Piezo Touch Sensor Assembly With Oxidation-Resistant Contacts

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Solution Overview

Problem

Conventional touch sensors for metal panels, such as refrigerator doors, face challenges in reliability due to oxidation of piezo disks and substrates, leading to electrical contact failures, and require complex sealing structures that increase costs and reduce productivity.

Innovation Solution

A touch sensor assembly with a piezo disk and touch substrate, where oxidation prevention films made of conductive materials like carbon or gold are used to prevent oxidation, eliminating the need for a sealing structure and enhancing durability and sensitivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a sealing structure is formed to prevent oxidation of connectors and piezo disk, then reliability is improved, but device complexity and manufacturing cost increase

Engineering Contradiction:
Improveelectrical connection reliabilityVSAvoidsealing structure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies oxidation prevention films made of inexpensive materials such as carbon or gold to the piezo disk and substrate surfaces. These films provide oxidation protection without requiring complex sealing structures, thereby maintaining reliability while reducing device complexity and manufacturing cost. The films are applied directly to the surfaces that would otherwise be exposed to oxidation, eliminating the need for elaborate sealing mechanisms.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

2Reliability

If a sealing structure is formed to prevent oxidation, then reliability is improved, but productivity decreases

Engineering Contradiction:
Improveelectrical connection reliabilityVSAvoidmanufacturing productivity
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The oxidation prevention films can be applied through simple coating processes rather than requiring complex sealing assembly steps. This significantly reduces manufacturing complexity and improves productivity while still providing effective oxidation protection. The films are integrated into the manufacturing process in a straightforward manner, eliminating time-consuming sealing operations.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

3Ease of manufacture

If metal connectors are exposed to air, then manufacturing is simpler, but oxidation occurs causing electrical connection failure

Engineering Contradiction:
Improveconnector manufacturing simplicityVSAvoidelectrical connection reliability
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent applies thin oxidation prevention films made of carbon or gold to the metal connectors and piezo disk surfaces. These films are applied directly during manufacturing without requiring complex sealing structures, thereby maintaining manufacturing simplicity while preventing oxidation. The films create a protective barrier that preserves electrical connection reliability without complicating the manufacturing process.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

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 ensures reliable touch operation sensing, prevents electrical contact failures, reduces manufacturing complexity and costs, and improves productivity by using oxidation prevention films on the piezo disk and touch substrate, while maintaining high sensitivity and robustness.

Implementation Method 1

a piezo disk having first and second poles stacked on a touch substrate... when force applied upon touch is large or the number of times of pressing a button is increased, a pressing portion and the periphery thereof may be damaged with time

Methodology Applied
Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentEP3419175B1Touch sensor assembly
Publication Date: 2020.08.19 LG ELECTRONICS INC
  • EP3419175B1 patent drawingFigure 1
  • EP3419175B1 patent drawingFigure 2
  • EP3419175B1 patent drawingFigure 3

AI summary

A touch sensor assembly includes a touch substrate attached to a rear surface of a panel having a touch point, a piezo disk having first and second poles stacked thereon, a pressing part flexibly provided on the touch substrate, electrically connected to the first pole upon being in contact with the first pole, and electrically connected to a wiring provided on the touch substrate, a fixing surface electrically connected to the second pole while supporting the second pole such that the piezo disk is fixed to the rear surface of the touch substrate and electrically connected to second wirings provided on the touch substrate, and an oxidation prevention film coated on at least one of the first pole or the second pole of the piezo disk and the pressing part or the fixing surface of the touch substrate and made of a conductive material.