Fingerprint Identification Circuit with Switching Power Management
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Solution Overview
Problem
Existing fingerprint identification systems in electronic devices consume high power due to always-active processors and sensors, leading to unintentional wake-ups from power-saving modes by non-finger objects.
Innovation Solution
A system comprising a fingerprint sensor, a force sensor, and a switching circuit that alternates between low-power detection modes to detect force and finger touches, only activating the processor when a matching fingerprint is confirmed, thereby reducing power consumption and preventing false wake-ups.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the processor and sensors are always active to ensure immediate response, then the response speed is improved, but the power consumption increases
Solution Approach 1:
The patent implements periodic action by alternating between power-saving mode and detection mode through a switching circuit. The fingerprint sensor and force sensor are activated periodically in alternating modes (low power force detection mode and low power fingerprint detection mode) rather than continuously, enabling the system to maintain responsiveness while significantly reducing power consumption during idle periods.
Solution Approach 2:
The system applies dynamics by making the operational state of the processor and sensors adjustable rather than fixed. The switching circuit dynamically transitions the system between sleep mode and active detection mode based on detected touches, allowing the processor to be awake only when needed while maintaining the ability to respond quickly when activated.
2Measurement precision
If the processor remains awake to process sensor data, then the identification accuracy is improved, but the power consumption increases
Solution Approach 1:
The patent extracts the fingerprint detection and initial processing functions from the main processor and implements them in a dedicated fingerprint identification circuit. This allows the fingerprint sensor to operate independently in low-power modes without requiring the processor to be continuously awake, while still maintaining identification accuracy through the extracted circuit's processing capabilities.
Solution Approach 2:
The fingerprint identification circuit acts as an intermediary between the fingerprint sensor and the processor. It performs preliminary fingerprint detection and matching in low-power mode, and only wakes the processor when a match is found, thus maintaining identification accuracy while reducing the processor's power consumption during normal operation.
3Measurement precision
If the sensor is always active to detect any touch, then the detection sensitivity is improved, but the power consumption increases
Solution Approach 1:
The switching circuit implements periodic activation of the fingerprint sensor and force sensor in alternating low-power modes. The sensor remains inactive during power-saving periods but is periodically activated to detect touches, maintaining detection sensitivity while consuming significantly less power compared to continuous operation.
Solution Approach 2:
The system dynamically adjusts the sensor's operational state through the switching circuit, transitioning between active and inactive states based on detection needs. This allows the sensor to maintain high sensitivity when activated while enabling power-saving mode during idle periods, optimizing the balance between detection sensitivity and power consumption.
Data Source
AI summary
A fingerprint identification apparatus includes a force sensor, a fingerprint sensor, and a switching circuit coupled between the force sensor and the fingerprint sensor. The switching circuit is configured to alternately activate a low power force detection mode to detect the force touch using the force sensor and a low power fingerprint detection mode to detect the finger touch using the fingerprint sensor after a switching period. In response to determining that either the force touch or the finger touch is detected, the fingerprint identification apparatus detects the fingerprint using the fingerprint sensor in a normal fingerprint detection mode. Next, the fingerprint identification apparatus determines whether the detected fingerprint matches one of reference fingerprints, and outputs an interrupt signal indicating whether the detected fingerprint matches one of the reference fingerprints. A fingerprint identification method and a system for fingerprint identification are also introduced.