Fingerprint Enrollment via Touch Sensor Coordinate Mapping
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Solution Overview
Problem
Existing fingerprint enrollment methods using small sensors are not intuitive and require combining partial images, which can be difficult, especially in mobile devices where enrollment and authentication should be performed using the same device.
Innovation Solution
A method that utilizes a touch sensor and fingerprint sensor arranged closely together to improve the formation of a combined fingerprint template by relating partial fingerprint images to a finger coordinate system, accounting for different orientations and ensuring sufficient coverage, thereby reducing the number of images needed and simplifying the enrollment process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If a small fingerprint sensor is used for stationary finger placement, then the form factor is reduced and surface space is saved, but the enrolled template must correspond to a considerably larger portion of the fingerprint than the partial image captured during authentication
Solution Approach 1:
The fingerprint sensor surface is divided into multiple sub-areas, each with its own touch sensor. During enrollment, the system captures multiple partial fingerprint images from different sub-areas and combines them to form a complete template, thereby achieving both small sensor size and complete fingerprint coverage.
Solution Approach 2:
The system adds a temporal dimension to the enrollment process by capturing multiple partial images at different time points and combining them. This allows the sensor to accumulate complete fingerprint information over time rather than requiring complete coverage in a single static image.
2Loss of information
If several partial images are combined to form a combined template, then sufficient fingerprint information is obtained, but it becomes difficult to combine the partial images due to alignment and registration challenges
Solution Approach 1:
A coordinate transformation system acts as an intermediary between different partial fingerprint images. The system uses known positional relationships between sensor sub-areas and touch sensor data to automatically transform and align partial images into a common coordinate system, eliminating manual alignment complexity.
Solution Approach 2:
The system uses touch sensor signals as feedback to determine finger position and orientation during enrollment. This feedback information is used to guide the alignment and combination of partial fingerprint images, ensuring accurate registration without complex manual procedures.
3Stability of the object's composition
If navigation information is used to adjust partial fingerprint images for motion compensation, then finger motion between images is accounted for, but the enrollment process becomes more complex and less intuitive for users
Solution Approach 1:
The system performs automatic motion compensation using touch sensor data without requiring user intervention. The touch sensor automatically detects finger position and motion, and the system self-corrects for these movements during image combination, making the process both accurate and simple for users.
4Adaptability or versatility
If the same electronic device is used for both enrollment and authentication, then device integration is improved, but the sensor must be small enough for mobile devices while still capturing sufficient fingerprint information
Solution Approach 1:
During the enrollment phase, the system proactively captures multiple partial fingerprint images from different sub-areas and combines them into a complete template stored in the device. This preliminary action ensures that sufficient fingerprint information is stored for future authentication operations on the same mobile device.
Solution Approach 2:
The system merges multiple partial fingerprint images captured from different sub-areas of the small sensor into a single combined template. This combining process enables the small sensor to achieve the same enrollment quality as a much larger sensor would provide in a single image.
Data Source
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AI summary
The present invention relates to a method of enrolling a fingerprint of a user's finger,by means of an electronic device comprising a touch sensor having an active area corresponding to a first surface portion of the electronic device; and a fingerprint sensor having an active area corresponding to a second surface portion of the electronic device. The comprises the steps of acquiring a touch sensor signal indicative of a sub-area of the touch sensor being touched by the finger;acquiring a partial fingerprint image of a portion of the fingerprint;a positional relationship between the portion of the fingerprint and the finger based on the sub-area and a positional relationship between the first and second surface portions of the electronic device;and forming a fingerprint template based on acquired partial fingerprint images and the determined positional relationships.