Lumber Pitch Detection via Laser Reflection Analysis
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Solution Overview
Problem
Current methods for detecting compression wood, blue stain, and pitch in lumber are not suitable for real-time industrial applications due to their inefficiencies and limitations in accurately identifying these defects at high lumber speeds.
Innovation Solution
A system using laser lines and cameras to measure the intensity of diffusely reflected light, with image processing techniques such as thresholding and conversion to HSI color space, allows for the detection of compression wood, blue stain, and pitch by analyzing the intensity and slope of light reflection across the wood surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If microscopy methods are used to identify compression wood areas, then detection accuracy is improved, but real-time detection capability is lost
Solution Approach 1:
The patent replaces mechanical microscopy methods with an optical detection system using laser lines and cameras. The system projects laser lines onto the lumber surface and captures reflected light images, eliminating the need for physical sectioning and microscopy while enabling real-time detection at industrial speeds up to 2500 fpm.
Solution Approach 2:
The patent creates optical copies (images) of the lumber surface by capturing reflected laser light with cameras. These digital images serve as substitutes for physical microsections, allowing compression wood areas to be identified through image analysis without requiring actual physical sampling or sectioning.
2Measurement precision
If thin cross section transmission imaging is used to identify compression wood, then detection accuracy is improved, but applicability to real-time industrial settings is lost
Solution Approach 1:
The patent replaces the mechanical process of cutting thin cross sections with a non-contact optical system. Laser lines are projected onto the surface of whole lumber pieces, and cameras capture images of the reflected light, eliminating all mechanical sectioning operations while maintaining detection accuracy.
Solution Approach 2:
The system performs detection on the surface of whole lumber before any processing or sectioning occurs. By detecting compression wood areas on intact boards using optical methods, the system enables real-time identification without requiring preliminary cutting or preparation steps.
3Reliability
If traditional detection methods are used for blue stain and pitch, then detection capability is provided, but efficiency and accuracy are insufficient
Solution Approach 1:
The patent creates a universal detection system that can identify multiple defect types (compression wood, blue stain, and pitch) using the same optical hardware platform. By analyzing different characteristics of reflected laser light, the system provides multi-functional detection capability without requiring separate specialized equipment for each defect type.
Solution Approach 2:
The patent detects different defect types by analyzing changes in optical parameters of reflected light. Compression wood areas show different reflectivity patterns compared to sound wood, while blue stain and pitch areas exhibit distinct optical characteristics. By monitoring these parameter changes in the reflected light intensity and distribution, the system efficiently identifies multiple defect types simultaneously.
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 accurate and efficient detection of compression wood, blue stain, and pitch in real-time, improving the ability to identify and quantify these defects in lumber, correlating well with traditional methods and allowing for robust measurement normalization.
Implementation Method 1
A light beam is projected towards the wood sample. Line or area cameras acquire images of light that is reflected from the wood sample. Based on the intensity of the reflected light at one or more locations on the wood sample, compression wood, blue stain, or pitch may be detected.
Data Source
AI summary
Methods are provided for detecting compression wood, blue stain, or pitch in lumber. A light beam is projected towards the wood sample. Line or area cameras acquire images of light that is reflected from the wood sample. Based on the intensity of the reflected light at one or more locations on the wood sample, compression wood, blue stain, or pitch may be detected.