problem

Refrigerators with metallic front panels face challenges in integrating touch sensors due to static electricity leakage and the difficulty in applying buttons that require constant pressure, making it hard to achieve a hidden touch sensing mechanism that is both aesthetically pleasing and functional.

Innovation Solution

A touch sensor assembly is designed with a simple structure and few parts, using a touch board and piezo discs attached to the rear side of a metallic panel via adhesive members and support members, allowing for high sensitivity and durability against repetitive inputs, while maintaining a sleek appearance by hiding the touch points until in use.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If electrostatic touch sensors are applied to metallic refrigerator doors, then touch sensing function is achieved, but static electricity leakage occurs causing unreliable sensing

Engineering Contradiction:
Improvetouch sensing functionVSAvoidsensing reliability
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent introduces an intermediary mechanism (mechanical touch structure with movable panel section) between the user and the metallic panel to transfer touch input without direct electrical contact, thereby avoiding static electricity leakage issues while maintaining reliable sensing on metallic surfaces

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces the electrostatic sensing mechanism with a mechanical touch detection system that uses physical displacement of a panel section to trigger sensing, substituting electrical field-based detection with mechanical movement-based detection to eliminate static electricity interference

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Ease of operation

If constant pressure buttons are applied to metallic panels, then button function is achieved, but difficulty in application occurs due to metal resistance to flexure

Engineering Contradiction:
Improvebutton functionVSAvoidapplication difficulty
Core Design Contradiction:
Ease of operationVSEase of manufacture

Solution Approach 1:

The patent divides the panel into a fixed section and a movable section, allowing the movable section to flex independently under touch pressure while the fixed section remains stable, thereby enabling button functionality on metallic panels without requiring the entire panel to be flexible

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies flexibility only to the specific region where button input is needed (movable panel section) while maintaining rigidity in other areas, creating localized tactile feedback without compromising the overall structural integrity of the metallic panel

Inventive Principle:
Principle #3Local quality

3Ease of operation

If touch buttons are displayed on metallic front panels, then user interaction is enabled, but aesthetic appearance deteriorates due to visible buttons and display

Engineering Contradiction:
Improveuser interactionVSAvoidaesthetic appearance
Core Design Contradiction:
Ease of operationVSShape

Solution Approach 1:

The patent implements a dynamic display mechanism where the panel section transitions between a flat aesthetic state and a depressed interactive state, allowing the interface to adapt its appearance based on user interaction while maintaining visual appeal during non-use periods

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent embeds the touch input mechanism within the metallic panel itself through a movable section that integrates seamlessly with the panel's surface, creating a nested structure where the functional element is concealed within the aesthetic shell until activation

Inventive Principle:
Principle #7Nested doll (Nesting)

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 provides reliable touch sensing on metallic panels with high sensitivity and durability, allowing for a hidden button mechanism that enhances user interaction without compromising the appliance's aesthetic appeal.

Implementation Method 1

piezo discs which have a first electrode and a second electrode disposed thereon in an overlapping manner

Methodology Applied
Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentEP3287725B1Refrigerator having touch sensor assembly
Publication Date: 2021.09.29 LG ELECTRONICS INC
  • EP3287725B1 patent drawingFigure 1
  • EP3287725B1 patent drawingFigure 2
  • EP3287725B1 patent drawingFigure 3

AI summary

An appliance according to an implementation of the present disclosure includes: a front panel that forms the external shape of the appliance and has touch point; a touch board that includes: a first side attached to a position of a rear surface of the front panel, the position corresponding to the touch point; and a second side opposite to the first side; a pressing portion; and holes formed around the pressing portion; a holder that is disposed at a position covering the pressing portion and the holes and coupled to the second side of the touch board, the holder having a receiving portion; a piezo disc that is inserted in the receiving portion of the holder and has a first electrode and a second electrode to be in contact with the pressing portions; a guide board that has a seating hole for receiving the holder and the piezo disc and is disposed on the second side of the touch board; and an adhesive member that is attached to the first side of the touch board.