Fingerprint Sensor Electrode Arrangement for Liveness Detection
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Solution Overview
Problem
Existing fingerprint identification systems face challenges in ensuring security against forgery and errors due to complex structures and inaccurate positioning, particularly in liveness detection and multi-finger authentication.
Innovation Solution
An arrangement with a first electrode for the thumb and at least one second electrode for other fingers, both coupled with a fingerprint sensor and a measuring unit, allowing for intuitive user handling and reduced measurement errors by guiding correct finger placement, and optionally using force detection units for enhanced security.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If closely spaced two-point electrodes are used for impedance measurement, then liveness detection capability is improved, but measurement accuracy deteriorates due to positioning errors and finger movement
Solution Approach 1:
The patent divides the single impedance measurement into multiple separate measurements using multiple electrode pairs. Each electrode pair measures impedance across a different finger or finger region, and the results are combined to achieve both accurate liveness detection and robustness against positioning errors. This segmentation allows the system to maintain reliability while reducing sensitivity to individual measurement errors.
2Reliability
If complex electrode structures are used for accurate liveness detection, then detection capability is improved, but device complexity increases
Solution Approach 1:
The patent makes the electrode structure multi-functional by using the same electrodes for both fingerprint capture and impedance measurement. The electrodes serve dual purposes: capturing the fingerprint pattern and simultaneously measuring electrical impedance for liveness detection. This eliminates the need for separate specialized electrode structures, reducing overall device complexity while maintaining detection capability.
Solution Approach 2:
The patent merges the fingerprint sensor functionality with the impedance measurement functionality into a single integrated system. The electrode structure is designed to perform both functions concurrently, combining what could have been separate components into one unified structure, thereby reducing device complexity.
3Reliability
If multiple fingers are used for authentication, then security against forgery is improved, but ease of operation deteriorates due to incorrect positioning
Solution Approach 1:
The patent enables the system to automatically handle positioning variations by measuring impedance across multiple electrode pairs that correspond to different fingers. The system self-adjusts by collecting data from all available finger contacts and using the combined information for authentication, eliminating the need for precise manual positioning by the user.
Solution Approach 2:
The patent segments the authentication process into multiple independent finger measurements, each captured by separate electrode pairs. This allows the system to process each finger independently and combine the results, making the overall authentication more secure while accommodating natural variations in finger placement.
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
This solution simplifies fingerprint identification and liveness detection, reducing errors and enhancing security by allowing easy handling and using force detection for improved authentication, thus ensuring accurate and quick access authorization checks.
Implementation Method 1
an impedance measurement is carried out on a fingertip placed on the fingerprint sensor
Implementation Method 2
a fingerprint sensor optically or electrically - usually capacitively - reading or capturing biometric data
Data Source
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AI summary
The invention relates to an arrangement for identifying fingerprints, comprising at least one fingerprint sensor (21) and at least two electrodes (8, 23), wherein a fingerprint can be detected (31) by means of the fingerprint sensor (21). The invention further relates to a corresponding method for identifying fingerprints. A first electrode (23) is arranged in the vicinity of a hand support surface (7) at a distance from said hand support surface (7) such that when an index, and/or middle, and/or ring, and/or little finger of a hand is placed on said hand support surface (7), the thumb (12) of said hand (20) can be placed on the first electrode (23). At least one second electrode (8) is arranged on the hand support surface (7) such that at least one finger of the index, middle, ring, or little finger can be placed on the second electrode (8). The fingerprint sensor (21) and the first electrode (23) and/or the at least one second electrode (8) are each designed as one unit (6). Electric signals are transmitted (32) to the placed hand (20) via the electrodes (8, 23) by a measuring unit (25) for applying and analyzing the electric signals, and the changes of the electric signals are detected (33). An identification result is then ascertained (34) using the detected fingerprints and the detected signals from the measuring unit (25). Using the arrangement and the corresponding method, the reliability when checking entrance and/or access authorizations is increased and the possibility of fraud by means of non-authorized persons is reduced in a simple manner.