Polyester Shrink Film Measurement Using Motion Capture Markers

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Solution Overview

Problem

Existing methods for measuring the heat shrinkage ratio of heat-shrinkable polyester films are inaccurate and difficult to perform quickly, especially for complex-shaped objects like PET bottles, leading to uneven heat distribution and large variations in measured values, and fail to accurately capture the maximum heat shrinkage rate during rapid changes.

Innovation Solution

A method using a motion capture device to measure the heat shrinkage ratio by setting markers at predetermined positions, heating the film under controlled conditions, and calculating the shrinkage ratio using Formula (1) based on the distance change before and after shrinkage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional measurement methods are used to measure heat shrinkage ratio, then the measurement process is simple, but the measurement precision is low and variations in measured values are large

Engineering Contradiction:

Improveheat shrinkage ratio measurement accuracyVSAvoidmeasurement system complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces conventional mechanical measurement methods with an optical measurement system using a motion capture device and markers. This substitution enables non-contact, high-precision measurement of heat shrinkage ratio by tracking marker positions through optical fields, thereby improving measurement accuracy while reducing mechanical interference and variation in measured values.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces markers as intermediary objects attached to the film surface. These markers serve as mediators between the film and the motion capture device, enabling precise tracking of film deformation during heat shrinkage. The markers transform the measurement problem from directly measuring film dimensions to tracking marker positions, which significantly improves measurement precision.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If conventional measurement methods are used, then the equipment is simple, but the measurement speed is slow and cannot capture rapid changes in heat shrinkage

Engineering Contradiction:

Improvemeasurement speedVSAvoidmaximum heat shrinkage rate detection accuracy

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The patent implements continuous measurement by capturing marker positions at multiple time points during the heat shrinkage process. The motion capture device continuously tracks marker movements, enabling real-time measurement of heat shrinkage ratio changes. This continuous measurement approach allows accurate capture of the maximum heat shrinkage rate and rapid changes that occur during heating, significantly improving productivity and measurement speed.

Inventive Principle:

Principle #20Continuity of useful action

Solution Approach 2:

The patent replaces slow mechanical measurement methods with high-speed optical tracking. The motion capture device uses optical fields to track marker positions at high frame rates, enabling rapid capture of heat shrinkage dynamics without the mechanical inertia and response delays inherent in conventional measurement systems.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If markers are attached to measurement positions, then measurement precision improves, but the ease of operation decreases due to additional setup steps

Engineering Contradiction:

Improveheat shrinkage ratio measurement accuracyVSAvoidmeasurement process simplicity

Core Design Contradiction:

Measurement precisionVSEase of operation

Solution Approach 1:

The patent extracts the measurement function from the film itself by attaching separate markers to the film surface. This separation allows the markers to be independently optimized for optical tracking while the film undergoes heat shrinkage. The markers can be positioned at specific measurement locations without interfering with the film's thermal and mechanical properties, thereby maintaining measurement precision while simplifying the overall measurement setup.

Inventive Principle:

Principle #2Taking out (Extraction)

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 quick and accurate measurement of the heat shrinkage ratio with minimal variation, allowing for precise control of heat shrinkage characteristics and reducing the occurrence of wrinkles and color unevenness.

Implementation Method 1

measuring a distance of the predetermined interval after heat shrinkage as L1 by using a motion capture device

Methodology Applied

Scientific EffectMotion capture:

Implementation Method 2

heating the polyester film at a predetermined temperature for a predetermined time as predetermined heat shrinkage conditions to allow the polyester film to undergo heat shrinkage

Methodology Applied

Scientific EffectHeat shrinkage: Thermal Contraction

Data Source

PatentUS20260049811A1Method for measuring thermal shrinkage rate of polyester shrink film

Publication Date: 2026.02.19 C I TAKIRON CORP

AI summary

It is a method for measuring a heat shrinkage ratio of a heat-shrinkable polyester film by using a motion capture device, the method including the following steps (a) to (e). That is, the method includes: step (a) of setting two measurement positions in a main shrinkage direction, and measuring an interval between the two measurement positions as L1; step (b) of attaching markers of an inertial measurement device to the measurement positions; step (c) of heating the film at a predetermined temperature for a predetermined time as predetermined heat shrinkage conditions to cause the film to undergo heat shrinkage; step (d) of measuring the interval between the two measurement positions after heat shrinkage as L′1 by using a motion capture device; and step (e) of calculating a heat shrinkage ratio of the heat-shrinkable polyester film based on a predetermined formula.