Substrate Surface Quality Detection in Packaging Conversion

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Solution Overview

Problem

Current methods for determining the surface quality of substrates during conversion processes in packaging production lines are inadequate, as they fail to identify all defects, particularly those masked by successive printing colors, and do not ensure final product quality, leading to potential defects in packaging products.

Innovation Solution

A method involving two defect detection steps: one before and one after the conversion process, using high-resolution cameras to acquire and process information on surface defects on both initial and converted substrates, allowing for classification and optimization of the substrate quality, and a converting machine equipped with devices for detecting defects upstream and downstream of the conversion elements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Extent of automation

If a single defect detection step is performed after the conversion process, then the checking operation can be carried out automatically on the production line, but defects masked by successive printing colors cannot be identified

Engineering Contradiction:
Improveautomatic defect detectionVSAvoiddefect identification accuracy
Core Design Contradiction:
Extent of automationVSMeasurement precision

Solution Approach 1:

The defect detection process is segmented into two distinct steps: a first detection step before the conversion process (printing) and a second detection step after the conversion process. This segmentation allows the system to capture defects at different stages - the first detection captures defects visible on the unprinted substrate, while the second detection captures defects that may have been created or revealed during printing. By combining information from both detection steps, the system overcomes the limitation of single-step detection where printed defects are masked by successive printing colors.

Inventive Principle:
Principle #1Segmentation

2Measurement precision

If multiple defect detection steps are implemented (before and after conversion), then all types of defects can be identified, but the device complexity increases

Engineering Contradiction:
Improvedefect identification accuracyVSAvoiddetection system structure
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The detection devices used in both the first and second detection steps are designed with multi-functionality. Each device is capable of detecting various types of defects (printing defects, substrate defects, creasing defects, embossing defects) and can adapt to different detection requirements. This universality reduces the need for completely separate specialized detection systems for each defect type or stage, thereby managing complexity while maintaining comprehensive detection capability.

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

Solution Approach 2:

The system implements feedback mechanisms where the results from the first detection step inform the second detection step, and vice versa. The processing unit compares information from both detection steps to identify defects that were present before conversion and defects that were created during conversion. This feedback loop allows the system to intelligently process and correlate data from multiple detection steps without requiring proportionally increased complexity in the processing architecture.

Inventive Principle:
Principle #23Feedback

3Device complexity

If defects are detected only after conversion, then the classification is simpler, but the quality control cannot prevent defective products from reaching the manufacturer

Engineering Contradiction:
Improveclassification systemVSAvoidproduction quality guarantee
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The first defect detection step is performed as a preliminary action before the substrate undergoes the conversion process (printing). This preliminary detection identifies defects that exist on the substrate before printing, allowing for early classification and potential intervention. By detecting defects in advance, the system can prevent obviously defective substrates from entering the conversion process, thereby improving production quality reliability without requiring overly complex classification systems.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system performs defect detection at both preliminary (before conversion) and final (after conversion) stages, which can be viewed as partial actions at different points in the process. The first detection provides partial quality assurance by catching pre-existing defects, while the second detection provides additional partial assurance by catching conversion-related defects. Together, these partial actions deliver comprehensive quality control without requiring a single excessively complex classification system.

Inventive Principle:
Principle #16Partial or excessive action

Data Source

PatentUS8045147B2Method for determining the surface quality of a substrate and associated machine for converting the substrate
Publication Date: 2011.10.25 BOBST SA SERVICE DES BREVETS
  • US8045147B2 patent drawing
  • US8045147B2 patent drawing
  • US8045147B2 patent drawing

AI summary

A method for determining the surface quality of a substrate passing from an initial state into a converted state during a conversion process including the steps of acquiring first information relating to surface defects detected on the initial substrate, acquiring second information relating to surface defects detected on the converted substrate, of processing the first information and the second information, and of classifying the converted substrate as a function of the first acquired information relating to the surface defects detected on the initial substrate and as a function of the second acquired information relating to the surface defects detected on the converted substrate.