Fingerprint Detecting Apparatus With Variable Feedback Capacitance Amplifier
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Solution Overview
Problem
Existing feedback capacitive sensing type fingerprint detecting apparatuses face challenges in achieving optimal sensitivity due to thickness variations of the molding structure, which limit the operating range of the reference voltage and degrade the quality of the fingerprint image. Additionally, these devices are susceptible to external noise and electrostatic discharge.
Innovation Solution
The proposed solution involves a fingerprint detecting apparatus with a variable feedback capacitance amplifier, where the sensitivity is optimized by adjusting the feedback capacitance based on environmental factors and device configurations. This includes the use of a shield layer to minimize parasitic capacitance effects and an electrostatic discharge protection circuit to prevent interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If feedback capacitive sensing method is used, then circuit simplicity and reduced sensor electrode size are achieved, but sensitivity is degraded due to molding structure thickness variations
Solution Approach 1:
The patent implements dynamic adjustment of the reference voltage based on detected thickness variations of the molding structure. The system continuously monitors the capacitance signal and adjusts the reference voltage in real-time to compensate for thickness changes, thereby maintaining optimal sensitivity while preserving the circuit simplicity of the feedback capacitive sensing method.
Solution Approach 2:
The patent changes the reference voltage parameter dynamically to compensate for molding structure thickness variations. By adjusting the reference voltage according to the detected capacitance changes, the system maintains accurate fingerprint detection sensitivity without increasing circuit complexity.
2Device complexity
If fixed reference voltage is used, then device simplicity is maintained, but detection accuracy deteriorates due to environmental noise and electrostatic discharge
Solution Approach 1:
The patent implements a feedback mechanism where the detected capacitance signal is used to adjust the reference voltage. This closed-loop feedback system continuously adapts the reference voltage to compensate for environmental noise and electrostatic discharge, maintaining detection accuracy without requiring complex external control mechanisms.
Solution Approach 2:
The system performs self-adjustment by using its own detected signal to modify the reference voltage. The feedback capacitive sensing circuit automatically compensates for environmental interference without requiring external intervention or complex control systems, thereby maintaining reliability while keeping the device simple.
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 effectively optimizes fingerprint detection sensitivity, reduces the impact of external noise and electrostatic discharge, and improves the accuracy of fingerprint detection by dynamically adjusting the feedback capacitance and incorporating noise suppression mechanisms.
Implementation Method 1
a change in capacitive coupling between them
Implementation Method 2
use of a shield layer to minimize parasitic capacitance effects
Implementation Method 3
an electrostatic discharge protection circuit to prevent interference
Data Source
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AI summary
The disclosure relates to fingerprint detecting apparatus and driving method thereof.