Switchable LED Illumination for Optical Inspection Contradictions

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Solution Overview

Problem

Current optical inspection systems for transparent or reflective materials, such as glass, require multiple camera and lighting configurations for bright field and dark field illumination to detect various defects, leading to increased complexity, cost, and space requirements, as well as inaccuracies in defect detection and classification.

Innovation Solution

A device and method that utilize a single camera bank with a processing unit to control multiple switchable lighting elements, allowing for flexible illumination patterns and multiple recordings in a single resolution range, enabling the combination of bright field, dark field, and other lighting configurations to detect and classify defects effectively.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If multiple camera and lighting configurations are used for bright field and dark field illumination, then defect detection accuracy is improved, but device complexity and cost increase

Engineering Contradiction:
Improvedefect detection accuracyVSAvoidinspection system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent applies dynamics by making the lighting configuration changeable over time. A single lighting device alternates between bright field and dark field illumination modes through controlled activation of different light sources, allowing one physical configuration to serve multiple inspection functions dynamically rather than requiring separate static configurations for each mode

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent implements universality by designing a single camera bank and lighting device that can perform multiple inspection functions. The same hardware infrastructure is used for both bright field and dark field illumination, enabling one system to detect different defect types that would otherwise require separate specialized equipment

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

2Measurement precision

If multiple camera and lighting configurations are used for bright field and dark field illumination, then defect detection accuracy is improved, but equipment cost increases

Engineering Contradiction:
Improvedefect detection accuracyVSAvoidequipment cost
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent implements universality by designing a single camera bank and lighting device that can perform multiple inspection functions. The same hardware infrastructure is used for both bright field and dark field illumination, enabling one system to detect different defect types that would otherwise require separate specialized equipment

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

Solution Approach 2:

The patent merges separate bright field and dark field illumination systems into a single integrated lighting device with multiple controllable light sources. By combining these functions into one physical unit with selective activation, the system reduces the total number of components needed while maintaining the capability to perform both types of illumination

Inventive Principle:
Principle #5Merging (Combining)

3Measurement precision

If multiple camera and lighting configurations are used for bright field and dark field illumination, then defect detection accuracy is improved, but space requirements increase

Engineering Contradiction:
Improvedefect detection accuracyVSAvoidinspection system space
Core Design Contradiction:
Measurement precisionVSArea of stationary object

Solution Approach 1:

The patent merges separate bright field and dark field illumination systems into a single integrated lighting device with multiple controllable light sources. By combining these functions into one physical unit with selective activation, the system reduces the total number of components needed while maintaining the capability to perform both types of illumination

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent applies dynamics by making the lighting configuration changeable over time. A single lighting device alternates between bright field and dark field illumination modes through controlled activation of different light sources, allowing one physical configuration to serve multiple inspection functions dynamically rather than requiring separate static configurations for each mode

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

This approach simplifies the inspection process, reduces equipment costs, and improves defect detection accuracy by allowing multiple lighting configurations to be achieved with a single camera bank, enhancing the ability to distinguish between different types of defects and increasing inspection speed.

Implementation Method 1

an illumination device for illuminating the moving object, in particular for generating a bright field or a dark field

Methodology Applied
Scientific EffectLight emission: Light

Implementation Method 2

an optical recording device for recording images of the areas of the object that are illuminated in particular as bright field or dark field

Methodology Applied
Scientific EffectLight detection: Photoelectric Effect

Data Source

PatentEP2390656B1Device and method for optical inspection
Publication Date: 2015.09.23 ISRA VISION GMBH
  • EP2390656B1 patent drawingFigure 1~2
  • EP2390656B1 patent drawingFigure 3~4
  • EP2390656B1 patent drawingFigure 5~7

AI summary

The device has an illumination device (2) illuminating a moving article (3) and comprising LEDs, and an optical recording device (1) e.g. charge coupled device matrix camera, recording images of an illumination area (5) of the article. A computing unit evaluates the recorded images on existence of faults. The computing unit is aligned to select a recording frequency for the recording device such that the recording device implements multiple recording processes in resolution area i.e. strip, corresponding to desired resolution in a transport direction (4). An independent claim is also included for a method for optical verification of faults in an article that is moved in a transport direction.