Fingerprint Sensor Test Module With Flexible Alignment

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Solution Overview

Problem

Existing methods for testing fingerprint sensing devices lack efficiency and accuracy, particularly in replicating the conditions of a human finger for quality image capture, making it difficult to automate the testing process in large-scale manufacturing.

Innovation Solution

A test module comprising an electrically conductive bottom element with a flexible intermediate element and a top element, configured to adapt to the sensing device's surface, mimicking a human finger's contact and providing a controlled electrical connection to simulate the finger's electrical properties, with a patterned surface for functionality verification.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a rigid test probe is used to contact the fingerprint sensor, then the alignment and contact position can be precisely controlled, but the probe cannot adapt to misalignment or tilting of the sensor surface

Engineering Contradiction:
Improvecontact alignment precisionVSAvoidadaptability to sensor misalignment
Core Design Contradiction:
Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The test probe incorporates a flexible intermediate element (rubber or elastomeric material) between the rigid contact element and the sensor surface. This flexible layer allows the probe to adapt to misalignment and tilting of the sensor while maintaining stable electrical contact, resolving the contradiction between precise alignment control and adaptability to surface variations.

Inventive Principle:
Principle #30Flexible shells and thin films

2Ease of manufacture

If a simple rubber stamp is used for testing, then the test structure is simple and easy to manufacture, but it cannot provide controlled electrical connection to simulate finger properties

Engineering Contradiction:
Improvetest structure simplicityVSAvoidelectrical connection reliability
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The test probe uses a composite structure combining rigid materials (for structural stability), flexible materials like rubber or elastomers (for adaptation and noise reduction), and electrically conductive materials (for reliable electrical connection). This composite approach maintains manufacturing simplicity while achieving reliable electrical connection and accurate simulation of finger properties.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The flexible intermediate element acts as a mediator between the rigid probe structure and the sensor surface, providing both mechanical adaptation and electrical connection. This intermediary layer simulates the electrical properties of a human finger while maintaining the structural integrity needed for automated testing.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Productivity

If automated testing is implemented, then testing efficiency and productivity increase, but the test setup becomes more complex requiring precise positioning mechanisms

Engineering Contradiction:
Improvetesting efficiencyVSAvoidpositioning mechanism complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The test probe incorporates dynamic elements such as spring-loaded mechanisms or flexible mounting that allow automatic adaptation to sensor position variations. This dynamic design enables automated testing without requiring extremely precise positioning mechanisms, as the probe can compensate for minor positioning errors through its inherent flexibility and adaptation capability.

Inventive Principle:
Principle #15Dynamics

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

Enables efficient and accurate testing of fingerprint sensing devices by ensuring uniform contact and minimizing electrical noise, allowing for reliable verification of sensor functionality and image quality across various manufacturing stages.

Implementation Method 1

The intermediate element comprises a flexible material enabling the bottom element to change alignment in response to an applied force

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

an electrically conductive bottom element (102) comprising an exterior surface portion (104) configured to contact a sensing surface of a fingerprint sensing device (110)

Methodology Applied
Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentEP3526618B1Test module for a fingerprint sensing device
Publication Date: 2023.06.21 FINGERPRINT CARDS ANACATUM IP AB
  • EP3526618B1 patent drawingFigure 1~2
  • EP3526618B1 patent drawingFigure 3~4
  • EP3526618B1 patent drawingFigure 5~6B

AI summary

There is provided a test module (100) for testing a fingerprint sensing device (110) comprising: an electrically conductive bottom element (102) comprising an exterior surface portion configured to contact a sensing surface of the fingerprint sensing device; an electrically conductive intermediate element(106), connected to the bottom element on a side opposing the exterior surface, the intermediate element comprising a flexible material enabling the bottom element to change alignment in response to an applied force occurring when the exterior surface is pressed against a surface being tilted with respect to the exterior surface of the bottom element; and a top element (108) configured connect the test module to a test fixture. There is alsoprovided a method for testing a fingerprint sensing device using the described test module.