Compact Palmprint Scanner with Folding Mirrors and Localized Illumination
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Solution Overview
Problem
Conventional fingerprint and palmprint imaging systems are bulky, require significant operator skill, consume substantial power, and are not ergonomically designed to capture rolled fingerprints effectively, often necessitating multiple devices and large housings to manage moisture and illumination issues.
Innovation Solution
A compact device with a single scanning system that employs a large optical platen, high-resolution imaging, and a thin, uniform illumination scheme to capture 500 ppi and 1000 ppi images of palms and fingerprints, including rolled fingerprints, using a combination of folding mirrors, multiple lens elements, and a monochromatic CMOS imager, which provides high modulation transfer function and moisture discrimination optics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single scanning device is used to capture both palm and rolled fingerprint images, then device complexity is reduced, but manufacturing precision requirements increase to maintain high MTF across the entire field of view
Solution Approach 1:
The patent applies local quality by implementing different optical performance requirements for different regions of the field of view. The center region (for palm images) requires high MTF across the entire area, while the lower region (for rolled fingerprints) has relaxed MTF requirements. This allows the single device to meet FBI standards for both capture types without requiring uniform high precision across the entire optical path.
Solution Approach 2:
The field of view is segmented into distinct regions: a central region for palm image capture with high MTF requirements, and a lower region for rolled fingerprint capture with reduced MTF requirements. This segmentation allows the optical system to be optimized for each region's specific needs, enabling a single device to handle multiple capture modes effectively.
2Area of stationary object
If a large optical platen is used to capture palm images, then area of object receiving surface increases, but device volume increases requiring large housing
Solution Approach 1:
The patent employs folding mirrors to redirect the optical path, effectively using the vertical dimension to fold the light path and reduce the horizontal footprint of the device. This allows a large object receiving surface area to be maintained while compacting the overall device volume by utilizing three-dimensional space more efficiently.
3Measurement precision
If high-resolution imaging is used to capture 1000 ppi images, then measurement precision increases, but use of energy increases due to powerful illumination and processing requirements
Solution Approach 1:
The illumination system provides different illumination intensities for different regions: the palm capture region receives standard illumination, while the rolled fingerprint region in the lower field of view receives enhanced illumination. This localized approach ensures sufficient image quality for high-resolution capture without uniformly increasing power consumption across the entire 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
Enables efficient capture of high-resolution palm and fingerprint images in a compact, ergonomic device that meets FBI standards, reducing power consumption and operator skill requirements while maintaining high image quality across the required field of view.
Implementation Method 1
A lens mechanism is provided to focus light from the object receiving surface onto the image plane
Implementation Method 2
The system may include one or more folding mirrors to direct light from the object receiving surface to the lens mechanism
Implementation Method 3
A light source is positioned to illuminate the object receiving surface
Data Source
AI summary
Systems, devices and methods for providing rolled fingerprint capture and palm capture capability in a device having reduced size are provided. In certain embodiments, the systems and methods provide capture of rolled fingerprints, slap fingerprints and palm prints in one continuous workflow in a compact device. In certain embodiments, moisture discriminating optics and/or enhanced definition image formation previously achieved only in devices designed for capturing only fingerprints are provided. In certain embodiments, the systems employ a single scanning device to capture 500 ppi and/or 1000 ppi palm and fingerprint images.