Piezo Fingerprint Sensor Pressure Feedback and Moisture Vibration

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Solution Overview

Problem

Current fingerprint sensors face challenges with variable pressure application and moisture, leading to reduced authentication accuracy and increased false rejections.

Innovation Solution

A piezo-based fingerprint sensor structure that incorporates a piezo structure to sense pressure and provide feedback, while also using vibration to facilitate fingerprint data collection and expel moisture.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If users apply variable pressure to the fingerprint sensor, then the sensor can capture fingerprint data, but the authentication accuracy is reduced and false rejections increase

Engineering Contradiction:
Improvefingerprint authentication accuracyVSAvoidpressure application consistency
Core Design Contradiction:
Measurement precisionVSEase of operation

Solution Approach 1:

The piezo structure provides real-time feedback to the controller about the pressure applied by the user. The controller uses this feedback to determine when sufficient pressure has been applied and to provide guidance to the user for achieving the correct pressure level, ensuring consistent pressure application and improving authentication accuracy

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The piezo structure generates vibrations that facilitate fingerprint data collection by enhancing the interaction between the fingerprint sensor and the user's finger. The vibrations help to expel moisture and improve contact, leading to more accurate fingerprint capture regardless of pressure variations

Inventive Principle:
Principle #18Mechanical vibration

2Reliability

If moisture is present on the fingerprint sensor or user's finger, then the sensor can still attempt to capture data, but the detection ability is reduced and false rejections increase

Engineering Contradiction:
Improvefingerprint detection abilityVSAvoidmoisture interference
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The piezo structure generates vibrations that actively expel moisture from the contact interface between the fingerprint sensor and the user's finger. The vibrations disrupt moisture accumulation and improve contact quality, maintaining reliable fingerprint detection even in humid conditions or when the user's finger is slightly damp

Inventive Principle:
Principle #18Mechanical vibration

Solution Approach 2:

The system converts the presence of moisture, which is normally harmful to fingerprint detection, into a detectable condition. The piezo structure's vibration response and pressure feedback allow the controller to identify moisture presence and adjust the sensing process accordingly, turning a potential failure mode into a manageable parameter

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

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

Improves fingerprint authentication accuracy by providing precise pressure feedback and enhancing data collection through vibration, reducing false rejections and user frustration.

Implementation Method 1

A piezo based fingerprint sensor structure is discussed herein. A device includes both a fingerprint sensor and a piezo structure.

Methodology Applied
Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

using vibration to facilitate fingerprint data collection and expel moisture

Methodology Applied
Scientific EffectVibration: Vibration

Data Source

PatentEP2936384B1Piezo based fingerprint sensor structure
Publication Date: 2025.03.05 GOOGLE TECHNOLOGY HOLDINGS LLC
  • EP2936384B1 patent drawingFigure 1
  • EP2936384B1 patent drawingFigure 2
  • EP2936384B1 patent drawingFigure 3

AI summary

A device includes both a fingerprint sensor (112) and a piezo structure (114). The fingerprint sensor senses fingerprint data identifying a pattern of a fingerprint of a user. The fingerprint data for the user can be collected and analyzed in various manners in order to authenticate the sensed fingerprint. The piezo structure can be used in various manners, such as to collect data used to facilitate authenticating the sensed fingerprint data, to provide feedback to the user regarding when the fingerprint authentication process is complete, and/or to cause different types of vibration in order to facilitate sensing fingerprint data. Various additional feedback can also be provided to the user, using the piezo structure or other feedback mechanisms, such as feedback to notify the user to increase or decrease an amount of pressure he or she is applying to the fingerprint sensor.