Wrist Strap Biometric Sensor Using Distance Imaging
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Solution Overview
Problem
Conventional biometric sensors for wrist blood vessel detection face challenges such as thickness, cost, and limited imaging area, making them difficult to integrate into wristwatches and resulting in unreliable authentication due to insufficient vessel patterns.
Innovation Solution
A biometric sensor apparatus mounted on a wrist strap with a camera positioned on the inner side, capturing images from a distance to capture a larger area of the wrist, using a deployant clasp with blades and a camera mounted on one blade, and employing computer vision software to stitch images for reliable authentication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional biometric sensors are used for wrist blood vessel detection, then authentication function is provided, but the device thickness increases and integration into wristwatch becomes difficult
Solution Approach 1:
The patent extracts the blood vessel imaging function from conventional contact-based sensors and implements it using a camera positioned at a distance from the wrist. This separates the imaging function from the physical contact requirement, thereby reducing sensor thickness while maintaining authentication capability through optical capture of blood vessel patterns
Solution Approach 2:
The patent transitions from a contact-based 2D sensor surface to a 3D spatial arrangement where the camera is positioned at a distance from the wrist. This dimensional change allows capturing blood vessel patterns without requiring thick contact sensors, enabling thin-wristwatch integration while preserving authentication reliability
2Area of stationary object
If conventional sensors rest directly on the skin, then imaging is possible, but the imaging area is limited by the contact surface
Solution Approach 1:
The patent moves from a 2D contact surface constraint to a 3D spatial configuration where the camera is positioned at a distance from the wrist. This allows the imaging area to extend beyond the limited contact surface of a wristwatch, capturing a larger network of blood vessels without increasing device complexity
Solution Approach 2:
The patent introduces optical elements (lens, illuminator) as intermediaries between the camera and the wrist. These intermediaries enable the camera to capture blood vessel patterns from a distance, expanding the effective imaging area beyond the physical contact surface while maintaining system simplicity
3Ease of operation
If wristwatches are worn loosely to allow rotation and sliding, then comfort is improved, but pattern matching reliability decreases due to area mismatch
Solution Approach 1:
The patent transitions from contact-based 2D pattern capture to distance-based 3D spatial imaging. This allows the imaging area to exceed the wristwatch contact surface, ensuring that sufficient blood vessel patterns are captured even when the watch is worn loosely or rotated, thereby maintaining pattern matching reliability while improving wearing comfort
Solution Approach 2:
The patent creates a system that functions effectively across multiple wearing positions and orientations. By capturing images from a distance with a larger area, the system becomes universal to various wrist positions, maintaining authentication reliability regardless of whether the watch is worn tightly or loosely, statically or dynamically
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 enables more reliable user authentication by capturing a larger network of blood vessels, improving illumination, and reducing the thickness and cost constraints of conventional sensors, while ensuring consistent pattern matching.
Implementation Method 1
The subcutaneous blood vessels on a human wrist can be imaged using infrared illumination and in particular, near infrared (NIR) illumination
Data Source
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AI summary
A biometric sensor apparatus for capturing patterns of blood vessels on the inner side of a wrist, comprising: a portion of wrist strap; a near infrared camera mounted on said portion and arranged for capturing said patterns when said portion is held at a distance of said wrist during closure or opening of the wrist strap. The apparatus may further comprise an illuminating unit for illuminating a portion of said inner side. The camera may be mounted in a deployant clasp.