Fingerprint Sensor Haptic Feedback for Complete Finger Capture

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Solution Overview

Problem

Existing computing devices often fail to acquire a complete and accurate fingerprint image due to users prematurely removing their finger from the fingerprint sensor during the sensing process, leading to inefficient and incomplete authentication.

Innovation Solution

The device initiates a fingerprint sensing operation and outputs a sequence of haptic signals with increasing intensity, followed by a discrete high-intensity signal to indicate successful completion, optionally accompanied by visual cues, ensuring the user maintains their finger until the process is finished.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the fingerprint sensing operation is performed without user feedback, then the device structure remains simple, but the user may prematurely remove their finger resulting in incomplete fingerprint capture

Engineering Contradiction:
Improvefingerprint image completenessVSAvoidfeedback mechanism complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent implements a feedback mechanism where the device provides real-time haptic feedback to the user during the fingerprint sensing operation. The haptic feedback changes based on the quality and completeness of the captured fingerprint image, guiding the user to maintain proper finger placement until a complete image is obtained. This resolves the contradiction by actively communicating sensing progress to prevent premature finger removal while maintaining relatively simple device architecture.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system enables the user to self-regulate their finger placement on the sensor by providing them with sensory feedback about the capture quality. Instead of requiring complex external monitoring or forcing the user to wait for a fixed time, the haptic feedback allows the user to independently determine when the fingerprint image is complete, improving measurement precision without adding significant device complexity.

Inventive Principle:
Principle #25Self-service

2Measurement precision

If multiple fingerprint sensing attempts are allowed, then the user can eventually provide a complete fingerprint image, but the authentication process becomes slower and less efficient

Engineering Contradiction:
Improvefingerprint image accuracyVSAvoidauthentication time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The device performs preliminary assessment of fingerprint image quality during the sensing operation and provides early feedback to the user about capture completeness. By detecting and communicating the status of the fingerprint image formation in real-time, the system prevents premature completion of unsuccessful attempts and guides users to achieve complete captures in a single attempt, reducing overall authentication time while maintaining high accuracy standards.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

Real-time haptic feedback during the sensing operation informs users about the quality of their fingerprint placement, enabling them to make immediate adjustments if needed. This prevents wasted time on incomplete captures by providing continuous guidance toward achieving a complete image, thereby reducing the need for multiple retry attempts and accelerating the authentication process.

Inventive Principle:
Principle #23Feedback

3Ease of operation

If the fingerprint sensing operation requires a fixed duration, then the device control is simplified, but the user may remove their finger too early resulting in incomplete capture

Engineering Contradiction:
Improvesensing operation controlVSAvoidfingerprint image completeness
Core Design Contradiction:
Ease of operationVSMeasurement precision

Solution Approach 1:

The patent transitions from a static, fixed-duration sensing model to a dynamic, adaptive sensing operation. The haptic feedback mechanism dynamically adjusts based on the actual fingerprint image quality and capture progress, allowing the sensing duration to vary according to real-time conditions. This maintains ease of operation by automatically managing the sensing process while ensuring complete capture through intelligent adaptation rather than rigid timing constraints.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

By implementing feedback that communicates capture progress to the user, the system enables flexible sensing duration that adapts to actual capture needs. The haptic feedback provides real-time information about image completeness, allowing the sensing operation to extend or conclude based on actual progress rather than arbitrary time limits, thereby maintaining both operational simplicity and capture completeness.

Inventive Principle:
Principle #23Feedback

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 enhances the accuracy and efficiency of fingerprint recognition by reducing the need for multiple attempts, thereby improving processing and power efficiency.

Implementation Method 1

a fingerprint sensor senses fingerprint data identifying a pattern of a fingerprint of a user

Methodology Applied
Scientific EffectCapacitive sensing: Capacitance

Implementation Method 2

The piezo structure can be used in various manners, such as to collect data used to facilitate authenticating the sensed fingerprint, 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

Methodology Applied
Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentEP4217828B1Guiding fingerprint sensing via user feedback
Publication Date: 2025.11.05 GOOGLE LLC
  • EP4217828B1 patent drawingFigure 1
  • EP4217828B1 patent drawingFigure 2
  • EP4217828B1 patent drawingFigure 3

AI summary

An example method includes initiating, by a computing device, a fingerprint sensing operation that is associated with a fingerprint sensor, outputting, by the computing device and over a defined period of time, a sequence of haptic signals with varying intensity, wherein each haptic signal in the sequence has an intensity that is different than a respective intensity of any haptic signal that was previously output in the sequence, obtaining, by the computing device and from the fingerprint sensor, fingerprint data associated with a fingerprint of the finger of the user, and responsive to determining that the finger of the user is still positioned at the fingerprint sensor upon completion of the fingerprint sensing operation, outputting, by the computing device, a discrete haptic signal indicating a successful completion of the fingerprint sensing operation.