Under-display Terahertz Biometric Imaging for Spoofing Prevention

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Solution Overview

Problem

Optical fingerprint sensors under display panels are vulnerable to spoofing with 2-dimensional fake fingerprints, lacking sufficient security against unauthorized access.

Innovation Solution

A terahertz biometric imaging arrangement is integrated under a partially transparent display panel, utilizing terahertz radiation to capture images of fingerprints without direct contact, with a transmitter element emitting terahertz radiation and an image sensor using an antenna pixel array to detect and convert terahertz signals into usable images for biometric verification.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If optical fingerprint sensors are used under display panels, then the device can perform biometric authentication, but the security against spoofing with 2-dimensional fake fingerprints is insufficient

Engineering Contradiction:

Improvesecurity against spoofingVSAvoiddepth detection capability

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent changes the operating wavelength parameter from visible light (optical sensors) to terahertz radiation. This parameter change enables penetration into sub-dermal layers of the fingerprint, allowing detection of depth information and three-dimensional structural characteristics that prevent spoofing with 2-dimensional fake fingerprints.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces optical sensing mechanisms with terahertz radiation-based imaging. The terahertz transmitter and receiver system substitutes the optical fingerprint sensor, enabling non-contact imaging and detection of sub-dermal fingerprint structures through the display panel and skin surface.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If terahertz radiation is used to penetrate into sub-dermal layers, then the ability to detect spoofing is improved, but the device complexity increases

Engineering Contradiction:

Improvespoof detection abilityVSAvoidsystem structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The display panel serves multiple functions: it acts as both the display interface for the user and as a transmission medium for terahertz radiation. This multi-functionality reduces device complexity by eliminating the need for separate transparent windows or openings in the display structure.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent uses the display panel itself as an intermediary medium that allows terahertz radiation to pass through. This intermediary approach enables the imaging system to operate under the display without requiring direct contact between the sensor and the fingerprint, simplifying the overall system architecture.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Measurement precision

If direct contact between skin and image sensor is required, then optical sensors can capture fingerprint images, but the performance under display arrangement is limited

Engineering Contradiction:

Improvefingerprint image capture qualityVSAvoidcontactless imaging capability

Core Design Contradiction:

Measurement precisionVSEase of operation

Solution Approach 1:

The patent replaces contact-based optical sensing with non-contact terahertz imaging. The terahertz radiation can penetrate through the display panel and illuminate the fingerprint without requiring direct contact between the sensor and skin, enabling contactless biometric authentication while maintaining image quality.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 terahertz biometric imaging arrangement enhances security by detecting sub-dermal layers of fingerprints, reducing the likelihood of spoofing and improving performance compared to optical sensors, allowing for secure biometric authentication without obstructing the display's visibility.

Implementation Method 1

a transmitter element arranged to emit terahertz radiation for illuminating the object

Methodology Applied

Scientific EffectTerahertz radiation emission: Electromagnetic Induction

Implementation Method 2

an image sensor comprising an antenna pixel array arranged to detect terahertz radiation transmitted from the illuminated object

Methodology Applied

Scientific EffectTerahertz radiation detection: Electromagnetic Induction

Implementation Method 3

the photon energy is low enough so that the photons are not absorbed in most materials, i.e. the penetration of the radiation may be e.g. up to 0.2 mm, into the skin

Methodology Applied

Scientific EffectElectromagnetic radiation penetration: Absorption (EM radiation)

Data Source

PatentUS11749015B2Under display terahertz biometric imaging arrangement

Publication Date: 2023.09.05 FINGERPRINT CARDS ANACATUM IP AB

AI summary

The present invention relates to a terahertz biometric imaging arrangement configured to be arranged under an at least partially transparent display panel and configured to capture an image of an object located on an opposite side of the transparent display panel, the biometric imaging arrangement comprising: a transmitter element arranged to emit terahertz radiation for illuminating the object; and an image sensor comprising an antenna pixel array arranged to detect terahertz radiation transmitted from the illuminated object, for producing an image.