Capacitive Fingerprint Touch Detection for Low-Power Recognition
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Solution Overview
Problem
Capacitive sensing fingerprint recognition systems require high power consumption due to the need for continuous scanning and processing of large finger areas, leading to inefficient energy use.
Innovation Solution
A fingerprint recognition system that uses a detection electrode and contact detection apparatus to determine when a finger is present, activating only when a touch is detected, thereby keeping most function modules in a dormant state until recognition is needed, reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If continuous fingerprint scanning is performed to ensure reliable recognition, then recognition reliability is improved, but power consumption increases
Solution Approach 1:
The system performs fingerprint scanning periodically based on touch detection events rather than continuously. The control unit activates the fingerprint sensor only when a touch event is detected, and deactivates it during idle periods, transforming continuous operation into periodic operation that maintains recognition reliability while reducing power consumption significantly
2Measurement precision
If high pixel density scanning is used to obtain accurate fingerprint information, then measurement precision is improved, but device complexity and power consumption increase
Solution Approach 1:
The system extracts only the essential fingerprint features needed for recognition rather than processing complete high-resolution images continuously. By using touch-triggered scanning, the system captures fingerprint data only when needed, extracting necessary information without requiring complex continuous processing of full-resolution data, thus reducing device complexity while maintaining precision
3Speed
If the fingerprint recognition apparatus remains active to respond quickly to user input, then response speed is improved, but power consumption increases
Solution Approach 1:
The system performs preliminary touch detection using the detection electrode to anticipate when fingerprint scanning will be needed. By detecting touch events in advance and triggering scanning only when necessary, the system maintains quick response to actual user input while avoiding unnecessary continuous operation, thus balancing response speed with power consumption
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 system effectively recognizes user fingerprints while significantly reducing power consumption by activating only when a finger is detected, ensuring reliable recognition with minimal standby power usage.
Implementation Method 1
an analog to digital converter, charges and discharges the detection electrode, and detecting capacitance value of the detection electrode
Data Source
AI summary
A fingerprint recognition system and method are disclosed. The fingerprint recognition system includes: a fingerprint recognition apparatus, a detection electrode, and a contact detection apparatus. The contact detection apparatus includes: an analog to digital converter configured to charge and discharge the detection electrode and to detect a capacitance value of the detection electrode; a determining module configured to determine whether the detection electrode is touched by a finger according to the capacitance value, and to generate finger touch information when determining that the finger touches the detection electrode to start the fingerprint recognition apparatus to perform fingerprint recognition.