Contactless Biometric Sensor With Spatially Variable Light Mask
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Solution Overview
Problem
Existing biometric readers, such as the MorphoWave™, are complex and costly due to their use of multiple lighting systems and test patterns, which complicates their design and increases production costs without necessarily enhancing performance.
Innovation Solution
A contactless biometric sensor with a spatially variable light transmissivity mask on its upper face, combined with a single-color lighting source and an imager, reduces complexity and cost while maintaining performance by using a mask to introduce a test pattern projection into both lighting and imaging paths, and a processing unit to compensate for these projections in the acquired image.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple lighting systems and test patterns are used, then biometric acquisition performance is improved, but device complexity and cost increase
Solution Approach 1:
The patent combines the lighting source and mask into a single integrated unit where the mask is positioned directly in front of the lighting source. This merging eliminates the need for separate lighting systems and test pattern projectors, reducing device complexity while maintaining the ability to project structured light patterns for accurate biometric acquisition
Solution Approach 2:
The mask serves multiple functions: it modulates the lighting to create test patterns, defines the illumination geometry, and structures the projected light without requiring additional dedicated components. This multi-functionality reduces the overall number of components needed in the system
2Measurement precision
If multiple lighting systems and test patterns are used, then biometric acquisition performance is improved, but manufacturing cost increases
Solution Approach 1:
By integrating the mask directly onto the lighting source housing or mounting it in a fixed position relative to the LED, the patent eliminates the need for separate test pattern projectors and multiple lighting assemblies, thereby reducing component count and manufacturing cost
Solution Approach 2:
The mask can be implemented as a simple opaque structure with specific geometric patterns that is inexpensive to manufacture, potentially as a molded plastic component or printed pattern, replacing expensive complex optical systems
3Device complexity
If a mask with spatially variable light transmissivity is used, then test pattern projection is achieved, but image quality is degraded by imaging projection
Solution Approach 1:
The system uses feedback through image processing algorithms that analyze the captured image to distinguish between the test pattern projection and the actual biometric features. The processing unit compensates for the mask's imaging projection by recognizing the known test pattern structure and subtracting or correcting its influence on the final image
Solution Approach 2:
The image processing extracts and removes the test pattern projection component from the captured image, separating it from the actual biometric information. This allows the system to recover clean biometric data despite the mask's presence in the imaging path
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 achieves reduced complexity and cost without degrading performance by effectively compensating for the mask's light modulation in the image, enabling accurate dermatoglyph acquisition and recognition, and supporting fraud detection.
Implementation Method 1
The upper face is provided with a mask having spatially variable light transmissivity. In use, the mask introduces onto said human body part a projection, referred to as lighting projection, of a test pattern having a spatial modulation of light intensity.
Implementation Method 2
a lighting source configured to light said human body part through the upper face
Implementation Method 3
an imager configured to acquire an image of said human body part through the upper face
Data Source
AI summary
A contactless biometric sensor, including an upper face above which, in use, a human body part which has dermatoglyphs is positioned, a lighting source configured to light the human body part through the upper face and an imager configured to acquire an image of the human body part through the upper face. The upper face of the sensor is provided with a mask having spatially variable light transmissivity.