Light Field Camera Substrate Defect Detection

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Solution Overview

Problem

High-speed print production systems face challenges in accurately detecting and correcting small variations in substrate web alignment, movement, and surface contour due to mechanical anomalies like web tension, paper deformities, and flutter, which current static or limit-sensing mechanisms are insufficient to address.

Innovation Solution

The implementation of one or more light field cameras to record image data of the substrate during printing, coupled with a control unit that processes this data to identify defect areas, enabling dynamic feedback for correcting paper stability issues.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If static or limit-sensing mechanisms (e.g., tension gauge, light beam make/break) are used to detect substrate defects, then the device complexity is reduced, but the measurement precision and reliability of defect detection deteriorate

Engineering Contradiction:
Improvedetection mechanism complexityVSAvoiddefect detection precision
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent replaces static mechanical sensing mechanisms (tension gauges, light beam make/break sensors) with a dynamic image processing system using cameras and computational analysis. This substitution enables continuous, high-precision measurement of substrate properties (tension, alignment, surface contour) without the limitations of threshold-based mechanical sensors, thereby improving measurement precision while maintaining reasonable system complexity through software-based processing.

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

Solution Approach 2:

The patent introduces an intermediary image processing system that captures optical images of the substrate and uses computational algorithms to extract defect information. This intermediary layer between the substrate and the detection system allows for non-contact, high-resolution measurement of substrate characteristics, overcoming the precision limitations of direct mechanical sensing while adding a manageable layer of system complexity.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Device complexity

If simple edge or threshold sensing is used to detect substrate defects, then the device complexity is reduced, but the reliability of defect detection deteriorates due to insufficient detection of subtle variations

Engineering Contradiction:
Improvesensing mechanism complexityVSAvoiddefect detection reliability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent replaces simple threshold-based sensing with a sophisticated image processing system that analyzes continuous variations in substrate properties. By using cameras to capture detailed images and applying computational algorithms to detect subtle changes in tension, alignment, and surface contour, the system achieves high reliability in defect detection while avoiding the binary limitations of threshold sensing.

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

Solution Approach 2:

The patent transitions from static threshold sensing to dynamic, continuous monitoring through image capture and processing. The system continuously captures images of the substrate during printing and dynamically analyzes variations in substrate properties over time, enabling reliable detection of subtle defects that would be missed by static threshold-based methods.

Inventive Principle:
Principle #15Dynamics

3Manufacturing precision

If dynamic feedback for real-time correction is implemented, then the manufacturing precision of substrate handling is improved, but the device complexity increases

Engineering Contradiction:
Improvesubstrate handling precisionVSAvoidcontrol system complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent implements a feedback control system where the image processing system continuously monitors substrate properties (alignment, tension, surface contour) and provides real-time feedback to the printing system. This feedback loop enables dynamic adjustment of substrate handling and printing parameters to maintain manufacturing precision, with the complexity managed through integrated control algorithms that process image data and generate correction signals.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent replaces complex mechanical feedback mechanisms with an optical and computational feedback system. Instead of using additional mechanical sensors and actuators, the system uses cameras to capture substrate images and computational algorithms to generate feedback signals for correction, reducing mechanical complexity while achieving high manufacturing precision through software-based control.

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

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 solution provides a more accurate and dynamic detection mechanism for mechanical and print quality defects, improving the predictability and final quality of printed products by capturing 3D surface information and providing real-time correction for issues like cockle, flutter, and wrinkling.

Implementation Method 1

one or more light field cameras to record image data of the substrate during printing

Methodology Applied
Scientific EffectLight field imaging: Plenoptic Camera

Data Source

PatentUS9132665B2Substrate defect detection mechanism
Publication Date: 2015.09.15 RICOH CO LTD
  • US9132665B2 patent drawing
  • US9132665B2 patent drawing
  • US9132665B2 patent drawing

AI summary

A method is disclosed. The method includes one or more light field cameras recording image data of a substrate during printing to the substrate and a control unit processing the image data received from the one or more light field cameras to identify defect areas in the substrate.