Capacitive Finger Biometric Sensor With Integrated Pressure Sensing
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Solution Overview
Problem
Fingerprint sensors in electronic devices often require separate authentication steps, which can be inconvenient and limit their functionality beyond authentication.
Innovation Solution
A finger biometric sensor design featuring a lower and upper conductive layer with a spacer defining an air gap, a finger biometric sensing IC that deflects the upper layer to change capacitance based on pressure, and a pressure sensing circuit to execute device functions, allowing for integrated authentication and additional functions like navigation and health monitoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fingerprint sensor is integrated into an electronic device to enable authentication, then authentication capability is improved, but the device requires separate authentication steps which reduces ease of operation
Solution Approach 1:
The patent combines fingerprint authentication and pressure sensing functions into a single integrated sensor module. The capacitive sensor array detects both fingerprint patterns and pressure magnitude, allowing authentication to be merged with other device functions such as navigation or health monitoring, eliminating the need for separate authentication steps
Solution Approach 2:
The sensor module is designed to perform multiple functions beyond authentication, including pressure-sensitive navigation, health monitoring, and other device controls. This multi-functionality allows the same hardware to serve various purposes, improving ease of operation by integrating authentication seamlessly into everyday device usage
2Adaptability or versatility
If the sensor structure is made more complex to enable multiple functions, then functionality is improved, but device complexity increases
Solution Approach 1:
Multiple sensing functions (fingerprint detection, pressure sensing, capacitance measurement) are merged into a single capacitive sensor array and integrated circuit module. This consolidation achieves multi-functionality without proportionally increasing structural complexity, as one hardware component performs multiple roles
Solution Approach 2:
The integrated circuit is designed with universal capabilities to process multiple types of input signals (fingerprint patterns, pressure magnitude, capacitance changes) and execute various device functions. This software/firmware-level multi-functionality allows a single hardware structure to adapt to different applications without requiring separate dedicated components for each function
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 quick and integrated authentication, enhanced mechanical robustness, and reduced sensor size while maintaining performance, allowing for various device functions based on pressure sensing.
Implementation Method 1
capable of deflecting the upper conductive layer toward the lower conductive layer to change a capacitance thereof based upon pressure applied to the finger biometric sensing IC
Implementation Method 2
sense the change in capacitance caused by deflection of the upper conductive layer toward the lower conductive layer. The deflection may be based upon pressure applied to the finger biometric sensing IC
Data Source
AI summary
A finger biometric sensor may include a lower conductive layer, an upper conductive layer, and a spacer between the lower and upper conductive layers to define an air gap therebetween. The finger biometric sensor may also include a finger biometric sensing integrated circuit (IC) above the upper conductive layer and capable of deflecting the upper conductive layer toward the lower conductive layer to change a capacitance thereof based upon pressure applied to the finger biometric sensing IC. A pressure sensing circuit may be coupled to the lower and upper conductive layers to sense the change in capacitance.