Fingerprint Sensor Touch Press Detection Without Mechanical Buttons
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Solution Overview
Problem
Existing biometric systems face challenges in distinguishing between finger touch and press events without mechanical buttons, particularly in mobile devices that have eliminated home buttons, as current solutions rely on mechanical motion which increases cost and reduces durability.
Innovation Solution
A fingerprint sensor system and method that detects finger presence and computes metrics from successive frames to differentiate between touch and press events using capacitive, optical, acoustic, or thermal sensing technologies without mechanical movement, setting thresholds for touch and press detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical buttons are used for home button functionality, then button press detection is reliable, but device cost and thickness increase
Solution Approach 1:
The patent replaces mechanical button structures with a capacitive fingerprint sensor that detects touch and press events through electrical field changes. The sensor measures capacitance variations caused by finger contact to distinguish between touch (light contact) and press (firm contact) events, eliminating the need for mechanical components while maintaining detection reliability.
Solution Approach 2:
The fingerprint sensor serves multiple functions: it performs biometric authentication and simultaneously detects both touch and press events. This multi-functionality eliminates the need for separate mechanical buttons, reducing device complexity and thickness while maintaining the ability to detect different user input forces.
2Device complexity
If mechanical buttons are eliminated to reduce cost and thickness, then device cost and thickness decrease, but touch and press detection capability is lost
Solution Approach 1:
The patent substitutes mechanical button structures with an electronic capacitive sensing system. The fingerprint sensor detects finger presence and measures capacitance changes to differentiate between touch and press events, providing the necessary detection capability without mechanical components, thereby reducing device thickness and cost.
Solution Approach 2:
The system detects different input forces by measuring changes in capacitance parameters. Light finger contact produces smaller capacitance changes (touch), while firm pressure produces larger changes (press). By monitoring these parameter variations, the system maintains touch and press detection capability without mechanical buttons.
3Duration of action of stationary object
If capacitive sensing is used to detect touch and press, then device durability increases, but distinction between touch and press events becomes difficult
Solution Approach 1:
The system continuously monitors capacitance values over time and uses threshold-based feedback to distinguish between touch and press events. When capacitance exceeds a first threshold, a touch event is registered; when it exceeds a higher second threshold, a press event is registered. This feedback mechanism enables precise event differentiation while maintaining sensor durability.
Solution Approach 2:
The patent distinguishes between touch and press events by detecting different magnitudes of capacitance parameter changes. Touch events produce smaller capacitance variations, while press events produce larger variations. By setting appropriate thresholds on these parameter changes, the system achieves accurate event distinction with durable capacitive sensors.
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 reliable and durable touch and press detection in mobile devices without mechanical components, reducing costs and increasing sensor durability by using fingerprint sensors to differentiate between touch and press events based on computed metrics.
Implementation Method 1
the sensor does not detect the presence of an object... computing a metric from the measurement... determining that a finger touch has occurred... determining that a finger press has occurred
Data Source
AI summary
Disclosed are systems and methods for detecting a finger touch and/or finger press. A method includes: detecting presence of a finger on a fingerprint sensor; causing the fingerprint sensor to take measurements using multiple successive frames of the fingerprint sensor; for each measurement, computing a metric associated with the measurement at a given frame corresponding to the measurement; at a first particular frame, determining that the finger has settled on the fingerprint sensor, wherein determining that the finger has settled comprises determining that the metric at the first particular frame exceeds a settled value threshold; and, based on determining that the finger has settled, determining that a finger touch has occurred. A finger press can be further determined by monitoring whether the metric passes a press threshold.