Dermatoglyph Detector Calibration Tracks
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Solution Overview
Problem
Current dermatoglyph detectors face irregular results in fake finger detection due to manufacturing tolerances affecting electrical conduction properties, leading to variations in impedance measurements between different production batches.
Innovation Solution
Incorporating a calibration track with known electrical properties into the detection circuit, allowing for the determination of sheet resistance, which enables accurate impedance calculations and reduces sensitivity to hardware disparities, thereby improving measurement uniformity and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If manufacturing tolerances are reduced to improve detector uniformity, then measurement precision improves, but manufacturing complexity and cost increase
Solution Approach 1:
The patent introduces calibration tracks with known impedance values into the detection circuit. By measuring the actual impedance of these calibration tracks and using the measured values to compensate for manufacturing variations, the system achieves consistent measurements across different detectors without requiring tighter manufacturing tolerances. This transforms the problem from controlling physical dimensions to measuring and compensating electrical parameters.
Solution Approach 2:
The patent implements a feedback mechanism where the impedance measurements from calibration tracks are used to adjust and normalize the measurements from authentication tracks. The system measures the actual electrical characteristics of each detector, compares them against expected values, and uses this information to compensate for deviations, thereby achieving uniform performance across production batches.
2Measurement precision
If calibration tracks are added to the detection circuit, then measurement accuracy improves, but device complexity increases
Solution Approach 1:
The patent combines the calibration functionality with the existing detection circuit by integrating calibration tracks alongside authentication tracks on the same substrate. The calibration tracks share the same electrical conduction properties and manufacturing process as the authentication tracks, merging the calibration function into the existing structure rather than adding a separate calibration system.
Solution Approach 2:
The calibration tracks serve multiple purposes: they provide reference impedance values for compensation, enable detector-to-detector uniformity adjustment, and allow for in-situ characterization of the conductive film properties. This multi-functional approach maximizes the utility of the added calibration elements.
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 enhances the reliability of distinguishing between authentic and fake fingers by accounting for the electrical conduction properties of the detection circuit, resulting in more consistent and accurate biometric recognition performance across different detectors.
Implementation Method 1
an electrically conductive thin film in which there are formed both electrodes that are arranged to come into contact with the skin of a portion of a human body and also conductive tracks connecting the electrodes to the processor unit
Implementation Method 2
the calibration track, which forms part of the detection circuit, presents the same electrical conduction properties as the remainder of the detection circuit. Measuring the impedance of the calibration track makes it possible to determine its sheet resistance
Data Source
AI summary
A dermatoglyph detector includes a detection circuit and an electronic processor unit. The detection circuit includes an electrically conductive thin film in which there are formed both electrodes that are arranged to come into contact with the skin of a portion of a human body and also conductive tracks connecting the electrodes to the processor unit. The processor unit is arranged to determine electrical characteristics of the body portion extending between each pair of electrodes in contact with the skin, and to execute a computer program for acting on the basis of the determined electrical characteristics to distinguish between an authentic body portion and a fake body portion. The detection circuit includes at least two track segments of different shapes between two calibration terminals so as to present an impedance ratio that is not equal to unity.