Fingerprint Sensor Pixel Driving for Noise-Reduced Pattern Sensing
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Solution Overview
Problem
Existing fingerprint sensors face challenges in effectively removing noise from fingerprint patterns, which can lead to inaccurate biometric verification, and they often have limited area coverage, making them less efficient for secure personal information verification.
Innovation Solution
A fingerprint sensor design incorporating a matrix arrangement of scan lines, driving signal lines, sensing lines, and sensor pixels with transistors and capacitors that utilize initialization and common voltages to differentiate between touch and noise signals, allowing for noise reduction and enhanced area coverage through a specific driving method that involves distinct signal periods for noise and sensing data acquisition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional fingerprint sensing methods are used, then the sensing process is simple, but noise cannot be effectively removed from fingerprint patterns
Solution Approach 1:
The sensing process is divided into distinct time periods: a first period for acquiring noise data without touch, and a second period for acquiring fingerprint data with touch. This temporal segmentation allows noise and signal to be separated and processed independently, improving measurement precision without adding structural complexity.
Solution Approach 2:
Noise data is acquired in advance during a first period before the actual fingerprint sensing occurs. This preliminary action allows the system to characterize and remove noise from the subsequent fingerprint measurement, thereby improving accuracy without requiring additional hardware components.
2Area of stationary object
If larger area coverage is implemented, then more fingerprint data can be captured, but the sensor pixel density and resolution may decrease
Solution Approach 1:
The sensor operates in periodic cycles, alternating between a first period for noise acquisition and a second period for fingerprint data acquisition. This periodic operation allows the same sensor pixels to serve dual purposes over time, enabling large area coverage while maintaining resolution through temporal multiplexing rather than spatial expansion.
3Reliability
If multiple transistors and capacitors are added to each sensor pixel for noise reduction, then noise removal capability improves, but manufacturing complexity increases
Solution Approach 1:
Each sensor pixel is designed with multiple functional components (first transistor, second transistor, third transistor, reference capacitor, touch capacitor) that serve multiple purposes: the transistors control signal flow for both noise and fingerprint acquisition, while the capacitors store and compare charge states. This multi-functionality improves reliability without proportionally increasing manufacturing complexity, as the same structures perform multiple operations within the periodic sensing cycle.
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 solution enables the acquisition of noise-reduced fingerprint patterns with improved accuracy and larger area coverage, enhancing the reliability of biometric verification processes.
Implementation Method 1
a touch capacitor including one electrode connected to the first node, wherein capacitance of the touch capacitor changes by touching of an external object
Data Source
AI summary
A sensor pixel includes: a reference capacitor including a first end connected to a driving signal line and a second end connected to a first node; a touch capacitor including one electrode connected to the first node, wherein capacitance of the touch capacitor changes by touching of an external object; a first transistor including a first end connected to an initialization voltage line, a second end connected to the first node, and a control end connected to an initialization line; a second transistor including a first end for receiving a common voltage, a second end for outputting a current generated based on the common voltage, and a control end connected to the first node; and a third transistor including a first end connected to the second end of the second transistor, a second end connected to a sensing line, and a control end connected to a scan line.