Capacitive Fingerprint Sensor Wake-Up Control for Lower Power Scanning
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Solution Overview
Problem
Conductive fingerprint sensors experience high power consumption due to continuous detection mode, wasting energy on detecting useless signals during the waiting period before actual fingerprint detection.
Innovation Solution
A fingerprint detection sensor with a conductive layer and capacitance detecting module that forms a sensing capacitance between the finger and detecting units, allowing the sensor to determine the distance based on capacitance changes and control units to scan only when the finger is close, reducing unnecessary scanning and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the detecting panel continuously scans for fingerprint in waiting state, then the detection speed is improved, but the power consumption increases significantly
Solution Approach 1:
The patent applies preliminary action by performing capacitance detection before full fingerprint scanning. The detecting panel first detects changes in sensing capacitance to determine if a finger is present and ready for scanning. This preliminary detection prepares the system in advance, allowing the high-power scanning mode to be activated only when necessary, thus reducing overall power consumption while maintaining fast detection response.
Solution Approach 2:
The patent implements dynamics by switching between different operating modes based on detection needs. The system dynamically transitions from a low-power capacitance detection mode (when no finger is present) to a high-power fingerprint scanning mode (when a finger is detected). This dynamic adjustment of operational states allows the system to optimize the balance between detection speed and power consumption in real-time.
2Measurement precision
If the detecting panel remains in on state continuously, then the detection accuracy is maintained, but the power consumption increases
Solution Approach 1:
The patent applies periodic action by implementing intermittent scanning instead of continuous operation. The system performs capacitance detection periodically to monitor for finger presence, and only activates the full fingerprint scanning function when a finger is detected. This periodic operation pattern maintains detection accuracy by regularly checking for fingers while significantly reducing power consumption compared to continuous scanning.
3Loss of time
If the sensor scans fingerprint continuously, then the detection response time is reduced, but unnecessary scanning of empty region wastes energy
Solution Approach 1:
The patent applies preliminary action by using capacitance detection to identify the presence and position of a finger before initiating full fingerprint scanning. This preliminary step ensures that scanning resources are focused only on regions where fingers are actually present, eliminating wasted energy on empty regions while maintaining fast detection response time by being ready to scan immediately upon finger detection.
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
This approach reduces power consumption and enhances detection accuracy by minimizing unnecessary scanning and isolating the detection region from external interference.
Implementation Method 1
a conductive layer, configured to form a sensing capacitance between the conductive layer and a finger when the finger is close to the detecting region; a capacitance detecting module, configured to detect the sensing capacitance
Data Source
AI summary
A sensor for detecting a fingerprint, a fingerprint identification apparatus and a controlling method of a sensor for detecting a fingerprint are provided. The sensor for detecting the fingerprint includes a detecting panel including: a detecting region with a plurality of detecting units, in which the plurality of detecting units are distributed in a plurality rows and columns on the detecting region; and a conductive layer, configured to form a sensing capacitance between the conductive layer and a finger when the finger is close to the detecting region; a capacitance detecting module, configured to detect the sensing capacitance; and a control module.