Fingerprint Force Estimation Through Ridge-Valley Touch Sensing
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Solution Overview
Problem
Touch-sensitive electronic devices, such as tablets and smartphones, are limited in the information they can receive due to their two-dimensional nature, as they primarily detect position and movement but not the force of touch, which restricts additional input possibilities.
Innovation Solution
A system that incorporates sensors to estimate the force of touch by analyzing the ratio of ridges to valleys in a user's fingerprint, using capacitive, frustrated total internal reflection, or ultrasonic sensing technologies, and calibrates this data to determine the force applied, allowing for more nuanced input beyond basic touch and multi-touch inputs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If traditional touch sensors are used to detect position and movement, then basic touch input functionality is achieved, but the amount of information provided to the device is limited due to the two-dimensional nature of the touched surface
Solution Approach 1:
The patent transitions from two-dimensional touch detection (position only) to three-dimensional force detection by analyzing fingerprint ridge-to-valley contact ratios. This adds a vertical dimension of force measurement to the traditional planar touch interface, enabling detection of pressure magnitude, contact area, and finger wetness levels that were previously unavailable.
Solution Approach 2:
The system changes the detection parameter from simple contact presence to quantitative force measurement by analyzing the ratio of ridges to valleys in fingerprint contact. This parameter transformation converts qualitative touch information into quantitative force data, enabling differentiated input recognition based on pressure magnitude and contact characteristics.
2Measurement precision
If fingerprint analysis is used to determine force applied, then force detection capability is achieved, but device complexity increases due to additional sensors and processing requirements
Solution Approach 1:
The patent makes the fingerprint sensor multi-functional by using it for both traditional fingerprint identification and force detection. The same sensor array that captures ridge patterns also measures contact area and pressure distribution, eliminating the need for separate force sensing hardware and reducing overall device complexity despite enhanced measurement precision.
Solution Approach 2:
The fingerprint ridges and valleys act as an intermediary medium that translates applied force into detectable signal variations. By analyzing how ridges contact the sensor surface versus valleys, the system indirectly measures force magnitude without requiring direct force sensing elements, simplifying the measurement mechanism while maintaining precision.
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 the detection of force applied to the touch surface, enhancing the input capabilities of touch-sensitive devices by interpreting variations in touch force, which can be used for additional commands or actions, improving user interaction with electronic devices.
Implementation Method 1
using capacitive, frustrated total internal reflection, or ultrasonic sensing technologies
Implementation Method 2
using capacitive, frustrated total internal reflection, or ultrasonic sensing technologies
Implementation Method 3
using capacitive, frustrated total internal reflection, or ultrasonic sensing technologies
Data Source
AI summary
Embodiments may take the form of a system having a user input device and a first sensor coupled to the user input device. The first sensor is configured to sense touch on a surface of the user input device. The system may also include a second sensor in communication with the surface of the user device configured to sense wetting of a user's fingerprint on the surface. The system has a processor coupled to the first and second sensors and configured to estimate an amount of force applied by the user's fingerprint based at least in part upon the sensed wetting of the user's fingerprint.