Secure Touchscreen Assembly with Segmented Conductive Grids

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Solution Overview

Problem

Touchscreen devices in point-of-sale systems face security vulnerabilities as they lack effective separation between touch detection and tamper detection grids, making them susceptible to unauthorized access and tampering.

Innovation Solution

The implementation of a secure touchscreen assembly with separate patterned conductive layers for touch sensing and tamper sensing, where each layer includes a grid for detecting touches and tampering, respectively, and is electrically insulated from the other, utilizing tamper sensing circuitry to monitor changes in conductivity for tamper detection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single patterned conductive layer is used for both touch detection and tamper detection, then device complexity is reduced, but security reliability deteriorates due to inability to distinguish between user inputs and tampering attempts

Engineering Contradiction:
Improvestructure complexityVSAvoidsecurity reliability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The conductive layer is segmented into two separate patterned conductive layers: a first patterned conductive layer for touch detection and a second patterned conductive layer for tamper detection. Each layer is electrically insulated from the other, allowing independent operation and distinct detection functions, thereby resolving the contradiction between structural simplicity and security reliability.

Inventive Principle:
Principle #1Segmentation

2Manufacturing precision

If the touch sensing grid and tamper sensing grid are physically contact with each other, then manufacturing precision requirements are reduced, but the ability to detect tampering independently deteriorates

Engineering Contradiction:
Improvealignment precisionVSAvoidtamper detection reliability
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

An electrically insulative layer is introduced as an intermediary between the first patterned conductive layer and the second patterned conductive layer. This insulative layer prevents electrical contact while maintaining mechanical stability and alignment, allowing the grids to be positioned close together without compromising either manufacturing precision or independent tamper detection capability.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Quantity of substance

If the tamper sensing grid is disposed only where the touch sensing grid is present, then material usage is reduced, but coverage for tamper detection is insufficient

Engineering Contradiction:
Improveconductive material quantityVSAvoidtamper detection coverage
Core Design Contradiction:
Quantity of substanceVSReliability

Solution Approach 1:

The second patterned conductive layer for tamper detection is disposed in areas where the first patterned conductive layer for touch detection is not present, creating complementary coverage. This local differentiation ensures that tamper detection is enhanced in regions where touch detection is not required, optimizing both material usage and detection coverage by assigning different functions to different spatial locations.

Inventive Principle:
Principle #3Local quality

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

Enhances the security of touchscreen devices by effectively distinguishing between user inputs and potential tampering attempts, thereby preventing unauthorized access and ensuring the integrity of the system.

Implementation Method 1

tamper sensing circuitry coupled to the first tamper sensing grid for detecting a tamper by detecting a change in conductivity in the first tamper sensing grid

Methodology Applied
Scientific EffectElectrical conductivity change detection: Conduction (electrical)

Implementation Method 2

an electrically insulative layer disposed between the first patterned conductive layer and the second patterned conductive layer

Methodology Applied
Scientific EffectElectrical insulation: Dielectric

Data Source

PatentEP3396502B1Secure touchscreen device
Publication Date: 2020.10.28 VERIFONE INC
  • EP3396502B1 patent drawingFigure 1
  • EP3396502B1 patent drawingFigure 2A
  • EP3396502B1 patent drawingFigure 2B

AI summary

Disclosed is a touchscreen assembly, particularly a touch screen forming part of a point of sale device. The touchscreen assembly comprises a first patterned conductive layer (190) comprising a first touch sensing grid (192) and a first tamper sensing grid (196), the first tamper sensing grid (196) is disposed in areas of the first patterned conductive layer (190) where the first touch sensing grid (192) is not present and is not in physical contact with the first touch sensing grid (192). A tamper sensing circuitry (148) is coupled to the first tamper sensing grid (196) that detects a tamper by detecting a change in conductivity in the first tamper sensing grid (196). This invention improves the security of touchscreen devices.