Capacitive Touch Interface for Smart Card Authentication

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Solution Overview

Problem

Smart cards lack a user interface for entering credentials, making them vulnerable to credential interception by malicious software, and integrating a touch-based user interface is difficult and expensive due to form factor and manufacturing constraints.

Innovation Solution

An electronic device with a non-conductive substrate and a touch-based user interface unit featuring a capacitive sensor structure formed by embedding conductive wires, which are arranged in patterns like meander or spiral and connected to a communication and processing module, allowing for a low-cost and efficient implementation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a touch-based user interface is integrated into a smart card, then user authentication security is improved, but manufacturing cost and complexity increase

Engineering Contradiction:

Improveauthentication securityVSAvoidmanufacturing complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical touch interface structures with a capacitive sensor structure formed by conductive wires embedded in the substrate. This substitution eliminates the need for physical buttons, membranes, or complex assembly processes, thereby reducing manufacturing complexity while maintaining authentication security through capacitive sensing.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the physical state and arrangement of conductive materials to create functional capacitive sensors. By embedding conductive wires in specific patterns (meander, spiral, grid) and arranging them at defined distances and orientations, the system transforms simple conductive elements into functional sensing components that detect touch inputs.

Inventive Principle:

Principle #35Parameter changes

2Ease of operation

If traditional touch interface components are used, then user interface functionality is achieved, but manufacturing cost increases

Engineering Contradiction:

Improveuser interface functionalityVSAvoidmanufacturing cost

Core Design Contradiction:

Ease of operationVSEase of manufacture

Solution Approach 1:

The patent uses simple, inexpensive conductive wires and standard substrate materials to create the touch interface. Instead of using costly components like touch screens, buttons, or membranes, the invention employs basic conductive elements that can be easily embedded in the substrate during standard manufacturing processes, significantly reducing component and assembly costs.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent merges the capacitive sensor functionality directly into the substrate structure itself, eliminating the need for separate touch interface components. The conductive wires are embedded within the substrate during the same manufacturing process, combining multiple functions (structural support, electrical connection, and touch sensing) into a single integrated component.

Inventive Principle:

Principle #5Merging (Combining)

3Ease of manufacture

If conductive wires are embedded in the substrate, then manufacturing cost is reduced, but manufacturing precision requirements increase

Engineering Contradiction:

Improvemanufacturing costVSAvoidwire embedding precision

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent performs preliminary actions by pre-forming the conductive wire patterns (meander, spiral, or grid) before embedding them in the substrate. The wires are arranged and positioned in advance according to predetermined designs, which simplifies the subsequent embedding process and reduces the precision requirements during final assembly. This staged approach allows for easier manufacturing while maintaining functional accuracy.

Inventive Principle:

Principle #10Preliminary action

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 a secure and user-friendly authentication method for smart cards, enhancing end-user acceptance by reducing the risk of credential interception and improving production efficiency while eliminating the need for expensive etched inlays.

Implementation Method 1

a touch-based user interface unit having a capacitive sensor structure, wherein said capacitive sensor structure comprises conductive wires embedded in the non-conductive substrate

Methodology Applied

Scientific EffectCapacitance: Capacitance

Data Source

PatentUS11100380B2Electronic device

Publication Date: 2021.08.24 NXP BV

AI summary

According to a first aspect of the present disclosure an electronic device is provided, which comprises a non-conductive substrate and a touch-based user interface unit having a capacitive sensor structure, wherein said capacitive sensor structure comprises conductive wires embedded in the non-conductive substrate. According to a second aspect of the present disclosure a corresponding method of manufacturing an electronic device is conceived.