Preform Barrier Layer Inspection Using OCT and Multispectral Imaging

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Solution Overview

Problem

Existing methods for inspecting preforms and closures for defects, particularly in barrier layers, are inefficient and require special alignment, leading to high costs due to production halts and manual counting, and are not suitable for transparent or optically blocked layers.

Innovation Solution

A testing method using optical coherence tomography (OCT) and multispectral imaging to inspect preforms and closures without requiring special alignment, allowing for rapid, automated detection of defects in barrier layers and accurate counting, compatible with existing manufacturing setups.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional optical inspection methods are used to detect defects in preforms and closures, then the inspection process is simple and fast, but transparent barrier layers and optically blocked layers cannot be detected reliably

Engineering Contradiction:
Improvedefect detection reliabilityVSAvoidinspection system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent introduces an intermediary substance (refractive index matching liquid) between the inspection object and the optical sensor. This intermediary modifies the optical properties of the inspection interface, enabling light to penetrate transparent barrier layers and reflect off defects that would otherwise be invisible to conventional optical inspection methods.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the refractive index parameter of the inspection medium by applying a liquid with specific refractive index properties to the preform or closure surface. This parameter change enables the optical inspection system to detect defects in transparent and optically blocked barrier layers that cannot be detected with air or standard optical methods.

Inventive Principle:
Principle #35Parameter changes

2Productivity

If manual inspection and counting methods are used for preforms, then equipment complexity is low, but production time increases and costs rise due to production halts

Engineering Contradiction:
Improveinspection speedVSAvoidautomation system complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent replaces manual mechanical inspection and counting operations with an automated optical inspection system. The system uses optical sensors, image processing algorithms, and automated defect recognition to perform both quality inspection and counting functions simultaneously, eliminating the need for production halts and manual labor.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent creates a multi-functional inspection system that simultaneously performs defect detection, quality assessment, and counting operations. This universal system handles multiple inspection tasks in a single automated process, improving productivity while managing device complexity through integrated functionality.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Reliability

If preforms are inspected for defects before further processing, then product quality improves, but production time increases due to production halts

Engineering Contradiction:
Improveproduct qualityVSAvoidproduction downtime
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent implements preliminary automated optical inspection of preforms immediately after manufacturing but before they enter the molding process. By performing inspection early in the production flow with automated systems that require no production halt, the method maintains product quality while minimizing loss of time.

Inventive Principle:
Principle #10Preliminary action

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 reliable, fast, and simple automatic quality testing of preforms and closures, reducing production downtime and manual labor, with high accuracy in defect detection and counting, and minimal modifications to existing facilities.

Implementation Method 1

the image is an optical coherence tomogram or a multispectral image

Methodology Applied
Scientific EffectOptical coherence tomography: Tomography

Implementation Method 2

the image is an optical coherence tomogram or a multispectral image

Methodology Applied
Scientific EffectMultispectral imaging: Absorption Spectroscopy

Data Source

PatentEP3298391B1Testing method and testing system
Publication Date: 2026.03.04 FINATEC HLDG
  • EP3298391B1 patent drawingFigure 1
  • EP3298391B1 patent drawingFigure 2
  • EP3298391B1 patent drawingFigure 3

AI summary

The invention relates to a testing method and a corresponding testing system, for example for testing workpieces (2) which are provided for producing containers, in particular beverage bottles, and which can consist of a main part and a barrier layer that is at least partly supported on the main part. The workpieces (2) are transported into a receiving vessel (4) by means of a transport device (3), and an image of the workpieces (2) is generated by means of a capturing device (6) and transmitted to a processing device for testing. The workpieces (2) are introduced into the receiving vessel (4) upon leaving the transport device (3), and the image is generated between when the workpieces leave the transport device (3) and when the workpieces leave the receiving vessel (4). The image is processed by the processing device such that the quality of the main part and/or the quality of the barrier layer of the workpieces (2) is tested in order to detect faulty workpieces (2). The same testing system and the same testing method can also be used to count the workpieces (2).