POS Terminal PIN Entry Using Audio and Hidden Keypad Cues

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Solution Overview

Problem

Existing authentication methods for PIN codes on touch screens are vulnerable to fraud due to visibility of the keypad, and solutions that attempt to address this issue either increase terminal size or are susceptible to camera-based interception.

Innovation Solution

A portable payment or point-of-sale terminal that includes a proximity sensor, a detection device for a headset plug, and a second detection device for finger position on the screen, combined with a mobile device application that provides an accessibility mode for secure PIN entry through audio signals and screen blurring, ensuring the PIN is not visible and reducing the risk of interception.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a protection against viewing key values is equipped on the display area, then security against observation is improved, but the terminal size increases

Engineering Contradiction:
Improvesecurity against observationVSAvoidterminal size
Core Design Contradiction:
ReliabilityVSArea of stationary object

Solution Approach 1:

The patent transitions from a 2D display-based authentication to a 3D spatial authentication by detecting the 3D position and movement trajectory of the user's finger in space above the touchscreen. This eliminates the need for additional display protection mechanisms while maintaining security, as the authentication relies on spatial finger movement patterns rather than displayed key positions.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent replaces the mechanical/display-based key entry system with a sensor-based detection system. Instead of relying on visual display and physical key pressing, the system uses sensors to detect finger position, movement trajectory, and pressure, substituting the display protection mechanism with a sensor-based authentication approach that does not increase terminal size.

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

2Reliability

If a virtual personal identification keypad is displayed at various locations on a touchscreen, then security against fraud is improved, but the system becomes susceptible to camera-based interception

Engineering Contradiction:
Improvesecurity against fraudVSAvoidcamera-based interception
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the visual display-based virtual keypad with a sensor-based detection system that tracks finger movement in 3D space. Since no visual representation of keys or input is displayed, camera-based interception becomes ineffective. The authentication relies on detecting the spatial trajectory, position, and temporal patterns of finger movements rather than visual key positions.

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

Solution Approach 2:

The patent extracts the authentication information from the visual display domain and transfers it to the sensor detection domain. By removing the visual representation of keys and input from the display, the system eliminates the vulnerability to camera interception while maintaining fraud security through sensor-based finger movement analysis.

Inventive Principle:
Principle #2Taking out (Extraction)

3Reliability

If the screen is kept black during accessibility mode sequence, then security against visibility is improved, but accessibility for visually impaired users must rely on other mechanisms

Engineering Contradiction:
Improvesecurity against visibilityVSAvoidaccessibility for visually impaired users
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The patent introduces audio feedback as an intermediary between the user and the authentication system. While the screen remains black to prevent visual interception, the system provides audio cues that guide visually impaired users through the authentication process, indicating key positions and confirming input without compromising security.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent segments the authentication feedback into multiple channels: visual (black screen for security) and auditory (audio feedback for accessibility). This segmentation allows the system to maintain security through visual obscuration while providing accessibility through alternative auditory feedback mechanisms.

Inventive Principle:
Principle #1Segmentation

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 secure authentication for both sighted and visually impaired users by preventing keypad visibility and interception, maintaining terminal size, and ensuring secure transaction validation without displaying keys on the screen.

Implementation Method 1

a proximity sensor to detect the presence of a cardholder

Methodology Applied
Scientific EffectProximity sensing:

Implementation Method 2

a second detection device to detect the position of the finger on the screen each time a finger of the headset owner touches the screen

Methodology Applied
Scientific EffectCapacitive sensing:

Data Source

PatentEP3579130B1Device and method for secure identification of a user
Publication Date: 2026.03.04 INGENICO BELGIUM
  • EP3579130B1 patent drawingFigure 1A
  • EP3579130B1 patent drawingFigure 1B
  • EP3579130B1 patent drawingFigure 2a~2b

AI summary

The invention relates to a portable payment or point-of-sale terminal with a jack connector and a method for the secure identification of a cardholder, the terminal comprising a set of devices and an arrangement for implementing said method, which includes at least: detecting whether said cardholder has a mobile device, configuring the terminal to launch an accessibility mode on the cardholder's mobile device; transmitting a request to the mobile device for sending a PIN code to the terminal; and, upon receiving a communication from the mobile device containing information, decrypting said information to obtain the PIN code and validate the transaction.