Hybrid Optical Capacitive Fingerprint Sensor Power Management
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Solution Overview
Problem
Current fingerprint sensor technologies face challenges in balancing power consumption and performance, particularly in providing high-resolution imaging and low-power modes for wake-on-finger and navigation functions, while ensuring strong security and anti-spoofing capabilities.
Innovation Solution
A hybrid capacitive and optical fingerprint sensor system that combines capacitive sensor electrodes with an optical image sensor, utilizing light conditioning elements and a processing system to operate in low-power modes and acquire high-resolution images, with capacitive sensors providing low-power functions like wake-on-finger and navigation, and optical sensors offering strong security and anti-spoofing features.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical image sensor is used for high-resolution fingerprint imaging, then measurement precision is improved, but use of energy increases
Solution Approach 1:
The sensor system is divided into two independent sensor types (optical and capacitive) that can operate independently or together. The optical sensor handles high-resolution imaging when needed, while the capacitive sensor handles low-power operations, allowing the system to segment energy consumption based on functional requirements.
Solution Approach 2:
The system dynamically switches between optical and capacitive sensing modes based on operational requirements. The controller selectively activates the optical image sensor for high-resolution fingerprint capture and uses capacitive sensing for wake-on-finger and navigation functions, optimizing power consumption in real-time.
2Use of energy by moving object
If capacitive sensor operates in low-power mode for wake-on-finger function, then use of energy is reduced, but measurement precision decreases
Solution Approach 1:
The capacitive sensor performs preliminary detection of finger presence in low-power mode before the optical sensor is activated. This preliminary action (wake-on-finger detection) allows the system to remain in a low-power state until fingerprint imaging is actually required, at which point the optical sensor is activated for high-precision capture.
3Reliability
If hybrid optical and capacitive sensor system is implemented, then reliability is improved, but device complexity increases
Solution Approach 1:
The sensor system integrates multiple sensing modalities (optical and capacitive) into a single unified structure that serves multiple functions: fingerprint imaging, wake-on-finger detection, navigation, and anti-spoofing verification. This multi-functionality approach increases reliability by providing redundant verification methods while managing complexity through shared hardware resources.
Solution Approach 2:
The controller acts as an intermediary that coordinates between the optical and capacitive sensors, processing data from both sources to make authentication decisions. This intermediary component manages the complexity of the hybrid system by providing a centralized control point that integrates inputs from multiple sensor types and coordinates their operation.
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
The hybrid system achieves efficient power management, high-resolution imaging, and enhanced security by leveraging capacitive and optical sensing capabilities, suitable for various usage scenarios and providing strong anti-spoofing functionality.
Implementation Method 1
an optical image sensor having a plurality of image sensor pixels... configured to condition light from a sensing region... for detection by the optical image sensor
Implementation Method 2
capacitive sensor electrodes... configured to operate the capacitive sensor electrodes in a low-power mode of operation
Data Source
AI summary
A hybrid capacitive and optical fingerprint sensor system includes: capacitive sensor electrodes; an optical image sensor having a plurality of image sensor pixels; light conditioning elements, configured to condition light from a sensing region of the hybrid capacitive and optical fingerprint sensor for detection by the optical image sensor; and a processing system having one or more controllers, configured to operate the capacitive sensor electrodes in a low-power mode of operation for the hybrid capacitive and optical fingerprint sensor, and to operate the optical image sensor to acquire an image from the sensing region of the hybrid capacitive and optical fingerprint sensor.