Veneer Grading Imaging System with Area-Scan Cameras
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Solution Overview
Problem
Existing veneer grading systems using line-scan cameras are prone to errors due to misalignment and slippage, leading to inaccurate composite images and prolonged grading processes.
Innovation Solution
An imaging system employing both black and white and color cameras captures area scans of veneer sheets, eliminating the need for digital stitching and allowing for simultaneous high-speed grading by determining dimensions, voids, and defects, with a controller processing images to assign grades based on reference comparisons and defect detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a line-scan camera is used to capture images of veneer sheets on a conveyor, then the system can operate continuously, but the images require digital stitching which introduces alignment errors and reduces accuracy
Solution Approach 1:
The system divides the imaging task into multiple area-scan cameras positioned at different locations along the conveyor, each capturing a complete area image of the veneer sheet at its respective position, eliminating the need to stitch images together while maintaining continuous operation
Solution Approach 2:
Reference marks are introduced as intermediary elements that are captured in each area-scan image to enable precise alignment and registration of images from different cameras without actual stitching, solving the alignment error problem
2Area of stationary object
If multiple line-scan cameras are used to capture the entire length of veneer sheets, then complete coverage is achieved, but the system becomes complex and error-prone due to synchronization requirements
Solution Approach 1:
The system transitions from line-scan imaging (one-dimensional scanning) to area-scan imaging (two-dimensional capture), allowing complete coverage of the veneer sheet area with fewer cameras and eliminating synchronization complexity between multiple scanning devices
3Measurement precision
If anti-skew devices are used to align veneer sheets before imaging, then alignment is improved, but the process time increases and errors can still occur
Solution Approach 1:
The system captures reference marks and performs digital alignment corrections in advance during the imaging process, eliminating the need for mechanical anti-skew devices and the time they consume while maintaining or improving alignment accuracy
Solution Approach 2:
The patent replaces mechanical anti-skew alignment devices with a digital image processing system that uses reference marks and software-based alignment algorithms, eliminating mechanical intervention and reducing process time
4Productivity
If conveyor slippage is allowed during transport, then the grading process can proceed, but the composite images become inaccurate due to position shifts
Solution Approach 1:
The system uses reference marks captured in each area-scan image as feedback to detect and correct for conveyor slippage and position shifts, allowing continuous operation at high speed while maintaining image accuracy through digital realignment
Data Source
AI summary
A black and white image of a wood product, such as a veneer sheet, is captured with a first camera and a color image of the wood product is captured with a second camera. Computer processing of the black and white image is performed to determine dimensions of the wood product, the existence of voids within the wood product, and the presence of debris on the wood product. Computer processing of the color image is performed to determine whether colored defects are present in the wood product. A grade is assigned to the wood product based on this computer processing. The wood product can then be sorted based on the grade.