Ultrasonic Fingerprint Circuit Layout for Low-Interference Sensing
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Solution Overview
Problem
Existing ultrasonic fingerprint identification circuits suffer from poor precision due to signal interference caused by coupling capacitance between numerous wirings, which affects the accuracy of fingerprint identification.
Innovation Solution
The ultrasonic fingerprint identification circuit employs a driving method with a reduced number of control signal lines by reusing one control signal line for multiple fingerprint identification units, incorporating a control module and reading module connected to a composite signal line, and utilizing transistors with low leakage current to minimize interference and enhance signal accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a large number of wirings are arranged in the ultrasonic fingerprint identification circuit, then each fingerprint identification unit can be independently controlled, but coupling capacitance interference increases and identification precision deteriorates
Solution Approach 1:
The patent merges control functions by having multiple fingerprint identification units share common control signal lines (first control signal line and second control signal line). Instead of providing separate control lines to each unit, the same control lines are reused across multiple units, reducing the total number of wirings and thereby minimizing coupling capacitance interference while maintaining independent controllability through timing-based multiplexing.
2Measurement precision
If the number of control signal lines is reduced by reusing signal lines, then coupling capacitance interference decreases, but the complexity of signal line management increases
Solution Approach 1:
The patent employs periodic action through time-division multiplexing, where control signal lines are activated in alternating periods to serve different fingerprint identification units. The first control signal line and second control signal line are used alternately for different units at different time intervals, allowing simple wiring reuse while maintaining clear signal management through periodic activation patterns.
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 configuration reduces the number of control signal lines, minimizes coupling capacitance interference, and improves the accuracy of fingerprint identification by enhancing the signal-to-noise ratio and stabilizing the potential at the identification node.
Implementation Method 1
an ultrasonic fingerprint identification sensor electrically connected to a first node, wherein the ultrasonic fingerprint identification sensor is configured to: convert a first electrical signal to an ultrasonic signal and radiate the ultrasonic signal towards a finger
Implementation Method 2
a control module electrically connected to a composite signal line, the first node, and one first control signal line of a plurality of first control signal lines, wherein the control module is configured to: provide a reset potential to the first node in response to a first level provided by the one of the plurality of first control signal lines
Data Source
AI summary
Provided are an ultrasonic fingerprint identification circuit, a driving method thereof, and a display device. The ultrasonic fingerprint identification circuit comprises fingerprint identification units each including an ultrasonic fingerprint identification sensor connected to a first node; a control module connected to a composite signal line, a first control signal line and the first node and configured to provide a reset potential to the first node and to provide a pull-up potential to the first node in response to a first level provided by the composite signal line; a reading module connected to a second control signal line, the first node and a reading signal line, and configured to read a detection signal of the first node. The first control signal line connected to one fingerprint identification unit is reused as the second control signal line connected to another fingerprint identification unit.