Optical End Inspection for Axial Runout in Circular Glass Tubes

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Solution Overview

Problem

Existing methods for measuring the axial run out of circular elongated elements, such as glass tubes, are inadequate for quantifying this parameter on a μm scale, are contact-dependent, and fail to account for curvature or inclination, leading to inconsistent quality and increased fracture susceptibility during transport and processing.

Innovation Solution

A method and system that illuminates and images the ends of circular elongated elements using angled cameras, comparing the circumference with an ellipse to determine and quantify axial run out, allowing for contactless measurement and improved accuracy on a μm scale.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a dial indicator is pressed against the rotating glass tube to measure axial run out, then measurement can be performed, but the measuring apparatus is in direct contact with the glass tube causing end damage and abrasion particles

Engineering Contradiction:

Improveaxial run out measurementVSAvoidend damage and abrasion particles

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the mechanical contact measurement system (dial indicator physically touching the glass tube) with an optical measurement system (camera capturing images of the glass tube end). This substitution eliminates mechanical contact, preventing end damage and abrasion particles while maintaining measurement capability through image analysis of the circular pattern.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces an optical intermediary (camera and image processing system) between the measurement function and the glass tube. Instead of direct mechanical contact, the measurement is performed by analyzing the circular pattern captured in images, using light reflection and geometric analysis as intermediaries to obtain axial run out data without physical contact.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If existing brightness comparison methods are used to inspect transparent elements, then defects within the wall can be detected, but axial run out of the end cannot be quantified

Engineering Contradiction:

Improvedefect detectionVSAvoidaxial run out quantification

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent changes the measurement parameter from brightness intensity comparison to geometric shape analysis. Instead of comparing brightness values to detect defects, the system analyzes the circular geometry of the tube end in images, measuring deviations from a perfect circle to quantify axial run out. This parameter change enables precise measurement of end alignment while maintaining defect detection capability.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent transitions from one-dimensional brightness comparison to two-dimensional geometric analysis. By analyzing the circular pattern in the image plane and measuring radial deviations at different angles, the system extracts axial run out information that cannot be obtained through simple brightness comparison, adding a spatial dimension to the measurement.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Stability of the object's composition

If glass tubes are produced with small axial run out, then stability and processability improve, but consistent high quality ends cannot be reliably formed due to process variations

Engineering Contradiction:

Improveglass tube stability and processabilityVSAvoidend quality consistency

Core Design Contradiction:

Stability of the object's compositionVSManufacturing precision

Solution Approach 1:

The patent implements a feedback mechanism by measuring the actual axial run out of produced glass tubes using the optical system and using this information to adjust and optimize the end formation process. The measurement data provides feedback on process variations, enabling continuous improvement and more consistent end quality while maintaining the stability and processability benefits of small axial run out.

Inventive Principle:

Principle #23Feedback

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, contactless quantification of axial run out, reducing fracture susceptibility and improving the quality and processability of circular elongated elements, particularly in pharmaceutical packaging production.

Implementation Method 1

a light source A configured for illuminating the first end; a camera A configured for acquiring one or more image(s) of the first end

Methodology Applied

Scientific EffectReflection: Reflection

Data Source

PatentUS12560421B2Apparatus for the inspection of a circular elongated element

Publication Date: 2026.02.24 SCHOTT AG

AI summary

A bundle includes five or more circular elongated elements. Each circular elongated element includes: a first end; a cylindrical portion defining an outer diameter of the circular elongated element and a rotation axis of the circular elongated element; and a second end. The first end and/or the second end of each circular elongated element fulfills at least one of the following equations: ARO≤A or ARO/OD≤B, where value A is 1.3 mm, ARO is an axial run out in mm of the first end and/or the second end of the respective circular elongated element, value B in mm/mm is 0.1, and OD is the outer diameter in mm of the respective circular elongated element.