Laser Print Quality Evaluation Using Image Histogram Fitting
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Solution Overview
Problem
Current methods for evaluating the quality of laser printing on compression moulded plaques made of polyolefin compositions lack objectivity and quantifiability, relying on visual inspection which is not reproducible.
Innovation Solution
A method involving digital image capture, Gaussian curve fitting, and automatic analysis of intensity distributions to objectively and quantitatively assess the quality of laser prints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If visual detection by human eye is used to inspect laser printed samples, then the inspection process is simple and requires no complex equipment, but the evaluation of print quality is not objective and quantitative, leading to non-reproducible results
Solution Approach 1:
The patent replaces the mechanical/visual inspection system (human eye) with an optical-digital system. A digital camera captures images of the laser-printed samples, and computer software automatically analyzes the images to quantify print quality metrics such as contrast, sharpness, and defect detection. This substitution transforms subjective visual evaluation into objective, reproducible numerical measurements.
Solution Approach 2:
The patent introduces a digital image processing system as an intermediary between the laser-printed sample and the evaluation process. The digital camera acts as an intermediary that converts optical information from the sample into digital data, which is then processed by algorithms to extract quality metrics. This intermediary layer enables automated, quantitative analysis while maintaining simplicity in the overall system architecture.
2Adaptability or versatility
If conventional printing techniques like ink jet or embossing are used, then the printing process is simple and well-established, but they are not suitable for moulded articles with non-planar surfaces or insufficient outer surface area
Solution Approach 1:
The patent changes the fundamental parameter of the printing process from contact-based (ink jet, embossing) to non-contact energy application (laser). By using laser radiation, the system can print on complex, non-planar surfaces without requiring physical contact or surface flatness. The laser parameters (power, speed, pulse duration) can be adjusted to accommodate different geometries and material types, providing high adaptability while maintaining manufacturing efficiency.
3Productivity
If laser printing is used to mark moulded articles, then higher line speed can be achieved increasing cost-efficiency and the print cannot be easily erased, but the contrast between dark carbon black filled moulded article and light marking needs optimization
Solution Approach 1:
The patent implements a feedback system where digital images of the laser-printed samples are captured and analyzed by computer software. The system automatically evaluates print quality metrics including contrast, sharpness, and uniformity. This feedback loop allows for real-time monitoring and adjustment of laser parameters to maintain optimal print quality at high line speeds, ensuring that contrast requirements are met without sacrificing productivity.
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
Provides a reproducible and quantitative evaluation of laser print quality, enabling consistent comparison and identification of good and deficient settings.
Implementation Method 1
providing a digital image of the laser printed part of the laser printed sample
Implementation Method 2
laser printing techniques... a laser-induced print cannot be erased so easily by rubbing or friction
Implementation Method 3
improving contrast between a dark carbon black filled moulded article and a light marking obtained by laser printing
Data Source
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AI summary
The present invention is directed to a method for quantitative and qualitative evaluation of laser printed samples, the method comprising the following steps: a) providing (S1) a laser printed sample, b) capturing (S2) a digital raster image of the laser printed part of the laser printed sample and thereon providing digital image information that constitutes the digital raster image, c) identifying (S3) at least one distinct part within the digital image information, d) obtaining at least one image histogram for the identified at least one distinct part of the digital image information, e) fitting (S4) a probability density function on the obtained at least one image histogram, and f) determining (S5) at least one parameter of the probability density function.