Non-contact Line Scan Camera Measurement for Rotating Printing Plates

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Solution Overview

Problem

Current measuring systems for rotating bodies in the graphic industry, such as flexographic printing plates and sleeves, face challenges in achieving high precision and speed while avoiding contact damage, especially when measuring fine printing points.

Innovation Solution

A non-contact measurement device using a line camera aligned parallel to the rotation axis, combined with a radiation source and a reference object, allows for precise and rapid elevation measurement of rotating bodies by generating a common image from individual line images, enabling automatic presetting of optimal working pressure and printing conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If contactless measurement is used, then damage to soft printing points is avoided, but measurement precision may be reduced

Engineering Contradiction:
Improvedamage to soft printing pointsVSAvoidmeasurement precision
Core Design Contradiction:
Object-affected harmful factorsVSMeasurement precision

Solution Approach 1:

The patent replaces mechanical contact measurement with optical measurement using a line camera and radiation source. The radiation source emits light that reflects off the printing plate surface, and the line camera captures the reflected light patterns to determine elevations without physical contact, thus avoiding damage while maintaining precision through optical detection methods.

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

Solution Approach 2:

The patent introduces light as an intermediary medium between the measurement system and the printing plate. The radiation source and line camera use light reflection patterns as an intermediary to indirectly measure surface elevations, eliminating the need for direct mechanical contact while preserving measurement accuracy through optical signal analysis.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If high precision measurement of fine printing points is achieved, then measurement time increases, but productivity decreases

Engineering Contradiction:
Improvemeasurement precisionVSAvoidproductivity
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The patent segments the measurement process by using a line camera that captures elevation data along linear scan lines rather than attempting to capture the entire surface simultaneously. The measurement system scans the printing plate surface in multiple passes, dividing the complex measurement task into manageable linear segments, which allows for high precision while maintaining reasonable measurement speed.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent performs preliminary scanning to identify the general area and characteristics of the printing plate before conducting detailed precision measurements. The system first captures an overview and then focuses measurement resources on specific regions requiring high precision, optimizing the balance between measurement speed and accuracy.

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

This solution enables quick and precise measurement of rotating bodies, reducing downtime and waste, and ensuring high-quality printed products with minimal personnel and costs, while avoiding damage to soft printing points.

Implementation Method 1

a measuring device for contactless measurement comprises at least one radiation source, at least one line scan camera

Methodology Applied
Scientific EffectReflection: Reflection

Data Source

PatentEP3988313B1Device for measuring elevations of the surface of a rotating body and system
Publication Date: 2024.07.03 HEIDELBERGER DRUCKMASCHINEN AG
  • EP3988313B1 patent drawingFigure 1
  • EP3988313B1 patent drawingFigure 2a~2c
  • EP3988313B1 patent drawingFigure 2b

AI summary

An inventive device for measuring elevations (13) of the surface (14) of a rotating body (6) designed as a cylinder (15), roller (15), sleeve (3), or plate (5) of a machine of the graphic arts industry (8), e.g., a flexographic printing plate, comprising a first motor (7) for rotating the rotating body (6) about an axis of rotation (22) and a measuring device (18), is characterized in that the measuring device (18) for non-contact measurement comprises at least one radiation source (19), at least one line scan camera (21), and a computer (39), and that the computer combines individual images from the line scan camera into a common image. Preferably, the measuring device (18) for non-contact measurement further comprises a reference object (30), e.g., a wire stretched parallel to the axis, and a second motor (29), and optionally,A second motor (29b) is provided for adjusting the measuring device (18) and/or the reference object perpendicular to the axis of rotation (22). The device enables the rapid and highly accurate measurement of protrusions, e.g., flexographic pressure points.